Combination and method for obtaining bactericidal ceramic enamels for ceramic products
Abstract
The invention relates to a combination for a bactericidal ceramic enamel with micro-roughness, characterised in that it comprises a first formulation and a second formulation, each formulation having a defined quantity of zinc cations, such that the first formulation comprises an equivalent percentage of ZnO of <= 20 wt. %, and the second formulation comprises an equivalent percentage of ZnO of less than the nominal corresponding to the composition of the first formulation. The invention also relates to a bactericidal ceramic enamel comprising the combination of formulations arranged such that the first formulation forms an outer layer of enamel in contact with the air and the second formulation forms an inner layer of enamel in contact with a surface, the outer layer being thinner than the inner layer, and to the use of the combination or the bactericidal enamel for applying to substrates and obtaining enamelled materials.

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21 claims: 5 independent, 16 dependent
- 1REIVINDICACIONES 1. Una combinación para un esmalte cerámico bactericida con micro-rugosidad caracterizada porque comprende una primera formulación y una segunda formulación, y cada una de ellas tiene una cantidad distinta de cationes cinc, tal que la primera formulación comprende un porcentaje equivalente de ZnO de≤ 20% en peso respecto al peso total de dicha primera formulación, y la segunda formulación comprende un porcentaje equivalente de ZnO menor que la nominal correspondiente a la composición de la primera formulación.
- 2Una combinación para esmalte cerámico según la reivindicación 1 , caracterizada porque la primera formulación comprende al menos:un feldespato;una frita vitrea o una combinación de fritas vitreas, óxido de cinc;y - una arcilla tipo caolinítica.
- 3Una combinación para esmalte según una de las reivindicación 1 ó 2, caracterizada por que:- la primera formulación comprende feldespato frita y caolín, preferentemente en el intervalo de porcentajes en peso respecto al peso total de la formulación: componente Intervalo de porcentaje en u óxido equivalente ^ eso ZnO ≤ 20 % Frita 10 a 70 % Feldespato 20 a 60 % Caolín 3 a 14 % - la segunda formulación comprende feldespato, frita y caolín, preferentemente en el intervalo de porcentajes en peso respecto al peso total de la formulación: componente Intervalo de porcentaje en u óxido equivalente ^ eso Frita 10 a 70 % Feldespato 20 a 60 % Caolín 3 a 14 % - y la segunda formulación tiene una concentración equivalente de ZnO menor que la nominal correspondiente a la composición de la primera formulación.
- 4Una combinación para esmalte según la reivindicación 3, caracterizada porque la frita comprende unos componentes que están presentes en el intervalo de porcentajes en peso respecto al peso total de la frita:
- 5Una combinación de formulaciones según una de las reivindicaciones 1 a 4, caracterizada porque la primera formulación comprende además, al menos un componente seleccionado entre:- un segundo óxido;- un pigmento cerámico;- un precursor de un pigmento.
- 6Una combinación según la reivindicación 5, caracterizada porque dicho pigmento cerámico está presente en la primera formulación en un porcentaje en peso respecto al peso total de dicha formulación, de hasta el 10 %, o en la segunda formulación en un porcentaje en peso respecto al peso total de dicha formulación, de hasta el 10%, o en ambas en un porcentaje en peso respecto al peso total de cada formulación, de hasta el 10.
- 7Uso de la combinación definida en una de las reivindicaciones 1 a 6 para obtener un material esmaltado, en el que la primera formulación se aplica como capa externa sobre una superficie del material y la segunda formulación se aplica como al menos una capa interna sobre dicha superficie, tal que la capa externa tiene un espesor menor que la capa interna.
- 8Uso de la combinación según la reivindicación 7 para su aplicación sobre superficies vitrificadas de productos cerámicos, sobre productos cerámicos para cerámica estructural, cerámica sanitaria o cerámica ornamental.
- 9Uso de la combinación para esmalte cerámico según la reivindicación 7 para su aplicación sobre materiales seleccionados entre ladrillos, tejas, vajillas, mobiliario, complementos cerámicos de cocina, pavimentos, revestimientos cerámicos, elementos sanitarios, elementos cerámicos estructurales, complementos cerámicos de cuarto de baño, azulejos de gres porcelánico y esmaltes de porcelana sanitaria y elementos cerámicos ornamentales.
- 10Un esmalte cerámico bactericida caracterizado porque comprende una combinación de formulaciones definida en una de las reivindicaciones 1 a 6.
- 111 1. Un esmalte cerámico bactericida según la reivindicación 10, caracterizado porque la combinación de formulaciones está dispuesta de modo que la primera formulación constituye una capa externa de esmalte en contacto con el aire y la segunda formulación constituye una capa interna de esmalte en contacto con una superficie, y la capa externa tiene menor espesor que la capa interna.
- 12Un esmalte cerámico bactericida caracterizado porque es obtenible mediante un procedimiento que comprende la aplicación de una combinación de formulaciones definida en una de las reivindicaciones 1 a 6, sobre una superficie de un material de modo que la primera formulación constituye una capa externa de esmalte sobre la superficie del material y la segunda formulación constituye una capa interna de esmalte sobre dicha superficie, y tal que la capa externa tiene menor espesor que la capa interna.
- 13Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 12, caracterizado porque la capa externa de esmalte tiene una viscosidad a la máxima temperatura de consolidación del esmalte menor que la viscosidad a la misma temperatura de la capa interna.
- 14Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 12, caracterizado porque la capa interna de esmalte y la capa externa tienen entre ellas una proporción en el gramaje tal que el gramaje de la capa interna es superior al gramaje de la capa externa de esmalte.
- 15Un esmalte cerámico bactericida según la reivindicación 14, caracterizado porque la capa externa tiene un gramaje inferior a 450 g/m 2 , más preferentemente inferior a 300 g/m 2 y más preferentemente inferior a 150 g/m 2 .
- 16Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 15, caracterizado porque el procedimiento comprende someter la combinación de formulaciones aplicada sobre la superficie de un material a temperaturas entre 900°C y 1280°C.
- 17Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 16, caracterizado porque en su superficie el esmalte comprende cristalizaciones correspondientes a fases cristalinas de la familia de los tectosilicatos y cristalizaciones de gahnita.
- 18Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 17, caracterizado porque la capa de esmalte interna está depositada sobre:- un esmalte de diferente naturaleza - una capa de engobe - o bien directamente sobre el substrato cerámico.
- 19Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 19, caracterizado porque la capa interna de esmalte está decorada con pigmentos cerámicos.
- 20Un esmalte cerámico bactericida según una de las reivindicaciones 10 a 19, caracterizado porque la superficie del esmalte micro-rugoso bactericida tiene un valor de rugosidad medio Ra superior a 0,7 μηι, preferentemente superior a 1 μηι, y un valor de máxima aspereza Rt superior a 7 μηι, preferentemente superior a 10 μηι.
- 21Un material esmaltado caracterizado porque comprende un esmalte cerámico bactericida definido en una de las reivindicaciones 10 a 17.
Independent claims21
186 paragraphs in 5 sections, as filed
COMBINATION AND PROCEDURE FOR OBTAINING CERAMIC BACTERICIDE ENAMELS FOR CERAMIC PRODUCTS
TECHNICAL SECTOR
This patent has its scope in the field of preparation of formulations for the ceramic industry, particularly in glaze applications for vitrified surfaces of ceramic products, both in the production of ceramic tiles and in structural ceramics, sanitary ceramics and ornamental ceramics.
More specifically, the present invention relates to a new type of bactericidal ceramic enamels.
STATE OF THE ART
Ceramic enamels are applied on multiple ceramic products used in different areas, such as: tableware, furniture, ceramic kitchen accessories, ceramic flooring and cladding, sanitary elements, structural ceramic elements, bathroom ceramic accessories, ornamental ceramic elements, etc.
A ceramic enamel is the result of the fusion of a milled mixture comprising different minerals, metal oxides, carbonates, and glass, among others, [Ceramic enamels and pigments, P. Escribano, JB Carda and E. Cordoncillo, Faenza Editrice SL Castellón 2001]. It is common practice to pre-melt the different components to obtain a glass powder, called a frit, which facilitates the technological processes of applying ceramic glazes. Ceramic enamel is generally prepared in the form of an aqueous suspension and applied to the surface of the ceramic product. The enamel is consolidated by heat treatment at high temperature. The final ceramic glaze is a glazed surface that consists of a glassy matrix and can contain different crystalline phases, either previously introduced, or formed during heat treatment. These crystalline phases are generally dispersed in the vitreous matrix.
It is well known in the state of the art that the advantages of enameled ceramic products lie in having a porosity-free surface, possessing high mechanical resistance and being resistant to chemical agents, such as acids and bases. These technical characteristics facilitate the cleaning of enameled surfaces. Enameled ceramic surfaces maintain colors in a lasting way and can be decorated with different motifs or reproduce elements such as stones, wood, metals, etc. The aesthetic aspects of ceramic enamels are highly valued for their stability over time and their durability against external agents.
However, the ease of cleaning of ceramic products that have a ceramic enamel does not prevent bacteria from proliferating in the presence of ceramic enamel. A bactericidal property in ceramic enamels is therefore a desired property in this type of product.
In the state of the art there are several procedures to confer bactericidal property to a ceramic enamel. One of the effects that are used to prevent the proliferation of bacteria on the surface of a ceramic product is the photocatalytic effect. This effect requires the presence of semiconductor crystal structures consisting of crystalline particles of metal ions in the enamel. These particles must be located on the external surface of the enamel. The absorption of light by the metal ion crystals produces an electron-hole pair on the surface of the crystal that interacts with organic substances, causing their oxidation. These processes are strongly favored in the presence of nanometric particles of semiconductor oxides, such as Ti0<sub>2</sub>, because the quantum confinement phenomena of the nanocrystals allow obtaining excitons that reach the surface of said particles. There are procedures to apply external layers by means of sols on ceramic enamels based on Ti0 particles.<sub>2</sub> with silver and copper cations [JP3063735 B2]. The set is thermally consolidated. Other procedures that use the same effect consist of ceramic enamels comprising rare earth oxide cations, such as Ce0<sub>2</sub>, and are applied by mixing or frying on ceramic floors and coatings [ES 2142249 B1]. The limitations presented by bactericidal enamels based on the photocatalytic effect lie in the need to illuminate the enamel, generally requiring illumination with ultraviolet light. This limitation consists rather of a restriction of use, since the bactericidal effect is only achieved under illumination with ultraviolet light. Another even more limiting aspect of bactericidal enamels based on the photocatalytic effect is the need for the semiconductor particles to be located on the external surface of the enamel, in order to yield the electrons produced by photoexcitation. The efficiency of this type of solutions is, therefore, limited to the presence of semiconductor particles on the surface and in particular to the presence of semiconductor nanoparticles. The insulating nature of ceramic glazes is deleterious for the generation of electronic carriers in metal oxide semiconductor particles if they are embedded in the glassy matrix. Another unresolved issue in the state of the art is how to preserve the nature of semiconductor particles in high temperature heat treatment processes in vitreous matrices.
The bactericidal effect can also be obtained by chemical processes in ceramic enamels that contain substances that provide silver cations. Diffusion of silver cations, Ag<sup>+</sup>, present in the ceramic enamel deactivates or destroys the enzymes that favor the supply of oxygen to the bacteria, and thus the cell membrane is destroyed, preventing its proliferation. The antimicrobial effect of silver has been well known since ancient times and its incorporation in glasses provides a bactericidal effect on ceramic enamels, and there are several procedures for obtaining it [WO2006 / 064059 A1] [US5807641]. The advantage of incorporating silver both in the form of silver nanoparticles and in the form of silver cations in the vitreous network, is that the surface properties of the ceramic enamel are maintained. Its use is limited by the cost of the application as well as by the environmental risk of uncontrolled leaching of silver cations. The main drawback of the presence of silver cations in ceramic enamels is the durability of the bactericidal effect. For the bactericidal effect to occur, the migration of silver ions from the vitreous matrix to the environment where the bacteria are is necessary. The existence of a finite number of silver atoms and the protective nature of the vitreous matrix for its release, strongly limit the bactericidal response of these enamels in time, in clear contrast to the high durability required of enameled ceramic products. A partial solution to this problem is to design more easily attachable vitreous matrices and thus increase the proportion of leachable silver or silver ions of the ceramic enamel, as described using phosphate glasses [KR20000004200 A]. This bactericidal effect is also obtained by combination with other cations that are incorporated in vitreous phases such as copper or zinc cations [JP1 1228186]. The main limitation of these glazes is that as their attackability increases, the degradation of the surface is very severe and loses the surface properties required of industrial ceramic products. There are glasses that have a high solubility in an aqueous medium and in whose composition there is a high percentage of alkaline and alkaline-earth cations [JP7257938 A]. The bactericidal property is attributed to the high pH values caused by the release of the alkaline and alkaline-earth cations from the vitreous matrix. This type of glass shows a greater bactericidal effect when the specific surface of the glass is increased; therefore the glass in the form of glass powder obtained for example by milling is used. These types of products are called bioactive glasses in the state of the art. A remarkable improvement of the bactericidal properties in bioactive glasses is achieved by means of the controlled crystallization of crystalline phases in the vitreous matrix so that the presence of said crystallizations generates a high number of edges or angles on the surface without reducing the solubility of the species. chemicals in the aqueous medium [US 7141520 B2]. The existence of crystallizations, in particular of needle-shaped crystals, contributes significantly to the rupture of the bacteria's membranes. The existence of needle-shaped or sharp-edged nanocrystals is known in the art as effective for its bactericidal effect. It is obvious to any expert in ceramic enamels that despite the high effectiveness of bioactive glass particles, its application on ceramic enamel surfaces for industrial ceramic products is not technologically compatible since ceramic powder does not meet the technical requirements for a glazed ceramic product.
An interesting aspect of the state of the art consists in the bactericidal effect of micro-rough surfaces that act as repellents of bacteria [DE 19818956 A1]. Roughness is obtained in different materials such as polymers, metals and glass by irradiation, stamping, abrasion or casting procedures on a micro-rough surface. Since the consolidation by means of thermal treatment of the ceramic enamels generates a surface with low roughness, which does not absorb water and does not present a bactericidal effect, the generation of subsequent micro-roughness on a glazed surface represents a complex and economically unfeasible process.
As can be deduced from the state of the art, obtaining a bactericidal ceramic enamel for ceramic products presents difficulties of practical application, mainly due to restrictions on the effects that the bactericidal effect provides. One of the common aspects of the different procedures proposed and not resolved to date is the incompatibility of the processes with the aesthetic properties required by the enameled ceramic materials that add to the requirements established in the technical properties of industrial ceramics.
The objective of the present invention is to establish the compositions and a method of producing enamels to obtain enamels with controlled surface micro-roughness that have a bactericidal effect. The enamels object of the present invention are applicable as coatings in industrial ceramics, both in the production of ceramic tiles and in tableware, ceramic accessories, structural ceramics and sanitary ceramics.
It can be seen that the use of mixtures and oxides is known but in the present invention, the oxides and proportions used are combined following a novel procedure that is advantageous compared to those known by the state of the art to produce in a controlled manner the bactericidal effect in ceramic enamels.
On the other hand, the preparation procedure and the formulations used in the present invention are advantageous to produce ceramic enamels with bactericidal properties in a wide temperature range, extending their application to different techniques that range from structural ceramic products such as bricks and tiles, tableware, ceramic accessories, red and white stoneware flooring, red and white body tiles, porcelain stoneware tiles and sanitary porcelain enamels.
Another advantage of the present invention is that the procedure used is compatible with the enamels commonly used in the ceramic industry. In this way, enamels with a bactericidal effect can be applied in different ceramic processes, maintaining the properties of ceramic enamels such as ease of cleaning, mechanical resistance and resistance to chemical attack. A particularly advantageous aspect of the present invention is that the composition and procedure thereof allow to maintain the aesthetic and decorative effects that characterize glazed ceramic products.
DESCRIPTION OF THE INVENTION
The present invention provides an industrial ceramic product with a ceramic enameled surface with controlled micro-roughness that has a bactericidal effect called bactericidal enamel. The bactericidal enamel with micro-roughness comprises in its composition the presence of zinc cations and at least one crystalline phase. Bactericidal enamel formation with micro-roughness is possible from a suitable combination of enamel layers with different composition. The combination of different enamel layers is characterized by the existence of a relationship between them, such that the external enamel layer is of a thickness less than that of the internal enamel layer. The thickness ratio between the outer and inner enamel layers is determined by the corresponding starting weights. The external enamel layer is characterized by having a lower viscosity at the maximum enamel consolidation temperature than the viscosity at the same temperature as the internal enamel layer. The formation of bactericidal enamel with micro-roughness from a suitable combination of enamel layers with different composition is possible by means of a suitable heat treatment.
A first object of the invention is a combination for a bactericidal ceramic enamel with micro-roughness characterized in that it comprises a first formulation and a second formulation, and each of them has a different quantity of zinc cations, such that the first formulation comprises an equivalent percentage of ZnO of ≤ 20% by weight with respect to the total weight of said first formulation and the second formulation comprises an equivalent percentage or equivalent concentration of ZnO less than the nominal corresponding to the composition of the first formulation.
According to particular embodiments in the combination the first formulation comprises at least:
- a feldspar;
a vitreous frit or a combination of vitreous fries,
zinc oxide; and
a kaolinitic clay.
According to additional particular embodiments in the combination:
- the first formulation comprises fried feldspar and kaolin, preferably in the range of percentages by weight with respect to the total weight of the formulation:
Component Percent Interval in
or equivalent oxide ^<sup>that</sup>
ZnO ≤ 20%
frit 10 to 70% feldspar 20 to 60%
kaolin 3 to 14%
- the second formulation comprises feldspar, frit and kaolin, preferably in the range of percentages by weight with respect to the total weight of the formulation:
Component Percent Interval in
or equivalent oxide ^<sup>that</sup>
fried 10 to 70%
feldspar 20 to 60%
kaolin 3 to 14%
- and the second formulation has an equivalent concentration of ZnO less than the nominal corresponding to the composition of the first formulation.
When referring to weight percentage ranges, it should be understood that the limits of both ranges are also included therein.
By "equivalent oxide" is meant that the percentage of the referred cation (Zn for example) is kept in the same proportion as that corresponding to the referred oxide (ZnO for example).
The frit can be of the same or different composition for each of the two formulations. Preferably, in this embodiment, the frit has the same composition in the first formulation and in the second. The frit may comprise components that are present in the range of percentages by weight with respect to the total weight of the frit:
<img file="WO2013041751A1_D0001.tif" /> According to further particular embodiments the first formulation further comprises at least one component selected from:
- a second oxide;
- a ceramic pigment;
- a precursor of a pigment;
Said ceramic pigment may be present in the first formulation in a percentage by weight with respect to the total weight of said formulation, of up to 10%, or in the second formulation in a percentage by weight with respect to the total weight of said formulation, up to 10%. 10%, or both in a percentage by weight with respect to the total weight of each formulation, of up to 10%.
The present invention also relates to the use of the defined combination to obtain a glazed material, in which the first formulation is applied as an external layer on a surface of the material and the second formulation is applied as at least an internal layer on said surface, such that the outer layer is less thick than the inner layer.
The defined combination can also be applied on vitrified surfaces of ceramic products, on ceramic products for structural ceramics, sanitary ceramics or ornamental ceramics.
Likewise, the combination can be used for its application on selected materials among bricks, tiles, tableware, furniture, ceramic kitchen accessories, flooring, ceramic coverings, sanitary elements, structural ceramic elements, bathroom ceramic accessories, porcelain stoneware tiles and sanitary porcelain enamels and ornamental ceramic elements.
The present invention also relates to a bactericidal ceramic enamel characterized in that it comprises the combination of formulations defined above.
In the enamel of the invention the combination of formulations is arranged such that the first formulation constitutes an outer layer of enamel in contact with air and the second formulation constitutes an inner layer of enamel in contact with a surface, and the outer layer has thinner than the inner layer. Furthermore, the present invention also relates to a bactericidal ceramic enamel characterized in that it is obtainable by a method that comprises the application of the combination of formulations defined above on a surface of a material so that the first formulation constitutes an external layer of enamel on the surface. surface of the material and the second formulation constitutes an internal layer of enamel on said surface, and such that the outer layer is less thick than the inner layer.
According to particular embodiments, the outer enamel layer has a viscosity at the maximum enamel consolidation temperature less than the viscosity at the same temperature as the inner layer.
According to particular embodiments, the inner enamel layer and the outer layer have a weight ratio between them such that the weight of the inner layer is greater than the weight of the outer enamel layer, preferably, the outer layer has a weight of less than 450 g / m<sup>2</sup>, more preferably less than 300 g / m<sup>2</sup> and more preferably less than 150 g / m<sup>2</sup>.
According to particular embodiments of obtaining the enamel, the process comprises subjecting the combination of formulations applied on the surface of a material to temperatures between 900 ° C and 1280 ° C.
The bactericidal ceramic enamel on its surface the enamel can comprise crystallizations corresponding to crystalline phases of the tectosilicate family and gahnite crystallizations.
According to particular embodiments, the inner enamel layer is deposited on:
- a second enamel or enamel of a different nature than the enamel being obtained
- a slip layer
- or directly on the ceramic substrate.
According to particular embodiments, the inner enamel layer is decorated with ceramic pigments.
According to particular embodiments, the surface of the bactericidal micro-rough enamel has a mean roughness value Ra greater than 0.7 μηι, preferably greater than 1 μηι, and a maximum roughness value Rt greater than 7 μηι, preferably greater than 10 μηι. Another subject of the present invention is an enamelled material characterized in that it comprises a bactericidal ceramic enamel as defined above. The procedure for obtaining micro-rough bactericidal enamels comprises at least applying an external layer corresponding to the first formulation defined above that is deposited on an internal layer of enamel previously deposited. The composition used by the outer enamel layer includes:
- a feldspar;
a vitreous frit or a combination of vitreous fries,
a zinc oxide, ZnO, and;
a kaolinitic clay.
In a preferred embodiment of the composition of the invention, the outer enamel layer further comprises a ceramic pigment. And in a more preferred embodiment the percentage by weight of the ceramic pigment in the external enamel layer is up to 10% with respect to the total weight of the composition. Ceramic pigments can be selected from, but not limited to, the different types of pigments available in the ceramic industry, such as spinel-structured pigments.
The incorporation of a second oxide element, or a ceramic pigment, or a combination of both, or a precursor thereof, is characterized by modifying the chromatic coordinate of the gloss metallic enamel while maintaining its bactericidal response. The incorporation of a second oxide element or a ceramic pigment or a combination of both or a precursor thereof different from those previously described in order to modify the color coordinates does not represent an advantage with respect to the bactericidal properties of the layer enamel. In the present invention when referring to an oxide element such as a metallic oxide, no restriction is established in its oxidation state. Therefore its substitution by an oxide with a different oxidation state or even if its substitution is made by a precursor of said oxide is not relevant since the subsequent firing processes of the resulting enamel are carried out at a high temperature in an oxidizing atmosphere, generally air. In a particular embodiment, the formulation to obtain micro-rough bactericidal enamels and which is especially suitable for applying to porcelain stoneware enamels, is characterized in that the combination of enamel layers comprises an external enamel layer that uses the formulation referred to as the first formulation. . The formulation of the outer enamel layer comprises ZnO, feldspar, frit and kaolin, which are preferably in the range of percentages by weight with respect to the total weight of the formulation expressed in Table 1.
Component Percentage range
weight
or equivalent oxide
ZnO ≤ 20%
fried 10 to 70%
feldspar 20 to 60%
kaolin 3 to 14%
Table 1
In the particular embodiment described, the frit corresponds to a glazed material that has been fried and whose components are preferably in the range of percentages by weight with respect to the total weight of the frit shown in Table 2.
<img file="WO2013041751A1_D0002.tif" />
Table 2 In the particular embodiment described, the frit may contain other compounds considered as minorities and always in a composition of less than 1% by weight with respect to the total frit. Optionally, the frit may incorporate the ZnO oxide that comprises the formulation in whole or in part.
The total ZnO content in the enamel can be achieved either by the content of the frit, either by the incorporation of ZnO particles or by a mixture of the two.
The ZnO content in the outer layer is from the start greater than the content in the inner layer.
The incorporation of the compounds in the frying process guarantees the inerting of said compounds limiting the subsequent volatilization during the enamel firing. Likewise, and as it is known in the state of the art, frying processes allow the raw materials to be adapted for later use in the ceramic industry, facilitating their use by conventional techniques. The procedure described in the present invention allows the formulation for the development of bactericidal enamel layers to be adapted to the different supports commonly used in the ceramic industry. The composition required for a specific product can be obtained by combining different frits, as long as the final composition resulting from the combination of frits is within the limits established in the present invention.
In the particular embodiment described, feldspar comprises a group of minerals from the family of tectosilicates, or three-dimensional silicates or framework-structure silicates that are mainly constituted by igneous type rocks and which feature a certain degree of silicon substitution by aluminum. Mixtures of two or more of the aforementioned tectosilicates, three-dimensional silicates and framework-structure silicates can also be used.
According to particular embodiments, a mineral is used which is a mixture of feldspars known as nepheline.
The feldspars comprise calcium and aluminum silicates as the general formula anorite CaAI<sub>2</sub>Yes<sub>2</sub>0<sub>8</sub>, or sodium silicates like albite of general formula NaAISi<sub>3</sub>0<sub>8</sub>, or potassium silicates such as potassium feldspar of general formula KAIS! 30<sub>8</sub>, or mixtures of these bases. Mixed minerals with a composition between potassium feldspar and albite are called alkaline feldspars, mixed minerals with composition between albite and anortite form the group of plagioclase. All feldspars are hard minerals, with a specific gravity of between 2.5 and 2.8 g / cm3. The feldspars are used in powder form with a particle size of less than 100 μηι, preferably less than 63 μηι.
In the particular embodiment described, the kaolinitic or kaolin type clay, or china clay, whose general chemical composition is AI<sub>2</sub>YES 205 (OH)<sub>4</sub> It comprises a mineral from the family of phyllosilicates that has a layer of silicon tetrahedra linked through oxygen with a layer of alumina octahedra. Kaolinitic clay can be made up of a mixture of different clays and minerals, the composition of which is extensively described in the state of the art. Kaolinitic clay allows the formulation to be suspended, in order to form a stable slip in an aqueous medium of the different constituent elements in the formulation for micro-rough enamel layers with bactericidal property. The homogeneity in the slip composition and its rheological stability must be compatible with the different enamel deposition processes in a wet medium. Said formulation will be processed following routes similar to those conventionally used in the ceramic flooring industry and which are broadly defined in the state of the art. In the preparation of enamels in aqueous medium, other additives are commonly used to guarantee a suitable process and application of the enamel layers, such as deflocculants, dispersants, antifoams, suspending agents, plasticizers, glues, etc.
The use of conventional routes for shaping enamel allows it to be applied by wet methods, such as those known as bell, veil, disc, spray or immersion, among others. Other less extended routes in its use can also lead to the application of enamels such as tape casting, electrostatic deposition, among others.
Additionally, by drying said slip, a dry enamel is generated that can be applied either as dry applications, for example grits, or once micronized as screen printing ink.
For the slip preparation the usual systems used by the ceramic industry can be used, such as grinding or dispersing. The average particle size of the enamel slip of the present invention will be such that it does not present a rejection greater than 5% by weight on a 63 μηι sieve. The final size of the materials to form the combination of the enamel layers will be determined by the application technique used to form said enamel layers.
In the particular embodiment referred to, the internal enamel layer comprises a composition similar to the external enamel layer reflected in Table 1, where the equivalent concentration of ZnO has a lower concentration than the nominal one corresponding to the composition of the external enamel layer. The outer enamel layer is characterized by having an equivalent content of zinc oxide that is proportionally higher than that corresponding to the internal enamel layer.
In a preferred embodiment of the combination of the invention, the inner enamel layer further comprises a ceramic pigment. And in a more preferred embodiment the percentage by weight of the ceramic pigment in the inner layer of enamels is up to 10% with respect to the total weight of the formulation.
In the particular embodiment of micro-rough bactericidal enamel the proportion between the grammage of the inner enamel layer is higher than the grammage of the outer enamel layer. The grammage unit is defined as the grams of enamel applied per unit of square meter of ceramic support, that is, g / m<sup>2</sup>. As an example and not restrictive to said example, a grammage of 450 g / m<sup>2</sup> Provides a 0.2mm thickness of enamel coat once it has been thermally bonded.
Preferably to obtain a micro-rough bactericidal enamel the weight used in the outer layer is less than 450 g / m<sup>2</sup>, more preferably the grammage is less than 300 g / m<sup>2</sup> and even more preferably, the weight used in the outer layer is less than 150 g / m.<sup>2</sup>.
The invention is based on the industrial cycle firing (eg single firing of a porcelain stoneware flooring in a fast firing single-layer gas oven) of the previous formulation.
A particular object of the invention is the process by which frits with different composition are used both for the formulation of the enamel of the outer layer and for the enamel of the inner layer. The modification of the composition of the frit thus represents an advantage that allows adjusting, depending on the ceramic substrate used, the temperature range in which the micro-rough bactericidal enamel layer develops. This procedure is advantageous since it allows its application in materials that require very different ranges of firing temperatures. In the present invention, the temperature range in which micro-rough bactericidal enamels have been obtained is comprised between 900 ° C and 1280 ° C.
The combination of layers of the composition of the invention is advantageous to produce micro-rough bactericidal enamels in a wide temperature range.
In a second aspect, the present invention relates to the use of the combination of layers of the formulation of the invention, as an enamel for ceramic coating, such as for example in sanitary porcelain enamels.
In a preferred embodiment, the ceramics are tiles, bricks, tiles, sanitary ware, pavements or decorative elements.
Another aspect of the present invention refers to a glazed material characterized by comprising the combination of enamel layers of composition of the outer layer and composition of the inner layer of the invention and a ceramic support.
The enamel surface of the present invention comprises crystallizations corresponding to crystalline phases of the tectosilicate family such as anortite, albite and solid solutions such as plagioclase. Other crystallizations such as the gahnite phase are present to a lesser extent on the enamel surface of the present invention. Other crystallizations can be incorporated into the outer layer such as quartz, zircon, corundum, spinels, garnets, etc. The effect of these other crystallizations is related to the chromatic modification of the enamel layer.
The decrease in melt viscosity during heat treatment favors the formation of crystalline phases in the enamel. The lower viscosity of the outer enamel layer compared to the viscosity of the inner enamel layer at the maximum sintering temperature results in the partial diffusion of cations from the outer enamel layer into the inner enamel layer, thereby promoting presence of crystallizations on the surface. This mass flow from the outer layer to the inner layer corresponds to the vitreous phase and in this way the crystalline phases of the tectosilicate family are found on the surface presenting edges and faces free of vitreous phase in micro enamel compositions. -rugged of the present invention. The presence of crystallizations on the surface is also favored by a lower thickness of the external enamel layer compared to the internal enamel layer. For the same composition, this process is also favored for firing cycles at a higher temperature and sintering cycles with a shorter residence time at the maximum sintering temperature.
Another characteristic of the micro-rough enamels of the present invention is that the content of the gahnite-like crystalline phase of the external enamel layer is less than that corresponding to an enamel of the same composition that is applied as a single layer or when its thickness in a combination of enamel layers is superior to that established within the limits of the present invention. The reduction in crystallization of the gahnite phase is favorable in the appropriate combination of enamel layers. Zn cations<sup>2+</sup> occupy positions similar to the cations of Ca<sup>2+</sup> in the vitreous network. Greater micro-roughness of the surface and the presence of Zn cations<sup>2+</sup> and Ca<sup>2+</sup> in the vitreous phase they promote synergy between the different physical and chemical processes that allow the bactericidal effect of the enamels of the present invention to be enhanced.
Another aspect of the present invention is that the external enamel layer can be deposited either in an enamel of a different nature or in a slip layer or directly on the ceramic substrate. In the cases described above, the viscosity of the support layer at the maximum firing temperature, regardless of its nature, must be less than the viscosity of the external enamel layer at said temperature to produce the effect of glassy phase free crystal formation. on the enamel surface.
Another aspect of the invention is that the inner enamel layer can be decorated with ceramic pigments. This decoration can be a mass decoration by incorporation into the formulation of a ceramic pigment or it can be a surface decoration by the standard decoration techniques used in the ceramic industry such as, but not limited to, such examples as screen printing, decoration digital or pad printing. Said decoration is kept under the external enamel layer of the present invention once the ceramic piece has been subjected to heat treatment. This aspect is of special relevance since it allows the use of bactericidal micro-rough enamels in the products demanded by the market, conferring bactericidal functionality on them. The surface of the bactericidal micro-rough enamel is characterized by presenting a surface with a mean roughness value Ra greater than 0.7 μηι, preferably greater than 1 μηι, and a maximum roughness value Rt greater than 7 μηι, preferably greater than 10 μηι.
As the average surface roughness value, Ra, the arithmetic average value of the absolute values of the roughness profile distances from the midline within the measurement section is defined. The average surface roughness value is expressed in μηι. The measurement section is at least 8 mm from the enamel surface.
As the maximum surface roughness value, Rt, the distance in micrometers, μηι, between the maximum depth and the maximum height within the measurement section is defined.
Surface roughness is determined by electronic instruments called roughness meters.
The bactericidal activity of the micro-rough enamels obtained according to the present invention has been evaluated by means of bacterial susceptibility tests. The samples were evaluated according to the JIS Z 2801 standard, version revised in 2006. The microorganisms on which the susceptibility tests were carried out were Staphylococcus aureus (CECT 86) and Escherichia coli (CECT 516, ATCC 8739). For this, 1 * 10 was initially inoculated<sup>5</sup> CFU (colony forming units) on each specimen. These samples were incubated at 37 ° C for 24 h and then a viable cell count was made. Three replicates were analyzed from each type of test specimens.
As indicated in the JIS Z 2801 standard, the value of antimicrobial activity of the samples after their evaluation is obtained from the expression:
R = log (B / C)
where B is the average of viable bacteria in the blank sample after 24 h incubation at 37 ° C, and C is the average of viable bacteria in the antimicrobial sample after 24 h incubation at 37 ° C.
If R ≥ 2.0, the evaluated sample is considered to have bactericidal effectiveness.
The enameled samples according to the procedure described in the present invention have a high bactericidal effectiveness according to the described examples. Comparative examples of enamels of similar composition whose bactericidal effectiveness is less than a value of R = 2 have been incorporated. An aspect required to provide the bactericidal property in an enameled ceramic is determined by the micro-roughness of the surface, by the existence of crystals on the surface and the existence of calcium cations and zinc cations in the glassy matrix. The samples obtained as comparative examples of similar composition and that present R <2 are characterized by a micro-roughness Ra <0.7 μηι and ΡΜ <7μηι and by presenting the surface crystals covered by the vitreous phase. Likewise, in the comparative examples that do not present a bactericidal effect, the presence of zinc in the formulation produces the formation of the gahnite phase with a spinel structure, thus reducing the proportion of Zn cations.<sup>2+</sup> in the vitreous phase.
The micro-rough enamels with a bactericidal effect of the present invention are characterized by presenting values of R> 2, preferably R> 3 and especially preferably R> 5.
The micro-rough enamels with a bactericidal effect of the present invention are characterized by the surface roughness of the enamel having values of Ra> 0, ^ m, preferably Ra> 1, C ^ m and Rt> 7μm, preferably Rt> 1C ^ m.
The micro-rough enamels with a bactericidal effect of the present invention are characterized in that the particles of the crystalline phases of the enamel surface have glassy phase free faces and edges.
A first aspect of special relevance related to the crystalline phases on the surface of micro-rough enamels with a bactericidal effect is that the crystalline phases of gahnite are completely or partially inhibited compared to enamels of the same composition applied in monolayer.
A second aspect of special relevance is that the characteristics of micro-rough enamels with a bactericidal effect are obtained when the grammage of the outer enamel layer is less than 450 g / m2, preferably 300 g / m<sup>2</sup>.
Another aspect representing an advantage of the present invention is that the bactericidal effectiveness is maintained after prolonged exposure of the surface to an aqueous medium. The bactericidal effectiveness tests on samples of the micro-rough enamels of the present that were kept immersed in aqueous medium for 10 days, maintain a value of R> 2 for the bacteria tested.
An advantageous aspect of the present invention is provided by the reduced thickness of the outer enamel layer. Said external enamel layer has adequate transparency such that it allows a decoration to be made below the external enamel layer. Said decoration is visible to the outside, thus allowing to decorate and aesthetically enhance the resulting enameled ceramic products, providing the external surfaces with the desired bactericidal property.
An advantageous aspect of the present invention is its economic aspect when using components that are common in the ceramic industry and in particular the use of feldspars which are low cost minerals and very abundant in nature.
Another advantageous aspect of the present invention refers to the use of the enameled material described above as a covering or decorative element, floors, walls, on building facades, both interior and exterior, or in any other non-conventional ceramic application, such as in urban environments, furniture, sanitary ware, and applications in technical ceramics, among others.
Throughout the description and claims, the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and characteristics of the invention will emerge in part from the description and in part from the practice of the invention. The following examples and drawings are provided by way of illustration, and are not intended to be limiting of the present invention.
DESCRIPTION OF THE FIGURES
Figure 1.- Scheme to produce a bactericidal micro-rough enamel using a combination of internal enamel layers (3) and external enamel layer (4) on a porcelain stoneware support (1) that is covered by a layer of ceramic engobe. (two).
Figure 2.- Scheme to produce a bactericidal micro-rough enamel by means of a combination of internal enamel layers (3) and external enamel layer (4) on a porcelain stoneware support (1) that is covered by a ceramic engobe layer. (two). The enamel incorporates a decoration motif (5) applied by screen printing ink between the outer enamel layers and the inner enamel layer. Figure 3. X-ray Diffraction Diagram of the crystalline phases on the surface of enamels (a) designated in Comparative Example 1 with a proportion of ZnO equivalents of <1.0% by weight in its composition; (b) designated comparative example 2 with a proportion of ZnO equivalents of 7.7% by weight in its composition; c) Bactericidal micro-rough enamel designated in Example 3 consisting of a combination of an inner enamel layer with a ZnO equivalent ratio of <1.0 wt% and a grammage of -459 g / m<sup>2</sup>, and an external enamel layer with a ZnO equivalent ratio of <7.7% by weight and a grammage of -138 g / m<sup>2</sup> and (d) bactericidal micro-rough enamel designated in Example 4 consisting of a combination of an enamel inner layer with a ZnO equivalent ratio of <1.0 wt% and a grammage of -480 g / m<sup>2</sup>, and a layer an outer layer of enamel with a ZnO equivalent ratio of <7.7% by weight and a grammage of -293 g / m<sup>2</sup>. Figure 4 Surface roughness of enamels (a) designated in Comparative Example 1 with a ZnO equivalent ratio of <1.0 wt% in its composition; (b) designated comparative example 2 with a proportion of ZnO equivalents of 7.7% by weight in its composition; c) Bactericidal micro-rough enamel designated in Example 3 consisting of a combination of an inner enamel layer with a ZnO equivalent ratio of <1.0 wt% and a grammage of -459 g / m<sup>2</sup>, and an external enamel layer with a ZnO equivalent ratio of <7.7% by weight and a grammage of -138 g / m<sup>2</sup> and (d) bactericidal micro-rough enamel designated in Example 4 consisting of a combination of an enamel inner layer with a ZnO equivalent ratio of <1.0 wt% and a grammage of -480 g / m<sup>2</sup>, and a layer an outer layer of enamel with a ZnO equivalent ratio of <7.7% by weight and a grammage of -293 g / m<sup>2</sup>.
Figure 5. Field Effect Scanning Electron Microscopy Micrograph of the enamel surface (a) designated in Comparative Example 2 with a ZnO equivalent ratio of 13.0% by weight; and (b) bactericidal micro-rough enamel designated in Example 4 consisting of a combination of an inner enamel layer with a ZnO equivalent ratio of <1.0 wt% and a grammage of -480 g / m<sup>2</sup>, and an external enamel layer with a ZnO equivalent ratio of <7.7% by weight and a grammage of -293 g / m<sup>2</sup>. Figure 6 Bactericidal micro-rough enamel designated as example 4 consisting of an inner enamel layer with a ZnO ratio of <1.0% and a grammage of -480 g / m<sup>2</sup>, and a layer an outer layer of enamel with a ZnO equivalent ratio of <7.7% by weight and a grammage of -293 g / m<sup>2</sup>. (a) Micrograph by Confocal Optical Microscopy of Reflected Light showing crystallizations on the surface of the bactericidal micro-rough enamel. The box indicates the selected area; (b) Atomic Force Microscopy Topography of the selected area, the brightest areas correspond to the highest areas of the surface while the darkest areas correspond to the deepest areas; (c) Characteristic Raman displacement spectra obtained in the selected area, the spectrum called the crystalline phase corresponds to the albite crystallizations and the spectrum called the vitreous phase is characteristic of the areas where the existence of crystallizations is not observed; (d) XY image of the enamel surface showing the location of the crystalline phases corresponding to the albite phase (in lighter color) and the areas with no crystallization corresponding to the vitreous phase (in darker color).
EXAMPLES OF IMPLEMENTATION OF THE INVENTION
The invention will now be illustrated by means of tests carried out by the inventors, which demonstrate the specificity and effectiveness of the process for obtaining enamel materials with a bactericidal effect with the combination of compositions of the invention.
Example n ° 1 Comparative example of the procedure for obtaining micro-rough enamels for ceramic porcelain stoneware floors. Internal Enamel Formulation.
Obtaining a micro-rough enamel on a porcelain stoneware substrate. To carry out this process, the following formulations of raw materials are used in percentages by weight with respect to the total weight:
a) 50% by weight of feldspar, and b) 40% by weight of a frit, and
c) 10% by weight of kaolin.
In the formulation of the internal enamel the composition expressed as a percentage in equivalent oxide with respect to the total is:
a) 55.3% equivalent Si0<sub>2</sub>, and
b) 22.3% equivalent to<sub>2</sub>0<sub>3</sub>, and
c) 8.3% CaO equivalent, and
d) 5.1% Na equivalent<sub>2</sub>0, and
e) 3.1% of K equivalent<sub>2</sub>0, and
f) 3.1% MgO equivalent, and
g) 2.3% of other minority components such as ZnO, B<sub>2</sub>0<sub>3</sub>, Ti0<sub>2</sub>, Faith<sub>2</sub>0<sub>3</sub>, BaO, P<sub>2</sub>0<sub>5</sub>, Sn0<sub>4</sub>, Bi<sub>2</sub>0<sub>3</sub>, or W0<sub>3</sub>, in a concentration of less than 1% each;
The above formulation is homogenized in aqueous medium at a concentration of 60% by weight of solids content. To said mixture, 0.2% by weight of a carboxymethyl cellulose type glue, 0.25% by weight of a sodium tripolyphosphate type dispersant and 0.05% by weight of an adicide type preservative are added. The mixture is homogenized by milling in alumina balls to form a stable suspension with a density greater than 1.7 g / cm.<sup>3</sup>. The deposition of this suspension was carried out by means of an airbrush on the ceramic porcelain paste support with a grammage of 50 grams for a piece measuring 33x33 cm.
The enamel deposited on the support was heat treated at a temperature of 1 198 ° C in an oxidizing atmosphere in a fast firing monostrat oven in a cycle of 50 minutes duration. As a result, a vitreous coating of silky appearance and white color was obtained on the porcelain stoneware support.
This enamel is characterized by presenting a micro-rough surface with Ρ ^ Ο, θδμηι and Rt = 7 ^ m. The enamel surface is also characterized by presenting crystalline phases identified by X-ray diffraction, such as crystalline particles of albite-type feldspar (with ICDD file, International Center for Diffraction Data, JCPDS 041-1480) and anortite (with ICDD file, JCPDS These crystalline phases are generally covered by a vitreous phase layer.
The enamel is characterized by no biocidal activity with values of R = 0 for Staphylococcus aureus and R = 0 for Escherichia coli.
Example n ° 2 Comparative example of the procedure for obtaining micro-rough enamels for ceramic porcelain stoneware floors. External Enamel Formulation.
Obtaining a micro-rough enamel on a porcelain stoneware substrate. To carry out this process, the following formulations of raw materials are used in percentages by weight with respect to the total weight:
a) 46.3% by weight of feldspar, and
b) 37% by weight of a frit, and
c) 9.3% by weight of kaolin, and
d) 7.4% by weight of ZnO.
In the formulation of the internal enamel the composition expressed as a percentage in equivalent oxide with respect to the total is:
e) 50.4% equivalent Si0<sub>2</sub>, and
f) 20.3% equivalent to Al<sub>2</sub>0<sub>3</sub>, and
g) 8.0% CaO equivalent, and
h) 7.7% ZnO equivalent, and
i) 5.0% Na equivalent<sub>2</sub>0, and
j) 2.9% K equivalent<sub>2</sub>0, and
k) 2.8% MgO equivalent, and
I) 2.9% of other minority components such as B<sub>2</sub>0<sub>3</sub>, Ti0<sub>2</sub>, Faith<sub>2</sub>0<sub>3</sub>, BaO, P<sub>2</sub>0<sub>5</sub>, Sn0<sub>4</sub>, Bi<sub>2</sub>0<sub>3</sub>, or W0<sub>3</sub>, in a concentration of less than 1% each; The above formulation is homogenized in aqueous medium at a concentration of 60% by weight of solids content. To said mixture, 0.2% by weight of a carboxymethyl cellulose type glue, 0.25% by weight of a sodium tripolyphosphate type dispersant and 0.05% by weight of an adicide type preservative are added. The mixture is homogenized by milling on alumina balls to form a stable suspension with a density greater than 1.6 g / cm.<sup>3</sup>. The deposition of this suspension was carried out by means of an airbrush on the ceramic porcelain paste support with a grammage of 50 grams for a piece measuring 33x33 cm.
The enamel deposited on the support was heat treated at a temperature of 1 198 ° C in an oxidizing atmosphere in a fast firing monostrat oven in a cycle of 50 minutes duration. As a result, a vitreous coating of silky appearance and white color was obtained on the porcelain stoneware support. This enamel is characterized by presenting a micro-rough surface with Ρ3 = 0.73μηι and Rt = 6 ^ m. The enamel surface is also characterized by presenting crystalline phases identified by X-ray Diffraction, such as crystalline particles of albite and anortite feldspars, as well as gahnite phase particles (with ICDD file JCPDS 82-1043). Said crystalline phases are generally covered by a glassy phase layer.
The enamel is characterized by no biocidal activity with values of R = 1.5 for Staphylococcus aureus and R = 0 for Escherichia coli.
Example 2 was repeated but using a 13% higher weight percentage of ZnO and the resulting enamel is characterized by showing an increase in the formation of gahnite phase. The enamel is characterized by no biocidal activity with values of R = 1, 8 for Staphylococcus aureus and R = 0 for Escherichia coli.
Example n ° 3 Example of a procedure for obtaining micro-rough enamels with bactericidal activity for ceramic porcelain stoneware floors.
Obtaining a micro-rough enamel with a bactericidal effect on a porcelain stoneware substrate. To carry out this process, the described formulations of raw materials in percentages by weight with respect to the total weight described in comparative examples 1 and 2 are used.
Firstly, the suspension of Example 1, called the internal enamel layer, was deposited by means of an airbrush on the ceramic porcelain paste support with a grammage of 50 grams for a piece measuring 33x33 cm.
Secondly, and on the previous deposition, the suspension of Example 2, called the external enamel layer, was deposited by means of an airbrush on the ceramic support of porcelain paste with a grammage of 50 grams for a piece measuring 33x33 cm.
The combination of enamel layers deposited on the support was heat treated at a temperature of 1198 ° C in an oxidizing atmosphere in a fast firing monostrat oven in a cycle of 50 minutes duration. As a result, a vitreous coating of silky appearance and white color was obtained on the porcelain stoneware support. This enamel is characterized by presenting a micro-rough surface with Ρ3 = 0.98μηι and Rt = 7 ^ m. The enamel surface is also characterized by presenting crystalline phases identified by X-ray diffraction, such as crystalline particles of albite and anortite feldspars as well as gahnite phase particles. It should be noted that the presence of gahnite phase particles on the surface is very low compared to the enamels of Example 2. These crystalline phases are partially covered by a glassy phase layer.
The enamel is characterized by no biocidal activity with values of R = 1, 6 for Staphylococcus aureus and R = 0 for Escherichia coli.
Example 3 was repeated but on the deposition of example 1 called the internal enamel layer, in this case the suspension of example 2 called the external enamel layer was deposited, by means of an airbrush on the ceramic support of porcelain paste with a grammage of 15 grams for a piece of 33x33 cm.
The enamel is characterized by biocidal activity with values of R = 5.6 for Staphylococcus aureus and R = 3.6 for Escherichia coli.
The biocidal activity measurement was repeated after keeping the surface of the samples submerged in deionized water by osmosis for 10 days. It should be noted that after the aging test, the biocidal activity is maintained with values of R = 6.0 for Staphylococcus aureus and R = 6.0 for Escherichia coli.
Example 3 was repeated on a 33x33 cm porcelain stoneware substrate using a first layer of enamel with a grammage of 50 g called internal enamel according to the procedure of Example 1, and a second layer of enamel with a grammage of 15 g called the external enamel layer according to the procedure of Example 2, but in this case the composition was made using a mixture of frits with different strength so as to maintain the previously described composition. The rest of the process was continued according to Example 3. It is highlighted that the results were reproduced and as an advantage it is observed that the mixture of different frits favors the adjustment of the composition.
Example n ° 4 Example of the procedure for obtaining micro-rough enamels with bactericidal activity for ceramic porcelain stoneware floors with screen printing decoration.
Obtaining a micro-rough enamel with a bactericidal effect on a porcelain stoneware substrate containing decoration. To carry out this process, the described formulations of raw materials are used in percentages by weight with respect to the total weight described in comparative examples 1 and 2.
Firstly, the suspension of Example 1, called the internal enamel layer, was deposited by means of an airbrush on the ceramic porcelain paste support with a grammage of 52 grams for a piece measuring 33x33 cm.
Secondly and on the previous deposition, a stone-like decoration motif was deposited by silk-screen printing on the internal enamel layer consisting of a decoration using standard inks.
Thirdly, the suspension of example 2, called the external enamel layer, was deposited by means of an airbrush on the ceramic support of porcelain paste with a grammage of 32 grams for a piece measuring 33x33 cm.
The combination of layers of enamel deposited on the support was heat treated at a temperature of 1220 ° C in an oxidizing atmosphere in a fast firing monostrat oven in a cycle of 39 minutes. As a result, a silky-looking vitreous coating was obtained that presents the decoration motif incorporated on the porcelain stoneware support. This enamel is characterized by presenting a micro-rough surface with Ra = 1,15 m and Rt = 12,2Mm.
The enamel is characterized by biocidal activity with values of R = 6.0 for Staphylococcus aureus and R = 2.6 for Escherichia coli.
Example 3 was repeated but in this case the suspension of example 2, called the external enamel layer, was deposited by means of an airbrush on the ceramic support of porcelain paste with a grammage of 16 grams for a piece measuring 33x33 cm.
The enamel is characterized by biocidal activity with values of R = 6.0 for Staphylococcus aureus and R = 6.0 for Escherichia coli. This enamel is characterized by presenting a micro-rough surface with Ra = 1, C ^ m and Rt = 13 ^ m.
It is highlighted that the external enamel layer maintains the decoration motif introduced.
Example 4 was repeated but in this case, once the suspensions of the internal and external enamels had been prepared, the described combination of these enamels was deposited on the substrate by hood. The rest of the process was continued according to Example 4. It should be noted that similar bactericidal activity results were obtained, but in this case there are fewer application surface defects.
Example n ° 5 Example of a procedure for obtaining micro-rough colored enamels with bactericidal activity for ceramic porcelain stoneware floors with decoration.
Obtaining a colored micro-rough enamel with a bactericidal effect on a porcelain stoneware substrate. To carry out this process, the described formulations of raw materials are used, in percentages by weight with respect to the total weight described in comparative examples 1 and 2. In these compositions, 2% by weight of a standard coral pink pigment consisting of Fe- ZrSi0<sub>4</sub> with zircon structure. Modifications by adding pigment give rise to colored enamels. Firstly, the suspension of Example 1, called a modified internal enamel layer with the described pigment addition, was deposited by means of an airbrush on the ceramic porcelain paste support with a grammage of 50 grams for a piece measuring 33x33 cm.
Secondly, the suspension of example 2, called the external enamel layer, was deposited by means of an airbrush on the ceramic porcelain paste support with a grammage of 15 grams for a piece measuring 33x33 cm.
The combination of enamel layers deposited on the support was heat treated at a temperature of 1198 ° C in an oxidizing atmosphere in a fast firing monostrat oven in a 45 minute cycle. As a result, a vitreous coating with a silky appearance and a pink color was obtained on the porcelain stoneware support. This enamel is characterized by presenting a micro-rough surface with Ra = 1, 06 μηι and Rt = 11, 0 μηι.
The enamel is characterized by biocidal activity with values of R = 5.8 for Staphylococcus aureus and R = 3.6 for Escherichia coli.
Example 5 was repeated, but in this case the suspension of Example 2 was deposited, called the modified external enamel layer with the described addition of a pigment, by means of an airbrush on the ceramic support of porcelain paste with a grammage of 15 grams for a piece of 33x33 cm.
The enamel is characterized by biocidal activity with values of R = 6.0 for Staphylococcus aureus and R = 3.6 for Escherichia coli.
Contents5
10 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10
Every citation, both waysCites: the store holds 14 of 15
| Document | Relation | Office | Category | Cited during |
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| CN112521141A | Cited by | China | – | Search report |
| WO2021189822A1 | Cited by | World Intellectual Property Organization (WIPO) | – | International search |
| JP2023044593A | Cited by | Japan | – | Search report |
| CN112479692A | Cited by | China | – | Search report |
| EP0653161A1 | Cites | European Patent Office (EPO) | A | International search |
| EP0921105A1 | Cites | European Patent Office (EPO) | A | International search |
| DE19818956A1 | Cites | Germany | – | Applicant |
| KR20000004200A | Cites | Republic of Korea | – | Applicant |
| WO2006064059A1 | Cites | World Intellectual Property Organization (WIPO) | – | Applicant |
| WO2008152174A1 | Cites | World Intellectual Property Organization (WIPO) | A | International search |
| ES2142249B1 | Cites | Spain | – | Applicant |
| ES2331284A1 | Cites | Spain | A | International search |
| JP3063735B2 | Cites | Japan | – | Applicant |
| US5807641A | Cites | United States of America | – | Applicant |
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| US7141520B2 | Cites | United States of America | – | Applicant |
| JPH07257938A | Cites | Japan | – | Applicant |
| JPH11228186A | Cites | Japan | – | Applicant |
| See also references of EP 2759524A4 | Non-patent | – | – | International search |
| P. ESCRIBANO; J. B. CARDA; E. CORDONCILLO: "Esmaltes y pigmentos Cerámicos", 2001, FAENZA EDITRICE S.L. CASTELLÓN | Non-patent | – | – | Applicant |
5 members in 3 offices
Priority claims4
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|---|---|---|---|
| 201131517 | Spain | A | |
| 201131517 | Spain | A | |
| ES20110031517 | – | – | – |
| P201131517 | – | – | – |
Members5
| Document | Office | Kind | |
|---|---|---|---|
| WO2013041751A1This record | World Intellectual Property Organization (WIPO) | A1 | |
| ES2406354A1 | Spain | A1 | |
| ES2406354B1 | Spain | B1 | |
| EP2759524A1 | European Patent Office (EPO) | A1 | |
| EP2759524A4 | European Patent Office (EPO) | A4 |
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Numbers
- Publication
- 2013/041751
- Publication, DOCDB
- 2013041751
- Publication, EPODOC
- WO2013041751
- Application
- 70655
- Application, DOCDB
- 2012070655
- Application, EPODOC
- WO2012ES70655
Titles3
- English
- COMBINATION AND METHOD FOR OBTAINING BACTERICIDAL CERAMIC ENAMELS FOR CERAMIC PRODUCTS
- Spanish
- COMBINACIÓN Y PROCEDIMIENTO DE OBTENCIÓN DE ESMALTES CERÁMICOS BACTERICIDAS PARA PRODUCTOS CERÁMICOS
- French
- COMBINAISON ET PROCÉDÉ D'OBTENTION D'ÉMAUX CÉRAMIQUES BACTÉRICIDES POUR DES PRODUITS EN CÉRAMIQUE
Classification
- IPC, 2
- C03C8 04
- C04B41 89
Designated states4
- Regional, 4
- Zimbabwe
- Turkmenistan
- Türkiye
- Togo