Curable resin composition and electrical / electronic parts

Abstract

To provide a curable resin composition which is comparatively inexpensive, is excellent in productivity since injection molding is possible, is excellent in reliability of an applied electric apparatus because of a low shrinkage rate, and enables production of a cured product that is excellent in adhesion to substrate, especially, a slightly adhesive resin substrate.SOLUTION: A curable resin composition contains (A) a curable resin, (B) an ethylenically unsaturated monomer, (C) a low shrinking agent, (D) an inorganic filler, (E) a heat polymerization initiator, and (F) a glass fiber, wherein (A) the curable resin contains a vinyl ester resin, a content of (C) the low shrinking agent is 5-50 pts.mass with respect to 100 pts.mass of the total of (A) the curable resin and (B) the ethylenically unsaturated monomer, and 55-100 mass% of at least one selected from the group consisting of a vinyl acetate polymer and a block copolymer having vinyl acetate as monomer units is contained with respect to the whole of (C) the low shrinking agent, as (C) the low shrinking agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition and an electric / electronic part. [Background technology]

[0002] In electronic devices such as motors, coils, and electronic control units installed in automobiles, etc., in order to protect the wiring board and the electronic components mounted on the wiring board, a structure is required that can fix the components and prevent damage to the components due to vibration, and that can prevent the intrusion of water, corrosive gases, etc. In such cases, a structure is generally used in which the entire electronic component is sealed and fixed using a material called a sealant.

[0003] For example, Patent Document 1 discloses an encapsulating epoxy resin composition used to form an encapsulant that collectively seals the gap between a wiring board and an electronic component. Patent Document 2 discloses an unsaturated polyester resin composition for molding electric and electronic components, which contains 7 to 15% by weight of a novolac vinyl ester resin, 2 to 5% by weight of a bis-unsaturated polyester resin, and 65 to 80% by weight of magnesium oxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-148586 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-27019 Summary of the Invention [Problem to be solved by the invention]

[0005] However, epoxy resins have a problem in that the raw material cost is relatively high among resins, making them difficult to use for large products. Furthermore, epoxy resin compositions have a high molding temperature of 170 to 180°C and a long curing time, leaving room for improvement in terms of reliability, productivity, and cost of electronic devices. The resin composition disclosed in Patent Document 2 leaves room for further improvement in terms of adhesion to substrates.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a curable resin composition that is relatively inexpensive, can be injection-molded to provide excellent productivity, has a low shrinkage rate to provide excellent reliability for electronic devices to which it is applied, and can provide a cured product that has excellent adhesion to substrates, particularly poorly adhesive resin substrates. Another aim of the present invention is to provide an electric / electronic component comprising a cured product of the curable resin composition, and a method for producing the electric / electronic component. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that, when a specific low-profile agent is used in a specific range together with a curable resin containing a specific resin, it is possible to realize a curable resin composition that can be injection molded, thereby providing excellent productivity, that has a low shrinkage rate, thereby providing excellent reliability for electronic devices to which it is applied, and that can provide a cured product that has excellent adhesion to substrates, particularly to poorly adhesive resin substrates, and has thereby completed the present invention.

[0008] The present invention includes the following aspects. [1] (A) Curable resin, (B) an ethylenically unsaturated monomer, (C) low shrinkage agent, (D) Inorganic filler, (E) a thermal polymerization initiator, and (F) Glass fiber Including, The (A) curable resin contains a vinyl ester resin, the content of the (C) low shrinkage agent is 5 to 50 parts by mass relative to 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer, the (C) low shrinkage agent contains at least one selected from the group consisting of vinyl acetate polymers and block copolymers having vinyl acetate as a monomer unit in an amount of 55 to 100 mass % based on the total mass of the (C) low shrinkage agent; Curable resin composition. [2] the (B) ethylenically unsaturated monomer contains an aromatic vinyl compound, The aromatic vinyl compound includes an aromatic monovinyl compound and an aromatic divinyl compound, The curable resin composition according to [1], wherein the total content of vinyl groups in the aromatic vinyl compound is 60 to 95 mol % based on the total of the ethylenically unsaturated groups contained in the (A) curable resin and the (B) ethylenically unsaturated monomer. [3] The curable resin composition according to [2], wherein the content of the aromatic divinyl compound is 5 to 50 mol % based on the total amount of the (B) ethylenically unsaturated monomer. [4] The curable resin composition according to [2] or [3], wherein the content of the aromatic vinyl compound is 70 mol % or more based on the total amount of the (B) ethylenically unsaturated monomer. [5] The curable resin composition according to any one of [2] to [4], wherein the aromatic divinyl compound is divinylbenzene. [6] The curable resin composition according to any one of [2] to [5], wherein the aromatic vinyl compound comprises divinylbenzene and at least one selected from the group consisting of ethylvinylbenzene and styrene. [7] relative to 100 parts by mass in total of the (A) curable resin and the (B) ethylenically unsaturated monomer, The content of the (A) curable resin is 5 to 95 parts by mass, the content of the (B) ethylenically unsaturated monomer is 5 to 95 parts by mass, the content of the (C) low shrinkage agent is 5 to 50 parts by mass, the content of the (D) inorganic filler is 200 to 700 parts by mass, the content of the (E) thermal polymerization initiator is 0.1 to 25 parts by mass, The curable resin composition according to any one of [1] to [6], wherein the content of the (F) glass fiber is 10 to 300 parts by mass. [8] The curable resin composition according to any one of [1] to [7], further comprising (G) an acidic surfactant. [9] An electric / electronic part comprising a cured product of the curable resin composition according to any one of [1] to [8].

[10] A step of injection-molding the curable resin composition according to any one of [1] to [8] to encapsulate components of an electric / electronic part; and A method for producing an electric / electronic component, comprising the step of heat-curing the curable resin composition. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a curable resin composition that is relatively inexpensive, can be injection-molded, and thus has excellent productivity, has a reduced shrinkage rate during curing, and can give a cured product that has excellent adhesion to substrates, particularly poorly adhesive resin substrates. Furthermore, it is possible to provide a cured product having excellent adhesion obtained by curing the curable resin composition, an electric / electronic component including the cured product, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

[0011] In this disclosure, "(meth)acrylic acid" means methacrylic acid or acrylic acid, and "(meth)acrylate" means acrylate or methacrylate.

[0012] The term "ethylenically unsaturated bond" refers to a double bond formed between carbon atoms excluding those forming an aromatic ring, the term "ethylenically unsaturated group" refers to a group having an ethylenically unsaturated bond, and the term "ethylenically unsaturated monomer" refers to a monomer having an ethylenically unsaturated bond. In the (B) ethylenically unsaturated monomer, the term "vinyl group" refers to CH=CH- and does not include 1-alkenyl groups such as allyl groups. However, the term "vinyl" in the vinyl ester resin is not limited to this.

[0013] 《1. Curable resin composition》 The curable resin composition of one embodiment contains (A) a curable resin, (B) an ethylenically unsaturated monomer, (C) a low-profile agent, (D) an inorganic filler, (E) a thermal polymerization initiator, and (F) glass fibers.

[0014] The curable resin composition may further contain (G) an acidic surfactant, if necessary.

[0015] <(A) Curing resin> The curable resin (A) is not particularly limited as long as it is a curable resin commonly used in sealing material applications. The curable resin is preferably, for example, a resin having a functional group capable of forming a crosslinked structure when the curable resin composition is cured by heating. Specific examples of the curable resin (A) include (A-1) vinyl ester resin, (A-2) unsaturated polyester resin, (A-3) urethane (meth)acrylate resin, (A-4) diallyl phthalate resin, and (A-5) epoxy resin.

[0016] From the viewpoints of material cost and moldability, the (A) curable resin contains at least an (A-1) vinyl ester resin. The (A) curable resin may be used alone or in combination of two or more kinds.

[0017] The content of the (A-1) vinyl ester resin in the (A) curable resin is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. When the content of the (A-1) vinyl ester resin is 75% by mass or more, the material cost of the curable resin composition can be reduced, and a cured product with better moldability and adhesion can be obtained. There is no particular upper limit for the content of the (A-1) vinyl ester resin in the (A) curable resin. The content of the (A-1) vinyl ester resin may be, for example, 100% by mass, 97% by mass, or 95% by mass.

[0018] The content of the (A) curable resin is preferably 5 to 95 parts by mass, more preferably 10 to 75 parts by mass, and even more preferably 20 to 60 parts by mass, relative to 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer.

[0019] [(A-1) Vinyl ester resin] (A-1) vinyl ester resins are generally compounds having a radically polymerizable unsaturated bond, obtained by a ring-opening reaction between an epoxy group in an (a) epoxy compound having two or more epoxy groups and a carboxy group in an (b) unsaturated monobasic acid having a radically polymerizable unsaturated bond and a carboxy group. (A-1) vinyl ester resins are described, for example, in the Polyester Resin Handbook (published by Nikkan Kogyo Shimbun, 1988).

[0020] The (A-1) vinyl ester resin may be used alone or in combination of two or more. In terms of handling, the (A-1) vinyl ester resin is generally used after diluting with the (B) ethylenically unsaturated monomer. By using the (A-1) vinyl ester resin, the material cost of the curable resin composition can be reduced and a cured product with excellent adhesion can be obtained.

[0021] The number average molecular weight (Mn) of the vinyl ester resin (A-1) can be adjusted depending on the desired physical properties, but from the standpoint of handling, it is preferably in the range of 500 to 5,000.

[0022] In the present disclosure, the "weight average molecular weight" and "number average molecular weight" are values ​​measured at room temperature (23°C) using gel permeation chromatography (GPC) under the following conditions and determined using a standard polystyrene calibration curve. Apparatus: Shodex (registered trademark) GPC-101 (Showa Denko K.K.) Column: Shodex (registered trademark) LF-804 (Showa Denko K.K.) Column temperature: 40℃ Sample: 0.2% by mass of sample in tetrahydrofuran Flow rate: 1mL / min Eluent: tetrahydrofuran Detector: Shodex (registered trademark) RI-71S (Showa Denko K.K.)

[0023] ((a) Epoxy Compound) The (a) epoxy compound is not particularly limited as long as it has two or more epoxy groups. Preferably, it is at least one selected from the group consisting of bisphenol-type epoxy compounds and novolac phenol-type epoxy compounds, and more preferably, it is a bisphenol-type epoxy compound. By using the (A-1) vinyl ester resin using the (a) epoxy compound as a raw material, the mechanical strength and corrosion resistance of the cured product are further improved.

[0024] Examples of bisphenol epoxy compounds include those obtained by reacting a bisphenol compound such as bisphenol A, bisphenol F, bisphenol S, and tetrabromobisphenol A with epichlorohydrin and / or methylepichlorohydrin, and those obtained by reacting a condensate of a compound obtained by glycidyl etherifying one or more of the above bisphenol compounds with one or more of the above bisphenol compounds with epichlorohydrin and / or methylepichlorohydrin. Among these, from the viewpoint of durability, a reaction product of a bisphenol compound with epichlorohydrin is preferred, and a reaction product of bisphenol A with epichlorohydrin is more preferred.

[0025] Examples of novolak phenol type epoxy compounds include those obtained by reacting phenol novolak or cresol novolak with epichlorohydrin and / or methyl epichlorohydrin.

[0026] ((b) Unsaturated monobasic acid) The (b) unsaturated monobasic acid is not particularly limited as long as it is a monocarboxylic acid having an ethylenically unsaturated bond. The unsaturated monobasic acid is preferably methacrylic acid, acrylic acid, crotonic acid, cinnamic acid, or the like, more preferably acrylic acid or methacrylic acid, and even more preferably methacrylic acid from the viewpoint of the corrosion resistance of the cured product.

[0027] ((A-1) Method for synthesizing vinyl ester resin) The (A-1) vinyl ester resin can be synthesized by a known synthesis method, for example, by adding (b) an unsaturated monobasic acid to (a) an epoxy compound in the presence of an esterification catalyst and (b) an unsaturated monobasic acid in a reaction vessel capable of being heated and stirred, and reacting the components at 70 to 150°C, preferably 80 to 140°C, and more preferably 90 to 130°C.

[0028] In the present disclosure, the unreacted (b) unsaturated monobasic acid remaining after synthesis of the (A-1) vinyl ester resin is considered to be the (B) ethylenically unsaturated monomer described below.

[0029] As the esterification catalyst, for example, known catalysts such as tertiary amines such as triethylamine, N,N-dimethylbenzylamine, N,N-dimethylaniline, and diazabicyclooctane, triphenylphosphine, and diethylamine hydrochloride can be used.

[0030] The compounding ratio of the (a) epoxy compound to the (b) unsaturated monobasic acid is preferably such that the total number of carboxy groups in the (b) unsaturated monobasic acid is 0.3 to 1.2 moles, more preferably 0.4 to 1.1 moles, and even more preferably 0.5 to 1.0 moles, per mole of the total number of epoxy groups in the (a) epoxy compound. When the total number of carboxy groups in the (b) unsaturated monobasic acid is 0.3 moles or more, a cured product with sufficient hardness can be obtained when the curable resin composition is cured. On the other hand, when the total number of carboxy groups in the (b) unsaturated monobasic acid is 1.2 moles or less, the amount of unreacted (b) unsaturated monobasic acid can be reduced during the synthesis of the (A-1) vinyl ester resin, thereby reducing the acid value of the mixture of the (A) curable resin and the (B) ethylenically unsaturated monomer, and thereby obtaining a cured product with better adhesion.

[0031] After synthesizing the (A-1) vinyl ester resin, any unreacted (b) unsaturated monobasic acid is not removed and can be used as the (B) ethylenically unsaturated monomer of the curable resin composition. When the curable resin composition is heat-cured, the unreacted (b) unsaturated monobasic acid may volatilize or bleed out, affecting the adhesion of the cured product. Therefore, it is desirable to reduce the content of the unreacted (b) unsaturated monobasic acid as much as possible. For example, the content of the unreacted (b) unsaturated monobasic acid is preferably 5% by mass or less, more preferably 3% by mass or less, relative to the total amount of the (A-1) vinyl ester resin and the unreacted (b) unsaturated monobasic acid.

[0032] [(A-2) Unsaturated polyester resin] The (A-2) unsaturated polyester resin is a polycondensate of a polyhydric alcohol and an unsaturated polybasic acid, or a polycondensate of a polyhydric alcohol, an unsaturated polybasic acid, and a saturated polybasic acid. The (A-2) unsaturated polyester resin may be used alone or in combination of two or more. The use of the (A-2) unsaturated polyester resin makes it possible to obtain a cured product having excellent mechanical strength and heat resistance.

[0033] In the present disclosure, styrene monomers and the like contained in general unsaturated polyester resins are classified as (B) ethylenically unsaturated monomers.

[0034] The polyhydric alcohol used in the synthesis of the unsaturated polyester resin is not particularly limited as long as it is a compound having two or more hydroxyl groups. Examples of the polyhydric alcohol include alkylene glycols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, pentanediol, hexanediol, neopentanediol, tetraethylene glycol, polyethylene glycol, 2-methyl-1,3-propanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A; bisphenol A; alkylene oxide-modified bisphenol A such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A; and glycerin.

[0035] Among these, from the viewpoints of the heat resistance and mechanical strength of the cured product and the fluidity of the curable resin composition during molding, at least one selected from the group consisting of propylene glycol, dipropylene glycol, neopentanediol, hydrogenated bisphenol A, and bisphenol A is preferred, and propylene glycol is more preferred. The polyhydric alcohols may be used alone or in combination of two or more.

[0036] The unsaturated polybasic acid used in the synthesis of the unsaturated polyester resin is not particularly limited as long as it has an ethylenically unsaturated bond and two or more carboxy groups, or an acid anhydride thereof, and known compounds can be used. In particular, unsaturated polybasic acids having 4 to 6 carbon atoms or an acid anhydride thereof are preferred because they are less expensive and can provide a curable resin composition having superior mechanical strength and heat resistance of the cured product.

[0037] Examples of unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, itaconic acid, and chloromaleic acid. More preferably, the unsaturated polybasic acid is an unsaturated polybasic acid selected from the group consisting of fumaric acid, maleic acid, maleic anhydride, and itaconic acid. The unsaturated polybasic acids may be used alone or in combination of two or more.

[0038] Preferred combinations of polyhydric alcohols and unsaturated polybasic acids used in the synthesis of unsaturated polyester resins include, for example, a combination of fumaric acid and neopentanediol, a combination of maleic acid and dipropylene glycol, a combination of maleic anhydride and propylene glycol, a combination of fumaric acid and propylene glycol, and a combination of fumaric acid, hydrogenated bisphenol A and propylene glycol. Among these, the combinations of fumaric acid and propylene glycol and the combinations of fumaric acid, hydrogenated bisphenol A and propylene glycol are preferred because they are lower in cost and can provide a curable resin composition with a higher heat distortion temperature of the cured product and superior mechanical strength and heat resistance.

[0039] The saturated polybasic acid used in the synthesis of the unsaturated polyester resin is not particularly limited as long as it is a compound or anhydride thereof that does not have an ethylenically unsaturated bond and has two or more carboxy groups, and known compounds can be used. Examples of saturated polybasic acids include aromatic saturated polybasic acids or anhydrides thereof, such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, nitrophthalic acid, and halogenated phthalic anhydride; aliphatic saturated polybasic acids, such as succinic acid, adipic acid, sebacic acid, oxalic acid, malonic acid, azelaic acid, and glutaric acid; and hexahydrophthalic anhydride. The saturated polybasic acids may be used alone or in combination of two or more.

[0040] The weight-average molecular weight (Mw) of the (A-2) unsaturated polyester resin is not particularly limited. The weight-average molecular weight of the (A-2) unsaturated polyester resin is preferably 2,000 to 25,000, more preferably 3,000 to 20,000, and even more preferably 3,500 to 10,000. If the weight-average molecular weight is 2,000 to 25,000, the moldability of the curable resin composition will be even better.

[0041] The degree of unsaturation of the (A-2) unsaturated polyester resin is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, and even more preferably 70 to 100 mol%. When the degree of unsaturation is within the above range, the moldability of a curable resin composition containing the (A-2) unsaturated polyester resin is improved. The degree of unsaturation of the (A-2) unsaturated polyester resin can be calculated using the molar numbers of the unsaturated polybasic acid and saturated polybasic acid used as raw materials according to the following formula: Degree of unsaturation (mol %) = {(number of moles of unsaturated polybasic acid × number of ethylenically unsaturated bonds per molecule of unsaturated polybasic acid) / (number of moles of unsaturated polybasic acid + number of moles of saturated polybasic acid)} × 100

[0042] After synthesis of the (A-2) unsaturated polyester resin, the unreacted unsaturated polybasic acid and any saturated polybasic acid may be present in the curable resin composition without being removed.

[0043] [(A-3) Urethane (meth)acrylate resin] As the (A-3) urethane (meth)acrylate resin, for example, a resin obtained by introducing (meth)acryloyl groups into the hydroxyl groups or isocyanato groups at both ends of a polyurethane obtained by reacting a polyhydric isocyanate with a polyhydric alcohol can be used.

[0044] As the polyhydric alcohol used in the synthesis of the urethane (meth)acrylate resin, the compounds described as raw materials for the (A-2) unsaturated polyester resin above can be used without any particular limitation.

[0045] Examples of polyisocyanates used in the synthesis of urethane (meth)acrylate resins include aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate, and trimethylhexane diisocyanate; alicyclic polyisocyanates such as hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4 (or 2,6)-diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,3-(isocyanatomethyl)cyclohexane; aromatic polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate; and adducts, isocyanurates, and biurets of these polyisocyanates. Polyisocyanates may be used alone or in combination.

[0046] In the synthesis of a urethane (meth)acrylate resin, when a (meth)acryloyl group is introduced, for example, a method of reacting a terminal isocyanato group with a hydroxyl group-containing (meth)acrylic compound, or a method of reacting a terminal hydroxyl group with an isocyanato group-containing (meth)acrylic compound such as 2-(meth)acryloyloxyethyl isocyanate, 2-(meth)acryloyloxypropyl isocyanate, or 1,1-bis(acryloyloxymethyl)ethyl isocyanate can be used.

[0047] Examples of hydroxyl group-containing (meth)acrylic compounds used to introduce (meth)acryloyl groups include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, tris(hydroxyethyl)isocyanuric acid di(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin mono(meth)acrylate, and hydroxyethyl acrylamide, with 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, and hydroxyethyl acrylamide being preferred. The isocyanato group-containing (meth)acrylic compounds and hydroxyl group-containing (meth)acrylic compounds may be used alone or in combination of two or more.

[0048] Any unreacted hydroxyl group-containing (meth)acrylic compound or unreacted isocyanato group-containing (meth)acrylic compound remaining after synthesis of (A-3) urethane (meth)acrylate resin is considered to be (B) an ethylenically unsaturated monomer, which will be described later.

[0049] [(A-4) Diallyl phthalate resin] The (A-4) diallyl phthalate resin is an oligomer obtained by an esterification reaction between diallyl phthalate and a polyhydric alcohol, and any conventionally known diallyl phthalate resin can be used without particular limitation. The (A-4) diallyl phthalate resin may be used alone or in combination of two or more kinds.

[0050] After synthesis of the (A-4) diallyl phthalate resin, unreacted diallyl phthalate may remain in the curable resin composition without being removed.

[0051] [(A-5) Epoxy resin] As the (A-5) epoxy resin, the compounds described in the section (a) Epoxy Compounds can be used. The (A-5) epoxy resins may be used alone or in combination of two or more.

[0052] <(B) Ethylenically Unsaturated Monomer> The (B) ethylenically unsaturated monomer is not particularly limited as long as it is a monomer having an ethylenically unsaturated bond. The (B) ethylenically unsaturated monomer may be used alone or in combination of two or more kinds.

[0053] From the viewpoint of ensuring adhesion as a cured product of the curable resin composition, the (B) ethylenically unsaturated monomer preferably contains at least an aromatic vinyl compound. Furthermore, from the viewpoint of obtaining a cured product with good appearance, the aromatic vinyl compound preferably contains an aromatic divinyl compound having two vinyl groups. Furthermore, the aromatic vinyl compound preferably contains an aromatic monovinyl compound and an aromatic divinyl compound. Note that, as defined above, the vinyl group in the (B) ethylenically unsaturated monomer does not include an allyl group or a substituted vinyl group (such as a 1-propenyl group).

[0054] The aromatic vinyl compound is not particularly limited as long as it is a compound having an aromatic ring skeleton and a vinyl group. Specific examples of the aromatic vinyl compound include aromatic monovinyl compounds such as styrene, vinyltoluene, ethylvinylbenzene, t-butylstyrene, methoxystyrene, vinylnaphthalene, and acenaphthylene; and aromatic divinyl compounds described below. Among these, the aromatic vinyl compound preferably contains at least one selected from the group consisting of styrene, vinyltoluene, ethylvinylbenzene, and t-butylstyrene, from the viewpoint of copolymerizability with the ethylenically unsaturated group of the (A) curable resin.

[0055] The aromatic divinyl compound is not particularly limited as long as it has an aromatic ring skeleton and two vinyl groups. Specific examples of the aromatic divinyl compound include divinylbenzene, divinylnaphthalene, divinylanthracene, and divinylbiphenyl. Among these, from the viewpoint of obtaining a cured product with excellent appearance, the aromatic divinyl compound is preferably divinylbenzene.

[0056] The aromatic vinyl compound preferably contains divinylbenzene and at least one selected from the group consisting of ethylvinylbenzene and styrene.

[0057] The (B) ethylenically unsaturated monomer may contain a compound other than an aromatic vinyl compound. Specific examples of the compound other than an aromatic vinyl compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate. Examples of the unsaturated monobasic acid include (meth)acrylates such as ethylene glycol di(meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, allyl (meth)acrylate, isobornyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate, as well as unsaturated monobasic acids such as methacrylic acid, acrylic acid, crotonic acid, and cinnamic acid. As mentioned above, any unreacted (b) unsaturated monobasic acid remaining after synthesis of the (A-1) vinyl ester resin is considered to be the (B) ethylenically unsaturated monomer.

[0058] The content of the (B) ethylenically unsaturated monomer is preferably 5 to 95 parts by mass, more preferably 25 to 90 parts by mass, and even more preferably 40 to 80 parts by mass, per 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer. When the content of the (B) ethylenically unsaturated monomer is 5 parts by mass or more, the viscosity of the curable resin composition can be adjusted within an appropriate range, and good moldability is achieved. When the content of the (B) ethylenically unsaturated monomer is 95 parts by mass or less, the mechanical strength of the cured product is good.

[0059] The content of the aromatic vinyl compound is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, relative to 100 mol% of the total of the (B) ethylenically unsaturated monomers. When the content of the aromatic vinyl compound is 70 mol% or more, the cured product of the curable resin composition has good adhesion. The content of the aromatic vinyl compound can be 100 mol% or less, 98 mol% or less, or 97 mol% or less, relative to the total of the (B) ethylenically unsaturated monomers.

[0060] The content of the aromatic divinyl compound is preferably 5 to 50 mol %, more preferably 7 to 35 mol %, and even more preferably 8 to 30 mol %, based on the total amount of (B) the ethylenically unsaturated monomer. When the content of the aromatic divinyl compound is 5 mol % or more, a cured product with excellent appearance can be molded. When the content of the aromatic divinyl compound is 50 mol % or less, the handleability of the curable resin composition, such as storage stability, can be improved.

[0061] The total content of vinyl groups in the aromatic vinyl compound is 60 to 95 mol%, more preferably 65 to 90 mol%, based on the total of the ethylenically unsaturated groups contained in (A) the curable resin and (B) the ethylenically unsaturated monomer. When the total content of vinyl groups is 60 mol% or more, a sufficient amount of aromatic vinyl compound is contained, resulting in good adhesion of the cured product to the substrate. When the total content of vinyl groups is 95 mol% or less, it is advantageous from the viewpoint of environmental resistance.

[0062] <(C) Low-shrinkage agent> The curable resin composition contains a (C) low-profile agent to reduce molding shrinkage. The (C) low-profile agent contains at least one or more selected from the group consisting of vinyl acetate polymers and block copolymers having vinyl acetate as a monomer unit. By containing a vinyl acetate polymer or a block copolymer having vinyl acetate as a monomer unit, the cured product exhibits a low-shrinkage effect while maintaining adhesion.

[0063] A block copolymer having vinyl acetate as a monomer unit is composed of a block made of a vinyl acetate polymer and a block made of a polymer of another monomer. The other monomer is not particularly limited, and examples thereof include styrene and methyl (meth)acrylate. Among them, a styrene-vinyl acetate block copolymer is preferred from the viewpoint of adhesion of the cured product.

[0064] Other (C) low-profile agents other than vinyl acetate polymers and block copolymers having vinyl acetate as a monomer unit are not particularly limited, and any known agent in the technical field of the present invention can be used. Among these, thermoplastic resins are preferred. Examples of other (C) low-profile agents include polystyrene, polyethylene, polymethyl methacrylate, block copolymers combining the raw monomers of the above compounds, saturated polyesters, polycaprolactone, and styrene-butadiene rubber. The (C) low-profile agents may be used alone or in combination of two or more.

[0065] The content of the (C) low shrinkage agent is 5 to 50 parts by mass per 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer. The content of the (C) low shrinkage agent is preferably 10 to 40 parts by mass, and more preferably 25 to 35 parts by mass. If the content of the (C) low shrinkage agent is 5 parts by mass or more, the shrinkage rate of the cured product is small, and the desired dimensional accuracy can be obtained in the molded product. If the content of the (C) low shrinkage agent is 50 parts by mass or less, the mechanical properties of the cured product are better.

[0066] The (C) low shrinkage agent contains at least one selected from the group consisting of vinyl acetate polymers and block copolymers having vinyl acetate as a monomer unit in an amount of 55 to 100 mass %, preferably 65 to 100 mass %, based on the total amount of the (C) low shrinkage agent. Within this range, a cured product with good adhesion can be obtained, and the shrinkage rate during molding can also be reduced.

[0067] <(D) Inorganic filler> As the (D) inorganic filler, any particulate material known in the technical field of the present invention can be used. The use of the (D) inorganic filler can reduce the molding shrinkage of the molded article, improve workability by adjusting the viscosity of the curable resin composition, or improve the strength of the molded article.

[0068] Examples of (D) inorganic fillers include calcium carbonate, silica, aluminum oxide, aluminum hydroxide, barium sulfate, calcium sulfate, calcium hydroxide, calcium oxide, magnesium oxide, magnesium hydroxide, wollastonite, clay, kaolin, mica, gypsum, silicic anhydride, and glass powder. Among these, at least one selected from the group consisting of calcium carbonate, aluminum oxide, and aluminum hydroxide is preferred because it is inexpensive. (D) inorganic fillers may be used alone or in combination of two or more.

[0069] The average particle size of the (D) inorganic filler is preferably 1 to 100 μm, more preferably 1 to 60 μm, and even more preferably 1 to 50 μm. When the average particle size of the (D) inorganic filler is 1 μm or more, particle aggregation can be suppressed. When the average particle size of the (D) inorganic filler is 100 μm or less, the moldability of the curable resin composition is good.

[0070] In the present disclosure, the "average particle size" refers to the 50% particle size (D50) in the volume-based cumulative particle size distribution measured using a laser diffraction / scattering particle size distribution analyzer (FRA, Microtrack Bell Co., Ltd.).

[0071] The shape of the (D) inorganic filler is not particularly limited, and examples thereof include nearly spherical, ellipsoidal, scaly, and amorphous shapes.

[0072] The amount of (D) inorganic filler is preferably 200 to 700 parts by mass, and more preferably 300 to 650 parts by mass, per 100 parts by mass of the total of (A) curable resin and (B) ethylenically unsaturated monomer. If the amount of (D) inorganic filler is 200 parts by mass or more, the mechanical properties of the cured product will be better. If the amount of (D) inorganic filler is 700 parts by mass or less, the (D) inorganic filler will be more uniformly dispersed in the curable resin composition, allowing for the production of a homogeneous molded product.

[0073] <(E) Thermal polymerization initiator> The (E) thermal polymerization initiator is not particularly limited as long as it is a polymerization initiator that generates radicals upon heating. Examples of the (E) thermal polymerization initiator include peroxides such as diacyl peroxides, peroxyesters, hydroperoxides, dialkyl peroxides, ketone peroxides, peroxyketals, alkyl peresters, and percarbonates.

[0074] Among these peroxides, at least one selected from the group consisting of 1,1-di-t-hexylperoxycyclohexane, t-hexylperoxyisopropyl monocarbonate, t-butyl peroxyoctoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, benzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, t-butyl peroxybenzoate, dicumyl peroxide, and di-t-butyl peroxide is preferred. (E) Thermal polymerization initiators may be used alone or in combination of two or more.

[0075] The amount of (E) thermal polymerization initiator is preferably 0.1 to 25 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.5 to 10 parts by mass, and particularly preferably 1 to 7 parts by mass, per 100 parts by mass of the total of (A) curable resin and (B) ethylenically unsaturated monomer. When the amount of (E) thermal polymerization initiator is 0.1 part by mass or more, the curing reaction during molding of the curable resin composition proceeds uniformly, resulting in good physical properties and appearance of the cured product. When the amount of (E) thermal polymerization initiator is 25 parts by mass or less, the storage stability of the curable resin composition is good and handling is improved.

[0076] <(F) Glass fiber> The curable resin composition may contain (F) glass fibers as needed. The (F) glass fibers are not particularly limited as long as they are fibrous materials with an aspect ratio of 3 or more. Specific examples include chopped strand glass.

[0077] The fiber length of the (F) glass fiber is preferably 20 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. When the fiber length is 20 mm or less, the moldability of the curable resin composition is good and the appearance of the cured product is good. The fiber length is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 1 mm or more. When the fiber length is 0.1 mm or more, the strength of the cured product is good. The average fiber diameter of the (F) glass fiber is preferably 3 to 100 μm, and more preferably 5 to 30 μm.

[0078] The content of the (F) glass fiber is preferably 10 to 300 parts by mass, more preferably 15 to 200 parts by mass, and even more preferably 30 to 100 parts by mass, per 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer. If the content of the (F) glass fiber is 10 parts by mass or more, the mechanical properties of the molded article obtained from the curable resin composition will be better. If the content of the (F) glass fiber is 300 parts by mass or less, the (F) glass fiber will be more uniformly dispersed in the curable resin composition, allowing for the production of a homogeneous molded article.

[0079] <(G) Acidic Surfactants> The curable resin composition may further contain (G) an acidic surfactant, as needed. The (G) acidic surfactant is a low-volatile substance having a surface-active effect and an acid value, and is not particularly limited as long as it is a compound that has excellent compatibility with the (A) curable resin and the (B) ethylenically unsaturated monomer, and excellent dispersibility of the (D) inorganic filler and the (F) glass fiber.

[0080] In the present disclosure, when a compound corresponds to both a saturated polybasic acid and a (G) acidic surfactant, the compound is classified as a (G) acidic surfactant.

[0081] In the present disclosure, a low-volatile substance is a substance that has a weight retention rate of 90% or more when heated at 150°C for 60 minutes in an atmospheric environment. The molecular weight or weight-average molecular weight of the low-volatile substance is, for example, 500 or more, 1,000 or more, or 1,500 or more. The upper limit of the molecular weight or weight-average molecular weight of the low-volatile substance is not particularly limited, but may be, for example, 7,000 or less, 6,000 or less, or 5,000 or less.

[0082] As the (G) acidic surfactant, those generally known as dispersants or plasticizers for resin compositions can be suitably used. Among them, low-volatile oligomers are preferred, low-volatile oligomers having a constituent component containing a monomer unit such as an ethylene unit, a styrene unit, an ester unit, an ether unit, or a urethane unit, and an acid group such as a carboxy group, a sulfo group, or a phospho group are more preferred, phosphate ester compounds or carboxylic acid ester compounds are even more preferred, and phosphate ester compounds containing a long-chain polyester structure are even more preferred.

[0083] In order to improve the adhesion of the cured product, it is effective to improve the wettability of the curable resin composition to the substrate (adherend), and for this purpose, it is considered important that the curable resin composition has an acid value. The use of a (G) acidic surfactant having an acid value improves the adhesion of the cured product. Furthermore, when the curable resin composition is heat-cured, a (G) acidic surfactant with low volatility is used to prevent the adhesion of the cured product from being affected by the volatilization or bleed-out of the (G) acidic surfactant.

[0084] Suitable examples of the phosphate ester compound include those described in JP-A-61-194091, JP-A-3-112992, JP-A-2007-527896, and JP-A-2014-520127. Specific examples include a phosphate triester compound of methyl ester of 12-hydroxystearic acid polyester, and an ester compound of tetraphosphoric acid with polyethylene glycol monomethyl ether and an ester compound of malic acid.

[0085] As the (G) acidic surfactant, commercially available products can also be used, and examples thereof include the following product names from BYK Additives & Instruments: BYK(trademark)-W 9010, BYK(trademark)-W 9011, BYK(trademark)-P 9051, BYK(trademark)-P 9050, BYK(trademark)-P 9060, BYK(trademark)-P 9065, BYK(trademark)-P 9080, and BYK(trademark)-P 9085. Among these, from the viewpoint of adhesion of the cured product, at least one selected from the group consisting of BYK(trademark)-W 9010 and BYK(trademark)-P 9051 is preferred.

[0086] The acid value of the (G) acidic surfactant is preferably 20 mgKOH / g or more, more preferably 30 to 190 mgKOH / g, even more preferably 100 to 180 mgKOH / g, and particularly preferably 120 to 160 mgKOH / g. When the acid value is 20 mgKOH / g or more, the amount of the (G) acidic surfactant can be kept within an appropriate range to ensure the acid value of the curable resin composition, and there is no adverse effect on the properties of the cured product, such as adhesion.

[0087] The content of (G) acidic surfactant is preferably 0.1 to 25 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 18 parts by mass, per 100 parts by mass of the total of (A) curable resin and (B) ethylenically unsaturated monomer. When the content of (G) acidic surfactant is 0.1 part by mass or more, the curable resin composition has a sufficient acid value, and a cured product with good adhesion can be obtained. When the content of (G) acidic surfactant is 25 parts by mass or less, the properties of the cured product are not adversely affected.

[0088] <Other additives> In addition to the above components, the curable resin composition may contain components known in the technical field of the present invention, such as viscosity modifiers such as thickeners, colorants, polymerization inhibitors, and viscosity reducers, and molding aids such as mold release agents, within a range that does not impair the effects of the present invention.

[0089] The thickener is a compound other than the (D) inorganic filler that exhibits a thickening effect, and examples thereof include isocyanate compounds. The thickener may be used alone or in combination of two or more. The content of the thickener can be appropriately adjusted depending on the handleability, flowability, etc. required for the curable resin composition.

[0090] A colorant is used when coloring a cured product. Various dyes, inorganic pigments, and organic pigments can be used as colorants. The colorants may be used alone or in combination of two or more. The content of the colorant can be adjusted appropriately depending on the degree of coloration desired in the cured product.

[0091] Examples of polymerization inhibitors include hydroquinone, trimethylhydroquinone, p-benzoquinone, naphthoquinone, t-butylhydroquinone, catechol, pt-butylcatechol, and 2,6-di-t-butyl-4-methylphenol. The polymerization inhibitors may be used alone or in combination. The content of the polymerization inhibitor can be appropriately adjusted depending on the storage environment and period of the curable resin composition, curing conditions, etc.

[0092] 2. Method for producing curable resin composition The curable resin composition can be produced by mixing (A) a curable resin, (B) an ethylenically unsaturated monomer, (C) a low-profile agent, (D) an inorganic filler, (E) a thermal polymerization initiator, and (F) glass fibers, and, as necessary, an optional component (G) an acidic surfactant and other additives other than the (G) acidic surfactant.

[0093] An example of a mixing method is kneading. The kneading method is not particularly limited, and for example, a kneader, a disperser, or a planetary mixer can be used. The kneading temperature is preferably 5°C to 50°C, and more preferably 10 to 40°C.

[0094] The order in which the components are mixed when producing a curable resin composition is not particularly limited. For example, it is preferable to mix the (A) curable resin with part or all of the (B) ethylenically unsaturated monomer and then mix the other components, as this makes it easier to obtain a curable resin composition in which the components are sufficiently dispersed or uniformly mixed. At least a part of the (B) ethylenically unsaturated monomer may be mixed in advance with the (A) curable resin so that it acts as a solvent, dispersion medium, etc.

[0095] One method for mixing the (F) glass fibers is to prepare glass fibers having a predetermined fiber length distribution in advance and then mix the (F) glass fibers into a composition containing components other than the (F) glass fibers. This method allows for fine adjustment of the fiber length distribution of the (F) glass fibers. This method is simple because it does not require breaking the (F) glass fibers beforehand. Another method involves preparing a curable resin composition containing the (F) glass fibers, and then breaking the (F) glass fibers by kneading to achieve a predetermined fiber length distribution. The fiber length distribution of the (F) glass fibers can be controlled by conditions such as the type and amount of other components to be kneaded, the type of stirrer, the stirring speed, the stirring temperature, and the stirring time.

[0096] 3. Method for producing cured product The curable resin composition can be cured by heating. The conditions for curing the curable resin composition can be appropriately set depending on the materials used. An example of preferred conditions is a temperature of 120 to 180°C, more preferably a temperature of 120 to 160°C, and a curing time of 1 to 30 minutes.

[0097] 4. Method for manufacturing molded body The curable resin composition can be molded into a desired shape and cured to produce a molded article containing a cured product of the curable resin composition. The molding and curing methods are not particularly limited, and methods commonly used in the technical field of the present invention, such as compression molding, transfer molding, and injection molding, can be used.

[0098] Examples of methods for molding and curing a curable resin composition include a method in which a mold is opened, the curable resin composition is poured into the mold, and cured; and a method in which the curable resin composition is poured into a closed mold from the outside through a hole in the mold, such as a sprue, under reduced pressure inside the mold or under pressure applied from the outside, as in injection molding. The conditions for curing the curable resin composition in the mold can be appropriately set depending on the material used. An example of a preferred condition is a temperature of 120 to 180°C, more preferably a temperature of 120 to 160°C, and a curing time of 1 to 30 minutes.

[0099] In one embodiment, an electric / electronic component is provided that includes a cured product of the curable resin composition. The electric / electronic component can be produced, for example, by encapsulating components of the electric / electronic component with the curable resin composition and then curing the curable resin composition by heating. The encapsulation of the components of the electric / electronic component can be achieved, for example, by injecting the curable resin composition into a housing having the components therein.

[0100] From the viewpoint of adhesion, the curable resin composition is suitable for use with polyphenylene sulfide (PPS) substrates, polybutylene terephthalate (PBT) substrates, epoxy glass substrates, and copper substrates. In particular, excellent adhesion can be obtained with poorly adhesive resin substrates such as PPS substrates. By using the curable resin composition, it is possible to omit the surface treatment step using a primer, plasma, or the like, which is generally performed on poorly adhesive resin substrates such as PPS substrates. [Example]

[0101] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0102] (A) Curing resin The bisphenol A vinyl ester resin obtained in the following synthesis example was used.

[0103] [Synthesis Example 1] Synthesis of vinyl ester resin A 1-L four-neck flask equipped with a thermometer, stirrer, gas inlet, and reflux condenser was charged with 478.9 g of bisphenol A epoxy resin (Araldite® AER-2603, Asahi Kasei E-Materials Corporation) with an epoxy equivalent of 188.0 and 73.1 g of methacrylic acid (Kuraray Co., Ltd.) in which 0.35 g of methylhydroquinone had been dissolved. The mixture was heated with stirring. When the temperature reached 100-110°C, 146.2 g of methacrylic acid in which 1.4 g of 2,4,6-tris(dimethylaminomethyl)phenol (Seikuol® TDMP, Seiko Chemical Co., Ltd.) had been dissolved was added dropwise over 30 minutes, and the mixture was allowed to react at 130°C. When the acid value reached 30 mgKOH / g or less, the mixture was cooled, and 150 g of styrene and 0.1 g of hydroquinone were added to synthesize a styrene-diluted bisphenol A vinyl ester resin containing 25% by mass of styrene and 2% by mass of unreacted methacrylic acid. The number-average molecular weight of the resulting bisphenol A vinyl ester resin was 500 g / mol.

[0104] The other components used were as follows:

[0105] (B) Ethylenically unsaturated monomer Styrene (manufactured by Idemitsu Kosan Co., Ltd.) DVB-570 (a mixture of 57% divinylbenzene and 43% ethylvinylbenzene by mass, manufactured by Nippon Steel Chemical & Material Co., Ltd.) Methacrylic acid (Kuraray Co., Ltd.)

[0106] (C) Low-shrinkage agent Modiper (trademark) S501 (styrene-vinyl acetate block copolymer, NOF Corporation) Sakunoru (trademark) SN-04T (vinyl acetate polymer, Denka Co., Ltd.) MS-200 (Polystyrene, Sekisui Chemical Co., Ltd.) Polyethylene powder (Takehara Chemical Industry Co., Ltd.) Lucant™ HC-100 (ethylene-propylene copolymer, Mitsui Chemicals, Inc.) Tuftec™ H1041G (styrene-ethylene-butylene-styrene block copolymer, Asahi Kasei Chemicals Corporation) Kraton™ G1701 (styrene-ethylene-propylene-styrene block copolymer, Kraton Polymer Japan Co., Ltd.)

[0107] (D) Inorganic filler Softon 1200BM (calcium carbonate, average particle size: 1.80 μm, Bihoku Funka Kogyo Co., Ltd.) B-103 (aluminum hydroxide, average particle size: 8 μm, Nippon Light Metal Co., Ltd.)

[0108] (E) Thermal polymerization initiator Luperox™ 575 (t-amylperoxy-2-ethylhexanoate, manufactured by Arkema Yoshitomi Co., Ltd.)

[0109] (F) Glass fiber: ECS 03 B-173 / P9 (fiber diameter: 13 μm, fiber length: 3 mm, Nippon Electric Glass Co., Ltd.)

[0110] (G) Acidic surfactants BYK (trademark)-P 9051 (polyester dispersant, acid value: 157 mg KOH / g, BYK) BYK(TM)-W 9010 (copolymer-based viscosity reducer with acidic groups, acid value: 129 mg KOH / g, BYK)

[0111] [Example 1] (Preparation of Curable Resin Composition) (A) 66.5 parts by mass of the styrene-diluted bisphenol A vinyl ester resin synthesized in Synthesis Example 1 as a curable resin (containing 48.6 parts by mass of bisphenol A vinyl ester resin, 16.5 parts by mass of styrene, and 1.3 parts by mass of unreacted methacrylic acid), (B) 27.6 parts by mass of styrene and 10.0 parts by mass of DVB-570 (5.7 parts by mass of divinylbenzene, 4.3 parts by mass of ethylenically unsaturated monomers), (C) 30 parts by mass of Modiper (trademark) S501 as a low-shrinkage agent, (D) 240 parts by mass of Softon 1200BM and 240 parts by mass of B-103 as inorganic fillers, (E) 4 parts by mass of Luperox (trademark) 575 as a thermal polymerization initiator, (F) 71 parts by mass of ECS 03 B-173 / P9 as glass fibers, and (G) BYK (trademark)-P as an acidic surfactant. Ten parts by mass of BYK 9051 and 7 parts by mass of BYK (trademark)-W 9010 were charged into a twin-arm kneader and kneaded for 30 minutes at 30° C. to prepare a curable resin composition.

[0112] The materials used and their compositions are shown in Table 1. In Table 1, only the amount of vinyl ester resin is listed for (A) curable resin, and the styrene and unreacted methacrylic acid used to dilute the vinyl ester resin are included as (B) ethylenically unsaturated monomer.

[0113] (Preparation of cured product) The prepared curable resin composition was transferred to a transfer molding machine (model: MF-070, Press Machinery Co., Ltd.) at a mold temperature of 140°C and a molding pressure of 15 kgf / cm. 2 The mixture was molded under the conditions of 180 seconds curing time, and a molded product (cured product) in the shape of a pudding cup (diameter of the substrate side: 5 mm, height: 3 mm) was produced on a PPS (polyphenylene sulfide) substrate.

[0114] (average adhesion strength) To evaluate the adhesion of the cured product to the substrate, a lateral load was applied to the molded product at a constant rate of 2 mm / min at 25°C using a die shear tester (Daisi Corporation), and the strength at the time of shear failure was measured five times, and the average value was calculated as the average adhesion strength. The results are shown in Table 1.

[0115] (Mold shrinkage rate) To evaluate the molding shrinkage of the cured product, a shrink disk (φ90mm x 11mm) was compression molded in a compression molding machine (Technomarushi Co., Ltd.) under conditions of a molding temperature of 140°C, a molding pressure of 5MPa, and a molding time of 3 minutes, in accordance with JIS K 6911:2006 "5.7 Molding shrinkage and heat shrinkage (molding materials)," and the molding shrinkage was calculated. The results are shown in Table 1.

[0116] (Injection moldability) To evaluate injection moldability, a molded product of the same shape as the shrink disk molded above was produced using an injection molding machine under the same conditions, and injection moldability was evaluated. Products that could be injection molded without any problems were rated as good, and products that could not be injection molded due to insufficient filling or other reasons were rated as poor. The results are shown in Table 1.

[0117] [Examples 2 to 4, Comparative Examples 1 to 8] Curable resin compositions were prepared in the same manner as in Example 1, except that materials were used in the compositions shown in Tables 1 to 3. Then, cured products were prepared in the same manner as in Example 1, and various evaluations were carried out. The results are shown in Tables 1 to 3.

[0118] [Table 1]

[0119] [Table 2]

[0120] [Table 3] [Industrial Applicability]

[0121] The curable resin composition of the present invention provides a curable resin composition that exhibits excellent adhesion to substrates, particularly poorly adhesive resin substrates, and that can produce a cured product having a low shrinkage rate. Also provided are electrical and electronic components that incorporate such a cured product as an encapsulant, and a method for producing the same. The curable resin composition is preferably used for encapsulating and fixing wiring boards and electronic components mounted on the wiring boards, which are used in electronic devices such as motors, coils, connectors, and electronic control units installed in automobiles.

Claims

1. (A) Curable resin, (B) an ethylenically unsaturated monomer, (C) a low shrinkage agent, (D) inorganic filler, (E) a thermal polymerization initiator, and (F) Glass fiber Including, The (A) curable resin contains a vinyl ester resin, the content of the (C) low shrinkage agent is 5 to 50 parts by mass per 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer, the (C) low shrinkage agent contains at least one selected from the group consisting of vinyl acetate polymers and block copolymers having vinyl acetate as a monomer unit in an amount of 55 to 100 mass % based on the total amount of the (C) low shrinkage agent; the (B) ethylenically unsaturated monomer contains an aromatic vinyl compound, The aromatic vinyl compound includes an aromatic monovinyl compound and an aromatic divinyl compound, a total content of vinyl groups in the aromatic vinyl compound is 60 to 95 mol % based on the total of ethylenically unsaturated groups contained in the (A) curable resin and the (B) ethylenically unsaturated monomer; Curable resin composition.

2. 2. The curable resin composition according to claim 1, wherein the content of the aromatic divinyl compound is 5 to 50 mol % based on the total of the ethylenically unsaturated monomers (B).

3. The curable resin composition according to claim 1 or 2, wherein the content of the aromatic vinyl compound is 70 mol% or more based on the total amount of the ethylenically unsaturated monomer (B).

4. The curable resin composition according to any one of claims 1 to 3, wherein the aromatic divinyl compound is divinylbenzene.

5. The curable resin composition according to any one of claims 1 to 4, wherein the aromatic vinyl compound comprises divinylbenzene and at least one selected from the group consisting of ethylvinylbenzene and styrene.

6. relative to 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer, The content of the (A) curable resin is 5 to 95 parts by mass, the content of the (B) ethylenically unsaturated monomer is 5 to 95 parts by mass, the content of the (C) low shrinkage agent is 5 to 50 parts by mass, The content of the (D) inorganic filler is 200 to 700 parts by mass, the content of the thermal polymerization initiator (E) is 0.1 to 25 parts by mass, The curable resin composition according to any one of claims 1 to 5, wherein the content of the (F) glass fiber is 10 to 300 parts by mass.

7. The curable resin composition according to any one of claims 1 to 6, further comprising (G) an acidic surfactant.

8. An electric / electronic part comprising a cured product of the curable resin composition according to any one of claims 1 to 7.

9. A step of injection molding the curable resin composition according to any one of claims 1 to 7 to encapsulate components of an electric / electronic device; and A method for producing an electric / electronic component, comprising the step of heat-curing the curable resin composition.

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