Laminate

Abstract

Provided is a laminate that has excellent storage stability and that exhibits excellent interlayer adhesiveness.　This laminate includes a base material layer (A) and a crosslinked polyester resin layer (B) in the stated order. The base material layer (A) contains at least one selected from the group consisting of aluminum, steel, stainless steel, copper, and glass. The crosslinked polyester resin layer (B) contains a transesterification catalyst (E), and a crosslinked polyester resin (b) that is a reaction product of an epoxy compound (D) and a polyester resin (C) having a carboxy group in a side chain.

Description

Laminated body

[0001] The present disclosure relates to a laminated body having excellent interlayer adhesion.

[0002] Conventionally, a laminated body in which a base material layer and a resin layer are laminated is lighter than a component made of only the base material and has higher strength than a component made of only the resin. Therefore, it is used in various applications such as building members, electric and electronic members, and automotive parts.

[0003] As a technology related to a laminated body of a base material layer and a resin layer, for example, the one described in Patent Document 1 can be cited. Patent Document 1 describes a method for producing a laminated body, which includes a step of applying an adhesive layer composition containing an acrylic resin containing a repeating unit derived from an ethylenically unsaturated monomer having a divalent sulfur atom on a base material, and then performing energy application on the applied adhesive layer composition to form a resin layer on the surface of the base material.

[0004] Japanese Patent Application Laid-Open No. 2010-76139

[0005] In the technology described in Patent Document 1, steps such as uniformly applying the adhesive layer composition on the surface of the base material and applying energy to the adhesive layer composition are required. Further, in the technology described in Patent Document 1, after energy application, washing with a solvent or water is performed for the purpose of removing unreacted compounds remaining in the adhesive layer, so there is a concern about storage stability. From the above, there is a need for a laminated body having excellent storage stability and interlayer adhesion.

[0006] As a result of intensive studies to solve the above problems, the present inventor has found that the following laminated body can achieve the above object, and has completed the present invention. That is, the present disclosure is as follows.

[0007] [1] A laminate comprising a base layer (A) and a crosslinked polyester resin layer (B) in that order, wherein the base layer (A) is a layer comprising at least one selected from the group consisting of aluminum, steel, stainless steel, copper, and glass, and the crosslinked polyester resin layer (B) is a layer comprising a crosslinked polyester resin (b) which is a reaction product of a polyester resin (C) having carboxyl groups in its side chains and an epoxy compound (D), and a transesterification catalyst (E). [2] The laminate according to [1], wherein the crosslinked polyester resin layer (B) has a base layer (F) or resin layer (G) provided on the side opposite to the base layer (A), wherein the base layer (F) is a layer comprising at least one selected from the group consisting of aluminum, steel, stainless steel, copper, and glass, and the resin layer (G) is a layer comprising a polyimide resin and / or a polyester resin. [3] The laminate according to [1] or [2], wherein the acid value of the polyester resin (C) having carboxyl groups in its side chains is 5 to 40 mg KOH / g. [4] A laminate according to any one of [1] to [3], comprising 10 to 40 moles of the transesterification catalyst (E) per 100 moles of carboxyl groups of the polyester resin (C) having carboxyl groups in its side chains. [5] A laminate according to any one of [1] to [4], comprising 50 to 150 moles of the epoxy compound (D) per 100 moles of carboxyl groups of the polyester resin (C) having carboxyl groups in its side chains.

[0008] The laminate of this disclosure exhibits excellent interlayer adhesion between the layers constituting the laminate, and can be used in a variety of applications such as building materials, electrical and electronic components, and automotive parts. Furthermore, the crosslinked polyester resin layer constituting the laminate forms a crosslinked structure at room temperature, thus possessing high strength, excellent adhesion to the base material layer and resin layer, and storage stability. In addition, the crosslinked polyester resin layer exhibits softening behavior at high temperatures, resulting in excellent moldability of the laminate.

[0009] Figure 1 is a partial cross-sectional view of the two-layer laminate of this embodiment. Figure 2 is a partial cross-sectional view of the three-layer laminate of this embodiment.

[0010] The laminate, which is an embodiment of the present disclosure, will be described below. In the following, the notation "~" indicating a numerical range will mean "less than" or "greater than," unless otherwise specified. In other words, "A~B" means "A or greater and B or less."

[0011] <Laminates> The laminates of the present disclosure include a two-layer laminate in which a base layer (A) and a crosslinked polyester resin layer (B) are laminated in that order, or a three-layer laminate in which a base layer (A) and a crosslinked polyester resin layer (B) are laminated in that order, and a further base layer (F) or resin layer (G) is bonded to the side of the crosslinked polyester resin layer (B) opposite to the base layer (A). The laminated structure of the two-layer laminate is, for example, base layer (A) / crosslinked polyester resin (B). The laminated structure of the three-layer laminate is, for example, base layer (A) / crosslinked polyester resin (B) / base layer (F), or base layer (A) / crosslinked polyester resin (B) / resin layer (G). The laminated structures of the laminates of the present disclosure are not limited to these.

[0012] A laminate including a two-layer laminate can be obtained, for example, by overlapping a base material layer (A) and a crosslinked polyester resin layer (B), pressing them together under heat, and then cooling them.

[0013] A laminate including a three-layer laminate can be obtained, for example, by creating a laminate of a base material layer (A) and a crosslinked polyester resin layer (B), then overlapping a base material layer (F) or a resin layer (G) on the side of the crosslinked polyester resin layer (B) opposite to the base material layer (A), pressing them together under heat, and then cooling. Alternatively, a laminate including a three-layer laminate can also be obtained, for example, by overlapping a base material layer (A), a crosslinked polyester resin layer (B), and a base material layer (F) or a resin layer (G), pressing them together under heat, and then cooling.

[0014] The temperature at which the base layer (A) or base layer (F) and the crosslinked polyester resin layer (B) are heated is preferably, for example, 150 to 190°C, and more preferably 160 to 180°C. The pressure at which the base layer (A) or base layer (F) and the crosslinked polyester resin layer (B) are pressed together is, for example, 15 to 25 kgf / cm². ２(1.47 to 2.45 MPa) is preferred, and more preferably 18 to 23 kgf / cm². ２ (1.77–2.26 MPa).

[0015] The temperature at which the resin layer (G) and the crosslinked polyester resin layer (B) are heated is not particularly limited, as long as it is below the melting point of the resin layer (G). The pressure at which the resin layer (G) and the crosslinked polyester resin layer (B) are pressed together is, for example, 15 to 25 kgf / cm². ２ (1.47 to 2.45 MPa) is preferred, and more preferably 18 to 23 kgf / cm². ２ (1.77–2.26 MPa).

[0016] <Base Layer (A) and Base Layer (F)> Base Layer (A) and Base Layer (F) are layers (bases) comprising at least one material selected from the group consisting of aluminum, steel, stainless steel, copper, and glass. Aluminum may be an alloy. Steel may be a plated steel sheet having a plating layer, and if the steel is a plated steel sheet, it may be, for example, a galvanized steel sheet or a hot-dip galvanized steel sheet. Copper may be an alloy. Base Layer (A) and Base Layer (F) are preferably aluminum, steel, or stainless steel, more preferably aluminum or stainless steel, and even more preferably stainless steel.

[0017] When the laminate includes a base layer (A) and a base layer (F), the base layer (A) and base layer (F) constituting the laminate may each consist of only one layer or two or more layers. If there are two or more base layer (A) or two or more base layer (F) layers, for example, the base layer (A) or base layer (F) may be laminated with a base material such as the aluminum mentioned above. For example, when the laminate includes two base layer (A) and one base layer (F), the laminated structure of the laminate may be base layer (A1) / base layer (A2) / crosslinked polyester resin (B) / base layer (F), or base layer (A1) / crosslinked polyester resin (B) / base layer (A1) / crosslinked polyester resin (B) / base layer (F). When the laminate includes two or more base layer (A) layers, the base layer (A) included in the laminate may all be made of the same material, all be made of different materials, or some may be made of the same material and some of the materials may be different. If the laminate contains two or more base material layers (A), the base material layers (A) may be bonded together using a crosslinked polyester resin (B), or they may be bonded together using an adhesive other than a crosslinked polyester resin (B). If the laminate contains two or more base material layers (F), the base material layers (F) included in the laminate may all be made of the same material, all be made of different materials, or some be made of the same material and some be made of different materials. If the laminate contains two or more base material layers (F), the base material layers (F) may be bonded together using a crosslinked polyester resin (B), or they may be bonded together using an adhesive other than a crosslinked polyester resin (B).

[0018] When the laminate includes a base layer (A) and a base layer (F), the base layers (A) and (F) may be made of the same material or of different materials.

[0019] The thickness of the base layer (A) and base layer (F) is not particularly limited, but is preferably 25 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more. The upper limit of the thickness of the base layer (A) and base layer (F) is also not particularly limited, but may be, for example, 5 mm or less, or 4 mm or less. That is, the thickness of the base layer (A) and base layer (F) may be, for example, 25 μm to 5 mm, 50 μm to 4 mm, or 100 μm to 4 mm. When the laminate includes base layer (A) and base layer (F), the thicknesses of base layer (A) and base layer (F) may be the same or different, but it is preferable that they be the same.

[0020] The surface roughness (Ra) of the base layer (A) and base layer (F) is not particularly limited, but is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. Furthermore, the surface roughness (Ra) of the base layer (A) and base layer (F) is practically preferably 0.01 μm or more, more preferably 0.03 μm or more, and even more preferably 0.05 μm or more. That is, the surface roughness (Ra) of the base layer (A) and base layer (F) may be 0.01 μm to 5 μm, 0.03 μm to 4 μm, or 0.05 μm to 3 μm. When the surface roughness (Ra) of the base layer (A) and base layer (F) is within the above range, the interlayer adhesion between base layer (A) or base layer (F) and the crosslinked polyester resin layer (B) is good. Furthermore, the surface roughness (Ra) of the base layer (A) is sufficient if at least the surface roughness (Ra) of the surface of the base layer (A) that is in contact with the crosslinked polyester resin layer (B) satisfies the above range. The surface roughness (Ra) of the base layer (F) is sufficient if at least the surface roughness (Ra) of the surface of the base layer (F) that is in contact with the crosslinked polyester resin layer (B) satisfies the above range.

[0021] <Crosslinked polyester resin layer (B)> The crosslinked polyester resin layer (B) is a layer containing a crosslinked polyester resin (b), which is a reaction product of a polyester resin (C) having carboxyl groups in its side chains and an epoxy compound (D), and a transesterification catalyst (E).

[0022] The crosslinked polyester resin layer (B) may contain additives in addition to the polyester resin (C) having carboxyl groups in its side chains, the epoxy compound (D), the crosslinked polyester resin (b), and the transesterification catalyst (E). Examples of these additives include fillers and flame retardants.

[0023] <Crosslinked polyester resin (b)> Crosslinked polyester resin (b) is a reaction product of a polyester resin (C) having carboxyl groups in its side chains and an epoxy compound (D).

[0024] The stress relaxation initiation temperature of the crosslinked polyester resin (b) is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher. The upper limit of the stress relaxation initiation temperature of the crosslinked polyester resin (b) is not particularly limited, but industrially it may be 300°C or lower, and may also be 250°C or lower. That is, the stress relaxation initiation temperature of the crosslinked polyester resin (b) may be 100 to 300°C, 110 to 250°C, or 120 to 250°C.

[0025] <Polyester resin having carboxyl groups in the side chain (C)> Polyester resin having carboxyl groups in the side chain (C) is a resin having carboxyl groups in the side chain of a polyester resin. Here, having carboxyl groups in the side chain means that the carboxyl groups may be directly bonded to the main chain of the polyester resin, or the carboxyl groups may be directly bonded to substituents (e.g., aliphatic hydrocarbon groups, aromatic hydrocarbon groups, alicyclic hydrocarbon groups, etc.) that are directly bonded to the main chain of the polyester resin. Preferably, the carboxyl groups are directly bonded to the main chain of the polyester resin.

[0026] The number-average molecular weight (Mn) of the polyester resin (C) having carboxyl groups in its side chains is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 12,000 or more. Furthermore, the number-average molecular weight (Mn) of the polyester resin (C) having carboxyl groups in its side chains is preferably 50,000 or less, more preferably 25,000 or less, and even more preferably 20,000 or less. That is, the number-average molecular weight (Mn) of the polyester resin (C) having carboxyl groups in its side chains may be 5,000 to 50,000, 10,000 to 25,000, or 12,000 to 20,000. By setting the number-average molecular weight (Mn) of the polyester resin (C) having carboxyl groups in its side chains within the above range, it becomes easier to control the acid value of the polyester resin (C) having carboxyl groups in its side chains.

[0027] The acid value of the polyester resin (C) having carboxyl groups in its side chains is preferably 5 mg KOH / g or higher, and more preferably 10 mg KOH / g or higher. Furthermore, the acid value of the polyester resin (C) having carboxyl groups in its side chains is preferably 40 mg KOH / g or lower, and more preferably 30 mg KOH / g or lower. That is, the acid value of the polyester resin (C) having carboxyl groups in its side chains may be 5 to 40 mg KOH / g, or 10 to 30 mg KOH / g. If the acid value is above the lower limit, crosslinking with the epoxy compound (D) proceeds sufficiently, and the heat resistance of the crosslinked polyester resin layer (B) is improved. If the acid value is below the upper limit, the movement of the molecules themselves is not suppressed by an appropriate crosslinking density, making ester bond exchange easier, resulting in sufficient stress relaxation and softening, and good adhesion between the crosslinked polyester resin layer (B) and the substrate layer (A), etc. The polyester resin (C) having carboxyl groups in its side chains preferably contains ester bonds and carboxyl groups at multiple points within the molecule.

[0028] The glass transition temperature of the polyester resin (C) having carboxyl groups in its side chains is preferably 0°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher. The upper limit of the glass transition temperature of the polyester resin (C) having carboxyl groups in its side chains is not particularly limited and may be, for example, 80°C or lower, 50°C or lower, or 30°C or lower. That is, the glass transition temperature of the polyester resin (C) having carboxyl groups in its side chains may be, for example, 0 to 80°C, 5 to 50°C, or 10 to 30°C.

[0029] A polyester resin (C) having carboxyl groups in its side chains must have side chains (hereinafter also referred to as a branched structure) within its molecule. For a polyester resin (C) having carboxyl groups in its side chains to have a branched structure, it is preferable that the copolymer component used as its raw material has a branched structure. A polyester resin (C) having carboxyl groups in its side chains is preferably obtained by reacting (copolymerizing) a high molecular weight polyol (a) with a polycarboxylic acid component of trivalent or higher to impart carboxyl groups, but it may also be obtained by adding a monomer having carboxyl groups to a polyester having reaction sites obtained by the reaction of a polycarboxylic acid component and a polyalcohol component. A polycarboxylic acid is a compound having two or more carboxyl groups (-COOH) in one molecule, and is sometimes called a polyhydric carboxylic acid. A polyalcohol is a compound having two or more hydroxyl groups (-OH) in one molecule, and is sometimes called a polyhydric alcohol.

[0030] <Polymer Polyol (a)> The number average molecular weight of polymer polyol (a) is preferably 1000 or more, more preferably 2000 or more, and even more preferably 3000 or more. Furthermore, the number average molecular weight of polymer polyol (a) is preferably 30000 or less, more preferably 25000 or less, and even more preferably 20000 or less. That is, the number average molecular weight of polymer polyol (a) may be, for example, 1000 to 30000, 2000 to 25000, or 3000 to 20000.

[0031] The acid value of polymer polyol (a) is preferably 0.1 mg KOH / g or higher, more preferably 0.2 mg KOH / g or higher, and even more preferably 0.3 mg KOH / g or higher. Furthermore, the acid value of polymer polyol (a) is preferably 20 mg KOH / g or less, more preferably 15 mg KOH / g or less, and even more preferably 10 mg KOH / g or less. That is, the acid value of polymer polyol (a) may be, for example, 0.1 to 20 mg KOH / g, 0.2 to 15 mg KOH / g, or 0.3 to 10 mg KOH / g.

[0032] The glass transition temperature of polymer polyol (a) is preferably -10°C or higher, more preferably 0°C or higher, and even more preferably 5°C or higher. Furthermore, the glass transition temperature of polymer polyol (a) is preferably 100°C or lower, more preferably 80°C or lower, and even more preferably 60°C or lower. That is, the glass transition temperature of polymer polyol (a) may be, for example, -10 to 100°C, 0 to 80°C, or 5 to 60°C.

[0033] The polymer polyol (a) is preferably a copolymer of a polycarboxylic acid component and a polyalcohol component (polymer polyester polyol). The polycarboxylic acid component used in the polymer polyester polyol is preferably an aromatic dicarboxylic acid component, from the viewpoint of increasing the cohesive strength of the resin and improving its strength. Other polycarboxylic acid components other than aromatic dicarboxylic acids may also be used.

[0034] The aromatic dicarboxylic acid component is not particularly limited, and examples include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and diphenic acid. Also, examples include aromatic dicarboxylic acids having a sulfonic acid group, such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5-(4-sulfophenoxy)isophthalic acid, as well as aromatic dicarboxylic acids having a sulfonic acid base, such as metal salts or ammonium salts thereof. These can be used individually or in combination of two or more. Among the aromatic dicarboxylic acid components used in polymer polyester polyols, terephthalic acid, isophthalic acid, and mixtures thereof are particularly preferred.

[0035] Other polycarboxylic acid components include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and their acid anhydrides; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid; and unsaturated bond-containing dicarboxylic acids such as fumaric acid, maleic acid and their acid anhydrides. In addition, thiomalic acid, which has a thiol group in its molecular structure, and biomass-derived 2,5-franzicarboxylic acid (FDCA) can also be used as other polycarboxylic acid components.

[0036] The polyalcohol component used in polymeric polyester polyols is preferably a glycol component. Preferred glycol components include aliphatic glycols, alicyclic glycols, aromatic glycols, or ether bond-containing glycols. Examples of aliphatic glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 2-methyl-1,3-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, neopentyl glycol hydroxypivalate, dimethylolheptane, and 2,2,4-trimethyl-1,3-pentanediol. Examples of alicyclic glycols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethylol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A, and dimergol. Examples of aromatic glycols include paraxylene glycol, metaxylene glycol, orthoxylene glycol, p-hydroxyphenethyl alcohol, 1,4-phenylene glycol, ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, ethylene oxide adducts and propylene oxide adducts of bisphenol A, and glycols obtained by adding 1 to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols. Examples of ether bond-containing glycols include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, neopentyl glycol ethylene oxide adduct, and neopentyl glycol propylene oxide adduct.Furthermore, glycol-modified aromatic dicarboxylic acids can also be used. Specific examples include bis-2-hydroxyethyl terephthalate (BHET), an ethylene glycol-modified terephthalic acid; propylene glycol-modified terephthalic acid; ethylene glycol-modified isophthalic acid; propylene glycol-modified isophthalic acid; ethylene glycol-modified orthophthalic acid; and propylene glycol-modified orthophthalic acid. Other examples of glycol-modified aromatic dicarboxylic acids include naphthalenedicarboxylic acid, biphenyldicarboxylic acid, diphenic acid, 5-hydroxyisophthalic acid, sulfoterephthalic acid, 5-sulfisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, sulfoterephthalic acid, and / or glycol-modified aromatic dicarboxylic acids having sulfonic acid groups or sulfonic acid bases, such as their metal salts and ammonium salts. These can be used individually or in combination of two or more. For high-molecular-weight polyester polyols, aliphatic glycols are preferred as the polyalcohol component.

[0037] High-molecular-weight polyester polyols may contain a trifunctional or higher polycarboxylic acid component or a trifunctional or higher polyalcohol component, and may also contain other components other than a trifunctional or higher polycarboxylic acid component or a trifunctional or higher polyalcohol component.

[0038] Examples of polycarboxylic acid components with three or more functions used in high-molecular-weight polyester polyols include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic acid dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic acid dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA). These can be used individually or in combination of two or more.

[0039] On the other hand, examples of polyalcohol components with three or more functions used in high-molecular-weight polyester polyols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. These can be used individually or in combination of two or more.

[0040] Other components that can be used in polymeric polyester polyols include oxycarboxylic acid compounds having hydroxyl and carboxyl groups in their molecular structure, such as 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis(p-hydroxyphenyl)valeric acid. These can be used individually or in combination of two or more.

[0041] The polymer polyol (a) may contain two or more components of polymer polyols having different number average molecular weights (Mn). When the polymer polyol (a) contains two or more components of polymer polyols having different number average molecular weights (Mn), the polymer polyol (a) may have a structure containing two or more components of polymer polyols including a long-chain polymer polyol (a1) having a number average molecular weight (Mn) of 7,000 or more and a short-chain polymer polyol (a2) having a number average molecular weight (Mn) of 1,000 or more and less than 7,000. The upper limit of the number average molecular weight (Mn) of the long-chain polymer polyol (a1) is not particularly limited, but may be, for example, 20,000 or less. That is, the number average molecular weight (Mn) of the long-chain polymer polyol (a1) may be 7,000 to 20,000. The number average molecular weight (Mn) of the long-chain polymer polyol (a1) may be, for example, 10,000 to 18,000. The number average molecular weight (Mn) of the short-chain polymer polyol (a2) may be, for example, 2,000 to 5,000. By adopting the above structure, it is possible to further improve the heat resistance. That is, while the long-chain molecules of the long-chain polymer polyol (a1) block contribute to the heat resistance, by introducing the short-chain polymer polyol (a2) block, an amount of carboxylic acid sufficient for imparting heat resistance can be introduced.

[0042] In the polyester resin (C) having carboxyl groups in its side chains, the copolymerization ratio of polymer polyol (a1) and polymer polyol (a2) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, of the total of polymer polyol (a1) and polymer polyol (a2) per 100 parts by mass of polymer polyol (a1) and polymer polyol (a2). Furthermore, in the polyester resin (C) having carboxyl groups in its side chains, the copolymerization ratio of polymer polyol (a1) and polymer polyol (a2) is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, of the total of polymer polyol (a1) and polymer polyol (a2) per 100 parts by mass of polymer polyol (a1) and polymer polyol (a2). That is, per 100 parts by mass of the total of polymer polyol (a1) and polymer polyol (a2), polymer polyol (a2) may be 5 to 50 parts by mass, 10 to 40 parts by mass, or 20 to 30 parts by mass of polymer polyol (a2). By setting the copolymerization ratio of polymer polyol (a1) and polymer polyol (a2) within the above range, heat resistance can be further improved.

[0043] In the polyester resin (C) having carboxyl groups in its side chains, the copolymerization amount of the polymer polyol (a1) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Furthermore, in the polyester resin (C) having carboxyl groups in its side chains, the copolymerization amount of the polymer polyol (a1) is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. That is, in the polyester resin (C) having carboxyl groups in its side chains, the copolymerization amount of the polymer polyol (a1) may be, for example, 50 to 90% by mass, 60 to 85% by mass, or 70 to 80% by mass. When the copolymerization amount of the polymer polyol (a1) is within the above range, good heat resistance and adhesion are achieved through a balance with the copolymerization amount of the polymer polyol (a2) and the trivalent or higher polycarboxylic acid component.

[0044] When the polymer polyol (a) contains a long-chain polymer polyol (a1) and a short-chain polymer polyol (a2), the acid value of the long-chain polymer polyol (a1) may be, for example, 1 to 20 mgKOH / g, may be 2 to 15 mgKOH / g, or may be 3 to 10 mgKOH / g. When the polymer polyol (a) contains a long-chain polymer polyol (a1) and a short-chain polymer polyol (a2), the acid value of the short-chain polymer polyol (a2) may be, for example, 0.1 to 10 mgKOH / g, may be 0.2 to 8 mgKOH / g, or may be 0.3 to 5 mgKOH / g.

[0045] When the polymer polyol (a) contains a long-chain polymer polyol (a1) and a short-chain polymer polyol (a2), the glass transition temperature of the long-chain polymer polyol (a1) may be, for example, -10 to 60°C, may be -5 to 30°C, or may be 0 to 15°C. When the polymer polyol (a) contains a long-chain polymer polyol (a1) and a short-chain polymer polyol (a2), the glass transition temperature of the short-chain polymer polyol (a2) may be, for example, 5 to 100°C, may be 20 to 90°C, or may be 30 to 80°C.

[0046] <Trivalent or higher polycarboxylic acid components> The trivalent or higher polycarboxylic acid component to be reacted (copolymerized) with the high molecular weight polyol (a) is not particularly limited as long as it is a compound having three or more carboxyl groups in its molecule. The carboxyl groups may also form acid anhydride groups within the molecule, in which case one acid anhydride group is counted as two carboxyl groups. Examples of polycarboxylic acid components with a valency of 3 or higher include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic acid dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic acid dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA). These can be used individually or in combination of two or more. Among these, trimellitic anhydride or pyromellitic anhydride is preferred.

[0047] In the polyester resin (C) having carboxyl groups in its side chains, the copolymerization ratio of the high polymer polyol (a) to the trivalent or higher polycarboxylic acid component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, of the trivalent or higher polycarboxylic acid component per 100 parts by mass of the high polymer polyol (a). Furthermore, in the polyester resin (C) having carboxyl groups in its side chains, the copolymerization ratio of the high polymer polyol (a) to the trivalent or higher polycarboxylic acid component is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, of the trivalent or higher polycarboxylic acid component per 100 parts by mass of the high polymer polyol (a). That is, in the polyester resin (C) having carboxyl groups in its side chains, the copolymerization ratio of the high polymer polyol (a) to the trivalent or higher polycarboxylic acid component may be 0.5 to 10 parts by mass, 1 to 8 parts by mass, or 2 to 5 parts by mass, of the trivalent or higher polycarboxylic acid component per 100 parts by mass of the high polymer polyol (a). When the copolymerization ratio of trivalent or higher polycarboxylic acid components is above the aforementioned lower limit, the amount of crosslinking becomes sufficient, improving heat resistance. Conversely, when the copolymerization ratio of trivalent or higher polycarboxylic acid components is below the aforementioned upper limit, the crosslinking density does not become too high, ester bond exchange occurs easily, softening is sufficient, and adhesion is improved.

[0048] <Chain extender> In addition to high-molecular-weight polyols (a) (high-molecular-weight polyol (a1), high-molecular-weight polyol (a2)) and polycarboxylic acid components of trivalent or higher, a chain extender may be optionally used as a copolymer component in the polyester resin (C) containing carboxyl groups in its side chains, as long as it does not impair the effects described above. By using a chain extender, the acid value can be efficiently imparted to the polyester resin (C) containing carboxyl groups in its side chains.

[0049] The chain extender is preferably a low molecular weight diol with a molecular weight of 1000 or less, such as 2,2-dimethyl-1,3-propanediol or dimethylolbutanoic acid. These can be used alone or in combination of two or more. Among these, 2,2-dimethyl-1,3-propanediol is preferred as the chain extender from the viewpoint of solubility and compatibility.

[0050] When a chain extender is used, the copolymerization amount is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of polymer polyol (a). Furthermore, when a chain extender is used, the copolymerization amount is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of polymer polyol (a). That is, when a chain extender is used, the copolymerization amount may be 0.1 to 5 parts by mass, 0.5 to 4 parts by mass, or 1 to 3 parts by mass, per 100 parts by mass of polymer polyol (a). If the copolymerization amount is too high, phenomena such as difficulty in increasing the molecular weight and clouding of the varnish due to reactions between chain extenders may occur.

[0051] The polyester resin (C) having a carboxyl group in its side chain may use imidazole compounds, tertiary amines, phenols, octic acid, or amine salts such as quaternary tetraphenylborate salts, or quaternary ammonium salts as reaction catalysts, to the extent that the above-mentioned effects are not impaired. For example, imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, or 1-cyanoethyl-2-ethyl-4-methylimidazole; triethylamine, triethylenediamine, N'-methyl-N-(2-dimethylaminoethyl)piperazine, N,N-diisopropylethylamine, N,N-dimethylaminopyridine, 1,8-diazabicyclo(5,4,0)-undecene-7, 1,5-diazabicyclo(4,3,0)-nonene-5, or 6-dibutylamino-1 Examples include tertiary amines such as ,8-diazabicyclo(5,4,0)-undecene-7 and compounds obtained by salting these tertiary amines with phenol, octic acid, or quaternized tetraphenyl borate salts; and quaternary ammonium salts such as tetramethylammonium bromide, tetraethylammonium bromide, tetra-n-butylammonium bromide, tetramethylammonium chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tetramethylammonium hydroxide, trimethylbenzylammonium hydroxide, and tetra-n-butylammonium hydroxide. These may be used individually or in combination of two or more. Among these, it is preferable to use tertiary amines and compounds obtained by salting tertiary amines with phenol, octic acid, or quaternized tetraphenyl borate salts, more preferably tertiary amines, and even more preferably triethylamine.

[0052] <Epoxy Compound (D)> The epoxy compound (D) is not particularly limited as long as it reacts with the carboxyl group of the polyester resin (C) having a carboxyl group in its side chain to form a bond. Preferably, the epoxy compound (D) is a compound having two or more epoxy groups in its molecule. By using a compound having two or more epoxy groups in its molecule, the cured coating film obtained from the crosslinked polyester resin composition can easily form three-dimensional crosslinks, and its heat resistance can be improved.

[0053] Examples of epoxy compounds (D) include diol diglycidyl ethers, epoxyamine compounds having two or more epoxy groups and two or more tertiary amino groups in the molecule, and compounds having two or more epoxy groups and one tertiary amino group in the molecule. Among these, diol diglycidyl ethers are preferred.

[0054] Examples of diol diglycidyl ethers include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and aliphatic diol diglycidyl ethers such as 1,6-hexanediol diglycidyl ether. Among these, 1,4-butanediol diglycidyl ether is preferred.

[0055] Examples of epoxyamine compounds having two or more epoxy groups and two or more tertiary amino groups in the molecule include compounds having two diglycidylamino groups and a benzene ring, such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 4,4'-methylenebis(N,N-diglycidylaniline). A commercially available product of N,N,N',N'-tetraglycidyl-m-xylylenediamine is, for example, "TETRAD-X" (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc. 4,4'-methylenebis(N,N-diglycidylaniline) can be obtained, for example, from Tokyo Chemical Industry Co., Ltd. (TCI). Among these, N,N,N',N'-tetraglycidyl-m-xylylenediamine is preferred.

[0056] Examples of compounds having two or more epoxy groups and one tertiary amino group in their molecule include triglycidyl para-aminophenol [also known as N,N-diglycidyl-4-(glycidyloxy)aniline], which has one diglycidylamino group, a glycidyloxy group, and a benzene ring, and N,N-diglycidylaniline, which has one diglycidylamino group and a benzene ring. A commercially available product of triglycidyl para-aminophenol is, for example, "JER630" (trade name) manufactured by Mitsubishi Chemical Corporation. A commercially available product of N,N-diglycidylaniline is, for example, "GAN" (trade name) manufactured by Nippon Kayaku Co., Ltd.

[0057] The epoxy compound (D) may be used alone or in combination of two or more types.

[0058] The number-average molecular weight (Mn) of the epoxy compound (D) is preferably 100 to 500, and more preferably 150 to 400, from the viewpoint of the crosslinking density of the crosslinked polyester resin.

[0059] The blending ratio of epoxy compound (D) is preferably 25 to 75 moles, and more preferably 40 to 60 moles, per 100 moles of carboxyl groups in the polyester resin (C) having carboxyl groups in its side chains. By having a blending ratio of epoxy compound (D) within the above range, the crosslinking density becomes appropriate, and stress relaxation can be achieved in the crosslinked polyester resin layer.

[0060] The ratio of epoxy groups in epoxy compound (D) to carboxyl groups in polyester resin (C) having carboxyl groups in its side chains (carboxyl groups:epoxy groups) is preferably 100:50 to 100:150 (moles), and more preferably 100:80 to 100:120 (moles).

[0061] The content of epoxy compound (D) per 100 moles of carboxyl groups in the polyester resin (C) having carboxyl groups in its side chains is preferably 25 to 75 moles, more preferably 40 to 70 moles, and even more preferably 45 to 65 moles. By having the content of epoxy compound (D) per 100 moles of carboxyl groups in the polyester resin (C) having carboxyl groups in its side chains within the above range, a laminate with excellent storage stability and interlayer adhesion can be obtained.

[0062] <Transesterification Catalyst (E)> Transesterification catalyst (E) is a transesterification catalyst for ester groups in the crosslinked polyester resin (b). With the transesterification catalyst (E), the crosslinked polyester resin layer (B) of this disclosure undergoes "dynamic" covalent crosslinking that allows for bond exchange at high temperatures, resulting in high strength at room temperature and adhesion to the substrate layer and resin layer above the ester bond exchange activation temperature.

[0063] Examples of transesterification catalysts (E) include zinc acetate, triphenylphosphine, 1,5,7-triazabicyclo[4.4.0]deca-5-ene, and 1,8-diazabicyclo[5.4.0]undecene-7, with zinc acetate being preferred.

[0064] The blending ratio of the transesterification catalyst (E) is preferably 10 to 40 moles, and more preferably 10 to 30 moles, per 100 moles of carboxyl groups in the side chain of the polyester resin (C) having carboxyl groups in its side chains.

[0065] One example of a method for producing crosslinked polyester resin (b) is to heat a mixture of a polyester resin (C) having carboxyl groups in its side chains and an epoxy compound (D), and carry out a crosslinking reaction via an epoxy ring-opening reaction. The reaction between the polyester resin (C) having carboxyl groups in its side chains and the epoxy compound (D) may be carried out without a solvent or in the presence of an organic solvent. The organic solvent is not particularly limited as long as it does not react with the polyester resin (C) having carboxyl groups in its side chains, the epoxy compound (D), and the crosslinked polyester resin (b). Examples include aromatic organic solvents such as toluene and xylene, aliphatic organic solvents such as heptane and octane, ketone solvents such as methyl ethyl ketone, ether solvents such as tetrahydrofuran and diethyl ether, and amide solvents such as dimethylformamide and N-methylpyrrolidone. These may be used individually or in combination of two or more.

[0066] The reaction temperature is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher. Furthermore, the reaction temperature is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. In other words, the reaction temperature may be between 80 and 200°C, between 100 and 180°C, or between 120 and 160°C.

[0067] The reaction time depends on the reaction temperature, but is preferably 30 minutes or more, more preferably 1 hour or more, and even more preferably 2 hours or more. The reaction time is also preferably 10 hours or less, more preferably 8 hours or less, and even more preferably 5 hours or less. In other words, the reaction time may be 30 minutes to 10 hours, 1 to 8 hours, or 2 to 5 hours.

[0068] The crosslinked polyester resin layer (B) can be produced by heating a solution containing a polyester resin (C) having carboxyl groups in its side chains, an epoxy compound (D), and a transesterification catalyst (E). One example of a method for producing the crosslinked polyester resin layer (B) is to prepare a solution containing a polyester resin (C) having carboxyl groups in its side chains, a solution containing a transesterification catalyst (E), and a solution containing an epoxy compound (D), mix these solutions, and heat the resulting mixture to carry out a crosslinking reaction via an epoxy ring-opening reaction.

[0069] <Resin Layer (G)> The resin layer (G) is a layer containing polyimide resin and / or polyester resin. The amount of polyimide resin contained in the resin layer (G) may be 80% by mass or more, 90% by mass or more, or 100% by mass, when the mass of the resin layer (G) is taken as 100% by mass. The amount of polyester resin contained in the resin layer (G) may be 80% by mass or more, 90% by mass or more, or 100% by mass, when the mass of the resin layer (G) is taken as 100% by mass. If the resin layer (G) contains both polyimide resin and polyester resin, the total amount of polyimide resin and polyester resin may be 80% by mass or more, 90% by mass or more, or 100% by mass, when the mass of the resin layer (G) is taken as 100% by mass. If the resin layer (G) contains both polyimide resin and polyester resin, the mass ratio of polyimide resin to polyester resin may be 10:90 to 90:10, 30:70 to 70:30, or 40:60 to 60:40.

[0070] The resin layer (G) may contain additives in addition to polyimide resin and / or polyester resin. Examples of such additives include fillers and flame retardants.

[0071] This application claims the benefit of priority based on Japanese Patent Application No. 2024-188604, filed on 25 October 2024. The entire contents of the specification of the above Japanese Patent Application No. 2024-188604 are incorporated herein by reference.

[0072] The contents of this disclosure will be explained in more detail below with reference to examples, but the contents of this disclosure are not limited by the examples below, and it is of course possible to implement modifications to the extent that are in line with the spirit described above and below, and all such modifications are included in the technical scope of this disclosure.

[0073] <Polymerization Example of High-Molecular-Weight Polyol (a1-1)> In a reaction vessel equipped with a stirrer, thermometer, and distillation condenser, 30 moles of terephthalic acid, 69 moles of isophthalic acid, and 1 mole of trimellitic anhydride were added as polycarboxylic acid components, 15 moles of 2-methyl-1,3-butanediol and 85 moles of 1,6-hexanediol as polyalcohol components, and 0.2 moles of tetrabutyl titanate were added. The temperature was gradually increased to 250°C, and the esterification reaction was carried out while removing the distilled water from the system. After the esterification reaction was completed, initial polymerization was carried out while gradually reducing the pressure to 10 mmHg and raising the temperature to 250°C, and then late polymerization was carried out at a pressure of 1 mmHg or less until the desired torque was reached. After that, the pressure was returned to atmospheric pressure with nitrogen, and 1 mole of trimellitic anhydride was added as a polycarboxylic acid component with three or more functions, and the reaction was carried out at 220°C for 30 minutes to obtain a long-chain high-molecular-weight polyol (a1). The obtained long-chain polymer polyol (a1) will be referred to as polymer polyol (a1-1) below. The composition and physical properties of polymer polyol (a1-1) are shown in Table 1.

[0074] <Polymerization Example of High-Molecular-Weight Polyol (a1-2)> In a reaction vessel equipped with a stirrer, thermometer, and distillation cooler, 50 moles of terephthalic acid and 50 moles of isophthalic acid were added as polycarboxylic acid components, 55 moles of ethylene glycol and 45 moles of 2,2-dimethyl-1,3-propanediol as polyalcohol components, and 0.2 moles of tetrabutyl titanate were added. The temperature was gradually raised to 250°C, and the esterification reaction was carried out while removing the distilled water from the system. After the esterification reaction was completed, initial polymerization was carried out while gradually reducing the pressure to 10 mmHg and raising the temperature to 250°C, and then late polymerization was carried out at a pressure of 1 mmHg or less until a predetermined torque was reached, thereby obtaining short-chain high-molecular-weight polyol (a2). The obtained short-chain high-molecular-weight polyol (a2) will be referred to as high-molecular-weight polyol (a1-2) below. The composition and physical properties of high-molecular-weight polyol (a1-2) are shown in Table 1.

[0075]

[0076] <Example of Synthesis of Polyester Resin (C-1) Having Carboxy Groups in Side Chains> In a reaction vessel equipped with a stirrer, thermometer, and reflux tubing, 80 parts by mass of high-molecular-weight polyol (a1-1), 20 parts by mass of high-molecular-weight polyol (a1-2), 2.6 parts by mass of pyromellitic anhydride, and 100 parts by mass of toluene were charged and dissolved while gradually raising the temperature to 80°C. After dissolution, 0.05 parts by mass of triethylamine was added as a reaction catalyst, and the temperature was gradually raised to 105°C and the reaction was carried out for 24 hours. After confirming the completion of the reaction by infrared spectroscopy (IR), 54 parts by mass of toluene was added to dilute the solution, thereby obtaining a solution of polyester resin (C-1) having carboxyl groups in side chains with a solid content of 40%. The composition and characteristic values ​​of the polyester resin (C-1) having carboxyl groups in side chains obtained in this way are shown in Table 2.

[0077]

[0078] For the polymeric polyols (a1-1) and (a1-2) shown in Table 1, and the polyester resin (C-1) with carboxyl groups in its side chains shown in Table 2, the number-average molecular weight (Mn), weight-average molecular weight (Mw), acid value, and glass transition temperature were measured using the following procedure. Furthermore, the molecular weight dispersion (PDI) was calculated based on the measured number-average molecular weight (Mn) and weight-average molecular weight (Mw).

[0079] <Number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight dispersion (PDI)> Samples (high-molecular-weight polyols (a1-1), high-molecular-weight polyols (a1-2), or polyester resins having carboxyl groups in the side chains (C-1)) were dissolved or diluted in tetrahydrofuran to a sample concentration of approximately 0.5% by mass, and filtered through a polytetrafluoroethylene membrane filter with a pore size of 0.5 μm to be used as the measurement sample. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the samples were measured by gel permeation chromatography using tetrahydrofuran as the mobile phase and a differential refractometer as the detector. The flow rate was 1 mL / min and the column temperature was 30°C. Showa Denko KF-802, KF-804L, and KF-806L columns were used. Monodisperse polystyrene was used as the standard substance (molecular weight standard). Low molecular weight compounds (oligomers, etc.) with a number-average molecular weight (Mn) of less than 1000 were not counted and were omitted. Based on the measured number-average molecular weight (Mn) and weight-average molecular weight (Mw), the molecular weight dispersion (PDI) of the sample was calculated using the following formula: PDI value = Mw / Mn

[0080] <Acid Value> 0.2 g of the sample (high molecular weight polyol (a1-1), high molecular weight polyol (a1-2), or polyester resin having a carboxyl group in the side chain (C-1)) was dissolved in 20 ml of chloroform. Phenolphthalein was added to this solution as an indicator, and neutralization titration was performed with a 0.1 N potassium hydroxide ethanol solution. From the titration volume, the amount of potassium hydroxide consumed in neutralization (mg KOH) was converted to the amount per gram of aromatic polyester resin to calculate the acid value of the sample (mg KOH / g).

[0081] <Glass Transition Temperature> Using a differential scanning calorimetry analyzer "DSC220" manufactured by Seiko Electronics Industries, Ltd., 5 mg of the sample (polymeric polyol (a1-1), polymeric polyol (a1-2), or polyester resin (C-1) having carboxyl groups in its side chains) was placed in an aluminum pan, sealed by pressing down on the lid, held at 250°C for 5 minutes, then rapidly cooled with liquid nitrogen, and subsequently heated from -100°C to 300°C at a heating rate of 20°C / min, and the amount of heat was measured. The inflection point of the obtained curve was defined as the glass transition temperature of the sample.

[0082] Next, a crosslinked polyester resin (b) was produced using the obtained polyester resin (C-1) having carboxyl groups in its side chains, an epoxy compound (D), and a transesterification catalyst (E). The epoxy compound (D) used was 1,4-butanediol diglycidyl ether (BDE, "Epogose® BD(D)" manufactured by Yokkaichi Synthetic Co., Ltd.). Its molecular weight is 202.25. The transesterification catalyst (E) was zinc acetate (Zn(OAc)). ２ ) was used.

[0083] <Example 1> (1) Production of the crosslinked polyester resin layer (B-1) A polyester resin having carboxyl groups in its side chains (C) was used as the polyester resin having carboxyl groups in its side chains (C), 1,4-butanediol diglycidyl ether was used as the epoxy compound (D), and zinc acetate was used as the transesterification catalyst (E). Based on 100 moles of the polyester resin having carboxyl groups in its side chains (C-1), each material was blended in the proportions shown in Table 3. The blending order was as follows: First, two solutions were prepared: one in which the polyester resin having carboxyl groups in its side chains (C-1) was dissolved in a mixed solvent of methyl ethyl ketone and toluene, and the other in which zinc acetate, the transesterification catalyst (E), was dissolved in N,N-dimethylformamide. These two solutions were then mixed with the epoxy compound (D), 1,4-butanediol diglycidyl ether, and heated to react, thereby producing the crosslinked polyester resin layer (B-1). The reaction temperature was 140°C and the reaction time was 3 hours. The dry film thickness of the obtained crosslinked polyester resin layer (B-1) was 25 μm. Since 1,4-butanediol diglycidyl ether has two epoxy groups, the epoxy groups in epoxy compound (D) amount to 50 × 2 = 100 moles, and the ratio of epoxy groups in epoxy compound (D) to carboxyl groups in polyester resin (C) having carboxyl groups in its side chain (carboxyl groups: epoxy groups) is 100:100.

[0084] (2) Preparation of the laminate Next, cross-linked polyester resin layer (B-1) was used as the cross-linked polyester resin layer (B), steel was used as the base layer (A), and steel was used as the base layer (F). The cross-linked polyester resin layer (B-1) was bonded together so that base layer (A) was in contact with one side of the cross-linked polyester resin layer (B-1), and base layer (F) was in contact with the other side of the cross-linked polyester resin layer (B-1). The bonded layers were heated at 170°C at 20 kgf / cm². ２ The substrate layer (A), the crosslinked polyester resin layer (B-1), and the substrate layer (F) were bonded together in this order by pressing under pressure of (1.96 MPa) for 5 minutes to obtain a laminate.

[0085] <Examples 2-3, Comparative Examples 1-3> Similar to Example 1, 100 moles of polyester resin (C-1) having carboxyl groups in the side chain were used as a base, and the laminates of Examples 2-3 and Comparative Examples 1-3 were prepared by changing each material as shown in Table 3.

[0086] In Comparative Example 1, steel was used as the base layer (A) and base layer (F). In Example 2 and Comparative Example 2, stainless steel was used as the base layer (A) and base layer (F). In Example 3 and Comparative Example 3, aluminum was used as the base layer (A) and base layer (F). The steel used in Example 1 and Comparative Example 1 was GI steel sheet (hot-dip galvanized steel sheet). The stainless steel used in Example 2 and Comparative Example 2 was SUS (SUS304). The aluminum used in Example 3 and Comparative Example 3 was aluminum alloy (A6061). The thickness of the steel, stainless steel, and aluminum was 2 mm. The surface roughness (Ra) of the steel was 0.14 μm, the surface roughness (Ra) of the stainless steel was 0.13 μm, and the surface roughness (Ra) of the aluminum was 0.43 μm. The surface roughness (Ra) was measured using a surface roughness measuring instrument "HANDYSURF" manufactured by Tokyo Seimitsu Co., Ltd.

[0087] The tensile shear adhesive strength of each of the laminates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was measured using the following procedure.

[0088] <Tensile Shear Bond Strength (Interlaminar Adhesion)> Tensile shear bond strength was measured by conducting a tensile test at 25°C at a tensile speed of 10 mm / min in a direction parallel to the bonded surface, and measuring the tensile shear stress. The tensile shear bond strength was defined as the value obtained by dividing the maximum point load at which the bonded joint broke by the bonded area. This test indicates the bond strength at room temperature. A Tensilon universal material testing machine manufactured by A&D Co., Ltd. was used to measure the tensile shear bond strength. The results are shown in Table 3.

[0089]

[0090] As is clear from Table 3, in Examples 1 to 3, the base material layer (A) and base material layer (F) and the crosslinked polyester resin layer (B) are well bonded. Furthermore, since washing with solvents or water is not required in the production of the crosslinked polyester resin layer (B), storage stability is good. In Comparative Examples 1 to 3, the adhesion between the base material layer (A) and base material layer (F) and the crosslinked polyester resin layer (B) was insufficient, making it impossible to create a laminate and evaluate its performance. This is thought to be because in Comparative Examples 1 to 3, the crosslinked polyester resin layer (B) did not have a transesterification catalyst (E) and did not exhibit stress relaxation properties, resulting in insufficient adhesion to the base material layer (A) and base material layer (F) at the temperature during laminate creation.

[0091] The laminate of this disclosure exhibits excellent interlayer adhesion between the layers constituting the laminate, making it useful in a variety of applications such as building materials, electrical and electronic components, and automotive parts.

[0092] 1. Base layer (A) 2. Crosslinked polyester resin layer (B) 3. Base layer (F) or resin layer (G)

Claims

1. A laminate comprising a base layer (A) and a crosslinked polyester resin layer (B) in that order, wherein the base layer (A) is a layer containing at least one selected from the group consisting of aluminum, steel, stainless steel, copper, and glass, and the crosslinked polyester resin layer (B) is a layer containing a crosslinked polyester resin (b) which is a reaction product of a polyester resin (C) having carboxyl groups in its side chains and an epoxy compound (D), and a transesterification catalyst (E).

2. The laminate according to claim 1, comprising a base layer (F) or resin layer (G) provided on the side of the crosslinked polyester resin layer (B) opposite to the base layer (A), wherein the base layer (F) is a layer containing at least one selected from the group consisting of aluminum, steel, stainless steel, copper, and glass, and the resin layer (G) is a layer containing polyimide resin and / or polyester resin.

3. The laminate according to claim 1 or 2, wherein the acid value of the polyester resin (C) having a carboxyl group in the side chain is 5 to 40 mgKOH / g.

4. The laminate according to claim 1 or 2, comprising 10 to 40 moles of the transesterification catalyst (E) per 100 moles of carboxyl groups of the polyester resin (C) having carboxyl groups in its side chains.

5. The laminate according to claim 1 or 2, comprising 50 to 150 moles of the epoxy compound (D) per 100 moles of carboxyl groups of the polyester resin (C) having carboxyl groups in its side chains.

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