Surface-modified resin sheet and method for manufacturing surface-modified resin sheet

Abstract

Provided is a surface-modified resin sheet that exhibits excellent adhesion to printed ink. [Solution] The surface-modified resin sheet of the present invention is a resin sheet selected from the group consisting of an acrylic resin laminate sheet, a polycarbonate resin sheet, and a polystyrene resin sheet, on at least one side of which the surface energy is 37 mN / m or more and 50 mN / m or less.

Description

[Technical Field]

[0001] The present invention relates to a surface-modified resin sheet and a method for producing a surface-modified resin sheet. [Background technology]

[0002] In recent years, highly designed products have been provided in which images, text, etc. are printed on resin plates, such as acrylic key chains and acrylic figures. As a resin plate used in such products, for example, Patent Document 1 describes a multilayer sheet having a structure in which a coating layer is laminated on at least one surface of a base layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-151108 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] Although conventional resin plates ensure a certain degree of ink adhesion, highly decorative products such as acrylic key chains and acrylic figures require high ink adhesion that is resistant to peeling even when rubbed or subjected to impact.

[0005] An object of the present invention is to provide a surface-modified resin sheet that has excellent adhesion to printed ink. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the present inventors have found a solution comprising the following configuration, and have completed the present invention. (1) The surface-modified resin sheet according to the present invention is a resin sheet selected from the group consisting of an acrylic resin laminate sheet, a polycarbonate resin sheet, and a polystyrene resin sheet, and at least one surface of the resin sheet has a surface energy of 37 mN / m or more and 50 mN / m or less. (2) The acrylic resin laminate sheet is a surface-modified resin sheet according to (1) above, having a structure in which a coating layer containing a styrene polymer is laminated on at least one surface of an acrylic resin sheet. (3) The surface-modified resin sheet according to (2) above, wherein the styrene-based polymer is a polymer containing 30% by mass or more of a styrene-based monomer. (4) The styrene-based polymer is a styrene-based copolymer containing a styrene-based monomer unit and at least one monomer unit selected from the group consisting of an acrylic acid ester, a methacrylic acid ester, acrylonitrile, and maleic anhydride. Surface-modified resin sheet according to (2) or (3). (5) The surface-modified resin sheet according to any one of (2) to (4) above, wherein the acrylic resin laminate sheet has a structure in which coating layers are laminated on both sides of a polymethyl methacrylate sheet. (6) A method for producing a surface-modified resin sheet according to any one of (1) to (5) above, wherein the surface-modified resin sheet is irradiated with ultraviolet light at an integrated dose of 100 mJ / cm on at least one surface of a resin sheet selected from the group consisting of an acrylic resin laminate sheet, a polycarbonate resin sheet, and a polystyrene resin sheet. 2 More than 15000mJ / cm 2 A method for producing a surface-modified resin sheet, comprising the step of irradiating so as to achieve the following: (7) The method for producing the acrylic resin laminate sheet according to (6) above, wherein the acrylic resin laminate sheet has a structure in which a coating layer containing a styrene polymer is laminated on at least one surface of an acrylic resin sheet. (8) The method according to (7) above, wherein the styrene polymer is a polymer containing 30% by mass or more of a styrene monomer. (9) The method for producing a styrene-based polymer according to (7) or (8) above, wherein the styrene-based polymer is a styrene-based copolymer containing a styrene-based monomer unit and at least one monomer unit selected from the group consisting of an acrylic acid ester, a methacrylic acid ester, acrylonitrile, and maleic anhydride. (10) The method according to any one of (7) to (9) above, wherein the acrylic resin laminate sheet has a structure in which coating layers are laminated on both sides of a polymethyl methacrylate sheet. [Effects of the Invention]

[0007] The surface-modified resin sheet according to the present invention has excellent adhesion to printed ink. Furthermore, according to the method for producing a surface-modified resin sheet according to the present invention, a surface-modified resin sheet having excellent adhesion to printed ink can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0008] The surface-modified resin sheet according to one embodiment of the present invention has a surface energy of 37 mN / m or more and 50 mN / m or less on at least one side. The resin sheet used as the material for the surface-modified resin sheet is a resin sheet selected from the group consisting of an acrylic resin laminate sheet, a polycarbonate resin sheet, and a polystyrene resin sheet (hereinafter, sometimes referred to as a "specific resin sheet"). In this specification, "resin sheet" refers to both a flexible resin film and a flexible resin plate. The resin sheet may have a thickness of, for example, 0.3 mm or more and 20 mm or less, 0.5 mm or more and 10 mm or less, or 1 mm or more and 5 mm or less.

[0009] The acrylic resin laminate sheet is not limited as long as it has a structure in which a coating layer is laminated on at least one surface of an acrylic resin sheet. The acrylic resin is not limited as long as it is a polymer containing monomer units whose main component is an acrylic acid ester or a methacrylic acid ester. "Mainly containing an acrylic acid ester or a methacrylic acid ester" means that at least one of the acrylic acid ester and the methacrylic acid ester is contained in the raw material monomer at a ratio of 75% by mass or more. Specifically, the acrylic resin may be a resin composed solely of monomer units derived from at least one of an acrylic acid ester and a methacrylic acid ester, or a resin composed of monomer units derived from a monomer mixture containing a monomer copolymerizable with the acrylic acid ester or the methacrylic acid ester. The average molecular weight of the acrylic resin is not limited, and the acrylic resin may have a weight average molecular weight of, for example, 80,000 to 200,000.

[0010] Specific examples of acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-nonyl acrylate, isononyl acrylate, decyl acrylate, undecyl acrylate, n-amyl acrylate, isoamyl acrylate, and lauryl acrylate.

[0011] Specific examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, decyl methacrylate, undecyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, and lauryl methacrylate.

[0012] Examples of monomers copolymerizable with acrylic acid esters or methacrylic acid esters include aromatic vinyl monomers, unsaturated nitrile monomers, ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomers, ethylenically unsaturated carboxylic acid amide monomers, ethylenically unsaturated acid monomers, ethylenically unsaturated sulfonic acid ester monomers, ethylenically unsaturated alcohols and ester monomers thereof, ethylenically unsaturated ether monomers, ethylenically unsaturated amine monomers, ethylenically unsaturated silane monomers, halogenated vinyl monomers, and aliphatic conjugated diene monomers.

[0013] Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, o-chlorostyrene, p-chlorostyrene, p-methoxystyrene, p-aminostyrene, p-acetoxystyrene, sodium styrenesulfonate, α-vinylnaphthalene, sodium 1-vinylnaphthalene-4-sulfonate, 2-vinylfluorene, 2-vinylpyridine, and 4-vinylpyridine.

[0014] Specific examples of the unsaturated nitrile monomer include acrylonitrile, α-chloroacrylonitrile, α-methoxyacrylonitrile, methacrylonitrile, and vinylidene cyanide.

[0015] Specific examples of the ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.

[0016] Specific examples of the ethylenically unsaturated carboxylic acid amide monomer include acrylamide, methacrylamide, N-butoxymethyl acrylamide, N-butoxymethyl methacrylamide, N-butoxyethyl acrylamide, N-butoxyethyl methacrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, Nn-propoxymethyl acrylamide, Nn-propoxymethyl methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide, N,N-diethyl acrylamide, and N,N-diethyl methacrylamide.

[0017] Specific examples of the ethylenically unsaturated acid monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, fumaric anhydride, maleic acid, and maleic anhydride, and ethylenically unsaturated sulfonic acids such as vinyl sulfonic acid and isoprene sulfonic acid. The ethylenically unsaturated acid monomer may be in the form of an alkali metal salt such as a sodium salt or a potassium salt, or in the form of an ammonium salt.

[0018] Specific examples of the ethylenically unsaturated sulfonate ester monomer include alkyl vinylsulfonates and alkyl isoprene sulfonates.

[0019] Specific examples of the ethylenically unsaturated alcohol and its ester monomer include allyl alcohol, methallyl alcohol, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, allyl acetate, methallyl caproate, allyl laurate, allyl benzoate, vinyl alkylsulfonate, allyl alkylsulfonate, and vinyl arylsulfonate.

[0020] Specific examples of the ethylenically unsaturated ether monomer include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, methyl allyl ether, and ethyl allyl ether.

[0021] Specific examples of the ethylenically unsaturated amine monomer include vinyldimethylamine, vinyldiethylamine, vinyldiphenylamine, allyldimethylamine, and methallyldiethylamine.

[0022] Specific examples of the ethylenically unsaturated silane compound include vinyltriethylsilane, methylvinyldichlorosilane, dimethylallylchlorosilane, and vinyltrichlorosilane.

[0023] Specific examples of the vinyl halide monomer include vinyl chloride, vinylidene chloride, 1,2-dichloroethylene, vinyl bromide, vinylidene bromide, and 1,2-dibromoethylene.

[0024] Specific examples of the aliphatic conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-neopentyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,2-dichloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 2-bromo-1,3-butadiene, 2-cyano-1,3-butadiene, substituted straight-chain conjugated pentadiene, and straight-chain and side-chain conjugated hexadienes.

[0025] The coating layer located on at least one side of the acrylic resin sheet is not limited as long as it is a layer that can be laminated to the acrylic resin sheet. Examples of such coating layers include a coating layer containing a styrene-based polymer and a coating layer containing a polycarbonate-based polymer. As described above, the coating layer may be laminated on only one side of the acrylic resin sheet or on both sides. The coating layer may have a thickness of, for example, 1% to 20% of the total thickness of the acrylic resin laminate sheet, specifically, 0.005 mm to 1 mm. The thickness of the coating layer refers to the thickness of the coating layer located on one side, not the total thickness of the coating layers located on both sides.

[0026] Examples of styrene-based polymers include polymers containing 30% by mass or more of styrene-based monomers. Regarding styrene-based polymers, "a polymer containing 30% by mass or more of styrene-based monomers" means that the styrene-based monomers are contained in the monomers used as raw materials for the polymer at a rate of 30% by mass or more. The average molecular weight of the styrene-based polymer is not limited, and the styrene-based polymer may have a weight-average molecular weight of, for example, 50,000 or more and 500,000 or less. When a styrene-based polymer containing 30% by mass or more of styrene-based monomers is used as the coating layer included in the acrylic resin laminate sheet, the ink adhesion of the surface-modified resin sheet is further improved. The styrene-based monomer may be contained at a rate of 35% by mass or more and 90% by mass or less.

[0027] Specific examples of the styrene monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, o-chlorostyrene, p-chlorostyrene, p-methoxystyrene, p-aminostyrene, p-acetoxystyrene, and sodium styrenesulfonate.

[0028] The styrene polymer may contain a monomer other than a styrene monomer among the monomers used as raw materials for the polymer. That is, the styrene polymer may contain only a styrene monomer unit, or may contain a styrene monomer unit and a monomer unit other than a styrene monomer. Furthermore, the styrene polymer may be a syndiotactic polystyrene (SPS) polymerized by a metallocene catalyst, or a high-impact polystyrene (HIPS) to which a butadiene rubber is added during polymerization.

[0029] Examples of the monomer other than the styrene-based monomer include the above-mentioned acrylic acid esters, methacrylic acid esters, unsaturated nitrile monomers, ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomers, ethylenically unsaturated carboxylic acid amide monomers, ethylenically unsaturated acid monomers, ethylenically unsaturated sulfonic acid ester monomers, ethylenically unsaturated alcohols and ester monomers thereof, ethylenically unsaturated ether monomers, ethylenically unsaturated amine monomers, ethylenically unsaturated silane monomers, halogenated vinyl-based monomers, and aliphatic conjugated diene-based monomers.

[0030] The styrene polymer may be, for example, a styrene copolymer containing a styrene monomer unit and at least one monomer unit selected from the group consisting of an acrylic acid ester, a methacrylic acid ester, acrylonitrile, and maleic anhydride. When such a styrene copolymer is used as the coating layer contained in the acrylic resin laminate sheet, the surface-modified resin sheet exhibits better ink adhesion.

[0031] Examples of polycarbonate polymers include the polycarbonate resins described later in the description of the polycarbonate resin sheet.

[0032] Specific examples of acrylic resin laminate sheets include laminate sheets in which a coating layer containing a styrene polymer or a polycarbonate polymer is laminated on one or both sides of a sheet of a polymethacrylic acid ester such as polymethyl methacrylate.

[0033] The acrylic resin laminate sheet may be formed by forming an acrylic resin sheet and then forming a coating layer on at least one surface of the acrylic resin sheet, or may be formed by integrally forming the acrylic resin sheet and the coating layer.

[0034] Specifically, the acrylic resin laminate sheet can be obtained by, for example, a coextrusion molding method, a lamination method, a thermal adhesion method, a solvent adhesion method, a polymerization adhesion method, a cast polymerization method, a surface coating method, or the like.

[0035] In the co-extrusion molding method, the acrylic resin sheet and the coating layer are melt-kneaded using separate single-screw or twin-screw extruders, and then the two are laminated together via a feed block die or multi-manifold die, after which they are cooled and solidified using a roll unit.

[0036] The lamination method is a method in which, for example, the resin of the coating layer is processed into a sheet, and an acrylic resin sheet is laminated to this in a molten state.

[0037] The thermal bonding method is a method in which, for example, the acrylic resin and the resin of the coating layer are each formed into a plate, and the resulting plate is pressed at a temperature higher than the softening points of both materials to combine them.

[0038] The solvent bonding method is a method in which, for example, the acrylic resin and the resin of the coating layer are each processed into a plate shape, and the resulting plate-shaped products are bonded together using a solvent that dissolves either or both of the resins.

[0039] The polymerization adhesion method is a method in which, for example, the acrylic resin and the resin of the coating layer are each processed into a plate shape, and the resulting plate-shaped objects are adhered using a thermally polymerizable or photopolymerizable adhesive. Examples of the adhesive include an adhesive in which a thermal polymerization initiator or a photopolymerization initiator is added to the monomer or partial polymer thereof that is the raw material of the acrylic resin and the coating layer.

[0040] The cast polymerization method is a method in which, for example, one of the acrylic resin and the resin of the coating layer is processed into a plate, the resulting plate is placed on the inner surface of a cell for cast molding, and the raw material of the other resin (monomer or component necessary for the partial polymer of the other resin) is injected into this cell and polymerized.

[0041] The surface coating method is a method in which, for example, either the acrylic resin or the resin of the coating layer is processed into a plate, and the raw material of the other resin (monomer or component necessary for the partial polymer of the other resin) is applied to the obtained plate and polymerized.

[0042] The polycarbonate resin contained in the polycarbonate resin sheet is not limited. Examples of polycarbonate resins include those obtained by reacting a dihydric phenol with a carbonylating agent using an interfacial polycondensation method or a melt transesterification method; those obtained by polymerizing a carbonate prepolymer using a solid-phase transesterification method; and those obtained by polymerizing a cyclic carbonate compound using a ring-opening polymerization method. The average molecular weight of the polycarbonate resin is not limited, and the polycarbonate resin may have a weight average molecular weight of, for example, 15,000 to 40,000.

[0043] Examples of dihydric phenols include hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)methane, bis{(4-hydroxy-3,5-dimethyl)phenyl}methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, 2,2-bis{(4-hydroxy-3,5-di 2,2-bis{(4-hydroxy-3,5-dibromo)phenyl}propane, 2,2-bis{(3-isopropyl-4-hydroxy)phenyl}propane, 2,2-bis{(4-hydroxy-3-phenyl)phenyl}propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 2,2-bis(4-hydroxyphenyl)- hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-4-isopropylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis{(4-hydroxy-3-methyl)phenyl}fluorene, α,α'-bis(4-hydroxyphenyl)-o-diisopropylbenzene, α ,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene, α,α'-bis(4-hydroxyphenyl)-p-diisopropylbenzene, 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl ester, etc. These may be used alone or in combination of two or more.

[0044] The dihydric phenol may be, for example, bisphenol A, 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene. In particular, bisphenol A may be used alone or in combination with at least one selected from the group consisting of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, and α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene.

[0045] Examples of carbonylating agents include carbonyl halides (phosgene, etc.), carbonate esters (diphenyl carbonate, etc.), haloformates (dihaloformates of dihydric phenols, etc.), etc. These may be used alone or in combination of two or more.

[0046] The polystyrene resin contained in the polystyrene resin sheet is not limited. Examples of polystyrene resins include polymers containing 50% by mass or more of a styrene monomer. Regarding polystyrene resins, "a polymer containing 50% by mass or more of a styrene monomer" means that the styrene monomer is contained in the raw material monomers of the polymer at a rate of 50% by mass or more. The average molecular weight of the styrene polymer is not limited, and the styrene polymer may have a weight average molecular weight of, for example, 50,000 or more and 500,000 or less. The term "polystyrene resin" is used to distinguish it from the term "styrene polymer," which is an example of the coating layer described above. The "styrene polymer" and the "polystyrene resin" may be resins with the same monomer composition and average molecular weight, or may be different resins.

[0047] Specific examples of the styrene monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, o-chlorostyrene, p-chlorostyrene, p-methoxystyrene, p-aminostyrene, p-acetoxystyrene, and sodium styrenesulfonate.

[0048] The polystyrene resin may contain a monomer other than a styrene monomer as a raw material for the polymer. That is, the styrene polymer may contain only a styrene monomer unit, or may contain a styrene monomer unit and a monomer unit other than a styrene monomer.

[0049] Examples of the monomer other than the styrene-based monomer include the above-mentioned acrylic acid esters, methacrylic acid esters, unsaturated nitrile monomers, ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomers, ethylenically unsaturated carboxylic acid amide monomers, ethylenically unsaturated acid monomers, ethylenically unsaturated sulfonic acid ester monomers, ethylenically unsaturated alcohols and ester monomers thereof, ethylenically unsaturated ether monomers, ethylenically unsaturated amine monomers, ethylenically unsaturated silane monomers, halogenated vinyl-based monomers, and aliphatic conjugated diene-based monomers.

[0050] As described above, at least one side of the surface-modified resin sheet according to one embodiment has a surface energy of 37 mN / m or more and 50 mN / m or less. That is, at least one side of the specific resin sheet has a surface energy of 37 mN / m or more and 50 mN / m or less. In the case of an acrylic resin laminate sheet, "at least one side" refers to the surface of the coating layer. When at least one side of the specific resin sheet has a surface energy of 37 mN / m or more and 50 mN / m or less, ink printed on the surface having a surface energy of 37 mN / m or more and 50 mN / m or less has excellent adhesion. The surface energy may be, for example, 37 mN / m or more and 45 mN / m or less.

[0051] Surface energy can be measured, for example, by applying a dyne pen (test pen) or ink (test ink) to the surface to be measured and measuring whether the ink is repelled. Dyne pens and inks are commercially available from, for example, Enercon and Arcotest.

[0052] Specifically, a dyne pen or ink corresponding to a predetermined surface energy is applied to the surface to be measured, and whether the applied state is maintained for approximately 2 to 4 seconds is measured. If the ink is repelled, the surface to be measured has a predetermined surface energy or less. For example, if a dyne pen or ink corresponding to 38 mN / m is applied and the ink is repelled after 2 to 4 seconds, the surface energy of the target surface is estimated to be 38 mN / m or less. Next, a dyne pen or ink corresponding to 37 mN / m is applied. If the ink is not repelled, the surface energy of the target surface is estimated to be 37 mN / m or more. Therefore, the surface energy of the target surface in this case is 37 mN / m or more but not more than 38 mN / m. Depending on the degree of ink repelling, it may be evaluated as approximately 37 mN / m, 37.5 mN / m, 38 mN / m, etc.

[0053] The method is not limited as long as the surface energy can be set to 37 mN / m or more and 50 mN / m or less on at least one side of a specific resin sheet. Hereinafter, one embodiment of the method for producing a surface-modified resin sheet according to the present invention will be described.

[0054] In one embodiment, a method for producing a surface-modified resin sheet is provided, in which ultraviolet light is applied to at least one surface of a resin sheet (specific resin sheet) selected from the group consisting of an acrylic resin laminate sheet, a polycarbonate resin sheet, and a polystyrene resin sheet, with an integrated light amount of 100 mJ / cm 2 2 More than 15000mJ / cm 2 When ultraviolet light is irradiated onto at least one surface of the specific resin sheet with such an integrated light amount, a surface energy of 37 mN / m or more and 50 mN / m or less can be imparted to at least one surface of the specific resin sheet. The integrated light amount is, for example, 500 mJ / cm. 2 More than 13000mJ / cm 2 may be less than 1200 mJ / cm 2 More than 11000mJ / cm 2 It may be the following:

[0055] Accumulated light intensity: 100mJ / cm 2 More than 15000mJ / cm2 The method of ultraviolet irradiation is not limited as long as ultraviolet rays can be irradiated as follows: Examples of ultraviolet irradiation methods include irradiation methods using pulsed xenon, a UV lamp, and an ozone lamp.

[0056] When irradiating with ultraviolet light, the surface (irradiation surface) of the specific resin sheet may be heated to a temperature of 20°C or higher and 100°C or lower. By heating the irradiation surface of the specific resin sheet to such a temperature, the specific resin sheet is less likely to soften or deform, and the solidified state is maintained. As a result, ultraviolet light is irradiated stably onto the specific resin sheet. Furthermore, there is no need to expose the equipment used for ultraviolet light irradiation to high temperatures, which reduces the load on such equipment. [Example]

[0057] The surface-modified resin sheet according to the present invention will be specifically described below with reference to examples and comparative examples, but the surface-modified resin sheet according to the present invention is not limited to these examples.

[0058] Example 1 A coating layer of a styrene-based polymer was formed on one side of a polymethyl methacrylate resin sheet to obtain multiple test sheets 1 (resin sheets). Test sheets 1 were obtained using an extruder equipped with a first extruder, a second extruder, a distribution block, a multi-manifold die, and a cooling unit. The first extruder was a vented single-screw extruder (manufactured by Canadavia Co., Ltd.) with a screw diameter of 120 mm. The second extruder was a vented single-screw extruder (manufactured by Canadavia Co., Ltd.) with a screw diameter of 45 mm. The distribution block was a two-type, three-layer distribution block (manufactured by Canadavia Co., Ltd.). The multi-manifold die was a two-type, three-layer distribution multi-manifold die (manufactured by Canadavia Co., Ltd.) with a resin outlet width of 1650 mm. The cooling unit consisted of three cooling rolls with a face length of 1800 mm and a diameter of 400 mm.

[0059] Test sheet 1 was obtained by extrusion molding by feeding polymethyl methacrylate into the first extruder and a styrene-based polymer into the second extruder. Test sheet 1 measured 150 mm x 150 mm and had a thickness of 3 mm. The styrene-based polymer was a copolymer obtained by copolymerizing a monomer mixture containing 60% by mass of methyl methacrylate and 40% by mass of styrene. The coating layer had a thickness of 0.05 mm. The polymethyl methacrylate used was "Sumipex MH" manufactured by Sumitomo Chemical Co., Ltd., and had a weight-average molecular weight of approximately 120,000. The styrene-based polymer used was "Toyo MS600" manufactured by Toyo Styrene Co., Ltd., and had a weight-average molecular weight of approximately 130,000. The surface energy of the coating layer side of test sheet 1 was 36 mN / m.

[0060] The surface energy was measured by applying a dyne pen corresponding to a predetermined surface energy to the surface to be measured, and measuring whether the ink was retained for 2 seconds. The ink retained for 2 seconds that corresponded to the largest surface energy was taken as the provisional surface energy. The same measurement was performed twice, and the average of the two provisional surface energies was taken as the surface energy of the surface to be measured.

[0061] The obtained test sheet 1 was irradiated with ultraviolet light to obtain a surface-modified sheet 1 with a modified surface. The ultraviolet light was irradiated onto the surface where the styrene polymer (coating layer) was located. The ultraviolet light had an integrated light amount of about 1250 mJ / cm. 2 , about 2500mJ / cm 2 , about 5000mJ / cm 2 , about 7500mJ / cm 2 and approximately 10,000 mJ / cm 2 The surface energy of the surface-modified sheet 1 at each integrated light dose is shown in Table 1.

[0062] A crosshatch test was performed on each of the obtained surface-modified sheets 1. The crosshatch test was performed according to the following procedure. First, white ink (LH-100, manufactured by Mimaki Engineering Co., Ltd.) was applied solidly to the surface-modified sheet 1 using an inkjet printer (UJF-6042MkIIe, manufactured by Mimaki Engineering Co., Ltd.) and dried. Specifically, white ink was applied solidly to the surface where the coating layer was located (ultraviolet irradiated surface) and dried. Next, a cutter guide (manufactured by TQC Screen Co., Ltd.) was used to create a crosshatch pattern of 100 squares, each 1 mm square. Next, adhesive tape having a peeling force of 4 N / 10 mm was attached to the 100 crosshatch patterns, and after removing the adhesive tape, the peeled crosshatch patterns were counted.

[0063] The number of peeled crosshatch marks was evaluated according to the following evaluation criteria, with A and B being evaluated as excellent adhesion of the printed ink. The results are shown in Table 1. Test sheet 1 (surface energy: 36 mN / m) before UV irradiation was also subjected to the crosshatch test, and was evaluated as C. <Evaluation criteria> A: No peeling at all B: When the number of peeled squares is more than 0 but less than 10 C: When the number of peeled squares is 10 or more

[0064] [Table 1]

[0065] As shown in Table 1, the surface-modified sheet 1 included in the surface-modified resin sheet of the present invention has excellent adhesion of printed ink. Similar results were obtained when irradiating with UV lamp irradiation at each of the above-mentioned integrated light intensities instead of pulsed xenon irradiation.

[0066] Furthermore, instead of irradiating with pulsed xenon, the obtained test sheet 1 was irradiated with ultraviolet light using an ozone sterilizer (OC-5606, manufactured by Iwasaki Electric Co., Ltd.), to obtain a surface-modified sheet 1 with a modified surface. The ultraviolet light was irradiated onto the surface where the coating layer was located. The ultraviolet light intensity of the ozone sterilizer is unclear, making it difficult to determine the cumulative light amount. Therefore, ultraviolet light was irradiated for 25 seconds, 50 seconds, and 150 seconds.

[0067] For the surface-modified sheet 1 obtained by ultraviolet irradiation using an ozone sterilizer, white ink was applied to the ultraviolet-irradiated surface and dried, and a crosshatch test was performed. The test results were evaluated according to the above-mentioned evaluation criteria. The results are shown in Table 2.

[0068] [Table 2]

[0069] As shown in Table 2, the surface-modified resin sheet 1 included in the surface-modified resin sheet of the present invention has excellent adhesion of printed ink. On the other hand, the surface-modified resin sheet having a surface energy of more than 50 mN / m was evaluated as C in the crosshatch test, indicating poor adhesion of printed ink.

[0070] Example 2 A plurality of test sheets 2 (resin sheets) were obtained in the same manner as in Example 1, except that a copolymer (styrene-based polymer) obtained by copolymerizing a monomer mixture containing 20% by mass of acrylonitrile and 80% by mass of styrene was used as the coating layer. The styrene-based polymer used in Example 2 was "LiTac A100PCF" manufactured by Nippon A&L Co., Ltd.

[0071] The obtained test sheet 2 was irradiated with ultraviolet light to obtain a surface-modified sheet 2. The ultraviolet light had an integrated light intensity of about 1250 mJ / cm. 2 , about 5000mJ / cm 2 and approximately 10,000 mJ / cm 2The surface energy of the surface-modified sheet 2 at each integrated light dose is shown in Table 3.

[0072] The obtained surface-modified sheet 2 was subjected to a crosshatch test in the same manner as in Example 1, and the test results were evaluated according to the above-mentioned evaluation criteria. The results are shown in Table 3.

[0073] [Table 3]

[0074] As shown in Table 3, the surface-modified sheet 2 included in the surface-modified resin sheet of the present invention has excellent adhesion of printed ink. Similar results were obtained when irradiating with a UV lamp at each of the above-mentioned integrated light intensities instead of pulsed xenon irradiation.

[0075] Furthermore, instead of irradiating the pulsed xenon, the obtained test sheet 2 was irradiated with ultraviolet light using the ozone sterilization device used in Example 1 to obtain a surface-modified sheet 2. The ultraviolet light intensity of the ozone sterilization device is unclear, making it difficult to determine the cumulative light amount. Therefore, ultraviolet light was irradiated for 25 seconds, 50 seconds, and 150 seconds.

[0076] The surface modified sheet 2 obtained by ultraviolet irradiation using the ozone sterilization device was also subjected to a crosshatch test, and the test results were evaluated according to the above evaluation criteria. The results are shown in Table 4.

[0077] [Table 4]

[0078] As shown in Table 4, it can be seen that the surface-modified sheet 2 included in the surface-modified resin sheet of the present invention has excellent adhesion of printed ink. On the other hand, the surface-modified resin sheet having a surface energy of more than 50 mN / m was evaluated as C in the crosshatch test, indicating poor adhesion of printed ink.

[0079] Example 3 A polycarbonate resin sheet was used as the test sheet 3 (resin sheet), and multiple test sheets 3 were obtained. The test sheets 3 were obtained by feeding polycarbonate resin into both the first extruder and the second extruder of the extruder used in Example 1 and extruding them. The test sheets 3 were 150 mm x 150 mm and 3 mm thick. The polycarbonate resin constituting the test sheets 3 was "Caliber 301-10" manufactured by Sumika Polycarbonate Co., Ltd., which was a polycondensate of bisphenol A and phosgene and had a weight-average molecular weight of approximately 28,000. The surface energy of the coating layer side of the test sheets 3 was 36 mN / m.

[0080] The obtained test sheet 3 was irradiated with ultraviolet light to obtain a surface-modified sheet 3. The ultraviolet light had an integrated light intensity of about 1250 mJ / cm. 2 , about 5000mJ / cm 2 and approximately 10,000 mJ / cm 2 The surface energy of the surface-modified sheet 3 at each integrated dose of light is shown in Table 5.

[0081] The obtained surface-modified sheet 3 was subjected to a crosshatch test using the same procedure as in Example 1, and the test results were evaluated according to the above-mentioned evaluation criteria. The results are shown in Table 5. The crosshatch test was also performed on test sheet 3 (surface energy: 36 mN / m) before ultraviolet irradiation, and the result was a rating of C.

[0082] [Table 5]

[0083] As shown in Table 5, the surface-modified sheet 3 included in the surface-modified resin sheet of the present invention has excellent adhesion of printed ink. Similar results were obtained when irradiating with a UV lamp at each of the above-mentioned integrated light intensities instead of pulsed xenon irradiation.

[0084] Example 4 A polystyrene resin sheet was used as test sheet 4 (resin sheet), and a plurality of test sheets 4 were obtained. Test sheet 4 was obtained by feeding polystyrene resin into both the first extruder and the second extruder of the extruder used in Example 1 and extrusion molding. Test sheet 4 was 150 mm x 150 mm and had a thickness of 2 mm. The polystyrene resin constituting test sheet 4 was "Toyo Styrol HRM24" manufactured by Toyo Styrene Co., Ltd., and had a weight average molecular weight of approximately 300,000.

[0085] The obtained test sheet 4 was irradiated with ultraviolet light to obtain a surface-modified sheet 4. The ultraviolet light had an integrated light intensity of about 2500 mJ / cm. 2 and approximately 10,000 mJ / cm 2 The surface energy of the surface-modified sheet 4 at each integrated light dose is shown in Table 6.

[0086] The obtained surface-modified sheet 4 was subjected to a crosshatch test in the same manner as in Example 1, and the test results were evaluated according to the above-mentioned evaluation criteria. The results are shown in Table 6.

[0087] [Table 6]

[0088] As shown in Table 6, it can be seen that surface-modified sheet 3, which is included in the surface-modified resin sheet of the present invention, has excellent adhesion of printed ink.

[0089] (Comparative Example 1) The polymethyl methacrylate resin sheet used in Example 1 was used as Comparative Test Sheet 1. Comparative Test Sheet 1 was obtained by extrusion molding Sumipex MH (weight average molecular weight, approximately 120,000) used in Example 1 into both the first and second extruders of the extruders used in Example 1. Comparative Test Sheet 1 measured 150 mm x 150 mm and had a thickness of 2 mm. The surface energy of Comparative Test Sheet 1 was 36 mN / m.

[0090] The obtained comparative test sheet 1 was irradiated with ultraviolet light to modify the surface, thereby obtaining a comparative surface-modified sheet 1. The ultraviolet light had an integrated light intensity of about 1250 mJ / cm 2 , about 2500mJ / cm 2 , about 5000mJ / cm 2 , about 7500mJ / cm 2 and approximately 10,000 mJ / cm 2 The surface energy of the comparative surface-modified sheet 1 at each integrated light dose is shown in Table 7.

[0091] The obtained comparative surface modified sheet 1 was subjected to a crosshatch test using the same procedure as in Example 1, and the test results were evaluated according to the above-mentioned evaluation criteria. The results are shown in Table 7. The crosshatch test was also performed on comparative surface modified sheet 1 (surface energy: 36 mN / m) before ultraviolet irradiation, and the result was a rating of C.

[0092] [Table 7]

[0093] As shown in Table 7, although comparative surface modified sheet 1 has a surface energy of 37 mN / m or more, the crosshatch test evaluation was C, indicating poor adhesion of the printed ink.

Claims

1. A surface-modified resin sheet, in which an acrylic resin laminate sheet has a structure in which a coating layer containing a styrene-based polymer is laminated on at least one side of the acrylic resin sheet, and the surface of the coating layer has a surface energy of 37 mN / m or more and 50 mN / m or less.

2. The surface-modified resin sheet according to claim 1, wherein the styrene-based polymer is a polymer containing 30% by mass or more of a styrene-based monomer.

3. The styrene-based polymer is a styrene-based copolymer containing a styrene-based monomer unit and at least one monomer unit selected from the group consisting of an acrylic acid ester, a methacrylic acid ester, acrylonitrile, and maleic anhydride. The surface-modified resin sheet according to claim 1 or 2.

4. The surface-modified resin sheet according to claim 1 or 2, wherein the acrylic resin laminate sheet has a structure in which the coating layer is laminated on both surfaces of a polymethyl methacrylate sheet.

5. The method for producing a surface-modified resin sheet according to claim 1, An acrylic resin laminated sheet has a structure in which a coating layer containing a styrene polymer is laminated on at least one surface of the acrylic resin sheet, and ultraviolet light is irradiated onto the surface of the coating layer at an integrated light dose of 100 mJ / cm. ２ More than 15000mJ / cm ２ irradiating such that: Method for manufacturing a surface-modified resin sheet.

6. The method according to claim 5 , wherein the styrene polymer contains 30% by mass or more of a styrene monomer.

7. 7. The method according to claim 5, wherein the styrene-based polymer is a styrene-based copolymer containing a styrene-based monomer unit and at least one monomer unit selected from the group consisting of an acrylic acid ester, a methacrylic acid ester, acrylonitrile, and maleic anhydride.

8. 7. The method according to claim 5, wherein the acrylic resin laminate sheet has a structure in which the coating layer is laminated on both sides of a polymethyl methacrylate sheet.

Images