JPH10195380A - Primer composition for adhering photocatalystic titanium oxide particle to plastic substrate, and photocatalytic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a primer which enables a thin titanium oxide film to adhere to a hydrophobic substrate such as a polyvinyl chloride substrate or an ethylene- tetrafluoroethylene copolymer substrate by compounding a tetraalkoxytitanium, a tetraalkoxysilane, an alkyl silicate, and a liq. alcohol. SOLUTION: A tetraalkoxytitanium, a tetraalkoxysilane, an alkyl silicate, and a liq. alcohol at least a part of which contains a liq. alcohol having a mol.wt. of 60-300 are compounded. This primer can firmly bond a plastic substrate to a thin titanium oxide film at a low temp., such as a temp. in the range of room temp. to 150 deg.C. Pref. a hardly decomposable curable binder (pref. a silcone or silica) is incorporated into a layer contg. photocatalytic titanium oxide particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to polyvinyl chloride,
The present invention relates to a primer composition for forming a photocatalytic titanium oxide thin film having good adhesion at low temperature on a plastic substrate such as polycarbonate, ethylene-tetrafluoroethylene copolymer, and polyethylene terephthalate.

[0002]

2. Description of the Related Art When a photocatalytic titanium oxide thin film is formed on a base material, when electrons are irradiated with ultraviolet rays, electrons in the valence band of the titanium oxide crystal are photo-excited due to the semiconductivity of the titanium oxide, thereby causing conduction electrons. And holes. Then, it is said that, based on the oxidizing power of the holes and the reducing power of the conduction electrons, the quantum energy can cause an oxidation-reduction reaction under conditions that cannot normally occur. Applications that effectively utilize the oxidizing power of holes include, for example, deodorization, removal of pollutant gases such as NOx and SOx,
Antibacterial and antifouling, antifouling based on antibacterial and algae generation prevention, decomposition of adhered oil, synthesis of phenol and carbonyl compounds, removal of organic chlorine, and the like have been proposed. As applications that effectively utilize the reducing power of conduction electrons, for example, removal of heavy metals in waste liquids, deposition of metals on circuit boards, production of hydrogen, reduction of carbon dioxide, and the like have been proposed. When the electrons in the valence band of the titanium oxide crystal are photoexcited, not only the above-mentioned redox reaction, but also the surface of the member is hydrophilized accordingly, whereby the present invention can also maintain the hydrophilic surface permanently. Have been found by others. This phenomenon is a reaction that occurs when polarities are imparted to the surface, presumably by the action of conduction electrons and holes, thereby adsorbing chemically adsorbed water on the surface and forming a layer of physically adsorbed water thereon. As applications using the photohydrophilizing action, for example, prevention of fogging of the transparent member, prevention of loss of visibility due to rainfall or splashing of the transparent member, and simple removal of dirt by rainfall or washing have been proposed.

[0003]

However, a titanium oxide thin film having the above function is coated on a polyvinyl chloride substrate having a hydrophobic surface or an ethylene-tetrafluoroethylene copolymer substrate at room temperature to about 150 ° C. When the material was fixed at a low temperature, the compatibility between the two materials was poor, and it was not possible to secure strong adhesion. Therefore, in the present invention, a primer composition that enables a titanium oxide thin film to be fixed to a substrate such as a polyvinyl chloride substrate having a hydrophobic surface or an ethylene-tetrafluoroethylene copolymer substrate is provided. The purpose is to provide.

[0004]

According to the present invention, there is provided a primer composition for fixing a photocatalytic titanium oxide to a plastic substrate, which comprises: (a) a tetraalkoxytitanium; (b) It is intended to provide a primer composition containing (c) an alkyl silicate (d) a liquid alcohol. With this primer composition, the plastic substrate and the titanium oxide thin film can be firmly adhered at a low temperature of about room temperature to about 150 ° C. The reasons are probably affected by the following three points. When the primer is applied, the alkyl portion of the liquid alcohol is well compatible with the plastic, so that the primer layer is uniformly coated. Since a monomer composed of tetraalkoxytitanium and tetraalkoxysilane is added to the alkyl silicate, cross-linking by the monomer is easily promoted,
Even at room temperature, a primer layer having a high degree of polymerization is formed. In particular, since tetraalkoxy titanium having a high hydrolysis rate is contained, cross-linking is more easily promoted. In addition, the coexistence of tetraalkoxysilane with tetraalkoxytitanium prevents the rate of hydrolysis from being too high and suppresses the formation of white turbidity and cracks. Accordingly, a primer layer having a high degree of polymerization and free from cloudiness or cracks is formed. When tetraalkoxytitanium is hydrolyzed, titanium hydroxide, tetraalkoxysilane and alkyl silicate are hydrolyzed to produce silanol.However, the surface composed of these substances has good wettability of the titanium oxide paint, so that And good adhesion of titanium oxide to the primer-coated surface. In particular, titanium hydroxide produced by hydrolysis of tetraalkoxytitanium and amorphous titanium oxide produced by its dehydration reaction have very good wettability of titanium oxide paint, and adhesion of titanium oxide to primer-coated surface Improve the performance.

[0005] In a preferred embodiment of the present invention, at least a part of the liquid alcohol has a molecular weight of 60 to 200. By setting the molecular weight to 60 or more, the evaporation rate of the liquid alcohol can be reduced. When the evaporation rate of the liquid alcohol is reduced, the alkyl silicate is polymerized to a state where the alkyl portion of the liquid alcohol is well compatible with the plastic to such an extent that the primer layer has a sufficient film-forming property. It becomes easier to keep it long until it becomes, so that the adhesion between the plastic substrate and the primer layer can be further improved.

Further, in the present invention, the photocatalytic titanium oxide particle-containing layer is formed on the surface of the plastic substrate via a layer formed by curing the primer composition according to claim 1. A photocatalytic member is provided. By interposing a layer formed by curing the primer composition according to claim 1, a photocatalytic member having excellent adhesion to a plastic substrate can be formed.

[0007] In a preferred embodiment of the present invention, the layer containing photocatalytic titanium oxide particles contains a hardly decomposable curable binder. By binding the photocatalytic titanium oxide particle-containing layer with a hard-to-decompose curable binder, without a high-temperature heat treatment such as sintering of the photocatalytic titanium oxide particles, at a low temperature of about room temperature to about 150 ° C, It becomes possible to form a wear-resistant photocatalytic titanium oxide particle-containing layer.

In a preferred embodiment of the present invention, the hardly decomposable curable binder is silicon or silica. By using silicone or silica as the hardly decomposable curable binder, it becomes easy to highly hydrophilize to about 0 °, especially in the photohydrophilic action by a photocatalyst, and also in a dark place. , The hydrophilicity retention property is also exhibited.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The components of the present invention will be described below. As the tetraalkoxytitanium, tetramethoxytitanium, tetraethoxytitanium, tetrabutoxytitanium, tetraisopropoxytitanium and the like can be suitably used.

As the tetraalkoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetraisopropoxysilane, dimethoxydiethoxysilane and the like can be suitably used.

As the alkyl silicate, methyl silicate, ethyl silicate, ethyl methyl silicate,
Propyl silicate, butyl silicate and the like can be suitably used.

The liquid alcohols include methanol, ethanol, isopropanol, n-propanol and t-
Butanol, n-butanol, isobutanol, 2-methylpropanol, ethylene glycol, pentanol
, Diacetone alcohol, propylene glycol, ethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, ethylene glycol monoethyl ether, tripropylene glycol, tripropylene glycol monoethylene ether and the like can be suitably used. In particular, isopropanol having a molecular weight of 60 or more, n
-Propanol, t-butanol, n-butanol, isobutanol, 2-methylpropanol, ethylene glycol, pentanol, diacetone alcohol, propylene glycol, ethylene glycol monomethyl ether, Dipropylene glycol monomethyl ether, ethylene glycol monoethyl ether, tripropylene glycol, and tripropylene glycol monoethylene ether are preferred because of their low evaporation rates. The above liquid alcohol
May be used as a mixture of two or more.

The plastic substrate which can be used in the present invention is not particularly limited, but examples thereof include a polyvinyl chloride substrate, an ethylene-tetrafluoroethylene copolymer substrate, a polyester substrate and a polycarbonate substrate. -Base material, polymethacrylate base material, polyethylene base, polypropylene base, polyethylene terephthalate base, urethane resin base, styrene resin base, epoxy resin base, melamine resin base, alkyd resin It can be suitably used for base materials and the like.

Photocatalytic titanium oxide is light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction electron band and the valence band of an oxide crystal.
Of electrons in the valence band when irradiated with light (photoexcitation)
Refers to crystalline titanium oxide that can generate conduction electrons and holes, and anatase-type titanium oxide, rutile-type titanium oxide, and the like can be suitably used.

To form a cured layer of the primer composition on the surface of a plastic substrate, the primer composition is spray-coated, flow-coated, dip-coated, It is applied by a method such as roll coating and cured. The curing of the primer composition is promoted by forming a crosslink by hydrolysis or dehydration-condensation polymerization of the primer composition by heat treatment or standing at room temperature.

The thickness of the layer containing the photocatalytic titanium oxide particles is preferably set to 0.2 μm or less. Then, color formation of the layer due to light interference can be prevented. Also, the thinner the surface layer, the more transparent the member can be. Furthermore, the thinner the film, the better the wear resistance of the layer. The surface of the above layer may be further provided with a wear-resistant or corrosion-resistant protective layer capable of being made hydrophilic and other functional films. Preferably, the layer has a refractive index not too high compared to the substrate. Preferably, the layer has a refractive index of 2 or less. Then, light reflection at the interface between the primer and the layer can be suppressed. Metals such as Ag, Cu, and Zn can be added to the surface layer. The surface layer to which the metal is added can kill bacteria adhering to the surface.
Furthermore, this surface layer inhibits the growth of microorganisms such as molds, algae and moss. Therefore, adhesion of dirt on the member surface due to microorganisms can be more effectively suppressed. The surface layer has P
Platinum group metals such as t, Pd, Rh, Ru, Os, Ir can be added. The surface layer to which the metal is added can enhance the oxidizing activity of the photocatalyst, and promote the decomposition of contaminants attached to the member surface.

The hard-to-decompose curable binder in the present invention refers to a binder that does not undergo a decomposition-degradation reaction due to the oxidizing action of the photocatalyst or has a very low decomposition rate. As the hardly decomposable curable binder, silicone, silica, acrylic silicone resin, fluororesin, alumina, water glass and the like can be suitably used.

Examples of the silicone include trimethoxymethylsilane, triethoxymethylsilane, triisopropoxymethylsilane, trichloromethylsilane, tribromomethylsilane, tri-t-butoxymethylsilane, trichloroethylsilane, tribromoethylsilane, Trimethoxyethylsilane, triethoxyethylsilane, triisopropoxyethylsilane, tri-t-butoxyethylsilane, n-propyltriethoxysilane, n-propyltrimethoxysilane, n-propyltribromosilane,
n-propyltrichlorosilane, n-propyltri-t-
Butoxysilane, n-propyltriisopropoxysilane, 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, phenyltrit Butoxysilane, dimethyldimethoxysilane, dimethyldichlorosilane, dimethyldibromosilane, dimethyldiethoxysilane, diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldichlorosilane, phenylmethyldichlorosilane Bromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane,
Tri-t-butoxyhydrosilane, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane, trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, Trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltri-t-butoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane Silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane , Γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl Triethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri-t-butoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxy Silane, γ
-Aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane , Γ-mercaptopropyltriethoxysilane, γ
-Mercaptopropyltriisopropoxysilane, γ-
Mercaptopropyltri-t-butoxysilane, β-
Hydrolysis of silane derivatives such as (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane,
Dehydration polycondensation; or hydrolysis of a partial hydrolyzate of the above silane derivative, dehydration polycondensation; or silicone formed by dehydration polycondensation of low molecular weight silicone produced by partial hydrolysis or dehydration polycondensation of the silane derivative And the like can be suitably used.

Examples of the silica include hydrolysis and dehydration condensation polymerization of tetrahalogenated silanes such as tetrachlorosilane and tetrabromosilane; or tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetraisopropoxysilane, dimethoxydiethoxy. Hydrolysis and dehydration condensation polymerization of tetraalkoxysilane such as silane; or hydrolysis and dehydration condensation polymerization of alkyl silicate such as methyl silicate, ethyl silicate, ethyl methyl silicate, propyl silicate and butyl silicate And the like produced by the above method can be suitably used.

As the acrylic silicone resin, silicon-
And a block copolymer of a polymethacrylate resin and an acrylic resin, and a composite of a polymethacrylate resin and a silicone resin. The content of the silicon component in the resin may be any as long as it is strong against oxidative deterioration by the photocatalyst, but the silicon content is preferably 5% to 80%, and particularly preferably 10% to 60%. For the purpose of increasing the surface strength or the flexibility, silica may be added to the acrylic silicone resin, two or more acrylic silicone resins may be mixed, or a silicone resin may be added. Here, as the silicone resin, a silicone resin, an alkyd-modified silicone resin, a urethane-modified silicone resin, a polyester-modified silicone resin, an epoxy-modified silicone resin, or the like can be used. Mixing a light stabilizer with the acrylic silicone resin is effective in improving durability. As the light stabilizer, a hindered amine type or the like can be used. In addition, an ultraviolet absorber such as triazole may be mixed.

Examples of the fluorine-based resin include polyvinyl fluoride, polyvinylidene fluoride, poly (ethylene trichloride), polytetrafluoroethylene, ethylene tetrafluoride-propylene hexafluoride copolymer, and ethylene-tetrafluoride. Ethylene copolymer, ethylene-ethylene chloride trifluoride copolymer, ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer, perfluorocyclopolymer, vinyl ether-fluoroolefin copolymer, A vinyl ester-fluoroolefin copolymer or the like can be suitably used.

The method of forming a layer containing photocatalytic titanium oxide and silicone on the surface of the primer layer is performed by using photocatalytic titanium oxide and the above silane derivative or a partial hydrolyzate of the silane derivative or the above low molecular weight silicone. Silicon such as
A coating solution containing a precursor of the coating is applied to the surface of the primer layer by a method such as spray coating, flow coating, dip coating, roll coating, and the like, and the silicone is cured. Depending on The curing of the silicone is promoted by forming a crosslink by hydrolysis and dehydration-condensation polymerization of the precursor by heat treatment or standing at room temperature.

A method for forming a layer containing photocatalytic titanium oxide and silica on the surface of the primer layer is performed by using a photocatalytic titanium oxide and the above-mentioned silica such as tetrahalogenated silane or tetraalkoxysilane or the above alkyl silicate. The coating solution containing the precursor is applied to the surface of the primer layer by a method such as spray coating, flow coating, dip coating, roll coating, and the like, and cured. The curing of the silica precursor
The precursor is hydrolyzed by heat treatment or standing at room temperature, and crosslinked by dehydration-condensation polymerization to form a crosslink and proceed.

[0024]

【Example】

Embodiment 1 FIG. (Polyvinyl chloride base material) 7.5 g of ethyl silicate (Corcot Co., pentamer)
And 7.5 g of tetraethoxysilane (Wako Pure Chemical) and 0.1 g of tetraethoxytitanium (Wako Pure Chemical), diluted with 111.8 g of methanol, and added with 23.3 g of 2% nitric acid aqueous solution And hydrolyzed to obtain a stock solution. Thereafter, the stock solution was diluted 5-fold with ethanol to give a primer solution # 1.
A sample was obtained. The primer liquid # 1 sample is applied to a polyvinyl chloride plate by a flow coating method, and then dried at room temperature (20 ° C.) for 20 minutes to harden the primer coating film, and thereafter, a corona discharge treatment As a result, a # 2 sample was obtained. # 2 The sample surface was uniformly transparent, and no poor appearance such as cracks was observed. A tape peeling test was performed to examine the adhesion between the polyvinyl chloride plate and the primer coating film. In the tape peeling test, when the cellophane tape was adhered from one end to the other end of the coating film surface and then quickly peeled off, evaluation was made based on whether or not the coating film peeled off at the same time. As a result, no peeling was particularly observed. Next, 75 parts by weight of a 98% tetraethoxysilane solution and a photocatalytic coating solution STK01 (a composition comprising an anatase type titanium oxide, an alkyl silicate, water, methanol and propanol) manufactured by Ishihara Sangyo Co., Ltd. After mixing 25 parts by weight and stirring for 1.5 hours after mixing to hydrolyze the tetraethoxysilane,
Top coating solution # 3 diluted 25-fold with ethanol
A sample was obtained. The top coating liquid # 3 sample was applied to the primer coating surface of the # 2 sample by the flow coating method, and then dried at room temperature (20 ° C.) for 20 minutes to cure the top coating liquid film. , # 4 sample was obtained. #
4 The surface of the sample was uniformly transparent, and no poor appearance such as cracks was observed. A tape peeling test was performed to examine the adhesion between the primer coating film and the top coating film. As a result, no peeling was particularly observed. further#
Four samples were examined for photohydrophilicity by photoexcitation. Photo-hydrophilization by photo-excitation is achieved by applying an ultraviolet illuminance of 0.5 m on the surface of # 4 sample.
W / cm ² light source (Sankyo Electric, Black Light Bull-
(BLB) fluorescent lamp) for 24 hours, and examined by measuring the contact angle of the surface of the # 4 sample with water after the irradiation. Here, the contact angle with water is measured using a contact angle measuring instrument (Kyowa Interface Science, CA
-X150), and measured 30 seconds after a water drop was dropped on the sample surface from the microsyringe. As a result, the contact angle with water was 0 °, and it was confirmed that the particles were superhydrophilized.

Embodiment 2 FIG. (Ethylene-tetrafluoroethylene copolymer base material) The primer liquid # 1 sample of Example 1 was applied to an ethylene-tetrafluoroethylene copolymer plate by a flow coating method, and then room temperature (20 ° C). ) Was dried for 20 minutes to cure the primer-coated film, followed by a corona discharge treatment to obtain a # 5 sample. The surface of the # 5 sample was uniformly transparent, and no poor appearance such as cracks was observed. Ethylene-
A tape peeling test was performed to examine the adhesion between the tetrafluoroethylene copolymer plate and the primer coating film. As a result, no peeling was particularly observed. Next, after applying the top coating liquid # 3 sample of Example 1 to the primer coating surface of the # 5 sample by the flow coating method, the top coating solution # 3 was cooled to room temperature (20%).
C.) for 20 minutes to harden the top-coating film, to obtain a # 6 sample. The # 6 sample surface was uniformly transparent, and no defective appearance such as cracks was observed.
A tape peeling test was performed to examine the adhesion between the primer coating film and the top coating film. As a result, no peeling was particularly observed. Furthermore, the photohydrophilization of the # 6 sample by photoexcitation was examined. The photo-hydrophilization by photo-excitation is performed by irradiating the surface of the # 6 sample with a light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp) having an illuminance of 0.5 mW / cm ² for 24 hours. It was determined by measuring the contact angle with water. Here, the contact angle with water was measured using a contact angle measuring device (Kyowa Interface Science, CA-X150) 30 seconds after a water droplet was dropped on the sample surface from the micro syringe. As a result, the contact angle with water was 0 °, and it was confirmed that the particles were superhydrophilized.

Embodiment 3 FIG. (Polycarbonate base material) The primer liquid # 1 sample of Example 1 was applied to a polycarbonate plate by a flow coating method, and then dried at 120 ° C. for 15 minutes to obtain a primer. Cure the coating, #
Seven samples were obtained. The surface of the # 7 sample was uniformly transparent, and no poor appearance such as cracks was observed. A tape peeling test was conducted to examine the adhesion between the polycarbonate plate and the primer coating film. As a result, no peeling was particularly observed. Next, the top coating liquid # 3 sample of Example 1 was applied to the primer coating surface of the # 7 sample by a flow coating method, and then dried at room temperature (20 ° C.) for 20 minutes to obtain a top coating solution. -The coating was cured to give a # 8 sample. The # 8 sample surface was uniformly transparent, and no poor appearance such as cracks was observed. A tape peeling test was performed to examine the adhesion between the primer coating film and the top coating film. As a result, no peeling was particularly observed. Further, the photohydrophilization of the # 8 sample by photoexcitation was examined.
The photo-hydrophilization by light excitation is performed by irradiating the surface of the # 8 sample with a light source (Sankyo Electric, Black Light Bull (BLB) fluorescent lamp) having an ultraviolet illuminance of 0.5 mW / cm ² for 24 hours. It was determined by measuring the contact angle with water. Here, the contact angle with water was measured using a contact angle measuring device (Kyowa Interface Science, CA-X150) 30 seconds after a water droplet was dropped on the sample surface from the micro syringe. As a result, the contact angle with water was 0 °, and it was confirmed that the particles were superhydrophilized.

Embodiment 4 FIG. (Polyethylene terephthalate base material) After the primer liquid # 1 sample of Example 1 was applied to a polyethylene terephthalate film by a flow coating method,
The primer coating film was cured by drying at room temperature (20 ° C.) for 20 minutes to obtain a # 9 sample. The surface of the # 9 sample was uniformly transparent, and no poor appearance such as cracks was observed. A tape peeling test was performed to examine the adhesion between the film and the primer coating film. As a result, no peeling was particularly observed. Next, the top coating liquid # 3 sample of Example 1 was flow-coated on the primer coating surface of the # 9 sample.
After coating by the coating method, the coating is dried at room temperature (20 ° C.) for 20 minutes to cure the top coating film,
A # 10 sample was obtained. # 10 The sample surface is uniformly transparent,
No appearance defects such as cracks were observed. To check the adhesion between the primer coating film and the top coating film,
A tape peel test was performed. As a result, no peeling was particularly observed. Further, the photohydrophilization of the # 10 sample by photoexcitation was examined. The photohydrophilization by light excitation is performed by irradiating the surface of the # 10 sample with a light source (Sankyo Electric, Black Light Bull- (BLB) fluorescent lamp) having an illuminance of 0.5 mW / cm ² for 24 hours. It was determined by measuring the contact angle with water. Here, the contact angle with water was measured using a contact angle measuring device (Kyowa Interface Science, CA-X150) 30 seconds after a water droplet was dropped on the sample surface from the micro syringe. As a result, the contact angle with water was 0 °, and it was confirmed that the particles were superhydrophilized.

[0028]

According to the present invention, a primer for fixing photocatalytic titanium oxide particles to a plastic substrate contains a primer composition containing tetraalkoxytitanium, tetraalkoxysilane, alkyl silicate, and liquid alcohol. Since the material is used, the photocatalytic titanium oxide particles can be fixed on the plastic substrate at low temperature with good adhesion.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 185/00 C09D 185/00

Claims (5)

[Claims] 1. A primer composition for fixing photocatalytic titanium oxide particles to a plastic substrate, comprising: (a) tetraalkoxytitanium (b) tetraalkoxysilane (c) alkyl silicate (d) liquid alcohol -A primer composition comprising: 2. The primer composition according to claim 1, wherein at least a part of the liquid alcohol has a molecular weight of 60 to 300. 3. The method according to claim 1, wherein the surface of the plastic substrate is
3. A photocatalytic member, wherein a layer containing photocatalytic titanium oxide particles is formed via a layer formed by curing the primer composition described in 1. above. 4. The photocatalytic member according to claim 3, wherein the photocatalytic titanium oxide particle-containing layer contains a hardly decomposable curable binder. 5. The photocatalytic member according to claim 4, wherein said hardly decomposable curable binder is silicon or silica.