Bending resistant material and laminate

Abstract

The present invention provides a bending-resistant agent and a laminate in which various functional layers are provided on a paper substrate, thereby reducing the deterioration of the functional layers before and after bending. [Solution] In a laminate in which a paper substrate layer, a bending-resistant layer, and a functional layer are laminated in this order, a bending-resistant agent is used to form the bending-resistant layer, satisfying the following conditions 1 to 3 (except when the bending-resistant agent is OKS-1009 and the functional layer is an active energy ray curable ink composition layer). (Condition 1) The bending-resistant agent contains a resin and a medium, and the resin content (in terms of solid content) is 70 to 100% by mass of the bending-resistant agent. (Condition 2) The elongation of the bending-resistant layer in tensile tests is 200% or more. (Condition 3) The shape recovery rate of the bending-resistant layer is 80% or higher.

Description

[Technical Field]

[0001] The present invention relates to a bending-resistant agent and a laminate. More specifically, the present invention relates to a bending-resistant agent and a laminate in which various functional layers are provided on a paper substrate, and which reduces the deterioration of the functionality of the functional layers before and after bending. [Background technology]

[0002] In recent years, in response to environmental concerns and the demands of the SDGs (Sustainable Development Goals), there has been a growing need to eliminate plastic and aluminum from food products. In response to these demands, paper packaging materials with barrier properties (moisture resistance) are being considered (for example, Patent Documents 1-2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2002-220494 [Patent Document 2] Japanese Patent Publication No. 2009-155780 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, when packaging materials are manufactured using the paper laminates described in Patent Documents 1 and 2, there is a problem in that the functionality of the functional layer (for example, moisture resistance) deteriorates when the packaging is folded.

[0005] This invention has been made in view of the above-mentioned conventional problems, and aims to provide a bending-resistant agent and a laminate that prevents deterioration of the functionality of the functional layers before and after bending in a laminate in which various functional layers are provided on a paper substrate. [Means for solving the problem]

[0006] As a result of intensive studies to solve the above problems, the present inventors 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 the 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 (however, except when the fold-resistant agent is OKS-1009 and the functional layer is an active energy ray-curable ink composition layer) for forming the fold-resistant layer. (Condition 1) The fold-resistant agent contains a resin and a medium, 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 obtained by the following formula for 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 obtained by the following formula for 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 fold-resistant agent is applied to form a fold-resistant 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 such that the functions of the functional layer are less likely to deteriorate before and after folding.

[0009] (2) The resin-containing bending resistance agent according to (1), wherein the resin contains at least one selected from the group consisting of polyurethane-based resins, acrylic-based resins, polyester-based resins, polyvinyl alcohol-based resins, styrene-butadiene-based resins, vinyl chloride-based resins, ethylene-vinyl acetate copolymer-based resins, and polyolefin-based resins.

[0010] According to such a configuration, the bending resistance agent is applied to form a bending resistance layer containing the above resin between the paper base material and the functional layer in a laminate in which various functional layers are provided on the paper base material. In the obtained laminate, the functions of the functional layer are less likely to deteriorate before and after bending.

[0011] (3) The bending resistance agent according to (1) or (2), wherein the functional layer contains 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.

[0012] According to such a configuration, the bending resistance agent is applied to form a bending 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. In the obtained laminate, the functions (moisture-proof property, gas barrier property, oil resistance, water resistance, or water repellency) of the various functional layers are less likely to deteriorate before and after bending.

[0013] (4) A laminate in which a paper base material layer, a bending resistance layer, and a functional layer are laminated in this order, and the bending resistance layer is a layer formed by applying the bending resistance agent according to any one of (1) to (3).

[0014] According to such a configuration, the functions of the functional layer in the obtained laminate are less likely to deteriorate before and after bending.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a bending resistance agent and a laminate for making it difficult for the functions of the functional layer to deteriorate before and after bending in a laminate in which various functional layers are provided on a paper base material.

Embodiments for Carrying Out the Invention

[0016] <Bending-resistant agent> The bending-resistant agent of one embodiment of the present invention is a bending-resistant agent for forming a bending-resistant layer in a laminate in which a paper substrate layer, a bending-resistant layer, and a functional layer are laminated in this order. However, this excludes cases where the bending-resistant agent is OKS-1009 and the functional layer is an active energy ray curable ink composition layer. The bending-resistant agent satisfies the following conditions 1 to 3. Note that the bending-resistant agent of this embodiment only needs to have a configuration in which the paper substrate layer, the bending-resistant layer, and the functional layer are laminated in this order, and other layers may be provided before, after, or in between. (Condition 1) The bending-resistant agent includes a resin and a medium. The resin content (in terms of solid content) is 70-100% by mass of the bending-resistant agent. (Condition 2) The elongation of the bending-resistant layer in the tensile test, as calculated by the following formula, is 200% or more. Elongation degree (%)=100×(Lb-L0) / L0 However, Lb refers to the gauge length at the time of fracture, and L0 refers to the gauge length before the tensile test. The tensile test is a tensile test conducted in accordance with JIS K 6251. (Condition 3) The shape recovery rate of the bending-resistant layer, as calculated by the following formula, is 80% or higher. Shape restoration degree (%) = 100 × (L1 - L2) / (L1 - L0) However, L0 refers to the gauge length before the tensile test. L1 refers to the gauge length at 100% elongation during the tensile test, or the limit gauge length at which fracture does not occur if elongation to 100% is not possible. L2 refers to the gauge length of the bending-resistant layer after the external force is removed following the tensile test. The tensile test is conducted in accordance with JIS K 6251. Each of these will be explained below.

[0017] (Regarding Condition 1) ·resin The resin is not particularly limited. For example, the resin preferably contains at least one selected from the group consisting of polyurethane resins, acrylic resins, polyester resins, polyvinyl alcohol resins, styrene-butadiene resins, vinyl chloride resins, ethylene-vinyl acetate copolymer resins, and polyolefin resins. From the viewpoint of solid content and viscosity, the resin is more preferably an emulsion of polyurethane resins, acrylic resins, styrene-butadiene resins, vinyl chloride resins, ethylene-vinyl acetate copolymer resins, or polyolefin resins. As a result, the bending-resistant agent is applied to form a bending-resistant layer containing the above resin between the paper substrate and the functional layer in a laminate in which various functional layers are provided on a paper substrate. The resulting laminate is less prone to deterioration of the function of the functional layer before and after bending.

[0018] Polyurethane resins are not particularly limited. For example, polyurethane resins are obtained by reacting a diisocyanate compound with a diol compound and optionally with a chain extender or reaction inhibitor.

[0019] The diisocyanate compounds are not particularly limited. For example, diisocyanate compounds include aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanate compounds such as isophorone diisocyanate and hydrogenated xylylene diisocyanate; and aromatic diisocyanate compounds such as xylylene diisocyanate, α,α,α',α'-tetramethylxylylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0020] The diol compounds are not particularly limited. For example, diol compounds include low molecular weight diols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, and triethylene glycol; and high molecular weight diols such as polyester diol compounds, polyether diol compounds, polycarbonate diol compounds, and polybutadiene glycol compounds.

[0021] Furthermore, polyurethane resins may have various types of skeletons. For example, polyurethane resins include polyether-based polyurethane resins, polyester-based polyurethane resins, polyester-polyether-based polyurethane resins, and polycarbonate-based polyurethane resins.

[0022] Polyester resins are not particularly limited. For example, polyester resins can be obtained by an esterification reaction using a polycarboxylic acid and a polyhydric alcohol as raw material components.

[0023] Polycarboxylic acids are not particularly limited. For example, polycarboxylic acids include 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 their acid anhydrides, etc.

[0024] Polyhydric alcohols are not particularly limited. For example, polyhydric alcohols include glycols and polyhydric alcohols with a valency of three or higher. 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, and 3,3-diethyl-1,5-pentanediol. Examples of polyhydric alcohols with a valency of three or higher include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and dipentaerythritol.

[0025] The acrylic resin is not particularly limited. For example, the acrylic resin may be a polyester-modified acrylic resin, a polyurethane-modified acrylic resin, or a copolymer of vinyl versatate and an acrylic monomer.

[0026] 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.

[0027] The polyvinyl alcohol-based resin preferably has a degree of polymerization of 100 to 5000, and more preferably 500 to 3000. By having the degree of polymerization of the polyvinyl alcohol-based resin within the above range, the bending-resistant agent exhibits excellent film strength and handling suitability.

[0028] The degree of saponification of the polyvinyl alcohol-based resin is preferably 60 mol% or more, and more preferably 75 mol% or more. When the degree of saponification of the polyvinyl alcohol-based resin is within the above range, the bending-resistant agent exhibits excellent film strength and water resistance.

[0029] Polyvinyl alcohol derivatives include polyvinyl alcohol derivatives in which approximately 40 mol% of the hydroxyl groups are acetalized.

[0030] Modified polyvinyl alcohols include polyvinyl alcohol modified products obtained by copolymerizing carboxyl group-containing monomers, amino group-containing monomers, sulfone group-containing monomers, acetoacetyl group-containing monomers, butenediol, etc.

[0031] Polyvinyl alcohol-based resins include POVA, Exceval (both manufactured by Kuraray Co., Ltd.), Gosenol, Nichigo G Polymer (both manufactured by Mitsubishi Chemical Corporation), etc.

[0032] 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.

[0033] Styrene monomers include styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, 4-methoxystyrene, vinyltoluene, and divinylbenzene.

[0034] Other monomers copolymerizable with styrene monomers and butadiene include 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; and carboxyl group-containing monomers such as itaconic acid, maleic acid, and (meth)acrylic acid. The styrene-butadiene resin emulsion is preferably a carboxy(carboxyl group)-modified styrene-butadiene resin emulsion.

[0035] From the viewpoint of improving blocking and leveling properties, styrene-butadiene resin emulsions preferably have a glass transition temperature of -20°C or higher, and more preferably -10°C or higher. The glass transition temperature is determined by differential scanning calorimetry (DSC) and is usually calculated as the midpoint of the temperature range in which the glass transition occurs.

[0036] Examples of styrene-butadiene resin emulsions include Nippol SX1105A, Nippol LX407S12, and Nippol LX435 (all manufactured by Nippon Zeon Co., Ltd.).

[0037] The vinyl chloride resin is not particularly limited. For example, vinyl chloride resins include vinyl chloride homopolymers, copolymers of vinyl chloride with copolymerizable monomers, and graft copolymers obtained by graft copolymerizing vinyl chloride with polymers other than copolymers of vinyl chloride with copolymerizable monomers. Among these, vinyl chloride resins and vinyl chloride resin emulsions are preferred.

[0038] The method for producing vinyl chloride resin is not particularly limited. For example, vinyl chloride resin can be produced by any known method, such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization.

[0039] The monomers copolymerized with vinyl chloride that constitute the copolymer of vinyl chloride and copolymerizable monomers are not particularly limited, as long as they have a reactive double bond in their 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; and N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide.

[0040] Polymers other than vinyl chloride copolymers are not particularly limited, as long as they can graft copolymerize vinyl chloride.

[0041] Examples of polyvinyl chloride resins include Vinibran (manufactured by Nisshin Chemical Industry Co., Ltd.) and Sumikaflex (manufactured by Sumika Chemtex Co., Ltd.).

[0042] The ethylene-vinyl acetate copolymer resin is not particularly limited. For example, the ethylene-vinyl acetate copolymer resin is a resin emulsion obtained by emulsion polymerization of a monomer composition containing ethylene and vinyl acetate monomer. In this case, the mass ratio of ethylene to vinyl acetate monomer (ethylene / vinyl acetate monomer) blended during copolymerization is preferably 10 / 90 to 70 / 30.

[0043] Ethylene-vinyl acetate copolymer resins include Sumikaflex (manufactured by Sumika Chemtex Co., Ltd.), etc.

[0044] The polyolefin resin is not particularly limited. For example, the polyolefin resin is a resin emulsion obtained by dispersing polyethylene resin, polypropylene resin, polybutylene resin, and polyolefin resin obtained by copolymerizing two or more of ethylene, propylene, and butylene in water.

[0045] Furthermore, the polyolefin resin may be a modified polyolefin resin in which amino groups, carboxyl groups, hydroxyl groups, acryloyl groups, or other polymer chains are introduced to the polyolefin chain; an oxidized polyolefin resin in which a portion of the polyolefin chain is oxidized; or a halogenated polyolefin resin in which a portion is treated with a halogen.

[0046] Examples of polyolefin resins include Arrowbase (manufactured by Unitika Ltd.), Chemipearl (manufactured by Mitsui Chemicals, Inc.), and Supercron (manufactured by Nippon Paper Industries Ltd.).

[0047] The resin content (in terms of solid content) in the solids of the bending-resistant agent is not particularly limited. For example, the resin content may be 70% by mass or more, and preferably 80% by mass or more. Alternatively, the resin content may be 100% by mass or less. By keeping the resin content within the above range, the bending-resistant agent can achieve both coating suitability and coating film properties.

[0048] ·Medium The medium is not particularly limited as long as conditions 1 to 3 are met. For example, if the bending resistance agent is aqueous, the medium may be water alone, or it may be an aqueous medium mixed with water and a water-miscible organic solvent. The water-miscible organic solvent is not particularly limited. For example, water-miscible organic solvents include 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.

[0049] Furthermore, if the bending agent is solvent-based, the medium may include alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, n-propanol, butanol, isobutanol, and tert-butanol; aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, and ethylene glycol. Glycol-based solvents such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether, and their esterified products, are preferred, and the esterified products are preferably mainly acetated, such as 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, and propylene glycol monoethyl ether acetate.

[0050] When the bending-resistant agent is solvent-based, the medium is preferably, from an environmental perspective, a mixed solvent of ester-based organic solvents, alcohol-based organic solvents, and ketone-based organic solvents, or a mixed solvent of ester-based organic solvents and alcohol-based organic solvents that is more environmentally friendly.

[0051] The media content is not particularly limited. For example, the media content is preferably 40% by mass or more, and more preferably 45% by mass or more, in the bending-resistant agent. Furthermore, the media content is preferably 80% by mass or less in the bending-resistant agent. By keeping the media content within the above range, the bending-resistant agent can be optimized for storage stability, printability, and coating amount.

[0052] ·Optional ingredients The bending-resistant agent of this embodiment may contain optional components in addition to the above-mentioned resin and medium. The optional components are not particularly limited. For example, optional components include waxes, defoamers, inorganic fillers, mold release agents, thickeners, surface modifiers, surfactants, plasticizers, polymerization inhibitors, UV absorbers, light stabilizers, antioxidants, etc.

[0053] (Regarding condition 2) The bending-resistant agent of this embodiment is a bending-resistant agent for forming a bending-resistant layer in a laminate in which a paper substrate layer, a bending-resistant layer, and a functional layer are laminated in that order.

[0054] Regarding condition 2, the elongation in the tensile test of the bending-resistant layer obtained using the bending-resistant agent of this embodiment is 200% or more. The elongation is expressed by the following formula. Elongation degree (%)=100×(Lb-L0) / L0 However, Lb refers to the gauge length at the time of fracture, and L0 refers to the gauge length before the tensile test. The tensile test is a tensile test conducted in accordance with JIS K 6251.

[0055] The elongation of the bending-resistant layer should be 200% or more, and preferably 250% or more. If the elongation of the bending-resistant layer is less than 200%, the bending-resistant layer has difficulty maintaining the function of the functional layer before and after bending the laminate, and its function tends to deteriorate. In this embodiment, the elongation of the bending-resistant layer can be measured by the following method.

[0056] • Method for measuring the elongation of the bending-resistant layer A bending-resistant agent is applied to any substrate such as glass, dried, and then peeled off to prepare a JIS K 6251 tensile test specimen of type 3, dumbbell shape (film thickness 300 μm). Then, under the following conditions, the elongation when each specimen is pulled to failure is measured using the following testing machine. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation. Stretching speed: 300mm / min Temperature: 23℃ Humidity: 50%

[0057] (Regarding condition 3) Regarding condition 3, the shape recovery rate of the bending-resistant layer is 80% or higher. A shape recovery rate of 80% or higher is sufficient, 90% or higher is preferable, and 95% or higher is more preferable. If the shape recovery rate is less than 80%, the bending-resistant layer will have difficulty maintaining the function of the functional layer.

[0058] In this embodiment, the degree of shape recovery can be evaluated by performing a tensile test in accordance with JIS K 6251. The tensile test for evaluating the degree of shape recovery can be performed under the following conditions using the following testing machine.

[0059] • Method for evaluating the degree of shape recovery of the bending-resistant layer A bending-resistant agent is applied to any substrate such as glass, dried, and peeled off to form a test specimen. Using the obtained test specimen, a JIS K 6251 tensile test, type 3, dumbbell shape (film thickness 300 μm) is prepared. Next, each test specimen is stretched using the testing machine described below under the following conditions and held in that state for 5 minutes. After that, the test specimen is removed from the testing machine and its length is measured after 3 hours. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation. Stretching speed: 50mm / min Temperature: 23℃ Humidity: 50% The degree of shape restoration can be calculated using the following formula. Shape restoration degree (%) = 100 × (L1 - L2) / (L1 - L0) However, L0 refers to the gauge length before the tensile test. L1 refers to the gauge length at 100% elongation during the tensile test, and for materials that cannot be elongated to 100%, it is the gauge length at the limit before fracture. L2 is the gauge length after the tensile test when the external force is removed.

[0060] Returning to the overall explanation of the bending-resistant agent, the laminate to which the bending-resistant agent is applied is a laminate in which the paper base layer, the bending-resistant layer, and the functional layer are laminated in that order.

[0061] (Paper base layer) The paper base layer is not particularly limited. For example, the paper that makes up the paper base layer is not particularly limited. For example, the paper can be any paper that is commonly used and mainly composed of plant-derived pulp, such as bleached or unbleached kraft paper, fine paper, cardboard, liner paper, coated paper, glossy paper, glassine paper, and graphite paper. Among these, it is preferable that the paper is mainly composed of pulp that disperses easily in water due to mechanical disintegration.

[0062] The basis weight and thickness of the paper substrate layer are not particularly limited. For example, the basis weight of the paper substrate layer may be 30 g / m². 2 Preferably, it is 50 g / m 2 It is more preferable that the above is true. Also, the thickness of the paper base material layer is 300 g / m². 2 Preferably, it is 250 g / m². 2 The following is more preferable: When the thickness and basis weight of the paper substrate layer are within the above range, the bending-resistant agent can easily maintain the function of the functional layer.

[0063] (bending resistant layer) The bending-resistant layer is a layer formed by applying the bending-resistant agent of this embodiment.

[0064] The method for applying the bending-resistant agent to the paper substrate is not particularly limited. For example, the application method may involve using a blade coater, bar coater, air knife coater, slit die coater, gravure coater, gravure reverse coater, microgravure coater, gate roll coater, etc.

[0065] The applied bending-resistant agent is dried. The drying method for the bending-resistant agent is not particularly limited. For example, known drying equipment can be used, such as a hot air dryer, infrared dryer, gas burner, or hot plate.

[0066] The thickness of the bending-resistant layer is not particularly limited. For example, the thickness of the bending-resistant layer is preferably 1 μm or more, and more preferably 3 μm or more. Furthermore, the thickness of the bending-resistant layer is preferably 30 μm or less, and more preferably 20 μm or less. By having the thickness of the bending-resistant layer within the above range, the resulting laminate is less likely to experience a decrease in the functionality of the functional layer before and after bending.

[0067] (Functional layer) The functional layer is a layer that imparts various functions to the paper substrate. The laminate of this embodiment includes a bending-resistant layer formed by applying the bending-resistant agent described above. As a result, the functions imparted by the functional layer are less likely to be impaired before and after bending.

[0068] The functional layer is not particularly limited. The functional layer can be appropriately selected depending on the desired application. Specifically, it is preferable that the functional layer includes at least one of the following layers: a moisture-proof layer, a gas barrier layer, an oil-resistant layer, a water-resistant layer, or a water-repellent layer. As a result, the resulting laminate is less likely to experience a decrease in the functionality of the various functional layers (moisture-proof, gas barrier, oil-resistant, water-resistant, or water-repellent) before and after bending.

[0069] • When the functional layer is a moisture barrier. A moisture barrier is provided by applying a moisture barrier coating agent. For example, the moisture barrier coating agent includes an anionic binder resin, an inorganic layered compound, and an aqueous medium.

[0070] The anionic binder resin is not particularly limited. For example, anionic binder resins include styrene-butadiene copolymers, styrene-acrylic copolymers, methacrylate-butadiene copolymers, acrylonitrile-butadiene copolymers, olefin-unsaturated carboxylic acid copolymers, and acrylic ester polymers. Among these, the anionic binder resin is preferably at least one selected from the group consisting of styrene-butadiene copolymers, styrene-acrylic copolymers, and olefin-unsaturated carboxylic acid copolymers, and more preferably an olefin-unsaturated carboxylic acid copolymer, because it has good water resistance, good elongation, and is less prone to cracking of the functional layer due to bending.

[0071] Styrene-butadiene copolymers are copolymers obtained by emulsion polymerization of monomers consisting of aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, and conjugated diene compounds such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, as well as other compounds copolymerizable with these. The aromatic vinyl compound is preferably styrene, etc. The conjugated diene compound is preferably 1,3-butadiene.

[0072] Styrene-acrylic copolymers are copolymers obtained by emulsion polymerization of an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, or chlorostyrene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, or butentricarboxylic acid, an unsaturated polycarboxylic acid alkyl ester having at least one carboxyl group such as monoethyl itaconic acid, monobutyl fumarate, or monobutyl maleate, an unsaturated sulfonic acid monomer or salt such as acrylamidepropanesulfonic acid, sodium sulfoethyl acrylate, or sodium sulfopropyl methacrylate, or other compounds copolymerizable with these. The aromatic vinyl compound is preferably styrene or the like. The unsaturated carboxylic acid monomer, unsaturated sulfonic acid monomer or salt is preferably acrylic acid, methacrylic acid, itaconic acid, or fumaric acid.

[0073] Olefin-unsaturated carboxylic acid copolymers are copolymers obtained by emulsion polymerization of monomers consisting of olefins, particularly α-olefins such as ethylene and propylene, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butentricarboxylic acid, unsaturated polycarboxylic acid alkyl esters having at least one carboxyl group, such as monoethyl itaconic acid, monobutyl fumarate, and monobutyl maleate, unsaturated sulfonic acid monomers or salts thereof, such as acrylamidepropanesulfonic acid, sodium sulfoethyl acrylate, and sodium sulfopropyl methacrylate, and other compounds copolymerizable with these. The olefin is preferably an α-olefin, particularly ethylene. The unsaturated carboxylic acid monomer, unsaturated sulfonic acid monomer or salt thereof is preferably acrylic acid, methacrylic acid, itaconic acid, fumaric acid, etc. As a specific example of an olefin-unsaturated carboxylic acid copolymer, aqueous dispersions of ethylene-acrylic acid copolymer ammonium salts are commercially available as Zaixen AC, Zaixen A, etc. (manufactured by Sumitomo Seika Co., Ltd.) and can be easily obtained and used.

[0074] 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, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to the total solid content of the moisture-proof coating agent. Furthermore, the content of the anionic binder resin is preferably 95% by mass or less, and more preferably 85% by mass or less, relative to the total solid content of the moisture-proof coating agent. By having the content of the anionic binder resin within the above range, the resulting functional layer (moisture-proof layer) can exhibit high moisture resistance.

[0075] The inorganic layered compound is not particularly limited. For example, the inorganic layered compound may be a natural product or a synthetic product, or a mixture thereof. Natural products include smectite-type clay minerals such as montmorillonite, kaolinite (kaolin mineral), pyrophyllite, talc, beidelite, nontronite, saponite, hectorite, souconite, and stevensite, and mica-type 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, and synthetic mica, synthetic hectorite, and synthetic bentonite. Furthermore, 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.

[0076] 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, even 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, and more preferably 2% by mass or more, based on the total solid content in the moisture-proof coating agent. By having the content of the inorganic layered compound within the above range, the resulting functional layer (moisture-proof layer) can exhibit high moisture-proof properties.

[0077] The aqueous medium is not particularly limited. For example, the aqueous medium may be water alone, or it may be 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.

[0078] The moisture-proof coating agent may contain at least one selected from amino acids and cationic resins to further improve moisture resistance. The amino acids and cationic resins are not particularly limited. For example, amino acids include glycine, alanine, leucine, valine, phenylalanine, proline, serine, threonine, lysine, arginine, aspartic acid, glutamic acid, polylysine, polyglutamic acid, polymers of amino acids, and amino acid derivatives. The amino acids may also be copolymers of amino acids. From the viewpoint of superior moisture resistance, the amino acids are preferably copolymers or polymers of amino acids.

[0079] Cationic resins include polyalkylene polyamines, polyamide compounds, polyamidoamine-epihalohydrin or formaldehyde condensation reaction products, polyamine-epihalohydrin or formaldehyde condensation reaction products, polyamidopolyurea-epihalohydrin or formaldehyde condensation reaction products, polyaminepolyurea-epihalohydrin or formaldehyde condensation reaction products, polyamidoaminepolyurea-epihalohydrin or formaldehyde condensation reaction products, polyamidoaminepolyurea compounds, polyaminepolyurea compounds, polyamidoaminepolyurea compounds and polyamidoamine compounds, polyethyleneimine, polyvinylpyridine, amino-modified acrylamide compounds, polyvinylamine, polydiallyldimethylammonium chloride, and the like.

[0080] Moisture-proof coating agents may contain additives as needed. The additives are not particularly limited. Examples of additives include dispersants, surfactants, defoamers, wetting agents, dyes, color adjusters, and thickeners.

[0081] The method for producing a moisture-proof coating agent is not particularly limited. For example, a moisture-proof coating agent can be prepared by mixing an anionic binder resin, an inorganic layered compound, an aqueous medium, and optionally amino acids, a cationic resin, and additives, and stirring and mixing them thoroughly at room temperature.

[0082] 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, and more preferably 5 μm or more. Furthermore, the thickness of the moisture-proof layer is preferably 30 μm or less, and more preferably 20 μm or less. By having the thickness of the moisture-proof layer within the above range, the resulting laminate will have excellent moisture resistance.

[0083] • When the functional layer is a gas barrier layer A gas barrier layer is provided by applying a gas barrier coating agent. For example, the gas barrier coating agent includes an aqueous polymer, an inorganic layered compound, and an aqueous medium.

[0084] The aqueous polymer is not particularly limited. For example, aqueous polymers include polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, polyacrylonitrile resins, polyamide resins, polyester resins, urethane resins, polyacrylic acid and its salts, casein, polyethyleneimine, etc. Among these, the aqueous polymer is preferably fully saponified or partially saponified polyvinyl alcohol, or modified polyvinyl alcohol, as it can impart superior gas barrier properties. Examples of modified polyvinyl alcohols include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol.

[0085] The content of aqueous polymer is not particularly limited. For example, the content of aqueous polymer is preferably 50% by mass or more, and more preferably 70% by mass or more, of the total solid content of the gas barrier coating agent.

[0086] The inorganic layered compound is the same as the inorganic layered compound described above in relation to the moisture barrier layer. From the viewpoint of improving gas barrier properties, the inorganic layered compound is preferably at least one selected from the group consisting of mica, bentonite, and kaolin.

[0087] 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, and more preferably 30 parts by mass or more, per 100 parts by mass of the aqueous polymer of the gas barrier coating agent. Furthermore, the content of the inorganic layered compound is preferably 20 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of the aqueous polymer of the gas barrier coating agent. By having the inorganic layered compound content within the above range, the resulting functional layer (gas barrier layer) exhibits excellent gas barrier properties under high humidity conditions.

[0088] The aqueous medium may consist of water alone, or it may be an aqueous medium that is a mixture of water and a water-miscible organic solvent 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.

[0089] The method for producing a gas barrier coating agent is not particularly limited. For example, a 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 thoroughly at room temperature.

[0090] 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, and more preferably 0.5 μm or more. Furthermore, the thickness of the gas barrier layer is preferably 10 μm or less, and more preferably 5 μm or less. By having the thickness of the gas barrier layer within the above range, the resulting laminate exhibits excellent gas barrier properties.

[0091] • When the functional layer is an oil-resistant layer An oil-resistant layer is provided by applying an oil-resistant coating agent. For example, the oil-resistant coating agent can be an oil-resistant coating agent containing a pigment, styrene-butadiene copolymer and polyvinyl alcohol, and an aqueous medium, or an oil-resistant coating agent containing a styrene-acrylic copolymer, wax, and an aqueous medium.

[0092] This paper describes oil-resistant coating agents containing pigments, styrene-butadiene copolymers, polyvinyl alcohol, and aqueous media.

[0093] The pigment is not particularly limited. For example, pigments include various types such as inorganic pigments and organic pigments. Inorganic pigments include kaolins such as kaolin, structural kaolin, delamikaolin, and calcined kaolin, as well as minerals such as 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, and smectite. Among these, kaolin is preferred because it can impart excellent oil and water resistance. In addition, kaolin provides excellent transparency and gloss when the density of oil-resistant paper is increased.

[0094] When the pigment is kaolin, the average particle size of the kaolin is preferably 0.5 μm or more, and more preferably 1 μm or more. Furthermore, the average particle size of the kaolin is preferably 20 μm or less, and more preferably 10 μm or less. By having the average particle size of the kaolin within the above range, the resulting functional layer (oil-resistant layer) will have excellent oil resistance.

[0095] Organic pigments include polydienes such as polyisoprene, polyneoprene, and polybutadiene; polyalkenes such as polybutene, polyisobutylene, and polypropylene; polymers and copolymers of vinyl monomers such as vinyl acetate, styrene, (meth)acrylic acid, alkyl (meth)acrylate, (meth)acrylamide, and methyl vinyl ether; and dense, hollow, or through-porous particles of polyurethane resins, polyester resins, polyamide resins, urea resins, melamine resins, and benzoguanamine resins.

[0096] The pigment content is not particularly limited. For example, the pigment content is preferably 20% by mass or more, and more preferably 40% by mass or more, of the total solid content of the oil-resistant coating agent. Furthermore, the pigment content is preferably 70% by mass or less, and more preferably 65% ​​by mass or less, of the total solid content of the oil-resistant coating agent. By having the pigment content within the above range, the resulting oil-resistant layer will have excellent oil resistance and water resistance.

[0097] Styrene-butadiene copolymers are incorporated into functional layers to impart excellent water resistance (water repellency). Styrene-butadiene copolymers are obtained by copolymerizing styrene and butadiene as monomers. When a water-insoluble copolymer is used, the copolymer may be used in the form of latex. The styrene-butadiene copolymer in this embodiment is not particularly limited. For example, a styrene-butadiene copolymer is "A6160" commercially available from Asahi Kasei Corporation.

[0098] 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. Furthermore, 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. By having the Tg of the styrene-butadiene copolymer within the above range, the resulting oil-resistant layer can exhibit excellent film-forming ability and excellent water-repellent and oil-resistant properties.

[0099] The average particle size of the styrene-butadiene copolymer is preferably 0.01 μm or larger, and more preferably 0.03 μm or larger. Furthermore, the average particle size of the styrene-butadiene copolymer is preferably 1.0 μm or smaller, and more preferably 0.5 μm or smaller. By having the average particle size of the styrene-butadiene copolymer within the above range, the styrene-butadiene copolymer exhibits excellent water dispersibility.

[0100] The content of styrene-butadiene copolymer is not particularly limited. For example, the content of styrene-butadiene copolymer is preferably 20% by mass or more, and more preferably 25% by mass or more, of the total solid content of the oil-resistant coating agent. Furthermore, the content of styrene-butadiene copolymer is preferably 50% by mass or less, and more preferably 45% by mass or less, of the total solid content of the oil-resistant coating agent. By having the content of styrene-butadiene copolymer within the above range, the oil-resistant coating agent can form an oil-resistant layer on the paper substrate that has excellent water resistance (water repellency) in addition to oil resistance.

[0101] Polyvinyl alcohol is not particularly limited. For example, polyvinyl alcohol can be unmodified fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol, or other polyvinyl alcohol-based resins. Modified polyvinyl alcohols include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol. Among these, unmodified fully saponified polyvinyl alcohol, ethylene-modified polyvinyl alcohol, and carboxy-modified polyvinyl alcohol are preferred because they can impart excellent oil resistance. Furthermore, ethylene-modified polyvinyl alcohol can suppress the thickening of the oil-resistant coating agent. As a result, the oil-resistant coating agent has excellent coating properties. In addition, the resulting oil-resistant layer has a superior surface condition.

[0102] The content of polyvinyl alcohol-based resin is not particularly limited. For example, the content of polyvinyl alcohol-based resin is preferably 0.5% by mass or more, and more preferably 3% by mass or more, of the total solid content of the oil-resistant coating agent. Furthermore, the content of polyvinyl alcohol-based resin is preferably 20% by mass or less, and more preferably 10% by mass or less, of the total solid content of the oil-resistant coating agent. By having a polyvinyl alcohol-based resin content within the above range, the resulting oil-resistant layer can exhibit superior oil resistance. In addition, the polyvinyl alcohol-based resin can suppress the thickening of the oil-resistant coating agent. As a result, the oil-resistant coating agent can suppress the occurrence of coating defects.

[0103] The aqueous medium may consist of water alone, or it may be an aqueous medium that is a mixture of water and a water-miscible organic solvent 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.

[0104] Next, we will describe an oil-resistant coating agent containing a styrene-acrylic copolymer, wax, and an aqueous medium.

[0105] Styrene-acrylic copolymers include styrene and styrene derivatives copolymerized with acrylic acid (methacrylic acid) and alkyl acrylates such as methyl acrylate, ethyl acrylate, and butyl acrylate, as well as alkyl methacrylates such as methyl methacrylate. Preferably, they are styrene-acrylic copolymer emulsions.

[0106] Examples of waxes include paraffin wax, carboxyl group-containing paraffin wax, microcrystalline wax, polyethylene wax, carboxyl group-containing polyethylene wax, polypropylene wax, polyolefin waxes such as ethylene-propylene copolymer wax, candelilla wax, rice wax, montan wax, fatty acids such as stearic acid, fatty acid amides such as stearic acid amide, stearate bisamide, oleic acid amide, palmitic acid amide, and fatty acid metal salts such as zinc stearate and calcium stearate. The wax content is preferably 1.5 to 20% by mass of the total solid content of the oil-resistant coating agent.

[0107] The aqueous medium may consist of water alone, or it may be an aqueous system obtained by mixing water with water-miscible organic solvents such as alcohols (methanol, ethanol, propanol, etc.), polyhydric alcohols (ethylene glycol, propylene glycol, etc. and their alkyl ether derivatives), esters (ethyl formate, methyl acetate, ethyl acetate, etc.), and ketones (acetone, etc.).

[0108] The method for producing an oil-resistant coating agent is not particularly limited. For example, an 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, wax, and an aqueous medium, or by thoroughly stirring and mixing at room temperature.

[0109] 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, and more preferably 3 μm or more. Furthermore, the thickness of the oil-resistant layer is preferably 20 μm or less, and more preferably 10 μm or less. By having the thickness of the oil-resistant layer within the above range, the resulting laminate will have excellent oil resistance.

[0110] • When the functional layer is a water-resistant layer A water-resistant layer is provided by applying a water-resistant coating agent. The water-resistant coating agent is not particularly limited. For example, water-resistant coating agents include styrene-acrylic copolymers, waxes, and water-based media.

[0111] The styrene-acrylic copolymer is not particularly limited. For example, a styrene-acrylic copolymer is a copolymer obtained by copolymerizing styrene and styrene derivatives with acrylic acid (methacrylic acid) and alkyl acrylates such as methyl acrylate, ethyl acrylate, and butyl acrylate, or alkyl methacrylate such as methyl methacrylate. Among these, the styrene-acrylic copolymer is preferably a styrene-acrylic copolymer emulsion.

[0112] The wax is not particularly limited. For example, the wax may be paraffin wax, carboxyl group-containing paraffin wax, microcrystalline wax, polyethylene wax, carboxyl group-containing polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax and other polyolefin waxes, candelilla wax, rice wax, montan wax, fatty acids such as stearic acid, fatty acid amides such as stearic acid amide, stearate bisamide, oleic acid amide, palmitic acid amide, fatty acid metal salts such as zinc stearate and calcium stearate. The wax content is preferably 1.5 to 20% by mass of the total solid content of the water-resistant coating agent.

[0113] The aqueous medium may consist of water alone, or it may be an aqueous system obtained by mixing water with water-miscible organic solvents such as alcohols (methanol, ethanol, propanol, etc.), polyhydric alcohols (ethylene glycol, propylene glycol, etc. and their alkyl ether derivatives), esters (ethyl formate, methyl acetate, ethyl acetate, etc.), and ketones (acetone, etc.).

[0114] The method for producing a water-resistant coating agent is not particularly limited. For example, a water-resistant coating agent can be prepared by mixing a styrene-acrylic copolymer, wax, and an aqueous medium, and stirring and mixing them thoroughly at room temperature.

[0115] 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, and more preferably 3 μm or more. Furthermore, the thickness of the water-resistant layer is preferably 20 μm or less, and more preferably 10 μm or less. By having the thickness of the water-resistant layer within the above range, the resulting laminate will have excellent water resistance.

[0116] • When the functional layer is a water-repellent layer A water-repellent layer is provided by applying a water-repellent coating agent. For example, the water-repellent coating agent includes a water-repellent agent, an aqueous medium, and optionally an inorganic pigment.

[0117] The water repellent is not particularly limited. For example, water repellents include water-based coating agents containing paraffinic hydrocarbons (e.g., Brightone FC-350 manufactured by Sakata Inx Co., Ltd.) and wax-based water repellents (e.g., Celestal 40R manufactured by Lion Specialty Chemicals Co., Ltd.). The water repellent is not limited to paraffinic. The water repellent may also contain modified wax components such as microcrystalline wax, polyethylene wax, or maleated petroleum resin. Furthermore, the wax-based component may also contain rosin-based resin or unsaturated higher alcohols.

[0118] The aqueous medium may consist of water alone, or it may be an aqueous medium that is a mixture of water and a water-miscible organic solvent 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.

[0119] The method for producing a water-repellent coating agent is not particularly limited. For example, a water-repellent coating agent can be prepared by mixing a water-repellent agent and an aqueous medium, and stirring and mixing them thoroughly at room temperature.

[0120] 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, and more preferably 3 μm or more. Furthermore, the thickness of the water-repellent layer is preferably 20 μm or less, and more preferably 10 μm or less. By having the thickness of the water-repellent layer within the above range, the resulting laminate will have excellent water repellency.

[0121] Returning to the explanation of the bending-resistant agent, the bending-resistant agent of this embodiment is applied to a laminate in which various functional layers are provided on a paper substrate, so as to form a bending-resistant layer between the paper substrate and the functional layers. The resulting laminate is less prone to deterioration of the functionality of the functional layers before and after bending.

[0122] <Laminate and method for manufacturing laminate> A laminate according to one embodiment of the present invention is a laminate in which a paper substrate layer, a bending-resistant layer, and a functional layer are laminated in this order. The bending-resistant layer is a layer formed by applying the bending-resistant agent described above.

[0123] The paper substrate layer, bending-resistant layer, and functional layer constituting the laminate are as described above in relation to the embodiment of the bending-resistant agent.

[0124] The method for manufacturing the laminate is not particularly limited. For example, the laminate can be manufactured by applying a bending-resistant 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 bending-resistant agent and functional coating agent may be dried individually after application, or both may be dried together after application.

[0125] The coating amount (in terms of solid content) for the bending-resistant layer is 1 g / m². 2 Preferably, it is 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 30 g / m 2 or less, preferably 20 g / m 2 or less, and more preferably. By the coating amount of the fold-resistant layer being within the above range, the obtained laminate exhibits excellent fold resistance.

[0126] 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, 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, preferably 20 g / m 2 or less, and more preferably. By the coating amount of the moisture-proof coating agent being within the above range, the laminate exhibits excellent moisture-proof property.

[0127] 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, 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, preferably 5 g / m 2 or less, and more preferably. By the coating amount of the gas barrier coating agent being within the above range, the laminate exhibits excellent gas barrier property.

[0128] 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, 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, preferably 10 g / m 2 or less, and more preferably. By the coating amount of the oil-resistant coating agent being within the above range, the laminate exhibits excellent oil resistance.

[0129] If the functional layer is a water-resistant layer, the amount of water-resistant coating agent applied (in terms of solid content) is 1 g / m². 2 Preferably, it is 3 g / m 2 It is more preferable that the above conditions are met. Furthermore, the amount of water-resistant coating agent applied (in terms of solid content) should be 20 g / m². 2 Preferably, it is 10 g / m 2 The following is more preferable: By having the amount of water-resistant coating agent applied within the above range, the laminate exhibits excellent water resistance.

[0130] If the functional layer is a water-repellent layer, the amount of water-repellent coating agent applied (in terms of solid content) is 1 g / m². 2 Preferably, it is 3 g / m 2 It is more preferable that the above conditions are met. Furthermore, the amount of water-repellent coating agent applied (in terms of solid content) should be 20 g / m². 2 Preferably, it is 10 g / m 2 The following is more preferable: When the amount of water-repellent coating agent applied is within the above range, the laminate exhibits excellent water repellency.

[0131] As described above, according to this embodiment, in a laminate in which various functional layers are provided on a paper substrate, a bending-resistant layer to which the above-mentioned bending-resistant agent is applied is formed between the paper substrate and the functional layer. Therefore, the resulting laminate is less prone to deterioration of the functionality of the functional layer before and after bending. [Examples]

[0132] The present invention will be described more specifically below with reference to examples. The present invention is not limited in any way to these examples. Unless otherwise specified, "%" means "mass percent" and "parts" means "parts by mass". Also, the numbers for the quantities of each material in the table are in "parts by mass".

[0133] The raw materials used are listed below. <Paper base material> OK Blizzard (basis weight 70g / m²) 2 (Manufactured by Oji Materia Co., Ltd.)

[0134] <Moisture-proof coating agent> A moisture-proof coating agent was obtained by adding 60.0 parts of an anionic binder (Zychsen A, 25% solids, manufactured by Sumitomo Seika Co., Ltd.) to 25.0 parts of an inorganic layered compound (Somasif ME300B-4T, 8% solids, manufactured by Katakura Coop Agri Co., Ltd.) under stirring, and then adding 2.0 parts of a modified amide resin (Sumirez® Resin SPI-203(50)H, manufactured by Taoka Chemical Industry Co., Ltd.) and 13 parts of deionized water as dispersants and stirring.

[0135] <Oil-resistant coating agent> For the oil-resistant coating, INXKote WB FLEXO FDA GREASE RES AC4551 was used.

[0136] <Bending-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-based resin 1 (OKS-1009, manufactured by Mitsubishi Chemical Corporation) Polyvinyl alcohol-based resin 2 (BVE8049Q, manufactured by Mitsubishi Chemical Corporation) Polyvinyl alcohol-based resin 3 (OKS-8118, manufactured by Mitsubishi Chemical Corporation) Styrene-butadiene resin 1 (Smartex VA-1015, manufactured by Nippon A&L Co., Ltd.) Styrene-butadiene resin 2 (Nipol LX407S12, manufactured by Nippon Zeon Co., Ltd.) Ethylene-vinyl acetate copolymer resin 1 (Sumikaflex S-201HQ, manufactured by Sumika Chemtex Co., Ltd.) Ethylene-vinyl acetate copolymer resin 2 (Sumikaflex SDX-5100, manufactured by Sumika Chemtex Co., Ltd.) Polyolefin resin 1 (Arrowbase SE-1030N, manufactured by Unitika Ltd.) Polyolefin resin 2 (Arrowbase SD-1010, manufactured by Unitika Ltd.)

[0137] <Manufacturing method for bending-resistant materials> 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 (deionized water) to obtain bending-resistant agents 1-3, 8, and 9 to a solid content of 30%. For acrylic resin 2, the undiluted solution was used as bending-resistant agent 4. In addition, polyvinyl alcohol resins 1-3 were dissolved in a solvent (deionized water) to obtain bending-resistant agents 5-7 as 10% solid content solutions. Ethylene-vinyl acetate copolymer resins 1 and 2 were diluted with a medium (deionized water) to a solid content of 30% to obtain bending-resistant agents 10 and 11. Polyolefin resins 1 and 2 were diluted with a medium (deionized water) to a solid content of 30% to obtain bending-resistant agents 12 and 13.

[0138] [Table 1]

[0139] <Example 1> Apply the anti-bending agent 1 to one side of the paper substrate at a rate of 3 g / m² after drying. 2 To achieve this, the coating was applied using a bar coater and then dried with a 60°C dryer to form a bending-resistant layer. Furthermore, an oil-resistant agent was applied on top of that, with a drying rate of 6g / m². 2 After coating with a bar coater, the oil-resistant layer was formed by drying with a 60°C dryer to create the oil-resistant laminate of Example 1.

[0140] <Examples 2-14> Laminates for oil resistance evaluation or moisture resistance evaluation were prepared in the same manner as in Example 1, except that bending-resistant agents 1, 3, 5, 6, 8, 10, and 12 were used for the oil-resistant layer and moisture-proof layer in the combinations shown in Table 2 below.

[0141] <Comparative Examples 1 and 2> On one side of the paper substrate, each functional layer is applied at a dry coating rate of 6 g / m². 2The oil-resistant laminates or moisture-resistant laminates of Comparative Examples 1 and 2 were prepared by applying the coating with a bar coater and then drying it with a 60°C dryer to form an oil-resistant layer.

[0142] <Comparative Examples 3-12> Laminates for oil resistance evaluation or moisture resistance evaluation were prepared in the same manner as in Example 1, except that bending-resistant agents 2, 4, 7, 9, 11, and 13 were used for the oil-resistant layer and moisture-proof layer in the combinations shown in Table 2 below.

[0143] The degree of elongation and shape recovery of the bending-resistant layer were evaluated using the following evaluation method. The results are shown in Table 2.

[0144] Furthermore, the moisture resistance and oil resistance of the resulting laminates were evaluated according to the type of functional layer fabricated. These evaluations were performed before and after the folding process described below. The results are shown in Table 2.

[0145] (Method for measuring the elongation of the bending-resistant layer) A bending-resistant coating was applied to a glass substrate, dried, and then peeled off to prepare a JIS K 6251 tensile test specimen of type 3, dumbbell shape (film thickness 300 μm). Subsequently, the elongation of each specimen was measured under the following conditions using the following testing machine until it broke. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation. Stretching speed: 300mm / min Temperature: 23℃ Humidity: 50% The degree of elongation can be calculated using the following formula. Elongation degree (%)=100×(Lb-L0) / L0 However, Lb refers to the gauge length at the time of fracture, and L0 refers to the gauge length before the tensile test. The tensile test is a tensile test conducted in accordance with JIS K 6251.

[0146] (Method for evaluating the shape recovery degree of bending-resistant materials) The degree of shape recovery was evaluated by performing a tensile test in accordance with JIS K 6251. The tensile test to evaluate the degree of shape recovery was performed under the following conditions using the following testing machine. A bending-resistant agent was applied to a glass substrate, dried, and peeled off to prepare a JIS K 6251 tensile test, type 3, dumbbell-shaped (film thickness 300 μm). Next, each test piece was stretched using the following testing machine under the following conditions and held in that state for 5 minutes. After that, the test piece was removed from the testing machine and its length was measured after 3 hours. Tensile testing machine: AGS-X, manufactured by Shimadzu Corporation. Stretching speed: 50mm / min Temperature: 23℃ Humidity: 50% The degree of shape restoration can be calculated using the following formula. Shape restoration degree (%) = 100 × (L1 - L2) / (L1 - L0) However, L0 refers to the gauge length before the tensile test. L1 refers to the gauge length at 100% elongation during the tensile test, and for materials that cannot be elongated to 100%, it is the gauge length at the limit before fracture. L2 is the gauge length after the tensile test when the external force is removed.

[0147] (Folding method) A 4000g roller was passed over the laminate 10 times at a speed of 30cm / second to create the first fold. The folded laminate was then unfolded, and a second fold was made in the same manner as the first fold, perpendicular to the first fold. The laminate was folded so that the side coated with the coating agent was facing inward.

[0148] (Oil resistance) 0.03 g of salad oil was dropped onto the coated surface of the laminate (on the intersection of the folds in the case of the folded sample). After 90 minutes, the area over which the salad oil had seeped to the back surface was measured, and the reduction in the stained area was evaluated compared to the case without the fold-resistant layer. The stained area in the case without the fold-resistant layer (Comparative Example 1) was 12.4 cm². 2Furthermore, in all examples and comparative examples, there was absolutely no seepage to the back surface when no folds were made in the laminate.

[0149] (Moisture-resistant) The laminate obtained above was subjected to a water vapor transmission rate (WVTR value, g / m³) test in accordance with JIS Z 0208-1976. 2 The water vapor transmission rate ( / day) was measured. The temperature and humidity conditions were 40±0.5℃ and 90±2% relative humidity. The degradation value of the water vapor transmission rate was calculated before and after bending, and the reduction in the degradation value was evaluated compared to the case without the bending-resistant layer. The water vapor transmission rate before bending in the case without the bending-resistant layer (Comparative Example 2) was 25.6 g / m². 2 / day, water vapor transmission rate after folding is 56.6 g / m² 2 The value is / day, and the degradation value is 31.0 g / m². 2 It was / day.

[0150] [Table 2]

[0151] As shown in Table 2, it was found that the laminates obtained using the bending-resistant agents of Examples 1 to 14 of the present invention did not experience a significant decrease in the functionality of the functional layer before and after bending.

Claims

1. In a laminate in which a paper substrate layer, a bending-resistant layer, and a functional layer are laminated in this order, The following conditions 1 to 3 must be met, A bending-resistant agent for forming the bending-resistant layer (except when the bending-resistant agent is OKS-1009 and the functional layer is an active energy ray-curable ink composition layer). (Condition 1) The bending-resistant agent comprises a resin and a medium, The resin content (in terms of solid content) is 70 to 100% by mass of the bending-resistant agent. (Condition 2) The elongation of the aforementioned bending-resistant layer in a tensile test, as determined by the following formula, is 200% or more. Elongation degree (%) = 100 x (Lb-L0) / L0 However, Lb refers to the gauge length at the time of fracture, and L0 refers to the gauge length before the tensile test. The tensile test is a tensile test conducted in accordance with JIS K 6251. (Condition 3) The degree of shape recovery of the aforementioned bending-resistant layer, as determined by the following formula, is 80% or more. Shape recovery degree (%) = 100 × (L1 - L2) / (L1 - L0) However, 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 materials that cannot be elongated to 100%, it is the gauge length at the limit before fracture. L2 is the gauge length of the bending-resistant layer after the external force is removed following the tensile test. The tensile test is conducted in accordance with JIS K 6251.

2. The bending-resistant agent according to claim 1, wherein the resin comprises at least one selected from the group consisting of polyurethane resins, acrylic resins, polyester resins, polyvinyl alcohol resins, styrene-butadiene resins, vinyl chloride resins, ethylene-vinyl acetate copolymer resins, and polyolefin resins.

3. The bending-resistant agent according to claim 1 or 2, 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.

4. The paper base layer, the bending-resistant layer, and the functional layer are laminated in this order. The laminate is a layer formed by applying the bending-resistant agent described in claim 1 or 2 to the bending-resistant layer.

Images