JPH07228716A - Prepreg - Google Patents

Abstract

PURPOSE:To prepare a prepreg, having excellent storage stability and other properties, which can provide a composite material having excellent impact strength. CONSTITUTION:A carbon fiber having a tensile elongation of not less than 1.7% is impregnated with a bisphenol A epoxy resin having an epoxy equivalent of 140 to 250 and/or a resin compsn., having a viscosity at 80 deg.C of 20 to 300 P, comprising, as indispensable ingredients, a mixture A of a bisphenol F epoxy resin A1 having an epoxy equivalent 140 to 250 and a bisphenol A epoxy resin A2 having an epoxy equivalent of 350 to 1000 in a A1 to A2 wt. ratio of 0.3 to 3, a reaction product B between a liquid butadiene/acrylonitrile copolymer, having a carboxyl group on its both molecular ends and an acrylonitrile content of 10 to 30wt.%, and an epoxy resin Al, and a dicyandiamide and/or curing accelerator C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention provides a composite material having excellent impact resistance by heat curing and has a suitable tack,
The present invention relates to a prepreg having drape property and excellent storage stability.

[0002]

2. Description of the Related Art A carbon fiber reinforced composite material having an epoxy resin as a matrix is excellent in mechanical properties and is utilized in various applications by utilizing this characteristic.

Recently, in sports applications, lighter weight and more durable products are required. In particular, for products such as golf shafts, tennis rackets, and baseball bats that are subjected to a momentary large load, it is necessary to significantly improve the impact resistance of the material in order to reduce the weight and improve the durability. Becomes

Conventionally, for sports purposes, for example, Japanese Patent Publication No.
As described in JP-A-8-40975 and JP-B-60-47290, dicyandiamide as a curing agent and 3- (3,4) as a curing accelerator in a mixture of a bisphenol type epoxy resin and a novolac type epoxy resin.
Many prepregs have been used in which carbon fibers are impregnated with an epoxy resin composition containing -dichlorophenyl) -1,1-dimethylurea. Heat-cured composite materials have excellent performance against static loads such as tension, bending, and compression, but impact resistance is not at a satisfactory level, and products with momentary large loads are not suitable. Is not suitable.

In order to improve the impact resistance of composite materials, attempts have been made to improve the fracture toughness of matrix resins by adding a rubber component.

For example, Japanese Patent Publication No. 62-34251 proposes a resin composition obtained by adding nitrile rubber to a mixture of an epoxy resin and a phenoxy resin having a molecular weight of 10,000 or more. Further, JP-B-63-12091 discloses a resin composition described in JP-B-62-34251, which is a reaction product of a liquid butadiene-acrylonitrile copolymer (hereinafter CTBN) having a carboxyl group at both molecular ends and an epoxy resin. A resin composition to which is further added is proposed. The honeycomb sandwich panel using the prepreg impregnated with these resin compositions has good penetration impact strength.

Further, JP-A-2-296858 proposes a resin composition obtained by adding CTBN to a bisphenol A type epoxy resin, and compresses a unidirectional composite material using a prepreg impregnated with the resin composition after impact. It is said that the strength is good.

[0008]

However, JP-B-62-34251 and JP-B-63-1209.
When nitrile rubber is added as in JP-A-1 No. 1, the impact resistance is improved but the heat resistance is greatly reduced.

Further, when the CTBN is directly added to the epoxy resin as in JP-A-2-296858, the impact resistance cannot be improved so much, and the dispersion state of the rubber component changes depending on the molding conditions. However, it has a drawback that the physical properties of the material including the impact resistance vary greatly.

An object of the present invention is to provide a prepreg which has improved such drawbacks, provides a composite material having excellent impact resistance, and has appropriate tack, drape, and excellent storage stability. is there.

[0011]

The prepreg of the present invention has the following constitution in order to achieve the above object. That is, a carbon fiber having a tensile elongation of 1.7% or more is impregnated with a resin composition composed of the following components [A], [B], and [C] and having a viscosity of 20 to 300 poise at 80 ° C. It is a prepreg.

[A]: Bisphenol A type epoxy resin having an epoxy equivalent of 140 to 250 and / or bisphenol F type epoxy resin (A ₁ ) having an epoxy equivalent of 140 to 250, and bisphenol A type having an epoxy equivalent of 350 to 1000. A mixture composed of an epoxy resin (A ₂ ) and having a weight ratio (A ₁ ) / (A ₂ ) of 0.3 to 3 [B]: Carboxyl groups at both molecular ends and an acrylonitrile content of 10 Liquid butadiene-acrylonitrile copolymer of about 30% by weight and an epoxy equivalent of 14
0-250 bisphenol A type epoxy resin and /
Alternatively, a reaction product with a bisphenol F type epoxy resin having an epoxy equivalent of 140 to 250 [C]: dicyandiamide and / or a curing accelerator Hereinafter, the present invention will be described in detail.

In the present invention, it is an essential condition to use high strength and high elongation carbon fiber having a tensile elongation of 1.7% or more in combination with the resin composition according to the present invention. The object of the invention cannot be achieved.

First, the tensile elongation of the carbon fiber used is 1.7.
% Or more, and more preferably 1.9% or more. With carbon fibers having a tensile elongation of less than 1.7%, excellent impact resistance cannot be realized even when used in combination with the resin composition according to the present invention.

The resin composition comprises [A], [B] and [C]. [A] is an epoxy resin component, and [B] contributes to the improvement of fracture toughness of the resin composition. [C] acts as a curing agent and / or a curing accelerator. Ingredient [A],
In addition to [B] and [C], for example, polyvinyl formal,
Thermoplastic resins such as polyetherimide and polyether sulfone, diluents such as phenylglycidyl ether,
A filler such as silicon fine particles may be contained.

The viscosity of the resin composition is 20 at 80 ° C.
To 300 poise, preferably 20 to 150 poise. If the viscosity is less than 20 poise, the prepreg is too soft and the handleability is poor, and if it exceeds 300 poise, it becomes difficult to impregnate the carbon fiber with the resin.

Hereinafter, the components [A], [B] of the resin composition,
[C] will be described in detail.

(Explanation of Component [A]) [A] is a bisphenol A type epoxy resin having an epoxy equivalent of 140 to 250 and / or a bisphenol F type epoxy resin (A ₁ ) having an epoxy equivalent of 140 to 250, and an epoxy. It is composed of a bisphenol A type epoxy resin (A ₂ ) having an equivalent weight of 350 to 1000.

Examples of the bisphenol A type epoxy resin used for (A ₁ ) include Epicoat Ep825, Ep
p827, Ep828 (Okaka Shell Epoxy Co., Ltd.)
Manufactured), DER331, DER337 (manufactured by Dow Chemical Japan Co., Ltd.), Araldite GY250, GY260 (manufactured by Ciba-Geigy Co., Ltd.), Epicron Epc850
(Manufactured by Dainippon Ink and Chemicals, Inc.), Epotote YD1
28 (manufactured by Tohto Kasei Co., Ltd.) and the like, as a bisphenol F type epoxy resin, Epicoat Ep807 (manufactured by Yuka Shell Epoxy Co., Ltd.), Epicron Epc830 (manufactured by Dainippon Ink and Chemicals, Inc.), Araldite XPY306.
(Nippon Ciba Geigy Co., Ltd.) can be used. Here, the epoxy equivalents of the bisphenol A type epoxy resin and the bisphenol F type epoxy resin are both 140 to 2
It is set to 50. If it is out of this range, it becomes difficult to control the tack (adhesiveness) and drapability of the prepreg, and it becomes difficult to increase the glass transition temperature of the molded product after heat curing.

As (A ₂ ), for example, Epicoat Ep
1001, Ep1004 (Okaka Shell Epoxy Co., Ltd.)
, DER661, DER663 (manufactured by Dow Chemical Japan Co., Ltd.), Araldite 6071, 7072 (manufactured by Nippon Ciba Geigy Co., Ltd.) and the like can be used.

The prepreg, a suitable tack i.e. tacky, in order to have a drapability is in the range of (A ₁₎ and the weight ratio of _{(A 2) (A 1)} / (A 2) is 0.3
~ 3 must be satisfied. More preferably 0.4-
It is 2.5. When (A ₁ ) / (A ₂ ) is less than 0.3, the prepreg is stiff, and both tack and drape are insufficient. On the other hand, when it exceeds 3, tackiness is excessive but tack is excessive, and the prepreg is easily handled. It is not preferable because it worsens.

If the epoxy resin component other than (A ₁ ) and (A ₂ ) has less than 3 glycidyl groups per molecule, the tackiness and drapability of the prepreg are not impaired. However, an epoxy resin having three or more glycidyl groups per molecule leads to a decrease in impact resistance of the composite material, and thus is not preferable.

(Explanation of Component [B]) The component [B] exists in the matrix resin of the composite material as phase-separated into islands of 0.1 to 5 μm and contributes to the improvement of fracture toughness of the matrix resin. . Moreover, since the shape and size of the phase-separated structure are stable and do not change depending on the molding conditions, the physical properties of the material are not easily influenced by the molding conditions.

[B] is a liquid butadiene-acrylonitrile copolymer (hereinafter referred to as CTBN) having carboxyl groups at both molecular ends, and a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin having an epoxy equivalent of 140 to 250. It is a reactant and is produced by reacting CTBN and an epoxy resin in the presence of a suitable catalyst such as triphenylphosphine at 120 to 170 ° C. The CTBN used has an acrylonitrile content (hereinafter referred to as AN content) of 10 to 30%, for example, Hycar CT.
BN1300 × 31 (AN content 10% by weight), Hyca
r CTBN1300 × 8 (AN content 17% by weight), H
ycar CTBN1300 × 13 (AN content 27% by weight) (both manufactured by Ube Industries, Ltd.) can be used, but when the AN content is 15 to 30% by weight, the impact resistance of the composite material is greatly improved. , And more preferably. AN
If the content is less than 10% by weight, the compatibility with the resin is poor, and if it exceeds 30% by weight, the compound is uniformly dissolved in the resin, and neither impact resistance is improved. Further, the epoxy resin to be reacted with CTBN may be the same as or different from (A ₁ ) of the component [A].

[B] is a structure in which CTBN and an epoxy resin are linked, and glycidyl groups are present at both molecular ends. The number average molecular weight is 400 from the viewpoint that the impact resistance is greatly improved and the carbon fiber is easily impregnated.
It is preferably 0 to 20000, and more preferably 6000 to 15000. The molecular weight can be controlled within this range by using a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin having an epoxy equivalent of 140 to 250.

The blending amount of [B] is component [A] 10 from the viewpoint of improving impact resistance and suppressing deterioration of heat resistance.
It is preferably 2 to 30 parts by weight, more preferably 5 to 25 parts by weight, relative to 0 parts by weight.

(Description of Component [C]) Dicyandiamide (hereinafter, DICY) acts as a curing agent. Examples of the curing accelerator include 3- (3,4-dichlorophenyl) -1,1-dimethylurea (hereinafter DCMU), 3
A urea derivative such as-(3-chlorophenyl) -1,1-dimethylurea, an imidazole compound, a tertiary amine compound, or the like can be used, but DCMU having excellent storage stability is preferable.

[0028]

EXAMPLES The contents of the components [A] and [B] of the carbon fiber and resin composition used in the examples are as follows.

Carbon fiber: "Torayca" T700S (registered trademark, tensile elongation 2.1%, tensile strength 490 kgf / mm ² , tensile elastic modulus 23500 kgf / mm ² , manufactured by Toray Industries, Inc.) Component [A]: (A ₁ ) Epicoat Ep828 (bisphenol A type epoxy resin, epoxy equivalent 184 to 194, manufactured by Yuka Shell Epoxy Co., Ltd.) and Epiclon Epc830 (bisphenol F type epoxy resin, epoxy equivalent 165 to 165)
185, manufactured by Dainippon Ink and Chemicals, Inc. (A ₂ ) Epicoat Ep1001 (epoxy equivalent 450)
-500, manufactured by Yuka Shell Epoxy Co., Ltd. Component [B]: CTBN / epoxy reaction product (1) Hycar CTBN1300 × 13 (AN content 27)
%, Ube Industries, Ltd. and Epicoat Ep828 reaction product (number average molecular weight 9600) CTBN / epoxy reaction product (2) Hycar CTBN1300 × 8 (AN content 17%,
Ube Industries, Ltd. product and Epicoat Ep828 reaction product (number average molecular weight 10000) (Example 1) Ep828 40 parts by weight (component (A ₁ )), Ep1001 60 parts by weight (component (A ₂ )) at 120 ° C. The mixture was heated and melted at 1, and kneaded while being cooled, and 10 parts by weight of CTBN / epoxy reaction product (1) was added at 90 ° C., and 1 part by weight of DICY and 4 parts by weight of DCMU were added at 60 ° C. to obtain a resin composition. 80 of this resin composition
The viscosity at ° C was 37 poise.

A resin film was produced from the above resin product with a film coater. Next, the aligned carbon fibers "Torayca" T700S were sandwiched between resin films and impregnated with the resin by heating and pressing to obtain a unidirectional prepreg with a resin content of 33% by weight.

After the prepreg was cut and laminated, it was heat-cured in an autoclave at 135 ° C. for 2 hours to form a unidirectional material having a thickness of 3 mm. When the Tg of the unidirectional material was measured by DSC at a temperature rising rate of 40 ° C./minute, it was 107 ° C.

From the unidirectional member, width 12.7 mm, length 64
A test piece of mm was cut out, and an edgewise impact, that is, an impact in a direction parallel to the surface of the unidirectional material was applied by a hammer having a capacity of 150 kgf · cm to measure the Izod impact value. No notch was introduced in the test piece. The Izod impact value was 313 kgf · m / cm ² .

A 1 mm thick unidirectional material was molded from this prepreg and subjected to a 0 ° tensile test in accordance with JIS K 7073. The breaking elongation was 1.90%. Table 1 shows the measurement results of Tg, Izod impact value, and 0 ° breaking elongation of the unidirectional material.

[0034]

[Table 1] (Example 2) A resin composition was prepared in the same manner by using CTBN / epoxy reactant (2) instead of CTBN / epoxy reactant (1) of Example 1. 8 of this resin composition
The viscosity at 0 ° C. was 23 poise. A prepreg was prepared and a unidirectional material was molded in the same manner as in the example. Unidirectional material T
Table 1 shows the measurement results of g, Izod impact value, and 0 ° elongation at break.
Shown in.

(Example 3) Ep82 as the component (A ₁ )
855 parts by weight, Ep1001 4 as component (A ₂ ).
A resin composition was obtained by kneading 0 parts by weight, 20 parts by weight of CTBN / epoxy reaction product (1), 4 parts by weight of DICY, and 5 parts by weight of DCMU in the same manner as in Example 1. The viscosity of this resin composition at 80 ° C. was 48 poise. A prepreg was prepared in the same manner as in Example 1, and a unidirectional material was molded. Table 1 shows the measurement results of Tg, Izod impact value, and 0 ° breaking elongation of the unidirectional material.

(Example 4) Ep82 as the component (A ₁ )
8 15 parts by weight and Epc830 20 parts by weight, component (A
₂ ) Ep1001 65 parts by weight, CTBN / epoxy reaction product (1) 10 parts by weight, DICY 3 parts by weight, D
5 parts by weight of CMU were kneaded in the same manner as in Example 1 to obtain a resin composition. The viscosity of this resin composition at 80 ° C. was 28 poise. A prepreg was prepared in the same manner as in Example 1,
A unidirectional material was molded. Table 1 shows the measurement results of Tg, Izod impact value, and 0 ° breaking elongation of the unidirectional material.

(Comparative Example 1) A resin composition was obtained by similarly kneading the components except the CTBN / epoxy reaction product (1) from Example 1. The viscosity of this resin composition at 80 ° C. was 14 poise. A prepreg was prepared in the same manner as in Example 1 and a unidirectional material was molded, but the prepreg was too soft, and thus the laminating operation was difficult. Table 1 shows the measurement results of Tg, Izod impact value, and 0 ° breaking elongation of the unidirectional material. Both the Izod impact value and the 0 ° breaking elongation were inferior to those of Examples 1 to 4.

Comparative Example 2 40 parts by weight of a phenol novolac type epoxy resin Epicoat Ep154 (produced by Yuka Shell Epoxy Co., Ltd.) having an average of 3.6 glycidyl groups per molecule and 25 parts by weight of Ep828,
Ep1001 35 parts by weight, CTBN / epoxy reaction product (1) 10 parts by weight, DICY 1 part by weight, DCMU
5 parts by weight were kneaded in the same manner as in Example 1 to obtain a resin composition. The viscosity of this resin composition at 80 ° C. was 33 poise. A prepreg was prepared in the same manner as in Example 1, and a unidirectional material was molded. Table 1 shows the measurement results of Tg, Izod impact value, and 0 ° breaking elongation of the unidirectional material. Izod impact value, 0
Both of the breaking elongations were inferior to those of Examples 1 to 4.

(Comparative Example 3) Hycar CTBN130 was used in place of the CTBN / epoxy reaction product (1) of Example 1.
A resin composition was obtained using 0 × 13 (AN content 27%). The viscosity of this resin composition at 80 ° C. was 20 poise. As in Example 1, a prepreg was prepared and a unidirectional material was molded. Table 1 shows the measurement results of Tg, Izod impact value, and 0 ° breaking elongation of the unidirectional material. Tg of unidirectional material is 91
The heat resistance was lower than that of Examples 1 to 4 at 0 ° C and was inferior. The Izod impact value of the unidirectional material was superior to Comparative Examples 1 and 2, but was inferior to Examples 1 to 4.

(Comparative Example 4) Instead of the carbon fiber "Torayca" T700S of Example 1, "Torayca" T300 (manufactured by Toray Industries, Inc., tensile elongation 1.5%, tensile strength 360 kgf / m).
m ² and tensile elastic modulus of 23500 kgf / mm ² ) were impregnated with the resin composition of Example 1 to prepare a prepreg, and a unidirectional material was molded. Tg of unidirectional material, Izod impact value, 0
Table 1 shows the measurement results of the breaking elongation. Both the Izod impact value and the 0 ° breaking elongation were inferior to those of Examples 1 to 4.

[0041]

EFFECTS OF THE INVENTION According to the present invention, a composite material having excellent impact resistance as compared with conventional prepregs can be obtained, and therefore, it can be widely applied to many applications including the field of sports, and the weight and durability of the product can be reduced. It is possible to improve the sex.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08J 5/04 CFC 7310-4F C08L 63/00 NJW // B29K 263: 00 307: 04 (72) Inventor Hiroshi Takagishi 1515 Tsutsui, Matsumae-cho, Iyo-gun, Ehime Prefecture Toray Industries, Inc. Ehime factory

Claims (1)

[Claims] 1. A carbon fiber having a tensile elongation of 1.7% or more, which comprises the following components [A], [B], and [C] at 80 ° C.
A prepreg impregnated with a resin composition having a viscosity of 20 to 300 poise. [A]: Bisphenol A type epoxy resin having an epoxy equivalent of 140 to 250 and / or an epoxy equivalent of 14
0-250 bisphenol F type epoxy resin (A ₁ )
And a bisphenol A type epoxy resin (A ₂ ) having an epoxy equivalent of 350 to 1000, and the weight ratio (A
₁ ) / (A ₂ ) is a mixture of 0.3 to 3 [B]: a liquid butadiene-acrylonitrile copolymer having a carboxyl group at both molecular ends and an acrylonitrile content of 10 to 30% by weight, Epoxy equivalent is 14
0-250 bisphenol A type epoxy resin and /
Or a reaction product with a bisphenol F type epoxy resin having an epoxy equivalent of 140 to 250 [C]: dicyandiamide and / or a curing accelerator