JPH09100358A - Epoxy resin composition for carbon-fiber reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin compsn. for a carbon-fiber-reinforced composite material excellent in adhesion to carbon fiber by using a resin compsn. having a specified viscosity and contg. a disphenol A epoxy resin, a specific epoxy resin, and a curative as the essential ingredients. SOLUTION: This compsn. has a viscosity of 100-5,000P at 60 deg.C and contains, as the essential ingredients, a disphenol A epoxy resin, an epoxy resin having a structure represented by formula I [wherein each R is independently H or methyl; X1 to X4 are each independently a halogen, H, or a 1-4C alkyl provided at least one of them is a halogen; R1 to R4 are each independently H or a 1-4C alkyl; and A is a group represented by formula II (wherein R1 to R4 are each independently H or a 1-4C alkyl) or formula III (wherein R1 ' to R8 ' are each independently H or a 1-4C alkyl; and B is a single bond, CH2 , C(CH3 )2 , SO2 , SO, S, or O)], and a curative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a carbon fiber (hereinafter,
It relates to an epoxy resin composition for a carbon fiber reinforced composite material (hereinafter referred to as CFRP) which is particularly excellent in adhesiveness to CF).

[0002]

2. Description of the Related Art Epoxy resins have been used in a wide range of fields because they have excellent mechanical properties, electrical properties, adhesiveness, etc. after curing. For example, it is widely used as a sealing material for electronic materials, paints / paving materials, and adhesives. Also CFR
It has come to be used as a resin composition for P as well, and is widely used from aircraft applications to general-purpose applications such as fishing rods and golf club shafts.

As a material for molding the CFRP, a prepreg in which an epoxy resin composition is impregnated with CF or the like is generally used, and the matrix resin of the prepreg is excellent in mechanical properties after molding. thing,
It is required to have excellent adhesiveness with CF, excellent tackiness and excellent workability. At present, epoxy resins are most commonly used as matrix resins for prepregs in order to satisfy the above requirements in a well-balanced manner.

However, the above-mentioned characteristics are of course greatly influenced by the composition, and the most commonly used compositions at present are bisphenol A type epoxy resin and phenol novolac type epoxy resin as main components, and a curing agent. However, the problem with this composition is that the adhesiveness to CF is insufficient, and especially the adhesiveness to highly elastic CF and pitch-based CF is not good. As means for solving this, JP-A-63-37135, JP-A-63-37136, and JP-A-63-37137 disclose that a thermoplastic resin such as polyvinyl formal is dissolved and added to the resin composition. However, dissolution in the epoxy resin usually requires stirring at a temperature of around 150 ° C. for 2 hours or more, which is quite troublesome. Also, in the prepreg preparation step, a matrix resin is usually applied to release paper in a thickness of several tens of microns and impregnated into CF, but when the thermoplastic resin is dissolved, the viscosity of the composition is considerably increased, and these coatings are applied. However, the passability of the impregnation process is adversely affected. In addition, the physical properties also have an adverse effect such as an increase in water absorption.

[0005]

In view of the above, the present inventors improve the adhesiveness with CF and the physical properties of CFRP without increasing the viscosity to the extent that the process passability is adversely affected. As a result of earnestly studying the resin composition, the present invention has been achieved.

[0006]

The gist of the present invention is (A)
A carbon fiber reinforced composite material having a bisphenol A type epoxy resin, (B) an epoxy resin having a structure represented by the following formula (1), and (C) a curing agent as essential components and having a viscosity at 60 ° C. of 100 to 5000 poises. Epoxy resin composition for use.

[0007]

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[0008]

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[0009]

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[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the bisphenol A type epoxy resin as the component (A) of the epoxy resin composition of the present invention, commercially available products can be used. Typical examples include Epicoat 828, 834, 1001, 1009 manufactured by Yuka Shell Epoxy Co., Ltd. The epoxy equivalent and the molecular weight are not limited as long as they are in the viscosity range described below when the composition is used.

Further, the component (B) of the epoxy resin composition of the present invention is required to have a skeleton represented by the following formula (1) in order to achieve the object of the present invention. The number of epoxy groups per molecule is preferably 1.2 to 5 functional on average,
The trifunctionality is more preferable.

[0012]

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[0013]

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[0014]

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Examples of such a resin include XAC4151 and 4152 manufactured by Asahi Ciba Co., Ltd.

The component (C) of the epoxy resin composition of the present invention is not particularly limited as long as it is one usually used as a curing agent for epoxy resin compositions.
Representative examples thereof include dicyandiamide, urea compounds, amine compounds, acid anhydrides, imidazole compounds, phenol compounds, and the like.

The epoxy resin composition of the present invention is used as a matrix resin for prepreg at 100 to 500 at 60 ° C.
Must be 0 poise. If the viscosity is less than 100 poise, the tack is too strong and the resin flow during molding is increased, which is not preferable. On the other hand, if it exceeds 5000 poise, the prepreg is not sufficiently impregnated with the resin, the tack is too much, and the prepreg becomes hard, which is not preferable. A more preferable range is 300 to
It is 3000 poise.

The epoxy resin composition of the present invention is (A) /
The weight ratio of (B) is preferably in the range of 30/70 to 90/10. Outside this range, the balance between the heat resistance and the adhesiveness to CF tends to decrease, and the strength in the 90 ° direction with respect to the fiber axis of the unidirectional CFRP will decrease.

Further, other epoxy resins and the like can be added to the epoxy resin composition of the present invention within a range satisfying the above conditions. For example, epoxy resins such as bisphenol F type, glycidyl amine type, and aminophenol type can be used.

Further, a prepreg having good handleability obtained by impregnating and integrating the epoxy resin composition of the present invention with a reinforcing fiber containing CF as a main component has physical properties after molding, particularly 90 ° of a unidirectional agent. Excellent in directional strength.

The type and form of the CF material are not particularly limited,
A unidirectional material of CF alone, a woven fabric, or a hybrid of glass or aramid fiber may be used. The CF itself is not particularly limited, and may be a pan-based or pitch-based CF.
There is no limit to the strength.

[0022]

The present invention will be described in more detail with reference to the following examples. The symbol of the compound in an Example, and a test method are as follows.

(Compound symbol) Ep828: Bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd. Ep1001: Bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd. Ep1002: Bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd. Ep1004 : Yuka Shell Epoxy Co., Ltd. bisphenol A type epoxy resin XAC4151: Asahi Ciba Co., Ltd. isocyanate modified epoxy resin XAC4152: Asahi Ciba Co., Ltd. isocyanate modified epoxy resin N740: Dainippon Ink and Chemicals Co., Ltd. phenol novolac type epoxy resin PDMU: Phenyldimethylurea DCMU: Dichlorodimethylurea Dicy: Dicyandiamide

(Measurement of temperature rising viscosity of uncured resin) A dynamic viscoelasticity measuring apparatus RDA-700 manufactured by Rheometrics was used.
An uncured resin was placed on a 25 mmφ Disk Plate, the temperature was raised to Gap 0.5 mm at a temperature rising rate of 2 ° C./min, and a share of 10 radians / sec was measured at 60 ° C. for measurement.

(Bending test (three-point bending)) CFRP was measured using a Tensilon universal testing machine manufactured by Orientec Co., Ltd.
A three-point bending test was performed in the directions of 0 ° and 90 ° with respect to the fiber axis. The size of each test piece is 0 ° bend: 120 m
m length × 10 mm width × 2 mm thickness, 90 ° bending: 60 mm length × 10 mm width × 2 mm thickness, indenter tip radius 3.2 mm,
The moving speed of the indenter was 2 mm / min and the distance between supporting points / thickness was 40 and 16, respectively.

(Glass Transition Temperature (Tg) of Cured Resin) Rheometrics Dynamic Viscoelasticity Measuring Device RDA-700
Was used to measure the storage rigidity G ′ of a cured resin test piece of 60 mm length × 12 mm width × 2 mm thickness while adding a share of 10 radians / second while heating at 5 ° C./STEP. G '
A curve of vs temperature was acquired, a tangent line was drawn to G ′ in the glass state region, a tangent line was drawn in the transition region in which G ′ was greatly changed, and the intersection of both tangent lines was taken as the glass transition temperature (Tg).

(Examples 1 to 10 and Comparative Examples 1 to 5) Epoxy resin compositions of the present invention were prepared with the compositions shown in Table 1 (numerical values are parts by weight) and coated on release paper. CF aligned in the direction (TR3 manufactured by Mitsubishi Rayon Co., Ltd.
0G-12L) to obtain a unidirectional prepreg. The viscosity of the resin composition at 60 ° C. is also shown in Table 1. The obtained prepreg had good handleability. This was laminated in one direction and vacuum bag molding was performed at 130 ° C. for 1 hour to obtain a unidirectional CFRP. A bending test and Tg measurement of the obtained CFRP were carried out, and the measurement results are also shown in Table 1. In addition, the following examples and comparative examples were prepared so that the volume fraction of CF was 60 ± 1%.

[0028]

[Table 1]

(Examples 11 to 13, Comparative Examples 6 to 8) Table 2
A unidirectional CFRP bending test and Tg measurement were performed in the same manner as in Example 1 except that an epoxy resin composition having the composition shown in 1 was prepared and HR40-12M manufactured by Mitsubishi Rayon Co., Ltd. was used as CF. The results are also shown in Table 2.

[0030]

[Table 2]

[0031]

The epoxy resin composition for a carbon fiber reinforced composite material of the present invention is the mainstream bisphenol A.
C than matrix resin for CFRP, which is mainly composed of epoxy resin and phenol novolac epoxy resin
It has excellent adhesiveness with F and does not require a troublesome step of dissolving and mixing other thermoplastic resin in order to improve tack performance. Further, the prepreg using the epoxy resin composition of the present invention as a matrix resin is very excellent in handleability,
CFRP obtained by molding it has excellent mechanical properties.

Claims (2)

[Claims] 1. A bisphenol A type epoxy resin (A), (B) an epoxy resin having a structure represented by the following formula (1) and (C) a curing agent as essential components, and a viscosity at 60 ° C. of 100 to 5000. An epoxy resin composition for a carbon fiber reinforced composite material, which is a poise. Embedded image Embedded image Embedded image 2. The ratio of the components (A) and (B) is (A) /
The epoxy resin composition for a carbon fiber reinforced composite material according to claim 1, wherein (B) = 30/70 to 90/10 (weight ratio).