Resin composition, composite material, and method for producing same

Abstract

[Problem] To provide a resin composition that can be cured at a low temperature in a short time, and a composite material that contains the resin composition and a fiber base material. [Solution] Specifically disclosed is a resin composition containing a vinyl ester resin (A), an ethylenically-unsaturated-group-containing monomer (B), a metal-containing compound (C), an organic peroxide (D), and a mercapto-group-containing compound (E). The metal-containing compound (C) is a compound that contains a group 7-11 metal element. The metal-equivalent content of the metal-containing compound (C) is 0.1 × 10−6 to 2000 × 10−6 parts by mass per 100 total parts by mass of the vinyl ester resin (A) and the ethylenically-unsaturated-group-containing monomer (B).

Description

Resin composition, composite material, and method for producing the same

[0001] The present invention relates to a vinyl ester resin composition, a composite material containing the resin composition, and a cured product thereof.

[0002] Fiber-reinforced plastics, a type of fiber-reinforced composite material, are lightweight, strong, and rigid, and are therefore used in a wide range of fields, including aviation, space, automobiles, railway vehicles, ships, civil engineering and construction, sports, and leisure.

[0003] One method for producing fiber-reinforced plastics is to use an intermediate material, i.e., a prepreg, in which a reinforcing material made of long fibers (continuous fibers) such as reinforcing fibers is impregnated with a matrix resin. This method has the advantage that the reinforcing fiber content of the resulting fiber-reinforced plastic can be easily controlled and can be designed to be higher. A fiber-reinforced plastic molded product can be obtained by stacking multiple sheets of this prepreg and heat-curing them.

[0004] Specific methods for obtaining fiber-reinforced plastics using prepregs include, for example, molding using an autoclave, press molding, internal pressure molding, oven molding, etc. In any of these methods, two or more prepregs are usually laminated, shaped into the desired shape, and then heat-cured, which requires approximately 2 to 6 hours at a temperature of approximately 160°C or higher until curing. In other words, high-temperature and long-term processing is required to produce fiber-reinforced plastics.

[0005] Therefore, in order to improve the molding cycle, it is required that molding can be performed at a relatively low temperature in a short time of several minutes to several tens of minutes.

[0006] As the matrix resin used in prepregs, epoxy resin compositions are widely used because of their excellent mechanical properties, heat resistance, and ease of handling. However, curing of epoxy resin compositions generally requires high temperatures and a long time.

[0007] Patent Document 1 discloses an epoxy resin composition and prepreg that can be cured completely in a short time even at low temperatures to give a fiber-reinforced plastic that is excellent in mechanical properties such as flexural strength, flexural modulus, and breaking strain, as well as in heat resistance. The epoxy resin composition has a flexural strength of 155 MPa or more and a flexural modulus of 3.3 GPa or more when heat-cured at 140°C for 30 minutes.

[0008] Japanese Patent Application Laid-Open No. 2021-116349

[0009] High-temperature, long-term treatment consumes a large amount of heat and requires time for curing the resin composition and for cooling and allowing it to cool, which has led to the problem that production efficiency is not necessarily good.

[0010] In recent years, there has been a growing demand for energy conservation and an improvement in the production cycle.

[0011] However, currently, epoxy resin compositions generally used to obtain fiber-reinforced plastics require long-term heating at high temperatures to obtain a cured product, and no compositions have been proposed that can be cured at relatively low temperatures of about 40 to 130°C in a period of several minutes to several tens of minutes.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition that can be cured at a low temperature in a short time, and a composite material containing the resin composition and a fiber substrate.

[0013] That is, the present invention relates to the following [1] to

[14] : [1] A resin composition containing a vinyl ester resin (A), an unsaturated group-containing monomer (B), a metal-containing compound (C), an organic peroxide (D), and a mercapto group-containing compound (E), wherein the metal-containing compound (C) is a compound containing a metal element of Groups 7 to 11, and the metal-equivalent content of the metal-containing compound (C) is 0.1 × 10 relative to 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B). -6 ~2000 x 10 -6parts by mass. [2] The resin composition according to claim 1, wherein the metal element contained in the metal-containing compound (C) is at least one selected from iron, nickel, cobalt, manganese, and copper. [3] The resin composition according to [2], wherein the metal-containing compound (C) is at least one carboxylate selected from iron, nickel, cobalt, manganese, and copper, or at least one β-diketone complex selected from iron, nickel, cobalt, manganese, and copper. [4] The resin composition according to [3], wherein the metal-containing compound (C) comprises at least one selected from copper naphthenate, copper bis(2,4-pentanedionato), nickel(II) bis(2,4-pentanedionato)hydrate, cobalt octoate, manganese octoate, and iron naphthenate. [5] The resin composition of any one of [1] to [4], comprising 40 to 95 parts by mass of the vinyl ester resin (A), 5 to 60 parts by mass of the ethylenically unsaturated group-containing monomer (B), and 0.5 to 4 parts by mass of an organic peroxide (D), relative to a total of 100 parts by mass of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B). [6] The resin composition of any one of [1] to [5], wherein the vinyl ester resin (A) is a reaction product of an epoxy compound (a-1) having two or more epoxy groups per molecule and an unsaturated monobasic acid (a-2), and the total number of acid groups in the unsaturated monobasic acid (a-2) is 80 to 105 moles relative to 100 moles of the total number of epoxy groups in the epoxy compound (a-1). [7] The resin composition of claim [6], wherein the epoxy compound (a-1) is a bisphenol-type epoxy resin. [8] The resin composition of [6], wherein the unsaturated monobasic acid (a-2) is at least one selected from (meth)acrylic acid and crotonic acid. [9] The resin compositions of [1] to [8], wherein the organic peroxide (D) is a peroxyester-based organic peroxide, a hydroperoxide-based organic peroxide, a dialkyl peroxide-based organic peroxide, or a peroxyketal-based organic peroxide.

[10] The resin compositions of [1] to [9], wherein the mercapto group-containing compound (E) is a polyfunctional thiol.

[11] A composite material comprising the resin composition of [1] to

[10] and a fibrous base material (G).

[12] The composite material of

[11] , wherein the fibrous base material (G) is at least one selected from carbon fiber and glass fiber.

[13] A method for producing a molded product, comprising the steps of molding and curing the composite material of

[11] or

[12] by one or more methods selected from hand layup molding, pultrusion molding, and press molding.

[14] A cured product of the composite material of

[11] or

[12] .

[0014] The resin composition of the present invention and a composite material containing the resin composition and a fiber substrate can be cured efficiently at low temperature in a short time, and therefore can be molded using a molding method that requires a high production cycle.

[0015] The present embodiment will be described in detail below, but the present embodiment is not limited to the following embodiment.

[0016] In this specification, when "to" is used to describe a numerical range, the numerical values ​​at both ends are the upper and lower limits, respectively, and are included in the numerical range. When multiple upper or lower limits are listed, numerical ranges can be created using all combinations of the upper and lower limits. Similarly, when multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining the upper and lower limits from those numerical ranges.

[0017] In this specification, "(meth)acrylic acid" means methacrylic acid or acrylic acid, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyloxy" means acryloyloxy or methacryloyloxy. [Resin Composition] The resin composition of this embodiment contains a vinyl ester resin (A), an ethylenically unsaturated group-containing monomer (B), a metal-containing compound (C), an organic peroxide (D), and a mercapto group-containing compound (E). In addition to these, the resin composition may contain other components described below. From the viewpoint of obtaining the effects of the present invention favorably, the total content of the vinyl ester resin (A), the ethylenically unsaturated group-containing monomer (B), the metal-containing compound (C), the organic peroxide (D), and the mercapto group-containing compound (E) in the resin composition is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass. [Vinyl ester resin (A)] The vinyl ester resin (A) is a reaction product of an epoxy compound (a-1) having two or more epoxy groups per molecule and an unsaturated monobasic acid (a-2). Generally, the vinyl ester resin (A) is a compound having a polymerizable unsaturated bond obtained by a ring-opening reaction between the epoxy group in the epoxy compound (a-1) and the carboxy group of the unsaturated monobasic acid (a-2). (Epoxy compound (a-1)) The epoxy compound (a-1) is a compound having two or more epoxy groups per molecule, and a monomer, oligomer, or polymer may be used in general, with no particular limitations on its molecular weight or molecular structure. The epoxy compound (a-1) may be used alone or in combination of two or more.

[0018] Examples of the epoxy compound (a-1) include biphenyl-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, tetrabromobisphenol A-type epoxy resins, and tetramethylbisphenol F-type epoxy resins; stilbene-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; polyfunctional epoxy resins such as triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-type epoxy resins; phenol aralkyl-type epoxy resins such as phenol aralkyl-type epoxy resins having a phenylene skeleton and phenol aralkyl-type epoxy resins having a biphenylene skeleton; dihydroxy naphthol-type epoxy resins such as sinaphthalene-type epoxy resins and epoxy resins obtained by glycidyl etherifying a dimer of dihydroxynaphthalene; triazine nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; alicyclic polyepoxy compounds such as alicyclic diepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxy carboxylate and vinylcyclohexene dioxide; bridged cyclic hydrocarbon compound-modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins; glycidyl ester-type epoxy resins obtained by reacting a polybasic acid such as dimer acid with epichlorohydrin; and oxazolidone ring-containing epoxy resins obtained by reacting the above-mentioned epoxy resins with diisocyanates.

[0019] Among these, from the viewpoints of toughness imparting, versatility, and cost, bisphenol type epoxy resins are preferred, and one or more selected from bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, and bisphenol AF type epoxy resins are more preferred, and from the viewpoint of a good balance between toughness and strength as a fiber-reinforced plastic, bisphenol A type epoxy resins are even more preferred. The bisphenol structure makes it possible to extend the molecular weight of the epoxy compound.

[0020] The epoxy equivalent of the epoxy compound (a-1) is preferably 170 to 1,000, more preferably 170 to 500, even more preferably 170 to 400, and even more preferably 170 to 300, from the viewpoint of workability and so that the epoxy compound (a-1) can be obtained without gelling the vinyl ester resin (A). From the viewpoint of workability, the epoxy compound (a-1) is preferably liquid at 25°C, and more preferably has an epoxy equivalent of 300 or less. (Unsaturated Monobasic Acid (a-2)) The unsaturated monobasic acid (a-2) is preferably a monocarboxylic acid having an ethylenically unsaturated group, and one type may be used alone, or two or more types may be used in combination.

[0021] Examples of the unsaturated monobasic acid (a-2) include (meth)acrylic acid, crotonic acid, cinnamic acid, etc. Among these, from the viewpoint of obtaining a resin composition having versatility, reactivity during synthesis of the vinyl ester resin (A), and good curability, at least one selected from (meth)acrylic acid and crotonic acid is preferred, from the viewpoint of workability, (meth)acrylic acid, which is liquid at room temperature, is more preferred, and from the viewpoint of chemical resistance, methacrylic acid is even more preferred.

[0022] Furthermore, the unsaturated monobasic acid (a-2) may be a half ester of a compound having one hydroxy group and one or more (meth)acryloyl groups with a dibasic acid or a dibasic acid anhydride. Examples of acrylic monomers having one hydroxy group and one or more (meth)acryloyl groups include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and polyethylene glycol monomethyl ether (meth)acrylate. Among these, compounds having a hydroxy group and an acryloyl group are preferred from the viewpoint of mechanical properties (elongation at break).

[0023] Known dibasic acids and dibasic acid anhydrides can be used, including, for example, succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, fumaric acid, maleic acid, itaconic acid, tetrahydrophthalic acid, hexahydrophthalic acid, dimer acid, ethylene glycol-2 moles of maleic anhydride adduct, polyethylene glycol-2 moles of maleic anhydride adduct, propylene glycol-2 moles of maleic anhydride adduct, polypropylene glycol-2 moles of maleic anhydride adduct, dodecanedioic acid, tridecanedioic acid, octadecanedioic acid, 1,16-(6-ethylhexadecane)dicarboxylic acid, 1,12-(6-ethyldodecane)dicarboxylic acid, and butadiene-acrylonitrile copolymer having carboxy groups at both ends (trade name: Hycar CTBN).

[0024] In the present invention, a half ester of 2-hydroxyethyl (meth)acrylate and succinic acid is preferred.

[0025] The amount of the unsaturated monobasic acid (a-2) is preferably such that the total amount of acid groups in the unsaturated monobasic acid (a-2) is 80 to 105 moles, more preferably 85 to 103 moles, and even more preferably 90 to 100 moles, relative to 100 moles of the total amount of epoxy groups in the epoxy compound (a-1).

[0026] If the total amount of acid groups in the unsaturated monobasic acid (a-2) is 80 moles or more relative to 100 moles of the total amount of epoxy groups in the epoxy compound (a-1), a sufficient amount of ethylenically unsaturated groups is introduced into the vinyl ester resin (A), and the resin composition is likely to exhibit good curability. Also, if the total amount of acid groups in the unsaturated monobasic acid (a-2) is 105 moles or less, the amount of unreacted unsaturated monobasic acid remaining in the vinyl ester resin (A) can be reduced.

[0027] From the viewpoint of workability, the weight average molecular weight Mw of the vinyl ester resin (A) is preferably 400 or more, more preferably 500 or more, and even more preferably 600 or more. From the viewpoint of impregnation into the fibrous base material (G), the weight average molecular weight Mw is preferably 6,000 or less, more preferably 4,000 or less, and even more preferably 3,000 or less.

[0028] From the viewpoint of workability, the number average molecular weight Mn of the vinyl ester resin (A) is preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more. From the viewpoint of impregnation into the fibrous base material (G), the number average molecular weight Mn is preferably 3,000 or less, more preferably 2,000 or less, and even more preferably 1,000 or less.

[0029] Mw / Mn is an index of molecular weight distribution, and when it is 1, it represents a monodisperse polymer, and the larger this ratio is, the wider the molecular weight distribution is.

[0030] The Mw / Mn of the vinyl ester resin (A) is preferably 1.0 or more, more preferably 1.1 or more, and even more preferably 1.2 or more from the viewpoint of ease of control of synthesis conditions, and is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less from the viewpoint of suppressing variation in the physical properties of the resin composition.

[0031] From the viewpoint of the storage stability of the resin, the acid value of the vinyl ester resin (A) is preferably 0 KOHmg / g or more, more preferably 0.1 KOHmg / g or more, and even more preferably 1.0 KOHmg / g or more. From the viewpoint of the reactivity during curing of the resin composition and the color stability of the cured product, the acid value is preferably 25 KOHmg / g or less, more preferably 20 KOHmg / g or less, and even more preferably 16 KOHmg / g or less. That is, the acid value of the vinyl ester resin (A1b) is preferably 0 to 25 KOHmg / g, more preferably 0.1 to 20 KOHmg / g, and even more preferably 1.0 to 16 KOHmg / g.

[0032] From the viewpoint of workability, moldability, adjustment of curability, and adjustment of physical properties due to a low viscosity, the vinyl ester resin (A) is preferably used after adjusting its viscosity using a solvent, a reactive diluent, etc. The adjusted viscosity is preferably 0.01 to 1.5 Pa s, more preferably 0.05 to 1.2 Pa s, and even more preferably 0.1 to 1.0 Pa s in a 25°C environment.

[0033] The vinyl ester resin (A) of the present embodiment may be used alone or in combination of two or more kinds.

[0034] The vinyl ester resin (A) may be a commercially available product, or may be produced by the following production method: (Production Method of Vinyl Ester Resin (A)) For example, the vinyl ester resin (A) can be produced by mixing the epoxy compound (a-1) and the unsaturated monobasic acid (a-2) with at least one of a solvent and a reactive diluent, as necessary, in a reaction vessel capable of being heated and stirred, and heating the mixture in the presence of a catalyst at preferably 70 to 150°C, more preferably 80 to 140°C, and even more preferably 90 to 130°C for 1 to 8 hours while mixing.

[0035] Examples of catalysts include tertiary amines such as triethylamine, triethylenediamine, N,N-dimethylbenzylamine, N,N-dimethylaniline, 2,4,6-tris(dimethylaminomethyl)phenol, and diazabicyclooctane; phosphorus compounds such as triphenylphosphine and benzyltriphenylphosphonium chloride; diethylamine hydrochloride; and quaternary ammonium salts such as trimethylbenzylammonium chloride and tetradecyldimethylbenzylammonium chloride. These may be used alone or in combination of two or more. Among these, from the viewpoints of gently accelerating the synthesis reaction rate of the vinyl ester resin, suppressing gelation of the resin, and easily controlling the molecular weight distribution, at least one selected from phosphorus compounds and quaternary ammonium salts is preferred, and at least one selected from quaternary ammonium salts is more preferred.

[0036] The amount of the catalyst used is preferably 0.01 to 3 parts by mass, more preferably 0.03 to 2 parts by mass, and even more preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the epoxy compound (a-1) and the unsaturated monobasic acid (a-2) in total, from the viewpoints of promoting the reaction while suppressing thickening of the vinyl ester resin (A) and ensuring the storage stability of the obtained reaction product.

[0037] The solvent and the reactive diluent are used as needed to facilitate uniform mixing of the epoxy compound (a-1) and the unsaturated monobasic acid (a-2). The mixing method is not particularly limited and can be performed by a known method.

[0038] The solvent is not particularly limited as long as it is inactive to the epoxy compound (a-1) and the unsaturated monobasic acid (a-2). For example, known solvents having a boiling point of 70 to 150°C at 1 atmospheric pressure, such as methyl isobutyl ketone (MIBK), may be used. One solvent may be used alone, or two or more solvents may be used in combination.

[0039] As the reactive diluent, one that is inactive to the epoxy compound (a-1) and the unsaturated monobasic acid (a-2) is used. In this embodiment, however, it is also possible to use an ethylenically unsaturated group-containing monomer (B) described later as the reactive diluent.

[0040] A polymerization inhibitor may be added to inhibit the progress of the polymerization reaction of the vinyl ester resin (A).

[0041] The polymerization inhibitor is preferably one described in the section below under [Other Components]. When a polymerization inhibitor is added, the amount added can be, for example, 0.0001 to 10 parts by mass, preferably 0.001 to 1.0 part by mass, and more preferably 0.01 to 0.3 parts by mass, per 100 parts by mass of the epoxy compound (a-1) and the unsaturated monobasic acid (a-2) combined. [Ethylenically Unsaturated Group-Containing Monomer (B)] The ethylenically unsaturated group-containing monomer (B) is not particularly limited as long as it has an ethylenically unsaturated group, but those having a vinyl group or a (meth)acryloyl group are preferred. The ethylenically unsaturated group-containing monomer (B) contributes to reducing the viscosity of the resin composition and further contributes to the fiber impregnation of the composite material.

[0042] Among the ethylenically unsaturated group-containing monomers (B), those having a vinyl group include, for example, styrene, p-chlorostyrene, vinyltoluene, α-methylstyrene, dichlorostyrene, divinylbenzene, t-butylstyrene, vinyl acetate, diallyl phthalate, triallyl isocyanurate, etc. Further examples include vinylbenzyl compounds such as vinylbenzyl butyl ether, vinylbenzyl hexyl ether, vinylbenzyl octyl ether, and divinylbenzyl ether.

[0043] Among the ethylenically unsaturated group-containing monomers (B), those having a (meth)acryloyl group include, for example, (meth)acrylic acid, (meth)acrylate, etc. The (meth)acrylate may be monofunctional or polyfunctional.

[0044] Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, stearyl (meth)acrylate, tridecyl (meth)acrylate, phenoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ethylene glycol monomethyl ether (meth)acrylate, ethylene glycol monoethyl ether (meth)acrylate, ethylene glycol monobutyl ether (meth)acrylate, and ethylene glycol monohexyl ether (meth)acrylate. , ethylene glycol mono 2-ethylhexyl ether (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate, diethylene glycol monoethyl ether (meth)acrylate, diethylene glycol monobutyl ether (meth)acrylate, diethylene glycol monohexyl ether (meth)acrylate, diethylene glycol mono 2-ethylhexyl ether (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, and allyl (meth)acrylate.

[0045] Examples of polyfunctional (meth)acrylates include alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate. and polyoxyalkylene glycol di(meth)acrylates such as these, as well as trimethylolpropane di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol diacrylate monostearate, 1,3-bis((meth)acryloyloxy)-2-hydroxypropane, ethoxylated bisphenol A di(meth)acrylate, and tris-(2-(meth)acryloxyethyl)isocyanurate.

[0046] Among the ethylenically unsaturated group-containing monomers (B), examples of those having a (meth)acryloyl group other than (meth)acrylate include acryloylmorpholine, 2-hydroxyethyl(meth)acrylamide, 2-hydroxyethyl-N-methyl(meth)acrylamide, and 3-hydroxypropyl(meth)acrylamide.

[0047] These ethylenically unsaturated group-containing monomers (B) may be used alone or in combination of two or more.

[0048] Among these, from the viewpoints of workability and fiber impregnation of composite materials containing the resin composition, at least one selected from styrene, methyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and neopentyl glycol (meth)acrylate is more preferred, and at least one selected from styrene, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, diethylene glycol di(meth)acrylate, and neopentyl glycol (meth)acrylate is more preferred, with styrene being even more preferred. [Metal-Containing Compound (C)] The metal-containing compound (C) is used to promote curing of the resin composition. As the metal compound (C), a compound containing a metal element of Groups 7 to 11 of the Periodic Table is used. The metal-containing compound (C) may be used alone or in combination of two or more kinds.

[0049] Examples of the metal elements include manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, and gold.

[0050] As the metal element, from the viewpoint of a high curing-accelerating effect and curing at a low temperature in a short time, manganese, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, copper, palladium, platinum, silver, and gold are preferred, manganese, iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, and silver are more preferred, from the viewpoints of cost, versatility, and availability, manganese, iron, cobalt, nickel, and copper are even more preferred, and from the viewpoint of fast curing, cobalt, nickel, and copper are even more preferred.

[0051] In this embodiment, the metal-containing compound (C) is preferably a carboxylate of the above metal or a β-diketone complex of the above metal.

[0052] Examples of the carboxylic acid include heptanoic acid, octylic acid, nonanoic acid, decanoic acid, neodecanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, octacosanoic acid, triacontanoic acid, behenic acid, naphthenic acid, oleic acid, linoleic acid, linolenic acid, rosin acid, linseed oil fatty acid, soybean oil fatty acid, tall oil acid, formic acid, acetic acid, citric acid, oxalic acid, and benzoic acid.

[0053] Examples of the β-diketones include 2,4-pentanedione (acetylacetone), 2,2,6,6-tetramethylheptane-3,5-dione, 2,6-dimethyl-3,5-heptanedione, ethyl acetoacetate, α-acetyl-γ-butyrolactone, N-pyrrolidininoacetoacetamide, N,N-dimethylacetoacetamide, 2-isobutyryl-1-cyclohexanone, 6-methyl-2,4-heptanedione, hexafluoroacetylacetone, and 3-methylnonane-2,4-dione.

[0054] From the viewpoint of the effect of accelerating the curing of the resin composition, naphthenic acid, octylic acid, and octenoic acid are preferred as the carboxylic acid, and 2,4-pentanedione is preferred as the β-diketone.

[0055] From the viewpoint of the curing-accelerating effect of the resin composition, the metal-containing compound (C) is preferably copper naphthenate, copper bis(2,4-pentanedionato), bis(2,4-pentanedionato)nickel(II) hydrate, bis(2,4-pentanedionato)nickel(II) dihydrate, bis(2,4-pentanedionato)cobalt(II), bis(2,4-pentanedionato)platinum(II), cobalt octylate, manganese octylate, iron octylate, nickel octylate, iron naphthenate, manganese naphthenate, or cobalt naphthenate, and more preferably copper naphthenate, bis(2,4-pentanedionato)

[0039] Preferred examples of the organic peroxide (D) include copper naphthenate, bis(2,4-pentanedionato)copper, bis(2,4-pentanedionato)nickel(II) hydrate, cobalt octylate, manganese octylate, iron octylate, iron naphthenate, manganese naphthenate, and cobalt naphthenate. More preferred examples include copper naphthenate, bis(2,4-pentanedionato)copper, bis(2,4-pentanedionato)nickel(II) hydrate, cobalt octylate, manganese octylate, and iron naphthenate. From the viewpoint of curability, more preferred examples include copper naphthenate, bis(2,4-pentanedionato)copper, bis(2,4-pentanedionato)nickel(II) hydrate, and cobalt octylate. [Organic Peroxide (D)] The organic peroxide (D) is not particularly limited as long as it is used as a radical curing agent for the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B). From the viewpoint of stability after mixing with the resin, it is preferable to use one having a 10-hour half-life temperature of 60 to 180°C, more preferably 90 to 175°C, and even more preferably 100 to 160°C.

[0056] Examples of the organic peroxide (D) include diacyl peroxides such as benzoyl peroxide, peroxyesters such as t-butyl peroxybenzoate, hydroperoxides such as cumene hydroperoxide, dialkyl peroxides such as dicumyl peroxide, ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide, peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane, alkyl peresters, and percarbonate organic peroxides. Among these, peroxyester organic peroxides, hydroperoxide organic peroxides, dialkyl peroxide organic peroxides, and peroxyketal organic peroxides are preferred from the viewpoint of curability, and peroxyester organic peroxides and hydroperoxide organic peroxides, which have a good synergistic effect with metal-containing compounds, are more preferred.

[0057] Among the above, one or more selected from cumene hydroperoxide, t-butyl peroxybenzoate, 1,1-di(t-butylperoxy)cyclohexane, and benzoyl peroxide are preferred, and among these, cumene hydroperoxide, which has excellent low-temperature curing properties, and t-butyl peroxybenzoate, which has excellent stability after mixing, are more preferred, with cumene hydroperoxide being even more preferred. [Mercapto Group-Containing Compound (E)] The resin composition of this embodiment contains a mercapto group-containing compound (E). By combining the mercapto group-containing compound (E), it is possible to obtain a resin composition that can be cured at low temperatures in a short time.

[0058] The mercapto group-containing compound (E) is preferably a polyfunctional thiol compound, and from the viewpoint of odor, a secondary thiol compound in which a mercapto group is bonded to a secondary carbon atom or a tertiary thiol compound in which a mercapto group is bonded to a tertiary carbon atom is preferred, and a secondary thiol compound is preferred in terms of a good balance between reactivity and storage stability, heat resistance, moisture resistance, water resistance, etc.

[0059] Furthermore, polyfunctional thiol compounds containing two or more mercapto groups in the molecule also function well as curing accelerators.

[0060] The term "polyfunctional thiol" as used herein means a mercapto group-containing compound having two or more mercapto groups as functional groups.

[0061] For this reason, in the present invention, polyfunctional secondary thiol compounds are preferred.

[0062] Examples of the mercapto group-containing compound (E) include monofunctional primary thiol compounds such as 3-mercaptobutyric acid and 1-dodecanethiol; and polyfunctional primary thiol compounds having two or more mercapto groups bonded to a primary carbon atom in the molecule such as pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(3-mercaptopropionate), 1,4-butanediol bis(thioglycolate), and dipentaerythritol hexakis(3-mercaptopropionate).

[0063] Examples of secondary thiol compounds having a mercapto group bonded to a secondary carbon atom in the molecule include monofunctional secondary thiol compounds such as 2-mercaptobutyric acid and 3-mercaptobutanoic acid (manufactured by Resonac Co., Ltd., product name: 3MBA); and examples of polyfunctional secondary thiol compounds having two or more mercapto groups bonded to a secondary carbon atom in the molecule include 1,4-bis(3-mercaptobutyryloxy)butane (manufactured by Resonac Co., Ltd., Karenz MT (registered trademark) BD1), pentaerythritol tetrakis(3-mercaptobutyrate) (manufactured by Resonac Co., Ltd., Karenz MT (registered trademark) PE1), and 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. (manufactured by Resonac Corporation, Karenz MT (registered trademark) NR1), trimethylolethane tris(3-mercaptobutyrate) (manufactured by Resonac Corporation, TEMB), trimethylolpropane tris(3-mercaptobutyrate) (manufactured by Resonac Corporation, TPMB), trimethylolpropane tris(3-mercaptobutyrate), dipentaerythritol hexakis(2-mercaptopropionate), ethylene glycol bis(4-mercaptovalerate), diethylene glycol bisabolate bis(4-mercaptovalerate), butanediol bis(4-mercaptovalerate), octanediol bis(4-mercaptovalerate), trimethylolpropane tris(4-mercaptovalerate), pentaerythritol tetrakis(4-mercaptovalerate), dipentaerythritol hexakis(4-mercaptovalerate), ethylene glycol bis(3-mercaptovalerate), propylene glycol bis(3-mercaptovalerate), diethylene glycol bis bis(3-mercaptovalerate), butanediol bis(3-mercaptovalerate), octanediol bis(3-mercaptovalerate), trimethylolpropane tris(3-mercaptovalerate), pentaerythritol tetrakis(3-mercaptovalerate), dipentaerythritol hexakis(3-mercaptovalerate), hydrogenated bisphenol A bis(3-mercaptobutyrate), bisphenol A dihydroxyethyl ether-3-mercaptobutyrate, 4,4'-(9-fluorenylidene)bis(2-phenoxyethyl(3-mercaptobutyrate)), ethylene glycol bis(3-mercapto-3-phenylpropionate), propylene glycol bis(3-mercapto-3-phenylpropionate), diethylene glycol bis(3-mercapto-3-phenylpropionate), butanediol bis(3-mercapto-3-phenylpropionate), octanediol bis(3-mercapto-3-phenylpropionate), trimethylolpropane tris(3-mercapto-3-phenylpropionate), tris-2-(3-mercapto-3-phenylpropionate)ethyl isocyanurate, pentaerythritol tetrakis(3-mercapto-3-phenylpropionate), dipentaerythritol hexakis(3-mercapto-3-phenylpropionate), and the like.

[0064] Tertiary thiol compounds having a mercapto group bonded to a secondary carbon atom in the molecule include di(2-mercaptoisobutyl) phthalate, ethylene glycol bis(2-mercaptoisobutyrate), propylene glycol bis(2-mercaptoisobutyrate), diethylene glycol bis(2-mercaptoisobutyrate), butanediol bis(2-mercaptoisobutyrate), octanediol bis(2-mercaptoisobutyrate), trimethylolethane tris(2-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), pentaerythritol tetrakis(2-mercaptoisobutyrate), dipentaerythritol hexakis(2-mercaptoisobutyrate), phthalic acid Di(3-mercapto-3-methylbutyl), ethylene glycol bis(3-mercapto-3-methylbutyrate), propylene glycol bis(3-mercapto-3-methylbutyrate), diethylene glycol bis(3-mercapto-3-methylbutyrate), butanediol bis(3-mercapto-3-methylbutyrate), octanediol bis(3-mercapto-3-methylbutyrate), trimethylolethane tris(3-mercapto-3-methylbutyrate), trimethylolpropane tris(3-mercapto-3-methylbutyrate), pentaerythritol tetrakis(3-mercapto-3-methylbutyrate), dipentaerythritol hexakis(3-mercapto-3-methylbutyrate), and the like.

[0065] Among these mercapto group-containing compounds (E), trimethylolpropane tris(3-mercaptobutyrate) and pentaerythritol tetrakis(3-mercaptobutyrate) are preferred, and pentaerythritol tetrakis(3-mercaptobutyrate) is more preferred. [Other Components] The resin composition of this embodiment may contain other components such as catalysts, thickening aids, polymerization inhibitors, thixotropic agents, cure retarders, cure accelerators, photopolymerization initiators, surfactants, interface modifiers, wetting and dispersing agents, antifoaming agents, leveling agents, coupling agents, light stabilizers, waxes, flame retardants, fillers, plasticizers, internal mold release agents, shrinkage reducing agents, toners, viscosity reducing agents, separation prevention agents, and compatibilizers. The content of the additives is not particularly limited as long as it is within a range that does not impair the effects of the present invention. [Polymerization Inhibitor] Furthermore, a polymerization inhibitor can be used to suppress the progress of the polymerization reaction of the resin composition.

[0066] Known polymerization inhibitors can be used, and examples thereof include hydroquinone, methylhydroquinone, phenothiazine, catechol, 4-t-butylcatechol, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. These can be used alone or in combination of two or more. From the viewpoint of ease of inhibiting the progress of the reaction and adjusting the curability, hydroquinone, methylhydroquinone, catechol, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl are preferred. [Curing Accelerator] Furthermore, a curing accelerator can be used to adjust the curing rate.

[0067] The curing accelerator is not particularly limited, and examples thereof include phosphorus compounds, amines such as amine salts, and β-diketones.

[0068] Specific examples of phosphorus compounds include trimethylphosphine and triphenylphosphine, and specific examples of amines include aniline, N,N-dimethylaniline, N,N-diethylaniline, p-toluidine, N,N-dimethyl-p-toluidine, N,N-bis(2-hydroxyethyl)-p-toluidine, 4-(N,N-dimethylamino)benzaldehyde, 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde, 4-(N-methyl-N-hydroxyethylamino)benzaldehyde, N,N-bis(2-hydroxypropyl)-p-toluidine, 4-(N,N-dimethylamino) ... Examples of the β-diketones include toluidine, N-ethyl-m-toluidine, triethanolamine, m-toluidine, diethylenetriamine, pyridine, phenylmorpholine, piperidine, N,N-bis(hydroxyethyl)aniline, N,N-substituted anilines such as diethanolaniline, N,N-substituted-p-toluidine, and 4-(N,N-substituted amino)benzaldehyde. Specific examples of the β-diketones include acetylacetone, ethyl acetoacetate, α-acetyl-γ-butyrolactone, N-pyrrolidininoacetoacetamide, and N,N-dimethylacetoacetamide.

[0069] These may be used alone or in combination of two or more. [Composition of Resin Composition] The content of the vinyl ester resin (A) in the resin composition is preferably 40 to 95 parts by mass, more preferably 45 to 85 parts by mass, and even more preferably 50 to 80 parts by mass, per 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B).

[0070] When the content of the vinyl ester resin (A) is 40 parts by mass or more, a cured product with good strength can be obtained. When the content of the vinyl ester resin (A) is 95 parts by mass or less, the viscosity is such that the resin can easily be impregnated into a fiber substrate, and workability is improved.

[0071] The content of the ethylenically unsaturated group-containing monomer (B) is preferably 5 to 60 parts by mass, more preferably 15 to 55 parts by mass, and even more preferably 20 to 50 parts by mass, relative to 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B).

[0072] When the content of the ethylenically unsaturated group-containing monomer (B) is 5 parts by mass or more, the viscosity becomes such that the fiber substrate can be easily impregnated with the monomer, and workability becomes good. When the content is 60 parts by mass or less, a cured product with good strength can be obtained.

[0073] In the present invention, the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B) are contained in a predetermined ratio, so that the viscosity of the resin composition does not become high and the viscosity is such that the resin composition can easily impregnate a fiber substrate, improving workability and enabling the production of a cured product with excellent strength.

[0074] The content of the metal-containing compound (C) in terms of metal components (hereinafter referred to as "metal component content") is 0.1 × 10 relative to 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B) from the viewpoint of rapid curing of the resin composition. -6 ~2000 x 10 -6 parts by mass, preferably 0.5×10 -6 ~1000 x 10 -6 parts by mass, more preferably 0.5 x 10 -6 ~250 x 10 -6 The content of the metal-containing compound (C) converted into a metal component is 0.1 × 10 -6 By using an amount of at least 2000 parts by mass, it is possible to obtain a resin composition having sufficient hardness and a cured product of a composite material containing the resin composition. -6 When the content of the metal-containing compound (C) is 1 / 2 parts by mass or less, the composite material containing the resin composition and the fiber substrate can be cured more efficiently at a low temperature in a short time. Note that the "content of the metal-containing compound (C) converted into a metal component" means the content by mass of the metal element contained in the metal-containing compound (C).

[0075] The content of the organic peroxide (D) is preferably 0.5 to 4 parts by mass, more preferably 0.7 to 3 parts by mass, and even more preferably 1 to 2.5 parts by mass, per 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B). By having the organic peroxide (D) in this range, the resin composition is sufficiently cured without affecting the physical properties of the cured product.

[0076] The content of the mercapto group-containing compound (E) is preferably 0.5 to 5 parts by mass, more preferably 1 to 4 parts by mass, and even more preferably 2 to 3 parts by mass, relative to 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B). When the content is within this range, curing can be carried out more efficiently.

[0077] By combining (A) to (E) in a predetermined ratio in this way, a resin composition that can be cured at low temperature in a short time can be obtained.

[0078] When the resin composition of the present embodiment contains a polymerization inhibitor, the content of the polymerization inhibitor in the resin composition is preferably 0.0001 to 5 parts by mass, more preferably 0.0005 to 4 parts by mass, and even more preferably 0.01 to 1 part by mass, per 100 parts by mass of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B) in total.

[0079] When the resin composition of this embodiment contains a curing accelerator, the content of the curing accelerator in the resin composition is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 4 parts by mass, and even more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B) combined, from the viewpoint of adjusting curability. [Method for Producing Resin Composition] The method for producing the resin composition of this embodiment is not particularly limited, and the resin composition can be produced by mixing the vinyl ester resin (A), the ethylenically unsaturated group-containing monomer (B), the metal-containing compound (C), the organic peroxide (D), and the mercapto group-containing compound (E). In addition to the vinyl ester resin (A), the ethylenically unsaturated group-containing monomer (B), the metal-containing compound (C), the organic peroxide (D), and the mercapto group-containing compound (E), optional components such as the other components described above may also be mixed.

[0080] The mixing method is not particularly limited, and can be carried out using, for example, a disper, a planetary mixer, a kneader, etc. The mixing temperature is preferably 10 to 50°C.

[0081]

[0042] In addition, from the viewpoint of facilitating uniform mixing of the vinyl ester resin (A), the ethylenically unsaturated group-containing monomer (B), the metal-containing compound (C), the organic peroxide (D), and the mercapto group-containing compound (E) and adjusting the viscosity, the vinyl ester resin (A) may be diluted in advance with at least one of a solvent and a reactive diluent. [Method for curing resin composition] The method for curing the resin composition of the present embodiment is not limited as long as it can heat the resin composition to a temperature required for curing, and for example, a method of heating using a heating furnace or a heater can be used.

[0082] The resin composition of this embodiment cures at a relatively low temperature in a short time of several minutes to several tens of minutes. Therefore, the temperature at which the resin composition is cured is not particularly limited, but it can be cured in the range of 40 to 130°C. The heating time is appropriately selected depending on the curing temperature, for example, between 1 and 40 minutes, preferably between 1 and 30 minutes.

[0083] As long as the resin composition can be cured, there are no particular limitations on the curing conditions as long as the resin composition is not denatured or decomposed, and there is no particular problem even if the temperature is lower than the above range or the curing time is longer.

[0084] [Composite Material] The composite material in this embodiment contains the above-described resin composition and a fibrous base material (G).

[0085] Specific examples of the composite material include prepreg, sheet molding compound (SMC), preform, etc., which can be suitably used for manufacturing various molded products and constructing structures. Prepreg or SMC is particularly preferred as the composite material of this embodiment.

[0086] SMC is a sheet-like material in which a fiber base material cut into pieces of several centimeters is dispersed in a resin composition.

[0087] The content of the fiber base material (G) in the composite material is preferably 20 to 90 mass%, more preferably 30 to 85 mass%, and even more preferably 50 to 75 mass%, relative to 100 mass% of the composite material, from the viewpoints of moldability, ease of handling, mechanical strength, and the like of the composite material.

[0088]

[0033] When the resin composition is impregnated into the fiber substrate, the resin composition may be used as a mixture with additives such as fillers such as calcium carbonate and aluminum hydroxide, low-profile agents such as polystyrene, viscosity reducers, colorants, etc. In this case, these additives may also be contained in the composite material. [Fiber substrate (G)] From the viewpoint of mechanical strength, examples of the fiber substrate (G) include so-called reinforcing fibers such as synthetic fibers such as polyamide (nylon), aramid fiber, vinylon, polyester, and phenolic resin, carbon fiber, glass fiber, metal fiber, and ceramic fiber, as well as composite fibers thereof.

[0089] These may be used alone or in combination of two or more. Among these, aramid fiber, carbon fiber and glass fiber are preferred, and carbon fiber and glass fiber are more preferred from the viewpoints of strength, hardness, availability, price, etc.

[0090] Any carbon fiber manufactured by various manufacturing methods can be used. For example, pitch-based, PAN (polyacrylonitrile)-based, and vapor-phase growth-based carbon fibers can be used. Any glass fiber manufactured by various manufacturing methods can be used. For example, glass fibers such as E-glass, T-glass, and NE-glass can be used. The glass fiber may be either long or short fiber, and the type is selected appropriately depending on the fiber substrate.

[0091] Examples of the form of the fiber substrate (G) include sheets, chopped strands, chopped fibers, milled fibers, etc. Examples of sheets include those formed by aligning multiple reinforcing fibers in one direction, bidirectional woven fabrics such as plain weave and twill weave, multiaxial woven fabrics, non-crimp woven fabrics, nonwoven fabrics, mats, knits, braids, and paper made from reinforcing fibers, etc. The fiber substrate (G) may be used alone or in combination of two or more types.

[0092] In addition, in the case of a sheet, it may be a single layer or may be a laminate of multiple layers. From the viewpoint of impregnation with the resin composition, the thickness of the sheet is, for example, preferably 0.01 to 5 mm in the case of a single layer, and in the case of a laminate of multiple layers, the total thickness is preferably 1 to 20 mm, more preferably 1 to 15 mm. [Method for producing composite material] The method for producing the composite material of this embodiment is not particularly limited, and can be obtained by mixing the above-mentioned resin composition and fiber base material (G) by a known method.

[0093] As a method for producing the composite material of this embodiment, a method of impregnating the fiber base material (G) with the resin composition is particularly preferred. [Method for Molding Composite Material] Examples of methods for molding the composite material of this embodiment include hand lay-up, spray-up, autoclave molding, resin transfer molding (RTM), vacuum-assisted resin transfer molding (VaRTM), pultrusion, injection molding, infusion molding, press molding, press molding using sheet molding compound (SMC), filament winding, and sheet winding.

[0094] The resin composition of the present embodiment cures at low temperatures in a short time. Therefore, from the viewpoint of obtaining a molded product with high hardness, the hand lay-up method, the RTM method, the pultrusion molding method, and the press molding method (including the case where SMC is used) are preferred. From the viewpoint of rapid curing, the pultrusion molding method and the press molding method are preferred, and from the viewpoint of ease of introduction of the molding method, the press molding method (including the case where SMC is used) is even more preferred.

[0095] In the press molding method using SMC, a resin composition is first applied to a carrier film moving at a constant speed, and the continuous fibers are chopped with a rotary cutter to produce short fibers, which are then randomly deposited on the coated lower carrier film. The upper carrier film coated with the resin composition is then placed resin-side down over the chopped fibers, and the sheet is fed through a series of pressure rollers. The air trapped inside the sheet is forced out of the sheet, and the fibers are impregnated with the resin paste, forming a sheet mold compound. [Curing the Composite Material] After molding the composite material of this embodiment into the desired shape, it is subjected to radical polymerization by heating under appropriate pressure or atmospheric pressure to form a cured product.

[0096] The mechanical strength required for a cured composite material varies depending on the intended use. For example, in the case of fiber reinforced plastic (CFRP) using a carbon fiber substrate, the bending strength of the CFRP is generally about 100 to 3000 MPa, and the bending modulus of the FRP is generally about 5 to 150 GPa.

[0097] The values ​​of bending strength and bending modulus are measured in accordance with JIS K7171:2016.

[0098] The present invention will be described below based on examples. The present invention is not limited in any way by the examples shown below. The vinyl ester resins used in the examples and comparative examples shown below are as follows. [Synthesis of vinyl ester resin] First, vinyl ester resins for preparing resin compositions were synthesized according to the following synthesis examples. Details of the epoxy compounds used in the synthesis of vinyl ester resins in the synthesis examples are shown below.

[0099] Epoxy compound (a-1): bisphenol A-type epoxy resin; "Epomic (registered trademark) R140P", manufactured by Mitsui Chemicals, Inc., epoxy equivalent: 188. The epoxy equivalent is a value measured in accordance with JIS K7236: 2001. Synthesis Example 1 2444 g of epoxy compound (a-1) was placed in a 5 L four-neck separable flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, and heated to 110°C.

[0100] Next, 1.1 g of methylhydroquinone ("MH", manufactured by Seiko Chemical Co., Ltd.) as a polymerization inhibitor (0.03 part by mass per 100 parts by mass of the epoxy compound (a-1) and the unsaturated monobasic acid (a-2) described below), 0.2 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl ("Polystub 7300P", manufactured by Hakuto Co., Ltd.) (0.005 part by mass per 100 parts by mass of the epoxy compound (a-1) and the unsaturated monobasic acid (a-2)), and benzyltriphenylphosphonium nitrite as a catalyst were added. 10.7 g of methyl methacrylate ("TPP-ZC", manufactured by Hokko Chemical Industry Co., Ltd.) (0.3 parts by mass relative to 100 parts by mass of the total of the epoxy compound (a-1) and the unsaturated monobasic acid (a-2)) and 1,119 g of methacrylic acid ("methacrylic acid (MAA)", manufactured by Mitsubishi Chemical Corporation) as the unsaturated monobasic acid (a-2) (100 moles of acid groups of the methacrylic acid relative to 100 moles of the total of the epoxy groups of the epoxy compound) were added dropwise over about 30 minutes, and the mixture was heated to 125°C and reacted for about 4 hours to obtain a vinyl ester resin (A1).

[0101] The vinyl ester resin (A1) had an acid value of 13 KOHmg / g, a weight average molecular weight Mw of 790, and a number average molecular weight Mn of 640.

[0102] To 3575 g of this vinyl ester resin (A1), 0.02 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (0.0005 parts by mass relative to a total of 100 parts by mass of the vinyl ester resin (A1) and the styrene monomer added later) was added, and the mixture was cooled to 100°C. 1532 g of styrene ("styrene monomer", manufactured by Idemitsu Kosan Co., Ltd.), which is the ethylenically unsaturated group-containing monomer (B), was added as a reactive diluent to obtain a mixture of 70% by mass of the vinyl ester resin (A1) (based on the total mass of the blended components) and 30% by mass of styrene. <Acid Value> The acid value of the vinyl ester resin (A1) was determined by measuring the mass of potassium hydroxide required to neutralize the acid components contained in the vinyl ester resin (A1) in accordance with JIS K6901:2008 "Partial Acid Value (Indicator Titration Method)."

[0103] Specifically, a mixture was prepared by diluting the vinyl ester resin (A1) obtained in the above Synthesis Example with styrene, which is the ethylenically unsaturated group-containing monomer (B), so that the content was 75% by mass. The mass of potassium hydroxide required to neutralize the acid component contained in the mixture was measured. The acid value of the vinyl ester resin (A1) was then calculated based on the measured value. An "Autoburette UCB-2000" (manufactured by Hiranuma Sangyo Co., Ltd.) was used as the titration apparatus, and a mixed indicator of bromothymol blue and phenol red was used as the indicator. <Weight-Average Molecular Weight Mw, Number-Average Molecular Weight Mn, and Molecular Weight Distribution Mw / Mn> Mw and Mn were measured by GPC under the following measurement conditions, and Mw / Mn was calculated from these measured values.

[0104] (Measurement conditions) Apparatus: "Shodex (registered trademark) GPC-101" (manufactured by Resonac Corporation) Column: "Shodex (registered trademark) LF-804" (manufactured by Resonac Corporation) Detector: differential refractometer "Shodex (registered trademark) RI-71S" (manufactured by Resonac Corporation) Column temperature: 40°C Sample: 0.2% by mass solution of vinyl ester resin in tetrahydrofuran Developing solvent: tetrahydrofuran Flow rate: 1.0 mL / min Sample injection amount: 20 μL Standard sample: polystyrene Example 1 A mixture of 70 parts by mass of vinyl ester resin (A1) as the vinyl ester resin (A) and 30 parts by mass of styrene as the ethylenically unsaturated group-containing monomer (B), and 0.001 parts by mass (metal-equivalent content: 50×10) of copper naphthenate (manufactured by Toei Kako Co., Ltd., copper content 5% by mass) as the metal-containing compound (C) was analyzed. -6To a total of 100 parts by mass of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B), 1 part by mass of cumene hydroperoxide ("Percumyl H-80" manufactured by NOF Corporation) as the organic peroxide (D) and 2 parts by mass of pentaerythritol tetrakis(3-mercaptobutyrate) ("Karenz MT (registered trademark) PE1" manufactured by Resonac Co., Ltd.) as the mercapto group-containing compound (E) were added, and the mixture was mixed at 2000 to 3000 rpm using a Disper (high-speed dispersion base "Homodisper 2.5 type" manufactured by Primix Corporation) for 20 minutes to obtain resin composition (X-1). [Examples 2 to 9, Comparative Examples 1 to 16] Resin compositions (X-2) to (X-9) for the examples and resin compositions (X'-1) to (X'-15) for the comparative examples were obtained by production in the same manner as in Example 1, except that the raw materials and compounding ratios were as shown in Tables 1 and 2. In Examples 2 to 6 and Comparative Examples 1 to 13, the type of metal-containing compound (C) in Example 1 was changed, and in Examples 7 to 9 and Comparative Examples 14 to 16, the amount of metal-containing compound (C) or the amount of mercapto group-containing compound (E) in Example 1 was changed.

[0105] The obtained resin composition was subjected to measurement and evaluation for the following items. The results of these measurements and evaluations are shown in Table 1 below. <80°C curability> The obtained resin composition was placed in a test tube (outer diameter 18 mm, length 165 mm) at room temperature to a depth of 100 mm, and placed in an oil bath heated to 80°C, and the test tube and its contents were heated. The temperature of the resin composition in the contents was measured using a thermocouple. The time required for the temperature of the resin composition to reach the maximum temperature from 65°C was defined as the "minimum curing time," and the maximum temperature was defined as the "maximum exothermic temperature," and these were measured in accordance with JIS K-6901:2021.

[0106] Measurements were performed twice, and the average value was calculated. <Barcol Hardness> The surface hardness of the cured resin composition was measured using a Barcol hardness tester ("GYZJ 934-1" (HBI-A), manufactured by Barber-Coleman) in accordance with JIS K6911:1995, and this was taken as the Barcol hardness. Values ​​range from 0 to 100, with larger values ​​indicating harder specimens. Measurement samples were prepared as follows: A tin cup (40 mm diameter x approximately 8 mm deep) was placed on a stainless steel plate (5 mm thick) preheated to 80°C, and approximately 10 g of the resin composition was placed in the cup. The cup was sealed with a release-treated film (125 μm thick), and another stainless steel plate was placed on top of it. The tin cup was sandwiched between the two stainless steel plates and heated in a heating device at 80°C for 15 minutes. Next, the tin cup was removed from the heating device and cured in a thermostatic chamber (23°C x 24 hours), after which the release film was peeled off and the Barcol hardness of the surface of the cured resin composition was measured. <Bending test> Test specimens were prepared and evaluated for bending strength and bending modulus as follows.

[0107] A U-shaped spacer with an outer size of 150 mm x 150 mm, a thickness of 3 mm, and a width of 1.5 mm was sandwiched between two glass plates (150 mm x 150 mm x 3 mm) with a release film attached to the surface and fixed to form a glass mold. Approximately 50 g of the resin composition was poured from the top of the glass mold, which was placed with the opening of the spacer facing up. The glass mold was heated at 110 ° C for 30 minutes to cure the resin composition.

[0108] The cured product was cut into a length of 80 mm, a width of 25 mm, and a thickness of 3 mm to prepare three test pieces. In accordance with JIS K 6911-1995, the flexural strength and flexural modulus were measured using a universal testing machine ("Tensilon UCT-1T", manufactured by Orientec Co., Ltd., test speed 1.5 mm / min) at a temperature of 23°C and a humidity of 50%. Measurements were taken for three test pieces each, and the average was calculated.

[0109]

[0110] In terms of 80°C curability, the resin compositions of the Examples all had shorter minimum curing times and higher or equivalent maximum exotherm temperatures than the Comparative Examples. In other words, it was demonstrated that they could be cured at low temperatures in a short time.

[0111] Furthermore, all of the Examples had high hardness, and both bending strength and bending modulus were sufficient. On the other hand, many of the Comparative Examples were insufficiently cured and could not be evaluated, and even those that could be evaluated had low bending strength. [Examples 10 and 11] <Evaluation of Carbon Fiber Reinforced Composite Material> Resin composition (X-1) was used in Example 10, and resin composition (X-7) was used in Example 11. Carbon fiber tows of Mitsubishi Chemical Corporation carbon fiber TR50S12L (sizing agent type AL) were used as the fiber substrate (G) in Example 10, and Mitsubishi Chemical Corporation carbon fiber TR50S12L (sizing agent type KL) were used in Example 11. Carbon fiber reinforced composite materials were prepared as follows. Preparation of Cured Products In Examples 10 and 11, cured carbon fiber reinforced composite material samples were prepared by a filament winding method.

[0112] Two of the tows were wrapped around a 300 mm (length) x 230 mm (width) x 1 mm (thickness) square-shaped mold, with each tow parallel to the others and overlapping eight times in the longitudinal direction, at the center of the mold width. The tow had 16 layers, with the combined width of the two tows being 14-16 mm. With the tows still restrained, the mold was placed on a glass plate of a shape corresponding to the inside of the square-shaped mold. Two 1 mm-thick rubber spacers were placed longitudinally between the frame and the left and right sides of the tow, respectively, along the length of the mold, and the tow was then impregnated with the resin composition. The top surface of the tow was then sandwiched between glass plates of the same size as the above. A 1 kg weight was placed on the glass plate, and the mixture was pre-cured at room temperature (25°C). After 24 hours, the mixture was post-cured by heating at 120°C for 2 hours (Example 10) or 3 hours (Example 11) at 120°C. After post-curing, the glass plate and spacers were removed, and the rectangular cured product was removed from the mold. This resulted in a cured product of a carbon fiber reinforced composite material containing 16 layers of tow. This cured product was cut to the following specified sizes and subjected to the various measurements and evaluations. In the evaluation sample, the direction parallel to the tows was designated the M direction, and the width direction perpendicular to the tows was designated the T direction. Fiber volume content (Vf) and fiber content (mass%) in the cured product: The cured product was cut into a 15 mm x 15 mm x 1 mm rectangular parallelepiped to prepare a test specimen. The mass of the test specimen was measured, and the test specimen was heated in a crucible in an air atmosphere at 350°C for 3 hours using a muffle furnace (Yamato Scientific, "Muffle Fumace FO510"), followed by heating at 625°C for 10 minutes. After natural cooling, the mass of the remaining carbon fiber was measured, and the carbon fiber content (mass%) and fiber volume content per unit volume in the cured product were evaluated. The density of the cured resin is 1.15 g / cm 3 , the density of carbon fiber is 1.81 g / cm 3 Two test pieces were prepared and the average was taken. Flexural properties: The cured product was cut into a length of 60 mm (M direction) x width of 15 mm (T direction) x thickness of 1 mm to prepare test pieces. Using a universal material testing machine ("Tensilon UCT-1T", manufactured by Orientec Co., Ltd., support distance 48 mm, test speed 5 mm / min), the flexural strength and flexural modulus in the M direction were measured under an environment of a temperature of 23°C and a humidity of 50% RH. Two test pieces were measured and the average value was calculated.

[0113] The results are shown in Table 2.

[0114] In all of the examples, cured products having sufficiently high bending strength and elastic modulus were obtained.

Claims

1. A resin composition comprising a vinyl ester resin (A), an ethylenically unsaturated group-containing monomer (B), a metal-containing compound (C), an organic peroxide (D), and a mercapto group-containing compound (E), wherein the metal-containing compound (C) is a compound containing a metal element of Groups 7 to 11, and the metal-equivalent content of the metal-containing compound (C) is 0.1 x 10 relative to 100 parts by mass of the total of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B). -6 ~2000 x 10 -6 Parts by mass of the resin composition.

2. The resin composition according to claim 1, wherein the metal element contained in the metal-containing compound (C) is at least one selected from the group consisting of iron, nickel, cobalt, manganese, and copper.

3. The resin composition according to claim 2, wherein the metal-containing compound (C) is at least one carboxylate selected from iron, nickel, cobalt, manganese, and copper, or at least one β-diketone complex selected from iron, nickel, cobalt, manganese, and copper.

4. The resin composition according to claim 3, wherein the metal-containing compound (C) comprises at least one selected from the group consisting of copper naphthenate, copper bis(2,4-pentanedionato), nickel(II) bis(2,4-pentanedionato), cobalt octoate, manganese octoate, and iron naphthenate.

5. The resin composition according to claim 1 or 2, comprising 40 to 95 parts by mass of the vinyl ester resin (A), 5 to 60 parts by mass of the ethylenically unsaturated group-containing monomer (B), and 0.5 to 4 parts by mass of the organic peroxide (D), relative to a total of 100 parts by mass of the vinyl ester resin (A) and the ethylenically unsaturated group-containing monomer (B).

6. The resin composition according to claim 1 or 2, wherein the vinyl ester resin (A) is a reaction product of an epoxy compound (a-1) having two or more epoxy groups per molecule and an unsaturated monobasic acid (a-2), and the total number of acid groups in the unsaturated monobasic acid (a-2) is 80 to 105 moles per 100 moles of the total number of epoxy groups in the epoxy compound (a-1).

7. The resin composition according to claim 6, wherein the epoxy compound (a-1) is a bisphenol-type epoxy resin.

8. The resin composition according to claim 6, wherein the unsaturated monobasic acid (a-2) is at least one selected from the group consisting of (meth)acrylic acid and crotonic acid.

9. A resin composition according to claim 1 or 2, wherein the organic peroxide (D) is at least one selected from the group consisting of peroxyester-based organic peroxides, hydroperoxide-based organic peroxides, dialkyl peroxide-based organic peroxides, and peroxyketal-based organic peroxides.

10. The resin composition according to claim 1 or 2, wherein the mercapto group-containing compound (E) is a polyfunctional thiol.

11. A composite material comprising the resin composition according to claim 1 and a fiber substrate (G).

12. The composite material according to claim 11, wherein the fiber substrate (G) is at least one selected from carbon fiber and glass fiber.

13. A method for producing a molded product, comprising the steps of molding and curing the composite material according to claim 11 or 12 by one or more methods selected from hand layup molding, pultrusion molding, and press molding.

14. A cured product of the composite material according to claim 11 or 12.

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