JP2003301029A - Epoxy resin composition and prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an epoxy resin composition which has storage stability for a long time, excellent handling property, a satisfactory curing rate at a predetermined temperature and suffices excellent mechanical strength, heat resistance of a cured product, and to provide a prepreg using the same. <P>SOLUTION: The epoxy resin composition which comprizes (A) an epoxy resin, (B) a curing agent and (C) at least one compound selected from among imidazole derivatives and urea derivatives is characterized in that it contains 0.03-0.3 wt.% of hydrolyzable chlorine and has a glass transition temperature from -10 to 15°C. A prepreg containing the resin composition and a reinforcing fiber is also provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a one-pack type epoxy resin which is excellent in storage stability and mechanical strength characteristics after curing and can be suitably used as a matrix resin for fiber-reinforced composite materials, adhesive applications and the like. The present invention relates to a composition and a prepreg that can be suitably used as an intermediate base material for obtaining a fiber-reinforced composite material.

[0002]

2. Description of the Related Art A one-pack type epoxy resin composition comprising an epoxy resin composed of a compound having an epoxy group in the molecule and a curing agent thereof has excellent mechanical strength, chemical resistance, heat resistance, It is used in paints, paving materials, adhesives, matrix resins for fiber-reinforced composite materials, etc. because of its good adhesion to base materials such as metal members and reinforcing fibers.

Fiber-reinforced composite materials are used for aerospace, general industrial applications such as structural members of automobiles and ships, bathtubs and helmets, and also for sports equipment such as fishing rods and golf shafts due to their excellent strength characteristics. Widely used for.

Various molding methods are known to obtain a fiber-reinforced composite material. For example, a prepreg obtained by impregnating a reinforced fiber with an uncured curable resin composition is used as an intermediate substrate, and a plurality of prepregs are laminated. There is a method of obtaining a fiber reinforced composite material by curing the resin by heating and pressure treatment.

The properties required for the curable resin used for these purposes include mechanical properties such as excellent strength and toughness after curing and heat resistance, as well as storage stability at room temperature and appropriate flow properties. Examples include tackiness, handleability such as flexibility when formed into a sheet, and rapid curing when heated to a predetermined temperature for shortening the molding cycle.

Various methods have been studied so far as means for achieving storage stability at room temperature and appropriate curability upon heating. For example, a method of neutralizing or acidifying an acidic or basic compound into a neutral salt or complex compound and activating it by dissociating by heating, or a so-called microcapsule type curing in which a curing agent is finely wrapped with a polymer. And a method in which a curing agent that is crystalline and has a high melting point and is incompatible with the epoxy resin at room temperature is dispersed in the epoxy resin and dissolved by heating. However, although these improve storage stability at room temperature to some extent, it cannot be said that they are still sufficient techniques in consideration of physical properties of cured products, required properties such as resin and prepreg handleability, and manufacturing costs. It was

Further, Japanese Patent Laid-Open No. 4-249521 discloses a technique of controlling the amount of hydrolyzable chlorine to enhance the storage stability of the epoxy resin composition at room temperature. Since the prepreg is simply controlled, the prepreg becomes excessively sticky, the adhesive strength between the prepregs is insufficient, and the handleability is poor, or the resin flow characteristics are inadequate and a fiber-reinforced composite material with a desired fiber content is obtained. It was not suitable for practical use because it was difficult and the strength characteristics of the obtained fiber reinforced composite material were not always sufficient.

[0008]

In view of such background of the prior art, the present invention has long-term storage stability, excellent handleability, sufficient curing speed at a predetermined temperature, and excellent cured product. Another object of the present invention is to provide an epoxy resin composition satisfying the mechanical strength and heat resistance, and a prepreg using the same.

[0009]

The present invention employs the following means in order to solve the above problems. That is, the epoxy resin composition of the present invention comprises the following constituent elements (A), (B) and (C), contains 0.03 to 0.3% by weight of hydrolyzable chlorine, and has a glass transition temperature. It is characterized in that Tg is −10 ° C. to 15 ° C. (A) Epoxy resin (B) Hardener (C) At least one compound selected from imidazole derivative and urea derivative The prepreg of the present invention is characterized by containing such a resin composition and reinforcing fibers. It is a thing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

In the present invention, by containing an appropriate amount of hydrolyzable chlorine in the resin composition, both storage stability at room temperature and appropriate curing activity at the time of heat curing are satisfied, and further, the resin composition is not By controlling the glass transition temperature Tg (hereinafter referred to as uncured resin Tg) in the cured state within an appropriate range, it is also extremely remarkable that excellent handling properties such as appropriate flow characteristics, adhesiveness and flexibility are achieved. Can be obtained.

The resin composition of the present invention contains a component called hydrolyzable chlorine in an amount of 0.03 to 100% by weight of the resin composition.
It is necessary to contain 0.3% by weight. Here, the hydrolyzable chlorine is a by-product generated during the reaction of epichlorohydrin with a compound having active hydrogen such as a hydroxyl group or an amino group in the production process of an epoxy resin, and can be quantified by the method described below.

The resin composition of the present invention contains, as an essential component, the component (C) which acts as a curing accelerator of (B) in addition to the component (B) which is a curing agent. It is considered that degradable chlorine interacts with the constituent element (C) to suppress the curing-accelerating activity of the constituent element (C) at room temperature, resulting in long-term storage stability at room temperature.

The amount of hydrolyzable chlorine contained in the resin composition of the present invention is 0.03 to 0.
It is necessary that the content is 3% by weight, and more preferably 0.
It is from 05 to 0.2% by weight. If the amount of such hydrolyzable chlorine is less than 0.03% by weight, the storage stability at room temperature may not be sufficient, and if it exceeds 0.3% by weight, the curing rate will be slow and the molding cycle will be lengthened. Alternatively, there may be a problem that the resin flow during heat curing becomes too large.

The amount of hydrolyzable chlorine can be achieved by, for example, adding an appropriate amount of an epoxy resin raw material having a known hydrolyzable chlorine content to the constituent element (A). Also, a compound having a 1,2-propylene chlorohydrin group in the molecule can be added at the time of resin preparation.

Further, in the present invention, it is necessary to control the uncured resin Tg of the resin composition within a predetermined range.
By setting the amount of hydrolyzable chlorine and the uncured resin Tg within a predetermined range at the same time, not only the storage stability at room temperature reaches a target level, but also appropriate flow characteristics, tackiness, and
It also achieves excellent handling properties such as flexibility.

The uncured resin Tg of the resin composition of the present invention is −
It is necessary to be 10 to 15 ° C, and -10 to 10 ° C.
Is more preferable, and it is further preferable that the temperature is -5 to 8 ° C.

When the uncured resin Tg is less than -10 ° C, the fluidity of the resin composition at room temperature is too large and the resin composition retains its form when used as a sheet adhesive or a matrix resin for prepreg. In some cases, it may be difficult or the surface may be excessively sticky, and the workability of sticking it to a base material or laminating a prepreg may deteriorate. When the uncured resin Tg is higher than 15 ° C., the adhesiveness of the resin composition at room temperature is lowered to make it difficult to stick to the substrate, or the flexibility is lowered to make it difficult to deform according to the shape of the substrate. There is. In particular,
In the case of prepreg using reinforcing fibers with high elastic modulus,
The flexibility of the reinforcing fiber tends to be impaired due to its rigidity, and it is important to control the uncured resin Tg.

The uncured resin Tg is composed of the constituent element (A).
This can also be achieved by adjusting the chemical structure of the epoxy resin component used for and the ratio thereof, or by including an appropriate amount of thermoplastic resin in the resin composition.

Generally, in a one-pack type epoxy resin composition, the reaction between the epoxy resin and its curing agent gradually progresses during storage, and the uncured resin Tg gradually changes during storage. There is.

The uncured resin Tg in the present invention is a value measured after the resin composition is prepared and the resin is not substantially cured.

Here, the fact that the curing of the resin has not substantially progressed means that the total weight of the constituents (A), (B) and (C) remaining unreacted in the resin composition is W ₁ , When the total weight of the reaction products derived from any of the elements (A), (B) and (C) is W ₂ , the degree of cure calculated by the following formula is 5% or less, preferably 3% or less. That is the case.

Curing degree (%) = 100 × W ₂ / (W ₁ +
W ₂ ) The weight of the organic component which has become insoluble in either the solvent of methanol or chloroform in the resin composition is included in W 2.

The epoxy resin which is the constituent element (A) of the present invention has two or more epoxy groups in the molecule, but at least one is contained. In addition to the compound having two or more epoxy groups, a compound having one epoxy group in the molecule may be contained. These epoxy resins are not particularly limited, but in particular, an epoxy resin produced by using epichlorohydrin as one of the starting materials can be preferably contained.

Epoxy resins using epichlorohydrin as a starting material include glycidyl ether type epoxy resins obtained from compounds having a hydroxyl group in the molecule, glycidyl amine type epoxy resins obtained from compounds having an amino group in the molecule, and isocyanuric acid. Heterocyclic epoxy resins such as the obtained triglycidyl isocyanurate are mentioned, and these can be used alone or in combination of two or more kinds.

In the present invention, the component (A) 1 is used in order to give the cured product of the resin sufficient elongation and toughness.
70 to 100 of the bifunctional epoxy resin in 100% by weight.
It is preferably contained in an amount of, preferably 85 to 100% by weight. When the compounding ratio of such a bifunctional epoxy resin is less than 70% by weight, elongation and toughness may be insufficient and the strength of the obtained material may be reduced.

Specific examples of the bifunctional epoxy resin include:
Obtained from bisphenol A type epoxy resin obtained from bisphenol A and hydrogenated product thereof, bisphenol F type epoxy resin obtained from bisphenol F and hydrogenated product thereof, bisphenol S type epoxy resin obtained from bisphenol S, and tetrabromobisphenol A Bisphenol type epoxy resin such as tetrabromobisphenol A type epoxy resin, bisphenol AD type epoxy resin obtained from bisphenol AD,
Resorcin diglycidyl ether, hydroquinone diglycidyl ether, 4,4′-dihydroxy-3,3 ′,
5,5′-tetramethylbiphenyl diglycidyl ether, 1,6-dihydroxynaphthalene diglycidyl ether, aniline diglycidyl amine, o-toluidine diglycidyl amine, 9,9-bis (4-hydroxyphenyl) fluorene Isocyanate modified products obtained by reacting difunctional epoxy resins such as diglycidyl ether and bisphenol A type epoxy resins with diisocyanates such as tolylene diisocyanate, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, and hexahydrophthalic acid Diglycidyl ester, hexahydroterephthalic acid diglycidyl ester, dimer acid diglycidyl ester, 1,4-di-tert-butyl-2,5-bis (2,3-epoxypropoxy)-
Reaction product of benzene, 2,2'-dimethyl-4,4'-dihydroxy-5,5'-di-tert-butyldiphenyl sulfide and chloromethyloxirane, 4,
Examples include a reaction product of 4′-methylenebis (2,6-dimethylphenol) and chloromethyloxirane, a polyepoxide obtained by oxidizing a compound having two double bonds in the molecule, and the like. These may be used alone or A plurality of them can be used in combination.

Further, the component (A) in the present invention contains an alcoholic hydroxyl group in the molecule for the purpose of exhibiting good adhesion to reinforcing fibers and the like, and high degree of elongation and toughness of the cured product. Component (A) 1 having a component having two or more
It can be contained in an amount of 10 to 100% by weight, more preferably 20 to 90% by weight, based on 00% by weight. If the compounding ratio is less than 20% by weight, the effect of improving the adhesiveness may not be sufficient.

Among the components having two or more alcoholic hydroxyl groups in the molecule, those having a molecular weight of more than 400 are combined with a component having a molecular weight of 400 or less so that the uncured resin Tg falls within the above range. It is possible to control.

When a large amount of alcoholic hydroxyl groups is present in the resin composition, the reaction between the constituent element (A) and the constituent element (B) is promoted, which may impair the storage stability at room temperature. As described above, by containing an appropriate amount of hydrolyzable chlorine, sufficient storage stability can be achieved even if the alcoholic hydroxyl group content is increased.

Examples of the component having two or more alcoholic hydroxyl groups in the molecule include a bisphenol A type epoxy resin represented by the following general formula (3) and a bisphenol F type epoxy resin represented by the general formula (4). A polymer having a degree of polymerization n of 2 or more, or a polyglycidyl ether of a polyol such as sorbitol or polyglycerin can be preferably used.

[0032]

[Chemical 3]

[0033]

[Chemical 4]

"Epicoat" as a bisphenol A type epoxy resin containing a large amount of components having two or more hydroxyl groups
(Registered trademark) 1001 (epoxy equivalent), "Epicoat" Epicoat "1003 (epoxy equivalent 670-77)
0), "Epicoat" 1004 (epoxy equivalent 875-
975), "Epicoat" 1009 (epoxy equivalent 24
00-3300), "Epicoat" 1010 (epoxy equivalent 3,000-5000), and as bisphenol F type epoxy resin "Epicoat" 4004P (epoxy equivalent 880), "Epicoat" 4007P (epoxy equivalent 2270), "Epicoat" 4010P (epoxy) Equivalent 4400), "Epicoat" 4110 (epoxy equivalent 3
500 to 4000) (all manufactured by Japan Epoxy Resins Co., Ltd.) and the like can be used, and these are used as the resin composition (A) 1
When it is contained in an amount of 20 to 100% by weight in 00% by weight, the amount of the component having two or more hydroxyl groups can be 10% by weight or more.

The component (A) of the present invention has a partial structure represented by the following general formula (1) or (2), and
A component having more than one epoxy group can be included.

[0036]

[Chemical 5]

(However, each R independently represents an arbitrary organic residue)

[0038]

[Chemical 6]

(However, each R independently represents an arbitrary organic residue.) Including the component having such a structure may further enhance the storage stability at room temperature.
When the resin contains a large amount of a compound having an alcoholic hydroxyl group, the presence of the alcoholic hydroxyl group may increase the curing activity of the constituent (B), which may impair the storage stability at room temperature. Even in such a case, the partial structure represented by the general formula (1) or (2) can interact with the alcoholic hydroxyl group and suppress the high activation of the component (B) by the alcoholic hydroxyl group. is there.

The compounding amount of the component having a partial structure represented by the general formula (1) or (2) is preferably 1 to 80% by weight in 100% by weight of the constituent element (A), and 5 to 50% by weight.
More preferably, it is wt%. If the blending amount is less than 1% by weight, the stability imparting effect may not be sufficient, and if the blending amount exceeds 80% by weight, the cured product may absorb moisture to deteriorate the physical properties.

The compound having a partial structure represented by the general formula (1) is not particularly limited, but N-glycidyl phthalimide obtained from phthalimide and epichlorohydrin, N-glycidyl-derived from 1,8-naphthalimide and epichlorohydrin. 1,8-naphthalimide,
Triglycidyl isocyanurate derived from isocyanuric acid, diallyl monoglycidyl isocyanurate,
Examples thereof include monoallyl diglycidyl isocyanurate, and these may be used alone or in combination of two or more.

Commercially available epoxy resins which can be used as a compound having a partial structure represented by the general formula (1) include:
"Denacol" (registered trademark) EX731 (manufactured by Nagase Chemtex Co., Ltd.), which is N-glycidyl phthalimide,
DA- which is diallyl monoglycidyl isocyanurate
MGIC (manufactured by Shikoku Chemicals Co., Ltd.) and the like can be exemplified.

The compound having a partial structure represented by the general formula (2) is not particularly limited, but bisphenol A is used.
It is possible to use an isocyanate-modified epoxy resin obtained by reacting an epoxy resin such as a type epoxy resin or a bisphenol F type epoxy resin with an isocyanate compound such as tolylene diisocyanate.

Commercially available epoxy resins which can be used as a compound having a partial structure represented by the general formula (2) include:
Examples include isocyanate-modified epoxy resins such as AER4152 and XAC4151 manufactured by Asahi Kasei Epoxy Co., Ltd.

The component (B) of the present invention is not particularly limited as long as it does not correspond to the component (C) among those having a function of curing an epoxy resin, and it is not limited to amine-based curing agents and acid anhydride-based curing agents. A phenolic curing agent or the like can be used.

As the amine-based curing agent, for example, 4,
Aromatic amines such as 4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, Aliphatic amines such as bis (aminomethyl) norbornane, bis (4-aminocyclohexyl) methane, dimer acid esters of polyethyleneimine, tetramethylguanidine,
Organic acid dihydrazides such as dicyandiamide, adipic acid hydrazide and naphthalene dicarboxylic acid hydrazide,
Examples thereof include those obtained by modifying an amine having active hydrogen with an epoxy compound, acrylonitrile, phenol and a compound such as formaldehyde, thiourea, and the like, and these can be used alone or in combination of two or more.

Examples of the acid anhydride type curing agent include 1-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and carboxylic acid anhydrides such as methylnadic acid anhydride. These can be used alone or in combination of two or more.

Examples of the phenol-based curing agent include polyphenol compounds such as novolac resins and bisphenol compounds such as 4,4'-isopropylidenediphenol and 4,4'-sulfonyldiphenol. These may be used alone or in combination. It can be used by mixing.

The constituent element (B) of the present invention is, for example, stability in the resin blending step, storage stability at room temperature, or stability against heat history received in the step of impregnating the reinforcing fiber with the resin composition. It is preferred to have a heat-activated latent potential.

Here, the thermal activation type latent property is a state in which the activity is low as it is, but it undergoes a phase change or a chemical change by receiving a constant heat history and changes to a high activity state. Means In the following description, the term latent means a heat activated type latent.

In the present invention, as a method for imparting latent potential, a method of blending a particulate curing agent in a state of being dispersed without being dissolved in an epoxy resin is preferably used. When they are subjected to a certain heat history, they are dissolved in the epoxy resin to become a homogeneous phase and become highly active.

The particulate latent curing agent has a melting point of 80 to 3
The temperature is preferably 00 ° C, more preferably 100 to 250 ° C. If the melting point is less than 80 ° C, sufficient latent properties may not be obtained, and if it exceeds 300 ° C, sufficient activity may not be obtained at the curing temperature.

As the particulate latent curing agent, dicyandiamide (melting point: 209 ° C.), salicylic acid hydrazide (melting point: 152 ° C.), adipic acid dihydrazide (melting point:
177-183 ° C), terephthalic acid dihydrazide (melting point 194 ° C), 2,6-naphthoic acid dihydrazide (melting point:
224 ° C), isophthalic acid dihydrazide (194 ° C),
Sebacic acid dihydrazide (melting point: 186-188 ° C.),
1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin (melting point: 118 to 124 ° C.), 7,
11-octadecadiene-1,18-dicarbohydrazide (melting point: 160 ° C), eicosane diacid dihydrazide (melting point: 180 ° C), 4,4'-diaminodiphenyl sulfone (melting point: 175 ° C), 3,3 ' -Diaminodiphenyl sulfone (melting point: 170 ° C), 4,4'-diaminodiphenylmethane (melting point: 92 ° C), 1,1-bis (4
-Hydroxyphenyl) cyclohexane (melting point: 189
C.), 4,4-dihydroxybenzophenone (melting point: 2
16-218 ° C.), 4,4′-isopropylidenediphenol (melting point: 158-159 ° C.), 4,4 ′-(1,
3-Phenylenediisopropylidene) bisphenol (melting point: 135-139 ° C.), 4,4 ′-(1,4-phenylenediisopropylidene) bisphenol (melting point:
193 to 195 ° C.), 4,4′-sulfonyldiphenol (melting point: 245 to 247 ° C.), 4,4′-biphenol (melting point: 282 to 284 ° C.) and the like. Can be used.

In particular, when good curability at a low temperature of about 80 ° C. to 100 ° C. is required, an amine adduct type curing agent “Amicure” (registered trademark) manufactured by Ajinomoto Co., Inc.
PN-23, MY-24, "Fujicure" (registered trademark) FXE-1000, FXR-10 manufactured by Fuji Kasei Kogyo Co., Ltd. as having an active hydrogen moiety and a catalyst moiety in the molecule.
30, H3615, H4070, H3 manufactured by ACR Co., Ltd.
293, H3366, H3849, H3670, microcapsule type hardener "Novacure" (registered trademark) HX3721, HX3722, etc. manufactured by Asahi Kasei Co., Ltd. can be contained in the component (B), or these can be used alone or Multiple combinations can be used.

As the component (C) of the present invention, at least one selected from imidazole derivatives and urea derivatives is used. In particular, from the viewpoint of room temperature stability and the like, it is more preferable to use a solid imidazole derivative or urea derivative dispersed in the resin composition.

Examples of the imidazole derivative which can be used as the constituent element (C) include 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1- (2-cyanoethyl) -2-phenylimidazole, Alternatively, an addition product of an imidazole derivative and a glycidyl compound, a salt of an imidazole derivative with an organic acid such as trimellitic acid, isocyanuric acid, or the like can be given.

The urea derivative which can be used as the constituent element (C) includes 1- (3,4-dichlorophenyl) -3,3-dimethylurea, 1- (4-chlorophenyl) -3,3-dimethylurea, 1,1-dimethyl-
3-phenylurea, 1- (3,4-dimethylphenyl) -3,3-dimethylurea, 1- (2-hydroxyphenyl) -3,3-dimethylurea, 2,4-bis (N, N-dimethyl) Ureido) -toluene, 4,4'-
Methylene bis (phenyl dimethyl urea) etc. are mentioned.

The resin composition of the present invention contains uncured resin Tg.
A thermoplastic resin can be included in order to improve the handling property of the resin and the prepreg by controlling the viscosity of the resin composition and optimizing the viscoelasticity of the resin composition.

The thermoplastic resin is preferably soluble in the component (A), and the resin composition is 100% by weight.
It is possible to contain 0.5 to 20% by weight, more preferably 1 to 15% by weight.

If the compounding ratio of the thermoplastic resin is less than 0.5% by weight, the effect of controlling the uncured resin Tg is not sufficient, and if it exceeds 20% by weight, the uncured resin Tg and the viscosity increase excessively. Alternatively, the strength may be reduced due to coarse separation in the cured product.

As the thermoplastic resin to be contained in the resin composition of the present invention, it is more preferable to use one having a hydrogen-bonding functional group because it has an effect of enhancing the adhesiveness between the reinforcing fiber and the matrix resin.

As such a thermoplastic resin, a resin having a hydrogen-bonding functional group, particularly an alcoholic hydroxyl group, an amide bond or a sulfonyl group, which has a high effect of improving the adhesion between the reinforcing fiber and the matrix resin, is preferably used. I can.

When a large amount of a thermoplastic resin having an alcoholic hydroxyl group is present in the resin composition, the reaction between the constituent element (A) and the constituent element (B) is promoted, which may impair the storage stability at room temperature. However, in the present invention, a suitable amount of hydrolyzable chlorine is contained as described above, and sufficient storage stability can be achieved even if a thermoplastic resin having an alcoholic hydroxyl group is contained.

Examples of the thermoplastic resin having an alcoholic hydroxyl group include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, and phenoxy resin.

Examples of the thermoplastic resin having an amide bond include polyamide and polyimide, and examples of the thermoplastic resin having a sulfonyl group include polysulfone.

Polyamide, polyimide and polysulfone may have functional groups such as ether bond and carbonyl group in the main chain. The polyamide may have a substituent on the nitrogen atom of the amide group.

The resin composition of the present invention preferably has a viscosity at 60 ° C. of 10 to 700 Pa · s,
More preferably, it is from 600 Pa · s. When the viscosity of the resin composition is less than 10 Pa · s, the resin may be too sticky, or the resin flow during heat curing may be too large to obtain the desired physical properties. Also, 700P
If it exceeds a · s, it may be difficult to impregnate the reinforcing fibers, or the flexibility of the prepreg or the sheet adhesive may be impaired.

The prepreg of the present invention comprises an uncured epoxy resin composition and reinforcing fibers, and its form is not particularly limited. The resin composition does not necessarily need to be impregnated to the inside of the carbon fiber bundle, and the resin composition is localized in the vicinity of the surface of the carbon fibers or the carbon fibers aligned in one direction in a sheet shape. Is also good.

In the prepreg of the present invention, carbon fibers, glass fibers, aramid fibers, boron fibers, PBO fibers, high-strength polyethylene fibers, alumina fibers, silicon carbide fibers and the like can be used as the reinforcing fibers.
Two or more kinds of these fibers may be mixed and used. The form and arrangement of the reinforcing fibers are not limited, and for example, fiber structures such as long fibers aligned in one direction, single tows, woven fabrics, knits, nonwoven fabrics, mats, and braids are used.

Particularly in applications where there is a strong demand for lighter weight and higher strength of the material, because of its excellent specific elastic modulus and specific strength,
Carbon fiber can be preferably used.

The reinforcing fiber contained in the prepreg of the present invention preferably has a certain amount of a sizing agent attached to the surface thereof in order to improve the handling property. In particular, a reinforcing fiber to which a sizing agent containing a component having a hydrogen-bonding functional group is attached can be preferably used.

The sizing agent is preferably attached to the carbon fiber in an amount of 0.1 to 3.0% by weight. 0.
If it is less than 1% by weight, fluff of the fiber may occur frequently, and if it exceeds 3.0% by weight, the reinforcing fiber becomes hard,
Impregnation of the matrix resin may be difficult.

In the present invention, the sizing agent that adheres to the surface of the reinforcing fiber is selected from alcoholic hydroxyl groups, phenolic hydroxyl groups, carboxyl groups, acid anhydride groups, amide groups, urethane groups and urea groups as hydrogen-bonding functional groups. Those having a functional group selected from the group can be included.
In particular, it is preferable to include a compound having an alcoholic hydroxyl group or an amide group in the sizing agent from the viewpoint of excellent thermal stability and easy availability of inexpensive ones.

In the present invention, the compound that can be contained in the sizing agent is not particularly limited as a compound having an alcoholic hydroxyl group as a hydrogen-bonding functional group, but polyalkylene glycol such as polyethylene glycol or polypropylene glycol, hexanediol, etc. Compounds such as alkylene diols, polyether polyols, pentaerythritol, sorbitol, polyvinyl alcohol, polyvinyl acetal partially acetalized polyvinyl alcohol, or alcoholic hydroxyl groups of these compounds partially reacted with epichlorohydrin, etc. Modified compound,
Alternatively, an oligomer type bisphenol A type epoxy resin having a plurality of bisphenol skeletons can be preferably used.

In the present invention, with respect to the compound that can be contained in the sizing agent, the compound having an amide group as a hydrogen-bonding functional group is not particularly limited,
Acrylamide derivatives such as acrylamide and dimethylacrylamide, and polymers obtained by polymerizing these, polyamide, polyvinylpyrrolidone, polyvinylacetamide and the like can be used.

The fiber-reinforced composite material obtained from the prepreg of the present invention is suitable for use in sports equipment such as golf club shafts and fishing rods, but in order to realize its weight reduction and obtain a suitable feeling, As the reinforcing fiber, a carbon fiber having an appropriate strand tensile elastic modulus may be selected according to the design of the intended use.

When strength is important, it is preferable to use carbon fibers having a strand tensile elastic modulus of 200 to 290 GPa. The prepreg using the carbon fiber in the standard elastic modulus region to the medium elastic modulus region has a higher strand tensile strength and compressive strength of the carbon fiber than the prepreg using the carbon fiber in the high elastic modulus region. The bending strength of the material tubular body is high. Moreover, the torsional strength is further improved by satisfying the above relational expression. Therefore,
For example, it is preferably used for golf club shafts for hard hitters, fishing rods for jigging, rock rods, and the like. It is also suitable for the tips of rods and the like that require flexibility and strength.

When a balance between strength and weight reduction is required, it is preferable to use carbon fiber having a strand tensile elastic modulus of 230 to 350 GPa. The prepreg using the carbon fiber having such a medium elastic modulus region exhibits appropriate bending strength and rigidity, and the torsional strength is also improved by satisfying the above expression, so that the weight can be further reduced. Therefore, for example, it is suitably used for a wood type golf club shaft, a fishing rod for a lure, and the like.

When weight reduction is particularly required, it is preferable to use carbon fibers having a strand tensile modulus of 320 GPa to 800 GPa. Such a prepreg using carbon fibers having a medium to high elastic modulus region can exhibit sufficient rigidity by using a small amount of material. Therefore, it is suitably used for a long golf club shaft, a golf club shaft for women / aged people, a rod for an ayu rod, and the like, which require weight reduction.

When carbon fibers are used as the reinforcing fibers, the strength and elastic modulus of the resulting fiber-reinforced composite material largely depend on the content of the carbon fibers. Therefore, in the case of containing a certain amount of reinforcing fibers, the smaller the amount of matrix resin to be impregnated, the more the weight of the product can be reduced while maintaining the performance of the fiber-reinforced composite material and the final product almost constant. . For such a purpose, the content of the reinforcing fiber based on the total weight of the prepreg and the fiber-reinforced composite material in the present invention is preferably 60 to 90% by weight,
More preferably, it is 70 to 85% by weight.
When the content of reinforcing fibers is less than 60% by weight, the weight reduction effect may not be sufficient, and when it exceeds 90% by weight, voids remain in the composite material due to the small amount of resin, and mechanical properties deteriorate. There is.

Hereinafter, a method for producing a prepreg and a method for producing a fiber composite material using the prepreg, which are preferably applicable to the present invention, will be described.

The prepreg of the present invention is produced, for example, by a method such as a wet method in which a resin composition is dissolved in a solvent such as methyl ethyl ketone or methanol to have a low viscosity and impregnated, or a hot melt method in which a resin composition is reduced in viscosity by heating and impregnated. can do.

In the wet method, the prepreg can be obtained by immersing the reinforcing fiber in a liquid containing the resin composition, pulling it up, and evaporating the solvent using an oven or the like.

In the hot melt method, a method of impregnating reinforcing resin directly with a resin composition whose viscosity has been reduced by heating, or a method in which a resin composition is once coated on a release paper or the like is first prepared, and then the reinforcing fiber is A resin-impregnated prepreg can be produced by stacking the films from both sides or one side and applying heat and pressure.
The hot melt method is preferable because there is no solvent remaining in the prepreg.

Further, in the method of manufacturing a prepreg,
In the step of impregnating the reinforcing fibers with the resin, the maximum temperature reached by the resin composition needs to be in the range of 70 ° C to 150 ° C, and more preferably 80 to 130 ° C. When the maximum temperature exceeds 150 ° C, the reaction between the constituent elements (A) and (B) partially proceeds in the resin composition, which may impair the handleability as a prepreg, and is less than 70 ° C. If so, sufficient impregnation may be difficult.

To form a fiber composite material using the prepreg of the present invention, a method of laminating the prepreg and then heating and curing the resin while applying pressure to the laminate can be used.

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

The wrapping tape method is a method of winding a prepreg around a cored bar such as a mandrel to form a tubular body, and is suitable for producing a rod-shaped body such as a golf club shaft or a fishing rod. Specifically, a prepreg is wound around a mandrel, a wrapping tape made of a thermoplastic resin film is wound around the outside of the prepreg for fixing and applying pressure to the prepreg, and the resin is heated and cured in an oven, and then a core metal is applied. A tubular body can be obtained by pulling out.

In the internal pressure molding method, a preform in which a prepreg is wrapped around an internal pressure imparting body such as a thermoplastic resin tube is set in a mold, and then high pressure gas is introduced into the internal pressure imparting body to apply pressure. At the same time, the tubular body can be formed by heating the mold.

[0090]

EXAMPLES The present invention will be described in detail below with reference to examples. The amount of hydrolyzable chlorine, the viscosity and thermal stability of the resin composition, the evaluation of the physical properties of the cured resin, the preparation of the prepreg, the evaluation of the properties of the prepreg, and the evaluation of the physical properties of the fiber-reinforced composite material were carried out under the following conditions. All physical properties were measured at a temperature of 23.
The test was performed in an environment of ° C and a relative humidity of 50%. The results of each measurement are summarized in Table 2. In addition, Table 1 shows the contents of the raw materials used in the preparation of the resin composition. (1) Characteristics of resin composition A. Measurement of hydrolyzable chlorine content According to the potentiometric method using a silver nitrate standard solution, ISO-4
583: 1998 (E), the amount of hydrolyzable chlorine was measured.

Here, in the present embodiment, the following items
The amount of hydrolyzable chlorine contained in the resin composition was measured by the procedure described in 1.

Weigh about 1 g of sample into a beaker. Add 25 ml of methyl ethyl ketone and dissolve the sample while stirring with a magnetic stirrer. At this time, the components insoluble in the solvent are separated by a membrane filter.

After adding 25 ml of ethylene glycol monobutyl ether to the liquid after separation, 120 g / l of N was added.
Add 25 mL of ethylene glycol monobutyl ether containing aOH, dissolve and stir, keep at 25 ± 0.5 ° C., and leave for 120 minutes.

After allowing to stand, 25 mL of glacial acetic acid was added, and the mixture was stirred and dissolved, and then immediately titrated with a potentiometer using 0.01 N silver nitrate standard solution.

By the same operation, a blank test without a sample is conducted.

The amount of hydrolyzable chlorine is calculated according to the following formula. Hydrolyzable chlorine amount (wt%) = 3.55 × c × (V ₁ −
V ₂ ) / m ₀ V ₁ : Titration amount of 0.01N silver nitrate standard solution (ml) V ₂ : Titration amount of 0.01N silver nitrate blank test (ml) c: Concentration of silver nitrate standard solution (mol / l) m ₀ : Weight of sample (g) B. Measurement of uncured resin Tg The uncured resin Tg was measured by differential calorimetry (DSC).

In this example, DSC2910 manufactured by TA Instruments Japan was used as a differential calorimeter.

The heating rate was 10 ° C./min, and the temperature was raised in a nitrogen atmosphere to obtain a DSC curve. With respect to this DSC curve, the temperature at the intersection of the tangent line of the base line and the tangent line of the endothermic line and the end point temperature of the endotherm are determined as shown in FIG. 1, and the midpoint between the two points is the uncured resin Tg And

C. Measurement of Viscosity at 60 ° C., Viscosity Increase Ratio at 80 ° C. Viscosity at 60 ° C. and viscosity increase ratio at 80 ° C. were measured using a rotary viscometer.

Using parallel plates having a radius of 20 mm, the viscoelasticity was measured with the following temperature profile at a distance between the parallel plates of 0.5 mm, a measurement starting temperature of 40 ° C. and a measurement frequency of 10 rad / s. The complex viscosity η * measured at 60 ° C. ± 1 ° C. at the time of temperature rise is defined as the viscosity at 60 ° C., the viscosity when 80 ° C. is reached for the first time is η ₀ , and the viscosity after 120 minutes after reaching 80 ° C is η ₁₂₀ Then, the thickening ratio at 80 ° C. was calculated by the following formula.

Viscosity increase ratio = η ₁₂₀ / η ₀ Measurement start temperature 40 ° C., temperature rising rate 1.5 ° C./min 80 ° C.
Up to.

After reaching 80 ° C., hold at 80 ° C. for 120 minutes.

In this example, a dynamic analyzer ARES manufactured by Rheometrics was used as the rotational viscometer. (2) Measurement of physical properties of cured resin A. Preparation of Resin Cured Product After heating the resin composition to 80 ° C. and defoaming with a vacuum pump,
Pour into a mold that has been subjected to mold release treatment, and heat-treat in a hot air oven at 130 ° C for 90 minutes to obtain a thickness of 6 m.
A resin cured product plate of m was prepared.

B. Measurement of nominal strain during compression failure A cubic test piece with a side length of 6 mm was cut out from a cured resin plate, the test speed was 1 ± 0.2 mm / min, and other conditions were compressed according to JIS K7181. The nominal strain at break was measured. (3) Characteristic evaluation of prepreg A. Preparation of prepreg The resin composition was applied onto release paper using a reverse roll coater to prepare a resin film. Next, two resin films were superposed on both sides of the carbon fiber on carbon fibers (made by Toray Industries, Inc., tensile elastic modulus: 377 GPa, sizing agent adhesion amount: 1.2% by weight) aligned in one direction in a sheet shape, By heating and pressurizing so that the maximum temperature of the composition reaches 100 ° C. to 110 ° C., impregnating the resin composition, peeling off the release paper on one side, and winding the polyethylene film on the side where the release paper is peeled off , Carbon fiber basis weight 125g / m
^2. A sheet-like prepreg having a fiber content of 76% by weight was obtained.

B. Adhesive strength measurement of prepreg 24 ° C, relative humidity 50 by the following operations (a) and (b)
The adhesive strength of the prepreg was measured under the environment of% RH. (A) The prepreg used for measurement is 100 mm × 200 m
The prepreg A was cut into a size of m and firmly attached to a plastic plate having a flat surface with a double-sided tape. (B) On the surface of the prepreg A, a prepreg B cut from the same prepreg A and having a contact area of 10
44N so that mm × 10 mm (= 100 mm ² )
After pressing for 1 second with the load of, prepreg B is 30mm
The peeling force at the time of peeling in the direction perpendicular to the surface of the prepreg A at a speed of / min was measured, and this was measured as
The value obtained by dividing by 0 mm ² ) was taken as the adhesive strength of the prepreg.

C. Storage stability of prepreg The prepreg is allowed to stand in an atmosphere of a temperature of 40 ° C. and a relative humidity of 50%, and the change in the uncured resin Tg of the resin composition contained in the prepreg at that time is measured to determine the storage stability. evaluated.

The uncured resin Tg of the resin composition contained in the prepreg was measured by obtaining the DSC curve of the prepreg by the same operation as in (1) A above. The measurement was performed twice at the start of standing and after standing for 2 weeks. Here, the prepreg used for evaluation has a storage time of 24 hours or less after the prepreg is manufactured and a storage temperature of -20 to 25.
The thing of the degree C was used. (4) Measurement of physical properties of fiber reinforced composite material A. Measurement of in-plane shear strength A unidirectional prepreg was laminated with [+ 45 / -45] s so that the direction of the carbon fiber was ± 45 °, and the thickness of the molded product was 2
mm so that the temperature is 13 in an autoclave.
It was measured by conducting a ± 45 # tensile test according to JIS K7079 on a sample produced by heating and pressurizing at 5 ° C. and a pressure of 290 Pa for 2 hours to cure. (5) Raw materials The following materials were used as raw materials for the resin composition. <Epoxy resin> -Bisphenol A type epoxy resin ("Epotote")
(Registered trademark) YD128, manufactured by Tohto Kasei Co., Ltd.-Bisphenol A type epoxy resin ("Epotote" Y
D128G, manufactured by Tohto Kasei Co., Ltd.-Bisphenol A type epoxy resin ("Epicoat" 1
001, Japan Epoxy Resin Co., Ltd.-Isocyanate-modified epoxy resin (AER4152,
Asahi Kasei Epoxy Co., Ltd. <Curing agent> -Dicyandiamide (DICY7, Japan Epoxy)
Resin Co., Ltd. <Curing aid> 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU99, Hodogaya Chemical Co., Ltd.) <Thermoplastic resin> Polyvinyl formal ("Vinylec") "(Registered trademark)
K, manufactured by Chisso Co., Ltd.) (Example 1) The compositions shown in Table 1 were mixed by a kneader according to the procedure shown below to obtain an epoxy resin composition in which polyvinyl formal was uniformly dissolved. (A) While heating each epoxy resin raw material of the constituent element (A) and polyvinyl formal to 150 to 170 ° C., 1 to
Stir for 2 hours to uniformly dissolve polyvinyl formal. (B) The resin temperature is lowered to 60 to 70 ° C., dicyandiamide which is a component (B), and 3- (3,4-dichlorophenyl) -1,1-dimethylurea are added, and the temperature is adjusted to 30
After kneading for about 40 minutes, the resin composition is obtained by taking out from the kneader.

The amount of hydrolyzable chlorine contained in the obtained resin composition was controlled in an appropriate range, and the viscosity stability of the resin composition was also good.

Next, using this resin composition, a prepreg was obtained by the above-mentioned operation. Reflecting that the amount of hydrolyzable chlorine in the resin composition is controlled within an appropriate range, the resin composition contained in the obtained prepreg has a small Tg change with time, and further, the uncured resin Tg is appropriate. Since it was in the above range, the prepreg showed good adhesive strength and was easy to handle.

The cured product had a high compression fracture, reflecting that the crosslinking density was lowered by using only the bifunctional epoxy resin as the constituent element (A) and further using a bifunctional epoxy resin having a high molecular weight. Time call distortion.

Furthermore, the in-plane shear strength measured by the above-mentioned method using such a prepreg shows a high value, and not only the resin composition is excellent in storage stability but also the strength of the composite material is good. I understood. (Examples 2 to 6) With respect to the compositions shown in Table 1, the resin composition was prepared, the prepreg was prepared, and the physical properties of the fiber-reinforced composite material were measured in the same manner as in Example 1. Similar to Example 1,
It showed good viscosity stability, prepreg handleability, and in-plane shear strength. Comparative Example 1 With respect to the composition shown in Table 1, the resin composition was prepared, the prepreg was prepared, and the physical properties of the fiber-reinforced composite material were measured in the same manner as in Example 1.

The amount of hydrolyzable chlorine was controlled, the viscosity stability and the storage stability of the prepreg were good, but the uncured resin Tg was low, so the prepreg was excessively sticky and had a low adhesive strength. The workability of molding using this was extremely poor. (Comparative Example 2) With respect to the composition shown in Table 2, the resin composition was prepared, the prepreg was prepared, and the physical properties of the fiber-reinforced composite material were measured in the same manner as in Example 1.

Since the amount of hydrolyzable chlorine was small and the amount of epoxy resin component having a hydroxyl group was large, the viscosity stability and the storage stability of the prepreg were insufficient.

[0114]

[Table 1]

[0115]

EFFECTS OF THE INVENTION According to the present invention, a resin composition having both storage stability at room temperature and curability upon heating and excellent handling properties can be obtained.

With such a resin composition, suitable tackiness,
A prepreg having flexibility is obtained, and by heat-curing the prepreg, a fiber-reinforced composite material having good mechanical properties can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of Tg measurement by DSC.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F072 AB04 AB06 AB08 AB09 AB10                       AB28 AB29 AB30 AD08 AD28                       AD30 AD44 AD45 AD46 AG03                       AH04 AH22 AL05                 4J002 AA00Y BE02Y BE06Y CD00W                       CD05X CD20X CH08Y CM04Y                       GC00                 4J036 AA05 AB07 AG10 AJ15 AJ18                       CA02 DC25 DC31 DC35 DC38                       DC41 FB01 FB13 FB14 FB15                       JA11

Claims (9)

[Claims] 1. A composition comprising the following constituent elements (A), (B) and (C), containing 0.03 to 0.3% by weight of hydrolyzable chlorine and having a glass transition temperature Tg of -10 to 15: The epoxy resin composition is characterized in that the temperature is 0 ° C. (A) Epoxy resin (B) Hardener (C) At least one compound selected from imidazole derivatives and urea derivatives 2. An epoxy resin having two or more alcoholic hydroxyl groups in the molecule is added in an amount of 10 per 100% by weight of the constituent element (A).
The epoxy resin composition according to claim 1, which comprises -100% by weight. 3. The viscosity at 60 ° C. is 10 to 700 Pa.
It is s, The epoxy resin composition of Claim 1 or 2 characterized by the above-mentioned. 4. The melting point of the constituent element (B) is 80 to 300 ° C., and the constituent element (B) is dispersed in the form of particles.
The epoxy resin composition according to any one of 1 to 3. 5. The epoxy resin composition according to claim 1, which comprises a thermoplastic resin. 6. The epoxy resin composition according to claim 5, wherein the thermoplastic resin is contained in an amount of 0.5 to 20% by weight based on 100% by weight of the resin composition. 7. The component (A) has a partial structure represented by the following general formula (1) or (2), and comprises a component having one or more epoxy groups. The epoxy resin composition according to any one of claims 1 to 6. [Chemical 1] (However, each R independently represents an arbitrary organic residue.) (However, each R independently represents an arbitrary organic residue.) 8. A prepreg comprising the epoxy resin composition according to any one of claims 1 to 7 and a reinforcing fiber. 9. A prepreg characterized in that the reinforced fiber is impregnated by heating the epoxy resin composition according to any one of claims 1 to 7 so that the maximum temperature reaches 70 ° C to 150 ° C. Production method.