Adhesive composition and adhesive sheet

Abstract

The present invention provides an adhesive composition which has excellent film-forming properties, and is capable of forming a dynamically bonded crosslinked polyester resin adhesive layer that has high adhesiveness to a resin base material such as a polyimide film and a metal base material such as a copper foil, and high heat resistance to withstand a solder bath.　The present invention specifically provides an adhesive composition (E) which contains a polyester resin (A), an epoxy compound (B), a transesterification catalyst (C), and an organic solvent (D), and which satisfies the following requirements (1) to (4). (1) The polyester resin (A) has a carboxy group in a side chain. (2) The organic solvent (D) is at least composed of an organic solvent (F) and an organic solvent (G). (3) The organic solvent (F) is composed of one organic solvent or a mixture of two or more organic solvents, and the relative energy difference (RED) with respect to the polyester resin (A) is 1.0 or less. (4) The organic solvent (G) is composed of one organic solvent or a mixture of two or more organic solvents, and the relative energy difference (RED) with respect to the transesterification catalyst (C) is 1.5 or less. The relative energy difference (RED) is a numerical value represented by formula (1). Formula (1): RED = Ra-b / R0 (In the formula, R0 is the interaction radius of the solute, and Ra-b is the distance between Hansen solubility parameter (HSP) values of the solute and the solvent.)

Description

Adhesive composition and adhesive sheet

[0001] The present invention relates to a polyester resin-containing adhesive composition in the process of producing a crosslinked polyester resin composition that exhibits adhesive properties, moldability, and repairability under high-temperature conditions, an adhesive sheet, and a printed wiring board using the same.

[0002] Crosslinked polyester resins, which are made by curing polyester resins with carboxyl groups in their side chains with epoxy compounds, have traditionally been used in adhesives and paints, but due to the irreversibility of the covalent bonds, they lack adhesion, formability, and repairability after curing. On the other hand, crosslinked polyester resins that incorporate dynamic bond crosslinking via bond exchange exhibit adhesion, formability, and repairability under high-temperature conditions, making them industrially useful.

[0003] Patent Document 1 reports a crosslinked aromatic polyester resin having a bond-exchange type dynamic bond crosslink, which is obtained by mixing a crosslinked aromatic polyester resin containing a carboxy group in the side chain with an epoxy compound and an ester exchange catalyst, and heating the mixture to crosslink the mixture.

[0004] WO2022 / 080469

[0005] In Patent Document 1, the organic solvent used in the production process of the crosslinked aromatic polyester resin is not particularly limited, except that it does not react with the polyester resin, the epoxy compound, or the crosslinked aromatic polyester resin. However, zinc acetate, which is used as the transesterification catalyst, has poor solubility in general-purpose solvents, and good solvents are quite limited, so the selection of the solvent is very important. If a solvent with poor solubility is used, the transesterification catalyst will remain undissolved, resulting in poor film-forming properties, which will result in poor coating appearance, and the heat resistance of the adhesive layer obtained by heating, drying, and curing the coating will be poor.

[0006] An object of the present invention is to provide an adhesive composition capable of forming a dynamically bond crosslinked polyester resin adhesive layer that has excellent film-forming properties, high adhesion to resin substrates such as polyimide films and metal substrates such as copper foils, and high heat resistance sufficient to withstand a solder bath.

[0007] As a result of extensive investigation, the present inventors have found that the above problems can be solved by the following means, and have arrived at the present invention. That is, the present invention has the following configuration.

[0008] [1] An adhesive composition (E) containing a polyester resin (A), an epoxy compound (B), a transesterification catalyst (C), and an organic solvent (D) and satisfying the following requirements (1) to (4): (1) The polyester resin (A) has a carboxy group in a side chain. (2) The organic solvent (D) comprises at least an organic solvent (F) and an organic solvent (G). (3) The organic solvent (F) comprises one organic solvent or a mixture of two or more organic solvents, and has a relative energy difference (RED) of 1.0 or less with respect to the polyester resin (A). (4) The organic solvent (G) comprises one organic solvent or a mixture of two or more organic solvents, and has a relative energy difference (RED) of 1.5 or less with respect to the transesterification catalyst (C). The relative energy difference (RED) is a numerical value expressed by the following mathematical formula (1): RED = R Equation (1) ａ－ｂ / R ０ (In the above formula (1), R ０ is the interaction radius of the solute, and R ａ－ｂis the distance between the Hansen solubility parameter (HSP) values ​​of the solute and the solvent.) [2] The adhesive composition (E) according to [1], further satisfying the following (5): (5) The molar ratio of the transesterification catalyst (C) to the carboxy groups of the polyester resin (A) (carboxy groups:transesterification catalyst) is 100:10 to 100:40. [3] The adhesive composition (E) according to [1] or [2], wherein the organic solvent (F) that dissolves the polyester resin (A) is at least one selected from aromatic organic solvents, alicyclic organic solvents, ketone organic solvents, ether organic solvents, amide organic solvents, and halogenated organic solvents. [4] The adhesive composition (E) according to any one of [1] to [3], wherein the organic solvent (F) for dissolving the polyester resin (A) is at least one selected from the group consisting of toluene, tetrahydrofuran, 1,4-dioxane, methyl ethyl ketone, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dichloromethane, and chloroform. [5] The adhesive composition (E) according to any one of [1] to [4], wherein the organic solvent (G) for dissolving the transesterification catalyst (C) is at least one selected from the group consisting of amide organic solvents, alcohol organic solvents, aprotic organic solvents, and ketone organic solvents. [6] The adhesive composition (E) according to any one of [1] to [5], wherein the organic solvent (G) for dissolving the transesterification catalyst (C) is at least one selected from the group consisting of N,N-dimethylformamide, N-methyl-2-pyrrolidone, methanol, dimethyl sulfoxide, acetone, γ-butyrolactone, and acetonitrile. [7] The adhesive composition (E) according to any one of [1] to [6], wherein the polyester resin (A) has an acid value of 5 mgKOH / g or more and 120 mgKOH / g or less. [8] The adhesive composition (E) according to any one of [1] to [7], wherein the viscosity at 25°C and 5 rpm is 20 Pa s or less. [9] An adhesive sheet containing a cured product of the adhesive composition (E) according to any one of [1] to [8].

[10] A printed wiring board containing the adhesive sheet according to [9] as a component.

[11] A method for producing an adhesive composition (E), comprising: a step S1 of dissolving a polyester resin (A) in an organic solvent (F) having a relative energy difference (RED) to the polyester resin (A) of 1.0 or less to produce a polyester resin solution (SA), a step S2 of dissolving a transesterification catalyst (C) in an organic solvent (G) having a relative energy difference (RED) to the transesterification catalyst (C) of 1.5 or less to produce a transesterification catalyst solution (SC), and a step S3 of mixing at least the polyester resin solution (SA), the transesterification catalyst solution (SC), and an epoxy compound (B) to produce an adhesive composition (E).

[12] A method for producing an adhesive sheet, comprising: a step T1 of applying the adhesive composition (E) obtained by the production method of

[11] to a substrate to produce a coating film, a step T2 of heating the coating film to remove at least a portion of the organic solvent and produce a dried coating film, and a step T3 of further heating the dried coating film to produce a crosslinked polyester resin and produce an adhesive layer.

[13] A method for producing a laminate, comprising step U1 of press-bonding, under heat, an adhesive sheet obtained by the production method according to item

[12] to an adherend, followed by cooling to produce a laminate.

[14] The adhesive composition (E) according to any one of items [1] to [8], wherein the organic solvent (F) for dissolving the polyester resin (A) is at least one selected from the group consisting of aromatic organic solvents and ketone organic solvents.

[15] The adhesive composition (E) according to any one of items [1] to [8], wherein the organic solvent (F) for dissolving the polyester resin (A) is at least one selected from the group consisting of toluene and methyl ethyl ketone.

[16] The adhesive composition (E) according to any one of items [1] to [8], wherein the organic solvent (G) for dissolving the transesterification catalyst (C) is at least one selected from the group consisting of amide organic solvents and alcohol organic solvents.

[17] The adhesive composition (E) according to any one of [1] to [8], wherein the organic solvent (G) for dissolving the transesterification catalyst (C) is at least one selected from the group consisting of N,N-dimethylformamide, N-methyl-2-pyrrolidone, and methanol.

[0009] The adhesive composition of the present invention exhibits excellent film-forming properties and can produce an adhesive layer that is excellent in adhesion and ordinary solder heat resistance.

[0010] The adhesive composition of the present invention is an adhesive composition (E) containing a polyester resin (A), an epoxy compound (B), a transesterification catalyst (C), and an organic solvent (D).

[0011] <Polyester Resin (A)> The polyester resin (A) is a resin having a carboxy group on a side chain of the polyester resin. Here, the structure of the polyester resin having a carboxy group on a side chain may be a structure in which the carboxy group is on a substituent (for example, 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 the carboxy group is directly on the polyester resin. A structure in which the carboxy group is directly on the polyester resin is preferred.

[0012] The number average molecular weight (Mn) of the polyester resin (A) is preferably 8,000 or more, more preferably 10,000 or more, and even more preferably 12,000 or more. The number average molecular weight (Mn) of the polyester resin (A) is preferably 30,000 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 (A) is preferably 8,000 to 30,000, more preferably 10,000 to 25,000, and even more preferably 12,000 to 20,000. By setting the number average molecular weight (Mn) of the polyester resin (A) within the above range, it becomes easier to control the acid value of the polyester resin (A).

[0013] The acid value of the polyester resin (A) is preferably 5 mgKOH / g or more. The acid value of the polyester resin (A) is more preferably 10 mgKOH / g or more, and even more preferably 15 mgKOH / g or more, because sufficient crosslinking is achieved and heat resistance is improved. Furthermore, the acid value of the polyester resin (A) is preferably 120 mgKOH / g or less. The acid value of the polyester resin (A) is more preferably 110 mgKOH / g or less, and even more preferably 100 mgKOH / g or less, because this prevents the crosslink density from becoming too high and the cured coating film obtained from the crosslinked polyester resin composition from becoming too hard. That is, the acid value of the polyester resin (A) is preferably 5 to 120 mgKOH / g, more preferably 10 to 110 mgKOH / g, and even more preferably 15 to 100 mgKOH / g.

[0014] The polyester resin (A) preferably contains multiple ester bonds and carboxy groups in the molecule. In particular, the carboxy groups are more preferably contained in the molecular chain at two or more points, even more preferably at three or more points, and even more preferably at four or more points. There is no particular upper limit, but it is sufficient as long as it is 50 points or less, and it may be 30 points or less. That is, the number of carboxy groups (N) per polymer chain of the polyester resin (A) ＣＯＯＨ ) is preferably 2 to 50, more preferably 3 to 30, and even more preferably 4 to 30.

[0015] The glass transition temperature (Tg) of the polyester resin (A) is preferably −10° C. or higher, more preferably 0° C. or higher, and even more preferably 5° C. or higher. The glass transition temperature (Tg) of the polyester resin (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 (Tg) of the polyester resin (A) is preferably −10° C. to 100° C., more preferably 0° C. to 80° C., and even more preferably 5° C. to 60° C.

[0016] The polyester resin (A) must have a side chain (hereinafter also referred to as a branched structure) in the molecule. In order for the polyester resin (A) to have a branched structure, it is preferable that the copolymerization component that serves as the raw material for the polyester resin (A) has a branched structure. The polyester resin (A) may be (i) a product obtained by reacting (copolymerizing) a polymer polyol (P) with a chain extender (Q) or the like, or (ii) a product obtained by adding a monomer having a carboxy group to a polyester having a reactive site obtained by reacting a polycarboxylic acid component with a polyalcohol component. One type of polymer polyol may be used, or two or more types may be used in combination.

[0017] The polycarboxylic acid component used in the polyester resin (A) is preferably an aromatic dicarboxylic acid component. Examples of aromatic dicarboxylic acid components include, but are not limited to, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and diphenic acid. Other 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 sulfonate salt group, such as their metal salts and ammonium salts. These may be used alone or in combination of two or more. Among these, terephthalic acid, isophthalic acid, and mixtures thereof are particularly preferred in terms of increasing the cohesive strength of the coating film.

[0018] Other polycarboxylic acid components that can be used in the polyester resin (A) include alicyclic dicarboxylic acids and their acid anhydrides, such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,2-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids and their acid anhydrides, such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid; and unsaturated bond-containing dicarboxylic acids and their acid anhydrides, such as maleic acid and fumaric acid. Also usable are hydroxycarboxylic acid compounds having a hydroxyl group and a carboxy group in their molecular structure, such as 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenethyl alcohol, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis(p-hydroxyphenyl)valeric acid; and thiomalic acid having a thiol group in its molecular structure.

[0019] The polyalcohol component used in the polyester resin (A) is preferably a glycol component. The glycol component is preferably an aliphatic glycol, an alicyclic glycol, an aromatic group-containing glycol, or an ether bond-containing glycol, and more preferably an aliphatic glycol.

[0020] 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, dimethylolheptane, 2,2,4-trimethyl-1,3-pentanediol, etc. Among these, it is preferable to use at least one selected from the group consisting of ethylene glycol, 2-methyl-1,3-butanediol, 2,2-dimethyl-1,3-propanediol, and 1,6-hexanediol.

[0021] 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 the like.

[0022] 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, 1,4-phenylene glycol, an ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, an ethylene oxide adduct and a propylene oxide adduct of bisphenol A, and glycol-modified aromatic dicarboxylic acids. Specific examples of glycol-modified aromatic dicarboxylic acids include, but are not limited to, bis-2-hydroxyethyl terephthalate (BHET), which is an ethylene glycol-modified terephthalic acid, a propylene glycol-modified terephthalic acid, an ethylene glycol-modified isophthalic acid, a propylene glycol-modified isophthalic acid, an ethylene glycol-modified orthophthalic acid, and a propylene glycol-modified orthophthalic acid. Further, 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.

[0023] 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.

[0024] These polycarboxylic acids and polyalcohol components can be used alone or in combination of two or more.

[0025] The polyester resin (A) may be a copolymer of a high molecular weight polyol (P) and a chain extender (Q).

[0026] The polymer polyol (P) used in the polyester resin (A) is preferably a copolymer of the polycarboxylic acid component and the polyol component (i.e., a polymer polyester polyol). The polymer polyol (P) is also preferably an acid-added polymer polyol with a trifunctional or higher polycarboxylic acid compound.

[0027] Examples of trifunctional or higher functional polycarboxylic acid compounds 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. Among these, trimellitic anhydride is preferably used. On the other hand, examples of tri- or higher functional polyol components include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0028] The number average molecular weight (Mn) of the polymer polyol (P) is preferably 1,000 or more, more preferably 2,000 or more, and even more preferably 3,000 or more. The number average molecular weight (Mn) of the polymer polyol (P) is preferably 30,000 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 polymer polyol (P) is preferably 1,000 to 30,000, more preferably 2,000 to 25,000, and even more preferably 3,000 to 20,000.

[0029] The acid value of the polymer polyol (P) is preferably 0.1 mgKOH / g or more, more preferably 0.2 mgKOH / g or more, and even more preferably 0.3 mgKOH / g or more. The acid value of the polymer polyol (P) is preferably 20 mgKOH / g or less, more preferably 15 mgKOH / g or less, and even more preferably 10 mgKOH / g or less. That is, the acid value of the polymer polyol (P) is preferably 0.1 to 20 mgKOH / g, more preferably 0.2 to 15 mgKOH / g, and even more preferably 0.3 to 10 mgKOH / g.

[0030] The glass transition temperature (Tg) of the polymer polyol (P) is preferably −10° C. or higher, more preferably 0° C. or higher, and even more preferably 5° C. or higher. The glass transition temperature (Tg) of the polymer polyol (P) 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 (Tg) of the polymer polyol (P) is preferably −10° C. to 100° C., more preferably 0° C. to 80° C., and even more preferably 5° C. to 60° C.

[0031] The chain extender (Q) is not particularly limited, but may be a tetracarboxylic dianhydride. In this case, the reaction between the acid anhydride group of the chain extender (Q) and the hydroxyl group of the polymer polyol (P) generates an ester bond in the main chain of the polymer polyester polyol, and a carboxyl group is generated in a branched form from the main chain.

[0032] Preferred examples of tetracarboxylic acid dianhydrides include aromatic tetracarboxylic acid dianhydrides, aliphatic tetracarboxylic acid dianhydrides, and alicyclic tetracarboxylic acid dianhydrides, with aromatic tetracarboxylic acid dianhydrides being more preferred. Specific examples of tetracarboxylic acid dianhydrides include pyromellitic anhydride (PMDA), oxydiphthalic 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 dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA). These can be used alone or in combination of two or more. Among these, pyromellitic anhydride is preferred.

[0033] The copolymerization ratio of the polymer polyol (P) and the chain extender (Q) 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, per 100 parts by mass of the polymer polyol (P). Furthermore, the amount of the chain extender (Q) per 100 parts by mass of the polymer polyol (P) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. That is, the amount of the chain extender (Q) per 100 parts by mass of the polymer polyol (P) is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 10 parts by mass.

[0034] A polyester containing multiple carboxyl groups is preferably used as the polyester resin (A). The method for introducing an acid value into the polyester resin (A) is not particularly limited, but the following two methods can be further exemplified.

[0035] The first method is to introduce a carboxylic acid into a polyester polyol by acid addition after polymerization. When a monocarboxylic acid, a dicarboxylic acid, or a polycarboxylic acid compound having three or more functional groups is used for the acid addition, a decrease in molecular weight may occur due to ester exchange, so it is preferable to use a compound having at least one carboxylic anhydride group.

[0036] Examples of carboxylic acid anhydrides include succinic anhydride, maleic anhydride, orthophthalic anhydride, 2,5-norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, 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). Of these, trimellitic anhydride is preferably used.

[0037] In the second method, a polyester precursor containing multiple double bond sites is obtained by melt polycondensation using a glycol-modified aromatic dicarboxylic acid as the diol component and maleic acid as the dicarboxylic acid component. When this precursor is reacted with, for example, thioglycolic acid, a Michael addition reaction occurs between the double bond sites derived from maleic acid and the thiol group, resulting in a polyester resin (A) containing multiple carboxyl groups in the side chain.

[0038] <Epoxy Compound (B)> The epoxy compound (B) is not particularly limited, but is preferably a compound having two or more epoxy groups in the molecule. The compound having two or more epoxy groups in the molecule (epoxy crosslinking agent) is not particularly limited as long as it undergoes a curing reaction with the carboxy group of the polyester resin (A) to form a crosslink. By using the epoxy compound (B), the cured coating film obtained from the crosslinked polyester resin composition is likely to form three-dimensional crosslinks, making it possible to improve heat resistance.

[0039] Examples of the epoxy compound (B) used in the present invention include diol diglycidyl ethers, epoxy amine 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. Examples of diol diglycidyl ethers include aliphatic diol diglycidyl ethers such as 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 1,6-hexanediol diglycidyl ether. Among these, 1,4-butanediol diglycidyl ether is preferred. Examples of epoxy amine 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). Commercially available N,N,N',N'-tetraglycidyl-m-xylylenediamine includes, for example, "TETRAD-X" (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc. 4,4'-methylenebis(N,N-diglycidylaniline) is available, for example, from Tokyo Chemical Industry Co., Ltd. (TCI). Among these, N,N,N',N'-tetraglycidyl-m-xylylenediamine is preferred. Examples of compounds containing two or more epoxy groups and one tertiary amino group in the molecule include compounds having one diglycidylamino group, a glycidyloxy group, and a benzene ring, such as triglycidyl paraaminophenol [also known as N,N-diglycidyl-4-(glycidyloxy)aniline], and compounds having one diglycidylamino group and a benzene ring, such as N,N-diglycidylaniline.Commercially available triglycidyl paraaminophenols include, for example, "JER630" (trade name) manufactured by Mitsubishi Chemical Corporation. Commercially available N,N-diglycidylaniline products include, for example, "GAN" (trade name) manufactured by Nippon Kayaku Co., Ltd.

[0040] Other epoxy compounds can be used in combination as the epoxy compound (B). Examples of other epoxy compounds include glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether, glycidyl ester types such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester, and alicyclic or aliphatic epoxides such as triglycidyl isocyanate, 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. These may be used alone or in combination of two or more.

[0041] The number average molecular weight (Mn) of the epoxy compound (B) is preferably 100 or more and 500 or less, more preferably 200 or more and 400 or less, from the viewpoint of the crosslinking density of the crosslinked polyester resin.

[0042] The mixing ratio of the polyester resin (A) and the epoxy compound (B) can be determined based on the functional group molar ratio between the carboxy groups in the side chains of the polyester resin (A) and the epoxy groups of the epoxy compound (B). From the viewpoints of crosslinking reaction efficiency and adhesiveness after crosslinking, the ratio of the carboxy groups in the polyester resin (A) to the epoxy groups in the epoxy compound (B) (carboxy groups:epoxy groups) is preferably 100:50 to 100:150 (mol parts), and more preferably 100:80 to 100:120 (mol parts).

[0043] The reaction temperature of the polyester resin (A) and the epoxy compound (B) is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher. The reaction temperature is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. That is, the reaction temperature is preferably 80°C to 200°C, more preferably 100°C to 180°C, and even more preferably 120°C to 160°C.

[0044] The crosslinking reaction time varies depending 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.

[0045] <Transesterification catalyst (C)> The transesterification catalyst (C) is a catalyst for transesterification of the ester groups in the polyester resin (A). The transesterification catalyst (C) causes dynamic covalent crosslinking in the adhesive sheet after curing, which enables bond exchange at high temperatures, resulting in high strength at room temperature and enabling adhesion to substrates and films at temperatures equal to or higher than the ester bond exchange activation temperature. In addition, stress relaxation is achieved, making it possible to suppress problems such as cracking and circuit distortion caused by differences in thermal expansion between the insulating layer and the conductor layer.

[0046] Examples of the transesterification catalyst (C) include anhydrous zinc acetate, zinc acetate dihydrate, zinc acetylacetonate, triphenylphosphine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,8-diazabicyclo[5.4.0]undecene-7, and tetrabutyl titanate. Of these, anhydrous zinc acetate and zinc acetate dihydrate are preferred.

[0047] The amount of the transesterification catalyst (C) mixed is preferably 10 to 40 parts by mole, and more preferably 10 to 30 parts by mole, per 100 parts by mole of carboxy groups in the polyester resin (A), from the viewpoints of the mechanical strength of the polyester resin (A), the uniformity of the sample, and the adhesiveness after curing.

[0048] <Organic Solvent (D)> The organic solvent (D) comprises at least an organic solvent (F) and an organic solvent (G). The organic solvent (F) comprises one organic solvent or a mixture of two or more organic solvents, and has a relative energy difference (RED) of 1.0 or less with respect to the polyester resin (A). The organic solvent (G) comprises one organic solvent or a mixture of two or more organic solvents, and has a relative energy difference (RED) of 1.5 or less with respect to the transesterification catalyst (C). The organic solvents (F) and (G) may be the same type of solvent.

[0049] From the viewpoint of solubility, the organic solvent (F) that dissolves the polyester resin (A) has a relative energy difference (RED) with respect to the polyester resin (A) represented by the following mathematical formula (1) of 1.0 or less. RED=R mathematical formula (1) ａ－ｂ / R ０ (In the above formula (1), R ０ is the interaction radius of the polyester resin (A), and R ａ－ｂ is the distance between the Hansen solubility parameter (HSP) value of the polyester resin (A) and the HSP value of the organic solvent (F).

[0050] When the organic solvent (F) has a relative energy difference (RED) of 1.0 or less with respect to the polyester resin (A), the polyester resin (A) dissolves in the organic solvent (F). The organic solvent (F) is preferably an organic solvent having a relative energy difference (RED) of 0.98 or less with respect to the polyester resin (A), and more preferably an organic solvent having a relative energy difference (RED) of 0.97 or less with respect to the polyester resin (A).

[0051] From the viewpoint of solubility, the organic solvent (G) that dissolves the transesterification catalyst (C) has a RED value of 1.5 or less for the transesterification catalyst (C) represented by the following mathematical formula (1): RED=R mathematical formula (1) ａ－ｂ / R ０ (In the above formula (1), R ０ is the interaction radius of the transesterification catalyst (C), and R ａ－ｂ is the distance between the HSP value of the transesterification catalyst (C) and the HSP value of the organic solvent (G).

[0052] When the organic solvent (G) has an RED value of 1.5 or less relative to the transesterification catalyst (C), the transesterification catalyst (C) is insoluble (i.e., in a dispersed state) or soluble in the organic solvent (G). The organic solvent (G) is preferably an organic solvent having a relative energy difference (RED) relative to the transesterification catalyst (C) of 1.45 or less, more preferably 1.30 or less, and even more preferably 1.0 or less.

[0053] <Hansen Solubility Parameter (HSP) Value and Interaction Radius> The HSP (Hansen Solubility Parameter) is a value used to predict the solubility of a substance and is expressed by three parameters: London dispersion force, dipole-dipole force, and hydrogen bonding force. In the present invention, the component corresponding to the London dispersion force is referred to as the dispersion term (hereinafter also referred to as "δd"), the component corresponding to the dipole-dipole force is referred to as the polarization term (hereinafter also referred to as "δp"), and the component corresponding to the hydrogen bonding force is referred to as the hydrogen bonding term (hereinafter also referred to as "δh"). These three parameters can be regarded as coordinates in a three-dimensional space (Hansen space). When the HSPs of two substances are plotted in Hansen space, the closer the distance between two points, the higher the affinity and the easier it is for the substances to dissolve in each other.

[0054] A database has been constructed for the HSPs of commonly used substances, and a person skilled in the art can obtain the HSP value of a desired substance by referring to this database.

[0055] Even for substances for which HSP values ​​are not registered in the database, those skilled in the art can calculate the HSP value from their chemical structure using computer software such as Hansen Solubility Parameters in Practice (HSPiP). Alternatively, the HSP value can be determined by conducting a dissolution test using multiple solvents with known HSP values ​​and inputting the resulting solubilities into HSPiP. Furthermore, in the case of a mixture of multiple substances, the HSP value can be calculated as the sum of the values ​​obtained by multiplying the HSP values ​​of each substance by the volume ratio of each substance.

[0056] In the present invention, the HSP values ​​and interaction radii of substances whose HSP values ​​are not registered in the database were determined by dissolving a certain amount of the substance to be measured in 28 solvents with known HSP values, and inputting the solubility into HSPiP.

[0057] In the present invention, the distance R between the HSP value of the polyester resin (A) and the HSP value of the organic solvent (F) ａ－ｂ can be calculated by the following formula (2): ａ－ｂ ) ２ = 4 × (δd ２ -δd １ ) ２ +(δp ２ -δp １ ) ２ + (δh ２ -δh １ ) ２ (In formula (2), δd １ , δp １ , δh １ represent the dispersion term of the HSP value of the polyester resin (A), the polarization term of the HSP value of the polyester resin (A), and the hydrogen bond term of the HSP value of the polyester resin (A), respectively. ２ , δp ２ and δh ２ represent the dispersion term of the HSP value of the organic solvent (F), the polarization term of the HSP value of the organic solvent (F), and the hydrogen bond term of the HSP value of the organic solvent (F), respectively.

[0058] In the present invention, the relative energy difference (RED) of the organic solvent (F) to the polyester resin (A) can be calculated by the following formula (1): RED=R Formula (1) ａ－ｂ / R ０ (In formula (1), R ０ represents the interaction radius of the polyester resin (A), and R ａ－ｂ indicates the distance between the HSP value of the polyester resin (A) and the HSP value of the organic solvent (F).

[0059] The organic solvent (F) for dissolving the polyester resin (A) may be at least one selected from aromatic organic solvents, alicyclic organic solvents, ketone organic solvents, ether organic solvents, amide organic solvents, and halogenated organic solvents, and may be two or more selected from these. Examples of aromatic organic solvents include toluene. Examples of alicyclic organic solvents include tetrahydrofuran and 1,4-dioxane. Examples of ketone organic solvents include methyl ethyl ketone. Examples of ether organic solvents include tetrahydrofuran. Examples of amide organic solvents include N,N-dimethylformamide and N-methyl-2-pyrrolidone. Examples of halogenated organic solvents include dichloromethane and chloroform. The organic solvent (F) preferably contains an aromatic organic solvent or a ketone organic solvent, and more preferably contains both an aromatic organic solvent and a ketone organic solvent.

[0060] Examples of the organic solvent (F) for dissolving the polyester resin (A) include toluene, tetrahydrofuran, 1,4-dioxane, methyl ethyl ketone, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dichloromethane, and chloroform. The organic solvent (F) may contain one or more selected from these. Among these, the organic solvent (F) preferably contains toluene or methyl ethyl ketone, and more preferably contains toluene and methyl ethyl ketone.

[0061] In the present invention, the distance R between the HSP value of the transesterification catalyst (C) and the HSP value of the organic solvent (G) ａ－ｂ can be calculated by the following formula (2): ａ－ｂ ) ２ = 4 × (δd ２ -δd １ ) ２ +(δp ２ -δp １ ) ２ + (δh ２ -δh １ ) ２ (In formula (2), δd１ , δp １ , δh １ represent the dispersion term of the HSP value of the transesterification catalyst (C), the polarization term of the HSP value of the transesterification catalyst (C), and the hydrogen bond term of the HSP value of the transesterification catalyst (C), respectively. ２ , δp ２ and δh ２ represent the dispersion term of the HSP value of organic solvent (G), the polarization term of the HSP value of organic solvent (G), and the hydrogen bond term of the HSP value of organic solvent (G), respectively.

[0062] In the present invention, the RED of the organic solvent (G) relative to the transesterification catalyst (C) can be calculated by the following mathematical formula (1): RED = R ａ－ｂ / R ０ (In formula (1), R ０ represents the interaction radius of the transesterification catalyst (C), and R ａ－ｂ indicates the distance between the HSP value of the transesterification catalyst (C) and the HSP value of the organic solvent (G).

[0063] The organic solvent (G) in which the transesterification catalyst (C) is dissolved may be at least one selected from amide organic solvents, alcohol organic solvents, aprotic organic solvents, and ketone organic solvents, and may be two or more selected from these. Examples of amide organic solvents include N,N-dimethylformamide and N-methyl-2-pyrrolidone. Examples of alcohol organic solvents include methanol and ethanol. Examples of aprotic organic solvents include dimethyl sulfoxide and acetonitrile. Examples of ketone organic solvents include acetone and γ-butyrolactone. The organic solvent (G) preferably contains an amide organic solvent or an alcohol organic solvent.

[0064] Examples of the organic solvent (G) for dissolving the transesterification catalyst (C) include N,N-dimethylformamide, N-methyl-2-pyrrolidone, methanol, dimethyl sulfoxide, acetone, γ-butyrolactone, and acetonitrile. The organic solvent (G) may contain one or more selected from these, and preferably contains at least one selected from the group consisting of N,N-dimethylformamide, N-methyl-2-pyrrolidone, and ethanol.

[0065] The organic solvent (D) is preferably a mixed solvent of two or more kinds, more preferably three or more kinds, of an organic solvent (F) that dissolves the polyester resin (A) and an organic solvent (G) that dissolves the transesterification catalyst (C). When the organic solvent (D) is a three-kind mixed solvent consisting of an organic solvent (F) that dissolves the polyester resin (A) and an organic solvent (G) that dissolves the transesterification catalyst (C), the organic solvent (D) may be, for example, a mixed solvent containing one organic solvent (F) that dissolves the polyester resin (A) and two organic solvents (G) that dissolve the transesterification catalyst (C), but is preferably a mixed solvent containing two organic solvents (F) that dissolve the polyester resin (A) and one organic solvent (G) that dissolves the transesterification catalyst (C).

[0066] <Adhesive composition (E)> The adhesive composition (E) is a composition containing a polyester resin (A), an epoxy compound (B), a transesterification catalyst (C), and an organic solvent (D). The organic solvent (D) is composed of at least an organic solvent (F) and an organic solvent (G). Note that the organic solvents (F) and (G) may be the same type of solvent.

[0067] The viscosity of the adhesive composition (E) at 25°C and 5 rpm is preferably 20 Pa s or less, and more preferably 15 Pa s or less, from the viewpoint of coatability. The viscosity of the adhesive composition (E) may be measured using an E-type viscometer.

[0068] To produce the adhesive composition (E), first, a polyester resin solution (SA) is prepared by dissolving the polyester resin (A) in an organic solvent (F) having a relative energy difference (RED) of 1.0 or less relative to the polyester resin (A) (step S1), and a transesterification catalyst (C) is dissolved in an organic solvent (G) having a relative energy difference (RED) of 1.5 or less relative to the transesterification catalyst (C) to prepare a transesterification catalyst solution (SC) (step S2), and the two are then mixed. By employing these steps, the transesterification catalyst (C) can be uniformly dispersed in the adhesive composition (E), thereby fully demonstrating the effects of the present application. Next, the adhesive composition (E) can be produced by mixing at least the polyester resin solution (SA), the transesterification catalyst solution (SC), and the epoxy compound (B) (step S3). The components contained in the adhesive composition (E) other than the polyester resin solution (SA) and the transesterification catalyst solution (SC), i.e., the epoxy compound (B) and other components, may be added and mixed simultaneously with the polyester resin solution (SA) and the transesterification catalyst solution (SC), or may be mixed sequentially in any order.

[0069] <Adhesive Sheet> The present invention also includes an adhesive sheet containing a cured product of the adhesive composition (E). That is, the adhesive sheet contains a cured coating film (hereinafter also referred to as an adhesive layer) of the adhesive composition obtained by curing the adhesive composition (E). The adhesive sheet has the function of adhering a substrate to an adhesive layer via the adhesive layer, and may be a two- or more-layer adhesive sheet having other layers such as a substrate layer and a release layer, or may be a single-layer adhesive sheet obtained by processing the cured coating film of the adhesive composition obtained by curing the adhesive composition (E) of the present invention into a sheet shape. Examples of the substrate to be laminated with the cured coating film include resin substrates, and may also be release-treated films. Examples of the resin substrate include polyimide films.

[0070] Examples of methods for producing an adhesive sheet include a hot melt coating method in which the cured adhesive composition is extruded onto a substrate (e.g., a release-treated film), and a method in which adhesive composition (E) is applied to a substrate (e.g., a release-treated film), and then the solvent is dried and the composition is cured.

[0071] The adhesive sheet can be produced, for example, by sequentially performing the following steps: Step T1: Applying the adhesive composition (E) to a substrate to produce a coating film; Step T2: Heating the coating film to remove at least a portion of the organic solvent to produce a dried coating film; Step T3: Further heating the dried coating film to produce a crosslinked polyester resin to produce an adhesive layer.

[0072] Here, by using a releasable substrate (e.g., a release-treated film) as the substrate used in step T1, and peeling the substrate and the dried coating film between steps T2 and T3, or peeling the substrate and the adhesive layer after step T3, an adhesive sheet consisting of a single adhesive layer can be obtained, in which the coating film of adhesive composition (E) itself is processed into a sheet. Furthermore, if the substrate is not peeled, a two-layer adhesive sheet consisting of a releasable substrate and an adhesive layer can also be obtained. Furthermore, by using a laminate of one or more layers of a substrate film layer, a metal foil layer, and a cover film layer, which are components of printed wiring boards described below, as the substrate used in step T1, a component of a printed wiring board having an adhesive layer can be produced.

[0073] The heating temperature in step T2 is, for example, preferably 70 to 150° C., more preferably 80 to 140° C. The heating in step T2 may be performed at a constant temperature, or the temperature may be changed as appropriate. The total heating time in step T2 depends on the heating temperature, but may be, for example, 1 to 10 minutes, or 2 to 8 minutes.

[0074] The heating temperature in step T3 is, for example, preferably 120 to 160° C., more preferably 130 to 150° C. The heating in step T3 may be performed at a constant temperature, or the temperature may be changed as appropriate. The total heating time in step T3 depends on the heating temperature, but may be, for example, 30 minutes to 6 hours, or 1 hour to 5 hours.

[0075] A laminate can be obtained by superposing an adhesive sheet and an adherend. Examples of the adherend include metal foil. The metal foil may be laminated with a resin. Examples of the metal foil include copper foil, and examples of copper foil and resin laminates include copper-clad laminates. Examples of copper-clad laminates include copper / polyimide / copper laminates.

[0076] The present invention also includes a method for producing a laminate, which includes step U1 of press-bonding an adhesive sheet and an adherend under heat and then cooling to produce a laminate. That is, by press-bonding an adhesive sheet and an adherend under heat and then cooling, a laminate consisting of an adhesive layer and an adherend can be produced.

[0077] When the adhesive sheet has two or more layers including an adhesive layer and a substrate, the adherend may be laminated so as to come into contact with the adhesive layer. The temperature at which the adhesive sheet and the adherend are heated is, for example, preferably 150 to 190°C, more preferably 160 to 180°C. The pressure at which the adhesive sheet and the adherend are pressed together is, for example, 15 to 25 kgf / cm. ２ is preferable, and more preferably 18 to 23 kgf / cm ２ is.

[0078] <Printed Wiring Board> The present invention also includes a printed wiring board containing an adhesive sheet as a component. The printed wiring board may contain, as a component, a laminate formed from a metal foil and a resin substrate that form a conductor circuit. The printed wiring board is manufactured, for example, by a conventionally known method such as a subtractive method using a metal-clad laminate. This generic term refers to so-called flexible printed circuit boards (FPCs), flat cables, circuit boards for tape automated bonding (TAB), etc., in which a conductor circuit formed from metal foil is partially or entirely covered with a cover film, screen printing ink, etc., as necessary.

[0079] The printed wiring board of the present invention can have any laminated structure that can be used as a printed wiring board. For example, it can be a printed wiring board consisting of four layers: a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. It can also be a printed wiring board consisting of five layers: a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer. Furthermore, if necessary, it can be configured by stacking two or more of the above printed wiring boards.

[0080] This application claims the benefit of priority based on Japanese Patent Application No. 2023-130257, filed on August 9, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-130257 are incorporated herein by reference.

[0081] In order to explain the present invention in more detail, examples and comparative examples are given below, but the present invention is not limited to these examples. The measured values ​​described in the examples and comparative examples were measured by the following methods. Furthermore, unless otherwise specified, "parts" means "parts by mass."

[0082] Polymerization Example of Polymer Polyol (A1-1) In a reactor equipped with a stirrer, thermometer, and distillation condenser, 30 mol parts of terephthalic acid, 69 mol parts of isophthalic acid, 1 mol part of trimellitic anhydride, 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 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 then final polymerization was carried out until a predetermined stirring 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, and the reaction was carried out at 220 ° C. for 30 minutes to obtain a polymer polyol (A1-1). The composition and properties of the polymer polyol (A1-1) obtained in this manner are shown in Table 1. Each measurement and evaluation item was performed according to the methods described below.

[0083] Polymerization Example of Polymer Polyol (A1-2) In a reactor equipped with a stirrer, thermometer, and distillation condenser, 50 mol parts of terephthalic acid, 50 mol parts of isophthalic acid, 55 mol parts of ethylene glycol, 45 mol parts of 2,2-dimethyl-1,3-propanediol, and 0.2 mol parts of tetrabutyl titanate were charged, and 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, the pressure was gradually reduced to 10 mmHg while performing reduced pressure initial polymerization, and the temperature was raised to 250 ° C., and then further polymerization was carried out at 1 mmHg or less until a predetermined stirring torque was reached, thereby obtaining a polymer polyol (A1-2). The composition and property values ​​of the polymer polyol (A1-2) obtained in this manner are shown in Table 1. Each measurement and evaluation item was performed according to the methods described below.

[0084] Synthesis Example of Polyester Resin (A-1) In a reactor equipped with a stirrer, thermometer, and reflux condenser, 80 parts of polymer polyol (A1-1), 20 parts of polymer polyol (A1-2), 2.6 parts of pyromellitic anhydride, and 100 parts of toluene were charged and dissolved in toluene while gradually increasing the temperature to 80 ° C. After completion of dissolution, 0.05 parts of triethylamine was added as a reaction catalyst, and then the temperature was gradually increased to 105 ° C. and the reaction was allowed to proceed for 24 hours. After confirming the completion of the reaction by IR (infrared spectroscopy), the mixture was diluted with 54 parts of toluene to obtain a solution of carboxylic acid group-containing polyester resin (A-1) with a solids concentration of 40%. The composition and properties of the polyester resin (A-1) containing carboxy groups in the side chains obtained in this way are shown in Table 2.

[0085]

[0086]

[0087] <Number-Average Molecular Weight (Mn)> A sample was dissolved or diluted in tetrahydrofuran to a concentration of approximately 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 (Mn) 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. Showa Denko KF-802, 804L, and 806L columns were used. Monodisperse polystyrene was used as the molecular weight standard. However, when the sample was insoluble in tetrahydrofuran, N,N-dimethylformamide was used instead of tetrahydrofuran. Low-molecular-weight compounds (oligomers, etc.) with a number-average molecular weight (Mn) of less than 1,000 were not counted and were omitted.

[0088] <Acid value> 0.2 g of a sample was dissolved in 20 ml of chloroform and titrated with a 0.1 N ethanolic solution of potassium hydroxide 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 resin to calculate the acid value (mg KOH / g).

[0089] <Number of carboxyl groups per polymer chain (N ＣＯＯＨ ) > number of carboxy groups per polymer chain (N ＣＯＯＨ ) was calculated by the following formula: NCOOH=A / 56.1×B / 1000, where A is the acid value (mg KOH / g), B is the number average molecular weight (g / mol) of the aromatic polyester resin (A) containing a carboxy group in the side chain, and 56.1 is the molecular weight of KOH (g / mol).

[0090] <Glass transition temperature> Using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., 5 mg of a sample was placed in an aluminum pan, the pan was sealed with a lid, and the pan was held at 250°C for 5 minutes, then rapidly cooled with liquid nitrogen. Thereafter, the pan was heated from -100°C to 300°C at a heating rate of 20°C / min. The inflection point of the obtained curve was taken as the glass transition temperature.

[0091] Example 1: A polyester resin (A-1) containing a carboxyl group in its side chain was used as the polyester resin (A), and 1,4-butanediol diglycidyl ether was used as the epoxy compound (B). Based on 100 parts by mass of polyester resin (A), the materials were blended in the amounts shown in Table 3. The blending order was as follows: first, a solution of polyester resin (A) dissolved in a mixed solvent of methyl ethyl ketone and toluene was prepared, and then a solution of anhydrous zinc acetate (transesterification catalyst (C)) dissolved in N,N-dimethylformamide was prepared. These two solutions were then mixed with 1,4-butanediol diglycidyl ether to produce adhesive composition (E). The reaction temperature was 140°C, and the reaction time was 3 hours.

[0092] Examples 2 to 4, Comparative Examples 1 to 4 As in Example 1, adhesive compositions (E) of Examples 2 to 4 and Comparative Examples 1 to 4 were prepared using 100 parts by mass of polyester resin (A-1) as the base material, and the materials were changed as shown in Table 3. The viscosity of the resulting adhesive composition (E) was measured by the following procedure.

[0093] <Viscosity> The viscosity of the adhesive composition (E) was measured using an E-type viscometer (TVE-25H) and a cone rotor (3° x R12) manufactured by Toki Sangyo Co., Ltd. at 25°C, 5 rpm, and for 1 minute. The measurement results are also shown in Table 3 below. In Table 3 below, "-" indicates that the polyester resin (A) was insoluble in the organic solvent (F).

[0094] This adhesive composition (E) was formed into a film by the method described below, and samples for evaluating peel strength and normal solder heat resistance were prepared. During the preparation of the evaluation samples, the film-forming properties of adhesive composition (E) were evaluated. In addition, the evaluation samples were used to evaluate peel strength and normal solder heat resistance according to the following procedures. The evaluation results are shown in Table 3.

[0095] <Method of preparing evaluation samples> The adhesive composition (E) was applied to a 12.5 μm thick polyimide film (Apical (registered trademark), manufactured by Kaneka Corporation) so that the thickness after drying was 25 μm. After drying at 80°C for 1 minute and at 140°C for 2 minutes, the film was cured by sequential heat treatments at 130°C for 1 hour, 140°C for 1 hour, and 150°C for 3 hours to obtain an adhesive sheet, which was a laminate of an adhesive layer and a polyimide film. A 49 μm thick copper-clad laminate (ESPANEX series, Cu / polyimide / Cu = 12 / 25 / 12 μm, manufactured by Nippon Steel Chemical & Material Co., Ltd.) was bonded to the adhesive layer surface of the adhesive sheet. A pressure of 20.4 kgf / cm at 170°C was measured. ２ The adhesive was pressed under a pressure of 100 psi for 280 seconds to obtain a sample for evaluation of peel strength and normal solder heat resistance.

[0096] <Film-forming properties> In the above-mentioned process for preparing the evaluation sample, adhesive composition (E) was applied to a 12.5 μm thick polyimide film so that the thickness after drying would be 25 μm. Immediately after that, the state of the coating surface was visually observed, and the film-forming properties of adhesive composition (E) were evaluated. (Evaluation criteria) A: Good coating appearance B: Coating possible, but poor appearance due to insoluble residue C: Insoluble residue present, poor solubility making coating impossible

[0097] <Peel Strength> The evaluation samples were subjected to a 90° peel test at 25°C, with the polyimide film pulled at a tensile speed of 50 mm / min, to measure the peel strength. This test indicates the adhesive strength at room temperature between the adhesive layer formed from the adhesive composition (E) and the copper-clad laminate. In all samples, peeling occurred at the interface between the adhesive layer formed from the adhesive composition (E) and the copper-clad laminate, but not between the adhesive layer formed from the adhesive composition (E) and the polyimide film. Therefore, although the adhesive strength between the adhesive layer formed from the adhesive composition (E) and the polyimide film was not measured, it was found to be higher than the adhesive strength between the adhesive layer formed from the adhesive composition (E) and the copper-clad laminate. In Table 3 below, "-" indicates that evaluation was not possible. (Evaluation Criteria) A: 15 N / cm or more B: 10 N / cm or more, less than 15 N / cm C: 7 N / cm or more, less than 10 N / cm D: Less than 7 N / cm

[0098] <Normal Solder Heat Resistance> After leaving the evaluation sample at a temperature of 25°C and a humidity of 50% RH for 24 hours, the evaluation sample was floated in a heated solder bath for 1 minute so that the copper-clad laminate side of the evaluation sample was in contact with the solder bath, and the upper limit temperature at which no blistering occurred on the surface of the polyimide film was measured in 10°C increments. Specifically, the temperature was increased from 260°C to 280°C. In this test, a higher measured value indicates better heat resistance. In Table 3 below, "-" indicates that the evaluation was not possible. (Evaluation Criteria) A: No blistering at 280°C B: No blistering at 270°C, but blistering occurred at 280°C C: No blistering at 260°C, but blistering occurred at 270°C D: Blistering occurred at 260°C

[0099]

[0100] As is clear from Table 3, in Examples 1 to 4, the RED value of the organic solvent (F) for the polyester resin (A) was 1.0 or less and the RED value of the organic solvent (G) for the transesterification catalyst (C) was 1.5 or less, so there was no residual dissolution of the polyester resin (A) or the transesterification catalyst (C), and the film-forming properties, adhesion, and normal solder heat resistance were good. In contrast, in Comparative Examples 1 and 2, the RED value of the organic solvent (F) for the polyester resin (A) was greater than 1.0, so the polyester resin (A) did not dissolve and could not be coated, making it impossible to evaluate adhesion and normal solder heat resistance. In Comparative Examples 3 and 4, the RED value of the organic solvent (F) for the polyester resin (A) was 1.0 or less, but the RED value of the organic solvent (G) for the transesterification catalyst (C) was greater than 1.5. As a result, the transesterification catalyst (C) remained undissolved, and when the adhesive composition (E) was applied, the undissolved transesterification catalyst (C) precipitated on the surface, resulting in poor coating appearance and poor film-forming properties, as well as normal solder heat resistance of 270°C or less.

[0101] The adhesive composition of the present invention can provide an adhesive composition that can form an adhesive layer with good film-forming properties and good heat resistance by selecting an organic solvent that dissolves the polyester resin and an organic solvent that dissolves the transesterification catalyst using Hansen solubility parameters.

Claims

1. An adhesive composition (E) containing a polyester resin (A), an epoxy compound (B), an ester exchange catalyst (C), and an organic solvent (D), and satisfying the following (1) to (4). (1) The polyester resin (A) has a carboxy group in a side chain. (2) The organic solvent (D) is composed of at least an organic solvent (F) and an organic solvent (G). (3) The organic solvent (F) is composed of one organic solvent or a mixture of two or more organic solvents, and has a relative energy difference (RED) of 1.0 or less with respect to the polyester resin (A). (4) The organic solvent (G) is composed of one organic solvent or a mixture of two or more organic solvents, and has a relative energy difference (RED) of 1.5 or less with respect to the ester exchange catalyst (C). The relative energy difference (RED) is a numerical value represented by the following formula (1). Formula (1) RED=R ａ－ｂ / R ０ (In the above formula (1), R ０ is the interaction radius of the solute, R ａ－ｂ is the distance between the Hansen Solubility Parameter (HSP) values ​​of the solute and the solvent.

2. The adhesive composition (E) according to claim 1, further satisfying the following (5): (5) The molar ratio of the transesterification catalyst (C) to the carboxy groups of the polyester resin (A) (carboxy groups:transesterification catalyst) is 100:10 to 100:

40.

3. The adhesive composition (E) according to claim 1, wherein the organic solvent (F) for dissolving the polyester resin (A) is at least one selected from the group consisting of aromatic organic solvents, alicyclic organic solvents, ketone organic solvents, ether organic solvents, amide organic solvents and halogenated organic solvents.

4. The adhesive composition (E) according to claim 1, wherein the organic solvent (F) for dissolving the polyester resin (A) is at least one selected from the group consisting of toluene, tetrahydrofuran, 1,4-dioxane, methyl ethyl ketone, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dichloromethane and chloroform.

5. The adhesive composition (E) according to claim 1, wherein the organic solvent (G) for dissolving the ester exchange catalyst (C) is at least one selected from the group consisting of amide-based organic solvents, alcohol-based organic solvents, aprotic organic solvents and ketone-based organic solvents.

6. The adhesive composition (E) according to claim 1, wherein the organic solvent (G) for dissolving the transesterification catalyst (C) is at least one selected from the group consisting of N,N-dimethylformamide, N-methyl-2-pyrrolidone, methanol, dimethyl sulfoxide, acetone, γ-butyrolactone, and acetonitrile.

7. An adhesive composition (E) according to claim 1, wherein the acid value of the polyester resin (A) is from 5 mg KOH / g to 120 mg KOH / g.

8. The adhesive composition (E) according to claim 1, having a viscosity of 20 Pa·s or less at 25°C and 5 rpm.

9. An adhesive sheet comprising a cured product of the adhesive composition (E) according to any one of claims 1 to 8.

10. A printed wiring board comprising the adhesive sheet according to claim 9 as a component.

11. A method for producing an adhesive composition (E), comprising: a step S1 of dissolving a polyester resin (A) in an organic solvent (F) having a relative energy difference (RED) of 1.0 or less to the polyester resin (A) to produce a polyester resin solution (SA); a step S2 of dissolving a transesterification catalyst (C) in an organic solvent (G) having a relative energy difference (RED) of 1.5 or less to the transesterification catalyst (C) to produce a transesterification catalyst solution (SC); and a step S3 of mixing at least the polyester resin solution (SA), the transesterification catalyst solution (SC), and an epoxy compound (B) to produce an adhesive composition (E).

12. A method for producing an adhesive sheet, comprising: step T1 of applying the adhesive composition (E) obtained by the production method according to claim 11 to a substrate to produce a coating film; step T2 of heating the coating film to remove at least a portion of the organic solvent to produce a dry coating film; and step T3 of further heating the dry coating film to generate a crosslinked polyester resin and produce an adhesive layer.

13. A method for producing a laminate, comprising step U1 of bonding the adhesive sheet obtained by the method according to claim 12 and an adherend under heat and pressure, followed by cooling to produce a laminate.

Images