JP7803465B2 - Urethane resin composition, laminate using the urethane resin composition, packaging material or electronic equipment containing the laminate, and method for producing recycled substrate - Google Patents

Description

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

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 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.

Prior art has disclosed packaging materials that can be detached by treating a printing ink containing a urethane resin 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 composition are said to be releasable even at low temperatures and with strong alkalis, which means 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).

Japanese Patent Application Laid-Open No. 2020-90627 Japanese Patent Application Laid-Open No. 2020-196855 JP 2017-114930 A

The problem that the present invention aims to solve is to provide a urethane resin composition that will not peel off even with strongly alkaline substances under temperature conditions that are normally used, but will produce a coating that can be removed from plastic substrates by treatment with warm alkaline water.

As a result of extensive research to solve the above-mentioned problems, the inventors 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 the reaction product of polyol (a) and polyisocyanate (b) and organic solvent (B) as a material for forming a removable primer layer, and completed the present invention.

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(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 respectively represent the dispersion force term, polarity term and hydrogen bond term in the Hansen solubility parameter of the polyester polyol (a1), 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 [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),
[1] 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], wherein the laminate 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 includes a substrate (D) different from the substrate (C),
The laminate according to any one of [12] to [14], 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, 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.

The present invention provides a urethane resin composition that, under normal temperature conditions, is not stripped even by strong alkaline substances, but the coating can be removed from plastic substrates by treatment with warm alkaline water.

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

(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).

<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 that is used to obtain a target compound through a chemical reaction such as synthesis or decomposition and that partially constitutes the chemical structure of the target compound, and excludes substances that serve as chemical reaction aids, such as solvents and catalysts. 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 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 the coating is more likely to be detached from the plastic substrate by treatment with warm alkaline water.
In the present invention, 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.
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.

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

Examples of dicarboxylic acids (a1-1) that can be used when producing 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.

In addition to the dicarboxylic acid (a1-1), aliphatic carboxylic acids and alicyclic carboxylic acids can also 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, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, as well as their anhydrides and ester-forming derivatives. These may be used alone or in combination of two or more.

Examples of polyhydric hydroxyl group compounds (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.

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

Examples of catalysts that can be used include alkali metal or alkaline earth metal acetates, and compounds containing zinc, manganese, cobalt, antimony, germanium, titanium, tin, zirconium, etc. Among these, tetraalkyl titanates and tin oxalate, which are effective in transesterification reactions and polycondensation reactions, are particularly preferred.

The polyester polyol (a1) component is preferably contained in an amount ranging from 50% 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 polyurethane resin, the solvent solubility of the polyurethane resin decreases. Furthermore, it becomes difficult to remove the polyurethane resin from the plastic substrate by warm alkaline water treatment. Furthermore, if the amount exceeds 80% by mass, the polyurethane resin film tends to become brittle, reducing the blocking resistance of the ink film.

When producing urethane resin (A), polyester polyol (a1) and polyisocyanate (b) can also be used in combination with polyether polyol (a2), other polyols (a3), etc.

<<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. By containing the polyether polyol (a2), adhesion to films in particular is significantly improved, resulting in excellent blocking resistance and laminate strength.

It is preferable that the polyether polyol (a2) 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 polyurethane resin (A) film tends to become hard, resulting in reduced adhesion to plastic films. If the number average molecular weight is greater than 3,500, the polyurethane resin film tends to become brittle, resulting in reduced blocking resistance of the ink film. From the same perspective, it is more preferable that the number average molecular weight of the polyether polyol (a2) is 600 or more, even more preferably 1,000 or more, and even more preferably 2,000 or more.

The polyether polyol (a2) component is preferably contained in the range of 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 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 content exceeds 40% by mass, the ink film becomes excessively soft, tending to exhibit poor blocking resistance.

<<Other polyols (a3)>>
As the other polyol (a3), the same polyols as those used for the polyhydric hydroxyl compound (a1-2) can be used, and 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.

The other polyol (a3) component is preferably contained in an amount ranging from 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 film tends to harden, resulting in reduced adhesion to plastic films.

<<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, which may be used alone or in combination of two or more. Of 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.

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 distillation or other methods as needed when dispersing the urethane resin (A) in the organic solvent (B).

Examples of organic solvents (B) that can be used when producing urethane resin (A) include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetate esters 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.

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

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; 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.

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.

A chain extender can be used during or after the reaction of the polyester polyol (a1) and the polyisocyanate (b). A chain extender can also be used when dispersing the urethane resin (A) in the organic solvent (B).

＜＜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) according to 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 respectively represent the dispersion force term, polarity term and hydrogen bonding term in the Hansen solubility parameter of the polyester polyol (a1), and δD ₂ , δP ₂ and δH ₂ respectively represent the dispersion force term, polarity term and hydrogen bonding term in the Hansen solubility parameter of the organic solvent (B).

R (HSP distance) is an index of the solubility of the organic solvent (B) in the polyester polyol (a1); the lower the value, the better the solubility can be expected; in the present invention, R is 9 or less. R (HSP distance) is preferably 8 or less, and more preferably 7 or less. R (HSP distance) is also 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.

<<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 concentration of the ester bond group can be determined by calculating the number of moles of the ester bond group contained in 1 g of the urethane resin (A).
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 substrate adhesion and deinking ability of the resulting primer layer, and is preferably 8 mmol/g or less, and more preferably 7 mmol/g or less, from the viewpoint of good blocking resistance of the primer layer.

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.

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 the diamine contained in 1 g of the urethane resin by the NCO equivalent weight of the constituting 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.

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 but 95% by weight or less, and particularly preferably 80% by weight or more but 90% by weight or less.

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 in preparing 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, and 70% by weight or more is more preferable, and 80% by weight or more is 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.

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 a 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, the solubility in organic solvents 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 but 95% by weight or less, and particularly preferably 80% by weight or more but 90% by weight or less.

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 finally obtained 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 organic solvent solubility 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 isophorone diisocyanate content 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.

<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, N-methyl-2-pyrrolidone, etc. 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.

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

When dispersing the urethane resin (A) in the organic solvent (B), a machine such as a homogenizer can be used if necessary.

The urethane resin composition of the present invention preferably contains urethane resin (A) in the range 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. Furthermore, the organic solvent (B) is preferably contained in the range 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.

<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 and improving deinking properties. The crosslinking agent is preferably mixed and used immediately before coating or the like of the urethane resin composition of the present invention.

<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.

Among the additives, emulsifiers and leveling agents may cause a decrease in the durability of the resulting film, etc., so if 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.

(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.

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.

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

(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.

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) Substrate (C) - Primer layer - Printed layer

Furthermore, the laminate of the present invention is not limited to a laminate having a surface printing type structure in which a printed layer is formed on the surface of the laminate, as in the above-mentioned embodiment (1-A), but also encompasses a laminate having a laminate type 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 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, the substrate film 1 corresponds to the substrate (C) of the present invention. However, in embodiments where the substrate 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 substrate (C) of the present invention. Furthermore, the substrate film 2 corresponds to the substrate (D) of the present invention. In embodiments where the substrate 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 substrate (D) of the present invention. In many cases, the substrate (D) refers to a film formed on the surface opposite the substrate (C) in the laminate. However, in some cases, the substrate (D) is not limited to a film disposed on the surface, and the substrate (D) may be present between layers, or multiple substrates (D) may be provided in the laminate.

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/metal-deposited stretched film Transparent vapor-deposited 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

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

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 / metallized 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 / plastic (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 vapor deposition 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

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/printing layer/adhesive layer 1/metal-deposited 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

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.

(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

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."

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 can be appropriately designed 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 for (5-2) and (5-3) above.
(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/plastic Mater 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

When manufacturing 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 in the section above (Primer Layer), the primer layer may be formed by an inline coating method in which a urethane resin composition is applied during the film stretching process and then a further stretching process is performed, or the primer layer may be formed by an offline coating method in which a urethane resin composition is applied and dried after the film stretching process to form the primer layer.

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.

Examples of the base film 1 include an OPP film (a polypropylene film, for example, a biaxially oriented polypropylene film), a PET film (a polyethylene terephthalate film, for example, a biaxially oriented polyethylene terephthalate film), and a nylon film. The base film 1 may be coated to improve gas barrier properties or ink receptivity when a printing layer is provided. Examples of commercially available coated base films 1 include a K-OPP film and a 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 films, PET films, nylon films, 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.

The adhesive layer can be made of 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.
Particularly preferred adhesives with excellent gas barrier properties are those that satisfy at least one of the following conditions: an oxygen barrier property of 300 cc/ ^m2 /day/atm or less, or a water vapor barrier property of 120 g/ ^m2 /day or less, of a cured coating film of the adhesive applied at 3 g/ ^m2 (solid content). 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.

<Applications of the laminate>
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 thereof.
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 goods.
Furthermore, a laminate having a primer layer formed from the urethane resin composition of the present invention can also be used in packaging materials (more specifically, multi-layer packaging materials).
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.

<Characteristics of the 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 application of a warm alkaline solution, not only for laminates having a surface-printed type structure such as in the above-mentioned (1-A) embodiment, but also for laminates having a laminate-type structure such as in the above-mentioned (1-1) to (4-3-2-7) embodiments, and the substrate and printed 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.

(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 for removing the primer layer in the present invention is not particularly limited, and examples thereof 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.

<Method for removing primer layer in the case of the laminate of the above embodiment (1-A)>
Typically, the primer layer removal conditions include immersion for 30 minutes 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, 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 is preferably an aqueous solution of 0.5% by mass to 3.0% by mass, more preferably an aqueous solution of 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, which would otherwise cause detachment of the primer layer and ultimately removal of the printed layer, it is necessary that the primer layer not be detached 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 within 60 minutes, more preferably within 30 minutes, and even more preferably within 20 minutes. 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.

<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 embodiment (1-1), 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 embodiment (1-A), 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.

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 is 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.

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

<Ester bond group concentration (mmol/g)>
The number of moles of ester bond groups contained in 1 g of urethane resin is calculated based on the raw materials used in the synthesis of the 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.

In formula (I), a represents the number of moles of carboxylic acid residues in 1 g of polyester polyol (a1).
After determining the concentration of ester bond groups in 1 g of polyester polyol (a1), the product of the concentration of ester bond groups 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 concentration of ester bond groups in 1 g of urethane resin.

<Hydroxyl value>
The measurement is carried out in accordance with the method described in JIS K1557-1.

<HSP distance>
The structure of polyester polyol (a1) was expressed in SMILES, and the three HSP parameters of polyester polyol (a1), namely, the dispersion force term (δD ₁ ), polar term (δP ₁ ), and hydrogen bond term (δH ₁ ) in the Hansen solubility parameter, were calculated using HSP calculation software HSP-iP. When two or more polyols were used, the product of each calculated HSP value and the percentage of each polyol was used.
Next, for the solvent ethyl acetate, the dispersion force term (δD ₂ ), polar term (δP ₂ ), and hydrogen bond term (δH ₂ ) in the Hansen solubility parameters of the solvent were similarly determined from SMILES, 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

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

<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 value.

<Total concentration of urethane groups and urea groups (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 a value.

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

<Hydroxyl value>
The measurement is carried out in accordance with the method described in JIS K1557-1.

(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 "EXCENOL 2020", number average molecular weight: 2000)

(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.

Urethane resins 2 to 14 were prepared in the same manner as above, except that the composition of urethane resin 1 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.

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 removed))}×1000=8.8 mmol/g

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)×0.61 (content of polyol 2 in urethane resin 1)=5.34 mmol/g

The urea group concentrations shown in Table 2 were determined as follows.
The urethane resin 1 will be used as an example.
0.05 (content of isophoronediamine 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, that is, 170.3/2=85.15.

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 (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 calculated by dividing the molecular weight of isophorone diisocyanate by 2, that is, 222.3 divided by 2 = 111.15.

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 the 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 of each polyol was 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, the Hansen solubility parameters δD _1, δP ₁ , and δH ₁ of the entire polyol were calculated by multiplying by the weight ratio of each polyol in the total polyol.
δD ₁ = 16.3 x 80% + 17.9 x 20% = 16.6
δP ₁ = 11.8 x 80% + 3.4 x 20% = 10.1
δH ₁ =4.5×80%+2.6×20%=4.1
Next, for the organic solvent ethyl acetate, the SMILES is represented by CCOC(C)=O, and the Hansen solubility parameters δD2 _{, δP2} , and _δH2 were calculated using HSP-iP. The calculation results were as follows:
δD ₂ =15.8
δP ₂ =5.3
δH ₂ =7.2
Then, by calculating R (HSP distance) expressed as R={4(δD ₁ −δD ₂ ) ² +(δP ₁ −δP ₂ ) ² +(δH ₁ −δH ₂ ) ² } ^0.5 based on these values,
The result was R = {4(16.6 - 15.8) ² + (10.1 - 5.3) ² + (4.1 - 7.2) ² } ^0.5 = 6.0.

((1-A) type laminate)
A laminate having the surface-printed structure described below was prepared.
(1-A) Substrate (C) - Primer layer - Printed layer

Example 1
The laminate 1 used in Example 1 was produced as follows.
As the base film 1, an OPP base film ("FOR 20 μm" manufactured by Futamura Chemical Co., Ltd.) 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 on 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 Corporation) equipped with a gravure plate having a plate depth of 22 μm, followed by drying at 100° C. for 10 minutes and then leaving 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 structure of the laminate 1 is shown in Table 4 below.

Laminates 2 to 38 were produced in the same manner except that the structure of Laminate 1 was changed as shown in Tables 4 to 10 below.
The structures of laminates 2 to 38 are shown in Tables 4 to 10.

Comparative laminates 1 to 12 were prepared in the same manner except that the structure of laminate 1 was changed as shown in Table 11 or Table 12 below.
The structures of comparative laminates 1 to 12 are shown in Tables 11 and 12.

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 solids 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.

((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

The laminate 1' used in Example 1 was produced as follows.
As the base film 1, an OPP base film ("FOR 20 μm" manufactured by Futamura Chemical Co., Ltd.) 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 on 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 Corporation) equipped with a gravure plate having a plate depth of 22 μm, followed by drying at 100° C. for 10 minutes and then leaving 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.
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)" using a dry laminating machine (manufactured by DIC Engineering), thereby obtaining the 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 structure of the laminate 1' is shown in Table 4 below.

Laminates 2' to 38' were prepared in the same manner as above except that the structure of laminate 1' was changed as shown in Tables 4 to 10 below.
The structures of the laminates 2' to 38' are shown in Tables 4 to 10.

Comparative laminates 1' to 12' were prepared in the same manner except that the structure of laminate 1' was changed as shown in Tables 11 and 12 below.
The structures of comparative laminates 1' to 12' are shown in Tables 11 and 12.

In Tables 4 to 12, PU resin refers to polyurethane resin. When base film 1 is PET, the base film refers to "E5102 12 μm" manufactured by Toyobo Co., Ltd. When it is PP (polypropylene), the base film refers to "FOR 20 μm" manufactured by Futamura Chemical Co., Ltd.
In the case of OPE, the substrate film is a uniaxially oriented polyethylene film (film thickness 25 μm, density 0.92 g/m ² , melting point 125° C.).
The cross-linking agent "BU3100" refers to "Bayhydur Ultra 3100" manufactured by Covestro.
For the primer layer containing the "BU3100" crosslinking agent, 100 parts of urethane resin was mixed with 3 parts of "Bayhydur Ultra 3100" manufactured by Covestro, and then diluted with water to a solid 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 solids 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'.

<Evaluation of Solvent Solubility>
The state of dissolution after dilution with the crosslinking agent and solvent was judged and evaluated according to the following two stages.
Good: Transparent homogeneous solution. Bad: Transparent homogeneous solution with precipitates and inhomogeneous solution.

<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.
2% or 1% by mass of sodium hydroxide, no surfactant. The liquid temperatures were set to 85°C and 55°C, respectively, according to the test conditions.

<<Peel test conditions>>
The printed matter was cut into a test piece of 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.

[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.

<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 the sample peeled off, it was evaluated as “poor”.

The following delamination test was conducted on laminate 1'.

<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% by mass of sodium hydroxide, no surfactant The liquid temperature was set to 85°C.

<<Delamination test conditions>>
A test piece obtained by cutting the laminate (multilayer film) into 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.

[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.

The evaluation results of the deinking properties of Laminate 1 and the delamination properties of Laminate 1' are shown in Table 4.

(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 in an alkaline solution even under normal temperature conditions, and the object of the present invention could not be achieved, so a delamination test was not performed.

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.

The present invention provides a urethane resin composition that, under normal temperature conditions, is not stripped even by strong alkaline substances, but whose coating can be removed from plastic substrates by treatment with warm alkaline water.

[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 (16)

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 respectively represent the dispersion force term, polarity term and hydrogen bond term in the Hansen solubility parameter of the polyester polyol (a1), 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).) 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. 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. The laminate according to claim 1, wherein the content of isophorone diisocyanate residues in the polyisocyanate (b) component in the urethane resin (A) is 50% by weight or more. 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). The laminate according to claim 5, wherein the polyether polyol (a2) includes polyethylene glycol and/or polypropylene glycol. 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. The laminate described in 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. The laminate described in 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. The laminate according to claim 1, wherein the urethane resin composition further contains a crosslinking agent. The laminate according to claim 10, wherein the crosslinking agent is a polyisocyanate crosslinking agent. 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. Packaging material or electronic equipment comprising the laminate of claim 1. The laminate further includes a substrate (D) different from the substrate (C),
The laminate according to claim 1, wherein the substrate (D) is arranged on the surface of the printed layer opposite to the surface on which the substrate (C) is arranged, and the substrate (C), the primer layer, the printed layer and the substrate (D) are laminated together. A method for producing a recycled substrate, comprising treating the laminate described in claim 1 with an alkaline solution to remove the primer layer and the printed layer from the substrate (C), thereby obtaining a recycled substrate. A method for producing a recycled substrate, comprising treating the laminate described in 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.