JPH0841174A - Epoxy resin composition and prepreg - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition which can give a molding of excellent impact resistance by mixing an epoxy resin with a urethane- modified epoxy resin, a low-temperature-activatable latent curing agent and a fibrous inorganic filler having a specified aspect ratio. CONSTITUTION:This composition is obtained by mixing an epoxy resin (e.g. bisphenol A epoxy resin) with a urethane-modified epoxy resin, a low- temperature-activatable latent curing agent and a fibrous inorganic filler having an aspect ratio of 3-500 (e.g. aluminum borate whisker). The above curing agent is desirably one which can be activated at near 80 deg.C and is exemplified by one of an amine adduct type which can be activated by heat melting or microencapsulated one of a wall rapture type. A prepreg obtained by impregnating a reinforcing fiber with this composition has suitable handleability and is amenable to free control of molding flow of a resin.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is excellent in handling workability such as appropriate tackiness (adhesiveness) and drapeability (flexibility) of prepreg, storage stability at room temperature, and good impact resistance. It can be molded at a relatively low temperature of around 80 ° C and has a small resin flow during molding. In particular, when molding tubular moldings made of fiber reinforced resin such as fishing rods and golf shafts, there is no furnace burnout and scratches on the polished surface of these moldings. The present invention relates to an epoxy resin composition suitable for a fiber reinforced composite material having excellent composite material properties without defects such as

[0002]

BACKGROUND OF THE INVENTION Fiber-reinforced composite materials such as carbon fibers are lightweight, have high strength and high elastic modulus, and are in the form of composites with resins, so-called prepregs, such as fishing rods, golf club shafts, and tennis. Sports and leisure fields such as rackets,
It is widely used for various applications such as industrial materials such as leaf springs and honeycomb structural materials, as well as structural materials for automobiles, aircraft materials, ships, etc., electronic materials, civil engineering and building materials.

The properties required for such a prepreg for a fiber-reinforced composite material include not only excellent handling workability, storage stability at room temperature, and mechanical properties of a cured product, but also the properties of a ship or vehicle in recent years. For molding large-scale structural materials, and molding using wooden molds and resin molds, there is a demand for curing at a lower temperature and for a shorter time, which shortens the molding cycle,
There is an increasing demand to reduce energy costs.

By the way, as a matrix resin for such a prepreg for a fiber-reinforced composite material, an epoxy resin is conventionally used (JP-A-62-127317 and JP-A-2-41314), and a rubber component is added thereto. Those added (JP-A-60-39286) and those added with urethane-modified epoxy resin (JP-B-62-44).
No. 011 and Japanese Patent Application Laid-Open No. 1-161041) have been proposed. However, these products have good workability in handling prepregs, for example, are free from defects such as scratches during polishing of the surface of tubular moldings, etc., and it is extremely difficult to obtain molded products with sufficient impact resistance. It was

In addition, to these matrix resins, a filler having a particle diameter of 10 times or less the diameter of the reinforcing single fiber, for example, graphite powder, carbon black, aluminum powder, silica powder, etc. is added to form a matrix resin for prepreg molding. Those having reduced fluidity (Japanese Patent Laid-Open No. 59-227931) and the like are used for producing prepregs. As a low-temperature curing prepreg, prepregs using a latent curing agent that cures at a relatively low temperature of 100 ° C. or lower are proposed in JP-A-5-9262 and JP-A-6-9802. These matrix resins need to be impregnated into the reinforcing fibers at a lower temperature in order to prevent deterioration in storage stability during the production of the prepreg as compared with the conventional ones, and therefore the resin viscosity needs to be set to be low. .

In particular, for tubular fiber-reinforced composite materials such as fishing rods and golf shafts, a sheet-shaped prepreg in which carbon fibers or glass fibers are aligned in one direction or a prepreg obtained by impregnating a woven fabric of the above-mentioned reinforcing fibers with a matrix resin is released. Wrap the taped mandrel coated with the agent in the longitudinal direction in the direction according to the desired design, and then wind the heat-shrinkable tape in a spiral shape using a tape winder etc. while gradually overlapping it. Then, put it in a heating furnace, harden the matrix resin while applying tightening force with heat shrinkable tape, remove from the heating furnace and remove the tape after cooling, pull out the mandrel with a core removing machine etc. . However, the conventional prepreg has a drawback that the prepreg moves from the large diameter side of the mandrel toward the small diameter side during molding, that is, so-called furnace drop occurs. This is because heating causes the matrix resin to have low viscosity and to increase fluidity, so when the tightening force of the heat-shrinkable tape is applied in such a state, the mandrel has a taper, and the mandrel has a taper from the large diameter side to the small diameter side. A component force is generated and a so-called furnace drop occurs in which the prepreg moves in this direction. When this furnace drop occurs, the distribution of the matrix resin and the reinforcing fibers becomes uneven, so that not only the desired composite material properties cannot be obtained, but also the cause of defects in the molded product or the warp of the small diameter portion occurs.

On the other hand, Japanese Unexamined Patent Publication No. 57-22636 discloses that
Prior to winding the prepreg around the mandrel, a method has been proposed in which a thread or a thread impregnated with a thermosetting resin is spirally wound in the longitudinal direction of the mandrel and the friction thereof prevents the furnace from falling. However, in this method, not only the effect of preventing the furnace from falling is not sufficient, but also the yarn remains in the molded product, which is not preferable in terms of characteristics. Further, in JP-A-59-159315, prior to winding the prepreg around the mandrel,
It has been proposed to prevent a furnace from falling by coating a mandrel with a thermosetting resin having a gel time at 130 ° C. of 80% or less of the resin for a prepreg matrix resin. However, this method requires a resin for undercoating, the gel time of which is adjusted by B-stage formation, and the step of applying the undercoating resin and air drying are required prior to molding, resulting in a marked decrease in productivity. Furthermore, these prepregs require a curing temperature of 100 ° C. or higher.

Regarding the handling property (tack and drape property) during the work of the prepreg, not only the productivity at the time of shaft winding but also the cause of defects (scratches etc.) on the surface of the molded product have appropriate characteristics. Required. If the tackiness is too strong, air is likely to be entrained at the time of winding, and if it is too low, workability such as laminating the prepreg deteriorates. In addition, when the drape property is insufficient, the prepreg is wound at the end portion of the winding, and particularly carbon fibers having a high elastic modulus may be broken. However, these factors appear on the surface as defects such as scratches at the time of polishing and coating after molding the shaft, causing defective products and deteriorating the physical properties, resulting in a significant reduction in yield. As described above, the prepreg using the conventional matrix resin composition has appropriate workability and excellent composite material properties, has good storage stability at room temperature, and is sufficiently cured by molding at 100 ° C or lower. However, it was extremely difficult to provide a prepreg which does not fall down during molding and has no defects on the polished or coated surface of the molded product.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the conventional method, to prevent the furnace from falling during molding without performing a pretreatment step, and to improve the impact resistance. Another object of the present invention is to obtain a fiber-reinforced composite material molded article which can be molded at a relatively low temperature of 100 ° C. or lower without deteriorating other composite material characteristics and has desired characteristics. Further, the prepreg using the epoxy resin composition of the present invention has an appropriate winding workability at a normal winding temperature, and since the resin flow at the time of molding can be freely controlled, it can be used after polishing. The object is to provide an excellent molded product that does not have defects (such as scratches) on the surface of the molded product.

[0010]

Means for Solving the Problems The present invention includes the following (A):
(B), (C) and (D) component (A) Epoxy resin (B) Urethane modified epoxy resin (C) Low temperature active latent curing agent (D) Fibrous inorganic filler having aspect ratio of 3 or more and 500 or less The present invention relates to an epoxy resin composition containing as an essential component, and a prepreg for a fiber-reinforced composite material, which is obtained by impregnating a reinforcing fiber with the epoxy resin composition.

The epoxy resin which is the component (A) used in the present invention is not particularly limited, and is a bisphenol A type epoxy resin or another glycidyl ether type epoxy resin such as a bisphenol F type epoxy resin or a bisphenol S type epoxy resin. Epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl amine type epoxy resin, naphthalene type epoxy resin, brominated bisphenol A type epoxy resin, glycidyl ester type epoxy resin, cycloaliphatic epoxy resin, heterocycle Formula epoxy resin etc. are mentioned. If desired, rubber-modified epoxy resin, alkyd-modified epoxy resin, etc. may be used. Among these, bisphenol A type epoxy resin and novolac type epoxy resin are preferable from the viewpoint of balance of handling property, economical efficiency, and physical properties of composite material, but two or more kinds of these can be appropriately mixed and used according to required characteristics.

As the urethane-modified epoxy resin as the component (B), those obtained by reacting a urethane prepolymer having an isocyanate group at the molecular end with an epoxy resin having a hydroxyl group in the molecule are used. As a urethane prepolymer having an isocyanate group (hereinafter referred to as NCO group) at the molecular end, which is a raw material of the urethane-modified epoxy resin, diisocyanate and polyether polyol,
Examples thereof include various ones obtained by reacting a polyol such as a polyester polyol with a conventional method. Examples of the diisocyanate include tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate, 4,4′-
Examples thereof include diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and the like, but particularly preferred are tolylene diisocyanate and 4,4′-diphenylmethane diisocyanate. As the polyol, polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, or glycerin, polyhydric alcohols such as trimethylolpropane or ethylene oxide of amines, alkylene oxide adducts such as propylene oxide, and the like, Polyether polyols usually having a molecular weight in the range of 500 to 3,000; oxalic acid, succinic acid,
Adipic acid, pimelic acid, azelaic acid, sebacic acid,
Phthalic acid, isophthalic acid, terephthalic acid, maleic acid,
Polycarboxylic acids such as fumaric acid and ethylene glycol, propylene glycol, 1,4-butanediol, 1,6
It is obtained by condensing a polyhydric alcohol such as hexanediol, diethylene glycol, trimethylolpropane, glycerin, neopentyl glycol, bis (hydroxymethylcyclohexane) under the condition that the molar ratio of the hydroxyl group to the carboxyl group is 1 or more, or Usually, the molecular weight obtained by ring-opening polymerization of a lactone such as caprolactone in the presence of a polyhydric alcohol is 500 to 3,000.
And polyester polyols in the range of

The reaction between the diisocyanate and the polyol such as polyether polyol or polyester polyol is usually carried out under the condition that the molar ratio of NCO group to hydroxyl group is more than 1, preferably 1.05-2, and the temperature is from room temperature to 120 ° C. It is carried out in. The urethane prepolymer thus obtained preferably has an NCO group content of 0.5 to 5% by weight and a molecular weight of 1,000 to 10,000. The NCO group content and molecular weight of the urethane prepolymer are Can be controlled by changing the raw material composition, that is, the molar ratio of NCO groups to hydroxyl groups.

The epoxy resin having a hydroxyl group in the molecule which is the other raw material of the urethane-modified epoxy resin is usually an epoxy resin having a molecular weight of 300 or more, particularly 350 or more. If the content of hydroxyl groups is too small, the object of the present invention cannot be achieved. Therefore, an epoxy resin having an average of 0.5 or more hydroxyl groups per epoxy resin molecule, for example, "E1001", "E1004", "E1".
009 "(made by Yuka Shell Co., Ltd.) or other bisphenol A type epoxy resin, or other hydroxyl group-containing epoxy resin used in the component (A), or hydroquinone, phenol novolac, cresol novolac, etc. are reacted with epichlorohydrin Alternatively, a hydroxyl group-containing epoxy resin having one or more epoxy groups may be used.

The reaction between the urethane prepolymer having an NCO group at the molecular end and the epoxy resin having a hydroxyl group in the molecule has a molar ratio of the hydroxyl group of the epoxy resin to the NCO group of more than 1, and preferably 3 to 40 as a raw material. It is carried out at a temperature of room temperature to 120 ° C., especially 60 to 100 ° C. until the NCO group completely disappears. The urethane-modified epoxy resin of the present invention is preferably one obtained by reacting the NCO group of the urethane prepolymer with the hydroxyl group of the epoxy resin, but at a reaction temperature of 100 ° C. or lower, an NCO group and Since the reaction with the hydroxyl group in the epoxy resin progresses preferentially, and the reaction between the NCO group and the epoxy group and the reaction between the NCO group and the urethane group do not substantially occur, the reaction under the above-mentioned conditions is effective for this purpose. Can be achieved.

The low temperature active latent curing agent as the component (C) is a curing agent which does not work as a curing agent at a temperature lower than 50 ° C. but is activated at a temperature of 50 ° C. or higher, and preferably at a temperature of around 80 ° C. Is a thermosetting latent curing agent that activates,
For example, an amine adduct-type latent curing agent that is activated by heat melting (“Amicure”: trademark of Ajinomoto Co., Inc.),
There are partition wall breaking type microcapsule type latent curing agents (“NOVACURE”: a trademark manufactured by Asahi Kasei Kogyo Co., Ltd.) and the like. These latent curing agents have good storage stability at around 50 ° C. Activates rapidly around ℃ and cures the epoxy resin. The addition amount of these latent curing agents is 3 to 60 parts by weight with respect to 100 parts by weight of the epoxy resin which is the component (A). If the amount is less than 3 parts by weight, the curing will be slow and sufficient properties cannot be obtained, and if it is more than 60 parts by weight, the storage stability and the physical properties of the cured product at room temperature will be significantly deteriorated, which is not preferable. Further, these latent curing agents have better curing reactivity at around 80 ° C. when used alone, but for the purpose of appropriate control of reactivity or storage stability,
Urea compounds, guanidine compounds, polyhydric carboxylic acid polyhydrazide compounds, amine imides, diaminomaleonitriles, guanamines, phenol resins, melamine resins, urea resins, etc. may be appropriately mixed and used as long as the characteristics are not deteriorated. it can.

As the fibrous inorganic filler as the component (D), those having an aspect ratio (fiber length / fiber diameter) of 3 or more and 500 or less, more preferably 3 or more and 450 or less are used. When the aspect ratio is less than 3, the resin flow at the time of molding is not sufficiently lowered, and when the aspect ratio is 500 or more, the impregnability into reinforcing fibers or the workability of prepreg and the moldability are adversely affected. These fibrous inorganic fillers are not particularly limited, but in natural products, there are, for example, sepiolite, wollastonite, asbestos, slag fibers, and in artificial products, for example, zonolite, elestadite, gypsum fibers, etc. ,
Also, for example, aluminum borate, calcium carbonate, silicon carbide, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, magnesia,
Examples include whiskers such as calcium sulfate, magnesium borate, titanium diboride, α-alumina and chrysotile. These fibrous inorganic fillers may be used alone or in combination of two or more. Of these, sepiolite, wollastonite or aluminum borate whiskers, calcium carbonate whiskers, and silicon carbide whiskers are particularly excellent in properties and economical efficiency. The addition amount of these fibrous inorganic fillers is 0.0 with respect to 100 parts by weight of the component (A).
5 to 30 parts by weight, preferably 0.5 to 15 parts by weight are used. If it is less than 0.5 part by weight, the flow during molding does not sufficiently decrease, and if it exceeds 15 parts by weight, the viscosity of the resin increases, and the impregnating ability of the fiber in the prepreg forming step tends to deteriorate, which is not preferable.

In addition to the above components, a thermoplastic resin, an epoxide-reactive diluent, etc. are added, if desired, so long as the impregnability into the reinforcing fiber is not deteriorated or the reactivity, heat resistance, storage stability and the like are not deteriorated. You may. Examples of thermoplastic resins include phenoxy resins, polyvinyl butyral, polyvinyl formal, acetal resins such as polyvinyl phenyl acetal, polyether sulfone, polysulfone, polyetherimide, polyarylate, and the like, and examples of reactive diluents. Examples include phenyl glycidyl ether, butyl glycidyl ether, alkyl glycidyl ether, styrene oxide, octylene oxide, and mixtures thereof.
In addition, coupling agents such as silane and titanate compounds, release agents such as higher fatty acids and waxes, halogens,
Additives such as a flame retardant such as a phosphorus compound, an antifoaming agent, a colorant, a low temperature foaming agent and the like can be used if necessary.

The reinforcing fibers used in the production of these prepregs include carbon fibers, glass fibers, aramid fibers, polyester fibers, silicon carbide fibers, boron fibers,
Alumina fibers, polyethylene fibers, etc. may be mentioned, and one kind or two or more kinds of them may be appropriately used. To manufacture prepreg, general prepreg manufacturing methods can be applied,
The reinforcing base material may be impregnated directly by the hot melt method or by the film method, or by the solvent impregnation method or by impregnation after film formation, but the solvent impregnation method requires a solvent distillation step. Moreover, the stability of the resin composition may be decreased, which is not preferable.

[0020]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. The abbreviations of the compounds used in the examples and the test methods are as follows. <Raw material>"E828": Bisphenol A type epoxy resin (made by Yuka Shell Co., Ltd.) "E1001": Bisphenol A type epoxy resin (made by Yuka Shell Co., Ltd.) "EPU-6": Urethane modified epoxy resin (Asahi Denka Kogyo ( Co., Ltd.) "PN-23", "MY-24": Amine adduct type latent curing agent (manufactured by Ajinomoto Co.) "HX-3722": Microcapsule type latent curing agent (manufactured by Asahi Kasei) ["E828 ] / Curing agent = 2/3 parts by weight masterbatch] DICY: Dicyandiamide (manufactured by Yuka Shell Co., Ltd.) DCMU: 3- (3,4-dichlorophenyl) -1,1
-N dimethyl urea (manufactured by Hodogaya Chemical Co., Ltd.) "Milcon PS": Sepiolite (manufactured by Showa Mining Co., Ltd.) <Aspect ratio = 50>"NYAD325": Wollastonite (manufactured by NYCO) <Aspect ratio = 5>""ArborexY","YS2": Aluminum borate whiskers (manufactured by Shikoku Chemicals Co., Ltd.) <Aspect ratio = 10 to 60) "Whiscar": Calcium carbonate whiskers (manufactured by Shikoku Chemicals Co., Ltd.) <Aspect Ratio = 20-60>"R202": Fine silica, "Aerosil R202"
(Manufactured by Nippon Aerosil Co., Ltd.) "Talc SWB": Talc, average particle size 10 μm (manufactured by Nippon Talc Co., Ltd.)

<Measurement of Resin Flow> 10 prepregs
Cut to 0 x 100 mm and stack 4 plies,
After laminating the top and bottom perforated films and glass cloth on the outermost layer, press it at 80 ° C and 3.5 Kg / cm ² with a heating press,
Measure the resin flow. <Evaluation of winding and furnace fallout> Prepreg is applied in an oblique layer (± 4
5 °) 3ply and straight layer (0 °) 3ply were cut. The cut prepreg was wound on a mandrel coated with a release agent by a rolling table. The heat shrink tape was then wrapped with a tape wrapping machine. It was hung in a heating furnace with the large diameter side up and cured at 80 ° C. for 2 hours. After cooling to room temperature, measure the furnace falling.

<Handling workability: tackiness, drapeability>
(Comprehensive judgment based on the laminated state of the oblique layer at 23 ° C., correctability, hardness of manual winding, shaving after rolling the rolling table, etc.) Good ... Poor ... Bending test (3 Point Bending)> According to ASTM D790, using an apparatus: "UTM-5T" manufactured by Toyo Baldwin Co., Ltd., sample shape: (length 100 mm, width 10 mm,
Thickness 2 mm), span length: 80 mm, crosshead speed: 2 mm / min, and measure strength in 0 ° and 90 ° directions.

<ILSS> According to ASTM D2344, sample shape: (length 12 mm,
Width 10 mm, thickness 2 mm), span length: 8 mm, crosshead speed: 2 mm / min. <Izod impact test> According to JIS K7110, a universal impact tester manufactured by Toyo Seiki Co., Ltd. is used.
Sample shape: (length 70mm, width 10mm, thickness 2m
Measure the strength in the 0 ° direction with m).

[Synthesis of Urethane Prepolymer] (Synthesis Example 1) 70 parts by weight of polyoxypropylene glycol having a molecular weight of 2,000 and propylene oxide adduct 3 of trimethylolpropane having a weight average molecular weight of 3,000
When 0 part by weight and 17 parts by weight of tolylene diisocyanate were mixed in a flask substituted with nitrogen and reacted at 90 ° C. for 4 hours, a highly viscous urethane prepolymer having an NCO group content of 2.82% (hereinafter referred to as prepolymer [A ]) Was obtained.

(Synthesis Example 2) Polyoxytetramethylene glycol 10 having a molecular weight of 1,000 and melted at a temperature of 50 ° C. with a flask containing 32 parts by weight of melted 4,4′-diphenylmethanediisocyanate was replaced with nitrogen.
0 parts by weight from the dropping funnel for about 30 minutes, the internal temperature is 60 ℃
It was dripped so as not to exceed the limit. After dropping, the internal temperature is up to 9
When the temperature was raised to 0 ° C. to complete the reaction, a semisolid urethane prepolymer having an NCO group content of 1.86% (hereinafter referred to as prepolymer [B]) was obtained.

[Synthesis of Urethane Modified Epoxy Resin] (Example 1) 60 parts by weight of "E828", "E100"
40 parts by weight of "1" are dissolved by stirring in a nitrogen atmosphere at 100 ° C for 1 hour, and then 15 parts by weight of prepolymer [A] is added and the mixture is added at 100 ° C for 2 hours with NCO groups in the urethane prepolymer and hydroxyl groups in the epoxy resin. By reacting with, a base resin partially containing a urethane-modified epoxy resin was obtained. The NCO group disappeared completely under these conditions. After cooling this base resin to room temperature, it was heated to 55 ° C. and 20 parts by weight of “PN-23” was added with a stirrer, “Milcon PS”.
Was added to 5 parts by weight and uniformly stirred and mixed for 30 minutes to obtain a resin composition of the present invention. A unidirectional prepreg was produced from the resin composition thus obtained and high-strength carbon fiber (“Torayca T700” manufactured by Toray Industries, Inc., elastic modulus 24 ton / mm ² ) by a hot melt method to obtain a prepreg of the present invention. The carbon fiber areal weight of this prepreg was 125 g / m ² , and the resin amount was 35%. Sixteen plies of this prepreg were laminated in one direction and cured at 80 ° C. for 2 hours in an autoclave to form a unidirectional laminated plate having a thickness of about 2 mm. Table 1 shows the physical properties (Vf = 60% conversion value) of the obtained composite material. Of these physical properties, especially 90 ° C bending strength and Izod
The impact strength showed excellent characteristics.

[0027]

[Table 1]

Further, this prepreg had good handling workability (tacking and drapeability), and 10 shaft moldings obtained had no furnace blowout at all. Furthermore, the surface of this molded product was polished with a polishing machine and observed for surface defects (scratches, etc.), and good molded products without any defects were obtained.

(Examples 2, 3, 4, 5) Using the compositions shown in Table 1, resin compositions and prepregs of the present invention were obtained in the same manner as in Example 1. The handling workability of this prepreg was good, and 90 ° bending strength and Izod impact strength showed excellent characteristics. Further, the molded product did not fall down from the furnace, and no defect was observed on the polished surface.

(Comparative Example 1) According to the composition of Table-1, (B)
A prepreg was produced in the same manner as in Example 1 except that the component (D) was not used. The basis weight of the prepreg was 125 g / m ² , and the resin amount was 35%. This prepreg had high tackiness, poor handleability, and large resin flow, and the furnace fell. Further, the occurrence of scratches after polishing the molded product was remarkable.

(Comparative Examples 2 and 3) A prepreg was produced in the same manner as in Example 1 except that the component (B) was not used and "Aerosil R202" or "talc SWB" was used as the inorganic filler. The workability of this prepreg was relatively good, but the furnace fell, unevenness was found on the surface of the molded product, and scratches were observed on several out of 10 after polishing.

(Comparative Example 4) A prepreg was produced in the same manner as in Example 1 except that the component (D) was not used. The workability was poor, and sufficient Izod impact strength was not obtained. (Comparative Example 5) According to the composition of Table 1, DICY was added to the component (C).
Was used and 4 parts by weight of DCMU were used to produce a prepreg in the same manner as in Example 1. The workability was poor, and the hardening was insufficient so that cutting was not possible.

[0033]

EFFECTS OF THE INVENTION The prepreg manufactured from the matrix resin of the present invention is capable of being appropriately adjusted in proper handling workability and resin flow at the time of molding, open molding,
Various moldings with excellent composite material properties, suitable for large-scale molding, because moldings with excellent impact resistance can be obtained without defects by molding methods such as internal pressure molding. Is obtained. As described above, it is extremely useful for improving the reliability, productivity, and economic efficiency of the fiber-reinforced composite material.

Claims (6)

[Claims] 1. An epoxy resin composition comprising the following components (A), (B), (C) and (D). (A) Epoxy resin (B) Urethane-modified epoxy resin (C) Low temperature active latent curing agent (D) Fibrous inorganic filler having an aspect ratio of 3 or more and 500 or less 2. The epoxy resin composition according to claim 1, wherein the low temperature active latent curing agent (C) is an amine adduct type latent curing agent. 3. The epoxy resin composition according to claim 1, wherein the low temperature active latent curing agent (C) is a microcapsule type latent curing agent. 4. The epoxy resin composition according to claim 1, wherein the fibrous inorganic filler (D) is at least one selected from sepiolite, wollastonite, aluminum borate whiskers and calcium carbonate whiskers. Stuff. 5. A prepreg obtained by impregnating a reinforcing fiber with the epoxy resin composition according to any one of claims 1 to 4. 6. The prepreg according to claim 5, wherein the reinforcing fibers are carbon fibers.