Hydrophilic film, manufacture thereof, and using method thereof

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a film for making the surface of a substrate highly hydrophilic and maintaining it. More specifically, the present invention relates to an antifogging film that prevents fogging and formation of water droplets on a base material by highly hydrophilicizing the surface of a mirror, lens, glass, prism or other transparent base material. The present invention also prevents the surface from becoming dirty by making the surface of buildings, windowpanes, machinery, and articles highly hydrophilic, or self-cleans or easily cleans the surface. Regarding possible films.

【0002】

[Conventional technology]

It is often experienced that the windshields and windows of automobiles and other vehicles, the windows of buildings, the lenses of eyeglasses and goggles, and the cover glass of various instrument panels become cloudy with condensed moisture in cold weather. In addition, it is often encountered that the mirrors and spectacle lenses in bathrooms and washrooms become cloudy due to steam. Furthermore, when the windshields and windowpanes of vehicles, the windowpanes of buildings, the lenses of eyeglasses and goggles, the shields of masks and helmets are exposed to rainfall and splashes, and a large number of scattered water droplets adhere to the surface, their surfaces are covered. Blurred, mottled, or cloudy, also loss of visibility. The term "anti-fog" used here broadly means a technique for preventing such optical damage due to fogging, growth of condensed water droplets, and adhesion of water droplets. Needless to say, the above-mentioned "cloudiness" has a profound effect on safety and efficiency of various operations. For example, if the windshield, window glass, or rear-view mirror of a vehicle is covered in cold weather or rainy weather, becomes blurry, has a mottled pattern, or becomes cloudy, it becomes difficult to secure visibility and traffic safety is impaired. Fogging of endoscopic lenses and dental mirrors interferes with accurate diagnosis, surgery, and treatment. If the instrument panel cover glass becomes cloudy, it will be difficult to read the data.

【0003】

As is well known, a conventionally used antifogging method is to apply an antifogging composition containing a hydrophilic compound such as polyethylene glycol or a water repellent compound such as silicone to the surface. However, this type of anti-fog film is only temporary and has the disadvantage that it is easily removed by washing with water or contact and loses its effect at an early stage.

【0004】

On the other hand, in the field of construction and paint, pollution of building exterior materials, outdoor buildings and their coating films has become a problem due to environmental pollution. Dust and particles floating in the atmosphere accumulate on the roof and outer walls of buildings in fine weather. Sediments are washed away by stormwater as it rains and flow down the outer walls of the building. Furthermore, in rainy weather, floating dust is carried by the rain and flows down the outer walls of buildings and the surface of outdoor structures. As a result, pollutants adhere to the surface along the path of rainwater. When the surface dries, striped stains appear on the surface. Dirt on building exterior materials and coatings consists of combustion products such as carbon black and pollutants of inorganic substances such as city dust and clay particles. It is believed that such diversity of pollutants complicates antifouling measures (Yoshinori Tachibana, "Test Method for Accelerating Contamination of Exterior Wall Finishing Materials", Architectural Institute of Japan Structural Papers Report, No. No. 404, October 1989, p.15-24).

【0005】

Conventional wisdom has been that water-repellent paints such as polytetrafluoroethylene (PTFE) are preferable to prevent stains on the building exterior, but these days, cities that contain a large amount of hydrophobic components. For soot and dust, it is considered desirable to make the surface of the coating film as hydrophilic as possible (Polymer, Vol. 44, May 1995, p. 307). Therefore, it has been proposed to paint the building with a hydrophilic graft polymer (Newspaper "The Chemical Daily" January 30, 1995). According to reports, this coating film exhibits hydrophilicity of 30 to 40 ° in terms of contact angle with water. However, the contact angle of inorganic dust represented by clay minerals with water is 20 to 50 °, and it has an affinity for graft polymers with a contact angle of 30 to 40 ° with water and adheres to the surface. It is considered that the coating film of this graft polymer cannot prevent stains due to inorganic dust because it is easy to do.

【0006】

PROBLEM TO BE SOLVED: To solve a problem of the invention.

As described above, by making the surface of the base material hydrophilic, it is possible to prevent the base material from becoming cloudy and forming water droplets, and to prevent the surface of buildings, windowpanes, machinery and articles from becoming dirty, or to make the surface dirty. Although there are proposals for self-cleaning or easy cleaning, the effect was not sufficient because the surface could not be maintained at a high degree of hydrophilicity for a long period of time. Therefore, in view of the above circumstances, it is an object of the present invention to provide a film capable of maintaining a high degree of hydrophilicity on the surface of a base material for a long period of time simply by attaching it to the surface of the base material, and a method for producing and using the film. To do.

【0007】

[Means for solving problems]

The present invention is based on the discovery that in a member having a surface layer containing a photocatalyst, when the photocatalyst is photoexcited, the surface of the member becomes highly hydrophilic. This phenomenon is considered to proceed by the mechanism shown below. That is, when the photocatalyst is irradiated with light having an energy equal to or greater than the energy gap between the upper end of the valence band and the lower end of the conduction band of the photocatalyst, the electrons in the valence band of the photocatalyst are excited to generate conduction electrons and holes. , Either or both of them will probably impart polarity to the surface and collect polar components such as water and hydroxyl bands. Then, by the cooperative action of either or both of conduction electrons and holes and the polar component, the chemical bond between the surface and the pollutant chemically adsorbed on the surface is broken, and the chemically adsorbed water on the surface. Is adsorbed, and a physically adsorbed aqueous layer is formed on it. Further, once the surface of the member is highly hydrophilic, the hydrophilicity of the surface is maintained for a certain period of time even if the member is held in a dark place.

【0008】

The present invention provides a hydrophilic film having a surface layer containing photocatalytic particles on the surface of a film substrate. By providing a surface layer containing a photocatalyst, the surface of the surface layer becomes permanently highly hydrophilic in response to photoexcitation of the photocatalyst. When the transparent surface becomes highly hydrophilic, the adhered wet condensed water and / or water droplets spread uniformly on the surface of the layer, and the wet condensed water and / or water droplets cause cloudiness or swelling. It will be prevented and the loss of visibility will be prevented. In addition, when the surface becomes highly hydrophilic, when the surface is exposed to rainfall, adherent deposits and / or contaminants can be washed away by raindrops, and self-cleaning by rainfall becomes possible. Further, when the surface becomes highly hydrophilic, the surface can be washed by rinsing with water or simply wiping with water, which facilitates washing with water.

【0009】

In a preferred embodiment of the present invention, the surface layer is further contained with silica. By containing silica, the surface tends to exhibit a high degree of hydrophilicity close to a water wetting angle of 0 °, and the hydrophilicity retention when held in a dark place is improved. The reason seems to be related to the ability of silica to store water in its structure.

【0010】

In a preferred embodiment of the present invention, the surface layer is further contained with silicone. Due to the inclusion of silicone, at least a part of the organic groups bonded to the silicon atoms in the silicone is replaced with hydroxyl groups by the photoexcitation of the photocatalyst, and a physically adsorbed aqueous layer is formed on the hydroxyl groups, so that the surface is surfaced. It exhibits a high degree of hydrophilicity close to a water wetting angle of 0 °, and improves hydrophilicity retention when held in a dark place.

【0011】

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a specific configuration of the present invention will be described. As shown in FIG. 1 or 2, a layer containing a photocatalyst is formed on the surface of the base material on the surface of the hydrophilic film in the present invention. By adopting such a surface structure, the surface of the hydrophilic film is highly hydrophilic in response to photoexcitation of the photocatalyst. As a result, even if the moisture in the atmosphere condenses and adheres, it does not grow in the form of water droplets, but becomes a uniform water film, and it is prevented from becoming cloudy or squeezed by the condensed water and / or water droplets. To. In addition, when the surface is exposed to rainfall, adherent deposits and / or contaminants can be washed away by raindrops, enabling self-cleaning by rainfall. Further, when the surface becomes highly hydrophilic, the surface can be washed by rinsing with water or simply wiping with water, which facilitates washing with water.

【0012】

In FIG. 1, when the surface layer is composed only of a photocatalyst, the photocatalyst is preferably an oxide. By doing so, the oxide exhibits hydrophilicity when the pollutants in the environment are not adsorbed. Therefore, the pollutants are eliminated by the photoexcitation action to form an adsorbed aqueous layer, so that the oxides tend to exhibit hydrophilicity. , A uniform water film can be formed. In FIG. 2, M represents a metallic element. Therefore, in the case of FIG. 2, the outermost surface is made of a general inorganic oxide. In this case as well, since the oxide exhibits hydrophilicity when the pollutants in the environment are not adsorbed, the pollutants are eliminated by the photoexciting action of the photocatalytic titanium oxide mixed in the surface layer in addition to the above-mentioned inorganic oxides. By forming an adsorbed aqueous layer, a uniform aqueous film can be formed.

【0013】

As the film substrate in the present invention, plastics such as polyethylene terephthalate, vinyl chloride and polyethylene, and plastics having a transparent hard coat on the plastic substrate can be preferably used. In some cases, these substrates may also have other functions such as shatterproofing, design imparting, and corrosion resistance.

【0014】

Further, the film in the present invention can be applied to various base materials. The base material to which the film in the present invention can be applied is a transparent base material when the above-mentioned antifogging effect is expected, and the material can be suitably used for a base material such as glass and transparent plastic. Applicable substrates include vehicle rearview mirrors, bathroom mirrors, washroom mirrors, dental mirrors, road mirror-like mirrors; eyeglass lenses, optical lenses, camera lenses, lighting lenses, lasers. Lenses such as light focusing lenses, semiconductor lenses, rearview mirrors; prisms; window glass for buildings and surveillance towers; automobiles, railroad vehicles, aircraft, ships, submersibles, snow vehicles, ropeway gondola, amusement park gondola , Spacecraft-like vehicle window glass; automobiles, railroad vehicles, motorcycles, aircraft, ships, submersibles, snow vehicles, ropeway gondola, amusement park gondola, spacecraft-like vehicle windshield; protective goggles , Sports goggles, protective mask shields, sports mask shields, helmet shields, frozen food display case glass; It can be suitably used as a cover glass for measuring equipment. When the above-mentioned surface cleaning effect is expected as the base material to which the film in the present invention can be applied, the material thereof is, for example, metal, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, or cloth. , A combination thereof, and a laminate thereof can be preferably used. Applicable base materials include building materials, building exteriors, building interiors, window frames, window glass, structural members, vehicle exteriors and paints, machinery and article exteriors, dustproof covers and paints, traffic signs, and more. Display devices, advertising towers, soundproof walls for roads, soundproof walls for railways, bridges, exteriors and paintings of guard rails, tunnel interiors and paintings, glass, solar cell covers, solar water heater heat collecting covers, vinyl houses, lighting for vehicles It can be suitably used for covers, housing equipment, toilets, bathtubs, wash basins, lighting fixtures, lighting covers, kitchen utensils, tableware, dishwashers, dish dryers, sinks, cooking ranges, kitchen hoods, ventilation fans, and the like. Since the film in the present invention can maintain a high degree of hydrophilicity for a long period of time, an antistatic function can also be expected. When antistatic effect is expected, for example, metal, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, cloth, a combination thereof, and a laminate thereof can be preferably used as the material. Applicable base materials include brown tubes, magnetic recording media, optical recording media, optical magnetic recording media, audio tapes, video tapes, analog records, housings and parts for household electrical products, exteriors and coatings, and OA equipment. It can be suitably used for product housings, parts, exteriors and paintings, building materials, building exteriors, building interiors, window frames, windowpanes, structural members, vehicle exteriors and paintings, mechanical equipment and article exteriors, dustproof covers and paintings, etc. ..

【0015】

A photocatalyst is an excitation (photoexcitation) of electrons in the valence band when irradiated with light (excitation light) having an energy larger than the energy gap between the conduction band and the valence band of the crystal (that is, a short wavelength). ) Is generated and can generate conduction electrons and holes. For example, anatase-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, dibismus trioxide, tungsten trioxide, ferric oxide, etc. Strontium titanate and the like can be preferably used. Here, as the light source used for photoexcitation of the photocatalyst, a light source in an environment such as sunlight or general indoor lighting may be used, or a light source capable of irradiating excitation light may be used as ancillary equipment or portable equipment. .. Further, a storage container dedicated to the plastic lens of the present invention or eyeglasses equipped with the plastic lens or goggles equipped with the plastic lens may be provided, and a light source capable of irradiating excitation light may be provided therein. As the light source used in that case, for example, an incandescent lamp, a metal halide lamp, a mercury lamp, a xenon lamp, a germicidal lamp, a fluorescent lamp and the like can be preferably used. In order for the surface of the substrate to be highly hydrophilic by photoexcitation of the photocatalyst, the illuminance of the excitation light is 0.001 mW / cm.²More than that is fine, but 0.01mW / cm²Above is preferable, 0.1mW / cm²The above is more preferable.

【0016】

The film thickness of the surface layer containing the photocatalyst is preferably 0.4 μm or less. By doing so, it is possible to prevent white turbidity due to diffused reflection of light, and the surface layer becomes substantially transparent. Further, it is more preferable that the film thickness of the surface layer containing the photocatalyst is 0.2 μm or less. By doing so, it is possible to prevent color development of the surface layer due to light interference. Further, the thinner the surface layer, the higher the transparency. Further, if the film thickness is reduced, the wear resistance of the surface layer is improved. A wear-resistant or corrosion-resistant protective layer or another functional film that can be hydrophilized may be further provided on the surface of the surface layer.

【0017】

It is preferable that the surface layer does not have a high refractive index as compared with the base material. Preferably, the refractive index of the surface layer is 2 or less. Then, the reflection of light at the interface between the base material and the surface layer and the interface between the surface layer and air can be suppressed. To reduce the refractive index of the surface layer to 2 or less, use a substance having a refractive index of 2 or less for the photocatalyst, or when the photocatalyst has a refractive index of 2 or more, use another substance having a refractive index of 2 or less for the surface layer. Add to. As a photocatalyst having a refractive index of 2 or less, tin oxide (refractive index 1.9) or the like can be used. Photocatalysts having a refractive index of 2 or more include anatase-type titanium oxide (refractive index 2.5) and rutile-type titanium oxide (refractive index 2.7). Calcium (refractive index 1.6), calcium hydroxide (refractive index 1.6), magnesium carbonate (refractive index 1.5), strontium carbonate (refractive index 1.5), dolomite (refractive index 1.7), calcium fluoride (refractive index 1.4), fluoride Magnesium (refractive index 1.4), silica (refractive index 1.5), alumina (refractive index 1.6), silica sand (refractive index 1.6), montmorillonite (refractive index 1.5), kaolin (refractive index 1.6), sericite (refractive index 1.6) , Zeolite (refractive index 1.5), tin oxide (refractive index 1.9), etc. may be added to the surface layer.

【0018】

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 and mold adhering to the surface even in a dark place.

【0019】

Platinum group metals such as Pt, Pd, Ru, Rh, Ir and Os can be added to the surface layer. The surface layer to which the metal is added can enhance the redox activity of the photocatalyst, and the deodorizing and purifying action and the like are improved.

【0020】

Hydrophilicity refers to the property of being easily adapted when water is dropped on the surface, and generally refers to a state in which the water wetting angle is less than 90 °. The high degree of hydrophilicity in the present invention refers to a property that is very familiar when water is dropped on the surface, and more specifically, a state in which the water wetting angle on a smooth surface is about 10 ° or less. In particular, as disclosed in PCT / JP96 / 00734, the antifogging property preferably has a water wetting angle of 10 ° or less, and more preferably 5 ° or less.

【0021】

Next, a method for forming the photocatalyst-containing surface layer on the film will be described by taking as an example a case where the surface layer is made of a photocatalyst and silica and a case where the surface layer is made of a photocatalyst and silicone. First, the case where the surface layer is composed of a photocatalyst and silica will be described by taking the case where the photocatalyst is anatase-type titanium oxide as an example. In this case, basically, a precursor of atypical silica is used as a coating film-forming element, and the coating film-forming element is used together with anatase-type titanium oxide particles on a film substrate by a spray coating method, a dip coating method, or a flow coating method. After coating by a method such as a spin coating method or a roll coating method, atypical silica is produced by a curing reaction of the coating film-forming element, and anatase-type titanium oxide particles are fixed to the atypical silica as a binder. Here, an intermediate layer such as a primer layer, a hard coat layer, or both may be formed on the film substrate before the coating film-forming element is applied together with the anatase-type titanium oxide particles. By doing so, the adhesion between the film base material and the surface layer can be improved. Further, here, the precursor of the atypical silica includes tetraalkoxysilane (tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.), a partial hydrolysis thereof, and an average composition formula (dehydration polycondensation polymer). A coating film-forming element such as a tetrafunctional siloxane resin composed of OR) xSiOy (0 <x4, 0y <2) (R is an alkyl group), silanol, and silanol resin which is a dehydration polycondensation polymer thereof is preferable. Available. Of these, the average composition formula (OR) xSiOy (0 <x 4, 0 y <2) (R is an alkyl group) because it has good storage stability and it is easy to cause a curing reaction at room temperature. It is most preferable to use a tetrafunctional siloxane resin composed of. For the same reason as above, when the intermediate layer is formed, the average composition formula (OR) xSiOy (0 <x 4, 0 y < 2) It is preferable to use a tetrafunctional siloxane resin composed of (R is an alkyl group) because it has good storage stability and it is easy to cause a curing reaction at room temperature. In particular, the ability to cause a curing reaction at room temperature is convenient when the base material does not have heat resistance, such as a vinyl chloride film. The curing reaction of the coating film-forming element is, for example, a hydrolysis reaction by bringing a precursor of atypical silica into contact with moisture in water or air, and then dehydration shrinkage by a method such as heating, ultraviolet irradiation, or leaving at room temperature. It is carried out by subjecting it to a polymerization reaction.

【0022】

Next, the case where the surface layer is composed of a photocatalyst and silicone will be described by taking the case where the photocatalyst is anatase-type titanium oxide as an example. In this case, the method is to mix a paint consisting of uncured or partially cured silicone or a silicone precursor with anatase-type titanium oxide sol, hydrolyze the silicone precursor if necessary, and then mix. Is applied to the surface of the base material by a method such as a spray coating method, a dip coating method, a flow coating method, a spin coating method, or a roll coating method, and the hydrolyzate of the silicone precursor is subjected to dehydration polycondensation by a method such as heating. To form a surface layer composed of anatase-type titanium oxide particles and silicone. In the formed surface layer, at least a part of the organic group bonded to the silicon atom in the silicone molecule is replaced with a hydroxyl group by photoexciting the anatase-type titanium oxide by irradiation with light including ultraviolet rays, and further on the surface layer. A physically adsorbed aqueous layer is formed to exhibit a high degree of hydrophilicity. Here, the precursors of silicone include methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, ethyltripropoxysilane, and phenyl. Trimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane, phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldibutoxy Silane, diethyldipropoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylmethyldibutoxysilane, phenylmethyldipropoxysilane, γ-glycidoxypropyltrimethoxysilane, and their hydrolyzates, mixtures thereof. Can be preferably used.

【0023】

[Example]

Example 1. A primer coating material (Shinetsu Silicone, PC-7A) was applied on a 10 cm square polyethylene terephthalate film by a flow coating method, dried at 120 ° C. for 20 minutes, and the substrate was coated with a primer resin layer. Next, a silicone-based hard coating agent (Shin-Etsu Silicone, KP-85) was applied by a flow coating method and then dried at 120 ° C. for 60 minutes to form a hard coat layer. Next, after corona discharge treatment of the hard coat layer, 16 parts by weight of a titanium oxide-containing coating composition (anathase-type titanium oxide sol (Nissan Chemical, TA-15, solid content 15% by weight)) and silica sol (Nippon Synthetic Rubber, Grasca A) Liquid, solid content 13% by weight) 9 parts by weight are mixed, diluted with ethanol, and then 3 parts by weight of trimethoxysilane (Nissan Synthetic Rubber, Grasca B liquid) is applied by the flow coating method, and then 120 A sample was obtained by heat-treating at ° C for 30 minutes and curing. After leaving this sample in the dark for several days, 0.5 mW / cm on the surface of the sample using an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp).²The # 1 sample was obtained by irradiating with ultraviolet rays for about 2 days with the ultraviolet illuminance of. For comparison, a # 2 sample in which a 10 cm square polyethylene terephthalate film was left in the dark for several days was also prepared. First, water droplets were dropped on the # 1 sample and the # 2 sample, and the state after the drops was observed and the contact angle with water was measured. Here, the contact angle with water was evaluated by using a contact angle measuring device (Kyowa Interface Science, CA-X150) and the contact angle with water 30 seconds after dropping. As a result, when water droplets were dropped on the sample surface from the microsyringe of the # 1 sample, it was observed that the water droplets uniformly spread on the sample surface in the form of a water film. In addition, the contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the # 2 sample, when water droplets were dropped from the microsyringe onto the sample surface, the water droplets hardly blended with the surface and did not reach a uniform water film shape. The contact angle with water after 30 seconds is about 70 It was. Next, the # 1 sample and the # 2 sample were blown to examine the presence or absence of fogging. As a result, the # 2 sample was cloudy, whereas the # 1 sample was not cloudy. Furthermore, the # 1 sample was then left in the dark for one week to obtain a # 3 sample. Then, water droplets were dropped on the # 3 sample in the same manner, and the state after the drops was observed and the contact angle with water was measured. As a result, when water droplets were dropped on the sample surface from the microsyringe on the # 3 sample, it was observed that the water droplets uniformly spread on the sample surface like a water film as in the # 1 sample. The contact angle with water after 30 seconds was maintained at about 2 °. Next, the presence or absence of cloudiness after blowing on the # 3 sample was observed. As a result, no cloudiness was observed.

【0024】

Next, soap water was applied to the back side of the # 3 sample and attached to a 10 cm square glass substrate. Then, 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp.²A # 4 sample was obtained by irradiating with ultraviolet rays for about 1 hour under the ultraviolet illuminance of. For comparison, soapy water was applied to the back side of the # 2 sample and attached to a 10 cm square glass substrate. Then, 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp.²A # 5 sample was obtained by irradiating with ultraviolet rays for about 1 hour under the ultraviolet illuminance of. Oleic acid was applied to the surfaces of each of the # 4 and # 5 samples, and each sample was immersed in water filled in a water tank while keeping the sample surface in a horizontal position. As a result, in the # 5 sample, the oleic acid remained attached to the surface, and even if it was lightly rubbed, the oleic acid only extended on the sample surface. On the other hand, in the # 4 sample, the oleic acid was rounded and lifted off the surface when lightly rubbed. Therefore, it is considered that the # 4 sample is easier to wash with water than the # 5 sample. A slurry was prepared by suspending a powder mixture consisting of 1 part by weight of hydrophobic carbon black and 1 part by weight of hydrophilic carbon black in water at a concentration of 1.05 g / liter. 150 ml of the above slurry was allowed to flow down to the # 4 sample and # 5 sample tilted at 45 degrees and dried for 15 minutes, and then 150 ml of distilled water was allowed to flow down and dried for 15 minutes, and this cycle was repeated 25 times. The change in color difference before and after the test was measured using a color difference meter (Tokyo Denshoku). The color difference was evaluated using the ΔE * display in accordance with Japanese Industrial Standards (JIS) H0201. As a result, the color difference change was as large as 20 in the # 5 sample, while the color difference change was as small as 0.4 in the # 4 sample.

【0025】

Example 2. (Room temperature curing method) After corona discharge treatment of a 10 cm square polyethylene terephthalate film, 30 parts by weight of ethyl silicate pentamer equivalent (corcoat, ethyl silicate 40) and 23.5 parts by weight of methyl alcohol are placed in a beaker placed in a constant temperature bath at 30 ° C. Mixed. A mixed solution of 45 parts by weight of ion-exchanged water and 1.5 parts by weight of 60% nitric acid was added thereto, and the mixture was hydrolyzed for 5 hours while being held at 30 ° C. to prepare an intermediate coating solution. This intermediate coating liquid was applied on a corona discharge-treated primer resin by a flow coating method and dried at room temperature for 10 minutes to form an intermediate layer. Next, after corona discharge treatment of the intermediate layer, a photocatalytic coating liquid (ST-K01 and ST-K03 of Ishihara Sangyo were mixed 1: 1 and then diluted with alcohol to prepare anatase-type titanium oxide particles and tetra. A coating solution containing alkyl silicate, which is a partial hydrolyzate of alkoxysilane, at a ratio of 13: 7) was applied by a flow coating method and dried at room temperature for 10 minutes to form a photocatalyst-containing surface layer. The contact angle of the forming surface with water is 5 It was. In addition, a tape peeling test (a test for evaluating whether or not the coating film peels off when the cellophane tape is applied from one end to the other end of the coating film surface and then quickly peeled off) was investigated on the formed surface. As a result, there was no change in appearance. The contact angle with water after the test was also 5 °. After leaving this sample in the dark for several days, 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp.²A # 6 sample was obtained by irradiating with ultraviolet rays for about 2 days with the ultraviolet illuminance of. For comparison, a # 2 sample similar to Example 1 in which a 10 cm square polyethylene terephthalate film was left in a dark place for several days was also prepared. First, water droplets were dropped on the # 6 sample and the # 2 sample, and the state after the drops was observed and the contact angle with water was measured. As a result, it was observed that when water droplets were dropped on the sample surface of the # 6 sample from the microsyringe, the water droplets uniformly spread on the sample surface in the form of a water film. In addition, the contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the # 2 sample, when water droplets were dropped from the microsyringe onto the sample surface, the water droplets hardly blended with the surface and did not reach a uniform water film shape. The contact angle with water after 30 seconds was about 70 °. Next, the # 6 sample and the # 2 sample were blown to examine the presence or absence of fogging. As a result, the # 2 sample was cloudy, whereas the # 6 sample was not cloudy.

【0026】

Next, soap water was applied to the back side of the # 6 sample and attached to a 10 cm square glass substrate. Then, 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp.²A # 7 sample was obtained by irradiating with ultraviolet rays for about 1 hour under the ultraviolet illuminance of. For comparison, as in Example 1, soap water was applied to the back side of the # 2 sample, attached to a 10 cm square glass substrate, and then 0.5 mW / cm on the surface of the sample using a BLB fluorescent lamp.²A # 5 sample was obtained by irradiating with ultraviolet rays for about 1 hour under the ultraviolet illuminance of. Oleic acid was applied to the surfaces of each of the # 7 sample and the # 5 sample, and each sample was immersed in water filled in a water tank while keeping the sample surface in a horizontal position. As a result, in the # 5 sample, the oleic acid remained attached to the surface, and even if it was lightly rubbed, the oleic acid only extended on the sample surface. On the other hand, in the # 7 sample, the oleic acid was rounded and lifted off the surface when lightly rubbed. Therefore, it is considered that the # 7 sample is easier to wash with water than the # 5 sample. A slurry was prepared by suspending a powder mixture consisting of 1 part by weight of hydrophobic carbon black and 1 part by weight of hydrophilic carbon black in water at a concentration of 1.05 g / liter. 150 ml of the above slurry was allowed to flow down to the # 7 sample and # 5 sample tilted at 45 degrees and dried for 15 minutes, and then 150 ml of distilled water was allowed to flow down and dried for 15 minutes, and this cycle was repeated 25 times. The change in color difference before and after the test was measured using a color difference meter (Tokyo Denshoku). The color difference was evaluated using the ΔE * display in accordance with Japanese Industrial Standards (JIS) H0201. As a result, the color difference change was as large as 20 in the # 5 sample, while the color difference change was as small as 0.4 in the # 7 sample.

【0027】

[Effect of the invention]

In the present invention, by providing the surface of the film substrate with a surface layer containing photocatalytic titanium oxide particles, the surface of the surface layer becomes hydrophilic in response to photoexcitation of the photocatalyst. As a result, fogging of the surface of the transparent base material is prevented and visibility is improved by simply attaching this film. In addition, the surface of the base material will be self-cleaned by rainfall. In addition, the surface of the substrate can be easily washed with water.

[Simple explanation of drawings]

[Figure 1]

The figure which shows the surface structure of the film which concerns on this invention.

[Figure 2]

The figure which shows the other surface structure of the film which concerns on this invention.