Prepregs and fiber-reinforced plastics

Abstract

To provide a prepreg that results in fiber-reinforced plastic with improved toughness while maintaining strength and elastic moduli, and fiber-reinforced plastic formed using the prepreg.SOLUTION: A prepreg contains a matrix resin composition and reinforced fiber. The matrix resin composition contains epoxy resin and (meth)acryl monomers. The ratio R of the double bond equivalent of the (meth)acryl monomers to the epoxy equivalent of the epoxy resin (double bond equivalent / epoxy equivalent) is 1.0 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to prepregs and fiber reinforced plastics.

Background Art

[0002] Fiber reinforced plastic, which is one of fiber reinforced composite materials, is lightweight, high-strength, and high-rigidity, and thus is widely used from sports and leisure applications to industrial applications such as automobiles and aircraft. As a method for manufacturing fiber reinforced plastics, there is a method using an intermediate material in which a reinforcing material made of long fibers (continuous fibers) such as reinforcing fibers is impregnated with a matrix resin, that is, a prepreg. According to this method, there is an advantage that it is easy to control the content of the reinforcing fibers in the fiber reinforced plastic and it is possible to design the content to be high. By laminating a plurality of prepregs and heating and curing them, a molded product can be obtained.

[0003] Due to the need for weight reduction, carbon fibers having excellent specific strength and specific modulus are widely used as reinforcing fibers, and epoxy resins having excellent adhesion to carbon fibers are widely used as matrix resins. However, since epoxy resins generally tend to have brittle cured products (resin cured products) and low toughness, improving the fracture toughness and rigidity of fiber reinforced plastics has been a technical problem. Therefore, in recent years, studies have been made to improve toughness by adding a modifier such as a block copolymer and using the phase separation structure generated during the curing process of the resin. In this modification system, however, the glass transition temperature (Tg) of the resin cured product of the epoxy resin and the elastic modulus of the resin cured product tend to decrease. In addition, although toughening of epoxy resins has been conventionally performed by a modification method using engineering plastics such as polyethersulfone, a significant increase in viscosity cannot be avoided.

[0004] To solve this problem, attempts have been made to polymerize the monomers used as raw materials for the modifier in-situ within the system, and simultaneously carry out the production of the modifier and the curing reaction of the matrix resin (see, for example, Non-Patent Document 1). In this attempt, a vinyl polymer produced by radical polymerization is used as a modifier, and in the field of fiber reinforced plastics, technological development for producing intermediate materials by using an epoxy resin and radical polymerization in combination has also advanced (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] <OO00121>One object of the present invention is to provide a prepreg capable of obtaining a fiber reinforced plastic with improved toughness while maintaining strength and modulus of elasticity, and a fiber reinforced plastic formed using this prepreg.

Means for Solving the Problems

[0008] The present invention has the following aspects. [1] A prepreg containing a matrix resin composition and reinforcing fibers, The matrix resin composition comprises an epoxy resin and a (meth)acrylic monomer. A prepreg in which the ratio R (double bond equivalent / epoxy equivalent) of the double bond equivalent of the (meth)acrylic monomer to the epoxy equivalent of the epoxy resin is 1.0 or greater. [2] The prepreg of [1], further comprising a curing agent and a thermal radical polymerization initiator. [3] The prepreg of [1] or [2], wherein the epoxy resin comprises at least one selected from the group consisting of novolac-type epoxy resins and trifunctional or more amine-type epoxy resins. [4] Any of the prepregs from [1] to [3], wherein the epoxy equivalent of the epoxy resin is 150 g / eq or more. [5] Any of the prepregs from [1] to [4] above, wherein the epoxy equivalent of the epoxy resin is 250 g / eq or less. [6] Any of the prepregs from [1] to [5], wherein the double bond equivalent of the (meth)acrylic monomer is 150 g / eq or more. [7] Any of the prepregs from [1] to [6], wherein the double bond equivalent of the (meth)acrylic monomer is 1500 g / eq or less. [8] Any of the prepregs from [1] to [7], wherein the (meth)acrylic monomer comprises at least one selected from the group consisting of monofunctional (meth)acrylic monomers and bifunctional (meth)acrylic monomers with a molecular weight of 150 or more. [9] A prepreg of any of the above [1] to [8] wherein the (meth)acrylic monomer comprises at least one selected from the group consisting of monofunctional (meth)acrylic monomers represented by the following general formula (1) and bifunctional (meth)acrylic monomers represented by the following general formula (2).

[0009] [ka]

[0010] In general formula (1), R 1 R is a hydrogen atom or a methyl group,2 is an alkylene group having 2 to 6 carbon atoms, and R 3 is an aromatic hydrocarbon group or an alicyclic hydrocarbon group, and p is an integer of 1 or more. In the general formula (2), R 4 and R 5 are each independently a hydrogen atom or a methyl group, and R 6 is a divalent organic group having 2 to 55 carbon atoms.

[0011]

[10] The prepreg according to [9], wherein the R 2 in the general formula (1) is an alkylene group having 2 to 6 carbon atoms, the R 3 is a phenyl group, a biphenyl group or a dicyclopentenyl group, and the p is an integer of 1 to 4.

[11] The prepreg according to [9] or

[10] , wherein the R 6 in the general formula (2) is an alkylene group having 2 to 15 carbon atoms or a divalent organic group having 6 to 55 carbon atoms having a cyclic structure.

[12] The prepreg according to

[11] , wherein the divalent organic group having 6 to 55 carbon atoms having a cyclic structure is a divalent organic group represented by the following general formula (3).

[0012] [Chemical formula]

[0013] In the general formula (3), R 7 and R 8 are each independently an alkylene group having 2 to 6 carbon atoms, and R 9 and R 10 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m and n are each independently an integer of 1 or more.

[0014]

[13] The prepreg according to [2], wherein the curing agent contains at least one selected from the group consisting of dicyandiamide, aromatic amines, ureas and imidazoles.

[14] The prepreg according to [2] or

[13] , wherein the thermal radical polymerization initiator contains organic peroxides.

[15] A prepreg according to any of [2],

[13] , and

[14] , wherein the 10-hour half-life temperature of the thermal radical polymerization initiator is 70°C or higher.

[16] A prepreg of any of the above [1] to

[15] , wherein the matrix resin composition further comprises a thermoplastic resin.

[17] The prepreg of

[16] wherein the thermoplastic resin comprises at least one selected from the group consisting of polyvinyl formal, polyvinyl butyral, polyethersulfone, and phenoxy resin.

[18] The matrix resin composition is a prepreg of any of [1] to

[17] , comprising 5 to 40 parts by mass of the (meth)acrylic monomer with respect to 100 parts by mass of the epoxy resin.

[19] The matrix resin composition is a prepreg of any of [2],

[13] ,

[14] and

[15] , comprising 0.1 to 5 parts by mass of the thermal radical polymerization initiator per 100 parts by mass of the (meth)acrylic monomer.

[20] A fiber-reinforced plastic obtained by curing any of the prepregs described in [1] to

[19] above. [Effects of the Invention]

[0015] According to a preferred embodiment of the present invention, it is possible to provide a prepreg that yields a fiber-reinforced plastic with improved toughness while maintaining strength and elastic modulus. Furthermore, it is possible to provide a fiber-reinforced plastic with improved adhesive strength between the matrix resin and the reinforcing fibers. [Modes for carrying out the invention]

[0016] The present invention will be described in detail below. In this specification, cured products obtained by curing a matrix resin composition are referred to as "resin cured products," and among these, plate-shaped cured products are sometimes referred to as "resin plates." A numerical range represented by "~" means a range that includes the numbers before and after the "~" as the lower and upper limits, respectively. The numerical ranges of the content, various physical properties, and characteristic values ​​disclosed herein can be modified by arbitrarily combining their lower and upper limits to create new numerical ranges.

[0017] [Prepreg] A prepreg according to a first aspect of the present invention comprises a matrix resin composition and reinforcing fibers. The prepreg may or may not contain other components in addition to the matrix resin composition and reinforcing fibers. Preferably, the prepreg consists only of the matrix resin composition and reinforcing fibers.

[0018] <Matrix resin composition> The matrix resin composition contains an epoxy resin and a (meth)acrylic monomer. The matrix resin composition preferably further comprises a curing agent and a thermal radical polymerization initiator in addition to the epoxy resin and (meth)acrylic monomer. The matrix resin composition preferably further comprises a thermoplastic resin in addition to the epoxy resin, (meth)acrylic monomer, curing agent and thermal radical polymerization initiator. The matrix resin composition may further comprise components other than the epoxy resin, (meth)acrylic monomer, curing agent, thermal radical polymerization initiator and thermoplastic resin (hereinafter also referred to as "optional components"). The individual components of the matrix resin composition will be described later.

[0019] The epoxy resin and (meth)acrylic monomer are blended into the matrix resin composition such that the ratio R (double bond equivalent / epoxy equivalent) of the double bond equivalent of the (meth)acrylic monomer to the epoxy equivalent of the epoxy resin is 1.0 or greater. As the epoxy equivalent of the epoxy resin decreases, the crosslinked structure of the matrix resin composition becomes denser, and the elastic modulus of the cured resin and fiber-reinforced plastic tends to improve. Also, as the double bond equivalent of the (meth)acrylic monomer increases, the toughness of the cured resin and fiber-reinforced plastic tends to improve. By setting the ratio R to 1.0 or higher, fine phase separation can be promoted during curing, in which the cured epoxy resin becomes the sea phase and the polymer of the (meth)acrylic monomer becomes the island phase, kinetically speaking. The improvement in toughness occurs when cracks reach the dispersed island phase, due to (i) cavitation caused by stress concentration in the island phase, (ii) release of strain constraints and relaxation of stress concentration due to cavitation, (iii) induction of shear deformation of the resin due to cavitation, (iv) energy absorption due to deformation of the island phase itself, and (v) suppression of crack growth by the island phase.

[0020] A ratio R of 1.0 or higher is preferable, and a ratio of 1.1 or higher is more preferable, as this improves the strength and elastic modulus of the fiber-reinforced plastic. There are no particular restrictions on the upper limit of ratio R, but a ratio R of 10.0 or less is preferred, more preferably 5.0 or less, and even more preferably 3.0 or less, as this improves the toughness of the fiber-reinforced plastic. The aforementioned upper and lower limits of the ratio R can be combined arbitrarily. For example, the ratio R is preferably 1.0 to 10.0, more preferably 1.1 to 5.0, and even more preferably 1.3 to 3.0. The epoxy equivalent of the epoxy resin and the double bond equivalent of the (meth)acrylic monomer will be discussed later.

[0021] (Epoxy resin) Examples of epoxy resins (hereinafter also referred to as "component (A)") include, but are not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, epoxy resin having an oxazolidone ring skeleton, novolac type epoxy resin, glycidylamine type epoxy resin, and naphthalene type epoxy resin. Among these, novolac type epoxy resin and glycidylamine type epoxy resin are preferred because they increase the elastic modulus of the cured resin. Among glycidylamine type epoxy resins, amine type epoxy resins with three or more functions are preferred. Examples of glycidylamine type epoxy resins include triglycidylaminophenol, triglycidylaminocresol, tetraglycidyldiaminodiphenylmethane, and tetraglycidyl-m-xylenediamine. Examples of novolac-type epoxy resins include phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, biphenyl aralkyl-type epoxy resins, naphthol cresol novolac-type epoxy resins, trisphenolmethane-type epoxy resins, and dicyclopentadiene-type epoxy resins. These can be used individually or in combination of two or more. It is preferable to use two or more in combination, as this allows for the production of prepregs with excellent handling properties and fiber-reinforced plastics with improved mechanical properties and heat resistance. In particular, it is preferable to use a novolac-type epoxy resin in combination with a trifunctional or higher amine-type epoxy resin.

[0022] Commercially available novolac-type epoxy resins include, but are not limited to, phenol novolac-type epoxy resins such as jER152, jER154 (both manufactured by Mitsubishi Chemical Corporation), EPICLON N-740, EPICLON N-770, EPICLON N-775 (both manufactured by DIC Corporation), and YDPN-638 (manufactured by Nippon Steel Chemical & Material Co., Ltd.); cresol novolac-type epoxy resins such as EPICLON N-660, EPICLON N-670, EPICLON N-680, and EPICLON N-690 (all manufactured by DIC Corporation); and bisphenol A novolac-type epoxy resins such as jER157S70 (manufactured by Mitsubishi Chemical Corporation), EPICLON N-865, and EPICLON N-885 (both manufactured by DIC Corporation). These can be used individually or in combination of two or more types.

[0023] Examples of commercially available amine-type epoxy resins with three or more functionalities include, but are not limited to, jER630, jER604 (both manufactured by Mitsubishi Chemical Corporation), YH-434, YH-434L (both manufactured by Nippon Steel Chemical & Material Corporation), SumiEpoxy ELM434 (both manufactured by Sumitomo Chemical Co., Ltd.), TEPIC-G, TEPIC-S, TEPIC-SP, TEPIC-SS, TEPIC-PAS B26L, TEPIC-PAS B22, TEPIC-VL, TEPIC-UC (all manufactured by Nissan Chemical Corporation), TETRAD-X, TETRAD-C (both manufactured by Mitsubishi Gas Chemical Company, Inc.), and Araldite MY0500, MY0510, MY0600, MY0610, MY0720, MY0721, MY0725 (all manufactured by Huntsman Japan Co., Ltd.). These can be used individually or in combination of two or more types.

[0024] Other commercially available epoxy resins besides those mentioned above include the following: Examples of commercially available liquid bisphenol A type epoxy resins at 25°C include, but are not limited to, jER827, jER828 (both manufactured by Mitsubishi Chemical Corporation), YD-127, YD-128 (both manufactured by Nippon Steel Chemical & Material Corporation), EPICLON840, EPICLON850 (both manufactured by DIC Corporation), DER331, DER332 (both manufactured by The Dow Chemical Company). Examples of commercially available bisphenol F type epoxy resins that are liquid at 25°C include, but are not limited to, jER806, jER807 (both manufactured by Mitsubishi Chemical Corporation), YDF-170 (manufactured by Nippon Steel Chemical & Material Corporation), EPICLON830, EPICLON835 (both manufactured by DIC Corporation), and DER354 (manufactured by The Dow Chemical Company). Examples of commercially available bisphenol A type epoxy resins that are semi-solid or solid at 25°C include, but are not limited to, jER1001, jER1002, jER1004, jER1007, jER1009 (all manufactured by Mitsubishi Chemical Corporation), EPICLON2050, EPICLON3050, EPICLON4050, EPICLON7050 (all manufactured by DIC Corporation), YD-011, YD-012, YD-013, YD-014, YD-902, YD-903N, YD-904, YD-907, YD-7910, YD-6020 (all manufactured by Nippon Steel Chemical & Material Co., Ltd.). Examples of bisphenol F type epoxy resins that are semi-solid or solid at 25°C include, but are not limited to, jER4004P, jER4005P, jER4007P, jER4010P (all manufactured by Mitsubishi Chemical Corporation), YDF-2001, YDF-2004, YDF-2005RD (all manufactured by Nippon Steel Chemical & Material Corporation). Examples of epoxy resins having an oxazolidone ring skeleton that is semi-solid or solid at 25°C include, but are not limited to, ACR1348 (manufactured by ADEKA Corporation), DER852, DER858 (both manufactured by THE DOW CHEMICAL COMPANY), TSR-400 (manufactured by DIC Corporation), and YD-952 (manufactured by Nippon Steel Chemical & Material Co., Ltd.). These can be used individually or in combination of two or more types.

[0025] The epoxy equivalent of the epoxy resin is preferably 150 g / eq or more, more preferably 160 g / eq or more, and even more preferably 165 g / eq or more, because this increases the molecular weight between crosslinking points of the cured resin and improves the toughness of the cured product. Furthermore, the epoxy equivalent of the epoxy resin is preferably 250 g / eq or less, more preferably 240 g / eq or less, and even more preferably 230 g / eq or less, because this prevents a decrease in the elastic modulus of the cured resin. If the epoxy equivalent of the epoxy resin is below the above upper limit, a decrease in the elastic modulus of the cured resin can be prevented. The aforementioned upper and lower limits for the epoxy equivalent of the epoxy resin can be combined arbitrarily. For example, the epoxy equivalent of the epoxy resin is preferably 150 to 250 g / eq, more preferably 160 to 240 g / eq, and even more preferably 165 to 230 g / eq.

[0026] The epoxy equivalent of epoxy resin can be measured in accordance with JIS K 7236:2001. When a matrix resin composition contains multiple epoxy resins, the epoxy equivalent of the epoxy resin is the average value of the epoxy equivalents of all epoxy resins contained in the matrix resin composition, and can be calculated as follows. For example, let's explain the calculation method using the case where three types of epoxy resins are used in combination. When 1 part by mass of epoxy resin with an epoxy equivalent of E1 (g / eq), 2 parts by mass of epoxy resin with an epoxy equivalent of E2 (g / eq), and 3 parts by mass of epoxy resin with an epoxy equivalent of E3 (g / eq) are blended, the epoxy equivalent can be calculated using the following formula. Epoxy equivalent = (W1 + W2 + W3) / (W1 / E1 + W2 / E2 + W3 / E3)

[0027] The epoxy resin content can be adjusted as needed relative to the total mass of the matrix resin composition, but is preferably 60-95% by mass, more preferably 70-95% by mass, and even more preferably 70-85% by mass. If the epoxy resin content is above the lower limit, the mechanical properties of the cured product can be improved. If the epoxy resin content is below the upper limit, a cured product without curing defects is more likely to be obtained.

[0028] ((meth)acrylic monomer) (Meth)acrylic monomer (hereinafter also referred to as "component (B)") is a component that contributes to improving the elastic modulus and toughness of cured resin products. Examples of (meth)acrylic monomers include monofunctional (having one acryloyl group) (meth)acrylic monomers and difunctional or more functional (having two or more acryloyl groups) (meth)acrylic monomers. Among these, monofunctional (meth)acrylic monomers and difunctional (meth)acrylic monomers are preferred, and monofunctional (meth)acrylic monomers with a molecular weight of 150 or more and difunctional (meth)acrylic monomers with a molecular weight of 150 or more are more preferred. These can be used individually or in combination of two or more types.

[0029] Examples of monofunctional (meth)acrylic monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxybenzyl (meth)acrylate, 4-hydroxyphenyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, 2-(meth)acryloyloxymethyl-2-methylbicycloheptane, adamantyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, tetracyclododecanyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate. Acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, eicosyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, methoxydipropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate, polypropylene glycol monomethyl (meth)acrylate, 4-acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4-acryloyloxymethyl-2-methyl-2-isobutyl-1,(meth)acrylic acid esters such as 3-dioxolane, o-phenylphenol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, nonylphenyl polyethylene glycol (meth)acrylate, dicyclopentenyloxyethylene (meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, N-(meth)acryloyloxyethylhexahydrophthalimide, paracumylphenol (meth)acrylate, ethoxylated paracumylphenol (meth)acrylate, trimethylolpropane formal (meth)acrylate; acrylamine Examples of (meth)acrylamides include, but are not limited to, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-butoxymethylacrylamide, Nt-butylacrylamide, N-benzyl(meth)acrylamide, N-phenyl(meth)acrylamide, N-(4-hydroxybenzyl)(meth)acrylamide, N-(4-hydroxyphenyl)(meth)acrylamide, acryloylmorpholine, hydroxyethylacrylamide, methylenebisacrylamide, and other (meth)acrylamides. Among these, monofunctional (meth)acrylamides having at least one of one of one oxyalkylene groups and one or more cyclic structures (cyclic skeletons) in the molecule are preferred, as they can reduce the volatility of the monofunctional (meth)acrylamide and further improve the toughness of the cured resin. Monofunctional (meth)acrylamides having at least one of one oxyalkylene groups and one or more cyclic structures in the molecule (hereinafter also referred to as "component (B1)") are more preferred. These can be used individually or in combination of two or more types.

[0030] (B1) Examples of components include, but are not limited to, monofunctional (meth)acrylic monomers represented by the following general formula (1) (hereinafter also referred to as "monomer (1)").

[0031] [ka]

[0032] In general formula (1), R 1 R is a hydrogen atom or a methyl group, 2 R is an alkylene group having 2 to 6 carbon atoms. 3 p is an aromatic hydrocarbon group or an alicyclic hydrocarbon group, and p is an integer greater than or equal to 1.

[0033] R 1 This is either a hydrogen atom or a methyl group, with a hydrogen atom being preferred. R 2 R is an alkylene group having 2 to 6 carbon atoms, preferably an alkylene group having 2 to 4 carbon atoms, more preferably an alkylene group having 2 or 3 carbon atoms, and even more preferably an alkylene group having 2 carbon atoms (ethylene group). 2 The alkylene group may be linear or branched. R 3 R is an aromatic hydrocarbon group or an alicyclic hydrocarbon group. Examples of aromatic hydrocarbon groups include, but are not limited to, phenyl, benzyl, naphthyl, biphenyl, and tolyl groups. Examples of alicyclic hydrocarbon groups include, but are not limited to, dicyclopentenyl, cyclopentyl, cyclohexyl, and cyclohexenyl groups. 3 As such, a phenyl group, a biphenyl group, or a dicyclopentenyl group is preferred. 3 The aromatic hydrocarbon group or alicyclic hydrocarbon group may or may not have substituents. Examples of substituents include, but are not limited to, C1-C12 alkyl groups, cyano groups, halogen atoms, etc. The alkyl group may be linear or branched. p is an integer greater than or equal to 1, preferably an integer between 1 and 10, and more preferably an integer between 1 and 4.

[0034] The monomer (1) is R in general formula (1). 2 This is an alkylene group with 2 to 6 carbon atoms, R 3A monofunctional (meth)acrylic monomer is preferred in which the group is a phenyl group, a biphenyl group, or a dicyclopentenyl group, and p is an integer from 1 to 4. Specifically, examples include (meth)acrylic acid esters such as phenoxydiethylene glycol (meth)acrylate, nonylphenyl polyethylene glycol (meth)acrylate, dicyclopentenyloxyethylene (meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, and ethoxylated paracumylphenol (meth)acrylate. These can be used individually or in combination of two or more types.

[0035] Examples of difunctional (meth)acrylic monomers include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 2-methyl-1,8-octane. Examples of diols include, but are not limited to, diols such as diols, 1,10-decanediol, neopentyl glycol hydroxypivalate, tricyclodecanedimethanol, cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A, bisphenol F, dioxane glycol, and bisphenoxyfluoreneethanol, as well as di(meth)acrylates obtained by esterifying diols obtained by adding ethylene oxide, propylene oxide, or caprolactone to these diols with (meth)acrylic acid. Among these, bifunctional (meth)acrylic monomers having one or more oxyalkylene groups and at least one of one or more cyclic structures in the molecule are preferred, and bifunctional (meth)acrylic monomers having one or more oxyalkylene groups and one or more cyclic structures in the molecule (hereinafter also referred to as "(B2) component") are more preferred, as they can provide a better balance of elastic modulus, strength, and toughness of the cured resin. These can be used individually or in combination of two or more types.

[0036] Examples of preferred difunctional (meth)acrylic monomers include, but are not limited to, those represented by the following general formula (2) (hereinafter also referred to as "monomer (2)").

[0037] [ka]

[0038] In general formula (2), R 4 and R 5 Each is independently a hydrogen atom or a methyl group, and R 6 It is a divalent organic group with 2 to 55 carbon atoms.

[0039] R 4 and R 5 Each is independently a hydrogen atom or a methyl group, and R 4 and R 5 Hydrogen atoms are preferred in both cases. R 6 This is a divalent organic group having 2 to 55 carbon atoms. The divalent organic group may or may not have an oxygen atom, but it is preferable that it does. Examples of divalent organic groups include alkylene groups having 2 to 15 carbon atoms, and divalent organic groups having 6 to 55 carbon atoms with a cyclic structure, but are not limited to these. Among divalent organic groups having 6 to 55 carbon atoms with a cyclic structure, those having one or more oxyalkylene groups are preferred, and the divalent organic group represented by the following general formula (3) is more preferred. Of the monomers (2), R 6 Compounds in which the group is a divalent organic group represented by the following general formula (3) are examples of component (B2).

[0040] [ka]

[0041] In general formula (3), R 7 and R 8 Each of these is an alkylene group with 2 to 6 carbon atoms, and R 9 and R 10 Each of these is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m and n are independently integers of 1 or more.

[0042] R 7 and R 8 Each of these is independently an alkylene group having 2 to 6 carbon atoms, with a preferred alkylene group having 2 to 4 carbon atoms, and a more preferred alkylene group having 2 or 3 carbon atoms, R 7 and R 8 Alkylene groups (ethylene groups) having 2 carbon atoms are even more preferred. 7 and R 8 The alkylene groups may be linear or branched. R 9 and R 10 Each of these is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, with alkyl groups having 1 to 6 carbon atoms being preferred, alkyl groups having 1 to 3 carbon atoms being more preferred, and alkyl groups having 1 or 2 carbon atoms being even more preferred. 9 and R 10 Alkyl groups (methyl groups) having one carbon atom are particularly preferred. The alkyl groups may be linear or branched. m and n are independent integers of 1 or greater, preferably between 1 and 10, and more preferably between 1 and 4. Furthermore, m+n is preferably an integer between 2 and 20, more preferably between 2 and 10, and even more preferably between 2 and 6.

[0043] The monomer (2) is R in general formula (2). 6 A bifunctional (meth)acrylic monomer in which is an alkylene group having 2 to 12 carbon atoms or a divalent organic group having 6 to 55 carbon atoms with a cyclic structure is preferred, and R in general formula (2) 6A difunctional (meth)acrylic monomer, which is a divalent organic group represented by general formula (3), is more preferred. Specifically, 1,9-nonanediol di(meth)acrylate and ethoxylated bisphenol A di(meth)acrylate are preferred, and the (B2) component such as ethoxylated bisphenol A di(meth)acrylate is more preferred. These can be used individually or in combination of two or more types.

[0044] The molecular weight of the (meth)acrylic monomer is preferably 150 or higher, more preferably 190 or higher, even more preferably 220 or higher, and particularly preferably 250 or higher, as it allows for excellent handling of the (meth)acrylic monomer, suppression of volatilization, and sufficient raising of the preparation temperature when preparing the matrix resin composition and the impregnation temperature when preparing the prepreg, thereby obtaining a product of consistent quality. Furthermore, the molecular weight of the (meth)acrylic monomer is preferably 1500 or lower, more preferably 1000 or lower, and even more preferably 800 or lower, as it facilitates uniform dispersion of the (meth)acrylic monomer in the matrix resin composition. The aforementioned upper and lower limits for the molecular weight of the (meth)acrylic monomer can be any combination. For example, the molecular weight of the (meth)acrylic monomer is preferably 150 to 1500, more preferably 190 to 1500, even more preferably 220 to 1000, and particularly preferably 250 to 800.

[0045] The double bond equivalent of (meth)acrylic monomer is preferably 150 g / eq or more, and more preferably 250 g / eq or more, as this improves the elastic modulus of the fiber-reinforced plastic. Furthermore, the double bond equivalent of (meth)acrylic monomer is preferably 1500 g / eq or less, and more preferably 1000 g / eq or less, as this improves compatibility with epoxy resin. The aforementioned upper and lower limits for the double bond equivalent of the (meth)acrylic monomer can be combined arbitrarily. For example, the double bond equivalent of the (meth)acrylic monomer is preferably 150 to 1500 g / eq, and more preferably 250 to 1000 g / eq.

[0046] The double bond equivalent of a (meth)acrylic monomer is calculated using the following formula, where M is the molecular weight of the (meth)acrylic monomer and D is the number of ethylenically unsaturated double bonds in the molecule. (meth)acrylic monomer double bond equivalent = M / D

[0047] In the present invention, when the matrix resin composition contains multiple (meth)acrylic monomers, the double bond equivalent of the (meth)acrylic monomer is the average value of the double bond equivalents of all (meth)acrylic monomers contained in the matrix resin composition, and can be calculated as follows. For example, let's explain the calculation method using the case where three types of (meth)acrylic monomers are used in combination. When 4 parts by mass of (meth)acrylic monomer with a double bond equivalent of D1 (g / eq), 5 parts by mass of (meth)acrylic monomer with a double bond equivalent of D2 (g / eq), and 6 parts by mass of (meth)acrylic monomer with a double bond equivalent of D3 (g / eq) are blended, the double bond equivalent can be calculated using the following formula. Double bond equivalent = (W4+W5+W6) / (W4 / D1+W5 / D2+W6 / D3)

[0048] The (meth)acrylic monomer content is preferably 5 parts by mass, more preferably 10 parts by mass or more, per 100 parts by mass of all epoxy resin contained in the matrix resin composition. Furthermore, it is preferably 40 parts by mass or less, and more preferably 35 parts by mass or less, per 100 parts by mass of epoxy resin. When the (meth)acrylic monomer content is within the above range, a sea-island structure with polymers of (meth)acrylic monomer as island phases is easily formed when the prepreg is cured, resulting in a particularly good balance of elastic modulus, toughness, and heat resistance. The above upper and lower limits for the (meth)acrylic monomer content can be combined arbitrarily. For example, the (meth)acrylic monomer content is preferably 5 to 40 parts by mass, and more preferably 10 to 35 parts by mass, per 100 parts by mass of epoxy resin. The (meth)acrylic monomer content can be determined by separation and analysis methods such as gas chromatography or liquid chromatography if it is in the prepreg state, and by pyrolysis gas chromatography if it is in the fiber-reinforced plastic state, i.e., the cured product state.

[0049] (Hardening agent) Examples of curing agents (hereinafter also referred to as "component (C)") include amine-based curing agents such as dicyandiamide, aliphatic amines, alicyclic amines, aromatic amines, ureas, and imidazoles, as well as acid anhydrides, phenols, boron chloride amine complexes, etc., but are not limited to these. Among these, dicyandiamide, aromatic amines, ureas, imidazoles, and acid anhydrides are preferred, and dicyandiamide, aromatic amines, ureas, and imidazoles are more preferred. These can be used individually or in combination of two or more types.

[0050] The curing agent content is preferably 1 part by mass, and more preferably 2 parts by mass or more, per 100 parts by mass of total epoxy resin contained in the matrix resin composition, in order to ensure sufficient curing of the epoxy resin. From the viewpoint of storage stability of the resin composition, the curing agent content is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of epoxy resin. The aforementioned upper and lower limits for the curing agent content can be combined arbitrarily. For example, the curing agent content is preferably 1 to 40 parts by mass, and more preferably 2 to 30 parts by mass, per 100 parts by mass of epoxy resin.

[0051] Since dicyandiamide has a melting point of approximately 210°C, it is incompatible with epoxy resins at low temperatures, and when used as a curing agent, it provides excellent pot life for the matrix resin composition. Commercially available dicyandiamide products include, but are not limited to, DICY7, DICY15 (both manufactured by Mitsubishi Chemical Corporation), and DICYANEX 1400F (manufactured by Evonik Japan Co., Ltd.). These can be used individually or in combination of two or more types.

[0052] The dicyandiamide content is preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass, based on 100 parts by mass of all epoxy resin contained in the matrix resin composition. If the dicyandiamide content is above the lower limit, the curing of the epoxy resin is facilitated. If the dicyandiamide content is below the upper limit, defects in the appearance of the cured product are easily suppressed. Since the heat resistance and mechanical properties of the cured resin tend to be superior, it is preferable that the number of moles of active hydrogen in dicyandiamide be 0.4 to 1 times, and more preferably 0.5 to 0.8 times, relative to the total number of moles of epoxy groups contained in all epoxy resins in the matrix resin composition.

[0053] Examples of aromatic amines include 3,3'-diisopropyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, and 3,3'-di-t-butyl-5,5'-di Examples of suitable resins include, but are not limited to, ethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraisopropyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-diisopropyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetra-t-butyl-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-methylene-bis[2-isopropyl-6-methylaniline], m-phenylenediamine, m-xylylenediamine, and diethyltoluenediamine. Among these, 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone are preferred because they yield resin cured products with excellent heat resistance and mechanical properties, as well as a low coefficient of thermal expansion and minimal decrease in heat resistance due to moisture absorption. In particular, 4,4'-diaminodiphenylsulfone is preferred because it can maintain the tack life of the prepreg for a long period of time. 3,3'-diaminodiphenylsulfone is preferred because it can increase the elastic modulus and toughness of the cured resin. Furthermore, 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone may be blended together. These can be used individually or in combination of two or more types.

[0054] The content of aromatic amines is preferably 1 to 60 parts by mass, and more preferably 2 to 50 parts by mass, based on 100 parts by mass of all epoxy resins contained in the matrix resin composition. If the content of aromatic amines is above the lower limit, the heat resistance and elastic modulus tend to be excellent. If the content of aromatic amines is below the upper limit, the toughness tends to be excellent. The number of active hydrogen equivalents of the amino groups is preferably 0.5 to 1.5 times the total epoxy equivalents of the epoxy resin contained in the matrix resin composition, and more preferably 0.6 to 1.4 times. By blending these epoxy resin curing agents so that the number of active hydrogen equivalents of the amino groups is 0.5 to 1.5 times the total epoxy equivalents of the epoxy resin, it tends to be possible to achieve good elastic modulus, toughness, and heat resistance of the cured resin.

[0055] Among aromatic amines, commercially available 4,4'-diaminodiphenyl sulfone products include, for example, Seika Cure S (active hydrogen equivalent 62 g / eq, manufactured by Wakayama Seika Kogyo Co., Ltd.) and Sumi Cure S (active hydrogen equivalent 62 g / eq, manufactured by Sumitomo Chemical Co., Ltd.), but are not limited to these. Examples of commercially available 3,3'-diaminodiphenylsulfone include, but are not limited to, 3,3'-DAS (active hydrogen equivalent 62 g / eq, manufactured by Mitsui Chemicals Fine, Inc.). Other commercially available aromatic amines include, but are not limited to, MDA-220 (active hydrogen equivalent 50 g / eq, manufactured by Mitsui Chemicals, Inc.), jER Cure W (active hydrogen equivalent 45 g / eq, manufactured by Mitsubishi Chemical Corporation), Lonzacure M-DEA (active hydrogen equivalent 78 g / eq), Lonzacure M-DIPA (active hydrogen equivalent 92 g / eq), Lonzacure M-MIPA (active hydrogen equivalent 78 g / eq), and Lonzacure DETDA 80 (active hydrogen equivalent 45 g / eq) (all manufactured by Lonza Corporation).

[0056] Urea compounds have a dimethylureide group in their molecule, and when heated at high temperatures, they generate isocyanate groups and dimethylamines, which activate epoxy groups. Examples of ureas include aromatic dimethylureas, in which a dimethylureide group is bonded to an aromatic ring, and aliphatic dimethylureas, in which a dimethylureide group is bonded to an aliphatic compound, but are not limited to these. Among these, aromatic dimethylureas are preferred because they tend to have higher heat resistance and flexural strength in the cured product. These can be used individually or in combination of two or more types.

[0057] The urea content is preferably 1 to 15 parts by mass, and more preferably 1 to 10 parts by mass, based on 100 parts by mass of all epoxy resin contained in the matrix resin composition. If the urea content is above the lower limit, it tends to accelerate the curing of the epoxy resin contained in the matrix resin composition, thereby increasing the mechanical properties and heat resistance of the cured resin product. If the urea content is below the upper limit, it tends to maintain high heat resistance and toughness of the cured resin product.

[0058] Examples of aromatic dimethylureas include phenyldimethylurea, methylenebis(phenyldimethylurea), and tolylenebis(dimethylurea). Specific examples of aromatic dimethylureas include, but are not limited to, 4,4'-methylenebis(phenyldimethylurea) (MBPDMU), 3-phenyl-1,1-dimethylurea (PDMU), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 2,4-bis(3,3-dimethylureido)toluene (TBDMU), and dimethylurea obtained from m-xylylene diisocyanate and dimethylamine. Among these, MBPDMU, PDMU, DCMU, and TBDMU are more preferred in terms of curing acceleration ability and imparting heat resistance to the cured resin. Examples of aliphatic dimethylureas include, but are not limited to, dimethylureas obtained from isophorone diisocyanate and dimethylamine, and dimethylureas obtained from hexamethylene diisocyanate and dimethylamine. These can be used individually or in combination of two or more types.

[0059] Commercially available ureas include, but are not limited to, DCMU-99 (manufactured by Hodogaya Chemical Co., Ltd.) as DCMU, Technicure MDU-11 (manufactured by A&C Catalysts Inc.); Omicure 52 (manufactured by Chori GLEX Co., Ltd.) as MBPDMU, Omicure 94 (manufactured by Chori GLEX Co., Ltd.) as PDMU, Omicure 24 (manufactured by Chori GLEX Co., Ltd.); U-CAT 3512T (manufactured by Sunapro Co., Ltd.) as TBDMU, and U-CAT 3513N (manufactured by Sunapro Co., Ltd.) as aliphatic dimethylurea.

[0060] Imidazoles have nitrogen atoms with lone pairs of electrons in their structure, which can activate epoxy groups and thus accelerate curing. Examples of imidazoles include, but are not limited to, imidazoles, imidazole adducts, inclusion-type imidazoles, microcapsule-type imidazoles, and imidazole compounds with stabilizers. These can be used individually or in combination of two or more types.

[0061] The imidazole content is preferably 1 to 15 parts by mass, and more preferably 1 to 10 parts by mass, based on 100 parts by mass of all epoxy resin contained in the matrix resin composition. If the imidazole content is above the lower limit, it tends to accelerate the curing of the epoxy resin contained in the matrix resin composition and increase the heat resistance of the cured resin product. If the imidazole content is below the upper limit, it tends to result in a cured resin product with superior mechanical properties.

[0062] Specific examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazolium trimellitate, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2,4-di Examples include, but are not limited to, amino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine, 2,4-diamino-6-(2'-undecylimidazolyl-(1'))-ethyl-s-triazine, 2,4-diamino-6-(2'-ethyl-4-methylimidazolyl-(1'))-ethyl-s-triazine, 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine isocyanurate adduct, 2-phenylimidazole isocyanurate adduct, 2-methylimidazole isocyanurate adduct, 1-cyanoethyl-2-phenyl-4,5-di(2-cyanoethoxy)methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Imidazoles treated with adducts, heteromolecular inclusion, microencapsulation, or stabilizers are modified imidazoles. These modifications reduce activity, allowing for accelerated curing while maintaining excellent pot life in low-temperature regions. These can be used individually or in combination of two or more types.

[0063] Examples of commercially available imidazoles include, but are not limited to, 2E4MZ, 2P4MZ, 2PZ-CN, C11Z-CNS, C11Z-A, 2MZA-PW, 2MAOK-PW, 2P4MHZ-PW, and 2PHZ-PW (all manufactured by Shikoku Chemicals Co., Ltd.). Examples of commercially available imidazole adducts include, but are not limited to, PN-50, PN-50J, PN-40, PN-40J, PN-31, PN-23, and PN-H (all manufactured by Ajinomoto Fine Techno Co., Ltd.), which have a structure in which an imidazole compound is ring-opened and added to the epoxy group of an epoxy resin. Examples of commercially available inclusion-conjugated imidazoles include, but are not limited to, TIC-188, KM-188, HIPA-2P4MHZ, NIPA-2P4MHZ, TEP-2E4MZ, HIPA-2E4MZ, and NIPA-2E4MZ (all manufactured by Nippon Soda Co., Ltd.). Examples of commercially available microencapsulated imidazoles include, but are not limited to, Novacure HX3721, Novacure HX3722, Novacure HX3742, and Novacure HX3748 (all manufactured by Asahi Kasei E-Materials Corporation); and LC-80 (manufactured by A&C Catalysts). Imidazole compounds with a stabilizer can be prepared, for example, by combining CureDact P-0505 (bisphenol A diglycidyl ether / 2-ethyl-4-methylimidazole adduct), an imidazole adduct manufactured by Shikoku Chemicals, Inc., with L-07N (epoxy-phenol-boric acid ester compound), a stabilizer also manufactured by Shikoku Chemicals, Inc. Similar effects can be obtained by using the various imidazole compounds and imidazole adducts mentioned above instead of CureDact P-0505.

[0064] Examples of acid anhydrides include, but are not limited to, methylnadic anhydride and methylhexahydrophthalic anhydride. These can be used individually or in combination of two or more types.

[0065] The curing agent preferably contains a curing agent having a melting point of 70°C or higher (hereinafter also referred to as "component (C1)"). The content of component (C1) is preferably 50% by mass or more, more preferably 80% by mass or more, and may be 100% by mass, relative to the total mass of component (C). If the content of component (C1) is above the lower limit, it tends to suppress the compatibility of the epoxy resin and the curing agent in the low-temperature range and suppress the immediate reaction between the epoxy resin and the curing agent. In other words, it tends to be possible to obtain a matrix resin composition with a long pot life and a prepreg with a long pot life.

[0066] (C1)Specific examples of component include dicyandiamide (melting point 208°C), 4,4'-diaminodiphenylsulfone (melting point 175°C), 3,3'-diaminodiphenylsulfone (melting point 170°C), 4,4'-methylene-bis[2-isopropyl-6-methylaniline] (melting point 72°C), 4,4'-methylenebis(phenyldimethylurea) (melting point 216°C), 3-phenyl-1,1-dimethylurea (melting point 126°C), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (melting point 159°C), 2,4-bis(3,3-dimethylureido)toluene ( Examples include, but are not limited to, 2-phenylimidazole (melting point 137°C), 2,4-diamino-6-(2'-ethyl-4-methylimidazolyl-(1'))-ethyl-s-triazine (melting point 248°C), 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine isocyanuric acid adduct (melting point 260°C or higher), 2-phenyl-4,5-dihydroxymethylimidazole (melting point 230°C or higher), and 2-phenyl-4-methyl-5-hydroxymethylimidazole (melting point 191°C).

[0067] (Thermal radical polymerization initiator) Radical polymerization initiators include thermal radical polymerization initiators, which are activated by heat, and photoradical polymerization initiators, which are activated by light irradiation. Since radicals can be generated simultaneously with the thermal curing of the epoxy resin, it is preferable to use at least a thermal radical polymerization initiator (hereinafter also referred to as "component (D)") as the radical polymerization initiator. That is, by incorporating a thermal radical polymerization initiator into the matrix resin composition, polymerization of (meth)acrylic monomers can be carried out simultaneously with the thermal curing of the epoxy resin.

[0068] The content of the thermal radical polymerization initiator is preferably 0.1 parts by mass, and more preferably 0.2 parts by mass or more, per 100 parts by mass of all (meth)acrylic monomers contained in the matrix resin composition, in order to ensure sufficient polymerization of the (meth)acrylic monomers. From the viewpoint of storage stability of the prepreg, it is preferably 10 parts by mass or less, and more preferably 9 parts by mass or less, per 100 parts by mass of (meth)acrylic monomers. The aforementioned upper and lower limits for the content of the thermal radical polymerization initiator can be combined arbitrarily. For example, the content of the thermal radical polymerization initiator is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 3 parts by mass, per 100 parts by mass of (meth)acrylic monomer.

[0069] From the viewpoint of prepreg storage stability, the 10-hour half-life temperature of the thermal radical polymerization initiator is preferably 70°C or higher, and more preferably 100°C or higher. From the viewpoint of ensuring sufficient polymerization of (meth)acrylic monomers during the curing process of the matrix resin composition, it is preferable to have a temperature of 150°C or lower. The upper and lower limits for the 10-hour half-life temperature of the thermal radical polymerization initiator can be arbitrarily combined. For example, the 10-hour half-life temperature of the thermal radical polymerization initiator is preferably 70 to 150°C, and more preferably 100 to 150°C.

[0070] Examples of thermal radical polymerization initiators include, but are not limited to, azo compounds and organic peroxides. Among these, organic peroxides (hereinafter also referred to as "component (D1)") are preferred from the viewpoint of not generating gas during thermal decomposition. The content of component (D1) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass, relative to the total mass of component (D). If the content of component (D1) is above the lower limit mentioned above, high-quality fiber-reinforced plastic with suppressed voids can be easily obtained.

[0071] Furthermore, the content of component (D1) is preferably 0.1 parts by mass, and more preferably 0.2 parts by mass or more, per 100 parts by mass of all (meth)acrylic monomers contained in the matrix resin composition, in order to allow sufficient polymerization of (meth)acrylic monomers to proceed. From the viewpoint of storage stability of the prepreg, it is preferably 10 parts by mass or less, and more preferably 9 parts by mass or less, per 100 parts by mass of (meth)acrylic monomers. The above upper and lower limits for the content of component (D1) can be combined arbitrarily. For example, the content of component (D1) is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 9 parts by mass, per 100 parts by mass of (meth)acrylic monomer.

[0072] Examples of component (D1) include, but are not limited to, diacyl peroxide, alkyl peroxyester, peroxydicarbonate, peroxyketal, dialkyl peroxide, and hydroperoxide. These can be used individually or in combination of two or more types.

[0073] (D1)Specific examples of components include ketone peroxides such as methyl ethyl ketone peroxide (110°C) and acetylacetone peroxide (130°C); 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane (95°C), 1,1-di(t-hexylperoxy)cyclohexane (87.1°C), 1,1-di(t-butylperoxy)cyclohexane (90.7°C), 2,2-di(t-butylperoxy)butane (103.1°C), and n-butyl 4,4-di(t-butylperoxy)valerate (104.5°C) Peroxyketals such as 2,2-di(4,4-di-t-butylperoxycyclohexyl)propane (94.7°C), 1,1-di(t-hexylperoxy)3,3,5-trimethylcyclohexane (86.7°C), and 1,1-di(t-butylperoxy)cyclododecane (95°C); p-menthane hydroperoxide (128°C), diisopropylbenzene hydroperoxide (145.1°C), 1,1,3,3-tetramethylbutyl hydroperoxide (152.9°C), and cumene hydroperoxide (157.9°C) Hydroperoxides such as t-butyl peroxide (166.5°C); di(2-t-butylperoxyisopropyl)benzene (119.2°C), dicumyl peroxide (116.4°C), 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (117.9°C), t-butylcumyl peroxide (119.5°C), di-t-hexyl peroxide (116.4°C), di-t-butyl peroxide (123.7°C), 2,5-dimethyl-2,5-di(t-butylperoxy)hexyn-3 (128.4°C) Dialkyl peroxides such as diisobutyryl peroxide (32.7°C), di(3,5,5-trimethylhexanoyl) peroxide (59.4°C), lauroyl peroxide (61.6°C), disuccinate peroxide (65.9°C), m-toluyl peroxide (73.1°C), dibenzoyl peroxide (73.6°C), dioctanoyl peroxide (63°C), etc.; di-n-propyl peroxydicarbonate (40.3°C), diisopropyl peroxydicarbonate (40.Peroxydicarbonates such as di(4-t-butylcyclohexyl)peroxydicarbonate (40.8°C), di(2-ethylhexyl)peroxydicarbonate (43.6°C), di-sec-butylperoxydicarbonate (40.5°C), di(3-methoxybutyl)peroxydicarbonate (43°C); cumylperoxyneodecanoate (36.5°C), 1,1,3,3-tetramethylbutylperoxyneodecanoate (4 (0.7℃), t-hexyl peroxyneodecanoate (44.5℃), t-butyl peroxyneodecanoate (46.4℃), t-hexyl peroxypivalate (53.2℃), t-butyl peroxypivalate (54.6℃), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (65.3℃), 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane (66.2℃), t-hexyl peroxy -2-ethylhexanoate (69.9°C), t-butylperoxy-2-ethylhexanoate (72.1°C), t-hexylperoxyisopropyl monocarbonate (95°C), t-butylperoxy-3,5,5-trimethylhexanoate (97.1°C), t-butylperoxylaurate (98.3°C), t-butylperoxyisopropyl monocarbonate (98.7°C), t-butylperoxy-2-ethylhexyl monocarbonate Examples of peroxyesters include, but are not limited to, peroxyesters such as t-hexyl peroxybenzoate (99.4°C), 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (99.7°C), t-butyl peroxyacetate (101.9°C), t-butyl peroxybenzoate (104.3°C), t-butyl peroxymalic acid (96.1°C), and t-butyl peroxyisobutyrate (75°C). The values ​​in parentheses represent the 10-hour half-life temperature. These can be used individually or in combination of two or more types.

[0074] (thermoplastic resin) Examples of thermoplastic resins (hereinafter also referred to as "component (E)") include, but are not limited to, polyamide, polyester, polycarbonate, polyethersulfone, polyphenylene ether, polyphenylene sulfide, polyetherether ketone, polyetherketone, polyimide, polytetrafluoroethylene, polyether, polyolefin, liquid crystal polymer, polyarylate, polysulfone, polyacrylonitrile styrene, polystyrene, polyacrylonitrile, polymethyl methacrylate, ABS (acrylonitrile-butadiene-styrene copolymer), AES (acrylonitrile-ethylene propylene rubber-styrene copolymer), ASA (acrylonitrile-acrylic rubber-styrene copolymer), polyvinyl chloride, polyvinyl formal, polyvinyl butyral, phenoxy resin, block copolymer, etc. Among these, polyvinyl formal, polyvinyl butyral, polyethersulfone, and phenoxy resin are preferred due to their excellent solubility in epoxy resins and resin flow control properties. Among these, polyvinyl formal is particularly preferred because it exhibits excellent resin flow control even in small amounts. These can be used individually or in combination of two or more types.

[0075] The thermoplastic resin content tends to exhibit good resin flow controllability, so it is preferably 1 part by mass, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of total epoxy resin contained in the matrix resin composition. From the viewpoint of minimizing the viscosity increase of the matrix resin composition, it is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 6 parts by mass or less, per 100 parts by mass of epoxy resin. The aforementioned upper and lower limits for the thermoplastic resin content can be combined arbitrarily. For example, the thermoplastic resin content is preferably 1 to 30 parts by mass, more preferably 2 to 10 parts by mass, and even more preferably 3 to 6 parts by mass, per 100 parts by mass of epoxy resin.

[0076] (optional ingredient) Optional components include, but are not limited to, epoxy resin curing accelerators, phosphorus-based flame retardants (e.g., phosphorus-containing epoxy resins, red phosphorus, phosphazene compounds, phosphates, phosphate esters, etc.), inorganic flame retardants (e.g., aluminum hydroxide, magnesium hydroxide, etc.), mold release agents (e.g., natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters, paraffins, etc.), inorganic fillers (e.g., powders such as crystalline silica, fused silica, calcium silicate, alumina, calcium carbonate, talc, barium sulfate, etc., or fibers such as glass fibers, carbon fibers, etc.), colorants (e.g., carbon black, red iron oxide, etc.), organic pigments, inorganic pigments, silane coupling agents, silicone oils, wetting and dispersing agents, defoaming agents, defoaming agents, inorganic oxides, or other auxiliary agents (e.g., antimony compounds, zinc borate, zinc stainate, Mo compounds, ZrO, zinc sulfide, zeolites, titanium dioxide nanofiller systems, etc.). These can be used individually or in combination of two or more types.

[0077] Furthermore, optional components such as oligomers or prepolymers having radically polymerizable double bonds may be used. Examples of oligomers or prepolymers include, but are not limited to, macromonomers, acrylic acrylates, epoxy acrylates, urethane acrylates, and polyester acrylates. These can be used individually or in combination of two or more types.

[0078] (Method for manufacturing matrix resin composition) The matrix resin composition is obtained by heating and mixing the components described above. Methods for mixing the components include, but are not limited to, using mixing equipment such as a three-roll mill, planetary mixer, kneader, homogenizer, or homodisper.

[0079] <Reinforced Fiber> The reinforcing fibers can be present in the prepreg as a reinforcing fiber substrate (an aggregate of reinforcing fibers), and are preferably in sheet form. The orientation of the fibers in the reinforcing fiber substrate may be such that the reinforcing fibers are arranged in a single direction or in a random direction. Examples of reinforcing fiber base materials include, but are not limited to, woven fabrics of reinforcing fibers, nonwoven fabrics of reinforcing fibers, and sheets in which long reinforcing fibers are aligned in one direction. From the viewpoint of being able to mold fiber-reinforced plastics with high specific strength and specific modulus, it is preferable to use a sheet consisting of bundles of reinforcing fibers in which continuous fibers are aligned in a single direction as the prepreg. From the viewpoint of ease of handling, it is preferable to use woven fabrics of reinforcing fibers as the prepreg. The basis weight of the reinforcing fiber base material is not particularly limited, but for example, 10 to 4000 g / m² 2 It can be done this way.

[0080] Examples of reinforcing fibers include, but are not limited to, glass fibers, carbon fibers, aramid fibers, nylon fibers, high-strength polyester fibers, boron fibers, alumina fibers, and silicon nitride fibers. Among these, carbon fibers are preferred as reinforcing fibers from the viewpoint of improving the mechanical properties of the resulting fiber-reinforced plastic and reducing its weight.

[0081] The fiber diameter of the carbon fiber is preferably 3 to 12 μm. The tensile strength of the carbon fiber strands is preferably 1.5 to 9 GPa. Furthermore, the tensile modulus of the carbon fiber strands is preferably 150 to 400 GPa. If both the tensile strength and tensile modulus of the carbon fiber strands are within the above ranges, the rigidity of the resulting fiber-reinforced plastic will be increased. Here, the strand tensile strength and strand tensile modulus of carbon fiber are values ​​measured in accordance with JIS R 7601:1986, respectively.

[0082] It is preferable to use carbon fibers as carbon fiber bundles, which are bundles of multiple carbon fibers together. Alternatively, a sheet-like reinforcing fiber base material may be made by using multiple carbon fiber bundles and aligning the fibers in one direction, or a sheet-like reinforcing fiber base material may be made by scattering chopped carbon fiber bundles, which are obtained by chopping carbon fiber bundles. The number of carbon fibers in a carbon fiber bundle is preferably between 1,000 and 70,000.

[0083] <Prepreg manufacturing method> A prepreg can be obtained, for example, by impregnating a reinforcing fiber substrate with a matrix resin composition. Methods for impregnating a reinforcing fiber substrate with a matrix resin composition include, but are not limited to, a wet method in which the matrix resin composition is dissolved in a solvent such as methyl ethyl ketone or methanol to reduce its viscosity before being impregnated into the reinforcing fiber substrate; and a hot melt method (dry method) in which the matrix resin composition is heated to reduce its viscosity before being impregnated into the reinforcing fiber substrate. The impregnation temperature of the matrix resin composition into the reinforcing fiber substrate is set according to the viscosity of the matrix resin composition. However, from the viewpoint of ensuring that the curing reaction of the matrix resin composition does not begin and that the matrix resin composition is sufficiently impregnated into the reinforcing fiber substrate, a temperature of 40 to 120°C is preferred, and 50 to 110°C is more preferred.

[0084] The wet method involves immersing a reinforcing fiber substrate in a solution of a matrix resin composition, then removing it and evaporating the solvent using an oven or the like. The hot melt method includes a method in which a matrix resin composition, whose viscosity has been reduced by heating, is directly impregnated into a reinforcing fiber substrate; and a method in which the matrix resin composition is first applied to the surface of a substrate such as release paper to create a resin film, and then the resin film is placed on both sides or one side of the reinforcing fiber substrate, and the matrix resin composition is impregnated into the reinforcing fiber substrate by heating and pressurizing. The coating layer obtained by applying the matrix resin composition to the surface of a substrate such as release paper may be used in the hot melt method while still uncured, or it may be used in the hot melt method after the coating layer has been cured. From the viewpoint of substantially eliminating residual solvent in the prepreg, it is preferable to manufacture the prepreg by the hot-melt method.

[0085] The content of the matrix resin composition in the prepreg (hereinafter also referred to as "resin content") is preferably 15 to 50% by mass, more preferably 15 to 45% by mass, and even more preferably 15 to 40% by mass, relative to the total mass of the prepreg. If the resin content is above the lower limit, sufficient adhesion between the reinforcing fibers and the matrix resin composition can be ensured. If the resin content is below the upper limit, the mechanical properties of the fiber-reinforced plastic are further enhanced.

[0086] The fiber content in the prepreg (hereinafter also referred to as "fiber content") is preferably 40 to 80% by volume, more preferably 45 to 80% by volume, and even more preferably 50 to 80% by volume, relative to the total volume of the prepreg. If the fiber content is above the lower limit, the mechanical properties of the fiber-reinforced plastic are further enhanced. If the fiber content is below the upper limit, sufficient adhesion between the reinforcing fibers and the matrix resin composition can be ensured.

[0087] <Effects and Effects> As described above, the prepreg of this embodiment includes a matrix resin composition containing epoxy resin and (meth)acrylic monomer blended in a specific ratio R, and reinforcing fibers. This improves the adhesive strength between the reinforcing fibers and the matrix resin composition, making it possible to obtain a fiber-reinforced plastic with improved toughness while maintaining strength and elastic modulus.

[0088] <Application> The prepreg of this embodiment is suitable as an intermediate material for fiber-reinforced plastics.

[0089] [Fiber-reinforced plastic] A fiber-reinforced plastic according to a second aspect of the present invention is obtained by curing the prepreg according to the first aspect of the present invention described above. That is, the fiber-reinforced plastic includes a cured product of the matrix resin composition contained in the prepreg and reinforcing fibers. When the prepreg of the first embodiment of the present invention is heated, the epoxy resin contained in the matrix resin composition hardens, and at the same time, radical polymerization of the (meth)acrylic monomer proceeds. At this time, if the matrix resin composition contains a curing agent, the hardening reaction of the epoxy resin is accelerated. Furthermore, if the matrix resin composition contains a thermal radical polymerization initiator, the thermal radical polymerization initiator cleaves and generates free radicals, thereby accelerating the radical polymerization reaction of the (meth)acrylic monomer. Therefore, the cured product of the matrix resin composition is composed of the cured epoxy resin and the (meth)acrylic polymer.

[0090] Fiber-reinforced plastics can be, for example, cured laminates made by stacking two or more prepregs. Specifically, after stacking two or more prepregs, molded articles made of fiber-reinforced plastics can be obtained by molding the resulting laminate by applying pressure and heat curing, etc. When laminating two or more prepregs, all prepregs may be prepregs according to the first aspect of the present invention, or a combination of a prepreg according to the first aspect of the present invention and a prepreg other than the prepreg according to the first aspect of the present invention (hereinafter also referred to as "other prepregs"). Other prepregs include, but are not limited to, prepregs containing a thermoplastic resin composition and reinforcing fibers, and prepregs containing an epoxy resin composition and reinforcing fibers.

[0091] Examples of molding methods include, but are not limited to, press molding, autoclave molding, bagging molding, wrapping tape method, internal pressure molding, sheet wrap molding, RTM (Resin Transfer Molding), VaRTM (Vacuum assisted Resin Transfer Molding), filament winding, and RFI (Resin Film Infusion), which involve impregnating reinforcing fiber filaments or preforms with a matrix resin composition and curing to obtain molded products. Among these, autoclave molding is preferred from the viewpoint of easily obtaining high-quality fiber-reinforced plastics, and press molding is preferred from the viewpoint of obtaining high productivity.

[0092] When manufacturing fiber-reinforced plastics by press molding, it is preferable to heat and pressurize a prepreg or preform made by laminating prepregs in a mold that has been pre-adjusted to a curing temperature, thereby curing the prepreg or preform. The temperature inside the mold during press molding is preferably 100 to 180°C. Furthermore, it is preferable to cure the prepreg or preform for 1 to 20 minutes under conditions of 1 to 15 MPa.

[0093] <Effects and Effects> As described above, the fiber-reinforced plastic of this embodiment is obtained by curing the prepreg of the first aspect of the present invention, and the adhesive strength between the reinforcing fibers and the matrix resin composition is improved, and toughness is improved while maintaining strength and elastic modulus, resulting in high strength and elastic modulus.

[0094] <Application> The fiber-reinforced plastic of this embodiment can be used in a wide range of applications, such as automotive components; aerospace materials; civil engineering and construction materials; sports and leisure materials such as fishing rods, golf shafts, and rackets; pressure vessels; and industrial materials such as wind turbine blades. [Examples]

[0095] The present invention will be specifically described below with reference to examples, but the present invention is not limited by the following description unless it exceeds the gist of the invention. The raw materials used in the examples and comparative examples are shown below.

[0096] [Raw materials] <(A) Component: Epoxy resin> • MY0600: Triglycidyl-m-aminophenol (manufactured by Huntsman Japan Co., Ltd., product name "MY0600", epoxy equivalent 106g / eq). jER604: Tetraglycidylamine type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER 604", epoxy equivalent 120g / eq). • N-660: Epoxy resin with a solid novolac-type skeleton (manufactured by DIC Corporation, product name "EPICLON N-660", epoxy equivalent 207 g / eq). • N-690: Epoxy resin with a solid novolac-type skeleton (manufactured by DIC Corporation, product name "EPICLON N-690", epoxy equivalent 214 g / eq). jER4005P: Solid bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER 4005P", epoxy equivalent 1075g / eq). jER4007P: Solid bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER 4007P", epoxy equivalent 2250 g / eq). jER807: Liquid bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER 807", epoxy equivalent 167.5 g / eq). • TSR-400: Epoxy resin with a solid oxazolidone ring skeleton (manufactured by DIC Corporation, product name "EPICLON TSR-400", epoxy equivalent 338 g / eq).

[0097] <(B) Component: (meth)acrylic monomer> · A-BPE-4: Ethoxylated bisphenol A diacrylate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "New Frontier A-BPE-4", molecular weight: 512, bifunctional, double bond equivalent 256 g / eq, in general formula (2), R4 and R 5 is a hydrogen atom, and R 6 is a divalent organic group represented by general formula (3), and R in general formula (3) 7 and R 8 is an ethylene group, R 9 and R 10 (2) A monomer in which the methyl group is and m+n is 4. • AMP-20GY: Phenoxydiethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., product name "AMP-20GY", molecular weight: 236, monofunctional, double bond equivalent 236 g / eq, in general formula (1), R 1 is a hydrogen atom, and R 2 is an ethylene group, R 3 A monomer (1) in which p is an integer of 2, where p is a phenyl group. • FA-314A: Nonylphenoxypolyethylene glycol acrylate (manufactured by Showa Denko Materials Co., Ltd., product name "Funkril FA-314A", molecular weight 452, monofunctional, double bond equivalent 452 g / eq, in general formula (1), R 1 is a hydrogen atom, and R 2 is an ethylene group, R 3 (1) is a monomer (1) in which p is an integer of 4, where p is a phenyl group having a nonyl group (nonylphenyl group). ·FA-512AS: Dicyclopentenyloxyethyl acrylate (manufactured by Showa Denko Materials Co., Ltd., product name "Funkril FA-512AS", molecular weight 248, monofunctional, double bond equivalent 248 g / eq, in general formula (1), R 1 is a hydrogen atom, and R 2 is an ethylene group, R 3 (1) is a monomer in which p is an integer of 1, where p is a dicyclopentenyl group. · A-LEN-10: Ethoxylated-o-phenylphenol acrylate (Shin-Nakamura Chemical Industry Co., Ltd., product name "A-LEN-10", molecular weight 268, monofunctional, double bond equivalent 268 g / eq, in general formula (1), R 1 is a hydrogen atom, and R 2 is an ethylene group, R 3 (1) is a biphenyl group and a monomer in which p is an integer of 1. · A-NOD-N: 1,9-nonanediol diacrylate (Shin-Nakamura Chemical Industry Co., Ltd., product name "A-NOD-N", molecular weight 268, bifunctional, double bond equivalent 134 g / eq, in general formula (2), R 4 and R 5 is a hydrogen atom, and R 6 (2) is a monomer that is a linear alkylene group with 9 carbon atoms.

[0098] <(C) Ingredients: Hardener> • DICYANEX 1400F: Dicyandiamide (manufactured by Evonik Japan Co., Ltd., product name "DICYANEX 1400F", active hydrogen equivalent 21g / eq, melting point 208℃). Omicure94: 3-phenyl-1,1-dimethylurea (Chori GLEX Co., Ltd., product name "Omicure94", active hydrogen equivalent 164 g / eq, melting point 126°C).

[0099] <(D) Component: Thermal radical polymerization initiator> • PERCUMYL D: Dicumyl peroxide (manufactured by NOF Corporation, product name "Percumyl D", half-life temperature at 10 hours: 116.4°C).

[0100] <(E) Component: Thermoplastic resin> • VINYLEC K: Polyvinyl formal resin (manufactured by JNC Corporation, product name "VINYLEC K"). • VINYLEC E: Polyvinyl formal resin (manufactured by JNC Corporation, product name "VINYLEC E").

[0101] [Example 1] <Preparation of Matrix Resin Composition> First, according to the composition shown in Table 1, component (C) and a portion of the liquid epoxy resin from component (A) were weighed into a container in a mass ratio of 1:1 and mixed by stirring. This mixture was then further finely mixed using a three-roll mill to obtain a masterbatch containing the curing agent. Next, according to the composition shown in Table 1, components (A) and (E), excluding those used in the masterbatch containing the curing agent, were weighed into a flask and heated and stirred at 140°C using an oil bath. After dissolving and mixing component (E), the mixture was cooled to 80°C. Subsequently, component (B) was added and stirred to obtain a uniform viscosity solution, which was then cooled to approximately 65°C. Subsequently, the masterbatch containing the curing agent prepared earlier and component (D) were added and stirred to obtain an uncured matrix resin composition. Note that blank spaces in the table indicate that the ingredient is not included (amount: 0 parts by mass).

[0102] <Preparation of cured products (resin plates) of matrix resin compositions> The uncured matrix resin composition was degassed in a vacuum at 60-70°C, then injected between two glass plates to form a plate, and heated and cured by increasing the temperature at 2°C / min and holding it at an oven atmosphere temperature of 150°C for 120 minutes to produce a cured product (resin plate) with a thickness of 2.0 mm.

[0103] <Prepreg fabrication> On the release paper, the uncured matrix resin composition was formed into a film using a comma coater (manufactured by Hirano Texseed Co., Ltd., product name "R-HC"), and a resin basis of 26.8 g / m² was applied to the release paper. 2 A resin film was prepared, and a 17μm thick polyethylene protective film was attached to the side without the release paper. After peeling the release paper from the resin film, carbon fibers (fiber diameter 7 μm, strand tensile strength 4.9 GPa, strand tensile modulus 235 GPa) were aligned to obtain a fiber basis weight of 125 g / m². 2 A resin film was laminated to both sides of a carbon fiber sheet so that the sides with the release paper removed were in contact with each other, and the film was impregnated with a heated roll to obtain an uncured unidirectional prepreg with a resin content of 30% by mass and a fiber content of 62% by volume.

[0104] <Fabrication of fiber-reinforced plastic sheets> Uncured prepreg was cut into 300mm x 300mm pieces, and 18 pieces were stacked with the fiber direction aligned to obtain a laminate. This laminate was heated in an autoclave at a pressure of 0.6 MPa at a rate of 2°C / min, and held at 150°C for 120 minutes to heat-cur it, obtaining a 2.0 mm thick fiber-reinforced plastic sheet. The obtained resin plates and reinforced fiber plastic plates were evaluated according to the evaluation methods described below. The results are shown in Tables 1 and 2.

[0105] <Rating> (Evaluation of the mechanical properties of resin sheets (flexural strength, flexural modulus, fracture toughness)) A 2.0 mm thick resin plate was processed into a 60 mm long x 8 mm wide specimen to prepare a test piece. The resulting test piece was subjected to a crosshead speed of 2 mm / min on a universal testing machine (INSTRON 5965) equipped with a three-point bending jig (indenter R=3.2 mm, support R=3.2 mm, support distance (L)=32 mm) under conditions of 23°C and 50% RH, to measure the bending strength and flexural modulus of the resin plate. Specifically, the flexural modulus (unit: GPa) was calculated using the secant method in the range of bending strain from 0.05 to 0.25% using the stress-strain curve obtained under the above measurement conditions. Separately, the fracture toughness value (KIc) of a 3.0 mm thick resin plate was measured in accordance with the SENB method specified in ASTM D5045.

[0106] (Evaluation of the 90° bending properties (90° bending strength, 90° bending modulus, fracture strain) of fiber-reinforced plastic sheets) A 2.0 mm thick fiber-reinforced plastic sheet was processed into a 60 mm long x 12.7 mm wide specimen. The obtained specimens were tested using a universal testing machine (INSTRON 5965, manufactured by INSTRON Corporation) equipped with a three-point bending jig (indenter R=5.0 mm, support R=3.2 mm) at a temperature of 23°C and a humidity of 50% RH. The ratio of the distance between supports (L) to the thickness of the specimen (d) L / d = 16, and the crosshead speed (meters per minute) = (L² × 0.01) / (6 × d). The 90° bending strength, 90° bending modulus, and fracture strain of the fiber-reinforced plastic sheet were measured.

[0107] [Examples 2-4] A matrix resin composition was prepared in the same manner as in Example 1, except that the compounding composition was changed to that shown in Table 1. A resin plate was fabricated and evaluated in the same manner as in Example 1, except that the obtained matrix resin composition was used. The results are shown in Table 1.

[0108] [Example 5] A matrix resin composition was prepared in the same manner as in Example 1, except that the compounding composition was changed to that shown in Table 1. Resin plates, prepregs, and fiber-reinforced plastic plates were manufactured and evaluated in the same manner as in Example 1, except that the obtained matrix resin composition was used. The results are shown in Tables 1 and 2.

[0109] [Comparative Examples 1-3] A matrix resin composition was prepared in the same manner as in Example 1, except that the compounding composition was changed to that shown in Table 1. A resin plate was fabricated and evaluated in the same manner as in Example 1, except that the obtained matrix resin composition was used. The results are shown in Table 1.

[0110] [Comparative Example 4] A matrix resin composition was prepared in the same manner as in Example 1, except that the compounding composition was changed to that shown in Table 1. A prepreg and a fiber-reinforced plastic sheet were prepared and evaluated in the same manner as in Example 1, except that the obtained matrix resin composition was used. The results are shown in Table 2.

[0111] [Table 1]

[0112] [Table 2]

[0113] As is clear from the results shown in Table 1, the resin sheets obtained in Examples 1 to 5 exhibited an excellent balance of flexural strength, flexural modulus, and fracture toughness. The flexural strength and flexural modulus of the resin sheets remained at 85% or higher compared to the case without (meth)acrylic monomer, while fracture toughness improved. Furthermore, as is clear from the results shown in Table 2, the fiber-reinforced plastic sheets obtained in Examples 1 and 5 exhibited an excellent balance of 90° bending strength, 90° bending modulus, and fracture strain. On the other hand, the resin plate obtained in Comparative Example 1, which did not use component (B), had lower fracture toughness compared to Examples 1-5. The resin plates obtained in Comparative Examples 2 and 3, where the ratio R was less than 1.0, had lower bending strength compared to Examples 1-5. In particular, the resin plate obtained in Comparative Example 2 also had lower fracture toughness compared to Examples 1-5. The fiber-reinforced plastic sheet obtained in Comparative Example 4, which did not use component (B), had lower 90° bending strength and 90° bending modulus compared to Examples 1 and 5. These results demonstrate that the prepregs obtained in Examples 1-5 can be used to obtain fiber-reinforced plastics with improved toughness while maintaining strength and elastic modulus. [Industrial applicability]

[0114] By using the prepreg of the present invention, it is possible to obtain fiber-reinforced plastics with improved strength and elastic modulus while maintaining toughness. Therefore, according to the present invention, fiber-reinforced plastic molded articles with excellent mechanical properties can be widely applied, from molded articles for sports and leisure use such as fishing rods, golf shafts, and rackets, to molded articles for industrial use such as aircraft and automobiles.

Claims

1. A prepreg comprising a matrix resin composition and reinforcing fibers, The matrix resin composition comprises an epoxy resin and a (meth)acrylic monomer. The ratio R (double bond equivalent / epoxy equivalent) of the double bond equivalent of the (meth)acrylic monomer to the epoxy equivalent of the epoxy resin is 1.0 or greater. The matrix resin composition further comprises a curing agent and a thermal radical polymerization initiator. A prepreg comprising at least one curing agent selected from the group consisting of dicyandiamide, aromatic amines, ureas, and imidazoles.

2. The prepreg according to claim 1, wherein the epoxy resin comprises at least one selected from the group consisting of novolac-type epoxy resins and trifunctional or more amine-type epoxy resins.

3. The prepreg according to claim 1 or 2, wherein the epoxy equivalent of the epoxy resin is 150 g / eq or more.

4. The prepreg according to claim 1 or 2, wherein the epoxy equivalent of the epoxy resin is 250 g / eq or less.

5. The prepreg according to claim 1 or 2, wherein the double bond equivalent of the (meth)acrylic monomer is 150 g / eq or more.

6. The prepreg according to claim 1 or 2, wherein the double bond equivalent of the (meth)acrylic monomer is 1500 g / eq or less.

7. The prepreg according to claim 1 or 2, wherein the (meth)acrylic monomer comprises at least one selected from the group consisting of monofunctional (meth)acrylic monomers with a molecular weight of 150 or more and bifunctional (meth)acrylic monomers with a molecular weight of 150 or more.

8. The prepreg according to claim 1 or 2, wherein the (meth)acrylic monomer comprises at least one selected from the group consisting of monofunctional (meth)acrylic monomers represented by the following general formula (1) and bifunctional (meth)acrylic monomers represented by the following general formula (2). 【Chemistry 1】 In general formula (1), R １ R is a hydrogen atom or a methyl group, ２ R is an alkylene group having 2 to 6 carbon atoms. ３ p is an aromatic hydrocarbon group or an alicyclic hydrocarbon group, and p is an integer of 1 or more. In general formula (2), R ４ and R ５ Each is independently a hydrogen atom or a methyl group, R ６ It is a divalent organic group with 2 to 55 carbon atoms.

9. The R in the general formula (1) ２ is an alkylene group having 2 to 6 carbon atoms, and the R ３ The prepreg according to claim 8, wherein is a phenyl group, a biphenyl group, or a dicyclopentenyl group, and p is an integer from 1 to 10.

10. The R in the general formula (2) ６ is an alkylene group having 2 to 15 carbon atoms or a divalent organic group having 6 to 55 carbon atoms and having a cyclic structure, and the prepreg according to claim 8.

11. The prepreg according to claim 10, wherein the divalent organic group having 6 to 55 carbon atoms and having the cyclic structure is a divalent organic group represented by the following general formula (3). 【Chemistry 2】 In general formula (3), R ７ and R ８ Each of these is an alkylene group having 2 to 6 carbon atoms, and R ９ and R １０ Each of these is independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m and n are independently integers of 1 or more.

12. The prepreg according to claim 1, wherein the thermal radical polymerization initiator comprises an organic peroxide.

13. The prepreg according to claim 1 or 12, wherein the 10-hour half-life temperature of the thermal radical polymerization initiator is 70°C or higher.

14. The prepreg according to claim 1 or 2, wherein the matrix resin composition further comprises a thermoplastic resin.

15. The prepreg according to claim 14, wherein the thermoplastic resin comprises at least one selected from the group consisting of polyvinyl formal, polyvinyl butyral, polyethersulfone, and phenoxy resin.

16. The prepreg according to claim 1 or 2, wherein the matrix resin composition contains 5 to 40 parts by mass of the (meth)acrylic monomer per 100 parts by mass of the epoxy resin.

17. The prepreg according to claim 1 or 12, wherein the matrix resin composition contains 0.1 to 5 parts by mass of the thermal radical polymerization initiator per 100 parts by mass of the (meth)acrylic monomer.

18. A fiber-reinforced plastic obtained by curing the prepreg according to claim 1 or 2.

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