Formulation for forming the surface layer of a composite material

ES 2 209 182 T3

DESCRIPTION

Use of a photocatalytic composition to remove harmful substances from the air.

The present invention relates to the use of a composite material containing a photocatalyst that functions as a catalyst when exposed to light to remove nitrogen oxides, ammonia, carbon monoxide and / or sulfur oxides from the air.

Photocatalysts that can function as catalysts when exposed to light are finding more and more applications because the energy used in catalytic reactions is light energy, for example sunlight, which is inexhaustible. For example, titanium dioxide (TiO2), a type of photocatalyst, especially titanium oxide in crystalline anatase form, produces excitation electrons and positive holes when exposed to the energy of light (ultraviolet light) and electrons from excitation and positive gaps give rise to active oxygen species, for example O₂^-, OR^- and · ΟΗ (in which · indicates an unpaired electron and means that the species marked with · is a radical species), in the presence of oxygen and water on the surface of the catalyst. Applications that draw on the radical properties of the active oxygen species have been proposed, for example air purification applications, in which nitrogen oxides (NOx) in the air are oxidized with the active oxygen species and then converted into a harmless reaction product (nitric acid) and the degradation of bacteria by oxidation of organic matter, that is, the so-called “anti-microbial” applications.

In the course of the oxidation of nitrogen oxides with the active oxygen species, nitrogen dioxide (NO2) is produced as an intermediate product that undergoes further oxidation and is finally converted into nitric acid. As a result of the production of nitric acid, the amount of nitrogen oxides in the air decreases and the air is purified. For this reason, the co-presence of active oxygen species and nitrogen oxide or nitrogen dioxide is essential to increase the percentage decrease in the amount of nitrogen oxides. But, since nitrogen dioxide is a relatively stable chemical compound (gas), the nitrogen dioxide produced is not affected by the reacting system. This reduces the efficiency of the oxidation with the active oxygen species, which translates into a lower percentage decrease in the amount of nitrogen oxides. The use of porous adsorbents, for example activated carbon, is considered effective in preventing carbon dioxide from being removed from the reactant system. As will be seen from the following description, this method is not always effective.

In particular, when nitrogen dioxide, which had initially been removed, is adsorbed onto the previous adsorbent, after such adsorption the nitrogen dioxide often remains within the pores of the adsorbent, without being released. For this reason, in many cases the adsorbed nitrogen dioxide is placed outside the oxidation system with the active oxygen species and does not undergo the oxidation reaction, therefore it does not become nitric acid as the final oxidation product. This inhibits the decrease in the amount of nitrogen oxides. In this case it should be noted that the nitrogen dioxide adsorbed on the adsorbent in a region in which nitrogen dioxide can be present together with the active oxygen species and is in this reacting system, that is, in a region close to the photocatalyst, where oxidation takes place to produce nitric acid. But, since the region near the photocatalyst occupies only a small proportion of the entire material adsorption region (including pores) of the adsorbent, it can be said that the proportion of nitrogen dioxide, which cannot be oxidized to nitric acid, is elevated. That is, the adsorbent merely adsorbs and retains nitrogen dioxide and the percentage decrease in the amount of nitrogen oxides by conversion to nitric acid does not appear to be satisfactory.

The present invention aims to address the problems just described and an object of the present invention is to continue improving the efficiency of a catalytic reaction in which a photocatalyst participates, or to improve the percentage decrease in the amount of a reagent applied to the reaction. catalytic by converting the reactants into the final product. Another object of the present invention is to supplement the function of a photocatalyst.

The present invention is directed to the use of a composite material consisting of at least a substrate and a surface layer, said surface layer is made hydrophilic and self-washing with water by photoexcitation, said surface layer consists of:

a component (i): a photocatalyst that functions as a catalyst when exposed to light, a component (ii): at least one metal oxide chosen from Al2O3, ZnO, SrO, BaO, MgO, CaO, Rb2O, Na2O, K2O and P2O5 and a component (iii): at least one metal oxide chosen from SiO2, ZrO2, GeO2 and ThO2, to remove nitrogen oxides, ammonia, carbon monoxide and / or sulfur oxides from the air.

Preferred embodiments of the present invention are described in the subclaims.

The composite material used according to the present invention consists of a surface layer that contains a first component, that is, a photocatalyst that functions as a catalyst when exposed to light, a second

ES 2 209 182 T3 component chosen from Al2 O3, ZnO, SrO, BaO, MgO, CaO, Rb2 O, Na2 O, K2 O and P2 O5 and a third component chosen from SiO2, ZrO2, GeO2 and ThO2.

When a reagent that participates in a catalytic reaction, in which a photocatalyst intervenes, undergoes a catalytic reaction and becomes a final product specified by the structure of the reagent and the catalytic reaction; the second component works in the simultaneous presence of the photocatalyst so that the degree of conversion of the reagent in the final product increases.

According to the photocatalytic formulation, which has the above composition, the conversion of the reagent into the final product can be increased, and therefore, the percentage decrease in the amount of the reagent can also be increased.

In the photocatalytic formulation having the above composition, the other compound is a reagent or a compound bound to an intermediate produced before the reagent catalytically reacts and becomes the final product.

The reagent or intermediate is kept in such a state that it is chemically bound to the other compound that has been formulated together with the photocatalyst. This other compound, with the reagent or intermediate product held on it, does not adopt a porous structure. Therefore, the reagent or the intermediate product is not placed outside the catalytic reaction system, in which the photocatalyst intervenes, that is, in a region distant from the photocatalyst, on the contrary, the reagent or the intermediate product is placed inside of the catalytic reaction system together with the photocatalyst that has been formulated together with the other compound. In addition, since the reagent or intermediate is chemically bound to the other compound, the reagent or intermediate can be safely placed within the catalytic reactant system. It follows that the photocatalytic formulation can provide the safe opportunity for the reagent to be applied in the catalytic reaction and the opportunity for the intermediate to be applied in this catalytic reaction. This can further improve the efficiency of the catalytic reaction. The improved efficiency of the catalytic reaction can increase the degree of conversion of the reagent into the final product and consequently increase the percentage decrease in the amount of the reagent.

When exposed to the energy of applied light, the photocatalyst produces excited electrons and positive holes that give rise to active oxygen species in the presence of oxygen and water on the surface of the catalyst.

The reagent or intermediate product is placed within the system of a catalytic reaction based on an active oxygen species produced by the photocatalyst. This gives rise to a certain chance that the reactant will be applied in the catalytic reaction or the chance that the intermediate may continue to be applied in the catalytic reaction. This allows the catalytic reaction to progress more efficiently. Therefore, the percentage decrease in the amount of the reagent is increased.

Examples of viable photocatalysts for this are titanium dioxide (TiO2), zinc oxide (ZnO), vanadium oxide (V2 O5) and tungsten or tungsten oxide (WO3). These photocatalysts are not restricted by their crystalline form and can be present in any crystalline form, for example an anatase, rutile or brookite form, the anatase form of titanium dioxide being preferred from the viewpoint of availability, and so on. Regarding the reagents applicable to the catalytic reaction based on an active oxygen species, the intermediates obtained from the reagents and the final products obtained from the intermediates, for example when the reagent is an oxide of nitrogen, the intermediate product and the final product are nitrogen dioxide and nitric acid, respectively; when the reagent is a sulfur oxide, the intermediate product and the final product are sulfur dioxide and sulfuric acid or sulfurous acid, respectively; and when it is reactive it is carbon monoxide, the intermediate product and the final product are carbon dioxide and carbonic acid, respectively. Furthermore, as an example of a reagent, ammonia may also be mentioned. In this case the intermediate product and the final product are nitrogen monoxide or nitrogen dioxide obtained from ammonia and nitric acid, respectively.

The other compound is the reagent applied in the catalytic reaction, based on an active oxygen species or at least one metal oxide chosen from specific amphoteric metal oxides, basic metal oxides and acid metal oxides that are chemically bound with the intermediate product.

When introducing the reagent or intermediate product into the catalytic reaction system, based on an active oxygen species produced by the photocatalyst, when the reagent or intermediate product is acidic, then the so-called "base point" can formed using a specific atom derived from the atomic arrangement of a basic metal oxide. At this base point, the basic metal oxide can be safely chemically bonded with the reagent or intermediate. When the reagent or intermediate is basic, the so-called "acid point" can be formed using a specific atom derived from the atomic arrangement of an acid metal oxide. At this acid point, the acidic metal oxide can be safely chemically bonded with the reagent or intermediate. Furthermore, when the other compound is an amphoteric metal oxide, a specific atom derived from the atomic arrangement of an amphoteric metal oxide can serve as a base point or an acid point compatible with the properties of the reagent or intermediate. Therefore, even when the reagent or intermediate is a basic compound and an acidic compound, the amphoteric metal oxide can be safely chemically bound with the reagent or intermediate.

ES 2 209 182 T3

Examples of amphoteric metal oxides are alumina (Al2 O3) and zinc oxide (ZnO). Examples of basic metal oxides are strontium oxide (SrO), barium oxide (BaO), magnesium oxide (MgO), calcium oxide (CaO), rubidium oxide (Rb2 O), sodium (Na2 O) and potassium oxide (K2 O). Examples of acidic metal oxides are phosphorous oxide (P2 O5). In these metal oxides, the formation of a base point or an acid point is attributable to the difference in electronegativity between the metal atom and the oxygen atoms that make up the metal oxide and the atomic arrangement of the metal atom and the atom atom. oxygen on the surface of the metal oxide. Basic metal oxide, acid metal oxide and amphoteric metal oxide can be chosen correctly according to the reagent to be applied in the catalytic reaction based on the active oxygen species and the intermediate product obtained from the reagent. It is clear that when zinc oxide is chosen as the photocatalyst, zinc oxide should not be chosen as the amphoteric metal oxide, because zinc oxide is a photocatalyst and, at the same time, an amphoteric metal oxide.

As an example to explain the progress of the catalytic reaction and the union using alumina, a system will be taken here in which the photocatalyst is titanium dioxide, the other compound is alumina as amphoteric metal oxide and the reactant is nitrogen oxide (monoxide nitrogen). In this case, nitrogen monoxide is oxidized with an active oxygen species produced by titanium dioxide, forming nitrogen dioxide as an intermediate product. As shown schematically in Figure 1, when nitrogen monoxide comes into contact with or approaches titanium dioxide that acts as a photocatalyst, nitrogen monoxide is oxidized with ΟΗ (hydroxy radical) which is an active species of oxygen produced by titanium dioxide exposed to light, forming nitrogen dioxide (gas) (figure 1 (a)). As is clear from the molecular structure, nitrogen dioxide is acidic and alumina is an amphoteric metal oxide, with an oxygen atom thereof acting as a base point for an acid gas. Thus, nitrogen dioxide is attracted to and chemically binds to the oxygen atom and is retained on alumina (Figure 1 (b)). The force, with which nitrogen dioxide is attracted to oxygen atoms, is a coulombic force and the bond is chemical.

Nitrogen dioxide bound to the oxygen atom of alumina is together with titanium dioxide, which acts as a photocatalyst, and therefore is within the system of an oxidation reaction (a catalytic reaction) induced by a hydroxy • OH radical (figure 1 B)). This provides a safe opportunity for nitrogen dioxide to be oxidized by the hydroxy • OH radical and allows the oxidation of nitrogen dioxide to progress efficiently. Nitrogen dioxide is considered to be oxidized to form nitrate ions which, together with the hydrogen atom of the hydroxy • OH radical, bind and remain in the form of nitric acid (final product) on the oxygen atom, which acts as a point base, of alumina (figure 1 (c)).

If nitrogen dioxide is originally present, that is, when nitrogen dioxide is the reactant, then nitrogen dioxide is oxidized directly by the action of an active oxygen species produced by titanium dioxide and, at the same time, the Nitrogen dioxide chemically bonded to alumina in the manner just described is also oxidized with the active oxygen species. In other words, in this case, the nitrogen dioxide as the reagent is chemically bound to the alumina.

The following explains the bonding using alumina, in the case where sulfur monoxide (SO) and carbon monoxide (C) are oxidized with an active oxygen species produced by titanium dioxide. With oxidation, these oxides are converted into sulfur dioxide and carbon dioxide, that is to say, acid gases are produced here again. For this reason, as shown schematically in figure 2, sulfur dioxide is chemically bound to oxygen atoms, which are the base points that alumina has as an amphoteric metal oxide and points adjacent to it. , and remain on the alumina. As shown schematically in Figure 3, in the case of carbon dioxide, the carbon atom and the oxygen atom can join in different bond orders. Therefore, carbon dioxide is chemically bound to a single oxygen atom that acts as a base point already indicated above (figure 3 (a)) or oxygen atoms that act as a base point and adjacent to it (figure 3 (b)) and are held on the alumina. In this case, the sulfur dioxide bound and held on the alumina in this way reacts subsequently with an active oxygen species (hydroxy radical • OH) produced by the titanium dioxide, giving rise to sulfuric acid or sulfurous acid (final product ), while carbon dioxide is converted to carbonic acid (end product). Carbon dioxide is also considered to be converted to methane or methanol by a reaction based on a radical hydrogen atom, produced at the time of the formation of the hydroxy radical • OH as an active oxygen species, and into active species of oxygen. In this case, methane or methanol can be considered end products.

According to a first preferred embodiment, the other compound is formulated so that the value of a / (a ​​+ b) is between 0.0001 and 0.8, in said formula "a" means the weight of the other compound and "B" means the weight of the photocatalyst.

When the value of a / (a ​​+ b) is not less than 0.0001, as specified in the first preferred embodiment, the other compound (amphoteric metal oxide, basic metal oxide or acid metal oxide) represented by "a" it can advantageously ensure that the chemical bonding of the reagent or intermediate does not impair the efficiency of the catalytic reaction. When the value of a / (a ​​+ b) is not greater than 0.8, it is advantageous that the amount of the photocatalyst represented by "b" is not too small in relation to the other compound, so that depletion can be advantageously avoided. of the efficiency of the catalytic reaction.

In this case, the amount of photocatalyst can be between 20 and 95% by weight, a percentage referred to the

ES 2 209 182 T3 total amount of photocatalyst, above compound as a mixing ingredient other than the photocatalyst and the other ingredient (s), if any.

According to the second preferred embodiment, the photocatalyst and the other compound are regulated and formulated in a particle size comprised between 0.005 and 0.5 µm.

When the particle size or diameter of the photocatalyst and the particle diameter of the other compound (amphoteric metal oxide, basic metal oxide, or acid metal oxide) are in a range of 0.005 to 0.5 μ / m, as specified In the second preferred embodiment, the regulation of the particle diameter can advantageously be carried out by means of a grinding device, for example a ball mill, or by means of a sol-gel process. Furthermore, according to the second preferred embodiment, there is no significant difference in the particle size of the photocatalyst and the other compound, since the particles of the photocatalyst and the particles of the other compound, which have diameters similar to those of the particles of the photocatalyst, are close to each other. Therefore, the other reagent or intermediate chemically bound to the other compound can be brought closer to the photocatalyst. This advantageously secures the opportunity for the catalytic reaction to progress, experiencing an improvement in efficiency.

Apart from the photocatalyst and the other compound, the photocatalyst formulation also consists of a third component which is a compound to which the hydroxyl group can chemically bind and which chemically adsorbs and fixes the hydroxyl group on the surface of the photocatalyst and this compound acts as a third component, whereby the attached hydroxyl group develops hydrophilicity.

The hydroxyl group, produced by catalytic reaction, in which the photocatalyst participates, is chemically adsorbed and remains on the surface of the compound as a third component, let alone the photocatalyst. Also, there is no possibility that the amount of water (water vapor in the air, rainwater, etc.) on the surface of the catalyst is zero. Therefore, it can be said that the hydroxyl group will always be produced when there is exposure to light. This allows the hydroxyl group to be fixed at a high density by chemical adsorption bonding, so that the hydroxyl group is firmly attached. On the other hand, during the period when there is no exposure to light, the photocatalyst does not produce hydroxyl groups. But, since the hydroxyl groups produced so far are firmly attached to the surface of the catalyst and of the compound acting as the third component, there is no danger that the hydroxyl group will be accidentally removed. In this case, when the light is reapplied, hydroxyl group fixation occurs again at a high density, even when the hydroxyl density has decreased at that time. Therefore, the fixation of the catalytic formulation on the surface of certain substrates allows the certainty of rendering the surface of said substrate very hydrophilic and this high hydrophilicity can be safely maintained for a long period of time. That is, the photocatalyst formulation can act as a material that imparts high hydrophilicity to the surface of the substrate.

The effects achieved by the hydrophilic nature are described. Hydrophilicity is closely related to the contact angle between the surface of the material and the water. The higher the hydrophilicity, the smaller the contact angle. When the contact angle is small, it is not able to stay on the surface of the material. Therefore, in this case, the dirt deposited on the surface slides together with the water on the surface of the material and falls from said surface. When the hydrophilicity obtained is large enough to have a contact angle less than the contact angle of inorganic dust, for example urban dust that has a high oleophilic content and clay-type minerals, then the dust can be removed without resorting to affinity. In addition, as the contact angle approaches 0 °, the hydrophilicity increases and the water diffuses in the form of a film on the surface of the substrate, facilitating the flow of dirt. Therefore, not only urban dust, but also inorganic dust easily slide along with water on the surface of the substrate. In this case, the contact angle is preferably below 20 ° and close to 0 ° from the point of view of increasing the antifouling or antifouling effect.

Thus, by fixing the photocatalyst formulation on the surface of an interior or exterior wall of a building or the bodywork of vehicles, for example cars or electric trains, the high hydrophilicity thus imparted can result in a intense anti-dirt effect. In this case, when rainwater falls on the surface of the same, by virtue of the great hydrophilicity imparted to the surface thereof, the dust and contaminants deposited on the surface are removed along with the rainwater from said surface whenever the surface is exposed to rain, thereby making the surface self-cleaning. That is, the so-called "rain washed dirt" can be effectively prevented when dust spots or the like are subjected to streams of water. Furthermore, the fixation of the photocatalyst formulation on the surface of glasses, lenses, mirrors, etc., can provide a high "antifogging" (antifogging) effect by virtue of its high hydrophilicity.

The third component compound has a heat of wetting equal to or greater than the photocatalyst. In the case of material with hydroxyl groups present on its surface, the heat of wetting can be considered as an indication of the ability of the surface to retain hydroxyl groups. The higher the heat of wetting, the greater the ability of the surface to retain hydroxyl groups and the higher the density of hydroxyl groups. Thus, the hydroxyl groups produced by the photocatalyst are chemically adsorbed and held at a higher density more effectively in the compound constituting the third component. This can impart high hydrophilicity to the surface of the substrate, with great reliability and over a long period of time. In this case, the heat of wetting of titanium oxide, an especially preferred catalyst, is between 320

ES 2 209 182 T3 and 512 x 10 ^{- 3} Jm ^{- 2} for the anatase form and from 293 to 645 x 10 ^{- 3} Jm ^{- 2} for the rutile form. Compounds having a heat of wetting not less than 500 x 10 are therefore preferred.^-3 Jm^-2 .

The compound that constitutes the third component is at least one metal oxide chosen from SiO2, ZrO2, GeO2 and ThO2.

Since these metal oxides have the heat of wetting equal to or greater than titanium dioxide, which is the especially preferred photocatalyst, the fixing density of the hydroxyl group is advantageously wider. Silica (SiO2), GeO2 and ThO2 are more preferred because their upper limit of heat of wetting exceeds 1000 x 10^-3 Jm^-2 .

Each compound that acts as a third component (SiO2, ZrO2, GeO2 or ThO2) is determined taking into consideration the reagent, whose amount is to be reduced with the present invention and the combination with the other compound (Al2O3, ZnO, SrO, BaO, MgO , CaO, Rb2O, Na2 O, K2O or P2O5) formulated together with the photocatalyst.

According to the third preferred embodiment of the embodiment, in addition to the photocatalyst, the other compound and the compound that acts as a third component, a fourth component of an antimicrobial metal is added and the metal, as the fourth component, is supported in the photocatalyst .

In the fifth preferred embodiment, during exposure to light the antimicrobial activity of the photocatalyst itself is used, while during the period without exposure to light the antimicrobial activity of the metal supported on the photocatalyst is used. In this way the antimicrobial activity of the photocatalyst can be complemented and a synergistic antimicrobial activity can be observed between the antimicrobial metal and the photocatalyst.

According to the fourth preferred embodiment of the invention, the metal constituting the fourth component has a reduction potential not less than the potential of the free electrons emitted by the photocatalyst.

In this fourth preferred embodiment, the metal can be easily supported on the photocatalyst taking advantage of the reduction potential of this metal. In this case, the metal is preferably at least one element chosen from silver, copper, palladium, iron, nickel, chromium, cobalt, platinum, gold, lithium, calcium, magnesium, aluminum, zinc, rhodium and ruthenium, because they have the previous reduction potential. Silver, copper, palladium, platinum and gold are especially preferred because they have a positive reduction potential and therefore reduction deposition of the metal can be easily carried out. The metal chosen as the fourth component is preferably formulated so that it meets the c / d value of 0.00001 to 0.05, in said formula "c" means the weight of the metal and "d" means the weight of the photocatalyst. That is, when the metal used as the fourth component has a c / d value greater than 0.00001, then there is no possibility that the amount of metal, because it is so small, displays a synergistic antimicrobial activity, while when the metal used As the fourth component it has a c / d value less than 0.05 (= c / d), there is no possibility that the amount of metal is excessive and negatively affects the catalytic reaction of the photocatalyst.

Material containing a photocatalyst that functions as a catalyst when exposed to light can be mixed or dispersed in a paint or enamel.

As a material containing a photocatalyst, the paint or enamel having the above constitution can increase the percentage decrease in the amount of the reagent or make it easier for the reagent or intermediate product to be safely introduced into the catalytic reaction system. Therefore, the amount of the reagent can be effectively lowered on a surface coated with a paint or on a surface on which an enamel has been applied. Furthermore, on these surfaces, the opportunity to apply the reagent in the catalytic reaction and the opportunity for the intermediate product to also apply in the catalytic reaction can be ensured, allowing the catalytic reaction to progress more efficiently.

In this case, the paints and varnishes, in which components (i), (ii) and (iii) are mixed or dispersed, can be conventional paints and varnishes. In the case of an enamel, the components of (i) to (iii) are dispersed together with the enamel raw material, for example a feldspar or potassium carbonate frit, in a solution. By dispersing and mixing the components from (i) to (iii), they can be formulated together with the enamel raw material during the manufacture of said enamel. Alternatively, they can be formulated and added to the final enamel prior to its application.

When the material containing the photocatalyst is a paint or an enamel, the following advantage can be obtained.

Depending on the material containing the photocatalyst, the reagent or intermediate can be safely fixed and maintained at the base point or acid point and the reagent or intermediate can be placed within the catalytic reaction system based on an active species. of oxygen. This allows the catalytic reaction to progress more efficiently on the paint-coated surface than the material containing the photocatalyst or a surface on which an enamel has been applied, which in turn increases the percentage decrease in the amount of paint. reagent. Furthermore, in the material containing the photocatalyst, a high anti-fouling effect (antifouling) based on the high hydrophilicity can be achieved with advantage on these surfaces. Furthermore, in the material that con6

ES 2 209 182 T3 has the photocatalyst, when photocatalyst formulations are used which carry a metal as the fourth component specified in the third and fourth preferred embodiments of the photocatalyst formulation, then on these surfaces an activity synergistic antimicrobial between antimicrobial metal and photocatalyst.

In the material containing the photocatalyst, used according to the present invention, especially paint, the paint can form a coating of material containing the photocatalyst on the interior or exterior walls of architectural masses, for example buildings, houses and bridges and structures. such as railings and sound insulation panels along highways. Furthermore, these structures can be easily modified so that with a significant decrease in the amount of the reagent a great antifouling effect is achieved.

The surface layer of the composite material can have a geometry that satisfies any of the following requirements (1) and (2):

(1) thickness of the surface layer: from 0.01 to 3.0 μιη and (2) the color difference, ΔΞ, of the surface layer before and after ultraviolet irradiation of said surface layer, which has been deposited a 1% silver nitrate solution for 5 min with an ultraviolet intensity on the surface layer of 1.2 mW / cm², is between 1 and 50.

By virtue of the compound used as the third component, the surface layer has a reduced contact angle and better hydrophilicity that allows it to generate a great antifouling effect. When the thickness of the layer is greater than 0.01 μm, the layer (surface layer) is not too thin, and it is advantageous in that the contact angle of the surface layer itself can be safely used as the contact angle. of the material. In particular, even if the substrate has a large contact angle, the surface layer arranged on the substrate can reduce the contact angle of the material. Therefore, the material can display a great antifouling effect. On the other hand, when the thickness of the surface layer is less than 3.0 µm, then the adhesion of the surface layer to the substrate can be maintained. This can advantageously prevent separation of the surface layer (separation layer). This is true if the compound is used as the third component combined with the metal acting as the fourth component.

Silver ions from the silver nitrate solution deposited on the surface layer are reduced and precipitated to form a color, as a result of receiving excited electrons from the photocatalyst in the excited state as a result of exposure to ultraviolet light. Therefore, a color difference ΔE is observed between the state before ultraviolet irradiation and the state after ultraviolet irradiation of the surface layer. The greater the number of excited electrons that are produced, the greater the color difference ΔΞ. The amount of excited electrons produced is a factor that regulates the photoactivity of the photocatalyst. This allows the photocatalytic activity to be evaluated based on the color difference ΔΞ. The excited electron from the photocatalyst produces active oxygen species, for example the hydroxy • OH radical, in air. Therefore, the higher the photocatalytic activity, that is, the greater the color difference ΔΞ, the greater the amount of active oxygen species, for example the hydroxy · OH moiety.

The compound that constitutes the third component of the surface layer acts to retain the hydroxy • OH radical produced by the excited electron of the photocatalyst. The greater the number of hydroxy · OH radicals that are produced, the greater the density of hydroxyl groups on the surface of the compound that constitutes the third component. This provides a smaller contact angle with the water and thus can increase hydrophilicity. Furthermore, the greater the number of hydroxy · OH radicals produced, the greater the amount of organic compounds that decompose. This is advantageous with a view to hydrophilicity. Therefore, when the surface layer has a color difference ΔE greater than 1, it will have a photocatalytic activity large enough to form a high density of hydroxyl groups. This will safely and advantageously reduce the contact angle of the surface layer to a low enough level to provide an antifouling effect. On the other hand, when the amount of photocatalyst, based on the binder, per unit area increases, then the color difference ΔΞ also increases. In this case it is considered that the adhesion to the substrate is reduced causing the separation of the surface layer. For this reason and from the point of view of preventing separation of the surface layer, a surface layer having a color difference ΔE of less than 50 is preferred.

The photocatalyst activatable material may contain a binder.

The binder is preferably one that is polymerized or melts below a temperature, at which the quality of the material of the substrate layer changes, to bind the photocatalyst formulation on the surface of the substrate layer, or alternatively enamel or paint is preferable.

According to a preferred embodiment of the present invention, the surface layer contains TiO2 as a photocatalyst and, in addition, Al2O3, SiO2 and an antimicrobial metal.

In photocatalytically activatable materials, having the structure defined above, on the surface of the surface layer arranged on the substrate layer, the percentage decrease in the amount of the reagent can be increased and the reagent or intermediate can be safely placed within the reacting system

ES 2 209 182 T3 catalytic. Therefore, on the surface of the surface layer of the photocatalytically activatable material, the amount of reagent can be effectively lowered, and at the same time, the opportunity to apply the reagent in the catalytic reaction and the opportunity to also apply the intermediate product can be ensured. in the catalytic reaction, allowing the catalytic reaction to progress more efficiently. Furthermore, since the surface layer contains an antimicrobial metal, a synergistic antimicrobial activity between the antimicrobial metal and the photocatalyst can be advantageously realized in said layer.

According to the present invention, the reagent or intermediate can be safely attached and held together at the base point or at the acid point and the reagent or intermediate can be placed in the catalytic reagent system, based on the active oxygen species. . This allows the catalytic reaction to progress more efficiently over the surface of the surface layer in the photocatalytically activatable material, which in turn results in an increase in the percentage decrease in the amount of the reagent. Furthermore, in photocatalytically activatable materials, a great antifouling effect can be carried out with advantage on these surfaces, based on a great hydrophilicity. On the other hand, in photocatalytically activatable materials, when photocatalyst formulations are employed or the photocatalyst-containing materials further contain a metal as the fourth component specified in the third and fourth preferred embodiments of the photocatalyst formulation, then it can be advantageously achieved on said surfaces a synergistic antimicrobial activity between the antimicrobial metal and the photocatalyst.

In the photocatalytically activatable materials used in accordance with the present invention, the following preferred embodiments may be adopted.

The substrate layer can contain a substrate chosen from among ceramics, resins, metals, glass, pottery materials, wood, calcium silicate boards, concrete boards, cement boards, extruded cement boards, plasterboard boards, and concrete boards. lightweight autoclaved concrete.

According to this preferred embodiment, the photocatalytically activatable material can act photocatalytically at the sites where these substrates are used, for example interior and exterior walls of architectural masses, for example buildings, houses and bridges and roads and decomposes environmental pollutants, for example nitrogen oxides, sulfur oxides and carbon dioxide, thus purifying the air. In addition, the photocatalytically activatable material can display a great antifouling effect based on the great hydrophilicity of the interior and exterior walls of buildings, roads, etc.

The surface layer can be formed by heat treatment, for example in an oven. According to this embodiment, a surface layer can be formed strongly adhering to the substrate layer.

An antimicrobial metal or metal compound can be anchored on the surface of the surface layer. According to this embodiment, during exposure to light, the antimicrobial activity of the photocatalyst itself is used in the surface layer, while during the period without exposure to light, the antimicrobial activity of the metal or metal oxide anchored on it is used. the surface of the surface layer. The antimicrobial activity of the photocatalyst can therefore be supplemented. In addition, since the surface layer contains the other compound described above, apart from the photocatalyst, the surface layer will be able, in addition to performing an antimicrobial action, decompose environmental pollutants and purify the air, improving the efficiency of the catalytic reaction in which the photocatalyst. Furthermore, a great antifouling effect can be achieved on these surface layers, based on a high hydrophilicity. On the other hand, in photocatalytically activatable materials, when photocatalyst formulations or materials containing photocatalyst are used with the metal that constitutes the fourth component, supported in the previous one, synergistic antimicrobial effects can be obtained with advantage thanks to the metal that acts as the fourth component. . Thus the amount of metal or metal compound anchored on the surface of the surface layer can be minimized. Furthermore, when the synergetic antimicrobial activity displayed by the metal constituting the fourth component is high, the anchoring of the metal or the metal compound on the surface of the surface layer can be dispensed with.

(1) The composite material manufacturing process can consist of the following stages:

providing a photocatalyst formulation or a dispersed sol of photocatalyst formulation in which said formulation is dispersed;

spreading layers of photocatalyst formulation or dispersed sol of photocatalyst formulation on the surface of the substrate layer (layer spreading step) and forming the surface layer.

In this case, the dispersed sol of photocatalyst formulation can be obtained by dispersing the photocatalyst formulation in a liquid, for example water or an alcohol.

This process does not require special stages. Consequently, a new photocatalytically activatable material can be easily produced which, as described above on the occasion of the photocatalyst formulation, allows the reagent or intermediate product to be safely placed in the catalytic reactant system, thereby

ES 2 209 182 T3 a highly efficient catalytic reaction takes place in the surface layer. In this case, in forming the surface layer, appropriate methods, for example heat treatment or drying treatment, may be adopted depending on the layered photocatalyst formulation or the dispersed sol of the photocatalyst formulation.

When the layering step involves caulking, coating, or stamping the photocatalyst formulation or dispersed sol of photocatalyst formulation onto the surface of the substrate layer to form a layer of photocatalyst formulation or dispersed sol of photocatalyst formulation, then the following advantages are obtained.

In particular, a new photocatalytically activatable material can be easily manufactured, containing a photocatalyst formulation and capable of generating a highly efficient catalytic reaction on a surface layer having a substantially uniform thickness. When the formation of a layered coating is contemplated, the spreading of the photocatalyst formulation layers on the surface of the substrate layer can be carried out with a suitable coating method, for example spray painting, whereas in case of desire the formation of a layered pattern, the spreading of the photocatalyst formulation layers on the surface of the substrate layer can be carried out by a suitable embossing method, for example roll embossing.

(2) Another process may consist of the following stages:

providing a photocatalyst formulation or a dispersed photocatalyst formulation sol bearing the dispersed photocatalyst formulation;

layering a binder on the surface of the substrate layer to form the binder layer;

spreading layers of the photocatalyst formulation or photocatalyst formulation dispersed sol on the surface of the binder layer; and heat treating the above assembly according to the properties of the binder to obtain the surface layer.

In this process, the surface layer can be formed on the surface of the binder layer so that, at the interface between the binder layer and the surface layer, the photocatalyst formulation of the surface layer is embedded and fixed in the layer of binder. This allows the surface layer to be firmly anchored onto the binder layer and, at the same time, effectively contact the photocatalyst formulation. with the outside air. In addition, a new photocatalytically activatable material can be provided which, as mentioned above on the occasion of the photocatalyst formulation, the reagent or intermediate product is safely placed within the catalytic reactive system, allowing the catalytic reaction to take place with great efficiency in the surface layer.

In this case, when the surface layer is formed using enamel as binder, the heat treatment is carried out at a temperature of 30 to 300 ° C above the softening temperature of the enamel and below the temperature at which the quality of the substrate constituting the substrate layer is altered. Heating temperature at least 30 ° C above the softening temperature of the binder (enamel) is advantageous because an unnecessarily long period of time is not required to soften the enamel by heating. Furthermore, since the heating temperature is not more than 300 ° C above the softening temperature of the enamel, rapid melting of the enamel can be prevented and the occurrence of unfavorable phenomena, for example excessive fouling of the enamel formulation, can be prevented. photocatalyst, the formation of an uneven surface or the formation of craters (pinholes). Furthermore, as the surface layer is formed, it is preferred to carry out the heat treatment at a temperature of 150 to 1300 ° C. This allows a conventional heating device to be used in the manufacture of the new photocatalytically activatable material that produces a catalytic reaction with great efficiency. The heat treatment temperature of 150 ° C or higher is commensurate with the heat treatment temperature of conventional enamels, dispensing with the need to use heat treatment conditions that are different from those of the prior art. In addition, when the heat treatment temperature is 1300 ° C or lower, the temperature is in accordance with the heat treatment temperature used in the substrate that requires such treatment, for example in the manufacture of tiles and ceramic articles, omitting the need to change heat treatment conditions.

When the surface layer is formed using a paint as a binder, the heat treatment can be carried out below the temperature at which the quality of the substrate constituted by the substrate layer is altered. This advantageously allows the formation of the surface layer without altering the quality of the substrate.

In the above processes (1) and (2), the stage of formation of the surface layer can be followed by the stage of coating with a solution containing an antimicrobial metal or a metallic compound dispersed in it on the surface of the surface layer. and the step of anchoring the metal or metal oxide on the surface of the surface layer.

In the process of producing a photocatalytically activatable material according to this embodiment, a new photocatalytically activatable material can be easily manufactured in which the surface layer can display antimicrobial activity regardless of whether the material is exposed to light or is held in place. darkness and, furthermore, in

ES 2 209 182 T3 the surface layer takes place a very efficient catalytic reaction. On the other hand, regardless of whether the material is placed under conditions of exposure to light or in conditions of darkness, its ability to display antimicrobial activity derives from the fact that the surface layer is formed by a photocatalytically activatable material.

In the previous processes (1) and (2), the stage of spreading layers can consist of:

spreading layers of the photocatalyst formulation or dispersed sol of photocatalyst formulation and then coating with a solution containing an antimicrobial metal or a metal compound dispersed therein and the step of forming the surface layer consists, simultaneously with the formation of the surface layer, in anchoring the metal or metal oxide on the surface of the surface layer.

In the process of manufacturing a photocatalytically activatable material according to this embodiment, a new photocatalytically activatable material can be easily manufactured which has, from the outset, both the ability to display antimicrobial activity regardless of whether the material is placed under exposure conditions to light or in dark conditions, and the property of generating a catalytic reaction with great efficiency.

In the above processes (1) and (2), the stage of formation of the surface layer can be followed by the stage of coating with an aqueous solution of a metal salt containing antimicrobial metal ions on the surface of the surface layer. and the step of exposing the surface layer to ultraviolet light to photoreduce the metal ions of the photocatalyst, whereby the metal is supported and fixed on the photocatalyst of the surface layer.

In the process of manufacturing a photocatalytically activatable material according to this embodiment, a new photocatalytically activatable material can be easily manufactured which, in the surface layer, can display antimicrobial activity, regardless of whether the material is placed under exposure conditions. light or dark conditions, and at the same time, it can develop a catalytic reaction in the surface layer very effectively. In addition, a metal, which helps to supplement the antimicrobial activity, is supported and fixed on the photocatalyst of the surface layer by photoreduction and thus is unlikely to separate from the photocatalyst. Consequently, the property of complementing antimicrobial activity can be maintained for a long period of time. Furthermore, regardless of whether the material is placed in light or dark conditions, this property of displaying antimicrobial activity can be derived from the fact that the surface layer is formed on the photocatalytically activatable material. When the photocatalyst formulation is used with the metal constituting the fourth component supported thereon, then the metal constituting the fourth component can also develop synergistic antimicrobial activity. Thus, the amount of metal supported on the surface of the surface layer can be minimized by coating an aqueous solution of a metal salt and subsequent ultraviolet irradiation. Furthermore, when the synergistic antimicrobial activity of the metal constituting the fourth component is high, then the step of supporting the metal on the surface of the surface layer can be omitted.

(3) Another process may consist of the following steps: providing a dispersed sol of photocatalyst formulation;

mixing the dispersed sol of the photocatalyst formulation with an aqueous solution of a metal salt having antimicrobial metal ions and supporting the metal, which constitutes the fourth component, on the photocatalyst.

(4) Another process may consist of the following stages:

providing the dispersed photocatalyst sol with an aqueous solution of a metal salt containing antimicrobial metal ions, co-precipitating the metal salt and the photocatalyst formulation, and supporting the metal, which constitutes the fourth component, on the photocatalyst.

(5) Another process may consist of the following stages:

providing a dispersed photocatalyst sol containing, dispersed therein, at least one photocatalyst chosen from the photocatalyst, the other compound and the compound constituting the third component; ^Y mixing the dispersed photocatalyst sol with an aqueous solution of a metal salt containing antimicrobial metal ions and then irradiating the mixture with ultraviolet light to photoreduce the metal ions, thereby supporting the metal, which constitutes the fourth component, on the photocatalyst .

In these processes from (3) to (5) to manufacture a photocatalyst formulation, a new photocatalyst formulation can be easily manufactured which, in the surface layer formed with the photocatalyst formulation, can display antimicrobial activity, regardless of whether the material it is situated in light conditions or in dark conditions and, at the same time, it can very effectively cause a catalytic reaction in the surface layer. Also in process (3), what is needed to support and previously fix the metal, which helps to complement

The antimicrobial activity on the photocatalyst is simply mixing the dispersed sol of the photocatalyst with the aqueous solution of a metal salt. This can simplify the process. Furthermore, in processes (4) and (5), coprecipitation or photoreduction is carried out to support and previously fix a metal, which can complement the antimicrobial activity, on the photocatalyst. By virtue of its constitution, the metal is unlikely to separate from the photocatalyst, allowing its ability to supplement antimicrobial activity to be maintained over a long period of time. Furthermore, in process (5), what is required to support and fix the metal is simply to apply ultraviolet light and the use of chemicals or the like is not required at all. This can simplify the process.

In the processes from (3) to (5) of manufacturing a photocatalyst formulation, the dispersed sol of the photocatalyst can be a sol that contains, dispersed inside, both the photocatalyst, the other compound and the compound that constitutes the third component, that is, a sol containing the photocatalyst formulation dispersed within it. Furthermore, the other compound and the compound constituting the third component can be dispersed in the dispersed sol of the photocatalyst after the metal has been supported. On the other hand, when the photocatalyst formulation should be powdery for reasons of storage convenience or the like, the sol containing, dispersed inside, the photocatalyst can be dried, together with the metal, which constitutes the fourth component, supported on the same, the other compound and the compound that constitutes the third component.

Figure 1 is a schematic diagram that, during the oxidation of nitrogen oxides with titanium dioxide as a photocatalyst, illustrates the progress of the catalytic reaction and the state of fixation of an intermediate product, produced by the catalytic reaction, on alumina, in the case where alumina is formulated together with titanium dioxide;

Figure 2 is a schematic diagram that, during the oxidation of sulfur oxides with titanium dioxide as a photocatalyst, illustrates the state of fixation of an intermediate product, resulting from the catalytic reaction, on alumina in the event that the alumina together with titanium dioxide;

Figure 3 is a schematic diagram that, during the oxidation of carbon monoxide with titanium dioxide as a photocatalyst, illustrates the progress of the catalytic reaction and the state of fixation of an intermediate product, resulting from the catalytic reaction, on the alumina in the case where alumina is formulated together with titanium dioxide;

Figure 4 is a schematic block diagram of a test apparatus used to determine the effect of reducing the amount of nitrogen oxides in the case of tiles according to the first example;

Figure 5 is a graph showing the results of a test on the effect of reducing the amount of nitrogen oxides in the case of tiles according to the first example;

Figure 6 is a graph showing the results of a test on the effect of reducing the amount of ammonia in the case of tiles according to the first example;

Figure 7 is a graph showing the results of a test on the effect of reducing the amount of sulfur oxides in the case of the tiles of the first example;

Figure 8 is a graph showing the results of a test on the effect of reducing the amount of nitrogen oxides in the case of the tiles of the first example;

Figure 9 is a graph showing the results of a test on the effect of reducing the amount of nitrogen oxides in the case of the tiles of the first example;

Figure 10 is a graph showing the results of a test on the antimicrobial effect in the case of the tiles of the third example;

Figure 11 is a graph that presents the relationship between c / d (proportion of metals in the formulation), in which c means the weight of a metal supported on the tiles of the example (baked type) of a four-component system according to the sixth example and d means the weight of TiO2 supported, and the antimicrobial activity;

Figure 12 is a graph that represents the relationship between c / d (proportion of metals in the formulation), in which c means the weight of a metal supported on the tiles of the example (painted type) of a four-component system according to the sixth example and d means the weight of TiO2 supported on the tiles, and the antimicrobial activity;

Figure 13 is a graph showing the relationship between the thickness of a surface layer and the contact angle under conditions of exposure to light in the case of the tiles of a four-component system (baked type) according to the sixth example;

Figure 14 is a graph showing the relationship between the thickness of the surface layer and the antimicrobial activity in the case of the tiles of a four-component system (baked type) according to the sixth example;

Fig. 15 is a graph showing the relationship between the thickness of the surface layer and the oil degradation activity in the case of tiles of a four-component system (baked type) according to the sixth example;

Figure 16 is a graph showing the relationship between the thickness of the surface layer and the NO oxidation activity in the case of tiles of a four-component system (baked type) according to the sixth example;

Figure 17 is a graph showing the relationship between the thickness of the surface layer and the contact angle under conditions of exposure to light in the case of tiles of a three-component system (baked type) according to the seventh example;

Fig. 18 is a graph showing the relationship between the color difference ΛΗ and the contact angle under conditions of exposure to light in the case of tiles of a four-component system (painted type) according to the sixth example;

Figure 19 is a graph showing the relationship between the color difference ΔE and the antimicrobial activity in the case of tiles of a four-component system (painted type) according to the sixth example;

Fig. 20 is a graph showing the relationship between the color difference ΔE and the oil degradation activity in the case of tiles of a four-component system (painted type) according to the sixth example;

Figure 21 is a graph showing the relationship between the color difference ΔE and the NO oxidation activity in the case of tiles of a four-component system (painted type) according to the sixth example; and Fig. 22 is a graph showing the relationship between the color difference ΛΗ and the contact angle under conditions of exposure to light in the case of tiles of a three-component system (painted type) according to the seventh example.

The embodiments of the present invention are described below with reference to the following examples.

The following composite materials are used in accordance with the present invention:

- the tiles of example 4 (four-component system)

- the tiles of example 5 (three-component system)

- the tiles of example 6 (four-component system)

- the tiles of example 7 (three-component system)

- tiles 4, 7, 8, 1 1-13 and 16-18 of example 8

- the tiles of example 9 (three-component system)

The other tiles are reference tiles or comparative tiles.

The manufacture of catalyst formulations used in the following examples is now described. Titanium dioxide (anatase form) is used as the photocatalyst. The metal oxides used are alumina as amphoteric metal oxide and strontium oxide and barium oxide as basic metal oxides.

Photocatalyst formulations are prepared by the following steps.

(i) Supply of the photocatalyst and metal oxide particles

The starting materials of titanium dioxide, alumina, strontium oxide and barium oxide are purchased. They are pulverized by a grinding device, for example a ball mill, or subjected to a sol-gel process. In this way, fine particles of titanium dioxide, alumina, strontium oxide and barium oxide are obtained. In this case, the size regulation is carried out so that the particles of the compounds have a diameter between 0.005 and 0.5 µm.

(ii) Preparation of the sun

Next, the formulation materials prepared in the above manner are dispersed in a solvent, for example water or an alcohol, to obtain a sol of each formulation material. In this case the amount of material to be dispersed in each sol is specified (for example, the weight of the formulation material per volume of solvent).

(iii) Preparation of photocatalyst formulations

The titanium dioxide sol (photocatalyst sol) prepared in the above manner is then mixed with a metal oxide sol, that is, an alumina sol, a strontium oxide sol or a barium oxide sol.

ES 2 209 182 T3

In this way a mixed sol of titanium dioxide and alumina (Ti / Al sol), a mixed sol of titanium dioxide and strontium oxide (Ti / Sr sol), a mixed sol of titanium dioxide and oxide are obtained. of barium (sol of Ti / Ba). For the manufacture of the mixed sols, the photocatalyst sol and the metal oxide sol are weighed and mixed sols with various formulation ratios between the photocatalyst and the metal oxide are manufactured by varying the heavy amount of photocatalyst sol to be mixed and the amount of metal oxide sol to be mixed. Specifically, mixed sols are prepared by varying the formulation ratio defined by a / (a ​​+ b) (the quotient "a / (a ​​+ b)" will be called hereinafter "formulation ratio"), in which "a "Means the weight of the metal oxide of each mixed sun and" b "means the weight of the photocatalyst of each mixed sun.

Apart from steps (i) to (iii), alumina particles, etc., which have been regulated to the desired particle size, can be added and dispersed in the photocatalyst sol to make a Ti / Al sol, etc. . Furthermore, the photocatalyst particles, which have been regulated to a desired particle size, and the alumina particles, etc., can be alternately or simultaneously dispersed in the solvent to make a Ti / Al sol, etc., the particles being photocatalyst and alumina, etc., originally dispersed therein.

The photocatalytically activatable materials having photocatalytic activity are described below using the photocatalyst formulations (Ti / Al mixed sol, Ti / Sr mixed sol and Ti / Ba mixed sol) obtained in this way. In the first example, tiles are used as the photocatalytically activatable material, which are manufactured as follows.

An unglazed tile is supplied as a substrate. On the surface of the tile, each of the mixed suns having a specified concentration is projected with a gun. In the spray gun, the application time is regulated, so that the thickness of the photocatalyst layer on the surface of the tile is 0.85 μm after oven drying. The tiles that have been spray-coated with the mixed sols are dried in an oven at a certain temperature, taking into account the melting temperature of the silica, etc., formulated to fix the photocatalyst and the melting temperature of titanium dioxide and each metal oxide (around 800 ° C in this example), for 60 min. In this way, photocatalytically activatable final materials are obtained that consist of a surface layer containing the neutral materials of the sun (photocatalyst and alumina, etc.), arranged on the surface of the substrate (tile). These photocatalytically activatable materials are evaluated as follows. The evaluation is carried out in terms of the effect of reducing the amount of nitrogen oxides, ammonia and sulfur dioxide that it is desired to reduce to harmless materials in the air or in the room. The evaluation trials are briefly described. To begin with, a test to evaluate the decrease in the case of nitrogen oxides is described. It should be noted that, instead of spraying, centrifugation, immersion, etc., can obviously be adopted for coating the mixed sun.

(1-1) Evaluation test 1

Effect of alumina, etc., in reducing the amount of nitrogen oxides

For comparison with the products of the examples, a photocatalytically activatable tile is prepared as follows using a photocatalyst formulation containing neither alumina, strontium oxide nor barium oxide, with only titanium dioxide being formulated therein (a comparative tile) and photocatalytically activatable tiles are prepared according to the examples (example tiles). The comparative tile is prepared by gunning a photocatalyst sol having a titanium dioxide content of 7.5% by weight on its surface and oven drying the coated tile under the conditions mentioned above (800 ° C for 60 min). For gunning, gunning time etc. are determined so that the weight of titanium dioxide on the tile surface after oven drying is 3.3 x 10^-4 g / cm² (thickness of the titanium dioxide layer: approx. 0.85 μm). The example tiles are Ti / Al tiles, Ti / Sr tiles and Ti / Ba tiles.

The Ti / Al tile is prepared by spraying a Ti / Al sol having a titanium dioxide content of 7.5% by weight and a proportion of alumina formulation regulated at 1/1 1 in terms of the proportion of formulation a / (a ​​+ b) (a Ti / Al sol with a weight ratio between titanium dioxide and alumina of 0.1) in the same way as just described on the occasion of the comparative tile and the coated tile is dried in the oven in the same way as described above in relation to the roof tile. comparison. Ti / Sr tile is manufactured by spray coating it with a Ti / Sr sol containing titanium dioxide and strontium oxide in the same formulation ratio as described above for the Ti / Al tile and kiln drying the coated tile in the same way described above in relation to the comparative tile. The Ti / Ba tile is manufactured in the same manner as described above. The comparative tile has only titanium dioxide on its surface and displays a catalytic activity that is taken as a comparison standard. Therefore, the comparison of the comparative tile with each of the tiles in the examples reveals whether or not an improvement in catalytic activity is achieved by formulating the metal oxide and the degree of improvement. The comparative tile consists of a tile that is coated with a surface layer consisting solely of titanium dioxide. On the other hand, each of the tiles in the examples consists of a tile covered by a surface layer formed by a formulation of titanium dioxide and alumina or strontium oxide or barium oxide.

The comparative tile and the example tiles are checked as follows. For the test, a specimen having a side size of 10 cm is used, both for the comparative tile and for the tiles of the examples. The effect of reducing the amount of nitrogen oxides is measured for each specimen in a tester, which is represented in FIG. 4. In this tester, a cylinder 12 filled with nitrogen monoxide

ES 2 209 182 T3 gaseous of a constant concentration is introduced countercurrent to a glass cell 10, hermetically sealed, which contains the test piece. NO gas from cylinder 12 is mixed with air that has been sucked in by an air pump 14 and adjusted to the desired humidity by a humidity controller 15, through a flow control valve 16. NO gas (test gas) having a predetermined concentration (0.95 ppm) flows at a constant flow rate (1 liter / min) through the flow control valve 16 and enters the glass cell 10. It is countercurrently introduces a concentration meter (NOx sensor) 18 into the glass cell 10 to measure the concentration of nitrogen oxides in the gas passing through the cell. The NOx sensor 18 is designed in such a way that at all times it measures the NO concentration and the nitrogen dioxide concentration (NO2 concentration) and the sum of both concentrations is indicated as the nitrogen oxide concentration (NOx concentration). The measuring apparatus is equipped with a lamp 20 which emits ultraviolet light (wavelength 300 to 400 nm) projecting it onto the glass cell 10. The lamp 20 is switched on in a controlled way, so that the intensity of the ultraviolet light on the test piece is 1.2 mW / cm² . The specimen is placed in the glass cell 10 of the test apparatus, that is, it is placed in an environment exposed to ultraviolet radiation. For both the comparative tile and the example tiles, the NO2 concentration and the NOx concentration are plotted against the time elapsed since the start of the test gas pass. The results are shown in Figure 5. Lamp 20 is not turned on until the NOx concentration (NO concentration) stabilizes on the outlet side after the start of the test gas pass.

In evaluation test 1, if the nitrogen monoxide oxidation reaction does not take place, for example, if the glass cell 10 is placed in a dark room so that no active oxygen species is produced by the carbon dioxide. titanium from the surface layer and to generate a catalytic reaction, the test gas is passed through the NOx sensor 18 without causing any reaction. Therefore, in this case, the NOx sensor 18 output is identical to the test gas concentration (CNO / input) for the NO concentration (CNO / output), the NO2 concentration (CNO2 / output) is zero , the NOx concentration (CNOx / outlet) being equal to the CNO / outlet, that is, it is identical to the CNO / inlet. However, when NO is oxidized in a catalytic reaction based on the active oxygen species produced by titanium dioxide in the surface layer, the NO concentration is reduced from CNO / input by the amount of NO that has been oxidized. Furthermore, when NO2 is produced by oxidation of NO and released from the tile surface, the NO2 concentration increases by the amount of NO2 released. The degree of reduction in the amount of NOx is determined by the relationship between the decrease in the NO concentration due to NO oxidation and the increase in the NO2 concentration due to the release of the NO2 formed on the surface of the tile.

As shown in Figure 5, for the comparative tile, the NOx concentration decreases rapidly from the start of the test. After about 5 min from the start of the test, the NOx concentration rises and approaches the test gas concentration. Furthermore, for the comparative tile, the NO2 concentration increases gradually from the start of the test and, 30 min after the start of the test, reaches a value of 0.18 ppm. The NOx concentration and the NO2 concentration increase substantially in the same way. This indicates that, for the comparative tile, the photocatalytic reaction of the titanium dioxide in the surface layer consists in oxidizing the NO, resulting in a reduced concentration of NO. In this case, an increase in the NO2 concentration inhibits the decrease in the amount in all NOx. Therefore, for the comparative tile, since NO2 is released from the tile surface, any further oxidation of NO2 on the tile surface will not be significant. The NOx concentration 30 min after the start of the test is 0.66 ppm and, therefore, the decrease in the amount of NOx in the comparative tile is 30.5% ((0.95-0.66) / 0.95).

On the other hand, for the tiles in the examples, that is, the Ti / Al tile, the Ti / Sr tile and the Ti / Ba tile, and for the comparative tile, the NOx concentration decreases rapidly from the start. of the essay. Afterwards, the NOx concentration is kept slightly higher than the minimum concentration. Furthermore, for the tiles in the examples, the NO2 concentration does not increase significantly after the start of the test and, even after 30 min from the start of the test, is as low as 0.05 ppm. From these facts it can be said firstly that, for the tiles of the examples, the photocatalytic reaction produced by the titanium dioxide in the surface layer progresses to oxidize the NO, resulting in a lower concentration of NO. In addition, NO2 binds to alumina, strontium oxide and barium oxide and therefore is not relatively released from the tile surface and further oxidation of NO2 by titanium dioxide actively progresses so the NO2 concentration does not increase. For this reason, for the example tiles, the amount of NOx can be lowered with very high efficiency. The NOx concentration 30 min after the start of the test is 0.45 ppm and, therefore, the decrease in the amount of NOx in the tiles of the examples is 52.6% ((0.95-0, 45) / 0.95), that is, essentially twice the value obtained with the comparative tile. The test is continued with the tiles of the examples. As a result, it is found that the high decrease in the amount of NOx is maintained. The test ends 12 h after the start of the test. The surface of the tiles in the examples is washed with water and the washing liquid is analyzed to discover the materials it contains. As a result, the presence of nitric acid is confirmed.

Furthermore, all the tiles in the examples have an excellent surface, without unacceptable irregularities. It is carried out in a sliding abrasion test using a plastic abrasive according to the JIS A 6808 standard. As a result, all the tiles in the examples, after performing the alternating sliding 40 times, the surface layer does not suffer neither deterioration nor separation , indicating that it has excellent resistance to abrasion. This means that the photocatalyst formulation, obtained by mixing sols in the manner described above, can be applied not only to kiln-dried paints and enamels, but also to printing binders, etc., which have to be kiln-dried. On the other hand, the photocatalyst formulation and the photocatalytically activatable material that

ES 2 209 182 T3 can greatly reduce the amount of nitrogen oxides thanks to the photocatalytic activity, they can be manufactured by mixing sols, in the manner described above.

(1-2) Evaluation test 1

Effect of alumina, etc., in reducing the amount of ammonia

In the case of ammonia, the decrease in the quantity produced by the comparative tile, the Ti / Al tile and the Ti / Sr tile is also investigated using the same apparatus and method that have been described above for nitrogen oxides. In this case, the test gas passing through the glass cell 10 contains 4 ppm of gaseous ammonia. The concentration of ammonia in the gas, which passes through the cell, is measured with a concentration meter (a gas detector tube) placed upstream of the cell. For the comparative tile and for the tiles of the examples (Ti / Al tile and Ti / Sr tile), the ammonia concentration is plotted against the time elapsed since the start of the test gas pass. The results are shown in Figure 6.

As can be seen in Figure 6, both for the comparative tile and for the tiles of the examples, the ammonia concentration decreases from the beginning of the test. Over time, the example tiles provide a lower concentration of ammonia than the comparative tile. 10 min after the start of the test, the tiles show substantially constant ammonia concentrations in all cases. Specifically, the ammonia concentration is 3.5 ppm for the comparative tile, 2.5 ppm for the Ti / Al tile and 2.6 ppm for the Ti / Sr tile. The decrease in the amount of ammonia was 12.5% ​​((4-3.5) / 4) for the comparative tile, 37.5% ((4-2.5) / 4) for the Ti tile / Al and 35% ((4-2.6) / 4) for the Ti / Sr tile. From these facts, it is evident that, for the comparative tile, the photocatalytic reaction due to titanium dioxide in the surface layer progresses to effect the chemical conversion of ammonia to NO, NO2 etc., reducing the amount of ammonia to a certain extent, while In the two example tiles, the Ti / Al tile and the Ti / Sr tile, the decrease in the amount of the amount of ammonia is greater than that of the comparative tile. The reason for such fact is believed to be the following.

If the reaction to convert ammonia to other compounds (chemical reaction) does not take place, the test gas enters the gas detector tube without causing any reaction. In this case, the measured value of the ammonia concentration is identical to that of the test gas. However, when ammonia undergoes a catalytic reaction based on active oxygen species generated by titanium dioxide in the surface layer and is converted to other compounds, the ammonia concentration decreases from the ammonia concentration in the test gas at the amount of ammonia that has been converted to other compounds. For this reason, both for the comparative tile and for the tiles of the examples, the ammonia concentration decreases immediately after the start of the test. In this case, since ammonia reacts catalytically with an active oxygen species, the nitrogen that constitutes ammonia is oxidized, giving NO and NO2 as intermediates. It is considered that, as mentioned above, NO is oxidized to NO2 by the oxygen-active species and NO2 undergoes further oxidation by the active oxygen species which chemically converts it to nitric acid, resulting in a more extensive chemical conversion of ammonia to NO and to NO2. NO2 thanks to the catalytic reaction of ammonia based on the active oxygen species, which can amplify the decrease in the amount of ammonia.

The tiles in the examples are different from the comparative tile in that, as mentioned above, they have been formulated with alumina or strontium oxide, which are bonded with NO2 to prevent NO2 from being released from the surface of the tile. In the case of the comparative tile, the NO2 produced from the ammonia escapes from the surface of the tile and, for this reason, there is no place for a subsequent oxidation of the NO2 by the active oxygen species, so that no further oxidation of NO2 by the active oxygen species to chemically convert NO2 to nitric acid progresses significantly. On the other hand, for the tiles of the examples, the NO2 generated from the ammonia does not escape from the surface of the tiles and this allows the subsequent oxidation of the NO2 into nitric acid by the action of the active oxygen species. For this reason, for the example tiles, as explained above, the decrease in the amount of the amount of ammonia is amplified. This is considered to be due to the superiority in reducing the amount of ammonia caused by the tiles of the examples compared to that achieved by the comparative tile.

(1-3) Evaluation essay 1

Effect of alumina, etc., in reducing the amount of sulfur dioxide

Also for sulfur dioxide, the decrease in the quantity caused by the comparative tile and by the Ti / Al tile is investigated using the same apparatus and method that have been described above for nitrogen oxides. In this case, the test gas passes through the glass cell 10 with 10 ppm of sulfur dioxide gas. The concentration of sulfur dioxide in the gas, which passes through the cell, is measured with a concentration meter (a gas detector tube) arranged counter-current with respect to the cell. For the comparative cell and for the example tile (Ti / Al tile), the sulfur dioxide concentration is plotted against the time elapsed since the start of the test gas passage. The results are shown in Figure 7.

It is observed in figure 7 that, both for the comparative tile and for the tile of the example, the concentration of sulfur dioxide decreases from the beginning of the test. As time passes, the example tile provides a lower concentration of sulfur dioxide than the comparative tile. 30 minutes after the start of the test, the

ES 2 209 182 T3 sulfur dioxide concentration is 7.7 ppm for the comparative tile and 2.7 ppm for the Ti / Al tile. Therefore, the decrease in the amount of sulfur dioxide is 23% ((10-7.7) / 10) for the comparative tile and 73% ((102.7) / 10) for the Ti / To the. From these facts it is evident that, for the comparative tile, the catalytic reaction caused by titanium dioxide in the surface layer progresses to produce the chemical conversion of sulfur dioxide into sulfuric acid, sulfurous acid, etc., decreasing the amount of carbon dioxide. sulfur to some extent, while for the Ti / Al tile (tile in the example), the decrease in the amount of sulfur dioxide is more pronounced than that achieved with the comparative tile. The reason for this fact is believed to be as follows.

The reason why, both in the case of the comparative tile and the tile in the example, the concentration of sulfur dioxide decreases is that, as in the case of nitrogen monoxide and ammonia, sulfur dioxide undergoes a Catalytic reaction based on an active oxygen species, generated by titanium dioxide in the surface layer, and converted into sulfuric acid or sulfurous acid. In this case, the sulfur dioxide concentration decreases from the sulfur dioxide concentration of the test gas to an amount of sulfur dioxide that is oxidized to other compounds. Sulfur dioxide is, as a reactant, an acid gas. Therefore, as explained in relation to Figure 2, sulfur dioxide, which is the reagent in this evaluation test, is chemically bound and adsorbed on alumina which is a basic metal oxide. For this reason, in the case of the comparative tile, which lacks alumina, the sulfur dioxide is oxidized with the active oxygen species and is chemically converted into sulfuric acid or sulfurous acid, in a state such that it is not adsorbed on the surface of the tile. On the other hand, in the example tile, sulfur dioxide is oxidized with the active oxygen species and becomes sulfuric acid or sulfurous acid, in such a state that it is adsorbed on the surface of the tile. This facilitates the reaction. For this reason, for the example tile, as mentioned above, the decrease in the amount of sulfur dioxide is amplified. This is considered to be the superiority in reducing the amount of sulfur dioxide by the example tile over the comparative tile.

The relationship between the proportion of alumina, etc., which is formulated together with the photocatalyst, and the effect of reducing the amount of nitrogen oxides, is then evaluated with the following two methods. This evaluation is carried out taking alumina as an example.

(2) Evaluation test 2

Effect of the proportion of alumina formulated in reducing the amount of nitrogen oxides - part 1

In order to compare the products according to the examples, a comparative tile and the photocatalytically activatable tiles of the examples (tiles of the examples) are purchased at the start, which are similar to those used in evaluation test 1. The comparative tile is manufactured by spray coating it with a photocatalyst sol having a titanium dioxide content of 7.5% by weight on its surface and oven drying the coated tile under the conditions indicated above (800 ° C for 60 min. ). In spray application, the spray period, etc., are determined so that the weight of titanium dioxide on the surface of the tile after oven drying is 3.3 x 10^-4 g / cm² (thickness of the titanium dioxide layer: 0.85 μm). The example tile is the following Ti / Al tile.

The Ti / Al tile is manufactured by spray coating it with a photocatalyst sol having a titanium dioxide content of 7.5% by weight, which is the same as that of the comparative tile, and a formulation proportion of alumina regulated between 0.0001 and 0.8 in terms of formulation ratio a / (a ​​+ b) and drying it in the oven in the manner already described above for the comparative tile. Specifically, several Ti / Al tiles are kiln dried so that the weight of titanium dioxide on the surface of the tiles after drying is identical to that of the comparative tile, i.e. 3.3 x 10^-4 g / cm² while varying the weight of alumina on the surface of the tiles after oven drying. These Ti / Al tiles are used as example tiles in evaluation test 2. When the formulation ratio a / (a ​​+ b) is 0.01, a = b / 99. Therefore, in this case, the weight of the alumina on the tile surface after oven drying is 3.3 x 10^-6 g / cm². On the other hand, when the formulation ratio a / (a ​​+ b) is 0.5, then a = b. Therefore, in this case, the weight of the alumina on the tile surface after oven drying is 3.3 x 10^-4 g / cm². Also in this evaluation test 2, given that the comparative tile displays a standard catalytic activity, the comparison between the comparative tile and the Ti / Al tiles with a variable amount of formulated alumina reveals the effect of the amount of formulated alumina in improving the catalytic activity when the amount of photocatalyst is identical.

In this evaluation test 2, the same test apparatus is used as in evaluation test 1 and, 30 min after the start of the test, that is, the time between the start of the flow of a test gas that has At a predetermined concentration (0.95 ppm) with a constant flow rate and the start of lighting of the lamp 20, the concentration of NO2 and NOx is measured for both the comparative tile and the tiles of the example. For each of the tiles, the amount of NOx removed, determined by subtracting the measured value of the NOx concentration from the NO concentration of the test gas, and the measured value of the NO2 concentration, are graphically recorded. The results are shown in Figure 8. For the comparative tile, since it lacks alumina at all, the formulation ratio a / (a ​​+ b) is zero.

In Figure 8, the results of the comparative tile (a / (a ​​+ b) = 0) are graphically recorded on the Y axis. It can be seen in Figure 8 that, for the comparative tile, the NO2 concentration is 0.17 ppm, while the amount of NOx removed is 0.3 ppm. The reason why, despite having decreased the NOx concentration to a value lower than the NOx concentration of the test gas, the presence of non-gas NO2 is detected

ES 2 209 182 T3 test is that, as indicated above, the photocatalytic reaction due to titanium dioxide proceeds in the surface layer and NO2 escapes from the surface of the tile.

On the other hand, in the case of the Ti / Al tile whose formulation ratio a / (a ​​+ b) is represented on the X coordinate axis, when the amount of formulated alumina is small, that is, the formulation ratio a / (a + b) is 0.01, the NO2 concentration is 0.15 ppm, while the amount of NOx removed is 0.4 ppm. For the Ti / Al tile, in which the amount of alumina formulated is identical to that of titanium dioxide, that is, the formulation ratio a / (a ​​+ b) is 0.5, the NO2 concentration is 0.14 ppm, while the amount of NOx removed is 0.43 ppm. For the Ti / Al tile in which the formulation ratio a / (a ​​+ b) is 0.05 to 0.2, the NO2 concentration is 0.06 to 0.13ppm, while the amount of NOx removed is 0. , 44 to 0.46 ppm. Therefore, if checked against the comparative example, these Ti / Al tiles provide a much lower NO2 concentration and remove a much higher amount of NOx. Also in the case of the Ti / Al tile, in which the formulation ratio a / (a ​​+ b) is 0.0001, the results (NO2 concentration = 0.155 ppm; amount of NOx removed = 0.36 ppm) are similar to those of a Ti / Al tile in which the formulation ratio a / (a ​​+ b) is 0.01. The results obtained with this Ti / Al tile are not plotted because the X-axis coordinate points for the Ti / Al tile are hitting zero.

As can be seen from these facts, when the formulation ratio a / (a ​​+ b) is between 0.0001 and 0.5, the alumina formulation can prevent NO2 from escaping from the tile surface, achieving a greater decrease in the amount of NO2 and, in turn, a greater decrease in the amount of NOx than the comparative tile. A formulation ratio a / (a ​​+ b) within the range of 0.05 to 0.2 is especially preferred because a much greater decrease in the amount of NOx is achieved than with the comparative tile. Furthermore, even when the amount of formulated alumina is very small, that is, when the formulation ratio a / (a ​​+ b) is 0.0001, a large decrease in the amount of NOx can be achieved.

In addition, Ti / Al tiles with a variable a / (a ​​+ b) formulation ratio have a good surface and have excellent abrasion resistance.

(3) Evaluation test 3

Effect of the proportion of alumina formulated in reducing the amount of nitrogen oxides - part 2

In this evaluation test 3, the total amount of titanium dioxide as photocatalyst and alumina (the sum of the amounts of both materials in the formulation) is constant and the ratio between titanium dioxide and alumina is varied to examine the effect. which has this variation in decreasing the amount of nitrogen oxides.

At the initial moment, to compare the products of the examples, it is sought to have a comparative tile and photocatalytically activatable tiles of the examples (tiles of the examples), similar to those used in the evaluation example 1. The comparative tiles are identical to the comparative tiles used in evaluation test 2, and the weight of titanium dioxide on the surface of the tile after oven drying is 3.3 x 10^-4 g / cm². A simple tile (a tile that does not have photocatalytic activity) is prepared using a formulation that only contains alumina without any photocatalyst, in it the weight of alumina on the surface of the tile is 3.3 x 10^-4 g / cm². The following Ti / Al tiles are prepared as example tiles.

Ti / Al tiles are manufactured by applying a Ti / Al sun coating with a spray gun, with a total amount of titanium dioxide and alumina that is the same as in the comparative tile, that is, 7.5% by weight. , and having an alumina formulation ratio regulated between 0.05 and 0.95 in terms of formulation ratio a / (a ​​+ b), in the same way as described above in connection with the comparative tile and by oven drying the coated tiles in the manner described above on the occasion of the comparative tile. Specifically, several Ti / Al tiles are kiln dried in which the weight of titanium dioxide on the surface of the tile after kiln drying decreases from 3.3 x 10^-4g / cm² as the weight of alumina increases. These Ti / Al tiles are used as example tiles for evaluation test 3. When the formulation ratio a / (a ​​+ b) is 0.05, a + b equals the previous value of 3.3 x 10^-4 g / cm². In addition, the weight "a" of alumina on the surface of the tile after oven drying is 1.65 x 10^-5g / cm², while the weight "b" of titanium dioxide is 3.135 x 10^-4 g / cm². On the other hand, when the formulation ratio a / (a ​​+ b) is 0.95, the weight "a" of the alumina is 3.135 x 10^-4 g / cm², while the weight "b" of titanium dioxide is 1.65 x 10^-5 g / cm². Also in this evaluation test 3, given that the comparative tile has a standard catalytic activity, the comparison between the comparative tile and the Ti / Al tiles with amounts of titanium dioxide and alumina formulated in a variable way shows that the effect of the amount of titanium dioxide and alumina formulated in improving the catalytic activity.

In evaluation test 3 the same test apparatus is used as in evaluation test 1, and the concentration of NO2 and the amount of NOx removed are recorded graphically, in the same way as in evaluation test 2. The Results are collected in Figure 9. For the comparative tile, since it does not contain alumina at all, the formulation ratio a / (a ​​+ b) is zero. For the tile that does not present any type of photocatalytic activity, since it does not contain titanium dioxide at all, the formulation ratio a / (a ​​+ b) is 1.

In figure 9 the results of the comparative tile (a / (a ​​+ b) = 0) are graphically recorded on the Y axis of the graph. It follows from figure 9, for the comparative tile, that the NO2 concentration is 0.17 ppm, while

ES 2 209 182 T3 the amount of NOx removed is 0.3 ppm. The reason why the presence of NO2 not belonging to the test gas is detected despite the decrease in the NOx concentration to a value lower than the NOx concentration in the test gas, has been described above on the occasion of the Evaluation test 2. For the simple tile, which does not have photocatalytic activity, the results are graphically recorded on the X axis of coordinates of the graph. From the graph it appears that both the NO2 concentration and the amount of NOx removed are obviously zero.

On the other hand, for the Ti / Al tile, whose formulation ratio a / (a ​​+ b) is indicated on the X coordinate axis of the graph, when the amount of formulated alumina is small, that is, the formulation ratio a / (a ​​+ b) is 0.05, the NO2 concentration is 0.07 ppm, while the amount of NOx removed is 0.46 ppm. For the Ti / Al tile, whose amount of formulated alumina is greater than that of formulated titanium dioxide and the formulation ratio a / (a ​​+ b) is 0.8, the NO2 concentration is 0.13 ppm , while the amount of NOx removed is 0.32 ppm. For the Ti / Al tile, whose formulation ratio a / (a ​​+ b) is between 0.05 and 0.65, the NO2 concentration is between 0.07 and 0.09 ppm, while the amount NOx removed is between 0.43 and 0.52 ppm. Therefore, when compared to the comparative tile, these Ti / Al tiles provide a much lower NO2 concentration and a much higher amount of NOx removed. For the Ti / Al tiles, whose formulation ratio a / (a ​​+ b) is 0.9 or higher, the NO2 concentration and the amount of NOx removed are not greater than those obtained in the case of the comparative tile.

It follows from the above facts that, when the formulation ratio a / (a ​​+ b) is between 0.0001 and 0.8, and the total amount of titanium dioxide and alumina is kept constant, the alumina formulation It can prevent NO2 from escaping from the surface of the tile, achieving a greater decrease in the amount of NO2 and, in turn, a greater decrease in the amount of NOx than the comparative tile. A formulation ratio a / (a ​​+ b) between 0.05 and 0.6 is especially preferred because a much greater decrease in the amount of NOx is achieved than with the comparative tile. When the formulation ratio a / (a ​​+ b) is less than 0.0001 or greater than 0.8, the decrease in the amount of NOx is similar to that achieved with the comparative tile. However, especially when the formulation ratio a / (a ​​+ b) is greater than 0.9, the amount of titanium dioxide as a photocatalyst is so small that the titanium dioxide particles are completely surrounded by particles. of alumina, without leaving any loophole. This situation is believed to prevent light from striking the titanium dioxide, resulting in a decrease in photocatalytic activity.

Furthermore, if the Ti / Al tiles with a variable formulation ratio a / (a ​​+ b) also have a good surface and have excellent abrasion resistance.

In the first example, the anatase form of titanium dioxide is used as the photocatalyst and as the metal oxide to be formulated together with the photocatalyst, alumina is used, as amphoteric metal oxide, and strontium oxide and barium oxide, as oxides. basic metallic. However, reducing the amount of NOx can obviously also be achieved by using other photocatalysts in combination with other metal oxides. For example, with regard to titanium dioxide as a photocatalyst, the crystalline form can also be rutile or brookite. In addition, the use of photocatalysts such as ZnO, V2 O5, WO3, SnO2, SrTiO3, Bi2 O3 and Fe2 O3 also reduces the amount of NOx. On the other hand, the effect of reducing the amount of NOx can be achieved by using zinc oxide and tin oxide (amphoteric metal oxides) and magnesium oxide, calcium oxide, rubidium oxide, sodium oxide and potassium oxide (metal oxides basic) instead of alumina, strontium oxide and barium oxide, as metal oxides. When the gas, whose quantity is to be reduced, is a basic gas, phosphorous oxide (acid metal oxide) can be used in addition to the amphoteric metal oxides.

The second example is described below. In this example, the process of forming the surface layer of a photocatalyst formulation, which consists of a photocatalyst, for example titanium dioxide, and a specific metal oxide, for example alumina, disposed on the surface of the tile is different from that of from the first example. In this second example, a substrate is first prepared on which a surface layer will be formed. The substrates that can be used for this are ceramic materials, resins, metals, glasses, pottery materials, wood, calcium silicate boards, concrete boards, cement boards, extruded cement boards, plasterboard boards and lightweight concrete boards. autoclave. In the event that the substrate is to be used in architectural structures, for example buildings, houses and bridges, and in acoustic protection panels next to motorways, the amount of environmental pollutants, for example nitrogen oxides, can be reduced with advantage. system of such architectural structures to purify the air.

A binder layer is then formed on the surface of the substrate. To form the binder layer, a binder material is chosen which has a softening temperature below the temperature, at which the quality of the substrate is altered. The binder layer is formed using the binder material chosen by a suitable method, compatible with the properties of the binder. For example, when the binder is a tile, a glaze or a pottery material, an enamel layer or a patterned layer can be used as a binder layer to apply the colors etc. on the surface. Once the binder is formed, a photocatalyst formulation is formed that subsequently serves as a surface layer, for this it is coated or stamped with a sol, for example a Ti / Al sol in the first example, on the surface of the binder layer , or a mixture of titanium dioxide particles with alumina, obtained by removing the solvent from the sol, is applied. Alternatively, a photocatalyst formulation layer can be formed on a separately prepared binder layer and subsequent mounting of the binder layer on the surface of the substrate. What is required here is that the photocatalyst formulation layer is formed on top of the binder layer in such a way that these two layers do not separate from each other when subsequent oven drying is carried out.

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Accordingly, when the binder layer is formed from an enamel layer, the heat treatment is carried out in an environment having a temperature of 30 to 300 ° C above the softening temperature of the binder material (enamel ) and below the temperature at which the quality of the substrate is altered. Heat treatment allows the binder material (enamel) to melt and solidify. As a consequence, the binder layer is firmly fixed on the surface of the tile and, at the same time, a surface layer is formed consisting of a photocatalyst formulation. In this case, at the border between the surface layer and the binder layer, particles of photocatalyst formulation (particles of titanium dioxide and alumina particles) are deposited on the surface layer of the binder layer during the melting of the binder material. The particles are embedded and held in the binder layer and this allows the surface layer to firmly fix on the binder layer. Furthermore, in the photocatalyst formulation layer, adjacent particles are bonded together by inter-particle intermolecular force and by sintering during oven drying to form the surface layer. In this surface layer, titanium dioxide particles and alumina particles are exposed on the surface of said layer. This allows the surface layer to be firmly fixed on the binder layer and, at the same time, allows the titanium dioxide particles and the alumina particles to effectively come into contact with the outside air. Therefore, in the process according to the second example, materials of architectural structures etc. having a surface layer capable of inducing a photocatalytic reaction with high efficiency can be easily manufactured.

In this case, the heating temperature of at least 30 ° C above the softening temperature of the binder material is advantageous because a large dedication of unnecessary time is not required to soften the binder material and there is no negative effect. on the deposition and fixation of titanium dioxide and alumina particles. Furthermore, since the heating temperature is not more than 300 ° C above the temperature, at which the binder undergoes a quality change, the rapid melting of the binder material can be advantageously avoided, preventing problems such as excessive deposition of titanium dioxide or alumina particles, the appearance of irregularities on the surface and the formation of craters (pinholes). The heating temperature is preferably between 50 and 150 ° C above the softening temperature of the binder material.

Also in the second example, as regards titanium dioxide as a photocatalyst, the crystalline form can also be rutile or brookite. Furthermore, ZnO, V2O5, WO3, SnO2, SrTiO3, Bi2O3 and Fe2O3 can also be used as photocatalyst. When the gas, whose quantity is to be reduced, is an acid gas, for example NOx, it is possible to use zinc oxide and tin oxide (amphoteric metal oxides) and magnesium oxide, calcium oxide, rubidium oxide, sodium oxide and potassium oxide (basic metal oxides) instead of alumina, as metal oxides. When the gas, whose quantity is to be reduced, is a basic gas, phosphorous oxide (acid metal oxide) can be used in addition to the amphoteric metal oxides.

Other examples are described below. In the first and second examples, the photocatalyst and specific compound described above fix a reagent (eg, NO) or an intermediate (eg, NO2) within the catalytic reactant system to ensure the opportunity for the intermediate to be applied. later in the catalytic reaction, thereby achieving an effect of reducing the amount of harmful materials, for example NOx. In the following examples, apart from the specific compounds described above, other compounds are added to enhance the effect of lowering the amount of NOx or to achieve effects that have not been described above.

The third example is now described. This example describes a photocatalytically activatable material that can effectively drive a catalytic reaction and, at the same time, has antimicrobial activity generated by the active oxygen species generated by the photocatalyst. Two sols are required to make the photocatalytically activatable material. One of the sols is a Ti / Al sol for which alumina is formulated together with titanium dioxide in the formulation ratio already mentioned above, which can drive an efficient catalytic reaction. The other sun is the third sun, in it are scattered particles of copper (Cu), copper oxide, silver (Ag) or silver oxide. A Ti / Al sol coating is then applied to the surface of a tile and the coating is kiln dried to form a Ti / Al layer. Then a coating of the third sol is applied on the surface of the Ti / Al layer arranged on the surface of the tile and the third sol component is fixed on the surface of the Ti / Al layer by photoreduction, and so on. This tile is a tile from the third example. The tile of the third example has a surface layer of titanium dioxide as a photocatalyst together with alumina, fixed thereon, and copper or other particles are fixed on the surface layer. In the preparation of the third sun, the application time is regulated in such a way that the photocatalyst can be satisfactorily exposed to light. For example, a copper weight of 0.8 to 2.0 μg / cm is sufficient to achieve satisfactory results.² after oven drying. The tile of the third example and the comparative tile used in the previous evaluation tests are evaluated by determining their antimicrobial activity. Antimicrobial activity can be assessed on the basis of whether or not the tile has a lethal effect on Escherichia coli (Escherichia coli strain s3 1 10).

Initially, the surface of the tile of the third example and the surface of the comparative tile are sterilized with 70% ethanol. Then 0.15 ml (from 1 to 5x10⁴ CFU) from a suspension of Escherichia coli. A glass plate is placed on the surface of the tiles so that the Escherichia coli comes into intimate contact with the surface of the tiles. In this way the samples are prepared. In this case, a couple of samples are prepared for each of the tiles. A sample of each sample from the third example and a comparative tile are irradiated with light emitted by a fluorescent lamp through the glass plate. The other sample of each of the tiles from the third example and the comparative sheet is placed in a light shelter environment.

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The degree of survival of Escherichia coli in samples under fluorescent light irradiation conditions (under light conditions) and in samples under light-sheltered conditions (under dark conditions) as a function of time elapsed. The antimicrobial activity (proportion of Escherichia coli dead or that has suffered a growth interruption) determined from the degree of survival against the elapsed time is recorded graphically. The results are shown in Figure 10. To measure the degree of survival, the Escherichia coli suspension of each of the samples is wetted in a sterilized gauze and collected in 10 ml of physiological saline solution and the degree of survival is determined. of Escherichia coli in the physiological saline solution and is considered as the degree of survival of the sample.

From Figure 10 it can be seen that, under fluorescent light irradiation conditions, both the tile of the third example and the comparative tile have a high antimicrobial activity. This is probably due to the fact that, under fluorescent light irradiation conditions, titanium dioxide has efficiently generated the active oxygen species in the surface layer and this species has decomposed the organic components of Escherichia coli to kill or interrupt the growth of Escherichia coli. Under conditions protected from light, the comparative tile does not produce active oxygen species and therefore basically does not display antimicrobial activity, while the tile from the third example has relatively high antimicrobial activity, even under conditions protected from light. , because Cu or other particles fixed on its surface display an antimicrobial action even in conditions protected from light. Therefore, in the tile of the third example, under conditions protected from light, the antimicrobial action (which cannot be achieved with titanium dioxide as a photocatalyst, since it is a state protected from light) can be achieved thanks to to Cu or other particles and, therefore, can complement the antimicrobial action of the photocatalyst.

Also in the third example, as regards titanium dioxide as a photocatalyst, the crystalline form can be rutile or brookite. ZnO, V2O5, WO3, SnO2, SrTiO3, Bi2O3 and Fe2O3 can also be used as photocatalyst. Instead of alumina, zinc oxide and tin oxide (amphoteric metal oxides) and magnesium oxide, calcium oxide, rubidium oxide, sodium oxide and potassium oxide (oxides of basic metals) and phosphorus oxide (acid metal oxide). Instead of copper, copper oxide, silver (Ag), silver oxide and metals, which have antimicrobial activity (even low antimicrobial activity), for example palladium, nickel, cobalt, platinum, gold, can be preferably used. , aluminum, iron, zinc, chromium, rhodium and ruthenium.

The fourth and fifth examples are described below. The formulation of the fourth example is a four-component system consisting of a photocatalyst and alumina or another metal oxide (amphoteric metal oxide, basic metal oxide or acid metal oxide), as in the first and second examples, and, in addition, a compound other than described above and the metal, for example copper or silver, as used in the third example. The formulation of example five is a three-component system consisting of a photocatalyst, alumina, or other metal oxide (amphoteric metal oxide, basic metal oxide, or acid metal oxide), and, in addition, a compound other than that described above.

In the fourth example, the metal used in combination with the other ingredients is preferably a metal that has a reduction potential greater than the potential (-3.2 V) of the free electrons released by titanium dioxide as a photocatalyst. , because the metal can be supported on titanium dioxide thanks to the reduction potential (support by reduction). Specific examples of metals that can be used for this are transition metals, for example silver, copper, palladium, iron, nickel, chromium, cobalt, platinum, gold, lithium, calcium, magnesium, aluminum, zinc, rhodium, and ruthenium. Among them, silver, copper, palladium, platinum and gold are especially preferred because they have a positive reduction potential and are therefore capable of creating a support by reduction, To use these metals in combination with the other ingredients Metal support methods can be applied on the photocatalyst. Viable methods for supporting the metal on the photocatalyst are as follows.

(i) Simple mixing: an aqueous solution of metal salt containing a contemplated metal species is added to a photocatalyst sol and mixed with it to adsorb the metal ions on the surface of the photocatalyst particles, thereby supporting the metal on the photocatalyst.

(ii) Coprecipitation: An aqueous solution of metal salt containing a contemplated metal species is added to a photocatalyst sol, then a precipitating agent is added or heated to simultaneously precipitate the metal salt and the photocatalyst, that is, to cause the co-precipitation. In this way, the metal ions are supported on the surface of the photocatalyst particles.

(iii) Support before photoreduction: an aqueous solution of metal salt containing a contemplated metal species is added to a photocatalyst sol and the mixture is irradiated with ultraviolet energy. In this way, the metal is supported on the surface of the photocatalyst particles by photoreduction of the metal ions.

(iv) Support after photoreduction: a photocatalyst film is coated with an aqueous solution of metal salt containing a contemplated metal species and then irradiated with ultraviolet energy. In this way the metal is supported on the surface of the photocatalyst film by photoreduction of the metal ions.

ES 2 209 182 T3 (v) Vapor phase deposition: a metal contemplated in the form of particles or in the form of a compound is supported by chemical or physical deposition in vapor phase.

(vi) Miscellaneous: ions of a contemplated metal species are added before the photocatalyst is granulated by a sol-gel process, then co-precipitated, etc., to obtain photocatalyst / metal ions.

Silicon dioxide (silica: SiO2) is used as the compound to be combined with the photocatalyst, and a metal oxide, for example alumina. Instead of silica, ZrO2, GeO2 or ThO2 can be used.

In the fourth example, simple mixing is adopted, the support before photoreduction or coprecipitation and in this method photocatalysts with metals supported on them are used.

In the photocatalyst activatable tile (example tile) according to the fourth example, photocatalyst sols are prepared containing a photocatalyst (titanium dioxide) with silver or copper supported on it, dispersed by simple mixing, support before photoreduction or coprecipitation . In the same way as that described above in relation to evaluation test 1 of the first example, sols of two different ingredients (alumina and silica) are mixed with sols of photocatalyst with a metal supported on the photocatalyst (photocatalyst / metal) and stirred mix. The tile is covered by gunning with the mixed suns, then it is dried in the oven. In this way the tiles of Example 4 are prepared which are a four component system of photocatalyst / metal (silver or copper) / alumina / silica. In this case, to investigate the influence of the further formulated metal and silica, a tile of a two-component photocatalyst / metal (silver or copper) system (reference tile) is also prepared. The tiles in the fifth example are prepared as follows. Sols of two other ingredients (alumina and silica) are mixed with the photocatalyst sol in the same way as described above for evaluation test 1 of the first example and the mixture is stirred. The tile is covered by gunning with the mixed sun and then dried in the oven. In this way, tiles of the fifth example are obtained which are of a three-component photocatalyst / alumina / silica system. The decrease in the amount of NOx is evaluated with the tiles of the example and the reference tile of the fourth and fifth examples, the tile of the first example and the comparative tile. The tile of the first example and the comparative tile are those described above during the evaluation test 1 of the first example. For the tile in the first example, the formulation ratio a / (a ​​+ b) is 1/11. For the tile in the fourth example, the formulation ratio (SiO2 / (TiO2 + Al2O3 + SiO2)) is 1/11. For the tile of the fifth example, the formulation ratio (Al2O3 / (TiO2 + Al2O3 + SiO2)) is 1/11. For the reference tile of a two-component system, the weight ratio between metal and TiO2 is 0.001 (Ag / TiO2) for the reference tile of a two-component system with silver formulated in it and at 0 .01 (Cu / TiO2) for the reference tile of a two-component system with copper formulated in it.

The CNO / outlet and CNO2 / outlet are measured for these tiles using a measuring apparatus represented in Figure 4 in the same way as that described above for evaluation test 1 of the first example. Determine (CNO-input / CNO-output), CNO2 output and decrease in the amount of NOx 30 minutes after the start of irradiation with light starting from the measured values ​​of CNO-output and CNO2-output and the already known concentration of the test gas (CNO-inlet). The results are shown in Table 1.

The column (CNO-in / CNO-outlet) represents the amount of NO oxidized to NO2 or NO3^- (decrease in the amount of NO) and is an indicative value of the NO oxidation activity. CNO2 / outlet means the amount of NO2 that has been released out of the system. The lower the CNO2 / outlet, the greater the ability to prevent NO2 from being released out of the system, that is, the greater the NO2 adsorption capacity. For this reason, as can be seen from Table 1, the tile of the fourth example shows an NO oxidation activity equal to or greater than that of the first example and can achieve a high decrease in the amount of NOx. Specifically, the tile of the fourth example with silver formulated inside has a high activity (CNO-input / CNO-output), that is, a high NO oxidation activity and a low CNO2 / output, that is, a high NO activity. NO2 adsorption. Therefore, the tile of the fourth example has a combination of good oxidation activity and good adsorption activity.

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ES 2 209 182 T3

The results of the test with the reference tile show that carrying out the support before photoreduction allows the oxidation activity of NO and the reduction of the amount of NOx to be carried out, basically the same as in the first example, even in the case of a two-component system of titanium dioxide and metal. It is observed by the results of the test of the tile of the fifth example that the silica formulation could provide a NO oxidation activity and a decrease in the amount of NOx basically the same as those of the first example, indicating that the silica formulation does not pose problem related to the decrease in the amount of NOx.

In the fourth and fifth examples, as regards titanium dioxide as a photocatalyst, the crystallized form can also be rutile or brookite. ZnO, V2 O5, WO3, SnO2, SrTiO3, Bi2 O3 and Fe2 O3 can also be used as photocatalysts. When the gas, whose quantity is to be reduced, is an acid gas, for example NOx, it is possible to use zinc oxide and tin oxide (amphoteric metal oxides) and magnesium oxide, calcium oxide, rubidium oxide, oxide of sodium and potassium oxide (basic metal oxides) instead of alumina, as metal oxides. When the gas, whose quantity is to be reduced, is a basic gas, phosphorous oxide (acid metal oxide) can be used in addition to the amphoteric metal oxides. On the other hand, the above metals can be used instead of silver and copper and the above oxides can be used instead of silica.

The sixth and seventh examples are described below. As in the formulation of the fourth example, the formulation of the sixth example is a four-component system that has a combination of photocatalyst, typified as titanium dioxide, an amphoteric metal oxide, basic or acid, typified as alumina, the metal described above on the occasion of the fourth example, for example copper, silver, palladium, iron, nickel, chromium, cobalt, platinum, gold, rhodium or ruthenium and the other compound (oxide) described above on the occasion of the fourth example, for example silica. The formulation of the seventh example is a three-component system consisting of a combination of a photocatalyst, an amphoteric metal oxide, basic or acid, typified as alumina, and the other compound (oxide) described above on the occasion of the fourth example, for example silica. The formulations of the sixth and seventh examples are intended to improve decomposition activity, including decomposition of environmental pollutants, for example NOx, and to prevent contamination.

As in the fourth example, in the sixth example photocatalyst sols are prepared containing a photocatalyst (titanium dioxide), with silver or copper supported on it, dispersed therein by simple mixing or support before photoreduction. As in the fourth example, the tiles of the sixth example are prepared in a similar way to that described above during the evaluation test 1 of the first example. As in the fifth example, the tile of the seventh example is prepared by mixing the catalyst sol with a sol of other ingredients (alumina and silica), stirring the mixture, coating the tile with the mixed sol sprayed and drying the mixture in the oven. coated tile. In order to investigate the influence of additionally formulated metal and silica, tiles (reference tiles) are prepared separately for a two-component photocatalyst / silica system and for a three-component photocatalyst / metal (silver or copper) system. /silica. In this case, instead of the spray-gun coating, the photocatalyst sol coating can be applied to the substrate (tile) by centrifugation, by dipping or by other means. The fixation of the photocatalyst sol on the surface of the substrate is carried out by oven drying, as indicated in evaluation test 1 of the first example (baking type), or by mixing a silicone resin with the sol of photocatalyst and crosslinking of the silicone resin at a relatively low temperature (painted type). The tiles of the sixth and seventh example, the reference tile and the comparative tile are evaluated. The comparative tile used is the same as that described during evaluation test 1 of the first example.

The formulation ratio (SiO2 / (TiO2 + Al2 O3 + SiO2)) in the tile of the sixth example is 1/10. The formulation ratio (Al2 O3 / (TiO2 + Al2O3 + SiO2)) in the tile of the seventh example is 1/10. The formulation ratio (SiO2 / (TiO2 + SiO2)) in the reference tile of a two-component photocatalyst / silica system is 1/5. With respect to the reference tile of the two-component photocatalyst / metal system, the weight ratio between metal and TiO2 is 0.001 (Ag / TiO2) for the reference tile of a two-component system with silver formulated in it. and 0.01 (Cu / TiO2) for the reference tile of a two-component system with copper formulated in it. For the reference tile of the three-component photocatalyst / metal / silica system, the weight ratio of metal to TiO2 is the same as that of the reference tile (0.001 (Ag / TiO2) and 0.01 (Cu / TiO2)) and the formulation ratio (SiO2 / (TiO2 + SiO2)) is 1/5.

To investigate the influence of further formulated metal, reference tiles of a two-component photocatalyst / metal system (silver or copper) are described at the outset. For the reference tiles of the two-component system, in the case of the baked type, various metal salts (special quality reagent, manufactured by Wako Pure Chemical Industries, Ltd.) are formulated in a titanium sol (STS-11 , manufactured by Ishihara Sangyo kaisha Ltd.). The metal salt is formulated in an amount of 0.001 to 10%, percentage based on titanium oxide (on solid base), of the titanium oxide sol. After the silver or copper are supported on the photocatalyst by simple mixing, support before photoreduction, then an aqueous solution of a metal salt, that is, a silver or copper salt, is mixed with the titanium oxide sol , the mixture is exposed to ultraviolet light with an intensity of 1 mW / cm² for 2 hours. In this way a photocatalyst sol is obtained with the metal supported thereon. In the case of coprecipitation, a TiOSO4 solution is prepared as the starting compound and an aqueous solution of metal salt is added to this solution, followed by hydrolysis to obtain a sol of the photocatalyst with the metal supported thereon. These photocatalyst sols are then sprayed onto the surface of the tile so that a coating of 0.8 µm thick in terms of thickness is formed after oven drying. The coated tiles are kiln dried at a temperature of 600 to 900 ° C (800 ° C for the reference tiles) to obtain reference tiles of a two-component system (baked type).

ES 2 209 182 T3

In the case of the painted type, various metal salts (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) are formulated in a titanium oxide sol (TA-15, manufactured by Nissan Chemical Industries Ltd.). The metal salt is formulated in an amount of 0.001 to 1%, percentage based on titanium oxide (solid base), in the titanium oxide sol. The photocatalyst sol is then mixed with silver or copper supported on it by simple mixing or support before photoreduction and a silicone resin as binder, with a solid content ratio between titanium oxide and silicone resin. of 7: 3. The mixtures are applied on the surface of the tile by centrifugation and the coated tiles are heated to 150 ° C to obtain the reference tiles of a two-component system (painted types).

The two-component system reference tiles (baked type and painted type) are evaluated for their chemical decomposition activity. The decomposition activity can be directly evaluated in terms of antimicrobial activity and oil decomposition. In this case, the antimicrobial activity is evaluated in terms of lethal / growth inhibitory activity of Escherichia coli strain w3 1 10, as described in the third example above. In this case, the antimicrobial activity of the tile having the photocatalyst layer formed by a photocatalyst (titanium dioxide) is only taken as a value of 1. The decomposition of the oil is determined as follows. A sample is coated with edible oil at a rate of 1 mg / 100 cm² and the coated sample is exposed to ultraviolet light of an intensity of 1 mW / cm² for 7 days. The gloss of the sample is measured before coating with oil, immediately after coating with oil, and at the end of exposure to light. The decomposition of the oil is determined according to the following numerical formula.

oil decomposition (%) = [{(gloss at end of exposure) - (gloss immediately after oil coating)} / {(gloss before oil coating) - (gloss immediately after oil coating)}] x 100

The decomposition of chemical materials by the action of the photocatalyst is mainly derived from the oxidation of the chemical materials with active oxygen species released by the photo-excited photocatalyst. Therefore, the oxidative activity of the photocatalyst can be taken as an index of one of the activities of the photocatalyst to decompose chemical materials. In this case, too, the oxidizing activity of NO of various tin photocatalyst films in terms of conversion of nitrogen monoxide (NO) to nitrogen dioxide (NO2) by oxidation is evaluated as a model reaction. In order to determine the oxidizing activity of NO, the CNOoutput is measured using the test apparatus shown in FIG. 4 in the same way as described above in relation to evaluation test 1 of the first example. (CNO-input / CNO-output) is determined against the time elapsed since exposure to light from the measured CNO-output and the known concentration of the test gas (CNO-input) and from (CNO-input / CNO -output) the total number of moles of NO that have been oxidized in a period of time between the start of exposure to light and one h after starting exposure to light is calculated and is taken as the oxidation activity of the NOT. In this case, the flow rate of NO gas (test gas) is 2 liters / min and the specimen has a size of 5 x 50 cm².

Table 2 summarizes the antimicrobial activity, oil decomposition and NO oxidation activity for the reference tiles (baked type and painted type) of a two-component system. As can be seen from the previous description, the antimicrobial activity, oil decomposition and NO oxidation activity listed in Table 2 are measured so that the tiles are exposed to light.

(Table goes to next page)

ES 2 209 182 T3

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ES 2 209 182 T3

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ES 2 209 182 T3

Table 2 shows that, for a system loaded with copper in reference baked tiles, tiles with 1% copper supported on TiO2 prepared by support before photoreduction have the best antimicrobial activity, oil decomposition and NO oxidizing activity. Also for the silver loaded system, the support before photoreduction results in better antimicrobial activity, oil decomposition and NO oxidizing activity than simple mixing. The addition of any of the metals listed in the table translates into better antimicrobial activity, oil decomposition and NO oxidizing activity than when the system is not loaded with any metal, which indicates that metals, for example copper, silver, palladium and iron, supported on TiO2, contribute to improve the decomposition activity generated by TiO2. For a copper-filled system of the baked-on type, tiles bearing 0.1 to 1% of over-supported on TiO2, obtained by support before photoreduction, have the highest antimicrobial activity. In addition, it has been found that the system loaded with silver has better antimicrobial activity than the system loaded with copper.

From the above results it is clear that, for reference tiles of the baked type and for reference tiles of the painted type, the supported metals, for example copper, silver, palladium and iron, on TiO2 can improve the decomposition activity. That is, the above metals clearly have the function of improving the decomposition activity that generates TiO2. Also, for the metal support method, the support before photoreduction is better for decomposition activity than simple mixing. On the other hand, the regulation of the amount of metal supported can vary the decomposition activity of TiO2.

The antimicrobial activity of the reference tiles of the baked type of a two-component system is also studied, when they are in dark conditions. The result is that, for a reference tile with 0.1% copper supported on TiO2 by simple mixing, the antimicrobial activity is 0.3. In another reference rate with 1% copper supported on TiO2 by simple mixing, the antimicrobial activity is 0.3. Also for a reference tile with 0.1% silver supported on TiO2 by simple mixing, the antimicrobial activity is 0.3. Under dark conditions, since the photocatalyst is not activated, the antimicrobial activity of the reference tile is due to the supported metal itself. If one takes into consideration the fact that the antimicrobial activity of a tile not loaded with metal, that is, a tile containing the photocatalyst alone, is substantially zero, it can be said that, under conditions of exposure to light, the antimicrobial activity of these reference tiles exceeds the activity of the metal itself and the antimicrobial activity of the tiles that contain the photocatalyst alone (1 of table 2). For example, the antimicrobial activity of the reference tile with 0.1% copper supported on TiO2 by simple mixing is 1.5 according to table 2. This value is higher than the sum of the antimicrobial activity (0.3) of the copper itself and the antimicrobial activity (1) of the tile that contains the photocatalyst alone. Therefore, it can be stated that the copper support on the TiO2 can translate into a greater effect than the simple combination of copper and TiO2.

On the basis of the above effect of the reference tiles, the tiles of the sixth and seventh examples are described. In the sixth and seventh examples, hydrophilicity is also evaluated, which is an additional evaluation element. Initially, before the hydrophilicity test and other tests, the relationship between hydrophilicity and surface soil is described.

In recent years it has been found that by conferring hydrophilicity to a surface it can be prevented from accumulating dirt (Kobunshi (Polymer), vol. 44, May 1995, p. 307). Hydrophilicity can be expressed in terms of the contact angle of the surface with the water. The smaller the contact angle, the better the wettability of the surface with water. In this case, the water that is in contact with the hydrophilic surface is less likely to be on the contact surface. If the water is less likely to be on the contact surface, pollutants, for example city dust, which contains rainwater, etc., slide along with the water from the hydrophilic surface, thus amplifying the effect. dirt prevention.

For this reason it has been proposed to coat with a graft polymer that imparts hydrophilicity to the exterior walls of buildings and the like to prevent the accumulation of dirt on the walls thanks to the graft polymer coating. However, although the hydrophilicity of the graft polymer coating translates into a contact angle of the graft polymer coating with water being 30 to 40 °, the water tends relatively to remain on the surface. Therefore, the antifouling effect and the antifogging effect will not necessarily be satisfactory. The inorganic powder typified as mineral clay has a contact angle with water of 20 to 50 ° and, therefore, has an affinity with the graft polymer that has the contact angle just indicated and is capable of being deposited on the surface of the polymer. graft. This makes it difficult for the coating (= paint) and the graft polymer film to have a high effect of preventing the accumulation of dirt on the surface, especially in the case of inorganic dust.

If the contact angle is made smaller than that of inorganic dust, for example urban dust containing a high lipophilic component, and mineral clays, the anti-dirt effect can be further amplified without affinity of the dust with the substrate surface. When the contact angle approaches 0 °, the hydrophilicity increases and the water is able to diffuse in the form of a film and is able to flow over the surface of the substrate, allowing not only urban dust to slip easily from the surface of the substrate but also inorganic dust along with water. In this case, the contact angle is preferably not more than 20 ° and is close to zero from the point of view of increasing the anti-fouling effect.

On the basis of the previous problem, the tiles of the sixth and seventh example of the present invention are studied

ES 2 209 182 T3 using a photocatalyst. Since the hydroxy radical · ΟΗ is generated by the catalytic reaction of the photocatalyst, the contact angle of the tiles with water is measured, which is an indicator of hydrophilicity. The essay is summarized below.

Specimens having a suitable size (baked type) are prepared from the tiles of the sixth and seventh examples, reference tiles of a two-component system and of a three-component system and comparative tiles, already described above. The contact angle of the water drop on the test piece is measured after applying ultraviolet light (wavelength: 320 to 380 nm, amount of light received by the test piece: 1 mW / cm²) with an ultraviolet lamp for 24 h (under light exposure conditions) during tile fabrication and after placing the specimen in a dark place for a period of time long enough to completely interrupt the activity of the photocatalyst ( in dark conditions). The results of the measurements are shown in Table 3.

(Table goes to next page)

ES 2 209 182 T3

<td colspan="3" rowspan="2"> 5</td><td rowspan="2">Mohs hardness of the P-</td><td colspan="3">icle ina</td><td rowspan="2">W »</td><td rowspan="2">u&gt;</td><td rowspan="2">xr</td><td rowspan="2">n</td><td rowspan="2">eo</td><td rowspan="2">u&gt;</td><td rowspan="2">*OR</td><td rowspan="2">W</td><td rowspan="2">KO</td><td rowspan="2">U&gt;</td><td rowspan="2">UJ</td><td rowspan="2">U&gt;</td><td rowspan="2">M3</td><td rowspan="2">IT</td><td rowspan="2">&lt;or</td>

<td>r- |</td><td colspan="2"></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>+ j</td><td></td><td></td><td>1 • H</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>Jm</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> 10</td><td></td><td></td><td>M</td><td></td><td></td><td>⁰ 9</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>X • 0</td><td></td><td></td><td>Ό £ J JS 0 /</td><td>on</td><td> 01</td><td>on</td><td>X »· •</td><td>&lt;n •</td><td> •</td><td>OR t</td><td>OR</td><td>r4 •</td><td>XI * •</td><td>t- •</td><td>OR •</td><td>4p</td><td> 4*</td><td>n *</td>

<td></td><td></td><td></td><td>c</td><td></td><td></td><td> 3 ^Ό 8</td><td>r4</td><td>ri</td><td>on</td><td>C4</td><td>on</td><td> &lt;4</td><td>v&gt;</td><td>&lt;n</td><td>&lt;n</td><td> &lt;4</td><td></td><td>KO</td><td>C4</td><td>C4</td><td> &lt;4</td>

<td></td><td></td><td></td><td>Ό</td><td></td><td></td><td>&gt; Φ H</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>or</td><td></td><td></td><td>• H + JQ</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> 15</td><td></td><td></td><td>• H on</td><td></td><td></td><td>ü § 5 &lt;ts \</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>1 (U 0 Ό af&gt;</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td rowspan="2">8 on φ Ό</td><td></td><td></td><td>fc c &lt;D 0 Ό 4-j</td><td>or</td><td>OR</td><td>or</td><td>OR</td><td>or</td><td>OR</td><td>m</td><td>OR</td><td>OR</td><td>OR</td><td>OR</td><td>or</td><td>OR</td><td>or</td><td>or</td>

<td> 20</td><td></td><td></td><td></td><td></td><td>U Ή · Η W (í &lt;l)</td><td>&lt;n</td><td>&lt;n</td><td>m</td><td>m</td><td>tn</td><td>«Λ</td><td>m</td><td>m</td><td>«N</td><td>tn</td><td>on</td><td>u&gt;</td><td>m</td><td>«N</td><td>m</td>

<td></td><td></td><td></td><td>φ Ό</td><td></td><td></td><td>ls§</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>2-έ</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>Ό O</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> 25</td><td></td><td></td><td> &gt;</td><td></td><td></td><td>H * rj&gt; E ¡0</td><td>or •</td><td>or</td><td>m •</td><td>m •</td><td> «&gt; •</td><td>m «</td><td>CO</td><td>iO</td><td>«N</td><td>it ♦</td><td>u&gt; •</td><td> 00 •</td><td>m •</td><td>m</td><td>m</td>

<td></td><td></td><td></td><td>+ J</td><td></td><td></td><td>P p §</td><td>r4</td><td>rl</td><td>f4</td><td>r4</td><td>f4</td><td>r4</td><td> &lt;4</td><td> «-5</td><td> &lt;4</td><td>r4</td><td>r4</td><td>C4</td><td>i-4</td><td>rl</td><td>r-4</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>OC -H &lt;&lt;3 x</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td> 1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2"> 30</td><td></td><td></td><td>3 &lt;B</td><td></td><td></td><td rowspan="2">S i Ό © η S</td><td>r *</td><td>OR</td><td>m</td><td>r *</td><td>OR</td><td>OR</td><td>OR</td><td>or</td><td>OR</td><td>OR</td><td>OR</td><td>or</td><td>OR</td><td>OR</td><td>OR</td>

<td></td><td></td><td>•• j Ό ~</td><td> «—4</td><td></td><td>&lt;M</td><td>CM</td><td>Í4</td><td> &lt;4</td><td> &lt;4</td><td> &lt;4</td><td> &lt;4</td><td> «4</td><td>&lt;M</td><td> &lt;4</td><td> &lt;4</td><td>CM</td><td>C4</td><td>C4</td><td> &lt;4</td>

<td></td><td></td><td></td><td>HO • Η 0 -P</td><td rowspan="2">10 to</td><td></td><td>O Μ Ό</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>'Η ι — 1 O</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td rowspan="2">E Yes " Θ cc</td><td> (0</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>c</td><td></td><td>N □</td><td>OR Rh</td><td>OR</td><td>s</td><td>OR</td><td>CO</td><td>or"</td><td>&lt;n</td><td>&lt;n</td><td>&lt;n</td><td> &lt;*&gt;</td><td>on</td><td> &lt;*&gt;</td><td>on</td><td>&lt;n</td><td>on</td>

<td></td><td rowspan="2">Π</td><td></td><td>• h '3 P</td><td>or</td><td></td><td>Pj</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> 35</td><td>Τ2</td><td></td><td>or.</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td rowspan="2">c ι — 1 η δ</td><td>φ 6</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>On %</td><td> 3</td><td>s cu</td><td> £</td><td> £</td><td> 3</td><td> 3</td><td>-P CM</td><td> %</td><td>.to</td><td>g</td>

<td></td><td>ο</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> +</td><td> 4-</td><td> 4·</td><td> 4·</td><td> 4·</td><td> +</td><td> ¥</td><td> 4·</td><td> +</td><td> 4-</td><td> +</td>

<td></td><td></td><td>χ:</td><td>c</td><td></td><td></td><td></td><td></td><td>cf</td><td></td><td></td><td>or</td><td>OR*</td><td>or</td><td>or</td><td>OR</td><td>or"</td><td>cf</td><td>what</td><td>or</td><td>OR*</td><td>cF</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>«H</td><td></td><td></td><td>P</td><td>P</td><td> •44</td><td>• H</td><td>• rl</td><td>• w</td><td> 44</td><td>m4</td><td> 44</td><td></td><td> 44</td>

<td rowspan="2"> 40</td><td></td><td>X</td><td></td><td></td><td></td><td></td><td></td><td>on</td><td></td><td></td><td>n</td><td>W</td><td>w</td><td></td><td> 01</td><td></td><td>on</td><td>m</td><td> 0)</td><td>M</td><td>co</td>

<td></td><td>W4</td><td>or</td><td></td><td></td><td></td><td></td><td> 4·</td><td></td><td></td><td> 4-</td><td> 4·</td><td> *4</td><td> 4·</td><td> 4-</td><td></td><td> 4</td><td> 4-</td><td> 4·</td><td> 4·</td><td></td>

<td></td><td></td><td>• Η Η</td><td>(Ό · —1</td><td></td><td></td><td></td><td></td><td>n^C1</td><td></td><td></td><td> °2</td><td>or:</td><td>or"</td><td>or:</td><td>or:</td><td></td><td> «£</td><td> 5</td><td> 5</td><td></td><td></td>

<td></td><td></td><td></td><td>B</td><td></td><td></td><td></td><td></td><td>Yes,¹</td><td></td><td> 3</td><td>g</td><td>to</td><td> $</td><td>g</td><td>sj</td><td>i</td><td></td><td></td><td></td><td>í</td><td>to</td>

<td></td><td></td><td></td><td>H</td><td></td><td></td><td></td><td></td><td></td><td> ·?</td><td> 4-</td><td>• P</td><td> +</td><td>• P</td><td> +</td><td> +</td><td>P</td><td>-P</td><td> ·?</td><td> +</td><td>-P</td><td>•F</td>

<td></td><td></td><td></td><td rowspan="2"> £</td><td></td><td></td><td></td><td>cF</td><td>c</td><td>cF</td><td>OR</td><td>or</td><td>&lt;F</td><td>&lt;F</td><td>or</td><td>cT</td><td>d *</td><td>d *</td><td>&lt;r</td><td>&lt;F</td><td>cT</td><td>or</td>

<td rowspan="2"> 45</td><td></td><td></td><td></td><td></td><td></td><td>• H</td><td></td><td> 44</td><td>• H</td><td>• H</td><td>• H</td><td>p</td><td></td><td>ri</td><td rowspan="2">you</td><td> 44</td><td> 44</td><td> 44</td><td>• rt</td><td> 44</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>Ee</td><td>H</td><td>X</td><td>H</td><td>t *</td><td></td><td></td><td>R</td><td>η</td><td>H</td><td>H</td><td>H</td><td>Ee</td><td>&lt;u</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>ΐ</td><td>Φ P C</td><td>8 • P</td><td> 8</td><td>on Φ</td><td> 8</td><td>on Φ</td><td>on &lt;v</td><td> 8</td><td> 8</td><td> 8</td><td>Ϊ</td><td>on</td><td>«-« χ on</td>

<td> 50</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>P c; a&gt; c:</td><td>&lt;u c</td><td>s c</td><td>P 8 c</td><td>P C Φ c</td><td>P c Φ c</td><td>+ j 8 c</td><td>-il 8 c</td><td>• c Φ c</td><td>-M 8 c</td><td>8 c</td><td>-P 8 c</td><td>Φ -w c Φ c</td><td>Φ c Φ c</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>faith'</td><td rowspan="2">on</td><td> 8</td><td> £</td><td>Π</td><td>π</td><td></td><td> 0</td><td> 0</td><td>Π</td><td></td><td>k</td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>C</td><td>on</td><td>what</td><td>Q</td><td> 0</td><td> 8</td><td> 0</td><td> 8</td><td>or</td><td> 0</td><td> 0</td><td>or</td><td> 5 8</td>

<td> 55</td><td></td><td></td><td></td><td></td><td></td><td></td><td rowspan="2">active</td><td>K φ Ih p</td><td>Ό 10 • H</td><td>0 two φ</td><td>aatro</td><td>s 0</td><td>8 p (0</td><td>s + J &lt;ü</td><td>s + J 10</td><td>S 4J Π3</td><td>or. μ + j (0</td><td> 8</td><td>8 • P</td><td>8 P í0</td><td>to another</td>

<td></td><td></td><td></td><td rowspan="2">ification</td><td></td><td></td><td></td><td>r-</td><td>or § Φ</td><td>• H OR C Φ or</td><td>£ not</td><td>not</td><td>8 \OR</td><td>8 v</td><td>8 not</td><td>8 &lt;or</td><td> 8</td><td>NOT</td><td>not</td><td>8 NOT</td><td>6 (cu</td>

<td> 60</td><td></td><td></td><td></td><td></td><td></td><td> 1</td><td>Ό CU</td><td>p φ</td><td>, Φ P 8</td><td>• ΓΊ 0)</td><td>• • ri Φ</td><td>• rn 0)</td><td>• • ΓΊ Φ</td><td>X&gt; Φ</td><td>• •or Φ</td><td>• n 0)</td><td>• m 0)</td><td>Φ</td><td>• m Φ</td><td>• m Φ</td>

<td></td><td></td><td></td><td rowspan="2">on &lt;0 ri or</td><td></td><td></td><td></td><td>0 io</td><td>Φ Ό 10</td><td>φ Ό &lt;0</td><td>Φ Ό</td><td>ι — 1 Φ XJ</td><td>H Λ Ό</td><td>-I Φ Ό</td><td>I — i Φ Ό</td><td>i — 1 Φ Ό</td><td>r — 1 Φ or</td><td>Ή Φ X5</td><td>i — 1 Φ Ό</td><td>aJ Ό</td><td>r — 1 Φ Ό</td><td>i — 1 Φ TO</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>&lt;P</td><td>•F-" Φ</td><td>• ΓΊ Φ</td><td>Φ</td><td>Φ</td><td>Φ</td><td>E0</td><td> (0</td><td> ¡0</td><td> 10</td><td> &lt;0</td><td> &lt;0</td><td>Φ</td><td> (0</td><td> (0</td>

<td> 65</td><td></td><td></td><td></td><td></td><td></td><td></td><td>H</td><td>F-</td><td>H</td><td>Φ H</td><td>Φ Η</td><td>Φ H</td><td>• φ 'H</td><td>• m Φ</td><td>•or Φ H</td><td>•or</td><td>• ii Φ H</td><td>τη Φ ± L „</td><td>• ο Φ OR-</td><td>• ri Φ H.</td><td>• r-&gt; Δ.</td>

ES 2 209 182 T3

From the results collected in Table 3 it can be deduced that, as for the reference tiles of a two-component system, of which the influence of the metal formulation has been examined, for the tiles of the example of a system of four components (sixth example), the metal formulation indicated in the table, for example copper and silver, can improve both antimicrobial activity, such as oil decomposition activity and NO oxidation activity and expand decomposition activity. In addition, the example tiles can provide antimicrobial activity greater than the sum of the antimicrobial activity of the metals, indicated in the table, for example copper and silver, per se and the antimicrobial activity of the comparative tile containing the photocatalyst alone and the example tiles of a three-component system. Furthermore, the Mohs hardness of the surface layer is equal to that of a simple tile without any surface layer, this indicates that the tiles of the sixth example can be used for practical use of tiles.

The contact angle of the tiles of the sixth and seventh example is less than the comparative tile regardless of whether the tiles are in conditions of exposure to light or in dark conditions, this indicates that, as mentioned before, SiO2 or Al2O3, either alone or in combination, formulated with TiO2 can contribute to improving the hydrophilicity of the tile surface thanks to the adsorption of the hydroxyl group. It has also been found that the formulation of metals indicated in the table, for example copper and silver, does not cause an increase in the contact angle, that is, a decrease in hydrophilicity. From these facts it follows that functional thin films that have decomposition activity and hydrophilicity and functional materials that have thin films can be manufactured by support on the TiO2 of metals that can contribute to improve the decomposition activity, for example copper, the silver, palladium, iron, nickel, chromium, cobalt, platinum, gold, rhodium and ruthenium, and by formulation of SiO2 and Al2O3 that contribute to improve hydrophilicity, both alone and in combination, within TiO2.

It is evident that the tiles of the sixth and seventh examples have the effect of decreasing the amount of harmful materials, for example nitrogen oxides, as described in the first and second examples, because the surface layer contains Al2O3 apart from TiO2. The tile of the seventh example of a three-component system lacking the above metal has an oxidizing activity of NO equal to that of the comparative tile. However, for the tiles of the sixth and seventh examples, as indicated above in connection with the first and second examples, the amount of NO2 also decreases because the intermediate product (NO2) is chemically converted to nitric acid. Therefore, the tiles of the sixth and seventh examples have the effect of decreasing the overall amount of harmful materials, including NO and NO2.

In the tiles of the sixth and seventh examples (painted type) the effect of improving decomposition activity is examined. Table 4 shows the results. The results show that, also for the painted type, according to the tiles of the sixth and seventh example, the formulation of metals indicated in the table can increase both the antimicrobial activity and the decomposition activity of the oil and the oxidizing activity of NO and can extend decomposition activity. It is evident that, like the tiles of the baked type example, the tiles of the sixth and seventh example of the painted type can contribute to improve the hydrophilicity of the tile surface thanks to the adsorption of the hydroxyl group derived from the SiO2 that is formulated along with TiO2. In the painted-type example tiles, the surface layer has a pencil hardness of 4H, indicating that the painted-type example tiles can be used for practical use as tiles.

The amount of copper, silver, etc. formulated is described taking as a model the tiles of the sixth example of a four-component photocatalyst / metal / alumina / silica system. The tiles of the sixth example are manufactured so that the formulation ratio (SiO2 / (TiO2 + Al2O3 + SiO2)) is constant and equal to 1/10, varying the formulation ratio of metals c / d, in which c indicates the weight of the metal and d means the weight of the TiO2. For the example tiles, the relationship between the metal formulation ratio and antimicrobial activity is examined. The results are shown in Figure 11 (baked type) and in the

ES 2 209 182 T3

Painted type

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<td>you</td><td>I heard 4-i ω</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> 44</td><td>q OI</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>c</td><td>3 iH</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>BECAUSE</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td>IT</td><td>IT</td><td>or</td><td>r »</td><td>or</td><td>r »</td><td>or</td><td>or</td><td>rt</td><td>M &lt;</td><td>r-</td><td>OR</td><td>xr</td><td>xr</td><td>xr</td>

<td></td><td></td><td> *</td><td> •</td><td> •</td><td> •</td><td> »</td><td> *</td><td> •</td><td> •</td><td> •</td><td> •</td><td> •</td><td> *</td><td> •</td><td> •</td><td> •</td>

<td> 0</td><td> 0</td><td> &lt;□</td><td>or</td><td>«H</td><td>or</td><td>r4</td><td>or</td><td>IT</td><td>m</td><td>to</td><td>CM</td><td>r-4</td><td>IT</td><td>CM</td><td>CM</td><td>CM</td>

<td></td><td>q O</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Sj</td><td>Or 2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> &gt;0</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>• H</td><td>5 OJ</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>or</td><td>aux</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>"1 • H ω &lt;#&gt;</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td rowspan="2">0.0) 'g X5 0) 0 4-1</td><td>or</td><td>or</td><td>OR</td><td>or</td><td>or</td><td>or</td><td>it</td><td>or</td><td>or</td><td>OR</td><td>or</td><td>OR</td><td>OR</td><td>OR</td><td>OR</td>

<td>M</td><td>m</td><td>m</td><td>σ&gt;</td><td>σ&gt;</td><td>σ&gt;</td><td>σ&gt;</td><td>ITEM)</td><td>V&gt;</td><td>IT</td><td>m</td><td>(X</td><td>IT</td><td>IT</td><td>&lt;n</td><td>IT</td>

<td>Φ Ό</td><td>Or q -η ra &lt;or you</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Φ Ό</td><td>ü) -HU Gura</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>Γ * s P Π3 O XI O</td><td></td><td></td><td>m</td><td></td><td></td><td></td><td>to</td><td>m</td><td>IT</td><td>UO</td><td>in</td><td>to?</td><td>in</td><td>m</td><td>IT</td>

<td></td><td>• Η · Κ</td><td></td><td></td><td> *</td><td>CM</td><td>n</td><td>CM</td><td> •</td><td> •</td><td> •</td><td> •</td><td> •</td><td> •</td><td> •</td><td> •</td><td> •</td>

<td>• H</td><td>»&gt; C * 0 • Η -HC</td><td></td><td></td><td>CM</td><td></td><td></td><td></td><td>CM</td><td>fM</td><td>CM</td><td>ri</td><td>Rh</td><td>CM</td><td>rM</td><td></td><td>Rh</td>

<td> 4-&gt;</td><td>44 44 ñj</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>OR</td><td>OC -H</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> &lt;</td><td>&lt;&lt;0 X)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td>tTV</td><td>or</td><td>Ό</td><td>to)</td><td>H</td><td>M</td><td>or</td><td> 4-&gt;</td><td>g</td><td rowspan="2"> &lt;§</td><td> 3</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td> &lt;&lt;</td><td>or</td><td> 04</td><td>Cm</td><td> 2</td><td>OR</td><td> 9</td><td>CU</td><td>Λ}</td><td>tá</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td> 4&gt;·</td><td> +</td><td> +·</td><td> 4*</td><td> +</td><td> +</td><td> +</td><td> +</td><td>• t</td><td> 4*</td>

<td></td><td>c</td><td></td><td>or</td><td></td><td></td><td>«X or</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>OR</td><td>d</td><td>d</td><td>d</td>

<td></td><td>Ό</td><td></td><td>«Rl</td><td></td><td rowspan="2">or¹</td><td>-H</td><td>• H</td><td>• H</td><td></td><td></td><td>Ή</td><td>• H</td><td>• H</td><td>• H</td><td>• H</td><td>-r</td>

<td></td><td>Ή</td><td></td><td>CQ</td><td></td><td>ω</td><td>to</td><td>to</td><td>to</td><td>to</td><td>to</td><td>to</td><td>to</td><td>to</td><td>to</td><td> 10</td>

<td></td><td rowspan="2">OR CO r — 1</td><td></td><td> +</td><td>• H</td><td>«H</td><td></td><td> +</td><td> +</td><td> 4·</td><td> 4·</td><td> +</td><td> +</td><td> 4</td><td>-t</td><td> 4·</td><td> +</td>

<td></td><td>&lt;M</td><td>d</td><td>tO</td><td> 10</td><td>• 0 or</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td><td>d</td>

<td></td><td> 23</td><td>OR</td><td> &lt;*♦</td><td> 4·</td><td> 4?</td><td>&lt;N</td><td> &lt;4</td><td> «4</td><td></td><td></td><td>(X</td><td></td><td>fX</td><td>_yes »</td><td></td><td> «4</td>

<td></td><td> 5</td><td>n4 CQ</td><td></td><td> «&lt;</td><td>to</td><td>to</td><td></td><td>to</td><td>to</td><td> $</td><td></td><td>d</td><td>to</td><td>to</td><td>to</td><td>to</td>

<td></td><td>p</td><td> 4·</td><td></td><td></td><td>-t-</td><td> 4·</td><td> ·?</td><td> +</td><td> 4“</td><td>M-</td><td> +</td><td> +</td><td> +</td><td> +</td><td> 4·</td><td></td>

<td></td><td>μ-.</td><td>«X or</td><td>or'</td><td>d</td><td>or</td><td>&lt;s</td><td>or-</td><td>d</td><td>OR</td><td>d</td><td>d</td><td>d</td><td>d</td><td>&lt;* or</td><td>d</td><td>d</td>

<td></td><td></td><td>• H</td><td></td><td></td><td>«H</td><td>• H</td><td>• H</td><td>Ή</td><td>-H</td><td>• H</td><td>• H</td><td>• H</td><td>• rt</td><td>• H</td><td>• H</td><td>* H</td>

<td></td><td></td><td>ÍH</td><td>and*</td><td>Et</td><td>IH</td><td>η</td><td></td><td>H</td><td>Et</td><td></td><td></td><td>H</td><td>Em</td><td>E- &lt;</td><td>Em</td><td></td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td>X-</td><td></td><td>(Λ</td><td> 05</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td>σ to</td><td></td><td>Φ 44</td><td>Φ 44</td><td></td><td></td><td></td><td></td><td>Z — K</td><td> ____</td><td></td><td></td><td></td><td> —</td><td>ra</td>

<td></td><td></td><td> 4-</td><td></td><td>c</td><td>what</td><td>ra</td><td>ra</td><td>ω</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>CQ</td><td>ω</td><td rowspan="2">Φ</td><td>Φ</td>

<td></td><td></td><td>c</td><td></td><td> 0)</td><td> 0)</td><td>ra</td><td> 0)</td><td>ai</td><td> 0)</td><td>you</td><td>ω</td><td>ra</td><td> 05</td><td>ai</td><td> 44</td>

<td></td><td></td><td> 0</td><td>ra</td><td>what</td><td>or</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td></td><td>k *</td>

<td></td><td></td><td>c</td><td> 0)</td><td>Q</td><td>Q</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>c</td><td rowspan="2">Φ</td><td>CU</td>

<td></td><td></td><td>F</td><td> 44</td><td>p.</td><td></td><td>ω</td><td> 0)</td><td>(I)</td><td> 0)</td><td> &lt;1)</td><td>ai</td><td> 0)</td><td> 0)</td><td> 0)</td><td>j-</td>

<td></td><td></td><td>ε</td><td rowspan="2">c 0) c</td><td>g</td><td>s</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>what</td><td>Q</td><td> 8,</td>

<td></td><td></td><td>C</td><td> 8</td><td> 8</td><td> &amp;</td><td> &amp;</td><td> 8</td><td> 8.</td><td></td><td> 8*</td><td>s</td><td> 8</td><td> 8.</td><td></td><td>s</td>

<td></td><td></td><td>c</td><td>fi</td><td> &amp;</td><td> «</td><td>g</td><td>g</td><td>g</td><td> 5</td><td rowspan="2">OR</td><td> 0</td><td> 5</td><td>P</td><td>R</td><td rowspan="2"> 8</td><td> 8</td>

<td></td><td></td><td>tr</td><td>P</td><td>or)</td><td>Φ</td><td>or</td><td>or</td><td>or</td><td>OR</td><td> 0</td><td>OR</td><td>or</td><td>or</td><td></td>

<td></td><td>c</td><td>c x</td><td> 0</td><td> 4-»</td><td>IM 4-&gt;</td><td> 0</td><td> 0</td><td> 0</td><td>or</td><td> 0</td><td>p</td><td>P</td><td> 0</td><td> 0</td><td>g</td><td> 8</td>

<td></td><td>'OR</td><td></td><td></td><td> ««-*·</td><td> »—·</td><td> 0</td><td> 0</td><td>or</td><td>or</td><td></td><td></td><td></td><td>what</td><td>what</td><td></td><td rowspan="2">ra</td>

<td></td><td></td><td></td><td>ra</td><td></td><td></td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td> 44</td><td rowspan="2">to</td>

<td></td><td rowspan="2">or &lt;0</td><td> (0</td><td> 01</td><td>ra</td><td>ra</td><td>ra</td><td rowspan="2">ra 3.</td><td rowspan="2">ra □</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td rowspan="2">ra 3</td><td rowspan="2"></td><td> 8</td>

<td></td><td>• H</td><td>what</td><td>Ή</td><td>• H</td><td> □</td><td></td><td> 3</td><td> ?</td><td> 3</td><td>π</td><td>cu</td>

<td></td><td>or</td><td>or</td><td> 44</td><td>OR</td><td>or</td><td> 0</td><td> 0</td><td>OR</td><td>or</td><td>C</td><td> 0</td><td>ΰ</td><td>or</td><td> □</td><td></td><td></td>

<td></td><td></td><td>c</td><td> &lt;«*»</td><td>c</td><td>c</td><td></td><td></td><td></td><td></td><td></td><td>"H."</td><td></td><td></td><td></td><td></td><td rowspan="2">c £&gt;</td>

<td></td><td>U-4</td><td> 0)</td><td></td><td> 0)</td><td> 0)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>ω</td><td>M Φ</td><td>r-</td><td> 3</td><td></td><td>&lt;O</td><td>vO</td><td>\ D</td><td>M3</td><td>\OR</td><td>kO •</td><td>SW</td><td> •</td><td></td><td></td><td></td>

<td></td><td> &lt;0</td><td>&lt;Ή</td><td>• I^-)</td><td>MJ</td><td> 44</td><td>• ΓΊ</td><td>• m</td><td>• i — i</td><td>• γί</td><td> •1—</td><td>• m</td><td>• ΓΊ</td><td>• m</td><td>• m</td><td>• ΓΊ</td><td>• r ~</td>

<td></td><td rowspan="2">or</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td>ai</td><td>ai</td><td>ai</td><td rowspan="2">ai</td><td> 0)</td><td></td>

<td></td><td> 0</td><td></td><td>or</td><td>or</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td></td><td></td><td>Rh</td><td></td><td></td><td>r-4</td><td>&lt;—I</td><td></td><td></td><td>f — 1</td><td>i-4</td><td>Ή</td><td>Ή</td><td>r-1</td><td></td><td rowspan="2">Φ</td>

<td></td><td></td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td>to)</td><td> 0)</td><td>cu</td><td>ai</td><td> 0)</td><td> 0)</td><td rowspan="2">0) X)</td><td> 0)</td>

<td></td><td></td><td>X)</td><td>X</td><td>xj</td><td>Ό</td><td>Ό</td><td>X</td><td>X</td><td>Ό</td><td>Ό</td><td>Ό</td><td>Ό</td><td>Ό</td><td>Ό</td><td>Ό</td>

<td></td><td></td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td><td>ra</td>

<td></td><td></td><td>•F-</td><td>ΓΊ</td><td>Ό</td><td>Ή</td><td>Ό</td><td>• n</td><td>'ΓΊ</td><td>'ΓΊ</td><td>'F-</td><td>• ri</td><td>'Π</td><td>• m</td><td>ΓΊ</td><td>m</td><td rowspan="2">&lt;u</td>

<td></td><td></td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td> 0)</td><td>Q)</td><td> 0)</td><td> 0)</td><td>OR)</td><td>to)</td><td> 0)</td>

<td></td><td></td><td>t-</td><td>H</td><td>t *</td><td>H</td><td></td><td>H</td><td>H</td><td></td><td>tra</td><td></td><td>H</td><td>tr *</td><td>H</td><td>H</td><td></td>

ES 2 209 182 T3 figure 12 (painted type). In this case, the antimicrobial activity is expressed by taking as a value of 1 the antimicrobial activity of the tile of the seventh example of a photocatalyst / alumina / silica three-component system.

It is obvious from Figures 11 and 12, both for the baked type and for the painted type, that an antimicrobial activity greater than 1 can be provided also in the case of any of the metals silver, palladium, platinum, copper and chromium, when the metal formulation ratio is greater than 0.00001. Antimicrobial activity peaks when the metal formulation ratio is 0.001 for silver, palladium, and platinum and 0.01 for copper and chromium. After the antimicrobial activity has reached the maximum, it gradually decreases. This shows that satisfactory results can be obtained when metals, for example silver, palladium, platinum, copper and chromium, are formulated in a metal formulation ratio of 0.00001 to 0.05. That is, when these metals are formulated in a metal formulation ratio greater than 0.00001, advantageously, there is no possibility that the metal does not contribute to the improvement of the antimicrobial activity at all, unless the metal content is excessively low. On the other hand, when these metals are formulated in a formulation ratio lower than 0.05, with advantage, there is no possibility that the amount of metal is excessive in relation to the amount of the photocatalyst (TiO2), negatively affecting the catalytic reaction. of the photocatalyst. It has also been found that the example tiles having a surface layer containing silver, palladium or platinum as the fourth component, have superior antimicrobial activity than the example tiles having a surface layer containing copper or chromium as fourth component.

The surface properties of the surface layer formed on the surface of a tile using the photocatalyst sol in the manner described above will be described taking as a model the tile of the sixth example of a four-component photocatalyst / metal / alumina / silica system and The tile of the seventh example of a three-component photocatalyst / alumina / silica system. In this case, the tiles of the sixth and seventh example are such that, in the surface layer, the formulation ratio (SiO2 / (TiO2 + Al2O3 + SiO2)) is constant and equal to 1/10, varying the thickness of the layer surface, one of the surface parameters. For the example tiles, the relationship between surface layer thickness and contact angle, antimicrobial activity, oil decomposition activity, and NO oxidizing activity are examined. The results are shown in tables 13 to 17.

Figures 13 to 16 show the results of the tiles (baked type) of the sixth example of a four component system. Specifically, figure 13 is a graph that presents the relationship between the thickness of the surface layer and the contact angle under conditions of exposure to light, figure 14 is a graph that presents the relationship between the thickness of the surface layer and antimicrobial activity, Figure 15 is a graph showing the relationship between the thickness of the surface layer and the decomposition activity of the oil and Figure 16 is a graph showing the relationship between the thickness of the surface layer and the oxidation activity of NO. In this case, the antimicrobial activity is expressed by taking as a value 1 the antimicrobial activity of the tile that has a surface layer containing photocatalyst / alumina / silica. Fig. 17 is a graph showing the relationship between the thickness of the surface layer and the contact angle under conditions of exposure to light in tiles (baked type) of the seventh example of a three-component system. The example tiles with a four component system have a surface layer bearing silver, palladium, platinum, copper or chromium, said surface layer having a thickness of 0.005 to 3 µm.

For the tiles of the examples of a three-component system and a four-component system, described above, since the surface layer contains SiO2 that contributes to improve the hydrophilicity by adsorbing the hydroxyl group, the function exerted by the incorporation is expected. SiO2 (improvement of hydrophilicity). In this case, as indicated above, the improvement in hydrophilicity based on whether the contact angle is small or not is confirmed and a contact angle less than 20 ° is preferred. Looking at Figures 13 and 17 with this in mind, it will be appreciated that for the baked-on type of tiles in the examples of a three-component system and a four-component system, a low contact angle, less than 20 °, when the thickness of the surface layer is greater than 0.01 µm, that is, the antifouling effect can be advantageously achieved by improving the hydrophilicity. The reason why a low contact angle, less than 20 °, is achieved in the case of a surface layer thickness greater than 0.01 μm is believed to be that, thanks to the satisfactory layer thickness (surface layer) , the contact angle of the surface layer, formed on the substrate (tile), can provide by itself, even when the contact angle of the substrate is large.

From Figures 13 and 17 it appears that when the thickness of the surface layer is greater than 0.5 µm, the contact angle is kept low. On the other hand, the weight of the contact zone of the surface layer increases as the thickness of said surface layer increases. Therefore, when the thickness of the surface layer is excessively large, the adhesion between the substrate and said surface layer often decreases, causing the separation of the latter layer. For this reason, the thickness of the surface layer is preferably kept at a value less than 3 µm, considering that it is desired to maintain the adhesion between the substrate and the surface layer. Furthermore, when the thickness of the surface layer is too great, the violet light does not reach the lower portion of the surface layer at all. This makes it impossible for the entire surface layer to display photocatalytic activity. Also from this point of view, the thickness of the surface layer will preferably be less than 3 µm.

As shown in Figures 14 to 16, when the thickness of the surface layer is in the range indicated above (0.01 to 3 μm), the antimicrobial activity, decomposition activity can be advantageously and safely improved oil and NO oxidation activity. In addition to the thickness of the surface layer, the following surface properties have been studied.

ES 2 209 182 T3

During ultraviolet irradiation, the photocatalyst generates excited electrons together with hydroxy radicals. Therefore, specification of the phenomena generated in the surface layer by the excited electrons and inspection of the situation can reveal the mechanism of generation of the excited electrons, that is, how hydroxy · OH radicals are produced. For the tiles of the sixth and seventh examples, the surface layer contains SiO₂ which can adsorb and retain a hydroxyl group, so that the hydroxy • OH radicals produced by the photocatalyst are retained in the SiO2. Therefore, it is considered that a large amount of excited electrons produced by the photocatalyst results in the production of a large amount of hydroxy • OH radicals and consequently increases the hydroxyl density on the surface of SiO2 and decreases the angle contact with water, increasing hydrophilicity. For this reason, when ultraviolet irradiation is carried out by depositing a silver nitrate solution on the surface layer, the charge of the silver ion of the silver nitrate solution deposited on the surface layer varies by the action of the excited electrons, developing a color reaction. This generates a color difference ΔE between the pre-UV state and the post-UV state. This color difference ΔE increases as the number of excited electrons involved in the reaction increases and, therefore, can serve as an indication of hydrophilicity. Therefore, the color difference ΔE is observed as follows.

To measure the color difference ΔE, a 1% silver nitrate solution is used, a general reagent capable of developing a color reaction. Silver ions in this solution precipitate as silver as a result of a reaction with excited electrons (e^-) generated by the photocatalyst according to the following formula. The precipitation of silver causes the color of the silver nitrate solution deposited on the surface to turn brown or black, generating a clear color difference ΔΕ.

Ag + + e> Ag |

Therefore, a 1% silver nitrate solution is deposited on the surface layer of the painted type of the tiles of the sixth example (four components) and of the seventh example (three components) and, in this state, they are irradiated with light. ultraviolet the tiles of the examples, then the color difference ΔΕ is measured for each of the tiles. Ultra violet light is applied with an intensity of 1.2 mW / cm² on the surface layer for 5 min and the relationship between the measured color difference ΔΕ and the contact angle, antimicrobial activity, oil decomposition activity and NO oxidation activity is investigated. In measuring the color difference ΔΕ, the residual aqueous solution on the tile surface is rubbed with a Kim towel and the difference between the amount of silver color development of the tile surface between this state is determined. and the pre-test state (before UV irradiation). The amount of color development is measured with a ND300A color difference meter, manufactured by Nippon Denshoku Co., Ltd., according to JIS Z 8729 (1980) and JIS Z 8730 (1980).

Figures 18 to 21 present the experimental results of tiles (painted type) of the sixth example of a four-component system. Specifically, figure 18 is a graph that presents the relationship between the color difference ΔΕ and the contact angle under conditions of exposure to light, figure 19 is a graph that presents the relationship between the color difference ΔΕ and the antimicrobial activity, Figure 20 is a graph showing the relationship between the color difference ΔΕ and the decomposition activity of the oil and Figure 21 is a graph showing the relationship between the color difference ΔΕ and the NO oxidation activity. Also in this case, the antimicrobial activity is expressed taking as value 1 the antimicrobial activity of tiles that have a surface layer containing photocatalyst / alumina / silica. Figure 22 is a graph showing the relationship between the color difference ΔΕ and contact angle under light exposure conditions of the tile (painted type) of the seventh example of a three-component system. The tiles in the examples of a four-component system have a surface layer containing silver and the test is carried out for tiles showing a color difference ΔΕ between 0 and 60. In this case, the tile that yields a color difference ΔΕ of zero is a simple tile that does not produce excited electrons (a tile that has a surface layer consisting solely of paint).

From Figures 18 to 22 it appears that a color difference ΔΕ greater than 1 is preferred because the contact angle is low, less than 20 °, and the antifouling effect is enhanced by an improvement in hydrophilicity. When the color difference ΔΕ is more than 20, the contact angle is kept low. On the other hand, the greater the amount of photocatalyst, the more active is the generation of excited electrons and the greater the color difference ΔΕ. However, in this case the amount of photocatalyst referred to the total amount of the ingredients other than the photocatalyst (Al2O3, SiO2 or a combination of Al2O3 or SiO2 with the above metal) becomes large and a large amount of photocatalyst decreases the adhesion to the substrate and generates a greater tendency to separate the surface layer. When the color difference ΔΕ is less than 50, the amount of photocatalyst referred to the total amount of the other ingredients, other than the photocatalyst, is not too great, which can advantageously prevent the separation of the surface layer.

As shown in Figures 19 to 21, the color difference ΔΕ is preferably in the above range (1 to 50) from the viewpoint of safely enhancing antimicrobial activity, decomposition activity of oil and NO oxidation activity.

An improvement of the superhydrophilic activity achieved with the addition of other ingredients (metal oxides) that contribute to improve the hydrophilicity of TiO2, for example SiO2 or Al2O3, is described below. First, the baked-on type tiles of the eighth example are described.

ES 2 209 182 T3 (i) Preparation of catalyst sol and metal oxide: photocatalytic material

TiO Sun₂: mean particle diameter around 0.02 μm (STS-11, manufactured by Ishihara Sangyo kaisha Ltd.) or mean particle diameter of 0.01 μm (A-6L, manufactured by Taki Chemical Co., Ltd.) .

SnO Sun₂: mean particle diameter around 0.002 µm (manufactured by Taki Chemical Co., Ltd.).

In the eighth example a SnO2 sol is used in addition to the anatase form of TiO2 which is harmless, chemically stable and cheap. As alternative materials other crystalline, photocatalytically active TiO2, SrTiO3, ZnO, SiC, GaP, CdS, CdSe, MoS3, V2O5, WO3, SnO2, Bi2O5 and Fe2O3 can be used.

Metal oxide sol / SiO₂: mean particle diameter between 0.007 and 0.009 µm (Snowtex S, manufactured by Nissan Chemical Industry Ltd.).

Sun of Al₂OR₃: mean particle diameter from 0.01 μm to 0.1 μm (Alumina Sol 200, amorphous form, manufactured by Nissan Chemical Industry Ltd.) or mean particle diameter from 0.01 to 0.02 μm (Alumina Sol 520, Boehmite form, manufactured by Nissan Chemical Industry Ltd.).

SoldeSiO2 + K2O: (Snowtex K, SiO2 to K2O molar ratio: 3.3 to 4.0, manufactured by Nissan Chemical Industry Ltd.).

SiO2 + Li2O sol: (Lithium silicate 35, SiO2 to Li2O molar ratio 3.5, manufactured by Nissan Chemical Industry Ltd.).

Sun by ZrO₂: mean particle diameter 0.07 μm (NZS-30B, manufactured by Nissan Chemical Industry Ltd.).

All the above suns are commercial products. As an alternative, it is possible to use a liquid obtained by adding a hydrolysis inhibitor, for example hydrochloric acid or ethylamine, to the metal alkoxide as starting material, dilute the mixture with an alcohol, for example ethanol or propanol, and allow the hydrolysis to progress. Totally or partially. For example, titanium alkoxides that can be used with tetraethoxy-titanium, tetraisopropoxy-titanium, tetra-n-propoxy-titanium, tetrabutoxy-titanium, and tetramethoxy-titanium. Other organometallic compounds (chelates and acetates) and inorganic metal compounds, for example TiCl4 and Ti (SO4) 2, can also be used as starting material.

(ii) Preparation of materials to confer hydrophilicity

When mixing a sol of photocatalytic material with a sol of metal oxide, each of the sols is previously diluted so that its solids content is 0.4% by weight and the sols are mixed in proportions indicated in the following table 5 , then stir thoroughly. The solids weight ratio after mixing is the liquid weight ratio of the sols.

(iii) Preparation of hydrophilizable tiles

An enameled tile (AB06E11, manufactured by TOTO) is used as a substrate and a predetermined amount of mixed sol with a layer thickness of 0.5 µm is sprayed onto its surface. The coated drying is oven dried at a maximum temperature of 700 to 900 ° C in an RHK (a rotary hearth oven) for a baking period of 60 min. In this way the tile of the eighth example is produced. In the eighth example, spray coating is used. Other coating methods are also viable, for example liquid coating, spin, dip, roll, brush, and so on. In the eighth example, tiles are used as the substrate. Apart from tiles, metals, ceramic materials, pottery materials, glass, plastics, wood, stone, cement, concrete or combinations or laminates of the previous substrates can be used. In this eighth example, the sols described in the previous sol are used, that is, sols of a two or three-component system that are a combination of photocatalyst, the amphoteric or basic or acid metal oxide, typified as alumina, and the other compound (oxide), for example silica, described in Example 4. However, in some cases a wide variety of compound types (metal oxides) can be used as a component.

(iv) Evaluation

Hydrophilicity is evaluated in terms of the static contact angle of the water. At the output, test tiles (the eighth example tile and the comparative tile) are irradiated with ultraviolet light emitted by a BLB fluorescent lamp (a black light lamp, FL20BLB, manufactured by Sankyo Electric Co., Ltd.) with an intensity 1.5 mW / cm² for 24 h and the contact angle of the tiles with the water is measured. The tiles are then stored under protected conditions (in a dark place) for 72 h and the angle of contact with the water is measured again. The results are collected in the table. Film strength is evaluated in terms of Mohs hardness. The results are shown in Table 5.

ES 2 209 182 T3

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<td></td><td colspan="2">to z</td><td>pH</td><td> 04</td><td>in xi m</td><td>co r ~ co &lt;3t</td><td>O Η (N Μ X¹Η pt H p | H</td><td>λ co &lt; r ~ 4 r-4 r — 1 r ~ t 1</td><td>Xt &lt;Ή C</td><td>3 s</td><td> 22</td>

ES 2 209 182 T3

From the numbers 2 to 14 of table 5 it can be deduced that, for hydrophilization by ultraviolet radiation, when SiO2 / (TiO2 + Al₂OR₃ + SiO₂) is> 0.4, the contact angle of the tiles of the examples with water is less than 10 °, which indicates that the hydrophilization carried out is satisfactory. After storing in a dark place, when the amount of TiO2 is identical, the hydrophilicity is maintained at a high level when an increasing amount of Al2O3 is added. Also, if Si2 is added, the hardness increases as the amount of SiO2 added increases. From these facts it is evident that the addition of SiO2 and Al2O3 to the photocatalyst (TiO2) can give rise to a formulation that, compared to the photocatalyst alone, has better hydrophilicity under conditions of exposure to light, has better retention of hydrophilicity in dark conditions. and it is found that it has better surface hardness and better density. When the sols described in this example are used, it is considered that, among these effects, the improvement in hydrophilicity is mainly due to the addition of Al2O3 and the improvement in the hardness of the film is due to the addition of SiO2. No. 1 of table 4 shows the results obtained with the glazed tile, while No. 2 shows the results of the tile using the photocatalyst alone (comparative tile).

The numbers 15 to 18 in Table 5 show the results for the same tiles used before, except that a part of SiO2 has been replaced by K2O. Also in this case, better hydrophilicity and an increase in surface hardness are achieved when the baking temperature is between 700 and 800 ° C, when SiO2, K2O and Al2O3 are added. No. 19 contains the results of the test in which a part of SiO2 has been replaced by LiO2. Also in this case, the hydrophilicity and surface hardness are improved.

Nos. 17 and 18 show the results of the examination of the shape of the alumina sol starting material. When using an alumina sol, which is amorphous and has a feather-like structure, a further improvement in hydrophilicity is noted. This suggests that, in order to improve hydrophilicity, the structure having a higher content of hydrophilic groups is more effective than the particulate form.

No. 20 shows the results of the test in which ZrO2 is added to TiO2. It follows from these facts that ZrO2 is also effective in improving hydrophilicity.

No. 21 and No. 22 show the results of the test in which SnO2 is used as a photocatalyst. It is found that the use of SnO2 alone can also provide a hydrophilic effect and the subsequent addition of Al2O3 can improve the hydrophilicity. At this time, the surface hardness has not decreased and it is confirmed that SnO2 itself has the function of a binder.

Furthermore, it is clear from Examples 3 to 14 that the greater the amount of Al2O3 added, the smaller the contact angle and the better the hydrophilicity. Therefore, the hydrophilicity can be varied by regulating the amount of Al2O3 that is added. From the results collected in table 2, since the decomposition activity of TiO2 can be varied by regulating the amount of metals, for example copper, silver, palladium and iron supported on the photocatalyst, with the amount of Al2O3 added and with the amount of supported metal, the balance between hydrophilicity and decomposition activity (decomposition properties) can be regulated. The result is that, when a high decomposition activity is required, this can be achieved by keeping the level of hydrophilicity equal to or greater than the level reached by the photocatalyst.

Having hydrophilic nature and decomposition activity has the following advantages. In particular, a two-stage soil removal process based on hydrophilic nature and soil removal based on photodecomposition activity can provide a marked improvement in removal of deposited soils and removal speed. In this case, for some soils, the intensity of the deposition of negligible soils that remain after removing the soils based on the hydrophilic nature is high. However, a better decomposition activity thanks to the regulation of the supported metal makes it possible to eliminate even light soils that have a great intensity of deposition. In addition, removing stains or dirt can prevent the photocatalyst from being shielded from light. This could force a greater amount of light to be applied. Therefore, stain removal based on hydrophilic nature and soil removal based on decomposition activity can be preserved very effectively.

In summary, it has been found that the addition of SiO2, Al2O3 or ZrO2 to the photocatalyst can improve the contact angle under conditions of exposure to light and the preservation of hydrophilicity after storage in a dark place. This effect is considered to be due to the hydrophilic nature of these materials. The heat of wetting can be mentioned as an indicator of the hydrophilicity of materials. The heat of wetting of TiO2, a preferred photocatalyst, is between 320 and 512 x 10^-3 Jm^-2 paralaformaanatasayentre293y645x10^-3 Jm^-2for the rutile form. For this reason, compounds having a heat of wetting greater than 500 x 10 are preferred.^-3 Jm^-2. In addition to the three previous metal oxides, GeO2, ThO2 and ZnO can be used. These metal oxides can be in crystalline form and also in amorphous form. Their particle diameter is below 0.1 µm. It is found that the addition of SiO₂ contributes to improving surface hardness. Replacing a part of the amount of SiO2 with K2O or Li2O could improve the surface hardness even when the baking temperature is low. In particular, when TiO2 / (total solid amount of agent that imparts or regulates hydrophilicity) is> 0.5 and SiO₂/ (total solid amount of agent that imparts or regulates hydrophilicity) is <0.5, the above effect can be expected.

The improvement of the superhydrophilic activity is described below for a painted type tile of the ninth example.

Ε8 2 209 182 T3 by adding another ingredient (metal oxide), which helps to improve the hydrophilicity of TiO2, for example SiO2 or Al2O3 and to improve other functions (improvement of surface hardness).

(i) Preparation of photocatalyst and metal oxide sols

Photocatalytic material / TiO2 sol: (TA-15, manufactured by Nissan Chemical Industries Ltd.).

Also in this ninth example a SiO2 sol is used together with the anatase form of TiO2 sol which is harmless, chemically stable and cheap. Other crystalline, photocatalytically active TiO2, SrTiO3, ZnO, SiC, GaP, CdS, CdSe, MoS3, V2O5, WO3, SnO2, Bi2O5 and Fe2O3 can also be used as alternative materials.

SiO2 / Metal Oxide Sol: (Glasca T2202, manufactured by Japan Synthetic Rubber Co., Ltd.).

Sun of Al₂OR₃: mean particle diameter from 0.01 µm to 0.1 µm (Alumina Sol 200, boehmite form, manufactured by Nissan Chemical Industry Ltd.).

Ε1 SiO₂ used is a commercial product. A film-forming element containing a silicone (an organopolysiloxane) or a previous silicone synthesis product can also be used. Commercial products can also be used for the TiO2 and Al2O3 sols. However, as in the eighth example, these sols can be obtained through the previous steps, for example the addition of a hydrolysis inhibitor, such as hydrochloric acid or ethylamine, to a metal alkoxide as Starting material.

(ii) Preparation of materials that confer hydrophilicity

The starting materials are mixed together in a given ratio. The mixture is diluted three times with ethanol to prepare the coating liquid. The formulation of the coating liquid is as follows.

TABLE 6

<td>TiO2</td><td>SiO2</td><td>^{To the}2^OR3</td>

<td> 1</td><td> 1/10</td><td>from 0 to 1/12</td>

<td> 1</td><td> 1/5</td><td>from 0 to 3</td>

<td> 1</td><td> 1/2</td><td>from 0 to 3</td>

<td> 1</td><td> 1</td><td>from 0 to 3</td>

<td> 1</td><td> 2</td><td>from 0 to 3</td>

<td> 1</td><td> 5</td><td>from 0 to 3</td>

(iii) Preparation of hydrophilizable tiles

As in the eighth example, a glazed tile is prepared as a substrate and a coating liquid is applied by centrifugation on the substrate. Dry the coated substrate in an oven at 150 ° C for 30 min to crosslink the coating. Although spin coating is used in the ninth example, it is also possible to use liquid coating, spray, dip, roll, brush, and other methods. Apart from tiles, metals, ceramics, pottery materials, glass, plastics, wood, stones, cements, concretes and combinations or laminates of the previous substrates can also be used as substrates of the ninth example. In this ninth example, those described above in relation to the preparation of sols are used as sols and, as specified in Table 6, the ingredients are TiO2, SiO2 and optionally Al2O3. Therefore, the surface layer is a two or three component system of a combination of photocatalyst, the amphoteric or basic or acid metal oxide, typified as alumina, and the other compound (oxide), for example silica, described in the fourth example.

(iv) Evaluation

For the tiles of the ninth example and the comparative tile, a pencil hardness test is carried out (general tests of paints specified in the JIS K 5400 standard). The results are shown in Table 7. For hydrophilicity, the static contact angle of the tiles of the ninth example and of the comparative tile with water is measured in the way already explained in the eighth example. The results are shown in table 8. In this case, the intensity of the ultraviolet radiation is 1.2 mW / cm² and the period of ultraviolet irradiation is 12 h.

ES 2 209 182 T3

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As can be seen from Table 7, when SiO2 / TiO2 is less than 0.1, the amount of binder (SiO2 sol) is not satisfactory, leading to low surface resistance. In addition, it can be seen in table 8 that, when Al2O3 / TiO2 is a value between 1/12 and 2, with SiO2 / TiO2 being a value between 1/5 and 2, an effect of improving hydrophilicity is developed due to the addition of alumina. As described in the eighth example, this effect is considered to be generated by the hydrophilic nature of Al2O3. The heat of wetting can be mentioned as an index of the hydrophilicity of materials. The heat of wetting of TiO2, a preferred photocatalyst, is between 320 and 512 x 10^-3 Jm^-2 for the anatase form and between 293 and 645 x 10^-3 Jm^-2 for the rutile form. For this reason, compounds having a heat of wetting greater than 500 x 10 are preferred.^-3 Jm^-2 . Also in this example, in addition to the three previous metal oxides, GeO2, ThO2 and ZnO can be used. These metal oxides can be in crystalline form and also in amorphous form.

The present invention has been described with reference to examples, but it is obvious that the present invention is not limited to the above examples and embodiments and variations and modifications can be made within the scope of the claims.

Εδ 2 209 182 T3

For example, to anchor the copper particles, an oxide thereof, etc., on a tile to achieve a tile that has a complementary antimicrobial activity, a method can be used that consists of the previous production of a tile that has a surface layer of a photocatalyst formulation, by coating the surface of the tile with a Ti / Al sol and oven drying the coated tile and then coating the surface layer of the tile after baking with a third sol.