JPH11171974A - Epoxy resin composition for fiber-reinforced composite material, prepreg and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition that gives the cured products having excellent toughness and resistance to heat and is useful in the sports purposes as golf club shafts and the like, in the aerospace field, in the other industries by using a specific epoxy resin, a toughness-increasing agent and a curing agent. SOLUTION: This epoxy resin composition includes (A) an epoxy resin mixture mainly comprising (i) one or more kinds of an epoxy resins of formula I (n is 0 or more; Y is a 6-20C organic divalent group; X is a structure of formula II; m is 0 or more; Z is -CH2 - or the like) and (ii) a difunctional epoxy resins other than Ai (such as bisphenol A epoxy resin or the like) and (B) a granular toughness-increasing agent such as core shell rubber particles and (C) a curing agent such as dicyandiamide. In a preferred embodiment, the amount of the component Ai is 5-50 pts.wt. per 100 pts.wt. of the component A, the total of the component Ai and the component Aii is 70-100 pts.wt., while the amount of the component B is 1-20 pts.wt. As a component Ai, is cited a reaction product between a bis-phenol A type epoxy resin and tolylene diisocyanate or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fiber-reinforced composite material suitable for sports use, aerospace use, and general industrial use.
And an epoxy resin composition and a prepreg for obtaining the same.

[0002]

2. Description of the Related Art Fiber-reinforced composite materials using a prepreg composed of a reinforcing fiber and a matrix resin as an intermediate base material have excellent mechanical properties, and are particularly suitable for use in sports, aerospace and general industrial applications. Widely used.

[0003] Various methods are used for producing a fiber-reinforced composite material, and a method using a prepreg, which is a sheet-like intermediate substrate in which a reinforcing fiber is impregnated with a matrix resin, is widely used. In this method, after laminating a plurality of prepregs, a molded product is obtained by heating.

Recently, for sports applications, products that are lighter and more durable have been desired. In particular, golf shafts, baseball bats, rackets such as tennis and badminton,
In the case of a ball game device such as a hockey stick that receives an instantaneous large load, it is important to improve the impact resistance of the material in order to reduce the weight and improve the durability. .

At present, as a matrix resin used in a fiber reinforced composite material, an epoxy resin cured product having excellent mechanical and chemical properties such as heat resistance, hardness, dimensional stability and chemical resistance is used. Mainly used. However, the cured epoxy resin has the disadvantage that it is brittle, that is, has low toughness. Therefore, a problem often arises that the impact resistance of a fiber-reinforced composite material using the same is low.

Therefore, the epoxy resin cured product is made tougher,
Many attempts have been made to improve the impact resistance of fiber reinforced composite materials. As a method for increasing the toughness of a cured epoxy resin, a method of improving an epoxy resin or a curing agent or a method of adding a modifier is generally proposed.

As a method of increasing toughness by improving an epoxy resin or a curing agent, it is known that toughness can be improved by blending a flexible skeleton epoxy resin or a curing agent. Since heat resistance is sacrificed, there has been proposed a method in which a rigid skeleton is introduced into an epoxy resin or a curing agent, and at the same time, the crosslink density is reduced to adjust toughness, elastic modulus, and heat resistance. For example, ACS Polym.
Preprints, Vol. 29, No. 1 (1988), reports that a cured product of an epoxy resin obtained from an epoxy resin containing a fluorene ring and a curing agent can improve the toughness while suppressing a decrease in the glass transition temperature. However, such an improvement did not always have a sufficient effect of improving toughness.

As a method of adding a modifier, a method of adding a rubber component or a thermoplastic resin to an epoxy resin composition to increase the toughness of a cured product is known.

As a method for adding a rubber component, for example,
JP-B-61-29613, JP-B-62-3425
No. 1 discloses a butadiene-acrylonitrile copolymer rubber (CT) having a carboxyl group as an end group in an epoxy resin.
Examples of modification by adding BN) or nitrile rubber have been proposed, and some of them have been put to practical use. However, this method involves a process in which a rubber component is once dissolved in an epoxy resin and then undergoes phase separation upon curing. Therefore, the obtained morphology changes depending on the type of epoxy resin to be blended and the curing conditions, and the desired modification effect cannot be obtained, or the rubber component partially dissolves in the epoxy resin phase after curing. There were problems such as lowering of the elastic modulus and glass transition temperature of the cured product.

[0010] As one of the methods for solving the morphological change, which is a problem in increasing the toughness of a cured epoxy resin product by adding a rubber component, a method of dispersing rubber-like particles in an epoxy resin is known. For example, JP-A-58-830
No. 14, JP-A-59-138254 discloses that in order to improve the shear strength of an adhesive, a monomer such as an acrylate ester in an epoxy resin and a functional group such as acrylic acid capable of reacting with the epoxy resin are used. A method is disclosed in which a group-containing monomer is polymerized to obtain a composition in which rubber particles formed in an epoxy resin are dispersed. However, even in such a case, it is inevitable that a part of the rubber component dissolves in the epoxy resin phase after curing, and in fact, sufficient heat resistance cannot be ensured.

When an epoxy resin composition containing a thermoplastic resin having a sufficiently high glass transition temperature is cured, if the cured product has an appropriate morphology, for example, an interpenetrating network structure, heat resistance and elastic modulus are maintained. It is possible to give a tough cured product. However, there are problems that it is difficult to control the morphology of the cured product and that a large amount of addition is required to increase the toughness, so that the viscosity of the system increases and the handling property is hindered.

[0012]

SUMMARY OF THE INVENTION In view of the background of the prior art, an object of the present invention is to provide an epoxy resin composition for a fiber-reinforced composite material which is excellent in both functions of toughness and heat resistance of a cured product. Further, it is an object of the present invention to provide a prepreg using such an epoxy resin composition, and an excellent fiber-reinforced composite material which simultaneously satisfies the impact resistance and heat resistance obtained thereby.

[0013]

The present invention employs the following means in order to solve the above problems. That is, the epoxy resin composition for a fiber-reinforced composite material of the present invention is characterized by containing at least the following components [A], [B] and [C].

[A]: an epoxy resin represented by the general formula (I) or an epoxy resin comprising this and another bifunctional epoxy resin

Embedded image (In the formula, n is an integer of 0 or more, Y is an organic divalent group having 6 to 20 carbon atoms, X represents the following structure,

Embedded image m is an integer of 0 or greater, Z _{is, -CH 2 -, -CH (CH} 3)
-, -C (CH ₃ ) ₂ -and -SO _2- . [B]: Particulate toughening agent [C]: Curing agent The epoxy resin composition for a fiber-reinforced composite material of the present invention is cured with one or more epoxy resins represented by the following general formula (I). Energy release rate G of the cured product obtained when the composition is obtained by curing at 130 ° C. for 2 hours.
It is characterized in that the _IC is at least 600 J / m ² .

[0015]

Embedded image (In the formula, n is an integer of 0 or more, Y is an organic divalent group having 6 to 20 carbon atoms, X represents the following structure,

Embedded image m is an integer of 0 or greater, Z _{is, -CH 2 -, -CH (CH} 3)
-, -C (CH ₃ ) ₂ -and -SO _2- . Further, the prepreg of the present invention is characterized in that the above-mentioned epoxy resin composition for a fiber-reinforced composite material is constituted by impregnating a reinforcing fiber with the above-mentioned fiber-reinforced composite material. It is characterized by comprising a cured product of the epoxy resin composition for a fiber-reinforced composite material and reinforcing fibers.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has been studied diligently to provide a fiber reinforced composite material having excellent performance in both heat resistance and impact resistance. When the epoxy resin composition composed of the above was adopted, it was found that such a problem could be solved at once. By adopting such means, the fiber-reinforced composite material has succeeded in achieving both heat resistance and impact resistance.

The component [A] of the present invention has the following general formula:
It may be a single epoxy resin represented by (1) or a mixture of a plurality of epoxy resins including other epoxy resins. As the epoxy resin used here, a compound having two or more epoxy groups in a molecule is used.

[0018]

Embedded image (In the formula, n is an integer of 0 or more, Y is an organic divalent group having 6 to 20 carbon atoms, X represents the following structure,

Embedded image m is an integer of 0 or greater, Z _{is, -CH 2 -, -CH (CH} 3)
-, -C (CH ₃ ) ₂ -and -SO _2- . The particulate toughening agent of the component [B] of the present invention has an effect of improving the toughness of the cured product of the epoxy resin composition containing the same, and the effect is due to the plastic deformation ability of the epoxy resin. Depends on. As an index of the plastic deformation capability, the tensile elongation of the cured product is exemplified, and the tensile elongation is preferably 8% or more, more preferably 10% or more.
Specifically, the lower the crosslink density of the cured epoxy resin, the greater the plastic deformation ability and the greater the effect of improving toughness. However, if the crosslinked density of the cured product is too low, the elastic modulus and heat resistance decrease, which is not preferable.

Therefore, it is preferable that the component [A] has a composition having an appropriate cured product crosslink density. Adjustment of the crosslink density of the cured product is generally performed by blending a plurality of types of epoxy resins having different numbers of functional groups per molecule (in this case, the number of epoxy groups) and adjusting the blending ratio.

In order to obtain an appropriate cured product crosslink density, it is preferable to use a bifunctional epoxy resin (having two epoxy groups per molecule) as a main component of the component [A]. In order to obtain an epoxy resin cured product having well-balanced physical properties, 70 to 100% by weight of the total epoxy resin is required.
Is preferably a bifunctional epoxy resin,
More preferably, it is 100% by weight.

The constituent element [A] may contain, as an optional component other than the bifunctional epoxy resin, a trifunctional or higher epoxy resin (having three or more epoxy groups per molecule). If an epoxy resin having three or more functionalities has too large a functional number, it becomes difficult to develop toughness. Therefore, an epoxy resin having six or less functionalities is preferably used.

The trifunctional or higher functional epoxy resin is effective for improving the elastic modulus and heat resistance of the cured product of the epoxy resin composition. However, if the amount is too large, the crosslink density of the cured product becomes too high and the toughness is high. May not be obtained. The compounding amount of the trifunctional or higher epoxy resin is 0 in the total epoxy resin.
It is preferably about 30% by weight.

As another criterion for optimizing the crosslinking density of the cured epoxy resin, the epoxy equivalent of the component [A] can be used. The epoxy equivalent of component [A] is
It is a value obtained by dividing the mass (g) by the number of moles of the epoxy group contained therein. This can be determined by titration or calculation from the respective epoxy equivalents of the respective epoxy resin raw materials to be blended.

If the epoxy equivalent of the epoxy resin as a whole of the component [A] is large, the crosslink density of the cured product becomes small. Therefore, the epoxy equivalent of the component [A] is preferably 250 or more. On the other hand, if the epoxy equivalent of the component [A] is too large, the elastic modulus and heat resistance may be reduced, or the viscosity may be too high. Therefore, the epoxy equivalent of the component [A] is 250 to 400. Preferably, there is.

As a general criterion for judging the plastic deformation ability of the epoxy resin, the crosslink density is mentioned, and as a quantitative index for controlling the crosslink density, the blending amount of the bifunctional epoxy resin and the epoxy equivalent are described. The chemical structure of the epoxy resin also affects the plastic deformation capacity. In general, the longer the distance between two epoxy groups and the greater the flexibility of the skeleton connecting these two groups, the greater the plastic deformation ability.

For example, polypropylene glycol diglycidyl ether, diglycidyl dimer acid, and the like can be exemplified as resins that enhance the plastic deformation ability. However, when such a resin is added in a large amount, the heat resistance and elastic modulus of the cured product are impaired.

However, it has been found that the epoxy resin represented by the general formula (I) does not impair the heat resistance and the elastic modulus while increasing the plastic deformation ability, so that the epoxy resin represented by the general formula (I) is used. It can be used as a particularly preferred bifunctional epoxy resin in the component [A].
The reason why the epoxy resin represented by the general formula (I) has such an effect is that the urethane structure in the chemical structure forms hydrogen bonds in the cured product, compensating for a decrease in crosslinking density and an increase in the distance between crosslinking points. It is considered to be doing.

The preferred amount of the epoxy resin represented by the general formula (I) is 5 to 50 parts by weight based on 100 parts by weight of the total epoxy resin. If the amount is less than 5 parts by weight, the effect is weak, and if it exceeds 50 parts by weight, it is difficult to control other physical properties (rheology of the uncured resin, mechanical properties of the cured product) by blending other components so as to be suitable for practical use. Become.

The epoxy resin represented by the general formula (I) is the same as the epoxy resin represented by the following general formula (II).
The diisocyanate represented by I) is a catalyst such as a tertiary amine, a quaternary ammonium salt, a quaternary phosphonium salt, a cycloamidine or a salt thereof, a metal chloride / phosphine oxide, a boron trifluoride amine complex, or a fiber metal chelate complex. Obtained by heating down. The conditions for the reaction of forming an oxazolidone ring from an epoxy compound and an isocyanate are described in U.S. Pat. Nos. 3,313,747, 3,334,110 and 3,702,839.
No., U.S. Pat.No. 3,721,650, U.S. Pat.
No. 7406, JP-A-48-103570, JP-A-49-379
It is disclosed in a number of documents such as Japanese Patent Application Laid-Open No. 99-94798, Japanese Patent Application Laid-Open No. 49-94798, Japanese Patent Application Laid-Open No. 49-93491, Japanese Patent Application Laid-Open No. 50-136398, and Japanese Patent Application Laid-Open No. 50-117771.

[0030]

Embedded image (Where m is an integer of 0 or more, and Z is -CH _2- ,
It is a divalent group selected from -CH (CH ₃ )-, -C (CH ₃ ) ₂ -and -SO _2- . OCN-Y-NCO (III) (wherein, Y is an organic divalent group having 6 to 20 carbon atoms.) A general formula which is a raw material of the epoxy resin represented by the general formula (I)
As specific examples of the epoxy resin represented by (II), the following bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin can be used, and as the diisocyanate represented by the general formula (III), Can be used tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

Commercial products of the epoxy resin represented by the general formula (I) include XAC4151 manufactured by Asahi Ciba, which is a reaction product of a bisphenol A type epoxy resin and tolylene diisocyanate.
(Epoxy equivalent 412), XAC4152 (epoxy equivalent 33
8) Alternatively, ACR Epoxy R-1206 (epoxy equivalent: 200) manufactured by AC R Co., Ltd., and ACR Epoxy R-1348 (epoxy equivalent: 350) manufactured by AC R Co., Ltd. can be used.

Bifunctional epoxy resins other than the epoxy resin represented by the general formula (I) which are preferably used in the present invention include bisphenol A type epoxy resins (epoxy resins obtained by the reaction of bisphenol A with epichlorohydrin). ), Bisphenol F type epoxy resin (epoxy resin obtained by reaction of bisphenol F and epichlorohydrin), bisphenol S type epoxy resin (epoxy resin obtained by reaction of bisphenol S and epichlorohydrin), brominated bisphenol A Epoxy resin (epoxy resin obtained by reaction of tetrabromobisphenol A with epichlorohydrin), resorcinol type epoxy resin (epoxy resin obtained by reaction of resorcinol and epichlorohydrin), bifunctional naphthalene epoxy Resin (epoxy resin obtained by reaction of dihydroxynaphthalene and epichlorohydrin), biphenyl type epoxy resin (epoxy resin obtained by reaction of dihydroxybiphenyl or a substituent derivative thereof with epichlorohydrin), fluorene type epoxy resin ( Epoxy resin obtained by the reaction of bishydroxyphenylfluorene and epichlorohydrin) and the like.

Of these, the incorporation of at least one selected from the group consisting of a resorcinol type epoxy resin, a biphenyl type epoxy resin, a bifunctional naphthalene type epoxy resin and a fluorene type epoxy resin is effective for increasing the resin elasticity. .

As a commercially available bisphenol A type epoxy resin, “Epicoat” 825 (epoxy equivalent: 172)
178) “Epicoat” 828 (epoxy equivalent 184)
194), “Epicoat” 834 (epoxy equivalent 23
0 to 270), “Epicoat” 1001 (epoxy equivalent 450 to 500), “Epicoat” 1004 (epoxy equivalent 875 to 975), “Epicoat” 1009 (epoxy equivalent 2400 to 3300) (the above are Yuka Shell Epoxy Co., Ltd.) "Epototo" YD-128 (epoxy equivalents 184-194, manufactured by Toto Kasei Co., Ltd.), "Epiclon" 840 (epoxy equivalents 180-190), "Epiclon" 850 (epoxy equivalents 184-194), "Epiclone""830 (epoxy equivalent: 165-185),
"Epiclon" 1050 (epoxy equivalent 450-50
0) (above, manufactured by Dainippon Ink and Chemicals, Inc.), “Sumi-Epoxy” ELA-128 (Epoxy equivalent 184-1
94, manufactured by Sumitomo Chemical Co., Ltd.), DER331 (epoxy equivalents: 182 to 192, manufactured by Dow Chemical Co., Ltd.) and the like can be used.

As a commercially available bisphenol F type epoxy resin, “Epicoat” 806 (epoxy equivalent: 160
170), "Epicoat" 807 (epoxy equivalent 16
0 to 175) (all manufactured by Yuka Shell Epoxy Co., Ltd.),
"Epiclon" 830 (epoxy equivalents 165 to 180,
Dainippon Ink and Chemicals, Inc.) can be used.

As a commercially available bisphenol S-type epoxy resin, "Denacol" EX-251 (Nagase Kasei Kogyo Co., Ltd., epoxy equivalent: 189) can be used.

Commercially available brominated bisphenol A type epoxy resins include "Epicoat" 5050 (manufactured by Yuka Shell Epoxy, epoxy equivalent: 380-410) and "Epiclon" 152 (manufactured by Dainippon Ink and Chemicals, epoxy equivalent). 340-380), "Sumi-Epoxy" ESB-400T
(Epoxy equivalent: 380-420, manufactured by Sumitomo Chemical Co., Ltd.),
"Epototo" YBD-360 (manufactured by Toto Kasei, epoxy equivalent 350-370) can be used.

As a commercially available resorcinol-type epoxy resin, "Denacol" EX-201 (Epoxy equivalent 118, manufactured by Nagase Kasei Kogyo Co., Ltd.) can be used.

A commercially available biphenyl type epoxy resin is "Epicoat" YX40 which is 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyldiglycidyl ether.
00 (made by Yuka Shell Epoxy Co., epoxy equivalent 180-1
92), "Epicoat" YL61, which is a mixture of 4,4'-dihydroxy-3,3 ', 5,5'-biphenyldiglycidyl ether and 4,4'-dihydroxybiphenyldiglycidyl ether
21H (Yuika Shell Epoxy Co., epoxy equivalent 175)
Can be used.

As a commercial product of a bifunctional naphthalene type epoxy resin, "Epiclon" HP-4032H (manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent: 250) which is 1,6-dihydroxynaphthalenediglycidyl ether may be used. it can.

As commercially available fluorene type epoxy resins, "EPON" HPT resin 1079 (manufactured by Shell Co., epoxy equivalent 250-260), ESF-300 (manufactured by Nippon Steel Chemical Co., Ltd., epoxy equivalent 246) and the like are used. be able to.

When a trifunctional or higher functional epoxy resin is blended, a novolak type epoxy resin (an epoxy resin obtained by reacting novolak with epichlorohydrin), tetrakis (glycidyloxyphenyl) ethane or tris (glycidyloxy) methane is used. Such a polyfunctional glycidyl ether type epoxy resin and a polyfunctional glycidylamine type epoxy resin such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol, and tetraglycidylxylylenediamine can be used.

Commercially available novolak epoxy resins include "Epicoat" 152 (epoxy equivalents 172 to 17).
9), “Epicoat” 154 (epoxy equivalent 176-1)
81) (both manufactured by Yuka Shell Epoxy Co., Ltd.), DER
438 (epoxy equivalents 176-181, manufactured by Dow Chemical Company), "Araldite" EPN1138 (epoxy equivalents 176-181, manufactured by Ciba), "Araldite" EPN113
9 (epoxy equivalents 172-179, manufactured by Ciba) can be used. Commercially available tetraglycidyldiaminodiphenylmethane is "Sumi-Epoxy" ELM434
(Epoxy equivalent: 110 to 130, manufactured by Sumitomo Chemical Co., Ltd.) can be used. Commercially available products of triglycidylaminophenol include Sumi-Epoxy “ELM120 (epoxy equivalent 118, triglycidyl-m-aminophenol).
And "Araldite" MY0510 (manufactured by Sumitomo Chemical Co., Ltd.), which is a triglycidyl-p-aminophenol (epoxy equivalent: 94 to 107, manufactured by Ciba Geigy).

The epoxy resin composition containing the particulate toughening agent of the component [B] is characterized in that if the particles are insoluble in the epoxy resin, the heat resistance of the cured resin is reduced by the epoxy resin composition containing no particles. Heat resistance of the cured product. Further, since the morphology does not change due to the type of the epoxy resin matrix and the curing conditions, stable cured physical properties such as toughness can be obtained.

As the particulate toughening agent unnecessary for the epoxy resin, a thermoplastic resin unnecessary for the epoxy resin, for example, a polyamide particle or a particle containing a rubber phase and unnecessary for the epoxy resin can be used. The latter is generally better.

As the particles containing a rubber phase and insoluble in the epoxy resin, for example, crosslinked rubber particles composed of only the rubber phase or core-shell rubber particles composed of a rubber phase and a resin phase other than rubber can be used.

As the crosslinked rubber particles, for example, particles obtained by copolymerizing a crosslinkable monomer with one or more unsaturated compounds can be used.

Examples of the unsaturated compound include aliphatic olefins such as ethylene and propylene, aromatic vinyl compounds such as styrene and methylstyrene, conjugated diene compounds such as butadiene, dimethylbutadiene, isoprene and chloroprene, methyl acrylate and propyl acrylate. And unsaturated carboxylic esters such as butyl acrylate, methyl methacrylate, propyl methacrylate, and butyl methacrylate; and vinyl cyanide such as acrylonitrile.

Further, as the unsaturated compound, for example, a compound having a functional group reactive with an epoxy resin such as a carboxyl group, an epoxy group, a hydroxyl group and an amino group or an amide group or a curing agent can be used. Examples include acrylic acid, glycidyl methacrylate, vinyl phenol, vinyl aniline, acrylamide, and the like.

Examples of the crosslinkable monomer include compounds having a plurality of polymerizable double bonds in a molecule, such as divinylbenzene, diallyl phthalate, and ethylene glycol dimethacrylate.

These particles can be produced by conventionally known various polymerization methods such as an emulsion polymerization method and a suspension polymerization method. A typical emulsion polymerization method is a method in which an unsaturated compound and a crosslinking monomer are subjected to emulsion polymerization in the presence of a radical polymerization initiator such as a peroxide, a mercaptan, a molecular weight modifier such as a halogenated hydrocarbon, and an emulsifier. After the polymerization conversion rate is reached, a reaction terminator is added to stop the polymerization reaction, and then unreacted monomers of the polymerization system are removed by steam distillation or the like to obtain a copolymer latex. Water is removed from the latex obtained by the emulsion polymerization method to obtain crosslinked rubber particles.

[0052] Commercial products can also be used. As commercially available crosslinked rubber particles, for example, XER-91 (manufactured by Nippon Synthetic Rubber Industries, Ltd.) composed of a crosslinked product of a carboxyl-modified butadiene-acrylonitrile copolymer can be used. Also, products in which crosslinked rubber particles are dispersed in an epoxy resin are commercially available, and these can be used. Typical commercially available products are “Eposet” BPA-323, “Eposet” BPA-307, “Eposet” BPA-601, “Eposet” BPA-604, and “Eposet” BPA in which acrylic rubber particles are dispersed in epoxy resin. -607, "Eposet" HDG-31, (Nippon Shokubai Co., Ltd.), YR-528,
YR-570, YR-516 (manufactured by Toto Kasei) and the like can be used.

The core-shell rubber particles are spherical polymer particles composed of a polymer having a center portion and a surface layer portion different from each other, and simply have a two-phase structure of a core phase and a single shell phase. Multi-core shell rubber particles having a multi-layered structure having a plurality of shell phases, such as a structure serving as a soft shell and a hard shell, are known. Here, soft means a rubber phase, and hard means a resin phase which is not a rubber. In this specification, rubber is used to mean a polymer whose glass transition temperature does not reach room temperature.

Of these, those having a soft core / hard shell structure are preferably used because of their good dispersibility in epoxy resins.

As the core component of the core-shell rubber particles having a soft-core / hard-shell structure, the same polymers as those mentioned as the crosslinked rubber particles are used.

Examples of the shell component include polymers having a glass transition temperature of room temperature or higher, for example, homopolymers such as polystyrene, acrylonitrile, methyl acrylate and methyl methacrylate, methyl methacrylate / alkyl acrylate, and methacrylic / acrylic acid. Or a terpolymer such as styrene / acrylonitrile / glycidyl methacrylic acid. Acrylic acid, methacrylic acid, itaconic acid, glycidyl methacrylic acid, hydroxyethyl methacrylic acid, dimethylaminomethyl having functional groups reactive with epoxy resins such as carboxyl group, epoxy group, hydroxyl group, amino group, amide group, etc. or curing agents It is also possible to copolymerize unsaturated compounds such as methacrylic acid and methacrylamide. As the shell component, it is better to use a polymer having no reactive functional group, such as polymethyl methacrylate,
On the contrary, the dispersibility in the epoxy resin tends to be excellent, which is preferable.

The core-shell rubber particles have a core component content of 10 to 90% by weight and a shell component content of 90 to 1%.
It is preferably in the range of 0% by weight. If the content of the core component is less than 10% by weight, it may be difficult to obtain a sufficient toughness improving effect, and if it exceeds 90% by weight, it may be difficult to completely cover the core with the shell, and the dispersibility may be poor. May be enough.

The core-shell rubber particles can be produced by a known method, for example, a method disclosed in US Pat. No. 4,419,496, European Patent 45,357, JP-A-55-94917. Can be. Commercial products can also be used. Examples of commercially available core-shell rubber particles having a soft-core / hard-shell structure include, for example, “paraloid” EXL-2655 composed of a butadiene-alkyl methacrylate-styrene copolymer.
(Made by Kureha Chemical Industry Co., Ltd.), "Staphyroid" AC made of acrylate / methacrylate copolymer
-3355, "STAPHYLOID" TR-2105, "STAPHYLOID" TR-2102, "STAPHYLOID" T
R-2122, "STAPHYLOID" IM-101, "STAPHYLOID" IM-203, "STAPHYLOID" IM
-301, "STAPHYLOID" IM-401 (manufactured by Takeda Pharmaceutical Co., Ltd.), "PARALOID" EXL-2314 (manufactured by Kureha Chemical Industry Co., Ltd.), "PARALOID" EXL-261
1. "PARALOID" EXL-387 (Rohm
& Haas), “Staphyloid” IM-601 (manufactured by Takeda Pharmaceutical Co., Ltd.) composed of an acrylate / acrylonitrile / styrene copolymer, and the like.

The particles containing the rubber phase and insoluble in the epoxy resin as described above may be used in combination of a plurality of types.

The average particle size of the particulate toughening agent is 10 μm.
m or less, more preferably 5 μm or less. If the particle diameter is too large, it may be difficult to pass through the gaps between the reinforcing fibers when impregnating the reinforcing fibers with the matrix resin, and it may be difficult to uniformly distribute the particles.

The compounding amount of the particulate toughening agent of the component [B] is preferably in the range of 1 to 20 parts by weight based on 100 parts by weight of the component [A], ie, the epoxy resin.
If the amount is less than 1 part by weight, the effect of improving the impact resistance may not be sufficiently obtained, and if the amount is more than 20 parts by weight, the viscosity of the resin composition may become high and it may be difficult to impregnate the reinforcing fibers. .

Examples of the curing agent used as the component [C] include aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone, aliphatic amines such as triethylenetetramine and isophoronediamine, imidazole derivatives, dicyandiamide and tetramethyl. Guanidine, carboxylic anhydride such as methylhexahydrophthalic anhydride, carboxylic acid hydrazide such as adipic hydrazide, carboxylic acid amide, polyphenol compound, polymercaptan, Lewis acid complex such as boron trifluoride ethylamine complex, etc. Can be used.

It is also possible to use an adduct having a curing activity by reacting these curing agents with an epoxy resin.

A microencapsulated product of these curing agents can also be suitably used to enhance the storage stability of the prepreg.

These curing agents can be combined with an appropriate curing accelerator to increase the curing activity. Preferred examples include an example in which a urea derivative or an imidazole derivative is combined with dicyandiamide as a curing accelerator, and an example in which a tertiary amine or an imidazole derivative is combined with a carboxylic anhydride or a polyphenol compound as a curing accelerator.

As the urea derivative, a compound obtained by reacting a secondary amine with an isocyanate, for example, 3-phenyl-1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU) ), 3-
(3-Chloro-4-methylphenyl) -1,1-dimethylurea, 2,4-bis (3,3-dimethylureido) toluene and the like are preferably used.

The epoxy resin composition for a fiber-reinforced composite material of the present invention may contain, as an optional component, a thermoplastic resin soluble in the epoxy resin. By blending a soluble thermoplastic resin with the epoxy resin, the effect of controlling the viscosity of the resin, controlling the handleability of the prepreg, or improving the adhesiveness between the matrix resin and the reinforcing fibers can be obtained.

The thermoplastic resin used here is particularly preferably a thermoplastic resin having a hydrogen-bonding functional group in view of compatibility with the epoxy resin and adhesiveness with the reinforcing fiber.

As the hydrogen bonding functional group, an alcoholic hydroxyl group, an amide group, an imide group, a sulfonyl group and the like can be used.

Examples of the thermoplastic resin having an alcoholic hydroxyl group include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, phenoxy resins, and the like.
As the thermoplastic resin having an amide group, polyamide,
Polyimide can be used as the thermoplastic resin having an imide group, and polysulfone can be used as the thermoplastic resin having a sulfonyl group. Polyamide, polyimide and polysulfone may have a functional group such as an ether bond or a carbonyl group in the main chain. The polyamide may have a substituent at the nitrogen atom of the amide group.

Examples of commercially available thermoplastic resins having an epoxy resin-soluble and hydrogen-bonding functional group include polyvinyl acetal resins such as "Denka Butyral" and "Denka Formal" (manufactured by Denki Kagaku Kogyo Co., Ltd.).
"VINYLEC" (manufactured by Chisso Corporation), "UCAR" PKHP (manufactured by Union Carbide) as a phenoxy resin, "Macromelt" (manufactured by Henkel Hakusui Corporation) as a polyamide resin, "Amilan" CM4000 (manufactured by Toray Industries, Inc.) "Ultem" (manufactured by General Electric) as polyimide, "Matrimid" 5
218 (manufactured by Ciba) as a polysulfone “Victr
ex "(manufactured by Mitsui Toatsu Chemicals, Inc.) and" UDEL "(manufactured by Union Carbide) can be used.

When a thermoplastic resin is contained, it is preferable that the thermoplastic resin is contained in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the epoxy resin, so that the epoxy resin composition has an appropriate viscoelasticity and a good composite material. It is preferable because physical properties can be obtained.

The epoxy resin composition of the present invention may contain components other than these, such as inorganic particles, in addition to the above-described epoxy resin, particulate toughening agent, curing agent, and thermoplastic resin.

As the inorganic particles, silica, alumina, smectite, synthetic mica and the like can be used. These inorganic particles are blended mainly for rheological control, that is, for thickening and imparting thixotropic properties.

The resin composition for a fiber-reinforced composite material of the present invention is characterized in that a cured product of a matrix resin of the fiber-reinforced composite material has high toughness and good heat resistance. Specifically, for the cured product obtained by curing at 130 ° C. for 2 hours, the energy release rate G _{IC as} an index of toughness is 6
It is preferably at least 00 J / m ² , and the glass transition temperature, which is an index of heat resistance, is preferably at least 130 ° C.

By impregnating the reinforcing fibers with the epoxy resin composition of the present invention, a prepreg as an intermediate substrate of the fiber-reinforced composite material is produced.

As the reinforcing fiber, glass fiber, carbon fiber, aramid fiber, boron fiber, alumina fiber, silicon carbide fiber and the like are used. Although two or more of these fibers may be used in combination, carbon fibers are particularly preferred in order to obtain a lighter and more durable molded product. In order to produce lighter sporting goods such as golf shafts and fishing rods, it is preferable to use carbon fibers having a high elastic modulus for the prepreg so that a small amount of material can express sufficient rigidity of the product. The elastic modulus of such a carbon fiber is preferably 200 GPa or more.
More preferably, it is 0 to 800 GPa.

The form and arrangement of the reinforcing fibers are not particularly limited.
For example, a long fiber, a single tow, a woven fabric, a mat, a knit, a braid, or the like that is aligned in one direction is used.

The prepreg is produced by a wet method in which the matrix resin is dissolved in a solvent such as methyl ethyl ketone or methanol to reduce the viscosity and impregnated, or a hot melt method in which the viscosity is decreased by heating and impregnated. .

The wet method is a method in which a reinforcing fiber is immersed in an epoxy resin composition solution, then pulled up, and the solvent is evaporated using an oven or the like to obtain a prepreg.

The hot melt method is a method of directly impregnating a reinforcing fiber with an epoxy resin composition whose viscosity has been reduced by heating, or a method in which a film in which the epoxy resin composition is once coated on a release paper or the like is first prepared and then reinforced. This is a method of producing a prepreg impregnated with a resin by laminating the film from both sides or one side of the fiber and applying heat and pressure. The hot melt method is preferable because there is no solvent remaining in the prepreg.

The molding of the composite using the prepreg can be carried out by laminating the prepreg and then heating and curing the resin while applying pressure to the laminate.

The method for applying heat and pressure includes press molding, autoclave molding, bagging, wrapping tape, and internal pressure molding. Particularly for sports goods, the wrapping tape method and internal pressure molding are used. It is preferably adopted.

The wrapping tape method is a method in which a prepreg is wound around a core metal such as a mandrel to form a cylindrical object, and is suitable for producing a rod-shaped body such as a golf shaft and a fishing rod. Specifically, the prepreg is wound around the mandrel, and for fixing the prepreg and applying pressure,
A wrapping tape made of a thermoplastic resin film is wrapped around the outside of the prepreg, and the resin is heated and cured in an oven, and then the core is removed to obtain a cylindrical molded body.

In the internal pressure forming method, a preform in which a prepreg is wound around an internal pressure applying body such as a thermoplastic resin tube is set in a mold, and then a high pressure gas is introduced into the internal pressure applying body to reduce the pressure. This is a method in which the mold is heated and molded simultaneously with the application. It is suitably used when molding a complicated shape such as a golf shaft, a bat, a racket such as tennis or badminton.

Further, a method in which a reinforcing fiber is directly impregnated with the epoxy resin composition of the present invention without using a prepreg and then heat-cured, such as a hand lay-up method, a filament winding method, a pultrusion method, and a resin
A fiber-reinforced composite material can also be produced by a molding method such as a transfer molding method. In these, a method of mixing two liquids of the present invention, ie, the main component composed of the constituents [A] and [B] and the curing agent composed of the constituent [C], immediately before molding can be applied.

The fiber-reinforced composite materials obtained by various molding methods are excellent in impact resistance, so that they can be used as balling equipment such as golf shafts, baseball bats, rackets such as tennis and badminton, sticks such as hockey, and aircraft. Used as parts.

[0088]

The present invention will be described in more detail with reference to the following examples. The measurement of the elongation and toughness of the cured resin, the preparation of the prepreg, the preparation of the fiber-reinforced composite material, the measurement of the Charpy impact value and the glass transition temperature were performed under the following conditions.

A. Measurement of Tensile Elongation of Cured Resin The resin composition was heated to 80 ° C. and injected into a mold.
The resin was cured in an oven at 30 ° C. for 2 hours to prepare a resin cured product plate having a thickness of 2 mm. Next, JI from the cured resin plate
According to S-K7113, a small 1 (1/2) type test piece was cut out and the tensile elongation was determined.

B. Measurement of the toughness of the cured resin The resin composition was heated to 80 ° C. and injected into a mold.
The resin was cured in an oven at 30 ° C. for 2 hours to prepare a cured resin plate having a thickness of 6 mm. Then, from the plate of the cured resin, A
A test piece for the SENB method described in STM D5045-93 was cut out, and using this, the stress intensity factor K _IC was determined by the SENB method.
Was measured, and the energy release rate G _IC was determined from the value, the tensile modulus E and Poisson's ratio ν, which were separately determined by a tensile test, according to the following equation.

G _IC = (1−ν ² ) K _IC ² / EC. Preparation of Prepreg An epoxy resin composition was applied on release paper using a reverse roll coater to prepare a resin film. Next, two resin films are stacked on both sides of carbon fiber “Treca” T700S (manufactured by Toray Industries, Inc.) having a tensile modulus of 230 GPa arranged in one direction in a sheet shape, and the resin is impregnated with heat and pressure. A unidirectional prepreg having a carbon fiber weight of 150 g / m ² and a matrix resin weight fraction of 33% was prepared.

D. Preparation of fiber reinforced composite material 21 unidirectional prepregs were laminated so that the direction of the reinforcing fiber was the same, and then molded at 135 ° C. for 2 hours at 0.29 MPa (3 kgf / cm ² ) using an autoclave to obtain a fiber reinforced composite material. A plate of material was obtained.

E. Charpy impact test of fiber reinforced composite material A test piece of 10 mm width and 80 mm length was cut out from the fiber reinforced composite material and weighed 300 kg · cm to give a flat wise impact, that is, JIS by giving an impact from a direction perpendicular to the surface of the unidirectional material. A Charpy impact test was performed according to K 7077. Notches were not introduced into the test pieces.

F. Measurement of glass transition temperature of cured resin and fiber reinforced composite material The midpoint glass transition temperature was determined by the DSC method according to JIS-K7121. The measurement device includes METTLER DSC-T3
000 system (manufactured by Mettler), and the heating rate is 4
0 ° C./min.

Example 1 A resin composition was obtained by mixing the following raw materials.

20 parts by weight of epoxy resin represented by the general formula (I) (XAC4151 manufactured by Asahi Ciba Co., Ltd.) 40 parts by weight of bisphenol A type epoxy resin (Epicoat 1001 manufactured by Yuka Shell Epoxy) Bisphenol F-type epoxy resin 20 parts by weight ("Epiclon" 830, manufactured by Dainippon Ink and Chemicals, Inc.) Brominated bisphenol A type epoxy resin 20 parts by weight ("Epiclon" 152, manufactured by Dainippon Ink and Chemicals, Inc.) Core shell 10 parts by weight of rubber particles (manufactured by Takeda Pharmaceutical Co., Ltd., “Staphyroid” IM-101) 4 parts by weight of dicyandiamide (manufactured by Yuka Shell Epoxy Co., Ltd., “Epicure” DICY7) 3- (3,4-dichlorophenyl) -4 parts by weight of 1,1-dimethylurea (DCMU-99, manufactured by Hodogaya Chemical Industry Co., Ltd.) Polyvinyl formal tree Fat 5 parts by weight ("Vinilec" K, manufactured by Chisso Corporation) The epoxy equivalent of the epoxy resin in this resin composition was 26.
3.

A cured product obtained by curing this resin composition at 130 ° C. for 2 hours had a tensile elongation of 11%, an energy release rate G _IC of 1050 J / m ² and a glass transition temperature of 142 ° C.

A unidirectional prepreg was prepared using this resin composition, and a Charpy impact test was performed using the prepreg to prepare a fiber-reinforced composite material. As a result, the impact value was as good as 138 kJ / m ^2. showed that. The glass transition temperature was 138 ° C.

Example 2 A resin composition was obtained by mixing the following raw materials.

25 parts by weight of epoxy resin represented by the general formula (I) (XAC4151 manufactured by Asahi Ciba Co., Ltd.) 45 parts by weight of bisphenol A type epoxy resin (Epicoat 1009 manufactured by Yuka Shell Epoxy Co., Ltd.) bisphenol F-type epoxy resin 10 parts by weight ("Epiclon" 830, manufactured by Dainippon Ink and Chemicals, Inc.) Brominated bisphenol A type epoxy resin 10 parts by weight ("Epiclon" 152, manufactured by Dainippon Ink and Chemicals, Inc.) amino Phenol triglycidyl ether 10 parts by weight (Sumitomo Chemical Co., Ltd., "Sumi-Epoxy" ELM-120) Crosslinked rubber particles 10 parts by weight (Nippon Synthetic Rubber Industry Co., Ltd., XER-91) Dicyandiamide 4 parts by weight (oil) "Epicure" DICY7, manufactured by Kabushiki Kaisha Epoxy Co., Ltd. 4- (3,4-dichlorophenyl) -1,1-dimethylurea 4 weight Part (DCMU-9, manufactured by Hodogaya Chemical Industry Co., Ltd.) 7 parts by weight of polyvinyl formal resin ("Vinilec" K, manufactured by Chisso Corporation) The epoxy equivalent of the epoxy resin in this resin composition is 29.
7

A cured product obtained by curing the resin composition at 130 ° C. for 2 hours has a tensile elongation of 9% and an energy release rate G _IC of 9%.
The glass transition temperature was 00 J / m ² and 147 ° C.

A unidirectional prepreg was prepared using this resin composition, and a Charpy impact test was performed using the prepreg to prepare a fiber-reinforced composite material. As a result, a good impact value of 132 kJ / m ² was obtained. showed that. The glass transition temperature was 142 ° C.

Comparative Example 1 A resin composition was obtained by mixing the following raw materials.

20 parts by weight of polypropylene glycol diglycidyl ether (“Epolite” 400P, manufactured by Kyoeisha Chemical Co., Ltd., epoxy equivalent 320 to 360) 40 parts by weight of bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., “Epicoat”) "1001) Bisphenol F type epoxy resin 20 parts by weight (" Epiclon "830, manufactured by Dainippon Ink and Chemicals, Inc.) Brominated bisphenol A type epoxy resin 10 parts by weight (manufactured by Dainippon Ink and Chemicals," Epiclon ""152) 10 parts by weight of core-shell rubber particles (manufactured by Takeda Pharmaceutical Co., Ltd.," Staphyroid "IM-101) 4 parts by weight of dicyandiamide (manufactured by Yuka Shell Epoxy Co., Ltd.," Epicure "DICY7) 3- (3, 4-Dichlorophenyl) -1,1-dimethylurea 4 parts by weight (Hodogaya Chemical Co., Ltd.) Ltd., DCMU-99) a polyvinyl formal resin 8 parts by weight (Chisso Corp., "Vinylec" K) epoxy equivalent of the epoxy resin in the resin composition 31
4.

A cured product obtained by curing this resin composition at 130 ° C. for 2 hours had a tensile elongation of 11%, an energy release rate G _IC of 940 J / m ² , and a glass transition temperature of 111 ° C.

A unidirectional prepreg was prepared using this resin composition, and a Charpy impact test was conducted by preparing a fiber-reinforced composite material using the prepreg. As a result, a good impact value of 135 kJ / m ² was obtained. However, the glass transition temperature was as low as 107 ° C.

[0107]

According to the present invention, the fiber reinforced composite material obtained by the prior art can be obtained with a smaller amount of material because it has higher impact resistance than the fiber reinforced composite material obtained by the prior art and does not impair the heat resistance. Impact resistance and heat resistance equivalent to those of the material can be obtained, and a lightweight design is possible.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 21:00)

Claims (11)

[Claims] 1. At least the following components [A] and [B]
And [C]. An epoxy resin composition for a fiber-reinforced composite material. [A]: an epoxy resin represented by the general formula (I), or
Epoxy resin comprising this and other bifunctional epoxy resin (Where n is an integer of 0 or more, Y is an organic divalent group having 6 to 20 carbon atoms, X represents the following structure, m is an integer of 0 or greater, Z _{is, -CH 2 -, -CH (CH} 3)
-, -C (CH ₃ ) ₂ -and -SO _2- . [B]: Particulate toughening agent [C]: Curing agent 2. An epoxy resin represented by the general formula (I) wherein the compounding amount of the epoxy resin represented by the general formula (I) is 5 to 50 parts by weight based on 100 parts by weight of the component [A]. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the total amount of the resin and the other bifunctional epoxy resin is 70 to 100 parts by weight based on 100 parts by weight of the component [A]. 3. The epoxy resin composition of the component [A] has an epoxy equivalent of 250 to 250.
The epoxy resin composition for a fiber-reinforced composite material according to claim 1 or 2, wherein 4. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the particulate toughening agent of the component [B] is a particle containing a rubber phase and being insoluble in an epoxy resin. 5. The epoxy resin composition for a fiber-reinforced composite material according to claim 4, wherein the particulate toughening agent of the component [B] is a crosslinked rubber particle. 6. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the particulate toughening agent is a core-shell rubber particle comprising a soft core and a hard shell. 7. The particulate toughening agent of component [B] has an average particle diameter of 10 μm or less.
The epoxy resin composition for a fiber-reinforced composite material according to any one of the above. 8. The method according to claim 1, wherein the particulate toughening agent of the component [B] is contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the epoxy resin. Epoxy resin composition for fiber reinforced composite materials. 9. A composition comprising at least one epoxy resin represented by the following general formula (I) and a curing agent,
An epoxy resin composition for a fiber-reinforced composite material, wherein the cured product has an energy release rate G _IC of at least 600 J / m ² when cured at 30 ° C. for 2 hours. Embedded image Wherein n is an integer of 0 or more, Y is an organic divalent group having 6 to 20 carbon atoms, X represents the following structure, m is an integer of 0 or greater, Z _{is, -CH 2 -, -CH (CH} 3)
-, -C (CH ₃ ) ₂ -and -SO _2- . ) 10. A prepreg, characterized in that a reinforcing fiber is impregnated with the epoxy resin composition for a fiber-reinforced composite material according to claim 1. 11. A fiber-reinforced composite material comprising a cured product of the epoxy resin composition for a fiber-reinforced composite material according to claim 1, and a reinforcing fiber.