JP6750348B2 - Sanitary ware with photocatalyst layer - Google Patents

Description

The present invention relates to a highly durable sanitary ware having a photocatalyst layer, and more specifically, the present invention has durability against repeated washing under different liquid conditions of acid and alkali, The present invention relates to sanitary ware having a photocatalyst layer.

A photocatalyst layer is provided on the surface of a glaze layer of a base material having a glaze layer, and a functional member utilizing the decomposition activity or hydrophilic activity of the photocatalyst is used in various applications. For example, a sanitary ware in which a photocatalyst surface layer is formed on the surface of the sanitary ware is known. Such sanitary ware can suppress the attachment of dirt due to the hydrophilicity exhibited by irradiating the photocatalyst layer with light, preferably ultraviolet light, and also can suppress the growth of bacteria by the decomposition action of the photocatalyst. This reduces the cleaning load.

As a photocatalyst layer provided on such a glaze layer surface, a layer containing titanium oxide and a zirconia compound is proposed to have good film strength, water resistance, or abrasion resistance while maintaining good photocatalytic activity. (Japanese Patent Laid-Open No. 2012-206907 (Patent Document 1) and Japanese Patent Laid-Open No. 2014-69098 (Patent Document 2)).

Although the cleaning load is reduced due to the presence of the photocatalyst layer, sanitary ware is generally cleaned at regular intervals using an acidic or alkaline liquid detergent, and to remove dirt. It is slid with a brush or the like and is subjected to physical stress. The photocatalyst layer is required to have a performance capable of withstanding such a load during cleaning for a long period of time, in particular, a property of not losing the activity of the photocatalyst and not peeling.

On the other hand, in order to form a strong photocatalyst film, it is usually necessary to perform high temperature baking at 500 to 1000°C, but under such high temperature, the alkali ions in the glaze of sanitary ware diffuse, which causes photocatalytic activity. Is known to decrease. As a countermeasure against this, it is known to provide an intermediate layer containing silica or the like as a main component between the base material and the photocatalyst layer to suppress the diffusion of alkali ions (for example, JP-A-10-235201 (Patent Document 3). ), JP-A-11-228865 (Patent Document 4), JP-A-2001-152051 (Patent Document 5), and JP-A-2003-277056 (Patent Document 6)). However, these intermediate layers are mainly intended to prevent alkali diffusion, and according to experiments conducted by the present inventors, the durability of the photocatalyst layer containing titanium oxide and a zirconia compound is comparable to that of the present invention. Was inferior to

JP 2012-206907 A JP, 2014-69098, A JP, 10-235201, A Japanese Patent Laid-Open No. 11-228865 JP 2001-152051 A JP, 2003-277056, A

In evaluating the durability of a photocatalyst layer, it has been common practice to test the photocatalyst layer after exposure to an acidic liquid alone or after exposure to an alkaline liquid alone. Then, it was evaluated as having good durability if it maintained a good photocatalytic activity or was difficult to be peeled off even after being exposed to an acidic or alkaline liquid alone, respectively. However, according to the knowledge obtained by the present inventors, in an actual environment of use, for example, cleaning with an acidic liquid cleaning liquid is performed and then cleaning with an alkaline liquid cleaning liquid is performed. However, in such a case, the durability of the conventionally proposed photocatalyst layer may not be sufficient.

The present inventors, when providing a photocatalyst layer containing titanium oxide and zirconium oxide on the glaze layer, contain silica as a main component and titanium oxide and/or zirconium oxide in a specific ratio between them. It was found that the durability of the photocatalyst layer can be greatly improved by providing the layer. In particular, it has been found that excellent durability is exhibited even in a situation where cleaning is repeatedly performed by being alternately exposed to acid and alkali. The present invention is based on such findings.

Therefore, an object of the present invention is to provide a sanitary ware having a photocatalyst layer having excellent durability. In particular, an object of the present invention is to provide a sanitary ware having a photocatalyst layer having excellent durability even in an environment where it is alternately exposed to acid and alkali.

The sanitary ware according to the present invention is a sanitary ware comprising a glaze layer, an intermediate layer provided on the glaze layer, and a photocatalyst layer provided on the intermediate layer.
The photocatalyst layer comprises titanium oxide and zirconium oxide in amounts of 95% by weight to 75% by weight and 5 to 25% by weight, respectively,
The intermediate layer contains silica and titanium oxide and/or zirconium oxide in an amount of 98% by mass to 85% by mass, respectively, and (in the case of containing both titanium oxide and zirconium oxide, as a total thereof) 2% by mass to 15% by mass. It is characterized by including.

Definitions In the present invention, "sanitary ware" means pottery products used around toilets and washrooms, and specifically, urinals, urinals, toilet bowls, toilet tanks, washbasin washbasins, handwashing. Means a vessel, etc. In addition, the term “pottery” refers to a pottery that has a degree of slightly water-absorption of the base material and has a glaze on the surface.

In the present invention, the “durability” of the photocatalyst layer is used as a phrase that individually or comprehensively represents that the photocatalyst layer is difficult to be peeled off and that deterioration of the photocatalytic activity over time is small. It is used as a phrase that individually or collectively represents that the photocatalyst layer is less likely to be peeled off and that the photocatalytic activity is less deteriorated when alternately exposed to the alkaline liquid property.

Acidic means from weakly acidic to strongly acidic, specifically in the range of pH 5 or less, and alkaline means from weakly alkaline to strongly alkaline, specifically pH 8 or more. It means in the range of.

Sanitary Ware According to the Present Invention The sanitary ware according to the present invention is basically a substrate, a glaze layer on the surface thereof, an intermediate layer provided on the glaze layer, and a photocatalyst layer provided on the intermediate layer. Have a structure. Then, the intermediate layer and the photocatalyst layer are composed of a specific composition described later.

The sanitary ware according to the present invention has excellent durability of the photocatalyst layer. In particular, the photocatalyst layer exhibits excellent durability even in an environment where it is alternately exposed to acidity and alkalinity. As described above, in the evaluation of the durability of the photocatalyst layer, it has been general to test the photocatalyst layer after being exposed to an acidic liquid alone or after being exposed to an alkaline liquid alone. .. However, even a conventional photocatalyst layer that shows sufficient durability when evaluated by acid or alkali alone, will be unexpectedly short in a short time when exposed to an environment where it is alternately exposed to acidity and alkalinity. Peeling or deterioration of photocatalytic activity was observed. According to the present invention, there is provided a sanitary ware provided with a photocatalyst layer exhibiting improved durability even under such an environment that is alternately exposed to acidity and alkalinity.

Although not wishing to be bound by a particular theory, the reason why the photocatalyst layer of the sanitary ware according to the present invention is excellent in durability is considered as follows. That is, the photocatalyst layer containing titanium oxide and zirconium oxide has a very slight water permeability, which may cause water to reach the glaze layer surface of the sanitary ware. When the liquid property of this water alternates between acidic and alkaline, the following reaction is promoted. First, acidic water elutes metal elements such as potassium, calcium, magnesium, and zinc in the glaze, and when alkaline water reaches this elution site, the silicon-silicon bond in the vicinity is cleaved. By repeating this, the bond between the glaze layer and the photocatalyst layer becomes weak, and in the worst case, the photocatalyst layer peels off. In the present invention, the intermediate layer is considered to firmly bond the surface of the glaze and the photocatalyst layer while hindering the slight penetration of water. The above description is merely an assumption, and the present invention is not limited to this.

Photocatalyst Layer The photocatalyst layer of the sanitary ware according to the present invention comprises titanium oxide and zirconium oxide in the amounts of 95% by mass to 75% by mass and 5% by mass to 25% by mass, respectively. The preferable lower limit of the content of titanium oxide is 80% by mass, and the preferable upper limit thereof is 90% by mass. The preferable lower limit of the content of zirconium oxide is 10% by mass, and the preferable upper limit thereof is 20% by mass.

In the present invention, titanium oxide is not particularly limited as long as it has photocatalytic activity, and may be either anatase type or rutile type, but anatase type is preferable.

In the present invention, the thickness of the photocatalyst layer may be appropriately determined in consideration of the required photocatalytic activity and other characteristics, but it is preferably about 50 nm to 150 nm, and the more preferable upper limit is 120 nm.

Intermediate Layer In the sanitary ware according to the present invention, the intermediate layer is provided between the glaze layer and the photocatalyst layer of the sanitary ware, and contains silica and titanium oxide and/or zirconium oxide. The content of silica is in the range of 98% by mass to 85% by mass, the preferable upper limit thereof is 95% by mass, and the preferable lower limit thereof is 90% by mass. Moreover, the content of titanium oxide and zirconium oxide is in the range of 2% by mass to 15% by mass as a total when both are contained, and the preferable upper limit is 10% by mass and the preferable lower limit is 5% by mass. is there.

In the present invention, the film thickness of the intermediate layer may be appropriately determined within a range that enhances the durability of the photocatalyst layer, but is preferably about 50 nm to 150 nm, and more preferably the upper limit is 120 nm.

Sanitary Ware Sanitary Ware Base The sanitary ware base of the present invention is not particularly limited and may be a normal sanitary ware base. Further, a glaze layer serving as an intermediate layer may be provided below the outermost glaze layer having the above-mentioned surface texture.

Manufacturing Method The sanitary ware according to the present invention can be preferably manufactured by the following method. That is, first, a pottery base is formed into an appropriate shape by using a sanitary ware base slurry prepared from silica sand, feldspar, clay, etc., by casting using a water-absorbing mold. Then, the glaze raw material is applied to the surface of the dried molded body by appropriately selecting a general method such as spray coating, dip coating, spin coating, or roll coating. The formed body on which the precursor layer of the surface glaze layer has been formed is then fired. The firing temperature is preferably 1,000° C. or higher and 1,300° C. or lower at which the ceramic body is sintered and the glaze is softened.

Glaze The composition of the glaze which forms the glaze layer of the sanitary ware according to the present invention is not limited as long as the above-mentioned surface properties can be realized. In the present invention, the glaze raw material is generally defined as a mixture of natural mineral particles such as silica sand, feldspar, and limestone. The pigment is, for example, a cobalt compound, an iron compound or the like, and the emulsifying agent is, for example, zirconium silicate or tin oxide. Amorphous glaze refers to a glaze obtained by melting a glaze raw material composed of a mixture of natural mineral particles as described above at a high temperature and then rapidly cooling it into a glass, for example, a frit glaze can be preferably used. ..

According to a preferred embodiment of the present invention, a preferable glaze composition is, for example, 10% by weight to 30% by weight of feldspar, 15% by weight to 40% by weight of silica sand, 10% by weight to 25% by weight of calcium carbonate, corundum, talc, dolomite and zinc white. 10 wt% or less, and the total amount of the emulsifying agent and the pigment is 15 wt% or less.

Method for manufacturing sanitary ware according to the present invention The sanitary ware according to the present invention is manufactured by forming the intermediate layer and the photocatalyst layer on the glaze layer of the sanitary ware. The intermediate layer and the photocatalyst layer are basically obtained by calcining silica, titanium oxide and/or zirconium oxide, or their precursors on the glaze layer, and also titanium oxide and zirconium oxide, or their precursors. It is formed by firing on the intermediate layer. Here, the firing for forming the intermediate layer and the photocatalyst layer may be performed each time, or may be performed by firing at the same time. According to a preferred embodiment of the present invention, the intermediate layer and the photocatalyst layer are prepared by preparing a coating liquid containing the above components, applying the coating liquid, and then baking the coating liquid.

According to one embodiment of the present invention, the photocatalyst layer is produced by applying a coating solution containing titanium oxide and zirconium oxide or a precursor thereof, preferably applying and then firing. You can do it. According to a preferred embodiment of the present invention, a coating liquid containing titanium alkoxide and zirconium alkoxide is used as a titanium oxide precursor and a zirconium oxide precursor, and the coating liquid is baked to obtain a photocatalyst layer.

In the present invention, titanium alkoxide and titanium chelate can be preferably used as the precursor of titanium oxide. The titanium alkoxide is basically represented by the general formula: Ti(OR) ₄ , and is not limited as long as it produces a photocatalytic titanium oxide by hydrolysis. Part of (OR) in the formula may be substituted with acetylacetonate (C ₅ H ₇ O ₂ ) or ethyl acetoacetate (C ₆ H ₉ O ₃ ). According to a preferred embodiment of the present invention, titanium alkoxide (preferably C _1-6) a lower organic radical R moieties of the alkoxide (RO-) are those wherein the alkyl group. Specific preferred examples thereof include tetraethoxy titanium, tetraisopropoxy titanium, tetra n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium, titanium diisopropoxy bis (acetylacetonate), titanium diisopropoxy bis (ethyl acetoacetate). ) And mixtures thereof. Examples of titanium chelates include titanium tetraacetylacetonate.

Further, zirconium alkoxide and zirconium chelate can be preferably used as the precursor of zirconium oxide. The zirconium alkoxide is basically represented by the general formula: Zr(OR) ₄ , and is not limited as long as it produces zirconium oxide by hydrolysis. Part of (OR) in the formula may be substituted with acetylacetonate (C ₅ H ₇ O ₂ ) or ethyl acetoacetate (C ₆ H ₉ O ₃ ). According to a preferred embodiment of the present invention, the organic group R moiety of the alkoxide (RO ⁻ ) is a zirconium alkoxide, and the organic group R moiety of the alkoxide (RO ⁻ ) is a lower (preferably C _2-6 ) alkyl group. is there. Specific preferred examples thereof include zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetrabutoxide, zirconium tributoxy monoacetylacetonate, zirconium dibutoxybis(ethylacetoacetate), zirconium monobutoxyacetylacetonate bis(ethyl). Acetoacetate) and mixtures thereof. Further, examples of the ruconium chelate include zirconium tetraacetylacetonate.

In the present invention, the intermediate layer can be produced by applying, preferably applying, a coating liquid containing silica and titanium oxide and/or zirconium oxide, or a precursor thereof, and then firing. .. According to a preferred embodiment of the present invention, examples of the silica precursor include alkyl silicates such as methyl silicate and ethyl silicate, and polymers thereof. As the titanium oxide precursor and the zirconium oxide precursor, those exemplified for the photocatalyst can be preferably used.

As a solvent for the coating liquid, alcohols such as ethanol, isopropanol, and normal butanol, cellosolves such as methyl cellosolve and butyl cellosolve, aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate. However, it is not particularly limited as long as it is a solvent in which titanium alkoxide and zirconium alkoxide are dissolved.

In addition to the above components, for example, a surfactant such as a leveling agent can be added to the coating liquid in order to improve the uniformity of the coating layer.

The application of the coating liquid to sanitary ware may preferably be carried out by a commonly used method such as brush coating, roller, spray, roll coater, flow coater, dip coating, flow coating, screen printing and the like.

The sanitary ware to which the coating liquid for forming the intermediate layer and the photocatalyst layer is applied is subjected to a firing process. Firing may be performed with the intermediate layer and then with the photocatalyst layer, but according to a preferred embodiment of the present invention, firing is performed simultaneously. The firing conditions may be appropriately determined, but for example, it may be carried out at a temperature of 700 to 900° C. for about 5 hours, preferably at a temperature of 750 to 850° C. for about 0.5 to 3 hours.

As is clear from the above, according to a preferred aspect of the present invention, there is provided a method for manufacturing a sanitary ware according to the present invention. In this method, a coating liquid in which a silicon alkoxide or a hydrolyzate thereof and a titanium alkoxide and/or a zirconium alkoxide are mixed is applied onto a glaze layer of sanitary ware, and the titanium oxide precursor and the zirconium oxide precursor are applied. Is applied, and then firing is carried out at a temperature of 750 to 850° C.

The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

Preparation of coating liquid for forming intermediate layer Silica alkoxide (alkoxysilane hydrolysis liquid, manufactured by Colcoat Co., Ltd.) and titanium alkoxide (titanium diisopropoxybis(acetylacetonate), NDH-510C, manufactured by Nippon Soda Co., Ltd.) Alternatively, zirconium alkoxide (compound name: zirconium tributoxy monoacetylacetonate, trade name: Organix ZC-540, manufactured by Matsumoto Fine Chemical Co., Ltd.), and the weight ratio of the solid content after firing and the proportions described in the table below Mixed so that Next, this mixture was diluted with a mixed solvent of 2-propanol (80%) and methyl cellosolve (20%) so that the solid content after firing was 0.5%, and the diluted solution was mixed with a stirrer. The obtained mixed liquid was left standing for 1 hour or more, and this was used as a coating liquid for forming an intermediate layer.

Preparation of coating liquid for forming photocatalyst layer Titanium alkoxide (Compound name: titanium diisopropoxybis(acetylacetonate) Trade name: NDH-510C, manufactured by Nippon Soda Co., Ltd.) and zirconium alkoxide (Compound name: zirconium tributoxy). Monoacetylacetonate (trade name: Organix ZC-540, manufactured by Matsumoto Fine Chemical Co., Ltd.) is mixed so that the weight ratio of titanium oxide/zirconium oxide solid content after firing is the ratio described in the following table. did. Next, this mixture was diluted with a mixed solvent of 2-propanol (80%) and methyl cellosolve (20%) so that the solid content after firing was 0.5%, and the diluted solution was mixed with a stirrer. The obtained mixed liquid was left standing for 1 hour or more, and this was used as a coating liquid.

Preparation of pottery tile A pottery raw material was cast and molded to obtain a base material, and a glaze was applied to the surface of the base material using a hand spray gun (F100 manufactured by Meiji Machine Mfg. Co., Ltd.). Subsequently, while gradually raising and lowering the temperature, it was passed through a tunnel kiln set to a maximum temperature of 1180° C. for 24 hours and fired to obtain a ceramic tile. The glaze used had a composition within the following range.
Glaze composition
SiO ₂ 55-80% by weight
Al ₂ O _{3 5 to} 13% by weight
Fe ₂ O ₃ 0.1-0.4 wt%
MgO 0.8-3% by weight
CaO 8-17% by weight
ZnO 3-8 wt%
K ₂ O 1-4% by weight
Na ₂ O 0.5-2.5 wt%
ZrO 0.1-15% by weight
Pigment 0.01-5% by weight

Using a hand spray gun (F100, manufactured by Meiji Kikai Seisakusho Co., Ltd.), the coating liquid for forming an intermediate layer obtained above was applied to the surface of the ceramic tile obtained in the formation of the intermediate layer to a film thickness of 50 nm after firing. The coating amount was controlled so as to achieve the above.

Formation of a photocatalyst layer and firing A photocatalyst layer-forming coating obtained above using a hand spray gun (F100 manufactured by Meiji Kikai Seisakusho Co., Ltd.) on the surface of a ceramic tile coated with the coating liquid for forming an intermediate layer obtained above Coating was performed by controlling the coating amount so that the film thickness after baking the liquid would be 50 nm.

Then, while gradually raising and lowering the temperature, it was fired for 24 hours in a high temperature electric furnace (manufactured by FUH732DA ADVANTEC Co., Ltd.) set to a maximum temperature of 800° C. to obtain a photocatalyst coated tile.

Photocatalytic activity The photocatalytic activity of the photocatalytic coating tile was evaluated by the methylene blue decomposition index according to JIS R1703-2. The results were evaluated according to the following criteria.
Decomposition index is 7 or more: ○
5 or more and less than 7: △
Decomposition index less than 5: ×
The results are shown in the table below.

Acid/Alkali Durability Test A test apparatus was prepared in which acidic water (pH 3.5) and alkaline water (pH 9.5) were alternately flown out at 2 minute intervals for 10 seconds, and a photocatalyst-coated tile was installed under running water of this apparatus. At this time, both acidic water and alkaline water were applied to make one cycle.

After a lapse of a predetermined cycle, a tape peeling test was carried out based on JISK5600-5-6. The results were evaluated according to the following criteria.
No peeling in 14000 cycles: ◎
Peeling occurred over 10,000 cycles and up to 14,000 cycles: ○
Peeling occurred over 6000 cycles and up to 10,000 cycles: △
Peeling occurred up to 6000 cycles: ×
The results are shown in the table below.

Sliding resistance test A rubbing tester (manufactured by Taihei Rika Kogyo Co., Ltd.) was used to perform a sliding resistance test of the photocatalyst-coated tile. Urethane sponge (Scotch Bright (SS-72K, manufactured by Sumitomo 3M Co., Ltd.)) was cut into 2.24 cm square pieces and bonded to the head using a double-sided tape so that the non-woven fabric part hits the sliding surface, and then distilled water. I got wet with. Then, a weight of 250 g was placed (loading condition: 5 kPa) and slid a predetermined number of times, and the presence or absence of scratches on the surface was visually confirmed. The urethane sponge was replaced with a new one after every 1000 slides. The results were evaluated according to the following criteria.
No visible scratches after sliding 20000 times: ◎
There are scratches that can be visually recognized after sliding 10,000 times to 20,000 times: ○
There are scratches visible after sliding 2000 times to 10,000 times: △
There are scratches visible when sliding up to 2000 times: ×
The results are shown in the table below.

The numerical values in the table are mass% or values based on it.

Claims (9)

A sanitary ware comprising a glaze layer, an intermediate layer provided on the glaze layer, and a photocatalyst layer provided on the intermediate layer.
The photocatalyst layer comprises titanium oxide and zirconium oxide in amounts of 95% by weight to 75% by weight and 5 to 25% by weight, respectively,
The intermediate layer contains silica and titanium oxide and/or zirconium oxide in an amount of 98% by mass to 85% by mass, respectively, and (in the case of containing both titanium oxide and zirconium oxide, as a total thereof) 2% by mass to 15% by mass. Sanitary ware characterized by comprising. The sanitary ware according to claim 1, wherein the intermediate layer comprises silica and titanium oxide, the silica content is 90 to 98% by mass, and the titanium oxide content is 2 to 10% by mass. The sanitary ware according to claim 2, wherein the silica content is 90 to 95% by mass, and the titanium oxide content is 5 to 10% by mass. The sanitary ware according to claim 1, wherein the intermediate layer contains silica and zirconium oxide, the silica content is 90 to 98% by mass, and the zirconium oxide content is 2 to 10% by mass. The sanitary ware according to claim 4, wherein the silica content is 90 to 95% by mass, and the zirconium oxide content is 5 to 10% by mass. The sanitary ware according to any one of claims 1 to 5, wherein the titanium oxide content of the photocatalyst layer is 90 to 80 mass% and the zirconium oxide content is 10 to 20 mass%. The sanitary ware according to any one of claims 1 to 6, wherein the intermediate layer has a film thickness of 50 to 150 nm. The sanitary ware according to any one of claims 1 to 7, wherein the photocatalyst layer has a film thickness of 50 to 150 nm. A method for manufacturing a sanitary ware according to any one of claims 1 to 8,
On the glaze layer of sanitary ware, apply a coating liquid in which silicon alkoxide or its hydrolyzate and titanium alkoxide and/or zirconium alkoxide are mixed,
Furthermore, a coating liquid containing the titanium oxide precursor and the zirconium oxide precursor is applied,
Then, the manufacturing method of the sanitary ware characterized by including the process of baking at the temperature of 750-850 degreeC.