Resin composition, adhesive film, laminate, and printed wiring board

Abstract

To provide a resin composition having heat resistance, good ability to embed into concavities and convexities of a wiring board, and flame retardancy. To provide an adhesive film containing the resin composition, a laminate including the adhesive film and a substrate, and a printed wiring board including the laminate.　The resin composition 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 has been crosslinked by an epoxy crosslinking agent (B) that includes an epoxy compound (b1) having two epoxy groups and no tertiary amino groups in the molecule and an epoxy-amine compound (b2) having two or more epoxy groups and one or more tertiary amino groups in the molecule; a transesterification catalyst (D); and a flame retardant (E).

Description

Resin composition, adhesive film, laminate, printed wiring board

[0001] The present invention relates to a resin composition, an adhesive film containing the resin composition, a laminate containing the adhesive film and a substrate, and a printed wiring board containing the laminate.

[0002] Epoxy adhesives have been studied as adhesives used to bond electronic circuit boards, flexible printed circuit boards (hereinafter sometimes abbreviated as FPCs), etc. Adhesives used in these applications are required to have good adhesion to the substrate material as well as heat resistance capable of withstanding high temperatures of 220°C or higher (particularly 260°C or higher), which are the conditions for solder reflow during component mounting.

[0003] In recent years, adhesive films in the form of a film of adhesive have come to be used for such applications. Adhesive films used for such applications are required to suppress a decrease in connection reliability caused by thermal stress resulting from the use of various materials with different thermal expansion coefficients, and to improve embedding properties for unevenness in wiring boards. Patent Document 1 proposes an adhesive film that combines acrylic rubber with an aliphatic or alicyclic epoxy resin as an adhesive film that satisfies these requirements. Patent Document 2 also proposes a cross-linked polyester resin that has high adhesion to metal substrates and can provide high heat resistance.

[0004] JP 2011-159693 A International Publication No. 2023 / 063386

[0005] Depending on the application of the adhesive film, it may be desirable for the adhesive film to have flame retardancy. However, Patent Documents 1 and 2 discuss the heat resistance of the adhesive film and its ability to embed into the irregularities of a wiring board, but do not discuss flame retardancy. According to the inventor's investigation, the addition of a flame retardant tends to reduce heat resistance. Attempting to improve heat resistance tends to reduce embeddability. For this reason, it has been difficult to satisfy all of the flame retardancy, heat resistance, and embeddability.

[0006] An object of the present invention is to provide a resin composition that has heat resistance, good embedding properties into irregularities in wiring boards, and flame retardancy. Another object of the present invention is to provide an adhesive film containing the resin composition, a laminate containing the adhesive film and a substrate, and a printed wiring board containing the laminate.

[0007] The present invention is as follows. [1] A resin composition containing: a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having a carboxy group at its side chain are crosslinked with an epoxy-based crosslinking agent (B) including an epoxy compound (b1) having two epoxy groups and no tertiary amino group in the molecule and an epoxy amine compound (b2) having two or more epoxy groups and one or more tertiary amino groups in the molecule; a transesterification catalyst (D); and a flame retardant (E). [2] The resin composition according to [1], wherein the epoxy amine compound (b2) has 2 to 4 epoxy groups in the molecule. [3] The resin composition according to [1] or [2], wherein the epoxy amine compound (b2) 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. [4] The resin composition according to any one of [1] to [3], wherein the epoxy compound (b1) is an aliphatic epoxy compound. [5] The resin composition according to any one of [1] to [4], wherein the flame retardant (E) is an inorganic flame-retardant filler and / or an organic flame-retardant filler. [6] The resin composition according to any one of [1] to [5], wherein the flame retardant (E) is a phosphorus-based compound. [7] The resin composition according to any one of [1] to [6], further comprising an inorganic filler (F). [8] The resin composition according to [7], wherein the inorganic filler (F) is a silica filler. [9] The resin composition according to [7], wherein the inorganic filler (F) is hydrophobic silica.

[10] The resin composition according to any one of [7] to [9], wherein the inorganic filler (F) is contained in an amount of 2 to 50 parts by mass per 100 parts by mass of the polyester resin (A).

[11] An adhesive film comprising the resin composition according to any one of [1] to

[10] .

[12] A laminate comprising the adhesive film according to

[11] and a substrate.

[13] A printed wiring board comprising the laminate according to

[12] .

[14] The resin composition according to any one of [1] to

[10] , wherein the flame retardant (E) is insoluble in an organic solvent.

[0008] According to the present invention, there is provided a resin composition having heat resistance, good embedding properties in irregularities in a wiring board, and flame retardancy. Furthermore, according to the present invention, there are provided an adhesive film containing the resin composition, a laminate containing the adhesive film and a substrate, and a printed wiring board containing the laminate.

[0009] The resin composition of the present invention comprises a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having a carboxy group at its side chain are crosslinked with an epoxy-based crosslinking agent (B) including an epoxy compound (b1) having two epoxy groups in its molecule but no tertiary amino group, and an epoxy amine compound (b2) having two or more epoxy groups and one or more tertiary amino group in its molecule; a transesterification catalyst (D); and a flame retardant (E). The addition of a flame retardant (E) tends to adversely affect the heat resistance and embeddability of the resin composition. However, the inventors have found that crosslinking the side chain carboxy groups of the polyester resin (A) with an epoxy-based crosslinking agent (B) composed of an epoxy compound (b1) and an epoxy amine compound (b2) can achieve both a high crosslink density and heat-induced softening properties in the presence of the transesterification catalyst (D), thereby improving flame retardancy without reducing the heat resistance and embeddability of the resin composition. This finding led to the completion of the present invention. The present invention is described below.

[0010] (A) Polyester Resin Having a Carboxy Group in a Side Chain The polyester resin (A) has a carboxy group in a 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.

[0011] The structure of the polyester resin (A) having a carboxy group in a side chain [hereinafter, sometimes simply referred to as polyester resin (A)] may be a structure in which a carboxy group is present in 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 a carboxy group is present directly in the main chain of the polyester resin, with a structure in which a carboxy group is present directly in the main chain of the polyester resin being preferred.

[0012] 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.

[0013] 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 resin composition. 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 softening and 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.

[0014] 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.

[0015] The number of carboxy groups per polymer chain of the polyester resin (A) (N ＣＯＯＨ ) is, for example, about 2 to 60, preferably about 3 to 40, and more preferably about 4 to 20 per molecule of polyester resin (A) before crosslinking. The greater the number of carboxy groups, the more crosslinking points there are, and the better the heat resistance. Furthermore, if the number of carboxy groups is not too large, the toughness or elasticity will be good. The number of carboxy groups per polymer chain of polyester resin (A) may be determined by proton nuclear magnetic resonance (1H NMR).

[0016] 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.

[0017] 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.

[0018] The polyester resin (A) is preferably contained as a base component in the resin composition. In this specification, the term "base component" specifically refers to the component with the highest content in the solid content of the resin composition. The content of the polyester resin (A) in the resin composition of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the solid content of the adhesive composition. Furthermore, the content of the polyester resin (A) in the resin composition is preferably 99.0% by mass or less, more preferably 98.0% by mass or less, and even more preferably 97.5% by mass or less, based on 100% by mass of the solid content of the adhesive composition. That is, the content of the polyester resin (A) in the resin composition is preferably 50 to 99.0% by mass, more preferably 60 to 98.0% by mass, and even more preferably 70 to 97.5% by mass, based on 100% by mass of the solid content of the adhesive composition. A content within the above range is preferred because it provides good adhesion and heat resistance.

[0019] (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.

[0020] (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.

[0021] 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.

[0022] 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; and unsaturated bond-containing dicarboxylic acids such as fumaric acid, maleic acid, and their anhydrides. Thiomalic acid, which has a thiol group in its molecular structure, and biomass-derived 2,5-furandicarboxylic acid (FDCA) may also be used. These may be used alone or in combination of two or more.

[0023] (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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] (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.

[0030] (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.

[0031] 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.

[0032] 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.

[0033] 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 containing two or more polymer polyols having different number average molecular weights (Mn), the heat resistance of the resin composition can be further 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.

[0034] 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 resin composition 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).

[0035] 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 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 resin composition 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 100% by mass.

[0036] (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.

[0037] 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.

[0038] The amount ratio of the tri- or higher functional polycarboxylic acid component in the resin composition 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).

[0039] 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 resin composition 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 does not become too high, ester bond exchange occurs easily, and softening is sufficient, resulting in improved adhesion.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] (Chain extender) The polyester resin (A) may optionally contain a chain extender as a copolymerization component, as long as the above-mentioned effects are not impaired. The use of a chain extender can efficiently impart an acid value. As the chain extender, for example, a low molecular weight diol having a molecular weight of 1000 or less may be used. However, the low molecular weight diol having a molecular weight of 1000 or less does not include an aliphatic glycol. Examples of low molecular weight diols having a molecular weight of 1000 or less include dimethylolbutanoic acid.

[0045] The polymerization amount of the chain extender in the polyester resin (A) is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of the high molecular weight polyol (a). If the polymerization amount of the chain extender is too large, it may become difficult to increase the molecular weight, or reactions between the chain extenders may proceed, causing the varnish to become cloudy, etc.

[0046] (Reaction Catalyst) In producing the polyester resin (A), a reaction catalyst such as a quaternary ammonium salt or a tertiary amine 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. and 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 salts, etc.; 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.

[0047] (B) Epoxy-based Crosslinking Agent The epoxy-based crosslinking agent (B) contains an epoxy compound (b1) having two epoxy groups in the molecule and no tertiary amino group, and an epoxy amine compound (b2) having two or more epoxy groups and one or more tertiary amino group in the molecule. By containing both the epoxy compound (b1) and the epoxy amine compound (b2), the heat resistance is less likely to deteriorate even when a flame retardant is contained in the resin composition, and embeddability is also improved.

[0048] (b1) Epoxy Compound The epoxy compound (b1) is a compound having two epoxy groups in the molecule. However, among the compounds having two epoxy groups in the molecule, compounds having a tertiary amino group in addition in the molecule are excluded. By using the epoxy compound (b1), three-dimensional crosslinking is easily formed, and the heat resistance of the resin composition can be improved.

[0049] The epoxy compound (b1) 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 necessary. 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.

[0050] Examples of the epoxy compound (b1) 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.

[0051] The ratio of the epoxy compound (b1) in the resin composition may be 10 to 200 molar parts of the epoxy groups of the epoxy compound (b1) relative to 100 molar parts of the carboxy groups of the polyester resin (A). When the ratio of the epoxy groups of the epoxy compound (b1) in the resin composition is within the above range, the crosslinking density becomes appropriate, and softening of the resin composition can be promoted by heating. The ratio of the epoxy groups of the epoxy compound (b1) in the resin composition is more preferably 80 to 150 molar parts, and even more preferably 80 to 120 molar parts, relative to 100 molar parts of the carboxy groups of the polyester resin (A).

[0052] (b2) Epoxyamine Compound The epoxyamine compound (b2) is a compound having two or more epoxy groups and one or more tertiary amino groups in the molecule, and may contain an oxygen atom or a sulfur atom in the molecule as necessary.

[0053] The use of the epoxy amine compound (b2) can improve the heat resistance of the resin composition even when a flame retardant (E) is added. Crosslinking the side chain carboxyl groups of the polyester resin (A) with the epoxy-based crosslinking agent (B) composed of the epoxy amine compound (b2) and the epoxy compound (b1) can achieve both high crosslink density and softening upon heating, thereby achieving both heat resistance and embeddability of the resin composition even when a flame retardant is added. Furthermore, the tertiary amino group of the epoxy amine compound (b2) has a transesterification catalytic action similar to that of the transesterification catalyst (D). By heating the resin composition, the hydroxyl groups contained in the resin composition 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 and resulting in softening behavior.

[0054] The number of epoxy groups contained in the molecule of the epoxyamine compound (b2) is preferably 2 to 4, and more preferably 3 or 4. The number of tertiary amino groups contained in the molecule of the epoxyamine compound (b2) may be 2 or more, and is preferably 3 or less.

[0055] The epoxy amine compound (b2) 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. A diepoxidized amino group having two epoxy groups bonded to it via an alkylene group having 1 to 4 carbon atoms is preferred.

[0056] The number of epoxidized amino groups contained in the molecule of the epoxyamine compound (b2) 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 epoxyamine compound (b2) may be 2 to 5, or may be 3 or 4. The number of diepoxidized amino groups contained in the molecule of the epoxyamine compound (b2) may be 1, 2, or 3, preferably 1 or 2, and more preferably 2, i.e., diglycidylamino groups.

[0057] The epoxy amine compound (b2) 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 (b2) 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 (b2) has an aromatic ring, the number of aromatic rings may be one or two, and preferably three or less. When the epoxy amine compound (b2) 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.

[0058] Examples of the epoxy amine compound (b2) 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 or N,N,N',N'-tetraglycidyl-m-xylylenediamine is preferred.

[0059] The ratio of the epoxy groups in the epoxy amine compound (b2) in the resin composition may be 1 to 30 molar parts per 100 molar parts of the carboxy groups in the polyester resin (A). When the ratio of the epoxy groups in the epoxy amine compound (b2) in the resin composition is within the above range, the crosslinking density becomes appropriate, and softening of the resin composition can be promoted when heated. The ratio of the epoxy groups in the epoxy amine compound (b2) in the resin composition is more preferably 1 to 20 molar parts, and even more preferably 2 to 10 molar parts, per 100 molar parts of the carboxy groups in the polyester resin (A).

[0060] The mixing ratio of the epoxy groups of the epoxy compound (b1) to the epoxy groups of the epoxy amine compound (b2) in the resin composition [epoxy groups of the epoxy compound (b1) / epoxy groups of the epoxy amine compound (b2)] is preferably 2 to 70 molar parts relative to 100 molar parts of the carboxy groups of the polyester resin (A). The mixing ratio [epoxy groups of the epoxy compound (b1) / epoxy groups of the epoxy amine compound (b2)] is more preferably 4 to 65, and even more preferably 8 to 60.

[0061] (C) Crosslinked Polyester Resin The crosslinked polyester resin (C) is a resin having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups at their side chains are crosslinked with an epoxy-based crosslinking agent (B) containing an epoxy compound (b1) having two epoxy groups and no tertiary amino group in the molecule and an epoxy amine compound (b2) having two or more epoxy groups and one or more tertiary amino group in the molecule.

[0062] (D) Transesterification catalyst The transesterification catalyst (D) is a catalyst for transesterification of the ester group in the polyester resin (A) having a carboxy group in the side chain. By containing the transesterification catalyst (D), 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, it can be bonded to or embedded in a substrate, film, or wiring, and it also softens, which can suppress problems such as cracking and circuit distortion caused by the difference in thermal expansion between the insulating layer and the conductor layer, improving the embeddability of the resin composition.

[0063] Examples of the transesterification catalyst (D) include zinc acetate, zinc acetate anhydride, zinc 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 is preferred.

[0064] The quantitative ratio of the transesterification catalyst (D) in the resin composition is preferably 5 to 40 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 resin composition within the above range, softening of the resin composition can be promoted when heated. The quantitative ratio of the transesterification catalyst (D) in the resin composition is more preferably 10 to 30 molar parts, and even more preferably 10 to 20 molar parts, per 100 molar parts of the carboxy groups of the polyester resin (A).

[0065] (E) Flame Retardant The resin composition can be imparted with flame retardancy by containing a flame retardant (E). The flame retardant (E) is not particularly limited as long as it can make the resin composition flame retardant when added to the resin composition, but is preferably one that is insoluble in organic solvents.

[0066] The flame retardant (E) may be, for example, a flame-retardant filler, and examples of the flame-retardant filler include inorganic flame-retardant fillers and organic flame-retardant fillers. The inorganic flame-retardant fillers and organic flame-retardant fillers may be used alone or in combination.

[0067] Examples of inorganic flame-retardant fillers include metal oxides such as magnesium oxide, molybdenum oxide, zirconium oxide, tin oxide, tin oxide hydrate, and antimony oxide; metal hydroxide compounds such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide, and barium hydroxide; metal carbonate compounds such as basic magnesium carbonate, zinc carbonate, magnesium-calcium carbonate (a mixture of magnesium carbonate and calcium carbonate), calcium carbonate, and barium carbonate; metal borate compounds such as zinc borate, zinc metaborate, and barium metaborate; inorganic metal compounds such as dolomite, hydrotalcite, and borax; and inorganic phosphorus compounds such as red phosphorus. These may be used alone or in combination of two or more.

[0068] Examples of the organic flame-retardant filler include phosphorus-based compounds such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amido phosphate, ammonium amido polyphosphate, carbamate phosphate, carbamate polyphosphate, aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, and titanium tetrakisdiphenylphosphinate; nitrogen-based compounds such as triazine-based compounds (e.g., melamine, melam, melamine cyanurate, etc.), cyanuric acid compounds, isocyanuric acid compounds, triazole-based compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based compounds such as silicone compounds and silane compounds. These may be used alone or in combination of two or more.

[0069] Among these, metal hydroxide compounds or phosphorus-based compounds are preferred, and phosphorus-based compounds are more preferred. Among the phosphorus-based compounds, aluminum phosphinates such as aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, and aluminum trisdiphenylphosphinate are more preferred. Phosphorus-based compounds are commercially available, for example, as "EXOLIT (registered trademark) OP-935" from Clariant Chemicals K.K. Note that phosphorus-based compounds include those that are insoluble in organic solvents (phosphorus-based flame-retardant fillers) and those that are soluble in organic solvents (phosphorus-based flame-retardant non-fillers), and it is preferable to use those that are insoluble in organic solvents (phosphorus-based flame-retardant fillers).

[0070] The average particle size of the flame retardant (E) may be, for example, 1 to 50 μm, more preferably 2 to 30 μm, and even more preferably 3 to 10 μm. The maximum particle size of the flame retardant (E) may be, for example, 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less. The particle size (median size) of the flame retardant (E) can be measured on a volume basis using a laser diffraction / scattering particle size distribution analyzer.

[0071] The amount of the flame retardant (E) in the resin composition is preferably 1 to 50 parts by mass per 100 parts by mass of the polyester resin (A). By setting the amount of the flame retardant (E) in the resin composition within the above range, the flame retardancy of the resin composition can be improved. The amount of the flame retardant (E) in the resin composition is more preferably 5 to 40 parts by mass, and even more preferably 10 to 40 parts by mass per 100 parts by mass of the polyester resin (A).

[0072] (F) Inorganic Filler The resin composition may further contain an inorganic filler (F). By containing the inorganic filler (F), heat resistance under humid conditions can be improved. The inorganic filler (F) does not need to exhibit flame retardancy, and inorganic fillers that exhibit flame retardancy are excluded.

[0073] As the inorganic filler (F), for example, a filler may be used. Examples of fillers include silica fillers (hereinafter simply referred to as silica). Known silicas include hydrophilic silica and hydrophobic silica. Examples of hydrophilic silica include untreated silica, and silica having silanol groups or siloxanes on the surface may also be used. Examples of hydrophobic silica include silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc. The use of hydrophobic silica can impart moisture absorption resistance to the resin composition. Among these, hydrophobic silica is preferred. Hydrophobic silica is commercially available, for example, from Nippon Aerosil Co., Ltd. under the name "AEROSIL (registered trademark) R972."

[0074] The average particle size of the inorganic filler (F) may be, for example, 0.001 to 10 μm, more preferably 0.002 to 0.5 μm, and even more preferably 0.01 to 0.1 μm. The average particle size (median size) of the inorganic filler (F) can be measured on a volume basis using a laser diffraction / scattering particle size distribution analyzer.

[0075] The amount of the inorganic filler (F) in the resin composition is not particularly limited, but is preferably 2 to 50 parts by mass, more preferably 4 to 40 parts by mass, even more preferably 6 to 30 parts by mass, particularly preferably 6 to 20 parts by mass, and most preferably 6 to 15 parts by mass, relative to 100 parts by mass of the polyester resin (A).

[0076] The resin composition can be obtained by mixing a polyester resin (A) having a carboxy group in a side chain, an epoxy-based crosslinking agent (B), a transesterification catalyst (D), and a flame retardant (E), heating the mixture, and carrying out a crosslinking reaction via an epoxy ring-opening reaction. The heating temperature is preferably 80 to 200°C, more preferably 85 to 180°C, and even more preferably 90 to 150°C. The heating time, although it depends on the heating temperature, is preferably 30 minutes to 10 hours, more preferably 1 to 8 hours, and even more preferably 2 to 5 hours.

[0077] 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.

[0078] The 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 in the epoxy-based crosslinking agent (B). From the viewpoints of crosslinking reaction efficiency and softening the crosslinked polyester resin (C), 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).

[0079] (Adhesive Film) The present invention also encompasses an adhesive film containing the resin composition. The adhesive film may have an adhesive layer made of the resin composition, and may be a single-layer film obtained by processing the resin composition into a film, or a two-layer or more film having an adhesive layer made of the resin composition and other layers such as a substrate layer or a release layer. The adhesive film may have two or more adhesive layers made of the resin composition.

[0080] For example, an adhesive film can be obtained by applying a resin composition to a release substrate and drying it according to a conventional method, thereby forming an adhesive film in which an adhesive layer made of the resin composition is laminated on the surface of the release substrate. Furthermore, by attaching a second release substrate to the adhesive layer after drying, the film can be wound up without causing transfer to the release substrate, resulting in excellent operability, and the adhesive layer is protected, resulting in excellent storage stability and ease of use. Furthermore, by applying the resin composition to a release substrate and drying it, the adhesive layer can be attached to another substrate, allowing the adhesive layer itself to be transferred to another substrate.

[0081] Examples of release substrates include those obtained by providing a coating layer of a filler such as clay, polyethylene, or polypropylene on the surface (one or both sides) of paper such as fine paper, kraft paper, roll paper, or glassine paper, and then coating the coating layer with a silicone-based, fluorine-based, or alkyd-based release agent. Other examples include various olefin films such as polyethylene, polypropylene, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer alone, as well as films such as polyethylene terephthalate and polyethylene naphthalate, to which the release agent is applied. Due to factors such as the release force between the release substrate and the adhesive layer and the adverse effect of silicone on electrical properties, it is preferable to use polypropylene to seal the surface of fine paper (particularly both sides) and then coat the polypropylene with an alkyd-based release agent, or to use polyethylene terephthalate films to which an alkyd-based release agent is applied.

[0082] The method for applying the resin composition to the release substrate is not particularly limited, but examples thereof include a comma coater, a reverse roll coater, etc. If necessary, an adhesive layer may be provided directly or by transfer onto a rolled copper foil or a polyimide film, which is a material constituting the printed wiring board.

[0083] The thickness of the adhesive layer may be changed as needed, but is preferably 5 to 200 μm, for example. When the thickness of the adhesive layer is 5 μm or more, sufficient adhesive strength can be obtained.

[0084] (Laminate) The present invention also encompasses a laminate comprising the above adhesive film and a substrate. Examples of the laminate include a laminate in which an adhesive film is laminated on a substrate (a two-layer laminate of substrate / adhesive film), or a laminate in which a substrate is further laminated (a three-layer laminate of substrate / adhesive film / substrate). The adhesive film refers to an adhesive layer made of a resin composition obtained by applying a resin composition to a substrate and drying it, or an adhesive layer made of a resin composition obtained by laminating an adhesive layer of an adhesive film made using the resin composition on a substrate.

[0085] Examples of the substrate include a resin substrate such as a film-like resin, a metal substrate such as a metal plate or a metal foil, paper, a composite material, etc., and a resin substrate is preferred, and a film-like resin (hereinafter also referred to as a substrate film layer) is more preferred. By using a resin substrate, the adhesive strength and durability with the adhesive layer constituting the adhesive film can be improved.

[0086] Examples of materials for the resin substrate include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluororesin.

[0087] The metal substrate may be made of any conventionally known conductive material that can be used for circuit boards. Examples of conductive materials include various metals such as stainless steel (SUS), copper, aluminum, iron, steel, zinc, and nickel, as well as alloys, plated products, and metals treated with other metals such as zinc or chromium compounds. Among these, stainless steel, copper, and aluminum are preferred from the standpoint of adhesion to the adhesive layer of the adhesive film and durability. Foils of the above-mentioned conductive materials are preferred as the metal substrate, and copper foil is more preferred. Copper foils manufactured by rolling or electrolysis can be used. The conductive foil may be subjected to a physical surface treatment such as roughening or a chemical surface treatment such as acid washing to ensure adhesion to the adhesive film. The thickness of the conductive foil is not particularly limited, but is preferably 1 to 50 μm, more preferably 3 to 30 μm, and even more preferably 10 to 20 μm. If the conductive foil is too thin, it may be difficult to obtain sufficient electrical performance of the circuit. If the conductive foil is too thick, processing efficiency during circuit fabrication may be reduced.

[0088] Examples of papers include fine paper, kraft paper, roll paper, and glassine paper.

[0089] An example of the composite material is glass epoxy.

[0090] (Printed Wiring Board) The present invention also includes a printed wiring board including the laminate described above. The printed wiring board includes, as a component, a laminate formed from a foil of a conductive material that forms a conductor circuit and a resin substrate.

[0091] Printed wiring boards are manufactured by conventional methods such as subtractive processes using metal-clad laminates. Printed wiring boards are a general term for flexible circuit boards (FPCs), flat cables, and circuit boards for tape automated bonding (TAB), in which a conductor circuit formed from a foil of a conductive material is partially or entirely covered with a cover film, screen printing ink, or the like, as needed.

[0092] The printed wiring board 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 conductive material 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 conductive material layer, an adhesive layer, and a cover film layer. Furthermore, if necessary, it can also be a structure in which two or more of the above-mentioned printed wiring boards are laminated.

[0093] The printed wiring board can be produced, for example, by heating an adhesive film containing a resin composition and a substrate to a temperature equal to or higher than the softening start temperature of the resin composition and laminating them together. That is, for example, by laminating the materials for each of the above-mentioned layers, and then heating them to a temperature equal to or higher than the softening start temperature of the resin composition and laminating them together, each member can be laminated without performing a curing treatment due to the properties of the polyester resin (A), and a printed wiring board can be obtained.

[0094] Examples of printed wiring boards include a product in which a conductive material layer is laminated onto a substrate film layer to form a desired circuit pattern (hereinafter referred to as a "substrate film-side two-layer product"), or a product in which a resin composition layer is laminated onto a substrate film layer, and a conductive material layer is laminated on top of that to form a desired circuit pattern (hereinafter referred to as a "substrate film-side three-layer product"). Hereinafter, the "substrate film-side two-layer product" and the "substrate film-side three-layer product" may be collectively referred to as the "substrate film-side product." By laminating the substrate film-side products thus obtained, a four-layer or five-layer printed wiring board can be obtained. Conventional methods can be used to form the circuit pattern, such as additive methods and subtractive methods, with subtractive methods being preferred.

[0095] The printed wiring board may be, for example, a reinforcing material-side product produced by applying a resin composition to a soft, rewound reinforcing material such as a polyimide film. When the reinforcing material is a hard, non-rewound material, such as a metal plate (e.g., SUS, aluminum), or a plate made of glass fiber cured with an epoxy resin, it is preferable to produce the board by transfer-coating a resin composition that has been previously applied to a release substrate. If necessary, a crosslinking reaction can be carried out in the applied resin composition. The obtained reinforcing material-side product may be used as is for bonding to the back surface of a printed wiring board, or it may be used for bonding to a substrate film-side product after being attached with a release film and stored.

[0096] This application claims the benefit of priority based on Japanese Patent Application No. 2024-029461, filed on February 29, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-029461 are incorporated herein by reference.

[0097] 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.

[0098] First, a long-chain high molecular weight polyol (a1) and a short-chain high molecular weight polyol (a2) were polymerized with a tri- or higher functional polycarboxylic acid component to produce a polyester resin (A) having carboxy groups in the side chains.

[0099] (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.

[0100] (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.

[0101] 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.

[0102] (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.

[0103] (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).

[0104] (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.

[0105]

[0106] (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.

[0107] The number average molecular weight (Mn), acid value, and glass transition temperature of the obtained polyester resin (A-1) were measured using the procedures described above in (i) to (iii). These physical property values ​​are shown in Table 2. Furthermore, the number of carboxy groups per polymer chain of the obtained polyester resin (A-1) was determined by proton nuclear magnetic resonance (H NMR). The measurement was performed using a Bruker Analytik DPX400 spectrometer (400 MHz), deuterated DMSO as the measurement solvent, and at a measurement temperature of 25°C. The results are shown in Table 2.

[0108]

[0109] Next, a mixture (a resin composition before crosslinking) was produced using the obtained polyester resin (A-1), an epoxy crosslinking agent (B) containing an epoxy compound (b1) having two epoxy groups in the molecule but no tertiary amino group, and an epoxy amine compound (b2) having two or more epoxy groups and one or more tertiary amino groups in the molecule, a transesterification catalyst (D-1), and a flame retardant (E-1). Furthermore, an inorganic filler (F-1) was used as needed. The following compounds were used as the epoxy compound (b1) and epoxy amine compound (b2), transesterification catalyst (D-1), flame retardant (E-1), and inorganic filler (F-1) constituting the epoxy crosslinking agent (B). The compounds used in the comparative examples are also shown below.

[0110] Epoxy compound (b1-1): 1,4-butanediol diglycidyl ether (hereinafter sometimes referred to as BDE) was used as "Epogose (registered trademark) BD" manufactured by Yokkaichi Chemical Co., Ltd. 1,4-butanediol diglycidyl ether (BDE) is classified as an epoxy compound (b1). The number of epoxy groups in the molecule is two. Epoxy amine compound (b2-1): Triglycidyl paraaminophenol was used as "jER630" manufactured by Mitsubishi Chemical Corporation. Triglycidyl paraaminophenol is classified as an epoxy amine compound (b2). The number of epoxy groups in the molecule is three and the number of tertiary amino group in the molecule is one. Epoxy amine compound (b2-2): N,N,N',N'-tetraglycidyl-m-xylylenediamine was used as a multifunctional epoxy compound "TETRAD-X" manufactured by Mitsubishi Gas Chemical Company, Inc. N,N,N',N'-tetraglycidyl-m-xylylenediamine is classified as an epoxy amine compound (b2). The number of epoxy groups in the molecule is four, and the number of tertiary amino groups in the molecule is two. "Denacol EX-321" manufactured by Nagase ChemteX Corporation: "Denacol EX-321" is a mixture of an aliphatic epoxy compound having two epoxy groups in the molecule but no tertiary amino group, and an aliphatic epoxy compound having three epoxy groups in the molecule but no tertiary amino group, and is not classified as either an epoxy compound (b1) or an epoxy amine compound (b2). Transesterification catalyst (D-1): "Zinc acetate anhydrous (Zn(OAc) ２ ")" was used. Flame retardant (E-1): "EXOLIT (registered trademark) OP-935" manufactured by Clariant Japan Co., Ltd. was used. "EXOLIT (registered trademark) OP-935" is a phosphorus-based compound that is not soluble in organic solvents. Inorganic filler (F-1): "AEROSIL (registered trademark) R972" manufactured by Nippon Aerosil Co., Ltd. was used. "AEROSIL (registered trademark) R972" is hydrophobic silica with an average particle size of 0.016 μm.

[0111] Example 1: Solution 1 was prepared by dissolving 100 parts by mass of polyester resin (A-1), 9.1 parts by mass of flame retardant (E-1), and 8.3 parts by mass of inorganic filler (F-1) in a mixed solvent of methyl ethyl ketone and toluene, and solution 2 was prepared by dissolving 1.1 parts by mass of transesterification catalyst (D) in N,N-dimethylformamide per 100 parts by mass of polyester resin (A-1). Mixing solution 1, solution 2, and 3 parts by mass of epoxy compound (b1-1) per 100 parts by mass of polyester resin (A-1), and 0.06 parts by mass of epoxy amine compound (b2-1) per 100 parts by mass of polyester resin (A-1) produced mixture 1. The amount of transesterification catalyst (D) was 20 parts by mole per 100 parts by mole of carboxy groups in polyester resin (A-1). The amount of epoxy groups in epoxy compound (b1-1) was 98 parts by mole per 100 parts by mole of carboxy groups in polyester resin (A-1). The amount of epoxy groups in the epoxy amine compound (b2-1) was 2 parts by mole relative to 100 parts by mole of carboxy groups in the polyester resin (A-1). The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 82.3% by mass.

[0112] Example 2 Mixture 2 was produced under the same conditions as Example 1, except that the amount of epoxy compound (b1-1) per 100 parts by mass of polyester resin (A-1) was changed from 3 parts by mass to 2.9 parts by mass, and the amount of epoxy amine compound (b2-1) per 100 parts by mass of polyester resin (A-1) was changed from 0.06 parts by mass to 0.14 parts by mass. The amount of epoxy groups in epoxy compound (b1-1) per 100 parts by mass of carboxy groups in polyester resin (A-1) was 95 parts by mole. The amount of epoxy groups in epoxy amine compound (b2-1) per 100 parts by mole of carboxy groups in polyester resin (A-1) was 5 parts by mole. The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 82.3% by mass.

[0113] Example 3 Mixture 3 was produced under the same conditions as Example 1, except that the amount of epoxy compound (b1-1) per 100 parts by mass of polyester resin (A-1) was changed from 3 parts by mass to 2.7 parts by mass, and 0.27 parts by mass of epoxy amine compound (b2-2) per 100 parts by mass of polyester resin (A-1) was used instead of epoxy amine compound (b2-1). The amount of epoxy groups in epoxy compound (b1-1) was 90 parts by mole per 100 parts by mole of carboxy groups in polyester resin (A-1). The amount of epoxy groups in epoxy amine compound (b2-2) was 10 parts by mole per 100 parts by mole of carboxy groups in polyester resin (A-1). The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 82.3% by mass.

[0114] Example 4 Mixture 4 was produced under the same conditions as in Example 1, except that solution 3, prepared by dissolving 100 parts by mass of polyester resin (A-1) and 9.1 parts by mass of flame retardant (E-1) in a mixed solvent of methyl ethyl ketone and toluene, was used instead of solution 1 in Example 1. The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 88.3% by mass.

[0115] (Comparative Example 11) Solution 11 was prepared by dissolving 100 parts by mass of polyester resin (A-1) in a mixed solvent of methyl ethyl ketone and toluene, and Solution 2 was prepared by dissolving 1.1 parts by mass of transesterification catalyst (D) in N,N-dimethylformamide per 100 parts by mass of polyester resin (A-1). Solution 11, Solution 2, and 3 parts by mass of epoxy compound (b1-1) per 100 parts by mass of polyester resin (A-1) were mixed to produce Mixture 11. The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 96.1% by mass.

[0116] (Comparative Example 12) Solution 12 was prepared by dissolving 100 parts by mass of polyester resin (A-1) and 9.1 parts by mass of flame retardant (E-1) in a mixed solvent of methyl ethyl ketone and toluene, and Solution 2 was prepared by dissolving 1.1 parts by mass of transesterification catalyst (D) in N,N-dimethylformamide per 100 parts by mass of polyester resin (A-1). Solution 12, Solution 2, and 3 parts by mass of epoxy compound (b1-1) per 100 parts by mass of polyester resin (A-1) were mixed to produce Mixture 12. The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 88.3% by mass.

[0117] (Comparative Example 13) Solution 12 was prepared by dissolving 100 parts by mass of polyester resin (A-1) and 9.1 parts by mass of flame retardant (E-1) in a mixed solvent of methyl ethyl ketone and toluene, and Solution 2 was prepared by dissolving 1.1 parts by mass of transesterification catalyst (D) in N,N-dimethylformamide per 100 parts by mass of polyester resin (A-1). Solution 12, Solution 2, and 3.9 parts by mass of "Denacol EX-321" per 100 parts by mass of polyester resin (A-1) were mixed to produce Mixture 13. The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 87.6% by mass.

[0118] (Comparative Example 14) Solution 12 was prepared by dissolving 100 parts by mass of polyester resin (A-1) and 9.1 parts by mass of flame retardant (E-1) in a mixed solvent of methyl ethyl ketone and toluene, and Solution 2 was prepared by dissolving 1.1 parts by mass of transesterification catalyst (D) in N,N-dimethylformamide per 100 parts by mass of polyester resin (A-1). Solution 12, Solution 2, and 2.9 parts by mass of epoxyamine compound (b2-1) per 100 parts by mass of polyester resin (A-1) were mixed to produce Mixture 14. The content of polyester resin (A) in 100% by mass of the solids content of the adhesive composition was 88.4% by mass.

[0119] The compositions of mixtures 1 to 4 and 11 to 14 are shown in the following Table 3. Table 3 also shows the calculated mixing ratio of the epoxy group of the epoxy compound (b1) to the epoxy group of the epoxy amine compound (b2) in the mixture [epoxy group of epoxy compound (b1) / epoxy group of epoxy amine compound (b2)].

[0120]

[0121] Next, the obtained mixture was applied to a substrate and dried to produce a laminate consisting of an adhesive film (adhesive layer) and the substrate. Specifically, the obtained mixture was applied to a 12.5 μm thick polyimide film (Apical (registered trademark) manufactured by Kaneka Corporation) so that the thickness after drying would be 25 μm, heated at 80 ° C for 1 minute, then heated at 140 ° C for 2 minutes to dry, and then heated at 150 ° C for 3 hours to cure, thereby obtaining a laminate consisting of an adhesive film containing a resin composition and the substrate.

[0122] The obtained laminate was used to evaluate the flame retardancy of the adhesive film. The flame retardancy of the adhesive film was evaluated by preparing a test piece based on the UL94 standard from the obtained laminate and conducting a combustion test based on the VTM method. As a result of the combustion test, if the VTM-0 condition was met, the film was judged as passing, and was given an evaluation of A. On the other hand, if the VTM-1 condition or VTM-2 condition was met, the film was judged as failing, and was given an evaluation of B. The evaluation results are shown in Table 3.

[0123] Next, the heat resistance of the adhesive film was evaluated using the obtained laminate. Specifically, a copper-clad laminate (manufactured by Nippon Steel Chemical & Material Co., Ltd., ESPANEX series, Cu / polyimide / Cu=12 μm / 25 μm / 12 μm) having a thickness of 49 μm was attached to the surface of the adhesive film (adhesive layer) of the obtained laminate, and the laminate was subjected to a pressure of 20.4 kgf / cm at 170°C. ２The test pieces were pressed and bonded under a pressure of 2 MPa for 280 seconds to produce test pieces for evaluating heat resistance. The obtained test pieces for evaluating heat resistance were placed in an oven and heated to 120°C for 30 minutes to dry. Immediately after removal from the oven, the test pieces (dried test pieces) in a low-moisture state were floated in a solder bath and visually observed for the presence or absence of blistering. The dried test pieces were floated so that the Cu of the copper-clad laminate was in contact with the solder. The initial temperature of the solder bath was 260°C. If no blistering occurred on the surface of the polyimide film after floating the dried test piece in the 260°C solder bath for 1 minute, the temperature of the solder bath was increased by 10°C and held for 1 minute. The temperature of the solder bath was increased by 10°C in increments until blistering occurred on the surface of the polyimide film, and the upper limit temperature at which blistering did not occur on the surface of the polyimide film was measured. The heat resistance of the adhesive film was evaluated according to the following criteria based on the upper limit temperature at which blistering did not occur on the measured surface of the polyimide film. The evaluation results are shown in Table 3.

[0124] (Evaluation Criteria) The upper limit of the temperature at which no swelling occurs on the surface of the polyimide film is 280°C: Pass, Evaluation A The upper limit of the temperature at which no swelling occurs on the surface of the polyimide film is 270°C: Pass, Evaluation B The upper limit of the temperature at which no swelling occurs on the surface of the polyimide film is 260°C: Pass, Evaluation C Blisters occur on the surface of the polyimide film at 260°C: Fail, Evaluation D

[0125] Next, the heat resistance of the adhesive film under humidified conditions was evaluated using the resulting laminate. Specifically, the heat resistance evaluation test piece was placed in a thermo-hygrostat humidified to 40°C and 80% RH, and the test piece (humidified test piece) in a high-moisture state immediately after removal from the thermo-hygrostat was floated in a solder bath and visually observed for the presence or absence of blistering. The humidified test piece was floated so that the Cu of the copper-clad laminate was in contact with the solder, and the initial temperature of the solder bath was 220°C. If no blistering occurred on the surface of the polyimide film after floating the humidified test piece in the solder bath at 220°C for 1 minute, the temperature of the solder bath was increased by 10°C and held for 1 minute. The temperature of the solder bath was increased by 10°C increments until blistering occurred on the surface of the polyimide film, and the upper limit temperature at which blistering did not occur on the surface of the polyimide film was measured. The heat resistance of the adhesive film under humid conditions was evaluated based on the upper limit of the temperature at which no blistering occurred on the surface of the measured polyimide film, according to the following criteria. The evaluation results are shown in Table 3.

[0126] (Evaluation Criteria) The upper limit of the temperature at which no swelling occurs on the surface of the polyimide film is 240°C: Pass, Evaluation A The upper limit of the temperature at which no swelling occurs on the surface of the polyimide film is 230°C: Pass, Evaluation B The upper limit of the temperature at which no swelling occurs on the surface of the polyimide film is 220°C: Pass, Evaluation C Blisters occur on the surface of the polyimide film at temperatures below 220°C: Fail, Evaluation D

[0127] Next, the embeddability of the adhesive film was evaluated using the obtained laminate. Specifically, a comb-shaped sample simulating a flexible substrate (manufactured by Oyo Co., Ltd., a sample in which a circuit having a Cu wiring line width (line) / interline width (space) of 50 μm / 50 μm is formed on the surface of a polyimide film) was attached to the surface of the adhesive film (adhesive layer) of the obtained laminate, and the sample was subjected to a pressure of 20.4 kgf / cm at 170°C. ２The laminate was pressed under a pressure of 2 MPa for 280 seconds. After pressing, the cross section of the test piece in which the laminate and the comb-shaped sample were bonded together was observed using a scanning electron microscope (SU1510) manufactured by Hitachi High-Technologies Corporation, to check whether the adhesive layer was embedded between the circuits. If the adhesive layer was embedded between the circuits, the embeddability was deemed to be acceptable, and a rating of A was given. If there was a gap between the circuits, the embeddability was deemed to be unacceptable, and a rating of B was given. The evaluation results are shown in Table 3.

[0128] As is clear from Table 3, Examples 1 to 4 are examples using resin compositions that satisfy the requirements of the present invention, and were able to improve flame retardancy without reducing heat resistance and embeddability. In particular, Examples 1 to 3 contained hydrophobic silica as the inorganic filler (F), and therefore had good heat resistance even under humidified conditions. On the other hand, Comparative Example 11 did not exhibit flame retardancy because it did not contain flame retardant (E-1). Comparative Example 12 is an example in which flame retardant (E-1) was added to Comparative Example 11, and although flame retardancy was improved, heat resistance deteriorated. Comparative Example 13 is an example in which Denacol EX-321 was used instead of the epoxy compound (b1-1) used in Comparative Example 12, and while both flame retardancy and heat resistance were improved, the softening temperature increased and embeddability deteriorated. Comparative Example 14 is an example in which an epoxy amine compound (b2-1) was used instead of the epoxy compound (b1-1) used in Comparative Example 12. As with Comparative Example 13, the flame retardancy and heat resistance were improved, but the softening temperature increased and the embeddability deteriorated.

Claims

1. A resin composition comprising: a crosslinked polyester resin (C) having a structure in which the side chain carboxy groups of a polyester resin (A) having carboxy groups at their side chains are crosslinked with an epoxy-based crosslinking agent (B) comprising an epoxy compound (b1) having two epoxy groups and no tertiary amino group in the molecule and an epoxy amine compound (b2) having two or more epoxy groups and one or more tertiary amino group in the molecule; an ester exchange catalyst (D); and a flame retardant (E).

2. The resin composition according to claim 1, wherein the epoxy amine compound (b2) has 2 to 4 epoxy groups in the molecule.

3. The resin composition according to claim 1, wherein the epoxy amine compound (b2) 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.

4. The resin composition according to claim 1, wherein the epoxy compound (b1) is an aliphatic epoxy compound.

5. The resin composition according to claim 1, wherein the flame retardant (E) is an inorganic flame retardant filler and / or an organic flame retardant filler.

6. The resin composition according to claim 1, wherein the flame retardant (E) is a phosphorus-based compound.

7. The resin composition according to claim 1, further comprising an inorganic filler (F).

8. The resin composition according to claim 7, wherein the inorganic filler (F) is a silica filler.

9. The resin composition according to claim 7, wherein the inorganic filler (F) is hydrophobic silica.

10. The resin composition according to claim 7, which contains 2 to 50 parts by mass of the inorganic filler (F) per 100 parts by mass of the polyester resin (A).

11. An adhesive film containing the resin composition according to any one of claims 1 to 10.

12. A laminate comprising the adhesive film according to claim 11 and a substrate.

13. A printed wiring board comprising the laminate of claim 12.

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