Fold-resistant agent and laminate

Abstract

To provide: a fold-resistant agent which, in a laminate having various functional layers arranged on a paper substrate, makes hypofunction of the functional layers difficult to occur before and after folding; and a laminate.SOLUTION: Provided is a fold-resistant agent which, in a laminate having a paper substrate layer in which a fold-resistant layer and functional layers are laminated in this order, satisfies the following conditions 1 to 3 and is used for forming the fold-resistant layer (excluding a case where the fold-resistant agent is OKS-1009 and the functional layer is a layer comprising an active energy ray-curable ink composition: (condition 1) the fold-resistant agent comprises a resin and a medium, wherein the resin includes at least one selected from the group consisting of a polyurethane resin, an acrylic resin, a polyester resin, a polyvinyl alcohol resin, a styrene-butadiene resin and a vinyl chloride resin and the content of the resin (in terms of solid content) in the fold-resistant agent is 70-100 mass%; (condition 2) the fold-resistant agent has a degree of elongation in a tensile test of 200% or more; and (condition 3) the fold-resistant layer has a degree of shape restoration of 80% or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a folding resistance agent and a laminate. More specifically, the present invention relates to a folding resistance agent and a laminate for preventing a functional layer from deteriorating in function before and after folding in a laminate in which various functional layers are provided on a paper substrate.

Background Art

[0002] In recent years, in order to respond to environmental concerns and the demands of SDGs (Sustainable Development Goals), there has been a desire to eliminate plastics and aluminum in the food field. In response to these demands, paper packaging materials with barrier properties (moisture-proof properties) have been studied (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a packaging material is produced using the paper laminates described in Patent Documents 1 and 2, the packaging material has a problem that the function of the functional layer (for example, moisture-proof property, etc.) deteriorates due to folding.

[0005] The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a folding resistance agent and a laminate for preventing a functional layer from deteriorating in function before and after folding in a laminate in which various functional layers are provided on a paper substrate.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the inventors of the present invention have found that the above problems can be solved by providing a fold-resistant layer between the paper base material layer and the functional layer, and have completed the present invention. That is, the fold-resistant agent and laminate of the present invention for solving the above problems mainly include the following configurations.

[0007] (1) In a laminate in which a paper base material layer, a fold-resistant layer, and a functional layer are laminated in this order, the following conditions 1 to 3 are satisfied, and a fold-resistant agent for forming the fold-resistant layer (however, except when the fold-resistant agent is OKS-1009 and the functional layer is an active energy ray-curable ink composition layer). (Condition 1) The fold-resistant agent contains a resin and a medium, The resin contains at least one selected from the group consisting of a polyurethane resin, an acrylic resin, a polyester resin, a polyvinyl alcohol resin, a styrene-butadiene resin, and a vinyl chloride resin, The content (in terms of solid content) of the resin is 70 to 100% by mass in the fold-resistant agent. (Condition 2) The elongation in the tensile test determined by the following formula of the fold-resistant layer is 200% or more. Elongation (%) = 100 × (Lb - L0) / L0 However, Lb refers to the length between the gauge marks at the time of breakage, and L0 refers to the length between the gauge marks before the tensile test. The tensile test is a tensile test carried out in accordance with JIS K 6251. (Condition 3) The shape recovery degree determined by the following formula of the fold-resistant layer is 80% or more. Shape recovery degree (%) = 100 × (L1 - L2) / (L1 - L0) However, L0 refers to the length between the gauge marks before the tensile test. L1 refers to the length between the gauge marks at 100% elongation in the tensile test, and for those that cannot be elongated to 100%, it is the length between the gauge marks at the limit without breakage. L2 refers to the length between the gauge marks of the fold-resistant layer when the external force is removed after the tensile test. The tensile test is a tensile test carried out in accordance with JIS K 6251.

[0008] According to such a configuration, the flex resistance agent is applied to form a flex resistance layer between the paper base material and the functional layer in a laminate in which various functional layers are provided on the paper base material. The obtained laminate is less likely to have the functions of the functional layer degraded before and after folding.

[0009] (2) The flex resistance agent according to (1), wherein the functional layer includes at least one of a moisture-proof layer, a gas barrier layer, an oil-resistant layer, a water-resistant layer, or a water-repellent layer.

[0010] According to such a configuration, the flex resistance agent is applied to form a flex resistance layer between the paper base material and the functional layer in a laminate in which various functional layers are provided on the paper base material. The obtained laminate is less likely to have the functions (moisture-proof property, gas barrier property, oil resistance, water resistance, or water repellency) of the various functional layers degraded before and after folding.

[0011] (3) A laminate in which a paper base material layer, a flex resistance layer, and a functional layer are laminated in this order, and the flex resistance layer is a layer formed by applying the flex resistance agent according to (1) or (2).

[0012] According to such a configuration, the obtained laminate is less likely to have the functions of the functional layer degraded before and after folding.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a flex resistance agent and a laminate for making it less likely for the functions of the functional layer to degrade before and after folding in a laminate in which various functional layers are provided on a paper base material.

Embodiments for Carrying Out the Invention

[0014] <Flex Resistance Agent> The flex resistance agent according to an embodiment of the present invention is a flex resistance agent for forming a flex resistance layer in a laminate in which a paper base material layer, a flex resistance layer, and a functional layer are laminated in this order. However, it excludes the case where the flex resistance agent is OKS-1009 and the functional layer is an active energy ray-curable ink composition layer. The flex resistance agent satisfies the following Conditions 1 to 3. Note that the flex resistance agent of the present embodiment may have a configuration in which the paper base material layer, the flex resistance layer, and the functional layer are laminated in this order, and other layers may be provided before, after, or in the middle thereof. (Condition 1) The flex resistance agent contains a resin and a medium. The resin contains at least one selected from the group consisting of a polyurethane resin, an acrylic resin, a polyester resin, a polyvinyl alcohol resin, a styrene-butadiene resin, and a vinyl chloride resin. The content of the resin (in terms of solid content) is 70 to 100% by mass in the flex resistance agent. (Condition 2) The elongation in the tensile test of the flex resistance layer determined by the following formula is 200% or more. Elongation (%) = 100×(Lb - L0) / L0 However, Lb refers to the length between the gauge marks at the time of breakage, and L0 refers to the length between the gauge marks before the tensile test. The tensile test is a tensile test carried out in accordance with JIS K 6251. (Condition 3) The shape recovery degree of the flex resistance layer determined by the following formula is 80% or more. Shape recovery degree (%) = 100×(L1 - L2) / (L1 - L0) However, L0 refers to the length between the gauge marks before the tensile test. L1 refers to the length between the gauge marks at 100% elongation in the tensile test, and for those that cannot be elongated up to 100%, it is the length between the gauge marks at the limit without breakage. L2 refers to the length between the gauge marks of the flex resistance layer when the external force is removed after the tensile test. The tensile test is a tensile test carried out in accordance with JIS K 6251. Hereinafter, each will be described.

[0015] (Regarding Condition 1) · Resin The resin contains at least one selected from the group consisting of polyurethane resins, acrylic resins, polyester resins, polyvinyl alcohol resins, styrene-butadiene resins, and vinyl chloride resins. From the viewpoints of solid content and viscosity, the resin is preferably an emulsion of a polyurethane resin, an acrylic resin, a styrene-butadiene resin, or a vinyl chloride resin. Thereby, the flex resistance agent is applied to form a flex resistance layer containing the above resin between the paper substrate and the functional layer in a laminate in which various functional layers are provided on the paper substrate. In the obtained laminate, the functions of the functional layer are less likely to deteriorate before and after folding.

[0016] The polyurethane resin is not particularly limited. For example, the polyurethane resin is a polyurethane resin obtained by reacting a diisocyanate compound, a diol compound, and optionally a chain extender or a reaction terminator.

[0017] The diisocyanate compound is not particularly limited. For example, the diisocyanate compound is an aliphatic diisocyanate compound such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; an alicyclic diisocyanate compound such as isophorone diisocyanate and hydrogenated xylylene diisocyanate; an aromatic diisocyanate compound such as xylylene diisocyanate, α,α,α’,α’-tetramethylxylylene diisocyanate, toluylene diisocyanate, and diphenylmethane diisocyanate.

[0018] The diol compound is not particularly limited. For example, the diol compound is low molecular weight diols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, and triethylene glycol; high molecular weight diols such as polyester diol compounds, polyether diol compounds, polycarbonate diol compounds, and polybutadiene glycol compounds.

[0019] In addition, the polyurethane resin may have various skeletons. For example, the polyurethane resin may be a polyether-based polyurethane resin, a polyester-based polyurethane resin, a polyester-polyether-based polyurethane resin, a polycarbonate-based polyurethane resin, or the like.

[0020] The polyester resin is not particularly limited. For example, the polyester resin can be obtained by an esterification reaction using a polyvalent carboxylic acid and a polyhydric alcohol as raw material components.

[0021] The polyvalent carboxylic acid is not particularly limited. For example, the polyvalent carboxylic acid includes phthalic acid, isophthalic acid, tetrahydrophthalic acid, tetrahydroisophthalic acid, hexahydrophthalic acid, hexahydroterephthalic acid, trimellitic acid, adipic acid, sebacic acid, succinic acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, pyromellitic acid, etc., and acid anhydrides thereof.

[0022] The polyhydric alcohol is not particularly limited. For example, the polyhydric alcohol includes glycols and polyhydric alcohols having three or more valences. Examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, hexylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, methylpropanediol, cyclohexanedimethanol, 3,3-diethyl-1,5-pentanediol, etc. Examples of polyhydric alcohols having three or more valences include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, etc.

[0023] The acrylic resin is not particularly limited. For example, the acrylic resin may be, for example, a polyester-modified acrylic resin, a polyurethane-modified acrylic resin, or a copolymer of vinyl versatate and an acrylic monomer, which is a copolymer of vinyl versatate and an acrylic monomer.

[0024] The polyvinyl alcohol-based resin is not particularly limited. For example, the polyvinyl alcohol-based resin may be polyvinyl alcohol, or a derivative or modified product of polyvinyl alcohol.

[0025] The polyvinyl alcohol-based resin preferably has a degree of polymerization of 100 to 5000, more preferably 500 to 3000. When the degree of polymerization of the polyvinyl alcohol-based resin is within the above range, the flex resistance agent has excellent film strength and handling suitability.

[0026] The saponification degree of the polyvinyl alcohol-based resin is preferably 60 mol% or more, more preferably 75 mol% or more. When the saponification degree of the polyvinyl alcohol-based resin is within the above range, the flex resistance agent has excellent film strength and water resistance.

[0027] The derivative of polyvinyl alcohol is a polyvinyl alcohol derivative in which about 40 mol% of the hydroxyl groups are acetalized.

[0028] The modified product of polyvinyl alcohol is a modified product of polyvinyl alcohol obtained by copolymerizing a carboxyl group-containing monomer, an amino group-containing monomer, a sulfone group-containing monomer, an acetoacetyl group-containing monomer, butanediol, etc.

[0029] The polyvinyl alcohol-based resin is Poval, Exceval (both manufactured by Kuraray Co., Ltd.), Gosenol, Nitgo G Polymer (both manufactured by Mitsubishi Chemical Corporation), etc.

[0030] The styrene-butadiene resin is not particularly limited. For example, the styrene-butadiene resin is a resin emulsion obtained by emulsion polymerization or solution polymerization of a monomer composition containing a styrene monomer, butadiene, and, if necessary, other monomers copolymerizable with the styrene monomer and butadiene.

[0031] The styrene monomer is styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, 4-methoxystyrene, vinyltoluene, divinylbenzene, etc.

[0032] Other monomers copolymerizable with the styrene monomer and butadiene are alkyl (meth)acrylate monomers such as methyl (meth)acrylate and butyl (meth)acrylate; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; amide group-containing monomers such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; hydroxyalkyl (meth)acrylate monomers such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; carboxyl group-containing monomers such as itaconic acid, maleic acid, and (meth)acrylic acid, etc. The styrene-butadiene resin emulsion is preferably a carboxy (carboxyl group) modified styrene-butadiene resin emulsion.

[0033] From the viewpoint of improving blocking properties and leveling properties, the glass transition temperature of the resin of the styrene-butadiene resin emulsion is preferably -20°C or higher, more preferably -10°C or higher. The glass transition temperature is determined by differential scanning calorimetry (DSC) and is usually calculated by the midpoint of the temperature range where the glass transition occurs.

[0034] The styrene-butadiene resin emulsion is Nipol SX1105A, Nipol LX407S12, Nipol LX435 (manufactured by Zeon Corporation, Japan), etc.

[0035] The vinyl chloride resin is not particularly limited. For example, the vinyl chloride resin may be a homopolymer of vinyl chloride, a copolymer of vinyl chloride and a monomer copolymerizable therewith, or a graft copolymer obtained by graft copolymerizing vinyl chloride onto a polymer other than the copolymer of vinyl chloride and a monomer copolymerizable therewith. Among these, the vinyl chloride resin is preferably a vinyl chloride resin or a vinyl chloride resin emulsion.

[0036] The method for producing the vinyl chloride resin is not particularly limited. For example, the vinyl chloride resin can be produced by any known method, such as an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, etc.

[0037] The monomer copolymerizable with vinyl chloride that constitutes the copolymer of vinyl chloride and a monomer copolymerizable therewith is not particularly limited as long as it has a reactive double bond in the molecule. Such monomers include α-olefins such as ethylene, propylene, and butylene, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as butyl vinyl ether and cetyl vinyl ether, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, esters of acrylic acid or methacrylic acid such as methyl acrylate, ethyl methacrylate, and phenyl methacrylate, aromatic vinyls such as styrene and α-methylstyrene, vinyl halides such as vinylidene chloride and vinyl fluoride, N-substituted maleimides such as N-phenyl maleimide and N-cyclohexyl maleimide, etc.

[0038] The polymer other than the vinyl chloride copolymer is not particularly limited as long as it can be graft copolymerized with vinyl chloride.

[0039] Examples of the vinyl chloride resin include Vinibran (manufactured by Nisshin Chemical Industry Co., Ltd.) and Sumika Flex (manufactured by Sumitomo Chemical Tex Co., Ltd.).

[0040] The content of the resin in the solid content of the flexure resistance agent (in terms of solid content) is not particularly limited. For example, the content of the resin may be 70% by mass or more, preferably 80% by mass or more, in the flexure resistance agent. Also, the content of the resin may be 100% by mass or less in the flexure resistance agent. By the content of the resin being within the above range, the flexure resistance agent can achieve both good coating applicability and coating film physical properties.

[0041] · Medium As long as Conditions 1 to 3 are satisfied, the medium is not particularly limited. For example, when the flexure resistance agent is aqueous, the medium may be only water, or an aqueous medium in which water and a water-miscible organic solvent are mixed. The water-miscible organic solvent is not particularly limited. For example, the water-miscible organic solvent includes alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and propylene glycol and their alkyl ether derivatives, esters such as ethyl formate, methyl acetate, and ethyl acetate, and ketones such as acetone.

[0042] In addition, when the folding resistance agent is solvent-based, the medium may be alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, normal propanol, butanol, isobutanol, tert-butanol, etc., aromatic hydrocarbon-based solvents such as toluene, xylene, etc., aliphatic hydrocarbon-based solvents such as hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, etc., ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc., ester-based solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, etc., glycol-based solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, etc. and esterified products thereof. The esterified products are preferably mainly acetate products, and examples include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, etc.

[0043] When the folding resistance agent is solvent-based, from an environmental perspective, the medium is preferably a mixed solvent of an ester-based organic solvent, an alcohol-based organic solvent and a ketone-based organic solvent, or a mixed solvent of an ester-based organic solvent and an alcohol-based organic solvent with more progress in addressing environmental issues.

[0044] The content of the medium is not particularly limited. For example, the content of the medium is preferably 40% by mass or more, more preferably 45% by mass or more in the flex resistance agent. Also, the content of the medium is preferably 80% by mass or less in the flex resistance agent. By the content of the medium being within the above range, the flex resistance agent can optimize storage stability, printability, and coating amount.

[0045] ·Optional components The flex resistance agent of this embodiment may appropriately contain optional components in addition to the above resin and medium. The optional components are not particularly limited. For example, the optional components are wax, defoaming agent, inorganic filler, release agent, thickening agent, surface conditioner, surfactant, plasticizer, polymerization inhibitor, ultraviolet absorber, light stabilizer, antioxidant, etc.

[0046] (Regarding condition 2) The flex resistance agent of this embodiment is a flex resistance agent for forming a flex resistance layer in a laminate in which a paper base material layer, a flex resistance layer, and a functional layer are laminated in this order.

[0047] Regarding condition 2, the elongation in the tensile test of the flex resistance layer obtained using the flex resistance agent of this embodiment is 200% or more. The elongation is represented by the following formula. Elongation (%) = 100×(Lb - L0) / L0 However, Lb refers to the length between gauge marks at the time of breakage, and L0 refers to the length between gauge marks before the tensile test. The tensile test is a tensile test carried out in accordance with JIS K 6251.

[0048] The elongation of the flex resistance layer only needs to be 200% or more, and is preferably 250% or more. When the elongation of the flex resistance layer is less than 200%, it is difficult for the flex resistance layer to maintain the function of the functional layer before and after folding the laminate, and the function is likely to deteriorate. In this embodiment, the elongation of the flex resistance layer can be measured by the following method.

[0049] ·Method for measuring the elongation of the flex resistance layer Apply a flexure-resistant agent onto an arbitrary substrate such as glass, dry it, peel it off, and produce a test piece in the shape of a JIS K 6251 tensile No. 3 dumbbell (film thickness: 300 μm). Next, measure the elongation when each test piece is pulled until it breaks using the following testing machine under the following conditions. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation Elongation rate: 300 mm / min Temperature: 23°C Humidity: 50%

[0050] (Regarding Condition 3) Regarding Condition 3, the shape recovery degree of the flexure-resistant layer is 80% or more. The shape recovery degree may be 80% or more, preferably 90% or more, and more preferably 95% or more. If the shape recovery degree is less than 80%, it is difficult for the flexure-resistant layer to maintain the function of the functional layer.

[0051] In this embodiment, the shape recovery degree can be evaluated by conducting a tensile test performed in accordance with JIS K 6251. The tensile test for evaluating the shape recovery degree can be carried out using the following testing machine under the following conditions.

[0052] · Method for evaluating the shape recovery degree of the flexure-resistant layer Apply a flexure-resistant agent onto an arbitrary substrate such as glass, dry it, peel it off, and make it into the shape of a test piece. Using the obtained test piece, produce a JIS K 6251 tensile No. 3 dumbbell (film thickness: 300 μm). Next, extend each test piece using the following testing machine under the following conditions and hold it in that state for 5 minutes. Then, remove the test piece from the testing machine and measure the length of the test piece after 3 hours. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation Elongation rate: 50 mm / min Temperature: 23°C Humidity: 50% The shape recovery degree is obtained by the following formula. Shape recovery degree (%) = 100 × (L1 - L2) / (L1 - L0) × 100 However, L0 refers to the length between the gauge marks before the tensile test. L1 refers to the length between the gauge marks at 100% elongation in the tensile test, and for those that cannot be elongated up to 100%, it is the length between the gauge marks at the limit without breaking. L2 is the length between the gauge marks when the external force is removed after the tensile test.

[0053] Returning to the description of the entire folding resistance agent, the laminate to which the folding resistance agent is applied is a laminate in which a paper base material layer, a folding resistance layer, and a functional layer are laminated in this order.

[0054] (Paper base material layer) The paper base material layer is not particularly limited. For example, the paper constituting the paper base material layer is not particularly limited. For example, the paper may be any paper generally used with plant-derived pulp as the main component, such as bleached or unbleached kraft paper, high-quality paper, cardboard, liner paper, coated paper, single-sided coated paper, glassine paper, graphane paper, etc. Among these, the paper is preferably a paper mainly composed of pulp that is easily dispersed in water by mechanical dissociation action.

[0055] The basis weight and thickness of the paper base material layer are not particularly limited. For example, the basis weight of the paper base material layer is preferably 30 g / m 2 or more, and more preferably 50 g / m 2 or more. Also, the thickness of the paper base material layer is preferably 300 g / m 2 or less, and more preferably 250 g / m 2 or less. When the thickness and basis weight of the paper base material layer are within the above ranges, the folding resistance agent can easily maintain the function of the functional layer.

[0056] (Folding resistance layer) The folding resistance layer is a layer formed by applying the folding resistance agent of the present embodiment.

[0057] The method for applying the folding resistance agent to the paper base material is not particularly limited. For example, the application method is a method using a blade coater, a bar coater, an air knife coater, a slit die coater, a gravure coater, a gravure reverse coater, a microgravure coater, a gate roll coater, etc.

[0058] The applied folding resistance agent is dried. The drying method for drying the folding resistance agent is not particularly limited. For example, as a drying method, known drying equipment can be used, and a hot air dryer, an infrared dryer, a gas burner, a hot plate, etc. can be used.

[0059] The thickness of the folding resistance layer is not particularly limited. For example, the thickness of the folding resistance layer is preferably 1 μm or more, more preferably 3 μm or more. Also, the thickness of the folding resistance layer is preferably 30 μm or less, more preferably 20 μm or less. When the thickness of the folding resistance layer is within the above range, the resulting laminate is less likely to have the functions of the functional layer degraded before and after folding.

[0060] (Functional layer) The functional layer is a layer for imparting various functions to the paper substrate. The laminate of the present embodiment includes a folding resistance layer formed by applying the above-described folding resistance agent. As a result, the functions imparted by the functional layer in the laminate are less likely to be impaired before and after folding.

[0061] The functional layer is not particularly limited. The functional layer can be appropriately selected according to the desired application. Specifically, the functional layer preferably includes at least one of a moisture-proof layer, a gas barrier layer, an oil-resistant layer, a water-resistant layer, or a water-repellent layer. Thereby, the functions (moisture-proof property, gas barrier property, oil resistance, water resistance, or water repellency) of various functional layers in the obtained laminate are less likely to be degraded before and after folding.

[0062] ·When the functional layer is a moisture-proof layer The moisture-proof layer is provided by applying a moisture-proof coating agent. For example, the moisture-proof coating agent includes an anionic binder resin, an inorganic layered compound, and an aqueous medium.

[0063] The anionic binder resin is not particularly limited. For example, the anionic binder resin may be a styrene-butadiene copolymer, a styrene-acrylic copolymer, a methacrylate-butadiene copolymer, an acrylonitrile-butadiene copolymer, an olefin-unsaturated carboxylic acid copolymer, an acrylic ester polymer, or the like. Among these, the anionic binder resin is preferably at least one selected from the group consisting of a styrene-butadiene copolymer, a styrene-acrylic copolymer, and an olefin-unsaturated carboxylic acid copolymer, more preferably an olefin-unsaturated carboxylic acid copolymer, because of its good water resistance, good elongation, and low tendency for cracks to occur in the functional layer due to folding.

[0064] The styrene-butadiene copolymer is a copolymer obtained by emulsion polymerization of monomers consisting of aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, p-t-butylstyrene, chlorostyrene, conjugated diene compounds such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and other compounds copolymerizable therewith. The aromatic vinyl compound is preferably styrene or the like. The conjugated diene compound is preferably 1,3-butadiene.

[0065] Styrene-acrylic copolymer is a copolymer obtained by emulsion polymerization of a monomer consisting of an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, p-t-butylstyrene, chlorostyrene, etc., an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, butenetricarboxylic acid, etc., an unsaturated polycarboxylic acid alkyl ester having at least one carboxyl group such as monoethyl itaconate, monobutyl fumarate and monobutyl maleate, an unsaturated sulfonic acid monomer or its salt such as acrylamidopropanesulfonic acid, sodium acrylate sulfonatoethyl salt, sodium methacrylate sulfopropyl salt, etc., and other compounds copolymerizable therewith. The aromatic vinyl compound is preferably styrene or the like. The unsaturated carboxylic acid monomer, the unsaturated sulfonic acid monomer or its salt is preferably acrylic acid, methacrylic acid, itaconic acid, fumaric acid or the like.

[0066] The olefin-unsaturated carboxylic acid copolymer is a copolymer obtained by emulsion polymerization of monomers consisting of olefins, especially α-olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butene tricarboxylic acid, unsaturated polycarboxylic acid alkyl esters having at least one carboxyl group such as monoethyl itaconate, monobutyl fumarate, and monobutyl maleate, unsaturated sulfonic acid monomers or their salts such as acrylamidopropanesulfonic acid, sodium acrylate sulfonate, and sodium methacrylate sulfonate, and other compounds copolymerizable therewith. The olefin is preferably an α-olefin, especially ethylene. The unsaturated carboxylic acid monomer, unsaturated sulfonic acid monomer or its salt is preferably acrylic acid, methacrylic acid, itaconic acid, fumaric acid, etc. As a specific example of the olefin-unsaturated carboxylic acid copolymer, an aqueous dispersion of an ethylene-acrylic acid copolymer ammonium salt is commercially available as Zeicen AC, Zeicen A, etc. (manufactured by Sumitomo Seika Chemicals Co., Ltd.) and can be easily obtained and used.

[0067] The content of the anionic binder resin is not particularly limited. For example, the content of the anionic binder resin is preferably 20% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, and particularly preferably 70% by mass or more based on the total solid content of the moisture-proof coating agent. Also, the content of the anionic binder resin is preferably 95% by mass or less, more preferably 85% by mass or less in the total solid content of the moisture-proof coating agent. When the content of the anionic binder resin is within the above range, the resulting functional layer (moisture-proof layer) can exhibit high moisture-proof performance.

[0068] The inorganic layered compound is not particularly limited. For example, the inorganic layered compound may be either a natural product or a synthetic product, or a mixture thereof. Natural products include smectite-based clay minerals such as montmorillonite, kaolinite (kaolin mineral), pyrophyllite, talc, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite, and mica-based clay minerals such as bentonite, pure mica, and brittle mica. Synthetic products include synthetic hectorite (sodium magnesium silicate), synthetic bentonite, synthetic saponite, and synthetic mica. Among these, from the viewpoint of improving dispersibility, the inorganic layered compound is preferably at least one selected from the group consisting of water-swellable montmorillonite, bentonite, synthetic mica, synthetic hectorite, and synthetic bentonite. Also, from the viewpoint of improving barrier properties, the inorganic layered compound is more preferably montmorillonite, synthetic mica, or synthetic hectorite. The inorganic layered compounds may be used in combination.

[0069] The content of the inorganic layered compound is not particularly limited. For example, the content of the inorganic layered compound is preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 30% by mass or less, and particularly preferably 20% by mass or less, based on the total solid content in the moisture-proof coating agent. On the other hand, the content of the inorganic layered compound is preferably 1% by mass or more, more preferably 2% by mass or more, based on the total solid content in the moisture-proof coating agent. When the content of the inorganic layered compound is within the above range, the resulting functional layer (moisture-proof layer) can exhibit high moisture-proof properties.

[0070] The aqueous medium is not particularly limited. For example, the aqueous medium may be water alone, or an aqueous medium obtained by mixing water with water-miscible organic solvents such as alcohols like methanol, ethanol, and propanol, polyhydric alcohols like ethylene glycol and propylene glycol and their alkyl ether derivatives, esters like ethyl formate, methyl acetate, and ethyl acetate, and ketones like acetone.

[0071] The moisture-proof coating agent may contain at least one selected from amino acids and cationic resins in order to further improve moisture-proof properties. The amino acids and cationic resins are not particularly limited. For example, the amino acids include amino acids such as glycine, alanine, leucine, valine, phenylalanine, proline, serine, threonine, lysine, arginine, aspartic acid, glutamic acid, polylysine, polyglutamic acid, polyglutamic acid, polymers of amino acids, amino acid derivatives, etc. The amino acids may be copolymers of amino acids. From the viewpoint of better moisture-proof properties, the amino acids are preferably copolymers or polymers of amino acids.

[0072] The cationic resins include polyalkylene polyamines, polyamide compounds, polyamideamine-epihalohydrin or formaldehyde condensation reaction products, polyamine-epihalohydrin or formaldehyde condensation reaction products, polyamidepolyurea-epihalohydrin or formaldehyde condensation reaction products, polyaminepolyurea-epihalohydrin or formaldehyde condensation reaction products, polyamideaminepolyurea-epihalohydrin or formaldehyde condensation reaction products, polyamidepolyurea compounds, polyaminepolyurea compounds, polyamideaminepolyurea compounds and polyamideamine compounds, polyethyleneimine, polyvinylpyridine, amino-modified acrylamide-based compounds, polyvinylamine, polydiallyldimethylammonium chloride, etc.

[0073] The moisture-proof coating agent may be appropriately blended with additives as necessary. The additives are not particularly limited. For example, the additives include dispersants, surfactants, defoamers, wetting agents, dyes, color adjusters, thickeners, etc.

[0074] The production method of the moisture-proof coating agent is not particularly limited. For example, the moisture-proof coating agent can be prepared by mixing an anionic binder resin, an inorganic layered compound, an aqueous medium and, as appropriate, amino acids, cationic resins, and additives, and stirring and mixing them sufficiently at room temperature.

[0075] When the functional layer is a moisture-proof layer, the thickness of the moisture-proof layer is not particularly limited. For example, the thickness of the moisture-proof layer is preferably 3 μm or more, more preferably 5 μm or more. Also, the thickness of the moisture-proof layer is preferably 30 μm or less, more preferably 20 μm or less. When the thickness of the moisture-proof layer is within the above range, the resulting laminate has excellent moisture-proof properties.

[0076] · When the functional layer is a gas barrier layer The gas barrier layer is provided by applying a gas barrier coating agent. For example, the gas barrier coating agent contains an aqueous polymer, an inorganic layered compound, and an aqueous medium.

[0077] The aqueous polymer is not particularly limited. For example, the aqueous polymer is polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinyl pyrrolidone, polyacrylonitrile-based resin, polyamide-based resin, polyester-based resin, urethane-based resin, polyacrylic acid and its salts, casein, polyethyleneimine, etc. Among these, the aqueous polymer is preferably completely saponified or partially saponified polyvinyl alcohol, or modified polyvinyl alcohol, from the viewpoint of imparting more excellent gas barrier properties. Examples of the modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, etc.

[0078] The content of the aqueous polymer is not particularly limited. For example, the content of the aqueous polymer is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total solid content of the gas barrier coating agent.

[0079] The inorganic layered compound is the same as the inorganic layered compound described above in relation to the moisture-proof layer. The inorganic layered compound is preferably at least one selected from the group consisting of mica, bentonite, and kaolin, from the viewpoint of improving the gas barrier properties.

[0080] The content of the inorganic layered compound is not particularly limited. For example, the content of the inorganic layered compound is preferably 1 part by mass or more, more preferably 30 parts by mass or more, based on 100 parts by mass of the aqueous polymer of the gas barrier coating agent. Further, the content of the inorganic layered compound is preferably 20 parts by mass or less, more preferably 50 parts by mass or less, based on 100 parts by mass of the aqueous polymer of the gas barrier coating agent. When the content of the inorganic layered compound is within the above range, the obtained functional layer (gas barrier layer) has excellent gas barrier properties under high humidity conditions.

[0081] The aqueous medium may be only water, or an aqueous medium in which water is mixed with water-miscible organic solvents such as alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and propylene glycol and their alkyl ether derivatives, esters such as ethyl formate, methyl acetate, and ethyl acetate, and ketones such as acetone.

[0082] The method for producing the gas barrier coating agent is not particularly limited. For example, the gas barrier coating agent can be prepared by mixing an aqueous polymer, an inorganic layered compound, and an aqueous medium and stirring and mixing them sufficiently at room temperature.

[0083] When the functional layer is a gas barrier layer, the thickness of the gas barrier layer is not particularly limited. For example, the thickness of the gas barrier layer is preferably 0.1 μm or more, more preferably 0.5 μm or more. Further, the thickness of the gas barrier layer is preferably 10 μm or less, more preferably 5 μm or less. When the thickness of the gas barrier layer is within the above range, the obtained laminate has excellent gas barrier properties.

[0084] · When the functional layer is an oil-resistant layer The oil-resistant layer is provided by applying an oil-resistant coating agent. For example, as the oil-resistant coating agent, an oil-resistant coating agent containing a pigment, a styrene-butadiene copolymer, polyvinyl alcohol, and an aqueous medium, a styrene-acrylic copolymer, a wax, and an aqueous medium can be used.

[0085] An oil-resistant coating agent containing a pigment, a styrene-butadiene copolymer, polyvinyl alcohol, and an aqueous medium will be described.

[0086] The pigment is not particularly limited. For example, the pigment is various pigments such as inorganic pigments and organic pigments. The inorganic pigments are kaolins such as kaolin, structural kaolin, delamic kaolin, and calcined kaolin, synthetic mica, heavy calcium carbonate, light calcium carbonate, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, aluminum hydroxide, magnesium carbonate, magnesium oxide, silica, magnesium aluminosilicate, calcium silicate, white carbon, bentonite, zeolite, sericite, smectite, and other minerals. Among these, kaolin is preferable because it can impart excellent oil resistance and water resistance. Also, kaolin has excellent transparency and gloss when the density of the oil-resistant paper is increased.

[0087] When the pigment is kaolin, the average particle size of kaolin is preferably 0.5 μm or more, more preferably 1 μm or more. Also, the average particle size of kaolin is preferably 20 μm or less, more preferably 10 μm or less. When the average particle size of kaolin is within the above range, the obtained functional layer (oil-resistant layer) has excellent oil resistance.

[0088] Organic pigments are polymers and copolymers of polydienes such as polyisoprene, polychloroprene, polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene, vinyl monomers such as vinyl acetate, styrene, (meth)acrylic acid, (meth)acrylic acid alkyl esters, (meth)acrylamide, methyl vinyl ether, etc., polyurethane resins, polyester resins, polyamide resins, urea resins, melamine resins, benzoguanamine resins, etc., in the form of solid, hollow, or through-hole particles.

[0089] The pigment content is not particularly limited. For example, the pigment content is preferably 20% by mass or more, more preferably 40% by mass or more, based on the total solid content of the oil-resistant coating agent. Also, the pigment content is preferably 70% by mass or less, more preferably 65% by mass or less, based on the total solid content of the oil-resistant coating agent. When the pigment content is within the above range, the resulting oil-resistant layer has excellent oil resistance and water resistance.

[0090] Styrene-butadiene copolymer is blended to impart excellent water resistance (water repellency) to the functional layer. Styrene-butadiene copolymer is obtained by copolymerizing styrene and butadiene as monomers. When a water-insoluble copolymer is used, the copolymer can be used in the form of a latex. The styrene-butadiene copolymer of this embodiment is not particularly limited. For example, the styrene-butadiene copolymer is "A6160" commercially available from Asahi Kasei Corporation, etc.

[0091] The glass transition temperature (Tg) of the styrene-butadiene copolymer is preferably 30°C or lower, more preferably 20°C or lower, and even more preferably 0°C or lower. Also, the Tg of the styrene-butadiene copolymer is preferably -40°C or higher, more preferably -30°C or higher, and even more preferably -20°C or higher. When the Tg of the styrene-butadiene copolymer is within the above range, the resulting oil-resistant layer can exhibit excellent film-forming ability and excellent water-repellent oil resistance.

[0092] The average particle diameter of the styrene-butadiene copolymer is preferably 0.01 μm or more, more preferably 0.03 μm or more. Further, the average particle diameter of the styrene-butadiene copolymer is preferably 1.0 μm or less, more preferably 0.5 μm or less. When the average particle diameter of the styrene-butadiene copolymer is within the above range, the styrene-butadiene copolymer has excellent water dispersibility.

[0093] The content of the styrene-butadiene copolymer is not particularly limited. For example, the content of the styrene-butadiene copolymer is preferably 20% by mass or more, more preferably 25% by mass or more, based on the total solid content of the oil-resistant coating agent. Further, the content of the styrene-butadiene copolymer is preferably 50% by mass or less, more preferably 45% by mass or less, based on the total solid content of the oil-resistant coating agent. When the content of the styrene-butadiene copolymer is within the above range, the oil-resistant coating agent can form an oil-resistant layer having excellent water resistance (water repellency) in addition to oil resistance on the paper substrate.

[0094] The polyvinyl alcohol is not particularly limited. For example, the polyvinyl alcohol is a polyvinyl alcohol-based resin such as unmodified completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, or modified polyvinyl alcohol. Modified polyvinyl alcohol includes ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, diacetone group-modified polyvinyl alcohol, and the like. Among these, unmodified completely saponified polyvinyl alcohol, ethylene-modified polyvinyl alcohol, and carboxy-modified polyvinyl alcohol are preferable because they can impart excellent oil resistance. Further, ethylene-modified polyvinyl alcohol can suppress the thickening of the oil-resistant coating agent. Thereby, the oil-resistant coating agent has excellent coating applicability. Also, the obtained oil-resistant layer has an excellent state of the coated surface.

[0095] The content of the polyvinyl alcohol-based resin is not particularly limited. For example, the content of the polyvinyl alcohol-based resin is preferably 0.5% by mass or more, more preferably 3% by mass or more, based on the total solid content of the oil-resistant coating agent. Further, the content of the polyvinyl alcohol-based resin is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the oil-resistant coating agent. When the content of the polyvinyl alcohol-based resin is within the above range, the obtained oil-resistant layer can exhibit more excellent oil resistance. Further, the polyvinyl alcohol-based resin can suppress the thickening of the oil-resistant coating agent. Thereby, the oil-resistant coating agent can suppress the occurrence of coating defects.

[0096] The aqueous medium may be only water, or an aqueous medium in which water is mixed with water-miscible organic solvents such as alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and propylene glycol and their alkyl ether derivatives, esters such as ethyl formate, methyl acetate, and ethyl acetate, and ketones such as acetone.

[0097] Next, an oil-resistant coating agent containing a styrene-acrylic copolymer, wax, and an aqueous medium will be described.

[0098] Examples of the styrene-acrylic copolymer include styrene-acrylic copolymers obtained by copolymerizing styrene and styrene derivatives with acrylic acid (methacrylic acid) and alkyl acrylates such as methyl acrylate, ethyl acrylate, and butyl acrylate, and alkyl methacrylates such as methyl methacrylate. Preferably, it is a styrene-acrylic copolymer emulsion.

[0099] The waxes include polyolefin waxes such as paraffin wax, carboxyl group-containing paraffin wax, microcrystalline wax, polyethylene wax, carboxyl group-containing polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, candelilla wax, rice wax, montan wax, fatty acids such as stearic acid, fatty acid amides such as stearic acid amide, bis-stearic acid amide, oleic acid amide, palmitic acid amide, and fatty acid metal salts such as zinc stearate and calcium stearate. The content of the wax is preferably 1.5 to 20% by mass in the total solid content of the oil-resistant coating agent.

[0100] The aqueous medium may be only water, or an aqueous medium obtained by mixing water with water-miscible organic solvents such as alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and propylene glycol and their alkyl ether derivatives, esters such as ethyl formate, methyl acetate, and ethyl acetate, and ketones such as acetone.

[0101] The production method of the oil-resistant coating agent is not particularly limited. For example, the oil-resistant coating agent can be prepared by mixing a pigment, a styrene-butadiene copolymer, polyvinyl alcohol, and an aqueous medium, or by mixing a styrene-acrylic copolymer, a wax, and an aqueous medium, and sufficiently stirring and mixing at room temperature.

[0102] When the functional layer is an oil-resistant layer, the thickness of the oil-resistant layer is not particularly limited. For example, the thickness of the oil-resistant layer is preferably 1 μm or more, more preferably 3 μm or more. Also, the thickness of the oil-resistant layer is preferably 20 μm or less, more preferably 10 μm or less. When the thickness of the oil-resistant layer is within the above range, the obtained laminate has excellent oil resistance.

[0103] · When the functional layer is a water-resistant layer The water-resistant layer is provided by applying a water-resistant coating agent. The water-resistant coating agent is not particularly limited. For example, the water-resistant coating agent is a styrene-acrylic copolymer, wax, a water-resistant coating agent containing an aqueous medium, or the like.

[0104] The styrene-acrylic copolymer is not particularly limited. For example, the styrene-acrylic copolymer is a styrene-acrylic copolymer obtained by copolymerizing styrene and styrene derivatives with acrylic acid (methacrylic acid) and alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, and alkyl methacrylates such as methyl methacrylate. Among these, the styrene-acrylic copolymer is preferably a styrene-acrylic copolymer emulsion.

[0105] The wax is not particularly limited. For example, the wax is a paraffin wax, a carboxyl group-containing paraffin wax, a microcrystalline wax, a polyethylene wax, a carboxyl group-containing polyethylene wax, a polypropylene wax, an ethylene-propylene copolymer wax, or other polyolefin waxes, a candelilla wax, a rice wax, a montan wax, a fatty acid such as stearic acid, a fatty acid amide such as stearic acid amide, bis-stearic acid amide, oleic acid amide, or palmitic acid amide, or a fatty acid metal salt such as zinc stearate or calcium stearate. The content of the wax is preferably 1.5 to 20% by mass in the total solid content of the water-resistant coating agent.

[0106] The aqueous medium may be only water, or an aqueous medium obtained by mixing water with water-miscible organic solvents such as alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and propylene glycol and their alkyl ether derivatives, esters such as ethyl formate, methyl acetate, and ethyl acetate, and ketones such as acetone.

[0107] The manufacturing method of the water-resistant coating agent is not particularly limited. For example, the water-resistant coating agent can be prepared by mixing a styrene-acrylic copolymer, wax, and an aqueous medium, and sufficiently stirring and mixing them at room temperature.

[0108] When the functional layer is a water-resistant layer, the thickness of the water-resistant layer is not particularly limited. For example, the thickness of the water-resistant layer is preferably 1 μm or more, more preferably 3 μm or more. Also, the thickness of the water-resistant layer is preferably 20 μm or less, more preferably 10 μm or less. When the thickness of the water-resistant layer is within the above range, the obtained laminate has excellent water resistance.

[0109] ·When the functional layer is a water-repellent layer The water-repellent layer is provided by applying a water-repellent coating agent. For example, the water-repellent coating agent contains a water-repellent agent, an aqueous medium, and an inorganic pigment as needed.

[0110] The water-repellent agent is not particularly limited. For example, the water-repellent agent is an aqueous coating agent containing a paraffinic hydrocarbon (e.g., Brightone FC-350 manufactured by Sakata Inx Co., Ltd.), a wax-based water-repellent agent (e.g., Celestar 40R manufactured by Lion Specialty Chemicals Co., Ltd.), etc. The water-repellent agent is not limited to paraffinic. The water-repellent agent may contain microcrystalline wax, modified wax components such as polyethylene wax and maleated petroleum resin, etc. Also, the wax-based component may contain a rosin-based resin or an unsaturated higher alcohol, etc.

[0111] The aqueous medium may be only water, or an aqueous medium mixed with water and water-miscible organic solvents such as alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and propylene glycol and their alkyl ether derivatives, esters such as ethyl formate, methyl acetate, and ethyl acetate, and ketones such as acetone.

[0112] The manufacturing method of the water-repellent coating agent is not particularly limited. For example, the water-repellent coating agent can be prepared by mixing a water-repellent agent and an aqueous medium and sufficiently stirring and mixing them at room temperature.

[0113] When the functional layer is a water-repellent layer, the thickness of the water-repellent layer is not particularly limited. For example, the thickness of the water-repellent layer is preferably 1 μm or more, more preferably 3 μm or more. Also, the thickness of the water-repellent layer is preferably 20 μm or less, more preferably 10 μm or less. When the thickness of the water-repellent layer is within the above range, the obtained laminate has excellent water repellency.

[0114] Returning to the description of the flex resistance agent, the flex resistance agent of the present embodiment is applied to form a flex resistance layer between the paper substrate and the functional layer in a laminate in which various functional layers are provided on the paper substrate. The obtained laminate has a function layer whose function is less likely to deteriorate before and after bending.

[0115] <Laminate and method for manufacturing laminate> A laminate according to an embodiment of the present invention is a laminate in which a paper substrate layer, a flex resistance layer, and a functional layer are laminated in this order. The flex resistance layer is a layer formed by applying the above-described flex resistance agent.

[0116] The paper substrate layer, the flex resistance layer, and the functional layer constituting the laminate are as described above in relation to the embodiment of the flex resistance agent.

[0117] The manufacturing method of the laminate is not particularly limited. For example, the laminate can be produced by applying a flex resistance agent to a paper substrate layer and then applying various functional coating agents (moisture-proof coating agent, gas barrier coating agent, oil-resistant coating agent, water-resistant coating agent, water-repellent coating agent). The applied flex resistance agent and functional coating agent may be dried after each is applied, or may be dried together after both are applied.

[0118] The coating amount (in terms of solid content) of the flex resistance layer is preferably 1 g / m 2 or more, preferably 3 g / m 2It is more preferable that it is as described above. Further, the coating amount (in terms of solid content) of the fold-resistant layer is preferably 30 g / m 2 or less, and more preferably 20 g / m 2 or less. When the coating amount of the fold-resistant layer is within the above range, the resulting laminate exhibits excellent fold resistance.

[0119] When the functional layer is a moisture-proof layer, the coating amount (in terms of solid content) of the moisture-proof coating agent is preferably 1 g / m 2 or more, and more preferably 3 g / m 2 or more. Further, the coating amount (in terms of solid content) of the moisture-proof coating agent is preferably 30 g / m 2 or less, and more preferably 20 g / m 2 or less. When the coating amount of the moisture-proof coating agent is within the above range, the laminate exhibits excellent moisture-proof property.

[0120] When the functional layer is a gas barrier layer, the coating amount (in terms of solid content) of the gas barrier coating agent is preferably 0.1 g / m 2 or more, and more preferably 0.5 g / m 2 or more. Further, the coating amount (in terms of solid content) of the gas barrier coating agent is preferably 10 g / m 2 or less, and more preferably 5 g / m 2 or less. When the coating amount of the gas barrier coating agent is within the above range, the laminate exhibits excellent gas barrier property.

[0121] When the functional layer is an oil-resistant layer, the coating amount (in terms of solid content) of the oil-resistant coating agent is preferably 1 g / m 2 or more, and more preferably 3 g / m 2 or more. Further, the coating amount (in terms of solid content) of the oil-resistant coating agent is preferably 20 g / m 2 or less, and more preferably 10 g / m 2 or less. When the coating amount of the oil-resistant coating agent is within the above range, the laminate exhibits excellent oil resistance.

[0122] When the functional layer is a water-resistant layer, the coating amount of the water-resistant coating agent (converted into solid content) is 1 g / m 2 It is preferable that the content is 3 g / m or more. 2 It is more preferable that the coating amount of the water-resistant coating agent (converted into solid content) is 20 g / m or more. 2 It is preferable that the thickness is less than 10 g / m 2 When the coating amount of the water-resistant coating agent is within the above range, the laminate exhibits excellent water resistance.

[0123] When the functional layer is a water-repellent layer, the coating amount of the water-repellent coating agent (converted into solid content) is 1 g / m 2 It is preferable that the content is 3 g / m or more. 2 It is more preferable that the coating amount of the water-repellent coating agent (converted into solid content) is 20 g / m or more. 2 It is preferable that the thickness is less than 10 g / m 2 When the coating amount of the water-repellent coating agent is within the above range, the laminate exhibits excellent water repellency.

[0124] As described above, according to the present embodiment, in a laminate in which various functional layers are provided on a paper base material, a fold-resistant layer containing the above-mentioned fold-resistant agent is formed between the paper base material and the functional layer, so that the function of the functional layer in the obtained laminate is unlikely to deteriorate before and after folding. EXAMPLES

[0125] The present invention will be described in more detail below with reference to the following examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass". The figures for the amounts of each material in the tables are "parts by mass".

[0126] The raw materials used are shown below. <Paper base material> OK Blizzard (grammage 70g / m 2 (manufactured by Oji Materia Co., Ltd.)

[0127] <Damp-proof coating agent> To 60.0 parts of an anionic binder (Zicen A, solid content 25%, manufactured by Sumitomo Seika Chemical Co., Ltd.), 25.0 parts of an inorganic layered compound (Somashif ME300B-4T, solid content 8%, manufactured by Katakura Chikkarin Co., Ltd.) were added under stirring. Further, 2.0 parts of a modified amide resin (Sumirez® Resin SPI-203(50)H, manufactured by Tago Chemical Industry Co., Ltd.) as a dispersant and 13 parts of ion-exchanged water were added and stirred to obtain a moisture-proof coating agent.

[0128] <Oil-resistant coating agent> For the oil-resistant coating agent, INXKote WB FLEXO FDA GREASE RES AC4551 was used.

[0129] <Flexure-resistant agent> Polyurethane resin 1 (Superflex 460S, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Polyurethane resin 2 (Superflex 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Acrylic resin 1 (DXA.4081, manufactured by VANORA) Acrylic resin 2 (Neocryl A-1125, manufactured by Covestro) Polyvinyl alcohol resin 1 (OKS-1009, manufactured by Mitsubishi Chemical Corporation) Polyvinyl alcohol resin 2 (BVE8049Q, manufactured by Mitsubishi Chemical Corporation) Polyvinyl alcohol resin 3 (OKS-8118, manufactured by Mitsubishi Chemical Corporation) Styrene-butadiene resin 1 (Sumatex VA-1015, manufactured by Nippon A&R Co., Ltd.) Styrene-butadiene resin 2 (Nipol LX407S12, manufactured by Zeon Corporation)

[0130] <Manufacturing method of flexure-resistant agent> As shown in Table 1, polyurethane resins 1 and 2, acrylic resin 1, and styrene-butadiene resins 1 and 2 were diluted with a medium (ion-exchanged water) to a solid content of 30% to obtain flex resistance agents 1 to 3, 8, and 9. For acrylic resin 2, the undiluted solution was used as flex resistance agent 4. Also, polyvinyl alcohol resins 1 to 3 were dissolved in a solvent (ion-exchanged water) to prepare solutions with a solid content of 10% to obtain flex resistance agents 5 to 7.

[0131]

Table 1

[0132] <Example 1> On one surface of the paper substrate, flex resistance agent 1 was applied with a bar coater so that the coating amount after drying would be 3 g / m 2 and then dried with a dryer air at 60°C to form a flex resistance layer. Further, an oil resistance agent was applied on top of it with a bar coater so that the coating amount after drying would be 6 g / m 2 and then dried with a dryer air at 60°C to form an oil resistance layer, thereby creating the laminate for oil resistance evaluation of Example 1.

[0133] <Examples 2 to 8> Using the combinations shown in Table 2 below, laminates for oil resistance evaluation or laminates for moisture resistance evaluation were produced in the same manner as in Example 1, except that flex resistance agents 1, 3, 5, and 6 were used for the oil resistance layer and the moisture-proof layer.

[0134] <Comparative Examples 1 and 2> On one surface of the paper substrate, each functional layer was applied with a bar coater so that the coating amount after drying would be 6 g / m 2 and then dried with a dryer air at 60°C to form an oil resistance layer, thereby creating the laminates for oil resistance evaluation or laminates for moisture resistance evaluation of Comparative Examples 1 and 2.

[0135] <Comparative Examples 3 to 10> Using the combinations shown in Table 2 below, except that flex resistance agents 2, 4, 7, and 9 were used for the oil-resistant layer and the moisture-proof layer, a laminate for oil resistance evaluation or a laminate for moisture-proof evaluation was produced in the same manner as in Example 1.

[0136] The elongation of the flex-resistant layer and the shape recovery degree of the flex-resistant layer were evaluated by the following evaluation methods. The results are shown in Table 2.

[0137] In addition, for the obtained laminate, depending on the type of the produced functional layer, the moisture-proof property and the oil resistance were evaluated. These evaluations were performed before and after the following bending. The results are shown in Table 2.

[0138] (Measurement method for the elongation of the flex-resistant layer) A flex resistance agent was applied onto a glass substrate, dried, and peeled off to produce a test piece in the shape of a dumbbell No. 3 for tension (film thickness: 300 μm) according to JIS K 6251. Next, under the following conditions, using the following testing machine, the elongation when each test piece was pulled until it broke was measured. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation Extension speed: 300 mm / min Temperature: 23°C Humidity: 50% The elongation is obtained by the following formula. Elongation (%) = 100×(Lb - L0) / L0 However, Lb refers to the length between the gauge marks at the time of fracture, and L0 refers to the length between the gauge marks before the tensile test. The tensile test is a tensile test carried out in accordance with JIS K 6251.

[0139] (Evaluation method for the shape recovery degree of the flex resistance agent) The shape recovery degree was evaluated by conducting a tensile test performed in accordance with JIS K 6251. The tensile test for evaluating the shape recovery degree was carried out using the following testing machine under the following conditions. A bending resistance agent was applied onto a glass substrate, dried, and then peeled off to produce test pieces in the shape of a dumbbell No. 3 for JIS K 6251 tensile test (film thickness: 300 μm). Subsequently, each test piece was stretched using the following testing machine under the following conditions and held in that state for 5 minutes. Then, the test piece was removed from the testing machine, and the length of the test piece after 3 hours was measured. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation Stretching speed: 50 mm / min Temperature: 23 °C Humidity: 50% The shape recovery degree is determined by the following formula. Shape recovery degree (%) = 100 × (L1 - L2) / (L1 - L0) However, L0 refers to the length between the gauge marks before the tensile test. L1 refers to the length between the gauge marks at 100% elongation in the tensile test, and for those that cannot be elongated up to 100%, it is the length between the gauge marks at the limit without breaking. L2 is the length between the gauge marks when the external force is removed after the tensile test.

[0140] (Bending method) While rolling a 4000 g roller at a speed of 30 cm / second, it was passed over the laminate 10 times to make the first fold on the laminate. The folded laminate was opened, and a second fold was made in the same manner as the first fold so as to be perpendicular to the first fold. Note that the folding direction of the laminate was such that the side coated with the coating agent was on the inside.

[0141] (Oil resistance) 0.03 g of salad oil was dropped onto the coated surface of the laminate (for the sample after folding, it was on the intersection of the folds). After 90 minutes, the area where the salad oil seeped through to the back surface was measured, and it was evaluated how much the seepage area was reduced compared to the case where no bending resistance layer was provided. Note that the seepage area in the case where no bending resistance layer was provided (Comparative Example 1) was 12.4 cm 2 It was. Also, when no folds were made on the laminate in all the examples and comparative examples, there was no seepage to the back surface at all.

[0142] (Moisture resistance) The laminate obtained above was measured for water vapor transmission rate (WVTR value, g / m 2 / day) in accordance with JIS Z 0208-1976. The temperature and humidity conditions were 40 ± 0.5°C and 90 ± 2% relative humidity. The deterioration value of the water vapor transmission rate before and after bending was calculated, and it was evaluated how much the deterioration value was reduced compared to the case where the bend-resistant layer was not provided. Note that the water vapor transmission rate before bending in the case where the bend-resistant layer was not provided (Comparative Example 2) was 25.6 g / m 2 / day, and the water vapor transmission rate after bending was 56.6 g / m 2 / day, and the deterioration value was 31.0 g / m 2 / day.

[0143]

Table 2

[0144] As shown in Table 2, it was found that the functions of the functional layers of the laminates obtained using the bend-resistant agents of Examples 1 to 8 of the present invention were less likely to deteriorate before and after bending.

Claims

1. A laminate in which a paper base layer, a folding-resistant layer, and a functional layer are laminated in this order, The following conditions 1 to 3 are met: A folding-resistant agent for forming the folding-resistant layer (excluding the case where the folding-resistant agent is OKS-1009 and the functional layer is an active energy ray-curable ink composition layer). (Condition 1) The folding resistance agent includes a resin and a medium, the resin includes at least one selected from the group consisting of a polyurethane resin, an acrylic resin, a polyester resin, a polyvinyl alcohol resin, a styrene-butadiene resin, and a vinyl chloride resin; The content of the resin (calculated as solid content) in the folding endurance agent is 70 to 100% by mass. (Condition 2) The degree of elongation of the fold-resistant layer in a tensile test determined by the following formula is 200% or more. Elongation degree (%) = 100 x (Lb-L0) / L0 Here, Lb indicates the gauge length at break, and L0 indicates the gauge length before the tensile test. The tensile test is a tensile test performed in accordance with JIS K 6251. (Condition 3) The shape recovery rate of the folding-resistant layer, calculated by the following formula, is 80% or more. Shape restoration rate (%) = 100 × (L1 - L2) / (L1 - L0) Here, L0 refers to the gauge length before the tensile test. L1 refers to the gauge length at 100% elongation in the tensile test, and for those that cannot be elongated to 100%, it is the limit gauge length at which the material does not break. L2 is the gauge length of the fold-resistant layer when the external force is removed after the tensile test, and the tensile test is a tensile test performed in accordance with JIS K 6251.

2. The folding endurance agent according to claim 1 , wherein the functional layer includes at least one layer selected from the group consisting of a moisture-proof layer, a gas barrier layer, an oil-resistant layer, a water-resistant layer, and a water-repellent layer.

3. A paper base layer, a folding-resistant layer, and a functional layer are laminated in this order, 3. A laminate, wherein the folding-resistant layer is a layer formed by applying the folding-resistant agent according to claim 1 or 2.

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