JPH10180948A - Transfer sheet and method for transferring photocatalytic hydrophilic thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the surface of a transparent object for transfer highly hydrophilic by providing a second layer consisting of a photocatalyst-containing layer on a substantially transparent resin sheet-like base, and further, providing a first layer consisting of a pressure-sensitive adhesive or a thermosensitive adhesive formed on the second layer. SOLUTION: First, an adhesive layer 1 of a transfer sheet is pressed against an object for transfer 4 (in the case of a pressure-sensitive adhesive) or is pressed against the object 4 while a heat is applied (in the case of a thermosensitive adhesive). Next, the transfer sheet is fixed to the surface of the object 4. In addition, a light excited by a photocatalyst is emitted to a photocatalyst-containing layer 2, and thereby the surface of a resin sheet-like base 3 is deteriorated by the oxidative reduction action of the photocatalyst, and further, the photocatalyst-containing layer 2 is peeled off the sheet-like base 3 to fix the layer 2 to the surface of the object for transfer 4. The photocatalyst-containing layer 2 can basically contain the photocatalyst. The photocatalyst is, for example, an anatase-type titanium oxide, a rutile-type titanium oxide, tin oxide, zinc oxide or strontium titanate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer sheet which can be transferred to a required portion of the surface of a transfer object to make the surface of the portion highly hydrophilic and maintain it.
And a method for transferring a photocatalytic hydrophilic thin film from the transfer sheet to the surface of a transfer object. More specifically,
The present invention provides an anti-fogging transfer sheet capable of preventing the transfer object from fogging and water droplet formation by making the surface of a mirror, lens, glass, prism or other transparent transfer object highly hydrophilic. And a method for transferring a photocatalytic hydrophilic thin film from the anti-fogging transfer sheet to the surface of the transfer object to impart anti-fogging property to the surface of the transfer object. The present invention also provides
Highly hydrophilizing the surface of buildings, windowpanes, machinery and articles to prevent the surface from being soiled, or to provide self-cleaning (self-cleaning) or cleanliness that can be easily cleaned The present invention relates to a transfer sheet and a method for transferring a photocatalytic hydrophilic thin film from the clean transfer sheet to the surface of a transfer object to impart cleanliness to the surface of the transfer object by rainfall or water.

[0002]

2. Description of the Related Art It is often experienced that in cold weather, windshields and windows of automobiles and other vehicles, window glasses of buildings, lenses of glasses and goggles, and cover glasses of various instrument panels are fogged by condensed moisture. Is Rukoto. In addition, mirrors and eyeglass lenses in bathrooms and washrooms are often fogged by steam. Furthermore, when windshields and windowpanes of vehicles, windowpanes of buildings, lenses of glasses and goggles, shields of masks and helmets receive rain and splashes, and a large number of discrete water droplets adhere to the surface, these The surface is dark, blurred, mottled, or cloudy, again losing visibility. As used herein, the term "anti-fog" broadly refers to a technique for preventing optical hindrance due to such fogging, growth of condensed water droplets, and adhesion of water droplets. Needless to say, the above "clouding" has a profound effect on safety and efficiency of various operations. For example, if the windshield, windowpane, and back mirror of a vehicle are exposed to cold or rainy weather, become blurred, spotted, or cloudy, it becomes difficult to secure a view, and traffic safety is impaired. When the endoscope lens or dental mirror becomes cloudy, accurate diagnosis, surgery,
Obstruct treatment. If the cover glass of the instrument panel is fogged, it becomes difficult to read 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. It is to be. However, this kind of anti-fog coating is only temporary, and has the drawback that it is easily removed by washing or contact and loses its effect early.

[0004] On the other hand, in the fields of construction and paints, stains on building exterior materials, outdoor buildings and their coatings have become a problem with environmental pollution. Dust and particles suspended in the air accumulate on the roof and outer walls of buildings in fine weather. Sediment is washed away by rainwater as it rains and flows down the building's outer walls. Furthermore, in the rain, the floating dust is carried by the rain and flows down on the outer wall of the building or the surface of the outdoor building. 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 inorganic pollutants such as urban dust and clay particles. It is believed that the diversity of such contaminants complicates antifouling measures (Yoshinori Tachibana,
"Method for Accelerated Testing of Exterior Wall Finishing Material Contamination", Architectural Institute of Japan Structural Transactions, No. 404, October 1989,
p. 15-24).

According to conventional wisdom, in order to prevent dirt on the building exterior and the like, polytetrafluoroethylene (PT) is used.
Water-repellent paints such as FE) have been considered preferable, but recently it has been considered desirable to make the surface of the paint film as hydrophilic as possible for urban dust containing a large amount of hydrophobic components. (Polymer, Vol. 44, May 1995, p. 307). Therefore, a hydrophilic graft polymer
It has been proposed to paint a building in the (Chemical Industry Daily, January 30, 1995). According to reports, this coating exhibits a hydrophilicity of 30 to 40 ° in contact angle with water. However, the contact angle of inorganic dust typified by clay minerals with water is from 20 ° to 50 °, and has an affinity for a graft polymer having a contact angle of 30 to 40 ° with water. It is thought that the coating of the graft polymer cannot prevent contamination by inorganic dust because it easily adheres.

[0006]

As described above, by making the surface of the article hydrophilic, it is possible to prevent clouding and water droplet formation of the article, prevent the surface of the article from being stained, or make the surface self-supporting. Although there are proposals that can be cleaned (self-cleaning) or easily cleaned, the effect was not sufficient because the surface could not be maintained at a high degree of hydrophilicity for a long time. Therefore, in the present invention, in view of the above circumstances, a transfer sheet that can maintain the surface of a transfer object highly hydrophilic for a long period of time only by transferring it to the surface of the transfer object.
The purpose of the present invention is to provide a computer and a method of using the same.

[0007]

SUMMARY OF THE INVENTION The present invention is based on the discovery that, in a member having a surface layer containing a photocatalyst formed thereon, when the photocatalyst is photoexcited, the surface of the member is highly hydrophilized. This phenomenon is considered to proceed by the following mechanism. That is, when light having energy equal to or more than the energy gap between the upper end of the valence band and the lower end of the conduction band of the photocatalyst is irradiated on the photocatalyst, the electrons in the valence band of the photocatalyst are excited, and the conduction electrons and holes are generated. Produced, either or both of these actions, presumably polarize the surface, collecting polar components such as water and hydroxyl groups. Then, one or both of conduction electrons and holes and the above-mentioned polar component cooperate with each other to cut off a chemical bond between the surface and the contaminant chemically adsorbed on the surface, and to cause a chemical adsorbed water on the surface. Is adsorbed, and a physically adsorbed water layer is formed thereon. Further, once the surface of the member is highly hydrophilized, the hydrophilicity of the surface is maintained for a certain period even if the member is kept in a dark place.

In the present invention, it is preferable that a first layer made of a pressure-sensitive adhesive or a heat-sensitive adhesive, a second layer made of a photocatalyst-containing layer, and a substantially transparent resin sheet-like base material are contained. A transfer sheet is provided. Due to the presence of the first layer made of the pressure-sensitive adhesive, the transfer sheet can be fixed to the surface of the transfer object by a simple operation of pressing against the surface of the transfer object. Due to the presence of the first layer made of the heat-sensitive adhesive, the transfer sheet can be fixed to the surface of the transfer object by a simple operation of pressing while applying heat to the surface of the transfer object. In addition, by using a resin base material as the base material, a portion of the base material that is in close contact with the second layer made of the photocatalyst-containing layer deteriorates due to the oxidation-reduction action of the photocatalyst, and the second layer made of the photocatalyst-containing layer is sealed. -Can be peeled off from the substrate. Further, since the substrate is transparent here, light for exciting the photocatalyst passes through the substrate. By the above operation, the second layer composed of the photocatalyst-containing layer is transferred to the surface of the transfer object. Here, since the second layer contains a photocatalyst, the surface of the transfer object permanently exhibits a high degree of hydrophilicity in response to the photoexcitation of the photocatalyst. When the surface of the transparent transfer object becomes highly hydrophilic, the condensed water and / or water droplets of the attached moisture spread evenly on the surface of the layer, and become cloudy due to the moisture condensed water and / or water droplets. Or, it can be prevented from being shaded, so that the visibility is prevented from being lost. In addition, when the surface of the transfer object becomes highly hydrophilic, when the surface is exposed to rainfall, the deposits and / or
Alternatively, contaminants can be washed away by raindrops, and self-cleaning by rainfall becomes possible. Furthermore, when the surface of the transfer object comes to exhibit a high degree of hydrophilicity, the surface can be washed with a water rinse or a simple water wipe,
Water washing becomes easy.

In a preferred embodiment of the present invention, a corrosion-resistant intermediate layer is formed between the first layer and the second layer. Thereby, contact between the photocatalyst and the first layer is prevented, and deterioration of the adhesive after transfer due to photooxidation of the photocatalyst can be effectively prevented.

In a preferred embodiment of the present invention, a design film layer is formed between the first layer and the intermediate layer. As a result, it is possible to impart hydrophilicity to the object to be transferred after the transfer, and at the same time to impart design properties.

In a preferred embodiment of the present invention, the second layer further contains silica. By containing silica, the surface is likely to exhibit a high degree of hydrophilicity near 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 fact that silica can store water in its structure. Further, in the case of silica, it is preferable to use a tetraalkylsilane, an alkylsilicate, or the like as a precursor, because a hardening reaction of the silica can form a wear-resistant second layer at a relatively low temperature.

In a preferred embodiment of the present invention, the second layer further contains silicon.
When silicon is contained, at least a part of the organic group bonded to the silicon atom in the silicon is replaced by a hydroxyl group by photoexcitation of the photocatalyst, and a physical adsorption water layer is formed thereon. As a result, the surface exhibits a high degree of hydrophilicity close to the water wetting angle of 0 °, and the hydrophilicity retention when held in a dark place is improved. Further, in the case of silicone, the use of a hydrolyzable silane, a partially hydrolyzed product thereof, a low-polymer of silicone partially polymerized, or the like as a precursor makes it possible to relatively cure the silicone by a curing reaction. This is preferable because a wear-resistant second layer can be formed at a low temperature.

[0013]

Next, a specific configuration of the present invention will be described. In one embodiment of the transfer sheet of the present invention, as shown in FIG. 1, a photocatalyst-containing layer 2 is formed on a substantially transparent resin sheet-like base material 3, and further thereon. The adhesive layer 1 made of a pressure-sensitive adhesive or a heat-sensitive adhesive is formed. As shown in FIG. 2, the method of using the transfer sheet of FIG. 1 is to first press the adhesive layer 1 of the transfer sheet against the transfer object 4 (in the case of a pressure-sensitive adhesive) or to apply heat. Press while adding (in the case of heat-sensitive adhesive). As a result, the transfer sheet is fixed on the surface of the transfer target 4. Next, the photocatalyst containing layer 2 is irradiated with light that excites the photocatalyst, and the redox action of the photocatalyst causes the resin-made sheath to be exposed.
The surface of the photocatalyst-containing substrate 2 is degraded, the photocatalyst-containing layer 2 is peeled off from the sheet-like substrate 3, and the photocatalyst-containing layer 2 is fixed on the surface of the transfer object 4. Through the above steps, the photocatalyst-containing layer 2 can be easily fixed on the surface of the transfer object 4 by the dry method.

In another embodiment of the transfer sheet according to the present invention, as shown in FIG. 3, a photocatalyst containing layer 2 is formed on a substantially transparent resin sheet-like base material 3, Further, the corrosion-resistant intermediate layer 5 is formed thereon, and the adhesive layer 1 made of a pressure-sensitive adhesive or a heat-sensitive adhesive is further formed thereon. In this embodiment, since the corrosion-resistant intermediate layer 5 is formed, the adhesive layer 1 does not directly contact the photocatalyst-containing layer 2, so that the deterioration of the adhesive due to the photooxidation action of the photocatalyst can be effectively prevented.

In another embodiment of the transfer sheet according to the present invention, as shown in FIG.
The photocatalyst containing layer 2 is formed, on which the corrosion-resistant intermediate layer 5 is formed, on which the decorative film layer 6 is further formed, and on which the pressure-sensitive adhesive or the heat-sensitive adhesive is used. Adhesive layer 1 is formed.
In this embodiment, since the design film layer 6 is formed, the transfer object 4 can be given a design property in addition to the hydrophilic property corresponding to the photoexcitation of the photocatalyst. Further, since the corrosion-resistant intermediate layer 5 is formed between the photocatalyst containing layer 2 and the designable film layer 6, the designable film layer 6 does not come into direct contact with the photocatalyst containing layer 2, so that the design due to the photooxidation action of the photocatalyst. The deterioration and discoloration of the conductive film layer can be effectively prevented.

Here, in FIGS. 1 to 4, the adhesive layer 1 is made of a pressure-sensitive adhesive or a heat-sensitive adhesive. When a pressure-sensitive adhesive is used, the transfer sheet can be fixed to the surface of the transfer object 4 by pressing with a finger, a pressure tool, or the like. When a heat-sensitive adhesive is used, the transfer sheet can be fixed to the surface of the transfer target 4 by pressing the adhesive with a pressing tool or the like while heating the adhesive with an iron or a dryer.

Here, the pressure-sensitive adhesive includes polyvinyl isobutyl ether, acrylic ester resin, chlorinated olefin resin, rubber resin polyethylene-vinyl acetate copolymer, polyethylene wax, polypropylene wax, ethylene-propylene copolymer. Polymer wax, acid-modified polyethylene wax, epoxy-modified polyethylene wax, acid-modified polypropylene wax, carnauba wax, candelilla wax, sugarcane wax, beeswax, shellac wax, wool wax, montan wax, paraffin wax,
Microcrystalline wax, palmitic acid, stearic acid, hydroxystearic acid, behenic acid, oleamide, stearamide, palmitamide,
N-hydroxyethyl-hydroxystearamide,
N, N'-ethylene-bis-stearamide, N, N '
-Ethylene-bis-ricinoleamide, N, N'-ethylene-bis-hydroxystearamide, calcium stearate, aluminum stearate, magnesium stearate, calcium palmitate, palmitic hydrazide, stearic hydrazide, myristylate p -Hydroxyanilide, p-hydroxyanilide stearic acid, stearamide-formaldehyde condensate, palmitic amide-formaldehyde condensate, asphalt, Gilsonite, nitrile rubber, chloride rubber,
Fisher-Tropsch wax, polyethylene glycol, sorbitol stearate, chlorinated paraffin,
Chlorinated propylene, hardened castor oil, hardened tallow oil and the like can be used.

Here, as the heat-sensitive adhesive, styrene resin, styrene-acryl copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, polyester resin, phenol resin, epoxy resin, acrylic resin, A maleic acid resin or the like can be used.

The photocatalyst containing layer 2 basically has to contain photocatalyst particles. A photocatalyst is a device that excites electrons in the valence band when irradiated with light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction band and the valence band of the crystal. (Photoexcitation) is a substance that can generate conduction electrons and holes when it occurs.
Anatase type titanium oxide (excited by light having a wavelength of 387 nm or less), rutile type titanium oxide (excited by light having a wavelength of 413 nm or less), tin oxide (excited by light having a wavelength of 344 nm or less), zinc oxide (light having a wavelength of 387 nm or less) ), Strontium titanate (excited by light having a wavelength of 387 nm or less), bismuth trioxide, tungsten trioxide, ferric oxide and the like can be suitably used.

The photocatalyst-containing layer 2 is transferred onto the surface of the transfer object 4, and the transfer object 4 has a surface structure as shown in FIG. 5 or FIG. 6, and becomes hydrophilic in response to the photoexcitation of the photocatalyst. It comes to exhibit. As a result, even if the moisture of the atmosphere condenses and adheres, it does not grow into water droplets,
A uniform water film is formed, and clouding or overcasting due to moisture condensed water and / or water droplets is prevented. Also, when the surface is exposed to rainfall, attached deposits and / or contaminants can be washed away by raindrops, and self-cleaning by rainfall becomes possible. Furthermore, when the surface exhibits a high degree of hydrophilicity, the surface can be washed with water rinsing or simple water wiping, which facilitates water washing.

In FIG. 5, when the surface layer comprises only a photocatalyst, the photocatalyst is preferably an oxide.
By doing so, the oxide shows hydrophilicity in the state where the pollutants in the environment are not adsorbed, so that the pollutants are rejected by the photoexcitation action and the adsorbed water layer is formed, so that the oxides easily exhibit hydrophilicity. A uniform water film can be formed. In FIG. 6, M represents a metal element. Therefore, in the case of FIG. 6, the outermost surface is silica, alumina, zirconia, ceria,
It is made of a metal oxide such as yttria, tungsten oxide, tin oxide, or a partially silanolized silicon. Also in this case, since the oxide and the partially silanolized silicone show hydrophilicity in a state where the pollutants in the environment are not adsorbed, the photocatalytic titanium oxide mixed in the surface layer in addition to the above substances is used. A uniform water film can be formed by excluding the contaminants by the photo-excitation effect of and forming an adsorbed water layer.

As the light source used for photoexcitation of the photocatalyst, a light source capable of irradiating excitation light such as sunlight, general indoor lighting, incandescent lamps, metal halide lamps, mercury lamps, xenon lamps, germicidal lamps and fluorescent lamps can be used. . In order for the substrate surface to be highly hydrophilic by photoexcitation of the photocatalyst,
Illuminance of the excitation light, may if 0.001 mW / cm ² or more, preferably that it 0.01 mW / cm ² or more, 0.1
More preferably, it is at least mW / cm ² .

The thickness of the second layer is preferably set to 0.4 μm or less. Then, it is possible to prevent the surface of the transfer object 4 from becoming cloudy due to irregular reflection of light due to sticking of the transfer sheet. Further, the thickness of the second layer is set to 0.2
It is more preferable that the thickness be equal to or less than μm. Then, the transfer sheet
By sticking, the surface of the transfer target 4 can be prevented from developing color based on light interference. Also, the thinner the second layer, the better its transparency. Furthermore, if the film thickness is reduced, the abrasion resistance of the second layer when attached to the surface of the transfer object 4 is improved. Between the second layer and the third layer, a wear-resistant or corrosion-resistant protective layer or other functional film that can be further hydrophilized may be provided. Then, when adhered to the surface of the transfer target 4, the protective layer and the like are exposed and formed on the surface to protect the second layer and the like, and the protective layer and the like become hydrophilic by photoexcitation of the photocatalyst. Will be presented.

The second layer preferably has a refractive index not so high as compared with the transfer object 4. Preferably, the refractive index of the second layer is 2 or less. Then, light reflection at the interface between the transfer target 5 and the second layer and the interface between the second layer and air can be suppressed. In order to make the refractive index of the second layer 2 or less, a substance having a refractive index of 2 or less is used for the photocatalyst, or another substance having a refractive index of 2 or less is used when the photocatalyst has a refractive index of 2 or more. Add to two layers. 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). For example, calcium carbonate (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), magnesium fluoride (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) or the like may be added to the second layer.

A metal such as Ag, Cu and Zn can be added to the second layer. The second layer to which the metal is added can kill bacteria and fungi attached to the surface even in a dark place.

In the second layer, Pt, Pd, Ru, R
A platinum group metal such as h, Ir, Os can be added. The second layer to which the metal has been added can enhance the oxidation-reduction activity of the photocatalyst and improve the deodorizing and purifying action.

The substantially transparent resin sheet-like base material 4 is made of polyethylene, polyester, polyethylene terephthalate, polypropylene, ethylene-propylene copolymer, polyvinyl chloride, other plastics, paper and the like. Can be used.

The corrosion-resistant intermediate layer 5 is made of water glass, colloidal silica, polyorganosiloxane, polyvinyl fluoride, polyvinylidene fluoride, polychloroethylene trifluoride, polytetrafluoroethylene, tetrafluoroethylene-hexafluoride. Propylene copolymer, ethylene-tetrafluoroethylene copolymer, ethylene-trichloroethylene copolymer, ethylene tetrafluoride-perfluoroalkyl ether copolymer, perfluorocyclopolymer, vinyl ether -Ter-fluoro olefin copolymer, vinyl ester-fluoro olefin copolymer, fluorine rubber, acrylic silicone resin, zinc phosphate, aluminum phosphate, cement and the like can be suitably used.

The transfer sheet according to the present invention can be transferred to various transfer objects 4. The transfer object to which the transfer sheet according to the present invention can be applied is, for example, a transparent transfer object when the above-described anti-fog effect is expected, and the material of the transfer object is glass, transparent plastic, or the like. It can be suitably used for objects. Speaking of applicable transfer objects, the back mirror for vehicles, mirrors for bathrooms, mirrors for toilets,
Mirrors such as dental mirrors and road mirrors; lenses such as spectacle lenses, optical lenses, camera lenses, illumination lenses, laser light focusing lenses, semiconductor lenses, and copier lenses;
Prisms; windows of buildings and towers; windows of vehicles such as cars, railcars, aircraft, ships, submersibles, snowmobiles, gondolaes in lowways, gondolas in amusement parks, spaceships; vehicles, railcars , Motorcycles, aircraft, ships,
Windshields for vehicles such as submersibles, snowmobiles, lowway gondola, amusement park gondola, and spacecraft;
Goggles, sports goggles, shields for protective masks,
Sport mask shield, helmet shield,
It can be suitably used as a glass for a frozen food display case and a cover glass for a measuring instrument. Other transfer objects to which the transfer sheet according to the present invention can be applied include cases where the above-mentioned surface cleaning effect is expected. Cement, concrete, fiber, fabric, combinations thereof,
Those laminates can be suitably used. Speaking of applicable transfer objects, use includes building materials, building exteriors, building interiors, window frames, window glasses, structural members, vehicle exteriors and coatings, exteriors of machinery and articles, dustproof covers and coatings, traffic signs , Various display devices, advertising towers, noise barriers for roads, noise barriers for railways, bridges, exterior and coating of girder rails, tunnel interiors and coatings, insulators, solar battery covers, solar water heater collector covers,
Vinyl house, vehicle lighting cover, housing equipment, toilet bowl, bathtub, wash basin, lighting equipment, lighting cover, kitchenware,
It can be suitably used for dishes, dishwashers, dish dryers, sinks, cooking ranges, kitchen hoods, ventilation fans, and the like. The transfer object to which the transfer sheet in the present invention can be applied includes:
In addition, since it is possible to maintain a high degree of hydrophilicity for a long period of time, a material for use in an antistatic function can be expected. When antistatic effect is expected, the material may be, for example, metal, ceramics, glass, plastic, wood, stone, cement, concrete, fiber, fabric, a combination thereof,
Those laminates can be suitably used. Speaking of applicable transfer objects, applications include cathode ray tubes, magnetic recording media,
Optical recording media, magneto-optical recording media, audio
, Video tape, analog record, housing and parts and exterior and painting for household electrical appliances, housing and parts and exterior and painting for OA equipment products, building materials, building exterior, building interior, window frames, window glass, It can be suitably used for structural members, exterior and coating of vehicles, exterior of mechanical devices and articles, dustproof covers and coating, and the like.

The term "hydrophilic" refers to the property of being easily conformed when water is dropped on the surface, and generally refers to a state where the water wetting angle is less than 90 °. The term “high hydrophilicity” in the present invention refers to a property that is highly compatible when water is dropped on the surface, and more specifically, a state where the water wetting angle on a smooth surface is about 10 ° or less. In particular, PCT / JP9
As disclosed in 6/00734, the water wetting angle is preferably 10 ° or less, more preferably 5 ° or less.

Next, a method of forming a transfer sheet will be described. The transfer sheet is formed basically by applying and drying a photocatalyst-containing substance on a film-like base material 3 to form a photocatalyst-containing layer 2 and then applying and drying an adhesive to form the adhesive layer 1.
To form

The method of forming the photocatalyst-containing layer 2 on the film-like substrate 3 will be described by taking as an example a case where the second layer is composed of a photocatalyst and silica, and a case where the second layer is composed of a photocatalyst and a silicone. I do. First, the case where the second layer is composed of a photocatalyst and silica will be described with reference to an example in which the photocatalyst is an anatase type titanium oxide. In this case, basically,
A precursor of amorphous silica is used as a film forming element, and the film forming element is coated on a film substrate together with an anatase type titanium oxide particle by a flow coating method, a roll coating method, a gravure printing method, a spin coating method. After coating by a method such as a coating method, an amorphous silica is generated by a curing reaction of a coating film forming element, and anatase type titanium oxide particles are fixed using the amorphous silica as a binder. Here, a hard coat layer or the like may be formed before applying the coating film forming element together with the anatase type titanium oxide particles. By doing so, the photocatalyst containing layer 2 after transfer is protected. Here, the precursor of the amorphous silica includes tetraalkoxysilane (tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.), and an average composition formula (partial hydrolysis, dehydration condensation polymer) OR) _x SiO _y (0 <x ≦ 4, 0 ≦ y <2)
(R is an alkyl group) a tetrafunctional siloxane resin,
Film forming elements such as alkyl silicate, silanol, and silanol resin which is a dehydration-condensation polymer thereof can be suitably used. Among them, the storage stability is good, and it is easy to cause a curing reaction at room temperature.
It is most preferable to use a tetrafunctional siloxane resin consisting of R) _x SiO _y (0 <x ≦ 4, 0 ≦ y <2) (R is an alkyl group). For the same reason as above, when the corrosion-resistant intermediate layer 6 is subsequently formed, the components of the intermediate layer include the average composition formula (OR) _x SiO _y (0 <x ≦ 4, 0 ≦ y <2) (R is The use of a tetrafunctional siloxane resin composed of an alkyl group) is preferred because storage stability is good and a curing reaction can easily be caused at room temperature. Curing reaction of the coating film forming element, for example, after a hydrolysis reaction by contacting the precursor of amorphous silica with water or moisture in the air,
It is carried out by a dehydration-condensation polymerization reaction by a method such as heating, irradiation with ultraviolet light, and standing at room temperature.

Next, the case where the second layer is composed of a photocatalyst and a silicone will be described by taking as an example the case where the photocatalyst is an anatase type titanium oxide. The method in this case is to mix an uncured or partially cured silicone or a silicone precursor paint with an anatase type titanium oxide sol, and to prepare the silicone precursor as necessary. After hydrolysis, the mixture is applied to the surface of the substrate by a method such as a flow coating method, a roll coating method, a gravure printing method, or a spin coating method, and then heated or left at room temperature. By subjecting the hydrolyzate of the silicone precursor to dehydration polycondensation,
A second layer comprising anatase-type titanium oxide particles and silicone is formed. After the transfer sheet is transferred to the transfer object 5, the formed second layer is subjected to photoexcitation of the anatase-type titanium oxide by irradiation of light including ultraviolet rays, so that the silicon layer is formed.
At least a part of the organic group bonded to the silicon atom in the molecule is replaced by a hydroxyl group, and a physisorbed water layer is further formed thereon to exhibit a high degree of hydrophilicity. Here, the precursors of silicone include methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, and ethyltripropoxysilane. , Phenyltrimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane, phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyl Dibutoxysilane, diethyldipropoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylmethyldibutoxysilane,
Phenylmethyldipropoxysilane, γ-glycidoxypropyltrimethoxysilane, their hydrolysates, and mixtures thereof can be suitably used.

The method for forming the adhesive layer 1 is as follows. The adhesive is formed, if necessary, using ketone, ethanol, toluene or propanol.
After dispersing in a non-aqueous solvent such as
After coating by a method such as a rucoating method, a gravure printing method or a spin coating method, the coating is left at room temperature or dried in a drier.

[0035]

EXAMPLES The following experiment was conducted to confirm the effect given to the transfer object and the releasability between the substantially transparent resin substrate and the photocatalyst-containing layer. That is, a 10 cm square polyethylene terephthalate film is subjected to a corona discharge treatment, and then a photocatalyst coating liquid (ST-K of Ishihara Sangyo) is used.
01 and ST-K03 were mixed at a ratio of 1: 1 and then diluted with an alcohol. An alkyl silicate which was a partial hydrolyzate of an anatase type titanium oxide particle and tetraalkoxysilane was prepared at a ratio of 13: 7. (A coating solution containing the photocatalyst) was applied by a flow coating method and dried at room temperature for 10 minutes to prepare a # 1 sample on which a photocatalyst-containing surface layer was formed. The contact angle with water on the surface on which the photocatalyst-containing surface layer was formed was 5 °. Here, the contact angle with water was evaluated using a contact angle measuring device (Kyowa Interface Science, CA-X150) based on the contact angle with water 30 seconds after dropping. Also, an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB)) is provided on the surface on which the photocatalyst-containing surface layer is formed.
The surface of the sample was irradiated with ultraviolet rays for about 4 days at a UV illuminance of 0.5 mW / cm ² using a fluorescent lamp). As a result, cracks were generated between the polyethylene terephthalate film and the photocatalyst film, and peeling was observed with the rubbing of a finger. After leaving the # 1 sample in a dark place for several days, the surface of the sample was irradiated with an ultraviolet light of 0.5 mW / cm ² for about 1 day using an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp). The sample was irradiated with ultraviolet rays to obtain a # 2 sample. For comparison, a # 3 sample in which a 10 cm square polyethylene terephthalate film was left in the dark for several days was also prepared. First,
Water drops were dropped on the # 2 sample and the # 3 sample, and the state after the drop was observed and the contact angle with water was measured. As a result, when a water drop was dropped on the sample surface from the microsyringe of the # 2 sample, it was observed that the water droplet spread uniformly on the sample surface in a water film shape. The contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the case of the # 3 sample, when a water droplet was dropped on the sample surface from the microsyringe, the water droplet hardly conformed to the surface and did not reach a uniform water film state. The contact angle with water after 30 seconds was about 70 °.

Next, soap water was applied to the back side of the # 2 sample, and the sample was adhered to a glass substrate of 10 cm square. Then, BL
Using a B fluorescent lamp, the surface of the sample was irradiated with ultraviolet rays at an ultraviolet illuminance of 0.5 mW / cm ² for about 1 hour to obtain a # 4 sample.
For comparison, soap water was applied to the back side of the # 3 sample.
The sample was adhered to a 0 cm square glass substrate, and then the surface of the sample was irradiated with ultraviolet light at an ultraviolet illuminance of 0.5 mW / cm ² for about 1 hour using a BLB fluorescent lamp to obtain a # 5 sample. The # 4 and # 5 samples were blown to examine whether or not fogging occurred. As a result, fogging occurred in the # 5 sample, but no fogging occurred in the # 4 sample.

Oleic acid was applied to each surface of the # 4 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 posture. as a result,
In the # 5 sample, oleic acid remained attached to the surface, and rubbing lightly only extended the oleic acid on the sample surface. On the other hand, in the # 4 sample, oleic acid was rounded and detached from the surface when lightly rubbed. Therefore, # 4
The sample is considered to be easier to wash with water than the # 5 sample.

A powder mixture consisting of 1 part by weight of hydrophobic carbon black and 1 part by weight of hydrophilic carbon black was added to 1.0 part by weight.
A slurry suspended in water at a concentration of 5 g / liter was prepared. The # 4 sample and the # 5 sample inclined at 45 degrees were allowed to flow down for 150 minutes by flowing 150 ml of the above slurry, and then dried for 15 minutes by flowing down 150 ml of distilled water. This cycle was repeated 25 times. The color difference change before and after the test,
It measured using the color difference meter (Tokyo Denshoku). The color difference was evaluated according to Japanese Industrial Standards (JIS) H0201 using ΔE * notation. As a result, while the color difference change was as large as 20 in the # 5 sample, the color difference change was as small as 0.4 in the # 4 sample.

[0039]

According to the present invention, in a transfer sheet, a first layer made of a pressure-sensitive adhesive or a heat-sensitive adhesive, a second layer containing a photocatalyst, and a substantially transparent resin sheet. By including the base material, the photocatalyst-containing layer can be transferred to the surface of the transfer object by sticking to the surface of the transfer object and rubbing lightly. As a result, the surface of the transfer object becomes hydrophilic in response to the photoexcitation of the photocatalyst. As a result, in the case of a transparent transfer target, fogging and the like on the surface are prevented, and visibility is improved. In addition, the surface of the transfer target is self-cleaned by the rainfall. Further, the surface of the transfer object can be easily washed with water.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a transfer sheet of the present invention.

FIG. 2 is a diagram showing one method of using the transfer sheet of the present invention.

FIG. 3 is a view showing another embodiment of the transfer sheet of the present invention.

FIG. 4 is a view showing another embodiment of the transfer sheet of the present invention.

FIG. 5 is a diagram showing a surface structure of a transfer target after transfer of a transfer sheet according to the present invention.

FIG. 6 is a view showing another surface structure of a transfer target after transferring a transfer sheet according to the present invention.

Claims (19)

[Claims] (A) a first layer made of a pressure-sensitive adhesive and having a bonding property with the surface of the transfer target when pressed against the surface of the transfer target; (B) a second layer comprising a photocatalyst-containing layer and, when adhered to the surface of the transfer object, causing the surface to exhibit hydrophilicity in response to photoexcitation of the photocatalyst; and (c) a transfer object. A substantially transparent resin sheet-like base material for fixing the photocatalyst-containing layer before attaching the photocatalyst-containing layer to the surface of the transfer object. Transfer sheet to give (A) a first layer made of a pressure-sensitive adhesive, which has an adhesive property with the surface of the transfer object when pressed against the surface of the transfer object; (B) a photocatalyst-containing layer which, when adhered to the surface of a transfer object, exhibits a hydrophilic surface in response to photoexcitation of the photocatalyst, and condensed water and / or water droplets of adhering moisture A second layer for spreading evenly on the surface of the layer and preventing clouding or shading by moisture condensed water and / or water droplets; and (c) before attaching to the surface of the transfer object. A substantially transparent resin sheet-like substrate for fixing the photocatalyst-containing layer, and a transfer sheet for imparting anti-fog properties to the surface of the transfer object. G. (A) a first layer made of a pressure-sensitive adhesive, which has an adhesive property with the surface of the transfer object when pressed against the surface of the transfer object; (B) a photocatalyst-containing layer, which is attached to the surface of a transfer object, when the surface exhibits hydrophilicity in response to the photoexcitation of the photocatalyst, and when the surface is exposed to rain, And / or a second layer for allowing contaminants to be washed away by raindrops, and (c) a substantially transparent layer for fixing the photocatalyst-containing layer prior to application to the surface of the transfer object. A transfer sheet for imparting rainfall self-cleaning property to the surface of the transfer object, characterized in that the transfer sheet comprises: 4. A first layer made of a pressure-sensitive adhesive, which has an adhesive property with the surface of the transfer object when pressed against the surface of the transfer object, and (B) a layer comprising a photocatalyst-containing layer, which, when adhered to the surface of an object to be transferred, exhibits a hydrophilic property in response to the photoexcitation of the photocatalyst, so that the surface can be easily washed with water; And (c) a substantially transparent resinous sheet-like base material for fixing the photocatalyst-containing layer before sticking to the surface of the transfer object. A transfer sheet for imparting water cleanliness to the surface of a transfer object, characterized in that: 5. A first layer made of a heat-sensitive adhesive and having an adhesive property to the surface of the transfer object when heat is applied while being pressed against the surface of the transfer object. And (b) a second layer comprising a photocatalyst-containing layer and, when adhered to the surface of the transfer object, causing the surface to exhibit hydrophilicity in response to photoexcitation of the photocatalyst; and (c)
Before attaching to the surface of the transfer object, a substantially transparent resin sheet-like base material for fixing the photocatalyst-containing layer, and Transfer sheet for imparting hydrophilicity. 6. A first layer made of a heat-sensitive adhesive and having an adhesive property with the surface of the transfer object when heat is applied while being pressed against the surface of the transfer object. And (b) a photocatalyst-containing layer, which, when adhered to the surface of a transfer target, has a surface that exhibits hydrophilicity in response to photoexcitation of the photocatalyst and condensed water and / or moisture adhering thereto Water droplets spread evenly on the surface of the layer, the moisture condensed water and / or
Or (c) a substantially transparent layer for fixing the photocatalyst-containing layer before being attached to the surface of the transfer object, and A transfer sheet for imparting anti-fog properties to the surface of the transfer object, characterized by containing a resin sheet-like base material.
G. 7. A first layer made of a heat-sensitive adhesive and having an adhesive property with the surface of the transfer object when heat is applied while being pressed against the surface of the transfer object. And (b) a photocatalyst-containing layer, which is attached to the surface of a transfer object, when the surface exhibits hydrophilicity in response to photoexcitation of the photocatalyst, and adheres when the surface is exposed to rainfall. A second layer for allowing sediments and / or contaminants to be washed away by raindrops, and (c) a substantial layer for fixing the photocatalyst-containing layer before attaching to the surface of the transfer object. A transfer sheet for imparting rainfall self-cleaning property to the surface of the transfer object. 8. A first layer made of a heat-sensitive adhesive and having an adhesive property to the surface of the transfer object when heat is applied while being pressed against the surface of the transfer object. And (b) a photocatalyst-containing layer, which, when adhered to the surface of the transfer object, exhibits hydrophilicity in response to the photoexcitation of the photocatalyst, so that the surface can be easily washed with water. And (c) a sheet substrate made of substantially transparent resin for fixing the photocatalyst-containing layer before being attached to the surface of the transfer object. A transfer sheet for imparting water cleanliness to the surface of the transfer object.
G. 9. A corrosion-resistant intermediate layer for preventing contact between the photocatalyst and the first layer is formed between the first layer and the second layer. 9. The transfer sheet according to 8. 10. A design film layer is formed between the first layer and the intermediate layer.
3. The transfer sheet according to item 1. 11. The transfer sheet according to claim 1, wherein the second layer further contains amorphous silica. 12. The transfer sheet according to claim 1, wherein the second layer further contains a silicone. 13. The transfer sheet according to claim 1, wherein the second layer has a thickness of 0.4 μm or less.
G. 14. The transfer sheet according to claim 1, wherein said second layer has a thickness of 0.2 μm or less.
G. 15. The transfer sheet according to claim 1, wherein the refractive index of the second layer is 2 or less. 16. The transfer sheet according to claim 1, wherein the hydrophilicity of the photocatalyst in response to photoexcitation is 10 ° or less in terms of a contact angle with water. 17. The transfer sheet according to claim 1, wherein the hydrophilicity provided by the photocatalyst in response to photoexcitation is 5 ° or less in terms of a contact angle with water. 18. The step of preparing the transfer sheet according to claim 1, wherein the step of pressing a first layer of a portion of the transfer sheet to be transferred onto the surface of the transfer object. Irradiating light to be excited by the photocatalyst to the surface of the sheet-like substrate at a portion to be transferred, thereby separating the second layer from the sheet-like substrate by photocatalysis. A method for transferring a photocatalytic hydrophilic thin film to the surface of a transfer object to be transferred. 19. The step of preparing a transfer sheet according to claim 5, wherein the step of pressing a first layer of a portion of the transfer sheet to be transferred while applying heat to the surface of the transfer object. Irradiating light to be excited by the photocatalyst to the surface of the sheet-like substrate at a portion to be transferred, thereby separating the second layer from the sheet-like substrate by photocatalysis. A method for transferring a photocatalytic hydrophilic thin film to the surface of a transfer object to be transferred.