Laminate

Abstract

This coating material for imparting mineral oil resistance comprises a copolymer of a monomer composition and an aqueous solvent in which the copolymer is dissolved and / or dispersed. The monomer composition contains a nitrile group-containing ethylenically unsaturated monomer and a carboxy group-containing ethylenically unsaturated monomer. The content ratio of the nitrile group-containing ethylenically unsaturated monomer relative to the total amount of the monomer composition is 21% to 70% by mass, inclusive. The content ratio of the carboxy group-containing ethylenically unsaturated monomer relative to the total amount of the monomer composition is 3% to 10% by mass, inclusive.

Description

[Technical Field]

[0001] The present invention relates to a mineral oil resistance imparting coating material and a laminate. [Background technology]

[0002] Mineral oil is contained in various materials. For example, recycled paper contains mineral oil derived from printing ink. Therefore, when recycled paper is used as packaging material, the mineral oil may adhere to and penetrate the packaged item. Therefore, laminating a mineral oil-resistant coating layer on materials containing mineral oil is being considered.

[0003] For example, a cardboard package has been proposed that includes paper contaminated with mineral oil and a barrier layer. In this cardboard package, the barrier layer is obtained from an aqueous polymer dispersion. The aqueous polymer dispersion contains a copolymer. The copolymer is obtained by emulsion polymerization of an alkyl (meth)acrylate, 0.1 to 5 mass % of an acid monomer, 0 to 20 mass % of acrylonitrile, and 0 to 10 mass % of other monomers (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2015-500927 Summary of the Invention [Problem to be solved by the invention]

[0005] In various industrial fields, further improvement in mineral oil resistance is required.

[0006] The present invention relates to a mineral oil resistance-imparting coating material that can impart excellent mineral oil resistance, and a laminate comprising a coating layer of the mineral oil resistance-imparting coating material. [Means for solving the problem]

[0007] The present invention [1] includes a mineral oil resistance-imparting coating material comprising a copolymer of a monomer composition containing a nitrile group-containing unsaturated ethylenic monomer and a carboxy group-containing unsaturated ethylenic monomer, and an aqueous solvent for dissolving and / or dispersing the copolymer, wherein the content of the nitrile group-containing unsaturated ethylenic monomer is 21% by mass or more and 70% by mass or less, and the content of the carboxy group-containing unsaturated ethylenic monomer is 3% by mass or more and 10% by mass or less, relative to the total amount of the monomer composition.

[0008] The present invention [2] includes the mineral oil resistance imparting coating material according to the above [1], wherein the glass transition temperature of the copolymer is from -30°C to 100°C.

[0009] The present invention [3] includes a laminate comprising recycled paper and a coating layer of the mineral oil resistance imparting coating material described in [1] or [2] above, formed on at least one side of the recycled paper. [Effects of the Invention]

[0010] The mineral oil resistance-imparting coating material of the present invention contains a copolymer of a monomer composition containing a nitrile group-containing unsaturated ethylenic monomer and a carboxy group-containing unsaturated ethylenic monomer in a predetermined ratio, and therefore the mineral oil resistance-imparting coating material of the present invention can form a coating layer with excellent mineral oil resistance.

[0011] The laminate of the present invention includes a coating layer of the above-mentioned mineral oil resistance-imparting coating material, and therefore the laminate of the present invention has excellent mineral oil resistance. DETAILED DESCRIPTION OF THE INVENTION

[0012] The mineral oil resistance imparting coating material of the present invention contains a copolymer of a monomer composition and an aqueous solvent that dissolves and / or disperses the copolymer.

[0013] The copolymer of the monomer composition is, for example, a (meth)acrylic polymer, where (meth)acrylic refers to acrylic and / or methacrylic (the same applies hereinafter).

[0014] The monomer composition contains a hard monomer as an essential component. The hard monomer is a monomer whose homopolymer has a relatively high glass transition temperature (calculated by the FOX formula (same applies hereinafter)) (for example, 20°C or higher, preferably 200°C or lower).

[0015] The hard monomer contains a nitrile group-containing unsaturated ethylenic monomer as an essential component, in other words, the monomer composition contains a nitrile group-containing unsaturated ethylenic monomer as an essential component.

[0016] Examples of the nitrile group-containing unsaturated ethylenic monomer include nitrile group-containing vinyl monomers. Examples of the nitrile group-containing vinyl monomer include (meth)acrylonitrile. (Meth)acrylonitrile is acrylonitrile and / or methacrylonitrile. These can be used alone or in combination of two or more. From the viewpoint of mineral oil resistance, the nitrile group-containing unsaturated ethylenic monomer is preferably a nitrile group-containing vinyl monomer, more preferably (meth)acrylonitrile, and even more preferably acrylonitrile.

[0017] The content of the nitrile group-containing unsaturated ethylenic monomer is 21% by mass or more, preferably 24% by mass or more, based on the total amount of the monomer composition. When the content of the nitrile group-containing unsaturated ethylenic monomer is higher than the lower limit, better mineral oil resistance can be obtained.

[0018] The content of the nitrile group-containing unsaturated ethylenic monomer is 70% by mass or less, preferably 65% ​​by mass or less, and more preferably 60% by mass or less, based on the total amount of the monomer composition. When the content of the nitrile group-containing unsaturated ethylenic monomer is below the upper limit, better mineral oil resistance can be obtained.

[0019] In particular, from the viewpoint of mineral oil resistance of the coated surface in an unflexed state, the content of the nitrile group-containing unsaturated ethylenic monomer is more preferably 35% by mass or more, particularly preferably 40% by mass or more, and preferably 60% by mass or less.

[0020] On the other hand, from the viewpoint of blocking resistance and flex resistance (crack resistance when flexed and mineral oil resistance after flexing) of the coated surface, the content of the nitrile group-containing unsaturated ethylenic monomer is more preferably 34% by mass or less, even more preferably 30% by mass or less, and particularly preferably 28% by mass or less. Also, the content of the nitrile group-containing unsaturated ethylenic monomer is preferably 24% by mass or more.

[0021] The content of the nitrile group-containing unsaturated ethylenic monomer relative to the total amount of hard monomers is, for example, 60 mass % or more, preferably 70 mass % or more, and more preferably 80 mass % or more.

[0022] The content of the nitrile group-containing unsaturated ethylenic monomer relative to the total amount of hard monomers is, for example, 100 mass % or less, preferably 95 mass % or less, and more preferably 90 mass % or less.

[0023] The hard monomer may optionally contain a benzene ring-containing unsaturated ethylenic monomer, in other words, the monomer composition may optionally contain a benzene ring-containing unsaturated ethylenic monomer.

[0024] Examples of the benzene ring-containing unsaturated ethylenic monomer include styrene-based vinyl monomers. Examples of the styrene-based vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, and chlorostyrene. These can be used alone or in combination of two or more. Examples of the benzene ring-containing unsaturated ethylenic monomer include preferably styrene-based vinyl monomers, and more preferably styrene.

[0025] When the monomer composition contains a benzene ring-containing unsaturated ethylenic monomer, the content of the benzene ring-containing unsaturated ethylenic monomer relative to the total amount of the monomer composition is, for example, 1 mass% or more, preferably 2 mass% or more, and more preferably 5 mass% or more, from the viewpoint of polymerizability of the nitrile group-containing unsaturated ethylenic monomer.

[0026] Furthermore, when the monomer composition contains a benzene ring-containing unsaturated ethylenic monomer, the content of the benzene ring-containing unsaturated ethylenic monomer relative to the total amount of the monomer composition is, for example, 50 mass% or less, preferably 30 mass% or less, and more preferably 10 mass% or less, from the viewpoint of mineral oil resistance.

[0027] The hard monomer may optionally contain methyl methacrylate, in other words, the monomer composition may optionally contain methyl methacrylate.

[0028] When the monomer composition contains methyl methacrylate, the content of methyl methacrylate relative to the total amount of the monomer composition is, for example, 1 mass% or more, preferably 2 mass% or more, and more preferably 5 mass% or more, from the viewpoint of mineral oil resistance.

[0029] Furthermore, when the monomer composition contains methyl methacrylate, the content of methyl methacrylate relative to the total amount of the monomer composition is, for example, 50 mass% or less, preferably 30 mass% or less, and more preferably 10 mass% or less, from the viewpoint of mineral oil resistance.

[0030] The hard monomer preferably contains a nitrile group-containing unsaturated ethylenic monomer and methyl methacrylate. The hard monomer more preferably consists of a nitrile group-containing unsaturated ethylenic monomer and methyl methacrylate, or the hard monomer preferably consists of a nitrile group-containing unsaturated ethylenic monomer, a benzene ring-containing unsaturated ethylenic monomer and methyl methacrylate.

[0031] From the viewpoint of mineral oil resistance, the content of the hard monomer relative to the total amount of the monomer composition is, for example, 30 mass% or more, preferably 40 mass% or more, more preferably 50 mass% or more, and even more preferably 55 mass% or more.

[0032] The content of the hard monomer relative to the total amount of the monomer composition is, from the viewpoint of film-forming properties, for example, 90 mass % or less, preferably 80 mass % or less, and more preferably 70 mass % or less.

[0033] The monomer composition may also contain a soft monomer as an optional component. The soft monomer is a monomer whose homopolymer has a relatively low glass transition temperature (for example, less than 20° C., preferably 0° C. or lower).

[0034] Examples of soft monomers include alkyl (meth)acrylates other than methyl methacrylate, where (meth)acrylate refers to acrylate and / or methacrylate (the same applies hereinafter).

[0035] Examples of alkyl(meth)acrylates include alkyl(meth)acrylates (excluding methyl methacrylate) having an alkyl moiety with 1 to 30 carbon atoms. More specifically, examples of alkyl(meth)acrylates include methyl acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, s-butyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, neopentyl(meth)acrylate, isoamyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate. Examples of the acrylates include methyl (meth)acrylate, ...

[0036] The alkyl(meth)acrylate is preferably an alkyl(meth)acrylate having an alkyl moiety having 2 to 10 carbon atoms, more preferably butyl(meth)acrylate and 2-ethylhexyl(meth)acrylate, and even more preferably butyl acrylate and 2-ethylhexyl acrylate.

[0037] When the monomer composition contains a soft monomer, the content of the soft monomer relative to the total amount of the monomer composition is, from the viewpoint of film-forming property, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more. That is, from the viewpoint of mineral oil resistance, the monomer composition preferably contains a soft monomer.

[0038] Furthermore, when the monomer composition contains a soft monomer, the content of the soft monomer relative to the total amount of the monomer composition is, for example, 60 mass% or less, preferably 55 mass% or less, and more preferably 50 mass% or less, from the viewpoint of mineral oil resistance.

[0039] The monomer composition also contains a copolymerizable monomer. The copolymerizable monomer is a monomer that can be copolymerized with the hard monomer and / or the soft monomer. The copolymerizable monomer includes an essential copolymerizable monomer and an optional copolymerizable monomer.

[0040] The copolymerizable essential monomer is contained as an essential component in the monomer composition. Examples of the copolymerizable essential monomer include a carboxyl group-containing unsaturated ethylenic monomer. In other words, the monomer composition contains a carboxyl group-containing unsaturated ethylenic monomer as an essential component.

[0041] Examples of carboxyl group-containing unsaturated ethylenic monomers include carboxyl group-containing vinyl monomers. Examples of carboxyl group-containing vinyl monomers include α,β-unsaturated carboxylic acids and their salts. Examples of α,β-unsaturated carboxylic acids include α,β-unsaturated monocarboxylic acids and α,β-unsaturated dicarboxylic acids. Examples of α,β-unsaturated monocarboxylic acids include (meth)acrylic acid and crotonic acid. Examples of α,β-unsaturated dicarboxylic acids include itaconic acid, maleic acid, fumaric acid, itaconic anhydride, maleic anhydride, and fumaric anhydride. Examples of salts include sodium salts, potassium salts, and ammonium salts. These can be used alone or in combination of two or more. From the viewpoint of mineral oil resistance, the carboxyl group-containing unsaturated ethylenic monomer is preferably a carboxyl group-containing vinyl monomer, more preferably an α,β-unsaturated monocarboxylic acid, even more preferably (meth)acrylic acid, and particularly preferably methacrylic acid.

[0042] The content of the carboxyl group-containing unsaturated ethylenic monomer is 3 mass% or more, preferably 4 mass% or more, more preferably 5 mass% or more, based on the total amount of the monomer composition, from the viewpoint of mineral oil resistance. When the content of the carboxyl group-containing unsaturated ethylenic monomer is higher than the lower limit, better film-forming properties and mineral oil resistance can be obtained.

[0043] Furthermore, the content of the carboxyl group-containing unsaturated ethylenic monomer is 10 mass% or less, preferably 8 mass% or less, based on the total amount of the monomer composition, from the viewpoint of mineral oil resistance. If the content of the carboxyl group-containing unsaturated ethylenic monomer is below the upper limit, better film-forming properties and mineral oil resistance can be obtained.

[0044] The optional copolymerizable monomer is a copolymerizable monomer contained in the monomer composition as needed. Examples of the optional copolymerizable monomer include other functional group-containing copolymerizable monomers.

[0045] The other functional group-containing copolymerizable monomer is a functional group-containing copolymerizable monomer other than the carboxy group-containing unsaturated ethylenic monomer. Examples of the other functional group-containing copolymerizable monomer include a hydroxyl group-containing vinyl monomer, an amide group-containing vinyl monomer, a glycidyl group-containing vinyl monomer, an amino group-containing vinyl monomer, an acetoacetoxy group-containing vinyl monomer, a phosphate group-containing vinyl monomer, and a sulfonic acid group-containing vinyl monomer.

[0046] Examples of hydroxyl group-containing vinyl monomers include hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. Examples of amide group-containing vinyl monomers include (meth)acrylamide and methylenebis(meth)acrylamide. Examples of glycidyl group-containing vinyl monomers include glycidyl (meth)acrylate. Examples of amino group-containing vinyl monomers include 2-aminoethyl (meth)acrylate, 2-(N-methylamino)ethyl (meth)acrylate, and 2-(N,N-dimethylamino)ethyl (meth)acrylate. Examples of acetoacetoxy group-containing vinyl monomers include acetoacetoxyethyl (meth)acrylate. Examples of phosphate group-containing vinyl monomers include 2-(meth)acryloxyethyl acid phosphate. Examples of sulfonic acid group-containing vinyl monomers include allyl sulfonic acid, methallyl sulfonic acid, acrylamido t-butyl sulfonic acid, and styrene sulfonate. Examples of salts include sodium salts, potassium salts, and ammonium salts.

[0047] The other functional group-containing copolymerizable monomers can be used alone or in combination of two or more kinds.

[0048] Preferred examples of other functional group-containing copolymerizable monomers include hydroxyl group-containing vinyl monomers, amide group-containing vinyl monomers, and N-substituted unsaturated carboxylic acid amides.

[0049] Further examples of the optional copolymerizable monomer include vinyl esters, N-substituted unsaturated carboxylic acid amides, heterocyclic vinyl compounds, vinylidene halide compounds, α-olefins, dienes, and crosslinkable vinyl monomers.

[0050] Examples of vinyl esters include vinyl acetate and vinyl propionate. Examples of N-substituted unsaturated carboxylic acid amides include N-methylol(meth)acrylamide. Examples of heterocyclic vinyl compounds include vinylpyrrolidone. Examples of halogenated vinylidene compounds include vinylidene chloride and vinylidene fluoride. Examples of α-olefins include ethylene and propylene. Examples of dienes include butadiene. Examples of crosslinkable vinyl monomers include methylenebis(meth)acrylamide, divinylbenzene, polyethylene glycol chain-containing di(meth)acrylate, trimethylolpropane tetraacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate. These can be used alone or in combination of two or more.

[0051] The content of the optional copolymerizable monomer is appropriately determined depending on the purpose and application.

[0052] For example, when the monomer composition contains a hydroxyl group-containing vinyl monomer, the content of the hydroxyl group-containing vinyl monomer relative to the total amount of the monomer composition is, for example, 0.5 mass% or more, preferably 1 mass% or more, and more preferably 5 mass% or more, from the viewpoint of mineral oil resistance.

[0053] Furthermore, for example, when the monomer composition contains a hydroxyl group-containing vinyl monomer, the content of the hydroxyl group-containing vinyl monomer is, for example, 30 mass % or less, preferably 20 mass % or less, and more preferably 10 mass % or less, from the viewpoint of mineral oil resistance.

[0054] Furthermore, for example, when the monomer composition contains an amide group-containing vinyl monomer, the content of the amide group-containing vinyl monomer relative to the total amount of the monomer composition is, from the viewpoint of mineral oil resistance, for example, 0.5 mass% or more, preferably 10 mass% or more, and more preferably 20 mass% or more.

[0055] Furthermore, for example, when the monomer composition contains an amide group-containing vinyl monomer, the content of the amide group-containing vinyl monomer is, for example, 50 mass % or less, preferably 40 mass % or less, and more preferably 30 mass % or less, from the viewpoint of mineral oil resistance.

[0056] Furthermore, for example, when the monomer composition contains N-substituted unsaturated carboxylic acid amides, the content of the N-substituted unsaturated carboxylic acid amides relative to the total amount of the monomer composition is, for example, 0 mass% or more, preferably 0.5 mass% or more, and more preferably 1.0 mass% or more, from the viewpoint of mineral oil resistance.

[0057] Furthermore, for example, when the monomer composition contains N-substituted unsaturated carboxylic acid amides, the content of the N-substituted unsaturated carboxylic acid amides is, for example, 20% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less, from the viewpoint of mineral oil resistance.

[0058] The copolymerizable monomer preferably contains an essential copolymerizable monomer and does not contain an optional copolymerizable monomer. That is, the monomer composition preferably contains a hard monomer, a soft monomer, and an essential copolymerizable monomer. The monomer composition more preferably consists of a hard monomer, a soft monomer, and an essential copolymerizable monomer.

[0059] The copolymer of the monomer composition can be obtained by polymerizing the above-mentioned monomer composition by a known method. More specifically, for example, the monomer composition and a polymerization initiator are mixed in an aqueous solvent, and the monomer composition is polymerized.

[0060] The polymerization initiator is not particularly limited, and examples thereof include water-soluble initiators and oil-soluble initiators. Examples of water-soluble initiators include potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, and organic hydroperoxides. Examples of oil-soluble initiators include benzoyl peroxide and azobisisobutyronitrile. Also, known redox initiators can be used as the polymerization initiator. These can be used alone or in combination of two or more types. The polymerization initiator is preferably a water-soluble initiator, more preferably ammonium persulfate.

[0061] The blending ratio of the polymerization initiator relative to 100 parts by mass of the monomer composition is, for example, 0.01 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.25 parts by mass or more, and for example, 3 parts by mass or less, preferably 2 parts by mass or less.

[0062] Examples of aqueous solvents include water and hydrophilic solvents. Examples of hydrophilic solvents include alcohols, ketones, esters, ethers, ether alcohols, ether alcohol acetates, and nitriles. Examples of alcohols include methanol and ethanol. Examples of ketones include acetone. Examples of esters include ethyl acetate and butyl acetate. Examples of ethers include dioxane and tetrahydrofuran. Examples of ether alcohols include cellosolve and carbitol. Examples of ether alcohol acetates include cellosolve acetate and carbitol acetate. Examples of nitriles include acetonitrile. These can be used alone or in combination of two or more. A preferred aqueous solvent is water.

[0063] When water is used as the aqueous solvent, an emulsifier is preferably blended with the monomer composition, and the monomer composition is emulsion polymerized in water.

[0064] Examples of emulsifiers include anionic surfactants and nonionic surfactants. Examples of anionic surfactants include alkyl sulfate ester salts, aliphatic sulfonates, alkylbenzene sulfonates, and alkyl diphenyl ether sulfonates. Examples of nonionic surfactants include alkyl esters of polyethylene glycol, alkyl phenyl ethers of polyethylene glycol, and alkyl ethers of polyethylene glycol. These can be used alone or in combination of two or more types.

[0065] The blending ratio of the emulsifier is appropriately set depending on the purpose and use. More specifically, the blending ratio of the emulsifier is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, relative to 100 parts by mass of the monomer composition. The blending ratio of the emulsifier is, for example, 2.0 parts by mass or less, preferably 1.8 parts by mass or less, relative to 100 parts by mass of the monomer composition.

[0066] The polymerization conditions are appropriately set depending on the purpose and application. For example, the pressure conditions are normal pressure. The polymerization temperature is, for example, 30°C or higher, preferably 50°C or higher. The polymerization temperature is, for example, 95°C or lower, preferably 85°C or lower. The polymerization time is, for example, 0.5 hours or higher, preferably 1.5 hours or higher. The polymerization time is, for example, 20 hours or shorter, preferably 10 hours or shorter.

[0067] In addition, in the polymerization, known additives can be blended in appropriate proportions from the viewpoint of improving production stability. Examples of additives include pH adjusters, metal ion sequestering agents, molecular weight modifiers, and chain transfer agents. The additives may be added to the monomer composition before polymerization, to the reaction liquid during polymerization, or to the reaction-terminated liquid after polymerization.

[0068] This allows the monomer composition to copolymerize in the aqueous solvent to produce a copolymer of the monomer composition. As a result, a mineral oil-resistant coating material is obtained that contains the aqueous solvent and the copolymer dissolved and / or dispersed in the aqueous solvent. More specifically, when water is used as the aqueous solvent, the mineral oil-resistant coating material is obtained as a resin emulsion in which the copolymer is dispersed in water.

[0069] In the above polymerization, a neutralizing agent is preferably added to the reaction-terminated liquid to adjust the pH. Examples of the neutralizing agent include ammonia. The neutralizing agent is preferably added to the reaction-terminated liquid after polymerization. If necessary, the reaction-terminated liquid is maintained for a predetermined period of time. The pH of the reaction-terminated liquid after adding the neutralizing agent is, for example, 5 or more, preferably 7 or more, and more preferably 8 or more. The pH of the reaction liquid is, for example, 11 or less, and more preferably 10 or less. The copolymer is hydrated in the reaction-terminated liquid by the neutralizing agent, and is swelled and softened.

[0070] In the polymerization, the monomer composition may be polymerized in one step or in multiple steps. For example, core-shell particles can be formed by polymerizing the monomer composition in multiple steps.

[0071] More specifically, a portion of the monomer composition (primary composition) is first polymerized to synthesize a primary polymer, and then the remainder of the monomer composition (secondary composition) is polymerized in the presence of the primary polymer to synthesize a secondary polymer (multi-stage polymerization). This results in core-shell particles of a copolymer comprising a core made of the primary polymer and a shell made of the secondary polymer that coats the primary polymer. The order of reaction of the portion of the monomer composition and the remainder may be reversed.

[0072] A part of the monomer composition (primary composition) preferably contains a nitrile group-containing unsaturated ethylenic monomer, a carboxy group-containing unsaturated ethylenic monomer, and a soft monomer, and the remainder of the monomer composition (secondary composition) preferably contains a functional group-containing copolymerizable monomer.

[0073] The copolymer contains repeating units derived from a nitrile group-containing unsaturated ethylenic monomer and repeating units derived from a carboxy group-containing unsaturated ethylenic monomer.

[0074] In the copolymer, the content of the repeating units derived from the nitrile group-containing unsaturated ethylenic monomer is the same as the content of the nitrile group-containing unsaturated ethylenic monomer in the monomer composition.

[0075] That is, the content of repeating units derived from the nitrile group-containing unsaturated ethylenic monomer is 21% by mass or more, preferably 24% by mass or more, based on the total amount of the copolymer. Furthermore, the content of repeating units derived from the nitrile group-containing unsaturated ethylenic monomer is 70% by mass or less, preferably 65% ​​by mass or less, more preferably 60% by mass or less, based on the total amount of the copolymer. When the content of repeating units derived from the nitrile group-containing unsaturated ethylenic monomer is within the above range, better mineral oil resistance can be obtained.

[0076] In particular, from the viewpoint of mineral oil resistance of the coated surface in an unflexed state, the content of repeating units derived from the nitrile group-containing unsaturated ethylenic monomer is more preferably 35% by mass or more, particularly preferably 40% by mass or more, based on the total amount of the copolymer, and the content of repeating units derived from the nitrile group-containing unsaturated ethylenic monomer is preferably 60% by mass or less, based on the total amount of the copolymer.

[0077] On the other hand, from the viewpoint of blocking resistance and flex resistance (cracking resistance when flexed and mineral oil resistance after flexing) of the coated surface, the content of repeating units derived from nitrile group-containing unsaturated ethylenic monomers is more preferably 34 mass% or less, even more preferably 30 mass% or less, and particularly preferably 28 mass% or less, based on the total amount of the copolymer. Also, the content of repeating units derived from nitrile group-containing unsaturated ethylenic monomers is preferably 24 mass% or more, based on the total amount of the copolymer.

[0078] In addition, the content of the repeating units derived from the carboxyl group-containing unsaturated ethylenic monomer in the copolymer is the same as the content of the carboxyl group-containing unsaturated ethylenic monomer in the monomer composition.

[0079] That is, the content of repeating units derived from the carboxyl group-containing unsaturated ethylenic monomer is 3% by mass or more, preferably 4% by mass or more, and more preferably 5% by mass or more, based on the total amount of the copolymer. Furthermore, the content of repeating units derived from the carboxyl group-containing unsaturated ethylenic monomer is 10% by mass or less, preferably 8% by mass or less, based on the total amount of the copolymer. When the content of repeating units derived from the carboxyl group-containing unsaturated ethylenic monomer is within the above range, better mineral oil resistance can be obtained.

[0080] The weight-average molecular weight of the copolymer is, for example, 5,000 or more, preferably 10,000 or more, and more preferably 30,000 or more. The weight-average molecular weight of the copolymer is, for example, 1,000,000 or less, preferably 800,000 or less, and more preferably 500,000 or less. The weight-average molecular weight is a polystyrene-equivalent molecular weight determined by gel permeation chromatography.

[0081] The copolymer has a glass transition temperature of, for example, -50°C or higher, preferably -30°C or higher, from the viewpoints of mineral oil resistance and blocking resistance of the coated surface. The copolymer has a glass transition temperature of, for example, 200°C or lower, preferably 100°C or lower, more preferably 80°C or lower, from the viewpoints of mineral oil resistance and film-forming properties. The glass transition temperature is calculated using the FOX formula (hereinafter the same).

[0082] In particular, from the viewpoint of mineral oil resistance of the coated surface in an unbent state, the glass transition temperature of the copolymer is more preferably −10° C. or higher, even more preferably 0° C. or higher, still more preferably 10° C. or higher, and particularly preferably 20° C. or higher. The glass transition temperature of the copolymer is preferably 80° C. or lower.

[0083] On the other hand, from the viewpoint of blocking resistance and flex resistance (cracking resistance when flexed and mineral oil resistance after flexing) of the coated surface, the glass transition temperature of the copolymer is more preferably 20° C. or lower, even more preferably 10° C. or lower, still more preferably 0° C. or lower, and particularly preferably −10° C. or lower. The glass transition temperature of the copolymer is preferably −30° C. or higher.

[0084] In the mineral oil resistance-imparting coating material, the solid content concentration of the copolymer is, for example, 3 mass % or more, preferably 5 mass % or more, more preferably 10 mass % or more, and in the mineral oil resistance-imparting coating material, the solid content concentration of the copolymer is, for example, 50 mass % or less, preferably 30 mass % or less.

[0085] In the mineral oil-resistant coating material, the solid content of the copolymer is appropriately adjusted by adding or removing an aqueous solvent, as required.

[0086] Furthermore, the mineral oil resistance-imparting coating material can contain additives in appropriate proportions as needed. Examples of additives include crosslinkers, inorganic pigments, organic pigments, fillers, antioxidants, UV absorbers, thermoplastic resins, thermosetting resins, lubricants, thickeners, wetting agents, antifoaming agents, and pH adjusters. These can be used alone or in combination. Preferred additives include crosslinkers and inorganic pigments.

[0087] Examples of crosslinking agents include isocyanate-based crosslinking agents, carbodiimide-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, and oxazoline-based crosslinking agents. These can be used alone or in combination of two or more. Preferred crosslinking agents include isocyanate-based crosslinking agents and carbodiimide-based crosslinking agents.

[0088] The blending ratio of the crosslinking agent is not particularly limited and is appropriately set depending on the purpose and use. More specifically, the blending ratio of the crosslinking agent is, for example, 1 part by mass or more, preferably 3 parts by mass or more, relative to 100 parts by mass of the total amount of the copolymer. Furthermore, the blending ratio of the crosslinking agent is, for example, 30 parts by mass or less, preferably 20 parts by mass or less, relative to 100 parts by mass of the total amount of the copolymer.

[0089] If the mineral oil resistance imparting coating material contains a crosslinking agent, better mineral oil resistance and film-forming properties can be obtained.

[0090] Examples of inorganic pigments include calcium carbonate, talc, colloidal silica, clay, calcined kaolin, titanium oxide, zinc oxide, aluminum hydroxide, and clay minerals. Examples of clay minerals include montmorillonite, saponite, hectorite, vermiculite, kaolinite, natural mica, and synthetic mica. These can be used alone or in combination of two or more. The blending ratio of inorganic pigments is not particularly limited and can be appropriately determined depending on the purpose and application.

[0091] If the mineral oil-resistant coating material contains an inorganic pigment, better mineral oil resistance can be obtained. Furthermore, if the mineral oil-resistant coating material contains an inorganic pigment, the gloss of the coated surface can be controlled and the heat resistance, water resistance, and gas barrier properties of the coated surface can be improved.

[0092] The mineral oil-resistant coating material contains a copolymer of a monomer composition containing a nitrile group-containing unsaturated ethylenic monomer and a carboxy group-containing unsaturated ethylenic monomer in a predetermined ratio. Therefore, the mineral oil-resistant coating material can form a coating layer with excellent mineral oil resistance. Furthermore, since the mineral oil-resistant coating material uses an aqueous solvent, it can reduce the environmental impact compared to when an organic solvent is used. Additionally, the coating layer formed from the mineral oil-resistant coating material has excellent adhesion to substrates containing mineral oil.

[0093] That is, the mineral oil-resistant coating material can form a mineral oil-resistant layer with excellent adhesion as a coating layer while reducing the environmental impact, and therefore is preferably applied to a substrate containing mineral oil.

[0094] Examples of mineral oils include saturated hydrocarbons derived from petroleum and aromatic hydrocarbons derived from petroleum, and more specific examples of mineral oils include hydrocarbon compounds having 6 to 30 carbon atoms, liquid paraffin, solid paraffin, wax, and vaseline.

[0095] Substrates containing mineral oil include, for example, substrates containing printing ink, and more specifically, recycled paper.

[0096] The thickness of the base material containing mineral oil is not particularly limited and is appropriately set according to the purpose and use.For example, the thickness of the base material containing mineral oil is, for example, 1 μm or more, preferably 3 μm or more.Furthermore, the thickness of the base material containing mineral oil is, for example, 1000 μm or less, preferably 800 μm or less.

[0097] The mineral oil resistance imparting coating material is applied, for example, to one surface of a substrate containing mineral oil, and is dried by heating as necessary.

[0098] The method for applying the mineral oil resistance-imparting coating material is not particularly limited, and any known coating method can be used, such as a gravure coater, a small-diameter gravure coater, a reverse roll coater, a transfer roll coater, a kiss coater, a dip coater, a microgravure coater, a knife coater, an air doctor coater, a blade coater, a rod coater, a squeeze coater, a cast coater, a die coater, a screen printing method, or a spray coating method.

[0099] The drying conditions are not particularly limited and are appropriately set depending on the purpose and application. For example, the drying temperature is 40° C. or higher. The drying temperature is 200° C. or lower. The drying time is appropriately set depending on the purpose and application.

[0100] As a result, a coating layer of the mineral oil resistance imparting coating material is formed on one surface of the base material containing mineral oil.

[0101] The thickness of the coating layer (after drying) is not particularly limited and is appropriately set depending on the purpose and use. For example, the thickness of the coating layer (after drying) is, for example, 1 μm or more, preferably 3 μm or more. In addition, the thickness of the coating layer (after drying) is, for example, 10 μm or less, preferably 8 μm or less.

[0102] As a result of the above, a laminate is obtained which comprises a substrate containing mineral oil and a coating layer of the above-mentioned mineral oil resistance imparting coating material disposed on the surface of the substrate.

[0103] In particular, when recycled paper is selected as the substrate containing mineral oil, a laminate is obtained comprising recycled paper and a coating layer of the above-mentioned mineral oil resistance-imparting coating material placed on one surface of the recycled paper.

[0104] The thickness of the laminate is not particularly limited and is appropriately set depending on the purpose and use. For example, the thickness (total thickness) of the laminate is, for example, 1 μm or more, preferably 3 μm or more. The thickness (total thickness) of the laminate is, for example, 1000 μm or less, preferably 800 μm or less.

[0105] The laminate includes a coating layer of the mineral oil resistance-imparting coating material, and therefore has excellent mineral oil resistance, making it suitable for use as a packaging material.

[0106] More specifically, when a substrate (preferably recycled paper) that does not have the above-mentioned coating layer is used as packaging material, mineral oil may seep onto the surface of the packaging material, and the mineral oil contained in the substrate may adhere to and impregnate the packaged item at the contact point between the packaging material and the packaged item.

[0107] In contrast, in the above laminate, a coating layer of the above mineral oil resistance imparting coating material is formed on at least one side of a substrate (preferably recycled paper) containing mineral oil.

[0108] Therefore, even when the packaging material comes into contact with the packaged item, the coating layer of the mineral oil-resistant coating material can prevent the mineral oil from adhering to and impregnating the packaged item.

[0109] In the above explanation, a coating layer of a mineral oil-resistant coating material is placed on one surface of the recycled paper, but it is also possible to place coating layers of the above-mentioned mineral oil-resistant coating material on both surfaces of the recycled paper.

[0110] In the above description, a coating layer of a mineral oil-resistant coating material is disposed on one or both surfaces of the recycled paper. However, for example, an optional intermediate layer (undercoat layer) may be interposed between the recycled paper and the coating layer. Furthermore, if necessary, a known top coat layer (overcoat layer) may be laminated on the coating layer of the mineral oil-resistant coating material. In such cases, too, the coating layer of the mineral oil-resistant coating material can prevent mineral oil from adhering to and impregnating the packaged item.

[0111] As described above, the mineral oil-resistant coating material and laminate are suitable for use in the field of packaging materials, for example.

[0112] The mineral oil-resistant coating material can also be used as a substitute for a fluorine-containing coating material, for example. In such cases, the mineral oil-resistant coating material can be suitably used in various fields where conventional fluorine-containing coating materials are used. [Example]

[0113] Specific numerical values ​​of blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(numeric values ​​defined as "not more than" or "less than") or lower limit values ​​(numeric values ​​defined as "not less than" or "exceeding") of blending ratios (content ratios), physical property values, parameters, etc. described in the above "Description of the Invention." Furthermore, unless otherwise specified in the following description, "parts" and "%" are based on mass.

[0114] 1. Preparation of coating material with mineral oil resistance Example 1 A separable flask equipped with a stirrer and reflux condenser was charged with 230 g of ion-exchanged water and 1.5 g of sodium dodecyl diphenyl ether disulfonate, and the atmosphere in the flask was purged with nitrogen gas. The flask was then heated to 75°C. 0.5 g of potassium persulfate was then added to the flask and dissolved. The emulsion of the monomer composition was then continuously added to the flask over approximately 5 hours. The emulsion of the monomer composition contained 56 g of acrylonitrile, 5 g of styrene, 5 g of methyl methacrylate, 26 g of n-butyl acrylate, 8 g of methacrylic acid, 0.1 g of n-dodecyl mercaptan, 0.2 g of sodium dodecyl diphenyl ether disulfonate, and 56 g of ion-exchanged water.

[0115] The mixture was then maintained at the above temperature for 4 hours to complete the polymerization. After that, aqueous ammonia was added to the flask to make it alkaline, and the temperature was maintained for 2 hours. This resulted in hydration, swelling, and softening of the copolymer. The flask was then cooled to room temperature, and deionized water was added to the flask. This resulted in a mineral oil-resistant coating material being obtained as a copolymer resin emulsion with a solids concentration of approximately 20% by mass.

[0116] The glass transition temperatures (Tg) of the copolymers were calculated using the following FOX formula (the same applies hereinafter). The glass transition temperatures (Tg) of the copolymers are shown in Table 1 (the same applies hereinafter).

[0117] 1 / Tg=W1 / Tg1+W2 / Tg2++W n / Tg n (1) [wherein Tg is the glass transition temperature of the copolymer (unit: K), Tg i (i=1, 2, . . . n) is the glass transition temperature (unit: K) when monomer i forms a homopolymer, W i (i=1, 2,...n) represents the mass fraction of monomer i in all monomers.]

[0118] Example 2 A separable flask equipped with a stirrer and a reflux condenser was charged with 230 g of ion-exchanged water and 1.5 g of sodium dodecyl sulfate, and the atmosphere in the flask was replaced with nitrogen gas. The flask was then heated to 75°C. 1.0 g of potassium persulfate was then added to the flask and dissolved. The emulsion of the monomer composition was then continuously added to the flask over approximately 5 hours. The emulsion of the monomer composition contained 45 g of acrylonitrile, 10 g of methyl methacrylate, 40 g of n-butyl acrylate, 5 g of methacrylic acid, 0.2 g of sodium dodecyl sulfate, and 56 g of ion-exchanged water.

[0119] Next, after maintaining the temperature for 2 hours, 0.2 g of ammonium persulfate was added, and the temperature was maintained for 2 hours to complete the polymerization. Ammonia water was then added to the flask to make it alkaline, and the temperature was maintained for 3 hours. This resulted in hydration, swelling, and softening of the copolymer. The flask was then cooled to room temperature, and deionized water was added to the flask. This resulted in a mineral oil-resistant coating material being obtained as a copolymer resin emulsion with a solids concentration of approximately 20% by mass.

[0120] Example 3 A separable flask equipped with a stirrer and reflux condenser was charged with 230 g of ion-exchanged water and 1.5 g of sodium dodecyl sulfate, and the atmosphere in the flask was replaced with nitrogen gas. The flask was then heated to 75°C. 1.0 g of potassium persulfate was then added to the flask and dissolved. An emulsion of the monomer composition was then continuously added to the flask over approximately 5 hours. The emulsion of the monomer composition contained 45 g of acrylonitrile, 10 g of methyl methacrylate, 40 g of n-butyl acrylate, 5 g of acrylic acid, 0.2 g of sodium dodecyl sulfate, and 56 g of ion-exchanged water.

[0121] Next, after maintaining the temperature for 2 hours, 0.2 g of ammonium persulfate was added, and the temperature was maintained for 2 hours to complete the polymerization. Ammonia water was then added to the flask to make it alkaline, and the temperature was maintained for 3 hours. This resulted in hydration, swelling, and softening of the copolymer. The flask was then cooled to room temperature, and deionized water was added to the flask. This resulted in a mineral oil-resistant coating material being obtained as a copolymer resin emulsion with a solids concentration of approximately 20% by mass.

[0122] Example 4 A separable flask equipped with a stirrer and a reflux condenser was charged with 230 g of ion-exchanged water and 1.5 g of sodium dodecyl sulfate, and the atmosphere in the flask was replaced with nitrogen gas. The flask was then heated to 75°C. 1.0 g of potassium persulfate was then added to the flask and dissolved. An emulsion of the monomer composition was then continuously added to the flask over approximately 5 hours. The emulsion of the monomer composition contained 24 g of acrylonitrile, 71 g of n-butyl acrylate, 5 g of acrylic acid, 0.2 g of sodium dodecyl sulfate, and 56 g of ion-exchanged water.

[0123] Next, after maintaining the temperature for 2 hours, 0.2 g of ammonium persulfate was added, and the temperature was maintained for 2 hours to complete the polymerization. Ammonia water was then added to the flask to make it alkaline, and the temperature was maintained for 3 hours. This resulted in hydration, swelling, and softening of the copolymer. The flask was then cooled to room temperature, and deionized water was added to the flask. This resulted in a mineral oil-resistant coating material being obtained as a copolymer resin emulsion with a solids concentration of approximately 20% by mass.

[0124] Comparative Example 1 A separable flask equipped with a stirrer and reflux condenser was charged with 170 g of ion-exchanged water and 1.0 g of sodium dodecyl diphenyl ether disulfonate, and the atmosphere in the flask was purged with nitrogen gas. The flask was then heated to 80°C. 0.3 g of sodium persulfate was then added to the flask and dissolved. The emulsion of the monomer composition was then continuously added to the flask over approximately 4 hours. The emulsion of the monomer composition contained 44 g of methyl methacrylate, 55 g of ethyl acrylate, 1 g of acrylic acid, 1.0 g of sodium dodecyl diphenyl ether disulfonate, and 40 g of ion-exchanged water.

[0125] The temperature was then maintained for 4 hours to complete the polymerization. Subsequently, ion-exchanged water and an aqueous ammonium solution were added to the flask, yielding a copolymer resin emulsion with a solids concentration of approximately 30% by mass.

[0126] Comparative Example 2 A separable flask equipped with a stirrer and reflux condenser was charged with 170 g of ion-exchanged water and 1.0 g of sodium dodecyl diphenyl ether disulfonate, and the atmosphere in the flask was purged with nitrogen gas. The flask was then heated to 80°C. 0.3 g of sodium persulfate was then added to the flask and dissolved. An emulsion of the monomer composition was then continuously added to the flask over approximately 4 hours. The emulsion of the monomer composition contained 20 g of acrylonitrile, 24 g of methyl methacrylate, 55 g of ethyl acrylate, 1 g of acrylic acid, 1.0 g of sodium dodecyl diphenyl ether disulfonate, and 40 g of ion-exchanged water.

[0127] The temperature was then maintained for 4 hours to complete the polymerization. Subsequently, ion-exchanged water and an aqueous ammonium solution were added to the flask, yielding a copolymer resin emulsion with a solids concentration of approximately 30% by mass.

[0128] Comparative Example 3 A separable flask equipped with a stirrer and reflux condenser was charged with 57 g of ion-exchanged water and 0.3 g of sodium dodecyl diphenyl ether disulfonate, and the atmosphere inside the flask was purged with nitrogen gas. The flask was then heated to 72°C. 0.3 g of potassium persulfate was then added to the flask and dissolved. The emulsion of the monomer composition was then continuously added to the flask over approximately 4 hours. The emulsion of the monomer composition contained 51 g of methyl methacrylate, 44 g of 2-ethylhexyl acrylate, 2 g of methacrylic acid, 2 g of 2-hydroxyethyl methacrylate, 1 g of acrylamide, 0.1 g of t-dodecyl mercaptan, 0.3 g of sodium dodecyl diphenyl ether disulfonate, and 40 g of ion-exchanged water.

[0129] The temperature was then maintained for 4 hours to complete the polymerization. Subsequently, ion-exchanged water and an aqueous ammonium solution were added to the flask, yielding a copolymer resin emulsion with a solid content of approximately 50% by mass.

[0130] Comparative Example 4 A separable flask equipped with a stirrer and a reflux condenser was charged with 230 g of ion-exchanged water and 1.5 g of sodium dodecyl sulfate, and the atmosphere in the flask was replaced with nitrogen gas. The flask was then heated to 75°C. 1.0 g of potassium persulfate was then added to the flask and dissolved. An emulsion of the monomer composition was then continuously added to the flask over approximately 5 hours. The emulsion of the monomer composition contained 15 g of acrylonitrile, 80 g of n-butyl acrylate, 5 g of acrylic acid, 0.2 g of sodium dodecyl sulfate, and 56 g of ion-exchanged water.

[0131] The mixture was then maintained at the above temperature for 2 hours, after which 0.2 g of ammonium persulfate was added, and the mixture was maintained at the above temperature for 2 hours to complete the polymerization. Ammonia water was then added to the flask to make it alkaline, and the temperature was maintained for 3 hours. This resulted in the hydration, swelling, and softening of the copolymer. The flask was then cooled to room temperature, and deionized water was added to the flask. This resulted in a copolymer resin emulsion with a solids concentration of approximately 20% by mass.

[0132] Comparative Example 5 A separable flask equipped with a stirrer and reflux condenser was charged with 230 g of ion-exchanged water and 1.5 g of sodium dodecyl sulfate, and the atmosphere in the flask was replaced with nitrogen gas. The flask was then heated to 75°C. 1.0 g of potassium persulfate was then added to the flask and dissolved. An emulsion of the monomer composition was then continuously added to the flask over approximately 5 hours. The emulsion of the monomer composition contained 22 g of acrylonitrile, 76 g of n-butyl acrylate, 2 g of acrylic acid, 0.2 g of sodium dodecyl sulfate, and 56 g of ion-exchanged water.

[0133] The mixture was then maintained at the above temperature for 2 hours, after which 0.2 g of ammonium persulfate was added, and the mixture was maintained at the above temperature for 2 hours to complete the polymerization. Ammonia water was then added to the flask to make it alkaline, and the temperature was maintained for 3 hours. This resulted in the hydration, swelling, and softening of the copolymer. The flask was then cooled to room temperature, and deionized water was added to the flask. This resulted in a copolymer resin emulsion with a solids concentration of approximately 20% by mass.

[0134] Example 5 A separable flask equipped with a stirrer and reflux condenser was charged with 80 g of ion-exchanged water and 0.2 g of sodium dodecyl diphenyl ether disulfonate, and the atmosphere in the flask was purged with nitrogen gas. The flask was then heated to 75°C. 0.5 g of ammonium persulfate was then added to the flask and dissolved. An emulsion of the primary composition in the monomer composition was then continuously added to the flask over approximately 6 hours. The emulsion of the primary composition in the monomer composition contained 30 g of acrylonitrile, 30 g of n-butyl acrylate, 2 g of methacrylic acid, 3.3 g of 2-hydroxyethyl methacrylate, 1.3 g of N-methylolacrylamide, 0.2 g of sodium dodecyl diphenyl ether disulfonate, and 40 g of ion-exchanged water.

[0135] The mixture was then maintained at this temperature for 5 hours. The flask was then cooled to room temperature. Ammonia water was then added to the flask to adjust the pH to 8.0, and the non-volatile content was adjusted to approximately 19% with ion-exchanged water. This yielded a dispersion of the primary polymer.

[0136] The primary polymer dispersion was then heated to 75°C. 0.5 parts of ammonium persulfate was then added to the flask. The remaining aqueous solution of the monomer composition was then continuously added to the flask over approximately 2 hours. The remaining aqueous solution of the monomer composition contained 6.7 g of methacrylic acid, 3.3 g of 2-hydroxyethyl methacrylate, 23.3 g of methacrylamide, 82 g of distilled water, and 8 g of 25% aqueous ammonia.

[0137] The polymerization was then completed by maintaining the temperature for 2 hours. This resulted in core-shell particles of a copolymer, each having a core made of a primary polymer and a shell made of a secondary polymer covering the primary polymer. A resin emulsion of the copolymer with a solids concentration of approximately 20% by mass was also obtained, providing a mineral oil-resistant coating material.

[0138] 2.Laminate Recycled paper (product name "OK Prince Fine Eco G100", manufactured by Oji Paper Co., Ltd.) was prepared as a substrate containing mineral oil. A mineral oil-resistant coating material was applied to one surface of the recycled paper to a dry film thickness of 4 μm, and the paper was dried at 90°C. This resulted in a coating layer (4 μm) of the mineral oil-resistant coating material being formed on the recycled paper. In other words, a laminate comprising recycled paper and a coating layer of the mineral oil-resistant coating material was produced.

[0139] 3. Evaluation <Sample> A sample for evaluating a mineral oil-resistant coating material was prepared. Specifically, uncoated paper (product name "Shiratama," manufactured by Oji Paper Co., Ltd.) was prepared. The mineral oil-resistant coating material was applied to one surface of the uncoated paper to a dry film thickness of 4 μm, and then dried at 90°C. This produced a laminate comprising uncoated paper and a coating layer of the mineral oil-resistant coating material as a sample.

[0140] <Adhesion> An adhesive tape (product name: Cellotape (registered trademark) CT405AP-24, manufactured by Nichiban Co., Ltd.) was applied to the coating layer of the mineral oil resistance-imparting coating material of the above sample, and a 2 kg roller was rolled back and forth once. The adhesive tape was then peeled off, and the sample was evaluated according to the following criteria.

[0141] ◯: No peeling of the coating layer was observed, or material destruction of the coating layer was observed. Δ: A part of the coating layer peeled off from the substrate. ×: The entire coating layer peeled off from the substrate.

[0142] <Mineral oil resistance> A drop of mineral oil (hexane or toluene) was dropped onto the coating layer of the mineral oil resistance coating material of each sample, and a rubbing test was performed with a cloth (1 kg load, 50 strokes back and forth). The results were evaluated according to the following criteria.

[0143] ◯: No change in the coating layer was observed. △: Roughness was observed in the coating layer. ×: The coating layer was dissolved.

[0144] The higher the rating of the coating layer in the rubbing test, the more it can suppress the exudation of mineral oil onto the surface of the laminate.

[0145] <Flexibility, mineral oil resistance of coated surface after bending> The above sample was bent once in the valley fold direction. Thereafter, the mineral oil resistance of the sample was evaluated using the same method and criteria as above. The result was used as an evaluation of bending resistance.

[0146] <Blocking resistance> The blocking resistance of the above samples was evaluated by the following method. Two samples (a laminate comprising uncoated paper and a coating layer of a coating material imparting mineral oil resistance) were stacked together, and the surface of the coating layer was brought into contact with the surface of the uncoated paper. This resulted in a sample laminate. The sample laminate was then subjected to a load of 100 g / cm. 2 The sample laminate was then left to stand for 24 hours in an environment of 40°C and 75% RH. Thereafter, the sample laminate was peeled off. The blocking resistance was evaluated according to the following criteria.

[0147] ○: The samples were peeled off without resistance. ×: The samples stuck together and the uncoated paper (substrate) was damaged.

[0148] [Table 1]

[0149] The above invention is provided as an exemplary embodiment of the present invention, but it is merely an example and should not be interpreted as being limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims. [Industrial Applicability]

[0150] The mineral oil-resistant coating material and laminate of the present invention are suitably used in packaging materials.

Claims

[Claim 1] Recycled paper and a coating layer of a mineral oil resistance-imparting coating material formed on at least one side of the recycled paper; Equipped with The mineral oil resistance imparting coating material is a copolymer of a monomer composition containing a nitrile group-containing unsaturated ethylenic monomer and a carboxy group-containing unsaturated ethylenic monomer; an aqueous solvent that dissolves and / or disperses the copolymer; Including, relative to the total amount of the monomer composition the content of the nitrile group-containing unsaturated ethylenic monomer is 21% by mass or more and 70% by mass or less, The laminate has a content of the carboxy group-containing unsaturated ethylenic monomer of 3% by mass or more and 10% by mass or less.

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