JP4653877B2 - Method and composition for immobilizing photocatalyst - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a method of fixing a photocatalyst on the surface of an object for the purpose of deodorization, air purification, antifouling including surface hydrophilization, antibacterial and the like, particularly an organopolysiloxane independent film and an organopolysiloxane coating formed on a substrate surface. The present invention relates to a method for fixing a photocatalyst on a film. The present invention also relates to a coating composition for use in such a photocatalyst fixing method.
[0002]
[Background technology and issues]
A photocatalyst typified by titanium oxide is known to generate active oxygen species upon irradiation with near ultraviolet light in the presence of oxygen and water to oxidize the substance. Utilizing this phenomenon, the photocatalyst is used to remove malodorous substances and contaminants in the air, and to impart antifouling property, self-cleaning property, antibacterial property and the like to the object surface.
[0003]
Since the photocatalyst is generally a powder, it must be fixed using a solid matrix or binder in order to be used for the above purpose. Since the photooxidation action of photocatalyst, particularly titanium oxide, is strong, when an organic substance is used as a matrix or binder, the photocatalyst itself cannot be fixed for a long time because it is decomposed by the photooxidation action itself. For this reason, as the material of the matrix or binder, only inorganic materials such as cement and silica, or materials that are difficult to be decomposed by the photo-oxidation action such as fluororesin and silicone resin can withstand practical use.
[0004]
In immobilizing the photocatalyst, it is important that the photocatalyst particles are firmly held and that the matrix or binder to be retained is not deteriorated by the photocatalytic action. There is a drawback of reducing the original photocatalytic function.
[0005]
For this reason, JP-A-5-253544 discloses a method of fixing many photocatalyst particles in an exposed state by, for example, applying a glaze to the tile surface, spraying a titanium oxide sol on the surface and then baking at a high temperature. ing. However, this method is limited to a substrate that can withstand high temperatures such as 300 to 850 ° C.
[0006]
In JP-A-11-323194, for example, acrylic modified silicone is applied as an adhesive layer on the surface of a substrate such as a PET film, and a photocatalyst is dispersed in an organic solvent such as alcohol containing silica sol as a binder on the adhesive layer. A method for producing a composite material having a hydrophilic photocatalytic surface comprising applying a coating liquid is disclosed. Even in this method, silica or silicone is necessary not only as a binder but also to provide a hydrophilic surface, and even if it is possible to immobilize many photocatalysts on the surface, the effective specific surface area is still lowered. I can't escape. Further, heating is required for curing the adhesive layer and the photocatalyst coating layer. Such heating cannot be applied to large objects or structures fixed on the ground.
[0007]
Therefore, it is desired to develop a method capable of fixing most of the photocatalyst in an exposed state at room temperature.
[0008]
[Solutions to the problem]
In the present invention, an organopolysiloxane film is used as a support member for the photocatalyst particles. This film may be an independent film prepared in advance by a sol-gel method, or may be a coating film formed on the substrate surface by a sol-gel method.
[0009]
According to the present invention, a coating liquid containing a photocatalyst dispersed in a dispersion medium containing a specific organic solvent is applied to the surface of the organopolysiloxane film. The organic solvent used here must soften the organopolysiloxane of the film by swelling. As the photocatalyst, for example, an aqueous sol obtained by peptizing anatase-type titanium oxide to a colloidal state, or an organosol by solvent substitution can be used. It is preferable that the coating liquid contains substantially no binder. Here, “substantially free” means that when the coating composition of the present invention is applied to a substrate that is not swollen and softened, it does not contain an amount of binder sufficient to firmly hold the photocatalyst thereon. It is.
[0010]
Since the dispersion medium of the coating liquid contains an organic solvent that swells and softens the film, the photocatalyst particles are easily trapped on the softened film surface, and the film is solidified again by evaporation of the solvent by air drying. It is firmly held on the surface. At this time, since the coating liquid does not substantially contain a binder, the effective specific surface area of the photocatalyst is not significantly reduced.
[0011]
The organopolysiloxane film can be formed as a stand-alone film or a coating film on a substrate by a sol-gel method from a silicone oligomer solution obtained by partial hydrolysis of alkoxysilane mainly composed of trialkoxysilane. At this time, it is possible to carry out all the steps of the present invention including the formation of the organopolysiloxane film at room temperature by using a room temperature curing type silicone oligomer solution.
[0012]
Therefore, the method of the present invention can be applied to plastics, wood, paper, and the like that are deformed and altered by heating, and can also be applied to large objects that cannot be heated or structures fixed on the ground.
[0013]
Organopolysiloxane is generally transparent and has a hydrophilic surface by photocatalytic action. Therefore, the present invention can be applied to anti-fogging of mirrors, lenses, window glass and the like.
[0014]
Detailed Description of Embodiments of the Invention
In the photocatalyst fixing method of the present invention, a photocatalyst dispersion containing an organic solvent that swells and softens the organopolysiloxane in the dispersion medium is applied to the organopolysiloxane film to soften the film surface layer, and the solvent is volatilized. The photocatalyst is fixed along with the solidification of the surface layer of the film. Application of the photocatalyst dispersion liquid can be performed at any time before dry-drying of the organopolysiloxane film to the touch.
[0015]
As the photocatalyst used, TiO ₂ , ZnO, SnO ₂ , SrTiO _Three , WO _Three Etc. Among them, anatase type titanium oxide is most preferable in consideration of photocatalytic ability and chemical durability. Further, two or more kinds of these photocatalysts may be mixed and used as desired.
[0016]
The photocatalytic coating composition of the present invention can be prepared using fine particles, sol or metal alkoxide. As titania powder, ST-01, ST-11, ST-21 or ST-31 from Ishihara Sangyo Co., Ltd., and AMT-100, AMT-600 and TITANIX JA-1 from Teika Co., Ltd. Are offered to the market. As the titania sol, for example, TKS-201, TKS-202, TKS-203 and TKS-251 brand sols from Teika Co., Ltd. can be used. Other titania powders and sols corresponding to these can also be used.
[0017]
The organic solvent used in the photocatalyst coating composition of the present invention, which softens the surface layer of the organopolysiloxane film by swelling, has a high affinity with the organopolysiloxane film and a boiling point of 200 ° C. capable of softening the film. Hereinafter, a volatile oxygen-containing solvent having a temperature of preferably 170 ° C. or lower can be used. As these oxygen-containing solvents, alcohols, ketones and carboxylic acid esters are particularly preferable. Examples of alcohols include methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, and tert-butyl alcohol. Also, alcohols having ether groups such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol can be used. Examples of ketones include acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, and methyl isobutyl ketone. Examples of carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. These compounds can also be used as a mixture of two or more. Furthermore, it is more preferable to include at least one component having a boiling point of 100 ° C. or higher in order to exert a softening effect. These components can be appropriately selected according to the components of the organopolysiloxane film, the degree of curing (crosslinking density), and the like. In the case where the curing of the organopolysiloxane film is proceeding, it is preferable to add a large amount of relatively high boiling alcohols and ketones. In addition, the carboxylic acid esters are preferably blended in order to improve the wettability between the photocatalyst coating composition and the film.
[0018]
Of the volatile organic solvents that soften the surface layer of the organopolysiloxane film, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, and the like are phases of water and the photocatalytic coating composition of the present invention. It also has an action as a compatibilizing agent for enhancing solubility. Thereby, when an organic solvent volatilizes at the time of fixation of photocatalyst fine particles, even if water condenses, it can prevent forming an immiscible part locally.
[0019]
Furthermore, the solvent (dispersion medium) of the photocatalyst coating composition of the present invention preferably contains an aromatic hydrocarbon such as toluene and xylene in order to prevent external water from mixing.
[0020]
By applying a photocatalyst coating composition containing these organic solvents on the organopolysiloxane film, a photocatalyst layer having a high photocatalyst content in the surface layer and a high degree of photocatalyst exposure was formed on the substrate. An organopolysiloxane coating film or an organopolysiloxane independent film surface layer can be formed.
[0021]
Of the solid content in the photocatalyst coating composition, the photocatalyst is preferably 80% by weight or more. For example, in the case of anatase-type titanium oxide sol, this means that the remainder obtained by removing a component having no photocatalytic function such as amorphous titanium oxide or a dispersant from the solid content is 80% by weight or more. If there are many components other than the photocatalyst in the solid content, the content of the photocatalyst in the surface layer is lowered and the degree of exposure is lowered, which may weaken the photocatalytic ability. In order to further exhibit the characteristics of the photocatalyst, the photocatalyst in the solid content is more preferably 90% by weight or more, and more preferably 95% by weight or more.
[0022]
From the above-described fixing mechanism, it is not necessary to add a binder component such as silica, silicone, or alumina to the photocatalyst coating composition of the present invention, but it is also possible to add it to the extent that it does not hinder the exposure of the photocatalyst if desired. .
[0023]
The content of the photocatalyst in the coating composition is preferably 5% by weight or less. If the photocatalyst content is too high, aggregation may occur during spraying. Moreover, the film thickness of the photocatalyst layer becomes thick, and interference fringes may appear, which may impair the aesthetic appearance. The content of the photocatalyst is more preferably 0.05% by weight or more and 2% by weight or less. In addition, as a coating method of a photocatalyst coating composition, various coating methods, such as brush coating and a roller, other than the said spray method can be selected.
[0024]
Furthermore, the surface of the photocatalyst of the photocatalyst coating composition of the present invention is preferably modified with a chelating agent. Since the photocatalyst becomes hydrophobic by modifying the surface of the photocatalyst with a chelating agent, the photocatalyst layer is not aggregated by moisture during formation of the photocatalyst layer, and a uniform photocatalyst layer is obtained. As a method for modifying the surface of the photocatalyst with a chelating agent, a photocatalyst modified in advance may be used, or the chelating agent may be added during preparation of the coating composition to modify the surface of the photocatalyst. The chelating agent used is preferably one having a large complex formation constant with the cationic component of the photocatalyst such as Ti, Zn, Sn, Sr, W, etc. It is necessary to dissolve in a medium, and β-diketones, β-ketoesters and the like can be suitably used. Specific examples include acetylacetone, ethyl acetoacetate, and diethyl malonate. After film formation, the chelating agent is oxidatively decomposed by the action of the photocatalyst.
[0025]
As the organopolysiloxane film for fixing the photocatalyst, a coating film or an independent film coated on a substrate is used. The hydrocarbon group directly bonded to the silicon atom of the organopolysiloxane is not only resistant to oxidation but also has a feature of small volume shrinkage even when oxidized. There are no particular restrictions on the components of the organopolysiloxane film, but from the viewpoint of adhesion to photocatalysts and oxidation resistance, the average structural unit R is the main component. _n SiO _{2-n / 2} (N = 0.8 to 1.2, R: hydrocarbon) is preferable. When n> 1.2, the content of the organic component is increased, and deterioration by the photocatalyst may be accelerated. In addition, it is difficult to form a three-dimensional network structure, and the mechanical properties of the film may be deteriorated. In the case of n <0.8, it is difficult to relieve stress in the drying stage of the film, and the film forming characteristics may be deteriorated. The hydrocarbon group R can be at least one of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a vinyl group, and a phenyl group, and they may all be the same or different. The organopolysiloxane film may contain unreacted hydroxyl groups, alkoxy groups, and curing agent components. Furthermore, filler fine particles and colloidal components that have little influence on the softening properties described above may be present. In order to keep the photocatalyst for a long time without dropping off, it is preferable that the hydrocarbon group directly connected to the silicon atom is a methyl group having the smallest weight loss after oxidation. In addition, an average structural unit is a structural unit averaged about Si1 atom of organopolysiloxane.
[0026]
The organopolysiloxane coating film, which is the coating layer of the base material, is obtained by applying a silicone oligomer solution obtained by hydrolysis and condensation polymerization of alkoxysilane to the base material and heat-treating, or by mixing a curing agent with the oligomer solution. The coated liquid can be applied to a substrate, dried, and cured. In addition, the organopolysiloxane film in the form of an independent film can be manufactured by molding by a doctor blade method or the like using a base material having low affinity with the film, and peeling after curing.
[0027]
Examples of the alkoxysilane used for the production of the silicone oligomer solution include tetraalkoxysilanes such as tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), ethyltrisilane. Trialkoxysilanes such as methoxysilane (ETMS), phenyltriethoxysilane (PhTES), vinyltriethoxysilane (VTES), n-propyltrimethoxysilane (n-PrTMS), isopropyltrimethoxysilane (iso-PrTMS), dimethyl Dialkoxysilanes such as diethoxysilane (DMDE), diphenyldimethoxysilane (DPhDM), and methylethyldimethoxysilane (MEDM), trimethylmethoxysilane (TMMS) What monoalkoxysilanes can be selected from like.
[0028]
In the production of the silicone oligomer solution, water and alkoxysilane are mixed with H. ₂ It is preferable to carry out hydrolysis and polycondensation reaction by mixing so that O / Si is 1.4 to 4.0 (molar ratio). ₂ It is more preferable to carry out hydrolysis and polycondensation reaction by mixing so that O / Si is 1.5 to 2.5 (molar ratio). H ₂ When O / Si is less than 1.4 (molar ratio), many unreacted alkoxy groups remain in the production of the silicone oligomer solution, the oligomer polymerization rate is lowered, and the mechanical properties of the film are adversely affected. There is a fear. H ₂ When O / Si exceeds 4.0 (molar ratio), the stability of the silicone oligomer solution may decrease. Moreover, when forming a coating film on a base material, it is easy to condense at the time of spraying, and there exists a possibility that it may become difficult to form a uniform coating film at the time of film-forming. H ₂ By setting O / Si to 1.4 to 4.0 (molar ratio), a part of the alkoxy group remains and brings about an effect of improving the stability of the solution containing the silicone oligomer.
[0029]
In the production of the silicone oligomer solution, a metal chelate compound or an acid can be used as a catalyst for hydrolysis. The metal chelate compound not only has a catalytic effect on the hydrolysis of the alkoxysilane, but also suppresses the precipitation of crystals when a large amount of methyltrialkoxysilane is used as a raw material. In addition to the action as a hydrolysis catalyst, the metal chelate compound also has the action of promoting deprotonation of silanol and causing the polycondensation reaction to proceed more linearly. It is long, excellent in long-term storage stability of the liquid, and is advantageous in the case of coating film formation. When an acid catalyst is added, it is preferable to use a metal chelate compound in combination. As the metal chelate compound to be used, a metal chelate compound having a β-diketone having a 1,3-dioxopropylene chain or a macrocyclic polyether as a ligand can be preferably used. Moreover, an ion with a large complex formation constant with a ligand can be suitably used as the metal ion species.
[0030]
Examples of such metal chelate compounds include tris (acetylacetonato) aluminum (III), tris (ethylacetoacetate) aluminum (III), tris (diethylmalonato) aluminum (III), and bis (acetylacetonato). ) Copper (II), Tetrakis (acetylacetonato) zirconium (IV), Tris (acetylacetonato) chromium (III), Tris (acetylacetonato) cobalt (III), Titanium oxide (II) acetylacetonate [(CH _Three COCHCOCH _Three ) ₂ Β-diketone metal chelate such as TiO], β-diketone metal chelate of rare earth metal, 18-crown-6-potassium chelate compound salt, 12-crown-4-lithium chelate compound salt, 15-crown-5-sodium Examples thereof include macrocyclic polyether compound metal chelates such as chelate compound salts.
[0031]
The addition amount of the metal chelate compound catalyst can be selected according to the catalytic effect, but is usually preferably 0.001 to 5 mol%, and preferably 0.005 to 1 mol% with respect to the alkoxysilane. It is more preferable. If the addition amount of the metal chelate compound catalyst is too small, it is natural that the catalytic effect of hydrolysis is not sufficiently exhibited. If the amount of the metal chelate compound catalyst added is excessive, the metal chelate compound may be precipitated during film formation, which may adversely affect the properties of the film.
[0032]
As the curing agent for the organopolysiloxane film, a partial chelate compound of a metal alkoxide such as titanium, zirconium or aluminum, an organic tin compound, an amine silane coupling agent, an ammonium salt of carboxylic acid, or the like can be used.
[0033]
Various silicone coating agents of this type are commercially available. For example, when a UTC inorganic coating agent manufactured by Nippon Yamamura Glass is used, an organopolysiloxane coating film can be formed at room temperature to 200 ° C.
[0034]
Any known method can be selected as the method for applying the liquid when forming the organopolysiloxane coating film on the substrate, depending on the shape of the article to be coated, the viscosity of the silicone oligomer solution, and the like. For example, various methods such as a spray method, a dipping method, a flow method, and a roll method can be selected. Although the thickness of a coating film is arbitrary, it is preferable normally that it is 1-50 micrometers. An organopolysiloxane coating is formed on inorganic substrates such as metals, glass, ceramics, and concrete, and organic substrates such as acrylic resin, ABS resin, wood, and paper to protect the surface of the substrate. It serves as a support layer for the photocatalyst intermediate to the material. Depending on the substrate, a primer can be applied before the application of the silicone oligomer, for example, for the purpose of improving rust prevention or adhesion of the organopolysiloxane coating film.
[0035]
In the case of forming an independent film, the same silicone oligomer solution as described above is preferably concentrated, and then the surface is coated with an organic base material that is non-bonding to silanol groups contained in the organopolysiloxane film, or the organic material. Develop and dry on various substrates. Thereafter, the film is peeled off from the substrate at the stage where the strength of the film is developed to obtain an independent film. Further, it is cured by heat treatment if necessary. The heat treatment temperature is preferably up to about 200 ° C. By this method, an independent film having a thickness of several tens to several hundreds of μm can be obtained.
[0036]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[0037]
Production Example 1 (Production of photocatalytic coating agent)
10 parts by weight of ethyl acetoacetate was mixed with 50 parts by weight of an aqueous anatase sol (TKS-201 manufactured by Teika Co., Ltd.) to obtain a photocatalyst adjustment liquid. Separately, 60 parts by weight of ethyl acetate, 10 parts by weight of toluene, 20 parts by weight of ethanol and 10 parts by weight of 2-butoxyethanol were mixed, and 5 parts by weight of the photocatalyst adjustment liquid was added and mixed. As a result, a photocatalytic coating agent A-1 was obtained.
[0038]
Production Example 2 (Production of photocatalytic coating agent)
60 parts by weight of ethyl acetate, 10 parts by weight of toluene, 10 parts by weight of isopropyl alcohol and 20 parts by weight of tert-butyl alcohol were mixed. To this mixed solution, 1 part by weight of acetylacetone and 5 parts by weight of organoanater sol (TKS-251 manufactured by Teika Co., Ltd.) were added and mixed to obtain a photocatalyst coating agent A-2.
[0039]
Production Example 3 (Production of photocatalytic coating agent)
60 parts by weight of n-propyl acetate, 10 parts by weight of isopropyl alcohol, 10 parts by weight of acetone and 20 parts by weight of 2-ethoxyethanol were mixed. To this mixed solution, 1 part by weight of acetylacetone and 10 parts by weight of organoanater sol (TKS-251 manufactured by Teika Co., Ltd.) were added and mixed to obtain a photocatalyst coating agent A-3.
[0040]
Production Example 4 (Production of silicone oligomer)
In a mixture of 178 parts by weight of methyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-1890) and 45 parts by weight of ethanol, 0.1 part by weight of tris (acetylacetonato) aluminum (III) (Corporation) Dojindo Laboratories) was added. This solution was stirred at room temperature for 30 minutes to dissolve tris (acetylacetonato) aluminum (III), and then 32 parts by weight of distilled water was added with stirring for 1 hour. The solution was allowed to stand at room temperature for 2 days to obtain a transparent silicone oligomer solution B-1.
[0041]
Production Example 5 (Production of curing agent)
After adding 20 parts by weight of titanium tetra-n-butoxide to 100 parts by weight of isopropyl alcohol, 7 parts by weight of acetylacetone was reacted. After standing at room temperature for 1 day, a curing agent C-1 was obtained.
[0042]
Example 1
To 100 parts by weight of the silicone oligomer solution B-1, 0.5 part by weight of ammonium acetate as a curing accelerator was added and stirred to obtain a transparent coating solution. After standing at room temperature for 2 hours, this coating solution was sprayed onto one side of a glass substrate (thickness 2 mm) having a thickness of 40 × 70 mm to obtain an organopolysiloxane coating film. The obtained coating film was naturally exposed (20 to 30 ° C.) for 2 days, and then photocatalyst coating agent A-1 was applied onto the coating film with a brush. Furthermore, it exposed naturally for 10 days and obtained the evaluation sample of the photocatalyst layer.
[0043]
Next, the deodorizing characteristics and surface properties of the obtained samples were examined. First, two 4 L Pyrex containers were prepared, and each of the above samples was put into a container and sealed. 5 μl of acetaldehyde was injected into this with a microsyringe, and the acetaldehyde concentration in the gas phase in the container was measured with an acetaldehyde gas detector tube (manufactured by Gastec) and found to be 450 ppm. When one container was left in the dark for 24 hours and the concentration of acetaldehyde was measured, there was almost no change. On the other hand, 365nm UV (4.5mW / cm ² ) Was reduced to 20 ppm in 24 hours. Moreover, when water droplets were dropped on the photocatalyst layer forming surface of this sample, the water droplets spread and were hydrophilic. Furthermore, when the adhesiveness of the photocatalyst layer was evaluated by JIS K 5400 8.5.2 grid tape method, it was 10 points.
[0044]
Example 2
10 parts by weight of the curing agent C-1 was added to 100 parts by weight of the silicone oligomer solution B-1 and stirred to obtain a transparent coating solution. After standing at room temperature for 2 hours, this coating solution was applied to one side of a 40 × 70 mm size glass substrate (thickness 2 mm) with a brush to obtain an organopolysiloxane coating film. The obtained coating film was naturally exposed (20 to 30 ° C.) for 2 days, and then photocatalyst coating agent A-2 was applied onto the coating film by a spray method. Furthermore, it exposed naturally for 10 days and obtained the evaluation sample of the photocatalyst layer.
[0045]
Next, the deodorizing characteristics and surface properties of the obtained samples were examined. First, two 4 L Pyrex containers were prepared, and each of the above samples was put into a container and sealed. 5 μl of acetaldehyde was injected into this with a microsyringe, and the concentration of gas phase acetaldehyde in the container was measured with an acetaldehyde gas detector tube (manufactured by Gastec), which was 470 ppm. When one container was left in the dark for 24 hours and the concentration of acetaldehyde was measured, there was almost no change. Meanwhile, 365nm UV (4.5mW / cm ² In the container irradiated with), it decreased to 30 ppm in 24 hours. Moreover, when water droplets were dropped on the photocatalyst layer forming surface of this sample, the water droplets spread and were hydrophilic. Furthermore, when the adhesiveness of the photocatalyst layer was evaluated by JIS K 5400 8.5.2 grid tape method, it was 10 points.
[0046]
Example 3
To 100 parts by weight of the silicone oligomer solution B-1, 0.5 part by weight of ammonium acetate as a curing accelerator was added and stirred to obtain a transparent coating solution. After standing at room temperature for 2 hours, this coating solution was applied to one side of a 40 × 70 mm size glass substrate (thickness 2 mm) with a brush to obtain an organopolysiloxane coating film. The obtained coating film was naturally exposed (20 to 30 ° C.) for 2 days, and then the photocatalyst coating agent A-3 was applied on the coating film by a spray method. Furthermore, it exposed naturally for 10 days and obtained the evaluation sample of the photocatalyst layer.
[0047]
Next, the surface properties of the obtained samples were examined. When water droplets were dropped on the photocatalyst layer forming surface of the sample, the water droplets spread and were hydrophilic. Further, the adhesion of the photocatalyst layer was evaluated by JIS K 5400 8.5.2 cross cut tape method, and was 10 points.
[0048]
Example 4
50 parts by weight of ethanol was distilled off from 100 parts by weight of the silicone oligomer solution B-1 at 40 ° C. using a vacuum evaporator. To the obtained transparent liquid, 10 parts by weight of curing agent C-1 was added and stirred. After reacting for 15 minutes at room temperature, a film was formed on a silicone-coated polyester sheet by the doctor blade method. After drying at 60 ° C., photocatalyst coating agent A-2 was applied to the surface by a spray method. Thereafter, the film was peeled off, cured at 120 ° C., and further naturally exposed for 5 days to obtain an organopolysiloxane independent film having a photocatalyst layer on one side having a thickness of 80 μm.
[0049]
Next, the obtained independent membrane was cut into a size of 40 × 70 mm, and the deodorizing characteristics and surface properties were examined. First, two 4 L Pyrex containers were prepared, and each of the above samples was put into a container and sealed. 5 μl of acetaldehyde was injected into this with a microsyringe, and the acetaldehyde concentration in the gas phase in the container was measured with an acetaldehyde gas detector tube (manufactured by Gastec) and found to be 460 ppm. When one container was left in the dark for 24 hours and the concentration of acetaldehyde was measured, there was almost no change. On the other hand, 365nm UV (4.5mW / cm ² In the container irradiated with), it decreased to 30 ppm in 24 hours. Further, when water droplets were dropped on the photocatalyst layer forming surface of this sample, the water droplets spread and were hydrophilic. On the other hand, the surface where the photocatalyst layer was not formed was water repellent.
[0056]
【The invention's effect】
According to the present invention, a photocatalyst layer having a high photocatalyst content in the surface layer and a high degree of photocatalyst exposure is formed on the surface of the organopolysiloxane coating film or the organopolysiloxane independent film surface layer formed on the substrate. be able to.

Claims (14)

Average structural units of the main component is _{R n SiO 2-n / 2} (n = 0.8~1.2, R: hydrocarbon) A method for fixing the photocatalyst organopolysiloxane film surface is, the dispersion medium alcohols into ketones, coating contains an organic solvent selected from esters and a mixed solvent thereof, a binder that does not contain photocatalyst dispersion liquid for fixing the photocatalyst organopolysiloxane film surface to the membrane surface The method is characterized in that at least the surface layer of the film is softened, and at the same time, the photocatalyst is attached to the softened film surface, and then the film coated with the photocatalyst dispersion is dried. The dispersion medium The method of claim 1 including a Fang aromatic hydrocarbon solvent further. The method according to claim 1 or 2 , wherein the dispersion contains a chelating agent for temporarily hydrophobizing the photocatalyst. The method according to any one of claims 1 to 3 , wherein the dispersion contains 5% by weight or less of a photocatalyst. The method of claim 4 , wherein the photocatalyst is 0.05 to 2 wt%. The method of any of claims 1 to 5 wherein the organopolysiloxane film coated photocatalyst dispersion liquid is dried at room temperature. The organopolysiloxane film, sol - The method of any of claims 1 an independent film produced by gel method 6. The method according to any one of claims 1 to 6 , wherein the organopolysiloxane film is a coating film formed on a substrate surface by a sol-gel method. Average structural units of the main component is _{R n SiO 2-n / 2} (n = 0.8~1.2, R: hydrocarbon) was a coating composition for fixing the photocatalyst organopolysiloxane film is Te, alcohols, ketones, esters and a dispersion medium containing an organic solvent selected from a mixed solvent thereof, comprises a photocatalyst dispersed in the dispersion medium, said composition characterized by containing no Ba Indah . The dispersion medium composition according to claim 9 which contains Kaoru aromatic hydrocarbon solvent further. The composition according to claim 9 or 10, further comprising a chelating agent for temporarily hydrophobizing the photocatalyst. The composition according to any one of claims 9 to 11 , wherein the content of the photocatalyst is 5% by weight or less. The composition according to claim 12 , wherein the content of the photocatalyst is 0.05 to 2% by weight. A step of applying a room temperature curable organopolysiloxane oligomer solution to the substrate surface;
Allowing air drying of the oligomer solution coating film and condensation polymerization of the oligomer in the oligomer solution to organopolysiloxane;
A step of applying the photocatalyst coating composition according to any one of claims 9 to 13 after the touch-drying on the coating film;
Allowing air drying of the photocatalyst coating composition coating and complete curing of the organopolysiloxane coating;
A method for forming a coating film for photochemical reaction on the surface of a base material, comprising: