JP7082496B2 - A resin composition for fiber reinforced plastics, a cured product thereof, and a fiber reinforced plastic containing the cured product. - Google Patents

Description

The present invention relates to a resin composition for fiber reinforced plastics. More specifically, by using a flexible epoxy resin as a part of the epoxy resin contained in the resin composition for fiber reinforced plastic, the workability is good and the flexibility is maintained while maintaining a high elasticity. The present invention relates to a resin composition for fiber reinforced plastic, which can obtain a cured product having excellent properties.

A method for producing a molded product by using a thermosetting epoxy resin, unsaturated polyester, polyamide resin, or phenol resin as a reinforcing material for a fiber material such as carbon fiber or glass fiber is well known. Fiber reinforced plastics using this method are widely used as materials for structures such as aircraft and ships, and sports equipment such as tennis rackets and golf clubs. Epoxy resin is often used as a reinforcing material as a well-balanced material because it is not only excellent in adhesiveness, heat resistance, and chemical resistance but also inexpensive.

It is known that a fiber material and a fiber reinforced plastic using an epoxy resin as a reinforcing material have higher strengths that the fiber material and the epoxy resin do not have by themselves. When a cyanic acid ester is further added, a rigid and highly heat-resistant fiber-reinforced plastic can be obtained by forming a triazine ring during curing.

Fiber reinforced plastics used in structures such as automobiles and aircraft, and industrial equipment such as high-pressure gas tanks and blades for wind power generation are required to have high strength and high heat resistance, but sudden external force is required. When added, characteristics such as impact resistance have been required so as not to be damaged by impact.

In Patent Document 1, as a matrix resin for fiber reinforced plastics, a polyfunctional maleimide, a polyfunctional cyanate ester, and an epoxy resin are cured with diaminodiphenyl sulfone to have excellent storage stability and high heat resistance. We provide prepregs and fiber reinforced composite materials. Although this method has no problem in terms of workability such as moldability and high heat resistance, it is used for the above-mentioned structures such as automobiles and aircraft, and industrial equipment such as high-pressure gas tanks and blades for wind power generation. In, it was not possible to obtain a cured product that was satisfactory in terms of impact resistance.

In Patent Document 2, a composition using a rubber-modified epoxy resin as a resin composition for a fiber-reinforced composite material and an acid anhydride as a curing agent is used to reinforce the fibers with excellent fiber orientation and vertical tensile strength. We provide composite materials. Although the pressure vessels obtained from these materials have some physical characteristics and impact resistance, it is possible to obtain a cured product having performance sufficient to meet the market demand in terms of heat resistance and Tg. There wasn't.

Japanese Unexamined Patent Publication No. 2009-013254 Japanese Unexamined Patent Publication No. 2015-078302

Generally, a cured product or molded product having a high elastic modulus obtained by using an epoxy resin has a high Tg and becomes hard and brittle, and as a result, stress relaxation is poor and tends to be damaged by an external impact or the like. be. In order to improve the impact resistance of cured products and molded products, physical properties that follow external stress are required, and one of the solutions is to provide flexibility. The problem to be solved by the present invention is to obtain a cured product having good workability, high elastic modulus in tensile and bending physical properties, good heat resistance, and excellent flexibility. It is an object of the present invention to provide a resin composition which can be obtained, and a fiber reinforced plastic obtained by using the composition.

Therefore, in order to solve the above-mentioned problems, the present inventors have diligently studied, and a resin composition containing a cyanate ester, an epoxy resin containing a specific flexible epoxy resin, and an aromatic amine-based curing agent liquid at 25 ° C. He found a thing and came up with the present invention. That is, the present invention contains A) a cyanate ester, (B) an epoxy resin, and (C) an aromatic amine-based curing agent that is liquid at 25 ° C., and (B) 1 to 35% by mass of the total amount of the epoxy resin. A resin composition for fiber-reinforced plastic, which is a flexible epoxy resin.

The effect of the present invention is that it is possible to obtain a cured product having good workability, high elastic modulus in tensile and bending physical properties, good heat resistance, and excellent flexibility. The resin composition is provided. Fiber reinforced plastics using the resin composition are particularly used for transportation equipment such as automobiles, aircraft and ships, industrial equipment such as chemical plants, chemical tanks and blades for wind power generation, and building materials such as roofs, road signs and bridges. It is a material suitable for applications that require high strength, high heat resistance, impact resistance, and the like.

Hereinafter, embodiments of the resin composition for fiber reinforced plastics of the present invention will be described.
[(A) Cyanic acid ester]
The (A) cyanic acid ester used in the present invention is not particularly limited and may be appropriately selected from known cyanic acid esters. The molecular structure, molecular weight, and the like of the (A) cyanic acid ester used in the present invention are not particularly limited and can be appropriately selected. Specifically, bisphenol type cyanate such as bisphenol A type cyanate, bisphenol F type cyanate, and bisphenol E type cyanate, and phenol novolac type cyanate can be exemplified. In the present invention, the cyanate ester (A) preferably has at least two cyanate groups (OCN) in the molecule, and is a compound represented by the following general formulas (1-1) and (1-2). In addition, it is more preferable to use these prepolymers.

(In the general formula (1-1), R ^a represents a single bond, —S— or a divalent hydrocarbon group, and R ^b and R ^c are independently, unsubstituted or 1 to 4 alkyl, respectively. Represents a phenylene group substituted with a group, where R ^b and R ^c are substituted with 2-4 alkyl groups, the alkyl groups may be the same or different).

(In the general formula (1-2), n represents an integer of 1 to 10, and R ^d represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

The divalent hydrocarbon group represented by Ra in the general formula (1-1) includes an alkylene group having 1 to 8 carbon atoms, ^a cycloalkylene group having 3 to 13 carbon atoms, and 6 to 6 carbon atoms. Twelve arylene groups, arylene alkylene groups having 7 to 12 carbon atoms, allylene alkylene groups having 8 to 12 carbon atoms, and the following general formulas (2-1) to (2-3) and (2-5) to Examples thereof include functional groups represented by (2-8).
Examples of the alkylene group having 1 to 8 carbon atoms include methylene, ethylene, propylene, methylethylene, butylene, 1-methylpropylene, 2-methylpropylene, 1,2-dimethylpropylene, 1,3-dimethylpropylene and 1-methyl. Butylene, 2-methylbutylene, 3-methylbutylene, 4-methylbutylene, 2,4-dimethylbutylene, 1,3-dimethylbutylene, pentylene, hexylene, heptylene, octylene, ethane-1,1-diyl, propane- 2,2-Gil and the like can be mentioned.
Examples of the cycloalkylene group having 3 to 13 carbon atoms include a 1,2-cyclopropylene group, a 1,3-cycloheptylene group, a trans-1,4-cyclohexylene group and the like.
Examples of the arylene group having 6 to 12 carbon atoms include phenylene, trilene, and naphthylene.
Examples of the arylene alkylene group having 7 to 12 carbon atoms include phenylene methylene and phenylene ethylene.
Examples of the allylene alkylene group having 8 to 12 carbon atoms include phenylenedimethylene and phenylenediethylene.
The methylene chains in the alkylene group having 1 to 8 carbon atoms, the arylene alkylene group having 7 to 12 carbon atoms, and the allylene alkylene group having 8 to 12 carbon atoms are -O-, -S-, and -CO-. Or it may be replaced with -C = C-. In that case, the methylene group is replaced with -COO- or the like in the alkylene group having 1 to 8 carbon atoms, the arylene alkylene group having 7 to 12 carbon atoms, and the allylene alkylene group having 8 to 12 carbon atoms. It refers to the number of carbon atoms after that, and does not refer to the number of carbon atoms before the methylene group is replaced with -COO- or the like.
The alkylene group having 1 to 8 carbon atoms, the arylene group having 6 to 12 carbon atoms, the arylene alkylene group having 7 to 12 carbon atoms and the allylene alkylene group having 8 to 12 carbon atoms are cyano groups and carboxyl groups. It may be substituted with an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom. Examples of the alkyl group having 1 to 4 carbon atoms, which may replace an alkylene group having 1 to 8 carbon atoms, include an alkyl group having 1 to 4 carbon atoms, which will be described later, and have 1 to 4 carbon atoms. Examples of the alkoxy group include an alkyl group having 1 to 4 carbon atoms, which will be described later, interrupted by an oxygen atom.

Examples of the alkyl group represented by R ^b and R ^c that may substitute phenylene in the general formula (1-1) include an alkyl group having 1 to 8 carbon atoms. Alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, tertiary butyl, isobutyl, amyl, isoamyl, secondary amyl, tertiary amyl, hexyl, 1-ethylpentyl, and the like. Examples thereof include cyclohexyl, 1-methylcyclohexyl, heptyl, isoheptyl, tertiary heptyl, n-octyl, isooctyl, tertiary octyl, 2-ethylhexyl and the like.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^d in the general formula (1-2) include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl and the like.

Among the compounds listed above, it is more preferable to use the compound represented by the above general formula (1-1) from the viewpoint of easy availability and the like, and it is represented by the above general formula (1-1). It is particularly preferable that the compound is a compound represented by the following general formula (1-3).

(In the general formula (1-3), ^Re is a single bond, a methylene group, -CH (CH ₃ )-, -C (CH ₃ ) _2- , or the following general formulas (2-1) to (2-). Represents any of the functional groups represented by 8), and R ^f , R ^g , R ^h , and R ⁱ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

(In the general formula (2-3), m represents an integer of 4 to 12 and represents an integer.
* In the general formulas (2-1) to (2-8) represents a bond. )

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^f , R ^g , R ^h , and ^Ri in the general formula (1-3) include methyl, ethyl, propyl, isopropyl, butyl, butyl, isobutyl, and t. -Butyl and the like can be mentioned.

Examples of the compound represented by the above general formula (1-3) include bis (4-cyanatophenyl) methane, bis (3,5-dimethyl-4-cyanatophenyl) methane, and 1,1-bis (1,1-bis). Examples thereof include 4-cyanatophenyl) ethane and 2,2-bis (4-cyanatophenyl) propane.
In the present invention, as the (A) cyanate ester, 1,1-bis (4-cyanatophenyl) ethane and 2,2-bis (4-cyanatophenyl) are used from the viewpoint of availability and workability. It is particularly preferred to use propane.

The content of the (A) cyanic acid ester in the present invention is preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass with respect to 100 parts by mass of the epoxy resin (B) described later. , 50 to 120 parts by mass is more preferable. (A) When the content of the cyanic acid ester is less than 10 parts by mass, the strength of the resin composition tends not to improve, and when it is more than 200 parts by mass, the adhesion of the resin composition to the substrate is remarkable. It tends to decrease.

[(B) Epoxy resin]
The (B) epoxy resin used in the present invention is a compound or a mixture having an epoxy group in the molecule. The present invention is characterized in that 1 to 35% by mass of the total amount of (B) epoxy resin is a flexible epoxy resin. In the present invention, from the viewpoint of the balance between Tg and impact resistance, the flexible epoxy resin is preferably 2% by mass or more, and 3% by mass or more, based on the total amount of the (B) epoxy resin. More preferably, it is more preferably 5% by mass or more, and particularly preferably 6% by mass or more. From the same viewpoint, the flexible epoxy resin is preferably 30% by mass or less, more preferably 20% by mass or less, and 10% by mass or less of the total amount of (B) epoxy resin. Is even more preferable. For example, the flexible epoxy resin is preferably 2 to 20% by mass, more preferably 6 to 10% by mass, out of the total amount of (B) epoxy resin.

In the present invention, the flexible epoxy resin is an epoxy resin having a flexible skeleton such as a urethane bond, a rubber component, an acetal component, and a long-chain fatty acid component in the molecule, and is a function of the conventional epoxy resin that is hard and brittle. It is a material that improves the quality and imparts flexibility to the cured product. (B) When the epoxy resin contains a predetermined amount of the flexible epoxy resin, the cured product of the resin composition is easily modified, and as a result, the impact resistance can be improved. It is possible to improve the reliability in terms of the strength of the fiber-reinforced plastic used. Examples of the flexible epoxy resin include urethane-modified epoxy resin, rubber-modified epoxy resin, acetal-modified epoxy resin, and polymerized fatty acid-modified epoxy resin. Among these, urethane-modified epoxy resin and rubber-modified epoxy resin are preferable because they are easily available and the impact resistance of the cured product can be improved.

The urethane-modified epoxy resin has an epoxy group and a urethane bond in the molecule. For example, (b-1) an epoxy resin containing at least one hydroxyl group and (b-2) a urethane prepolymer can be used, for example. It can be obtained by reacting at 40 to 150 ° C. for 1 to 10 hours using a catalyst as needed.

The blending amount of the epoxy resin (b-1) containing at least one hydroxyl group and the urethane prepolymer (b-2) is not particularly limited, but the obtained urethane-modified epoxy resin contains an isocyanate group. It is preferable that the amount does not remain, because the storage stability of the urethane-modified epoxy resin is improved. That is, it is preferable that (b-2) the number of isocyanate group equivalents in the urethane prepolymer is smaller than (b-1) the number of hydroxyl group equivalents in the epoxy resin containing at least one hydroxyl group.

Examples of the catalyst include conventionally known tertiary amines, quaternary ammonium salts, organometallic catalysts and the like. These may be used alone or in combination of two or more.

Examples of the tertiary amines include N, N, N', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylpropylenediamine, N, N, N', N''. , N''-pentamethyldiethylenetriamine, N, N, N', N'', N''-pentamethyl- (3-aminopropyl) ethylenediamine, N, N, N', N'', N''-penta Methyldipropylene triamine, N, N, N', N'-tetramethylguanidine, 1,3,5-tris (N, N-dimethylaminopropyl) hexahydro-S-triazine, 1,8-diazabicyclo [5.4] .0] Undecene-7, Triethylenediamine, N, N, N', N'-Tetramethylhexamethylenediamine, N-Methyl-N'-(2-dimethylaminoethyl) piperazine, N, N'-dimethylpiperazine, Dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, bis (2-dimethylaminoethyl) ether, N, N-dimethyllaurylamine, 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2- Examples thereof include methylimidazole and 1-dimethylaminopropylimidazole.

Examples of the quaternary ammonium salt include tetraalkylammonium halides such as tetramethylammonium chloride, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide salt, and tetraalkyls such as tetramethylammonium 2-ethylhexanolate. Examples include ammonium organic acid salts.

Examples of the organic metal catalyst include stanas diacetate, stanas dioctate, stanas dilaurate, stanas dilaurate, dibutyl tin oxide, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin dichloride, dioctyl tin dilaurate, and lead octanoate. , Lead naphthenate, nickel naphthenate, cobalt naphthenate and the like.

More preferred catalysts listed above are dibutyltin dilaurate and dioctyltin dilaurate, which are highly reactive, low in volatility and easy to use.
The blending amount of the catalyst is not particularly limited, but is preferably 0.01 to 2.0 parts by mass, and 0.05 to 1 part by mass with respect to 100 parts by mass of the (b-2) urethane prepolymer. It is more preferably 9.0 parts by mass. If it is less than 0.01 parts by mass, the reaction rate may not improve, and if it is more than 2.0 parts by mass, the reaction rate may increase too much and heat generation may increase, making it difficult to control the reaction temperature. be.

(B-1) The method for producing an epoxy resin containing at least one hydroxyl group is not particularly limited, but 1 to 10 equivalents of epichlorohydrin and sodium hydroxide are equal to 1 equivalent of a hydroxyl group of a low molecular weight polyol having at least two hydroxyl groups. For example, a method of reacting at 40 to 150 ° C. for 1 to 20 hours by using an alkali metal hydroxide in combination as described above can be mentioned. By adjusting the blending amount, heating temperature, and reaction time of these epichlorohydrin and alkali metal hydroxides, some of the generated epoxy groups further react with unreacted hydroxyl groups to generate new hydroxyl groups. , Incorporated in epoxy resin. This hydroxyl group reacts with the (b-2) urethane prepolymer.

The low molecular weight polyol containing at least two hydroxyl groups is not particularly limited, and examples thereof include polyphenols, aliphatic polyols, and alicyclic polyols.

Examples of the polyphenols include bisphenol A, bisphenol F, tetrabrom bisphenol A, phenol novolak, brominated phenol novolak, cresol novolak, brominated cresol novolak, 4,4'-dihydroxybiphenyl, 1,1,2,2. -Tetakis (hydroxyphenyl) ethane can be mentioned.

Examples of the aliphatic polyols include polyhydric alcohols such as ethylene glycol and propylene glycol, butanediol, pentandiol, hexanediol, octanediol, decanediol, glycerin, trimethylolpropane, trimethylolethane and pentaerythritol. Examples thereof include linear or branched low molecular weight polyols such as dipentaerythritol and neopentyl glycol, and ethylene oxides or propylene oxide adducts thereof.

Examples of the alicyclic polyol include cyclohexanediol, cyclohexanetriol, cyclohexanedimethanol, isopropyridendicyclohexanol, decalindiol, and tricyclodecanedimethanol.

Among these polyols having at least two hydroxyl groups, polyphenols having high reactivity and easy production are preferable, and bisphenol A and bisphenol F, which can be obtained at low cost, are more preferable. That is, in the present invention, (b-1) the epoxy resin containing at least one hydroxyl group is preferably a reaction product obtained by reacting epichlorohydrin with bisphenol A and / or bisphenol F.

The urethane prepolymer (b-2) is obtained by reacting a polyol containing at least two hydroxyl groups with a polyisocyanate.

The polyol containing at least two hydroxyl groups is not particularly limited, and for example, a polyether polyol, a polyester polyol, a polycarbonate polyol, or the like can be used. These compounds may be used alone or in combination of two or more.

As the above-mentioned polyether polyol, for example, one or two or more compounds having two or more active hydrogen atoms can be used as an initiator and addition-polymerized with an alkylene oxide.
Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylolglycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and glycerin. , Trimethylolethane, trimethylolpropane and the like.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran.

As the polyester polyol, for example, a cyclic ester compound such as an aliphatic polyester polyol, an aromatic polyester polyol, or ε-caprolactone obtained by esterifying a low molecular weight polyol and a polycarboxylic acid is subjected to ring-opening polymerization reaction. Examples thereof include the obtained polyester and these copolymerized polyesters.
Examples of the low molecular weight polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1.4-butanediol, 2-methyl-1,3-propanediol, and 1,5-pentanediol. Aliper glycols such as neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, 1,4-cyclohexane Examples thereof include alicyclic glycols such as dimethanol.
Examples of the polycarboxylic acid include succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, and anhydrides or ester-forming derivatives thereof.

Examples of the polycarbonate polyol include those obtained by reacting a carbonic acid ester with a polyol, and those obtained by reacting phosgene with bisphenol A and the like.
Examples of the carbonic acid ester include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenylcarbonate and the like. Examples of the polyol to be reacted with the carbonate ester for producing the above polycarbonate polyol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol and 1,4. -Butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6- Hexylene diol, 1,7-heptane diol, 1,8-octane diol, 1,9-nonan diol, 1,10-decane diol, 1,11-undecane diol, 1,12-dodecane diol, 3-methyl-1 , 5-Pentane diol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethylpropanediol, 2 -Relatively low levels of methyl-1,8-octanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcin, bisphenol A, bisphenol F, 4,4'-biphenol, etc. Examples thereof include dihydroxy compounds having a molecular weight; polyether polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; and polyester polyols such as polyhexamethylene adipate, polyhexamethylene succinate and polycaprolactone.

Among these polyols containing at least two hydroxyl groups, a polyether polyol that is inexpensive and can be used with low viscosity is preferable, and a propylene oxide addition polymer of propylene glycol and a propylene oxide addition polymer of glycerin are more preferable.

The number average molecular weight of the polyol containing at least two hydroxyl groups is not particularly limited, but is preferably 1000 to 5000, and more preferably 1500 to 4000.

The polyisocyanate used for producing the above (b-2) urethane prepolymer is not particularly limited, and known polyisocyanates can be used. For example, aromatic diisocyanates such as phenylenediocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalenedi isocyanate, xylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxyli Examples thereof include aliphatic or aliphatic ring structure-containing diisocyanates such as range isocyanate. These may be used alone or in combination of two or more. Among these, aromatic diisocyanates are preferable, and tolylene diisocyanates are more preferable because they can be obtained at low cost.

In the reaction of a polyol containing at least two hydroxyl groups with a polyisocyanate, a catalyst can be used, if necessary, in order to increase the reaction rate. Examples of the catalyst used include the same catalysts that can be used in the reaction of the epoxy resin (b-1) containing at least one hydroxyl group and the urethane prepolymer (b-2) mentioned above.
More preferred catalysts used in the reaction of a polyol containing at least two hydroxyl groups with a polyisocyanate are dibutyltin dilaurate and dioctyltin dilaurate, which are highly reactive, low in volatility and easy to use.
The blending amount of the catalyst is not particularly limited, but is preferably 0.01 to 2.0 parts by mass, preferably 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the polyisocyanate component. Is more preferable. If it is less than 0.01 parts by mass, the reaction rate may not improve, and if it is more than 2.0 parts by mass, the reaction rate may increase too much and heat generation may increase, making it difficult to control the reaction temperature. be.

The (b-2) urethane prepolymer needs to have an isocyanate group in order to react with the (b-1) epoxy resin containing at least one hydroxyl group. Therefore, when producing the above (b-2) urethane prepolymer, the number of isocyanate groups of the polyisocyanate needs to be larger than the number of hydroxyl groups in the polyol containing at least two hydroxyl groups, and more preferably at least two. The isocyanate group equivalent of the polyisocyanate is 1.2 to 3.0 equivalents, more preferably 1.3 to 2.5, with respect to 1 equivalent of the number of hydroxyl groups in the polyol containing a hydroxyl group.

The rubber-modified epoxy resin, which is suitable as a flexible epoxy resin, is obtained by polymerizing isoprene rubber, butadiene, styrene, acrylonitrile, chloroprene, etc. in the epoxy resin, and copolymerizing each component or copolymerizing two or more kinds of components. It contains a rubber component that has been polymerized, and contains an epoxy group at the end. In the present invention, the rubber-modified epoxy resin is preferably a reaction product obtained by reacting (b-3) a liquid epoxy resin at 25 ° C. with (b-4) acrylonitrile butadiene rubber containing a terminal carboxyl group. In this case, it is preferable to mix 5 to 100 parts by mass of the component (b-4) with respect to 100 parts by mass of the component (b-3) and react. Under the reaction conditions, it can be obtained by reacting with a catalyst such as triphenylphosphine at, for example, 60 to 160 ° C. for 1 to 60 hours.

Examples of the epoxy resin liquid at 25 ° C. (b-3) include polyglycidyl ether compounds of mononuclear polyvalent phenolic compounds such as hydroquinone, resorcin, pyrocatechol, and fluoroglucosinol; dihydroxynaphthalene, biphenol, and methylenebisphenol. Polyglycidyl ether compound of polynuclear polyvalent phenolic compounds such as (bisphenol F), methylenebis (orthocresol), etilidenbisphenol, isopropyridenebisphenol (bisphenol A), isopropyridenebis (orthocresol), tetrabromobisphenol A; ethylene glycol, Propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, dicyclopentadiene dimethanol, 2,2-bis (4-hydroxycyclohexylpropane (bisphenol A hydride), glycerin, trimethylolpropane, pentaerythritol, sorbitol , Polyglycidyl ethers of polyhydric alcohols such as bisphenol A-ethylene oxide adduct; N, N-diglycidylaniline, bis (4- (N-methyl-N-glycidylamino) phenyl) methane, diglycidyl orthotoluidine, N , N-bis (2,3-epoxypropyl) -4- (2,3-epoxypropoxy) -2-methylaniline, N, N-bis (2,3-epoxypropyl) -4- (2,3-) Epoxypropoxy) Aniline, N, N, N', N'-tetra (2,3-epoxypropyl) -4,4'-diaminodiphenylmethane and other epoxy compounds having a glycidylamino group can be mentioned. Among them, polyglycidyl ether compounds of polynuclear polyvalent phenol are preferable, and bisphenol A and bisphenol F diglycidyl ethers are more preferable because they are easily available and inexpensive.

The (b-4) terminal carboxyl group-containing acrylonitrile butadiene rubber is obtained by modifying acrylonitrile butadiene rubber, which is a copolymer of acrylonitrile and butadiene, to introduce a carboxyl group.

Examples of the method for introducing a carboxyl group include (1) a method of copolymerizing acrylonitrile and butadiene with a monomer further having a carboxyl group, and (2) a method of copolymerizing acrylonitrile and butadiene and then carboxylating. Examples thereof include a method of graft-reacting a monomer having a group.
The (b-4) terminal carboxyl group-containing acrylonitrile butadiene rubber for producing a rubber-modified epoxy resin is preferably a liquid one from the viewpoint of easy handling. Examples of commercially available liquid terminal carboxyl group-containing acrylonitrile butadiene rubber include Nipol (registered trademark) 1072 and Nipol (registered trademark) DN-601 (all manufactured by Nippon Zeon Corporation).

Examples of the flexible epoxy resin other than the urethane-modified epoxy resin and the rubber-modified epoxy resin are described in JP-A-2005-298728 and the like, acetal-modified epoxy resin having an acetal skeleton, JP-A-9-208664 and the like. Examples thereof include known ones such as a polymerized fatty acid-modified epoxy resin obtained by modifying an epoxy resin with a polymerized fatty acid such as castor oil fatty acid or tall oil fatty acid.

Examples of commercially available flexible epoxy resins include adekaresins EPU-11F, EPU-73B, EPR-1415-1, EPR-2000 (all manufactured by ADEKA Corporation); jER (registered trademark) 871, 872. , (Above, manufactured by Mitsubishi Chemical Corporation); EPICLON (registered trademark) EXA-4816, EXA-4850 (above, manufactured by DIC Co., Ltd.), Araldite (registered trademark) LY 3508 (manufactured by HUNTSMAN), and the like.

In the present invention, the (B) epoxy resin other than the flexible epoxy resin can be used without particular limitation as long as it has an epoxy group. For example, polyglycidyl ether compounds of mononuclear polyvalent phenolic compounds such as hydroquinone, resorcin, pyrocatechol, fluoroglucosinol; dihydroxynaphthalene, biphenol, methylenebisphenol (bisphenol F), methylenebis (orthocresol), etylidenebisphenol, isopropylidene. Bisphenol (bisphenol A), isopropylidenebis (orthocresol), tetrabromobisphenol A, 1,3-bis (4-hydroxycumylbenzene), 1,4-bis (4-hydroxycumylbenzene), 1,1 , 3-Tris (4-hydroxyphenyl) butane, 1,1,2,2-tetra (4-hydroxyphenyl) ethane, thiobisphenol, sulfobisphenol, oxybisphenol, phenol novolak, orthocresol novolak, ethylphenol novolak, butylphenol Polyglycidyl ether compounds of polynuclear polyvalent phenol compounds such as novolak, octylphenol novolak, resorcin novolak, terpenphenol; ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, dicyclopentadiene dimethanol, 2, Polyglycidyl ethers of polyhydric alcohols such as 2-bis (4-hydroxycyclohexylpropane (bisphenol A hydride), glycerin, trimethylolpropane, pentaerythritol, sorbitol, bisphenol A-ethylene oxide adduct; maleic acid, fumaric acid, Itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, trimeric acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid , Hexahydrophthalic acid, Endomethylenetetrahydrophthalic acid and other aliphatic, aromatic or alicyclic polybasic acid glycidyl esters and glycidyl methacrylate homopolymers or copolymers; N, N-diglycidylaniline, bis (4- (N-Methyl-N-glycidylamino) phenyl) methane, diglycidyl orthotoluidine, N, N-bis (2,3-epoxypropyl) -4- (2,3-epoxypropoxy) -2-methyl Aniline, N, N-bis (2,3-epoxypropyl) -4- (2,3-epoxypropoxy) aniline, N , N, N', N'-tetra (2,3-epoxypropyl) -4,4'-diaminodiphenylmethane and other epoxy compounds with glycidylamino groups; vinylcyclohexene epoxides, dicyclopentanedienepoxides, 3, 4-Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-6-methylcyclohexanecarboxylate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, etc. Epoxides of cyclic olefin compounds in the above; examples thereof include epoxidized conjugated diene polymers such as epoxidized polybutadiene and epoxidized styrene-butadiene copolymers, and heterocyclic compounds such as triglycidyl isocyanurate. In addition, these epoxy resins may be internally crosslinked with a prepolymer of terminal isocyanate, or may be polymerized with a polyvalent active hydrogen compound (polyhydric phenol, polyamine, carbonyl group-containing compound, polyphosphate ester, etc.). good.

In the present invention, as the (B) epoxy resin other than the flexible epoxy resin, a polyglycidyl ether compound, which is a polynuclear polyvalent phenol compound, can be obtained at low cost and has good physical properties. Epoxy compounds having a glycidylamino group are preferable, and bisphenol A diglycidyl ether and bisphenol F diglycidyl ether are more preferable.

[(C) Aromatic amine-based curing agent liquid at 25 ° C]
The aromatic amine-based curing agent (C) liquid at 25 ° C. used in the present invention is liquid at 25 ° C. and has an amino group directly on the aromatic ring in order to allow easy penetration into the fiber material. It is a compound that is provided. Examples of such compounds include diaminodimethyldiphenylmethane, diaminodiethyldiphenylmethane, diaminodiethyltoluene, 1-methyl-3,5-bis (methylthio) -2,4-benzenediamine, 1-methyl-3,5-bis. (Methylthio) -2, 6-benzenediamine and the like can be mentioned.
Among these, diaminodiphenylmethane, diaminodimethyldiphenylmethane, and diaminodiethyltoluene are preferable, and diaminodiethyldiphenylmethane is more preferable, from the viewpoint of improving the heat resistance of the cured product.

In the present invention, the content of the (C) aromatic amine-based curing agent is preferably 20 to 100 parts by mass, more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the (B) epoxy resin. When the content of the aromatic amine-based curing agent is less than 20 parts by mass or more than 100 parts by mass, the resin composition tends not to be completely cured.

The resin composition for fiber reinforced plastics of the present invention may contain (D) a light-absorbing component. (D) When the light-absorbing component is contained, the curing time can be further shortened by irradiating with active energy rays. By shortening the curing time, the working time is shortened, and curing is performed with less energy than in the case of heat curing, which is not only economical but also environmentally advantageous.

The (D) light-absorbing component contained in the resin composition of the present invention is a component capable of absorbing the active energy rays described later and releasing heat energy, and the released heat energy cures the resin composition. Can be made to. Such light-absorbing components include those that are liquid at 25 ° C. from the viewpoint of permeating the resin composition between the fibers, or those that are compatible with other materials and become liquid. Is preferable. Examples of such compounds include aniline black, metal complexes, square acid derivatives, immonium dyes, polymethins, phthalocyanine compounds, naphthalocyanine compounds, perylene compounds, quoterylene compounds, niglosin compounds and the like. In the present invention, among these compounds, it is more preferable to use a niglosin-based compound because it is easily available.

Examples of commercially available niglocin-based compounds include BONASORB series, eBIND ACW series, eBIND LTW series, eBIND LAW series, ORIENT NIGROSINE series, and NUBIAN BLACK series manufactured by Orient Chemical Industries, Ltd. In the present invention, among these niglocin-based compounds, it is preferable to use the NUBIAN BLACK series because it is inexpensive and easily available. One of these niglocin-based compounds may be used alone, or two or more thereof may be used in combination.

The content of the (D) light-absorbing component of the resin composition for fiber reinforced plastic of the present invention may be in the range of 0.001 to 1% by mass with respect to the total amount of the resin composition. From the viewpoint of the balance between the curing rate of the resin composition and the heat generation (burning of the composition), it is preferably 0.01 to 0.5% by mass, preferably 0.05 to 0.2% by mass. More preferred. If the content is less than 0.001%, heat generation will be insufficient only by irradiation with active energy rays, and it will be difficult to completely cure the resin composition. If it is more than 1%, most of the active energy rays are absorbed on the surface of the resin composition, and only the surface of the resin composition is carbonized and the active energy does not pass to the inside. It becomes difficult to completely cure.

[Additive]
Additives may be used in combination with the resin composition of the present invention, if necessary.
Examples of the additive include non-reactive diluents (plasticizers) such as dioctylphthalate, dibutylphthalate, benzyl alcohol, and coaltal; pigments; γ-aminopropyltriethoxysilane and N-β- (aminoethyl). -Γ-Aminopropyltriethoxysilane, N-β- (aminoethyl) -N'-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-anilinopropyltriethoxysilane, γ-glycidoxy Propyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, vinyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltriethoxysilane, γ-methacryloxy Silane coupling agents such as propyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-isocyanatepropyltriethoxysilane; isopropyltriisostearoyl titanate, isopropyltri-n-dodecylbenzenesulfonyl titanate. , Isopropyltris (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (di-tridecyl) ) Phosphite titanate, bis (dioctylpyrophosphate) oxyacetate titanate, bis (dioctylpyrrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, isopropyldimethacryloylisostearoyltitanate, isopropylisostearoyldiacryl titanate, isopropyltri (dioctylphosphate) Titanate, isopropyltricylphenyl titanate, isopropyltri (N-aminoethyl-aminoethyl) titanate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetrakis (2-ethylhexyl) titanate, tetrastearyl titanate, tetramethyl titanate, Diethoxybis (acetylacetonato) titanium, diisopropylbis (acetylacetonato) titanium, diisopropoxybis (ethylacetoacetate) titanium, isopropoxy (2-ethyl-1,3-hexanediorat) titanium, di (2-ethylhexoxy) ) Bis (2-ethyl-1,3-hexanediorat) titanium, di-n-butoxybis (triethanolaminato) titanium, tetraacetylacetonate titanium, hydroxybis (lactoto) titanium, dicumylphenyloxyacetate titanate, Titanium coupling agents such as diisostearoylethylene titanate; neoalkoxytris neodecanoylzirconate, neoalkoxytris (dodecyl) benzenesulfonylzirconate, neoalkoxytris (dioctyl) phosphate zirconate, neoalkoxytris (dioctyl) pyrophosphate Zirconate, Neoalkoxytris (ethylenediamino) ethylzirconate, Neoalkoxytris (m-amino) Phenylzirconate, Tetra (2,2-diallyloxymethyl) butyl, Di (ditridecyl) phosphatidylconate, Neopentyl (diallyl) ) Oxy, Trineodecanoylzirconate, Neopentyl (diallyl) oxy, Tri (dodecyl) benzene-sulfonylzirconate, Neopentyl (diallyl) oxy, Tri (dioctyl) phosphatzirconate, Neopentyl (diallyl) oxy, Tri (dioctyl) ) Pyro-phosphatzirconate, neopentyl (diallyl) oxy, tri (N-ethylenediamino) ethylzirconate, neopentyl (diallyl) oxy, tri (m-amino) phenylzirconate, neopentyl (diallyl) oxy, trimethacrylzircoate Nate, neopentyl (diallyl) oxy, triacrylic zirconate, dineopentyl (diallyl) oxy, diparaaminobenzoylzirconate, dineopentyl (diallyl) oxy, di (3-mercapto) propionic zirconate, zirconium (IV) 2,2 -Bis (2-propenolatomethyl) butanorat, cyclodi [2,2- (bis2-propenoratmethyl) butanorat] pyrophosphat-O, O, neoalkoxytris neodecanoylzirconate, neoalkoxytris (dodecyl) Benzenesulfonyl zirconate, neoalkoxytris (dioctyl) phosphate zirconate, neoalkoxytris (dioctyl) pyrophosphate zirconate, neoalkoxytris (ethylenediamino) ethylzirconate, neoalkoxytris (m-amino) phenylzirconate, and also , As a zirconium-based coupling agent, tetra Normalpropoxyzylzyl, tetranormalbutoxyzylene, zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, zirconium tributoxystearate, zirconium dibutoxybis (acetylacetonate), zirconium dibutoxybis (acetylacetonate), zirconium tri Zyla-based coupling agents such as butoxyethylacetate, zirconium monobutoxyacetylacetonatebis (ethylacetacetate); candelilla wax, carnauba wax, wood wax, ibotarou, honey wax, lanolin, whale wax, montan wax, petroleum wax. , Fatty acid waxes, fatty acid esters, fatty acid ethers, aromatic esters, aromatic ethers and other lubricants; thickeners; thixotropic agents; antioxidants; light stabilizers; ultraviolet absorbers; flame retardants; antifoaming agents; Examples thereof include commonly used additives such as rust agents.

Among the additives listed above, from the viewpoint of impregnating the fiber, it is preferable that the additive is liquid at 25 ° C. or is soluble in a cyanate ester, an epoxy resin, or an aromatic amine-based curing agent. It is more preferable to add a silane coupling agent in terms of improving adhesion to γ-aminopropyltriethoxysilane, and / or γ-glycidoxy in that it is easily available and inexpensive. It is more preferable to add propyltriethoxysilane, and it is particularly preferable to add γ-glycidoxypropyltriethoxysilane.

The amount of the silane coupling agent listed above is preferably 0.1 to 50 parts by mass with respect to 100 parts by weight of the epoxy resin (B), which has good miscibility with the resin and is compatible with the fiber. From the viewpoint of improving the adhesiveness, it is more preferable to add 7 to 20 parts by mass.

The resin composition for fiber reinforced plastics of the present invention preferably has a viscosity at 25 ° C. of 100 to 2000 mPa · s, more preferably 500 to 1700 mPa · s, and 900 to 1500 mPa · s. Is particularly preferable. When the viscosity at 25 ° C. is in the above range, workability is improved. The viscosity of the resin composition for fiber reinforced plastic can be adjusted, for example, by adjusting the content of the flexible epoxy resin in the total amount of the epoxy resin (B). The viscosity of the resin composition for fiber reinforced plastic can be measured, for example, with a B-type viscometer or the like.

The cured product of the present invention is obtained by curing the resin composition for fiber reinforced plastic of the present invention. The method for curing the resin composition for fiber reinforced plastics of the present invention is not particularly limited, and can be cured by a known method. Specifically, the resin composition for fiber reinforced plastics of the present invention can also be cured by heating. Further, when the resin composition for fiber reinforced plastic of the present invention contains (D) a light-absorbing component, the curing time can be further shortened by irradiating with active energy rays. By shortening the curing time, the working time is shortened, and curing is performed with less energy than in the case of heat curing, which is not only economical but also environmentally advantageous.

The active energy ray is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the active energy ray include electron beam, ultraviolet ray, infrared ray, laser beam, visible ray, ionizing radiation (X-ray, α ray, β ray, γ ray, etc.), microwave, high frequency and the like.
In the present invention, among these active energy rays, from the viewpoint of further improving the curing rate, it is preferable to use a laser beam and / or infrared rays, and it is more preferable to use infrared rays.

The laser beam is a solid-state laser using ruby, glass, or YAG (crystals of yttrium, aluminum, or garnet with a small amount of rare earth added) as a medium; a dye dissolved in a solvent such as water or alcohol is used as a medium. Liquid laser; gas laser using CO2, argon, He-Ne mixed gas or the like as a medium; semiconductor laser utilizing recombination emission of semiconductor. In the present invention, it is preferable to use a semiconductor laser which is inexpensive and whose output can be easily controlled.

The wavelength of the laser beam used in the present invention is not particularly limited, and for example, the resin composition can be cured in the near infrared region (wavelength is about 0.7 to 2.5 μm). The output of the laser beam is also not particularly limited, and the resin composition can be cured, for example, in the range of 1 W to 4 kW.

The time for irradiating the laser is not particularly limited, but the range varies depending on the irradiation area and the output. For example, the resin composition can be cured in the range of 0.2 W / mm ² to 10 W / mm ² . .. The wavelength of infrared rays that cures the resin composition of the present invention is also not particularly limited. For example, the wavelength of any region such as the near-infrared region (wavelength is about 0.7 to 2.5 μm), the mid-infrared region (wavelength is about 2.5 to 4 μm), and the far-infrared region (wavelength is about 4 to 1000 μm). However, the resin composition can be cured.

Examples of the method of curing the resin composition for fiber reinforced plastic of the present invention by irradiation with infrared rays include a method of irradiating with an infrared heater. Examples of the infrared heater include a halogen heater, a quartz heater, a sheathed heater, and a ceramic heater. Halogen heaters can irradiate infrared rays with wavelengths from the near-infrared region to the mid-infrared region, and quartz heaters, sheathed heaters, and ceramic heaters emit infrared rays with wavelengths from the mid-infrared region to the far-infrared region. It can also be irradiated. Among these, it is preferable to use a halogen heater because the time from turning on the power to heating the heat source is short and the heating can be performed quickly.

The wavelength of the infrared ray that cures the resin composition for fiber reinforced plastic of the present invention is not particularly limited, but various wavelength regions can be used depending on the absorption region of the light-absorbing component used. For example, when a niglocin-based compound is used, the cured resin product of the present invention can be cured in a short time in the near infrared region (wavelength is about 0.7 to 2.5 μm).

The fiber-reinforced plastic of the present invention can be obtained by curing the resin composition for fiber-reinforced plastic of the present invention and the matrix resin (composition) of the fiber-reinforced plastic uniformly containing the reinforcing fibers. In the present invention, uniformly containing the resin composition for fiber reinforced plastic and the reinforced fiber means that the resin composition does not stay on the surface but completely spreads to the inside of the fiber. The type of the reinforcing fiber is not particularly limited, and for example, carbon fiber, glass fiber, aramid fiber, boron fiber, alumina fiber, silicone carbide fiber and the like may be used alone, or may be used as two or more kinds of hybrid fibers. good.
The forms of the reinforcing fibers listed above include so-called toe sheets in which high-strength and high-elasticity fibers are arranged in one direction, unidirectional woven fabrics in which the fiber threads are arranged in one direction or two directions, and bidirectional. Examples thereof include woven fabrics, triaxial woven fabrics arranged in three directions, and multiaxial woven fabrics arranged in multiple directions. In the tow sheet, the fibers may be arranged so as to secure an appropriate gap between the strands in order to improve the resin impregnation property into the base material.

The amount of the reinforcing fiber used in the resin composition for fiber reinforced plastic of the present invention is not particularly limited and can be appropriately determined depending on the intended use of the obtained fiber reinforced plastic. For example, the resin composition for fiber reinforced plastic The volume content of the reinforcing fibers is preferably 45 to 70%, more preferably 50 to 65%, based on the total volume of the reinforcing fibers. Further, the method for curing the matrix resin of the fiber reinforced plastic is not particularly limited, and for example, the resin composition for fiber reinforced plastic of the present invention can be cured in the same manner as described above.

The method for molding the fiber-reinforced plastic obtained by curing the resin composition of the present invention is not particularly limited, but for example, an extrusion molding method, a blow molding method, a compression molding method, a vacuum molding method, or an injection molding method. , RTM (Resin Transfer Molding) molding, VaRTM (Vaccum assist Resin Transfer Molding) molding, laminated molding, hand lay-up molding, filament winding molding and the like.

The fiber reinforced plastic obtained by using the resin composition of the present invention can be used for various purposes. For example, general industrial applications such as structural materials for moving bodies such as automobiles, ships and railroad vehicles, drive shafts, leaf springs, windmill blades, pressure vessels, fly wheels, paper rollers, roofing materials, cables, and repair reinforcement materials; Aerospace applications such as fuselage, main wings, tail wings, moving blades, fairings, cowls, doors, seats, interior materials, motor cases, antennas; golf shafts, fishing rods, tennis and badminton racket applications, stick applications such as hockey, and Sports applications such as ski pole applications can be mentioned.

Hereinafter, the present invention will be specifically described with reference to Examples. In the following examples and the like,% is based on mass unless otherwise specified.

[Production Example 1: Modified Epoxy Resin UR-1]
Add 150.6 g of ADEKApolyether G-3000B (propylene oxide addition polymer of glycerin having a number average molecular weight of 3000, manufactured by ADEKA Corporation) and 39.3 g of tolylene diisocyanate to a 1 L separable flask from above. After the nitrogen substitution, the inside of the flask was heated and reacted at 70 to 75 ° C. for 2 hours. The isocyanate group equivalent of tolylene diisocyanate was 3 with respect to 1 equivalent of the hydroxyl group of Adekapolyether G-3000B. Then, 662 g of ADEKARESIN EP-4901 (bisphenol F type epoxy resin having a hydroxyl group, manufactured by ADEKA Corporation, epoxy equivalent: 170 g / eq.) And 0.08 g of dioctyltin dilaurate as a catalyst for the urethane reaction were added, and 80 to 80 to The reaction was carried out at 90 ° C. After measuring the infrared absorption spectrum of the obtained reactant and confirming that there is no absorption of NCO, ADEKA glycyrrole ED-523T (neopentyl glycol diglycidyl ether, manufactured by ADEKA Corporation, epoxy equivalent: 140 g / eq). ) Was added to obtain a modified epoxy resin U-1. Of the total amount of epoxy resin in U-1, the urethane-modified epoxy resin component is 28.1% in theory, and the remaining unreacted epoxy resin component (EP-491, ED-523T) is 71.9%. Is.

[Production Example 2: Modified Epoxy Resin UR-2]
Add 231 g of ADEKApolyether P-2000 (propylene oxide addition polymer of propylene glycol having a number average molecular weight of 2000, manufactured by ADEKA Corporation) and 42 g of tolylene diisocyanate to a 1 L separable flask, and perform nitrogen substitution from above. After that, the inside of the flask was heated and reacted at 70 to 75 ° C. for 2 hours. The isocyanate group equivalent of tolylene diisocyanate was 2.1 with respect to 1 equivalent of the hydroxyl group of the adekapolyether P-2000. Then, 643 g of Adecaledin EP-4100TX (bisphenol A type epoxy resin having a hydroxyl group, manufactured by ADEKA Corporation, epoxy equivalent: 210 g / eq.) And 0.1 g of dioctyltin dilaurate as a catalyst for the urethane reaction were added, and 80 to 80 to The reaction was carried out at 90 ° C. After measuring the infrared absorption spectrum of the obtained reactant and confirming that there is no absorption of NCO, ADEKA glycyrrole ED-523T (neopentyl glycol diglycidyl ether, manufactured by ADEKA Corporation, epoxy equivalent: 140 g / eq). ) Was added to obtain a modified epoxy resin U-2. Of the total amount of epoxy resin in U-2, the urethane-modified epoxy resin component is 36.4% in theory, and the remaining unreacted epoxy resin component (EP-4100TX, ED-523T) is 63.6%. Is.

[Manufacturing Example 3: Modified Epoxy Resin G-1]
228 g of Adecaledin EP-4300E (bisphenol A type epoxy resin, manufactured by ADEKA Corporation, epoxy equivalent: 185 g / eq.) Liquid at 25 ° C., Nipol® DN-601 (terminal carboxyl group-containing acrylonitrile butadiene rubber, 124 g of Nippon Zeon Co., Ltd. was charged and heated to 100 ° C. 0.1 part by mass of triphenylphosphine was added at 100 ° C., and the mixture was reacted at 130 to 150 ° C. for 4 hours. After confirming that the acid value is 1 mgKOH / g or less, 668 g of ADEKAREGIN EP-4901E (liquid bisphenol F type epoxy resin, manufactured by ADEKA Corporation, epoxy equivalent: 170 g / eq.) Is charged and brought to 90 to 100 ° C. And mixed for 1 hour to obtain a modified epoxy resin G-1. Of the total amount of epoxy resin in G-1, the rubber-modified epoxy resin component is 24.0% in theory, and the remaining unreacted epoxy resin components (EP-4300E, EP-4901E) are 76.0%. Is.

[Example 1]
In a 500 mL disposable cup, 50 g of LECy (1,1-bis (4-cyanatophenyl) ethane; manufactured by Ronza) as (A) cyanate ester, and (B) Adecaledin EP-4901E (bisphenol F) as an epoxy resin. Type epoxy resin, manufactured by ADEKA Co., Ltd., epoxy equivalent: 170 g / eq.) 25 g, modified epoxy resin UR-1 25 g, (C) Kayahard AA (diamino) as a liquid aromatic amine-based cured product at 25 ° C. 35 g of diethyldiphenylmethane (manufactured by Nippon Kayaku Co., Ltd.) was added, and the mixture was stirred at 25 ° C. for 5 minutes with a spatula. Then, it was further stirred using a planetary stirrer to obtain a compound. The obtained compound was evaluated by conducting a tensile test and measuring the viscosity by the following method.

<Tensile test method>
The above formulation was heated at 80 ° C. for 5 hours and then further heated at 150 ° C. for 2 hours to cure, and then a test piece was prepared according to a method in accordance with JIS K 7161-1, and the maximum point stress and maximum point elongation were obtained. , Stress at break, elongation at break and elastic modulus were measured. The results are shown in Table 1.

<Viscosity>
The above formulation was transferred to a glass bottle, and the viscosity was measured with a B-type viscometer under the conditions of 25 ° C. and a rotation speed of 10 rpm. The results are shown in Table 1.

[Examples 2 to 8, Comparative Example 1, Comparative Example 2]
The operation was carried out in the same manner as in Example 1 except that the formulations were changed as shown in Tables 1 and 2, respectively, to obtain formulations. The obtained compound was evaluated by conducting a tensile test and measuring the viscosity in the same manner as in Example 1. The results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, the cured product obtained by curing the resin composition of the present invention has an improved maximum point stress in the tensile test as compared with Comparative Example 1 in which the flexible epoxy resin is not used. I understood it. Further, in Comparative Example 2 in which the blending amount of the flexible epoxy resin is excessive, although there is no problem in terms of physical properties other than the elastic modulus in the tensile test, the viscosity becomes high and there is a problem in workability, and the fiber material has a problem. It was not satisfactory for impregnation. Further, it was found that the cured product obtained by curing the resin composition of the present invention had an improved elastic modulus in the tensile test as compared with the cured product obtained by curing the resin composition of Comparative Example 2.

Claims (10)

It contains (A) cyanic acid ester, (B) epoxy resin, and (C) an aromatic amine-based curing agent that is liquid at 25 ° C.
(B) 1 to 35% by mass of the total amount of epoxy resin is flexible epoxy resin.
The cyanate ester as a component (A) is a compound represented by the following general formula (1-1), a prepolymer of a compound represented by the following general formula (1-1), and the following general formula (1-2). ), The resin composition for a fiber-reinforced plastic containing at least one compound selected from the group consisting of the compounds represented by) and / or a prepolymer.

(In the general formula (1-1), R ^a represents a single bond, —S— or a divalent hydrocarbon group, and R ^b and R ^c are independently, unsubstituted or 1 to 4 alkyl, respectively. Represents a phenylene group substituted with a group, where R ^b and R ^c are substituted with 2-4 alkyl groups, the alkyl groups may be the same or different).

(In the general formula (1-2), n represents an integer of 1 to 10, and R ^d represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) The resin composition for fiber reinforced plastic according to claim 1, wherein the compound represented by the general formula (1-1) is a compound represented by the following general formula (1-3).

(In the general formula (1-3), ^Re is a single bond, a methylene group, -CH (CH ₃ )-, -C (CH ₃ ) _2- , or the following general formulas (2-1) to (2-). Represents any of the functional groups represented by 8), and R ^f , R ^g , R ^h , and R ⁱ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

(In the general formula (2-3), m represents an integer of 4 to 12, and * in the general formulas (2-1) to (2-8) represents a bond.) The first or second claim, wherein the flexible epoxy resin is at least one epoxy resin selected from the group consisting of a urethane-modified epoxy resin, a rubber-modified epoxy resin, an acetal-modified epoxy resin, and a polymerized fatty acid-modified epoxy resin. Resin composition for fiber reinforced plastics. The flexible epoxy resin contains a urethane-modified epoxy resin, and the urethane-modified epoxy resin is a reaction of (b-1) an epoxy resin containing at least one hydroxyl group and (b-2) a urethane prepolymer. The resin composition for a fiber-reinforced plastic according to any one of claims 1 to 3, which is a product. (B-1) The resin composition for fiber reinforced plastic according to claim 4, wherein the epoxy resin containing at least one hydroxyl group is a reaction product obtained by reacting epichlorohydrin with bisphenol A and / or bisphenol F. (B-2) The urethane prepolymer is a reaction product obtained by reacting a polyol containing at least two hydroxyl groups with a polyisocyanate, and the isocyanate group equivalent of the polyisocyanate is 1. The resin composition for a fiber-reinforced plastic according to claim 4 or 5, which is 2 to 3.0. The flexible epoxy resin contains a rubber-modified epoxy resin, and the rubber-modified epoxy resin reacts a liquid epoxy resin at (b-3) 25 ° C. with a (b-4) terminal carboxyl group-containing nitrile butadiene rubber. The resin composition for a fiber-reinforced plastic according to any one of claims 1 to 6, which is a reaction product. (C) Any one of claims 1 to 7, wherein the aromatic amine-based curing agent liquid at 25 ° C. is at least one compound selected from the group consisting of diaminodiphenylmethane, diaminodiethyldiphenylmethane, and diaminodiethyltoluene. The resin composition for fiber-reinforced plastics according to the section. A cured product obtained by curing the resin composition for fiber reinforced plastic according to any one of claims 1 to 8. A fiber-reinforced plastic obtained by curing the resin composition for fiber-reinforced plastic according to any one of claims 1 to 8 and a composition containing reinforcing fibers.