Thermosetting resin composition for binder

Abstract

To provide a thermosetting resin composition for binder, exhibiting excellent dielectric characteristics and capable of forming a sheet with superior moldability even under high filling of inorganic fillers or metal powders.SOLUTION: A thermosetting resin composition for binder, comprises (A) 100 pts.mass of a styrene-based elastomer, (B) 1 to 50 pts.mass of a maleimide compound represented by the following formula (1) or (2), and (C) 0.01 to 10 pts.mass of an organic peroxide, wherein n is independently an integer from 1 to 100, and -C36H70- is a divalent hydrocarbon group derived from a dimer acid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting resin composition for binders. [Background technology]

[0002] In recent years, the next-generation mobile communication system known as 5G has become widespread, aiming to realize high-speed, large-capacity, and low-latency communications. To achieve this, materials for high-frequency bands are required, and reducing transmission loss as a noise countermeasure is essential. To achieve this, there is a demand for the development of insulating materials with excellent dielectric properties, such as low dielectric constant and low dielectric loss tangent.

[0003] Among these, materials with excellent dielectric properties are in demand for binder applications. Binders are constituent substances required when forming powder materials such as inorganic fillers and metal powders into shapes such as sheets or films. Because the properties of powder materials depend on the properties of the substance, it is difficult to reduce the relative dielectric constant and dielectric dissipation factor of the powder material itself. To improve the dielectric properties of insulating materials containing powder materials and binder resins, it is necessary to reduce the relative dielectric constant and dielectric dissipation factor of the binder resin.

[0004] A common method for manufacturing sheets or films involves mixing and dispersing a binder resin, additives, and powder material, and then molding the mixture. Thermoplastic resins such as polyester and thermosetting resins such as epoxy resins are often used as binder resins in this process (Patent Documents 1 and 2). While these resins have good sheet formability, there are issues with the heat resistance of thermoplastic resins and the dielectric properties of thermosetting resins.

[0005] In light of this background, it has been reported that compositions combining an epoxy resin with a thermosetting or thermoplastic resin other than an epoxy resin as a binder resin have excellent dielectric properties (for example, Patent Documents 3 to 6). Many of the binder resins that were previously said to have excellent dielectric properties are currently not yet sufficient in dielectric properties. On the other hand, a resin composition containing a special maleimide compound has been disclosed as a composition having excellent high-frequency characteristics (Patent Document 7). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2023-074617 [Patent Document 2] International Publication No. 2023-100923 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-248141 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-68713 [Patent Document 5] International Publication No. 2016-17473 [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-79354 [Patent Document 7] International Publication No. 2018-16489 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the resin composition described in Patent Document 7 has very excellent dielectric properties, it does not have sufficient sheet formability, and there has been a demand for a material that has excellent formability for being formed into a sheet or film as a binder resin and also has excellent dielectric properties. Therefore, an object of the present invention is to provide a thermosetting resin composition for binders that has excellent dielectric properties and can be formed into a sheet with excellent moldability even when highly filled with powder materials such as inorganic fillers and metal powders. [Means for solving the problem]

[0008] As a result of extensive research to solve the above problems, the present inventors have found that the following thermosetting resin composition can achieve the above object, and have completed the present invention. That is, the present invention provides the following thermosetting resin composition for binders.

[0009] <1> (A) 100 parts by mass of styrene-based elastomer, (B) 1 to 50 parts by mass of a maleimide compound represented by the following formula (1) or (2), and (C) Organic peroxide 0.01~10 parts by mass A thermosetting resin composition for binders comprising: [ka] (In formula (1) and formula (2), n is independently a number from 1 to 100, and -C 36 H 70 - is a divalent hydrocarbon group derived from a dimer acid. <2> The styrene-based elastomer of component (A) is a copolymer of a styrene monomer and a compound having a carbon-carbon double bond other than a styrene monomer. <1> 2. The thermosetting resin composition for binders according to claim 1. <3> Furthermore, (D) an antioxidant is contained in an amount of 0.1 to 20 parts by mass per 100 parts by mass of component (A). <1> or <2> 2. The thermosetting resin composition for binders according to claim 1. <4> (D) The antioxidant is solid at 25°C. <3> 2. The thermosetting resin composition for binders according to claim 1. <5> The antioxidant of component (D) contains at least one selected from the group consisting of phenol-based antioxidants, thioether-based antioxidants, and phosphorus-containing antioxidants. <3> or <4> 2. The thermosetting resin composition for binders according to claim 1. <6> Furthermore, the component (E) contains an organic solvent in an amount of 10 to 800 parts by mass per 100 parts by mass of the component (A). <1> ~ <5> 10. The thermosetting resin composition for binders according to claim 9. [Effects of the Invention]

[0010] The thermosetting resin composition for binders of the present invention has good sheet formability even when highly filled with powder materials such as inorganic fillers, and the cured product thereof has excellent dielectric properties and heat resistance. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in more detail below.

[0012] [(A) Styrene-based elastomer] The styrene-based elastomer (A) used in the present invention is not particularly limited as long as it has a structural unit derived from a styrene-based compound, and may be a thermoplastic elastomer having a structural unit derived from styrene. Furthermore, the styrene-based elastomer (A) may be modified with a reactive functional group, or may be an unmodified thermoplastic elastomer. This component (A) primarily contributes to improving the dielectric properties of the cured product of the composition at high frequencies and the flexibility of the composition when formed into a film.

[0013] In the present invention, the styrene-based elastomer is preferably a copolymer of styrene monomer and a compound other than styrene monomer that has a carbon-carbon double bond. That is, the styrene-based elastomer (component (A)) is preferably a copolymer with styrene as the hard segment and a compound other than styrene that has a carbon-carbon double bond as the soft segment. The bonding structure of this copolymer may be a block copolymer or a random copolymer. Among these, block copolymers are preferred due to their stable quality. Examples of styrene-based elastomers include styrene / butadiene / styrene block / random copolymer, styrene / isoprene / styrene block / random copolymer, styrene / ethylene / butylene / styrene block / random copolymer, styrene / ethylene / propylene / styrene block / random copolymer, and styrene / butadiene block / random copolymer.

[0014] From the viewpoint of heat resistance, it is preferable to use, as the styrene-based elastomer of component (A), styrene / ethylene / butylene / styrene block / random copolymer, styrene / ethylene / propylene / styrene block / random copolymer, styrene / butadiene block / random copolymer, etc., in which the double bonds in compounds having carbon-carbon double bonds have been reduced by a hydrogenation reaction (hydrogenation). The hydrogenation may be partial or complete, but from the viewpoint of heat resistance, complete hydrogenation or copolymers with a high degree of hydrogenation are more preferable.

[0015] The mass ratio of styrene / compound having a carbon-carbon double bond and the portion where the double bond is hydrogenated in the styrene copolymer is preferably 10 / 90 to 70 / 30, and more preferably 20 / 80 to 67 / 33. If the mass ratio is within this range, a composition with excellent compatibility and dispersibility and stable quality can be obtained. That is, the styrene content by mass in the styrene-based elastomer is preferably 10 to 70 mass%, and more preferably 20 to 67 mass%.

[0016] The number average molecular weight (Mn) of component (A) is preferably 10,000 to 300,000, and more preferably 10,000 to 200,000. When the number average molecular weight of component (A) is within the range of 10,000 to 300,000, the resulting composition exhibits excellent film properties, excellent compatibility and dispersibility with other components such as components (B) and (C) described below, and good sheet formability. The number average molecular weight referred to in this specification refers to the number average molecular weight measured by gel permeation chromatography (GPC) under the following conditions using polystyrene as a standard substance.

[0017] [Measurement conditions] Developing solvent: tetrahydrofuran (THF) Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperHZ4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ2000(4.6mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass THF solution)

[0018] The styrene-based elastomer (A) may be a commercially available product. Specific examples include the Tuftec series manufactured by Asahi Kasei Corporation and the FG series manufactured by Kraton. The composition of the present invention may contain one type of styrene-based elastomer alone or a mixture of two or more types. In the thermosetting resin composition for binders of the present invention (excluding the organic solvent (E)), the blending amount of the component (A) is preferably 60 to 99 mass%, more preferably 65 to 97 mass%, and even more preferably 70 to 95 mass%.

[0019] [(B) Specific maleimide compound] The component (B) used in the present invention is a maleimide compound having a specific structure represented by the following formula (1) or (2). The component (B) is a thermosetting resin, and the thermosetting resin composition for binders of the present invention contains the component (B), resulting in excellent heat resistance, mechanical properties, and sheet formability, making it a highly reliable composition. In addition, the component (B) has a dimer acid skeleton, which results in excellent dielectric properties. Therefore, the composition of the present invention containing the component (B) exhibits excellent dielectric properties. If the specific maleimide compound is not used, compatibility with the component (A) will be poor, and a homogeneous composition will not be obtained. [ka] In formula (1) and formula (2), n is independently a number from 1 to 100, -C 36 H 70 - is a divalent hydrocarbon group derived from a dimer acid.

[0020] Dimer acids are liquid fatty acids primarily composed of a 36-carbon dicarboxylic acid, produced by the dimerization of 18-carbon unsaturated fatty acids derived from natural sources such as vegetable oils. Dimer acids do not have a single skeleton but have multiple structures, resulting in the existence of several isomers. Representative dimer acids are classified as linear (a), monocyclic (b), aromatic (c), and polycyclic (d). In this specification, the dimer acid skeleton refers to a group derived from a dimer diamine having a structure in which the carboxy groups of such a dimer acid are substituted with primary aminomethyl groups. In other words, the cyclic imide compound of component (B) preferably has a dimer acid skeleton in which two carboxy groups in each of the dimer acids shown below (a) to (d) are substituted with methylene groups. Furthermore, from the viewpoint of the heat resistance and reliability of the cured product, it is more preferable that the hydrocarbon group derived from the dimer acid skeleton in the maleimide compound has a structure in which the carbon-carbon double bond in the hydrocarbon group derived from the dimer acid skeleton is reduced by a hydrogenation reaction. As described above, dimer acids have multiple structures, and therefore, in this specification, the divalent hydrocarbon group derived from the dimer acid is referred to as the average structure, i.e., -C 36 H 70 It is written as -. [ka]

[0021] In the formula (1), n ​​is 0 to 100, preferably 1 to 90, and more preferably 1 to 80.

[0022] The number average molecular weight of the maleimide compound of component (B) is preferably 1,000 to 30,000, and more preferably 1,200 to 10,000. The number average molecular weight of component (B) refers to the number average molecular weight measured by gel permeation chromatography (GPC) under the same conditions as those for measuring the number average molecular weight of component (A) above, using polystyrene as the standard substance.

[0023] The blending amount of component (B) is 1 to 50 parts by mass, preferably 3 to 40 parts by mass, per 100 parts by mass of (A). If the blending amount of component (B) is more than 50 parts by mass, the varnish may become cloudy or film properties may be impaired. Conversely, if the blending amount of component (B) is less than 1 part by mass, the amount of thermosetting component may be reduced, resulting in reduced mechanical properties and reduced sheet formability.

[0024] [(C)Organic peroxide] The component (C) used in the present invention is an organic peroxide. Component (C) is added primarily to initiate the crosslinking reaction of the maleimide compound (B). Furthermore, if the styrene-based elastomer (A) contains a radically polymerizable functional group, component (C) is added to promote the reaction between the functional group and the maleimide compound (B). Examples of organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide.

[0025] The blending amount of component (C) is 0.01 to 10 parts by mass, preferably 0.1 to 3.0 parts by mass, per 100 parts by mass of component (A). If the blending amount of component (C) is more than 10 parts by mass, the reactivity may be too high, resulting in a decrease in sheet formability. In addition, if component (C) remains in the composition, the dielectric properties may be deteriorated. Conversely, if the blending amount of component (C) is less than 0.01 part by mass, the curing properties may be reduced, resulting in a decrease in dielectric properties.

[0026] [(D) Antioxidant] The thermosetting resin composition for binders of the present invention may optionally contain an antioxidant (D). Component (D) is added primarily to impart heat resistance to the composition. The antioxidant is not particularly limited, but preferably contains at least one selected from the group consisting of phenolic antioxidants, thioether antioxidants, and phosphorus-containing antioxidants. Examples of phenolic antioxidants include n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)acetate, neododecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, dodecyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, ethyl-α-(4-hydroxy-3,5-di-t-butylphenyl)isobutyrate, octadecyl-α-(4-hydroxy-3,5-di-t-butylphenyl)isobutyrate, and octadecyl-α-(4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl)propionate. ester, 2-(n-octylthio)ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2-(n-octadecylthio)ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2-(n-octadecylthio)ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-(2-stearoyloxyethylthio)ethyl-7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate, 2-hydroxyethyl-7-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and the like. Examples of thioether antioxidants include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, and pentaerythrityl tetrakis(3-laurylthiopropionate). Examples of phosphorus-containing antioxidants include tridecyl phosphite, triphenyl phosphite, tris(2,4-di-t-butylphenyl)phosphite, 2-ethylhexyldiphenyl phosphite, diphenyltridecyl phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, distearyl pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, 2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-N,N-bis[2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-ethyl]ethanamine, and the like.

[0027] The blending amount of component (D) is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, per 100 parts by mass of component (A). If the blending amount of component (D) is more than 20 parts by mass, the dielectric properties may deteriorate and reactivity may decrease. Conversely, if the blending amount of component (D) is less than 0.1 part by mass, it does not contribute to improving heat resistance, and the effect of adding component (D) is less likely to be achieved.

[0028] [(E) Organic solvent] The thermosetting resin composition for binders of the present invention may contain an organic solvent (E) as an optional component. Component (E) is added to dissolve components (A) to (C) or components (A) to (D) to form a varnish. Any organic solvent can be used without particular limitation as long as it dissolves components (A) to (D). Suitable organic solvents include, for example, toluene, xylene, anisole, cyclohexanone, and cyclopentanone. The above organic solvents may be used alone or in combination of two or more.

[0029] The amount of component (E) blended is 10 to 800 parts by mass, and preferably 20 to 500 parts by mass, per 100 parts by mass of component (A). If the amount of component (D) blended is 10 parts by mass or more, the varnish is easy to handle; conversely, if it is more than 800 parts by mass, the organic solvent tends to volatilize, and the ratio of solid components in the varnish solution may become unstable.

[0030] [Other additives] The composition of the present invention may further contain various additives as needed within the range that does not impair the effects of the present invention. Examples of such additives include adhesion promoters such as coupling agents such as silane coupling agents and titanate coupling agents, and monomers having a (meth)acrylic group. As the adhesion aid, a coupling agent such as a silane coupling agent or a titanate coupling agent, or a monomer having a (meth)acrylic group can be blended.

[0031] Other additives include organopolysiloxanes having a reactive functional group, non-functional silicone oils, thermoplastic resins, non-styrene thermoplastic elastomers, organic synthetic rubbers, photosensitizers, light stabilizers, polymerization inhibitors, flame retardants, pigments, dyes, etc. In order to improve the electrical properties of the cured product of the thermosetting cyclic imide resin composition, an ion trapping agent or the like may also be blended as other additives.

[0032] The thermosetting resin composition for binders of the present invention can be produced by mixing the components (A), (B), and (C), as well as the components (D), (E), and other additives that are added as needed.

[0033] The thermosetting resin composition for binders of the present invention can be highly moldable into sheets even when highly loaded with powder materials such as inorganic fillers or metal powders. For example, when the thermosetting resin composition for binders of the present invention is used as a varnish, the powder material is blended in a high proportion, preferably 50 to 95% by mass, more preferably 55 to 90% by mass, of the powder material relative to the total mass of the organic solvent and powder material. The resulting uncured resin film or sheet obtained by applying the composition to a substrate and drying the organic solvent exhibits excellent sheet moldability and does not crack or break when bent. Furthermore, the cured resin film or sheet obtained by heating the uncured resin film also exhibits excellent dielectric properties, such as low dielectric constant and dielectric loss tangent. [Example]

[0034] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0035] The components used in the examples and comparative examples are shown below.

[0036] (A) Styrene-based elastomer (A-1) Amine-modified styrene / ethylene / butylene / styrene block copolymer, hydrogenated, styrene content 30% (Tuftec MP10: manufactured by Asahi Kasei Corporation) (A-2) Carboxylic acid-modified styrene / ethylene / butylene / styrene block copolymer, styrene content 30% (Tuftec M1913: Asahi Kasei Corporation) (A-3) Styrene / ethylene / butylene / styrene block copolymer, styrene content 30% (Tuftec H1041: manufactured by Asahi Kasei Corporation)

[0037] (B) Maleimide compound (B-1): A bismaleimide compound represented by the following formula (1) (SLK-1500, manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 2,200) [ka] n≒3 (average value) (B-2): A bismaleimide compound represented by the following formula (2) (X-45-1400, manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 1,500) [ka] n≒2 (average value) (B-3): Bismaleimide compound represented by the following formula (SLK-3000, manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 5,000, for comparative example) [ka] n≒5 (average value) (B-4): 4,4'-diphenylmethane bismaleimide (BMI-1000: manufactured by Daiwa Chemical Industry Co., Ltd., number average molecular weight 500, for comparative example)

[0038] (C)Organic peroxide (C-1): Dicumyl peroxide (Percumyl D: manufactured by NOF Corporation)

[0039] (D) Antioxidants (C-1): 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-sec-triazine-2,4,6-(1H,3H,5H)trione (ADEKA STAB AO-20: ADEKA Corporation) (C-2): Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (ADEKA STAB AO-60, manufactured by ADEKA Corporation) (C-3): Cyclic neopentanetetraylbis(octadecyl phosphite) (PEP-8: manufactured by ADEKA Corporation)

[0040] (E) Organic solvent (E-1): Xylene (E-2): Toluene <Preparation of varnish> According to the formulations in Tables 1 and 2, each component was placed in a 500 mL four-neck flask equipped with a Dimroth condenser and a stirrer, and stirred at 50°C for 2 hours to obtain a varnish-like resin composition. The resin composition obtained in Example 1 is referred to as Binder 1. The same applies to Examples 2 to 18. The resin composition obtained in Comparative Example 1 is referred to as Binder 1'. The same applies to Comparative Examples 2 to 9.

[0041] [Table 1] [Table 2]

[0042] <Preparation of Blended Composition> The binders and inorganic fillers prepared in the above examples were mixed in the formulations shown in Tables 3 to 5. The resulting blended compositions were evaluated as follows, and the results are shown in Tables 3 to 5.

[0043] [Table 3]

[0044] [Table 4]

[0045] [Table 5]

[0046] <Preparation of uncured resin film> The varnish-like compositions formulated in Tables 3 to 5 were applied to a 38 μm thick PET film using a roller coater so that the thickness after drying would be 50 μm, and the film was dried at 100°C for 10 minutes to obtain an uncured resin film.

[0047] <Flexibility of sheet before curing> The uncured resin film was visually inspected for cracks or breakage when bent 90 degrees at 25° C. If no cracks, breaks, tacks, or the like were observed, it was marked with ○, and if even a small amount of cracks, breaks, tacks, or the like were observed, it was marked with ×.

[0048] <Flexibility of the sheet after curing> The uncured resin film was cured at 180°C for 2 hours, and the resulting resin film was cut to prepare a 60 mm x 60 mm test piece. The prepared test piece was bent 90 degrees at 25°C, and visually inspected to see if the film cracked or broke. When no cracks, breaks, tacks, etc. were observed, it was marked with an ◯, and when even a small amount of cracks, breaks, tacks, etc. were observed, it was marked with an X.

[0049] <Relative permittivity, dielectric loss tangent> The uncured resin film was cured at 180°C for 2 hours, and the resulting resin film was cut to prepare 60 mm x 60 mm test pieces. The dielectric constant and dielectric loss tangent at 10 GHz at 25°C were measured for the obtained test pieces using an SPDR dielectric resonator (MS46122B, manufactured by Anritsu Corporation). Furthermore, to evaluate heat resistance, the dielectric constant and dielectric loss tangent at 10 GHz were measured in the same manner after storing the test pieces at 125°C for 200 hours.

[0050] The results in Tables 3 to 5 confirm that the uncured resin films and cured resin films produced using the binders of the Examples were free of cracks, breaks, etc. On the other hand, the uncured resin films and cured resin films produced using the binders of the Comparative Examples showed cracks, etc., and the dielectric loss tangent of the cured products produced using the binders of the Comparative Examples after storage at 125°C was significantly higher than the initial dielectric loss tangent, indicating poor heat resistance.

[0051] From the above results, it was confirmed that the thermosetting resin composition for binders of the present invention has excellent dielectric properties when cured, good film handling properties even when filled with filler, and good heat resistance, and therefore is useful as a binder resin.

Claims

1. (A) 100 parts by mass of styrene-based elastomer, (B) 1 to 50 parts by mass of a maleimide compound represented by the following formula (1) or (2), and (C) Organic peroxide 0.01 to 10 parts by mass A thermosetting resin composition for binders comprising: 【Chemical 1】 (In formula (1) and formula (2), n is independently a number from 1 to 100, and -C 36 H 70 - is a divalent hydrocarbon group derived from a dimer acid.

2. 2. The thermosetting resin composition for binders according to claim 1, wherein the styrene-based elastomer of component (A) is a copolymer of a styrene monomer and a compound having a carbon-carbon double bond other than a styrene monomer.

3. 2. The thermosetting resin composition for binders according to claim 1, further comprising 0.1 to 20 parts by mass of an antioxidant (D) per 100 parts by mass of the component (A).

4. 4. The thermosetting resin composition for binders according to claim 3, wherein the antioxidant of component (D) is solid at 25°C.

5. 4. The thermosetting resin composition for binders according to claim 3, wherein the antioxidant of component (D) comprises at least one selected from the group consisting of phenol-based antioxidants, thioether-based antioxidants, and phosphorus-containing antioxidants.

6. 2. The thermosetting resin composition for binders according to claim 1, further comprising 10 to 800 parts by mass of an organic solvent (E) per 100 parts by mass of the component (A).

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