Adhesive film for bonding to draw-formed base material, adhesive layer, laminate for draw forming, and draw-formed body

Abstract

Provided is an adhesive film in which an adhesive layer is laminated on a resin film, wherein the adhesive film is easily stretchable and resistant to breakage during draw forming, has an adhesive layer that is unlikely to be separated from an adherend, and is used by being bonded to a draw-formed base material. Also provided is an adhesive layer which is laminated on a resin film used to serve as the adhesive film, wherein the adhesive layer is easily stretchable and resistant to breakage during draw forming and is unlikely to be separated from an adherend.　The present invention is an adhesive film for bonding to a draw-formed base material, in which an adhesive layer is laminated on a resin film, wherein the adhesive layer contains: a crosslinked polyester resin (C) having a structure in which a side-chain carboxy group of a polyester resin (A) having a carboxy group in a side chain is crosslinked with an epoxy-based crosslinking agent (B) having a plurality of epoxy groups within a molecule; and a transesterification catalyst (D).

Description

Adhesive film for laminating draw-molded substrates, adhesive layer, draw-molded laminate, and draw-molded product

[0001] The present invention relates to an adhesive film to be used by laminating it to a die-molding substrate, an adhesive layer to be laminated on a resin film used to make the adhesive film, a die-molding laminate in which the adhesive film and a die-molding substrate are laminated together, and a die-molded product obtained from the die-molding laminate.

[0002] A known method for protecting and decorating the surfaces of automobile interior and exterior parts, home appliance parts, building materials, etc. involves applying a paint to the surface of the part, drying it, and then heating it to harden it. However, the paint used for painting contains volatile organic solvents, which poses a problem of volatile organic solvent emissions.

[0003] Besides painting, vacuum forming is another known method for decorating the surface of a molded body. Vacuum forming is a lamination method in which a decorative film is heated and softened while being stretched, the space on the adherend side of the decorative film is depressurized, and, if necessary, the space on the opposite side of the decorative film from the adherend side is pressurized, thereby forming and bonding the decorative film to a molded body molded into a three-dimensional shape. A decorative film used in such vacuum forming is disclosed in Patent Document 1, and a cured adhesive used in vacuum forming is disclosed in Patent Document 2.

[0004] Patent No. 5708153 Patent No. 7081214

[0005] In vacuum forming, the formation of the adherend and the lamination of the decorative film are carried out separately, making it difficult to position the decorative film relative to the formed body. Furthermore, vacuum forming requires the adherend to be strong enough to prevent deformation or warping even when high pressure is applied during molding, which limits its scope of application. Therefore, if the decorative film is bonded to the adherend and then the adherend is drawn, the position of the decorative film relative to the adherend can be accurately determined before molding, which is thought to facilitate proper positioning. However, when drawing is performed after laminating the decorative film to the substrate, deformation of the substrate usually causes the adhesive to break, resulting in the decorative film peeling from the substrate, or the decorative film's deformation does not match the deformation of the substrate, causing wrinkles in the decorative film. Therefore, forming the decorative film while maintaining its position presents a significant technical hurdle.

[0006] An object of the present invention is to provide an adhesive film in which an adhesive layer is laminated on a resin film, the adhesive layer being easily stretched and resistant to breakage during drawing, but not easily separated from the adherend, and being used by being stuck to a draw-molded substrate. Another object of the present invention is to provide an adhesive layer laminated on a resin film used to make the above adhesive film, the adhesive layer being easily stretched and resistant to breakage during drawing, but not easily separated from the adherend. Another object of the present invention is to provide a laminate in which a resin film is stuck to a draw-molded substrate via an adhesive layer, the laminate having good adhesion between the draw-molded substrate and the resin film, and the resin film not easily peeling off from the draw-molded substrate even after drawing, and a draw-molded product obtained from the laminate.

[0007] The present invention is as follows. [1] An adhesive film for laminating draw-molded substrates, comprising a resin film and an adhesive layer laminated thereon, the adhesive layer comprising a crosslinked polyester resin (C) having a structure in which a side-chain carboxy group of a polyester resin (A) having a side-chain carboxy group is crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and an ester exchange catalyst (D). [2] The adhesive film according to [1], wherein the epoxy-based crosslinking agent (B) contains an aliphatic epoxy compound. [3] The adhesive film according to [1] or [2], wherein the epoxy-based crosslinking agent (B) contains an epoxy amine compound further having a tertiary amino group in the molecule. [4] The adhesive film according to [3], wherein the epoxy amine compound has one or more epoxidized amino groups formed by bonding the tertiary amino group to the epoxy group via an alkylene group having 1 to 4 carbon atoms. [5] The adhesive film according to any one of [1] to [4], which contains 30 to 60 molar parts of the epoxy-based crosslinking agent (B) per 100 molar parts of the carboxy groups of the polyester resin (A). [6] The adhesive film according to any one of [1] to [5], which contains 1 to 70 molar parts of the transesterification catalyst (D) per 100 molar parts of the carboxy groups of the polyester resin (A). [7] The adhesive film according to any one of [1] to [6], in which the polyester resin (A) is obtained by reacting a polymer polyol (a) obtained by reacting a polycarboxylic acid component with a polyhydric alcohol component with a trifunctional or higher polycarboxylic acid component to provide carboxy groups. [8] The adhesive film according to [7], in which the polymer polyol (a) contains two or more polymer polyol components having different number average molecular weights (Mn). [9] An adhesive layer used for laminating a resin film to form an adhesive film for bonding a squeeze-molded substrate, the adhesive layer comprising: a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups in the side chain are crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule; and a transesterification catalyst (D).

[10] The adhesive layer according to [9], wherein the stress at 100% elongation in the longitudinal direction at both 170°C and 250°C is 1 MPa or less, the stress at 200% elongation in the longitudinal direction at both 170°C and 250°C is 1 MPa or less, and the elongation at break at both 170°C and 250°C is 100% or more and 1200% or less.

[11] The adhesive layer according to [9] or

[10] , wherein the polyester resin (A) is a polymer polyol (a) obtained by reacting a polycarboxylic acid component with a polyhydric alcohol component, and the polymer polyol (a) is reacted with a trifunctional or higher polycarboxylic acid component to provide carboxy groups.

[12] The adhesive layer according to

[11] , wherein the polymer polyol (a) contains two or more polymer polyol components having different number-average molecular weights (Mn).

[13] A laminate for die-forming, comprising a die-forming substrate and the adhesive film according to any one of [1] to [8] bonded together.

[14] A draw-formed body obtained from the draw-forming laminate according to

[13] .

[0008] According to the present invention, it is possible to provide an adhesive layer that is easily stretched and resistant to breakage during drawing, and an adhesive film having the adhesive layer and used by being attached to a drawing substrate. Furthermore, according to the present invention, it is possible to provide a laminate in which a drawing substrate and a resin film are attached via the adhesive layer, and this laminate has good adhesion between the drawing substrate and the resin film, and the resin film is not easily peeled off from the drawing substrate even after drawing. Furthermore, according to the present invention, it is possible to provide a draw-formed product obtained from the laminate, and this draw-formed product has good designability because the resin film does not peel off.

[0009] The adhesive film according to the present invention is a film in which an adhesive layer is laminated on a resin film and is used by bonding it to a drawing-molded substrate. The adhesive layer is characterized by containing a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups at its side chains are crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and an ester exchange catalyst (D). By crosslinking the side chain carboxy groups of the polyester resin (A) with the epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, both high crosslink density and high high-temperature fluidity can be achieved in the presence of the ester exchange catalyst (D). As a result, an adhesive layer that is easy to stretch during drawing and is resistant to breakage can be achieved. By bonding an adhesive film having this adhesive layer to a drawing-molded substrate, the adhesion between the drawing-molded substrate and the resin film is improved, and the resin film is less likely to peel from the drawing-molded substrate even during drawing. The present invention will now be described.

[0010] (A) Polyester Resin Having Carboxy Group in Side Chain The polyester resin (A) has a carboxy group in the side chain (hereinafter also referred to as a branched structure) of the polyester resin. The polyester resin (A) also has an ester bond in the molecule. The structure of the polyester resin (A) having a carboxy group in the side chain [hereinafter sometimes simply referred to as polyester resin (A)] may be a structure in which a carboxy group is in a substituent (e.g., an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, etc.) branched from the main chain of the polyester resin, or a structure in which a carboxy group is directly in the main chain of the polyester resin, with a structure in which a carboxy group is directly in the main chain of the polyester resin being preferred.

[0011] The number average molecular weight (Mn) of the polyester resin (A) is preferably, for example, 5,000 to 50,000. When the number average molecular weight (Mn) of the polyester resin (A) is within the above range, it becomes easier to control the acid value of the polyester resin (A). The number average molecular weight (Mn) of the polyester resin (A) is more preferably 10,000 to 25,000, and even more preferably 12,000 to 20,000.

[0012] The acid value of the polyester resin (A) is preferably, for example, 5 to 40 mgKOH / g. When the acid value of the polyester resin (A) is 5 mgKOH / g or more, crosslinking with the epoxy-based crosslinking agent (B) proceeds sufficiently, improving the heat resistance of the adhesive layer. When the acid value of the polyester resin (A) is 40 mgKOH / g or less, the crosslinking density is optimized, and ester bond exchange occurs easily without suppressing the movement of the molecules themselves, resulting in sufficient stress relaxation and softening, resulting in good adhesion. The acid value of the polyester resin (A) is more preferably 7 to 30 mgKOH / g, and even more preferably 10 to 20 mgKOH / g.

[0013] The glass transition temperature of the polyester resin (A) is, for example, preferably 0 to 110°C, more preferably 5 to 85°C, still more preferably 10 to 65°C, and particularly preferably 10 to 45°C.

[0014] In order for the polyester resin (A) to have a branched structure and a side chain, the copolymerization component serving as the raw material thereof may have a branched structure.

[0015] The polyester resin (A) can be produced by the reaction of a polycarboxylic acid component with a polyhydric alcohol component, and may be obtained by adding a monomer having a carboxy group to a polyester having a reactive site obtained by the reaction of a polycarboxylic acid component with a polyhydric alcohol component. However, it is preferable that the polyester resin (A) is obtained by the reaction of a polycarboxylic acid component with a polyhydric alcohol component, and is reacted (copolymerized) with a trifunctional or higher polycarboxylic acid component to impart a carboxy group.

[0016] (a) Polymer Polyol The polymer polyol (a) may be a polymer of a polycarboxylic acid component and a polyhydric alcohol component (polymer polyester polyol). The polymer polyol (a) may also contain a tri- or higher functional polycarboxylic acid component or a tri- or higher functional polyhydric alcohol component.

[0017] (Polycarboxylic Acid Component) The polycarboxylic acid component used in the polymer polyol (a) may be an aromatic dicarboxylic acid component and / or a polycarboxylic acid component other than an aromatic dicarboxylic acid component, and it is preferable to use at least an aromatic dicarboxylic acid component.

[0018] The polycarboxylic acid component used in the polymer polyol (a) is preferably an aromatic dicarboxylic acid component from the viewpoint of increasing the cohesive force of the resin and improving its strength. Examples of aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and diphenic acid. Sulfonate group-containing aromatic dicarboxylic acids 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 sulfonate salt groups such as their metal salts and ammonium salts, may also be used. These may be used alone or in combination of two or more. Among these, terephthalic acid, isophthalic acid, and mixtures thereof are preferred.

[0019] Examples of polycarboxylic acid components other than aromatic dicarboxylic acid components include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and their anhydrides; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid; unsaturated bond-containing dicarboxylic acids such as fumaric acid, maleic acid, and their anhydrides; thiomalic acid having a thiol group in its molecular structure; and biomass-derived 2,5-furandicarboxylic acid (FDCA). These may be used alone or in combination of two or more.

[0020] (Polyhydric Alcohol Component) The polyhydric alcohol component used in the polymer polyol (a) is preferably a glycol component. Examples of the glycol component include aliphatic glycols, alicyclic glycols, aromatic group-containing glycols, and ether bond-containing glycols.

[0021] 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 (DMH), hydroxypivalic acid neopentyl glycol ester, dimethylol heptane, and 2,2,4-trimethyl-1,3-pentanediol.

[0022] 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 dimer diol.

[0023] Examples of aromatic-containing glycols include glycols obtained by adding 1 to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols such as paraxylene glycol, metaxylene glycol, orthoxylene glycol, p-hydroxyphenethyl alcohol, 1,4-phenylene glycol, an ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct thereof. Glycol-modified aromatic dicarboxylic acids may also be used, and specific examples include bis-2-hydroxyethyl terephthalate (BHET), which is an ethylene glycol-modified product of terephthalic acid, a propylene glycol-modified product of terephthalic acid, an ethylene glycol-modified product of isophthalic acid, a propylene glycol-modified product of isophthalic acid, an ethylene glycol-modified product of orthophthalic acid, and a propylene glycol-modified product of orthophthalic acid. Other examples of glycol-modified aromatic dicarboxylic acids include glycol-modified aromatic dicarboxylic acids having a sulfonic acid group or a sulfonate salt group, such as naphthalenedicarboxylic acid, biphenyldicarboxylic acid, diphenic acid, 5-hydroxyisophthalic acid, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, sulfoterephthalic acid, and / or metal salts or ammonium salts thereof.

[0024] 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.

[0025] These may be used alone or in combination of two or more. Among these, aliphatic glycols are preferred, and ethylene glycol, 2-methyl-1,3-butanediol, 2,2-dimethyl-1,3-propanediol, and 1,6-hexanediol are more preferred.

[0026] (Trifunctional or higher polycarboxylic acid component) Examples of trifunctional or higher polycarboxylic acid components used in the polymer polyol (a) include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA) and the like. These may be used alone or in combination of two or more. Of these, trimellitic anhydride is preferred.

[0027] (Trifunctional or higher polyhydric alcohol component) Examples of trifunctional or higher polyhydric alcohol components used in the polymer polyol (a) include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. These may be used alone or in combination of two or more.

[0028] The polymer polyol (a) may contain, as other components, oxycarboxylic acid compounds having a hydroxyl group and a carboxyl group in the 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.

[0029] The number average molecular weight (Mn) of the high molecular weight polyol (a) is, for example, preferably 1,000 to 30,000, more preferably 2,000 to 25,000, and even more preferably 3,000 to 20,000.

[0030] The polymer polyol (a) may contain two or more polymer polyols having different number-average molecular weights (Mn). When the polymer polyol (a) contains two or more polymer polyols having different number-average molecular weights (Mn), it may contain 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 but less than 7,000. By including two or more polymer polyols having different number-average molecular weights (Mn), the heat resistance of the adhesive layer can be improved. For example, the long-chain molecules of the long-chain polymer polyol (a1) block contribute to heat resistance, while the introduction of the short-chain polymer polyol (a2) block can introduce a sufficient amount of carboxylic acid to impart heat resistance. 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.

[0031] When the polymer polyol (a) contains a long-chain polymer polyol (a1) and a short-chain polymer polyol (a2), the polymerization ratio of the long-chain polymer polyol (a1) to the short-chain polymer polyol (a2) is preferably 5 to 50 parts by mass of the short-chain polymer polyol (a2) relative to 100 parts by mass of the long-chain polymer polyol (a1) and the short-chain polymer polyol (a2). By having the polymerization ratio of the long-chain polymer polyol (a1) to the short-chain polymer polyol (a2) within the above range, the heat resistance of the adhesive layer can be improved. The amount of the short-chain polymer polyol (a2) is more preferably 10 to 40 parts by mass, and even more preferably 20 to 30 parts by mass, relative to 100 parts by mass of the long-chain polymer polyol (a1) and the short-chain polymer polyol (a2).

[0032] When the polymer polyol (a) contains a long-chain polymer polyol (a1) and a short-chain polymer polyol (a2), the polymerization amount of the long-chain polymer polyol (a1) is preferably 50 to 90% by mass when the polymer polyol (a) is taken as 100% by mass. When the polymerization amount of the long-chain polymer polyol (a1) in the polymer polyol (a) is within the above range, the heat resistance and adhesion of the adhesive layer are improved due to the balance with the polymerization amount of the short-chain polymer polyol (a2) and the trifunctional or higher polycarboxylic acid component. The polymerization amount of the long-chain polymer polyol (a1) is more preferably 60 to 85% by mass, and even more preferably 70 to 80% by mass when the polymer polyol (a) is taken as 100% by mass.

[0033] (Trifunctional or higher polycarboxylic acid component) The trifunctional or higher polycarboxylic acid component to be reacted (polymerized) with the polymer polyol (a) is not particularly limited as long as it is a compound having three or more carboxy groups in the molecule. The carboxy groups may form acid anhydride groups in the molecule, and in this case, one acid anhydride group is counted as two carboxy groups.

[0034] Examples of trifunctional or higher polyvalent carboxylic acid components include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA). These may be used alone or in combination of two or more. Of these, pyromellitic anhydride is preferred.

[0035] The ratio of the tri- or higher functional polycarboxylic acid component in the adhesive layer may be 0.1 to 3 molar parts, more preferably 0.3 to 2 molar parts, and even more preferably 0.5 to 1.5 molar parts, of the tri- or higher functional polycarboxylic acid component relative to 100 molar parts of the polyester resin (A).

[0036] The polymerization ratio of the high molecular weight polyol (a) to the tri- or higher functional polycarboxylic acid component in the polyester resin (A) is preferably 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 5 parts by mass, of the tri- or higher functional polycarboxylic acid component per 100 parts by mass of the high molecular weight polyol (a). When the polymerization ratio of the tri- or higher functional polycarboxylic acid component is equal to or greater than the lower limit, the amount of crosslinking is sufficient, and the heat resistance of the adhesive layer is improved. When the polymerization ratio of the tri- or higher functional polycarboxylic acid component is equal to or less than the upper limit, the crosslink density is not too high, ester bond exchange is likely to occur, and softening is sufficient, resulting in improved adhesion.

[0037] The acid value of the high molecular weight polyol (a) is, for example, preferably from 0.1 to 20 mgKOH / g, more preferably from 0.2 to 15 mgKOH / g, and even more preferably from 0.3 to 10 mgKOH / g.

[0038] 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) is, for example, preferably 1 to 20 mgKOH / g, more preferably 2 to 15 mgKOH / g, and even more preferably 3 to 10 mgKOH / g. The acid value of the short-chain polymer polyol (a2) is, for example, preferably 0.1 to 10 mgKOH / g, more preferably 0.2 to 8 mgKOH / g, and even more preferably 0.3 to 5 mgKOH / g.

[0039] The glass transition temperature of the polymer polyol (a) is, for example, preferably from -10 to 100°C, more preferably from 0 to 80°C, and even more preferably from 5 to 60°C.

[0040] 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) is, for example, preferably −10 to 60° C., more preferably −5 to 30° C., and even more preferably 0 to 15° C. The glass transition temperature of the short-chain polymer polyol (a2) is, for example, preferably 5 to 100° C., more preferably 20 to 90° C., and even more preferably 30 to 80° C.

[0041] (Reaction Catalyst) In producing the polyester resin (A), a reaction catalyst may be used within a range that does not impair the above-mentioned effects. Examples of the reaction catalyst include imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 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, and 6-dibutylamine. Examples of suitable amine salts include tertiary amines such as 1,8-dimethylamino-1,8-diazabicyclo(5,4,0)-undecene-7, and compounds prepared by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate, and the like; 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 alone or in combination of two or more. Among these, it is preferable to use tertiary amines and compounds prepared by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate, and the like, with triethylamine being more preferred.

[0042] (B) Epoxy-based Crosslinking Agent The epoxy-based crosslinking agent (B) is an epoxy compound having multiple epoxy groups in the molecule. That is, the epoxy compound is a compound having two or more epoxy groups in the molecule. The epoxy compound may contain oxygen atoms and sulfur atoms in the molecule as necessary.

[0043] The use of an epoxy compound facilitates the formation of three-dimensional crosslinks, thereby improving the heat resistance of the adhesive layer. Furthermore, by crosslinking the side chain carboxyl groups of the polyester resin (A) with an epoxy compound, both high crosslink density and high high-temperature fluidity can be achieved in the presence of the transesterification catalyst (D). As a result, an adhesive layer that is easy to stretch during drawing and resistant to breakage can be realized while maintaining heat resistance.

[0044] The number of epoxy groups contained in the molecule of the epoxy compound is preferably 2 to 4, more preferably 2 or 3, and even more preferably 2.

[0045] The epoxy compound may be an aliphatic epoxy compound. The aliphatic epoxy compound is a compound composed of an aliphatic saturated hydrocarbon group and an epoxy group, and may contain oxygen atoms or sulfur atoms in the molecule as needed. Examples of the aliphatic epoxy compound include compounds in which multiple epoxy group-containing groups are bonded to an aliphatic saturated hydrocarbon group via oxygen atoms or sulfur atoms. Examples of the epoxy group-containing group include an epoxy group and a glycidyl group.

[0046] Examples of epoxy compounds include polytetramethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A diglycidyl ether, and bisphenol S diglycidyl ether. These may be used alone or in combination of two or more. Of these, 1,4-butanediol diglycidyl ether is preferred.

[0047] The epoxy crosslinking agent (B) may be an epoxy amine compound having multiple epoxy groups in the molecule and further having a tertiary amino group. That is, among epoxy compounds having multiple epoxy groups in the molecule, an epoxy amine compound having multiple epoxy groups and one or more tertiary amino groups in the molecule may be used as the epoxy crosslinking agent (B). The epoxy amine compound may contain an oxygen atom or a sulfur atom in the molecule as necessary.

[0048] By crosslinking the side chain carboxyl groups of the polyester resin (A) with an epoxy amine compound, in the presence of a transesterification catalyst (D), it is possible to achieve both high crosslink density and high high-temperature fluidity. As a result, it is possible to realize an adhesive layer that is easy to stretch during drawing and is resistant to rupture while maintaining heat resistance. In addition, the tertiary amino group of the epoxy amine compound, like the transesterification catalyst (D), has a transesterification catalytic action. By heating the adhesive layer, the hydroxyl groups contained in the adhesive layer attack the C=O bonds of the ester groups present near the hydroxyl groups through the action of the tertiary amino group, causing bond exchange through a transesterification reaction, thereby exhibiting stress relaxation behavior.

[0049] The number of epoxy groups contained in the molecule of the epoxy amine compound is preferably 2 to 4, and more preferably 3 or 4. The number of tertiary amino groups contained in the molecule of the epoxy amine compound may be 2 or more, and is preferably 3 or less.

[0050] The epoxy amine compound may have one or more epoxidized amino groups formed by bonding a tertiary amino group to an epoxy group via an alkylene group having 1 to 4 carbon atoms. The number of carbon atoms in the alkylene group bonding the tertiary amino group to the epoxy group is more preferably 3 or less, even more preferably 2 or less, and particularly preferably 1. The nitrogen atom of the tertiary amino group may have one epoxy group bonded to it via an alkylene group having 1 to 4 carbon atoms, or two epoxy groups bonded to it via alkylene groups having 1 to 4 carbon atoms, and a diepoxidized amino group having two epoxy groups bonded to it via an alkylene group having 1 to 4 carbon atoms is preferred.

[0051] The number of epoxidized amino groups contained in the molecule of the epoxy amine compound may be 2 or more, or 3 or more, or 5 or less, or 4 or less. That is, the number of epoxidized amino groups contained in the molecule of the epoxy amine compound may be 2 to 5, or may be 3 or 4. The number of diepoxidized amino groups contained in the molecule of the epoxy amine compound may be 1, 2, or 3, preferably 1 or 2, and more preferably 2, i.e., diglycidylamino groups.

[0052] The epoxy amine compound may have an aromatic ring, and a diepoxidized amino group may be bonded to the aromatic ring. The number of diepoxidized amino groups bonded to the aromatic ring may be one or two, and preferably three or less. When the epoxy amine compound has an aromatic ring, the diepoxidized amino group may be bonded to the aromatic ring via an alkylene group having 1 to 4 carbon atoms. The number of carbon atoms in the alkylene group bonding the aromatic ring and the diepoxidized amino group is more preferably three or less, even more preferably two or less, and particularly preferably one. When the epoxy amine compound has an aromatic ring, the number of aromatic rings may be one or two, and preferably three or less. When the epoxy amine compound has two or more aromatic rings, the aromatic rings may be bonded directly to each other, or two or more aromatic rings may be bonded via an alkylene group having 1 to 4 carbon atoms.

[0053] Examples of epoxyamine compounds include 4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline (hereinafter sometimes referred to as triglycidyl para-aminophenol), N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 4,4'-methylenebis(N,N-diglycidylaniline). These may be used alone or in combination of two or more. Of these, triglycidyl para-aminophenol is preferred.

[0054] As the epoxy-based crosslinking agent (B), an epoxy compound and an epoxy amine compound may be used either alone or in combination.

[0055] The ratio of the epoxy-based crosslinking agent (B) in the adhesive layer may be 30 to 60 molar parts of the epoxy-based crosslinking agent (B) per 100 molar parts of the carboxy groups of the polyester resin (A). By having the ratio of the epoxy-based crosslinking agent (B) in the adhesive layer within the above range, the crosslinking density becomes appropriate, and stress relaxation in the adhesive layer after crosslinking can be achieved. The ratio of the epoxy-based crosslinking agent (B) in the adhesive layer is more preferably 25 to 58 molar parts, and even more preferably 30 to 55 molar parts, per 100 molar parts of the carboxy groups of the polyester resin (A).

[0056] (C) Crosslinked Polyester Resin The crosslinked polyester resin (C) is a resin having a structure in which the side chain carboxy groups of the polyester resin (A) are crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and the side chain carboxy groups of the polyester resin (A) may be crosslinked with an epoxy compound having multiple epoxy groups in the molecule, or with an epoxy amine compound having multiple epoxy groups and one or more tertiary amino groups in the molecule, or with both an epoxy compound having multiple epoxy groups but no tertiary amino groups in the molecule and an epoxy amine compound having multiple epoxy groups and one or more tertiary amino groups in the molecule.

[0057] (D) Transesterification catalyst The transesterification catalyst (D) is a catalyst for transesterification of the ester group in the polyester resin (A).By containing the transesterification catalyst (D) in the adhesive layer, the crosslinked polyester resin (C) undergoes dynamic covalent crosslinking that allows bond exchange at high temperatures, which results in high strength at room temperature, and at or above the ester bond exchange activation temperature, adhesion to resin films and drawing-molded substrates is possible, and stress relaxation is also exhibited, making it easier for the deformation of the adhesive film (decorative film) to follow the deformation of the substrate during drawing.

[0058] Examples of the transesterification catalyst (D) include zinc acetate, zinc acetate anhydride, zinc(II) acetylacetonate, aluminum(III) acetylacetonate, triphenylphosphine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 1,8-diazabicyclo[5.4.0]undecene-7. These may be used alone or in combination of two or more. Of these, zinc acetate anhydride and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0059] The quantitative ratio of the transesterification catalyst (D) in the adhesive layer is preferably 1 to 70 molar parts of the transesterification catalyst (D) per 100 molar parts of the carboxy groups of the polyester resin (A). By having the quantitative ratio of the transesterification catalyst (D) in the adhesive layer within the above range, stress relaxation in the adhesive layer after crosslinking can be exhibited. The quantitative ratio of the transesterification catalyst (D) in the adhesive layer is more preferably 3 to 65 molar parts, and even more preferably 5 to 60 molar parts, per 100 molar parts of the carboxy groups of the polyester resin (A).

[0060] The adhesive layer can be produced by mixing a polyester resin (A) having a carboxy group in a side chain, an epoxy-based crosslinking agent (B), and an ester exchange catalyst (D), heating the mixture, and carrying out a crosslinking reaction via an epoxy ring-opening reaction. The heating temperature is, for example, preferably 80 to 200°C, more preferably 85 to 180°C, and even more preferably 90 to 150°C. The heating time varies depending on the heating temperature, but is, for example, preferably 30 minutes to 10 hours, more preferably 1 to 8 hours, and even more preferably 2 to 5 hours.

[0061] The reaction between the polyester resin (A) and the epoxy-based crosslinking agent (B) may be carried out in the absence of a solvent or in the presence of an organic solvent. When an organic solvent is used, the organic solvent is not particularly limited as long as it does not react with the polyester resin (A) and the epoxy-based crosslinking agent (B). Examples of the organic solvent include aromatic organic solvents such as toluene and xylene, aliphatic organic solvents such as heptane and octane, ketone-based solvents such as methyl ethyl ketone, ether-based solvents such as tetrahydrofuran and diethyl ether, and amide-based solvents such as dimethylformamide, N-methylpyrrolidone, and N,N-dimethylformamide. These may be used alone or in combination of two or more. Among these, aromatic organic solvents, ketone-based solvents, and amide-based solvents are preferred.

[0062] The quantitative ratio of the polyester resin (A) having a carboxy group in its side chain to the epoxy-based crosslinking agent (B) in the crosslinked polyester resin (C) can be determined based on the functional group molar ratio between the carboxy group in the side chain of the polyester resin (A) and the epoxy group of the epoxy-based crosslinking agent (B). From the viewpoints of crosslinking reaction efficiency and stress relaxation in the crosslinked polyester resin (C) after crosslinking, the ratio of the carboxy group in the polyester resin (A) to the epoxy group in the epoxy-based crosslinking agent (B) (carboxy group:epoxy group) is preferably 100:50 to 100:150 (mol parts), more preferably 100:80 to 100:120 (mol parts).

[0063] (Adhesive Film) The adhesive film is formed by laminating an adhesive layer containing a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups in its side chains are crosslinked with the above-mentioned epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and an ester exchange catalyst (D) on a resin film.

[0064] Examples of materials for the resin film include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, fluororesin, etc. Among these, polyester resin is preferred.

[0065] For example, adhesive films can be obtained by applying a coating liquid containing the epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, the polyester resin (A) having carboxyl groups in its side chains, and the transesterification catalyst (D) to a resin film and then drying the coating liquid, resulting in an adhesive film having an adhesive layer laminated on the surface of the resin film, according to a conventional method. Furthermore, after drying, attaching a release substrate to the adhesive layer allows for winding without causing offset onto the resin film, improving operability, and protecting the adhesive layer, resulting in excellent storage stability and ease of use. Examples of release substrates include those in which a coating layer of a filler such as clay, polyethylene, or polypropylene is applied to the surface (one or both sides) of paper such as fine paper, kraft paper, roll paper, or glassine paper, with a silicone-based, fluorine-based, or alkyd-based release agent further coated on the coating layer. Other examples include various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymers, and propylene-α-olefin copolymers, as well as films such as polyethylene terephthalate and polyethylene naphthalate, to which the release agent is applied.

[0066] The method for applying the coating liquid to the resin film is not particularly limited, and examples thereof include methods using a coating machine such as a comma coater, lip coater, die coater, or reverse roll coater.

[0067] (Adhesive Layer) The present invention also includes an adhesive layer that is laminated on a resin film to form an adhesive film for bonding a drawing-molded substrate. The adhesive layer contains a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having a carboxy group in its side chain are crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and a transesterification catalyst (D). The thickness of the adhesive layer can be appropriately changed as needed, but is preferably 0.01 to 0.8 mm, for example. By making the thickness of the adhesive layer 0.01 mm or more, sufficient adhesive strength can be obtained.

[0068] The adhesive layer preferably has a stress of 1 MPa or less at 170 ° C. and 250 ° C. when stretched 100% in the longitudinal direction. This makes it difficult for the resin film to peel off from the stretched substrate even when a laminate in which the stretched substrate and the resin film are bonded via the adhesive layer is stretched. The stress of the adhesive layer when stretched 100% in the longitudinal direction at 170 ° C. is more preferably 0.8 MPa or less, and even more preferably 0.5 MPa or less. The stress of the adhesive layer when stretched 100% in the longitudinal direction at 250 ° C. is more preferably 0.5 MPa or less, and even more preferably 0.3 MPa or less.

[0069] The adhesive layer preferably has a stress of 1 MPa or less when stretched 200% in the longitudinal direction at 170 ° C. and 250 ° C. As a result, even when a laminate in which a draw-molded substrate and a resin film are bonded together via the adhesive layer is draw-molded, the resin film is less likely to peel from the draw-molded substrate. The stress of the adhesive layer when stretched 200% in the longitudinal direction at 170 ° C. is more preferably 0.8 MPa or less, and even more preferably 0.5 MPa or less. The stress of the adhesive layer when stretched 200% in the longitudinal direction at 250 ° C. is more preferably 0.5 MPa or less, and even more preferably 0.3 MPa or less.

[0070] The adhesive layer preferably has a breaking elongation of 100% or more and 1200% or less at 170°C and 250°C. This makes it difficult for the resin film to peel from the drawing-molded substrate even when drawing is performed on a laminate in which the drawing-molded substrate and the resin film are bonded via the adhesive layer. The breaking elongation of the adhesive layer at 170°C is more preferably 110 to 1180%, and even more preferably 120 to 1150%. The breaking elongation of the adhesive layer at 250°C is more preferably 105 to 1180%, and even more preferably 110 to 1150% or less.

[0071] It is particularly preferred that the adhesive layer has a stress of 1 MPa or less when elongated by 100% in the longitudinal direction at both 170°C and 250°C, a stress of 1 MPa or less when elongated by 200% in the longitudinal direction at both 170°C and 250°C, and a breaking elongation of 100% or more and 1200% or less at 170°C and 250°C.

[0072] (Laminate) The present invention also encompasses a laminate in which the adhesive film and a drawing substrate are bonded together, and this laminate can be suitably used for deep drawing. The drawing laminate is a laminate in which a resin film, an adhesive layer, and a drawing substrate are laminated in this order. Examples of drawing substrates include metal substrates such as metal plates, and resin substrates such as film-like resins. Examples of materials for metal substrates include various metals such as SUS, copper, aluminum, iron, steel, zinc, and nickel, as well as their alloys, plated products, and metals treated with other metals such as zinc or chromium compounds. Examples of materials for resin substrates include polyester resins, polyamide resins, polyimide resins, polyamideimide resins, liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resins, and fluororesins. Among these, metal substrates are preferred from the viewpoint of adhesion strength and durability with the adhesive layer of the adhesive film, and SUS, copper, aluminum, etc. are more preferred.

[0073] The conditions for bonding the draw-molded substrate and the adhesive film are preferably such that the temperature is, for example, about 15° C. or more higher than the softening temperature of the adhesive layer, specifically, for example, 185° C. or higher.

[0074] (Draw-formed body) The present invention also includes a draw-formed body obtained from the draw-forming laminate. When the draw-forming laminate is draw-formed, the adhesive layer and the resin film deform in accordance with the deformation of the draw-forming base material, so that the draw-formed body does not have peeling or wrinkles of the resin film, and a draw-formed body with good design properties can be obtained.

[0075] This application claims the benefit of priority based on Japanese Patent Application No. 2024-23115, filed on February 19, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-23115 are incorporated herein by reference.

[0076] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is of course possible to carry out the invention by making modifications within the scope that is compatible with the above-mentioned and below-mentioned aims, and all such modifications are included in the technical scope of the present invention.

[0077] First, a long-chain high molecular weight polyol (a1) and a short-chain high molecular weight polyol (a2) were copolymerized with a tri- or higher functional polycarboxylic acid component to produce a polyester resin (A) having carboxy groups in the side chains.

[0078] (a1) Long-chain polymer polyol In a reactor equipped with a stirrer, thermometer, and distillation condenser, 30 mol parts of terephthalic acid, 69 mol parts of isophthalic acid, and 1 mol part of trimellitic anhydride were charged as polycarboxylic acid components, 15 mol parts of 2-methyl-1,3-butanediol, 85 mol parts of 1,6-hexanediol, and 0.2 mol parts of tetrabutyl titanate were charged, and the temperature was gradually raised to 250 ° C., and the distilled water was removed from the system while the esterification reaction was carried out. After the esterification reaction was completed, initial polymerization was carried out while gradually reducing the pressure to 10 mmHg, and the temperature was raised to 250 ° C., and further, post-polymerization was carried out until a predetermined torque was reached at 1 mmHg or less. Thereafter, the pressure was returned to normal pressure with nitrogen, and 1 mol part of trimellitic anhydride was added as a trifunctional or higher polycarboxylic acid component, and the reaction was carried out at 220 ° C. for 30 minutes to obtain a long-chain polymer polyol (a1-1). The composition of the resulting long-chain polymer polyol (a1-1) is shown in Table 1.

[0079] (a2) Short-chain polymer polyol A reactor equipped with a stirrer, thermometer, and distillation condenser was charged with 50 mol parts of terephthalic acid and 50 mol parts of isophthalic acid as polycarboxylic acid components, 55 mol parts of ethylene glycol and 45 mol parts of 2,2-dimethyl-1,3-propanediol as polyhydric alcohol components, and 0.2 mol parts of tetrabutyl titanate. The temperature was gradually raised to 250 ° C., and an 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 the temperature was raised to 250 ° C., and further, post-polymerization was carried out at 1 mmHg or less until a predetermined torque was reached, thereby obtaining a short-chain polymer polyol (a2-1). The composition of the resulting short-chain polymer polyol (a2-1) is shown in Table 1.

[0080] The number average molecular weight (Mn), acid value, and glass transition temperature of the obtained long-chain polymer polyol (a1-1) and short-chain polymer polyol (a2-1) were measured by the following procedure. These physical property values ​​are shown in Table 1.

[0081] (i) Number Average Molecular Weight (Mn) The obtained long-chain polymer polyol (a1-1) or short-chain polymer polyol (a2-1) was dissolved or diluted in tetrahydrofuran to a concentration of about 0.5% by mass, and filtered through a polytetrafluoroethylene membrane filter with a pore size of 0.5 μm to prepare a measurement sample. The number average molecular weight was 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. Monodisperse polystyrene was used as the molecular weight standard. The number average molecular weight was calculated excluding the portion corresponding to a molecular weight of less than 1,000.

[0082] (ii) Acid Value 0.2 g of the obtained long-chain polymer polyol (a1-1) or short-chain polymer polyol (a2-1) was dissolved in 20 ml of chloroform and subjected to neutralization titration with a 0.1 N potassium hydroxide (KOH) ethanol solution using phenolphthalein as an indicator. From the titration amount, the number of mg of KOH consumed for neutralization was converted into the amount per 1 g of long-chain polymer polyol (a1-1) or short-chain polymer polyol (a2-1) to calculate the acid value (mg KOH / g).

[0083] (iii) Glass Transition Temperature 5 mg of the obtained long-chain polymer polyol (a1-1) or short-chain polymer polyol (a2-1) was placed in an aluminum pan, the pan was sealed with a lid, and the resulting sample was used as a measurement sample. The sample was measured using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., by first holding the sample at 250°C for 5 minutes, then quenching with liquid nitrogen, and then heating from -100°C to 300°C at a heating rate of 20°C / min. The inflection point of the resulting curve was taken as the glass transition temperature.

[0084]

[0085] (A) Polyester Resin Having Carboxy Groups in the Side Chains In a reactor equipped with a stirrer, thermometer, and reflux condenser, 80 parts by mass of long-chain polymer polyol (a1-1), 20 parts by mass of short-chain polymer polyol (a2-1), 2.6 parts by mass of pyromellitic anhydride as a trifunctional or higher polycarboxylic acid component, and 100 parts by mass of toluene were charged and dissolved in toluene while gradually heating to 80 ° C. After dissolution was complete, 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 allowed to proceed 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 mixture, thereby obtaining a solution of polyester resin (A-1) containing carboxy groups in the side chains with a solids concentration of 40% by mass. The composition of the resulting polyester resin (A-1) containing carboxy groups in the side chains is shown in Table 2.

[0086]

[0087] Next, an adhesive layer was produced using the obtained polyester resin (A-1), an epoxy-based crosslinking agent (B), and an ester exchange catalyst (D).

[0088] The following compounds were used as the epoxy crosslinker (B). Epoxy compound (B-1): 1,4-butanediol diglycidyl ether (hereinafter sometimes referred to as BDE) was "Epogose® BD" manufactured by Yokkaichi Chemical Co., Ltd. 1,4-butanediol diglycidyl ether has two epoxy groups in the molecule. Epoxy amine compound (B-2): Mitsubishi Chemical Corporation's "jER630" was used as triglycidyl paraaminophenol. Triglycidyl paraaminophenol has three epoxy groups and one tertiary amino group in the molecule. Epoxy compound (B-3): Nippon Steel Chemical & Material's "YDCN-700-10" was used as a novolac epoxy resin. "YDCN-700-10" is a multifunctional epoxy with an epoxy equivalent of 198 to 210.

[0089] The following compounds were used as the transesterification catalyst (D): Transesterification catalyst (D-1): "Zinc acetate anhydrous (Zn(OAc)" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. ２ Transesterification catalyst (D-2): 1,5,7-triazabicyclo[4.4.0]dec-5-ene (hereinafter sometimes referred to as TBD) manufactured by Tokyo Chemical Industry Co., Ltd. was used.

[0090] Example 1 The amount (molar equivalent) of carboxy groups in polyester resin (A-1) and the amount (molar equivalent) of epoxy groups in epoxy compound (B-1) were dissolved in toluene to a specific ratio, preparing solution 1 with a solids content of 25.5% by mass. The amount of epoxy compound (B-1) was 50 molar parts per 100 molar parts of carboxy groups in polyester resin (A-1). A transesterification catalyst (D-1) was dissolved in N,N-dimethylformamide to prepare solution 2 with a solids content of 8.3% by mass. Solution 1 and solution 2 were mixed so that the amount (molar equivalent) of carboxy groups in polyester resin (A-1) and the amount (molar equivalent) of transesterification catalyst (D-1) were a specific ratio, producing coating solution 1 with a solids content of 20% by mass. The amount of transesterification catalyst (D-1) was 20 molar parts per 100 molar parts of carboxy groups in polyester resin (A-1).

[0091] Next, the obtained coating liquid 1 was applied to a resin film and dried to produce an adhesive film 1 consisting of a resin film and an adhesive layer 1. A PET film (G2000 manufactured by Toyobo, thickness 38 μm) that had been subjected to plasma treatment and corona treatment as surface treatment was used as the resin film, and the coating liquid 1 was applied to the surface of the PET film. The coating liquid 1 was applied using an applicator. The required amount of liquid was dropped onto the surface of the PET film, and then uniformly applied to the PET film surface using an applicator with a 200 μm gap. The PET film coated with the coating liquid 1 was heat-treated at 100°C for 3 hours to produce an adhesive film 1 consisting of a PET film and an adhesive layer 1. The dry film thickness of the adhesive layer 1 in the obtained adhesive film 1 was approximately 0.025 mm. The physical properties of the obtained adhesive layer 1 were evaluated.

[0092] The PET film was peeled off from the adhesive film 1, the adhesive layer 1 was removed, and a test piece measuring 250 mm in length x 10 mm in width was cut out from the adhesive layer 1 in the longitudinal direction. A tensile test was performed using a tensile tester (Tensilon universal testing machine manufactured by Orientec Co., Ltd.) with an initial tensile chuck distance of 20 mm and a tensile speed of 20 mm / min. The test piece was then pulled in the longitudinal direction to perform a tensile test. The tensile test was performed after placing the test piece in a thermostatic chamber set at 170 ° C. or 250 ° C. and preheating for 30 seconds. The load applied to the film when the test piece was elongated to 100% (i.e., when the chuck distance was 40 mm) and when the test piece was elongated to 200% (i.e., when the chuck distance was 60 mm), and the load applied to the film was read. The read load was divided by the cross-sectional area of ​​the test piece before the tensile test (film thickness x 10 mm) to calculate the stress at 100% elongation and the stress at 200% elongation, respectively.

[0093] The elongation at the time when the test piece broke was measured, and the breaking elongation was calculated based on the following formula: where Lo represents the length of the test piece before the test, and L represents the length of the test piece at the time when the test piece broke. Breaking elongation (%) = 100 × (L - Lo) / Lo

[0094] As a reference experiment, a tensile test was carried out at room temperature (25°C) without placing the test piece in a thermostatic chamber, and the stress at 100% elongation and the stress at 200% elongation were calculated.

[0095] Table 3 below shows the stress of adhesive layer 1 at 100% longitudinal elongation at 25°C, 170°C, or 250°C, the stress of adhesive layer 1 at 200% longitudinal elongation at 25°C, 170°C, or 250°C, and the breaking elongation of adhesive layer 1 at 170°C or 250°C.

[0096] Next, the adhesive film 1 and a drawing substrate were bonded together to produce a drawing laminate 1, and the adhesion between the PET film and the GA steel sheet and the drawing formability of the drawing laminate 1 were evaluated. That is, a galvannealed steel sheet (hereinafter sometimes referred to as a GA steel sheet) was used as the drawing substrate. The GA steel sheet was placed on the heating stage of a laminator and preheated at 185°C for 5 minutes, and then the laminator was operated to transport the GA steel sheet at a speed of 9.0 m / min. The adhesive film 1 was supplied to the GA steel sheet so that the galvannealed layer of the GA steel sheet and the adhesive layer 1 of the adhesive film 1 came into contact with each other. Utilizing the preheating of the GA steel sheet, the GA steel sheet was laminated at a lamination pressure of 3 bar. After passing through a laminator, the sheet was immersed in a water bath to cool, and a drawing laminate 1 was produced. The laminating machine used was an original machine base with a structure in which a heating stage for a steel plate and a laminating roll are connected in series. The laminate structure of the draw-forming laminate 1 is PET film / adhesive layer / GA steel plate.

[0097] The adhesion between the PET film and the GA steel sheet was evaluated for the resulting draw-forming laminate 1. The adhesion was evaluated by a peel test in which one end of the PET film was pulled while being folded back 180° along the surface of the draw-forming laminate 1, and the load at which the PET film peeled off was measured. The width of the test piece was 20 mm, and the pulling speed of the PET film was 100 mm / min. The adhesion was evaluated based on the measured load and using the following criteria. The evaluation results are shown in Table 3 below. (Evaluation Criteria) When the load per 20 mm width of the PET film was greater than 10 N, the adhesion was evaluated as particularly excellent, and this was indicated as A in Table 3. When the load per 20 mm width of the PET film was 5 to 10 N, the adhesion was evaluated as excellent, and this was indicated as B in Table 3. When the load per 20 mm width of the PET film was less than 5 N, the adhesion was evaluated as poor, and this was indicated as C in Table 3.

[0098] Next, the obtained draw-forming laminate 1 was draw-formed, and visual observation was made to see whether the PET film followed the deformation of the GA steel sheet, and the draw-formability of the draw-forming laminate 1 was evaluated. A hydraulic press "DPD-1500" manufactured by Kawasaki Hydro Engineering Co., Ltd. was used as the draw-forming machine. The draw-forming was performed at a press pressure of 100 tons, and the PET film or adhesive layer 1 was visually observed for cracks, lifting, and wrinkles, and evaluated according to the following criteria. The evaluation results are shown in Table 3 below. (Evaluation Criteria) When neither the PET film nor the adhesive layer 1 exhibited cracks, lifting, or wrinkles, the draw-formability was evaluated as being particularly excellent, and this was indicated as A in Table 3. When either the PET film or the adhesive layer 1 exhibited cracks, lifting, or wrinkles, the draw-formability was evaluated as being good, and this was indicated as B in Table 3. When two or more of cracks, lifting, and wrinkles were observed in either the PET film or the adhesive layer 1, the drawability was evaluated as poor, and this was indicated by C in Table 3.

[0099] Example 2 A draw-forming laminate 2 was produced under the same conditions as in Example 1, except that the temperature at which the GA steel sheet was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The resulting draw-forming laminate 2 was evaluated for adhesion between the PET film and the GA steel sheet, and draw formability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0100] Example 3 A draw-forming laminate 3 was produced under the same conditions as in Example 1, except that the temperature at which the GA steel sheet was preheated on the heating stage of the laminator was changed from 185°C to 230°C. The resulting draw-forming laminate 3 was evaluated for adhesion between the PET film and the GA steel sheet, and draw formability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0101] Example 4 A coating solution 4 was produced under the same conditions as in Example 1, except that instead of using 20 mol parts of the transesterification catalyst (D-1) per 100 mol parts of the carboxy groups of the polyester resin (A), 20 mol parts of the transesterification catalyst (D-2) were used. The resulting coating solution 4 was then applied to a resin film under the same conditions as in Example 1 and dried to produce an adhesive film 4 consisting of a resin film and an adhesive layer 4. The dry film thickness of the adhesive layer 4 in the resulting adhesive film 4 was approximately 0.353 mm. The physical properties of the resulting adhesive layer 4 were evaluated under the same conditions as in Example 1. A draw-forming laminate 4 was then produced under the same conditions as in Example 1, except that the temperature at which the GA steel sheet was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The resulting draw-forming laminate 4 was evaluated for adhesion between the PET film and the GA steel sheet, and for drawability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0102] Example 5 Coating liquid 5 was produced under the same conditions as in Example 1, except that 50 mol parts of transesterification catalyst (D-1) were used instead of 20 mol parts per 100 mol parts of carboxy groups in polyester resin (A). Next, the resulting coating liquid 5 was applied to a resin film under the same conditions as in Example 1 and dried to produce an adhesive film 5 consisting of a resin film and an adhesive layer 5. The dry film thickness of adhesive layer 5 in the resulting adhesive film 5 was approximately 0.017 mm. The physical properties of the resulting adhesive layer 5 were evaluated under the same conditions as in Example 1. Next, a draw-forming laminate 5 was produced under the same conditions as in Example 1, except that the temperature at which the GA steel sheet was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The resulting draw-forming laminate 5 was evaluated for adhesion between the PET film and the GA steel sheet, and for draw-formability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0103] Example 6 A coating solution 6 was produced under the same conditions as in Example 1, except that instead of using 50 mol parts of the epoxy compound (B-1) per 100 mol parts of the carboxy groups of the polyester resin (A), 33 mol parts of the epoxy amine compound (B-2) were used. The resulting coating solution 6 was then applied to a resin film under the same conditions as in Example 1 and dried to produce an adhesive film 6 consisting of a resin film and an adhesive layer 6. The dry thickness of the adhesive layer 6 in the resulting adhesive film 6 was approximately 0.487 mm. The physical properties of the resulting adhesive layer 6 were evaluated under the same conditions as in Example 1. A draw-forming laminate 6 was then produced under the same conditions as in Example 1, except that the temperature at which the GA steel sheet was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The resulting draw-forming laminate 6 was evaluated for adhesion between the PET film and the GA steel sheet, as well as for draw formability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0104] Example 7 Coating liquid 7 was produced under the same conditions as in Example 1, except that, per 100 mol parts of carboxy groups in the polyester resin (A), 47 mol parts of epoxy compound (B-1) were used instead of 50 mol parts, and 2 mol parts of epoxyamine compound (B-2) were used, and 10 mol parts of transesterification catalyst (D-1) were used instead of 20 mol parts. Next, the resulting coating liquid 7 was applied to a resin film under the same conditions as in Example 1 and dried to produce an adhesive film 7 consisting of a resin film and an adhesive layer 7. The physical properties of the resulting adhesive layer 7 were evaluated under the same conditions as in Example 1. Next, a draw-forming laminate 7 was produced under the same conditions as in Example 1, except that the temperature at which the GA steel sheet was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The resulting draw-forming laminate 7 was evaluated for adhesion between the PET film and the GA steel sheet, and for draw-formability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0105] Comparative Example 1 The amount (molar equivalent) of carboxy groups in polyester resin (A-1) and the amount (molar equivalent) of epoxy groups in epoxy compound (B-1) were dissolved in toluene to a specific ratio to prepare a solution 11 with a solids content of 25.5% by mass. The amount of epoxy compound (B-1) was 50 molar parts per 100 molar parts of carboxy groups in polyester resin (A-1). Next, the obtained solution 11 was applied to a resin film under the same conditions as in Example 1 and dried to produce an adhesive film 11 consisting of a resin film and an adhesive layer 11. The physical properties of the obtained adhesive layer 11 were evaluated under the same conditions as in Example 1. Next, a draw-forming laminate 11 was produced under the same conditions as in Example 1, except that the temperature at which the GA steel plate was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The obtained draw-forming laminate 11 was evaluated for adhesion between the PET film and the GA steel plate and draw formability under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0106] Comparative Example 2 The amount (molar equivalent) of carboxy groups in polyester resin (A-1) and the amount (molar equivalent) of epoxy groups in epoxy compound (B-3) (novolac epoxy resin) were dissolved in toluene to a specific ratio to prepare a solution 12 with a solids content of 25.5% by mass. The amount of novolac epoxy resin was 65 molar parts per 100 molar parts of carboxy groups in polyester resin (A-1). Next, the obtained solution 12 was applied to a resin film under the same conditions as in Example 1 and dried to produce an adhesive film 12 consisting of a resin film and an adhesive layer 12. The physical properties of the obtained adhesive layer 12 were evaluated under the same conditions as in Example 1. Next, a draw-forming laminate 12 was produced under the same conditions as in Example 1, except that the temperature at which the GA steel plate was preheated on the heating stage of the laminator was changed from 185°C to 200°C. The resulting draw-forming laminate 12 was evaluated for adhesion between the PET film and the GA steel sheet, and for draw-formability, under the same conditions as in Example 1. The evaluation results are shown in Table 3 below.

[0107]

[0108] As is clear from Table 3, Examples 1 to 7 are examples using adhesive films that satisfy the requirements of the present invention, and the adhesive layer contained in the adhesive film is easily stretched and not easily broken during drawing, so that the laminate in which the GA steel sheet and the PET film are bonded together via the adhesive layer exhibits good adhesion between the GA steel sheet and the PET film, and the PET film is not easily peeled off from the GA steel sheet during drawing. On the other hand, Comparative Examples 1 and 2 are examples using adhesive films that do not satisfy the requirements of the present invention, and the adhesive layer contained in the adhesive film is easily stretched and not easily broken during drawing, so that the laminate in which the GA steel sheet and the PET film are bonded together via the adhesive layer exhibits poor adhesion between the GA steel sheet and the PET film, and the PET film peeled off from the GA steel sheet during drawing.

Claims

1. An adhesive film for laminating extrusion-molded substrates, comprising a resin film and an adhesive layer laminated thereon, the adhesive layer comprising a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups in its side chain are crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and an ester exchange catalyst (D).

2. The adhesive film according to claim 1, wherein the epoxy-based crosslinking agent (B) contains an aliphatic epoxy compound.

3. The adhesive film according to claim 1, wherein the epoxy-based crosslinking agent (B) contains an epoxyamine compound further having a tertiary amino group in the molecule.

4. An adhesive film according to claim 3, wherein the epoxy amine compound has one or more epoxidized amino groups formed by bonding the tertiary amino group to the epoxy group via an alkylene group having 1 to 4 carbon atoms.

5. The adhesive film according to claim 1, which contains 30 to 60 parts by mole of the epoxy-based crosslinking agent (B) per 100 parts by mole of the carboxyl groups of the polyester resin (A).

6. The adhesive film according to claim 1, which contains 1 to 70 parts by mole of the transesterification catalyst (D) per 100 parts by mole of the carboxyl groups of the polyester resin (A).

7. An adhesive film as described in claim 1, wherein the polyester resin (A) is a polymer polyol (a) obtained by reacting a polycarboxylic acid component with a polyhydric alcohol component, and then reacting the polymer polyol (a) with a polycarboxylic acid component having three or more functionalities to provide a carboxyl group.

8. The adhesive film according to claim 7, wherein the polymer polyol (a) contains two or more polymer polyol components having different number average molecular weights (Mn).

9. An adhesive layer used to laminate a resin film to form an adhesive film for bonding a squeeze-molded substrate, the adhesive layer containing a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups in its side chain are crosslinked with an epoxy-based crosslinking agent (B) having multiple epoxy groups in the molecule, and a transesterification catalyst (D).

10. An adhesive layer as described in claim 9, wherein the stress at 100% elongation in the longitudinal direction at both 170°C and 250°C is 1 MPa or less, the stress at 200% elongation in the longitudinal direction at both 170°C and 250°C is 1 MPa or less, and the elongation at break at both 170°C and 250°C is 100% or more and 1200% or less.

11. An adhesive layer as described in claim 9, wherein the polyester resin (A) is a polymer polyol (a) obtained by reacting a polycarboxylic acid component with a polyhydric alcohol component, and then reacting the polymer polyol (a) with a polycarboxylic acid component having three or more functionalities to provide a carboxyl group.

12. The adhesive layer according to claim 11, wherein the polymer polyol (a) contains two or more polymer polyol components having different number average molecular weights (Mn).

13. A draw-forming laminate comprising a draw-forming substrate and the adhesive film according to any one of claims 1 to 8 bonded together.

14. A drawn product obtained from the draw-forming laminate according to claim 13.

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