JP2001112851A - Member for bathroom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member for bathroom, which can prevent sticking and generation of slime without requiring human hands, and can keep the surface clean. SOLUTION: This member for bathroom is coated with a photocatalyst, which is optically excited to have the surface super-hydrophilized to 10 deg. or lower in terms of a contact angle with water. A hydrophobic organic substance such as water-insoluble soap scum or fat is not only hard to stick to the surface which is super-hydrophilized, but also easily washed away when poured with a shower or wetted with water, so the surface of the photocatalyst layer is kept clean. In this member for bathroom, microbes existing on the surface, such as germs, mildew or yeast comes directly into contact with the surface of the photocatalyst layer, and is effectively killed by the photooxidation of the photocatalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing so-called "slime" from adhering to or forming on a bathroom member such as a bathroom floor, a washing place, a bathtub, a bathroom side wall, a sash, and a bathroom stool.

[0002]

2. Description of the Related Art It is well known that so-called "slime" adheres to the floor of a bathroom, a bathtub, a side wall of a bathroom, and a bed of a bathroom. The slimy skin not only gives an unsanitary impression, but also is slippery and can cause a fall if you are not careful.

[0003] Slime is considered to be a mixture of microorganisms such as bacteria, molds and yeasts, secretions thereof, dirt from the human body such as fats and proteins, and decomposition products thereof. In order to remove the slime, it was necessary to clean the bathroom floor, the sash, etc. with a detergent and a scrubber, so that it took time to manage the bathroom.

Japanese Patent Application Laid-Open No. 6-154118 (Matsushita Electric Industrial)
It has been proposed to prevent the adhesion of slime by coating the bathtub with a coating composed of a highly water-repellent fluoropolymer and an antibacterial agent. As described above, the conventional wisdom was that water-repellent materials were considered to be less likely to adhere to dirt, but recently, water-repellent materials have an affinity for fats and oils, such as fat contained in human scales. It has been pointed out that lipophilic substances are more likely to be attached.

[0005] In WO 94/11092 (Tohoku Kikai), a photocatalytic coating is provided on the surface of a substrate such as a tile, and the photocatalyst is photoexcited by weak ultraviolet rays radiated from indoor lighting such as a fluorescent lamp. It is disclosed that antimicrobial and contaminant decomposition can be performed by using the method.

However, if this technique is applied to the removal of slime in a bathtub or a washing place, in the bathtub or the washing place, insoluble so-called "soap scum" which is a reaction product between human scale and soap and lipophilic organic contamination are produced. As the substance attaches to the surface of the photocatalytic coating, the active sites of the photocatalytic coating are shielded from microorganisms such as bacteria, molds and yeast. As a result, the antibacterial function of the photocatalyst is not sufficiently exhibited.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bathroom member capable of preventing the attachment and generation of "slimming" without requiring any manpower and keeping the surface clean. .

[0008]

Means for Solving the Problems The present inventor has discovered that a photocatalyst has a hydrophilizing action in addition to the conventionally known antibacterial action and photooxidation-reduction action. Surprisingly, the photocatalytic titania was photoexcited and found that the surface was highly hydrophilized to a contact angle with water of 10 ° or less, more specifically 5 ° or less, and especially about 0 °. Was done.

The present invention is based on such a finding, and the present invention cleans bathroom members such as bathroom floors, washing areas, bathtubs, bathroom side walls, pens, bathroom stools, and prevents slime adhesion. Provide a way. According to the present invention, the surface of the bathroom member is coated with a layer containing a semiconductor photocatalyst. When the photocatalyst is photoexcited, the photocatalyst is activated and the surface of the photocatalyst layer is hydrophilized. The photoexcitation is performed until the surface of the photocatalyst layer is hydrophilized to a contact angle with water of about 10 ° or less, preferably about 5 ° or less.

[0010] The surface which has been highly hydrophilized in this way is naturally exposed to water droplets or wetness with bathing, washing and use of showers. Highly hydrophilized surfaces have no affinity for soap scum or lipophilic organic pollutants,
These contaminants are easily released from the surface and are washed away with water each time the bathroom is used. Therefore, the surface of the photocatalyst layer is kept clean. As a result, microorganisms such as bacteria, molds, and yeasts attached to the surface of the bathroom member come into direct contact with the surface of the photocatalyst layer, and are effectively killed or grown by the photooxidation action of the photocatalyst. Can be suppressed.

The above-mentioned features and effects of the present invention, as well as other features and advantages, will be apparent from the description of the following embodiments.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface of a bathroom member is covered with a semiconductor photocatalyst layer. The thickness of the photocatalyst layer is preferably set to 0.2 μm or less. With such a film thickness, the photocatalyst layer can be made sufficiently transparent, and color formation due to light interference can be prevented.

The most preferred photocatalyst is titania (TiO ₂ ). Titania is harmless, chemically stable, and available at low cost. As photocatalytic titania, any of anatase and rutile can be used. An advantage of anatase titania is that a sol in which very fine particles are dispersed can be easily obtained on the market, and a very thin thin film can be easily formed. On the other hand, rutile-type titania can be sintered at a high temperature, and has an advantage that a film having excellent strength and wear resistance can be obtained.

When the bathroom member is coated with a photocatalytic layer of titania and the titania is photoexcited with ultraviolet light, the surface of the photocatalytic layer is converted to a contact angle with water of 10 ° or less, more specifically 5 ° or less, and especially about 0 °. It becomes superhydrophilic to the extent that it becomes ゜. It is believed that water is chemically adsorbed on the surface in the form of hydroxyl groups (OH-) by photocatalysis, resulting in the surface becoming superhydrophilic.

Other usable photocatalysts include ZnO and SnO.
₂ , metal oxide semiconductors such as SrTiO ₃ , WO ₃ , Bi ₂ O ₃ , and Fe ₂ O ₃ . These metal oxides, like titania,
Since metal elements and oxygen exist on the surface, surface hydroxyl groups (OH
-) It is thought to absorb.

The photocatalyst layer may be formed of any one of the above photocatalysts, or may be formed of a mixture thereof. In particular, when silica or tin oxide is mixed with photocatalytic titania, the surface can be highly hydrophilized.

The photocatalytic semiconductor is photoexcited by light having a wavelength having energy equal to or greater than its band gap energy. When the photocatalyst is, for example, anatase type TiO ₂ or ZnO, the photocatalyst can be photoexcited by ultraviolet rays having a wavelength of 387 nm or less, and when the photocatalyst is rutile type TiO ₂ , ultraviolet rays having a wavelength of 413 nm or less can be excited. As the ultraviolet light source, a fluorescent lamp, an incandescent lamp, a metal halide lamp, a mercury lamp, a fluorescent mercury lamp, and other electric lamps can be used. In order to make the surface of the photocatalyst layer superhydrophilic so that it becomes about 0 ° in terms of the contact angle with water,
It is preferable to irradiate ultraviolet rays with sufficient illuminance for a sufficient time. However, once the surface of the photocatalyst layer is highly hydrophilized, the superhydrophilicity can be sufficiently maintained even with weak ultraviolet rays emitted from a fluorescent lamp or the like. Under conditions where sunlight enters the bathroom, sunlight can be used during the day.

When the bathroom member is formed of a heat-resistant base material such as a tile or an enameled product, it has a super-hydrophilic property such that the contact angle with water becomes 0 ° and is excellent in abrasion resistance. A preferred way of forming the photocatalytic layer is to first coat the surface of the substrate with amorphous titania and then to convert the amorphous titania to crystalline titania (anatase or rutile) by calcination. For forming amorphous titania, any of the following methods can be employed.

(1) Hydrolysis and dehydration of an organotitanium compound An alkoxide of polycondensed titanium such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, and hydrochloric acid or ethylamine After adding such a hydrolysis inhibitor and diluting with an alcohol such as ethanol or propanol, while partially or completely allowing hydrolysis to proceed, the mixture is spray-coated, flow-coated, It is applied to the surface of a substrate by spin coating, dip coating, roll coating or other coating methods, and dried at a temperature of from room temperature to 200 ° C. By drying, the hydrolysis of the alkoxide of titanium is completed to produce titanium hydroxide, and a layer of amorphous titania is formed on the surface of the base material by dehydration-condensation polymerization of titanium hydroxide. Instead of titanium alkoxides, other organic titanium compounds such as titanium chelates or titanium acetate may be used. (2) Formation of amorphous titania with inorganic titanium compound An acidic aqueous solution of an inorganic titanium compound, for example, TiCl ₄ or Ti (SO ₄ ) ₂ is spray-coated, flow-coated, spin-coated, dip-coated, and roll-coated to form a substrate. Apply to the surface. Then, the inorganic titanium compound is subjected to hydrolysis and dehydration-condensation polymerization by drying at a temperature of about 100 ° C. to 200 ° C. to form an amorphous titania layer on the surface of the substrate. Alternatively, amorphous titania may be applied to the surface of the substrate by chemical vapor deposition of TiCl ₄ . (3) Formation of Amorphous Titania by Sputtering Amorphous titania is deposited on the surface of the substrate by irradiating an electron beam on a metal titanium target in an oxidizing atmosphere. (4) Firing temperature The firing of amorphous titania is performed at least at the crystallization temperature of anatase or higher. If calcined at a temperature of 400 ° C. to 500 ° C. or more, amorphous titania can be converted to anatase type titania. By firing at a temperature of 600 ° C. to 700 ° C. or higher, amorphous titania can be converted to rutile type titania.

When the bathroom member is covered with a glaze such as a tile or an enamel product, an intermediate layer such as silica is preferably formed in advance between the substrate and the amorphous titania layer. This prevents the alkali network modifying ions in the glaze from diffusing from the base material into the photocatalyst layer during firing of amorphous titania, realizing superhydrophilicity with a contact angle with water of 0 ° Is done.

Another preferred method of forming a photocatalytic layer exhibiting superhydrophilicity with a contact angle with water of 0 ° and having excellent abrasion resistance is based on a photocatalytic coating comprising a mixture of titania and silica. It is to form on the surface of the material. The ratio of silica to the total of titania and silica can be 5 to 90 mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. Any of the following methods can be used for forming a photocatalytic coating composed of silica-containing titania.

(1) A suspension containing particles of anatase type or rutile type titania and particles of silica is applied to the surface of a substrate and sintered at a temperature lower than the softening point of the substrate. (2) precursors of amorphous silica (for example, tetraalkoxysilanes such as tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, etc .; silanol which is a hydrolyzate thereof); Alternatively, a mixture of a polysiloxane having an average molecular weight of 3000 or less) and crystalline titania sol is applied to the surface of the base material, and if necessary, hydrolyzed to form silanol. Is subjected to dehydration polycondensation to form a photocatalytic coating in which titania is bound with amorphous silica.
In particular, if the dehydration-condensation polymerization temperature of silanol is performed at a temperature of about 200 ° C. or higher, the degree of polymerization of silanol can be increased, and the alkali resistance performance of the photocatalytic coating can be improved. (3) Dispersing silica particles in a solution of amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) The resulting suspension is applied to the surface of a substrate, and the titanium compound is subjected to hydrolysis and dehydration condensation polymerization at a temperature of from room temperature to 200 ° C. to form a thin film of amorphous titania in which silica particles are dispersed. . Next, the amorphous titania is changed into crystalline titania by heating to a temperature equal to or higher than the crystallization temperature of titania and equal to or lower than the softening point of the substrate. (4) Precursor of amorphous silica in a solution of precursor of amorphous titania (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) Body (eg, tetraethoxysilane, tetraisopropoxysilane, tetran
A mixture of tetraalkoxysilanes such as propoxysilane, tetrabutoxysilane, and tetramethoxysilane; silanol which is a hydrolyzate thereof; or polysiloxane having an average molecular weight of 3000 or less), and coating the mixture on the surface of the substrate. Next, these precursors are subjected to hydrolysis and dehydration condensation polymerization to form a thin film composed of a mixture of amorphous titania and amorphous silica. Next, the amorphous titania is changed into crystalline titania by heating to a temperature equal to or higher than the crystallization temperature of titania and equal to or lower than the softening point of the substrate.

Still another preferred method of forming a photocatalytic coating with excellent abrasion resistance that exhibits superhydrophilicity such that the contact angle with water is 0 ° is a photocatalytic coating comprising a mixture of titania and tin oxide. To form a coating on the surface of a substrate. The ratio of tin oxide to the total of titania and tin oxide is 1 to 95% by weight, preferably 1 to 50%.
% By weight. Any of the following methods can be used for forming the photocatalytic coating composed of tin oxide-containing titania. (1) A suspension containing particles of anatase or rutile type titania and particles of tin oxide is applied to the surface of a substrate, and sintered at a temperature equal to or lower than the softening point of the substrate. (2) Tin oxide particles in a solution of a precursor of amorphous titania (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) The suspension obtained by dispersing is applied to the surface of the substrate, and the titanium compound is subjected to hydrolysis and dehydration condensation polymerization at a temperature of from room temperature to 200 ° C., thereby forming a thin film of amorphous titania in which tin oxide particles are dispersed. Form. Next, the amorphous titania is changed into crystalline titania by heating to a temperature equal to or higher than the crystallization temperature of titania and equal to or lower than the softening point of the substrate.

When the bathroom member is formed of a non-heat-resistant material such as plastic, it is preferable to form a photocatalytic layer having a superhydrophilic property such that the contact angle with water becomes 0 ° when light is excited. An approach is to use a coating composition comprising photocatalyst particles dispersed in a film-forming element consisting of uncured or partially cured silicone (organopolysiloxane) or a silicone precursor. After applying this coating composition to the surface of a bathroom member and curing the film-forming element, the photocatalyst is photoexcited, and the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the photocatalytic action of the photocatalyst. The surface of the photocatalyst layer is made superhydrophilic.

The coating film forming components of the coating composition include methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltrit
-Butoxysilane; ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane,
Ethyl tri-t-butoxysilane; n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-propyltri-t-butoxysilane; n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane; n-decyltrichlorosilane, n -Decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltriisopropoxysilane, n-decyltri-t-butoxysilane; n-octadecyltrichlorosilane, n
-Octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-
Octadecyltri-t-butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane; tetrachlorosilane, tetrabromosilane,
Tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, Diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, tri-t -Butoxyhydrosilane; vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyl Triethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane , Trifluoropropyltri-t-butoxysilane;
γ-glycidoxypropylmethyldimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane; γ-methacryloxypropylmethyldimethoxysilane Γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri t-butoxysilane; γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ
-Aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane; γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane Γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane; And their partial hydrolysates; and mixtures thereof.

It is preferable to add an antibacterial metal such as Ag, Cu or Zn to the photocatalyst layer. Ag for photocatalyst,
To add Cu or Zn, soluble salts of these metals can be added to a suspension of photocatalytic particles and the resulting solution used to form a photocatalytic coating. Alternatively, after forming the photocatalytic coating, a soluble salt of these metals may be applied, and photoreduced precipitation may be performed by light irradiation. The photocatalyst layer doped with Ag, Cu, or Zn exhibits antibacterial performance even when light cannot be excited, such as at night.

On the surface which has been highly hydrophilized in this way,
Hydrophobic contaminants such as soap scum and organic matter are hard to adhere. Also, even if attached, the superhydrophilized surface has much greater affinity for water than it does for hydrophobic contaminants, so that when wetted with water, there is water between the surface and the contaminants. Enter and release contaminants from the surface. Therefore, when the surface of the bathroom member is exposed to water splash or wet with the use of a bath, a washing place, or a shower, the contaminants are easily released from the surface and washed away with water. Thus, each time the bathroom is used, the surface of the photocatalyst layer is kept clean since the contaminants are washed away with water. As a result, microorganisms such as bacteria, molds, and yeasts attached to the surface of the bathroom member come into direct contact with the surface of the photocatalyst layer, and are effectively killed or grown by the photooxidation action of the photocatalyst. Can be suppressed.

[0028]

EXAMPLES Example 1 Anatase type titania sol (Ishihara Sangyo, STS-11, average particle size 0.01 μm) was applied to the surface of a 10 cm square glazed tile (TOTO Kiki, AB02E01) by a spray coating method. It was baked at the temperature for 2 hours. Next, a 1% by weight aqueous solution of silver nitrate was applied to the sample by a spray coating method, and irradiated with ultraviolet rays for several minutes using a 4 W black light blue (BLB) fluorescent lamp (Sankyo Electric Co., Ltd.) to decompose silver nitrate. The silver was precipitated to obtain a sample A. The contact angle of the surface of Sample A with water was 8 °.

For sample A and a glazed tile without a photocatalyst layer (sample B) for comparison, the change in slipperiness and the adhesion of dirt with use were tested. Therefore, sample A
And Sample B were placed on the floor of a public bath in an employee dormitory located in Chigasaki City and observed. This public bath is illuminated with fluorescent lights at normal illuminance at night.

The slipperiness was evaluated by the ratio of the maximum static friction coefficient at the time of measurement to the initial maximum static friction coefficient (maximum static friction coefficient ratio). The maximum static friction coefficient is determined by wetting a sample surface with water, placing a 0.5 kg weight on the sample, applying a force in the horizontal direction, and measuring the force when the weight starts to move. ). The adhesion state of the stain was evaluated by the ratio of the glossiness at the time of measurement to the initial glossiness (specific glossiness). The reflectance was measured using a gloss meter (Nippon Denshoku Industries) according to JIS Z8741, and the specific gloss was determined from the change in the reflectance.

The measurement results are shown in the graphs of FIG. 1 and FIG. As can be seen from these graphs, in the glazed tile without the photocatalyst layer (sample B), the maximum static friction coefficient decreases with use, and the glazed tile gradually becomes slippery and the adhesion of dirt increases. On the other hand, in the glazed tile provided with the photocatalyst layer (sample A), the initial maximum static friction coefficient is maintained, and the adhesion of dirt is small.

Example 2 Anatase type titania sol (Ishihara Sangyo, STS-11) and colloidal silica sol (Nissan Chemical, Snowtex O) were mixed at a molar ratio of solids of 88:12, and a 15 cm square glazed tile ( TOTO EQUIPMENT, AB02E0
Apply to the surface of 1) by spray coating method, 800
The sample was baked at a temperature of 1 ° C. for 1 hour to obtain a sample covered with a coating composed of titania and silica. The thickness of the coating was 0.3 μm. The contact angle with water immediately after firing was 5 °. After leaving the sample in the dark for one week, the contact angle with water was 5 °. When the surface of the sample was irradiated with ultraviolet rays at a UV illuminance of 0.03 mW / cm ² for one day using a BLB fluorescent lamp (Sankyo Electric, FL20BLB), the contact angle with water became 0 °.

Example 3 Anatase type titania sol (STS-
11) and colloidal silica sol (Nissan Chemical, Snowtex 20) were mixed at a molar ratio of solids of 80:20, applied to the surface of a 15 cm square glazed tile (AB02E01) by spray coating, and heated at 800 ° C. The sample was baked at a temperature for 1 hour to obtain a sample covered with a film composed of titania and silica. The thickness of the coating was 0.3 μm. The contact angle with water immediately after firing was 5 °. After leaving the sample in the dark for two weeks, the contact angle with water was 14 °. When the surface of the sample was irradiated with ultraviolet light at 0.004 mW / cm ² for 1 day using a white fluorescent lamp, the contact angle with water became 4 °. Therefore, it can be seen that the film is sufficiently hydrophilized even under indoor lighting.

Example 4 In 86 parts by weight of a solvent of ethanol, 6 parts by weight of tetraethoxysilane Si (OC ₂ H ₅ ) ₄ (Wako Pure Chemical Industries, Ltd.), 6 parts by weight of pure water and 36 parts by weight of a hydrolysis inhibitor for tetraethoxysilane % Hydrochloric acid was added and mixed to prepare a silica coating solution. Since the solution generated heat by mixing, the mixture was left to cool for about 1 hour. This solution was applied to the surface of a 10 cm square soda lime glass plate by a flow coating method, and dried at a temperature of 80 ° C. With drying, tetraethoxysilane was hydrolyzed to silanol Si (OH) _{4 first} , and then a thin film of amorphous silica was formed on the surface of the glass plate by dehydration condensation polymerization of silanol.

Next, tetraethoxytitanium Ti (OC ₂ H ₅ )
₄ (Merck) To a mixture of 1 part by weight of ethanol and 9 parts by weight of ethanol was added 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor to prepare a titania coating solution, and this solution was dried on the surface of the glass plate. It was applied by a flow coating method in air. The coating amount was 45 μg / cm ² in terms of titania. Since the rate of hydrolysis of tetraethoxytitanium was extremely fast, part of the tetraethoxytitanium was hydrolyzed at the coating stage, and titanium hydroxide Ti (OH) ₄ began to form.

Next, this glass plate is placed on the glass plate for about 10 minutes for about 150 minutes.
By maintaining the temperature at ° C., hydrolysis of tetraethoxytitanium was completed, and the produced titanium hydroxide was subjected to dehydration condensation polymerization to produce amorphous titania. Thus, a glass plate in which amorphous titania was coated on amorphous silica was obtained. The glass plate was fired at a temperature of 500 ° C. to convert amorphous titania to anatase titania.

After leaving this sample in a dark place for several days,
0.5mW on the surface of the sample using a BLB fluorescent lamp (FL20BLB)
The sample was irradiated with ultraviolet light at an ultraviolet illuminance of / cm ² for about 1 hour to obtain a # 1 sample. For comparison, a glass plate not coated with titania was prepared and used as a # 2 sample.

The contact angle between the # 1 sample and the # 2 sample with water was measured with a contact angle measuring device (Model CA-X150, manufactured by Kyowa Interface Science Co., Ltd.). The lower angle side detection limit of this contact angle measuring instrument was 1 °. The contact angle was measured 30 seconds after a water drop was dropped on the sample surface from the micro syringe. The reading of the measuring instrument with respect to water on the surface of the # 1 sample was 0 °, indicating superhydrophilicity. On the other hand, the contact angle of the # 2 sample with water was 30 to 40 °.

Oleic acid was applied to the surface of the # 1 sample,
When the glass plate was immersed in the water filled in the water tank while keeping the surface of the glass plate in a horizontal posture, oleic acid was curled into oil droplets, released from the surface of the glass plate, and floated.

Example 5 In this example, 10 cm was used as the base material.
A square aluminum substrate was used. In order to smooth the surface of the substrate, it was previously coated with a silicone layer. For this reason,
Liquid A (silica sol) and liquid B (trimethoxymethylsilane) of Nippon Synthetic Rubber Coating Composition “Glaska”
The liquid and the liquid B are mixed so that the weight ratio becomes 3: 1. This mixed liquid is applied to an aluminum substrate, cured at a temperature of 150 ° C., and coated with a 3 μm-thick silicone base coat. An aluminum substrate (# 1 sample) was obtained.

Next, the # 1 sample was coated with a titania-containing paint. More specifically, a mixture of anatase titania sol (Nissan Chemical Co., TA-15) and solution A (silica sol) of the above “Glaska” is diluted with ethanol, and then the above solution B of “Glaska” is added, and the titania-containing paint is added. Composition was prepared. The composition of the coating composition was 39 parts by weight of silica, 97 parts by weight of trimethoxymethylsilane, and titania 8
It was 7 parts by weight. This coating composition was applied to the surface of a # 1 sample and cured at a temperature of 150 ° C. to form a top coat in which anatase-type titania particles were dispersed in a silicone coating, to obtain a # 2 sample.

Next, a 0.5% BLB fluorescent lamp was used for the # 2 sample.
The sample was irradiated with ultraviolet light at an illuminance of mW / cm ² for 5 days to obtain a # 3 sample. The contact angle of the surface of this sample with water is measured using a contact angle measuring device (ER
(Manufactured by MA Company), the contact angle reading was less than 3 °. The contact angle of the # 2 sample before ultraviolet irradiation was measured and was found to be 70 °. When the contact angle of the # 1 sample was measured, it was 90 °. Further, the # 1 sample was irradiated with ultraviolet rays for 5 days under the same conditions as the # 2 sample, and the contact angle was measured. As a result, the contact angle was 85 °.

From this, it can be seen that when a photocatalyst is contained in silicone and the photocatalyst is photoexcited, the silicone coating is highly hydrophilized. It is considered that the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by photocatalysis, and a hydrophilic silicone derivative is formed on the surface.

Example 6 In this example, an acrylic resin plate was used as a base material. In order to prevent the acrylic resin plate from being deteriorated by the photocatalyst, the surface of the acrylic resin plate was previously coated with a silicone layer. Therefore, in the same manner as in Example 5, the A solution and the B solution of "Glaska" were mixed to prepare a coating solution. This coating solution was applied to the surface of a 10 cm square acrylic resin plate and cured at a temperature of 100 ° C. to obtain a plurality of acrylic resin plates (# 1) coated with a 5 μm-thick silicone base coat.

Next, anatase-type titania sol (Nissan Chemical Co., TA-15) and the above-mentioned “Glaska” solution A were mixed, diluted with ethanol, and further added with “Glaska” solution B. Was prepared. The compositions of these coating solutions were adjusted so that the ratio of the weight of titania to the sum of the weight of titania, the weight of silica, and the weight of trimethoxymethylsilane was 5%, 10%, 50%, and 80%, respectively. Apply each coating solution to the acrylic resin plate coated with a silicone layer,
To form a top coat in which anatase-type titania particles are dispersed in a silicone coating film.
A # 5 sample was obtained. 0.5mW of BLB fluorescent lamp for # 1 to # 5 samples
The contact angle of water on the surface of these samples was measured at different time intervals with a contact angle measuring device (made by ERMA) while irradiating ultraviolet rays with an illuminance of / cm ^{2 for} a maximum of 200 hours, and the temporal change of the contact angle Was observed. The results are shown in the graph of FIG.

As can be seen from the graph of FIG. 3, in the # 1 sample having no titania-containing layer, there was almost no change in the contact angle with water even when irradiated with ultraviolet rays. On the other hand, it can be seen that the samples # 2 to # 5 provided with the titania-containing topcoat are hydrophilized until the contact angle with water becomes less than 10 ° in response to the ultraviolet irradiation. In particular, in the samples # 3 to # 5 in which the ratio of titania is 10% by weight or more, the contact angle with water is 3 ° or less. Furthermore, the titania content is 50% by weight and 80% by weight, respectively.
It is noted that the contact angle with water becomes 3 ° or less for the 4 samples and the # 5 sample by short-time ultraviolet irradiation. After leaving the # 4 sample in a dark place for two weeks, a contact angle measurement device (CA-X15
When the contact angle with water was measured according to 0), the contact angle with water was 3 ° or less.

[0047]

According to the bathroom member of the present invention, the surface of the photocatalyst layer of the bathroom member is highly hydrophilized by the hydrophilizing action of the photocatalyst. And the surface of the photocatalyst layer is always kept clean. Therefore, microorganisms such as bacteria, molds and yeasts attached to the surface of the bathroom member come into direct contact with the photocatalyst, and are effectively killed or inhibited from growing by the photooxidation action of the photocatalyst. . Therefore, the occurrence of "sliminess" on the surface of the bathroom member is prevented without requiring special maintenance.

[Brief description of the drawings]

FIG. 1 is a graph showing test results of Example 1.

FIG. 2 is a graph showing test results of Example 1.

FIG. 3 is a graph showing test results of Example 6.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) E03C 1/20 E03C 1/20 A // A61L 2/16 A61L 2/16 Z (72) Inventor Atsushi Kitamura 2-1, 1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka

Claims (2)

[Claims] 1. The surface of a bathroom member is coated with a layer containing a semiconductor photocatalyst, and the surface of the layer is hydrophilized to about 10 ° or less in terms of a contact angle with water by photoexcitation of the photocatalyst. Activating the photocatalyst and exposing the surface of the layer to water splashes or water wetting to wash away contaminants attached to the surface of the layer and to remove bacteria and microorganisms attached to the surface of the layer. A bathroom member characterized in that the surface is cleaned by killing or suppressing its growth by the photooxidation action of a photocatalyst. 2. The surface of a bathroom member is covered with a layer containing a semiconductor photocatalyst and an antibacterial metal, and the photocatalyst is photoexcited to convert the surface of the layer to a contact angle of about 10 ° with water. The photocatalyst is activated together with hydrophilization below, and the surface of the layer is exposed to water splashes or wetness to wash water to wash away contaminants attached to the surface of the layer, and adhered to the surface of the layer. A bathroom member characterized in that the surface is cleaned by killing bacteria or microorganisms by the antibacterial action of the antibacterial metal or suppressing their growth.