Resin composition, liquid composition for separative printed layer formation, laminate and printed layer separation method

Abstract

To provide a resin composition for preparing a liquid composition for separative printed layer formation which enables formation of a printed layer that can be easily separated under a mild alkali condition, and is excellent in blocking resistance, heat resistance, glossiness and wet abrasion resistance.SOLUTION: There is provided a resin composition for preparing a liquid composition for separative printed layer formation. The resin composition contains a binder resin (A), a resin (B) for imparting separation property, which has an acid value of 60 to 300 mgKOH / g, and a resin (C) having an acid value of 10 to 55 mgKOH / g and an amine value of 15 mgKOH / g or less, the binder resin (A) is a combination of (A-1) a cellulose resin and a polyamide resin, a content of the resin (B) is 2 to 20 mass% based on a solid content (except for a pigment), a content of the resin (C) is 2 to 20 mass% based on a solid content (except for a pigment), and the content of the resin (C) with respect to 1 pts.mass of the resin (B) is 0.3 to 3.2 pts.mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a liquid composition for forming a removable printed layer, a laminate, and a method for removing a printed layer. [Background technology]

[0002] Various containers made of plastic materials are widely used as containers for storing food, soft drinks, cosmetics, seasonings, medicines, sanitary products, etc. On the surface of these containers, various information such as the product name, contents, and manufacturer is usually printed directly with ink, or a resin label with various information printed on it is affixed. In addition, various information such as the product name is usually printed with ink on the surface of resin bags for storing bread, rice balls, side dishes, etc.

[0003] From the viewpoint of protecting the global environment, various molded articles (substrates) such as containers, labels, and bags are collected, recycled, and widely used as secondary products. However, as mentioned above, various information is printed on the surface of these substrates with ink. Therefore, when recycling and reusing resin molded articles and labels, it is necessary to remove the ink applied to their surfaces beforehand.

[0004] Previously, inks capable of printing a removable printing layer upon treatment with an alkaline aqueous solution have been proposed. For example, a removable ink composition containing a copolymer containing a lower alkyl ester unit of an unsaturated carboxylic acid, which becomes water-soluble upon saponification, has been proposed (Patent Document 1). Another proposed ink composition contains a binder resin and a resin such as a rosin-maleic acid resin (Patent Document 2). Furthermore, a printing ink for forming a removable printing layer, which contains a colorant, a dispersant such as a pigment derivative, and a binder resin having an acidic group, as well as a packaging material having a printing layer formed with this printing ink, have been proposed (Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-86951 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-31899 [Patent Document 3] Japanese Patent Application Publication No. 2023-36097 Summary of the Invention [Problem to be solved by the invention]

[0006] Various studies have been conducted to date on the releasability of printed layers by treatment with an alkaline aqueous solution. However, printed layers formed using conventional ink compositions proposed in Patent Documents 1 to 3 and the like are not necessarily easily removable under mild conditions, and sometimes require strict conditions. Furthermore, the properties of removable printed layers formed using conventional ink compositions, such as blocking resistance, heat resistance, gloss, and wet friction resistance, are not necessarily sufficient, and further improvements are desired.

[0007] The present invention was made in consideration of the problems associated with the prior art, and its objective is to provide a resin composition for preparing a liquid composition for forming a detachable printing layer that can be easily detached under mild alkaline conditions and that can form a printing layer that has excellent blocking resistance, heat resistance, gloss, and wet friction resistance.

[0008] Another object of the present invention is to provide a liquid composition for forming a removable printing layer that can easily be removed under mild alkaline conditions and that can form a printing layer that has excellent blocking resistance, heat resistance, gloss, and wet friction resistance.A further object of the present invention is to provide a laminate including a printing layer formed from the above-mentioned liquid composition for forming a removable printing layer, and a method for removing the printing layer from this laminate. [Means for solving the problem]

[0009] That is, according to the present invention, there is provided the following resin composition. [1] A resin composition for preparing a liquid composition for forming a detachable printing layer, comprising a binder resin (A), a resin (B) for imparting detachability having an acid value of 60 to 300 mgKOH / g, and a resin (C) having an acid value of 10 to 55 mgKOH / g and an amine value of 15 mgKOH / g or less, wherein the binder resin (A) is a combination of any of the following (A-1), (A-2), and (A-3), wherein the content of the resin (B) is 2 to 20 mass% based on the solid content (excluding pigments), the content of the resin (C) is 2 to 20 mass% based on the solid content (excluding pigments), and the content of the resin (C) is 0.3 to 3.2 mass parts per 1 mass part of the resin (B). (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin [2] The resin composition according to [1], wherein the resin (B) is at least one selected from the group consisting of rosin-maleic acid resin, styrene-acrylic acid resin, styrene-maleic acid resin, hydrogenated rosin resin, and terpene phenol resin. [3] The resin composition according to [1] or [2], wherein the resin (C) is at least one selected from the group consisting of carboxylic acid compounds, phosphoric acid ester compounds, phosphonic acid compounds, phosphinic acid compounds, and acid alkyl ester compounds. [4] The resin composition according to any one of [1] to [3] above, further comprising a curing agent.

[0010] The present invention also provides the following liquid composition for forming a detachable printing layer. [5] A liquid composition for forming a removable printing layer, comprising a binder resin (A), a resin (B) for imparting releasability having an acid value of 60 to 300 mgKOH / g, and a resin (C) having an acid value of 10 to 55 mgKOH / g and an amine value of 15 mgKOH / g or less, wherein the binder resin (A) is a combination of any of the following (A-1), (A-2), and (A-3), wherein the content of the resin (B) is 2 to 20 mass% based on the solid content (excluding pigments), the content of the resin (C) is 2 to 20 mass% based on the solid content (excluding pigments), and the content of the resin (C) is 0.3 to 3.2 mass parts per 1 mass part of the resin (B). (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin [6] The liquid composition according to [5], wherein the resin (B) is at least one selected from the group consisting of rosin-maleic acid resin, styrene-acrylic acid resin, styrene-maleic acid resin, hydrogenated rosin resin, and terpene phenol resin. [7] The liquid composition according to [5] or [6], wherein the resin (C) is at least one selected from the group consisting of carboxylic acid compounds, phosphoric acid ester compounds, phosphonic acid compounds, phosphinic acid compounds, and acid alkyl ester compounds. [8] The liquid composition according to any one of [5] to [7] above, further comprising a curing agent. [9] The liquid composition according to any one of [5] to [8], which is an ink, a medium, a primer, or an overcoat varnish.

[0011] Furthermore, according to the present invention, there is provided the following laminate.

[10] A laminate comprising a resin substrate and a printed layer formed from the liquid composition according to any one of [5] to [9] above, disposed on the substrate.

[11] The laminate according to

[10] above, which is a label or packaging material.

[0012] The present invention also provides the following method for removing a printed layer.

[12] A method for removing a printed layer, comprising the step of contacting the printed layer of the laminate described in

[10] or

[11] with an alkaline aqueous solution to remove and detach the printed layer from the substrate.

[13] The method for removing a printed layer according to

[12] , further comprising the step of recovering the substrate from which the printed layer has been removed. [Effects of the Invention]

[0013] According to the present invention, a resin composition can be provided for preparing a liquid composition for forming a removable printing layer that can be easily removed under mild alkaline conditions and can form a printing layer that has excellent blocking resistance, heat resistance, gloss, and wet friction resistance.

[0014] The present invention also provides a liquid composition for forming a removable printing layer that can easily be removed under mild alkaline conditions and that can form a printing layer that has excellent blocking resistance, heat resistance, gloss, and wet friction resistance.Furthermore, the present invention also provides a laminate including a printing layer formed from the liquid composition for forming a removable printing layer, and a method for removing the printing layer from this laminate. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present inventors have investigated liquid compositions such as inks, mediums, primers, and overcoat varnishes that can be applied to the surface of various resin molded articles (substrates) to form a printed layer, and that the formed printed layer can be easily removed by treating it under alkaline conditions. As a result, they have found that when a specific binder resin combining two types of resins is combined with a resin for imparting releasability to the printed layer, which has an acid value within a specific range, and a resin whose acid value and amine value are within specific ranges, in a predetermined ratio, it is possible to form a printed layer that not only has improved releasability but also various properties such as blocking resistance, heat resistance, gloss, and wet friction resistance, thereby completing the present invention.

[0016] <Resin composition> One embodiment of the resin composition of the present invention is a composition for preparing a liquid composition for forming a removable printing layer, and contains a binder resin (A), a resin (B) for imparting alkali releasability to the printing layer to be formed, and a resin (C) other than the binder resin (A) and the resin (B). The binder resin (A) is a combination of any of the following (A-1), (A-2), and (A-3). The acid value of the resin (B) is 60 to 300 mg KOH / g. The acid value of the resin (C) is 10 to 55 mg KOH / g, and the amine value is 15 mg KOH / g or less. The content of the resin (B) is 2 to 20 mass% based on the solid content (excluding pigments). The content of the resin (C) is 2 to 20 mass% based on the solid content (excluding pigments). The content of resin (C) relative to 1 part by mass of resin (B) is 0.3 to 3.2 parts by mass. The resin composition of this embodiment will be described in detail below. (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin

[0017] (Binder resin (A)) The binder resin (A) is a combination of any of the following (A-1), (A-2), and (A-3). By combining two specific resins and using them as the binder resin (A), it is possible to impart the properties required for various printed layers provided on labels, packages, etc. (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin

[0018] (Binder resin (A)) (A-1) is a combination of a cellulose resin and a polyamide resin. By combining a cellulose resin and a polyamide resin, it is expected that the properties of the resulting printed layer will be improved, such as heat resistance, blocking resistance, abrasion resistance, adhesion, and gloss.

[0019] (A-2) is a combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin. By combining polyurethane resin and vinyl chloride-vinyl acetate copolymer resin, it is expected that the properties of the resulting printed layer will be improved, such as adhesion, heat resistance, and blocking resistance.

[0020] (A-3) is a combination of a cellulose resin and a (meth)acrylic resin. By combining a cellulose resin and a (meth)acrylic resin, it is expected that the properties of the resulting printed layer, such as adhesion, heat resistance, and blocking resistance, will be improved.

[0021] [Cellulose resin] Examples of cellulose resins include cellulose esters such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate propionate, and cellulose acetate butyrate; cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and carboxymethyl cellulose; and nitrocellulose. Preferred cellulose resins include cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), and nitrocellulose. Of these, nitrocellulose is particularly preferred. Preferred cellulose resins in the combination (A-3) include cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB).

[0022] [Polyamide resin] The polyamide resin is a polycondensation product of a polybasic acid and a polyamine. Among them, a thermoplastic polyamide resin that is soluble in an organic solvent can be preferably used.

[0023] Examples of polybasic acids include adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, dimer acid, and hydrogenated dimer acid. Monocarboxylic acids such as acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, and cyclohexanecarboxylic acid can also be used together with these polybasic acids.

[0024] Examples of polyamines that can be used include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine; aliphatic polyamines such as diethylenetriamine and triethylenetetramine; alicyclic polyamines such as cyclohexylenediamine and isophoronediamine; and aromatic polyamines such as xylylenediamine, phenylenediamine, and diaminodiphenylmethane. Primary and secondary monoamines such as n-butylamine, octylamine, dielamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine can also be used in addition to these polyamines.

[0025] Specific examples of polyamide resins include thermoplastic polyamide resins obtained using fatty acids prepared from plant materials or polymerized fatty acids. Representative examples of fatty acids prepared from plant materials include tall oil, soybean oil, coconut oil, palm oil, cashew nut oil, rice bran oil, and cacao oil. Furthermore, examples of polymerized fatty acids include dimer acids and hydrogenated dimer acids obtained by hydrogen reduction of dimer acids.

[0026] The weight-average molecular weight of the polyamide resin is preferably 500 to 50,000, more preferably 700 to 30,000, and particularly preferably 1,000 to 10,000. If the weight-average molecular weight of the polyamide resin is too small, the abrasion resistance and heat resistance of the printed layer may be slightly reduced. On the other hand, if the weight-average molecular weight of the polyamide resin is too large, the adhesion and solubility of the printed layer to the substrate may be slightly reduced. The weight-average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0027] The acid value of the polyamide resin is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and particularly preferably 15 mgKOH / g or less. If the acid value of the polyamide resin is too high, the stability of the liquid composition such as ink may be slightly reduced.

[0028] The amine value of the polyamide resin is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and particularly preferably 15 mgKOH / g or less. If the amine value of the polyamide resin is too high, printability may be slightly reduced.

[0029] The softening point of the polyamide resin is preferably 80 to 160°C, more preferably 85 to 150°C, and particularly preferably 90 to 140°C. If the softening point of the polyamide resin is too low, the heat resistance and blocking resistance of the printed layer may be slightly reduced. If the softening point of the polyamide resin is too high, the adhesion to the substrate may be slightly reduced. The softening point in this specification is a value measured in accordance with JIS K 2207.

[0030] [Polyurethane resin] As the polyurethane resin, a thermoplastic polyurethane resin soluble in an organic solvent obtained by polymerizing a polyol and a polyisocyanate can be suitably used. The polyurethane resin can be produced according to a conventionally known method. For example, a product obtained by reacting a urethane prepolymer, which is a reaction product of a diisocyanate compound and a polyol compound, with a chain extender and a reaction terminator as necessary can be used.

[0031] Diisocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4-diphenylether diisocyanate, 2-nitrodiphenyl-4,4-diisocyanate, 2,2-diphenylpropane-4,4-diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, 4,4-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, and naphthylene-1 aromatic diisocyanates such as 2,4-diisocyanate, naphthylene-1,5-diisocyanate, and 3,3-dimethoxydiphenyl-4,4-diisocyanate; aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; and the like.

[0032] Examples of the polyol compound include polyester polyol, polycarbonate polyol, and polyether polyol.

[0033] Examples of polyester polyols include polyester polyols and polyesteramide polyols obtained by dehydration polycondensation reaction between polycarboxylic acids and polyhydric alcohols or secondary or tertiary amines.

[0034] Examples of polycarboxylic acids include polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydroorthophthalic acid, naphthalenedicarboxylic acid, and trimellitic acid; polycarboxylic acid esters; polycarboxylic acid anhydrides; and the like.

[0035] Examples of polyhydric alcohols include low molecular weight alcohol compounds such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, ethylene oxide or propylene oxide adducts of bisphenol A, trimethylolpropane, glycerin, and pentaerythritol; and low molecular weight amino alcohol compounds such as monoethanolamine and diethanolamine.

[0036] Examples of secondary and tertiary amines include low molecular weight amine compounds such as hexamethylenediamine, xylylenediamine, and isophoronediamine.

[0037] As the polyester polyol, lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester (lactone) monomers such as ε-caprolactone and γ-valerolactone using a low molecular weight alcohol compound, a low molecular weight amino alcohol compound, or the like as an initiator can also be used.

[0038] Examples of polycarbonate polyols include those obtained by the dehydrochlorination reaction of a low-molecular-weight alcohol compound used in the synthesis of polyester polyol with phosgene; and those obtained by the transesterification reaction of such a low-molecular-weight alcohol compound with diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, or the like.

[0039] Examples of polyether polyols include polyoxyethylene polyols, polyoxypropylene polyols, polytetramethylene ether polyols, and polyoxyethylene polyoxypropylene polyols obtained by ring-opening polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide, and tetrahydrofuran, using the above-mentioned low-molecular-weight alcohol compounds, low-molecular-weight amine compounds, low-molecular-weight amino alcohol compounds, and phenols as initiators.Further examples include polyester ether polyols using the above-mentioned polyester polyols and polycarbonate polyols as initiators.

[0040] The chain extender may be a compound having two or more functional groups (such as amino groups and hydroxyl groups) in the molecule that can react with an isocyanate group. Examples of the chain extender include diamine compounds such as ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, hexamethylenediamine, isophoronediamine, and 2-ethylaminoethylamine; polyamine compounds such as diethylenetriamine and triethylenetetramine; low-molecular-weight diol compounds such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, and triethylene glycol; aminoethylethanolamine; and aminopropylethanolamine.

[0041] Examples of the reaction terminator include monoalkylamines such as n-propylamine and n-butylamine; dialkylamines such as di-n-butylamine; alkanolamines such as monoethanolamine and diethanolamine; and monoalcohols such as methanol and ethanol.

[0042] The number average molecular weight of the polyurethane resin is preferably 3,000 to 50,000, more preferably 4,000 to 30,000, and particularly preferably 5,000 to 20,000. If the number average molecular weight of the polyurethane resin is too small, the blocking resistance and heat resistance of the printed layer may be slightly reduced. If the number average molecular weight of the polyurethane resin is too large, the adhesion to the substrate may be slightly reduced. The number average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0043] The hydroxyl value of the polyurethane resin is preferably 50 mgKOH / g or less, more preferably 30 mgKOH / g or less, and particularly preferably 20 mgKOH / g or less. If the hydroxyl value of the polyurethane resin is too high, the stability of the liquid composition such as ink and the blocking resistance of the printed layer may be slightly reduced. The hydroxyl value in this specification is a value measured in accordance with JIS K 1557-1.

[0044] The amine value of the polyurethane resin is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and particularly preferably 3 mgKOH / g or less. If the amine value of the polyurethane resin is too high, printability may be slightly reduced. The amine value in this specification is a value measured by neutralization titration using hydrochloric acid in accordance with JIS K 7237.

[0045] The acid value of the polyurethane resin is preferably 20 mgKOH / g or less, more preferably 15 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. If the acid value of the polyurethane resin is too high, the stability of the liquid composition such as ink and the blocking resistance of the printed layer may be slightly reduced. The acid value in this specification is a value measured by the neutralization titration method in accordance with JIS K 0070-1992.

[0046] [Vinyl chloride-vinyl acetate copolymer resin] Vinyl chloride-vinyl acetate copolymer resin (hereinafter also referred to as "Vinyl chloride-vinyl acetate resin") is a copolymerization reaction product of vinyl chloride and vinyl acetate. Vinyl chloride-vinyl acetate copolymer resin may contain structural units (other structural units) other than structural units derived from vinyl chloride and structural units derived from vinyl acetate, as necessary. Examples of vinyl chloride-vinyl acetate copolymer resins containing other structural units include vinyl chloride-vinyl acetate-vinyl alcohol copolymer resin, vinyl chloride-vinyl acetate-hydroxyalkyl (meth)acrylic acid ester copolymer resin, and vinyl chloride-vinyl acetate-dicarboxylic acid copolymer resin. Among these, it is preferable to use vinyl chloride-vinyl acetate-vinyl alcohol copolymer resin.

[0047] In the vinyl chloride-vinyl acetate copolymer resin, the content of structural units derived from vinyl chloride is preferably 50 to 98% by mass, more preferably 70 to 98% by mass, and particularly preferably 80 to 95% by mass. If the content of structural units derived from vinyl chloride is too low, the blocking resistance of the printed layer may be slightly reduced. On the other hand, if the content of structural units derived from vinyl chloride is too high, the adhesion of the printed layer to the substrate and the kneading resistance may be slightly reduced.

[0048] In the vinyl chloride-vinyl acetate copolymer resin, the content of structural units derived from vinyl acetate is preferably 0.1 to 20% by mass, more preferably 0.3 to 10% by mass, and particularly preferably 0.5 to 5% by mass. If the content of structural units derived from vinyl acetate is too low, the adhesion of the printed layer to the substrate and the resistance to rubbing may be slightly reduced. On the other hand, if the content of structural units derived from vinyl acetate is too high, the blocking resistance of the printed layer may be slightly reduced.

[0049] The glass transition temperature of the vinyl chloride-vinyl acetate copolymer resin is preferably 40 to 110°C, more preferably 50 to 100°C, and particularly preferably 60 to 90°C. If the glass transition temperature of the vinyl chloride-vinyl acetate copolymer resin is too low, the blocking resistance and heat resistance of the printed layer may be slightly reduced. On the other hand, if the glass transition temperature of the vinyl chloride-vinyl acetate copolymer resin is too high, the adhesion of the printed layer to the substrate may be slightly reduced.

[0050] The number-average molecular weight of the vinyl chloride-vinyl acetate copolymer resin is preferably 10,000 to 100,000, more preferably 15,000 to 80,000, and particularly preferably 20,000 to 50,000. If the number-average molecular weight of the vinyl chloride-vinyl acetate copolymer resin is too small, the blocking resistance and heat resistance of the printed layer may be slightly reduced. On the other hand, if the number-average molecular weight of the vinyl chloride-vinyl acetate copolymer resin is too large, the adhesion of the printed layer to the substrate may be slightly reduced.

[0051] [(Meth)acrylic resin] (Meth)acrylic resins are polymers whose main component is a structural unit derived from a (meth)acrylic acid ester. Examples of (meth)acrylic resins include homopolymers of (meth)acrylic acid esters; copolymers of multiple types of (meth)acrylic acid esters; copolymers of (meth)acrylic acid esters and other polymerizable monomers copolymerizable with (meth)acrylic acid esters; urethane-modified acrylic resins; and silicone-modified acrylic resins. In this specification, "(meth)acrylic" refers to both "acrylic" and "methacrylic."

[0052] Examples of the (meth)acrylic acid ester include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylic acid aralkyl esters such as benzyl (meth)acrylate; (meth)acrylic acid aryl esters such as phenyl (meth)acrylate and naphthyl (meth)acrylate; and (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate.

[0053] Other polymerizable monomers copolymerizable with (meth)acrylic acid esters include styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, and derivatives thereof; unsaturated carboxylic acid-based monomers such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acrylamide; methacrylamide; acrylonitrile; methacrylonitrile; and the like.

[0054] The (meth)acrylic resin preferably has a hydroxyl group and is preferably an acrylic polyol. The hydroxyl value of the (meth)acrylic resin is preferably 1 to 130 mgKOH / g, more preferably 10 to 120 mgKOH / g, and particularly preferably 50 to 110 mgKOH / g. If the hydroxyl value of the (meth)acrylic resin is too low, the adhesion of the printed layer to the substrate may be slightly reduced. On the other hand, if the hydroxyl value of the (meth)acrylic resin is too high, the stability of the liquid composition such as ink and the blocking resistance of the printed layer may be slightly reduced.

[0055] The acid value of the (meth)acrylic resin is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and particularly preferably 10 mgKOH / g or less. If the acid value of the (meth)acrylic resin is too high, the stability of the liquid composition such as ink may be slightly reduced.

[0056] The glass transition temperature of the (meth)acrylic resin is preferably 5 to 100°C, more preferably 10 to 70°C, and particularly preferably 15 to 40°C. If the glass transition temperature of the (meth)acrylic resin is too low, the blocking resistance and heat resistance of the printed layer may be slightly reduced. On the other hand, if the glass transition temperature of the (meth)acrylic resin is too high, the adhesion of the printed layer to the substrate may be slightly reduced.

[0057] The weight-average molecular weight of the (meth)acrylic resin is preferably 10,000 to 300,000, more preferably 20,000 to 280,000, and particularly preferably 40,000 to 250,000. If the weight-average molecular weight of the (meth)acrylic resin is too small, the blocking resistance and heat resistance of the printed layer may be slightly reduced. On the other hand, if the weight-average molecular weight of the (meth)acrylic resin is too large, the adhesion of the printed layer to the substrate may be slightly reduced.

[0058] The content of the binder resin (A) may be appropriately set depending on the intended use, etc. For example, the content of the binder resin (A) is preferably 40 to 90 mass % based on the solid content, more preferably 50 to 80 mass %, and particularly preferably 60 to 70 mass %. By setting the content of the binder resin (A) within the above range, the adhesion of the printing layer can be further improved.

[0059] (Resin (B)) Resin (B) is a component that imparts alkali-removability to the resulting printed layer, and is a resin with a relatively high acid value of 60 to 300 mgKOH / g. By using such resin (B), it is possible to form a printed layer that can be removed by alkali treatment.

[0060] The acid value of resin (B) is 60 to 300 mgKOH / g, preferably 70 to 270 mgKOH / g, and more preferably 80 to 230 mgKOH / g. From the viewpoints of blocking resistance, heat resistance, and wet rub resistance, it is particularly preferably 85 to 200 mgKOH / g. If the acid value of resin (B) is less than 60 mgKOH / g, it becomes difficult to improve the releasability of the printed layer by alkali treatment in PET or nylon. On the other hand, if the acid value of resin (B) exceeds 300 mgKOH / g, the stability of liquid compositions such as inks decreases, and the wet rub resistance and water resistance of the printed layer decrease. Furthermore, the stability of liquid compositions such as inks containing crosslinking agents such as curing agents tends to decrease. By setting the acid value of resin (B) within the above range, blocking resistance, heat resistance, wet rub resistance, and releasability can be improved.

[0061] From the viewpoint of improving wet friction resistance, it is particularly preferable to use at least one resin selected from the group consisting of rosin-maleic acid resin, styrene-acrylic acid resin, styrene-maleic acid resin, hydrogenated rosin resin, and terpene phenol resin as resin (B). Among these, it is preferable to use at least one resin selected from the group consisting of rosin-maleic acid resin, styrene-acrylic acid resin, styrene-maleic acid resin, and terpene phenol resin. Furthermore, from the viewpoint of improving the releasability of the printed layer by alkali treatment and the gloss of the printed layer in a balanced manner, it is even more preferable that resin (B) be a rosin-maleic acid resin.

[0062] Known rosin-maleic acid resins can be used as the rosin-maleic acid resin (hereinafter also referred to as "rosin-modified maleic acid resin"). Examples of rosin-maleic acid resins include a resin obtained by adding maleic anhydride to rosin, and a resin obtained by partially esterifying this resin with a polyol.

[0063] Styrene-acrylic acid resins are copolymers of styrene-based monomers and acrylic-based monomers. Examples of styrene-acrylic acid resins include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid alkyl ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymers.

[0064] Examples of styrene-maleic acid resins include copolymers composed of at least one styrene-based monomer selected from the group consisting of styrene and styrene derivatives and at least one maleic acid-based monomer selected from the group consisting of maleic acid and maleic acid derivatives.

[0065] Examples of hydrogenated rosin resins include hydrogenation reaction products of rosin resins (tall rosin, gum rosin, wood rosin, etc., which contain resin acids such as abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, and dehydroabietic acid as their main components).

[0066] Terpene phenolic resins are copolymers of terpenes and phenolic compounds, including monoterpenes such as α-pinene, β-pinene, and limonene (including d-, l-, and d / l-dipentene).

[0067] The content of resin (B) is 2 to 20% by mass, preferably 3 to 17% by mass, more preferably 5 to 15% by mass, based on the solid content (excluding pigments). From the viewpoints of blocking resistance, gloss, heat resistance, and wet rub resistance, it is particularly preferably 5.5 to 10% by mass. If the content of resin (B) based on the solid content (excluding pigments) is less than 2% by mass, the release properties in PET are poor. On the other hand, if the content of resin (B) based on the solid content (excluding pigments) is more than 20% by mass, the blocking resistance, heat resistance, and wet rub resistance are poor. By setting the content of resin (B) based on the solid content (excluding pigments) within the above range, the blocking resistance, heat resistance, wet rub resistance, gloss, and release properties of the printed layer can be improved.

[0068] (Resin (C)) Resin (C) is a resin other than binder resin (A) and resin (B), and is a component that contributes to improving the releasability of the printing layer. Note that when the liquid composition for forming a detachable printing layer prepared using the resin composition of this embodiment contains a component (insoluble component) that is insoluble in the liquid medium, such as a pigment, resin (C) is a component that can also function as a dispersant to improve the dispersibility of the insoluble component in the liquid medium.

[0069] The acid value of resin (C) is 10 to 55 mgKOH / g or less, preferably 10 to 50 mgKOH / g, more preferably 10 to 40 mgKOH / g. From the viewpoints of blocking resistance, heat resistance, and wet abrasion resistance, it is particularly preferably 10 to 30 mgKOH / g. If the acid value of resin (C) is less than 10 mgKOH / g, it becomes difficult to improve the releasability of the printed layer in PET or nylon. On the other hand, if the acid value of resin (C) exceeds 55 mgKOH / g, the blocking resistance, heat resistance, and wet abrasion resistance of the printed layer decrease. By setting the acid value of resin (C) within the above range, it is possible to improve blocking resistance, heat resistance, wet abrasion resistance, and releasability.

[0070] The amine value of resin (C) is 15 mgKOH / g or less, preferably 13 mgKOH / g or less, more preferably 11 mgKOH / g or less, particularly preferably 7 mgKOH / g or less, and most preferably 3 mgKOH / g or less because this provides particularly excellent release properties. If the amine value of resin (C) exceeds 15 mgKOH / g, the blocking resistance and heat resistance of the printed layer will decrease, and it will be difficult to improve the release properties of the printed layer by alkali treatment in PET or nylon. There is no particular restriction on the lower limit of the amine value of resin (C), but it may be essentially 0 mgKOH / g. By setting the amine value of resin (C) within the above range, blocking resistance, heat resistance, and release properties can be improved.

[0071] As the resin (C), it is preferable to use at least one selected from the group consisting of carboxylic acid compounds, phosphoric acid ester compounds, phosphonic acid compounds, phosphinic acid compounds, and acid alkyl ester compounds.

[0072] Resin (C) may be one produced by a conventional method or a commercially available product. Examples of commercially available resins that can be used as resin (C) include the Solsperse series manufactured by Lubrizol Corporation, the Disperbyk series manufactured by BYK, the Dispex series and Efka series manufactured by BASF, the Tego Disperse series manufactured by Evonik, the Disparlon series manufactured by Kusumoto Chemicals, the Floren series manufactured by Kyoeisha Chemical, the Tarplus series manufactured by Otsuka Chemical, and the Ajisper series manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0073] The content of resin (C) is 2 to 20% by mass, preferably 2 to 17% by mass, and more preferably 2 to 15% by mass, based on the solid content (excluding pigments), and from the viewpoint of wet friction resistance. If the content of resin (C) based on the solid content (excluding pigments) is less than 2% by mass, the release properties for PET and nylon are poor. On the other hand, if the content of resin (C) based on the solid content (excluding pigments) is more than 20% by mass, the wet friction resistance is poor. By keeping the content of resin (C) within the above range, the blocking resistance, heat resistance, wet friction resistance, and release properties of the printed layer can be improved.

[0074] The content of resin (C) per part by mass of resin (B) is 0.3 to 3.2 parts by mass. By setting the content of resin (C) per part by mass of resin (B) within the above range, the blocking resistance, heat resistance, gloss, wet rub resistance, and releasability of the printed layer can be improved. If the content of resin (C) per part by mass of resin (B) is less than 0.3 parts by mass, the blocking resistance, heat resistance, wet rub resistance, and releasability from PET and nylon are poor. If the content of resin (C) per part by mass of resin (B) is more than 3.2 parts by mass, the wet rub resistance and releasability from PET and nylon are poor.

[0075] (hardening agent) The resin composition of this embodiment may further contain a crosslinking agent such as a curing agent, if necessary. Examples of curing agents include isocyanate compounds and carbodiimide compounds. The content of the curing agent may be appropriately determined depending on the purpose, etc. For example, the content of the curing agent is preferably 5 to 15 mass % based on the solid content.

[0076] The curing agent may be one produced by a conventional method or a commercially available product. Examples of commercially available resins that can be used as the curing agent include isocyanate compounds such as the Duranate series (manufactured by Asahi Kasei) and the Coronate series (manufactured by Tosoh Corporation); and carbodiimide compounds such as the Carbodilite series (manufactured by Nisshinbo Chemical).

[0077] (Method for preparing resin composition) The resin composition of the present embodiment can be prepared by mixing the above-mentioned components in a conventional manner. If necessary, an organic solvent and various additives may be further added.

[0078] By using the resin composition of this embodiment, it is possible to easily prepare liquid compositions such as ink, medium, primer, and overcoat varnish for forming a removable printing layer, which will be described later. That is, by mixing the resin composition with each of the conventionally known components used in liquid compositions such as ink in a conventional manner, it is possible to prepare a liquid composition for forming a removable printing layer, which can form a printing layer that is easily removable under mild alkaline conditions and has excellent blocking resistance, heat resistance, gloss, and wet friction resistance.

[0079] <Liquid composition for forming a detachable print layer> One embodiment of the liquid composition of the present invention is a composition for forming a removable printing layer, containing a binder resin (A), a resin (B) for imparting alkali releasability to the printing layer to be formed, and a resin (C) other than the binder resin (A) and the resin (B). The binder resin (A) is any combination of the following (A-1), (A-2), and (A-3). The acid value of the resin (B) is 60 to 300 mgKOH / g. The acid value of the resin (C) is 10 to 55 mgKOH / g, and the amine value is 15 mgKOH / g or less. The content of the resin (B) is 2 to 20 mass% based on the solid content (excluding pigments). The content of the resin (C) is 2 to 20 mass% based on the solid content (excluding pigments). The content of the resin (C) is 0.3 to 3.2 mass parts per 1 mass part of the resin (B). (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin

[0080] The liquid composition for forming a removable printing layer of this embodiment (hereinafter also referred to simply as "liquid composition") contains specific binder resin (A), resin (B), and resin (C) in predetermined contents and mass ratios, etc., similar to the resin composition described above, and therefore can form a printing layer that is easily removable under mild alkaline conditions and has excellent blocking resistance, heat resistance, gloss, and wet friction resistance. Note that each component, such as binder resin (A), resin (B), and resin (C), is the same as each component, such as binder resin (A), resin (B), and resin (C), used in the resin composition described above.

[0081] (optional ingredient) The liquid composition of the present embodiment may further contain pigments, organic solvents, and various additives as components other than the binder resin (A), resin (B), and resin (C) described above.

[0082] [Pigment] The pigment may be a general pigment used in inks such as gravure printing inks, etc. Examples of the pigment include inorganic pigments such as ultramarine, Prussian blue, cobalt blue, red iron oxide, iron black, yellow iron oxide, titanium dioxide, and carbon black, and organic pigments such as monoazo pigments, disazo pigments, condensed azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, thioindigo pigments, and pyrrolopyrrole pigments.

[0083] The content of the pigment in the liquid composition may be appropriately set depending on the color tone, density, etc. of the printing layer (printed matter) to be formed. Specifically, the content of the pigment is usually 40% by mass or less, and preferably 30% by mass or less, based on the total mass of the liquid composition.

[0084] [Organic solvents] The liquid composition may contain an organic solvent as a solvent or dispersion medium, such as ethyl acetate, propyl acetate, butyl acetate, methyl ethyl ketone, methanol, ethanol, isopropanol, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, and toluene.

[0085] The content of the organic solvent in the liquid composition may be appropriately set depending on the printing method, etc. Specifically, the content of the organic solvent is usually 20 to 60 mass %, and preferably 30 to 50 mass %, based on the total mass of the liquid composition.

[0086] [Additives] The liquid composition may contain additives such as extender pigments, waxes, synthetic resin powders, and plasticizers to maintain the properties of the liquid composition such as viscosity and fluidity, to plasticize the printed layer (printed surface), and to impart slip properties to the printed layer (printed surface).

[0087] Examples of extender pigments include alumina white, talc, precipitated barium sulfate, and calcium carbonate. Examples of waxes include polyethylene wax, polypropylene wax, paraffin wax, carnauba wax, and ozokerite. Examples of synthetic resin powders include acrylic resin powder, polyurethane resin powder, polyimide resin powder, melamine resin powder, benzoguanamine resin powder, and silicone resin powder. Examples of plasticizers include dibutyl phthalate, dioctyl phthalate, dioctyl adipate, and triethyl citrate.

[0088] The inclusion of wax in the liquid composition is preferred because it can improve the abrasion resistance of the resulting printed layer. The wax content in the liquid composition is preferably 1 to 3 mass %, and more preferably 1.5 to 2.5 mass %, based on the total mass of the liquid composition.

[0089] (hardening agent) The liquid composition of this embodiment may further contain a crosslinking agent such as a curing agent, if necessary. Examples of the curing agent that may be contained in the resin composition include the same curing agents as those described above. The content of the curing agent may be appropriately determined depending on the purpose, etc. For example, the content of the curing agent in the liquid composition is preferably 1 to 10 mass % based on the total mass of the liquid composition.

[0090] (Method for preparing liquid composition) The liquid composition of this embodiment can be prepared by mixing the above-mentioned components in a conventional manner.

[0091] The liquid composition of this embodiment can be prepared by adding the aforementioned resin (B) and resin (C) to a general non-releasing liquid printing composition such as an ink, medium, primer, or overcoat varnish containing a binder resin (A) at a predetermined content and mass ratio. That is, by appropriately adding the aforementioned resin (B) and resin (C) to a liquid composition such as a non-releasing ink, the liquid composition such as a non-releasing ink can be converted into a liquid composition with releasing properties.

[0092] Furthermore, the liquid composition of this embodiment can also be prepared by adding various components that are incorporated into general liquid compositions for printing, such as ink, medium, primer, and overcoat varnish, to the above-mentioned resin composition (resin composition of this embodiment) for preparing a liquid composition for forming a detachable printing layer.

[0093] The liquid composition of this embodiment can be used as an ink, medium, primer, and overcoat varnish. That is, the liquid composition can be suitably used not only as an ink containing a colorant such as a pigment, but also as a medium, primer, and overcoat varnish that is substantially free of pigment. It is also possible to produce printed materials by combining an ink containing a pigment with a medium, primer, or overcoat varnish that is free of pigment. From the standpoint of compatibility, it is particularly preferable to combine an ink having the same composition of components other than the pigment with a medium, primer, or overcoat varnish.

[0094] <Laminate> One embodiment of the laminate of the present invention comprises a resin substrate and a printed layer formed from the liquid composition for forming the detachable printed layer described above, disposed on the substrate. That is, by using the liquid composition described above, a laminate can be obtained in which a detachable printed layer that can be easily detached by treatment under mild alkaline conditions is formed. Furthermore, the printed layer formed from the liquid composition described above not only has excellent detachability, but also has excellent properties as a printed material, such as blocking resistance, heat resistance, gloss, and wet friction resistance. Therefore, the laminate of this embodiment is excellent in recyclability, as well as in handleability and design.

[0095] A specific example of the laminate configuration is a laminate (laminate-1) comprising a first substrate and a printed layer formed from a liquid composition. This laminate-1 may further comprise layers other than the first substrate and the printed layer. Examples of other layers include a pattern layer formed using printing ink, and a vapor-deposited layer formed by vapor-depositing a metal or metal oxide such as aluminum or silica.

[0096] After applying the liquid composition to the first substrate, the volatile components are removed to form a printed layer on the first substrate. The liquid composition can be easily and stably applied to the first substrate using a gravure coater, knife coater, reverse coater, bar coater, spray coater, slit coater, or the like. In consideration of releasability, the thickness of the printed layer is preferably 0.5 to 3 μm, and more preferably 1 to 2 μm.

[0097] Another specific example of a laminate configuration is one in which a second substrate is further provided in addition to the laminate-1 (laminate-2). That is, the laminate-2 is a laminate having a so-called laminate structure, which includes a first substrate, a second substrate, and a printed layer. The laminate-2 may further include layers other than the first substrate, the second substrate, and the printed layer. Examples of other layers include a pattern layer formed using printing ink, and a vapor-deposited layer formed by vapor-depositing a metal or metal oxide such as aluminum or silica. The laminate-2 may also be a laminate film in which a first substrate, a printed layer, an adhesive layer, and a second substrate are laminated in this order.

[0098] The laminate film can be easily produced, for example, by the following method. First, an adhesive is applied to the surface of the printed layer of the laminate-1 to form an adhesive layer. Next, a second substrate is attached to the surface of the formed adhesive layer to produce the laminate film.

[0099] As the substrates such as the first substrate and the second substrate, plastic films formed from resins such as polyethylenes such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), etc.; polypropylene; polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); nylon (NY); polystyrene; etc. can be used. Paper substrates can also be used. The surface of the substrate may be corona discharge treated. The substrate may be made of recycled materials recovered after being used as printed matter. The substrate may be stretched or unstretched. The substrate may be one on which metals or metal oxides such as silica, alumina, and aluminum are vapor-deposited, or one on which the vapor-deposited surface is coated with a paint such as polyvinyl alcohol.

[0100] The shape of the substrate is not particularly limited, and a substrate of a shape according to the purpose can be used. Specific examples of the shape of the substrate include a film and a sheet. By applying a liquid composition such as ink to the surface of the substrate by a general printing method such as gravure printing, a removable printed layer having a desired design, information, etc. can be formed, and the desired laminate can be obtained.

[0101] The laminate of this embodiment, which includes a printed layer formed from a liquid composition such as the ink, medium, primer, or overcoat varnish, is useful, for example, as a label or packaging. More specifically, the laminate of this embodiment is suitable for containers that hold food products, soft drinks, cosmetics, seasonings, medicines, sanitary products, etc.; labels that are attached to these containers; resin bags (packaging materials) that hold foods such as bread, rice balls, and side dishes; etc.

[0102] <How to remove the printed layer> One embodiment of the method for removing a printed layer of the present invention includes a step of contacting the printed layer of the laminate with an alkaline aqueous solution to remove and remove the printed layer from the substrate. The printed layer provided on the substrate constituting the laminate is a layer formed from the liquid composition, and therefore can be easily removed under mild alkaline conditions.

[0103] To remove the printed layer disposed on the substrate, the laminate can be immersed in an alkaline aqueous solution, for example, to bring the printed layer into contact with the alkaline aqueous solution. The alkaline aqueous solution can be prepared by dissolving various alkalis in water. Examples of alkalis include ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate. From the viewpoint of versatility, it is preferable to use an aqueous sodium hydroxide solution as the alkaline aqueous solution. By immersing the laminate in a 1 to 7.5 mass % aqueous sodium hydroxide solution for 5 to 60 minutes, the printed layer can be easily removed from the substrate, resulting in a clean, recyclable substrate. The temperature of the alkaline aqueous solution, such as the sodium hydroxide aqueous solution, in which the laminate is immersed can be set to room temperature (25°C) to 90°C.

[0104] For example, when treating the aforementioned laminate-2, the laminate-2 is immersed in a 1.5% by mass aqueous solution of sodium hydroxide and stirred for about 30 minutes at 80° C. This allows the printed layer to be detached from the first substrate and the second substrate.

[0105] The removal method of the present embodiment preferably further includes a step of recovering the substrate from which the printed layer has been removed. For example, if 80% or more of the printed layer has been peeled off from the substrate, the substrate can be reused as a recycled film simply by cleaning the surface by washing with water, drying, or the like. [Example]

[0106] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0107] <Preparation of various raw materials> (Binder resin (A)) As the binder resin (A), the following A-1 to A-3 were prepared. A-1: 21% cellulose resin (nitrocellulose resin, product name "RS1 / 2", manufactured by Kimia) 38% polyamide resin solution (polyamide resin, trade name "Reomaid S-7100", manufactured by Kao Corporation, acid value 5 mg KOH / g or less, amine value 2 mg KOH / g or less) A-2: 30% polyurethane resin (polyurethane resin, product name "TA24-215E", manufactured by Resonac Corporation, non-toluene type polyurethane resin solution for gravure ink, viscosity 800-1300 mPa·s (25°C), amine value less than 1 mgKOH / g) 20% vinyl chloride-vinyl acetate copolymer resin (vinyl chloride-vinyl acetate resin) (vinyl chloride-vinyl acetate copolymer resin, trade name "Solvine A", manufactured by Nissin Chemical Industry Co., Ltd., vinyl chloride (VC) content 92%, vinyl acetate (VAc) content 3%, vinyl alcohol (VA) content 5%, hydroxyl value 69.3 mg KOH / g, Tg 76°C, Mw 73,000, Mn 35,000) A-3: 20% cellulose resin (cellulose acetate butyrate (CAB) resin, trade name "CAB381-0.5", manufactured by Eastman Chemical Co., Mn 30,000, acetyl content 13.5%, butyl content 38%, hydroxyl content 1.3%, Tg 130°C) 40% acrylic resin (acrylic resin, product name "Dianal BR106", manufactured by Mitsubishi Chemical Corporation, Mw 60,000, Tg 50°C, acid value 3.5 mg KOH / g)

[0108] (Resin (B)) Resins (B) of the type shown in Table 1 were prepared.

[0109] TIFF2025152328000001.tif75170

[0110] (Resin (C)) The types of resins (C) shown in Table 2 were prepared.

[0111] TIFF2025152328000002.tif108170

[0112] (Other ingredients) The following ingredients were prepared: Wax: Polyethylene wax, product name "Hiwax 220P", manufactured by Mitsui Chemicals Chelate crosslinking agent: Product name "TC-100", manufactured by Matsumoto Fine Chemical Co., Ltd.

[0113] (organic solvent) As the organic solvent (D), the following D-1 to D-3 were prepared. D-1: A mixed solvent of methylcyclohexane, n-propyl acetate, and isopropanol in a ratio of 5:3:2 (by mass) D-2: A mixed solvent of methyl ethyl ketone, toluene, and isopropanol in a ratio of 5:3:2 (by mass) D-3: n-propyl acetate: isopropanol = 5:5 (mass ratio) mixed solvent

[0114] <Ink preparation> The components were mixed to obtain mixtures with the compositions (units: %) shown in the upper rows of Tables 3-1 to 3-4. The resulting mixtures were kneaded using a paint shaker to prepare inks.

[0115] TIFF2025152328000003.tif255157

[0116] TIFF2025152328000004.tif255156

[0117] TIFF2025152328000005.tif255157

[0118] TIFF2025152328000006.tif255157

[0119] <Production of laminate> The following three types of substrate films were prepared. OPP film with one side corona discharge treated (product name "FOH", manufactured by Futamura Chemical Co., Ltd., thickness 25 μm) PET film with one side corona discharge treated (product name "E5102", manufactured by Toyobo Co., Ltd., thickness 25 μm) Nylon film with one side corona discharge treated (product name "Harden N1102", manufactured by Toyobo Co., Ltd., thickness 15 μm)

[0120] The prepared ink was diluted with a mixed solvent (methylcyclohexane / propyl acetate / isopropyl alcohol). The diluted ink was applied to the treated surface of each substrate film by gravure printing using a 70-line heliostat. This resulted in a laminate with a printed layer (100 mm x 150 mm solid layer, 1 μm thick) formed on the substrate film.

[0121] <Evaluation> (blocking resistance) The surface of the printed layer was placed on the non-printed side of the same base film to prepare a test piece, and a pressure of 4 kg / cm 2 The test pieces were stored in a thermostatic chamber at 40°C for 24 hours with a load of 1000 kJ / cm2 applied. After storage, the test pieces were peeled off and the blocking resistance of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Table 4. 5: The area ratio of the printed layer transferred to the non-printed surface was 0% or more and less than 10%. 4: The area ratio of the printed layer transferred to the non-printed surface was 10% or more and less than 20%. 3: The area ratio of the printed layer transferred to the non-printed surface was 20% or more but less than 50%. 2: The area ratio of the printed layer transferred to the non-printed surface was 50% or more but less than 80%. 1: The area ratio of the printed layer transferred to the non-printed surface was 80% or more and 100% or less.

[0122] (heat resistance) A test piece was prepared by overlapping the surface of the printed layer with soft aluminum foil. Using a heat seal tester (product name "TP-701-C Heat Seal Tester", manufactured by Tester Sangyo Co., Ltd.), a test piece was applied from the aluminum foil to the test piece at 110 to 150°C and 2 kg / cm. 2 After heating, the test piece was peeled off and the heat resistance of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Table 4. 5: The ink did not adhere to the aluminum foil even when heated to 150°C. 4: When heated to 140°C, the ink did not adhere to the aluminum foil, but when heated to 150°C, the ink was removed. 3: When heated to 130°C, the ink did not adhere to the aluminum foil, but when heated to 140°C, the ink was removed. 2: When heated to 120°C, the ink did not adhere to the aluminum foil, but when heated to 130°C, the ink was removed. 1: The ink was absorbed onto the aluminum foil when heated to less than 120°C.

[0123] (glossiness) Using a gloss meter (product name "micro-TRI-gloss S", manufactured by BYK), the gloss value at a 60° angle of the printed layer formed on the OPP film was measured, and the gloss of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Table 4. 5: The gross value was 70 or more. 4: Gross value was 65 or more and less than 70. 3: The gross value was 60 or more and less than 65. 2: The gross value was 50 or more and less than 60. 1: The gross value was less than 50.

[0124] (Wet friction resistance) A rubbing test was conducted using a Gakushin-type rubbing fastness tester (product name "AB-301", manufactured by Tester Sangyo Co., Ltd.) in which a water-soaked black cloth (cotton No. 3-1, gold cloth No. 3) was rubbed back and forth 100 times with a load of 200 gf applied to the surface of the printed layer. After the rubbing test, the appearance of the printed layer was visually inspected, and the wet rubbing resistance of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Table 4. 5: The area ratio of the printed layer that migrated to the black cloth side was 0% or more and less than 10%. 4: The area ratio of the printed layer that migrated to the black cloth side was 10% or more but less than 20%. 3: The area ratio of the printed layer that migrated to the black cloth side was 20% or more but less than 50%. 2: The area ratio of the printed layer that migrated to the black cloth side was 50% or more but less than 80%. 1: The area ratio of the printed layer that migrated to the black cloth side was 80% or more and 100% or less.

[0125] (detachment) The laminate was immersed in a 1.5% aqueous sodium hydroxide solution at 70°C and stirred for 5 minutes. After removing the laminate from the aqueous sodium hydroxide solution and rinsing it with water, it was visually observed and the releasability of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Table 4. 5: The printed layer was completely detached. 4: Part of the printed layer remained on the base film. 3: About half of the printed layer remained on the base film. 2: Most of the printed layer remained on the base film. 1: The printed layer was not detached at all.

[0126] TIFF2025152328000007.tif248170

[0127] Furthermore, the same tests as in Examples 2 and 3 were carried out except that a curing agent (trade name "Coronate HL", manufactured by Tosoh Corporation) was added. As a result, the evaluation was similar to that of Examples 2 and 3, and the wet friction resistance was particularly evaluated as good.

[0128] (Application example) Using the prepared ink, a laminate having the layer structure of the aforementioned "Laminate-2" was produced and subjected to the same tests as above. As a result, it was confirmed that the ink was excellent in all evaluations, similar to Examples 1 to 19. [Industrial Applicability]

[0129] The liquid composition of the present invention is useful as an ink, medium, primer, overcoat varnish, etc. for forming an alkali-releasable printing layer. By using the liquid composition of the present invention, a resin laminate that can be easily recycled can be obtained.

Claims

1. A resin composition for preparing a liquid composition for forming a detachable printing layer, The binder resin (A), the resin (B) for imparting releasability and having an acid value of 60 to 300 mgKOH / g, and the resin (C) having an acid value of 10 to 55 mgKOH / g and an amine value of 15 mgKOH / g or less, The binder resin (A) is any combination of the following (A-1), (A-2), and (A-3): The content of the resin (B) is 2 to 20 mass% based on the solid content (excluding pigments), The content of the resin (C) is 2 to 20 mass% based on the solid content (excluding pigments), A resin composition in which the content of the resin (C) relative to 1 part by mass of the resin (B) is 0.3 to 3.2 parts by mass. (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin

2. The resin composition according to claim 1, wherein the resin (B) is at least one selected from the group consisting of a rosin-maleic acid resin, a styrene-acrylic acid resin, a styrene-maleic acid resin, a hydrogenated rosin resin, and a terpene phenol resin.

3. 2. The resin composition according to claim 1, wherein the resin (C) is at least one selected from the group consisting of carboxylic acid compounds, phosphoric acid ester compounds, phosphonic acid compounds, phosphinic acid compounds, and acid alkyl ester compounds.

4. The resin composition according to claim 1, further comprising a curing agent.

5. The binder resin (A), the resin (B) for imparting releasability and having an acid value of 60 to 300 mgKOH / g, and the resin (C) having an acid value of 10 to 55 mgKOH / g and an amine value of 15 mgKOH / g or less, The binder resin (A) is any combination of the following (A-1), (A-2), and (A-3): The content of the resin (B) is 2 to 20 mass% based on the solid content (excluding pigments), The content of the resin (C) is 2 to 20 mass% based on the solid content (excluding pigments), A liquid composition for forming a detachable printing layer, in which the content of the resin (C) per 1 part by mass of the resin (B) is 0.3 to 3.2 parts by mass. (A-1) Combination of cellulose resin and polyamide resin (A-2) Combination of polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (A-3) Combination of cellulose resin and (meth)acrylic resin

6. The resin (B) is at least one selected from the group consisting of rosin-maleic acid resin, styrene-acrylic acid resin, styrene-maleic acid resin, hydrogenated rosin resin, and terpene phenol resin. The liquid composition according to claim 5.

7. 6. The liquid composition according to claim 5, wherein the resin (C) is at least one selected from the group consisting of carboxylic acid compounds, phosphoric acid ester compounds, phosphonic acid compounds, phosphinic acid compounds, and acid alkyl ester compounds.

8. The liquid composition according to claim 5, further comprising a curing agent.

9. 6. The liquid composition according to claim 5, which is an ink, a medium, a primer, or an overcoat varnish.

10. A laminate comprising a resin substrate and a printed layer formed from the liquid composition according to any one of claims 5 to 9, disposed on the substrate.

11. The laminate according to claim 10, which is a label or packaging material.

12. A method for removing a printed layer, comprising the step of contacting the printed layer of the laminate according to claim 10 with an alkaline aqueous solution to remove the printed layer from the substrate.

13. The method for removing a printed layer according to claim 12, further comprising the step of recovering the substrate from which the printed layer has been removed.

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