CURABLE RESIN COMPOSITION, ELECTRICAL / ELECTRONIC COMPONENT, AND METHOD FOR MA

Abstract

Provided is a curable resin composition which can be injection molded and has exceptional yield, and from which it is possible to obtain a cured product having excellent appearance and exceptional adhesion to a substrate, particularly to a hardly adhesive resin substrate. A curable resin composition including a curable resin (A), an ethylenically unsaturated monomer (B), an inorganic filler (C), a heat polymerization initiator (D), glass fibers (E), and a low constrictive agent (F), the curable resin (A) containing at least a vinyl ester resin, the ethylenically unsaturated monomer (B) containing at least an aromatic vinyl compound, the aromatic vinyl compound containing at least an aromatic divinyl compound, and the ratio of the total quantity of vinyl groups in the aromatic vinyl compound to the total quantity of ethylenically unsaturated groups included in the curable resin (A) and the ethylenically unsaturated monomer (B) being 60-95 mol%.

Description

[Technical field]

[0001] The present invention relates to a curable resin composition, an electric / electronic component, and a method for producing an electric / electronic component. [Background technology]

[0002] In electronic devices such as motors, coils, and electronic control units mounted on 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 to prevent damage to the components due to vibration and 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 with 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 / 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] JP 2014-148586 A [Patent Document 2] JP 2004-27019 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, epoxy resins have a problem 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 which can be injection molded, has excellent productivity, and gives a cured product which has excellent adhesion to a substrate, particularly a poorly adhesive resin substrate, and has a good appearance. Another aim of the present invention is to provide an electric / electronic component which includes such a cured product as an encapsulant, and a method for producing the same. [Means for solving the problem]

[0007] The present invention includes the following aspects. [1] (A) Curing resin, (B) an ethylenically unsaturated monomer, (C) Inorganic filler, (D) a thermal polymerization initiator, (E) Glass fibers, and (F) Low shrinkage agent Including, The (A) curable resin contains at least a vinyl ester resin, The (B) ethylenically unsaturated monomer contains at least an aromatic vinyl compound, The aromatic vinyl compound contains at least an aromatic divinyl compound, a ratio of a total amount of vinyl groups contained in the aromatic vinyl compound to a total amount of ethylenically unsaturated groups contained in the (A) curable resin and the (B) ethylenically unsaturated monomer is 60 to 95 mol %. Curable resin composition. [2] The curable resin composition according to [1], wherein the ratio of the aromatic divinyl compound contained in the (B) ethylenically unsaturated monomer is 5 to 50 mol %. [3] The curable resin composition according to either [1] or [2], wherein the proportion of the aromatic vinyl compound contained in the (B) ethylenically unsaturated monomer is 70 mol % or more. [4] The curable resin composition according to any one of [1] to [3], wherein the aromatic divinyl compound is divinylbenzene. [5] The curable resin composition according to any one of [1] to [4], wherein the aromatic vinyl compound comprises divinylbenzene and at least one selected from ethylvinylbenzene and styrene. [6] For a total of 100 parts by mass of the curable resin (A) and the ethylenically unsaturated monomer (B), (A) 5 to 95 parts by mass of a curable resin, (B) 5 to 95 parts by mass of an ethylenically unsaturated monomer, (C) 200 to 700 parts by mass of an inorganic filler, (D) 0.1 to 20 parts by mass of a thermal polymerization initiator, (E) 10 to 300 parts by mass of glass fibers, and (F) 10 to 80 parts by mass of a low shrinkage agent The curable resin composition according to any one of [1] to [5], [7] The curable resin composition according to any one of [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 [1] to [7]. [9] A method for producing an electric / electronic component, comprising: a step of injection-molding the curable resin composition according to any one of [1] to [7] to encapsulate components of the electric / electronic component; and a step of heat-curing the curable resin composition. Effect of the Invention

[0008] According to the present invention, it is possible to provide a curable resin composition which can be injection molded, has excellent productivity, and gives a cured product having excellent adhesion to a substrate, particularly a poorly adhesive resin substrate, and a good appearance. Furthermore, it is possible to provide a cured product 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 PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail, however, the present invention is not limited to the embodiments described below.

[0010] In this specification, "(meth)acrylic acid" means methacrylic acid or acrylic acid, and "(meth)acrylate" means acrylate or methacrylate.

[0011] The term "ethylenically unsaturated bond" refers to a double bond formed between carbon atoms other than 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. The term "vinyl group" refers to CH2=CH- and does not include 1-alkenyl groups such as allyl groups. However, the "vinyl" in vinyl ester resin is not limited to this.

[0012] 1. Curable resin composition The curable resin composition of one embodiment contains (A) a curable resin, (B) an ethylenically unsaturated monomer, (C) an inorganic filler, (D) a thermal polymerization initiator, (E) glass fibers, and (F) a low shrinkage agent.

[0013] The curable resin composition may further contain (G) an acidic surfactant, if necessary.

[0014] [(A) Curing resin] The (A) curable resin is not particularly limited as long as it is a curable resin generally used for sealing material applications. For example, a resin having a functional group capable of forming a crosslinked structure when the curable resin composition is heated and cured is preferred. Specific examples of the (A) curable resin include (A-1) vinyl ester resin, (A-2) unsaturated polyester resin, (A-3) urethane (meth)acrylate resin, (A-4) diallyl phthalate resin, (A-5) epoxy resin, etc. From the viewpoint of material cost and moldability, the (A) curable resin contains at least (A-1) vinyl ester resin. The (A) curable resin may be used alone or in combination of two or more kinds.

[0015] The content of the vinyl ester resin (A-1) in the curable resin (A) 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 vinyl ester resin (A-1) is 75% by mass or more, the material cost of the curable resin composition can be reduced, and a cured product having better moldability and better adhesion can be obtained. The upper limit of the content of the vinyl ester resin (A-1) in the curable resin (A) is not particularly limited. For example, it may be 100% by mass, 97% by mass, or 95% by mass.

[0016] 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.

[0017] <(A-1) Vinyl ester resin> (A-1) vinyl ester resin is generally a compound having a radical polymerizable unsaturated bond obtained by a ring-opening reaction between (a) an epoxy group in an epoxy compound having two or more epoxy groups and (b) a carboxy group of an unsaturated monobasic acid having a radical polymerizable unsaturated bond and a carboxy group. (A-1) vinyl ester resin is described, for example, in the Polyester Resin Handbook (published by Nikkan Kogyo Shimbun, 1988).

[0018] The vinyl ester resin (A-1) may be used alone or in combination of two or more kinds. In terms of handling, the vinyl ester resin (A-1) is generally used by diluting it with an ethylenically unsaturated monomer (B). By using the vinyl ester resin (A-1), the material cost of the curable resin composition can be reduced and a cured product having excellent adhesion can be obtained.

[0019] The number average molecular weight (Mn) of the (A-1) vinyl ester resin can be adjusted depending on the desired physical properties, but from the viewpoint of handling, it is preferably in the range of 500 to 5,000. In this specification, 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. Equipment: 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 solution of sample in tetrahydrofuran Flow rate: 1mL / min Eluent: Tetrahydrofuran Detector: Shodex (registered trademark) RI-71S (Showa Denko K.K.)

[0020] ((a) Epoxy Compound) The (a) epoxy compound is not particularly limited as long as it is a compound having two or more epoxy groups. It is preferably at least one selected from the group consisting of bisphenol-type epoxy compounds and novolac phenol-type epoxy compounds, and more preferably 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.

[0021] Examples of the bisphenol type epoxy compound include those obtained by reacting a bisphenol compound such as bisphenol A, bisphenol F, bisphenol S, and tetrabromobisphenol A with epichlorohydrin and / or methyl epichlorohydrin; and those obtained by reacting a compound obtained by glycidyl etherifying one or more of the above bisphenol compounds with a condensate of one or more of the above bisphenol compounds with epichlorohydrin and / or methyl epichlorohydrin. 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.

[0022] Examples of novolak phenol type epoxy compounds include those obtained by reacting phenol novolak or cresol novolak with epichlorohydrin and / or methyl epichlorohydrin.

[0023] ((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, and is preferably methacrylic acid, acrylic acid, crotonic acid, cinnamic acid, etc., more preferably acrylic acid or methacrylic acid, and even more preferably methacrylic acid from the viewpoint of the corrosion resistance of the cured product.

[0024] ((A-1) Method for synthesizing vinyl ester resin) The vinyl ester resin (A-1) can be synthesized by a known synthesis method, for example, a method in which an unsaturated monobasic acid (b) is added in the presence of an esterification catalyst and an epoxy compound (a) in a reaction vessel capable of being heated and stirred, and the reaction is carried out at 70 to 150°C, preferably 80 to 140°C, and more preferably 90 to 130°C.

[0025] Incidentally, the unreacted (b) unsaturated monobasic acid remaining after synthesis of the (A-1) vinyl ester resin is regarded as the (B) ethylenically unsaturated monomer described below.

[0026] As the esterification catalyst, for example, known catalysts such as tertiary amines such as triethylamine, N,N-dimethylbenzylamine, N,N-dimethylaniline, diazabicyclooctane, triphenylphosphine, diethylamine hydrochloride, etc. can be used.

[0027] The compounding ratio of the (a) epoxy compound and the (b) unsaturated monobasic acid is preferably such that the total amount of the carboxyl groups of the (b) unsaturated monobasic acid is 0.3 to 1.2 moles per mole of the total amount of the epoxy groups of the (a) epoxy compound, more preferably 0.4 to 1.1 moles, and even more preferably 0.5 to 1.0 moles. When the total amount of the carboxyl groups of the (b) unsaturated monobasic acid is 0.3 moles or more, a cured product having sufficient hardness can be obtained when the curable resin composition is cured. On the other hand, when the total amount of the carboxyl groups of the (b) unsaturated monobasic acid is 1.2 moles or less, the amount of unreacted (b) unsaturated monobasic acid can be reduced when synthesizing the (A-1) vinyl ester resin, so that the acid value of the mixture of the (A) component and the (B) component can be reduced, and a cured product with better adhesion can be obtained.

[0028] The unreacted (b) unsaturated monobasic acid after synthesis of the (A-1) vinyl ester resin can be used as it is as the (B) ethylenically unsaturated monomer of the curable resin composition without being removed. 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, so it is better 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, based on the total amount of the (A-1) vinyl ester resin and the unreacted (b) unsaturated monobasic acid.

[0029] <(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. By using the (A-2) unsaturated polyester resin, a cured product having excellent mechanical strength and heat resistance can be obtained.

[0030] In the present disclosure, styrene monomers and the like contained in general unsaturated polyester resins are classified as (B) ethylenically unsaturated monomers.

[0031] The polyhydric alcohol 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, hydrogenated bisphenol A, bisphenol A, alkylene oxide-modified bisphenol A, such as ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A, and glycerin. From the viewpoints of heat resistance and mechanical strength of the cured product and fluidity of the curable resin composition during molding, propylene glycol, dipropylene glycol, neopentanediol, hydrogenated bisphenol A, and bisphenol A are preferred, and propylene glycol is more preferred. The polyhydric alcohols may be used alone or in combination of two or more.

[0032] The unsaturated polybasic acid is not particularly limited as long as it has an ethylenically unsaturated bond and has two or more carboxy groups or its acid anhydride, and known compounds can be used. In particular, unsaturated polybasic acids having 4 to 6 carbon atoms or their acid anhydrides are preferred because they are less expensive and provide a curable resin composition having excellent mechanical strength and heat resistance of the cured product. Examples of unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, itaconic acid, and chloromaleic acid. More preferred are unsaturated polybasic acids selected from fumaric acid, maleic acid, maleic anhydride, and itaconic acid. The unsaturated polybasic acids may be used alone or in combination of two or more.

[0033] Preferred combinations of polyhydric alcohols and unsaturated polybasic acids 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, a combination of fumaric acid, hydrogenated bisphenol A and propylene glycol, etc. 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 less expensive and can provide a curable resin composition having a higher heat distortion temperature of the cured product and superior mechanical strength and heat resistance.

[0034] The saturated polybasic acid is not particularly limited as long as it is a compound or its acid anhydride that does not have an ethylenically unsaturated bond and has two or more carboxy groups, and known compounds can be used. Examples of the saturated polybasic acid include aromatic saturated polybasic acids or their acid anhydrides 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 acid may be used alone or in combination of two or more.

[0035] 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 further 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 becomes even better.

[0036] The degree of unsaturation of the unsaturated polyester resin (A-2) 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 the curable resin composition containing the unsaturated polyester resin (A-2) is improved.

[0037] The degree of unsaturation of the (A-2) unsaturated polyester resin can be calculated from the number of moles of the unsaturated polybasic acid and the 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

[0038] ((A-2) Method for synthesizing unsaturated polyester resin) The (A-2) unsaturated polyester resin can be synthesized by a known method using the above-mentioned raw materials. The various conditions for synthesizing the (A-2) unsaturated polyester resin are appropriately set depending on the raw materials used and their amounts.

[0039] In general, the esterification reaction can be carried out in an inert gas stream such as nitrogen gas at a temperature of 140°C to 230°C under pressure or reduced pressure. In the esterification reaction, an esterification catalyst can be used as necessary. Examples of the esterification catalyst include known catalysts such as manganese acetate, dibutyltin oxide, stannous oxalate, zinc acetate, and cobalt acetate. The esterification catalyst can be used alone or in combination of two or more kinds.

[0040] Incidentally, the unreacted unsaturated polybasic acid remaining after synthesis of the unsaturated polyester resin (A-2) is regarded as an ethylenically unsaturated monomer (B) described below.

[0041] In order to increase the molecular weight by improving the reaction rate and to improve adhesion by reducing the acid value, it is preferable that the equivalent weight of the hydroxyl groups of the polyhydric alcohol is in the range of 0.9 to 1.2 relative to the total amount of carboxyl groups of the unsaturated polybasic acid and any saturated polybasic acid.

[0042] The unreacted unsaturated polybasic acid and any saturated polybasic acid remaining after synthesis of the (A-2) unsaturated polyester resin 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 polyisocyanate with a polyhydric alcohol can be used.

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

[0045] Examples of polyisocyanates include aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate, and trimethylhexane diisocyanate; cyclic aliphatic 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 biuret bodies of these polyisocyanates. The polyisocyanates may be used alone or in combination of two or more.

[0046] When introducing a (meth)acryloyl group, 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. Examples of the hydroxyl group-containing (meth)acrylic compound 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 hydroxyethylacrylamide, and 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, and hydroxyethylacrylamide are preferred. The isocyanato group-containing (meth)acrylic compound and the hydroxyl group-containing (meth)acrylic compound may each be used alone or in combination of two or more.

[0047] In addition, any unreacted hydroxyl group-containing (meth)acrylic compound or unreacted isocyanato group-containing (meth)acrylic compound remaining after synthesis of the (A-3) urethane (meth)acrylate resin is considered to be the (B) ethylenically unsaturated monomer described below.

[0048] <(A-4) Diallyl phthalate resin> The (A-4) diallyl phthalate resin is an oligomer obtained by esterification reaction of diallyl phthalate with a polyhydric alcohol, and a conventionally known one can be used without any particular limitation. The (A-4) diallyl phthalate resin can be used alone or in combination of two or more kinds.

[0049] Incidentally, after synthesis of the (A-4) diallyl phthalate resin, unreacted diallyl phthalate may be present in the curable resin composition without being removed.

[0050] <(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 resin may be used alone or in combination of two or more kinds.

[0051] [(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.

[0052] The (B) ethylenically unsaturated monomer contains at least an aromatic vinyl compound from the viewpoint of ensuring adhesion as a cured product of the curable resin composition. The aromatic vinyl compound contains at least an aromatic divinyl compound having two vinyl groups from the viewpoint of obtaining a cured product with good appearance.

[0053] 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.(A) From the viewpoint of copolymerization with the ethylenically unsaturated group of the curable resin, styrene, vinyltoluene, ethylvinylbenzene, and t-butylstyrene are preferred.

[0054] The aromatic divinyl compound is not particularly limited as long as it is a compound having an aromatic ring skeleton and two vinyl groups.Specific examples of the aromatic divinyl compound include divinylbenzene, divinylnaphthalene, divinylanthracene, and divinylbiphenyl.In view of obtaining a cured product with excellent appearance, divinylbenzene is preferred.

[0055] The aromatic vinyl compound preferably comprises divinylbenzene and at least one selected from ethylvinylbenzene and styrene.

[0056] The (B) ethylenically unsaturated monomer may contain a compound other than the aromatic vinyl compound. Specifically, 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, phenoxyethyl (meth)acrylate ...methyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate )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, trimethylolpropane tri(meth)acrylate, and other (meth)acrylates.

[0057] 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, relative to 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 to an appropriate range, and the moldability is good. 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.

[0058] The proportion of the aromatic vinyl compound contained in the (B) ethylenically unsaturated monomer is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more. When the proportion of the aromatic vinyl compound is 70 mol% or more, the adhesive strength of the cured product of the curable resin composition is good. The proportion of the aromatic vinyl compound contained in the (B) ethylenically unsaturated monomer can be 100 mol% or less, 98 mol% or less, or 95 mol% or less.

[0059] The proportion of the aromatic divinyl compound contained in the (B) ethylenically unsaturated monomer is preferably 5 to 50 mol%, more preferably 7 to 35 mol%, and even more preferably 8 to 30 mol%. When the proportion of the aromatic divinyl compound is 5 mol% or more, a cured product with excellent appearance can be molded. When the proportion of the aromatic divinyl compound is 50 mol% or less, the handleability of the curable resin composition, such as storage stability, can be improved.

[0060] The ratio of the total amount of vinyl groups in the aromatic vinyl compound to the total amount of ethylenically unsaturated groups in the (A) curable resin and the (B) ethylenically unsaturated monomer is 60-95 mol%, and more preferably 65-90 mol%. When the ratio of the total amount of vinyl groups is 60 mol% or more, a sufficient amount of aromatic vinyl compound is contained, so that the adhesive strength of the cured material to the substrate is good. When the ratio of the total amount of vinyl groups is 95 mol% or less, it is advantageous from the viewpoint of environmental resistance.

[0061] [(C) Inorganic filler] As the inorganic filler (C), a particulate material known in the technical field of the present invention can be used. By using the inorganic filler (C), it is possible to reduce the molding shrinkage rate of the molded product, adjust the viscosity of the curable resin composition to improve the workability, or improve the strength of the molded product.

[0062] Examples of the (C) inorganic filler 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, glass powder, etc. Calcium carbonate, aluminum oxide, and aluminum hydroxide are preferable because they are inexpensive. The (C) inorganic filler may be used alone or in combination of two or more kinds.

[0063] The average particle size of the (C) inorganic filler is preferably 1 to 100 μm, more preferably 1 to 60 μm, and even more preferably 1 to 50 μm. If the average particle size of the (C) inorganic filler is 1 μm or more, particle aggregation can be suppressed. On the other hand, if the average particle size of the (C) inorganic filler is 100 μm or less, the moldability of the curable resin composition is good.

[0064] In this specification, the term "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 (Microtrack Bell, Inc., FRA).

[0065] The shape of the (C) inorganic filler is not particularly limited, and examples thereof include an approximately spherical shape, an ellipsoidal shape, a scaly shape, and an amorphous shape.

[0066] The amount of the inorganic filler (C) 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 the curable resin (A) and the ethylenically unsaturated monomer (B). If the amount of the inorganic filler (C) is 200 parts by mass or more, the mechanical properties of the cured product are better. If the amount of the inorganic filler (C) is 700 parts by mass or less, the inorganic filler (C) is more uniformly dispersed in the curable resin composition, and a homogeneous molded product can be produced.

[0067] [(D) Thermal polymerization initiator] The (D) thermal polymerization initiator is not particularly limited as long as it is a polymerization initiator that generates radicals by heating, and examples thereof include peroxides such as diacyl peroxides, peroxy esters, hydroperoxides, dialkyl peroxides, ketone peroxides, peroxy ketals, alkyl peresters, and percarbonates.

[0068] Among these peroxides, the preferred thermal polymerization initiators (D) are 1,1-di-t-hexylperoxy-cyclohexane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxyoctoate, 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-butylperoxybenzoate, dicumyl peroxide, and di-t-butyl peroxide. The thermal polymerization initiators (D) may be used alone or in combination of two or more.

[0069] The amount of the (D) thermal polymerization initiator is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 7 parts by mass, relative to 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer. When the amount of the (D) thermal polymerization initiator is 0.1 parts by mass or more, the curing reaction during molding of the curable resin composition proceeds uniformly, and the physical properties and appearance of the cured product become good. When the amount of the (D) thermal polymerization initiator is 20 parts by mass or less, the storage stability of the curable resin composition becomes good, and the handleability is improved.

[0070] [(E) Glass fiber] The (E) glass fiber is not particularly limited as long as it is a fibrous material having an aspect ratio of at least 3. A specific example is chopped strand glass.

[0071] The fiber length of the (E) 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 (E) glass fiber is preferably 3 to 100 μm, and more preferably 5 to 30 μm.

[0072] The content of the (E) 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, relative to 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer. If the content of the (E) glass fiber is 10 parts by mass or more, the mechanical properties of the molded article obtained from the curable resin composition are better. If the content of the (E) glass fiber is 300 parts by mass or less, the (E) glass fiber is more uniformly dispersed in the curable resin composition, and a homogeneous molded article can be produced.

[0073] [(F) Low shrinkage agent] The (F) shrinkage reducing agent is not particularly limited, and any agent known in the technical field of the present invention can be used. The (F) shrinkage reducing agent is preferably a thermoplastic resin. Examples of the (F) shrinkage reducing agent include polystyrene, polyethylene, polymethyl methacrylate, polyvinyl acetate, saturated polyester, polycaprolactone, and styrene-butadiene rubber. The (F) shrinkage reducing agent may be used alone or in combination of two or more.

[0074] The content of the (F) low shrinkage agent is preferably 10 to 80 parts by mass, more preferably 15 to 50 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) low shrinkage agent is 10 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 (F) low shrinkage agent is 80 parts by mass or less, the mechanical properties of the cured product are better.

[0075] [(G) Acidic surfactant] The curable resin composition may further contain (G) an acidic surfactant, if necessary. The (G) acidic surfactant is a low-volatile substance having a surface activity and an acid value, and is not particularly limited as long as it is a compound having excellent compatibility with (A) the curable resin and (B) the ethylenically unsaturated monomer, and excellent dispersibility of (C) the inorganic filler and (E) the glass fiber. When a compound corresponds to both a saturated polybasic acid and (G) an acidic surfactant, the compound is classified as (G) an acidic surfactant.

[0076] In the present disclosure, a low-volatile substance is a substance that has a weight retention rate of 90% or more under conditions of air at 150°C for 60 minutes. 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.

[0077] As the (G) acidic surfactant, those generally known as dispersants or plasticizers for resin compositions can be suitably used. Low-volatile oligomers are preferred, low-volatile oligomers having components including monomer units such as ethylene units, styrene units, ester units, ether units, and urethane units, and acid groups such as carboxy groups, sulfo groups, and phospho groups are more preferred, phosphoric acid ester compounds or carboxylate compounds are even more preferred, and phosphoric acid ester compounds including long-chain polyester structures are even more preferred.

[0078] 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 it is considered important for the curable resin composition to have an acid value for this purpose. By using an acidic surfactant (G) having an acid value, the adhesion of the cured product is improved. In addition, when the curable resin composition is heated and cured, in order to prevent the adhesion of the cured product from being affected by the volatilization or bleed-out of the acidic surfactant (G), a low-volatility acidic surfactant (G) is used.

[0079] As the phosphoric acid ester compound, those described in JP-A-61-194091, JP-A-3-112992, JP-T-2007-527896, JP-T-2014-520127, etc. can be suitably used. Specific examples include a phosphoric acid triester compound of a methyl ester of 12-hydroxystearic acid polyester, polyethylene glycol monomethyl ether, and an ester compound of an ester compound of malic acid with tetraphosphoric acid.

[0080] As the (G) acidic surfactant, commercially available products can be used, for example, products manufactured by BYK Additives & Instruments under the following product names: BYK W-9010, BYK W-9011, BYK P-9051, BYK P-9050, BYK P-9060, BYK P-9065, BYK P-9080, BYK P-9085, etc. From the viewpoint of adhesion of the cured product, BYK W-9010 and BYK P-9051 are preferred.

[0081] 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 acid value of the curable resin composition can be ensured while keeping the blending amount of the (G) acidic surfactant within an appropriate range, and there is no adverse effect on the properties of the cured product, such as adhesion.

[0082] The content of the (G) acidic surfactant is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 18 parts by mass, and even more preferably 1 to 15 parts by mass, based on 100 parts by mass of the total of the (A) curable resin and the (B) ethylenically unsaturated monomer. When the content of the (G) acidic surfactant is 0.1 parts by mass or more, the curable resin composition has a sufficient acid value, and a cured product having good adhesion can be obtained. When the content of the (G) acidic surfactant is 20 parts by mass or less, there is no adverse effect on the properties of the cured product.

[0083] [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 release agents, within the scope that does not impair the effects of the present invention.

[0084] The thickener is a compound other than the (C) 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 amount of the thickener added may be appropriately adjusted according to the handling property, flowability, etc. required for the curable resin composition.

[0085] The colorant is used when coloring the cured product. As the colorant, various dyes, inorganic pigments, or organic pigments can be used. The colorant may be used alone or in combination of two or more. The amount of the colorant added can be appropriately adjusted depending on the degree of coloration desired for the cured product.

[0086] Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, p-benzoquinone, naphthoquinone, t-butylhydroquinone, catechol, pt-butylcatechol, and 2,6-di-t-butyl-4-methylphenol. The polymerization inhibitor may be used alone or in combination of two or more. The amount of the polymerization inhibitor added may be appropriately adjusted depending on the storage environment and period of the curable resin composition, the curing conditions, and the like.

[0087] 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) an inorganic filler, (D) a thermal polymerization initiator, (E) glass fiber, (F) a low shrinkage agent, and, as necessary, optional components, such as (G) an acidic surfactant, other additives other than the (G) acidic surfactant, or a combination of two or more of these optional components.

[0088] An example of the mixing method is kneading. The kneading method is not particularly limited, and examples thereof include kneading using a kneader, a disperser, a planetary mixer, etc. The kneading temperature is preferably 5°C to 50°C, and more preferably 10°C to 40°C.

[0089] There is no particular restriction on the order of mixing each component when producing a curable resin composition. For example, it is preferable to mix (A) the curable resin and part or all of (B) the ethylenically unsaturated monomer and then mix other components, since it is easy to obtain a curable resin composition in which each component is sufficiently dispersed or uniformly mixed. At least a part of (B) the ethylenically unsaturated monomer may be mixed in advance with (A) the curable resin so as to act as a solvent, dispersion medium, etc.

[0090] An example of a method for mixing the (E) glass fibers is to prepare glass fibers having a predetermined fiber length distribution in advance, and mix the (E) glass fibers with a composition containing each component other than the (E) glass fibers. This method allows fine adjustment of the fiber length distribution of the (E) glass fibers. Another example is to prepare a curable resin composition containing the (E) glass fibers, and then break the (E) glass fibers by kneading to achieve a predetermined fiber length distribution. The fiber length distribution of the (E) 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. This method does not require breaking the (E) glass fibers in advance, and therefore the process is simple.

[0091] 3. Manufacturing method of the 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 120 to 160°C, and a curing time of 1 to 30 minutes.

[0092] 4. Manufacturing method of 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 method is not particularly limited, and methods commonly used in the technical field of the present invention, such as compression molding, transfer molding, injection molding, etc., can be used.

[0093] For example, there is a method in which a mold is opened, a curable resin composition is poured into the mold, and cured, and a method in which a curable resin composition is poured into a closed mold through a hole provided in the mold such as a sprue while the mold is under reduced pressure or under pressure from the outside of the mold as typified by injection molding, and cured. The conditions for curing the curable resin composition in the mold can be appropriately set depending on the material used, and an example of a preferred condition is a temperature of 120 to 180°C, more preferably 120°C to 160°C, and a curing time of 1 to 30 minutes.

[0094] 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 curing the curable resin composition by heating. The encapsulation of the components of the electric / electronic component can be carried out, for example, by injecting the curable resin composition into a housing having the components therein.

[0095] From the viewpoint of adhesion, the curable resin composition is preferably used for polyphenylene sulfide (PPS) substrates, polybutylene terephthalate (PBT) substrates, epoxy glass substrates, and copper substrates. The curable resin composition can obtain excellent adhesion, particularly for poorly adhesive resin substrates such as PPS substrates. By using the curable resin composition, it is possible to omit a surface treatment step using a primer, plasma, or the like, which is generally performed for poorly adhesive resin substrates such as PPS substrates. EXAMPLES

[0096] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0097] An example of the synthesis of the curable resin (A) is shown below.

[0098] [Synthesis Example 1] (A-1) Synthesis of vinyl ester resin In a 1L four-neck flask equipped with a thermometer, a stirrer, a gas inlet, and a reflux condenser, 478.9g of bisphenol A type epoxy resin Araldite (registered trademark) AER-2603 (Asahi Kasei E-Materials Corporation) with an epoxy equivalent of 188.0 and 73.1g of methacrylic acid in which 0.35g of methyl hydroquinone was dissolved were charged and heated with stirring. When the temperature reached 100 to 110°C, 146.2g of methacrylic acid in which 1.4g of 2,4,6-tris(dimethylaminomethyl)phenol (Seikuol (registered trademark) TDMP, Seiko Chemical Co., Ltd.) was dissolved was dropped over 30 minutes and reacted at 130°C. When the acid value reached 30mgKOH / g or less, the mixture was cooled, and 150g of styrene and 0.1g of hydroquinone were added to synthesize a bisphenol A type vinyl ester resin containing 25% by mass of styrene and 2% by mass of unreacted methacrylic acid.

[0099] The other components used were as follows:

[0100] (B) Ethylenically unsaturated monomers: Styrene (Idemitsu Kosan Co., Ltd.) DVB-570 (mixture of 57% divinylbenzene and 43% ethylvinylbenzene, Nippon Steel Chemical & Material Co., Ltd.) EGDMA: Ethylene glycol dimethacrylate (Hitachi Chemical Co., Ltd.)

[0101] (C) Inorganic filler: Softon 1200 (calcium carbonate, average particle size 1.80 μm, Bihoku Powder Industry Co., Ltd.)

[0102] (D) Thermal polymerization initiator: Luperox 575 (t-amylperoxy-2-ethylhexanoate, Arkema Yoshitomi Co., Ltd.)

[0103] (E) Glass fiber: ECS-03B173 / P9 (fiber diameter 13μm, fiber length 3mm, Nippon Electric Glass Co., Ltd.)

[0104] (F) Low shrinkage agent: ·Polyethylene powder (Takehara Chemical Industry Co., Ltd.)

[0105] (G) Acidic surfactants: BYK P-9051 (polyester dispersant, acid value 157mgKOH / g, BYK)

[0106] <Example 1> (Preparation of Curable Resin Composition) (A) 64.3 parts by mass of the styrene-diluted bisphenol A vinyl ester resin synthesized in Synthesis Example 1 as a curable resin (containing 47 parts by mass of bisphenol A vinyl ester resin, 16 parts by mass of styrene, and 1.3 parts by mass of unreacted methacrylic acid) (B) 20 parts by mass of DVB-570 as an ethylenically unsaturated monomer (11.4 parts by mass of divinylbenzene, 8.6 parts by mass of ethylvinylbenzene) (C) 480 parts by mass of Softon 1200 as an inorganic filler, (D) 4 parts by mass of Luperox 575 as a thermal polymerization initiator, (E) 70 parts by mass of ECS-03B173 / P9 as a glass fiber, (F) 30 parts by mass of polyethylene powder as a low shrinkage agent, and (G) 10 parts by mass of BYK P-9051 as an acidic surfactant were added to a twin-arm kneader and kneaded at 30 ° C. for 30 minutes to prepare a curable resin composition.

[0107] (Preparation of cured product) The prepared curable resin composition was used in 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 conditions of 100 s and a curing time of 180 s, yielding a molded product (cured product) in the shape of a pudding cup (diameter on the substrate side: 5 mm, height: 3 mm) on a PPS (polyphenylene sulfide) substrate.

[0108] (Evaluation of adhesion of cured product to substrate) A lateral load was applied to the obtained molded product at a constant speed of 2 mm / min using a die shear tester (Daisy Co., Ltd.), and the strength at the time of shear failure was measured five times at 25°C, and the average value was taken as the adhesion strength. The results are shown in Table 1.

[0109] (Evaluation of molding shrinkage of cured product) In accordance with JIS K 6911:2006 "5.7 Molding shrinkage and heat shrinkage (molding materials)", a shrink disk (φ90mm×11mm) was compression molded (compression molding machine, Technomarushi Co., Ltd.) under the conditions of molding temperature 140℃, molding pressure 5MPa, molding time 3 minutes, and the molding shrinkage was calculated. The results are shown in Table 1.

[0110] (Appearance evaluation of molded products) The shrink disk molded product was evaluated based on the number of spots caused by cracks that appeared on the surface. The evaluation criteria are as follows. The results are shown in Table 1. 10 points: No spots 9 points: 3 or fewer spots 8 points: 4 to 8 spots 7 points: 9-11 spots 6 points: 12 to 14 spots 5 points: 15-17 spots 4 points: 18-20 spots 3 points: 21-23 spots 2 points: 24 to 26 spots 1 point: 27-29 spots 0 points: 30 or more spots

[0111] (Injection moldability evaluation) A molded product of the same shape as the shrink disk molded above was made under the same conditions using an injection molding machine, and the injection moldability was evaluated. If the product was good and there were no problems, it was rated as good, but if it could not be molded due to insufficient filling, etc., it was rated as bad. The results are shown in Table 1.

[0112] <Examples 2 to 4 and Comparative Examples 1 to 6> Curable resin compositions were prepared in the same manner as in Example 1, except that the types and compositions of raw materials were changed as shown in Table 1. The amount of styrene used to dilute the curable resin (A) was excluded from the amount of component (A) and was added to the amount of the ethylenically unsaturated monomer (B) that was listed. Next, cured products were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 1.

[0113] [Table 1]

[0114] The results shown in Table 1 indicate that the molded articles of Examples 1 to 4 and Comparative Examples 4 to 6 have high adhesion to the PPS substrate. It is believed that by adjusting the ratio of the total amount of vinyl groups in the aromatic vinyl compound to the total amount of ethylenically unsaturated groups in (A) the curable resin and (B) the ethylenically unsaturated monomer within a predetermined range, the wettability to the substrate is improved, and high adhesion is obtained.

[0115] On the other hand, Comparative Examples 1 to 3, which had a low ratio of the total amount of vinyl groups in the aromatic vinyl compound, had low adhesion. This is believed to be because the crosslinked structure was not suitable for adhesion, and the effect of improving wettability to the substrate was insufficient, resulting in no adhesion.

[0116] The molded articles of Examples 1 to 4, which contained divinylbenzene, also had good appearances. It is believed that cracking was suppressed by improving the crosslink density of the cured product.

[0117] On the other hand, Comparative Examples 4 to 6, which had high adhesion to the PPS substrate but did not contain divinylbenzene, had molded articles with inferior appearances compared to Examples 1 to 4. The frequent occurrence of cracks is believed to be due to insufficient crosslink density in the cured product.

[0118] The compositions of Examples 1 to 4 are suitable for use as BMC (bulk molding compound), and it was possible to provide curable resin compositions that are excellent in injection moldability and have a small molding shrinkage rate. [Industrial Applicability]

[0119] According to the present invention, there is provided a curable resin composition which can give a cured product having excellent adhesion to a substrate, particularly a poorly adhesive resin substrate, and a good appearance. Also provided is an electric / electronic component having such a cured product as an encapsulant, and a method for producing the same. The curable resin composition is preferably used for encapsulation and fixing of 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 mounted on automobiles.

Claims

1. (A) Curable resin, (B) an ethylenically unsaturated monomer, (C) inorganic filler, (D) a thermal polymerization initiator, (E) glass fibers, and (F) Low shrinkage agent A curable resin composition comprising: The (A) curable resin contains at least a vinyl ester resin, The (B) ethylenically unsaturated monomer contains at least an aromatic vinyl compound, The aromatic vinyl compound contains at least an aromatic divinyl compound, a ratio of a total amount of vinyl groups contained in the aromatic vinyl compound to a total amount of ethylenically unsaturated groups contained in the (A) curable resin and the (B) ethylenically unsaturated monomer is 60 to 95 mol %; An encapsulant which is a cured product of a curable resin composition.

2. 2. An encapsulant which is a cured product of the curable resin composition according to claim 1, wherein the ratio of the aromatic divinyl compound contained in the ethylenically unsaturated monomer (B) is 5 to 50 mol %.

3. 3. An encapsulant which is a cured product of the curable resin composition according to claim 1, wherein the ratio of the aromatic vinyl compound contained in the ethylenically unsaturated monomer (B) is 70 mol % or more.

4. An encapsulant which is a cured product of the curable resin composition according to any one of claims 1 to 3, wherein the aromatic divinyl compound is divinylbenzene.

5. The aromatic vinyl compound is composed of at least one selected from divinylbenzene, ethylvinylbenzene, and styrene.

6. For a total of 100 parts by mass of the curable resin (A) and the ethylenically unsaturated monomer (B), (A) 5 to 95 parts by mass of a curable resin, (B) 5 to 95 parts by mass of an ethylenically unsaturated monomer, (C) 200 to 700 parts by mass of an inorganic filler, (D) 0.1 to 20 parts by mass of a thermal polymerization initiator, (E) 10 to 300 parts by mass of glass fibers, and (F) 10 to 80 parts by mass of a low shrinkage agent An encapsulant comprising the cured product of the curable resin composition according to any one of claims 1 to 5.

7. An encapsulant which is a cured product of 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 an encapsulant which is a cured product of the curable resin composition according to any one of claims 1 to 7.

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

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