JPH0776616A - Epoxy resin composition for prepreg and prepreg - Google Patents

Abstract

PURPOSE:To provide the composition comprising a specific epoxy resin component, a guanidine compound, a reaction product, etc., capable of being cured at low temperatures, and excellent in heat resistance and rapid curability. CONSTITUTION:This composition comprises (A) 100 pts.wt. of a mixture comprising a bisphenol type epoxy resin preferably in an amount of 60-90wt.% and a novolak epoxy resin preferably in an amount of 10-40wt.%, (B) (i) a guanidine compound such as dicyandiamide preferably in an amount of 0.3-10 pts.wt. and (ii) a curing accelerator such as N-(3-chloro-4-methoxyphenyl)-N,N'- dimethylurea of the formula (X, Y are H, chlorine, bromine, methyl, nitro, etc.; R1, R2 are alkyl, allyl, alkoxy, etc.) preferably in an amount of 0.3-20 pts.wt., and (C) the reaction product of an epoxy compound with an imidazole compound preferably in an amount of 5-30 pts.wt.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for prepreg and a prepreg. More specifically, the present invention relates to an epoxy resin composition for prepreg and a prepreg that has low-temperature curability and further has low-temperature fast-curability.

[0002]

2. Description of the Related Art Epoxy resins are widely used in various industrial fields by taking advantage of their excellent mechanical properties. In particular, epoxy resins are often used for composite materials composed of reinforcing fibers such as carbon fibers, glass fibers and aramid fibers and matrix resins.

Regarding the various properties required of a prepreg in which reinforcing fibers are impregnated with a matrix resin, it goes without saying that the physical properties of the molded product are excellent, but at the same time, at room temperature, the pot life is as long as possible and the resin is cured. It can be mentioned that the temperature is low and the curing speed is fast.

In general, most epoxy resins used for prepregs cure at a relatively high temperature (for example, 120 to 180 ° C.). Therefore, inconvenience may occur during molding,
The heat energy is required to raise the temperature, and the economy becomes poor. In addition, since epoxy resins generally have low viscosity at high temperatures, fiber reinforced plastics (hereinafter referred to as F
RP) is easy to impregnate into the reinforcing fiber during molding, and bubbles inside the molded product can easily escape, but on the other hand, if the viscosity at high temperature is too low, a large and thick molded product will be molded. In some cases, the resin unnecessarily flows too much, which causes problems such as disorder of the reinforcing fibers and deterioration of dimensional accuracy. Especially, when the time required for curing is long, the phenomenon becomes more prominent.

If the molding temperature of the prepreg is too high, the resulting FRP tends to warp due to thermal strain.
This results in poor molding and poor quality of the FRP product and deteriorates the yield.

Further, the prepreg has an FRP obtained
For the purpose of reinforcing the FRP or decorating the appearance of the FRP, metal fibers, thermoplastic resin,
Reinforcing materials such as inorganic materials and decorative materials such as powder and fibers may be added. In such a case, if a high temperature is used during molding or it takes a long time to fix the shape of the molded product due to the progress of curing, the molding temperature rises until the shape of the molded product is fixed. The resin is likely to flow out between the two, causing a problem that the arrangement of the reinforcing material or the decoration material is disturbed or the arrangement of the reinforcing fibers is disturbed.

Claim 1 of JP-A-63-37137
In addition, 100 parts by weight of an epoxy resin composition composed of a bisphenol type epoxy resin, a phenol novolac type epoxy resin and / or a modified epoxy resin thereof is melt-mixed with a polyvinyl formal type resin, and a curing agent dicyandiamide and / or a urea derivative is further mixed. Although a prepreg obtained by impregnating a reinforcing fiber with the resin composition described above is disclosed, a considerably high temperature (for example, 120 to 180 ° C.) is required even when curing such a prepreg,
The fact is that the above problems could not be avoided.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, namely, to cure at a lower temperature than before,
Furthermore, it aims at providing the epoxy resin composition for prepregs, and the prepregs which cure rapidly at low temperature.

[0009]

In order to solve the above problems, the resin composition for prepreg of the present invention has the following constitution. That is, the epoxy resin composition for prepreg is characterized by comprising the following components [A] to [C].

[A]: Epoxy resin component consisting of bisphenol type epoxy resin and novolac type epoxy resin [B]: Guanidine compound and curing accelerator [C]: Reaction product of epoxy compound and imidazole Further, the above problems are solved. Therefore, the prepreg of the present invention is
It has the following configuration. That is, the following components [A] to [C]
A prepreg obtained by impregnating reinforcing fibers with an epoxy resin composition comprising

[A]: Epoxy resin component composed of bisphenol type epoxy resin and novolac type epoxy resin [B]: Guanidine compound and curing accelerator [C]: Reaction product of epoxy compound and imidazole compound Explained.

In the present invention, a bisphenol type epoxy resin and a novolac type epoxy resin are used as the component [A].

As the bisphenol type epoxy resin,
As the bisphenol A type epoxy resin, for example, Epicoat 828, Epicoat 825, Epicoat 1001,
Epicoat 1004 (produced by Yuka Shell Epoxy Co., Ltd.), YD128 (produced by Toto Kasei Co., Ltd.), Epicron 840,
Epicron 850, Epicron 855, Epicron 86
0, Epicron 1050 (Dainippon Ink and Chemicals, Inc.)
), ELA128 (Sumitomo Chemical Co., Ltd.), DER33
Commercially available products such as 1C (manufactured by Dow Chemical Co.) can be used. In order to add functionality, Epiclon 1
52, Epiclon 1120A (manufactured by Dainippon Ink and Chemicals, Inc.) and other brominated bisphenol A type epoxy resins can also be used. Examples of the bisphenol F type epoxy resin include Epicron 830 (manufactured by Dainippon Ink and Chemicals, Inc.) and Epicoat 807 (manufactured by Yuka Shell Epoxy Co., Ltd.). These bisphenol type epoxy resins may be used alone or in combination of two or more. If the blended amount of these bisphenol type epoxy resins is too large, the obtained cured product may have a high resin toughness but a low elastic modulus. While preventing the toughness of the cured product from decreasing, from the viewpoint of preventing the elastic modulus of the cured product from decreasing, and in order to adjust the tackiness and drape when used as a prepreg, solid, semi-solid, or liquid bisphenol at room temperature. The type epoxy resin in the epoxy resin component is preferably 40% by weight or more, more preferably 60 to 90.
It is preferable to add the composition in an amount of 60% by weight, more preferably 60 to 70% by weight.

As the novolac type epoxy resin, Epicoat 152, Epicoat 154 (produced by Yuka Shell Epoxy Co., Ltd.), DER485, DEN431, DEN43 are used.
8 (manufactured by Dow Chemical Co., Ltd.), EPN1138, EPN
Phenolic novolac type epoxy resin and E sold under the trade names such as 1139 (manufactured by Ciba Geigy)
CN1273, ECN1280 (Ciba Geigy Co., Ltd.)
A cresol novolac type epoxy resin which is commercially available under the trade name such as (trade name) can be used. These novolac type epoxy resins may be used alone or in combination of two or more. These novolac type epoxy resins preferably have as high a blending amount as possible in order to obtain a cured product having high heat resistance and high water resistance, but when the blending amount of the novolak type epoxy resin is too high, a high heat resistance is obtained. Although a cured product with high resistance and high water resistance can be obtained, it may become a cured product with low toughness, or the solubility of the thermoplastic resin deteriorates when it is desired to add a thermoplastic resin for imparting functionality. There are cases. While increasing the heat resistance and water resistance of the cured product as much as possible and preventing the toughness from decreasing, it is also possible to reduce the elastic modulus of the cured product or increase the resin viscosity to deteriorate the tackiness and drape of the prepreg. From the viewpoint of prevention, the addition amount of the novolac type epoxy resin is preferably 60% by weight or less, more preferably 1% by weight in the epoxy resin component.
Within the range of 0 to 40% by weight, more preferably 30 to 40
It is preferable to set it within the range of weight%.

When a bisphenol type epoxy resin having a number average molecular weight of 350 to 1500 is used as the component [A], the viscosity at 80 ° C. easily falls within the preferable range described below, and the tackiness and drapability of the prepreg are improved. Good and prevents the resin flow from increasing during curing and preventing the toughness of the cured product from decreasing, while preventing the adhesiveness and drape property at room temperature from decreasing, resulting in poor handling as a prepreg. It is preferable from the viewpoint.

The guanidine compound used as the component [B] functions as a curing agent, and specifically, dicyandiamide (DICY), 2,6-xylenyl-piguanide, O-tolylpiguanide, diphenylguanidine, di- O-tolyl guanidine, 1-O-tolyl hyguanide, acetoguanamine, melamine, benzoguanamine, etc. are mentioned. Generally, dicyandiamide (DI
CY) is preferable from the viewpoint of curability and storability.

The amount of the guanidine-based compound used as the component [B] is adjusted so that the gelling time, the regulation of the resin flow, the heat resistance of the cured product, the tackiness of the prepreg, and the drape property are in proper ranges. , 0.3 to 10 parts by weight, and more preferably 1 to 100 parts by weight of the component [A].
~ 7 parts by weight is recommended.

The curing accelerator used as the component [B] is
Examples thereof include urea derivatives, imidazole compounds, and tertiary amine compounds. From the viewpoint of storage stability, urea derivatives represented by the following formula are preferably used.

[0019]

[Chemical 1] In the formula, X and Y are hydrogen atom, chlorine atom, bromine atom, methyl group, methoxy group, ethoxy group, nitro group or -NH
CONR ₁ (R ₂ ), R ₁ and R ₂ represent an alkyl group, an allyl group, an alkoxy group, an alkenyl group or an aralkyl group, and R ₁ and R ₂ may be bonded to form a heterocycle. .

Specific examples of such compounds include N-
(3-chloro-4-methoxyphenyl) -N, N'-dimethylurea, N- (4-chlorophenyl) -N, N'-
Dimethylurea, N- (3-chloro-4-ethylphenyl) -N, N'-dimethylurea, N- (4-chlorophenyl) -N, N'-dipropylurea, N- (3-chloro-4-methyl Phenyl) -N, N'-dimethylurea, N
-(3,4-dichlorophenyl) -N, N'-dimethylurea (hereinafter abbreviated as DCMU), N- (4-methyl-3)
-Nitrophenyl) -N, N'-dimethylurea, N-
(4-methoxyphenyl) -N, N'-dimethylurea,
Examples thereof include N- (4-chlorophenyl-carbamoyl) piperidine and N- (4-chlorophenyl-carbamoyl) morpholine.

The blending amount of the curing accelerator used as the component [B] depends on the gelation time, the regulation of the resin flow, the heat resistance of the cured product,
In order to adjust the tackiness and drape property of the prepreg within an appropriate range, the amount is preferably 0.3 to 20 parts by weight, more preferably 2 to 8 parts by weight, relative to 100 parts by weight of the component [A]. Is good.

The reaction product of the epoxy compound of the component [C] and the imidazole compound is one having two or more epoxy groups, preferably glycidyl groups, in one molecule as an epoxy compound, and examples thereof include bisphenol A and bisphenol F. , Polyphenols such as catechol and resorcinol, or polyglycidyl ethers obtained by reacting polyhydric alcohols such as glycerin and polyethylene glycol with epichlorohydrin, hydroxycarboxylic acids such as p-oxybenzoic acid and β-oxynaphthoic acid Glycidyl ester obtained by reacting with epichlorohydrin, polyglycidyl ether ester obtained from polycarboxylic acid such as phthalic acid and terephthalic acid,
Examples thereof include glycidylamine compounds obtained from 4,4′-diaminodiphenylmethane, m-aminophenol and the like, as well as epoxidized novolac and epoxidized polyolefin. Further, as the epoxy compound, the above-mentioned bisphenol type epoxy resin is also used. Examples of the imidazole compound used to react with these epoxy compounds include 1- (2-hydroxy-3-phenoxypropyl) -2-methylimidazole and 1- (2-hydroxy-3-phenoxypropyl).
2-ethyl-4-methylimidazole, 1- (2-hydroxy-3-butoxypropyl) -2-methylimidazole, 1- (2-hydroxy-3-butoxypropyl) -2-ethyl-4-methylimidazole, 1- (2
-Hydroxy-3-phenoxypropyl) -2-phenylimidazoline, 1- (2-hydroxy-3-butoxypropyl) -2-methylimidazoline, 2- (dimethylaminomethyl) phenol, 1- (2-hydroxy-3)
-Phenoxypropyl) -2-methylimidazole piperazine and the like.

As the component [C] in the present invention, those commercially available as an adduct of an imidazole compound and an epoxy compound can be used, and as such a compound, for example, Novacure-HX3722, HX37.
21 (manufactured by Asahi Kasei Co., Ltd.), Amicure-PN-23, P
NH (manufactured by Ajinomoto Co., Inc.) and the like.

In order to properly regulate the resin flow, the blending amount of the component [C] is based on 100 parts by weight of the component [A].
Preferably 5 to 30 parts by weight, more preferably 10 to 25
It is preferable to use parts by weight.

The epoxy resin composition of the present invention enhances the fluidity of the resin and impregnates it into the reinforcing fiber easily when using the hot melt method, while the prepreg is too sticky to cause poor handling or molding. In order to prevent the composite performance from deteriorating due to a large amount of resin being washed away, the viscosity is 1 to
It is preferably 100 poise (80 ° C.).

Further, the epoxy resin composition for prepreg of the present invention may contain other resins and additives as long as the object of the present invention is not impaired.

The prepreg of the present invention is obtained by impregnating reinforcing fibers with the above-mentioned epoxy resin composition. As the reinforcing fiber, fibers conventionally used for FRP such as carbon fiber, aromatic polyamide fiber and glass fiber are used. The form of these reinforcing fibers may be a tape arranged in one direction, a sheet form, a woven fabric, a mat form, or the like.

The prepreg can be produced by a so-called hot melt method in which the epoxy resin composition is impregnated into the reinforcing fibers under heating and pressure, or a solution of the epoxy resin composition dissolved in an organic solvent is impregnated into the reinforcing fibers and then removed. Any of the so-called wet methods using a solvent can be applied. However, the epoxy resin composition used for the prepreg of the present invention is less likely to be cured at a lower temperature and a shorter time than conventional ones, and therefore it is necessary to avoid exposing the epoxy resin composition to an unnecessarily high temperature when producing the prepreg. However, when the reinforcing fiber is impregnated with the epoxy resin composition by, for example, the hot melt method, it is desirable to carry out at a relatively low temperature.

[0029]

The present invention will be described in more detail with reference to the following examples.

The resin viscosity in the present invention was measured under the following conditions using an RDA-II type device manufactured by Rheometrics.

(Viscosity measurement conditions) Operation mode: Dynamic mode Frequency: 3.14 rad / sec Temperature rising rate: 1.5 ° C./min Plate configuration: Parallel plate (radius 25 mm) Gap 1.00 mm (Example 1) Epicoat 828 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 25% by weight, 2- (dimethylaminomethyl) phenol 25% by weight, 1- (2-hydroxy-3-phenoxypropyl) -2- 10% by weight of methylimidazole and 10% by weight of piperazine were heated at 100 ° C. for about 1 hour to react with each other to obtain a component [C].

Epicoat 828 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 60 parts by weight, Epicoat 154 (phenol novolak type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 40 parts by weight, dicyandiamide 3. 0 parts by weight, 3 parts by weight of N- (3,4-dichlorophenyl) -N, N'-dimethylurea (DCMU) and 10 parts by weight of the above component [C] were mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. The curing characteristics of the obtained cured product and the epoxy resin composition before curing were measured by a differential scanning calorimeter (DSC) based on ASTM D3418-82. T ₀ represents the curing start temperature, and T ₁ represents the exothermic peak temperature. As for the obtained curing characteristics, the curing reaction started at a low temperature and the glass transition temperature (Tg) of the cured product was higher than that in the case where the addition compound was not contained.

Further, the resin toughness was measured by the double torsion method (hereinafter, DT method) as the fracture strain energy release rate G _IC of the cured resin obtained from the composition. For more information on the DT method, see Journal of Materials Sci.
ence) Volume 20, pp. 77-84 (1985) and the like. G _IC is calculated crack load P, the slope [Delta] C / .DELTA.a _f and crack growth of the sample thickness t for crack extension distance a _f compliance C by the following equation.

G _IC = P ² (ΔC / Δa _f ) / 2t Here, the compliance C is C = δ / P depending on the crosshead displacement amount δ when the crack occurs and the crack generating load P.
Is defined by

Further, the obtained epoxy resin composition was impregnated into unidirectionally aligned carbon fibers to obtain a prepreg having a resin content of 45% by weight. The tackiness and drape of this prepreg were good. Further, when this prepreg was left at 25 ° C. to evaluate the storage stability, it took more than one month for the Tg of the prepreg to rise by 3 ° C.

When this prepreg was cured at a curing temperature of 100 ° C. for a curing time of 1 hour, a molded product having a Tg of 121 ° C. was obtained.

The results obtained are summarized in Table 1.

[0039]

[Table 1] (Comparative Example 1) 60 parts by weight of Epicoat 828, 40 parts by weight of Epicoat 154, 3.0 parts by weight of DICY, DC
3 parts by weight of MU was mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. Regarding the obtained cured product and the epoxy resin composition before curing, as in Example 1,
The curing characteristics were measured using DSC. The curing properties obtained were inferior to those containing the addition compound.

Further, the obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. The results are summarized in Table 1 together with the evaluation results of the tackiness, drape property and storage stability of this prepreg.

(Comparative Example 2) 60 parts by weight of Epicoat 828, 40 parts by weight of Epicoat 154 and 20 parts by weight of the component [C] used in Example 1 were mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. Regarding the obtained cured product and the epoxy resin composition before curing, as in Example 1,
The curing characteristics were measured using DSC. The obtained curing start temperature (T ₀ ) was inferior to that of Example 1.

Further, the obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. The results are summarized in Table 1 together with the evaluation results of the tackiness, drape property and storage stability of this prepreg.

(Comparative Example 3) 60 parts by weight of Epicoat 828, 40 parts by weight of Epicoat 154, and 4.0% of DICY.
20 parts by weight of the component [C] used in Example 1 were mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. Regarding the obtained cured product and the epoxy resin composition before curing, as in Example 1,
The curing characteristics were measured using DSC. The obtained curing start temperature (T ₀ ) was inferior to that of Example 1.

Further, the obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. The results are summarized in Table 1 together with the evaluation results of the tackiness, drape property and storage stability of this prepreg.

Example 2 20 parts by weight of Epicoat 828, 80 parts by weight of Epicoat 154, 5 parts by weight of DICY, 5 parts by weight of DCMU, and 10 parts by weight of the component [C] used in Example 1 were mixed to obtain an epoxy resin composition. I got a thing. The curing characteristics were as good as in Example 1.

Further, the obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. The impregnating property of the prepreg was slightly poorer than that of Example 1, and the tackiness and drape property of the prepreg were also slightly less than those of Example 1. It is summarized in Table 1 together with other evaluation results. (Example 3) Epicoat 828 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 25% by weight, 2- (dimethylaminomethyl) phenol 25% by weight, 1- (2-hydroxy-3-) 10% by weight of phenoxypropyl) -2-methylimidazole and 10% by weight of piperazine were heated at 100 ° C. for about 1 hour to react with each other to obtain a component [C].

Next, Epicoat 828 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 2
5% by weight, Epicoat 1001 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 45% by weight, and Epicoat 154 (phenol novolac type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 30% by weight 5 parts by weight of dicyandiamide, N- (3,4-dichlorophenyl) -N, N'-dimethylurea (DCMU) 5 relative to 100 parts by weight of the melted epoxy resin component
20 parts by weight of the above component [C] was added and mixed to obtain an epoxy resin composition.

The obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight.

When this prepreg was cured at a curing temperature of 80 ° C. for a curing time of 120 minutes, a molded product having a Tg of 83 ° C. was obtained. It is summarized in Table 2 together with other evaluation results.

[0053]

[Table 2] (Comparative Example 4) A prepreg having a resin content of 45% by weight was obtained in the same manner as in Example 3 except that the component [C] was not used.

When this prepreg was cured at a curing temperature of 80 ° C. for a curing time of 120 minutes, the prepreg did not cure and did not become a molded product. It is summarized in Table 2 together with other evaluation results.

Example 4 The prepreg obtained in Example 3 was cured at a curing temperature of 130 ° C. for a curing time of 10 minutes to obtain a molded product having a Tg of 122 ° C. It is summarized in Table 2 together with other evaluation results.

Comparative Example 5 When the prepreg obtained in Comparative Example 4 was cured at a curing temperature of 130 ° C. for a curing time of 10 minutes, the prepreg did not cure and did not become a molded product. It is summarized in Table 2 together with other evaluation results.

Example 5 A prepreg having a resin content of 45% was obtained in the same manner as in Example 3 except that 20 parts by weight of Amicure PN-23 was used as the component [C] of Example 3. It was When this prepreg was cured at a curing temperature of 80 ° C. for a curing time of 120 minutes, a molded product having a Tg of 87 ° C. was obtained. It is summarized in Table 2 together with other evaluation results.

Example 6 The prepreg obtained in Example 5 was cured at a curing temperature of 130 ° C. for a curing time of 10 minutes to obtain a molded product having a Tg of 125 ° C. It is summarized in Table 2 together with other evaluation results.

Example 7 Epicoat 828 (bisphenol A type epoxy resin, Yuka Shell Epoxy Co., Ltd.)
25% by weight, 2- (dimethylaminomethyl) phenol 25% by weight, 1- (2-hydroxy-3-phenoxypropyl) -2-methylimidazole 10% by weight, piperazine 10% by weight at 100 ° C. The component [C] was obtained by heating and reacting for about 1 hour.

Next, Epicoat 828 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 2
5% by weight, Epicoat 1001 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 45% by weight, Epicoat 154 (phenol novolac type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 30% by weight are mixed and melted. With respect to 100 parts by weight of the made epoxy resin component,
After adding 10 parts by weight of polyvinyl formal as a thermoplastic resin and mixing and dissolving it, 5 parts by weight of dicyandiamide,
5 parts by weight of N- (3,4-dichlorophenyl) -N, N'-dimethylurea (DCMU) and 2 parts of the above component [C] were added.
An epoxy resin composition was obtained by adding 0 parts by weight and mixing.

The obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight.

When this prepreg was cured at a curing temperature of 130 ° C. for a curing time of 10 minutes, a molded product having a Tg of 127 ° C. was obtained. It is summarized in Table 2 together with other evaluation results.

Example 8 Epicoat 828 (bisphenol A type epoxy resin, Yuka Shell Epoxy Co., Ltd.)
25% by weight, 2- (dimethylaminomethyl) phenol 25% by weight, 1- (2-hydroxy-3-phenoxypropyl) -2-methylimidazole 10% by weight, piperazine 10% by weight at 100 ° C. The component [C] was obtained by heating and reacting for about 1 hour.

Next, Epicoat 828 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 2
100 parts by weight of an epoxy resin component prepared by mixing and mixing 0% by weight and 80% by weight of Epicoat 154 (phenol novolac type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) with 10 parts of polyvinyl formal as a thermoplastic resin.
5 parts by weight of dicyandiamide and N- (3,4-dichlorophenyl) -N, N'-
5 parts by weight of dimethylurea (DCMU) and 20 parts by weight of the above component [C] were added and mixed to obtain an epoxy resin composition.

The obtained epoxy resin composition was impregnated into unidirectionally aligned carbon fibers to obtain a prepreg having a resin content of 45% by weight.

When this prepreg was cured at a curing temperature of 130 ° C. for a curing time of 10 minutes, a molded product having a Tg of 123 ° C. was obtained. The results of the other evaluations are summarized in Table 2, and the results of the other evaluations are summarized in Table 2. .

Example 9 Epicoat 828 (bisphenol A type epoxy resin, Yuka Shell Epoxy Co., Ltd.)
60 parts by weight, Epicoat 154 (phenol novolac type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) 4
0 parts by weight, dicyandiamide 3.5 parts by weight, N- (3,
4-dichlorophenyl) -N, N'-dimethylurea (D
CMU) 4 parts by weight and Amicure PN-23 (manufactured by Ajinomoto Co., Inc.) 10 parts by weight were mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. When the curing characteristics were measured in the same manner as in Example 1, the curing reaction started at a low temperature and the glass transition temperature (Tg) of the cured product was higher than that in the case where no addition compound was contained. The results are shown in Table 3.

[0069]

[Table 3] (Comparative Example 6) 60 parts by weight of Epicoat 828, 40 parts by weight of Epicoat 154, 3.5 parts by weight of DICY, DC
4 parts by weight of MU was mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air drier at 100 ° C. for 1 hour. About the obtained cured product and the epoxy resin composition before curing, in the same manner as in Example 9,
The curing characteristics were measured using DSC. The curing properties obtained were inferior to those containing the addition compound.

The obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. When this prepreg was cured at a curing temperature of 100 ° C. for a curing time of 1 hour, Tg
A molded product at 100 ° C. was obtained.

The other evaluation results are summarized in Table 3.

(Comparative Example 7) 60 parts by weight of Epicoat 828, 40 parts by weight of Epicoat 154, Amicure PN-
20 parts by weight of 23 were mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. About the obtained cured product and the epoxy resin composition before curing, in the same manner as in Example 9,
The curing characteristics were measured using DSC. The obtained curing start temperature (T ₀ ) was inferior to that in Example 9.

Further, the obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. When this prepreg was cured at a curing temperature of 100 ° C. for a curing time of 1 hour, Tg
A molded product of 121 ° C. was obtained.

The other evaluation results are summarized in Table 3.

(Comparative Example 8) 60 parts by weight of Epicoat 828, 40 parts by weight of Epicoat 154, and 3.5% of DICY.
By weight, 20 parts by weight of Amicure PN-23 was mixed to obtain an epoxy resin composition.

This epoxy resin composition was cured in a hot air dryer at 100 ° C. for 1 hour. About the obtained cured product and the epoxy resin composition before curing, in the same manner as in Example 9,
The curing characteristics were measured using DSC. The obtained curing start temperature (T ₀ ) was inferior to that in Example 9.

Further, the obtained epoxy resin composition was impregnated into carbon fibers aligned in one direction to obtain a prepreg having a resin content of 45% by weight. When this prepreg was cured at a curing temperature of 100 ° C. for a curing time of 1 hour, Tg
A molded product having a temperature of 119 ° C. was obtained.

The other evaluation results are summarized in Table 3.

(Embodiment 10) 20 parts by weight of Epicoat 828, 80 parts by weight of Epicoat 154, DICY3.5
Parts by weight, N- (3,4-dichlorophenyl) -N, N '
4 parts by weight of dimethylurea (DCMU) and 10 parts by weight of Amicure PN-23 were mixed to obtain an epoxy resin composition. The curing characteristics were as good as in Example 9.

Further, the obtained epoxy resin composition was impregnated into unidirectionally aligned carbon fibers to obtain a prepreg having a resin content of 45% by weight. The impregnation property of this prepreg was slightly poorer than that of Example 9, and the tackiness and drape property of the prepreg were also slightly insufficient as compared with Example 9. It is summarized in Table 3 together with other evaluation results.

[0083]

According to the present invention, since it cures at a low temperature as compared with the conventional epoxy resin composition for prepreg, it is possible to improve the inconvenience caused by the high temperature during molding and is economically advantageous. Further, it is possible to obtain a cured product having high heat resistance even though it is cured at a low temperature.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroyuki Izumi 1515 Tsutsui, Matsumae-cho, Iyo-gun, Ehime Prefecture Toray Industries, Inc. Ehime Plant

Claims (12)

[Claims] 1. An epoxy resin composition for a prepreg, which comprises the following components [A] to [C]. [A]: Epoxy resin component consisting of bisphenol type epoxy resin and novolac type epoxy resin [B]: Guanidine compound and curing accelerator [C]: Reaction product of epoxy compound and imidazole 2. The epoxy resin composition for prepreg according to claim 1, wherein the novolac type epoxy resin of the component [A] is a phenol novolac type epoxy resin. 3. The epoxy resin composition for prepreg according to claim 1 or 2, wherein the guanidine compound as the component [B] is dicyandiamide. 4. The component [A] comprises bisphenol type epoxy resin in an amount of 40% by weight or more, and novolac type epoxy resin is 60%.
The epoxy resin composition for a prepreg according to any one of claims 1 to 3, wherein the epoxy resin composition is contained in an amount of not more than 5% by weight. 5. The viscosity of component [A] at 80 ° C. is 1 to 1.
It is 00 poise, The epoxy resin composition for prepregs in any one of Claims 1-4 characterized by the above-mentioned. 6. The component [A] comprises 60 to 90% by weight of a bisphenol type epoxy resin and 10 to 40% by weight of a novolac type epoxy resin, and the component [B] is added to 100 parts by weight of the component [A]. Guanidine compound is 0.3
-10 parts by weight, 0.3-20 parts of the curing accelerator of the component [B]
The epoxy resin composition for prepreg according to any one of claims 1 to 3, wherein the weight ratio and the component [C] are 5 to 30 weight parts. 7. A prepreg obtained by impregnating reinforcing fibers with an epoxy resin composition comprising the following components [A] to [C]. [A]: Epoxy resin component consisting of bisphenol type epoxy resin and novolac type epoxy resin [B]: Guanidine compound and curing accelerator [C]: Reaction product of epoxy compound and imidazole 8. The prepreg according to claim 7, wherein the novolac type epoxy resin of the component [A] is a phenol novolac type epoxy resin. 9. The prepreg according to claim 7 or 8, wherein the guanidine compound as the component [B] is dicyandiamide. 10. The component [A] comprises at least 40% by weight of a bisphenol type epoxy resin and a novolac type epoxy resin of 6%.
The prepreg according to any one of claims 7 to 9, which comprises 0% by weight or less. 11. The viscosity of component [A] at 80.degree.
The prepreg according to any one of claims 7 to 10, wherein the prepreg is 100 poise. 12. The component [A] comprises 60 to 90% by weight of a bisphenol type epoxy resin and 10 to 40% by weight of a novolac type epoxy resin, and the component [B] is added to 100 parts by weight of the component [A]. The guanidine-based compound is 0.
3 to 10 parts by weight, and the curing accelerator of the component [B] is 0.3 to 2
The prepreg according to any one of claims 7 to 9, wherein 0 part by weight and 5 to 30 parts by weight of the component [C] are included.