JP2007313705A - Laminated film and laminated adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film which has a photocatalyst layer and in which the surface of the photocatalyst layer is excellent in scratch resistance. <P>SOLUTION: In the laminated film, a photocatalyst layer containing fine oxide semiconductor particles having photocatalytic activity and an acrylic copolymer having methyl methacrylate-derived structural units and butyl methacrylate-derived structural units is formed on one side of a synthetic resin film. The arithmetic mean roughness Ra of the surface of the photocatalyst layer is 0.3 μm or below, and the ten-point mean roughness Rz is 1.0 μm or below. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated film having photocatalytic activity, and more particularly to a laminated film having excellent scratch resistance such as scratch resistance on the surface having a photocatalytic activity (photocatalytic layer).

A material having photocatalytic activity (hereinafter, sometimes simply referred to as a photocatalyst) is excited to generate electrons in the conduction band and holes in the valence band when irradiated with light having energy higher than the band gap. . The generated electrons reduce surface oxygen to generate superoxide anions (• O ₂ ⁻ ), and holes oxidize surface hydroxyl groups to generate hydroxyl radicals (• OH). It is known that active oxygen species exert a strong oxidative decomposition function and decompose organic substances adhering to the surface of the photocatalyst with high efficiency. By applying such photocatalytic functions, for example, deodorization, antifouling, antibacterial, sterilization, and decomposition / removal of various substances that cause environmental pollution in wastewater and waste gas are being studied. Yes.

Further, as another function of the photocatalyst, when the photocatalyst is photoexcited, for example, as disclosed in International Patent Publication No. 96/29375, the photocatalyst surface has a contact angle with water of 10 degrees or less. It is also known to express superhydrophilization.
Such photocatalytic technology has been attracting attention year by year, and nowadays, building outer walls, hospital inner walls, wallpaper (Patent Document 1), mirrors, window glass, sanitary ware, kitchen knives, cutting boards, and soundproof walls on highways. Have been studied by various companies in applications such as lighting in tunnels, street lights, road signs, automobile body coats, and automobile side mirrors, and some have been put into practical use.

As materials having photocatalytic activity, various compounds having semiconductor characteristics, such as metal oxides such as titanium dioxide, iron oxide, tungsten oxide, and zinc oxide, metal sulfides such as cadmium sulfide and zinc sulfide, are known. Of these, titanium dioxide, particularly anatase titanium dioxide, is useful as a practical photocatalyst. This titanium dioxide exhibits excellent photocatalytic activity by absorbing light of a specific wavelength in the ultraviolet region contained in daily light such as sunlight.
Recently, materials that exhibit photocatalytic activity even under visible light have been developed.
As described above, various studies have been made to develop various functions by forming a layer containing a compound having photocatalytic activity on the outermost layer. However, the layer containing a compound having photocatalytic activity is resistant to scratches. However, there is no problem in applications where physical load is not applied. For example, in applications such as wallpaper and window glass films, there are problems such as scratches and the removal of photocatalytic fine particles. Is desired.

JP 2005-35198 A

  The object of the present invention is to provide a film having photocatalytic activity and excellent scratch resistance.

  That is, the gist of the present invention is that (1) on one side of a synthetic resin film, oxide semiconductor fine particles having photocatalytic activity, a structural unit derived from methyl methacrylate, and a structural unit derived from butyl methacrylate A laminated film having a photocatalyst layer containing an acrylic copolymer having an arithmetic average roughness Ra of 0.3 μm or less and a ten-point average roughness Rz of 1.0 μm or less. (2) The laminated film according to (1), wherein the average particle diameter of the oxide semiconductor fine particles having photocatalytic activity is 3 to 300 nm, and (3) the oxide semiconductor fine particles having a photocatalytic layer having photocatalytic activity The laminated film according to (1) or (2) containing 20 to 70% by weight and 30 to 80% by weight of an acrylic copolymer, (4) a synthetic resin film and a photocatalyst layer A laminated film according to any one of (1) to (3), wherein the organic-inorganic composite resin is composed of an organopolysiloxane and a silyl group. The laminated film according to (4), which is a polymer obtained by reacting with a vinyl-containing polymer, and (6) an acrylic copolymer is 5 to 50% by weight of methyl methacrylate, 40 to 90 of butyl methacrylate. The laminated film according to any one of (1) to (5), which is a copolymer obtained by polymerizing 0% to 40% by weight of a monomer copolymerizable therewith, and (7) a synthetic resin The laminated film according to any one of (1) to (6) and the laminated film according to any one of (8) (1) to (7), wherein the film-made film contains 50 to 100% by weight of a polyolefin resin. Adhered to the surface of the synthetic resin film It consists in the adhesive film obtained by forming a layer.

  Since the laminated film of the present invention has photocatalytic activity and is excellent in scratch resistance on the surface of the photocatalyst layer, it is very useful for various film applications such as wallpaper and display films and decorative films.

Details of the present invention will be described below.
The laminate of the present invention comprises an acrylic semiconductor fine particle having photocatalytic activity on one side of a synthetic resin film, and a structural unit derived from methyl methacrylate and a structural unit derived from butyl methacrylate as a structural unit. It has a photocatalyst layer containing a copolymer.

  Examples of the resin constituting the synthetic resin film include acrylic resins such as polymethyl methacrylate, styrene resins such as polystyrene and ABS resins, polyolefin resins such as polyethylene resins and polypropylene resins, and mixtures thereof, polyethylene Polyester resins such as terephthalate and polyethylene naphthalate, polyamide resins such as 6-nylon and 6,6-nylon, polyvinyl chloride resins, polycarbonate resins, polyphenylene sulfide resins, polyphenylene ether resins, polyimide resins, Examples thereof include cellulose resins such as cellulose acetate, fluorine resins such as polyvinylidene fluoride, fluorinated ethylene-propylene copolymer, and fluorinated ethylene-ethylene copolymer. These resins may be used alone or in combination of two or more. Furthermore, polyethylene resins include homopolymers of ethylene, copolymers of ethylene as a main component and other monomers copolymerizable with ethylene (low density polyethylene (LDPE), high pressure method low density polyethylene, wire And low density polyethylene (LLDPE), high density polyethylene (HDPE), ethylene-α-olefin copolymer (metallocene polyethylene) obtained by polymerization using a metallocene catalyst, and mixtures thereof. . Examples of the polypropylene resin include a propylene homopolymer (homopolypropylene), a propylene copolymer, a reactor type polypropylene thermoplastic elastomer, and a mixture thereof. The propylene copolymer may be a random copolymer of propylene and ethylene or other α-olefin (random polypropylene), a block copolymer (block polypropylene), a block copolymer containing a rubber component, or a graft copolymer. Examples include coalescence. The other α-olefin copolymerizable with propylene is preferably one having 4 to 12 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4 -Methyl-1-pentene, 1-decene, etc. are mentioned, The 1 type (s) or 2 or more types of mixture is used. Usually, the mixing ratio of the α-olefin is about 1 to 10% by weight with respect to propylene.

  The amount of synthetic resin in the film is preferably 50 to 100% by weight.

In addition, for the purpose of preventing film deterioration, it is preferable to add a light stabilizer such as an ultraviolet absorber or a hindered amine light stabilizer to the synthetic resin film, and if necessary, an antioxidant or a filler. , Pigments, water resistance agents, dispersants, antifoaming agents, and the like can be blended.
As UV absorbers, 2- (2′-hydroxy-3′lauryl-5′-methylphenyl) benzotriazole, methyl-3- [3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate-polyethylene glycol condensates and hydroxyphenylbenzotriazole derivatives.
Examples of hindered amine light stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 2- ( 3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), dimethyl succinate-1- (2 -Hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate and li [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5- Triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] and the like Is mentioned.

The blending amounts of the ultraviolet absorber and the hindered amine light stabilizer are preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin component of the film, even when used alone or in combination.
The method for producing the synthetic resin film is not particularly limited as long as it is appropriately selected in consideration of the physical properties of the resin from conventionally known methods such as a T-die extrusion molding method, an inflation molding method and a calender molding method.
Although the thickness of the synthetic resin film varies depending on the application, it is usually preferably 20 to 300 μm.

Furthermore, the synthetic resin film may be subjected to easy adhesion treatment on the surface of the film in advance in order to improve adhesion with other layers laminated on the film.
Examples of the easy adhesion treatment include known methods such as corona discharge treatment, plasma treatment, ozone treatment, and flame treatment.

The oxide semiconductor fine particles having photocatalytic activity in the photocatalytic layer (hereinafter referred to as “photocatalytically active fine particles”) are not particularly limited, and are conventionally known, for example, titanium dioxide, strontium titanate (SrTiO ₃ ), titanic acid. Barium (BaTi ₄ O ₉ ), sodium titanate (Na ₂ Ti ₆ O ₁₃ ), zirconium dioxide, α-Fe ₂ O ₃ , tungsten oxide, K ₄ Nb ₆ O ₁₇ , Rb ₄ Nb ₆ O ₁₇ , K ₂ Rb ₂ Nb ₆ O ₁₇ , cadmium sulfide, zinc sulfide and the like can be mentioned. These may be used alone or in combination of two or more. Among these, titanium dioxide, particularly anatase titanium dioxide, is useful as a practical photocatalytically active material. This titanium dioxide exhibits excellent photocatalytic activity by absorbing light of a specific wavelength in the ultraviolet region contained in daily light such as sunlight. The average particle diameter of the photocatalytically active fine particles is preferably from 3 to 300 nm, particularly preferably from 5 to 100 nm. If the average particle size is smaller than 3 nm, the storage stability in the case of a coating solution is deteriorated, and if it is larger than 300 nm, the scratch resistance tends to decrease, which is not preferable. In addition, an average particle diameter can be calculated | required by the laser diffraction method, for example.

Further, the photocatalytically active fine particles can be used in which the surface is treated with silica or apatite as long as the performance is not impaired. Further, photocatalytically active fine particles and silica may be used in combination.
Further, the photocatalyst layer may contain a conventionally known photocatalyst promoter together with the photocatalyst fine particles, if desired, for the purpose of promoting photocatalytic activity. Preferred examples of the photocatalyst promoter include platinum group metals such as platinum, palladium, rhodium, and ruthenium. These may be used alone or in combination of two or more. In general, the amount of the photocatalyst promoter added is preferably in the range of 1 to 20% by weight in the total weight of the photocatalytically active fine particles and the photocatalyst promoter from the viewpoint of photocatalytic activity.

The acrylic copolymer used for the photocatalyst layer has a structural unit derived from methyl methacrylate and a structural unit derived from butyl methacrylate as the structural unit, and particularly an acrylic copolymer having a main structural unit, A compound obtained by reacting 5 to 50% by weight of methyl methacrylate, 40 to 90% by weight of butyl methacrylate, and 0 to 40% by weight of a monomer copolymerizable therewith is preferable. When the methyl methacrylate is less than 5% by weight or the butyl methacrylate exceeds 90% by weight, the scratch resistance of the photocatalyst layer tends to be lowered. Moreover, when methyl methacrylate exceeds 50% by weight or butyl methacrylate is less than 40% by weight, the photocatalyst layer tends to become brittle.
As monomers that can be copolymerized with methyl methacrylate and butyl methacrylate, acrylic acid, methacrylic acid (← added because it was described in the Examples), alkyl acrylate, methyl methacrylate, and butyl methacrylate Other than methacrylic acid alkyl ester, butadiene, isoprene, styrene, α-methylstyrene, vinyl toluene, acrylonitrile, methacrylonitrile, N-cyclohexylmaleimide, N-ethylmaleimide, Nt-butylmaleimide, N-phenylmaleimide, N -Unsaturated monomers such as orthochlorophenylmaleimide, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene, allyl Methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, diallyl fumarate, functional group-containing monomer such as triallyl cyanurate. These can be used alone or in combination.

The content of the photocatalytically active fine particles and the acrylic copolymer in the photocatalyst layer is preferably 20 to 70% by weight of the photocatalytic active fine particles and 30 to 80% by weight of the acrylic copolymer resin, and the amount of the photocatalytic active fine particles is 20%. If it is less than% by weight, the photocatalytic functions such as deodorization, antibacterial action and antifouling may be insufficient, and if it exceeds 70% by weight, the scratch resistance tends to be lowered.
The average thickness of the photocatalyst layer is 0.1 to 5 μm, preferably 0.2 to 1 μm. If it is thinner than 0.1 μm, it is difficult to obtain a sufficient photocatalytic function, and the photocatalytic function is hardly improved even if it exceeds 5 μm.
Formation of the photocatalyst layer on the synthetic resin film can be achieved, for example, by mixing the composition obtained by mixing the photocatalytic active fine particles, the acrylic copolymer, and other components as necessary with a known solvent such as isopropyl alcohol, methyl ethyl ketone, and water. Disperse and adjust to a suitable concentration using the above-mentioned solvent as necessary, and apply to a synthetic resin film by a known method such as bar coating, knife coating, roll coating, die coating or gravure roll coating, What is necessary is just to carry out by heating for several seconds-several minutes normally at 50-200 degreeC using a hot air dryer etc., and drying.
The photocatalytically active fine particles can be mixed in a powder state, but it is preferable to mix them after preparing them in a slurry or sol form, and if the necessary properties and physical properties are satisfied, they are commercially available. Alternatively, a titanium dioxide slurry or sol may be used.

  The laminated film of the present invention has an arithmetic average roughness Ra specified in JIS B 601 of the surface of the photocatalyst layer of 0.3 μm or less, preferably 0.2 μm or less, and a ten-point average roughness Rz of 1.0 μm or less. Preferably it is 0.8 micrometer or less. When Ra and Rz exceed the above ranges, the scratch resistance of the photocatalyst layer tends to be remarkably lowered. Further, although there is no particular limitation, usually, the lower limit of Ra is about 0.01 μm, and the lower limit of Rz is about 0.05 μm.

Furthermore, the laminated film of the present invention is an organic-inorganic layer between the photocatalyst layer and the synthetic resin film for the purpose of improving the durability of the laminated film or improving the adhesion of the photocatalyst layer to the synthetic resin film. It is preferable to form a layer mainly composed of a composite resin (polymer). The organic-inorganic composite resin is preferably 50 to 100% by weight in the layer.
As the organic-inorganic composite resin, at least one silyl group having a silicon atom bonded to a hydroxyl group or a hydrolyzable group and an organopolysiloxane that is a hydrolyzate of organoalkoxysilane or a partial condensate thereof is contained in the polymer. Examples thereof include a hybrid polymer obtained by reacting with a silyl group-containing vinyl polymer.

  Specific examples of the organoalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltriacetoxysilane, methyltriisopropoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, N-propyltrimethoxysilane, isopropyltrimethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxy Silane, vinyltriethoxysilane, trifluoropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacrylo Cypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxy A silane etc. can be mentioned. These organoalkoxysilanes can be used alone or in combination of two or more.

In addition, a method for producing an organoalkoxysilane hydrolyzate and / or an organopolysiloxane which is a partial condensate thereof has already been known, and many methods have been proposed, for example, disclosed in JP-B-52-39691. It can be implemented by a method. That is, the method comprises the steps of adding a predetermined amount of water to the organoalkoxysilane and heating it to cause hydrolysis and condensation.
The silyl group-containing vinyl polymer used in the organic-inorganic composite resin is a silyl group having a silicon atom bonded to a hydroxyl group or a hydrolyzable group at the terminal or side chain of a vinyl polymer having a carbon skeleton as the main chain. Those having at least one group in the polymer are preferred. Most of the silyl groups are represented by the general formula (1): —Si (R ₁ ) _{3-n Xn} . In general formula (1), X is a hydrolyzable group such as a hydroxyl group, an alkoxy group, an acyloxy group, an amino group, a phenoxy group, or an alkyl sulfide group, and n is a positive integer of 1 to 3. In X, the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like, the acyloxy group includes an acetyl group, a propionyl group, and the like, and the alkyl sulfide group includes a methyl sulfide, an ethyl sulfide group, and the like. Preferred examples include alkoxy groups such as a hydroxyl group, a methoxy group, an ethoxy group, and a propoxy group.

R ₁ represents a hydrogen atom; an alkyl group having 1 to 10 carbon atoms such as a methyl group, an ethyl group, a propyl group, a cyclohexyl group, an octyl group, a nonyl group, or a decyl group; a phenyl group, a tolyl group, a xylyl group, or the like An aryl group of: benzyl group, phenethyl group and aralkyl group.
Such a silyl group-containing vinyl polymer is, for example, represented by the general formula (2): R ₂ —Si (R ₃ ) _3−n X _n (wherein R ₃ , X and n are the same as in the general formula (1)). R ₂ is an organic group having a polymerizable double bond such as vinyl, 2-propenyl, 3-acryloxypropyl, 3-methacryloxypropyl, 4-vinylphenyl, 2- (4-vinyl) phenylethyl, etc. Can be produced by copolymerizing a silane compound, a vinyl compound, and a compound copolymerizable therewith by a general method in the presence of a radical generating compound. Here, the vinyl compound is not particularly limited as long as an adduct with the silane compound of the general formula (2) is obtained. For example, methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) (Meth) acrylic acid alkyl esters such as butyl acrylate, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid, itaconic acid, Unsaturated carboxylic acids such as fumaric acid and acid anhydrides such as maleic anhydride, epoxy compounds such as glycidyl (meth) acrylate, amino compounds such as dimethylaminoethyl (meth) acrylate and aminoethyl vinyl ether , (Meth) acrylamide, crotonamide, itaconic acid amide, maleic acid diamide, etc. Compound, acrylonitrile, methacrylonitrile, styrene, alpha-methyl styrene, vinyl chloride, vinyl acetate and vinyl propionate. Moreover, 1,1,1-trimethylamine methacrylimide, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine etc. are mentioned as a compound copolymerizable with these.

The proportion of the structural unit derived from the silane compound represented by the general formula (2) in the silyl group-containing vinyl polymer thus produced is usually 0.01 to 20% by weight in terms of Si element. Preferably, it is 0.1 to 10% by weight. If it is less than 0.01% by weight, the effect of improving the adhesion tends to be small. This is not preferable.
As the hybrid polymer, those obtained by reacting 30 to 70% by weight of organopolysiloxane and 70 to 30% by weight of a silyl group-containing vinyl polymer are particularly preferable, and the amount of organopolysiloxane is less than 30% by weight, or 70 If it exceeds wt%, the durability improving effect tends to be small.
In the same manner as the formation of the photocatalyst layer, the organic-inorganic composite resin is formed by dissolving or dispersing the organic-inorganic composite resin in a known organic solvent, applying it by a known coating method, and drying. You can do it.
In the laminated film of the present invention, an adhesive layer can be provided on the surface opposite to the surface on which the photocatalyst layer of the synthetic resin film is formed, if necessary. The type of pressure-sensitive adhesive that forms this pressure-sensitive adhesive layer is not particularly limited. For example, natural rubber-based, synthetic rubber-based, acrylic-based, urethane-based, vinyl ether-based, silicone-based, amide-based and styrene-based pressure-sensitive adhesives, Various adhesives such as styrene-based elastomers, olefin-based elastomers, and acid-modified olefin resins graft-modified with ethylenically unsaturated carboxylic acids and anhydrides thereof are preferably used. Any of hot melt type and the like may be used. For the purpose of controlling the adhesive properties, the pressure-sensitive adhesive layer may include, for example, terpene resins such as α-pinene, β-pinene polymer, diterpene polymer, α-pinene / phenol copolymer, fat Suitable tackifiers such as aromatic resins, aromatic resins, aliphatic / aromatic copolymer resins, rosin resins, coumarone indene resins, (alkyl) phenol resins, xylene resins, etc. Can be blended. Furthermore, various additives required according to the use, such as softeners such as liquid polymers and paraffinic oils, fillers, pigments, antioxidants, stabilizers, ultraviolet absorbers, and the like can be blended.

Embodiments of the present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.
(1) Preparation of synthetic resin film (A) 100 parts by weight of propylene random copolymer (Grand Polymer Co., Ltd., Grand Polypro F327), hindered amine light stabilizer (Ciba Specialty Chemicals Co., Ltd., Kimasorb) 944) Using a mixture composed of 0.1 parts by weight, a polypropylene resin film having a thickness of 0.1 mm was prepared by an extruder manufactured by Mitsubishi Heavy Industries, Ltd.

(B) A polyester film (Tetron HB, thickness 50 μm) manufactured by Teijin DuPont Films Ltd. was used as a synthetic resin film.

(2) Formation of organic-inorganic composite resin layer a) Synthesis of silyl group-containing vinyl polymer In a reactor equipped with a reflux condenser and a stirrer, 70 parts by weight of methyl methacrylate, 40 parts by weight of n-butyl acrylate, γ- 20 parts by weight of methacryloxypropyltrimethoxysilane, 5 parts by weight of acrylic acid, 13 parts by weight of 2-hydroxyethyl methacrylate, 1 part by weight of 1,1,1-trimethylamine methacrylamide, 4- (meth) acryloyloxy-2,2, After adding 1 part by weight of 6,6-tetramethylpiperidine, 150 parts by weight of i-propyl alcohol, 50 parts by weight of methyl ethyl ketone and 25 parts by weight of methanol, the mixture was heated to 80 ° C. with stirring. A solution prepared by dissolving 4 parts by weight of isovaleronitrile in 10 parts by weight of xylene is dropped over 30 minutes. And then it was reacted for 5 hours at 80 ° C. to give a solid concentration of 40 wt% of the silyl group-containing vinyl-based polymer solution.
b) Preparation of coating solution for organic-inorganic composite resin layer In a reactor equipped with a reflux condenser and a stirrer, 70 parts by weight of methyltrimethoxysilane, 30 parts by weight of dimethyldimethoxysilane, and a silyl group-containing vinyl obtained in a) After adding 100 parts by weight of a polymer, 100 parts by weight of i-butyl alcohol, 75 parts by weight of ethylene glycol monobutyl ether and 10 parts by weight of di-i-propoxyethyl acetoacetate aluminum, 30 parts by weight of water was added dropwise with stirring. , Reacted at 60 ° C. for 4 hours. Subsequently, 10 parts by weight of acetylacetone was added, and then cooled to room temperature to obtain a composition having a solid content concentration of 30% by weight. After adding 100 parts by weight of i-butyl alcohol and 100 parts by weight of propylene glycol monomethyl ether acetate to 100 parts by weight of the resulting composition and mixing well, an i-propyl alcohol solution of dioctyltin dimaleate ester (solid content 15 10 wt parts) was added and stirred well to obtain a coating solution for organic-inorganic composite resin layer.
c) Formation of organic-inorganic composite resin layer The coating liquid obtained in b) was applied to one side of the synthetic resin film obtained in (1) with a gravure roll coater, and then in a hot air dryer at 80 ° C. A coating layer was formed by heating and drying for 1 minute. The coating thickness after drying was 1 μm.

(3) Formation of photocatalyst layer d) Synthesis of acrylic copolymer 125 parts by weight of water, 0.025 part by weight of potassium persulfate and 1.0 part by weight of polyoxyethylene alkylphenyl ether derivative were charged into a reaction vessel, and nitrogen was added. The temperature was raised to 70 ° C. under an air stream. To this, 27 parts by weight of methyl methacrylate, 70 parts by weight of butyl methacrylate and 4 parts by weight of methacrylic acid were added dropwise over 3 hours, followed by emulsion polymerization, and further reacted for 3 hours after the completion of the addition. A liquid (aqueous dispersion) was obtained. Aqueous ammonia was added dropwise to the reaction solution, and PH was neutralized to 7.0 to obtain an acrylic copolymer.
e) Formation of photocatalyst layer Using the acrylic copolymer obtained in d), photocatalyst, isopropyl alcohol, and the like, after mixing so as to have the composition shown in Table 1, the mixture is sufficiently stirred, and the photocatalyst-containing coating is applied. The liquid was adjusted.
The obtained coating solution is applied on the synthetic resin film obtained in (1) or on the organic-inorganic composite resin layer obtained in c) with a gravure roll coater, and then in a hot air dryer at 80 ° C. for 1 minute. A photocatalyst layer was formed by heating and drying to obtain a laminated film. The coating thickness after drying was 0.5 μm.

(4) Evaluation of laminated film f) Measurement of surface roughness of laminated film Surface roughness of photocatalyst layer of laminated film obtained in (3) (arithmetic average roughness Ra and ten-point average defined in JIS B 0601) Roughness Rz) was obtained using a scanning probe microscope (SPM-9500J3) manufactured by Shimadzu Corporation, and the results are shown in Table-2.

g) Scratch resistance The surface of the photocatalyst layer of the laminated film obtained in (3) was subjected to a test by rubbing under the following conditions using a Gakushin abrasion tester. The results are shown in Table 2.

<Test conditions> Friction: Covered with Kanakin 3
Load: 500g
Number of friction: 1000 round trips

<Evaluation criteria>
◎: No scratches are seen
○: Very small scratches are seen
Δ: Scratched
×: Significant scratches are seen

h) Evaluation of photocatalytic action A 0.1% by weight aqueous solution of methylene blue was applied to each surface of the laminated film obtained in (3) and the film not formed with a photocatalytic layer as Comparative Example 3 after drying. The coating was applied with a bar coater so that the amount was about 5 mg / m ^2, and dried with a hot air dryer. The obtained sample was placed under 1000 LX fluorescent lamp irradiation, and the color change with time (decomposition of organic dye due to photocatalytic activity and fading) was measured. The results are shown in Table-2.

  Color measurement was performed with X-Rite MA68 (manufactured by X-Rite).

(* 1) TITALEX PC-8X: manufactured by Kutani Co., Ltd. (amorphous silica mixed titanium dioxide aqueous dispersion, solid content 20% by weight)
(* 2) PHOTOHAPPCAP L-20: manufactured by Taihei Chemical Industry Co., Ltd. (photocatalytic apatite-containing aqueous dispersion, solid content 20% by weight)
(* 3) NW-1: manufactured by Nanowave Co., Ltd. (apatite-coated titanium dioxide aqueous dispersion, solid content 20% by weight)

(* 4) Measure color difference from untreated film without methylene blue coating

Claims (8)

  On one side of the synthetic resin film, there is a photocatalytic layer containing oxide semiconductor fine particles having photocatalytic activity and an acrylic copolymer having a structural unit derived from methyl methacrylate and a structural unit derived from butyl methacrylate. A laminated film having an arithmetic average roughness Ra of 0.3 μm or less and a ten-point average roughness Rz of 1.0 μm or less on the surface of the photocatalyst layer.   The laminated film according to claim 1, wherein the oxide semiconductor fine particles having photocatalytic activity have an average particle diameter of 3 to 300 nm.   The laminated film according to claim 1 or 2, wherein the photocatalyst layer contains 20 to 70% by weight of oxide semiconductor fine particles having photocatalytic activity and 30 to 80% by weight of an acrylic copolymer.   The laminated film according to any one of claims 1 to 3, further comprising a layer containing an organic-inorganic composite resin as a main component between the synthetic resin film and the photocatalyst layer.   The laminated film according to claim 4, wherein the organic-inorganic composite resin is a polymer obtained by reacting an organopolysiloxane with a silyl group-containing vinyl polymer.   An acrylic copolymer is a copolymer obtained by polymerizing 5 to 50% by weight of methyl methacrylate, 40 to 90% by weight of butyl methacrylate, and 0 to 40% by weight of monomers copolymerizable therewith. The laminated film according to any one of claims 1 to 5.   The laminated film according to any one of claims 1 to 6, wherein the synthetic resin film contains 50 to 100% by weight of a polyolefin resin.   The adhesive film formed by forming an adhesive layer in the synthetic resin film side surface of the laminated | multilayer film of any one of Claims 1-7.