Method for manufacturing printed matter and recycled base material

Abstract

Provided are a method for producing recycled substrates that can suppress coloration of the alkaline solution after detachment when a coating is detached from a plastic substrate by treatment with an alkaline solution, and a printed matter having a detachable coating that can be suitably used in the method for producing recycled substrates. The printed matter is composed of a substrate, a primer layer that can be removed from the substrate by treatment with an alkaline solution, an ink layer that contains a colorant and at least one resin selected from the group consisting of acrylic resin, urethane resin, polyamide resin, rosin resin, and polyester resin, and a varnish layer, laminated in this order.

Description

[Technical field]

[0001] The present invention relates to a printed matter having a coating that can be detached from a substrate, and a method for producing a recycled substrate from the printed matter. [Background technology]

[0002] In recent years, the problem of marine plastics has become evident, caused by plastics discarded or dumped in the ocean being broken down into fine particles (microplastics) in seawater. It is feared that these microplastics will enter the bodies of marine organisms, become concentrated, and affect the health of seabirds and humans through the food chain. One way to improve this marine plastic problem is recycling. Improving the recycling rate of resources such as soft packaging materials and plastic bottles will prevent plastics from entering the ocean. However, with current recycling, there is an issue that the printed layer printed on the plastic substrate does not come off during the recycling process and gets mixed into the plastic, causing a deterioration in color and physical properties, and reducing the value of the recycled plastic. If it is possible to remove the film from the plastic substrate during the recycling process and solve this problem, the value of the recycled plastic will increase, leading to the entry of new recyclers and the establishment of separate collection by local governments. It is believed that this will improve the recycling rate and improve the marine plastic problem. Therefore, there is a need to develop a method to remove the film from the plastic substrate during the recycling process. Furthermore, the film-forming materials that are widely used on plastic substrates are being replaced by toluene-free and methyl ethyl ketone (MEK)-free materials out of consideration for the impact on worker health and the environment. Therefore, materials that solve the above problems must be developed with this in mind.

[0003] In the prior art, a method is disclosed in which a film containing a styrene-acrylic acid resin, a phenolic resin, and a styrene-maleic acid resin as a vehicle printed on a heat-shrinkable PET film is removed with alkaline water (Patent Document 1). Similarly, a method is disclosed in which a coating layer containing a styrene-maleic acid resin, a rosin-maleic acid resin, and an acrylic acid copolymer resin is formed on a heat-shrinkable PET film by arranging the coating layer between the coating layers, and the coating layer is removed with alkaline water (Patent Documents 2 and 3). However, these techniques only guarantee the characteristics for a specific heat-shrinkable PET substrate, and are limited in that a coating layer other than the coating layer must be provided, and are not suitable for recycling general-purpose plastic substrates containing polyolefins. On the other hand, organic solvent-based printing inks for alkaline water desorption, which use a urethane resin having an acid value as a binder resin, have also been disclosed (Patent Document 4, Patent Document 5, and Patent Document 6). However, few of the developments in technology to promote the detachment of the printing film have taken into consideration the release of the detached film into the cleaning solution.In particular, no effective solution has been shown to address the problem of the colored pigments contained in the ink being released into the cleaning solution during cleaning, causing coloration and resulting in wastewater treatment problems, which in turn increases the environmental burden. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3822738 [Patent Document 2] Patent No. 4653913 [Patent Document 3] Patent No. 4451071 [Patent Document 4] Patent No. 6638802 [Patent Document 5] Patent No. 6631964 [Patent Document 6] JP 2020-169280 A Summary of the Invention [Problem to be solved by the invention]

[0005] The problem that the present invention aims to solve is to provide a method for producing recycled substrates that can suppress coloration of the alkaline solution after detachment when a coating is detached from a plastic substrate by treatment with an alkaline solution, and a printed matter having a removable coating that can be suitably used in the method for producing recycled substrates. [Means for solving the problem]

[0006] As a result of extensive research into solving the above-mentioned problems, the inventors discovered that the above-mentioned problems can be solved by placing a removable primer layer between the substrate and the ink layer as a coating that will detach from the substrate when treated with an alkaline solution, and then placing a varnish layer on top of the ink layer, in a printed matter having a substrate, primer layer, ink layer, and varnish layer layered in that order, thereby completing the present invention.

[0007] That is, the present invention includes the following aspects. [1] A substrate; a primer layer that can be removed from the substrate by treatment with an alkaline solution; an ink layer containing a colorant and at least one resin selected from the group consisting of an acrylic resin, a urethane resin, a polyamide resin, a rosin resin, and a polyester resin; A printed matter in which a layer of varnish and a layer of paper are laminated in this order. [2] The printed matter described in [1], wherein the varnish layer contains a resin selected from the group consisting of urethane resins, cellulose derivatives, and polyester resins. [3] The varnish layer is (i) containing at least a urethane resin and a cellulose derivative, or (ii) containing at least a urethane resin, a cellulose derivative, and a polyisocyanate; The printed matter described in [1] or [2], which is either of the following: [4] The printed matter described in [1] or [2], wherein the varnish layer is a crosslinked coating film. [5] The printed matter described in [1] or [2], wherein the primer layer contains a urethane resin or polyvinyl alcohol. [6] A method for producing a recycled substrate, comprising treating the printed matter described in [1] with an alkaline solution to remove the primer layer from the substrate, thereby obtaining a recycled substrate. [7] The method for producing a recycled substrate according to [6], wherein the alkaline solution has a pH of 9 or higher and contains a nonionic surfactant. Effect of the Invention

[0008] The present invention makes it possible to provide a method for producing recycled substrates that can suppress coloration of the alkaline solution after detachment of a coating from a plastic substrate by treatment with an alkaline solution, and a printed material having a removable coating that can be suitably used in the method for producing recycled substrates. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below. Note that the following description of the constituent elements is merely an example for explaining the present invention, and the present invention is not limited to these contents.

[0010] (Printed material) The printed matter of the present invention comprises a laminate comprising a substrate, a removable primer layer, an ink layer, and a varnish layer laminated in this order. The primer layer is a coating that can be removed from the substrate by treatment with an alkaline solution. The ink layer contains a colorant and at least one resin selected from the group consisting of acrylic resins, urethane resins, polyamide resins, rosin resins, and polyester resins. Each layer constituting the laminate will now be described.

[0011] <Base material> The substrate is preferably a plastic substrate, and examples thereof include polyamide resins such as nylon 6, nylon 66, and nylon 46; polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; biodegradable resins such as polyhydroxycarboxylic acids such as polylactic acid, aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate); thermoplastic resins such as polyolefin resins such as polypropylene and polyethylene, polyimide resins, polyarylate resins, and mixtures thereof, and films and laminates thereof. Among these, films and laminates made of polyethylene terephthalate, polyester, polyamide, polyethylene, and polypropylene can be preferably used, and polyethylene terephthalate, polypropylene, or polyethylene are more preferable when the release property of the composition according to the present invention is considered. These substrate films may be unstretched or stretched films, and the manufacturing method thereof is not limited. The thickness of the substrate film is also not particularly limited, but it is usually within the range of 1 to 500 μm.

[0012] The printing surface of the substrate is preferably subjected to surface modification by corona discharge treatment or chemical treatment, and silica, alumina, etc. may be vapor-deposited.

[0013] <Ink layer> The ink layer is formed using a composition for forming an ink layer. The composition for forming the ink layer contains a colorant. The composition for forming the ink layer also contains at least one type of resin A selected from the group consisting of acrylic resins, urethane resins, polyamide resins, rosin resins, and polyester resins. The composition for forming the ink layer may contain other resins in addition to the above-mentioned resin A. The composition for forming the ink layer may contain an organic solvent, and may also contain other components such as auxiliaries and acidic additives. The components of the ink layer forming composition will be described below.

[0014] <<Coloring agent>> The colorant component may be a color dye and / or a color pigment, and among these, a color pigment (hereinafter, simply referred to as a pigment) is preferable.

[0015] -Pigments- The pigment used in the present invention may be an inorganic pigment or an organic pigment that is used in general inks, paints, recording materials, etc. From the viewpoint of effectively suppressing coloring of the alkaline solution after desorption, an organic pigment is preferred.

[0016] Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. In addition, for example, carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthal yellow, chromophthal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, etc. can be mentioned. In addition, both non-acid-treated pigments and acid-treated pigments can be used. Specific examples of preferred organic pigments are given below.

[0017] Examples of black pigments include CI Pigment Black 1, CI Pigment Black 6, CI Pigment Black 7, CI Pigment Black 9, and CI Pigment Black 20.

[0018] Examples of indigo pigments include CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:5, CI Pigment Blue 15:6, CI Pigment Blue 16, CI Pigment Blue 17:1, CI Pigment Blue 22, CI Pigment Blue 24:1, CI Pigment Blue 25, CI Pigment Blue 26, CI Pigment Blue 60, CI Pigment Blue 61, CI Pigment Blue 62, CI Pigment Blue 63, CI Pigment Blue 64, CI Pigment Blue 75, CI Pigment Blue 79, and CI Pigment Blue 80.

[0019] Examples of green pigments include CI Pigment Green 1, CI Pigment Green 4, CI Pigment Green 7, CI Pigment Green 8, CI Pigment Green 10, and CI Pigment Green 36.

[0020] Examples of red pigments include CI Pigment Red 1, CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 4, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Red 8, CI Pigment Red 9, CI Pigment Red 10, CI Pigment Red 11, CI Pigment Red 12, CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 17, CI Pigment Red 18, CI Pigment Red 19, CI Pigment Red 20, CI Pigment Red 21, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 24, CI Pigment Red 25, CI Pigment Red 26, CI Pigment Red 27, CI Pigment Red 28, CI Pigment Red 29, CI Pigment Red 30, CI Pigment Red 31, CI Pigment Red 32, CI Pigment Red 33, CI Pigment Red 34, CI Pigment Red 35, CI Pigment Red 36, CI Pigment Red 37, CI Pigment Red 38, CI Pigment Red 39, CI Pigment Red 40, CI Pigment Red 41, CI Pigment Red 42, CI Pigment Red 43, CI Pigment Red 44, CI Pigment Red 45, CI Pigment Red 46, CI Pigment Red 47, CI Pigment Red 48, CI Pigment Red 49, CI Pigment Red 50, CI Pigment Red 51, CI Pigment Red 52, CI Pigment Red 53, CI Pig Red 19, CI Pigment Red 20, CI Pigment Red 21, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 31, CI Pigment Red 32, CI Pigment Red 38, CI Pigment Red 41, CI Pigment Red 43, CI Pigment Red 46, CI Pigment Red 48, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 48:4, CI Pigment Red 48:5, CI Pigment Red 48:6, CI Pigment Red 49, CI Pigment Red 49:1, CI Pigment Red 49:2, CI Pigment Red 49:3, CI Pigment Red 52, CI Pigment Red 52:1, CI Pigment Red 52:2, CI Pigment Red 53, CI Pigment Red 53:1, CI Pigment Red 53:2, CI Pigment Red 53:3, CI Pigment Red 54, CI Pigment Red 57, CI Pigment Red 57: 1, CI Pigment Red 58, CI Pigment Red 58:1, CI Pigment Red 58:2, CI Pigment Red 58:3, CI Pigment Red 58:4, CI Pigment Red 60:1, CI Pigment Red 63, CI Pigment Red 63:1, CI Pigment Red 63:2, CI Pigment Red 63:3, CI Pigment Red 64:1, CI Pigment Red 68, CI Pigment Red 68, CI Pigment Red 81:1, CI Pigment Red 83, C.I. Pigment Red 88, CI Pigment Red 89, CI Pigment Red 95, CI Pigment Red 112, CI Pigment Red 114, CI Pigment Red 119, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 136, CI Pigment Red 144, CI Pigment Red 146, CI Pigment Red 147, CI Pigment Red 149, CI Pigment Red 150, CI Pigment Red 164, CI Pigment Red Pigment Red 166, CI Pigment Red 168, CI Pigment Red 169, CI Pigment Red 170, CI Pigment Red 171, CI Pigment Red 172, CI Pigment Red 175, CI Pigment Red 176, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 179, CI Pigment Red 180, CI Pigment Red 181, CI Pigment Red 182, CI Pigment Red 183, CI Pigment Red 184, CI Pigment Red 185, CI Pigment Red 187, CI Pigment Red 188, CI Pigment Red 190, CI Pigment Red 192, CI Pigment Red 193, CI Pigment Red 194, CI Pigment Red 200, CI Pigment Red 202, CI Pigment Red 206, CI Pigment Red 207, CI Pigment Red 208, CI Pigment Red 209, CI Pigment Red 210, CI Pigment Red 211, CI Pigment Red Pigment Red 213, CI Pigment Red 214, CI Pigment Red 216, CI Pigment Red 215, CI Pigment Red 216, CI Pigment Red 220, CI Pigment Red 221, CI Pigment Red 223, CI Pigment Red 224, CI Pigment Red 226, CI Pigment Red 237, CI Pigment Red 238, CI Pigment Red 239, CI Pigment Red 240, CI Pigment Red 242, CI Pigment Red 245, CIPigment Red 247, CI Pigment Red 248, CI Pigment Red 251, CI Pigment Red 253, CI Pigment Red 254, CI Pigment Red 255, CI Pigment Red 256, CI Pigment Red 257, CI Pigment Red 258, CI Pigment Red 260, CI Pigment Red 262, CI Pigment Red 263, CI Pigment Red 264, CI Pigment Red 266, CI Pigment Red 268, CI Pigment Red 269, CI Pigment Red 270, CI Pigment Red 271, CI Pigment Red 272, CI Pigment Red 279, etc.

[0021] Examples of purple pigments include CI Pigment Violet 1, CI Pigment Violet 2, CI Pigment Violet 3, CI Pigment Violet 3:1, CI Pigment Violet 3:3, CI Pigment Violet 5:1, CI Pigment Violet 13, CI Pigment Violet 19 (γ type, β type), CI Pigment Violet 23, CI Pigment Violet 25, CI Pigment Violet 27, CI Pigment Violet 29, CI Pigment Violet 31, CI Pigment Violet 32, CI Pigment Violet 36, CI Pigment Violet 37, CI Pigment Violet 38, CI Pigment Violet 42, and CI Pigment Violet 50.

[0022] Examples of yellow pigments include CI Pigment Yellow 1, CI Pigment Yellow 3, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, Pigment Yellow 17, CI Pigment Yellow 24, CI Pigment Yellow 42, CI Pigment Yellow 55, CI Pigment Yellow 62, CI Pigment Yellow 65, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 86, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 95, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 117, CI Pigment Yellow 120, CI Pigment Yellow 122, CI Pigment Yellow 124, CI Pigment Yellow 126, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 130, CI Pigment Yellow 131, CI Pigment Yellow 132, CI Pigment Yellow 133, CI Pigment Yellow 134, CI Pigment Yellow 135, CI Pigment Yellow 136, CI Pigment Yellow 137, CI Pigment Yellow 138, CI Pigment Yellow 139, CI Pigment Yellow 140, CI Pigment Yellow 141, CI Pigment Yellow 142, CI Pigment Yellow 143, CI Pigment Yellow 144, CI Pigment Yellow 145, CI Pigment Yellow 146, CI Pigment Yellow 147, CI Pigment Yellow 148, CI Pigment Yellow 149, CI Pigment Yellow 150, CI Pigment Yellow 15 Yellow 120, Pigment Yellow 125, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 137, CI Pigment Yellow 138, CI Pigment Yellow 139, CI Pigment Yellow 147, CI Pigment Yellow 148, CI Pigment Yellow 150, CI Pigment Yellow 151, CI Pigment Yellow 153, CI Pigment Yellow 154, CI Pigment Yellow 155, CI Pigment Yellow 166, CI Pigment Yellow 168, CI Pigment Yellow 174, CI Pigment Yellow 180, CI Pigment Yellow 185 and CI Pigment Yellow 213.

[0023] Examples of orange pigments include CI Pigment Orange 5, CI Pigment Orange 13, CI Pigment Orange 16, CI Pigment Orange 34, CI Pigment Orange 36, CI Pigment Orange 37, CI Pigment Orange 38, CI Pigment Orange 43, CI Pigment Orange 51, CI Pigment Range 55, CI Pigment Orange 59, CI Pigment Orange 61, CI Pigment Orange 64, CI Pigment Orange 71, and CI Pigment Orange 74.

[0024] Examples of brown pigments include CI Pigment Brown 23, CI Pigment Brown 25, and CI Pigment Brown 26. Among them, preferred pigments include CI Pigment Black 7 as a black pigment, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6 as indigo pigments, CI Pigment Green 7 as a green pigment, and CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Red 185, CI Pigment Red 1 as red pigments. Examples of pigments that can be used include CI Pigment Red 22, CI Pigment Red 178, CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, purple pigments such as CI Pigment Violet 23 and CI Pigment Violet 37, yellow pigments such as CI Pigment Yellow 83, CI Pigment Yellow 14, CI Pigment Yellow 180, CI Pigment Yellow 139, and orange pigments such as CI Pigment Orange 38, CI Pigment Orange 13, CI Pigment Orange 34, and CI Pigment Orange 64. It is preferable to use at least one or more pigments selected from this group.

[0025] Examples of inorganic pigments include carbon black, titanium oxide, red iron oxide, aluminum, mica, zinc oxide, barium sulfate, calcium carbonate, silica, etc. Also usable is a glittering pigment (Metashine; Nippon Sheet Glass Co., Ltd.) made of glass flakes or aggregate flakes as a base material and coated with a metal or metal oxide. From the standpoint of cost and coloring power, it is preferable to use carbon black for black ink, titanium oxide for white ink, aluminum for gold and silver ink, and mica for pearl ink.

[0026] The total content of the pigments is not particularly limited, but for example, in the ink layer forming composition, from the viewpoint of ensuring the coloring power of the composition, the content of the pigments is preferably 1 to 60 parts by mass, more preferably 5 to 40 parts by mass, relative to 100 parts by mass of the total amount of the composition. The total content of the white pigments may be 15 to 60 parts by mass, or may be 20 to 40 parts by mass, relative to 100 parts by mass of the total amount of the composition. The total content of the colored organic pigments may be 1 to 30 parts by mass, or may be 5 to 25 parts by mass, relative to 100 parts by mass of the total amount of the pigment composition. Any combination of these upper and lower limits may be used.

[0027] <<Resin>> The composition for forming the ink layer contains at least one type of resin A selected from the group consisting of acrylic resins, urethane resins, polyamide resins, rosin resins, and polyester resins. The composition for forming the ink layer may contain a resin other than the resin A. For example, it may contain other resins such as cellulose-based resins, ketone resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, cyclized rubbers, chlorinated rubbers, butyral resins, and petroleum resins. These may be used in appropriate combination.

[0028] -Urethane resin- The number average molecular weight of the urethane resin is preferably within the range of 15,000 to 100,000. If the number average molecular weight of the urethane resin is less than 15,000, the blocking resistance, chemical resistance, etc. of the ink layer forming composition tend to be low, and if it exceeds 100,000, the viscosity of the composition tends to be high, making it difficult to obtain a desired print density.

[0029] The urethane resin contained in the composition for forming the ink layer preferably uses polyester polyol and / or polyether polyol as its reaction raw material.

[0030] The number average molecular weight of the polyester polyol is preferably 3000 to 7000. If the number average molecular weight of the polyester polyol is less than 3000, the urethane resin film tends to be hard and the adhesion to the polyester film is likely to decrease. If the number average molecular weight is more than 7000, the urethane resin film tends to be fragile and the blocking resistance of the film is likely to decrease. On the other hand, the polyester polyol is preferably 1 to 50 parts by mass per 100 parts by mass of the urethane resin. If the polyester polyol is less than 1 part by mass, the solubility of the polyurethane resin in ketone, ester, and alcohol-based solvents decreases, and the adhesion, especially on high-performance barrier films, tends to decrease. In addition, the resolubility of the urethane resin film in the solvent decreases, and the reproducibility of the printed matter tends to decrease. If the amount exceeds 50 parts by mass, the urethane resin film tends to be excessively soft and the blocking resistance tends to be poor.

[0031] The number average molecular weight of the polyester polyol is a value measured by gel permeation chromatography (GPC) under the following conditions. Measurement equipment: High-speed GPC equipment (Tosoh Corporation "HLC-8220GPC") Column: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution) Standard sample: A calibration curve was prepared using the following standard polystyrene. (Standard polystyrene) "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0032] As the polyester polyol, for example, one obtained by a known esterification reaction between a compound having two or more hydroxyl groups and a polybasic acid can be used.

[0033] The above-mentioned compounds having two or more hydroxyl groups are used as chain extenders, and examples thereof include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, and neopentyl glycol. Glycols having a branched structure such as 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, and 2-methyl-1,8-octanediol; aliphatic polyols such as trimethylolpropane, trimethylolethane, pentaerythritol, saccharose, methylene glycol, glycerin, and sorbitol; and aromatic polyols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone, each having a number average molecular weight in the range of 50 to 400, can be used. These chain extenders may be used alone or in combination of two or more.

[0034] Examples of the polybasic acid that can be used include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalic acid, and anhydrides of these acids. These polybasic acids may be used alone or in combination of two or more kinds.

[0035] The polyether polyol preferably has a number average molecular weight of 100 to 4000. Examples of the polyether polyol include polyether polyols which are polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc. Specifically, known and general-purpose polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used, and among these, polyethylene glycol is preferred. By containing the polyester polyol and / or polyether polyol in the above range, adhesion, particularly to the substrate film, is significantly improved, resulting in excellent blocking resistance.

[0036] If the number average molecular weight of the polyether polyol is less than 100, the urethane resin film tends to become hard and the adhesion to the polyester film tends to decrease. If the number average molecular weight is more than 4000, the urethane resin film tends to become brittle and the blocking resistance of the film tends to decrease. The number average molecular weight of the polyether polyol can be determined by measuring it under the same conditions by gel permeation chromatography (GPC) as the polyester polyol above.

[0037] Examples of the diisocyanate compound used in the urethane resin in the ink layer forming composition include various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. that are generally used in the production of urethane resins. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, socyanate, isophorone diisocyanate (3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate; 5-isocyanato-1-(isocyanomethyl)-1,3,3-trimethylcyclohexane), dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanate-benzyl chloride, and dimer diisocyanate in which the carboxyl group of dimer acid is converted to an isocyanate group. These diisocyanate compounds can be used alone or in combination of two or more.

[0038] Examples of chain extenders used in the urethane resin in the ink layer forming composition include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, etc., as well as amines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. These chain extenders can be used alone or in combination of two or more.

[0039] Furthermore, the amine value of the urethane resin used in the composition for forming the ink layer is preferably 10.0 mgKOH / g or less. If the amine value exceeds 10.0 mgKOH / g, blocking resistance tends to deteriorate, and the stability of the second liquid after the addition of the curing agent decreases. From the viewpoint of maintaining good blocking resistance and second liquid stability while maintaining plate fogging resistance, adhesion, and extrusion lamination strength, the range of 1.0 to 5.0 mgKOH / g is more preferable, and the range of 1.0 to 3.5 mgKOH / g is even more preferable.

[0040] -Acrylic resin- The acrylic resin can be obtained by copolymerizing various (meth)acrylate monomers and, if necessary, other polymerizable unsaturated group-containing compounds.

[0041] The monomer constituting the acrylic resin is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-pentafluoropropyl (meth)acrylate, perfluorocyclohexyl (meth)acrylate, and glyceryl (meth)acrylate. (Meth)acrylic monomers such as ricinyl (meth)acrylate, allyl glycidyl ether, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, (meth)acrylamide, N-monoalkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, N-methylol (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, 2-aziridinylethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, acrolein, diacetone (meth)acrylamide, and acetoacetoxyethyl (meth)acrylate can be used. The above "(meth)acrylate" refers to either or both of acrylate and methacrylate, and "(meth)acrylic" refers to either or both of acrylic and methacrylic.

[0042] As the polymerizable unsaturated group-containing compound, in addition to the above (meth)acrylic monomers, vinyl acetate, vinyl propionate, vinyl versatate, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, (meth)acrylonitrile, styrene, α-methylstyrene, divinylstyrene, isoprene, chloroprene, butadiene, ethylene, tetrafluoroethylene, vinylidene fluoride, N-vinylpyrrolidone, etc. can also be used. These may be used alone or in combination of two or more.

[0043] The number average molecular weight of the acrylic resin is not particularly limited, but is preferably from 3,000 to 50,000, and more preferably from 10,000 to 30,000.

[0044] -Polyamide resin- The polyamide resin is obtained by reacting a polycarboxylic acid compound with a polyamine or a polyisocyanate compound. Examples of the polycarboxylic acid compound include succinic acid, maleic acid, fumaric acid, itaconic acid, azelaic acid, mesaconic acid, citraconic acid, sebacic acid, glutaconic acid, adipic acid, malonic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, nadic acid, methylnadic acid, octyl succinic acid, and anhydrides of these acids, polymerized fatty acids such as linoleic acid dimers and trimers, dodecanedioic acid, C21 dibasic acid, and dimer acids (polymerized fatty acids obtained by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid), etc.

[0045] Furthermore, aliphatic polycarboxylic acids having 7 to 20 carbon atoms, such as 1,2,4-butanetricarboxylic acid and 1,2,5-hexanetricarboxylic acid, alicyclic polycarboxylic acids having 9 to 20 carbon atoms, such as 1,2,4-cyclohexanetricarboxylic acid, aromatic polycarboxylic acids having 9 to 20 carbon atoms, such as 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid and pyromellitic acid, as well as trivalent or higher polycarboxylic acids, such as their anhydrides and lower alkyl (methyl, butyl, etc.) esters.

[0046] Examples of polyamines used to obtain polyamide resins include diamines such as ethylenediamine, propylenediamine, diaminobutane, diaminopentane, diaminohexane, diaminoheptane, diaminooctane, diaminodecane, and diaminododecane; and trivalent or higher amines such as diethylenetriamine and triethylenetetramine.

[0047] The number average molecular weight of the polyamide resin is not particularly limited, but is preferably from 5,000 to 20,000, and more preferably from 500 to 10,000.

[0048] -Rosin resin- The rosin resin may have 20% by mass or more of a rosin-derived structure, and the softening point (ring and ball method) is preferably 30°C to 180°C, more preferably 50 to 170°C. Suitable examples of the rosin resin include polymerized rosin resin, rosin-modified maleic acid resin, and rosin-modified fumaric acid resin. The acid value of the rosin resin is preferably 50 to 350 (mgKOH / g). Suitable examples of the rosin resin include Aradigm R-95 and Malquid No. 32 manufactured by Arakawa Chemical Industries, Ltd.

[0049] The weight average molecular weight of the rosin modified maleic acid resin or the rosin modified fumaric acid resin is preferably at least 500, more preferably at least 700, and even more preferably at least 1000. By setting it within the above range, it is possible to achieve a good balance between adhesion to a substrate and releasability in an alkaline solution.

[0050] The weight average molecular weight of the rosin modified maleic acid resin or rosin modified fumaric acid resin is preferably not more than 50,000, more preferably not more than 30,000, more preferably not more than 10,000, more preferably not more than 5,000, and more preferably not more than 2,000. By setting the weight average molecular weight within the above range, the viscosity of the ink can be reduced, and a balance between adhesion to the substrate and releasability in an alkaline solution can be achieved.

[0051] The weight average molecular weight of the rosin modified maleic acid resin or the rosin modified fumaric acid resin is preferably 500 to 50000, more preferably 700 to 520000, more preferably 1000 to 10000, and even more preferably 1000 to 5000. By setting it within the above range, printability can be improved.

[0052] -Polyester resin- The polyester resin can be any of various known polyester resins. The polyester resin can be obtained by reacting glycol with a dibasic acid or its derivative as an essential component. Of course, the polyester resin can be obtained by using an ester-forming derivative such as a dibasic acid anhydride or a dibasic acid lower alkyl ester instead of the dibasic acid, not only by polycondensation reaction but also by addition reaction or transesterification reaction. Examples of such polyester resins include aliphatic polyester polyols obtained by reacting an aliphatic glycol such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, decanediol, or cyclohexanedimethanol with an aliphatic dibasic acid such as succinic acid, adipic acid, sebacic acid, fumaric acid, suberic acid, azelaic acid, 1,10-decamethylenedicarboxylic acid, or cyclohexanedicarboxylic acid as an essential raw material component; and aromatic polyester polyols obtained by reacting an aliphatic glycol such as ethylene glycol, propylene glycol, or butanediol with an aromatic dibasic acid such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid as an essential raw material component. Examples of such polyester resins include the "Polylite" series manufactured by DIC Corporation and the "Kuraray Polyol" series manufactured by Kuraray Co., Ltd.

[0053] <<Resin content in the composition for forming the ink layer>> The content of the resin in the composition for forming the ink layer is not particularly limited, but is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, based on 100 parts by mass of the total amount of the composition. The total content is preferably 60 parts by mass or less, and more preferably 55 parts by mass or less. When two or more kinds of resins are contained in the composition for forming the ink layer, the preferable range of the content is the total amount of those resins contained.

[0054] <<Organic solvents>> The composition for forming the ink layer may contain an organic solvent. The organic solvent is not particularly limited, but examples thereof include aromatic hydrocarbon organic solvents such as toluene, xylene, Solvesso #100, Solvesso #150, etc.; aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, decane, etc.; and various ester-based organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, butyl propionate, etc. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, isopropyl alcohol, and normal propyl alcohol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and glycol ethers such as ethylene glycol (mono, di) methyl ether, ethylene glycol (mono, di) ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) methyl ether, propylene glycol (mono, di) methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di) methyl ether. Among these, various ester-based organic solvents and various alcohol-based organic solvents are preferred, and isopropyl alcohol and ethyl acetate are more preferred. These can be used alone or in a mixture of two or more.

[0055] The content of the organic solvent is not particularly limited, but is preferably 20% by mass or more, and more preferably 30% by mass or more, based on 100 parts by mass of the total amount of the composition for forming the ink layer, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, more preferably 60% by mass or less, and more preferably 55% by mass or less.

[0056] <<Other ingredients>> The composition for forming the ink layer may further contain other components such as auxiliaries and acidic additives, if necessary.

[0057] Examples of the auxiliary that can be used appropriately include waxes such as paraffin wax, polyethylene wax, and carnauba wax for imparting friction resistance, slipperiness, etc.; fatty acid amide compounds such as oleic acid amide, stearic acid amide, and erucic acid amide; silicone and non-silicone defoamers for suppressing foaming during printing; and dispersants. As the dispersant, nonionic dispersants are preferred.

[0058] The acid value of the dispersant is preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, and even more preferably 20 mgKOH / g or less, and may be, for example, 1 mgKOH / g or more, or even 3 mgKOH / g or more.

[0059] The content of the dispersant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, more preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 75 parts by mass or less, more preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less, relative to 100 parts by mass of the colorant (e.g., pigment).

[0060] As the acidic additive, for example, an organic acid or a resin having an acidic group can be used. The acid value of the acidic additive is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, and more preferably 50 mgKOH / g or more. The acid value is preferably 900 mgKOH / g or less, more preferably 850 mgKOH / g or less, more preferably 800 mgKOH / g or less, more preferably 750 mgKOH / g or less, more preferably 700 mgKOH / g or less, more preferably 650 mgKOH / g or less, more preferably 600 mgKOH / g or less, and more preferably 550 mgKOH / g or less. By setting it in the above range, it is possible to achieve both alkaline solution releasability and adhesion to other layers.

[0061] When emphasis is placed on releasability in an alkaline solution, the OH content is preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, more preferably 200 mgKOH / g or more, more preferably 300 mgKOH / g or more, more preferably 400 mgKOH / g or more, more preferably 500 mgKOH / g or more, and particularly preferably 550 mgKOH / g or more. When emphasis is placed on adhesion to other layers, the OH content is preferably 550 mgKOH / g or less, more preferably 500 mgKOH / g or less, more preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, and more preferably 200 mgKOH / g or less.

[0062] When importance is attached to both the alkaline solution releasability and adhesion to other layers, the acid value is preferably in the range of 1 to 900 mgKOH / g, more preferably 3 to 850 mgKOH / g, more preferably 5 to 800 mgKOH / g, more preferably 10 to 750 mgKOH / g, more preferably 20 to 700 mgKOH / g, more preferably 30 to 650 mgKOH / g, more preferably 40 to 600 mgKOH / g, and more preferably 50 to 550 mgKOH / g.

[0063] In addition, when emphasis is placed on releasability in an alkaline solution, 50 to 900 mgKOH / g is preferable, 65 to 900 mgKOH / g is preferable, 80 to 900 mgKOH / g is preferable, 100 to 900 mgKOH / g is more preferable, 200 to 900 mgKOH / g is more preferable, 300 to 900 mgKOH / g is more preferable, 400 to 900 mgKOH / g is more preferable, 500 to 900 mgKOH / g is more preferable, and 550 to 900 mgKOH / g is more preferable. In addition, when emphasis is placed on adhesion to other layers, 1 to 550 mgKOH / g is preferable, 1 to 500 mgKOH / g is more preferable, 1 to 400 mgKOH / g is more preferable, 1 to 300 mgKOH / g is more preferable, and 1 to 200 mgKOH / g is more preferable.

[0064] When both the alkaline solution releasability and the adhesion to other layers are satisfied, the molecular weight of the acidic additive is preferably 50 or more, preferably 60 or more, preferably 80 or more, preferably 100 or more, preferably 150 or more, preferably 200 or more, preferably 250 or more, and preferably 300 or more. Also, it is preferably 2000 or less, preferably 1800 or less, preferably 1500 or less, preferably 1200 or less, and preferably 1000 or less. The molecular weight range is preferably 50 to 2000, preferably 50 to 1800, preferably 50 to 1500, preferably 60 to 1500, preferably 80 to 1500, preferably 100 to 1500, preferably 150 to 1500, preferably 200 to 1500, preferably 250 to 1500, preferably 300 to 1500, preferably 300 to 1200, and preferably 300 to 1000.

[0065] The organic acid refers to a low molecular weight organic compound having an acidic group. Preferred examples of the low molecular weight compound having an acidic group include saturated fatty acids, unsaturated fatty acids, hydroxy acids, aromatic carboxylic acids, dicarboxylic acids, tricarboxylic acids, oxocarboxylic acids, and carboxylic acid derivatives, and these can be used singly or in combination.

[0066] Examples of saturated fatty acids include lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, decanoic acid, undecanoic acid, and dodecanoic acid. Examples of unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid. Examples of hydroxy acids include lactic acid, malic acid, and citric acid. Examples of aromatic carboxylic acids include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and ketone. Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimer acid, fumaric acid, maleic acid, azelaic acid, etc. Examples of the tricarboxylic acid include aconitic acid and trimer acid, etc. Examples of the oxocarboxylic acid include pyruvic acid and oxaloacetic acid, etc. Examples of the carboxylic acid derivative include amino acids and nitrocarboxylic acids, and these can be used singly or in combination. In addition, citric acid, butyric acid, caproic acid, enanthic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, eleostearic acid, arachidic acid, sebacic acid, etc. can comply with the so-called Swiss Ordinance, and it is preferable to use substances that comply with various regulations.

[0067] The acid value of the organic acid is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, more preferably 50 mgKOH / g or more, more preferably 60 mgKOH / g or more, more preferably 70 mgKOH / g or more, more preferably 80 mgKOH / g or more, more preferably 90 mgKOH / g or more, and particularly preferably 100 mgKOH / g or more. The acid value is preferably 900 mgKOH / g or less, more preferably 850 mgKOH / g or less, more preferably 800 mgKOH / g or less, more preferably 750 mgKOH / g or less, more preferably 700 mgKOH / g or less, more preferably 650 mgKOH / g or less, more preferably 600 mgKOH / g or less, and more preferably 550 mgKOH / g or less. By setting the acid value in the above range, it is possible to achieve both alkaline solution releasability and adhesion to other layers.

[0068] In addition, when emphasis is placed on the releasability in an alkaline solution, 100 mgKOH / g or more is preferable, 150 mgKOH / g or more is more preferable, 200 mgKOH / g or more is more preferable, 250 mgKOH / g or more is more preferable, 300 mgKOH / g or more is more preferable, 350 mgKOH / g or more is more preferable, 400 mgKOH / g or more is more preferable, 450 mgKOH / g or more is more preferable, 500 mgKOH / g or more is more preferable, and 550 mgKOH / g or more is more preferable. When emphasis is placed on the adhesion to other layers, 550 mgKOH / g or less is preferable, 500 mgKOH / g or less is more preferable, 400 mgKOH / g or less is more preferable, 300 mgKOH / g or less is more preferable, and 200 mgKOH / g or less is more preferable.

[0069] When importance is attached to both the alkaline solution releasability and adhesion to other layers, the acid value is preferably in the range of 1 to 900 mgKOH / g, more preferably 3 to 850 mgKOH / g, more preferably 10 to 800 mgKOH / g, more preferably 20 to 750 mgKOH / g, more preferably 30 to 700 mgKOH / g, more preferably 50 to 650 mgKOH / g, more preferably 80 to 600 mgKOH / g, and more preferably 100 to 550 mgKOH / g. In addition, when emphasis is placed on releasability in an alkaline solution, 100 to 900 mgKOH / g is preferable, 150 to 900 mgKOH / g is more preferable, 200 to 900 mgKOH / g is more preferable, 250 to 900 mgKOH / g is more preferable, 300 to 900 mgKOH / g is more preferable, 350 to 900 mgKOH / g is more preferable, 400 to 900 mgKOH / g is more preferable, 450 to 900 mgKOH / g is more preferable, 500 to 900 mgKOH / g is more preferable, and 550 to 900 mgKOH / g is more preferable. In addition, when emphasis is placed on adhesion to other layers, 1 to 550 mgKOH / g is preferable, 1 to 500 mgKOH / g is more preferable, 1 to 400 mgKOH / g is more preferable, 1 to 300 mgKOH / g is more preferable, and 1 to 200 mgKOH / g is more preferable.

[0070] The number of carbon atoms of the organic acid is preferably 3 or more, more preferably 4 or more, more preferably 5 or more, more preferably 6 or more, more preferably 7 or more, and more preferably 8 or more. By setting the number of carbon atoms of the organic acid within the above range, it is possible to improve adhesion with other layers. Furthermore, the number of carbon atoms of the organic acid is preferably 20 or less, more preferably 18 or less, and more preferably 16 or less. By setting the number of carbon atoms of the organic acid within the above range, it is possible to improve dispersibility in an aqueous medium. The range of the number of carbon atoms of the organic acid is preferably 3 to 20, more preferably 3 to 18, more preferably 4 to 18, more preferably 5 to 18, more preferably 6 to 18, more preferably 6 to 16, more preferably 7 to 16, and more preferably 8 to 16.

[0071] The solubility of the organic acid in 100 g of water at 25° C. is preferably less than 2 g, more preferably less than 1.8 g, even more preferably less than 1.5 g, and particularly preferably less than 1.2 g, when importance is attached to releasability from other layers and water resistance of the coating.

[0072] Examples of the resin having an acidic group include resins having an acid value such as cellulose resins, ketone resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, cyclized rubbers, chlorinated rubbers, butyral resins, and petroleum resins; resins that are radical copolymers such as styrene-(meth)acrylic resins, styrene-(anhydride)maleic acid resins, and terpene-(anhydride)maleic acid resins, which are copolymerized with polymerizable monomers having an acidic group, such as polymerizable monomers having a carboxyl group such as itaconic acid, maleic acid, fumaric acid, cinnamic acid, or their acid anhydrides, polymerizable monomers having a sulfonic acid group such as sulfonated styrene, and polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide; and acid-modified polyolefin resins (excluding the above resins), which can be used singly or in combination. As the resin having an acidic group, styrene-(anhydride)maleic acid resins are more preferable.

[0073] The acid value of the resin having an acidic group is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. The acid value is preferably 300 mgKOH / g or less, more preferably 280 mgKOH / g or less, more preferably 260 mgKOH / g or less, more preferably 240 mgKOH / g or less, more preferably 220 mgKOH / g or less, and more preferably 200 mgKOH / g or less. By setting it in the above range, it is possible to achieve both alkaline solution releasability and adhesion to other layers.

[0074] When emphasis is placed on releasability in an alkaline solution, the OH content is preferably 50 mgKOH / g or more, more preferably 60 mgKOH / g or more, more preferably 70 mgKOH / g or more, more preferably 80 mgKOH / g or more, more preferably 90 mgKOH / g or more, and particularly preferably 100 mgKOH / g or more. When emphasis is placed on adhesion to other layers, the OH content is preferably 200 mgKOH / g or less, more preferably 180 mgKOH / g or less, more preferably 160 mgKOH / g or less, more preferably 140 mgKOH / g or less, more preferably 120 mgKOH / g or less, and more preferably 100 mgKOH / g or less. When importance is attached to both the alkaline solution releasability and adhesion to other layers, the acid value is preferably in the range of 1 to 300 mgKOH / g, preferably 3 to 300 mgKOH / g, preferably 5 to 280 mgKOH / g, more preferably 10 to 260 mgKOH / g, more preferably 20 to 240 mgKOH / g, more preferably 30 to 220 mgKOH / g, more preferably 40 to 200 mgKOH / g, and more preferably 50 to 200 mgKOH / g.

[0075] When emphasis is placed on releasability in an alkaline solution, the KOH / g is preferably 50 to 300 mgKOH / g, more preferably 60 to 300 mgKOH / g, more preferably 70 to 300 mgKOH / g, more preferably 80 to 300 mgKOH / g, more preferably 90 to 300 mgKOH / g, and more preferably 100 to 300 mgKOH / g. When emphasis is placed on adhesion to other layers, the KOH / g is preferably 1 to 200 mgKOH / g, more preferably 1 to 180 mgKOH / g, more preferably 1 to 160 mgKOH / g, more preferably 1 to 140 mgKOH / g, more preferably 1 to 120 mgKOH / g, and more preferably 1 to 100 mgKOH / g.

[0076] When the resin having an acidic group is a styrene-maleic anhydride resin, the weight average molecular weight of the resin having an acidic group is preferably at least 500, more preferably at least 700, and even more preferably at least 1000. By setting the weight average molecular weight of the resin having an acidic group within the above range, it is possible to achieve a balance between adhesion to other layers and releasability in an alkaline solution.

[0077] Furthermore, when the resin having an acidic group is a styrene-maleic (anhydride) resin, the weight average molecular weight of the resin having an acidic group is preferably not more than 100,000, more preferably not more than 70,000, more preferably not more than 50,000, and still more preferably not more than 30,000. By setting the weight average molecular weight of the resin having an acidic group within the above range, the viscosity of the ink layer forming composition can be reduced, and further, a balance can be achieved between the adhesion to other layers and the releasability in an alkaline solution.

[0078] When the resin having an acidic group is a styrene-maleic (anhydride) resin, the weight average molecular weight range of the resin having an acidic group is preferably 500 to 100000, more preferably 700 to 30000, more preferably 1000 to 50000, and still more preferably 1000 to 30000. By setting the weight average molecular weight of the resin having an acidic group within the above range, printability can be improved.

[0079] The content of the acidic additive as a solid content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, more preferably 2 parts by mass or more, more preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and more preferably 50 parts by mass or less, based on 100 parts by mass of the total amount of the ink layer forming composition, from the viewpoints of resolubility of the ink layer forming composition, suppression of blocking of the printed matter, improvement of print density, and adhesion to other layers. The content of the acidic additive as a solid content is preferably 0.1 to 60 parts by mass, more preferably 0.5 to 55 parts by mass, more preferably 1 to 50 parts by mass, more preferably 1.5 to 45 parts by mass, and more preferably 2 to 40 parts by mass.

[0080] When the acidic additive is an organic acid, the content of the organic acid as a solid content is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, more preferably 2 parts by mass or more, more preferably 20 parts by mass or less, more preferably 18 parts by mass or less, more preferably 16 parts by mass or less, more preferably 14 parts by mass or less, more preferably 12 parts by mass or less, and more preferably 10 parts by mass or less. The range of the content of the organic acid as a solid content is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 18 parts by mass, more preferably 0.3 to 16 parts by mass, more preferably 0.5 to 14 parts by mass, more preferably 1 to 12 parts by mass, more preferably 1.5 to 10 parts by mass, and more preferably 2 to 10 parts by mass.

[0081] When the acidic additive is a resin having an acidic group, the content of the resin having an acidic group as a solid content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, more preferably 2 parts by mass or more, preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and more preferably 50 parts by mass or less, relative to 100 parts by mass of the total amount of the composition for forming the ink layer. The content of the acidic additive as a solid content is preferably 0.1 to 60 parts by mass, more preferably 0.5 to 55 parts by mass, more preferably 1 to 50 parts by mass, more preferably 1.5 to 45 parts by mass, and more preferably 2 to 40 parts by mass.

[0082] In addition to the above, water, wetting agents, adhesion promoters, leveling agents, antistatic agents, viscosity modifiers, metal chelates, trapping agents, antiblocking agents, isocyanate-based curing agents, and silane coupling agents may also be used as necessary.

[0083] The viscosity of the ink layer-forming composition, as measured at 25° C. using a Zahn Cup #4 manufactured by Rigo Co., Ltd., is preferably 6 seconds or more, more preferably 10 seconds or more, and even more preferably 13 seconds or more, and is preferably 25 seconds or less, more preferably 20 seconds or less, and even more preferably 18 seconds or less.

[0084] The surface tension of the ink layer forming composition is preferably 25 mN / m or more, more preferably 33 mN / m or more. Also, it is preferably 50 mN / m or less, more preferably 43 mN / m or less. By appropriately increasing the surface tension of the ink layer forming composition, it is possible to suppress dot bridging (a stain on the printing surface in which adjacent dots in a halftone dot portion are connected to each other) while maintaining the wettability of the ink layer forming composition to other layers, and by appropriately decreasing the surface tension of the ink layer forming composition, it is possible to increase the wettability of the ink layer forming composition to other layers and suppress repelling.

[0085] <Primer layer> The primer layer is a coating that can be removed from the substrate by treatment with an alkaline solution. The primer layer may be any known layer that can be detached from the substrate by treatment with an alkaline solution, and may be dissolved or swelled in the alkaline solution by hydrolysis, etc., to be detached from the substrate. As long as a film that can be detached from the substrate by treatment with an alkaline solution can be formed, the type of primer layer-forming composition that forms the primer layer is not particularly limited, but for example, a composition containing a urethane resin or polyvinyl alcohol is preferred, or a composition containing a resin having an acidic group is also preferred. Examples of the resin having an acidic group include resins having an acid value, such as polyurethane resins having an acid value, rosin-modified maleic acid resins and rosin-modified fumaric acid resins; radical copolymer resins such as (meth)acrylic resins, styrene-(meth)acrylic resins, styrene-maleic acid (anhydride) resins and terpene-maleic acid (anhydride) resins, which are copolymerized with polymerizable monomers having an acidic group, such as polymerizable monomers having a carboxyl group, such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, cinnamic acid, or acid anhydrides thereof, polymerizable monomers having a sulfonic acid group, such as sulfonated styrene, and polymerizable monomers having a sulfonamide group, such as vinylbenzenesulfonamide; and acid-modified polyolefin resins, which may be used singly or in combination. Among them, in the present invention, a composition containing a urethane resin or polyvinyl alcohol is more preferable, and a composition containing a urethane resin or polyvinyl alcohol having an acid value of 8 to 45 mgKOH / g is more preferable.

[0086] The composition for forming a primer layer may contain, in addition to the above-mentioned resin, a solvent such as an organic solvent or an aqueous solvent, an additive, etc. Examples of the additive include the same auxiliary agent and acidic additive that can be added to the composition for forming an ink layer described above. As preferred embodiments of the primer layer forming composition, there can be mentioned a first embodiment of the primer layer forming composition which is an aqueous urethane resin composition, and a second embodiment of the primer layer forming composition which contains polyvinyl alcohol. The primer layer forming compositions of these embodiments will be described below.

[0087] <<First aspect of composition for forming primer layer>> A first embodiment of the composition for forming a primer layer includes a composition for forming a primer layer made of an aqueous urethane resin composition. The aqueous urethane resin composition according to the present invention contains a urethane resin (A) and an aqueous medium (B). The aqueous urethane resin composition according to the present invention is a dispersion in an aqueous medium (B) of a urethane resin (A) obtained by reacting an aromatic polyester polyol (a1) containing an aromatic dicarboxylic acid (a1-1) as a raw material monomer with a polyisocyanate (a2), and, if necessary, a chain extender, etc. The concentration of aromatic rings derived from raw material monomers of the aromatic dicarboxylic acid (a1-1) in the urethane resin (A) is, for example, 1 mmol / g or more. The concentration of ester bond groups in the urethane resin (A) is, for example, 1 mmol / g or more. The acid value of the urethane resin (A) is, for example, 8 to 45 mgKOH / g.

[0088] <<<Urethane resin (A)>>> The urethane resin (A) is a general term for a polymeric compound having a urethane bond (-NHCOO-), and in the present invention, it is made of a reaction product obtained by reacting (crosslinking / curing reaction) an aromatic polyester polyol (a1) with a polyisocyanate (a2). The urethane resin (A) may contain, in addition to the aromatic polyester polyol (a1) and the polyisocyanate (a2), another polyol (a3), or may be a reaction product of the aromatic polyester polyol (a1), the polyisocyanate (a2), and the other polyol (a3).

[0089] -Aromatic polyester polyol (a1)- The aromatic polyester polyol (a1) can be produced, for example, by subjecting an aromatic dicarboxylic acid (a1-1) and a polyol (a1-2) to an esterification reaction.

[0090] Examples of the aromatic dicarboxylic acid (a1-1) that can be used when producing the aromatic polyester polyol (a1) include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-P,P'-dicarboxylic acid, as well as their acid anhydrides or ester-forming derivatives; aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and their ester-forming derivatives; and sulfonic acid group-containing aromatic dicarboxylic acids such as 5-sulfoisophthalic acid and their ester-forming derivatives.

[0091] In addition to the aromatic dicarboxylic acid (a1-1), an aliphatic carboxylic acid or an alicyclic carboxylic acid can be used in combination. For example, an aliphatic dicarboxylic acid such as succinic acid, succinic anhydride, adipic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, maleic anhydride, or fumaric acid, an alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, or an anhydride or ester-forming derivative thereof can be used. These can be used alone or in combination of two or more kinds.

[0092] Examples of the polyol (a1-2) that can be used include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, and neopentyl glycol.

[0093] Specifically, the aromatic dicarboxylic acid (a1-1) and the polyol (a1-2) can be reacted, if necessary, in the presence of a catalyst in a reaction vessel purged with an inert gas such as nitrogen under normal pressure or reduced pressure. The reaction is preferably carried out at a temperature in the range of 100°C to 300°C.

[0094] Examples of the catalyst that can be used include acetates of alkali metals or alkaline earth metals, and compounds containing zinc, manganese, cobalt, antimony, germanium, titanium, tin, zirconium, etc. Among these, it is preferable to use tetraalkyl titanates and tin oxalate, which are effective in transesterification reactions and polycondensation reactions.

[0095] When producing the urethane resin (A), other polyols (a3) ​​and the like can also be used in combination with the aromatic polyester polyol (a1) and the polyisocyanate (a2).

[0096] As the other polyol (a3), polyols similar to the above polyol (a1-2) can be used, such as relatively low molecular weight polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, and neopentyl glycol.

[0097] -Polyisocyanate (a2)- As the polyisocyanate (a2) that reacts with the polyol (a1) to form the urethane resin (A), for example, aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate, and aliphatic or aliphatic cyclic structure-containing diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate can be used alone or in combination of two or more. Among them, it is more preferable to use one or more selected from the group consisting of isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate from the viewpoint of improving the adhesion to the substrate and the deinking property of the resulting primer layer.

[0098] The urethane resin (A) can be produced, for example, in the absence of a solvent or in the presence of an organic solvent, by reacting the aromatic polyester polyol (a1), the polyisocyanate (a2), and, if necessary, the polyol (a3), and, if necessary, a chain extender. When the organic solvent is used, it is preferable to remove the organic solvent by a method such as distillation when dispersing the urethane resin (A) in the aqueous medium (B).

[0099] Examples of organic solvents that can be used when producing the urethane resin (A) include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetates such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; dimethylformamide and N-methylpyrrolidone, which can be used alone or in combination of two or more.

[0100] The chain extender that can be used when producing the urethane resin (A) can be used for the purpose of increasing the molecular weight of the urethane resin (A) and improving the durability of the resulting film or the like. As the chain extender that can be used in producing the urethane resin (A), polyamines and other compounds containing active hydrogen atoms can be used.

[0101] Examples of polyamines include diamines such as ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, and 1,4-cyclohexanediamine; N-hydroxymethylaminoethylamine, N-hydroxyethylaminoethylamine, N-hydroxypropylaminopropylamine, N-ethylaminoethylamine, and N-methylaminopropylamine; Benzene triamine, dipropylene triamine, triethylenetetramine; hydrazine, N,N'-dimethylhydrazine, 1,6-hexamethylenebishydrazine; succinic dihydrazide, adipic dihydrazide, glutaric dihydrazide, sebacic dihydrazide, isophthalic dihydrazide; β-semicarbazidopropionic hydrazide, 3-semicarbazido-propyl-carbazic acid ester, semicarbazido-3-semicarbazidomethyl-3,5,5-trimethylcyclohexane may be used, and it is preferable to use ethylenediamine.

[0102] Other active hydrogen-containing compounds that can be used include, for example, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, neopentyl glycol, sucrose, methylene glycol, glycerin, and sorbitol; phenols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone; and water.

[0103] The chain extender can be used when reacting the aromatic polyester polyol (a1) with the polyisocyanate (a2) or after the reaction. The chain extender can also be used when dispersing the urethane resin (A) in the aqueous medium (B) to make it aqueous.

[0104] -Characteristics of urethane resin (A)- The concentration of aromatic rings derived from raw material monomers of the aromatic dicarboxylic acid (a1-1) in the urethane resin (A) is preferably 1 mmol / g or more. The aromatic ring concentration can be determined by calculating the number of moles of aromatic rings contained in 1 g of the urethane resin (A). The specific calculation method will be described later. From the viewpoint of improving the adhesion to the substrate and deinking ability of the resulting primer layer, the aromatic ring concentration is preferably 1.5 mmol / g or more, and more preferably 2 mmol / g or more, and from the viewpoint of good film-forming properties of the primer layer, the aromatic ring concentration is preferably 6 mmol / g or less, and more preferably 5 mmol / g or less.

[0105] The concentration of ester bond groups in the urethane resin (A) is preferably 1 mmol / g or more. The ester bond concentration can be determined by calculating the number of moles of the ester bond groups contained in 1 g of the urethane resin (A). The specific calculation method will be described later. From the viewpoint of improving the adhesion to the substrate and the deinking ability of the obtained primer layer, the ester bond concentration is preferably 2 mmol / g or more, and more preferably 4 mmol / g or more, and from the viewpoint of good blocking resistance of the primer layer, the ester bond concentration is preferably 9 mmol / g or less, and more preferably 7 mmol / g or less.

[0106] The acid value of the urethane resin (A) is preferably 8 to 45 mgKOH / g. The acid value is the amount of acid in 1 g of resin calculated by titrating the acid with an alkali, converted into mg of potassium hydroxide, according to JIS K0070. If the acid value is 8 mgKOH / g or more, the aqueous dispersion stability can be improved, and is preferably 15 mgKOH / g or more, and more preferably 20 mgKOH / g or more.If the acid value is 45 mgKOH / g or less, the adhesion to the polyester substrate can be well ensured, and is preferably 40 mgKOH / g or less, and more preferably 30 mgKOH / g or less.

[0107] The mass of the raw material monomer of the polyisocyanate (a2) contained in 1 g of the urethane resin (A) divided by the NCO equivalent weight of the raw material monomer of the polyisocyanate (a2) is preferably 1.0 to 6.0 mmol / g. If this value is 1.0 mmol / g or more, the substrate adhesion and deinking properties of the resulting primer layer can be improved, and it is more preferable that the value is 1.5 mmol / g or more, and even more preferable that the value is 1.8 mmol / g or more. If it is 6.0 mmol / g or less, the film-forming properties of the primer layer can be ensured, and it is more preferably 5.0 mmol / g or less, and even more preferably 4.0 mmol / g or less.

[0108] The weight average molecular weight of the urethane resin (A) is preferably 10,000 to 100,000. From the viewpoints of blocking resistance to the substrate, hydrolysis resistance stability of the resin, etc., the weight average molecular weight of the urethane resin (A) is preferably 20,000 or more, more preferably 30,000 or more. Moreover, from the viewpoints of low viscosity during aqueous dispersion, productivity, etc., the weight average molecular weight is preferably 80,000 or less, more preferably 60,000 or less.

[0109] In the present invention, the weight average molecular weight was measured by gel permeation chromatography (GPC) under the above-mentioned measurement conditions.

[0110] The glass transition temperature of the urethane resin (A) is preferably from 0 to 110°C.

[0111] <<<Aqueous medium (B)>>> The aqueous medium (B) that serves as a solvent for the urethane resin (A) includes water, organic solvents that are miscible with water, and mixtures thereof. Examples of organic solvents that are miscible with water include alcohols such as methanol, ethanol, n- and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycol; and N-methyl-2-pyrrolidone. In the present invention, only water may be used, or a mixture of water and an organic solvent miscible with water may be used, or only an organic solvent miscible with water may be used. From the viewpoint of safety and environmental load, only water or a mixture of water and an organic solvent miscible with water is preferred, and only water is particularly preferred.

[0112] When dispersing the urethane resin (A) in the aqueous medium (B), a machine such as a homogenizer can be used as necessary.

[0113] The aqueous urethane resin composition of the present invention contains urethane resin (A) in the range of preferably 5% by mass to 50% by mass, more preferably 10% by mass to 25% by mass, based on the total amount of the aqueous urethane resin composition, and aqueous medium (B) in the range of preferably 50% by mass to 95% by mass, more preferably 75% by mass to 90% by mass, based on the total amount of the aqueous urethane resin composition.

[0114] <<<Other additives>>> In the aqueous urethane resin composition according to the present invention, various additives such as a film-forming assistant, a crosslinking agent, a curing accelerator, a plasticizer, an antistatic agent, a wax, a light stabilizer, a flow control agent, a dye, a leveling agent, a rheology control agent, an ultraviolet absorber, an antioxidant, a photocatalytic compound, an inorganic pigment, an organic pigment, and an extender pigment can be used as necessary.

[0115] Among the additives, the emulsifier and leveling agent may cause a decrease in the durability of the resulting film, etc., so when high durability is required for the film, etc., it is preferable to use them in an amount of 5 mass % or less based on the total amount of the aqueous urethane resin composition.

[0116] Furthermore, in order to form films and the like having excellent durability, the aqueous urethane resin composition of the present invention can be used in combination with various crosslinking agents. Examples of the crosslinking agent that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amino-based crosslinking agents, aziridine-based crosslinking agents, silane coupling agent-based crosslinking agents, carbodiimide-based crosslinking agents, and oxazolidine-based crosslinking agents. The crosslinking agent is preferably used in an amount of 30% by mass or less, and more preferably 20% by mass or less, based on the total amount of the urethane resin (A) from the viewpoints of improving adhesion to the substrate, improving deinking properties, etc. The crosslinking agent is preferably mixed and used immediately before coating the aqueous urethane resin composition of the present invention.

[0117] <<Primer layer-forming composition according to the second embodiment>> A second embodiment of the composition for forming a primer layer includes a composition for forming a primer layer containing polyvinyl alcohol. The primer layer containing polyvinyl alcohol is preferably a resin layer containing at least 25% by mass of polyvinyl alcohol. Hereinafter, the resin layer containing polyvinyl alcohol may be referred to as a PVA resin layer.

[0118] Polyvinyl alcohol is a colorless powder obtained by saponifying polyvinyl acetate. It is a water-soluble thermoplastic resin and is the raw material for the synthetic fiber Vinylon. It is generally abbreviated as Poval or PVA. Commercially available products include Poval, Elvanol, and Exeval manufactured by Kuraray Co., Ltd., Gohsenol manufactured by Mitsubishi Chemical Corporation, and Nippon Vinyl Acetate & Poval Co., Ltd.

[0119] The degree of saponification of polyvinyl alcohol is determined by the ratio of vinyl groups in polyvinyl acetate substituted with hydroxyl groups, and is preferably 90% or more. Examples of polyvinyl alcohol with a degree of saponification of 90% or more include, but are not limited to, the following commercially available products: Kuraray Co., Ltd. Poval "3-98, 5-98, 28-98, 60-98, 27-96", Kuraray Co., Ltd. Elvanol "71-30, 90-50, T-25, T-66", Kuraray Co., Ltd. Exeval "AQ-4104, HR-3010, RS-2117, RS-1717", Mitsubishi Chemical Co., Ltd. Gohsenol "N-300, NL-0 5, A-300, AL-06R", Japan Vinyl Acetate & Poval Co., Ltd.'s JC-25, JC-33, JC-40, JF-02, JF-03, JF-04, JF-05, JF-10, JF-17, JF-17L, JF-22, JM-17, JM-17L, JM-23, JM-26, JM-33, JT-05, JT-13Y, etc.

[0120] The composition for forming a primer layer containing polyvinyl alcohol can be obtained by mixing the above-mentioned aqueous medium (B) with polyvinyl alcohol (C). Furthermore, the polyvinyl alcohol-containing resin composition according to the present invention may contain various additives, etc., as necessary. Examples of additives include those listed in the <<<Other Additives>>> section above.

[0121] The primer layer-forming composition of the present invention can be used to form a primer layer by coating the primer layer-forming composition on a substrate. As described below, an ink layer made of an ink layer-forming composition can be formed on the primer layer. The primer layer can be easily removed by treatment with an alkaline solution. Since the primer layer can be easily peeled off from the substrate, the ink layer formed on the primer layer can also be easily removed from the substrate. The method for removing the primer layer will be described in detail later.

[0122] <Varnish layer> The varnish layer is formed using a varnish layer forming composition. The composition for forming a varnish layer generally contains a binder resin, a solvent such as an organic solvent or an aqueous solvent, and additives.

[0123] The varnish layer according to the present invention has the function of suppressing coloration of the alkaline solution by the ink layer. As long as it is possible to suppress discoloration caused by the ink layer dissolving in an alkaline solution, there are no particular restrictions on the type of varnish layer-forming composition that forms the varnish layer. However, it is preferable that the varnish layer-forming composition contains at least one type of resin (hereinafter also referred to as resin (B)) selected from the group consisting of urethane resins, cellulose derivatives, and polyester resins. Examples of the cellulose derivative include cellulose acetate propionate resin, cellulose acetate butyrate resin, and nitrocellulose resin.

[0124] <<Cellulose acetate propionate resin>> Cellulose acetate propionate resin (hereinafter sometimes referred to as CAP) is a resin obtained by triesterifying cellulose with acetic acid and propionic acid, followed by hydrolysis. Since there is a tendency for a composition to be obtained that has an excellent coloration suppression effect per 100 parts by mass of the total amount of CAP, it is preferable to use one having an acetyl group of 0.3 to 2.5 parts by mass, a propionyl group of 42 to 46 parts by mass, and a hydroxyl group of 1.8 to 5 parts by mass.

[0125] <<Cellulose acetate butyrate resin>> Cellulose acetate butyrate resin (hereinafter sometimes referred to as CAB) is a resin obtained by triesterifying cellulose with acetic acid and butyric acid, followed by hydrolysis. Since there is a tendency for a composition to be obtained that has excellent coloration suppression effect per 100 parts by mass of the total amount of CAB, it is preferable to use one having 2 to 30 parts by mass of acetyl groups, 17 to 53 parts by mass of butyryl groups, and 1 to 5 parts by mass of hydroxyl groups.

[0126] <<Nitrocellulose resin>> As the nitrocellulose resin, a general cellulose nitrate obtained by treating cellulose with a mixed acid of nitric acid and sulfuric acid can be used. In addition, in order to adjust the viscosity of the composition, two or more types of products with different viscosity standards (e.g., H20 equivalent and L1 / 4 equivalent) according to JIS K-6703 (industrial nitrocellulose) may be mixed and used.

[0127] The varnish layer forming composition may contain other resins in addition to the at least one type of resin (B) selected from the group consisting of the above-mentioned urethane resins, cellulose derivatives, and polyester resins.

[0128] Furthermore, the varnish layer-forming composition according to the present invention is preferably a composition capable of forming a varnish layer having a heat-resistant coating function. Because the varnish layer has a heat-resistant coating function, it can effectively suppress coloration of the alkaline solution when the ink layer detaches from the substrate.

[0129] As a varnish forming composition that forms a varnish layer having a heat-resistant coating function, it is preferable to contain, for example, a compound having a cellulose skeleton, a benzene ring skeleton, an isocyanuric ring skeleton, or an alicyclic skeleton, whose homopolymer has a glass transition temperature (hereinafter sometimes referred to as Tg) of 100°C or higher. Specific examples of resins contained in the varnish forming composition include cellulose derivatives such as nitrocellulose (nitrocellulose), cellulose acetate, cellulose propionate, and cellulose butyrate; polyester resins having a benzene ring, such as phthalic acid, naphthalene dicarboxylic acid, and an ethylene oxide (hereinafter sometimes referred to as EO) adduct of bisphenol A, and / or an alicyclic skeleton, such as cyclopentanediol and dimethyloltricyclodecane; and aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate and norbornene diisocyanate; and / or urethane resins in which isocyanuric triisocyanate is bonded to a polyol, and / or tris(2-hydroxyethyl)isocyanurate. The varnish forming composition may contain a polyisocyanate using the above-mentioned isocyanate as a curing agent (crosslinking agent). In addition, the varnish forming composition may preferably contain a compound having a benzene ring and an unsaturated double bond, such as styrene or phenoxydiethylene glycol acrylate, and / or a compound having an alicyclic structure and an unsaturated double bond, such as isobornyl acrylate or dicyclopentanyl acrylate, and a radical copolymer such as (meth)acrylate. In addition, in consideration of adhesion to olefin films, a resin with a low Tg may be mixed and used. The total amount of the cellulose skeleton, benzene ring skeleton, isocyanuric ring skeleton and alicyclic skeleton of the above-mentioned compound is preferably 20 to 90 mass %, and more preferably 30 to 80 mass %, of the solid content of the varnish forming composition.

[0130] As a preferred embodiment of the varnish layer forming composition according to the present invention, (i) a composition for forming a varnish layer containing at least a urethane resin and a cellulose derivative, or (ii) A composition for forming a varnish layer containing at least a urethane resin, a cellulose derivative, and a polyisocyanate.

[0131] As described above, the varnish layer-forming composition according to the present invention preferably contains a polyisocyanate curing agent (crosslinking agent), and the varnish layer according to the present invention is preferably a crosslinked coating film formed by the varnish layer-forming composition. By forming the varnish layer as a crosslinked coating film, coloring of the alkaline solution when the ink layer is detached from the substrate can be more preferably suppressed.

[0132] The solvent contained in the composition for forming the varnish layer may be an organic solvent or water, and for example, the same organic solvents and aqueous media as those described in the <<Organic Solvent>> section above or those described in the <<<Aqueous Medium (B)>>> section in <<Primer Layer>> can be used.

[0133] The additives contained in the composition for forming the varnish layer are not particularly limited, and may include, for example, extender pigments, pigment dispersants, leveling agents, defoamers, waxes, plasticizers, anti-blocking agents, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, etc., and may also include the various additives described in the <<<Other Additives>>> column in the <Primer Layer> above.

[0134] <<Content of Resin B in the composition for forming the varnish layer>>> The content of resin B is, for example, 2 parts by mass or more, more preferably 4 parts by mass or more, based on 100 parts by mass of the total amount of the composition for forming a varnish layer. The content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less. If the content of resin B is equal to or more than the lower limit, a composition having excellent coloring suppression effect tends to be obtained. If the content of resin B is equal to or less than the upper limit, a composition having excellent stability tends to be obtained. When two or more kinds of resins B are contained, the preferable range of the content is the total amount of those resins contained.

[0135] <Method of producing the composition> The method for producing the various compositions according to the present invention (the composition for forming an ink layer, the composition for forming a primer layer, and the composition for forming a varnish layer are collectively referred to simply as the composition) is not particularly limited, and a conventionally known method can be used. The components of the composition may all be mixed together at once, or may be mixed in portions, such as by first mixing a portion to produce a premix and then mixing it with the other components. The mixing method is not particularly limited, and examples thereof include a method of stirring and mixing with a mixer or the like, a method using a three-roll mill, and a method using a dispersing machine such as a bead mill.

[0136] The composition according to the present invention can be used for any of the known and commonly used applications, such as printing ink, paint, water-based ink for inkjet recording, etc. For use in printing ink, etc., a composition for forming an ink layer is necessarily used to form an ink layer, but in the present invention, the primer layer formed with the composition for forming a primer layer and the varnish layer formed with the composition for forming a varnish layer are both used in printing ink, etc. together with the ink layer, so in the present invention, the meaning of the "composition" used in printing ink, etc. includes not only the composition for forming an ink layer, but also the composition for forming a primer layer and the composition for forming a varnish layer.

[0137] <Printing ink> The composition according to the present invention can be used as a printing ink. The printing ink is not particularly limited as long as it contains the composition according to the present invention, and can be obtained with a known composition.

[0138] The printing ink may contain, as necessary, various additives contained in ordinary printing inks, such as organic or inorganic fillers, antistatic agents, antifoaming agents, viscosity modifiers, polymerization inhibitors, light resistance stabilizers, weather resistance stabilizers, heat resistance stabilizers, ultraviolet absorbers, antioxidants, leveling agents, pigment dispersants, and waxes.

[0139] <Printing on substrate> The printing ink using the composition according to the present invention has excellent adhesion to substrates and can be used for printing on paper, synthetic paper, cloth, thermoplastic resin films, plastic products, steel plates, etc., and is useful as an ink for gravure printing using a gravure printing plate made by electronic engraving or the like, or for flexographic printing using a flexographic printing plate made by a resin plate or the like.

[0140] The thickness of the printing ink formed by the gravure printing method or the flexographic printing method is, for example, preferably 10 μm or less, and more preferably 5 μm or less.

[0141] <Laminate> By printing the composition of the present invention or a printing ink using the composition onto the surface of a substrate directly or via another layer, a primer layer, an ink layer, and a varnish layer can be laminated on the substrate in that order, thereby obtaining a printed item consisting of a laminate of the substrate and these layers. Here, the other layer is not particularly limited, and may be a single layer or multiple layers. For example, each of the primer layer, the ink layer, and the varnish layer may be composed of two or more layers.

[0142] <<Specific layer structure of the laminate>> The printed matter and laminate of the present invention may have the following configurations. · Substrate / Primer layer / Ink layer / Varnish layer

[0143] <<Laminate manufacturing>> The laminate according to the present invention can be produced, for example, by the following method. A primer layer forming composition is printed on a plastic substrate by a printing method such as gravure printing or flexographic printing. Next, an ink layer is formed as a printed layer by printing an ink layer forming composition on the primer layer by a printing method such as gravure printing or flexographic printing. Next, a varnish layer forming composition is printed on the ink layer by a printing method such as gravure printing or flexographic printing to form a varnish layer. This makes it possible to obtain a laminate (substrate / primer layer / ink layer / varnish layer).

[0144] The compositions according to the present invention can be applied to a substrate using a known printing method such as gravure printing, flexographic printing, etc. In addition to the above-mentioned gravure printing and flexographic printing, known printing methods include, for example, a T-die coater, a lip coater, a knife coater, a curtain, an inkjet, a bar coater, a roll coater, a spray coater, a comma coater, a reverse roll coater, a direct gravure coater, a reverse gravure coater, an offset gravure coater, a roll kiss coater, a reverse kiss coater, a kiss gravure coater, a reverse kiss gravure coater, an air doctor coater, a wire bar coater, a dip coater, a blade coater, a brush coater, a die slot coater, an offset printing machine, a screen printing machine, etc., or a combination of two or more coating methods can be used. When printing, the ink is diluted with a diluting solvent, for example, a mixture of water and an alcohol-based organic solvent such as ethyl alcohol, isopropyl alcohol, or normal propyl alcohol, to a viscosity and concentration suitable for various printing methods such as gravure printing and flexographic printing, and supplied to each printing unit either alone or in a mixture.

[0145] In addition, the method of applying the primer layer-forming composition onto the substrate can be an inline coating method in which the primer layer-forming composition is applied during a substrate stretching process (e.g., a biaxial stretching process) and then a stretching process is performed, or an offline coating method in which the primer layer-forming composition is applied and dried after the substrate stretching process (e.g., a biaxial stretching process) to form a primer layer.

[0146] The primer layer formed from the primer layer-forming composition of the present invention has good adhesion to the substrate, and the laminate of the present invention has excellent adhesion between the substrate and the printed layer. In addition, the laminate of the present invention can remove the primer layer in a simple manner by using an alkaline solution, and the substrate and the printing layer, which is the ink layer, can be easily peeled off. However, the primer layer of the laminate of the present invention will not be peeled off even if an alkaline solution is applied under temperature conditions in which it is normally used. Therefore, under temperature conditions in which it is normally used, even if an alkaline solution happens to adhere to the laminate, it can be used without worrying about peeling.

[0147] (Manufacturing method for recycled substrates) In the present invention, the primer layer of the printed matter of the present invention described above is removed from the substrate by treatment with an alkaline solution, and the ink layer and varnish layer are also removed at the same time, thereby producing a recycled substrate. "Detachment" refers to the peeling off of the coating due to swelling, dissolution, erosion, etc. caused by the alkaline solution treatment. In the present invention, the primer layer can be peeled off due to swelling, dissolution, erosion, etc. caused by the alkaline solution treatment. In one embodiment of the present invention, a primer layer provided on a substrate is detached by an alkaline solution treatment. The detachment of the primer layer causes the ink layer and the varnish layer to be detached from the substrate together with the primer layer. When the ink layer dissolves in an alkaline solution, the alkaline solution is colored, but the varnish layer that is detached together with the ink layer can contribute to suppressing coloration of the alkaline solution.

[0148] <How to remove the coating from the substrate> The detachment step includes a step of immersing the printed matter in an alkaline solution while heating and stirring at 20 to 90° C. or ultrasonically vibrating the printed matter. Heating and stirring and ultrasonic vibration may be performed simultaneously. The heating temperature is preferably 30° C. or higher, more preferably 40° C. or higher, more preferably 50° C. or higher, and more preferably 60° C. or higher, and it is more preferable to perform heating and stirring and ultrasonic vibration simultaneously.

[0149] The alkaline solution used in the desorption step is not limited, but preferably has a pH of 9 or higher, and is preferably an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, an aqueous solution of sodium hydrogen carbonate, an aqueous solution of potassium hydrogen carbonate, an aqueous solution of sodium dihydrogen carbonate, an aqueous solution of potassium dihydrogen carbonate, etc. The aqueous solutions of sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium dihydrogen carbonate, potassium dihydrogen carbonate, etc. are preferably aqueous solutions with a concentration of 0.5% by mass to 10% by mass, and more preferably aqueous solutions with a concentration of 1% by mass to 5% by mass.

[0150] The alkaline solution may also contain a water-soluble organic solvent. Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol dibutyl ether, diethylene glycol monomethyl ether (methyl carbitol), diethylene glycol dimethyl ether, diethylene glycol monoethyl ether (carbitol), diethylene glycol diethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, and triethylene glycol. Examples of such an alkyl ether include glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methylene dimethyl ether (methylal), propylene glycol monobutyl ether, tetrahydrofuran, acetone, diacetone alcohol, acetonylacetone, acetylacetone, ethylene glycol monomethyl ether acetate (methyl cellosolve acetate), diethylene glycol monomethyl ether acetate (methyl carbitol acetate), diethylene glycol monoethyl ether acetate (carbitol acetate), ethyl hydroxyisobutyrate, and ethyl lactate. These may be used alone or in combination of two or more.

[0151] The content of the water-soluble organic solvent in the alkaline solution is preferably 0.1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass. The alkaline solution may also contain a water-insoluble organic solvent. Specific examples of the water-insoluble organic solvent include alcohol-based solvents such as n-butanol, 2-butanol, isobutanol, and octanol; aliphatic hydrocarbon-based solvents such as hexane, heptane, and normal paraffin; aromatic hydrocarbon-based solvents such as benzene, toluene, xylene, and alkylbenzene; halogenated hydrocarbon-based solvents such as methylene chloride, 1-chlorobutane, 2-chlorobutane, 3-chlorobutane, and carbon tetrachloride; ester-based solvents such as methyl acetate, ethyl acetate, and butyl acetate; ketone-based solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; and ether-based solvents such as ethyl ether and butyl ether. These can be used alone or in combination of two or more.

[0152] The alkaline solution may contain a surfactant. Examples of the surfactant include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc., and among these, anionic surfactants, nonionic surfactants, and amphoteric surfactants are preferred, and nonionic surfactants are more preferred.

[0153] Examples of the anionic surfactant include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate ester salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates. Specific examples of these include dodecylbenzenesulfonates, isopropylnaphthalenesulfonates, monobutylphenylphenol monosulfonates, monobutylbiphenylsulfonates, and dibutylphenylphenol disulfonates.

[0154] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylol amides, alkyl alkanol amides, acetylene glycol, oxyethylene adducts of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers, and the like. Among these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylol amides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers are preferred.

[0155] Other surfactants that can be used include silicon-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; and biosurfactants such as spiculisporic acid, rhamnolipids, and lysolecithin.

[0156] These surfactants can be used alone or in combination of two or more. When a surfactant is added, the amount of the surfactant added is preferably in the range of 0.001 to 2 mass %, more preferably 0.001 to 1.5 mass %, and even more preferably 0.01 to 1 mass %, based on the total amount of the alkaline solution.

[0157] When these surfactants are used, the alkaline solution tends to become more discolored after detachment than when the alkaline solution is used alone, but when the primer layer detaches from the substrate, the varnish layer that is detached together with the ink layer can effectively suppress discoloration of the treatment solution.

[0158] The target printed matter or laminate is immersed in, for example, a treatment tank in an alkaline solution heated or ultrasonically vibrated at 20 to 90° C. The heating method is not particularly limited, and known heating methods using heat rays, infrared rays, microwaves, etc. can be used. In addition, ultrasonic vibration can be, for example, a method in which an ultrasonic vibrator is attached to the treatment tank and ultrasonic vibration is applied to the warm water or alkaline solution.

[0159] The alkaline solution is preferably stirred during immersion. Examples of the stirring method include a method of mechanically stirring the dispersion of the printed matter or laminate contained in the treatment tank with a stirring blade, a method of water flow stirring with a water flow pump, and a method of bubbling with an inert gas such as nitrogen gas, and these may be used in combination to achieve efficient peeling.

[0160] The time for immersing the printed matter or laminate in the alkaline solution varies depending on the composition of the printed matter, but is generally in the range of 2 minutes to 48 hours. In the present invention, it is not necessary for 100% of the coating in the printed matter to be completely detached from the substrate, but it is preferable that 60% or more of the coating detaches from 100% by mass of the coating, more preferably 70% or more by mass, even more preferably 80% or more by mass, and particularly preferably 90% or more by mass.

[0161] In the desorption step, the number of times of immersion in the alkaline solution may be one or several times. That is, the immersion may be performed once, and then the process of recovering the separated film substrate may be performed, or the immersion may be performed several times, and then the process of recovering the film substrate may be performed. When the immersion is performed several times in the desorption step, the concentration of the alkaline solution may be changed. In addition, during the desorption step, known processes such as washing with water and drying may be appropriately added.

[0162] The printed matter of the present invention has a coating formed on a substrate, the coating being composed of a removable primer layer, an ink layer containing a colorant, and a varnish layer. Therefore, the presence of the varnish layer can effectively suppress discoloration of the alkaline treatment solution when the coating is detached in the detachment process. EXAMPLES

[0163] The contents and effects of the present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. Note that "parts" and "%" shown below are all based on mass.

[0164] <Concentration of aromatic rings derived from raw material monomer of aromatic dicarboxylic acid (a1-1) (mmol / g)> The number of moles of aromatic rings contained in 1 g of urethane resin is calculated based on the raw materials used in the synthesis of the aromatic polyester polyol and their blend amounts. It is determined by dividing the mass of the raw material monomer of aromatic dicarboxylic acid (a1-1) contained in 1 g of the urethane resin by the molecular weight of the raw material monomer of aromatic dicarboxylic acid (a1-1).

[0165] <Ester bond concentration (mmol / g)> The number of moles of ester bond groups contained in 1 g of urethane resin is calculated based on the raw materials used in the synthesis of the aromatic polyester polyol and their blend amounts. First, the concentration of ester bond groups in 1 g of the aromatic polyester polyol (a1) is calculated by the following formula (I): The formula (I) takes into consideration dehydration due to ester formation.

[0166]

number

[0167] <Acid value (mgKOH / g)> The COOH groups contained in 1 g of urethane resin are calculated as the number of mg of KOH required when titrated using the potassium hydroxide method.

[0168] <Urethane + urea functional group concentration (mmol / g)> The mass of the raw material monomer of polyisocyanate (a2) contained in 1 g of the urethane resin is divided by the NCO equivalent weight of the raw material monomer of polyisocyanate (a2).

[0169] <Weight average molecular weight> The weight average molecular weight is measured by gel permeation chromatography (GPC).

[0170] <Glass transition temperature (℃)> The glass transition temperature is measured by differential scanning calorimetry.

[0171] <Polyol hydroxyl value> The measurement is performed according to the method described in JIS K1557-1.

[0172] (Layer forming composition) The layer-forming compositions used in the examples and comparative examples are as follows. [Ink composition] [[Ink A]] <Pigments> Pigment: Phthalocyanine blue pigment (DIC FASTOGEN BLUE FA5380) <Resin> Nitrocellulose resin 30% solution Nobel nitrocellulose DLX5-8, 30% non-volatiles, ethyl acetate:IPA solution · Urethane resin 30% solution DIC urea urethane resin, number average molecular weight 14,000, non-volatile content 30%, ethyl acetate:IPA soluble <Organic solvent> Isopropyl alcohol ·Normal propyl alcohol Ethyl Acetate Propyl acetate Methylcyclohexane The mixing ratio of each of the above raw materials is as shown in Table 1-1 below.

[0173] [[Ink B]] <Pigments> Pigment: Phthalocyanine blue pigment (DIC FASTOGEN BLUE FA5380) <Resin> Acrylic resin 50% solution DIC Acrydic WCL-1419, number average molecular weight 16,000, non-volatile content 50%, ethyl acetate:IPA solution Vinyl chloride-vinyl acetate copolymer resin 25% solution Solvin A manufactured by Nissin Chemical Industry Co., Ltd., non-volatile content 25%, soluble in methyl ethyl ketone Cellulose acetate butyrate 20% solution Cellulose acetate butyrate resin (Eastman Chemical Company CAB-381-0.1), non-volatile content 20%, ethyl acetate soluble <Organic solvent> Isopropyl alcohol Methyl ethyl ketone Ethyl Acetate ·toluene Propyl acetate The mixing ratio of each of the above raw materials is as shown in Table 1-2 below.

[0174] [[Ink C]] <Pigments> Pigment: Phthalocyanine blue pigment (DIC FASTOGEN BLUE FA5380) <Resin> Nitrocellulose resin 40% solution Nobel nitrocellulose DLX5-8, 40% non-volatiles, ethyl acetate:IPA solution Acrylic resin 50% solution DIC Acrydic WCL-1419, number average molecular weight 16,000, non-volatile content 50%, ethyl acetate:IPA solution <Organic solvent> Isopropyl alcohol Propyl acetate Propylene glycol monomethyl ether The mixing ratio of each of the above raw materials is as shown in Table 1-3 below.

[0175] [[Ink D]] <Pigments> Pigment: Phthalocyanine blue pigment (DIC FASTOGEN BLUE FA5380) <Resin> Nitrocellulose resin 30% solution Nobel nitrocellulose DLX5-8, 30% non-volatiles, ethyl acetate:IPA solution Polyamide resin 40% solution In a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 100 parts of dimer acid (Haridimer 270S; manufactured by Harima Chemicals Co., Ltd.), 1 part of tall oil fatty acid (Hartall FA-1; manufactured by Harima Chemicals Co., Ltd.), 5 parts of sebacic acid, 10 parts of ethylenediamine, 5 parts of hexamethylenediamine and 0.24 parts of triphenylphosphine were put, and the system was made into a nitrogen atmosphere, and the temperature was slowly raised to 200 ° C. while stirring uniformly under a nitrogen gas flow. Then, dehydration condensation was carried out at 200 ° C. for 5 hours while stirring, and isopropyl alcohol / industrial ethanol / methylcyclohexane (20 / 20 / 60 mass ratio) was added to obtain a tall fatty acid-derived dimer acid modified polyamide resin solution with a solid content of 40%, a softening point of 123 ° C., an amine value of 2, an acid value of 8 and a number average molecular weight of 10,000. <Organic solvent> Isopropyl alcohol ·Normal propyl alcohol Methylcyclohexane Ethylene glycol monopropyl ether The mixing ratio of each of the above raw materials is as shown in Table 1-4 below.

[0176] [Primer composition] Primer composition 1 (also referred to as primer 1) to primer composition 2 (also referred to as primer 2) are as follows. [[Primer 1]] 100 parts of urethane resin 1 was mixed with 9 parts of "Carbodilite SV-02" manufactured by Nisshinbo Chemical Inc., and then diluted with isopropyl alcohol (IPA) to a solid content of 10% to obtain a primer-forming composition consisting of an aqueous urethane resin composition containing a crosslinking agent. <Urethane resin 1> Urethane resin 1 was synthesized as follows. A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 0.74 g of polyol a, 0.20 g of isophorone diisocyanate, and 0.06 g of 2,2'-dimethylolpropionic acid, and the mixture was reacted at 75°C for 8 hours under a nitrogen stream to obtain urethane resin 1. Polyol a was prepared by mixing and reacting 0.32 g of terephthalic acid (TPA), 0.32 g of isophthalic acid (IPA), 0.13 g of ethylene glycol (EG), and 0.23 g of diethylene glycol (DEG) to produce an aromatic polyester polyol. The composition and physical properties of polyol a are shown in Table 2-1 below. The composition and physical properties of urethane resin 1 are shown in Table 2-2 below. Hereinafter, Table 2-1 and Table 2-2 will be collectively referred to as Table 2.

[0177] The aromatic ring concentrations shown in Table 2 were determined as follows. The urethane resin 1 will be used as an example. First, the aromatic ring concentration in 1 g of polyol a is calculated. Calculate the mass ratio of the raw material monomer of aromatic dicarboxylic acid (a1-1) containing an aromatic ring to the molecular weight of that monomer (if there are multiple raw material monomers of aromatic dicarboxylic acid (a1-1), calculate the sum). {0.32 (terephthalic acid content in polyol a) / 166 (molecular weight of terephthalic acid) + 0.32 (isophthalic acid content in polyol a) / 166 (molecular weight of isophthalic acid)}×1000=3.8mmol / g Next, the product of the aromatic ring concentration in 1 g of the aromatic polyester polyol (a1) and the proportion of the aromatic polyester polyol (a1) in 1 g of the urethane resin is calculated, to calculate the aromatic ring concentration in 1 g of the urethane resin. 3.84 (aromatic ring concentration of polyol a) × 0.74 (content of polyol a in urethane resin 1) = 2.8 mmol / g

[0178] The ester bond group concentrations shown in Table 2 were determined as follows. The urethane resin 1 will be used as an example. First, the concentration of ester bond groups in 1 g of polyol a is calculated. When the number of moles of carboxylic acid in 1 g of the aromatic polyester polyol (a1) is a, a can be calculated as follows. a = {0.32 (terephthalic acid content in polyol a) / 166 (molecular weight of terephthalic acid) + 0.32 (isophthalic acid content in polyol a) / 166 (molecular weight of isophthalic acid)} x 2 (the raw material monomer for aromatic dicarboxylic acid (a1-1) contains two carboxylic acids) = 0.00771 Next, the determined a is substituted into the above formula (I). ·{a / (1-a×18(amount of water to be removed))}×1000=8.9mmol / g Next, the product of the ester bond group concentration in 1 g of aromatic polyester polyol (a1) and the proportion of aromatic polyester polyol (a1) in 1 g of urethane resin is calculated, to calculate the ester bond group concentration in 1 g of urethane resin. 8.9 (ester bond group concentration of polyol a) × 0.74 (polyol a content in urethane resin 1) = 6.6 mmol / g

[0179] The urethane + urea functional group concentrations shown in Table 2 were determined as follows. The urethane resin 1 will be used as an example for explanation. 0.2 (Isophorone diisocyanate content in urethane resin 1) ÷ 111.15 (NCO equivalent weight of isophorone diisocyanate) = 1.8 mmol / g Here, the NCO equivalent weight of isophorone diisocyanate is calculated by dividing the molecular weight of isophorone diisocyanate by 2, i.e., 222.3÷2=111.15.

[0180] [[Primer 2]] Poval 28-98 (polyvinyl alcohol having a saponification degree of 90% or more) manufactured by Kuraray Co., Ltd. was diluted with water to 10% by mass to obtain a primer-forming composition containing PVA (polyvinyl alcohol).

[0181] [Varnish composition] Varnish composition 1 (also referred to as Varnish 1) to varnish composition 3 (also referred to as Varnish 3) were prepared as shown in Table 3 below. In Table 3 below, the abbreviations are as follows: CAP-504-0.2: Cellulose acetate propionate manufactured by Eastman Chemical Company CAB-1000: Cellulose Acetate Butyrate manufactured by Eastman Chemical Company NITROCELLULOSE DLX5-8: Nitrocellulose manufactured by Nobel NC LX-470EL: Polyurethane polyol manufactured by DIC KW-75: Aromatic polyisocyanate manufactured by DIC

[0182] Example 1 <Production of printed matter> The prepared primer composition was printed on a substrate (PE film) using bar coater #4 as a solid layer measuring 240 mm in length and 80 mm in width, then dried with a dryer and left at room temperature for at least one day to form a primer layer. Subsequently, the prepared ink composition was printed on the dried primer layer using a bar coater #4, and after printing, it was dried with a dryer to form an ink layer. Next, the prepared varnish composition was printed on the ink layer using bar coater #4, and after printing, it was dried with a dryer to form an OP varnish layer, which was then aged at 40° C. for 3 days. As a result of the above, a printed matter was obtained consisting of a laminate in which a primer layer, an ink layer, and an OP varnish layer were laminated on a substrate.

[0183] <Evaluation item 1: Ink peeling test> [Alkaline solution] A peeling test was carried out under each of the following conditions, and the ease of peeling under each condition was compared. Sodium hydroxide 0.5% by mass, surfactant 0.3%, 70℃ Here, the surfactant used was a nonionic surfactant (Triton X-100).

[0184] [Peel test conditions] The peeling test was performed for 10 minutes under each condition, and evaluation was performed. If peeling occurred within 5 minutes of treatment, it indicates fairly high performance. A test piece of the printed matter cut to a size of 20 mm x 20 mm was immersed in the solution and stirred with a stirrer. After checking the peeling state after stirring, the printed matter was rubbed with a finger to see if rubbing would cause the coating to peel off. The peelability of the ink coating film under the above conditions was evaluated according to the following evaluation criteria.

[0185] [Evaluation Criteria] 5: Ink film peels off within 5 minutes of stirring. Complete peeling occurs when rubbed. 4: After 10 minutes of stirring, the ink film was confirmed to have come off. It was completely removed when rubbed. 3: No ink film detachment was observed after 10 minutes of stirring. Complete detachment when rubbed. 2: No ink film detachment was observed after 10 minutes of stirring. Partial detachment occurred when rubbed. 1: No ink film detachment confirmed after 10 minutes of stirring. No ink film detachment confirmed even after rubbing.

[0186] The results of the peelability test are shown in Table 4-1 below. From the perspective of practical application, a rating of 3 or higher is required.

[0187] <Evaluation item 2: Color inhibition test> Using the produced prints, a discoloration inhibition test was carried out under the following conditions.

[0188] <<Alkaline solution>> Sodium hydroxide 1% by mass, surfactant 0.3%, 70℃ Here, the surfactant used was a nonionic surfactant (Triton X-100).

[0189] <<Coloring inhibition test conditions>> The color inhibition test was performed by treating with the alkaline solution for 10 minutes. The printed matter was cut into 20mm x 20mm test pieces, and 50 pieces were immersed in 500mL of alkaline solution and stirred with a stirrer. The transparency of the alkaline solution after stirring was measured using a transparency meter according to the method of JIS (Japanese Industrial Standards) K0102.

[0190] Specifically, a transparency meter was filled with an alkaline solution in a glass cylinder with a bottom opening and a double cross on the bottom, and the bottom was viewed from the top until the double cross on the bottom was clearly visible. The sample was then quickly drained from the bottom opening, and the scale on the water surface was read. This was repeated twice, and the average value was calculated and expressed as transparency in degrees (10 mm = 1 degree). Evaluation was based on the following criteria.

[0191] As the blank samples in Examples 1 to 3, 50 test pieces cut to a size of 20 mm x 20 mm from the printed matter obtained using the ink composition of Comparative Example 1 were used after immersing in 500 mL of an alkaline solution and stirring with a stirrer. As the blank samples in Examples 4 to 6, 50 test pieces cut to a size of 20 mm x 20 mm from the printed matter obtained using the ink composition of Comparative Example 4 were used after immersing in 500 mL of an alkaline solution and stirring with a stirrer. As the blank samples in Examples 7 to 9, 50 test pieces cut to a size of 20 mm x 20 mm from the printed matter obtained using the ink composition of Comparative Example 7 were used after immersing in 500 mL of an alkaline solution and stirring with a stirrer. As the blank samples in Examples 10 to 12, 50 test pieces cut to a size of 20 mm x 20 mm from the printed matter obtained using the ink composition of Comparative Example 10 were used after immersing in 500 mL of an alkaline solution and stirring with a stirrer. As blank samples for Examples 13 to 15, 50 test pieces cut to a size of 20 mm x 20 mm from the printed matter obtained using the ink composition of Comparative Example 13 were used, which were immersed in 500 mL of an alkaline solution and stirred with a stirrer.

[0192] [Evaluation Criteria] 5: Transparency 10 times or more than that of the blank sample. 4: Transparency 5 times or more than that of the blank sample. 3: Transparency three times or more than that of the blank sample. 2: Transparency 1.5 times or more that of the blank sample. 1: Transparency equal to that of the blank sample.

[0193] The results of the color inhibition test are shown in Table 4-1 below. From the perspective of practical application, a rating of 3 or higher is required.

[0194] (Examples 2 to 15, Comparative Examples 1 to 15) A printed matter was obtained in the same manner as in Example 1, except that the layer structure in Example 1 was changed to those shown in Tables 4-1 to 4-5 below. The obtained prints were evaluated in the same manner as in Example 1. The results are shown in Tables 4-1 to 4-5.

[0195] [Table 1-1]

[0196] [Table 1-2]

[0197] [Table 1-3]

[0198] [Table 1-4]

[0199] [Table 2-1]

[0200] [Table 2-2]

[0201] [Table 3]

[0202] [Table 4-1]

[0203] [Table 4-2]

[0204] [Table 4-3]

[0205] [Table 4-4]

[0206] [Table 4-5]

[0207] From the above examples, it was found that the printed matter according to the present invention can easily remove the ink layer from the substrate by treatment with an alkaline solution, and can effectively suppress discoloration of the alkaline solution when the ink layer is removed. The printed matter according to the present invention has an effect of suppressing the coloring of the alkaline treatment solution, and therefore can prevent water pollution and environmental load caused by colored wastewater. In addition, since raw materials and manufacturing equipment for decolorization of colored wastewater are not required, it is possible to reduce manufacturing costs when recycling substrates. Furthermore, since no step for decolorization is required and the recycling efficiency of substrates is excellent, it is very useful industrially.

Claims

1. A substrate; a primer layer that can be removed from the substrate by treatment with an alkaline solution; an ink layer containing a colorant and at least one resin selected from the group consisting of an acrylic resin, a urethane resin, a polyamide resin, a rosin resin, and a polyester resin; A printed matter in which a varnish layer and a varnish layer are laminated in this order, The varnish layer is (i) containing at least a urethane resin and a cellulose derivative, or (ii) A printed matter containing at least a urethane resin, a cellulose derivative, and a polyisocyanate.

2. The printed matter according to claim 1 , wherein the varnish layer is a crosslinked coating.

3. The printed matter according to claim 1 or 2, wherein the primer layer contains a urethane resin or polyvinyl alcohol.

4. A method for producing a recycled substrate, comprising treating the printed matter according to claim 1 with an alkaline solution to remove the primer layer from the substrate, thereby obtaining a recycled substrate.

5. The method for producing a recycled substrate according to claim 4 , wherein the alkaline solution has a pH of 9 or more and contains a nonionic surfactant.