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

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

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

[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.

[0002] In recent years, the marine plastic problem has become apparent due to the degradation of plastic discarded or dumped in the ocean in seawater, resulting in microplastics. These microplastics enter the bodies of marine organisms, where they accumulate, potentially affecting the health of seabirds and humans through the food chain. Recycling is one way to address this issue. 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 municipal waste sorting and collection systems. 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 removed by treating printing inks containing 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, adhesion to the substrate is expected to be insufficient, and adding an acid value to the urethane resin increases the resin's viscosity. This has led to problems such as the need to use solvents that have significant health and environmental impacts to adjust viscosity, or avoiding the coexistence of amine value and acid value to reduce viscosity, resulting in reduced suitability for lamination applications. As such, many issues remain regarding the use of urethane resin compositions in materials with removable coatings. Furthermore, a technique has been proposed in which an aqueous urethane resin composition is used as a removable primer layer, but the deinking properties of this composition are said to be releasable even at low temperatures and with strong alkalis. Specifically, there is the issue of coating peeling under normal usage conditions, such as when printed materials are exposed to strongly alkaline substances such as detergents in daily life (Patent Document 3).

[0004] JP 2020-90627 A JP 2020-196855 A JP 2017-114930 A

[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.

[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 encompasses the following aspects. [1] A urethane resin composition containing 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), and the polyol (a) contains a polyester polyol (a1), wherein R (HSP distance) represented by the following formula (1) is 9 or less, the ester bond group concentration of the urethane resin (A) is 3 mmol / g or more and 9 mmol / g or less, the acid value of the urethane resin (A) is 0 mg KOH / g or more and 15 mg KOH / g or less, the urea group concentration of the urethane resin (A) is 0.2 mmol / g or more and 2 mmol / g or less, and the content of diethylene glycol residues or ethylene glycol residues in all glycol components of the polyester in the urethane resin (A) is 50 wt % or more.

[0022] 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 ２represent the dispersion force term, polarity term, and hydrogen bond term, respectively, 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 (b) component in the urethane resin (A) is 50% by weight or more. [5] The urethane resin composition according to any one of [1] to [4], wherein the polyol (a) further contains a polyether polyol (a2), and 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) contains 20% by weight or more and 100% by weight or less of ethyl acetate and 0% by weight or more and 80% by weight or less of isopropyl alcohol. [9] The urethane resin composition according to any one of [1] to [8], wherein the organic solvent (B) contains 60% by weight or more and 100% by weight or less of ethyl acetate and 0% by weight or more and 40% by weight or less of isopropyl alcohol.

[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] The laminate according to any one of [1] to

[12] , wherein the method for applying the urethane resin composition to the substrate (C) is an in-line coating method in which the urethane resin composition is applied during a stretching process of the substrate (C) and then a stretching process is further performed, or an off-line coating method in which the urethane resin composition is applied and dried after the stretching process of the substrate (C), thereby forming the primer layer.

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

[12] or

[13] .

[15] The laminate according to any one of

[12] to

[14] , further comprising a substrate (D) different from the substrate (C), wherein the substrate (D) is disposed on the surface of the printed layer opposite to the surface on which the substrate (C) is disposed, 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, wherein the recycled substrate is obtained by treating the laminate according to

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

[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.

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

[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)> Urethane resin (A) is a general term for polymeric compounds having a urethane bond (—NHCOO—). In the present invention, the urethane resin (A) comprises 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). In addition to the polyester polyol (a1), the polyol (a) may optionally contain a polyether polyol (a2) and / or another polyol (a3). The urethane resin (A) may contain, as reaction raw materials, a polyether polyol (a2) and / or another polyol (a3) ​​in addition to the polyester polyol (a1) and polyisocyanate (b), or may be a reaction product of the polyester polyol (a1), the polyisocyanate (b), and the polyether polyol (a2) and / or another polyol (a3). As used herein, 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 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), polyvalent hydroxyl group compound (a1-2), polyether polyol (a2), and other polyols (a3). Furthermore, the term "residue" refers to a partial structure in the product compound formed by 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 diethylene glycol residues or ethylene glycol residues are contained within the above range among all glycol residues in the polyester polyol (a1) residues (also referred to as polyester or polyester component) constituting the urethane resin (A), the film is less susceptible to peeling even with strongly alkaline substances, and the film is more likely to be detached from plastic substrates by treatment with warm alkaline water. Furthermore, in the present invention, the content of dicarboxylic acid residues having 6 or fewer 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 carboxylic acid compound residues are contained within the above range among the residues of the acid components (e.g., carboxylic acid compounds) constituting the polyester in the urethane resin (A), the film is less susceptible to peeling even with strongly alkaline substances, and the film is more likely to be detached from plastic substrates by treatment with warm alkaline water. Furthermore, 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 subjecting a dicarboxylic acid (a1-1) to an esterification reaction with a polyhydric hydroxyl 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 anhydrides or ester-forming derivatives thereof. These may be used alone or in combination of two or more.

[0015] Examples of the polyhydric hydroxyl 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 polyhydric hydroxyl 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 pressure 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 of 50% by mass or more and 80% by mass or less 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, and the blocking resistance of the ink film decreases.

[0019] When producing the urethane resin (A), the polyester polyol (a1) and the polyisocyanate (b) may 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 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. By including the polyether polyol (a2), adhesion to films in particular is significantly improved, 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 3,500 or less. If the number average molecular weight of the polyether polyol is less than 100, the coating of the polyurethane resin (A) tends to be hard, resulting in reduced adhesion to plastic films. If the number average molecular weight is greater than 3,500, the coating of the polyurethane resin 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 1,000 or more, and even more preferably 2,000 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, and the tone reproducibility of printed matter tends to decrease. 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), the same polyols as those used for the polyhydric hydroxyl compound (a1-2) can be used. For example, 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 can be used.

[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, resulting in reduced adhesion to plastic films.

[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. Of these, 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 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, and the like, 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, etc. Examples of the chain extender that can be used when producing the urethane resin (A) include 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; Examples of suitable hydrazines include ethylenetriamine, dipropylenetriamine, and triethylenetetramine; hydrazine, N,N'-dimethylhydrazine, and 1,6-hexamethylenebishydrazine; succinic dihydrazide, adipic dihydrazide, glutaric dihydrazide, sebacic dihydrazide, and isophthalic dihydrazide; β-semicarbazidopropionic hydrazide, 3-semicarbazidopropylcarbazate, and semicarbazido-3-semicarbazidomethyl-3,5,5-trimethylcyclohexane, 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). Alternatively, the chain extender 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 from the dispersion force term, polarity term, and hydrogen bond term in the Hansen solubility parameters of the polyester polyol (a1) and the organic solvent (B) by the following formula (1): R={4(δD １ -δD ２ ) ２ + (δP １ -δP ２ ) ２ + (δH １ -δH ２ ) ２} ０．５ ... (1) Here, 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).

[0033] R (HSP distance) is an index of the solubility of the organic solvent (B) in the polyester polyol (a1), and the lower the value, the better the solubility can be expected, and R in the present invention is 9 or less. R (HSP distance) is preferably 8 or less, and more preferably 7 or less. Furthermore, R (HSP distance) is preferably 3 or more, and more preferably 5 or more. Among these, R (HSP distance) is preferably 3 or more and 8 or less, and more preferably 5 or more and 7 or less.

[0034] <<Characteristics 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. The 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 viewpoint of improving the substrate adhesion and deinking ability of the resulting primer layer, the ester bond group concentration is preferably 4 mmol / g or more, and more preferably 5 mmol / g or more. From the viewpoint of improving the blocking resistance of the primer layer, the ester bond group concentration is preferably 8 mmol / g or less, and 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, aqueous dispersion stability can be improved, and 7 mgKOH / g or more is preferable, and 8 mgKOH / g or more is more preferable. If the acid value is 15 mgKOH / g or less, adhesion to the polyester substrate can be well ensured, and 13 mgKOH / g or less is preferable, and 10 mgKOH / g or less is more preferable. Furthermore, from the viewpoint of resin viscosity and storage stability, the acid value is preferably 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 constituent diamine. A urea group concentration of 0.2 mmol / g or more can improve the durability of the final urethane resin composition, and is preferably 0.3 mmol / g or more, and more preferably 0.6 mmol / g or more. A urea group concentration of 2 mmol / g or less can ensure organic solvent solubility, and is preferably 1.7 mmol / g or less, and more preferably 1.5 mmol / g or less. 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 to prepare the polyester polyol (a1) used as the raw material for the urethane resin (A), and is the percentage obtained by dividing the weight of diethylene glycol or ethylene glycol in the polyester polyol (a1) by the weight of all glycols. A diethylene glycol residue or ethylene glycol residue content of 50% by weight or more can improve the deinking properties of the resulting primer layer, and is preferably 70% by weight or more, more preferably 80% by weight or more. The upper limit of the diethylene glycol residue or ethylene glycol residue content 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 but 95% by weight or less, and particularly preferably 80% by weight or more but 90% by weight or less.

[0038] Among the acid components 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. Among these, the dicarboxylic acid preferably has 3 or more carbon atoms, and more preferably 3 to 5 carbon atoms. The content of adipic acid residues can be calculated from the composition of the raw materials used to prepare the polyester polyol (a1) used as the raw material for the urethane resin (A), and is the weight of adipic acid in the polyester polyol (a1) divided by the weight of all dicarboxylic acids, expressed as a percentage. An adipic acid residue content of 50% by weight or more can improve the deinking properties of the resulting primer layer; a content of 70% by weight or more is more preferred, and a content of 80% by weight or more is even more preferred. 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 and 95% by weight or less, and particularly preferably 80% by weight or more and 90% by weight or less.

[0039] The content of isophorone diisocyanate residues in the polyisocyanate (b) component in the urethane resin (A) is preferably 50% by weight or more. The content of isophorone diisocyanate residues can be calculated from the composition of raw materials used in preparing the polyisocyanate (b) that serves as the raw material for the urethane resin (A), and is the percentage obtained by dividing the weight of isophorone diisocyanate in the polyisocyanate (b) by the total weight of the polyisocyanate. If the content of isophorone diisocyanate is 50% by weight or more, organic solvent solubility can be improved, and a content of 70% by weight or more is more preferred, and 80% by weight or more is even more preferred. 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 but 95% by weight or less, and particularly preferably 80% by weight or more but 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 the urethane resin (A) by the NCO equivalent weight of the constituting diisocyanate. If the urethane group and urea group concentration is 1.0 mmol / g or more, the durability of the finally obtained urethane resin composition can be improved, and 1.2 mmol / g or more is more preferable, and 1.5 mmol / g or more is even more preferable. If the urethane group and urea group concentration is 3.0 mmol / g or less, the organic solvent solubility can be ensured, and 2.5 mmol / g or less is more preferable, and 2.0 mmol / g or less is even more preferable. 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 serves 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 glycol, and N-methyl-2-pyrrolidone. Here, 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] In addition, in order to improve the compatibility with the polyester polyol (a1) and reduce the R (HSP distance), the organic solvent (B) that serves as the solvent for the urethane resin (A) preferably contains ethyl acetate at a content of 20% by weight or more and 100% by weight or less, and the content of isopropyl alcohol is preferably 0% by weight or more and 80% by weight or less. From the same viewpoint, the content of ethyl acetate is more preferably 60% by weight or more and 100% by weight or less, and the content of isopropyl alcohol is more preferably 0% by weight or more and 40% by weight or less. Similarly, in order to reduce the 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 necessary.

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

[0045] <Crosslinking Agent> In addition, in order to form a film or the like having excellent durability, it is preferable to use various crosslinking agents in combination with the urethane resin composition of the present invention. Examples of crosslinking agents 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. Among these, it is preferable to use a polyisocyanate crosslinking agent. From the viewpoints of improving adhesion to the substrate and improving deinking properties, the crosslinking agent is preferably used in an amount of 30% by mass or less, and more preferably 20% by mass or less, relative to the total amount of urethane resin (A). Furthermore, it is preferable to mix and use the crosslinking agent immediately before coating or the like of 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 needed.

[0047] Among the additives, the emulsifier and leveling agent may cause a decrease in the durability of the resulting film, etc., and therefore, when high durability is required for the film, etc., it is preferable to use them in an amount of 5 mass % or less relative to the total amount of the urethane resin composition.

[0048] (Primer Layer) A primer layer can be formed by applying the urethane resin composition of the present invention to a substrate. A printed 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 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 coater, an inkjet coater, 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 in-line 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] 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 by coating the urethane resin composition of the present invention on a substrate, and further has a printed layer formed by printing a printing ink composition on the primer layer.

[0052] The laminate having a primer layer formed using the urethane resin composition of the present invention is not limited to any particular embodiment, but the following embodiment (1-A) is preferred, for example: (1-A) Substrate (C) - Primer layer - Printed layer

[0053] The laminate of the present invention encompasses 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-described embodiment (1-A), but also laminates having a laminate structure in which a coating film (various layers or films) is further formed on the printed layer. In other words, the laminate of the present invention also encompasses laminate structures in which another substrate (substrate (D)) is placed on the side opposite the substrate (substrate (C)) on which the printed layer is placed, and the substrate (C), a primer layer, a printed layer, and the substrate (D) are laminated together. Examples of laminate structures include laminates having the following embodiments. In the examples of laminate structures described below, substrate film 1 corresponds to the substrate (C) in the present invention. However, in embodiments without substrate film 1, films such as a sealant film, a metal-vapor-deposited unstretched film, and a transparent vapor-deposited stretched film may correspond to the substrate (C) in the present invention. Furthermore, substrate film 2 corresponds to the substrate (D) in the present invention. In an embodiment without the substrate film 2, each film such as a sealant film, a metal-deposited unstretched film, or a transparent vapor-deposited stretched film corresponds to the substrate (D) of the present invention. The substrate (D) often refers to a film formed on the surface of the laminate opposite to the substrate (C), but in some cases, the substrate (D) is not limited to a film disposed on the surface, and may exist between layers, or multiple substrates (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 / printed layer / adhesive layer 1 / sealant film (1-2) Base film 1 / primer layer / printed layer / adhesive layer 1 / metallized unstretched film (1-3) Base film 1 / primer layer / printed layer / adhesive layer 1 / metallized stretched film (1-4) Transparent vapor-deposited stretched film / primer layer / printed layer / adhesive layer 1 / sealant film (1-5) Base film 1 / primer layer / printed layer / adhesive layer 1 / base film 2 / adhesive layer 2 / sealant film (1-6) Base film 1 / primer layer / printed layer / adhesive layer 1 / metallized stretched film / adhesive layer 2 / sealant film (1-7) Base film 1 / primer layer / printed layer / adhesive layer 1 / transparent vapor-deposited stretched film / adhesive layer 2 / sealant film (1-8) Base film 1 / primer layer / printed layer / adhesive layer 1 / metal layer / adhesive layer 2 / sealant film (1-9) Base film 1 / primer layer / printed layer / adhesive layer 1 / base film 2 / adhesive layer 2 / metal layer / adhesive layer 3 / sealant film (1-10) Base film 1 / primer layer / printed 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 / printed layer / adhesive layer 1 / primer layer / base film 2 / primer layer / adhesive layer 2 / sealant film (2-6) Base film 1 / primer layer / printed layer / adhesive layer 1 / primer layer / metal-deposited stretched film / primer layer / adhesive layer 2 / sealant film (2-7) Base film 1 / primer layer / printed 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 / printed 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 / printed 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 / printed layer / adhesive layer 1 / metal layer / adhesive layer 2 / primer layer / sealant film (3-9) Base film 1 / primer layer / printed 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 / printed 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 / printed 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 / printed 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 / printed 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 / printed 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 / printed 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, allowing the primer layer formed on one surface of the vapor-deposited film to be removed. 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 inner surface is removed. (4-2-6) Base film 1 / primer layer / printed layer / adhesive layer 1 / metal-deposited stretched film / primer layer / adhesive layer 2 / sealant film (4-2-7) Base film 1 / primer layer / printed layer / adhesive layer 1 / transparent vapor-deposited stretched film / primer layer / adhesive layer 2 / sealant film (4-3-4) Transparent vapor-deposited stretched film / printed layer / adhesive layer 1 / primer layer / sealant film (4-3-2-6) Base film 1 / primer layer / printed 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 / printed layer / adhesive layer 1 / transparent vapor-deposited stretched film / primer layer / adhesive layer 2 / primer layer / sealant film

[0058] The laminate having a laminate type structure may be 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 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, and the substrate (C), a primer layer, a printed layer, and an extrusion laminate layer are laminated together. Examples of laminates having an extrusion laminate type structure include laminates of the following embodiments. In the examples of the laminate type structure described below, the substrate film 1 corresponds to the substrate (C) of the present invention.

[0059] (5-1) Base film 1 / primer layer / printed layer / extrusion lamination anchor layer / extrusion laminate layer (5-2) Base film 1 / printed layer / primer layer / extrusion lamination anchor layer / extrusion laminate layer (5-3) Base film 1 / primer layer / printed layer / primer layer / extrusion lamination anchor layer / extrusion laminate 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 embodiments (5-1) to (5-3), an "anchor layer for extrusion lamination" is provided on the printed layer, but the "extrusion laminate layer" may be provided directly on the "printed layer" without providing an "anchor layer for extrusion lamination".

[0061] In addition to the above configurations (5-1) to (5-3), other layers such as a sealant layer may be disposed on the side of the extrusion laminate layer opposite to the side on which the base film 1 is disposed. The configurations of the other layers are not limited to the following (5-1-1) to (5-1-6) and can be designed appropriately depending on the required properties. The following is an example of a configuration in which other layers are provided in the configuration of (5-1) above. Similar configurations are also possible in the above (5-2) and (5-3). (5-1-1) Base film 1 / primer layer / printed layer / extrusion laminate anchor layer / extrusion laminate layer / adhesive layer 1 / sealant film (5-1-2) Base film 1 / primer layer / printed 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 / printed layer / extrusion laminate anchor layer / extrusion laminate layer / primer layer / adhesive layer 1 / sealant film (5-1-4) Base film 1 / primer layer / printed 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 / printed 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 / printed 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 carried out, 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 present invention is not limited thereto. The printed layer refers to, for example, a printed layer formed by printing ink. Examples of the printed layer include a printed layer formed by using a colored pigment or a white pigment as a colorant and a printing ink containing the colorant. The printing method of 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 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 OPP film (polypropylene film, e.g., biaxially oriented polypropylene film), PET film (polyethylene terephthalate film, e.g., biaxially oriented polyethylene terephthalate film), and nylon film. The base film 1 may be coated to improve gas barrier properties or 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 CPP film (unstretched polypropylene film) and LLDPE film (linear low-density polyethylene resin film). Examples of the metal-vapor-deposited unstretched film include VM-CPP film, which is CPP film vapor-deposited with a metal such as aluminum. Examples of the metal-vapor-deposited stretched film include VM-OPP film, which is OPP film vapor-deposited with a metal such as aluminum. Examples of the transparent vapor-deposited stretched film include films obtained by vapor-depositing silica or alumina onto OPP film, PET film, nylon film, or the like. For the purpose of protecting the inorganic vapor deposition layer of silica or alumina, a film having a coating applied thereto may be used. The metal layer may be aluminum foil or the like. The base film 2 may be a nylon film or the like.

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

[0066] <Applications of Laminates> The urethane resin composition of the present invention can be suitably used for packaging materials or electronic materials as a surface treatment agent (primer coating agent) for substrates in molded articles having an overprinted layer, including a printed layer, such as electronic materials, building materials, textiles / leather, home appliances, vehicles such as cars and airplanes, furniture, office supplies, play equipment, sporting goods, or molded parts thereof. Therefore, a laminate having a primer layer formed from the urethane resin composition of the present invention can be applied to various molded articles, such as electronic materials, building materials, textiles / leather, home appliances, vehicles such as cars and airplanes, furniture, office supplies, play equipment, sporting goods, or molded parts thereof. Furthermore, a laminate having a primer layer formed from the urethane resin composition of the present invention can also be applied to packaging materials (more specifically, multilayer packaging materials). It can also be used as a multilayer packaging material. When used as a multilayer packaging material, the layer structure can be changed depending on the contents, usage environment, and usage form. When used as a packaging material, for example, a product using a packaging material formed from the laminate of the present invention is produced by filling the contents through the opening and then heat-sealing the opening. 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] <Laminate Properties> The primer layer formed from the urethane resin 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. Furthermore, the primer layer of the laminate of the present invention can be removed in a simple manner using a warm alkaline solution, allowing for easy peeling of the substrate and the printed layer. However, the primer layer of the laminate of the present invention does not peel off even when an alkaline solution is applied under temperature conditions normally used. Therefore, under temperature conditions normally used, even if an alkaline solution is unintentionally attached, the laminate can be used safely without worrying about peeling. The primer layer of a laminate having a primer layer formed from the urethane resin composition of the present invention can be easily removed by application of a warm alkaline solution, allowing for easy peeling of the substrate and the printed layer, not only for laminates having a surface-printed 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. 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 is removed from the substrate by immersing the substrate in a warm alkaline solution. In the alkaline aqueous solution used to remove the primer layer in the present invention, the alkaline substance to be used is not particularly limited, and examples thereof include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ２ ), ammonia, etc. are preferred. NaOH or KOH is preferred. In a method for producing an alkaline aqueous solution, NaOH, KOH, ammonia, etc. may be uniformly dissolved or dispersed in water, and the resulting solution may be appropriately adjusted to a specified concentration or pH.

[0069] <Method for Removing Primer Layer in the Case of Laminate of the Above (1-A) Form> Typically, the primer layer removal conditions include immersing the laminate in an alkaline aqueous solution having a pH of 11 or higher or a concentration of 0.5% by mass to 3.0% by mass at 10°C to 100°C for 30 minutes, followed by rinsing and drying to remove 90% or more 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% by mass to 3.0% by mass, and more preferably 1.0% by mass 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 therefore 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 60 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less. After rinsing with water and drying, 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 a laminate such as the above (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, a longer immersion time is required than in the (1-A) embodiment, but a method in which delamination proceeds in a short time is more preferable. 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 to laminates having 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) together with the primer layer from the substrate (C), thereby obtaining a recycled substrate (C), or a recycled substrate (C) and a recycled substrate (D) or a sealant film.

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

[0074] In formula (I), a represents the number of moles of carboxylic acid residues in 1 g of polyester polyol (a1). After determining the ester bond group concentration in 1 g of polyester polyol (a1), the product of the ester bond group concentration in 1 g of polyester polyol (a1) and the proportion of polyester polyol (a1) residues in 1 g of urethane resin is then determined to calculate the ester bond group concentration in 1 g of urethane resin.

[0075] <Hydroxyl value> The hydroxyl value is measured in accordance with the method described in JIS K1557-1.

[0076] <HSP distance> The structure of the polyester polyol (a1) is expressed in SMILES, and the dispersion force term (δD １ ), polarity term (δP １ ), hydrogen bond term (δH １ ) was calculated. When two or more polyols were used, the product of the calculated HSP value and the percentage of each polyol was used. Next, for the solvent ethyl acetate, the dispersion force term (δD ２ ), polarity term (δP ２ ), hydrogen bond term (δH ２ ) was obtained, and R (HSP distance) was calculated using the following formula: R = {4(δD １ -δD ２ ) ２ + (δP １ -δP ２ ) ２ + (δH １ -δH ２ ) ２} ０．５

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

[0078] <Urea Group Concentration> The weight of the diamine residue contained in 1 g of the urethane resin is divided by the NCO equivalent weight of the constituting diamine to obtain the urea group concentration.

[0079] <Total concentration of urethane group and urea group (mmol / g)> The mass of the raw material monomer, which is a 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 a precursor of the polyisocyanate (b) residue, to obtain the total concentration.

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

[0081] <Hydroxyl value> The hydroxyl value is measured 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 Inc., "Exenol 2020," number average molecular weight: 2000)

[0083]

[0084] (Urethane Resin) Urethane resin 1 was synthesized as follows. 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 were charged into a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 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 the 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 Urethane Resins 2 to 14 are shown in Tables 2 and 3.

[0086]

[0087]

[0088] The ester bond group concentrations shown in Table 2 were determined as follows. An example will be described using urethane resin 1. First, the ester bond group concentration in 1 g of polyol 1 is calculated. If 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 in polyol 1) / 146 (molecular weight of adipic acid) Next, the determined a is substituted into the above formula (I): {a / (1 - a x 18 (amount of water to be removed))} x 1000 = 8.8 mmol / 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 to calculate the ester bond group concentration in 1 g of urethane resin: 8.8 (ester bond group concentration of polyol 1) × 0.61 (content of polyol 2 in urethane resin 1) = 5.34 mmol / g

[0090] The urea group concentrations shown in Table 2 were determined as follows. An example will be described using urethane resin 1: 0.05 (content of isophorone diamine in urethane resin 1) ÷ 85.15 (NCO equivalent weight of isophorone diamine) × 1000 = 0.60 mmol / g. Here, the NCO equivalent weight of isophorone diamine is determined by dividing the molecular weight of isophorone diamine by 2, or 170.3 ÷ 2 = 85.15.

[0091] The total concentration of urethane groups and urea groups shown in Table 2 was determined as follows. An example will be described using Urethane Resin 1: 0.19 (content of isophorone diisocyanate 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 determined by dividing the molecular weight of isophorone diisocyanate by 2, or 222.3 ÷ 2 = 111.15.

[0092] The R (HSP distance) shown in Table 3 was calculated as follows. An explanation will be given using urethane resin 1 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 Then, the Hansen solubility parameter was calculated for each polyol 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, the Hansen solubility parameter δD of the entire polyol was calculated by multiplying by the weight ratio of each polyol in the total polyol. １、 δP １ and δH １ was calculated. １ =16.3×80%+17.9×20%=16.6 δP １ =11.8×80%+3.4×20%=10.1 δH １ = 4.5 × 80% + 2.6 × 20% = 4.1 Next, for the organic solvent ethyl acetate, SMILES is expressed as CCOC(C)=O, and the Hansen solubility parameter δD is calculated using HSP-iP. ２、 δP ２ and δH ２ The calculation results were as follows: δD ２ = 15.8 δP ２ = 5.3 δH ２ = 7.2 Based on these values, R = {4(δD １ -δD ２ ) ２ + (δP １ -δP ２ ) ２ + (δH １ -δH ２ ) 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 following surface-printed structure was prepared: (1-A) Substrate (C) - Primer layer - Printed layer

[0094] Example 1 The laminate 1 used in Example 1 was prepared as follows. An OPP substrate film (FOR 20 μm, manufactured by Futamura Chemical Co., Ltd.) was used as the substrate film 1. Urethane resin 1 was used for the primer layer, and a crosslinking agent was added to the urethane resin composition. The crosslinking agent-containing primer layer was prepared as follows. Urethane resin 1 was used, and 9 parts of Bayhydur Ultra 3100, manufactured by Covestro, were mixed with 100 parts of the urethane resin, and then diluted with ethyl acetate to a solids content of 10%. The urethane resin composition obtained above was printed on substrate film 1, one side of which had been subjected to a corona discharge treatment, using a gravure printing machine (manufactured by DIC Engineering Corporation) equipped with a gravure plate with a plate depth of 22 μm. The print 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 (manufactured by 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 (manufactured by 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 composition of 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 structure of laminate 1 was changed as shown in Tables 4 to 10. The structures 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 laminate 1, except that the structure of laminate 1 was changed as shown in Table 11 or Table 12. The structures of comparative laminates 1 to 12 are shown in Tables 11 and 12.

[0097] In Tables 4 to 12, PU resin means polyurethane resin. When base film 1 is PET, the base film is "E5102 12 μm" manufactured by Toyobo Co., Ltd. When the primer layer does not contain a crosslinking agent, the primer layer is formed using a urethane resin composition diluted with ethyl acetate to a solids content of 10%. The method of applying the urethane resin composition using a gravure printing machine to form the primer layer is as described above in the preparation of laminate 1. The transparent vapor-deposited film 1 used in Comparative Example 12 is 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 following laminate structure was prepared: (1-1) Base film 1 / primer layer / printed layer / adhesive layer / sealant film

[0099] The laminate 1' used in Example 1 was prepared as follows. An OPP substrate film (FOR 20 μm, manufactured by Futamura Chemical Co., Ltd.) was used as the substrate film 1. Urethane resin 1 was used for the primer layer, and a crosslinking agent was added to the urethane resin composition. The crosslinking agent-containing primer layer was prepared as follows. Urethane resin 1 was used, and 9 parts of Bayhydur Ultra 3100 manufactured by Covestro were mixed with 100 parts of the urethane resin, followed by dilution with ethyl acetate to a solids content of 10%. The urethane resin composition obtained above was printed on substrate film 1, one side of which had been subjected to a corona discharge treatment, using a gravure printing machine (manufactured by DIC Engineering Corporation) equipped with a gravure plate with a plate depth of 22 μm. The print 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 (manufactured by 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. This was printed using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) equipped with a gravure plate with a plate depth of 22 μm. A sealant film was laminated onto the printed matter obtained above, consisting of the substrate film 1, primer layer, and printed layer, using an ether-based dry laminating adhesive "Dicdry LX-760A / KP-70 (manufactured by DIC)" and a dry laminating machine (manufactured by DIC Engineering), to obtain Laminate 1' of Example 1. The sealant film used here 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 Laminate 1' is shown in Table 4 below.

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

[0101] Comparative laminates 1' to 12' were produced in the same manner as above, except that the structure of laminate 1' was changed as shown in Tables 11 and 12. The structures of comparative laminates 1' to 12' are shown in Tables 11 and 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. When the base film is OPE, the base film refers to a uniaxially oriented polyethylene film (thickness 25 μm, density 0.92 g / m ２ , melting point 125°C). The crosslinker "BU3100" refers to "Bayhydur Ultra 3100" manufactured by Covestro. A primer layer containing the "BU3100" crosslinker was prepared by mixing 3 parts of "Bayhydur Ultra 3100" manufactured by Covestro with 100 parts of urethane resin, and then diluting the mixture with water to a solids content of 10%. When the primer layer did not contain a crosslinker, the primer layer was formed using a urethane resin composition diluted with isopropyl alcohol (IPA) to a solids content of 10% relative to the urethane resin. The method of applying the urethane resin composition using a gravure printing machine to form the primer layer was as described above in the preparation of laminate 1'.

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

[0104] <Evaluation of deinking properties> Next, the following deinking property test was carried out on the laminate 1. <<Warm alkaline solution>> A peeling test was carried out under each of the following conditions, and the ease of peeling under each condition was compared. 2% or 1% by mass of sodium hydroxide, no surfactant The liquid temperature was set to 85°C and 55°C according to the test conditions.

[0105] <<Peeling test conditions>> Test pieces of printed matter cut to a size of 20 mm x 20 mm were immersed in the solution and stirred with a stirrer. After stirring, the state of peeling was confirmed, and then the printed matter was rubbed with a finger to confirm whether the coating film peeled off when rubbed. The deinking ability of the ink coating film under the above conditions was evaluated according to the following evaluation criteria.

[0106] [Evaluation criteria] 5: Peeling of the ink film was confirmed within 5 minutes of stirring. Completely removed when rubbed 4: Peeling of the ink film was confirmed after 15 minutes of stirring. Completely removed when rubbed 3: No peeling of the ink film was confirmed after 15 minutes of stirring. Completely removed when rubbed 2: No peeling of the ink film was confirmed after 60 minutes of stirring. Partially removed when rubbed 1: No peeling of the ink film was confirmed after 60 minutes of stirring. No peeling was confirmed even when rubbed Note that, for the above evaluation results, a level of 4 or higher is preferable in practice, but since even a level of 3 can contribute to recycling, a level of 3 or higher can be considered an acceptable level.

[0107] <Evaluation of Alkali Resistance> A 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 the sample 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>> A peeling test was carried out under the following conditions, and the ease of peeling under each condition was compared: 1% by mass of sodium hydroxide, no surfactant The liquid temperature was set to 85°C.

[0110] <<Delamination Test Conditions>> Test pieces of laminated material (multilayer film) cut to a size of 10 mm x 10 mm were immersed in the solution and stirred with a stirrer. It was confirmed whether the substrate had been delaminated from the multilayer film. Here, delamination is defined as a state in which a specific film in the multilayer body has been 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: The substrate was delaminated from the multilayer film after less than 5 hours of stirring 3: The substrate was delaminated from the multilayer film after 10 hours of stirring 2: Signs such as the film floating up were observed after 10 hours of stirring, and the substrate was delaminated from the multilayer film after 24 hours of stirring 1: No change in appearance from before treatment after 10 hours of stirring Note that, for the above evaluation results, a rating of 3 or higher is preferable in practice, but even a rating of 2 can be considered to be at a level that can contribute to recycling.

[0112] Table 4 shows the evaluation results of the deinking properties of Laminate 1 and the evaluation results of the delamination properties of 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 Examples 12 (Comparative Laminate 12) to 12 (Comparative Laminate 14), peeling occurred in an alkaline solution even under normal temperature conditions, and the object of the present invention could not be achieved, so delamination tests were not conducted.

[0114]

[0115]

[0116]

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[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 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 when the laminate of the present invention had a laminate-type structure in which multiple layers were stacked, the primer layer could be removed by a warm alkaline solution.

[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 urethane resin composition containing 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), and the polyol (a) contains a polyester polyol (a1), R (HSP distance) represented by the following formula (1) is 9 or less, the ester bond group concentration of the urethane resin (A) is 3 mmol / g or more and 9 mmol / g or less, the acid value of the urethane resin (A) is 0 mg KOH / g or more and 15 mg KOH / g or less, the urea group concentration of the urethane resin (A) is 0.2 mmol / g or more and 2 mmol / g or less, and the content of diethylene glycol residues or ethylene glycol residues in all glycol components of the polyester in the urethane resin (A) is 50 wt% 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. The urethane resin composition 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 said urethane resin (A) is 50% by weight or more.

3. The urethane resin composition 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. The urethane resin composition 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 urethane resin composition according to claim 1, wherein the polyol (a) further contains a polyether polyol (a2), and 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 claim 5, wherein the polyether polyol (a2) contains polyethylene glycol and / or polypropylene glycol.

7. The urethane resin composition 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. The urethane resin composition according to claim 1, wherein the organic solvent (B) contains 20% by weight or more and 100% by weight or less of ethyl acetate and 0% by weight or more and 80% by weight or less of isopropyl alcohol.

9. The urethane resin composition according to claim 1, wherein the organic solvent (B) contains 60% by weight or more and 100% by weight or less of ethyl acetate and 0% by weight or more and 40% by weight or less of isopropyl alcohol.

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

11. The urethane resin composition according to claim 10, wherein the crosslinking agent is a polyisocyanate crosslinking agent.

12. A laminate comprising a substrate (C) and a primer layer formed by coating the urethane resin composition described in any one of claims 1 to 5 on the substrate (C), and further comprising a printed layer formed by printing a printing ink composition on the primer layer.

13. The laminate according to claim 12, wherein the method for applying the urethane resin composition onto the substrate (C) is an in-line coating method in which the urethane resin composition is applied during a stretching process of the substrate (C) and then a stretching process is carried out, or an off-line coating method in which the urethane resin composition is applied and dried after the stretching process of the substrate (C) to form the primer layer.

14. A packaging material or electronic equipment comprising the laminate of claim 12.

15. The laminate according to claim 12, further comprising a substrate (D) different from the substrate (C), the substrate (D) being disposed on the surface of the printed layer opposite to the surface on which the substrate (C) is disposed, and the substrate (C), the primer layer, the printed layer and the substrate (D) being laminated together.

16. A method for producing a recycled substrate, comprising treating the laminate described in claim 12 with an alkaline solution to remove the primer layer and the printed layer from the substrate (C), thereby obtaining a recycled substrate.

17. A method for producing a recycled substrate, comprising treating the laminate described in claim 15 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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