Urethane resin composition, laminate using the urethane resin composition, packaging material or electronic equipment containing the laminate, and method for producing recycled substrate

Abstract

The present invention provides a urethane resin composition, a film of which can be removed from a plastic base material by a warm alkaline water treatment, although the film is not separated even by means of a strong alkaline substance under temperature conditions where the film is normally used.　Provided is a urethane resin composition which contains a urethane resin (A) and an organic solvent (B), wherein: the urethane resin (A) comprises a reaction product of a polyol (a) and a polyisocyanate (b); the polyol (a) includes a polyester polyol (a1), and has an HSP distance (R) of 9 or less; the ester bond group concentration of the urethane resin (A) is 3-9 mmol / g inclusive; the acid value of the urethane resin (A) is 0-15 mgKOH / g inclusive; the urea group concentration of the urethane resin (A) is 0.2-2 mmol / g inclusive; and the content of diethylene glycol or ethylene glycol in the total glycol component of the polyester in the urethane resin (A) is 50 wt% or more.

Description

[Technical Field]

[0001] The present invention relates to a urethane resin composition for forming a primer layer that can be detached from a substrate, a laminate using the urethane resin composition, a packaging material or electronic equipment containing the laminate, and a method for producing a recycled substrate. [Background technology]

[0002] In recent years, the marine plastic problem has become apparent, stemming from plastics discarded or dumped in the ocean breaking down in seawater and breaking down into tiny particles (microplastics). These microplastics enter the bodies of marine organisms, where they accumulate, raising concerns that they may impact the health of seabirds and humans through the food chain. Recycling is one way to address this problem. Improving the recycling rate of resources such as flexible packaging and plastic bottles will prevent plastic from entering the ocean. However, current recycling methods pose a challenge: the printed layer on the plastic substrate does not detach during the recycling process. This residual printed layer contaminates the recycled plastic, causing a deterioration in color and physical properties, thereby reducing the value of the recycled plastic. Solving this issue by enabling the printed layer to detach from the plastic substrate during the recycling process would increase the value of recycled plastic, leading to the entry of new recyclers and the establishment of separate collection systems by local governments. This would improve recycling rates and potentially alleviate the marine plastic problem. Therefore, there is a need for the development of materials that can form a detachable coating from the plastic substrate during the recycling process.

[0003] Prior art has disclosed packaging materials that can be detached by treating printing inks that use urethane resins with an acid value as the binder resin with a basic aqueous solution (Patent Documents 1 and 2). However, when a urethane resin with an acid value is used as the main binder resin, it is expected that adhesion to the substrate will be insufficient, and imparting an acid value to the urethane resin increases the viscosity of the resin. This has led to problems such as the need to use solvents that have significant health and environmental impacts to adjust viscosity, or the avoidance of the coexistence of an amine value and an acid value to reduce viscosity, resulting in reduced suitability for lamination applications. As such, many challenges remain when using urethane resin compositions in materials with detachable coatings. A method has also been proposed in which an aqueous urethane resin composition is used as a removable primer layer, but the deinking properties of this method are said to be such that it can be removed even with strong alkali at low temperatures. This means that there is a problem that the coating film peels off under normal usage conditions, such as when strong alkaline substances such as detergents adhere to printed materials in daily life (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-90627 [Patent Document 2] Japanese Patent Publication No. 2020-196855 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-114930 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a urethane resin composition that will not peel off even with a strongly alkaline substance under temperature conditions in normal use, but will form a coating that can be detached from a plastic substrate by treatment with warm alkaline water. [Means for solving the problem]

[0006] As a result of extensive research to solve the above problems, the inventors have focused on the HSP distance calculated from the Hansen solubility parameters of polyol (a) and organic solvent (B) in a urethane resin composition containing urethane resin (A) formed from a reaction product of polyol (a) and polyisocyanate (b) as a material for forming a removable primer layer, and have completed the present invention.

[0007] That is, the present invention includes the following aspects. [1] A urethane resin composition containing a urethane resin (A) and an organic solvent (B), the urethane resin (A) is a reaction product of a polyol (a) and a polyisocyanate (b), the polyol (a) includes a polyester polyol (a1), R (HSP distance) represented by the following formula (1) is 9 or less, the urethane resin (A) has an ester bond group concentration of 3 mmol / g or more and 9 mmol / g or less, the acid value of the urethane resin (A) is 0 mgKOH / g or more and 15 mgKOH / g or less; the urethane resin (A) has a urea group concentration of 0.2 mmol / g or more and 2 mmol / g or less, A urethane resin composition, wherein the content of diethylene glycol residues or ethylene glycol residues in the total glycol components of the polyester in the urethane resin (A) is 50% by weight or more. R = {4(δD1-δD2) 2 +(δP1-δP2) 2 +(δH1-δH2) 2} 0.5 ···(1) (In the above formula (1), δD1, δP1, and δH1 respectively represent the dispersion force term, polarity term, and hydrogen bond term in the Hansen solubility parameter of the polyester polyol (a1), and δD2, δP2, and δH2 respectively represent the dispersion force term, polarity term, and hydrogen bond term in the Hansen solubility parameter of the organic solvent (B).) [2] The urethane resin composition according to [1], wherein the content of dicarboxylic acid residues having 6 or less carbon atoms in the acid component of the polyester in the urethane resin (A) is 50% by weight or more. [3] The urethane resin composition according to [1], wherein the content of adipic acid residues in the acid component of the polyester in the urethane resin (A) is 50% by weight or more. [4] The urethane resin composition according to [1] or [2], wherein the content of isophorone diisocyanate residues in the polyisocyanate component (b) in the urethane resin (A) is 50% by weight or more. [5] The polyol (a) further contains a polyether polyol (a2), The urethane resin composition according to any one of [1] to [4], wherein the urethane resin (A) is a reaction product of a polyester polyol (a1), a polyether polyol (a2), and a polyisocyanate (b). [6] The urethane resin composition according to [5], wherein the polyether polyol (a2) contains a polyethylene glycol component and / or a polypropylene glycol component. [7] The urethane resin composition according to any one of [1] to [6], wherein the total concentration of urethane groups and urea groups in the urethane resin (A) is 1.0 mmol / g or more and 3.0 mmol / g or less. [8] The urethane resin composition according to any one of [1] to [7], wherein the organic solvent (B) has an ethyl acetate content of 20% by weight or more and 100% by weight or less, and an isopropyl alcohol content of 0% by weight or more and 80% by weight or less. [9] The urethane resin composition according to any one of [1] to [8], wherein the organic solvent (B) has an ethyl acetate content of 60% by weight or more and 100% by weight or less, and an isopropyl alcohol content of 0% by weight or more and 40% by weight or less.

[10] The urethane resin composition according to any one of [1] to [9], wherein the urethane resin composition further contains a crosslinking agent.

[11] The urethane resin composition according to

[10] , wherein the crosslinking agent is a polyisocyanate crosslinking agent.

[12] A laminate comprising a substrate (C), a primer layer formed by coating the urethane resin composition according to any one of [1] to [9] above, and a printed layer formed by printing a printing ink composition on the primer layer.

[13] A method for applying the urethane resin composition onto the substrate (C), comprising: The laminate according to any one of [1] to

[12] , which is an in-line coating method in which the urethane resin composition is applied to the substrate (C) during a stretching step, and then a stretching step is further carried out, or an off-line coating method in which the urethane resin composition is applied to the substrate (C) after the stretching step, and then dried to form the primer layer.

[14] An electronic device or packaging material comprising the laminate according to

[12] or

[13] .

[15] The laminate further comprises a substrate (D) different from the substrate (C), The laminate according to any one of

[12] to

[14] , wherein the substrate (D) is placed on the surface of the printed layer opposite to the surface on which the substrate (C) is placed, and the substrate (C), the primer layer, the printed layer, and the substrate (D) are laminated together.

[16] A method for producing a recycled substrate, comprising treating the laminate according to

[12] with an alkaline solution to remove the primer layer and the printed layer from the substrate (C), thereby obtaining a recycled substrate.

[13] A method for producing a recycled substrate, comprising treating the laminate according to

[11] with an alkaline solution to remove the primer layer, the printed layer, and / or the substrate (D) from the substrate (C), thereby obtaining a recycled substrate. [Effects of the Invention]

[0008] The present invention can provide a urethane resin composition that cannot be peeled off even by a strongly alkaline substance under temperature conditions in normal use, but that can form a coating that can be detached from a plastic substrate by treatment with warm alkaline water. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] (Urethane resin composition) The urethane resin composition of the present invention contains at least a urethane resin (A) formed from a reaction product of a polyol (a) and a polyisocyanate (b), and an organic solvent (B).

[0011] <Urethane resin (A)> The urethane resin (A) is a general term for a polymeric compound having a urethane bond (-NHCOO-). In the present invention, the urethane resin (A) is a reaction product obtained by reacting (crosslinking / curing reaction) a polyol (a) with a polyisocyanate (b), and the polyol (a) essentially contains a polyester polyol (a1). The polyol (a) may contain, in addition to the polyester polyol (a1), a polyether polyol (a2) and / or other polyol (a3), as necessary. The urethane resin (A) may contain, in addition to the polyester polyol (a1) and the polyisocyanate (b), a polyether polyol (a2) and / or another polyol (a3) ​​as reaction raw materials, or may be a reaction product of the polyester polyol (a1), the polyisocyanate (b), and the polyether polyol (a2) and / or another polyol (a3). In this specification, the term "reaction raw material" refers to a compound used to obtain a target compound through a chemical reaction such as synthesis or decomposition, and which partially constitutes the chemical structure of the target compound. Substances that act as chemical reaction aids, such as solvents and catalysts, are excluded. In this specification, the term particularly refers to a precursor for obtaining the target urethane resin (A) or its precursor compound (e.g., polyester polyol (a1)) through a chemical reaction. Therefore, examples of reaction raw materials include polyester polyol (a1), polyisocyanate (b), dicarboxylic acid (a1-1), polyhydric hydroxyl compound (a1-2), polyether polyol (a2), and other polyols (a3). Furthermore, the term "residue" refers to a partial structure in a product compound formed by a reaction or polymerization other than the structure of the chemical bond involved in the reaction or polymerization. For example, the urethane resin (A) of the present invention has a polyester polyol (a1) residue (also referred to as the polyester polyol (a1) component) and a polyisocyanate (b) residue (also referred to as the polyisocyanate (b) component), and optionally further has a polyether polyol (a2) residue and another polyol (a3) ​​residue. The content of diethylene glycol residues or ethylene glycol residues in the total glycol components of the polyester in the urethane resin (A) is 50% by weight or more. When the diethylene glycol residue or ethylene glycol residue is contained within the above range among all glycol residues in the polyester polyol (a1) residue (also referred to as polyester or polyester component) constituting the urethane resin (A), the coating is less susceptible to peeling even with a strongly alkaline substance, and is more likely to be detached from the plastic substrate by treatment with warm alkaline water. In the present invention, the content of dicarboxylic acid residues having 6 or less carbon atoms in the acid component of the polyester in the urethane resin (A) is preferably 50% by weight or more, and the content of adipic acid residues is more preferably 50% by weight or more. When the residues of the acid components (e.g., carboxylic acid compounds) constituting the polyester in the urethane resin (A) contain carboxylic acid compound residues within the above range, the coating is less susceptible to peeling even with strongly alkaline substances, and is more likely to be detached from the plastic substrate by treatment with warm alkaline water. In the present invention, the content of isophorone diisocyanate residues in the polyisocyanate (b) component in the urethane resin (A) is preferably 50% by weight or more. In the present invention, the total concentration of urethane groups and urea groups in the urethane resin (A) is preferably 1.0 mmol / g or more and 3.0 mmol / g or less.

[0012] <<Polyester polyol (a1)>> The polyester polyol (a1) can be produced, for example, by esterifying a dicarboxylic acid (a1-1) with a polyhydroxyl compound (a1-2).

[0013] Examples of the dicarboxylic acid (a1-1) that can be used when producing the polyester polyol (a1) include 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.

[0014] In addition to the dicarboxylic acid (a1-1), an aliphatic carboxylic acid or an alicyclic carboxylic acid can be used in combination. Examples include aliphatic dicarboxylic acids such as succinic acid, succinic anhydride, adipic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, maleic anhydride, and fumaric acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, and their anhydrides or ester-forming derivatives. These may be used alone or in combination of two or more.

[0015] Examples of the polyhydric hydroxyl group compound (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.

[0016] Specifically, the dicarboxylic acid (a1-1) and the polyhydroxyl compound (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 atmospheric or reduced pressure. The reaction is preferably carried out at a temperature in the range of 100°C to 300°C.

[0017] Examples of catalysts 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.

[0018] The polyester polyol (a1) component is preferably contained in an amount ranging from 50% by mass to 80% by mass relative to the polyurethane resin. If the polyester polyol (a1) component is less than 50% by mass relative to 100% by mass of the polyurethane resin, the solvent solubility of the polyurethane resin decreases. Furthermore, it becomes difficult to remove the polyurethane resin from the plastic substrate by treatment with warm alkaline water. Furthermore, if the amount exceeds 80% by mass, the polyurethane resin film tends to become brittle, resulting in a decrease in the blocking resistance of the ink film.

[0019] When producing the urethane resin (A), the polyester polyol (a1) and the polyisocyanate (b) can be used in combination with a polyether polyol (a2), another polyol (a3), or the like.

[0020] <<Polyether polyol (a2)>> As the polyether polyol (a2), various known polyether polyols commonly used in the production of polyurethane resins can be used, and one or more of them may be used in combination. Examples include polyether polyols of polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, etc. Specifically, polyethylene glycol is preferred, and known general-purpose polyether polyols such as polypropylene glycol and polytetramethylene glycol may also be used, or a copolymer of polyethylene glycol and polypropylene glycol may also be used. The inclusion of polyether polyol (a2) significantly improves adhesion, particularly to films, resulting in excellent blocking resistance and laminate strength.

[0021] The polyether polyol (a2) preferably has a number average molecular weight of 100 or more and 3500 or less. If the number average molecular weight of the polyether polyol is less than 100, the polyurethane resin (A) film tends to be hard, resulting in reduced adhesion to plastic films. If the number average molecular weight is greater than 3500, the polyurethane resin film tends to be brittle, resulting in reduced blocking resistance of the ink film. From the same viewpoint, the number average molecular weight of the polyether polyol (a2) is more preferably 600 or more, even more preferably 1000 or more, and even more preferably 2000 or more.

[0022] The polyether polyol (a2) component is preferably contained in an amount ranging from 1% by mass to 40% by mass relative to the polyurethane resin. If the polyether polyol (a2) component is less than 1% by mass relative to 100% by mass of the polyurethane resin, the solubility of the polyurethane resin in ketone, ester, and alcohol-based solvents decreases. Furthermore, the resolubility of the ink film in these solvents decreases, tending to reduce the tone reproducibility of printed matter. Furthermore, if the polyether polyol (a2) component exceeds 40% by mass, the ink film becomes excessively soft, and blocking resistance tends to be poor.

[0023] <<Other polyols (a3)>> As the other polyol (a3), polyols similar to those used for the polyhydric hydroxyl compound (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.

[0024] The other polyol (a3) ​​component is preferably contained in an amount of 0 to 20% by mass relative to the polyurethane resin. If the other polyol (a3) ​​component exceeds 20% by mass relative to 100% by mass of the polyurethane resin, the polyurethane resin coating tends to harden, and the adhesion to plastic films decreases.

[0025] <<Polyisocyanate (b)>> Examples of the polyisocyanate (b) that reacts with the polyol (a1) to form the urethane resin (A) include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate, and aliphatic or alicyclic structure-containing diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more. Among these, the use of one or more selected from the group consisting of isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate is more preferred from the viewpoint of improving the substrate adhesion and deinking ability of the resulting primer layer.

[0026] The urethane resin (A) can be produced by reacting the polyester polyol (a1), the polyisocyanate (b), and optionally the polyol (a3), and optionally a chain extender, in the presence of an organic solvent (B). When the organic solvent (B) is used, it is preferable to remove the organic solvent (B) by a method such as distillation when dispersing the urethane resin (A) in the organic solvent (B).

[0027] Examples of the organic solvent (B) 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, N-methylpyrrolidone, etc., which can be used alone or in combination of two or more.

[0028] 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. The chain extender that can be used when producing the urethane resin (A) includes polyamines and other active hydrogen atom-containing compounds.

[0029] 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; diethylaminoethylamine, N-hydroxypropylaminoethylamine, N-hydroxypropylaminopropylamine, N-ethylaminoethylamine, and N-methylaminopropylamine; Benzene triamine, dipropylene triamine, triethylenetetramine; hydrazine, N,N'-dimethylhydrazine, 1,6-hexamethylenebishydrazine; succinic acid dihydrazide, adipic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide; β-semicarbazidopropionic acid hydrazide, 3-semicarbazidopropyl-carbazic acid ester, semicarbazido-3-semicarbazidomethyl-3,5,5-trimethylcyclohexane can be used, and it is preferable to use ethylenediamine.

[0030] 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.

[0031] The chain extender can be used during or after the reaction of the polyester polyol (a1) with the polyisocyanate (b), or can be used when dispersing the urethane resin (A) in the organic solvent (B).

[0032] <<HSP distance>> In the present invention, R (HSP distance) is calculated by the following formula (1) from the dispersion force term, polar term, and hydrogen bond term in the Hansen solubility parameters of the polyester polyol (a1) and the organic solvent (B). R = {4(δD1 - δD2) 2 +(δP1 - δP2) 2 +(δH1 - δH2) 2} 0.5 ···(1) Here, in the above formula (1), δD1, δP1, and δH1 respectively represent the dispersion force term, polar term, and hydrogen bond term in the Hansen solubility parameter of the polyester polyol (a1), and δD2, δP2, and δH2 respectively represent the dispersion force term, polar term, and hydrogen bond term in the Hansen solubility parameter of the organic solvent (B).

[0033] R (HSP distance) is an index of the solubility of the organic solvent (B) with respect to the polyester polyol (a1). It can be expected that the lower this numerical value is, the better the solubility. In the present invention, R is 9 or less. Preferably, R (HSP distance) is 8 or less, more preferably 7 or less. Also, preferably, R (HSP distance) is 3 or more, more preferably 5 or more. Among these, preferably, R (HSP distance) is 3 or more and 8 or less, more preferably 5 or more and 7 or less.

[0034] <<Properties of urethane resin (A)>> The ester bond group concentration of the urethane resin (A) is 3 mmol / g or more and 9 mmol / g or less. Such an ester bond group concentration is determined by calculating the number of moles of ester bond groups contained in 1 g of the urethane resin (A). From the viewpoints of improving the substrate adhesion and deinking property of the obtained primer layer, etc., preferably, the ester bond group concentration is 4 mmol / g or more, more preferably 5 mmol / g or more. From the viewpoints of good blocking resistance, etc., of the primer layer, preferably, the ester bond group concentration is 8 mmol / g or less, more preferably 7 mmol / g or less.

[0035] The acid value of the urethane resin (A) is 0 mgKOH / g or more and 15 mgKOH / g or less. 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, and is a value measured in accordance with JIS K0070. If the acid value is 0 mgKOH / g or more, the aqueous dispersion stability can be improved, and it is preferably 7 mgKOH / g or more, and more preferably 8 mgKOH / g or more. If the acid value is 15 mgKOH / g or less, the adhesion to the polyester substrate can be ensured well, and it is preferably 13 mgKOH / g or less, and more preferably 10 mgKOH / g or less. Furthermore, from the viewpoint of resin viscosity and storage stability, it is preferable that the acid value is 0 mgKOH / g.

[0036] The urea group concentration of the urethane resin (A) is 0.2 mmol / g or more and 2 mmol / g or less. The urea group concentration is the value obtained by dividing the weight of diamine contained in 1 g of urethane resin by the NCO equivalent weight of the constituting diamine. If the urea group concentration is 0.2 mmol / g or more, the final urethane resin composition The durability of the product can be improved, and a urea group concentration of 0.3 mmol / g or more is preferable, and 0.6 mmol / g or more is more preferable. If the urea group concentration is 2 mmol / g or less, the solubility in organic solvents can be ensured, and a urea group concentration of 1.7 mmol / g or less is preferable, and 1.5 mmol / g or less is more preferable. Among these, the urea group concentration is preferably 0.3 mmol / g or more and 1.7 mmol / g or less, and more preferably 0.6 mmol / g or more and 1.5 mmol / g or less.

[0037] The content of diethylene glycol residues or ethylene glycol residues in the total polyol (a) component of the polyester in the urethane resin (A) is 50% by weight or more. The content of diethylene glycol residues or ethylene glycol residues can be calculated from the composition of the raw materials used in preparing polyester polyol (a1), which is the raw material for urethane resin (A), and is the weight of diethylene glycol or ethylene glycol in polyester polyol (a1) divided by the weight of all glycols, expressed as a percentage. If the content of diethylene glycol residues or ethylene glycol residues is 50% by weight or more, the deinking properties of the resulting primer layer can be improved, and 70% by weight or more is preferable, and 80% by weight or more is more preferable. The upper limit of the content of diethylene glycol residues or ethylene glycol residues may be 100% by weight, 95% by weight or less, or 90% by weight or less. Among these, the content of diethylene glycol or ethylene glycol is more preferably 70% by weight or more and 95% by weight or less, and particularly preferably 80% by weight or more and 90% by weight or less.

[0038] In the acid component of the polyester in the urethane resin (A), the content of dicarboxylic acid residues having 6 or less carbon atoms is preferably 50% by weight or more, and the content of adipic acid residues is more preferably 50% by weight or more. Of these, the carbon number of the dicarboxylic acid is preferably 3 or more, and of these, 3 to 5 is more preferred. The content of adipic acid residues can be calculated from the composition of the raw materials used to prepare polyester polyol (a1), which is the raw material for urethane resin (A), and is the weight of adipic acid in polyester polyol (a1) divided by the weight of all dicarboxylic acids, expressed as a percentage. If the content of adipic acid residues is 50% by weight or more, the deinking properties of the resulting primer layer can be improved, with 70% by weight or more being more preferable, and 80% by weight or more being even more preferable. The content of adipic acid residues may be 100% by weight, 95% by weight or less, or 90% by weight or less. Among these, the content of adipic acid is more preferably 70% by weight or more but 95% by weight or less, and particularly preferably 80% by weight or more but 90% by weight or less.

[0039] It is preferable that the content of isophorone diisocyanate residues in the polyisocyanate component (b) in the urethane resin (A) is 50% by weight or more. The content of isophorone diisocyanate residues can be calculated from the composition of raw materials used in preparing polyisocyanate (b), which is the raw material for urethane resin (A), and is the weight of isophorone diisocyanate in polyisocyanate (b) divided by the total weight of polyisocyanate, expressed as a percentage. If the content of isophorone diisocyanate is 50% by weight or more, organic solvent solubility can be improved, and 70% by weight or more is more preferable, and 80% by weight or more is even more preferable. The content of isophorone diisocyanate may be 100% by weight, 95% by weight or less, or 90% by weight or less. Among these, the content of isophorone diisocyanate is more preferably 70% by weight or more and 95% by weight or less, and particularly preferably 80% by weight or more and 90% by weight or less.

[0040] The total concentration of urethane groups and urea groups in the urethane resin (A) is preferably 1.0 mmol / g or more and 3.0 mmol / g or less. The total concentration of urethane groups and urea groups is the value obtained by dividing the weight of diisocyanate contained in 1 g of urethane resin (A) by the NCO equivalent weight of the constituting diisocyanate. If the urethane group and urea group concentrations are 1.0 mmol / g or more, the durability of the final urethane resin composition can be improved, with 1.2 mmol / g or more being more preferred, and 1.5 mmol / g or more being even more preferred. If the urethane group and urea group concentrations are 3.0 mmol / g or less, the solubility in organic solvents can be ensured, with 2.5 mmol / g or less being more preferred, and 2.0 mmol / g or less being even more preferred. Among these, the content of isophorone diisocyanate is preferably 1.0 mmol / g or more and 2.5 mmol / g or less, and particularly preferably 1.2 mmol / g or more and 2.0 mmol / g or less.

[0041] <Organic solvent (B)> Examples of the organic solvent (B) that can be used as a solvent for the urethane resin (A) include acetate esters such as ethyl acetate and butyl acetate, 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 glycols, and N-methyl-2-pyrrolidone. Therefore, since film-forming materials widely used on plastic substrates require consideration of worker health and the environment, it is preferable to use toluene-free and methyl ethyl ketone (MEK)-free organic solvents, and ethyl acetate and isopropyl alcohol are preferred.

[0042] Furthermore, from the viewpoint of improving compatibility with the polyester polyol (a1) and reducing R (HSP distance), the content of ethyl acetate in the organic solvent (B) that serves as a solvent for the urethane resin (A) is preferably 20% by weight to 100% by weight, and the content of isopropyl alcohol is preferably 0% by weight to 80% by weight. From the same viewpoint, the content of ethyl acetate is more preferably 60% by weight to 100% by weight, and the content of isopropyl alcohol is more preferably 0% by weight to 40% by weight. Similarly, to reduce R (HSP distance) with the polyester polyol (a1), the content of ethyl acetate is more preferably 70% by weight or more, and even more preferably 80% by weight or more.

[0043] When dispersing the urethane resin (A) in the organic solvent (B), a machine such as a homogenizer can be used as needed.

[0044] The urethane resin composition of the present invention preferably contains urethane resin (A) in an amount of 5 to 50% by mass, more preferably 10 to 40% by mass, based on the total amount of the urethane resin composition, and the organic solvent (B) is preferably contained in an amount of 50 to 95% by mass, more preferably 60 to 90% by mass, based on the total amount of the urethane resin composition.

[0045] <Crosslinking agent> In addition, in order to form films and the like having excellent durability, it is preferable to use the urethane resin composition of the present invention 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. Of these, it is preferable to use a polyisocyanate crosslinking agent. 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 urethane resin (A), from the viewpoints of improving adhesion to substrates, improving deinking properties, etc. The crosslinking agent is preferably mixed and used immediately before coating the urethane resin composition of the present invention.

[0046] <Other additives> The urethane resin composition of the present invention may contain various additives, such as a film-forming aid, a curing accelerator, a plasticizer, an antistatic agent, a wax, a light stabilizer, a flow modifier, a dye, a leveling agent, a rheology control agent, an ultraviolet absorber, an antioxidant, a photocatalytic compound, an inorganic pigment, an organic pigment, or an extender pigment, as necessary.

[0047] Among the additives, emulsifiers and leveling agents 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 urethane resin composition.

[0048] (Primer layer) The urethane resin composition of the present invention can be used to form a primer layer by coating the urethane resin composition on a substrate. A printing layer made of a printing ink composition can be formed on the primer layer. The primer layer can be easily removed by treatment with warm alkaline water. Since the primer layer can be easily peeled off from the substrate, the printed layer formed on the primer layer can also be easily removed from the substrate.

[0049] The urethane resin composition of 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 gravure printing and flexographic printing described above, known printing methods that can be used 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. When printing, the ink is diluted with a diluting solvent, for example, a mixture of an acetate ester-based organic solvent such as ethyl acetate or butyl acetate with 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 or flexographic printing, and then supplied to each printing unit either alone or in a mixture.

[0050] Furthermore, the method for applying the urethane resin composition onto the substrate can be an inline coating method in which the urethane resin composition is applied during a substrate stretching step (e.g., a biaxial stretching step) and then a further stretching step is performed, or an offline coating method in which the urethane resin composition is applied and dried after the substrate stretching step (e.g., a biaxial stretching step) to form a primer layer.

[0051] (Laminate) The present invention also provides a laminate having a primer layer formed using the urethane resin composition of the present invention. The laminate of the present invention has a primer layer formed on a substrate by coating the urethane resin composition of the present invention, and further has a printed layer formed on the primer layer by printing a printing ink composition.

[0052] The embodiment of the laminate having a primer layer formed using the urethane resin composition of the present invention is not limited, but preferred examples include the following embodiment (1-A). (1-A) Base material (C) - primer layer - printing layer

[0053] Furthermore, the laminate of the present invention covers not only laminates having a surface-printed structure in which a printed layer is formed on the surface of the laminate, as in the above-mentioned (1-A) embodiment, but also laminates having a laminated structure in which a coating film (various layers or films) is further formed on top of the printed layer. In other words, the laminate of the present invention also covers laminates having a laminate-type structure in which another substrate (substrate (D)) is placed on the side opposite to the side on which the substrate (substrate (C)) is placed relative to the printed layer, and the substrate (C), primer layer, printed layer, and substrate (D) are laminated together. Examples of the laminate having a laminate type structure include the laminates of the following embodiments. In the examples of laminate-type structures described below, base film 1 corresponds to the base (C) of the present invention. However, in embodiments where base film 1 is not present, films such as a sealant film, a metal-vapor-deposited unstretched film, or a transparent vapor-deposited stretched film may correspond to the base (C) of the present invention. Furthermore, base film 2 corresponds to the base (D) of the present invention. In embodiments where base film 2 is not present, films such as a sealant film, a metal-vapor-deposited unstretched film, or a transparent vapor-deposited stretched film may correspond to the base (D) of the present invention. In many cases, the base (D) refers to a film formed on the surface opposite to the base (C) in the laminate, but in some cases the base (D) is not limited to a film disposed on the surface, and the base (D) may be present between layers, or multiple bases (D) may be provided in the laminate.

[0054] In this embodiment, a primer layer is applied onto a film corresponding to the substrate (C). (1-1) Base film 1 / primer layer / printing layer / adhesive layer 1 / sealant film (1-2) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal-deposited unstretched film (1-3) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal-deposited stretched film (1-4) Transparent vapor-deposited stretched film / primer layer / printing layer / adhesive layer 1 / sealant film (1-5) Base film 1 / primer layer / printing layer / adhesive layer 1 / base film 2 / adhesive layer 2 / sealant film (1-6) Base film 1 / primer layer / printing layer / adhesive layer 1 / metallized stretched film / adhesive layer 2 / sealant film (1-7) Base film 1 / primer layer / printing layer / adhesive layer 1 / transparent vapor-deposited stretched film / adhesive layer 2 / sealant film (1-8) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal layer / adhesive layer 2 / sealant film (1-9) Base film 1 / primer layer / printing layer / adhesive layer 1 / base film 2 / adhesive layer 2 / metal layer / adhesive layer 3 / sealant film (1-10) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal layer / adhesive layer 2 / base film 2 / adhesive layer 3 / sealant film

[0055] In the above embodiments (1-5) to (1-7) and (1-9) to (1-10), a primer layer may be applied to both sides of the film positioned as the intermediate layer. (2-5) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / base film 2 / primer layer / adhesive layer 2 / sealant film (2-6) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / metal-deposited stretched film / primer layer / adhesive layer 2 / sealant film (2-7) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / transparent vapor-deposited stretched film / primer layer / adhesive layer 2 / sealant film (2-9) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / base film 2 / primer layer / adhesive layer 2 / metal layer / adhesive layer 3 / sealant film (2-10) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal layer / adhesive layer 2 / primer layer / base film 2 / primer layer / adhesive layer 3 / sealant film

[0056] In the above embodiments (1-1) to (1-10), (2-5) to (2-7), and (2-9) to (2-10), a primer layer may be applied to the film corresponding to the substrate (D) (the film located on the surface opposite to the substrate (C)). (3-1) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / sealant film (3-2) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / metal-deposited unstretched film (3-3) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / metal-deposited stretched film (3-4) Transparent vapor-deposited stretched film / primer layer / printing layer / adhesive layer 1 / primer layer / sealant film (3-5) Base film 1 / primer layer / printing layer / adhesive layer 1 / base film 2 / adhesive layer 2 / primer layer / sealant film (3-6) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal-deposited stretched film / adhesive layer 2 / primer layer / sealant film (3-7) Base film 1 / primer layer / printing layer / adhesive layer 1 / transparent vapor-deposited stretched film / adhesive layer 2 / primer layer / sealant film (3-8) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal layer / adhesive layer 2 / primer layer / sealant film (3-9) Base film 1 / primer layer / printing layer / adhesive layer 1 / base film 2 / adhesive layer 2 / metal layer / adhesive layer 3 / primer layer / sealant film (3-10) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal layer / adhesive layer 2 / base film 2 / adhesive layer 3 / primer layer / sealant film (3-2-5) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / base film 2 / primer layer / adhesive layer 2 / primer layer / sealant film (3-2-6) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / metal-deposited stretched film / primer layer / adhesive layer 2 / primer layer / sealant film (3-2-7) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / transparent vapor-deposited stretched film / primer layer / adhesive layer 2 / primer layer / sealant film (3-2-9) Base film 1 / primer layer / printing layer / adhesive layer 1 / primer layer / base film 2 / primer layer / adhesive layer 2 / metal layer / adhesive layer 3 / primer layer / sealant film (3-2-10) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal layer / adhesive layer 2 / primer layer / base film 2 / primer layer / adhesive layer 3 / primer layer / sealant film

[0057] Among the above embodiments, the primer layer on the surface of the vapor-deposited film (whether transparent or metallic, stretched or unstretched) facing the printed layer may be removed. The vapor-deposited layer may be dissolved in an alkaline solution, making it possible to remove the primer layer formed on one surface of the vapor-deposited film. In the embodiment (4-3-4) below, one surface of the vapor-deposited film is located on the surface of the laminate, so the primer layer facing the other inward surface is removed. (4-2-6) Base film 1 / primer layer / printing layer / adhesive layer 1 / metallized stretched film / primer layer / adhesive layer 2 / sealant film (4-2-7) Base film 1 / primer layer / printing layer / adhesive layer 1 / transparent vapor-deposited stretched film / primer layer / adhesive layer 2 / sealant film (4-3-4) Transparent vapor-deposited stretched film / printing layer / adhesive layer 1 / primer layer / sealant film (4-3-2-6) Base film 1 / primer layer / printing layer / adhesive layer 1 / metal-deposited stretched film / primer layer / adhesive layer 2 / primer layer / sealant film (4-3-2-7) Base film 1 / primer layer / printing layer / adhesive layer 1 / transparent vapor-deposited stretched film / primer layer / adhesive layer 2 / primer layer / sealant film

[0058] The laminated body having a laminate type structure may have a laminate type structure in which a coating film (various layers or films) is further formed on the printed layer by extrusion lamination. In other words, the laminate of the present invention also covers laminates having a laminate-type structure in which an extrusion laminate layer is placed on the side opposite to the side on which the substrate (substrate (C)) is placed relative to the printed layer, and the substrate (C), primer layer, printed layer, and extrusion laminate layer are laminated together. Examples of the laminate having an extrusion laminate type structure include the laminates of the following embodiments. In the examples of laminate-type structures shown below, the substrate film 1 corresponds to the substrate (C) of the present invention.

[0059] (5-1) Base film 1 / primer layer / printing layer / extrusion lamination anchor layer / extrusion lamination layer (5-2) Base film 1 / printing layer / primer layer / extrusion lamination anchor layer / extrusion lamination layer (5-3) Base film 1 / primer layer / printing layer / primer layer / extrusion lamination anchor layer / extrusion lamination layer

[0060] In the above embodiments (5-2) and (5-3), the extrusion laminate layer can be recovered and reused as a resin without a printed layer attached. In the embodiment (5-3), both the base film 1 and the extrusion laminate layer can be recovered and reused as a resin without a printed layer attached. In the above (5-1) to (5-3), an "anchor layer for extrusion lamination" is provided on the printing layer, but an "extrusion lamination layer" may be provided directly on the "printing layer" without providing an "anchor layer for extrusion lamination."

[0061] In addition to the above structures (5-1) to (5-3), other layers such as a sealant layer may be disposed on the surface of the extrusion laminate layer opposite to the surface on which the base film 1 is provided. The structures of the other layers are not limited to the following structures (5-1-1) to (5-1-6), and may be any other layers depending on the required properties. It can be designed appropriately according to the requirements. The following is an example of a configuration in which another layer is provided in the configuration of (5-1) above. Similar configurations are also possible for the above (5-2) and (5-3). (5-1-1) Base film 1 / primer layer / printing layer / extrusion laminate anchor layer / extrusion laminate layer / adhesive layer 1 / sealant film (5-1-2) Base film 1 / primer layer / printing layer / extrusion laminate anchor layer / extrusion laminate layer / adhesive layer 1 / metal layer / adhesive layer 2 / sealant film (5-1-3) Base film 1 / primer layer / printing layer / extrusion laminate anchor layer / extrusion laminate layer / primer layer / adhesive layer 1 / sealant film (5-1-4) Base film 1 / primer layer / printing layer / extrusion laminate anchor layer / extrusion laminate layer / primer layer / adhesive layer 1 / metal layer / adhesive layer 2 / sealant film (5-1-5) Base film 1 / primer layer / printing layer / extrusion laminate anchor layer / extrusion laminate layer / primer layer / adhesive layer 1 / primer layer / sealant film (5-1-6) Base film 1 / primer layer / printing layer / extrusion laminate anchor layer / extrusion laminate layer / primer layer / adhesive layer 1 / metal layer / adhesive layer 2 / primer layer / sealant film

[0062] When producing the laminates of each of the above embodiments, if a primer layer is formed on each of the substrate film 1, substrate film 2, metal-vapor-deposited stretched film, and transparent-vapor-deposited stretched film, as explained above in the section (Primer layer), the primer layer may be formed by an in-line coating method in which a urethane resin composition is applied during the film stretching process and then a stretching process is performed, or by an off-line coating method in which a urethane resin composition is applied after the film stretching process and then dried to form the primer layer.

[0063] Although the above-mentioned embodiments have been given as examples of the structure of the laminate, the structure is not limited to these. The printed layer is, for example, a printed layer formed with printing ink. Examples of the printed layer include a printed layer formed with printing ink containing a colored pigment or a white pigment as a colorant. The printing method for the printed layer is not particularly limited, and the printed layer can be formed by various printing methods such as gravure printing, flexographic printing, offset printing, inkjet printing, and screen printing. The printing ink can be an ink suitable for the various printing methods, and may be a solvent-based ink or a water-based ink. UV-curable or EB-curable ink may also be used.

[0064] Examples of the base film 1 include an OPP film (a polypropylene film, such as a biaxially oriented polypropylene film), a PET film (a polyethylene terephthalate film, such as a biaxially oriented polyethylene terephthalate film), and a nylon film. The base film 1 may be coated to improve gas barrier properties and ink receptivity when a printing layer is provided. Commercially available coated base films 1 include K-OPP film and K-PET film. Examples of the sealant film include a CPP film (unstretched polypropylene film) and an LLDPE film (linear low-density polyethylene resin film). As the metal-vapor-deposited unstretched film, a VM-CPP film obtained by vapor-depositing a metal such as aluminum onto a CPP film can be used. As the metal-deposited stretched film, a VM-OPP film obtained by depositing a metal such as aluminum on an OPP film can be used. Examples of the transparent vapor-deposited stretched film include films obtained by depositing silica or alumina on OPP film, PET film, nylon film, etc. For the purpose of protecting the inorganic vapor-deposited layer of silica or alumina, a film having a coating applied to the vapor-deposited layer may also be used. The metal layer may be an aluminum foil or the like. The base film 2 may be a nylon film or the like.

[0065] The adhesive layer can be formed using a known adhesive for film lamination. When laminating by extrusion lamination, a known anchor coating agent for extrusion lamination can be used as an adhesive aid. The use of a material having gas barrier properties for these adhesives or anchor coating agents can result in a laminate with particularly excellent barrier properties. As an adhesive with excellent gas barrier properties, 3 g / m 2 The oxygen barrier property of the cured coating film of the adhesive applied at (solid content) is 300cc / m 2 / day / atm or less, or water vapor barrier property of 120g / m 2 / day. Commercially available products include the "PASLIM" series, such as PASLIM VM001 and PASLIM J350X, manufactured by DIC Corporation, and "Maxieve" manufactured by Mitsubishi Gas Chemical Company, Inc. The extrusion laminate layer can be made of a known thermoplastic resin, such as a polyolefin resin such as a polyethylene resin or a polypropylene resin, but is not limited to these materials. Various known anchor coating agents can be used for the anchor layer for extrusion lamination. Examples include, but are not limited to, isocyanate-based and amine polymer-based materials. The "anchor layer for extrusion lamination" may also be formed using the urethane resin composition of the present invention. Forming the "anchor layer for extrusion lamination" using the urethane resin composition of the present invention improves adhesion to the extrusion laminate layer and also improves the deinking properties of the extrusion laminate layer during peeling treatment.

[0066] <Applications of laminates> The urethane resin composition of the present invention can be suitably used for packaging materials or electronic equipment as a surface treatment agent (primer coating agent) for substrates in molded products having an overprinted layer, including a printed layer, such as electronic equipment, building materials, textiles and leather, home appliances, vehicles such as cars and airplanes, furniture, office supplies, play equipment, sporting goods, or molded parts for these products. Therefore, laminates having a primer layer formed from the urethane resin composition of the present invention can be applied to various molded products such as electronic equipment, building materials, textiles and leather, home appliances, vehicles such as cars and airplanes, furniture, office supplies, play equipment, sporting goods, and molded parts for these products. Furthermore, a laminate having a primer layer formed from the urethane resin composition of the present invention can also be used as a packaging material (more specifically, a multi-layer packaging material). In addition, it can also be used as a multi-layer packaging material. When used as a multi-layer packaging material, the layer structure can be changed depending on the contents, the environment of use, and the form of use. When used as a packaging material, for example, the contents are filled through the opening, and the opening is then heat-sealed to produce a product using the packaging material formed from the laminate of the present invention. The uses of the packaging material are not particularly limited, but it can be used as a packaging material for food, medicine, sanitary products, cosmetics, electronic equipment, building materials, industrial materials, etc., and is particularly applicable to electronic equipment.

[0067] <Characteristics of laminate> The primer layer formed from the urethane resin composition of the present invention also has good adhesion to the substrate, and the laminate of the present invention has excellent adhesion between the substrate and the printed layer. Furthermore, the primer layer of the laminate of the present invention can be removed in a simple manner by using a warm alkaline solution, and the substrate and the printing layer can be easily peeled off. However, the primer layer of the laminate of the present invention will not be peeled off even when an alkaline solution is applied under temperature conditions that are normally used. Therefore, under temperature conditions that are normally used, even if an alkaline solution is unintentionally attached, the laminate can be used safely without worrying about peeling. In laminates having a primer layer formed from the urethane resin composition of the present invention, the primer layer can be easily removed by applying a warm alkaline solution, not only for laminates having a surface-printed type structure such as the above-mentioned (1-A) embodiment, but also for laminates having a laminate type structure such as the above-mentioned (1-1) to (4-3-2-7) embodiments, and the substrate and printing layer can be easily peeled off. Furthermore, when the urethane resin composition of the present invention contains a crosslinking agent as described above, a primer layer formed using the urethane resin composition containing the crosslinking agent has excellent film strength and good film-forming properties, but on the other hand, a primer layer formed using the urethane resin composition of the present invention can maintain the high deinking performance that is the objective of the present invention, even if it contains a crosslinking agent. In other words, the laminate of the present invention produced using a crosslinking agent can be made to be excellent in both film-forming properties and removability.

[0068] (Method for removing primer layer from substrate (C)) The primer layer can be removed from the substrate by immersing it in a warm alkaline solution. The alkaline substance used in the alkaline aqueous solution used to remove the primer layer in the present invention is not particularly limited, and examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), and ammonia. Preferably, NaOH or KOH is used. In the method for producing an alkaline aqueous solution, NaOH, KOH, ammonia, or the like is uniformly dissolved or dispersed in water, and the concentration or pH is appropriately adjusted to a specified level.

[0069] <Method for removing primer layer in the case of the laminate of the above embodiment (1-A)> Typically, the primer layer is removed by immersing the laminate in an alkaline aqueous solution having a pH of 11 or higher or a concentration of 0.5 to 3.0% by mass at 10 to 100°C for 30 minutes, followed by rinsing and drying to remove at least 90% of the primer layer. The pH is preferably 11.0 or higher, more preferably 13.0 or higher. The concentration of the aqueous solution is preferably 0.5 to 3.0% by mass, and more preferably 1.0 to 2.5% by mass. The immersion temperature is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. On the other hand, to prevent unintentional adhesion of an alkaline substance to the laminate and thus removal of the primer layer and the printed layer, it is necessary that the primer layer does not detach at low temperatures. Therefore, the immersion temperature is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher. The immersion time is preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less. After that, when the substrate is washed with water and dried, the removal rate of the primer layer is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0070] <Method for removing primer layer in the case of a laminate-type laminate such as the above (1-1) embodiment> In the case of the laminate of the above-mentioned (1-1) embodiment, the primer layer is sandwiched between plastic films, and it takes a considerable amount of time for the alkaline aqueous solution to reach the primer layer. Therefore, the immersion time is longer than that of the (1-A) embodiment, but it is more preferable that delamination proceeds in a short time. The immersion time is preferably within 24 hours, more preferably within 12 hours, and even more preferably within 6 hours.

[0071] As described above, the primer layer can be removed by immersing the laminate in a warm alkaline solution. That is, according to the present invention, the laminate is treated with a warm alkaline solution to remove the printed layer together with the primer layer from the substrate (C), thereby obtaining a recycled substrate (C). The same applies even if the laminate has a laminate-type structure, and according to the present invention, the laminate can be treated with a warm alkaline solution to remove the printed layer and / or substrate (D) from the substrate (C) together with the primer layer, thereby obtaining a recycled substrate (C), or a recycled substrate (C) and a recycled substrate (D) or a sealant film. [Example]

[0072] The present invention will be described in further detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, "%" in the compositions means "% by mass."

[0073] <Ester bond concentration (mmol / g)> The number of moles of ester bond groups contained in 1 g of urethane resin can be calculated based on the raw materials used in the synthesis of the polyester polyol and their blend amounts. First, the concentration of ester bond groups in 1 g of polyester polyol (a1) is calculated by the following formula (I): Formula (I) takes into consideration dehydration due to ester formation.

[0074]

number

[0075] <Hydroxyl value> Measure in accordance with the method described in JIS K1557-1.

[0076] <HSP distance> The structure of polyester polyol (a1) was represented by SMILES, and using the HSP calculation software HSP-iP, the dispersion force term (δD1), polar term (δP1), and hydrogen bond term (δH1) of the Hansen solubility parameters of polyester polyol (a1), which are three parameters of HSP, were obtained. In this case, when using two or more polyols, the product of the calculated HSP value and the 100% ratio of each polyol was used. Next, for ethyl acetate as the solvent, similarly, the dispersion force term (δD2), polar term (δP2), and hydrogen bond term (δH2) of the Hansen solubility parameters of the solvent were obtained from SMILES, and R (HSP distance) represented by the following calculation formula was calculated. R = {4(δD1 - δD2) 2 +(δP1 - δP2) 2 +(δH1 - δH2) 2} 0.5

[0077] <Acid value (mgKOH / g)> The mg number of KOH required when titrating the COOH groups contained in 1 g of urethane resin by the potassium hydroxide method is determined.

[0078] <00​​​​​ <Total concentration of urethane groups and urea groups (mmol / g)> The mass of the raw material monomer, which is the precursor of the polyisocyanate (b) residue contained in 1 g of the urethane resin, is divided by the NCO equivalent weight of the raw material monomer, which is the precursor of the polyisocyanate (b) residue, to obtain the value.

[0080] <Weight average molecular weight> The weight average molecular weight is measured by gel permeation chromatography (GPC).

[0081] <Hydroxyl value> Measurement is carried out in accordance with the method described in JIS K1557-1.

[0082] (Polyol) The compositions and physical properties of polyols 1 to 6 used in the examples and comparative examples are shown in Table 1 below. In Table 1, AA means adipic acid, NPG means neopentyl glycol, DEG means diethylene glycol, and EG means ethylene glycol. For example, Polyol 1 in Table 1 indicates that a polyester polyol was produced by mixing and reacting 0.55 g of adipic acid and 0.45 g of diethylene glycol. The raw material compositions of Polyols 2 to 4 and 6 are also shown in Table 1. The following products were used as raw materials for polyols 5, 7 and 8, which are non-polyester polyols. Polyol 5: Polyethylene glycol (NOF Corporation "PEG #600", number average molecular weight: 600) Polyol 7: Polyethylene glycol (NOF Corporation "PEG #2000", number average molecular weight: 2000) Polyol 8: Polypropylene glycol (AGC Corporation's "Exenol 2020", number average molecular weight: 2000)

[0083] [Table 1]

[0084] (urethane resin) 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 0.61 g of Polyol 1, 0.15 g of Polyol 5, 0.19 g of isophorone diisocyanate, and 0.05 g of isophorone diamine, and the mixture was reacted at 75°C for 8 hours under a nitrogen stream to obtain Urethane Resin 1. The composition and physical properties of urethane resin 1 are shown in Table 2 below, and the R (HSP distance) between polyester polyol and ethyl acetate in urethane resin 1 in particular is shown in Table 3.

[0085] Urethane resins 2 to 14 were prepared in the same manner as urethane resin 1, except that the composition was changed as shown in Table 2 below. The compositions and physical properties of polyurethane resins 2 to 14 are shown in Tables 2 and 3.

[0086] [Table 2]

[0087] [Table 3]

[0088] 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 1 is calculated. When the number of moles of carboxylic acid in 1 g of polyester polyol (a1) is a, a can be determined as follows. a = 0.55 (adipic acid content of polyol 1) / 146 (molecular weight of adipic acid) Next, the determined value a is substituted into the above formula (I). {a / (1-a×18(amount of water to be dehydrated))}×1000=8.8mmol / g

[0089] Next, the product of the ester bond group concentration in 1 g of polyester polyol (a1) and the proportion of polyester polyol (a1) in 1 g of urethane resin is calculated, and the ester bond group concentration in 1 g of urethane resin is calculated. 8.8 (ester bond group concentration of polyol 1) x 0.61 (polyol 2 content in urethane resin 1) = 5.34 mmol / g

[0090] The urea group concentrations shown in Table 2 were determined as follows. The urethane resin 1 will be used as an example. 0.05 (Isophoronediamine content in urethane resin 1) ÷ 85.15 (NCO equivalent weight of isophoronediamine) × 1000 = 0.60 mmol / g Here, the NCO equivalent weight of isophoronediamine is calculated by dividing the molecular weight of isophoronediamine by 2, which is 170.3 / 2=85.15.

[0091] The total concentration of urethane groups and urea groups shown in Table 2 was determined as follows. The urethane resin 1 will be used as an example. 0.19 (Isophorone diisocyanate content in urethane resin 1) ÷ 111.15 (NCO equivalent weight of isophorone diisocyanate) × 1000 = 1.67 mmol / g Here, the NCO equivalent weight of isophorone diisocyanate is calculated by dividing the molecular weight of isophorone diisocyanate by 2, which is 222.3 / 2=111.15.

[0092] R (HSP distance) shown in Table 3 was calculated as follows. The urethane resin 1 will be used as an example. First, each polyol in urethane resin 1 is represented by the following SMILES. Polyol 1: O=C(CCCCC(=O)OCCOCCX)OX Polyol 5: XOCCX The Hansen solubility parameters of each polyol were calculated using the HSP calculation software HSP-iP. The calculation results were as follows: Polyol 1: δD=16.3, δP=11.8, δH=4.5 Polyol 5: δD=17.9, δP=3.4, δH=2.6 Next, multiply by the weight ratio of each polyol in the total polyol to obtain the Hansen solubility parameter δD of the entire polyol. 1、 δP1 and δH1 were calculated. δD1=16.3×80%+17.9×20%=16.6 δP1=11.8×80%+3.4×20%=10.1 δH1=4.5×80%+2.6×20%=4.1 Next, for the organic solvent ethyl acetate, the SMILES is represented as CCOC(C)=O, and the Hansen solubility parameter δD is calculated using HSP-iP. 2、 ΔP2 and ΔH2 were calculated, and the calculation results were as follows: δD2=15.8 δP2=5.3 δH2=7.2 And based on these values R = {4(δD1-δD2) 2 +(δP1-δP2) 2 +(δH1-δH2) 2} 0.5 By calculating R (HSP distance) expressed as R={4(16.6-15.8) 2 +(10.1-5.3) 2 +(4.1-7.2) 2} 0.5 =6.0.

[0093] ((1-A) type laminate) A laminate having the surface-printed structure described below was prepared. (1-A) Base material (C) - primer layer - printing layer

[0094] Example 1 The laminate 1 used in Example 1 was produced as follows. As the base film 1, an OPP base film (Futamura Chemical Co., Ltd., "FOR 20 μm") was used. For the primer layer, urethane resin 1 was used, and the urethane resin composition contained a crosslinking agent. The primer layer containing a crosslinking agent was prepared as follows: 100 parts of urethane resin 1 was mixed with 9 parts of Bayhydur Ultra 3100 manufactured by Covestro, and then diluted with ethyl acetate to a solid content of 10%. The urethane resin composition obtained above was printed onto a substrate film 1 that had been subjected to a corona discharge treatment on one side using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) equipped with a gravure plate having a plate depth of 22 μm. The printed film was then dried at 100°C for 10 minutes and then left at room temperature for at least one day. The ink layer was prepared as follows: Laminating ink "Finart (DIC Corporation)" was diluted with a mixed organic solvent in the same ratio as the ink, and diluted to 16 seconds using a Rigo Zahn Cup No. 3. Printing was carried out using a gravure printing machine (DIC Engineering Corporation) equipped with a gravure plate with a plate depth of 22 μm. The resulting laminate 1 was aged at 40°C for 5 days. The configuration of the laminate 1 is shown in Table 4 below.

[0095] Laminates 2 to 38 were produced in the same manner as laminate 1, except that the configuration was changed as shown in Tables 4 to 10 below. The configurations of laminates 2 to 38 are shown in Tables 4 to 10.

[0096] Comparative laminates 1 to 12 were produced in the same manner as above, except that the configuration of laminate 1 was changed as shown in Table 11 or Table 12 below. Tables 11 and 12 show the structures of comparative laminates 1 to 12.

[0097] In Tables 4 to 12, PU resin means polyurethane resin. When the base film 1 is PET, the base film is "E5102 12 μm" manufactured by Toyobo Co., Ltd. When the primer layer did not contain a crosslinking agent, the primer layer was formed using a urethane resin composition diluted with ethyl acetate to a solid content of 10%. The urethane resin composition was applied using a gravure printing machine to form the primer layer as described above in the preparation of Laminate 1. The transparent vapor-deposited film 1 used in Comparative Example 12 was an alumina-deposited transparent PET film IB-PET-PUB (thickness: 12 μm) manufactured by Dai Nippon Printing Co., Ltd.

[0098] ((1-1) type laminate) A laminate having the laminate structure described below was prepared. (1-1) Base film 1 / primer layer / printing layer / adhesive layer / sealant film

[0099] The laminate 1' used in Example 1 was produced as follows. As the base film 1, an OPP base film (Futamura Chemical Co., Ltd., "FOR 20 μm") was used. For the primer layer, urethane resin 1 was used, and the urethane resin composition contained a crosslinking agent. The primer layer containing a crosslinking agent was prepared as follows: 100 parts of urethane resin 1 was mixed with 9 parts of Bayhydur Ultra 3100 manufactured by Covestro, and then diluted with ethyl acetate to a solid content of 10%. The urethane resin composition obtained above was printed onto a substrate film 1 that had been subjected to a corona discharge treatment on one side using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) equipped with a gravure plate having a plate depth of 22 μm. The printed film was then dried at 100°C for 10 minutes and then left at room temperature for at least one day. The ink layer was prepared as follows: Laminating ink "Finart (DIC Corporation)" was diluted with a mixed organic solvent in the same ratio as the ink, and diluted to 16 seconds using a Rigo Zahn Cup No. 3. Printing was carried out using a gravure printing machine (DIC Engineering Corporation) equipped with a gravure plate with a plate depth of 22 μm. A sealant film was laminated onto the printed material obtained as described above, which had the substrate film 1, primer layer, and printed layer laminated thereon, using an ether-based dry laminating adhesive "Dic Dry LX-760A / KP-70 (manufactured by DIC)" and a dry laminating machine (manufactured by DIC Engineering), to obtain laminate 1' of Example 1. Here, the sealant film used was "Pylen Film CT P1128 30 μm" manufactured by Toyobo Co., Ltd. The resulting laminate 1' was aged at 40°C for 5 days. The configuration of the laminate 1' is shown in Table 4 below.

[0100] Laminates 2' to 38' were produced in the same manner as above except that the configuration of laminate 1' was changed as shown in Tables 4 to 10 below. The configurations of the laminates 2' to 38' are shown in Tables 4 to 10.

[0101] Comparative laminates 1' to 12' were produced in the same manner except that the structure of laminate 1' was changed as shown in Tables 11 and 12 below. Tables 11 and 12 show the structures of comparative laminates 1' to 12'.

[0102] In Tables 4 to 12, PU resin refers to polyurethane resin. When the base film 1 is PET, the base film refers to "E5102 12 μm" manufactured by Toyobo Co., Ltd. When the base film is PP (polypropylene), the base film refers to "FOR 20 μm" manufactured by Futamura Chemical Co., Ltd. In the case of OPE, the base film is a uniaxially oriented polyethylene film (thickness: 25 μm, density: 0.92 g / m 2 , melting point 125°C). The crosslinking agent "BU3100" refers to "Bayhydur Ultra 3100" manufactured by Covestro. The primer layer containing the "BU3100" crosslinking agent was prepared by mixing 100 parts of urethane resin with 3 parts of Covestro's "Bayhydur Ultra 3100," then diluting the mixture with water to a solids content of 10%. When the primer layer did not contain a crosslinking agent, the primer layer was formed using a urethane resin composition diluted with isopropyl alcohol (IPA) to a solid content of 10%. The urethane resin composition was applied using a gravure printing machine to form the primer layer as described above in the preparation of the laminate 1'.

[0103] <Evaluation of Solvent Solubility> The state of dissolution after dilution with a crosslinking agent and solvent was judged and evaluated according to the following two stages. Good: Transparent, uniform solution Poor: Transparent homogeneous solution. Precipitation present. Inhomogeneous solution.

[0104] <Evaluation of deinking ability> Next, the laminate 1 was subjected to the following deinking test. <<Warm alkaline solution>> Peeling tests were carried out under the following conditions, and the ease of peeling under each condition was compared. Sodium hydroxide 2% or 1% by weight, no surfactant The liquid temperatures were set to 85°C and 55°C, respectively, according to the test conditions.

[0105] <<Peel test conditions>> The printed material was cut into a test piece measuring 20 mm x 20 mm, which was then immersed in the solution and stirred with a stirrer. After stirring, the peeling state was checked, and then the printed matter was rubbed with a finger to check whether the coating film would peel off by rubbing. The deinking properties of the ink coating film under the above conditions were evaluated according to the following evaluation criteria.

[0106] [Evaluation criteria] 5: Ink film peels off within 5 minutes of stirring. Completely peels off when rubbed. 4: After 15 minutes of stirring, the ink film peeled off. It completely came off when rubbed. 3: No peeling of the ink film was observed after 15 minutes of stirring. Complete detachment occurred when rubbed. 2: After 60 minutes of stirring, no peeling of the ink film was observed. Partial peeling occurred when rubbed. 1: No peeling of the ink film was observed after 60 minutes of stirring. No peeling was observed even when rubbed. Regarding the above evaluation results, a level of 4 or higher is preferable in practical use, but since a level of 3 can also contribute to recycling, a level of 3 or higher can be judged to be acceptable.

[0107] <Evaluation of alkali resistance> The peeling test was carried out using 2% by mass of sodium hydroxide at a liquid temperature of 25° C. If the sample did not peel off even when rubbed, it was evaluated as "good", and if it peeled off, it was evaluated as "poor".

[0108] The laminate 1' was subjected to the following delamination test.

[0109] <Evaluation of delamination properties> <<Warm alkaline solution>> Peeling tests were carried out under the following conditions, and the ease of peeling under each condition was compared. 1% sodium hydroxide by weight, no surfactant The liquid temperature was set to 85°C.

[0110] <<Delamination test conditions>> A test piece of the laminate (multilayer film) cut to a size of 10 mm x 10 mm was immersed in the solution and stirred with a stirrer. It was confirmed whether the substrate was delaminated from the multilayer film. Here, delamination is defined as a state in which a specific film in a multi-layered body is completely separated. The deinking properties of the ink coating film under the above conditions were evaluated according to the following evaluation criteria.

[0111] [Evaluation criteria] 4: Delamination of substrate from multi-layer film in less than 5 hours of stirring 3: The substrate delaminates from the multilayer film within 10 hours of stirring. 2: After 10 hours of stirring, signs such as the film lifting were observed, and after 24 hours of stirring, the substrate was delaminated from the multi-layer film. 1: After 10 hours of stirring, the appearance remained unchanged from before treatment. Regarding the above evaluation results, a score of 3 or higher is preferable in practice, but even a score of 2 can be judged to be at a level that can contribute to recycling.

[0112] Table 4 shows the evaluation results of the deinking properties of the laminate 1 and the evaluation results of the delamination properties of the laminate 1'.

[0113] (Examples 2 to 38 and Comparative Examples 1 to 12) Tests for deinking and delamination properties were conducted in the same manner as in Example 1, except that Laminate 1 and Laminate 1' in Example 1 were changed to Laminates 2 to 38, or Comparative Laminates 1 to 12, or Laminates 2' to 38', or Comparative Laminates 1' to 12', respectively. The evaluation results are shown in Tables 4 to 12. However, for Comparative Example 12 (Comparative Laminate 12) to Comparative Example 12 (Comparative Laminate 14), peeling occurred with an alkaline solution even under normal temperature conditions, and the object of the present invention could not be achieved, so a test for delamination properties was not conducted.

[0114] [Table 4]

[0115] [Table 5]

[0116] [Table 6]

[0117] [Table 7]

[0118] [Table 8]

[0119] [Table 9]

[0120] [Table 10]

[0121] [Table 11]

[0122] [Table 12]

[0123] As is clear from the results of the above examples, the primer layer of a laminate having a primer layer formed from the urethane resin composition of the present invention could be easily removed by using an alkaline solution at temperatures of 85° C. and 55° C. On the other hand, the primer layer was not removed by the alkaline solution at a temperature of 25° C. Furthermore, even though the laminate of the present invention has a laminate-type structure in which a plurality of layers are stacked, the primer layer can be removed by a warm alkaline solution. [Industrial Applicability]

[0124] According to the present invention, it is possible to provide a urethane resin composition that, although it is not peeled off even by a strongly alkaline substance under temperature conditions in normal use, forms a coating that can be detached from a plastic substrate by treatment with warm alkaline water.

[0125] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is thought to be a technology that can contribute to goals such as "No. 7 - Affordable and Clean Energy" and "No. 12 - Responsible Consumption and Production."

Claims

1. A laminate comprising a substrate (C), a primer layer formed by coating a urethane resin composition on the substrate, and a printed layer formed by printing a printing ink composition on the primer layer, The urethane resin composition contains a urethane resin (A) and an organic solvent (B), the urethane resin (A) is a reaction product of a polyol (a) and a polyisocyanate (b), The polyol (a) includes a polyester polyol (a1), R (HSP distance) represented by the following formula (1) is 9 or less, the urethane resin (A) has an ester bond group concentration of 3 mmol / g or more and 9 mmol / g or less, the acid value of the urethane resin (A) is 0 mgKOH / g or more and 15 mgKOH / g or less, the urethane resin (A) has a urea group concentration of 0.2 mmol / g or more and 2 mmol / g or less, A laminate, wherein the content of diethylene glycol residues or ethylene glycol residues in the total glycol components of the polyester in the urethane resin (A) is 50% by weight or more. R={4(δD １ -δD ２ ) ２ +(δP １ -δP ２ ) ２ +(δH １ -δH ２ ) ２ } ０．５ ・・・(1) (In the above formula (1), δD １ , δP １ and δH １ represent the dispersion force term, polarity term, and hydrogen bond term in the Hansen solubility parameter of the polyester polyol (a1), respectively, and δD ２ , δP ２ and δH ２ respectively represent the dispersion force term, polarity term, and hydrogen bond term in the Hansen solubility parameter of the organic solvent (B).

2. 2. The laminate according to claim 1, wherein the content of dicarboxylic acid residues having 6 or less carbon atoms in the acid component of the polyester in the urethane resin (A) is 50% by weight or more.

3. 2. The laminate according to claim 1, wherein the content of adipic acid residues in the acid component of the polyester in the urethane resin (A) is 50% by weight or more.

4. 2. The laminate according to claim 1, wherein the content of isophorone diisocyanate residues in the polyisocyanate component (b) in the urethane resin (A) is 50% by weight or more.

5. The polyol (a) further comprises a polyether polyol (a2), The laminate according to claim 1, wherein the urethane resin (A) is a reaction product of a polyester polyol (a1), a polyether polyol (a2), and a polyisocyanate (b).

6. The laminate according to claim 5 , wherein the polyether polyol (a2) comprises polyethylene glycol and / or polypropylene glycol.

7. 2. The laminate according to claim 1, wherein the total concentration of urethane groups and urea groups in the urethane resin (A) is 1.0 mmol / g or more and 3.0 mmol / g or less.

8. 2. The laminate according to claim 1, wherein the organic solvent (B) has an ethyl acetate content of 20% by weight or more and 100% by weight or less, and an isopropyl alcohol content of 0% by weight or more and 80% by weight or less.

9. 2. The laminate according to claim 1, wherein the organic solvent (B) has an ethyl acetate content of 60% by weight or more and 100% by weight or less, and an isopropyl alcohol content of 0% by weight or more and 40% by weight or less.

10. The laminate according to claim 1 , wherein the urethane resin composition further contains a crosslinking agent.

11. The laminate of claim 10, wherein the crosslinking agent is a polyisocyanate crosslinking agent.

12. A method for applying the urethane resin composition onto the substrate (C), comprising:

2. The laminate according to claim 1, wherein the coating method is an in-line coating method in which the urethane resin composition is applied to the substrate (C) during a stretching step and then a stretching step is further carried out, or an off-line coating method in which the urethane resin composition is applied to the substrate (C) after the stretching step and then dried to form the primer layer.

13. A packaging material or electronic equipment comprising the laminate according to claim 1.

14. The laminate further includes a substrate (D) different from the substrate (C), The laminate described in claim 1, wherein the substrate (D) is arranged on the surface of the printing layer opposite to the surface on which the substrate (C) is arranged, and the substrate (C), the primer layer, the printing layer, and the substrate (D) are laminated together.

15. A method for producing a recycled substrate, comprising treating the laminate according to claim 1 with an alkaline solution to remove the primer layer and the printed layer from the substrate (C), thereby obtaining a recycled substrate.

16. A method for producing a recycled substrate, comprising treating the laminate according to claim 14 with an alkaline solution to remove the primer layer, the printed layer, and / or the substrate (D) from the substrate (C), thereby obtaining a recycled substrate.

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