Resin composition, liquid composition, laminate, and method for removing printed layer

Abstract

The present invention provides a resin composition for preparing liquid compositions such as inks with excellent fluidity, which can form a printed layer with excellent blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption properties on a substrate made of A-PET, HDPE, LLDPE, etc., while suppressing whitening of the substrate. [Solution] This is a resin composition used in a liquid composition for forming a detachable printing layer on a substrate made of a resin such as A-PET. It contains (meth)acrylic resin (A) with an acid value of less than 25 mg KOH / g, styrene-(meth)acrylic resin (B) with an acid value of 25 to 90 mg KOH / g, and a dispersion resin (C) with an acid value of 150 to 400 mg KOH / g. The total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) in the solid content of the resin composition is 10 to 30% by mass, and the content of dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of styrene-(meth)acrylic resin (B).

Description

Technical Field

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

Background Art

[0002] Plastic products such as various containers and packaging materials formed of plastic are widely used around the world including the food field due to the excellent properties of plastics. Plastic products are light, durable, and suitable for mass production, and thus have become indispensable to modern life. For example, amorphous polyethylene terephthalate (A-PET) is a plastic that has gloss, high transparency, and is easy to mold. Taking advantage of such properties, A-PET is widely used as a constituent material for products such as containers and packaging materials for foods including salads, prepared dishes, sushi, and sashimi. In addition, high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) are also widely used as constituent materials for products such as garbage bags and rice bags.

[0003] On the surface of various products formed of plastic materials, various types of information such as product names, contents, and manufacturers are usually directly printed with ink, or resin labels on which various types of information are printed are attached. In addition, various types of information such as product names are usually printed with ink on the surface of resin bags for containing bread, rice balls, prepared dishes, and the like.

[0004] From the viewpoint of global environmental protection and the like, various molded articles (base materials) such as these containers, labels, and bags are collected, recycled, and widely used as secondary products. However, as described above, various types of information are printed with ink on the surfaces of these base materials. For this reason, when recycling and reusing resin molded articles and labels, it is necessary to remove the ink applied to these surfaces in advance.

[0005] Various methods have been proposed to recycle plastic substrates by desorbing and removing ink printed on them. For example, methods for manufacturing packaging materials and recycled molding materials with excellent desorption properties for printed substrates have been proposed (Patent Documents 1 and 3). In addition, an organic solvent-based ink containing a urethane resin having an acidic group at its end has been proposed for forming a desorption layer to peel plastic films from laminates (Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-036097 [Patent Document 2] Japanese Patent Publication No. 2023-88345 [Patent Document 3] Patent No. 7546182 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the printed layers formed using conventional inks, etc., as proposed in Patent Documents 1 and 2, did not necessarily exhibit good adhesion to substrates made of polyester resins such as A-PET or polyolefin resins such as polyethylene, nor did they exhibit good detachability from these substrates through alkaline treatment. Furthermore, the properties of detachable printed layers formed using conventional inks, etc., such as blocking resistance, abrasion resistance, and heat resistance, were not necessarily sufficient, and further improvements were needed.

[0008] The present invention has been made in view of the problems of the prior art, and its objective is to provide a resin composition for preparing a liquid composition such as an ink that can form a printed layer with excellent storage stability (flowability), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption on a substrate made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, etc., while suppressing whitening of the substrate.

[0009] Furthermore, an object of the present invention is to provide a liquid composition such as an ink that can form a printed layer with excellent storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption on a substrate made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, etc., while suppressing whitening of the substrate. Moreover, an object of the present invention is to provide a detachable printed layer formed with the above liquid composition, a laminate comprising this detachable printed layer, and a method for detaching the printed layer from this laminate. [Means for solving the problem]

[0010] In other words, the present invention provides the following resin composition. [1] A resin composition used in a liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, comprising: (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g; styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g; and a dispersion resin (C) having an acid value of 150 to 400 mgKOH / g, wherein the total content of the styrene-(meth)acrylic resin (B) and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30 mg by mass. A resin composition wherein the content of the dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of the styrene-(meth)acrylic resin (B), the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass, and the liquid composition contains a solvent including an alcohol-based solvent and an ester-based solvent, the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. [2] The resin composition according to [1], wherein the glass transition temperature of the (meth)acrylic resin (A) is 40 to 65°C. [3] The resin composition according to [1] or [2], wherein the content of the (meth)acrylic resin (A) in the solid content (excluding colorants such as pigments) of the liquid composition is 40 to 75% by mass. [4] The resin composition according to any one of [1] to [3], wherein the dispersion resin (C) is at least one selected from the group consisting of carboxylic acid resins and ammonium salt resins. [5] The resin composition according to any one of [1] to [4], further containing silica having an average particle size of 1.0 to 8.0 μm. [6] The resin composition according to any one of [1] to [5], further containing a cellulose resin.

[0011] Furthermore, the present invention provides the following liquid compositions. [7] A liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, comprising: a solvent containing an alcohol-based solvent and an ester-based solvent; a printing composition for forming a non-detachable printing layer; and the resin composition according to any one of [1] to [6], wherein the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. [8] A liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, comprising: (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g; styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g; a dispersion resin (C) having an acid value of 150 to 400 mgKOH / g; and a solvent containing an alcohol-based solvent and an ester-based solvent, wherein the solid content of the liquid composition (excluding colorants such as pigments) is the styrene-(meth)acrylic resin (B) A liquid composition wherein the total content of (meth)acrylic resin (A) and the dispersion resin (C) is 10 to 30% by mass, the content of the dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of the styrene-(meth)acrylic resin (B), the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100% by mass, the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. [9] The liquid composition according to [7] or [8], wherein the alcohol-based solvent is at least one selected from the group consisting of isopropyl alcohol, methanol, ethanol, n-propanol, and n-butanol.

[10] The liquid composition according to any one of [7] to [9], wherein the ester solvent is at least one selected from the group consisting of ethyl acetate, propyl acetate, and butyl acetate.

[11] The liquid composition according to any one of [7] to

[10] , wherein when a cellophane tape is quickly peeled off from a part of the surface of a printed layer formed by coating the liquid composition onto the substrate, the ratio of the area of ​​the peeled printed layer to the adhesive area of ​​the cellophane tape is less than 20%.

[0012] Furthermore, the present invention provides the use of the following liquid compositions in inks and the like, and provides inks and the like.

[12] Use of the liquid composition described in any of [7] to

[11] above in an ink having a medium, primer, overcoat varnish, or colorant.

[13] An ink having a medium, primer, overcoat varnish, or colorant, which is obtained by using any of the liquid compositions described in [7] to

[11] above.

[0013] Furthermore, the present invention provides the following detachable printed layer and laminate.

[14] A removable printing layer formed of an ink having a medium, primer, overcoat varnish, or colorant as described in

[13] , disposed on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene.

[15] A laminate comprising a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, and a detachable printed layer as described in

[14] disposed on the substrate.

[16] The laminate described in

[15] , which is a container or lid material.

[0014] Furthermore, the present invention provides the following method for removing the printed layer.

[17] A method for detaching a printed layer, comprising the step of bringing an aqueous alkali solution into contact with the printed layer of the laminate according to

[15] or

[16] to detach and remove the printed layer from the substrate.

[18] The method for detaching a printed layer according to

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

Effects of the Invention

[0015] According to the present invention, it is possible to provide a resin composition for preparing a liquid composition such as an ink, which is capable of forming a printed layer excellent in storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali detachability on a substrate composed of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, or the like while suppressing whitening of the substrate.

[0016] Further, according to the present invention, it is possible to provide a liquid composition such as an ink, which is capable of forming a printed layer excellent in storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali detachability on a substrate composed of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, or the like while suppressing whitening of the substrate. Furthermore, according to the present invention, there can be provided a detachable printed layer formed from the above liquid composition, a laminate comprising the detachable printed layer, and a method for detaching the printed layer from the laminate.

Modes for Carrying Out the Invention

[0017] The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. The inventors have investigated resin compositions for preparing a liquid composition that can form a printed layer with excellent storage stability, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption on the surface of various molded articles (substrates) made of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE), while suppressing whitening of the substrate. Furthermore, the inventors have investigated a liquid composition that can form a printed layer with excellent storage stability, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption on substrates made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, etc., while suppressing whitening of the substrate. As a result, we discovered that when a liquid composition containing an alcohol-based solvent and an ester-based solvent in predetermined proportions, and containing a resin composition in predetermined proportions of a (meth)acrylic resin, a styrene-(meth)acrylic resin, and a dispersion resin, each having an acid value within a certain range, is prepared and used on the surface of the substrate, it is possible to form a printed layer with improved storage stability, adhesion, alkali desorption, blocking resistance, abrasion resistance, and heat resistance without causing whitening of the substrate, leading to the present invention.

[0018] <Resin composition> One embodiment of the resin composition of the present invention is a resin composition used in a liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE), and contains a (meth)acrylic resin (A) with an acid value of less than 25 mgKOH / g, a styrene-(meth)acrylic resin (B) with an acid value of 25 to 90 mgKOH / g, and a dispersion resin (C) with an acid value of 150 to 400 mgKOH / g. The total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass, and the content of dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of styrene-(meth)acrylic resin (B). Furthermore, the total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass. The liquid composition prepared using the resin composition of this embodiment contains a solvent including an alcohol-based solvent and an ester-based solvent, with the total content of the alcohol-based solvent and the ester-based solvent being 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent being 2.5:7.5 to 7:3. The details of the resin composition of this embodiment will be described below.

[0019] ((Meth)acrylic resin (A)) (Meth)acrylic resin (A) is a component used to improve properties such as blocking resistance, adhesion, abrasion resistance, and heat resistance of the printed layer. (Meth)acrylic resin (A) is a resin (polymer) whose main component is a structural unit derived from (meth)acrylate ((meth)acrylic acid ester). Examples of (meth)acrylic resin (A) include homopolymers of (meth)acrylate; copolymers of multiple types of (meth)acrylate; copolymers of (meth)acrylate and other polymerizable monomers copolymerizable with (meth)acrylate; and so on. In this specification, "(meth)acrylic" means either "acrylic" or "methacrylic". The content of structural units derived from (meth)acrylate in (meth)acrylic resin (A) is preferably 10 to 100% by mass, and more preferably 20 to 100% by mass.

[0020] Examples of (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and the like.

[0021] Other polymerizable monomers copolymerizable with (meth)acrylate include conjugated diene compounds such as 1,3-butadiene, isoprene, and chloroprene; aromatic vinyl compounds such as styrene, α-methylstyrene, halogenated styrene, and divinylbenzene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid; and unsaturated carboxylic acid esters such as diethyl maleate, dibutyl maleate, dibutyl fumarate, diethyl itaconate, and dibutyl itaconate.

[0022] The acid value of (meth)acrylic resin (A) is less than 25 mgKOH / g, preferably 0 to 18 mgKOH / g, and more preferably 0 to 12 mgKOH / g from the viewpoint of adhesion and heat resistance. The acid value of (meth)acrylic resin (A) may be 0. By keeping the acid value of (meth)acrylic resin (A) within the above range, the adhesion of the printed layer to the substrate and the heat resistance can be improved. If the acid value of (meth)acrylic resin (A) is 25 mgKOH / g or more, the adhesion and water resistance of the printed layer formed on the substrate made of A-PET and LLDPE will be insufficient. The acid value in this specification is the value measured by the neutralization titration method in accordance with JIS K 0070-1992.

[0023] The glass transition temperature of (meth)acrylic resin (A) is preferably 40 to 65°C, and more preferably 40 to 62°C. By setting the glass transition temperature of (meth)acrylic resin (A) within the above range, the blocking resistance and adhesion to the substrate of the printed layer can be further improved.

[0024] The weight-average molecular weight of (meth)acrylic resin (A) is preferably 1,000 to 1,000,000, and more preferably 5,000 to 500,000. By keeping the weight-average molecular weight of (meth)acrylic resin (A) within the above range, storage stability, blocking resistance of the printed layer, and adhesion to the substrate can be further improved. In particular, from the viewpoint of improving the balance between storage stability, blocking resistance of the printed layer, and adhesion to the substrate, the weight-average molecular weight of (meth)acrylic resin (A) is preferably 10,000 to 390,000.

[0025] (Meth)acrylic resin (A) can be obtained by polymerizing a monomer component comprising (meth)acrylate and other polymerizable monomers as needed. Polymerization methods include polymerizing the monomer component in the presence of a known radical polymerization initiator by solution polymerization, bulk polymerization, emulsion polymerization, etc. (Meth)acrylic resin (A) may also be a self-crosslinking resin.

[0026] As (meth)acrylic resin (A), in addition to those manufactured according to conventional methods, commercially available products can be used. Commercially available resins that can be used as (meth)acrylic resin (A) include, for example, Taisei Fine Chemical's "Acrit" series, and Seikoh PMC's "Hiros-X TE-1048", "Hiros-X NE-2186", "Hiros-X KE-1062", "Hiros-X QE-1042", "Hiros-X X-436", "Hiros-X KE-1060", "Hiros-X HE-2342", "Hiros-X HE-1335", "Hiros-X RE-1075", "Hiros-X PE-1304", "Hiros-X KE-2536", "Hiros-X J-140A", "Hiros-X TE-1102", "Hiros-X RE-218", "Hiros-X NE-2009", "Hiros-X JE-1056", "Hiros-X KE-1148", and "Hiros-X "M-141", "Hyros-X ME-2039", "Hyros-X UE-1051", "Hyros-X PE-1126", "Hyros-X JE-1113", "Hyros-X PL-1231", "Hyros-X BL-2300", "Hyros-X NL-1253", "Hyros-X X-228L", "Hyros-X M-30", "Hyros-X UL-1191", "Hyros-X YL-1098", "Hyros-X QL-1358", "Hyros-X YL-1825", "Hyros-X X-345", "Hyros-X GL-2439", "Hyros-X VL-1147", "Hyros-X X-321L", "Hyros-X AW-36H", and "Hyros-X NL-1189"; Aica Kogyo Co., Ltd. product names "Ultrazol A-25", "Ultrazol "A-35", "Ultrazole A-40", "Ultrazole A-50", "Ultrazole C-63", "Ultrazole C-70", "Ultrazole D-32", "Ultrazole D-40", "Ultrazole GP-300", and "Ultrazole UL-1097";Product names manufactured by BASF Japan: "Joncryl PDX-7357", "Joncryl PDX-7182", "Joncryl PDX-7326", "Joncryl PDX-7616A", "Joncryl PDX-7732", "Joncryl PDX-7741", "Joncryl PDX-7787", "Joncryl PDX-7356", "Joncryl PDX-7734", "Joncryl PDX-7777", "Joncryl PDX-7615", "Joncryl PDX-7775", "Joncryl PDX-7692", "Joncryl PDX-7630A", "Joncryl PDX-7158", "Joncryl 352D", "Joncryl PDX-7199", "Joncryl PDX-7358", "Joncryl PDX-7667", "Joncryl PDX-7700", "Joncryl PDX-7696", Examples include "Johncryl PDX-7780", "Johncryl PDX-7177", "Johncryl PDX-7164", "Johncryl PDX-7430", "Johncryl 67", "Johncryl 678", "Johncryl 611", "Johncryl 693", "Johncryl 682", "Johncryl 690", "Johncryl 819", "Johncryl JDX-C3000A", "Johncryl JDX-C3080", "Johncryl 52J", "Johncryl PDX-6157", "Johncryl 60J", "Johncryl 70J", "Johncryl JDX-6180", "Johncryl HPD-196", "Johncryl HPD-96J", "Johncryl PDX-6137A", "Johncryl 6610", "Johncryl JDX-6500", and "Johncryl PDX-6102B"; etc.

[0027] The content of (meth)acrylic resin (A) in the solid content (excluding colorants such as pigments) of the liquid composition may be set appropriately depending on the intended use. For example, the content of (meth)acrylic resin (A) is preferably 40 to 75% by mass, more preferably 50 to 70% by mass, and particularly preferably 59 to 65% by mass, based on the solid content in the liquid composition, from the viewpoint of superior blocking resistance, adhesion, and alkali desorption of the printed layer. By setting the content of (meth)acrylic resin (A) within the above range, the blocking resistance, adhesion, and alkali desorption of the printed layer can be improved. If the content of (meth)acrylic resin (A) is less than 40% by mass, the adhesion of the ink layer may be poor, and if it is more than 75% by mass, the alkali desorption and blocking resistance of the ink layer may be poor, but in either case, the objectives of the present invention can be achieved.

[0028] The solid content of (meth)acrylic resin (A) in the total mass of the liquid composition (excluding colorants such as pigments) can be set appropriately according to the intended use. For example, the solid content of (meth)acrylic resin (A) is preferably 1 to 50% by mass, more preferably 3 to 35% by mass, and particularly preferably 5 to 20% by mass, based on the total mass of the liquid composition, from the viewpoint of better storage stability of the ink, resistance to blocking of the printed layer, adhesion, and alkali desorption. By setting the solid content of (meth)acrylic resin (A) within the above range, storage stability, resistance to blocking of the printed layer, adhesion, and alkali desorption can be improved. If the solid content of (meth)acrylic resin (A) is less than 1% by mass, the adhesion of the ink layer may be poor, and if it is more than 50% by mass, the alkali desorption and resistance to blocking of the ink layer may be poor, but in either case, the objectives of the present invention can be achieved.

[0029] (Styrene-(meth)acrylic resin (B)) Styrene-(meth)acrylic resin (B) is a resin with a higher acid value than (meth)acrylic resin (A). By using (meth)acrylic resin (A) and styrene-(meth)acrylic resin (B), which have different acid values, in combination, alkali desorption properties can be imparted while maintaining adhesion and heat resistance. Styrene-(meth)acrylic resin (B) is a resin (polymer) having constituent units derived from styrene and constituent units derived from (meth)acrylate ((meth)acrylic acid ester). Styrene-(meth)acrylic resin (B) is the same as the aforementioned (meth)acrylic resin (A), except that it has constituent units derived from styrene as essential constituent units and has a different acid value.

[0030] The acid value of styrene-(meth)acrylic resin (B) is 25 to 90 mgKOH / g, preferably 26 to 90 mgKOH / g, more preferably 30 to 90 mgKOH / g, and particularly preferably 50 to 90 mgKOH / g from the viewpoint of further improving alkali desorption properties. By keeping the acid value of styrene-(meth)acrylic resin (B) within the above range, the adhesion and alkali desorption properties of the printed layer can be improved. If the acid value of styrene-(meth)acrylic resin (B) is less than 25 mgKOH / g, the alkali desorption properties of the printed layer will be insufficient. On the other hand, if the acid value of (meth)acrylic resin (B) is greater than 80 mgKOH / g, the adhesion of the printed layer formed on a substrate made of HDPE and LLDPE will be insufficient.

[0031] By using styrene-(meth)acrylic resin (B) in combination with the dispersion resin (C) described later, the alkali-desorbing properties of the printed layer can be further improved. When printing on substrates made of polyester resin or polyolefin resin, such as polyester resin substrates like A-PET, these substrates have relatively low solvent resistance. Therefore, when a liquid composition such as an ink containing a solvent is applied, the substrate is slightly dissolved by the solvent while the printed layer is formed. As a result, the formed printed layer adheres more firmly to the substrate than a printed layer formed on a substrate made of other resins. In other words, typically, printed layers formed on substrates made of polyester resin or polyolefin resin, such as A-PET, tend to be more difficult to desorb by alkali than printed layers formed on substrates made of other resins. In contrast, by using the resin composition or liquid composition of this embodiment, which uses styrene-(meth)acrylic resin (B) and dispersion resin (C) in combination, it is possible to form a printed layer with excellent alkali-desorbing properties even when using a substrate made of polyester resin or polyolefin resin, such as A-PET.

[0032] As styrene-(meth)acrylic resin (B), either a resin manufactured by conventional methods or a commercially available product can be used. Examples of commercially available resins that can be used as styrene-(meth)acrylic resin (B) include the "Acrit" series manufactured by Taisei Fine Chemical Co., Ltd., and "Hyros-X X-609" and "Hyros-X X-1" manufactured by Seikoh PMC Co., Ltd.

[0033] The content of styrene-(meth)acrylic resin (B) in the solid content (excluding colorants such as pigments) of the liquid composition may be set appropriately depending on the intended use. For example, the content of styrene-(meth)acrylic resin (B) is preferably 4 to 28% by mass, more preferably 5 to 17% by mass, and particularly preferably 6 to 14% by mass, based on the solid content in the liquid composition, from the viewpoint of better blocking resistance and alkali desorption of the printed layer. By setting the content of styrene-(meth)acrylic resin (B) within the above range, the blocking resistance and alkali desorption of the printed layer can be improved. If the content of styrene-(meth)acrylic resin (B) is less than 4% by mass, alkali desorption may be poor, and if it is more than 28% by mass, blocking resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0034] The solid content of styrene-(meth)acrylic resin (B) in the total mass of the liquid composition (excluding colorants such as pigments) can be appropriately set according to the intended use. For example, the solid content of styrene-(meth)acrylic resin (B) is preferably 0.1 to 10.0% by mass, more preferably 1.0 to 8.0% by mass, and particularly preferably 1.0 to 6.0% by mass, based on the total mass of the liquid composition, from the viewpoint of superior blocking resistance, alkali desorption resistance, and water resistance of the printed layer. By setting the styrene-(meth)acrylic resin (B) content within the above range, storage stability, blocking resistance, and alkali desorption resistance of the printed layer can be improved. If the solid content of styrene-(meth)acrylic resin (B) is less than 0.1% by mass, alkali desorption resistance may be poor, and if it exceeds 10.0% by mass, blocking resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0035] (Dispersion resin (C)) The dispersion resin (C) is a resin other than (meth)acrylic resin (A) and styrene-(meth)acrylic resin (B), and is a component that contributes to improving the alkali desorption properties of the printed layer. Furthermore, if the liquid composition prepared using the resin composition of this embodiment contains a pigment component, the dispersion resin (C) can also function as a dispersant to improve dispersibility in the liquid medium. In other words, by using the dispersion resin (C), it is possible to improve pigment dispersibility and enhance the alkali desorption properties of the formed printed layer.

[0036] The acid value of the dispersion resin (C) is 150 to 400 mgKOH / g, preferably 170 to 390 mgKOH / g, and more preferably 200 to 380 mgKOH / g from the viewpoint of further improving alkali desorption and adhesion. By setting the acid value of the dispersion resin (C) within the above range, the alkali desorption, adhesion, and pigment dispersibility of the printed layer can be improved. If the acid value of the dispersion resin (C) is less than 150 mgKOH / g, the alkali desorption of the printed layer and the adhesion between HDPE and LLDPE will be insufficient. On the other hand, if the acid value of the dispersion resin (C) is greater than 400 mgKOH / g, the heat resistance and printability of the printed layer will decrease.

[0037] As the dispersion resin (C), carboxylic acid resins, ammonium salt resins, and phosphate ester resins can be used. Among these, carboxylic acid resins are more preferred as the dispersion resin (C) from the viewpoint of improving affinity with the resin. Furthermore, using ammonium salt resins is also a preferred form from the viewpoint of obtaining effects equivalent to those of carboxylic acid resins. Note that "carboxylic acid resin" refers to a resin that has a carboxylic acid group (-COOH) in its molecule. Also, "ammonium salt resin" refers to a resin that has an ammonium salt structure (-NH4) in its molecule. + X - This refers to a resin containing (where "X" represents a halogen atom).

[0038] As the dispersion resin (C), either one manufactured by conventional methods or a commercially available product can be used. Examples of commercially available resins that can be used as the dispersion resin (C) include the product names "DISPERBYK-P104," "BYK-P105," and "DISPERBYK-102" from BYK GmbH; and the product names "Solsperse45000," "Solsperse17000," and "Solsperse16000" from Lubrizol GmbH.

[0039] The content of the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition may be set appropriately depending on the intended use. For example, the content of the dispersion resin (C) is preferably 0.9 to 18% by mass, more preferably 2 to 10% by mass, and particularly preferably 3 to 5.5% by mass, based on the solid content (excluding colorants such as pigments) of the liquid composition. By setting the content of the dispersion resin (C) within the above range, storage stability, alkali desorption properties of the printed layer, and heat resistance can be improved. If the content of the dispersion resin (C) is less than 0.9% by mass, the desorption properties of the printed layer may be poor, and if it is more than 18% by mass, storage stability and heat resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0040] The solid content of the dispersion resin (C) in the total mass of the liquid composition (excluding colorants such as pigments) can be set appropriately according to the intended use. For example, the solid content of the dispersion resin (C) is preferably 0.05 to 5.0% by mass, more preferably 0.1 to 4.0% by mass, and particularly preferably 0.15 to 3.0% by mass, based on the total mass of the liquid composition. By setting the solid content of the dispersion resin (C) within the above range, storage stability, alkali desorption of the printed layer, and heat resistance can be improved. If the solid content of the dispersion resin (C) is less than 0.05% by mass, the desorption of the printed layer may be poor, and if it is more than 5% by mass, storage stability and heat resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0041] The total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass, preferably 10 to 28% by mass, and more preferably 11 to 25% by mass from the viewpoint of further improving blocking resistance, abrasion resistance, heat resistance, and alkali desorption. By keeping the total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) within the above range, the blocking resistance, heat resistance, and alkali desorption of the printed layer can be improved. If the total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) is less than 10% by mass, the alkali desorption of the printed layer decreases. On the other hand, if the total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) exceeds 30% by mass, the blocking resistance of the printed layer formed on substrates made of A-PET and LLDPE decreases, and the heat resistance of the printed layer formed on substrates made of A-PET and HDPE decreases.

[0042] The content of the dispersion resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 0.1 to 1.5 parts by mass per 1 part by mass of styrene-(meth)acrylic resin (B), preferably 0.15 to 1.2 parts by mass, and more preferably 0.3 to 0.8 parts by mass from the viewpoint of further improving blocking resistance, heat resistance, and alkali desorption. By setting the content of the dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) within the above range, the alkali desorption properties of the printed layer can be improved. If the content of the dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) is less than 0.1 parts by mass, the alkali desorption properties of the formed printed layer will decrease. On the other hand, if the content of the dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) is greater than 1.5 parts by mass, the alkali desorption properties of the printed layer formed on a substrate made of A-PET and HDPE will decrease.

[0043] The total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass, and 70 to 100% by mass is more preferable from the viewpoint of further improving adhesion, blocking resistance, and abrasion resistance. By setting the total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition to the above range, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption resistance of the printed layer can be improved. On the other hand, if the total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is less than 65% by mass, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption resistance are inferior.

[0044] (silica) The resin composition may further contain silica. The use of silica can further improve the blocking resistance of the printed layer. The silica may be either naturally occurring or synthetic. Synthetic silica may be synthesized using either a dry or wet method. Known dry methods include combustion and arc methods, while known wet methods include sedimentation and gel methods; silica synthesized by any of these methods may be used. Furthermore, the silica may be crystalline or amorphous, and hydrophobic or hydrophilic. These silicas may be used individually or in combination of two or more types.

[0045] The average particle size of silica is preferably 1.0 to 8.0 μm, and more preferably 2.0 to 6.5 μm. In this specification, "average particle size" refers to the cumulative 50% particle size (median diameter; D) in the volume-based particle size distribution. 50 This means that the silica solid content is preferably 0.3 to 5.0% by mass, and more preferably 0.5 to 3.0% by mass, based on the total solid content of the liquid composition (excluding colorants such as pigments).

[0046] (Cellulose resin) The resin composition may further contain cellulose resin. Using cellulose resin can improve the blocking resistance, abrasion resistance, and heat resistance of the printed layer. Examples of cellulose-based resins include cellulose and cellulose derivatives in which at least some of the hydroxyl groups of cellulose are substituted with other groups, with cellulose derivatives being preferred. Examples of cellulose derivatives include nitrocellulose (nitro group substituted); lower acyl group substituted derivatives such as cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate; lower alkyl group substituted derivatives such as methylcellulose and ethylcellulose; aralkyl group substituted derivatives such as benzylcellulose; and cellulose derivatives having hydroxyalkyl groups such as hydroxyethylcellulose, hydroxypropylcellulose, and hydroxymethylpropylcellulose, with nitrocellulose being preferred. These cellulose-based resins may be used individually or in combination of two or more. The weight-average molecular weight of the cellulose resin is preferably 5,000 to 200,000, and more preferably 10,000 to 100,000.

[0047] The solid content of the cellulose resin is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass, based on the total solid content of the liquid composition (excluding colorants such as pigments). By keeping the cellulose resin content within the above range, it is possible to improve blocking resistance and abrasion resistance while maintaining adhesion to the substrate.

[0048] (Other resins) The resin composition may further contain resins other than (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C). Examples of these other resins include those similar to those commonly found in liquid compositions such as inks, provided they do not affect the effects of this embodiment. More specifically, examples include nitrated cotton, urethane resin, polyamide resin, and chlorinated polypropylene resin.

[0049] (solvent) The resin composition of this embodiment is used in a liquid composition containing an alcohol-based solvent and an ester-based solvent as the main solvents in a certain ratio. It is also preferable to include organic solvents other than alcohol-based and ester-based solvents, or water, to the extent that it does not affect the effects of this embodiment. The solvent content relative to the total mass of the liquid composition is preferably 20-80% by mass, more preferably 25-75% by mass, and particularly preferably 30-70% by mass.

[0050] The liquid composition contains a solvent comprising an alcohol-based solvent and an ester-based solvent. The total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and more preferably 95 to 100% by mass from the viewpoint of further improving storage stability. By using a solvent comprising an alcohol-based solvent and an ester-based solvent, and by keeping the content of these solvents in the solvent within the above range, it is possible to form a printed layer that can suppress whitening of substrates made of A-PET, HDPE, and LLDPE. On the other hand, if the total content of the alcohol-based solvent and the ester-based solvent is less than 90% by mass, the storage stability of the ink will be poor, or the A-PET substrate will whiten.

[0051] Furthermore, the mass ratio of alcohol-based solvent to ester-based solvent in the liquid composition is 2.5:7.5 to 7:3, and more preferably 3:7 to 6.5:3.5 from the viewpoint of suppressing whitening of the substrate and providing better storage stability. By setting the mass ratio of alcohol-based solvent to ester-based solvent in the solvent within the above range, it is possible to form a printed layer that has excellent storage stability and can suppress whitening of substrates made of A-PET, HDPE, and LLDPE.

[0052] Examples of alcohol-based solvents include isopropyl alcohol, methanol, ethanol, n-propanol, and n-butanol. These alcohol-based solvents can be used individually or in combination of two or more. Examples of ester-based solvents include ethyl acetate, propyl acetate, and isobutyl acetate. These ester-based solvents can be used individually or in combination of two or more. When an alcohol-based solvent is used alone, the storage stability of the ink is poor. On the other hand, when an ester-based solvent is used alone, the substrate whitens, and the desired printed material cannot be obtained.

[0053] When alcohol-based solvents and ester-based solvents are not used as the primary solvents, specifically when hydrocarbon-based, ketone-based, glycol ether-based solvents, etc., are used as the primary solvents, the substrate whitens, and the storage stability of the liquid composition is poor.

[0054] (Method for preparing resin composition) The resin composition of this embodiment can be prepared by mixing the above-mentioned components in accordance with conventional methods. The components constituting the resin composition, (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C), may each be liquid or solid. That is, the resin composition may be a liquid obtained by mixing liquid and solid components, a liquid obtained by mixing all liquid components, or a solid obtained by mixing all solid components. Furthermore, various additives may be included as needed.

[0055] By using the resin composition of this embodiment, liquid compositions such as inks, mediums, primers, and overcoat varnishes for forming the detachable printing layer described later can be easily prepared. Specifically, by mixing the resin composition with conventionally known components used in inks, etc., according to a conventional method, a liquid composition can be prepared that can form a printing layer on a substrate made of A-PET, HDPE, and LLDPE that is easily detachable under mild alkaline conditions, has excellent storage stability, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali detachability, and can suppress whitening of the substrate.

[0056] <Liquid composition> The liquid composition of the present invention is a liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). The first embodiment of the liquid composition of the present invention contains a solvent comprising an alcohol-based solvent and an ester-based solvent, a printing composition for forming a non-detachable printing layer, and the aforementioned resin composition. The total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3.

[0057] Furthermore, a second embodiment of the liquid composition of the present invention contains (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g, styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g, a dispersion resin (C) having an acid value of 150 to 400 mgKOH / g, and a solvent including an alcohol-based solvent and an ester-based solvent. The total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass, the content of dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of styrene-(meth)acrylic resin (B), and the total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass. Furthermore, the total content of alcohol-based solvents and ester-based solvents in the solvent is 90-100% by mass, and the mass ratio of alcohol-based solvents to ester-based solvents is 2.5:7.5-7:3. Hereinafter, "the liquid composition of the first embodiment" and "the liquid composition of the second embodiment" will be collectively referred to as "the liquid composition of this embodiment."

[0058] The liquid composition of the first embodiment contains the aforementioned resin composition and therefore contains (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in predetermined amounts and mass ratios. The liquid composition of the second embodiment also contains (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in predetermined amounts and mass ratios. Therefore, by using the liquid composition of this embodiment, a printed layer with excellent storage stability, easy desorption under mild alkaline conditions, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption properties can be formed on substrates made of A-PET, HDPE, and LLDPE while suppressing whitening of the substrate. Note that the components such as (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) are the same as the components such as (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) used in the aforementioned resin composition.

[0059] The content of (meth)acrylic resin (A) in the solid content (excluding colorants such as pigments) of the liquid composition may be set appropriately depending on the intended use. For example, the content of (meth)acrylic resin (A) is preferably 40 to 75% by mass, more preferably 50 to 70% by mass, and particularly preferably 59 to 65% by mass, based on the solid content in the liquid composition, from the viewpoint of superior blocking resistance, adhesion, and alkali desorption of the printed layer. By setting the content of (meth)acrylic resin (A) within the above range, the blocking resistance, adhesion, and alkali desorption of the printed layer can be improved. If the content of (meth)acrylic resin (A) is less than 40% by mass, the adhesion of the ink layer may be poor, and if it is more than 75% by mass, the alkali desorption and blocking resistance of the ink layer may be poor, but in either case, the objectives of the present invention can be achieved.

[0060] The solid content of (meth)acrylic resin (A) in the total mass of the liquid composition (excluding colorants such as pigments) can be set appropriately according to the intended use. For example, the solid content of (meth)acrylic resin (A) is preferably 1 to 50% by mass, more preferably 3 to 35% by mass, and particularly preferably 5 to 20% by mass, based on the total mass of the liquid composition, from the viewpoint of better storage stability of the ink, resistance to blocking of the printed layer, adhesion, and alkali desorption. By setting the solid content of (meth)acrylic resin (A) within the above range, storage stability, resistance to blocking of the printed layer, adhesion, and alkali desorption can be improved. If the solid content of (meth)acrylic resin (A) is less than 1% by mass, the adhesion of the ink layer may be poor, and if it is more than 50% by mass, the alkali desorption and resistance to blocking of the ink layer may be poor, but in either case, the objectives of the present invention can be achieved.

[0061] The content of styrene-(meth)acrylic resin (B) in the solid content (excluding colorants such as pigments) of the liquid composition may be set appropriately depending on the intended use. For example, the content of styrene-(meth)acrylic resin (B) is preferably 4 to 28% by mass, more preferably 5 to 17% by mass, and particularly preferably 6 to 14% by mass, based on the solid content in the liquid composition, from the viewpoint of better blocking resistance and alkali desorption of the printed layer. By setting the content of styrene-(meth)acrylic resin (B) within the above range, the blocking resistance and alkali desorption of the printed layer can be improved. If the content of styrene-(meth)acrylic resin (B) is less than 4% by mass, alkali desorption may be poor, and if it is more than 28% by mass, blocking resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0062] The solid content of styrene-(meth)acrylic resin (B) in the total mass of the liquid composition (excluding colorants such as pigments) can be appropriately set according to the intended use. For example, the solid content of styrene-(meth)acrylic resin (B) is preferably 0.1 to 10.0% by mass, more preferably 1.0 to 8.0% by mass, and particularly preferably 1.0 to 6.0% by mass, based on the total mass of the liquid composition, from the viewpoint of superior blocking resistance, alkali desorption resistance, and water resistance of the printed layer. By setting the styrene-(meth)acrylic resin (B) content within the above range, storage stability, blocking resistance, and alkali desorption resistance of the printed layer can be improved. If the solid content of styrene-(meth)acrylic resin (B) is less than 0.1% by mass, alkali desorption resistance may be poor, and if it exceeds 10.0% by mass, blocking resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0063] The content of the dispersion resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) can be appropriately set according to the intended use. For example, the content of the dispersion resin (C) is preferably 0.9 to 18% by mass, more preferably 2 to 10% by mass, and particularly preferably 3 to 5.5% by mass, based on the solid content of the liquid composition. By setting the content of the dispersion resin (C) within the above range, storage stability, alkali desorption properties of the printed layer, and heat resistance can be improved. If the content of the dispersion resin (C) is less than 0.9% by mass, the desorption properties of the printed layer may be poor, and if it is more than 18% by mass, storage stability and heat resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0064] The solid content of the dispersion resin (C) in the total mass of the liquid composition (excluding colorants such as pigments) can be set appropriately according to the intended use. For example, the solid content of the dispersion resin (C) is preferably 0.05 to 5.0% by mass, more preferably 0.1 to 4.0% by mass, and particularly preferably 0.15 to 3.0% by mass, based on the total mass of the liquid composition. By setting the solid content of the dispersion resin (C) within the above range, storage stability, alkali desorption of the printed layer, and heat resistance can be improved. If the solid content of the dispersion resin (C) is less than 0.05% by mass, the desorption of the printed layer may be poor, and if it is more than 5% by mass, storage stability and heat resistance may be poor, but in either case, the objectives of the present invention can be achieved.

[0065] The total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass, preferably 11 to 25% by mass, and more preferably 11 to 20% by mass. By keeping the total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) within the above range, the blocking resistance, heat resistance, and alkali desorption properties of the printed layer can be improved. If the total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) is less than 10% by mass, the alkali desorption properties of the printed layer decrease. On the other hand, if the total content of styrene-(meth)acrylic resin (B) and dispersion resin (C) exceeds 30% by mass, the blocking resistance of the printed layer formed on substrates made of A-PET and LLDPE decreases, and the heat resistance of the printed layer formed on substrates made of A-PET and HDPE decreases.

[0066] In the solid content of the liquid composition (excluding colorants such as pigments), the content of dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) is 0.1 to 1.5 parts by mass, preferably 0.15 to 1.2 parts by mass, and more preferably 0.3 to 0.8 parts by mass from the viewpoint of further improving blocking resistance, heat resistance, and alkali desorption. By setting the content of dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) within the above range, the alkali desorption properties of the printed layer can be improved. If the content of dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) is less than 0.1 parts by mass, the alkali desorption properties of the formed printed layer will decrease. On the other hand, if the content of dispersion resin (C) per 1 part by mass of styrene-(meth)acrylic resin (B) is greater than 1.5 parts by mass, the alkali desorption properties of the printed layer formed on a substrate made of A-PET and HDPE will decrease.

[0067] The total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass, and 70 to 100% by mass is more preferable from the viewpoint of further improving adhesion, blocking resistance, and abrasion resistance. By setting the total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition to the above range, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption resistance of the printed layer can be improved. On the other hand, if the total content of (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is less than 65% by mass, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali desorption resistance are inferior.

[0068] The liquid composition of the first embodiment can be prepared, for example, by adding and mixing the aforementioned resin composition to a printing composition such as an ink, medium, primer, and overcoat varnish for forming a non-detachable printing layer, which contains each of the conventionally known components.

[0069] The liquid composition of the second embodiment can be prepared, for example, by adding and mixing various components commonly used in printing compositions such as inks, mediums, primers, and overcoat varnishes with the aforementioned resin composition.

[0070] (optional ingredient) The liquid composition of this embodiment may further contain silica, pigments, cellulose resins, other resins, and various additives as components other than the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) described above. The silica and cellulose resins are the same as those that can be used in the aforementioned resin composition.

[0071] The solid content of silica in the liquid composition is preferably 0.1 to 1.5% by mass, and more preferably 0.2 to 1.0% by mass, based on the solid content of the liquid composition (excluding colorants such as pigments).

[0072] The solid content of the cellulose resin is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass, based on the total solid content of the liquid composition (excluding colorants such as pigments). By keeping the cellulose resin content within the above range, the pigment dispersibility can be further improved.

[0073] [Pigments] As pigments, general pigments used in inks such as gravure printing inks can be used. Examples of pigments 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.

[0074] The pigment content in the liquid composition can be appropriately set according to the color tone and density of the printed layer (printed material) to be formed. Specifically, the solid content of the pigment is usually 80% by mass or less, preferably 70% by mass or less, based on the solid content of the liquid composition.

[0075] [Other resins] Other resins are those other than the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) mentioned above. Examples of other resins that do not affect the liquid composition of this embodiment include nitrated cotton, urethane resin, polyamide resin, and chlorinated polypropylene resin.

[0076] [Additives] Liquid compositions may contain additives such as extender pigments, waxes, synthetic resin powders, defoamers, dispersants, and plasticizers in order to maintain the properties of the liquid composition, such as viscosity and fluidity, to plasticize the printed layer (printed surface), and to impart slipperiness to the printed layer (printed surface).

[0077] 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.

[0078] Incorporating wax into the liquid composition is preferable because it can improve the abrasion resistance of the resulting printed layer. The solid content of the wax in the liquid composition is preferably 0.1 to 5.0% by mass, and more preferably 0.5 to 3.0% by mass, based on the total solid content of the liquid composition.

[0079] (Method for preparing a liquid composition) The liquid composition of this embodiment can be prepared by mixing the above-mentioned components according to a conventional method.

[0080] For example, the liquid composition of the second embodiment can be prepared by adding and mixing various components commonly used in printing compositions such as inks, mediums, primers, and overcoat varnishes with the aforementioned resin composition.

[0081] Furthermore, the liquid composition of the first embodiment can be prepared by adding and mixing the aforementioned styrene-(meth)acrylic resin (B) and dispersion resin (C) to a general printing composition such as an ink, medium, primer, and overcoat varnish for forming a non-detachable printing layer containing (meth)acrylic resin (A) as a binder resin, in a predetermined content and mass ratio. In other words, by appropriately adding and mixing the aforementioned styrene-(meth)acrylic resin (B) and dispersion resin (C) to a liquid composition such as an ink for forming a non-detachable printing layer, the liquid composition for forming a non-detachable printing layer can be converted into a liquid composition capable of forming a detachable printing layer.

[0082] The liquid composition of this embodiment can be used in inks containing medium, primer, overcoat varnish, and colorants. The liquid composition of this embodiment can be suitably used not only as an ink containing colorants (colorants) such as pigments, but also as a medium, primer, and overcoat varnish that substantially does not contain pigments. Printed materials can be manufactured by combining an ink containing pigments with at least one of the mediums, primers, and overcoat varnishes that do not contain pigments. In particular, from the viewpoint of compatibility, it is preferable to use an ink with the same composition of components other than pigments in combination with at least one of the mediums, primers, and overcoat varnishes.

[0083] By using a medium, primer, overcoat varnish, or ink containing a colorant made from the liquid composition of this embodiment, a printable layer with excellent adhesion can be formed on a substrate made of at least one resin selected from the group consisting of A-PET, HDPE, and LLDPE. Specifically, when cellophane tape is quickly peeled off a portion of the surface of a printable layer formed by coating the liquid composition onto a substrate made of the above resin, the ratio of the area of ​​the peeled printable layer to the adhesive area of ​​the cellophane tape is less than 20%, more preferably less than 15%.

[0084] <Detachable printed layers and laminates> One embodiment of the detachable printed layer of the present invention is a printed layer formed of an ink containing a medium, primer, overcoat varnish, or colorant using the aforementioned liquid composition, disposed on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). Another embodiment of the laminate of the present invention comprises a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE), and a printed layer formed of the aforementioned liquid composition disposed on the substrate. That is, by using the aforementioned liquid composition, a detachable printed layer that can be easily detached by treatment under mild alkaline conditions, and a laminate comprising this detachable printed layer can be obtained. Furthermore, the printed layer formed with the aforementioned medium, primer, overcoat varnish, or ink containing a colorant not only exhibits excellent alkali desorption properties, but also boasts excellent properties as a printed material, such as blocking resistance, adhesion, abrasion resistance, and heat resistance, and the substrate is less prone to whitening. For this reason, the laminate of this embodiment is highly recyclable and also offers excellent handling and design capabilities.

[0085] A specific example of the configuration of a laminate is a laminate (laminated-1) comprising a first substrate and a removable printing layer formed with a liquid composition medium, primer, overcoat varnish, or ink containing a colorant. This laminate-1 may further comprise other layers besides the first substrate and the removable printing layer. Examples of other layers include a pattern layer formed using printing ink, and a vapor-deposited layer formed by depositing a metal or metal oxide such as aluminum or silica.

[0086] After applying the liquid composition onto a first substrate, a detachable printed layer can be formed on the first substrate by removing volatile components. 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, etc. The thickness of the printed layer is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

[0087] Another specific example of a laminate configuration is one in which laminate-1 further comprises a second substrate (laminated-2). That is, laminate-2 is a laminate having a so-called laminate structure comprising a first substrate, a second substrate, and a removable printed layer. Laminate-2 may further comprise other layers besides the first substrate, the second substrate, and the removable printed layer. Examples of other layers include a pattern layer formed using printing ink, and a vapor-deposited layer in which metals or metal oxides such as aluminum or silica are deposited. Laminate-2 may also be a laminate film in which the first substrate, the removable printed layer, the adhesive layer, and the second substrate are laminated in this order.

[0088] A laminate film can be easily manufactured, for example, by the following method. First, an adhesive layer is formed by applying an adhesive to the surface of the detachable printed layer of the aforementioned laminate-1. Then, a second substrate is bonded to the surface of the formed adhesive layer to manufacture a laminate film.

[0089] As the first substrate and the second substrate, etc., a plastic film made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE) can be used. The surface of the substrate may be corona discharge treated. The substrate may be made of recycled material recovered after being used once as printed material. The substrate may be stretched or unstretched. As the substrate, a material with a metal or metal oxide such as silica, alumina, and aluminum deposited on it, or a material with a deposited surface coated with a paint such as polyvinyl alcohol can be used.

[0090] As the base material, products manufactured according to conventional methods or commercially available products can be used. Examples of commercially available base materials include the product names "NOA CRYSTAL-V" and "NOA CRYSTAL-R" from RP Topla Co., Ltd., and "TC400" and "HD" from Tamapoly Co., Ltd.

[0091] The shape of the substrate is not particularly limited, and a substrate of a shape appropriate to the purpose can be used. Specific examples of substrate shapes include film and sheet shapes. Furthermore, specific examples of substrate shapes include various containers such as cups, plates, bowls, and bottles, as well as lids such as caps. By applying a liquid composition such as ink to the surface of the substrate using a general printing method such as gravure printing, a removable printed layer with the desired design or information is formed, and the desired laminate can be obtained.

[0092] The laminate of this embodiment, which has a detachable printed layer formed with the aforementioned ink, medium, primer, or overcoat varnish, is useful, for example, as a label or packaging. More specifically, the laminate of this embodiment is suitable as a container for food products, soft drinks, cosmetics, seasonings, pharmaceuticals, and hygiene products; a label to be affixed to these containers; a resin bag (packaging material) to contain food products such as bread, rice balls, and prepared foods; a lid to seal containers and bottles; and so on. Among these, since many food and beverage containers are recycled, the laminate is particularly suitable as a food and beverage container, a label to be affixed to a food and beverage container, and a lid to seal a food and beverage container.

[0093] <Method for removing the printed layer> One embodiment of the method for removing a printed layer according to the present invention comprises the step of contacting the printed layer of the laminate with an alkaline aqueous solution to remove the printed layer from the substrate. Since the printed layer provided on the substrate constituting the laminate is a layer formed by the liquid composition described above, it can be easily removed under mild alkaline conditions.

[0094] To detach the printed layer placed on the substrate, the laminate can be treated by immersing it in an alkaline aqueous solution, thereby bringing the alkaline aqueous solution into contact with the printed layer. 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 1-7.5% by mass sodium hydroxide aqueous solution for 5-60 minutes, the printed layer can be easily detached from the substrate, and a clean, recyclable substrate can be obtained. The temperature of the alkaline aqueous solution, such as the sodium hydroxide aqueous solution, into which the laminate is immersed should be room temperature (25°C) to 90°C.

[0095] For example, when processing the aforementioned laminate-2, the laminate-2 is immersed in a 1.5% by mass sodium hydroxide aqueous solution and stirred at 80°C for about 30 minutes. This allows the printed layer to be detached from the first substrate and the second substrate.

[0096] The desorption method of this 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 the substrate, it can be used as a recycled film simply by cleaning the surface by washing and drying it with water. [Examples]

[0097] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0098] <Preparation of various raw materials> (Resin (A)) The types of resin (A) shown in Table 1 were prepared.

[0099] TIFF2026165915000001.tif64170

[0100] (Resin (B)) The types of resin (B) shown in Table 2 were prepared.

[0101] TIFF2026165915000002.tif51170

[0102] (Dispersion resin (C)) The types of dispersion resins (C) shown in Table 3 were prepared.

[0103] TIFF2026165915000003.tif48170

[0104] (silica) As silica, we prepared S-1 and S-2 as shown below. • S-1: Product name "ACEMAT OK412", manufactured by EVONIK, average particle size 6.3 μm • S-2: Product name "NipSeal E220A", manufactured by Tosoh Silica Co., Ltd., average particle size 4.2 μm

[0105] (Other ingredients) The following ingredients were prepared. • Pigment: Product name "Seika First Carmine 3870", manufactured by Dainichi Seika Kogyo Co., Ltd. • Antifoaming agent: Product name "BYK-1752", manufactured by BYK Corporation. • Dispersant: Product name "Solspers 20000", manufactured by Lubrizol, acid value 0 mg KOH / g • Plasticizer: Product name "Citroflex A-4", manufactured by Morimura Shoji Co., Ltd. Solvents: Isopropanol (IPA), methanol, ethyl acetate, propyl acetate, hydrocarbon solvent (toluene), ketone solvent (methyl ethyl ketone), glycol ether solvent (diethylene glycol methyl ether), water

[0106] <Preparation of liquid composition (ink)> The components were mixed to obtain the compositions shown in the upper row of Tables 4-1 to 4-5 (unit: %). The obtained mixtures were kneaded using a paint shaker to prepare a liquid composition (ink). In Tables 4-1 to 4-5, "Alc" is an abbreviation for alcohol-based solvent, and "Est" is an abbreviation for ester-based solvent.

[0107] TIFF2026165915000004.tif255164

[0108] TIFF2026165915000005.tif255164

[0109] TIFF2026165915000006.tif255160

[0110] TIFF2026165915000007.tif237170

[0111] TIFF2026165915000008.tif243170

[0112] <Manufacturing of laminates> Three types of base films were prepared as shown below. • A-PET sheet with corona discharge treatment on one side (product name "NOA CRYSTAL-V", manufactured by RP Topla Co., Ltd., thickness 250 μm) • HDPE film with corona discharge treatment on one side (product name "Karariyan Y", manufactured by Denka Co., Ltd., thickness 18 μm) • LLDPE film with corona discharge treatment on one side (product name "HC", manufactured by RM Tohcello Co., Ltd., thickness 25 μm)

[0113] Furthermore, the prepared liquid composition was diluted with a mixed solvent (methylcyclohexane / propyl acetate / isopropyl alcohol). The diluted liquid composition for release ink was applied to the treated surface of each prepared substrate film by gravure printing using a 70-line helio plate. This resulted in a laminate in which a printed layer (100 mm × 150 mm solid layer, 1 μm thick) was formed on the substrate film.

[0114] <Rating (1)> (Storage stability) The prepared ink was left to stand at 40°C for 5 days starting the following day. The viscosity of the ink after standing was measured using a Zahn cup, and the storage stability (flowability) of the liquid composition was evaluated according to the evaluation criteria shown below. The results are shown in Tables 5-1 and 5-2. ○: Viscosity increased slightly. △: Viscosity increased for more than 10 seconds. ×: Gelated, or the raw materials precipitated.

[0115] (Blocking resistance) A test specimen was prepared by overlapping the printed surface with the unprinted surface of the same base film, and the result was 4 kg / cm². 2 The specimens were stored in a 40°C constant temperature chamber for 24 hours under the applied load. After storage, the test specimens were peeled off, and the blocking resistance of the printed layer was evaluated according to the evaluation criteria shown below. The results are shown in Tables 5-1 and 5-2. 5: The area percentage of the printed layer transferred to the non-printed surface was between 0% and 10%. 4: The area percentage of the printed layer that transferred to the non-printed surface was 10% or more but less than 20%. 3: The area percentage of the printed layer that transferred to the non-printed surface was between 20% and 50%. 2: The area percentage of the printed layer that transferred to the non-printed surface was between 50% and 80%. 1: The area ratio of the printed layer transferred to the non-printed surface was between 80% and 100%.

[0116] (Adhesion) After applying cellophane tape (manufactured by Nichiban Co., Ltd.) to a portion of the surface of the ink layer, the cellophane tape was quickly removed, and the condition of the ink layer remaining on the base film (plastic film) was visually inspected. The adhesion of the ink layer to the base film (plastic film) was then evaluated according to the following evaluation criteria. The results are shown in Tables 5-1 and 5-2. 5: The area of ​​the peeled ink layer is less than 10% of the adhesive area of ​​the cellophane tape. 4. The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 10% or more and less than 20%. 3. The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 20% or more and less than 50%. 2: The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 50% or more and less than 80%. 1: The area of ​​the peeled-off ink layer is 80% or more of the adhesive area of ​​the cellophane tape.

[0117] (Abrasion resistance) Using a Japan Society for the Promotion of Science (JSPS) friction fastness tester (product name "AB-301," manufactured by Tester Sangyo Co., Ltd.), a friction test was conducted by applying a load of 200 gf and rubbing the surface of the printed layer 200 times back and forth with a No. 3 metal cloth. After the friction test, the appearance of the printed layer was visually inspected, and the friction resistance of the printed layer was evaluated according to the evaluation criteria shown below. The results are shown in Tables 5-1 and 5-2. 5: The area ratio of the printed layer that migrated to the No. 3 gold cloth side was between 0% and less than 10%. 4. The area ratio of the printed layer that migrated to the No. 3 gold cloth side was between 10% and 20%. 3: The area ratio of the printed layer that migrated to the No. 3 gold cloth side was between 20% and 50%. 2: The area ratio of the printed layer that migrated to the No. 3 gold cloth side was between 50% and 80%. 1: The area ratio of the printed layer that migrated to the No. 3 gold cloth side was between 80% and 100%.

[0118] (Heat resistance) Test specimens were prepared by layering the surface of the printed layer with a soft aluminum foil. A heat seal tester (product name "TP-701-C Heat Seal Tester", manufactured by Tester Sangyo Co., Ltd.) was used to apply a seal at 100-120°C and 2 kg / cm² from the aluminum foil. 2 The specimens were heated for 1 second under the specified conditions. After heating, the specimens were peeled off, and the heat resistance of the printed layer was evaluated according to the evaluation criteria shown below. The results are shown in Tables 5-1 and 5-2. 5. Even when heated to 150°C, the printed layer (liquid composition for releaseable ink) did not adhere to the aluminum foil. 4. The printed layer (liquid composition for releaseable ink) did not adhere to the aluminum foil even when heated to 140°C, but the ink was removed when heated to 150°C. 3. The printed layer (liquid composition for releaseable ink) did not adhere to the aluminum foil even when heated to 130°C, but the ink was removed when heated to 140°C. 2. The printed layer (liquid composition for releaseable ink) did not adhere to the aluminum foil even when heated to 120°C, but the ink was removed when heated to 130°C. 1: A printed layer (liquid composition for releaseable ink) was formed on aluminum foil by heating at a temperature below 120°C.

[0119] (Alkaline desorption) The laminate was immersed in a 4.5% sodium hydroxide aqueous solution at 80°C and stirred for 30 minutes. After removing the laminate from the sodium hydroxide aqueous solution and rinsing it with water, it was visually inspected, and the delamination properties of the printed layer were evaluated according to the evaluation criteria shown below. The results are shown in Tables 5-1 and 5-2. 5: The printed layer had completely detached. 4: A portion of the printed layer remained on the base film. 3: Approximately half of the printed layer remained on the base film. 2: The majority of the printed layer remained on the base film. 1: The printed layer had not detached at all.

[0120] TIFF2026165915000009.tif110170

[0121] TIFF2026165915000010.tif129170

[0122] Furthermore, laminate-2 was manufactured and evaluated in the same manner as the "alkali desorption properties" described above. As a result, it was confirmed that all laminate-2 exhibited excellent alkali desorption properties equivalent to those of the aforementioned examples.

[0123] <Rating (2)> (Whitening resistance) The liquid compositions prepared in Examples 1, 22-29, and Comparative Examples 14-21 were applied to the three types of substrate films used in the "Laminate Manufacturing" process described above, printed, and then the liquid compositions were wiped off with IPA. The surface of the substrate films was visually inspected, and the whitening resistance was evaluated according to the evaluation criteria shown below. The results are shown in Table 6. ○: No bleaching was observed. △: It was slightly bleached. ×: It was severely bleached.

[0124] (Storage stability) The storage stability (flowability) of the liquid compositions prepared in Examples 1, 22-29, and Comparative Examples 14-21 was evaluated in the same manner as described above for "storage stability." The results are shown in Table 6.

[0125] TIFF2026165915000011.tif46170

[0126] <Rating (3)> (Adhesion and alkali desorption) A liquid composition (ink) was prepared in the same manner as in Example 1 described above, except that the solvent (IPA: ethyl acetate) was used in the mass ratio shown in Table 7. In addition, six types of base films were prepared as shown below. • Shrink PS: Shrink polystyrene • OPS: Biaxially oriented polystyrene • CPS: Unstretched polystyrene • OPP: Biaxially oriented polypropylene • PET: Polyethylene terephthalate • ONY: Biaxially oriented nylon

[0127] The prepared liquid composition was diluted with a mixed solvent (methylcyclohexane / propyl acetate / isopropyl alcohol). The diluted liquid composition for release ink was applied to the treated surface of each prepared substrate film by gravure printing using a 70-line helio plate. This resulted in a laminate in which a printed layer (100 mm × 150 mm solid layer, 1 μm thick) was formed on the substrate film. The obtained laminate was then evaluated in the same manner as described above for "adhesion" and "alkali release properties". The results are shown in Table 7.

[0128] TIFF2026165915000012.tif123170

[0129] In Comparative Example 24 of the evaluation results in Table 7, adhesion and alkali desorption tests for shrink PS, OPS, and CPS substrates could not be measured because whitening of the substrate occurred during printing. [Industrial applicability]

[0130] The resin composition of the present invention is useful as a material for preparing liquid compositions such as inks for forming alkali-desorbable printing layers. Furthermore, the liquid composition of the present invention is useful for use in inks, mediums, primers, and overcoat varnishes for forming alkali-desorbable printing layers. By using the inks, mediums, primers, and overcoat varnishes of the present invention to form a printing layer on a substrate made of resins such as A-PET, HDPE, and LLDPE, a recyclable laminate can be easily obtained.

Claims

1. A resin composition used in a liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, (Meth)acrylic resin (A) having an acid value of less than 25 mg KOH / g, A styrene-(meth)acrylic resin (B) with an acid value of 25-90 mgKOH / g, It contains a dispersion resin (C) with an acid value of 150 to 400 mg KOH / g, The total content of the styrene-(meth)acrylic resin (B) and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass. The content of the dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of the styrene-(meth)acrylic resin (B), The total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass. The liquid composition contains a solvent including an alcohol-based solvent and an ester-based solvent, A resin composition wherein the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:

3.

2. The resin composition according to claim 1, wherein the glass transition temperature of the (meth)acrylic resin (A) is 40 to 65°C.

3. The resin composition according to claim 1, wherein the content of the (meth)acrylic resin (A) in the solid content of the liquid composition resin composition is 40 to 75% by mass.

4. The resin composition according to claim 1, wherein the dispersed resin (C) is at least one selected from the group consisting of carboxylic acid resins and ammonium salt resins.

5. The resin composition according to claim 1, further containing silica having an average particle size of 1.0 to 8.0 μm.

6. The resin composition according to claim 1, further comprising a cellulose resin.

7. A liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, Solvents including alcohol-based solvents and ester-based solvents, A printing composition for forming a non-detachable printed layer, The resin composition according to claim 1 contains, A liquid composition wherein the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:

3.

8. A liquid composition for forming a detachable printing layer on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, (Meth)acrylic resin (A) having an acid value of less than 25 mg KOH / g, A styrene-(meth)acrylic resin (B) with an acid value of 25-90 mgKOH / g, A dispersion resin (C) having an acid value of 150-400 mgKOH / g, A solvent containing alcohol-based solvents and ester-based solvents, The total content of the styrene-(meth)acrylic resin (B) and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass. The content of the dispersion resin (C) is 0.1 to 1.5 parts by mass per 1 part by mass of the styrene-(meth)acrylic resin (B), The total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100% by mass. A liquid composition wherein the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:

3.

9. The liquid composition according to claim 7 or 8, wherein the alcohol-based solvent is at least one selected from the group consisting of isopropyl alcohol, methanol, ethanol, n-propanol, and n-butanol.

10. The liquid composition according to claim 7 or 8, wherein the ester solvent is at least one selected from the group consisting of ethyl acetate, propyl acetate, and butyl acetate.

11. The liquid composition according to claim 7 or 8, wherein when a cellophane tape is quickly peeled off from a part of the surface of a printed layer formed by coating the liquid composition onto the substrate, the ratio of the area of ​​the peeled printed layer to the adhesive area of ​​the cellophane tape is less than 20%.

12. Use of the liquid composition according to claim 7 or 8 in an ink having a medium, primer, overcoat varnish, or colorant.

13. An ink having a medium, primer, overcoat varnish, or colorant, using the liquid composition according to claim 7 or 8.

14. A detachable printing layer formed of an ink having a medium, primer, overcoat varnish, or colorant according to claim 13, disposed on a substrate made of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene.

15. A substrate formed from at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, A laminate comprising a removable printed layer according to claim 14, disposed on the substrate.

16. The laminate according to claim 15, which is a container or lid material.

17. A method for removing a printed layer, comprising the step of contacting the printed layer of the laminate according to claim 15 with an alkaline aqueous solution to detach and remove the printed layer from the substrate.

18. The method for removing a printed layer according to claim 17, further comprising the step of recovering the substrate from which the printed layer has been removed.

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