Titanium oxide particle, hydrophilic paint, hydrophilic coating film layer, and building material

The present invention relates to titanium oxide having suppressed organic matter resolution, a hydrophilic coating material using the same, a hydrophilic coating layer formed on the surface of a base material by the hydrophilic coating material, and a building material using the base material. The present invention also relates to a technique for enhancing the hydrophilicity and hydrophilization ability of a base material by the hydrophilic coating film layer to impart long-term antifouling performance to the base material.

Titanium oxide is excited when irradiated with ultraviolet light having an energy equal to or higher than the bandgap to generate electrons and holes, which act on water molecules to generate OH radicals and decompose organic substances.

Therefore, titanium oxide has been used for antifouling and purification from various angles, and its research has been conducted. Regarding antifouling, a film containing titanium oxide is formed by a sol-gel method, a solid phase reaction, a gas phase reaction, etc., and antifouling of building materials, cars, etc. is performed.

The paint used for forming a coating film containing crystalline titanium oxide includes a titanium oxide powder slurry, a sol prepared by hydrolyzing a salt aqueous solution of titanium oxide or titanium alkoxide, and an amorphous state in which titanium is in a peroxide state. There are a titanium oxide sol solution in which titanium oxide particles are present, a metal sol solution in which crystalline titanium oxide is present as particles, and the like.

In the process of preparing these paints, the crystalline titanium oxide particles are doped with other metals. Due to this doping, the band cap energy of titanium oxide is displaced, and titanium oxide is excited even in the wavelength range of visible light, and exhibits hydrophilicity and organic matter resolution. However, since holes and electrons tend to collect in the doped metal, there is also an aspect that the holes and electrons bond with each other and disappear, and the activity of decomposing organic substances cannot be maintained.

Titanium oxide has a high photocatalytic activity among metal oxides, and anatase type, blue anatase type, and rutile type are known as its crystal phase, and the stable crystal phase produced at the lowest temperature is the anatase type.

For example, Non-Patent Document 1 discloses a method for producing vanadium or niobium-doped titanium oxide particles (amorphous titanium oxide particles, crystalline titanium oxide ultrafine particles). In this production method, aqueous ammonia and hydrogen peroxide are added to an aqueous solution of titanium tetrachloride containing vanadium (V) or niobium to cause a hydrothermal reaction, and peroxotitanic acid (HO-) containing vanadium or niobium is produced. (NbO₅) n- (TiO₅) m-OH, m> n or HO- (VO₅) p- (TiO₅) Q-OH), q> p) amorphous molecules are formed, and an aqueous solution of this peroxo-state composite metallic acid is refluxed at 100 ° C for 8 hours to be doped with vanadium or niobium. The technical content of forming ultrafine particles of crystalline titanium oxide which is nanometer is disclosed.

On the other hand, in Patent Document 1, a surface layer containing titanium dioxide particles and binder-derived silica is formed on the surface of the base layer of a mirror, lens, glass, prism or other transparent member via an acrylic silicon resin layer. By doing so, the technical content of maintaining the surface of the underlying layer with a high degree of hydrophilicity for a long period of time is disclosed. Specifically, as shown in FIG. 6, titanium oxide particles are embedded in the surface layer so as to be scattered. In the surface layer, the portion other than the titanium oxide particles is composed of silica formed by dehydration polycondensation of the silicon precursor, and the surface layer is not extremely eroded by the organic matter resolution of the titanium oxide particles.

The problem to be solved

However, in the latter case of Patent Document 1, as shown in FIG. 6, the particles of titanium oxide embedded in the silica portion in the surface layer are, depending on the particles, the acrylic silicon resin at the interface between the acrylic silicon resin layer and the surface layer. Since the particles are fixed in contact with the layer, when the titanium oxide particles are photoexcited and exhibit organic resolution, the acrylic silicon resin at the contact portion is eroded.

For this reason, there is a problem that the light reflection is not uniform due to the unevenness of the eroded portion and the appearance of the base layer is deteriorated, and there is a problem that the surface layer is easily peeled off.

On the other hand, in the former non-patent document 1, titanium oxide is doped with vanadium for the purpose of making crystalline titanium oxide particles excited even in the visible light region and improving organic matter resolution and hydrophilicity. (Effect of increasing organic matter resolution, etc.) has not been obtained, and no further studies have been conducted on vanadium-doped titanium oxide.

Further, when an attempt is made to bind crystalline titanium oxide using a general organic resin binder, the surface layer is eroded over time because the binder is organic, and the appearance of the base material is changed. It deteriorates and the surface layer is easily peeled off.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide titanium oxide particles which are used as a component of a hydrophilic coating material and whose organic matter resolution is suppressed so as to reduce the above-mentioned erosion.

<p><patcit num="1"><text>Patent No. 3087682</text></patcit></p>

<p><nplcit num="1"><text>Hiromichi Ichinose, Improvement of Titanium Oxide Coating Agent and Application to Environmental Purification, [online], 3. Research Report P.85-89 2002 Research Report, Saga Ceramics Technology Center, [September 3, 2009 Day search], Internet &lt;URL: http://www.scrl.gr.jp/research/reports/h14/h14titancoat.pdf&gt;</text></nplcit></p>

<p> As a result of diligent studies, the present inventors have improved the organic matter resolution (resulting in organic matter decomposition activity) of the titanium oxide particles by containing a predetermined amount of vanadium in the crystalline titanium oxide particles having organic matter resolution. We have found that the above problems can be solved by adjusting the direction of suppression, and have completed the present invention.</p><p> That is, the titanium oxide particles according to the present invention are crystalline titanium oxide particles that are components of a hydrophilic coating material, and are in a photoexcited state when a film composed of the titanium oxide particles contains a predetermined amount of vanadium. It is characterized by having a contact angle with water of 25 ° or less and a methylene blue decomposition rate of 40% or less.</p><p> The amount of vanadium mixed may be 1 to 10 mol% with respect to the total molar amount of titanium and vanadium used for forming the titanium oxide particles.</p><p> The hydrophilic coating material according to the present invention contains at least the titanium oxide particles described above, and may further contain a binder. This binder binds at least the titanium oxide particles to a base material to which the hydrophilic paint is applied. The base material is one to which a hydrophilic paint is applied.</p><p> The binder may be a silicon compound. This silicon compound is, for example, a silicon precursor, which forms a silane oligomer by a siloxane bond through hydrolysis and condensation.</p><p> The building material according to the present invention is characterized by having the above-mentioned hydrophilic coating film layer.</p>

<p> The titanium oxide particles according to the present invention are crystalline titanium oxide particles that are components of a hydrophilic coating material, and contain a predetermined amount of vanadium. The content of this vanadium is such that when a film is formed using only the titanium oxide particles and the film-shaped titanium oxide particles are irradiated with light to be in a photoexcited state, the contact angle between the film and water is 25 ° or less. Moreover, the amount of vanadium is such that the decomposition rate of methylene blue is 40% or less.</p><p> Therefore, when a hydrophilic coating film using various binders is used to form a hydrophilic coating film layer on a base material, titanium oxide particles are based on the interface between the base material surface and the hydrophilic coating film layer. Even if it is in contact with the material, the organic matter resolution of the titanium oxide particles themselves is suppressed, so that the erosion of the base material is suppressed. Therefore, deterioration of the appearance of the base material due to erosion and peeling of the hydrophilic coating film layer are unlikely to occur.</p><p> Although the hydrophilicity of the titanium oxide particles is reduced by containing vanadium, the amount of the vanadium mixed is 1 to 10 mol% with respect to the total molar amount of titanium and vanadium used for forming the titanium oxide particles. If the amount is large, the hydrophilicity of the titanium oxide particles will not be extremely reduced, and a high effect of suppressing the resolution of organic substances can be obtained.</p><p> Specifically, when the amount of vanadium contained in the titanium oxide particles exceeds 10 mol%, the effect of suppressing the organic matter resolution of the titanium oxide particles is hardly enhanced even if the amount of vanadium is increased, and the effect of suppressing the organic matter resolution is obtained. The correlation with the amount of vanadium is low. Further, when it exceeds 10 mol%, the rate of decrease in hydrophilicity of the film increases with respect to the amount of increase in vanadium with respect to the contact angle between the film containing only titanium oxide particles and water, and the amount of vanadium and hydrophilicity increase. The correlation of decrease is high.</p><p> Further, when the amount of vanadium contained in the titanium oxide particles is less than 1 mol%, the decrease in hydrophilicity is small, but the effect of suppressing the resolution of organic matter is not sufficient.</p><p> The hydrophilic coating material according to the present invention contains at least the titanium oxide particles, and further contains a binder, for example, when the binder has an organic substituent R or an organic polymer chain. Even if the titanium oxide particles in the hydrophilic paint are excited by some irradiation light while the hydrophilic paint is stored, the organic matter resolution is suppressed as described above, so that the organic substituent R and the organic height are high. Difficult to decompose molecular chains. Therefore, the organic binder is less likely to deteriorate in quality, the binding force is less likely to be lowered, and the quality of the hydrophilic paint is less likely to be deteriorated.</p><p> Further, since the binder is amorphous metal oxide particles, the hydrophilicity of the hydrophilic coating film layer is improved in many cases, and therefore, even a smaller amount of titanium oxide particles have the same self-cleaning ability. Is obtained. Therefore, the number of titanium oxide particles in the hydrophilic coating material can be reduced, and the erosion of the base material by the titanium oxide particles can be further suppressed.</p><p> If the amorphous metal oxide particles are titanium oxide amorphous particles, a binder can also be produced in the same production process.</p><p> The hydrophilic coating film formed by using the hydrophilic coating material containing a binder has lower hydrophilicity and organic matter resolution suppressing effect than the film made of titanium oxide, but the metal oxide particles: the weight of the titanium oxide particles. If the ratio is 25:75 to 0: 100, the contact angle with water and the methylene blue decomposition rate tend to be 40% or less when the hydrophilic coating film is used, even when the binder is included. It becomes.</p><p> The hydrophilic coating film layer according to the present invention is characterized in that it is formed on the surface of a base material by using the above-mentioned hydrophilic coating material. Therefore, in the hydrophilic coating film layer according to the present invention, even if the titanium oxide particles in the hydrophilic coating film layer are in contact with the base material at the interface between the substrate surface and the hydrophilic coating film layer, the titanium oxide particles themselves Since the organic matter resolution of the substrate is suppressed, the erosion of the base material is suppressed. Therefore, deterioration of the appearance of the base material due to erosion and peeling of the hydrophilic coating film layer are unlikely to occur.</p><p> Since the building material according to the present invention is a building material having the above-mentioned hydrophilic coating film layer, it is difficult to shorten the life as a building material due to the above-mentioned effect.</p><p> For example, when a general building material has an organic base material portion, a layer containing crystalline titanium oxide particles is directly applied onto the organic base material to form the building material, as described above. The base material is eroded by the decomposition of organic substances by the crystalline titanium oxide particles, and the life of the building material is shortened. However, in the case of the building material according to the present invention, a predetermined amount of vanadium is mixed in the titanium oxide particles. Therefore, the above-mentioned erosion is prevented, and the hydrophilicity as the antifouling performance and the organic matter resolution (self-cleaning ability) are sacrificed to some extent, but the life of the building material is not shortened as described above.</p>

<figref num="1A">It is a figure which showed the steps 1 and 2 of the method of preparing the coating agent (hydrophilic paint) which concerns on embodiment of this invention in the order of steps.</figref><figref num="1B">It is a figure which showed the steps 3 to 5 of the method of preparation | preparation of the coating agent which concerns on embodiment of this invention in the order of steps.</figref><figref num="1C">It is a figure which showed the steps 6 and 7 of the method of preparing a coating agent which concerns on embodiment of this invention in the order of steps.</figref><figref num="2">(A) It is explanatory drawing which shows the movement of an electron and a hole when vanadium (V) is not contained. (B) It is explanatory drawing which shows the movement of an electron and a hole when vanadium (V) is contained.</figref><figref num="3">It is a figure which showed the band cap energy, hydrophilicity and organic matter resolution of each metal oxide.</figref><figref num="4">(A) The methylene blue decomposition rate [%] (organic matter resolution) of the film formed only by anatase particles (titanium oxide particles) according to the amount of vanadium mixed is shown. (B) The contact angle (°) of the film formed only by anatase particles with respect to water according to the amount of vanadium mixed is shown.</figref><figref num="5">(A) Fig. 4 shows the suppression of organic matter resolution (methylene blue decomposition rate) when an amorphous solution (binder) of titanium oxide is mixed with crystalline titanium oxide at a predetermined solid content ratio to form a hydrophilic coating film layer. is there. (B) It is a figure which shows the hydrophilic ability (contact angle with water) about the hydrophilic coating film layer of (A).</figref><figref num="6">It is sectional drawing of the conventional hydrophilic coating film layer.</figref>

The crystalline titanium oxide particles such as the anatase particles according to the present invention are crystalline titanium oxide particles which are components of a hydrophilic coating material, and contain a predetermined amount of vanadium to form a film composed of the titanium oxide particles. Titanium oxide is sometimes in a photoexcited state, and the contact angle between the film and water is 25 ° or less, and the methylene blue decomposition rate is 40% or less.

For example, when a hydrophilic coating layer is formed on the surface of an organic base material with a coating material containing anatase particles, a part of the anatase particles dispersed in the hydrophilic coating layer comes into contact with the base material, so that the anatase particles are photoexcited. When this is done, unnecessary decomposition of the base material occurs at the contact point, but in the present invention, by mixing vanadium with the anatase particles, the organic matter decomposition activity of the anatase particles is adjusted and the unnecessary base material is decomposed. Decomposition can be suppressed.

When the surface of the base material is decomposed, fine irregularities are generated on the surface of the base material, and the light reflection on the surface of the base material is not uniform, so that the appearance of the base material is deteriorated. Decomposition of the surface can be suppressed and deterioration of the appearance of the base material can be prevented.

Regarding the amount of vanadium to be mixed, it is desirable that the anatase particles are contained in a molar amount of 1 to 10 mol% with respect to the total molar amount of titanium and vanadium used for forming the anatase particles.

When the molar amount of vanadium is less than 1 mol%, the effect of suppressing the organic matter resolution of the anatase particles becomes low as described above. Further, when it is higher than 10 mol%, the correlation between the effect of suppressing the organic matter resolution and the amount of vanadium becomes low as described above, while the correlation between the amount of vanadium and the decrease in the hydrophilicity of titanium oxide becomes high, which is not preferable. Further, since the brown color of the hydrophilic coating film layer is increased, the color reproducibility of the base layer is lowered.

When vanadium in an amount in the range of more than 10 mol% is mixed with the titanium oxide particles, the effect of suppressing the organic matter resolution of titanium oxide can be obtained, but the color is very tinted. In this case, vanadium is mixed. It is also possible to obtain an acceptable color by reducing the thickness of the hydrophilic coating layer according to the amount and applying an extremely thin coating.

As the vanadium source to be mixed with titanium oxide, vanadium compounds such as vanadium chloride, vanadium hydroxide, vanadium sulfide, and vanadium iodide can be used.

The hydrophilic coating material according to the present invention contains at least the titanium oxide particles and further contains a binder, for example, when the binder has an organic substituent or an organic polymer chain, the hydrophilic coating material. Even if the titanium oxide particles in the hydrophilic coating material are excited by some kind of irradiation light during storage, the organic matter resolution of the titanium oxide particles is suppressed as described above, so that the organic system of the binder is replaced. It is difficult to decompose the group R and organic polymer chains. Therefore, the binder is less likely to deteriorate in quality, the binding force is less likely to be lowered, and the quality of the hydrophilic paint is less likely to be deteriorated.

In addition, since vanadium serves as an electron / hole recombination site (see Fig. 2), if the binder is radically polymerized, its rate can be adjusted. That is, even if the titanium oxide contained during the storage of the hydrophilic coating material is excited, radical polymerization is not unnecessarily started. Therefore, the hydrophilic paint has high storage stability.

The hydrophilic coating film layer according to the present invention is characterized in that it is formed on the surface of a base material by using the above-mentioned hydrophilic coating material. Therefore, in the hydrophilic coating film layer according to the present invention, even if the titanium oxide particles are in contact with the base material at the interface between the surface of the base material and the hydrophilic coating film layer, the organic matter resolution of the titanium oxide particles themselves is suppressed. Therefore, the erosion of the base material is suppressed. Therefore, deterioration of the appearance of the base material due to erosion and peeling of the hydrophilic coating film layer are unlikely to occur. Therefore, the hydrophilic coating film layer is stronger than the conventional product and is hard to peel off.

Since the building material according to the present invention is a building material containing the hydrophilic coating film layer, the life of the building material is not shortened or the appearance is not deteriorated due to the problem of erosion of the base material.

The hydrophilicity in the present invention means that the film made of titanium oxide is irradiated with light and the vanadium-containing anatase particles inside the coating film are excited to exhibit water wettability of 25 ° or less in terms of contact angle with water. The state. If it has a hydrophilic ability of 25 ° or less in terms of the contact angle with water, the self-cleaning performance (self-cleaning ability) of the surface when it is made into a hydrophilic coating film layer on the exterior etc. can be fully exhibited.

&lt;Irradiance&gt; As a light source for light irradiation that makes the hydrophilic coating film layer hydrophilic, ultraviolet rays and a part of visible light wavelengths contained in a light source such as the sun can be used. The illuminance in this case is 0.001 mW / cm² More than that is fine, but 0.01mW / cm² The above is preferable, 0.1 mW / cm²The above is more preferable.

&lt;Base material&gt; The base material applicable to the present invention may be any as long as it can be used as a building material and the hydrophilic paint according to the present invention can be uniformly applied.

As the organic base material, a base material containing an organic polymer polymer can be used. For example, an organic polymer such as acrylic silicon type, acrylic urethane type, polyolefin type, polyether type, or fluorine type can be used. it can. In this case, if the coating agent is hydrophilic enough to prevent the formation of striped droplets on the surface of the base material when the coating agent is applied, it is more preferable because it can be applied more evenly.

Examples of the acrylic silicone resin include a composite of a silicone resin and an acrylic resin and block copolymerization, a composite of a polymethacrylate resin and a silicone resin, and the like. As this silicone-based resin, a silicone resin, an alkyd-modified silicone resin, a urethane-modified silicone resin, a polyester-modified silicone resin, an epoxy-modified silicone resin, or the like can be used.

&lt;Binder&gt; The binder applicable to the present invention may be any binder that binds anatase particles to the organic base material, and the inorganic binder includes amorphous particles of metal oxide, alumina, silica (silicon compound), and the like. A silicon precursor (silicon compound) or the like can be used.

As the organic binder, acrylic silicon-based, acrylic urethane-based, polyolefin-based, polyether-based, fluorine-based, or the like can be used.

Amorphous particles may be precursors of anatase particles that crystallize when heated to form anatase particles. In this case, the binder can also be manufactured in the same manufacturing process. The amorphous particles in this case may contain vanadium in the same proportion as the above-mentioned formation of anatase particles with respect to the molar amount of titanium used for forming the amorphous particles.

The silicon precursor forms a silane oligomer by siloxane bond through hydrolysis and condensation, and by including it as a composition of the coating agent, for example, the pH of this coating agent is set to the acidic or alkaline side, or heat treatment is performed. As a result, a hydrolyzate containing a silanol SiOH group is formed from the silicon precursor, and this is dehydrated and polycondensed on the surface of the organic substrate, so that titanium oxide particles such as anatase particles are integrally contained. Adheres to organic substrates. At this time, the titanium oxide particles are fixed to the surface of the organic base material in a state of being in contact with each other at a plurality of places.

Methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, ethyltripropoxysilane, phenyl Trimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane, phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldibutoxy Silane, diethyldipropoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylmethyldibutoxysilane, phenylmethyldipropoxysilane, γ-glycidoxypropyltrimethoxysilane, and their hydrolyzates, mixtures thereof. Can be preferably used.

When the above-mentioned silicon compound is used as the binder, the hydrophilicity of the formed hydrophilic coating film layer is improved, so that the contact angle of the coating agent with water when a general organic paint is used as the binder It decreases in comparison.

&lt;Additives&gt; If a surfactant is added to the coating agent, the surface tension is lowered, so that the coating agent is less likely to be repelled on the surface of the organic base material at the time of application, and the coating agent can be applied evenly and evenly.

The surfactant may be any water-soluble solvent, and anionic, cationic ionic molecules, nonionic nonionic molecules and the like can be used. For example, monoalcohols such as methanol, ethanol and propanol, and dialcohols such as ethylene glycol, propylene glycol and propylene glycol can be used. In addition, methyl cellosolve, cellosolve, and butyl cellosolve cellosolves can also be used.

Further, when the coating agent has a substantially inorganic composition, when it is applied to an organic base material, even if a coupling agent is added to the coating agent in order to improve the adhesion of the formed hydrophilic coating film layer to the base material. Good. As the coupling agent, for example, a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent can be used. The formed substantially inorganic hydrophilic coating film layer is more firmly bonded to the surface of the organic base material by this coupling agent.

Further, a matting agent may be added to the coating agent in order to matte the hydrophilic coating film layer and improve the appearance. As the matting agent, extender pigments such as kaolin, talcite, alumina, hydrotalcite, benton, barium sulfate, and calcium carbonate and clays can be used. Next, a method of mixing vanadium into the anatase particles and a method of forming a hydrophilic coating film layer will be described.

When vanadium is mixed with anatase particles, the method basically follows the manufacturing method described in "Hiromichi Ichinose," Improvement of Titanium Oxide Coating Agent and Application to Environmental Purification "" (Non-Patent Document 1). According to this document, the average particle size of anatase particles contained in this sol is estimated to be in the range of 40 nm or less.

The specific procedure is described in [Step 1] to [Step 7] described later. Of these, [Step 1] to [Step 5] are examples of methods for preparing anatase particles mixed with vanadium, such as hydrogen peroxide solution in an aqueous solution containing the respective hydroxides of titanium and vanadium in a predetermined ratio. The oxidizing agent of the above is added, and the reaction caused by this addition forms amorphous particles containing the titanium and the vanadium in the same molecule, and further forms anatase particles from the amorphous particles.

Hereinafter, an example thereof will be described with reference to FIGS. 1A to 1C, and further, a method for preparing a hydrophilic coating material and formation of a hydrophilic coating film layer will be described. The specific numerical values in the description are examples and are not limited thereto. [Process 1]: Raw material preparation Titanium source, vanadium source, etc. are prepared as raw materials used in step 2 and subsequent steps described later.

First, the volume of the amorphous solution or anatase solution to be finally prepared is determined, and the final concentration of titanium contained in the solution (for example, 0.5% by weight) and the molar amount of titanium (for example, 0.1 mol) are determined. A titanium chloride aqueous solution containing a molar amount is prepared as a titanium source. It is easier to prepare the coating agent later when the molar amount of titanium is the same in both the case of preparing the amorphous solution and the case of preparing the anatase solution.

Further, for example, vanadium oxide (0.0005 to 0.005 mol) containing a molar amount of vanadium (0.001 to 0.01 mol of vanadium in the above example) which is 1 to 10 mol% with respect to the total molar amount of titanium and vanadium described above is prepared. To do.

In addition, ammonia water for neutralization and ammonia water for preparing a vanadium solution are prepared. The molar amount of ammonia in the ammonia water for preparing the vanadium solution is less than or equal to the molar amount of ammonia finally used for neutralization, and an arbitrary molar amount is added to set the pH at the start of pH adjustment. Can be done.

Then, as shown in FIG. 1A, a compound containing vanadium (vanadium oxide in the above example) is dissolved in aqueous ammonia for preparing a vanadium solution and appropriately diluted with distilled water (in the above example, the vanadium oxide concentration is 0.9% by weight). %) To obtain a vanadium solution.

Further, since titanium chloride is strongly acidic, distilled water may be mixed with the titanium chloride aqueous solution to dilute it. [Step 2]: Precipitation In step 2, each solution prepared in step 1 is mixed to form a precipitate (gel).

First, a vanadium solution and aqueous ammonia for neutralization are mixed, and the entire amount of this solution is gradually added to the titanium chloride aqueous solution. After that, the pH is further adjusted with aqueous ammonia, preferably pH 2 to 6 when preparing high-viscosity amorphous particles, and pH 7 when preparing anatase particles.

As a result, a precipitate (gel) in which titanium hydroxide and vanadium hydroxide are mixed is obtained (see step 2 in FIG. 1).

Here, when the vanadium solution and the ammonia water are mixed, the amount of vanadium contained can be adjusted by adjusting the amount of the vanadium oxide solution to be mixed. [Step 3]: Removal of unnecessary ions (cleaning)

Next, in step 3, as shown in FIG. 1B, distilled water is added to the precipitate (gel) in step 2 and washed with water to remove the supernatant. This washing with water is repeated until the conductivity of the supernatant is 10 μs / cm or less. This is because when the conductivity exceeds 10 μs / cm, crystallization is difficult to proceed when the subsequent step 5 is performed. After washing with water, the amount of water required to reach the final solution concentration (Ti 0.5% by weight in the example) is added to the weight of the precipitate (gel) (not shown). [Step 4]: Dissolution of gel (preparation of amorphous solution) Next, in step 4, an oxidizing agent such as hydrogen peroxide is added to the precipitate (gel) washed in step 3 and dissolved to obtain an amorphous solution.

First, an oxidizing agent such as hydrogen peroxide, which has a molar amount about 10 times the molar amount of titanium, is added to the precipitate (gel) obtained by discarding the supernatant water in step 3 with water added.

As a result, an amorphous solution (in the above example, an amorphous solution containing 0.1 mol of titanium and 0.001 to 0.01 mol of vanadium) is obtained.

Here, when preparing an amorphous solution for forming anatase particles, it is preferable to prepare under the following conditions.

Specifically, the temperature of the mixture of the precipitate (gel) and distilled water in step 3 is adjusted to a low temperature of, for example, around 5 ° C, and while maintaining this temperature in a constant temperature bath or the like, an oxidizing agent such as hydrogen peroxide solution is used. Is added. After that, the precipitate (gel) is stirred until it melts into a transparent solution showing orange to yellow color, taken out from a constant temperature bath and left at room temperature, so that the amorphous solution has a low viscosity like water and is suitable for forming anatase particles. A solution is obtained.

[Step 5]: Crystallization Next, the amorphous solution for anatase particles prepared in step 4 is further maintained at a temperature of, for example, around 100 ° C. and refluxed for 1 hour (h) to 70 hours (h) to crystallize the amorphous particles and vanadium. (In the above example, the amorphous particles containing 1 to 10 mol% of vanadium with respect to the total molar amount of titanium and vanadium in the particles) containing the amorphous particles are obtained. ..

Further, as another method for obtaining anatase particles containing vanadium, an amorphous solution containing no vanadium is prepared through steps 1 to 4 without using a vanadium solution, and in the step 5 of the above-mentioned vanadium compound. There is also a method of adding a solution and continuing reflux to contain vanadium, but from the viewpoint of uniformly containing vanadium, it is preferable to use a vanadium solution from the stage of step 2.

[Step 6]: Preparation of coating agent Next, as shown in FIG. 1C, a coating agent (hydrophilic paint) is prepared from anatase solution, water, (optionally a binder, an additive). When a binder is included, the coating agent is prepared in consideration of the solid content ratio of both the anatase solution and the binder. The hydrophilicity of the hydrophilic coating film layer can also be adjusted by this solid content ratio. The total weight% of the anatase particles and the binder with respect to the coating agent can be a general composition as described later, and can be arbitrarily changed.

[Step 7]: Coating The hydrophilic coating film layer according to the present invention is a coating film formed by using the coating agent, and its thickness is preferably less than 20 μm. It is not preferable to apply a thick coat of 20 μm or more because it will be colored and will be noticeable when cracks occur.

Also, it can be applied as thinly as possible. The range that can be thinly coated depends on the hydrophilicity of the organic base material or the inorganic base material on which the hydrophilic coating layer is formed, and changes depending on the material of the organic base material or the inorganic base material. An organic base material or an inorganic base material which is highly hydrophilic and easy to coat is preferred.

The coating agent can be applied to an organic base material or an inorganic base material by a method such as spray coating, dipping, spin coating, brush coating, or bell coating. (Drying of coating film) Regarding the drying of the hydrophilic coating film layer after coating, any drying method that does not adversely affect the coating film or the organic base material, such as a temperature range that does not deteriorate the base material in the case of an organic base material, is used. It may be dried by the method.

(Evaluation of organic matter resolution, evaluation of hydrophilicity) The hydrophilic coating film layer includes both a coating film containing only titanium oxide particles and a coating film containing other binder components. The organic matter resolution and hydrophilicity of these hydrophilic coating layers can be evaluated according to the above-mentioned "Photocatalyst Product Technology Council Regulations / Regulations and Test Method June 2005".

Regarding the investigation of the decomposition of the base material at the interface between the base material and the hydrophilic coating film layer, one of the titanium oxide particles on the surface of the hydrophilic coating film layer has the same frequency as the interface of the hydrophilic coating film layer. Since the portion is exposed, the organic matter resolution at the interface can be roughly known by examining the hydrophilicity and the organic matter resolution on the surface of the hydrophilic coating film layer.

Here, to be more precise, mW / cm at the interface and the surface depends on the parameters (film thickness and haze value) of the hydrophilic coating film to be formed.²May be measured to create a correction factor, thereby correcting the evaluation value of the organic matter resolution on the surface.

<p> Examples and comparative examples of the present invention are shown below, and the present invention will be described in more detail, but the present invention is not limited to these examples and the like. In FIG. 4, the vanadium mixed amount (mol%) indicates the molar amount (mol%) of vanadium used with respect to the total molar amount of titanium and vanadium used for forming anatase particles. [Example 1] In Example 1, anatase particles were formed using about 0.1 mol of titanium (Ti) and about 0.001 mol of vanadium (about 1 mol% of the molar amount of titanium). Then, a coating agent was prepared and applied to a base material to form a hydrophilic coating film layer, and the organic matter resolution and hydrophilicity of this hydrophilic coating film layer were evaluated.</p><p> The specific procedure (steps 1 to 7, coating, measurement of organic matter resolution and hydrophilicity) will be described below. [Process 1]: Raw material preparation I prepared the following items. Solution A: Titanium chloride aqueous solution (titanium source) (Made by Wako Junyakusha, TiCl₄Contains 16.5 ± 0.5% by weight of aqueous solution and titanium (Ti)) Solution B: Ammonia water (ammonia source) (Made by Wako Junyakusha, NH₄OH aqueous solution, ammonia (NH₃) Containing 25 ~ 27.9 ± 0.5% by weight) Solution C: Vanadium solution (vanadium source) (Contains 95% by weight or more of vanadium oxide) Liquid D: Hydrogen peroxide solution (hydrogen peroxide source) (Manufactured by Wako Pure Chemical Industries, hydrogen peroxide aqueous solution, 30.0 to 35.5% by weight) Liquid E: Vanadium solution (vanadium oxide approx. 0.9% by weight) For liquid E, vanadium solution (manufactured by Wako Pure Chemical Industries, Ltd., V)₂O₅(Contains 95% by weight or more) 3.6 g (about 0.02 mol as vanadium) and solution B ammonia water (Wako Pure Chemicals NH₄OH aqueous solution, NH₃18.0 g (about 0.02 mol as ammonium ion) and 378.4 g of distilled water were mixed to prepare a mixture containing about 0.9% by weight of vanadium oxide.</p><p>[Step 2]: Formation of precipitate (gel) In a 3 L beaker, 30 g of titanium chloride solution (solution A) (about 0.1 mol as titanium) and 60 g of distilled water were mixed. Separately, ammonia water (Liquid B) was diluted with distilled water (about 140 g) to a concentration of 2.5% by weight. Diluted aqueous ammonia (about 0.074 mol) was mixed with about 10.54 g (about 0.001 mol) of vanadium solution (solution E). The entire volume of this solution was mixed with a 3 L beaker solution.</p><p> Furthermore, the pH was measured with a pH meter (HANNAHI 98129 COMBO1) every time 20 g of ammonia water (Liquid B) was added to a 3 L beaker. A precipitate (gel) was formed for the anatase particles at pH 7. [Step 3]: Removal of unnecessary ions (cleaning) Distilled water was added to each solution containing the precipitate (about 400 g each) at the end of step 2 to make 3 L, and the conductivity of the supernatant at this time was measured with a pH meter (HANNAHI 98129 COMBO1 or HORIBA, Ltd. B-173), and the supernatant was measured. Was removed. These operations were repeated until the conductivity of the supernatant of each solution became 10 μS / cm or less. [Step 4]: Preparation of amorphous solution The supernatant of each solution in step 3 was discarded, the weight of the precipitate (gel) was measured, and about 118 g (about 1 mol) of hydrogen peroxide solution (D solution) was prepared. Further, distilled water was added to the precipitate (gel) in consideration of the weight of the precipitate (gel) and the weight of hydrogen peroxide so that the titanium weight concentration was around 0.5%.</p><p> Regarding the preparation of an amorphous solution for forming anatase particles, the temperature of the mixture of the precipitate (gel) and distilled water from step 3 was adjusted to a low temperature of around 5 ° C, and this temperature was maintained in a constant temperature bath or the like. Hydrogen oxide water was added. After that, the mixture is stirred until the precipitate (gel) dissolves and becomes a transparent solution showing orange to yellow color, and the solution is taken out from a constant temperature bath and left at room temperature to obtain an amorphous solution for forming anatase particles having a low viscosity like water. Obtained. [Step 5]: Crystallization A 1 L flask was set in the mantle heater, the amorphous solution from step 4 was placed in this flask, and the amorphous solution was refluxed for 1 hour or more by constantly applying the amount of heat that the solution boils. As a result, the amorphous particles in the amorphous solution were crystallized to form anatase particles. This solution was designated as an anatase solution (ANA). This reflux was performed with a Dimroth condenser. [Step 6]: Preparation of coating agent The anatase solution of step 5 was used as a coating agent. [Step 7]: Coating After spreading 2 ml of the above coating agent on a commercially available slide glass (Matsunami Glass Industry Co., Ltd. S-1111 (length 76 mm x width 26 mm x thickness 0.8 to 1.0 mm)), spin coating method (500 r.pm 5 seconds, It was coated by 1,500 rpm (10 seconds). The slide glass was dried at room temperature. Coating and drying were repeated twice in total to form a film made of titanium oxide (titanium oxide film).</p><p>(Evaluation of organic matter resolution) Ultraviolet rays (1.0 mW / cm) for 3 hours on the titanium oxide film of this slide glass²) Is irradiated to prepare a test piece, and the photocatalyst performance evaluation test method I (liquid phase film adhesion method, 2001 version) described in "Photocatalyst Product Technical Regulations / Regulations and Test Method (June 2005)" is used. The organic matter resolution of the titanium oxide film (hydrophilic coating film layer) was evaluated (see Fig. 4 (A)).</p><p> The values in the table shown in FIG. 4 (A) represent the decomposition rate [%] of methylene blue when the substrate solution of methylene blue immediately after preparation is blank (decomposition rate 0%). (Evaluation of hydrophilicity) Five slide glasses coated with the above were prepared and left in a constant temperature and humidity room (dark place) with a humidity of 65% and a temperature of 23 ° C for 8 hours or more. Then, the slide glass left unattended was taken out from this constant temperature and humidity chamber. 1 μl of distilled water was dropped onto the titanium oxide film of each slide glass with a micropipettor or the like, and the contact angle between the titanium oxide film and water was measured. The hydrophilicity of the titanium oxide film was evaluated by taking the average of each measured value.</p><p> Kyowa Interface Science Co., Ltd. DM300 was used to measure the contact angle. This result was used as the contact angle of the titanium oxide film in a dark place (before irradiation) (see Fig. 4 (B)).</p><p> On the other hand, prepare another 5 slide glasses (same as above) coated in the same way, and apply ultraviolet rays (1.0 mW / cm) to this titanium oxide film for 3 hours in a dark place.²) Was irradiated. Then, 1 μl of distilled water was dropped onto the titanium oxide film after irradiation with a micropipettor or the like, and the contact angle between the titanium oxide film and water was measured. Regarding the measurement of the contact angle, the average of the measured values of each slide glass was taken and evaluated as the hydrophilicity of the titanium oxide film. Kyowa Interface Science Co., Ltd. DM300 was used for this measurement in the same manner as described above. This result was used as the contact angle of the titanium oxide film after irradiation (see Fig. 4 (B)). [Examples 2 to 6] By adjusting the amount of vanadium solution (liquid E) mixed in step 2 of Example 1, about 21.0 g (containing about 0.002 mol of vanadium) in Example 2 and about 31.6 g (about 31.6 g of vanadium) in Example 3. About 0.003 mol (including 0.003 mol), about 42.1 g in Example 4 (including about 0.004 mol of vanadium), about 52.7 g in Example 5 (including about 0.005 mol of vanadium), about 105.3 g in Example 6 (about 0.010 mol of vanadium) The coating, organic matter resolution, and hydrophilicity were evaluated in the same manner as in Example 1 except that (included) (see FIG. 4).</p><p> [Comparative example 1] The coating, organic matter resolution, and hydrophilicity were evaluated in the same manner as in Example 1 except that the vanadium solution (Liquid E) was not added in step 2 of Example 1 and the same amount of pure water was added instead. (Organic resolution of titanium oxide film) With reference to FIG. 4 (A), in the titanium oxide film formed without vanadium (0 mol%) (Comparative Example 1), the decomposition rate of methylene blue was 91.1% in the titanium oxide film after irradiation. ..</p><p> The hydrophilic ability is exhibited because OH groups are formed on the film surface by radicals generated by exciting titanium oxide in the titanium oxide film by irradiation. Therefore, as shown in FIG. 4 (B), irradiation is performed in Comparative Example 1. Since the contact angle with water is as small as 13.7 ° even before, in Comparative Example 1, a considerable amount of radicals are generated even in the normal state. Since organic matter decomposition also occurs due to radicals, it can be seen that it has organic matter resolution (not shown). In other words, this suggests that the surface of the organic substrate is gradually eroded.</p><p> On the other hand, as shown in FIG. 4 (A), vanadium in an amount of 1 to 5 or 10 mol% with respect to the total molar amount of titanium and vanadium used for forming anatase particles was used to form anatase particles. When vanadium was mixed, the methylene blue decomposition rate was 36.9% (Example 1), 27.6% (Example 2), 33.6% (Example 3), and 28.9% (Example 3), respectively, in each example after irradiation. 4), 19.6% (Example 5), which resulted in suppressing organic matter resolution.</p><p> Here, a high correlation was observed between the amount of vanadium and the decomposition rate of methylene blue when the amount of vanadium mixed was 1 to 10 mol% (Examples 1 to 6), which can be seen from FIG. 4 (A). In Example 6 in which vanadium was mixed at 10 mol%, the above correlation was low in the range exceeding 10 mol%, and even if vanadium was included in excess of 10 mol%, the effect was further increased. Can't be expected. Further, although not shown, the effect of suppressing the organic matter resolution is low when the content is less than 1 mol%.</p><p> From the viewpoint of suppressing the resolution of organic matter, it is preferable to mix vanadium in an amount of 1 to 10 mol%. (Hydrophilicity of titanium oxide film) With reference to FIG. 4 (B), in Comparative Example 1 of 0 mol% not mixed with vanadium, the contact angle with water before irradiation was 13.7 °, which was very small, and was 0 ° after irradiation. .. In Examples 1 to 5 in which vanadium was mixed in an amount of 1 to 5 mol%, the contact angles with water before irradiation were 47.2 ° (Example 1), 40.0 ° (Example 2), and 37.5 ° (Example 3), respectively. , 30.8 ° (Example 4) and 28.1 ° (Example 5). None of these contact angles exceed 50 °, and the contact angle with water is rather low. That is, it is slightly hydrophilic even in the normal state.</p><p> Further, in each example after irradiation, the contact angles with water were 5.4 ° (Example 1), 6.7 ° (Example 2), 8.3 ° (Example 3), 6.2 ° (Example 4), 11.3 ° (Example 4). In Example 5), it exhibited a very high hydrophilicity close to 0 ° in Comparative Example. However, when vanadium is 10 mol% (Example 6), the angle after irradiation is 23.9 °, which is almost unchanged from 25.8 ° before irradiation.</p><p> Therefore, when the amount of vanadium mixed is between 1 and 10 mol% (Examples 1 to 6), the amount of vanadium and the contact angle between the titanium oxide film and water after irradiation (effect of reducing the hydrophilicity of the titanium oxide film) It can be seen that the correlation is low, and the correlation between the amount of vanadium and the contact angle is very high in the range exceeding 10 mol%, and the contact angle is also large. Therefore, from the viewpoint of hydrophilicity, it is preferable to mix vanadium in a range of less than 10 mol%.</p><p> From the results of organic matter resolution and hydrophilicity of Examples 1 to 6 and Comparative Example 1 described above (see FIG. 4), the amount of vanadium mixed was based on the total molar amount of titanium and vanadium used for forming anatase particles. The amount is preferably 1 to 10 mol%.</p><p>[Example 7] In Example 7, the results of Examples 1 to 6 showed that Example 5 in which 5 mol% of vanadium was mixed suppressed the organic matter resolution most. Therefore, the anatase particles produced in Example 5 and the binder were mixed. As a coating agent, hydrophilicity and organic matter resolution were evaluated. First, the following materials were prepared. (Composition of hydrophilic paint) (F) Anatase solution (ANA) (Ti about 0.5% by weight, molar ratio Ti: V = about 0.95: 0.05, derived from step 5 of Example 5) ... 0.25% by weight (G) Amorphous solution (AMO) (Ti about 0.5% by weight, derived from step 4 of Comparative Example 1) ... 0.25% by weight (H) Water ... 99.5% by weight The compositions (F) to (H) were mixed with a stirrer to prepare 100 g of a coating agent (hydrophilic coating composition) having a solid content ratio of 50:50 between the anatase solution (F) and the amorphous solution (G). Using this coating agent, a hydrophilic coating film layer was formed by coating in the same manner as in Example 1, and the organic matter resolution evaluation and the hydrophilicity evaluation were performed.</p><p>[Examples 8 and 9, Comparative Example 2] Using the anatase solution and the amorphous solution used in Example 7, the solid content ratios of each were set to ANA: AMO = 25: 75 (Example 8), 75:25 (Example 9), 0: 100 (Comparative Example). It was mixed so as to be 2), and it was evaluated how much the organic matter resolution and hydrophilicity as a coating agent changed when the solid content ratio was changed. Other than that, it was coated in the same manner as in Example 1 to form a hydrophilic coating film layer, and its organic resolution and hydrophilicity were evaluated (see FIG. 5).</p><p>(Organic matter resolution as coating agent, hydrophilicity) In Examples 1 to 6, a hydrophilic coating film layer was formed using only the anatase solution and evaluated, but when actually applied to the base material, the anatase particles were made into a peroxo-modified type, etc. Unless the treatment is performed to improve the binding property of the anatase particles themselves, a binder that binds the crystal particles in the anatase solution to the substrate is often included.</p><p> In Examples 7 to 9, by including an amorphous solution having low hydrophilicity as a binder in the coating agent, it is expected that the ratio of crystal particles in the formed coating film layer will decrease, and naturally the hydrophilicity will decrease. Even so, the contact angle of the hydrophilic coating film layer with water after UV irradiation was 19.1 ° (Example 7) 25.0 ° (Example 8) 17.6 ° (Example 9), which was in the range of about 19 to 25 °. .. It can be said that this is a value close to 11.3 ° when only the anatase solution is applied (see Fig. 5 (B)).</p><p> Also, in Comparative Example 2 containing only the amorphous solution for reasons such as partial crystallization, the contact angle after irradiation decreases to 40.6 °, but it further decreases as the anatase solution is mixed, and the anatase solution and the amorphous solution are 100%. If the amorphous solution is mixed at a ratio of at least 25% or more, the contact angle of the formed hydrophilic coating layer becomes 25 ° or less. In this case, regarding the organic matter resolution, the methylene blue decomposition rate is less than 40% because a binder having a lower organic matter resolution than crystalline titanium oxide is mixed.</p><p> Therefore, even if the hydrophilic coating material contains the coating agent for forming the titanium oxide film and the binder according to any one of Examples 1 to 6, if the anatase solution is 25% or more, the film is composed only of titanium oxide (Example 1). It has the same performance as ~ 6) (hydrophilic ability, ability to suppress organic matter decomposition), and using this hydrophilic paint, for example, a hydrophilic coating layer was formed on the exterior part of an organic base material used for building materials. In this case, as compared with the case where the coating agent of Comparative Example 1 is used as the composition, it is possible to suppress unnecessary decomposition of the base material by each anatase particle dispersed in the hydrophilic coating layer and in contact with the base material. As a result, the appearance of the base material is less likely to deteriorate.</p><p> Since this hydrophilic coating film layer has high hydrophilicity after light irradiation and excitation, water such as raindrops and cleaning water spreads uniformly over the entire surface of the hydrophilic coating film surface, and the water flows away. A high self-cleaning effect can be expected. Further, if the building material uses this hydrophilic coating film layer, the same effect can be obtained, and the shortening of the life of the building material can be prevented due to the above-mentioned effect of suppressing decomposition.</p><p> It was shown in Examples 1 to 6 that the organic matter of the crystal particles of titanium oxide was suppressed, and even if the ones of Examples 1 to 6 were used together with the binder in Examples 7 to 9, the same organic matter suppression was performed. It has been shown that it can be hydrophilic. Further, since the component of the binder is a metal oxide similar to silica, the effects of suppressing the decomposition of organic substances and suppressing the decrease in hydrophilicity when the coating agent composition is used can be expected in the same manner.</p><p> Although the present invention has been described above based on the embodiments, examples and comparative examples, the present invention is not limited to the above configuration, and may be mixed by, for example, another method different from the examples. Specifically, vanadium may be carried on the surface of anatase particles or amorphous particles, or may be mixed by being included inside each particle.</p>