Laminate

Abstract

To provide a laminate having excellent adhesion, density, leveling properties, and heat sealability.SOLUTION: A laminate includes, in this order, a paper substrate including a size agent, a printed layer, and a surface protective layer. The laminate is characterized in that the printed layer includes a binder resin, a surfactant, and a coloring agent; the binder resin includes an acrylic resin (A) and / or a urethane resin (B); and the content of the surfactant is 0.05-20 mass% based on 100 mass% of the printed layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate. [Background technology]

[0002] In recent years, printing has become common on product packages and other packaging materials for decoration and surface protection. Furthermore, the quality of the print, such as the design, aesthetics, and luxurious feel of the printed matter, can stimulate consumer purchasing motivation and is of great industrial value.

[0003] Conventionally, laminated packaging materials using plastic film have mainly been used to construct packages. For example, Patent Document 1 describes an invention related to a laminated packaging material consisting of a substrate, a printing layer, an adhesive layer, and a sealant layer, in which biomass resin is used in the printing layer and the adhesive layer. However, laminated packaging materials use a large amount of plastic film made from petroleum-derived materials, and from the perspectives of reducing plastic, being environmentally friendly, and being carbon-neutral, there is a desire to switch to paper (paper-based packaging materials), and technological developments are being made.

[0004] Patent Document 2 describes a laminate having, in that order, acid-resistant paper, an ink layer, and a polyethylene layer, but makes no mention of the ink layer containing a surfactant, raising concerns that the ink layer may have poor smoothness. Patent Document 3 describes a laminate having, in that order, a paper substrate, a barrier layer, and a heat-seal layer, but makes no mention of the amount of surfactant added to each of the layers, and since the heat-seal layer does not contain a polyethylene resin, there are concerns that the leveling and heat-sealing properties may be poor. Patent Document 4 describes a laminate having a paper substrate, a protective layer, and a heat-sealing layer, but does not specify whether the protective layer is made of a urethane resin, and furthermore, makes no mention of the amount of surfactant added, thereby leaving no mention of adhesion, density, leveling, or heat-sealing strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-051796 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-213111 [Patent Document 3] Patent Publication No. 2021-138434 [Patent Document 4] International Publication No. 2021 / 106926 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a laminate that is excellent in adhesion, density, leveling property, and heat sealability. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using the laminate described below, and have thus achieved the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a laminate excellent in adhesion, density, leveling property, and heat sealability.

[0009] That is, the present invention provides a laminate having, in this order, a paper base material containing a sizing agent, a printing layer, and a surface protective layer, the printing layer contains a binder resin, a surfactant, and a colorant; the binder resin contains an acrylic resin (A) and / or a urethane resin (B), The present invention relates to a laminate, wherein the content of the surfactant is 0.05 to 20% by mass relative to 100% by mass of the printed layer.

[0010] That is, the present invention relates to the laminate, wherein the surfactant comprises at least one selected from the group consisting of acetylene-based compounds, alcohol alkoxylate-based surfactants, silicon-based surfactants, acrylic-based surfactants, and fluorine-based surfactants.

[0011] That is, the present invention relates to the laminate, wherein the total solid content of the acrylic resin (A) and the urethane resin (B) is 75% by mass or more relative to 100% by mass of the solid content of the binder resin.

[0012] That is, the present invention relates to the laminate, wherein the acrylic resin (A) has a weight average molecular weight of 25,000 or more.

[0013] That is, the present invention relates to the laminate, wherein the urethane resin (B) contains at least one selected from the group consisting of a structure derived from a polyester polyol, a structure derived from a polyether polyol, and a structure derived from a polycarbonate polyol.

[0014] That is, the present invention relates to the laminate, wherein the printed layer further contains a hydrocarbon wax.

[0015] That is, the present invention relates to the laminate, wherein the solid mass ratio of the surfactant to the binder resin in the printed layer is 1:99 to 50:50.

[0016] That is, the present invention relates to the laminate, wherein the solid mass ratio of the surfactant to the colorant in the printed layer is 1:99 to 40:60.

[0017] That is, the present invention relates to the laminate, wherein the sizing agent is at least one selected from the group consisting of rosin resin, alkenyl succinate, alkyl ketene dimer, polyvinyl alcohol resin, and starch resin.

[0018] That is, the present invention relates to the laminate, wherein the surface protective layer comprises at least one resin selected from the group consisting of polyolefin resins, cellulose-based resins, acrylic resins (A'), and urethane resins (B').

[0019] That is, the present invention relates to the laminate, wherein the mass ratio of the sizing agent content in the paper substrate per unit area to the surfactant content in the printing layer per unit area is 0.1:99.9 to 50:50.

[0020] That is, the present invention relates to the laminate, which is for use in a packaging container.

[0021] That is, the present invention provides a method for producing a laminate having, in this order, a paper base material containing a sizing agent, a printing layer, and a surface protective layer, the method comprising: a step of printing a printing ink containing a binder resin, a surfactant, and a colorant onto the paper substrate to form the printing layer; the binder resin contains an acrylic resin (A) and / or a urethane resin (B), The present invention relates to a method for producing a laminate, wherein the surfactant is present in an amount of 0.05 to 20% by mass relative to 100% by mass of the printed layer.

[0022] That is, the present invention relates to the method for producing the laminate, wherein the printing ink further contains a solvent, and the solvent contains an alcohol solvent in an amount of 1 to 70 mass % based on the total amount of the solvent in the printing ink. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following describes in detail the embodiments of the present invention, but the following description of the embodiments or requirements is merely an example of how the present invention can be implemented, and the present invention is not limited to these details as long as it does not deviate from the gist of the present invention.

[0024] <Laminate> A laminate having, in this order, a paper base material containing a sizing agent, a printing layer, and a surface protective layer, characterized in that the printing layer contains a binder resin, a surfactant, and a colorant, the binder resin contains an acrylic resin (A) and / or a urethane resin (B), and the content of the surfactant is 0.05 to 20 mass% in 100 mass% of the printing layer. The laminate of the present invention may further include layers other than those described above, such as a barrier layer and a heat seal layer. The use of the laminate is not particularly limited, but it is preferably for use as a packaging material, and more preferably for use as a packaging container formed by molding the laminate into the shape of a container.

[0025] When forming a printed layer on a substrate, the color pigment contained in the ink used to form the printed layer remains largely on the surface of the paper substrate, while the binder resin penetrates into the paper substrate. As a result, the pigment concentration in the surface layer of the printed layer becomes high, and the coating strength of the printed layer tends to decrease. Therefore, by using a paper substrate containing an acrylic resin (A) and / or a urethane resin (B) and a surfactant in the ink, and also containing a sizing agent, excessive penetration of the ink into the paper substrate can be suppressed and the adhesion between the paper substrate and the printing layer can be improved, thereby achieving excellent adhesion, density, leveling properties, and heat sealability.

[0026] The following are suitable examples of the layer structure of the laminate in the present invention, but the present invention is not limited to these examples. In the following examples, " / " indicates the boundary between layers. Paper base material / printing layer / surface protection layer Paper base material / printing layer / anchor layer / surface protection layer Barrier layer / Paper base material / Printing layer / Surface protection layer Barrier layer / paper substrate / printing layer / anchor layer / surface protection layer Heat seal layer / paper base material / printing layer / surface protection layer Heat seal layer / paper base material / printing layer / anchor layer / surface protection layer Heat seal layer / barrier layer / paper base material / printing layer / surface protection layer Heat seal layer / barrier layer / paper base material / printing layer / anchor layer / surface protection layer

[0027] <Paper base material containing sizing agent> The paper base material containing a sizing agent used in the present invention may be produced by any method as long as the sizing agent is contained in the paper base material. For example, the paper base material can be produced by agglutinating a mixture of plant fibers and a sizing agent described below and producing paper, as described in JP-A-2021-075827, or by applying a coating agent containing a sizing agent to the paper base material and removing the volatile components. The content of the sizing agent in 100% by mass of the paper base material including the sizing agent is preferably 0.01 to 5% by mass, more preferably 0.05 to 2% by mass, and even more preferably 0.1 to 1% by mass. When it is in the above range, adhesion, density, leveling property, and heat sealability tend to be improved. The mass ratio of the content of sizing agent in the paper substrate per unit area to the content of surfactant in the printing layer per unit area is preferably 0.1:99.9 to 50:50, more preferably 1:99 to 30:70, even more preferably 5:95 to 20:80, and particularly preferably 7:93 to 15:85. When it is within the above range, adhesion, density, leveling properties, and heat sealability tend to be improved. The mass ratio of the content of the sizing agent in the paper substrate per unit area to the content of the acrylic resin (A) and the urethane resin (B) in the printing layer per unit area is preferably 0.1:99.9 to 30:70, more preferably 0.2:99.8 to 10:90, and even more preferably 0.3:99.7 to 5:95. When it is within the above range, adhesion, density, leveling properties, and heat sealability tend to be improved.

[0028] <Sizing agent> Examples of sizing agents used in the present invention include rosin resins, alkenyl succinates, alkyl ketene dimers, styrene-acrylic copolymer resins, styrene-maleic acid copolymer resins, maleic acid resins, polyvinyl alcohol resins, starch resins, casein resins, vinyl acetate resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, urethane resins, acrylic resins, epoxy resins, polysaccharide esters, and styrene elastomer resins such as styrene-butadiene copolymer resins. These sizing agents may be used alone or in combination of two or more in any proportion. Among these, at least one selected from the group consisting of rosin resins, alkenyl succinates, alkyl ketene dimers, polyvinyl alcohol resins, and starch resins is preferred, with at least one selected from the group consisting of rosin resins, alkenyl succinates, and alkyl ketene dimers being more preferred, and alkyl ketene dimers being even more preferred. The use of these compounds tends to improve adhesion, density, and leveling properties.

[0029] <Coating agent containing sizing agent> The coating agent containing a sizing agent used in the present invention contains a sizing agent and a solvent, and is preferably aqueous from the viewpoint of environmental load. The coating agent containing a sizing agent can be applied by any known method, and can be applied using, for example, a size press machine such as a vertical two-roll size press coater, a horizontal two-roll size press coater, an inclined two-roll size press coater, a gate roll coater, or a rod metering size press.

[0030] <Additives other than sizing agents> The paper base material containing a sizing agent used in the present invention may contain additives other than the sizing agent, for example, known additives such as retention aids such as aluminum sulfate and polyacrylamide, paper strength agents such as urea formaldehyde resin and melamine formaldehyde resin, and fillers such as talc and kaolin.

[0031] <Print layer> The printing layer of the present invention contains a binder resin, a surfactant, and a colorant. The printing layer is formed by printing a printing ink (hereinafter, also referred to as an aqueous ink when the solvent is an aqueous solvent). Either an oil-based ink or an aqueous ink can be used, but from the viewpoints of adhesion, leveling, and density, it is preferable to use an aqueous ink. The printing layer is located between the paper substrate and the surface protective layer, and can be formed by printing an aqueous ink onto the paper substrate using, for example, a gravure printing machine, and the coating amount of the printing layer is 0.1 to 4 g / m. 2 It is preferable that the amount is 1 to 3 g / m 2 It is more preferable that:

[0032] <Binder resin> The binder resin used in the present invention contains an acrylic resin (A) and / or a urethane resin (B). The binder resin may further contain a resin other than the acrylic resin and the urethane resin, such as a polylactic acid resin, a rosin-based resin, a vinyl acetate resin, a styrene-maleic acid copolymer resin, etc. These resins may be used alone or in combination of two or more. The content of the binder resin in the printed layer is preferably 40 to 90% by mass, and more preferably 60 to 80% by mass, based on 100% by mass of the printed layer. When the content is within the above range, adhesion, density, leveling properties, and heat sealability tend to be improved. The solid content of the acrylic resin (A) and the urethane resin (B) in the printing layer is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass to 100% by mass, based on 100% by mass of the binder resin. When the solid content is within the above range, adhesion, concentration, leveling properties, and heat sealability tend to be improved. The solid content of the acrylic resin (A) and the urethane resin (B) in the printed layer is preferably 40 to 90% by mass, and more preferably 60 to 80% by mass, based on 100% by mass of the printed layer. The solid content of the acrylic resin (A) in the printed layer is preferably 40 to 90% by mass, and more preferably 60 to 80% by mass, based on 100% by mass of the printed layer. The solid content of the urethane resin (B) in the printed layer is preferably 40 to 90% by mass, and more preferably 60 to 80% by mass, based on 100% by mass of the printed layer. When the solid content is within the above ranges, adhesion, concentration, leveling properties, and heat sealability tend to be improved.

[0033] <Acrylic resin (A)> The acrylic resin used in the present invention preferably contains an aqueous acrylic resin emulsion (a-1) and / or a water-soluble acrylic resin (a-2), and more preferably contains an aqueous acrylic resin emulsion (a-1) and a water-soluble acrylic resin (a-2). The acid value of the acrylic resin (A) is preferably 5 to 200 mgKOH / g, more preferably 20 to 100 mgKOH / g, and even more preferably 30 to 80 mgKOH / g. When the acid value is 5 mgKOH / g or more, adhesion and heat-sealing properties tend to be good, while when the acid value is 200 mgKOH / g or less, concentration and leveling properties tend to be good. The glass transition temperature of the acrylic resin (A) is preferably -20 to 130°C, more preferably 0 to 50°C. When it is within the above range, adhesion, leveling, and heat-sealing properties are improved. The weight-average molecular weight of the acrylic resin (A) is preferably 25,000 to 600,000. When it is within the above range, adhesion, leveling, and heat-sealing properties tend to be improved. When the acrylic resin (A) is composed of a plurality of components, the acid value, glass transition temperature, and weight average molecular weight were calculated using the following formulas. (Equation 1) Acid value [mgKOH / g] when n types of acrylic resins (A1 to An) are included JPEG2025167017000001.jpg39130 (Formula 2) Glass transition temperature [°C] when n types of acrylic resins (A1 to An) are included JPEG2025167017000002.jpg36170 (Formula 3) Weight average molecular weight when n types of acrylic resin (An) are included JPEG2025167017000003.jpg34170

[0034] <Water-based acrylic resin emulsion (a-1)> The acid value of the aqueous acrylic resin emulsion (a-1) is preferably 5 to 80 mgKOH / g, and more preferably 20 to 60 mgKOH / g. Within the above range, adhesion, concentration, and heat sealability tend to be improved. The glass transition temperature of the aqueous acrylic resin emulsion (a-1) is preferably -20 to 60°C, and more preferably 0 to 40°C. Within the above range, adhesion, leveling, and heat sealability tend to be improved. The weight average molecular weight of the aqueous acrylic resin emulsion (a-1) is preferably 10,000 to 600,000, more preferably 50,000 to 500,000, even more preferably 100,000 to 400,000, and particularly preferably 200,000 to 300,000. Within the above range, adhesion, leveling, and heat sealability tend to be improved. The emulsion particle size of the aqueous acrylic resin emulsion (a-1) is preferably 10 to 300 nm, more preferably 60 to 100 nm. When it is within the above range, the concentration, leveling property, and heat sealability tend to be improved.

[0035] The aqueous acrylic resin emulsion (a-1) is a polymer or copolymer obtained by polymerizing a monomer component mainly composed of (meth)acrylic acid and / or (meth)acrylate, and may be referred to as an aqueous (meth)acrylic resin hereinafter. It is preferably a styrene-acrylic copolymer resin. Here, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid." "(Meth)acrylate" refers to both "acrylate" and "methacrylate."

[0036] Examples of the (meth)acrylate include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, behenyl acrylate, trimethylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; and aromatic (meth)acrylates such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxydiethylene glycol (meth)acrylate. Heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and oxetane (meth)acrylate; alkoxypolyalkylene glycol (meth)acrylates such as methoxypolypropylene glycol (meth)acrylate and ethoxypolyethylene glycol (meth)acrylate; Examples thereof include N-substituted (meth)acrylamides such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, diacetone(meth)acrylamide, and acryloylmorpholine; amino group-containing (meth)acrylates such as N,N-dimethylaminoethyl(meth)acrylate and N,N-diethylaminoethyl(meth)acrylate; and nitriles such as (meth)acrylonitrile.

[0037] In one embodiment, the monomer components constituting the aqueous (meth)acrylic resin may further contain, in addition to (meth)acrylic acid and / or (meth)acrylate, an ethylenically unsaturated monomer other than these monomers. Examples of the ethylenically unsaturated monomer include styrene-based monomers such as styrene and α-methylstyrene, vinyl-based monomers such as vinyl acetate and vinyl chloride, and carboxyl group-containing ethylenically unsaturated monomers such as itaconic acid, maleic acid, fumaric acid, and crotonic acid. Among these, it is preferable to use styrene-based monomers, which make it easier to obtain excellent gloss.

[0038] In one embodiment, the aqueous (meth)acrylic resin may be a copolymer of (meth)acrylic acid and / or (meth)acrylate with a styrene-based monomer. More specifically, the aqueous (meth)acrylic resin may be a copolymer obtained by copolymerization of (meth)acrylic acid, (meth)acrylate, and styrene.

[0039] Although not particularly limited, specific examples of combinations of monomers that constitute the aqueous (meth)acrylic resin include acrylic acid / styrene / n-butyl methacrylate / 2-ethylhexyl acrylate, acrylic acid / methyl methacrylate / 1,4-cyclohexanedimethanol monoacrylate / n-butyl methacrylate / 2-ethylhexyl acrylate, acrylic acid / styrene / n-butyl methacrylate, methacrylic acid / methyl methacrylate / styrene, and acrylic acid / styrene / n-butyl methacrylate / 2-ethylhexyl acrylate.

[0040] The emulsion resin can be prepared according to a method known in the art. For example, the emulsion resin can be prepared by carrying out emulsion polymerization under conditions in which the monomer components are emulsified into micelles and dispersed in water. For example, the emulsion polymerization can be carried out in the presence of ammonium persulfate and sodium metabisulfite. After the emulsion polymerization, a basic compound such as aqueous ammonia can be added to adjust the acid value of the resin, if necessary.

[0041] In one embodiment, the aqueous (meth)acrylic resin may be neutralized to improve its solubility or dispersibility in aqueous solvents. For example, acid groups such as carboxyl groups may be introduced during the synthesis of the resin, and then some or all of these groups may be neutralized to enhance hydrophilicity. Neutralization of the carboxyl groups may be carried out using amines such as triethylamine or other basic compounds.

[0042] The aqueous acrylic resin emulsion (a-1) may be a commercially available product, such as HE-1335, X-436, or QE-1042 manufactured by Seiko PMC Corporation.

[0043] <Water-soluble acrylic resin (a-2)> The acid value of the water-soluble acrylic resin (a-2) is preferably 200 mgKOH / g or less, more preferably 20 to 150 mgKOH / g, and even more preferably 40 to 100 mgKOH / g. When the acid value is within the above range, adhesion, concentration, and heat-sealability tend to be improved. The glass transition temperature of the water-soluble acrylic resin (a-2) is preferably 40 to 130°C, more preferably 60 to 120°C. When the acid value is within the above range, adhesion, leveling, and heat-sealability tend to be improved. The neutralizing agent for the water-soluble acrylic resin (a-2) is preferably ammonia, organic amine, alkali metal hydroxide, etc., and more preferably ammonia. When the above neutralizing agent is used, concentration and leveling tend to be improved. The weight-average molecular weight of the water-soluble acrylic resin (a-2) is preferably 1,500 to 50,000, more preferably 1,500 to 30,000, and even more preferably 1,500 to 8,000. When the content is within the above range, adhesion, leveling, and heat sealing properties tend to be improved.

[0044] The monomers constituting the water-soluble acrylic resin (a-2) can be the same as those in the <aqueous acrylic resin emulsion (a-1)> described in the <acrylic resin (A)>.

[0045] The water-soluble acrylic resin (a-2) used in the present invention may be a commercially available product, such as "Joncryl 67, Joncryl 678, Joncryl 680, Joncryl 819" manufactured by BASF.

[0046] The solid content ratio of the aqueous acrylic resin emulsion (a-1) to the water-soluble acrylic resin (a-2) is preferably 95:5 to 60:40, and more preferably 90:10 to 80:20. When it is in the above range, adhesion, leveling, and heat-sealing properties tend to be improved.

[0047] <Urethane resin (B)> The urethane resin used in the present invention is preferably an aqueous urethane resin, and is obtained by reacting a urethane prepolymer having an isocyanate group at its terminal, which is obtained by reacting polyisocyanate (b-1), polymer polyol (b-2), and compound (b-3) having a carboxyl group and at least two active hydrogen-containing groups in the molecule, with organic diamine (b-4). The acid value of the aqueous urethane resin used in the present invention is preferably 25 to 65 mgKOH / g, and more preferably 25 to 45 mgKOH / g. When it is within the above range, adhesion, concentration, leveling property, and heat sealability are improved. The weight average molecular weight of the aqueous urethane resin is preferably 5,000 to 100,000, and more preferably 10,000 to 70,000, and even more preferably 20,000 to 40,000. When it is within the above range, adhesion, leveling property, and heat sealability are improved. The glass transition temperature of the aqueous urethane resin is preferably -20 to 60°C, and more preferably 0 to 40°C. When it is within the above range, adhesion, leveling property, and heat sealability tend to be improved.

[0048] The polyisocyanate (b-1) used in the aqueous urethane resin of the present invention may be any of various known aromatic, aliphatic, or alicyclic diisocyanates. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylsilyl methyl ether ... Representative examples include methylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate in which the carboxyl groups of dimer acid are converted to isocyanate groups. These can be used alone or in combination of two or more. Isophorone diisocyanate is preferred in terms of reactivity, etc.

[0049] The number average molecular weight of the polymer polyol (b-1) used in the aqueous urethane resin of the present invention is preferably 3,000 or less, i.e., each number average molecular weight of the polymer polyol (b-1) used is preferably 3,000 or less. When the number average molecular weight is within the above range, adhesion is improved. The number average molecular weight is calculated from the hydroxyl value, which is the amount of hydroxyl groups per gram of resin calculated by esterifying or acetylating the hydroxyl groups in the resin and back-titrating the remaining acid with an alkali, converted into mg of potassium hydroxide, according to JIS K0070.

[0050] Examples of the polymer polyol (b-1) include polyester polyol, polyether polyol, polycaprolactone diol, polycarbonate polyol, polyolefin polyol, castor oil polyol, hydrogenated castor oil polyol, dimer diol, and hydrogenated dimer diol, and among these, at least one selected from the group consisting of polyester polyol, polyether polyol, and polycarbonate polyol is preferred, polyester polyol and / or polyether polyol is more preferred, and polyester polyol is even more preferred. When using the above polyol, adhesion, concentration, leveling property, and heat sealability tend to be improved.

[0051] (polyester polyol) The polyester polyol is a dehydration condensate or polymer of at least one selected from the group consisting of 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,4-pentanediol, 3-methyl-1,5-pentanediol, 2,5-hexanediol, 2-methyl-1,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol, and a polycarboxylic acid or a polycarboxylic acid anhydride. For example, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,4-pentanediol, 3-methyl-1,5-pentanediol, 2,5-hexanediol, 2-methyl-1,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol are used. Examples of suitable branched low molecular weight polyols include ethanol, neopentyl glycol, 1,4-pentanediol, 3-methyl-1,5-pentanediol, 2,5-hexanediol, 2-methyl-1,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol, and dehydrated condensates or polymers of polycarboxylic acids such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, trimellitic acid, and pyromellitic acid, or anhydrides thereof. These may be used alone or in combination of two or more. The polyester polyol preferably has a branched structure, and by using the low molecular weight polyols having the branched structure, a branched structure can be introduced into the polyester polyol.

[0052] When the polymer polyol (b-1) contains a polyester polyol, the content of the polyester polyol is preferably 30 to 99 mass%, more preferably 50 to 97 mass%, and even more preferably 80 to 95 mass%, based on 100 mass% of the polymer polyol. When the content is within the above range, adhesion, concentration, and leveling properties tend to be improved.

[0053] (Polyether polyol) Suitable examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, and copolymers thereof. The polyether polyol preferably contains a structural unit derived from polyethylene glycol, and the content of the polyethylene glycol is preferably 0.1 to 25% by mass, more preferably 2 to 15% by mass, and even more preferably 2 to 10% by mass, based on 100% by mass of the polyether polyol.

[0054] (Polycarbonate polyol) The polycarbonate polyol is not limited by the production method or the type of diol constituting the polycarbonate polyol, but a suitable example is a polycondensate obtained by an ester exchange reaction between a diol consisting of alkylene glycol and a carbonate compound. The polycarbonate polyol is preferably an alicyclic and / or aliphatic polycarbonate diol.

[0055] Suitable examples of the diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,10-decanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butynediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, polypropylene glycol, and dipropylene glycol, which can be used alone or in combination of two or more. 3-Methyl-1,5-pentanediol and other polycarbonate polyols having a branched diol structure are preferred. The carbonate compound is not particularly limited, but examples thereof include dialkyl carbonates, diaryl carbonates, and alkylene carbonates. Specific examples of the carbonate compound include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and dibutyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethylene carbonate.

[0056] The active hydrogen-containing group in the aqueous urethane resin of the present invention refers to a group having an active hydrogen, such as a hydroxyl group or an amino group, which reacts with an isocyanate group.

[0057] Examples of the compound (b-3) having a carboxyl group and at least two active hydrogen-containing groups in the molecule used in the aqueous urethane resin of the present invention include dimethylolalkanoic acids such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid; and diamine-type amino acids such as glutamine, asparagine, lysine, diaminopropionic acid, ornithine, diaminobenzoic acid, and diaminobenzenesulfonic acid. These can be used alone or in combination of two or more.

[0058] The organic diamine (b-4) used in the aqueous urethane resin of the present invention is an organic diamine having a hydroxyl group in an amount of 50 to 100% by weight. If the organic diamine having a hydroxyl group is less than 50% by weight, the resolubility in water-alcohol is poor.

[0059] Examples of organic diamines having a hydroxyl group that can be used in the aqueous urethane resin of the present invention include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. These can be used alone or in combination of two or more.

[0060] Examples of organic diamines that do not have hydroxyl groups and are used in the aqueous urethane resin of the present invention include various known diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and dimer diamine, which is obtained by converting the carboxyl groups of dimer acid to amino groups. These can be used alone or in combination of two or more.

[0061] The aqueous urethane resin used in the present invention can be obtained by the acetone method, which uses an organic solvent that is inactive and hydrophilic to isocyanates, or a solventless synthesis method, which does not use any solvent at all. In the present invention, the acetone method was used, which uses an organic solvent to reduce viscosity and enable the synthesis reaction to proceed uniformly and smoothly.

[0062] To obtain a urethane prepolymer having an isocyanate group at its terminal, which is obtained by reacting a polyisocyanate (b-1), a polymer polyol (b-2), and a compound (b-3) having a carboxyl group and at least two active hydrogen-containing groups in the molecule (hereinafter referred to as the prepolymer reaction), the reaction is preferably carried out at 50 to 100°C for 10 minutes to 10 hours. The end point of the reaction is determined by viscosity measurement, NCO peak by IR measurement, NCO% measurement by titration, etc.

[0063] A catalyst can also be used in the prepolymer reaction. Usable catalysts include known metal catalysts and amine catalysts. Metal catalysts include dibutyltin dilaurate, tin octoate, dibutyltin di(2-ethylhexoate), lead 2-ethylhexoate, 2-ethylhexyl titanate, iron 2-ethylhexoate, cobalt 2-ethylhexoate, zinc naphthenate, cobalt naphthenate, and tetra-n-butyltin. Amine catalysts include tertiary amines such as tetramethylbutanediamine. These catalysts are used in an amount of 0.001 to 1 mol % based on the polymer polyol.

[0064] The reaction between the urethane prepolymer and the organic diamine (hereinafter referred to as the chain extension reaction) is preferably carried out for 10 minutes to 10 hours at 30 to 80° C. The end point of the reaction is determined by viscosity measurement, NCO peak by IR measurement, amine value measurement by titration, etc.

[0065] A reaction terminator may be used in the chain extension reaction. Examples of the reaction terminator include dialkylamines such as di-n-butylamine, as well as amines having a hydroxyl group, such as monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri(hydroxymethyl)aminomethane, and 2-amino-2-ethyl-1,3-propanediol. Other examples include monoamine-type amino acids such as glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, and sulfamic acid.

[0066] Examples of basic compounds that neutralize the carboxyl groups incorporated in the aqueous urethane resin used in the present invention include organic amines such as ammonia, monoethylamine, diethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, methyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, N-methylmorpholine, and 2-amino-2-methyl-1-propanol; and inorganic alkalis such as sodium hydroxide and potassium hydroxide. These may be used alone or in combination of two or more types, but from the standpoint of water resistance of printed matter, residual odor, etc., preferred are water-soluble compounds that are highly volatile and easily dissociate when heated, and ammonia is particularly preferred.

[0067] Examples of hydrophilic organic solvents that are inert to isocyanates include ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and amides such as dimethylformamide and N-methylpyrrolidone. However, since aqueous polyurethanes are usually removed by distillation under reduced pressure (solvent removal), and even when used without solvent removal, it is preferable to use a solvent with a boiling point lower than that of water to accelerate the drying rate. Desolvation can be performed, for example, by adding water and a basic compound as a neutralizer to the reaction solution, then increasing the temperature and distilling off the required amount of solvent under normal pressure or reduced pressure. The aqueous urethane resin may be in the form of either an emulsion resin or a water-soluble resin.

[0068] <Coloring agent> The printed layer contains a colorant. The content of the colorant is preferably 1 to 60 mass % of the total mass of the printed layer, and more preferably 30 to 50 mass %. The colorant is preferably a pigment, and either an organic pigment or an inorganic pigment can be used.

[0069] (organic pigments) Specific examples of organic pigments are shown by their CI numbers in the Colour Index International (CI). Preferably, CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Yellow 83, CI Pigment Yellow 14, CI Pigment Orange 64, CI Pigment Orange 38, CI Pigment Orange 34, CI Pigment Orange 13, CI Pigment Yellow 180, CI Pigment Yellow 139, CI Pigment Red 185, CI Pigment Red 122, CI Pigment Red 178, CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, CI Pigment Violet 23, CI Pigment Violet 37, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6, CI Pigment Green 7, and CI Pigment Black 7, which may be used alone or in combination of two or more.

[0070] (inorganic pigments) Examples of inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, aluminum hydroxide, silica, kaolin, clay, talc, aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, titanium oxide, and zinc oxide. Aluminum can be either leafing or non-leafing, with non-leafing being preferred.

[0071] <Additives> The printing layer of the present invention may contain various additives as needed, such as dispersants, surfactants, waxes, leveling agents, antifoaming agents, and film-forming aids. Specifically, various additives may be added, such as surfactants for adjusting the affinity with the substrate, binder resin, colorant, etc., wax resin microparticle dispersions such as polyethylene wax for improving water friction resistance, inorganic microparticles, adhesive resins, and vinyl acetate resins for imparting anti-slip properties, leveling agents for improving leveling properties, antifoaming agents for imparting antifoaming properties, basic compounds such as sodium hydroxide and potassium hydroxide for imparting resolubility, and glycol compounds for imparting film-forming properties.

[0072] <Surfactant> As the surfactant used in the present invention, known surfactants can be used, among which, at least one selected from the group consisting of acetylene surfactant, silicon surfactant, acrylic surfactant, fluorine surfactant and alcohol alkoxylate surfactant is preferred, at least one selected from the group consisting of acetylene surfactant, acrylic surfactant and alcohol alkoxylate surfactant is more preferred, and acetylene surfactant is even more preferred.When using the above-mentioned compound, adhesion, concentration, leveling property and heat sealability tend to improve. The HLB value of the surfactant is preferably in the range of 1 to 17, more preferably in the range of 3 to 10, and even more preferably in the range of 4 to 8. When it is in the above range, the leveling property and alcohol resistance tend to be improved.

[0073] The solid content of the surfactant in the printed layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 10% by mass, even more preferably 0.5 to 7% by mass, and particularly preferably 1 to 5% by mass, based on 100% by mass of the printed layer. When the content is within the above range, adhesion, concentration, leveling properties, and heat sealability are improved. The solid mass ratio of the surfactant to the binder resin in the printing layer is preferably 1:99 to 50:50, more preferably 10:90 to 30:70, and even more preferably 20:80 to 40:60. When it is within the above range, adhesion, concentration, leveling properties, and heat sealability tend to be improved. The solids mass ratio of surfactant to colorant in the printed layer is preferably 1:99 to 40:60, more preferably 3:97 to 30:70, and even more preferably 5:95 to 20:80. When it is within the above range, adhesion, density, leveling properties, and heat sealability tend to be improved.

[0074] <Acetylene-based surfactants> The acetylene surfactant is a nonionic compound having an acetylene group. The acetylene surfactant is more preferably an ethylene oxide adduct. Commercially available acetylene glycol compounds include Olfin E1010 and Olfin E1020 manufactured by Nissin Chemical Industry Co., Ltd., and Surfynol 104, Surfynol 420, Surfynol 440, Surfynol 465, and Surfynol 485 manufactured by Air Products and Chemicals Co., Ltd.

[0075] Examples of commercially available silicone surfactants include BYK-3480 and BYK-3481, examples of commercially available acrylic surfactants include BYK-381 and BYK-3441, examples of commercially available fluorine-based surfactants include Megafac F-552 and Megafac F-572, and examples of commercially available alcohol alkoxylate surfactants include DYNWET800, manufactured by BYK.

[0076] <Wax> The printing layer preferably contains a wax. Examples of wax include amide wax and hydrocarbon wax, and among these, it is more preferable to contain a hydrocarbon wax. The hydrocarbon wax is preferably polyethylene wax. The average particle size of the hydrocarbon wax is preferably 1.5 to 10 μm, and more preferably 2 to 5 μm. When it is in the above range, the adhesion and heat sealability are improved. The hardness (penetration) of the hydrocarbon wax at 25°C specified in JIS K2207 is preferably 15 or less, more preferably 7 or less, even more preferably 3 or less, particularly preferably 1 or less, and preferably 0.01 to 1. When it is in the above range, the adhesion and heat sealability are improved. The density of the hydrocarbon wax at 23°C specified in JIS K7112 (Method B) is 880 to 990 kg / m 3 It is preferable that the density is 900 to 940 kg / m 3 It is more preferable that the melting point is within the above range. When the melting point is within the above range, the adhesion and heat sealability are improved. The melting point of the hydrocarbon wax measured by DSC is preferably 90 to 150°C, and more preferably 100 to 125°C. When the melting point is within the above range, the adhesion and heat sealability tend to be improved. The melting point of the hydrocarbon wax refers to the melting point at the peak top (minimum value) of the endothermic peak in the DSC temperature rise curve.

[0077] The content of the hydrocarbon wax is preferably 0.01 to 10 mass%, more preferably 0.1 to 5 mass%, and even more preferably 0.2 to 0.3 mass%, based on 100 mass% of the total solid content of the printing ink. When it is within the above range, adhesion and heat sealability tend to be improved.

[0078] <Solvents contained in printing ink> The solvent contained in the printing ink is preferably water as the main component, but a polar organic solvent can also be used in addition to water. Specifically, it is preferable to add an alcohol solvent or the like depending on the printing conditions (speed, plate depth, design, drying temperature). The content of the solvent contained in the printing ink is preferably 40 to 80 mass%. Furthermore, the content of the alcohol solvent is preferably 1 to 70 mass% of the total solvent contained in the printing ink, more preferably 10 to 50 mass%, and even more preferably 15 to 35 mass%. When it is within the above range, adhesion, density, and leveling properties tend to be improved. In the present invention, the phrase "the main component is water" means that the content of water is the highest in the solvent.

[0079] Examples of the alcohol solvent include methanol, ethanol, propanol, isopropanol, isobutanol, normal butanol, tert-butanol, hexanol, octanol, and decanol. These may be used alone or in combination.

[0080] <Printing ink manufacturing method> Printing inks can be produced, for example, by dispersing a pigment in an aqueous medium using a disperser with a resin or the like, and then mixing the resulting pigment dispersion with resin, various additives, an organic solvent, and the like. Commonly used dispersers, such as roller mills, ball mills, pebble mills, attritors, and sand mills, can be used. The particle size distribution of the pigment in the pigment dispersion can be adjusted by appropriately adjusting the size of the grinding media in the disperser, the grinding media filling rate, the dispersion treatment time, the discharge speed of the pigment dispersion, the viscosity of the pigment dispersion, and the like. The viscosity of the printing ink at 25°C is preferably 50 mPa·s or more to prevent pigment sedimentation and adequately disperse the pigment, and 300 mPa·s or less to ensure efficient operation during ink production and printing.

[0081] <Method for forming the printing layer> The printing layer can be formed, for example, by printing a printing ink onto a paper substrate containing a sizing agent, followed by removal of the solvent. The printing ink can be diluted with a diluent consisting of water or a water-soluble organic solvent as needed during printing, and then printed onto various substrates. A preferred diluent is a mixed solvent of water and an alcohol solvent, with a mass ratio of 30:70 to 90:10 being desirable from the viewpoints of ink storage stability and drying. As the printing method, gravure printing, flexographic printing, screen printing, and other printing methods can be applied, with gravure printing being preferred.

[0082] (gravure printing) Gravure version In gravure printing, the gravure plate is a cylindrical metal plate on which recesses of each color are created by engraving, etching, or laser. There are no restrictions on the use of engraving or laser, and it can be set arbitrarily to suit the pattern. Lines per inch of 80 to 250 lines are used appropriately, with the higher the line count, the finer the printing. The thickness of the printing layer is preferably 0.1 μm to 100 μm.

[0083] Gravure printing machine In a gravure printing press, one printing unit is equipped with the gravure plate and doctor blade. There are multiple printing units, and printing units can be set up to handle organic solvent-based printing inks and pattern inks, and each unit has an oven drying unit. Printing is carried out by rotary printing using a web printing method. The type of plate and doctor blade can be selected appropriately to suit the specifications.

[0084] <Surface protective layer> The surface protective layer used in the present invention can be formed from known resins, such as styrene resins, maleic acid resins, urethane resins (B'), polylactic acid resins, polyvinylpyrrolidone resins, starch resins, cellulose-based resins, polyolefin-based resins, and acrylic resins (A'). Among these, it is preferable to include at least one resin selected from the group consisting of polyolefin-based resins, cellulose-based resins, acrylic resins (A'), and urethane resins (B'), and it is more preferable to include a polyolefin-based resin. When using the above resins, the method for forming the surface protective layer is not particularly limited, but it can be formed by coating a heated and melted resin or by applying a coating agent in which the resin is dissolved or dispersed in a solvent or the like. The above resins can be used alone or in combination of two or more. The thickness of the surface protective layer is preferably 1 to 30 μm, more preferably 5 to 15 μm. The resin content of the surface protective layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, based on 100% by mass of the surface protective layer. When it is within the above range, the heat sealability tends to be good.

[0085] (Polyolefin resin) Examples of the polyolefin resin contained in the surface protective layer include polyethylene resins and polypropylene resins, and among these, polyethylene resins are preferred from the viewpoint of heat sealing properties. The polyethylene resin may be an ethylene homopolymer or copolymer, or may be a copolymer with other monomers such as vinyl acetate, and may have ionic properties. Among these, at least one resin selected from the group consisting of polyethylene resin, ethylene-vinyl acetate copolymer resin, and ethylene ionomer resin is preferred, polyethylene resin and / or ethylene-vinyl acetate copolymer resin is more preferred, and polyethylene resin is even more preferred.

[0086] (Acrylic resin (A')) The acrylic resin (A') contained in the surface protective layer can be the same as the acrylic resin (A) described in the printing layer.

[0087] (Urethane resin (B')) The urethane resin (B') contained in the surface protective layer can be the same as the urethane resin (B) described in the printing layer.

[0088] (cellulose-based resin) The cellulose-based resin is preferably a cellulose ester resin. Cellulose ester resins are resins obtained by esterifying cellulose derived from non-edible plants such as wood fiber and cotton, and examples thereof include cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and nitrocellulose. Of the cellulose ester resins, nitrocellulose is preferred from the viewpoint of heat resistance.

[0089] The viscosity of the cellulose-based resin, measured in accordance with JIS K 6703-1995, preferably satisfies any one of the following (1) to (3): The viscosity is the time it takes for a steel ball to fall into an isopropanol solution of the cellulose-based resin (steel ball falling time (seconds)). (1) The viscosity at a solution concentration of 12.2% is 1.5 to 16 seconds. (2) The viscosity at a solution concentration of 20.0% is 3.0 to 40 seconds. (3) The viscosity at a solution concentration of 25.0% is 0.1 to 22 seconds. In particular, the viscosity of the cellulose-based resin preferably satisfies the above requirement (3). In the above requirement (3), the viscosity at a solution concentration of 25.0% is preferably 0.5 to 15 seconds, more preferably 0.5 to 9 seconds.

[0090] The weight average molecular weight (Mw) of the cellulose-based resin is preferably 5,000 to 200,000, more preferably 10,000 to 100,000, and even more preferably 10,000 to 80,000.The glass transition temperature of the cellulose-based resin is preferably 80°C to 160°C.

[0091] <Anchor layer> The laminate of the present invention may further have an anchor layer, which is located between the printing layer and the surface protective layer. The method for forming the anchor layer is not particularly limited, but it can be formed by printing an imine-based anchor coating agent, a butadiene-based anchor coating agent, an isocyanate-based anchor coating agent, or the like using a known printing method such as gravure printing. The coating amount of the anchor layer is 0.1 to 3 g / m 2 It is preferable that:

[0092] <Heat seal layer> The laminate of the present invention may further have a heat seal layer, which is located on the paper substrate on the side opposite to the side having the printing layer. The method for forming the heat seal layer is not particularly limited, but it can be formed by coating a heat-melted resin or by applying a coating agent in which a resin is dissolved and dispersed in a solvent or the like. For example, the heat seal layer can be formed by printing a heat seal agent on the surface of the paper substrate opposite the printed layer, and then drying to remove the volatile components. In this case, gravure printing or flexographic printing is suitable as the printing method. For example, in gravure printing, the resin is diluted with a diluting solvent to an appropriate viscosity and concentration as needed, and supplied to each printing unit either alone or in a mixture, and then applied. The coating is then fixed by drying in an oven to obtain a heat seal layer. Alternatively, the heat seal layer can be formed by applying a molten resin.

[0093] The heat seal layer preferably contains a polyolefin resin and / or an acrylic resin. The polyolefin resin may be a homopolymer or copolymer of ethylene, propylene, butadiene, hexene, or the like, or may be a copolymer with other monomers such as vinyl acetate, and may be ionic. Among these, at least one selected from the group consisting of an ethylene-vinyl acetate copolymer resin, an acrylic resin, and an ethylene-based ionomer resin is preferred, and an ethylene-vinyl acetate copolymer resin and / or an ethylene-based ionomer resin is more preferred. In addition to the above, the heat seal layer may contain urethane resin, polyethylene resin, polypropylene resin, etc. These may be used alone or in combination of two or more. The thickness of the heat seal layer is 1 to 30 μm, and preferably 5 to 20 μm.

[0094] <Barrier layer> The laminate of the present invention may further include a barrier layer, which is preferably disposed on the opposite side of the paper substrate from the printed layer. The method for forming the barrier layer is not particularly limited, and an inorganic compound layer can be formed on the paper substrate by known methods such as vacuum deposition and sputtering. Alternatively, the barrier layer can be applied to the paper substrate by using the above-described metallized paper. The barrier layer preferably contains an inorganic compound such as aluminum, alumina, or silica. The purity of the inorganic compound is preferably 99% by mass or more, more preferably 99.9% by mass or more. [Example]

[0095] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples and various modifications are possible. In the present invention, "parts" and "%" represent parts by mass and % by mass unless otherwise noted.

[0096] <Hydroxyl value> The hydroxyl value is the number of milligrams of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of a sample is acetylated, and was measured by the method described in JIS K 0070.

[0097] <Acid value> The acid value is the number of milligrams of potassium hydroxide required to neutralize the free fatty acids, resin acids, etc. contained in 1 g of sample, and was measured by the method described in JIS K 0070.

[0098] <Amine value> The amine value is the amount of potassium hydroxide (mg) equivalent to the amount of hydrochloric acid required to neutralize the amino groups in 1 g of sample, and was measured according to JIS K 0070. 0.5 to 2 g of sample was precisely weighed (sample solids: 5 g), and 50 mL of a 60 / 40 (mass ratio) methanol / methyl ethyl ketone solution was added to dissolve the sample. Bromophenol blue was added as an indicator to the resulting solution, and the resulting solution was titrated with 0.2 mol / L ethanolic hydrochloric acid solution (titer: 5). The point at which the solution color changed from green to yellow was set as the endpoint, and the titer (A mL) at this point was used to calculate the amine value according to the following equation (4). (Formula 4) Amine value = (A × f × 0.2 × 56.108) / S [mgKOH / g]

[0099] <Mass average molecular weight> The weight average molecular weight was determined by measuring the molecular weight distribution using a gel permeation chromatography (GPC) device (HLC-8220 manufactured by Tosoh Corporation) and calculating the molecular weight converted using polystyrene as a standard substance. The measurement conditions are shown below. Columns: The following columns were used in series. Tosoh Corporation TSKgel Super AW2500 Tosoh Corporation TSKgel Super AW3000 Tosoh Corporation TSKgel Super AW4000 Tosoh TSK Gelguard Column Super AWH Detector: RI (differential refractometer) Measurement conditions: Column temperature 40°C Eluent: tetrahydrofuran Flow rate: 1.0mL / min

[0100] <Glass transition temperature (Tg)> The glass transition temperature was determined by differential scanning calorimetry (DSC). Measurements were performed using a Rigaku DSC8231 at a temperature range of -70 to 250°C and a heating rate of 10°C / min. The midpoint (inflection point) of the baseline shift due to the glass transition in the DSC curve was taken as the glass transition temperature.

[0101] <Measurement of the thickness of the printed layer> Five 10 cm square pieces were cut out from a sample in which a printed layer was formed on a paper substrate, and five 10 cm square pieces were cut out from a sample containing only the paper substrate. The mass of each sample was measured, and the mass per unit area of ​​the printed layer was calculated using the following formula (5). The paper substrate used was paper substrate K1, which contains a sizing agent as described below. (Formula 5) Mass per unit area of ​​printed layer [g / m 2 ] = (average mass of 5 samples of paper substrate / printed layer) - (average mass of 5 samples of paper substrate)

[0102] <Synthesis Example 1> Synthesis of aqueous urethane resin PU1 solution In a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 178.2 parts of poly(3-methyl-1,5-pentane adipate)diol having a number average molecular weight of 2000, 18.2 parts of polyethylene glycol having a number average molecular weight of 2000, 33.4 parts of dimethylol butanoic acid, and 116.5 parts of isophorone diisocyanate were reacted at the boiling point in 200 parts of methyl ethyl ketone for 6 hours while introducing nitrogen gas to obtain a terminal isocyanate prepolymer. The mixture was then cooled to 40°C, and 100 parts of acetone was added to obtain a solvent solution of the terminal isocyanate prepolymer. Next, 646.3 parts of the resulting terminal isocyanate prepolymer solution was gradually added at room temperature to a mixture of 16.3 parts of 2-hydroxyethylethylenediamine and 400 parts of acetone, and the mixture was reacted at 50°C for 3 hours to obtain a solvent-based urethane resin solution. Next, 9.76 parts of 28% aqueous ammonia and 500 parts of deionized water were gradually added to the solvent-based polyurethane resin solution to neutralize it and make it water-soluble. The methyl ethyl ketone and acetone were then all removed by azeotropy, and water was added to adjust the viscosity, yielding an aqueous urethane resin PU1 solution (solids content 40%). The aqueous urethane resin PU1 has an acid value of 30 mg KOH / g, a glass transition temperature of -40°C, and a weight-average molecular weight of 22,000, and contains structural units derived from polyester polyol.

[0103] <Synthesis Example 2> Synthesis of aqueous urethane resin PU2 solution In a reactor equipped with a thermometer, stirrer, reflux condenser, and nitrogen gas inlet tube, 146.19 parts of polytetramethylene glycol having a number average molecular weight of 2000, 35.55 parts of polyethylene glycol having a number average molecular weight of 2000, 21.57 parts of 2,2-dimethylolpropionic acid, and 84.07 parts of isophorone diisocyanate were reacted at the boiling point in 200 parts of methyl ethyl ketone for 6 hours while introducing nitrogen gas to obtain a terminal isocyanate prepolymer. The mixture was then cooled to 40°C, and 100 parts of acetone was added to obtain a terminal isocyanate prepolymer solution. Next, 587.38 parts of the resulting terminal isocyanate prepolymer solution was gradually added at room temperature to a mixture of 8.73 parts of 2-hydroxyethylethylenediamine, 2.91 parts of isophoronediamine, and 400 parts of acetone, and the mixture was reacted at 50°C for 3 hours to obtain a solvent-based polyurethane resin solution. Next, 9.76 parts of 28% aqueous ammonia and 450 parts of deionized water were gradually added to the solvent-based polyurethane resin solution to neutralize it and make it water-soluble. The methyl ethyl ketone and acetone were then all removed by distillation under azeotropy, and water was added to adjust the viscosity, yielding an aqueous polyurethane resin PU2 solution (solids content 40%). The aqueous polyurethane resin PU2 is an aqueous urethane resin with an acid value of 30 mg KOH / g, a glass transition temperature of 25°C, and a weight-average molecular weight of 30,000, and contains structural units derived from polyether polyol.

[0104] <Synthesis Example 3> Synthesis of aqueous urethane resin PU3 solution In a reactor equipped with a thermometer, stirrer, reflux condenser, and nitrogen gas inlet tube, 235.6 parts of a polycarbonate diol having a number average molecular weight of 2000 composed of 1,6-hexanediol-derived units, 10.7 parts of polyethylene glycol having a number average molecular weight of 2000, 30.0 parts of 2,2-dimethylolpropanoic acid, and 250 parts of methyl ethyl ketone were mixed and stirred. 91.5 parts of isophorone diisocyanate was added dropwise over 1 hour, and the mixture was allowed to react at 80°C for 4 hours to form a terminal isocyanate prepolymer. The mixture was then cooled to 30°C and 100 parts of isopropanol was added to obtain a solvent solution of the terminal isocyanate prepolymer. A mixture of 2.7 parts of 2-aminoethylethanolamine and 150 parts of isopropanol was slowly added to the resulting terminal isocyanate prepolymer at room temperature, and the mixture was allowed to react at 40°C for 2 hours to obtain a solvent-based urethane resin solution. Next, 13.6 parts of 28% aqueous ammonia and 851 parts of ion-exchanged water were gradually added to the solvent-based urethane resin solution to neutralize and solubilize it, and the methyl ethyl ketone and isopropanol were then distilled off under reduced pressure, followed by adding water to adjust the solids content, yielding an aqueous urethane resin PU3 solution (solids content 40%). The aqueous urethane resin PU3 is an aqueous urethane resin with an acid value of 35 mg KOH / g, a glass transition temperature of -15°C, and a weight-average molecular weight of 35,000, and contains structural units derived from polycarbonate polyol.

[0105] <Synthesis Example 4> Synthesis of aqueous urethane resin PU4 solution In a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 29.7 parts of dimethylolbutanoic acid, 156.4 parts of polyethylene glycol with a number average molecular weight of 2000, and 67 parts of alcohol-modified dicyclopentadiene polymer hydride (number average molecular weight 610, hydroxyl value 200 mg KOH / g) were mixed and stirred while introducing nitrogen gas. 121.95 parts of isophorone diisocyanate was added dropwise over 1 hour, and the mixture was allowed to react at 80 ° C for 4 hours to form a terminal isocyanate prepolymer. The mixture was then cooled to 30 ° C to obtain a terminal isocyanate prepolymer. A mixture of 550 parts of water, 85 parts of isopropyl alcohol, 20.25 parts of triethylamine, and 26.3 parts of adipic acid hydrazide was slowly added at room temperature to the resulting terminal isocyanate prepolymer, and the mixture was allowed to react at 40 ° C for 2 hours to obtain an aqueous urethane resin solution PU4 solution (solids content 40%). The aqueous urethane resin solution PU4 is an aqueous urethane resin having an acid value of 30 mgKOH / g, a glass transition temperature of −20° C., and a weight average molecular weight of 40,000, and has structural units derived from polyolefin polyol.

[0106] <Production Example 1> Production of printing ink W1 Phthalocyanine blue pigment (Toyo Color Co., Ltd., Lionol Blue FG-7400G (CI Pigment Blue 15:4, solids 100%) 10 parts, water 13.5 parts, aqueous acrylic resin emulsion AC1 50 parts (weight average molecular weight 240,000, acid value 51 mg KOH / g, glass transition temperature: 30 ° C, solids 40%), water-soluble acrylic resin solution AC3 10 parts (weight average molecular weight 5,000, acid value: 50 mg KOH / g, glass transition temperature: 110 ° C, solids 40%), isopropyl alcohol 15 parts, acetylene surfactant (solids 100%, HLB value = 6) 1 part, polyethylene wax (particle size (Coulter counter method): 3 μm, hardness (penetration): 1 or less, solids 40%) 0.5 parts, silicone antifoaming agent (solids 100%) 0.01 parts of each of the above ingredients were mixed and dispersed in a bead mill for 15 minutes to obtain printing ink W1.

[0107] <Production Examples 2 to 33, Comparative Production Examples 1 to 5> Production of printing inks W2 to W38 Printing inks W2 to 32 were obtained in the same manner as in Production Example 1, except that the raw materials and blending ratios shown in Tables 1 and 2 were used. The properties of the raw materials used are as follows: Water-based acrylic resin emulsion AC2 (weight average molecular weight 250,000, acid value 35 mg KOH / g, glass transition temperature: 25°C, solid content 40%) Water-soluble acrylic resin solution AC4 (weight average molecular weight 6000, acid value 80 mg KOH / g, glass transition temperature: 100°C, solid content 40%) Water-soluble acrylic resin solution AC5 (weight average molecular weight 5500, acid value 215 mg KOH / g, glass transition temperature: 85°C, solid content 40%) Water-soluble acrylic resin solution AC6 (weight average molecular weight 10,000, acid value 41 mg KOH / g, glass transition temperature: 90°C, solid content 40%) Vinyl chloride emulsion PVC1 (Nissin Chemical Co., Ltd., Vinyblan 278, glass transition temperature: 30°C, solid content: 40%) Alcohol alkoxylate surfactant (100% solids, HLB value = 8) Acrylic surfactant (100% solids, HLB value = 7) Fluorocarbon surfactant (100% solids, HLB value = 7) Silicone surfactant (100% solids, HLB value = 14)

[0108] [Table 1-1]

[0109] [Table 1-2]

[0110] [Table 2-1]

[0111] [Table 2-2]

[0112] <Production Example 34> Production of coating agent S1 containing a sizing agent 2500 parts of alkylketene dimer (SE2360, manufactured by Seiko PMC Corporation, solid content 20%) and 7500 parts of a mixed solvent (water / isopropanol=1 / 1) were mixed and stirred to obtain a coating agent S1 containing a sizing agent.

[0113] <Production Examples 35 to 39> Production of coating agents S2 to S6 containing sizing agents Coating agents S2 to S6 containing a sizing agent were obtained in the same manner as in Production Example 34, except that the raw materials and compounding ratios shown in Table 3 were used. The properties of the raw materials used are as follows: Rosin resin (Arakawa Chemical Industries, Polymaron 351T, solids content 20%) Alkenyl succinate (Arakawa Industries, SP864, solid content 20%) Polyvinyl alcohol resin (Nippon Synthetic Chemical Industry Co., Ltd., Gohsenaal T-350, solids content 20%) Starch resin (Japan Cornstarch Co., Ltd., SK-20, solids 20%)

[0114] [Table 3]

[0115] <Production Example 40> Production of Overcoat Agent V1 72 parts of nitrocellulose nc1 (NOBEL, product name NC DHX 5-10, NV 70% (solvent: isopropyl alcohol), weight average molecular weight: 10,000, viscosity at 25.0% solution concentration: 2 seconds) were mixed and dissolved in 33.6 parts ethyl acetate and 33.6 parts isopropyl alcohol to obtain a 30% solids nitrocellulose resin solution (NC1). Next, 65.5 parts of the nitrocellulose resin solution NC1, 5.5 parts N-propyl acetate, 3 parts ethyl acetate, 5.5 parts isopropyl alcohol, 5.4 parts methylcyclohexane, 0.9 parts methylpropylene glycol, 0.9 parts water, 1.85 parts diethylene glycol monobutyl ether (NV 100%), and 3 parts hexamethylenbisoleic acid amide (NV 100%) were mixed and stirred to obtain overcoat agent V1.

[0116] <Production Example 41> Production of Overcoat Agent V2 14.49 parts of water, 60 parts of aqueous acrylic emulsion AC1, 20 parts of aqueous acrylic emulsion AC2, 2 parts of diethylene glycol monobutyl ether, 3 parts of polyethylene wax, 0.5 parts of a phosphate ester compound (Phosphanol RA-600 manufactured by Toho Chemical Industry Co., Ltd., polyoxyethylene alkyl ether phosphate ester, solids content 100%), and 0.01 parts of an antifoaming agent (TEGO (registered trademark) Foamex 1488 manufactured by EVONIC, solids content 100%) were added and mixed with stirring to obtain overcoat agent V2.

[0117] <Production Example 42> Production of Overcoat Agent V3 14.49 parts of water, 80 parts of aqueous urethane resin PU1, 2 parts of diethylene glycol monobutyl ether, 3 parts of polyethylene wax, 0.5 parts of a phosphate ester compound (Phosphanol RA-600 manufactured by Toho Chemical Industry Co., Ltd., polyoxyethylene alkyl ether phosphate ester, solids content 100%), and 0.01 parts of an antifoaming agent (TEGO (registered trademark) Foamex 1488 manufactured by EVONIC, solids content 100%) were added and mixed by stirring to obtain aqueous overcoat agent V3.

[0118] (Manufacturing of laminates) Example 1: Production of laminate P1 A paper stock was obtained by mixing 500 parts of softwood bleached kraft pulp (CSF freeness 500 ml, solvent: water), 500 parts of hardwood bleached kraft pulp (CFS freeness 500 ml, solvent: water), 11 parts of cationized starch (Grain Processing Corporation, CHARGEMASTER R462) as a paper strength agent, and 10 parts by mass of aluminum sulfate. The paper stock was made into a paper sheet with a basis weight of 65 g / m using a Fourdrinier paper machine. 2 A substrate k1 of the above was obtained. Using a tabletop size press machine (manufactured by Kumagai Riki Kogyo Co., Ltd.) capable of simultaneously coating both sides of the substrate k1 in equal amounts, the coating agent S1 containing the sizing agent was applied to both sides in a total amount after drying of 0.3 g / m 2 The mixture was dried in an oven at 60°C to obtain a paper base material K1 containing a sizing agent. The printing ink W1 was diluted with a dilution solvent (water / isopropyl alcohol = 30 / 70) so that it would take 15 seconds (25°C) in a Zahn cup #3 (manufactured by Rigo Co., Ltd.) The diluted printing ink W1 was then printed onto the entire surface of the sizing-containing paper substrate K1 at a printing speed of 40 m / min and an in-line oven temperature of 90°C using a gravure printing machine equipped with a gravure plate with 175 lines / inch heliograving to form a printed layer, thereby obtaining an intermediate laminate p1 having a paper substrate / printed layer configuration. A surface protective layer was formed by hot-melt extrusion coating of polyethylene resin (melting point: 120°C) onto the printed layer of the paper substrate in intermediate laminate p1 under conditions of a resin temperature of 330°C, a coating speed of 80 m / min, and a coating thickness of 10 μm. Furthermore, a polyethylene resin (melting point: 120°C) was hot-melt extrusion coated onto the opposite side of the surface protective layer of the paper substrate in intermediate laminate p1 under conditions of a resin temperature of 330°C, a coating speed of 80 m / min, and a coating thickness of 20 μm, to obtain laminate P1 having a configuration of heat seal layer / paper substrate / printed layer / surface protective layer. The coating amount of the printed layer of laminate P1 was 2 g / m 2 It was.

[0119] <Examples 2 to 25, 29 to 52, Comparative Examples 1 to 7> Production of laminates P2 to 25, 29 to 52, and PP1 to 7 Laminates P2 to 25, 29 to 52 and PP1 to 7 were obtained in the same manner as in Example 1, except that the raw materials and coating methods were changed as shown in Tables 3 to 6.

[0120] Example 26: Production of laminate P26 Printing ink W1 was diluted with a diluting solvent (water / isopropyl alcohol = 30 / 70) so that it took 15 seconds (25°C) to cure in a Zahn cup #3 (manufactured by Rigo Co., Ltd.), and overcoat agent V1 was diluted with a diluting solvent (ethyl acetate / isopropyl alcohol = 70 / 30) so that it took 15 seconds (25°C) to cure in a Zahn cup #3 (manufactured by Rigo Co., Ltd.) The diluted printing ink W1 was then printed onto the entire surface of paper substrate K1 containing a sizing agent at a printing speed of 40 m / min and an in-line oven temperature of 90°C, using a gravure printing machine equipped with a gravure plate with 175 lines / inch heliograving, to form a printed layer, thereby obtaining an intermediate laminate p26 having a paper substrate / printed layer configuration. A surface protective layer was formed on the printed layer of the paper substrate in intermediate laminate p26 by printing diluted overcoat agent V1 using a gravure printing machine equipped with a 175 line / inch heliogravure plate at a printing speed of 40 m / min and an in-line oven temperature of 90°C. Furthermore, a polyethylene resin (melting point: 120°C) was hot-melt extrusion coated on the side opposite the surface protective layer of the paper substrate in intermediate laminate p22 at a resin temperature of 330°C, a coating speed of 80 m / min, and a coating thickness of 20 μm, to obtain laminate P26, which had a heat seal layer / paper substrate / printed layer / surface protective layer configuration. The coating amount of the printed layer of laminate P26 was 2 g / m. 2 It was.

[0121] <Examples 27, 28, 53 to 55> Preparation of laminates P27, P28, and P53 to 55 Laminates P27, P28, and P53 to 55 were obtained in the same manner as in Example 26, except that the overcoating agents shown in Tables 4 and 5 were used instead. The solvents used to dilute the overcoat agent are as follows: Overcoat agent V1: ethyl acetate / isopropyl alcohol = 70 / 30 Overcoat agent V2 and V3: Water / Isopropyl alcohol = 30 / 70

[0122] <Characteristics evaluation> The intermediate laminates p1 to 55 and pp1 to 7 and the laminates P1 to 55 and PP1 to 7 obtained in the above Examples and Comparative Examples were evaluated as described below. The evaluation results are shown in Tables 4 to 6, respectively.

[0123] <Adhesion> A 15 mm wide x 200 mm cellophane tape was applied to the surface of the printed layer of the obtained intermediate laminate, and the condition of the printed layer when it was quickly peeled off was evaluated according to the following criteria, with practical levels being A to C. Evaluation Criteria A: 100% of the printed layer remained on the paper substrate. B: 80% or more and less than 100% of the printed layer remained on the paper substrate. C: 50% or more and less than 80% of the printed layer remained on the paper substrate. D: Less than 50% of the printed layer remained on the paper substrate.

[0124] <Concentration> The print density of the obtained intermediate laminate was measured using X-RiteeXact (density status: ISO status E, white standard: absolute value, filter: none, illuminant / observer field of view: D50 / 2°) manufactured by X-Rite Inc. The practical levels were rated A to C. A: The density of the printed layer is 1.60 or more B: Density of the printed layer is 1.50 or more and less than 1.60 C: Density of the printing layer is 1.40 or more and less than 1.50 D: Density of the printed layer is less than 1.40

[0125] <Leveling ability> The resulting intermediate laminate was visually evaluated for the degree of bleeding of the printed layer and the degree of coating unevenness, with practical levels A to C. (Evaluation criteria) A: No swimming or uneven application is observed, or almost no swimming or uneven application is observed B: Slightly sloppy and uneven application C: Slight runnyness and uneven application D: Significant unevenness in application and swirl

[0126] <Heat sealability evaluation> The resulting laminate was cut into two samples measuring 15 mm x 100 mm, designated Sample (1) and Sample (2). The heat seal layer of Sample (1) and the surface protective layer of Sample (2) were placed in contact with each other, and a PET silicone separator film (manufactured by Nippa Corporation, thickness: 75 μm) was placed on top of the surface protective layer of Sample (1), followed by heat sealing from the PET silicone separator film side using the following equipment and conditions. After heat sealing, the PET silicone separator film was peeled off from Sample (1), and both unsealed ends were fixed to a small tensile tester to evaluate the heat seal strength. The practical grades were A to C. <Heat sealing conditions> Equipment: Heat seal tester manufactured by Tester Sangyo Co., Ltd., seal width: 10 mm from the sample edge, heater temperature: 200°C, seal pressure: 2 kg / cm 2 , Sealing time: 1 sec <<Heat seal strength measurement conditions>> Equipment: Intesco small tensile testing machine (model: IM-20), test piece width: 15 mm, Peeling mode: 90° peeling, pulling speed: 300 mm / min Evaluation Criteria A: The heat seal strength is 5.0N or more. B: The heat seal strength is 3.5N or more and less than 5.0N. C: The heat seal strength is 1.0N or more and less than 3.5N. D: The heat seal strength is less than 1.0 N.

[0127] [Table 4-1]

[0128] [Table 4-2]

[0129] [Table 4-3]

[0130] [Table 5-1]

[0131] [Table 5-2]

[0132] [Table 5-3]

[0133] [Table 6]

[0134] From the above results, Comparative Example 1 had poor density and leveling properties because the printing layer did not contain acrylic resin (A) and urethane resin (B). Comparative Examples 2 and 4 had poor adhesion and leveling properties because the amount of surfactant in the printing layer was less than the specified amount. Comparative Examples 3 and 5 had poor adhesion and heat sealability because the amount of surfactant in the printing layer exceeded the specified amount. Comparative Examples 6 and 7 had poor adhesion, density, leveling properties, and heat sealability because the paper base material did not contain a sizing agent. On the other hand, in the examples, the printing layer contained acrylic resin (A) and / or urethane resin (B), the surfactant content in the printing layer was 0.05 to 20 mass% based on 100 mass% of the printing layer, and the paper base material contained a sizing agent, so the adhesion, concentration, leveling properties, and heat sealability were good.

Claims

1. A laminate having, in this order, a paper substrate containing a sizing agent, a printing layer, and a surface protective layer, the printing layer contains a binder resin, a surfactant, and a colorant; the binder resin contains an acrylic resin (A) and / or a urethane resin (B), A laminate in which the content of the surfactant is 0.05 to 20% by mass relative to 100% by mass of the printed layer.

2. 2. The laminate according to claim 1, wherein the surfactant comprises at least one selected from the group consisting of acetylene-based surfactants, alcohol alkoxylate-based surfactants, silicon-based surfactants, acrylic-based surfactants, and fluorine-based surfactants.

3. 3. The laminate according to claim 1, wherein the total solid content of the acrylic resin (A) and the urethane resin (B) is 75% by mass or more relative to 100% by mass of the solid content of the binder resin.

4. 3. The laminate according to claim 1, wherein the acrylic resin (A) has a weight average molecular weight of 25,000 or more.

5. The laminate according to claim 1 or 2, wherein the urethane resin (B) comprises at least one selected from the group consisting of a structure derived from a polyester polyol, a structure derived from a polyether polyol, and a structure derived from a polycarbonate polyol.

6. The laminate according to claim 1 or 2, wherein the printing layer further comprises a hydrocarbon wax.

7. 3. The laminate according to claim 1, wherein the solid mass ratio of the surfactant to the binder resin in the printed layer is 1:99 to 50:

50.

8. 3. The laminate according to claim 1, wherein the solid mass ratio of the surfactant to the colorant in the printed layer is 1:99 to 40:

60.

9. 3. The laminate according to claim 1, wherein the sizing agent is at least one selected from the group consisting of rosin resins, alkenyl succinates, alkyl ketene dimers, polyvinyl alcohol resins, and starch resins.

10. 3. The laminate according to claim 1, wherein the surface protective layer comprises at least one resin selected from the group consisting of a polyolefin resin, a cellulose-based resin, an acrylic resin (A'), and a urethane resin (B').

11. 3. The laminate according to claim 1, wherein the mass ratio of the sizing agent content in the paper substrate per unit area to the surfactant content in the printing layer per unit area is 0.1:99.9 to 50:

50.

12. The laminate according to claim 1 or 2, which is for use in a packaging container.

13. A method for producing a laminate having, in this order, a paper substrate containing a sizing agent, a printing layer, and a surface protective layer, comprising: a step of printing a printing ink containing a binder resin, a surfactant, and a colorant onto the paper substrate to form the printing layer; the binder resin contains an acrylic resin (A) and / or a urethane resin (B), A method for producing a laminate, wherein the surfactant is present in an amount of 0.05 to 20% by mass relative to 100% by mass of the printed layer.

14. 14. The method for producing a laminate according to claim 13, wherein the printing ink further comprises a solvent, and the solvent comprises an alcohol solvent in an amount of 1 to 70% by mass based on the total amount of the solvent in the printing ink.

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