JP2736442B2 - Epoxy resin composition for carbon fiber composite material - Google Patents

Description

The present invention relates to a novel epoxy resin composition for a carbon fiber composite material.

[Conventional technology]

BACKGROUND ART Since carbon fiber composite materials (hereinafter abbreviated as CFRP) have excellent mechanical performance, they are used in various fields for structural parts and the like, as well as sports and registrar goods.
Various types of matrix resins are used, but they have excellent mechanical properties, no volatile components during curing, little shrinkage during curing, and excellent adhesion to carbon fibers. For such reasons, epoxy resins have been widely used.

However, as carbon fiber composite materials have become lighter and thinner in recent years, an increase in defective products due to warpage at the end of molding of molded products such as pipes has become a major problem. On the other hand, reduction of uneven thickness of composite material, change of manufacturing conditions such as optimization of carbon fiber dispersion or reduction of matrix resin crosslinking degree, reduction of residual thermal stress generated at the interface due to addition of plasticizer, etc. Although various studies have been made, a simple and economical method for reducing the warpage while maintaining the mechanical strength of the composite material has not been realized.

[Problems to be solved by the invention]

The present inventors have conducted various studies in view of the above situation, and as a result, have developed a composite by using a resin that combines a specific epoxy compound, a curing agent, a curing accelerator, and a reaction product obtained by reacting a specific compound in a matrix. The present inventors have found that an epoxy resin composition for a composite material having high mechanical properties of a material, particularly high mechanical properties of an orthogonal laminate and less warpage of a molded product can be obtained, and completed the present invention.

[Means for solving the problem]

The gist of the present invention is the following components (A) (B) (C) (D)
An epoxy resin composition for a carbon fiber composite material containing (E) as an essential component.

(A) phenol novolak type epoxy resin (B) bisphenol A diglycidyl ether type epoxy resin (C) N, N, O-triglycidylaminophenol or a derivative thereof (D) dicyandiamide, 2,6-xylenyl biguanide At least one curing agent and curing accelerator selected from the group consisting of, 0-tolylbiguanide, diphenylguanidine, adipyl dihydrazide, azelyl dihydrazide and isophthalic dihydrazide; (Where X is hydrogen, chlorine, bromine or a hydroxyl group, R is hydrogen, Amide or amine represented by the general formula (Wherein X is the same as described above), and a reaction product obtained by reacting with an epoxy compound represented by the formula:

The phenol novolak type epoxy resin of the component (A)
Specific examples thereof include Epicoat 152 (hereinafter abbreviated as Ep152), Ep154, and Ep157, which are reaction products containing a polyfunctional epoxy compound as a main component and commercially available from Yuka Shell Epoxy Co., Ltd.

The bisphenol A diglycidyl ether type epoxy resin as the component (B) is not particularly limited in terms of epoxy equivalent weight, viscosity, etc., but may be appropriately selected in consideration of the viscosity of the resin composition, the tack when prepreg is used, and the like. Good. Specifically, Yuka Shell Epoxy Co., Ltd.'s Ep807, Ep808, Ep827, Ep828, Ep100
1, Ep1002, Ep1004, Ep1007, Ep1009 and the like. These can be used alone or in combination. The mixing ratio of the components (A) and (B) described above is preferably in the range of (A) / (B) = 80/20 to 50/50.
When the amount of the component (A) exceeds 80 parts, the low-temperature curability tends to deteriorate, and when the amount is less than 50 parts, the curability is good, but the physical properties of CFRP using this resin system are unfavorably deteriorated.

The component (C), N, N, O-triglycidylaminophenol or a derivative thereof, is a reaction product containing a compound represented by the formula (4) as a main component.

(R represents hydrogen or —CH ₃ ) Among the compounds represented by the general formula (4), The three are preferred.

The amount of the component (C) added is 5 to 100 parts by weight per 100 parts by weight of the epoxy resin of the components (A) and (B). When the compounding ratio of the component (C) is less than 5 parts by weight,
(C) improvement of low-temperature curability, which is an important addition effect of the component,
The two points of improvement of the cured resin elastic modulus became insufficient, while 100
If the amount is more than 10 parts by weight, the water resistance of the obtained CFRP is reduced, which causes a problem in practical performance.

As the curing agent in the component (D), dicyandiamide is preferable, and as the curing accelerator used in combination with the curing agent group of the component (D), a urea compound, imidazole, or an imidazole derivative represented by the general formula (5) can be given. However, mono- or dichlorophenyl-1,1-dimethylurea is preferred.

(Wherein X ₁ and X ₂ may be the same or different and may be hydrogen, chlorine, bromine, nitro, methyl, methoxy, ethoxy, or Is shown. The amounts of the curing agent and the curing accelerator are (A) and (B).
The curing agent ranges from 1 to 10 parts by weight and the curing accelerator from 1.5 to 15 parts by weight based on 100 parts by weight of the epoxy resin shown in (C). If the amount is less than the above range, the low-temperature curability is deteriorated, and if the amount is large, the stability of the prepreg at room temperature is unfavorably deteriorated.

In the present invention, the component (E) is further blended. (E)
The component is obtained by reacting an amine or amide of formula (1) with an epoxy compound of formula (2) or (3). Only by this addition, a low-warpage composite material can be realized.

The above reaction product (hereinafter referred to as "reactant") (E) is obtained by reacting the compound of the formula (1) with the compound of the formula (2) or (3) at a molar ratio of 1: 0.9 to 1.1 in a temperature range of 100 to 200C. Can be easily obtained. Although the reaction product may be used as it is, it is preferable to use the product after unreacted components are distilled off under reduced pressure (1 mmHg or less) by heating (50 to 200 ° C.) after the reaction, and then purified. The addition amount of the reactant (E) is in the range of 5 to 100% by weight based on the epoxy resin composition shown in (A) to (D). If the amount of the reactant (E) is less than 5% by weight, the effect of improving the warpage of the composite material is low, and if it exceeds 100% by weight, the mechanical properties of the composite material are undesirably reduced.

The resin composition of the present invention is useful as an intermediate for a carbon fiber composite material. The shape of the carbon fiber may be any shape such as a tape-like material, a sheet-like material, a mat-like material, a cloth-like material, and the like. Depending on the application, glass fibers, organic fibers, metal fibers and carbon fibers may be used in combination.

〔Example〕

 Hereinafter, the present invention will be described specifically with reference to examples.

 The physical properties of the composite material were measured by the following methods.

(1) Interlaminar shear strength (ILSS) Using a 15 mm long, 10 mm wide, and 2 mm thick plate-like specimen at a fulcrum (tip radius of 3.2 mm) with a span interval of 8 mm, the center of the specimen has a tip radius of 3.2 mm. Perform a three-point bending test by pressing with an indenter,
The crosshead speed was 2 mm / min. ILSS was calculated by the following equation. Note that the span interval is L (mm) and the sample thickness is T (m
m), the sample width was W (mm), and the breaking strength was P (kg).

ILSS = 3P / 4WT (kg / mm ² ) (2) Bending test (i) 0 ° bending test A span interval of 80 mm was used using a plate-like specimen with a length of 100 mm (0 ° direction), a width of 10 mm, and a thickness of 2 mm. The other tests were performed in the same manner as in the ILSS, and the bending strength and the flexural modulus were calculated by the following equations. δ indicates the amount of crosshead descent (mm) at a certain load P ′ (kg).

0 ° flexural strength ^{(FM) = 3PL / 2WT 2} (kg / mm 2) 0 ° flexural modulus (FM) = P '· L 3 · 10 -3 / 4WT 3 · δ
(T / mm ² ) (ii) 90 ° bending test A 0 ° bending test of (i) except that a plate specimen having a length of 60 mm, a width of 10 mm (0 ° direction) and a thickness of 2 mm was used, and the span interval was 32 mm. 90 ° bending strength (FS⊥), 90 °
The flexural modulus (FM⊥) was calculated.

Reference Example 1 Synthesis of N- [4- (2-hydroxy-3-phenoxypropoxy) -phenyl] -acetamide [(E) -1] When P-hydroxyacetanilide and phenylglycidyl ether were mixed at a molar ratio of 1: 1.05 and heated at 160 ° C. for 60 minutes, a viscous liquid reaction product was obtained at room temperature. This was heated to 150 ° C. at 1 mmHg to remove unreacted phenylglycidyl ether to obtain a reaction product (E) -1. The infrared absorption spectrum of the reaction product (E) -1 was measured,
It was confirmed that there was no epoxy group. The reactant (E)-
The gel permeation chromatograph was measured using the chloroform solution of No. 1 to find that the reaction product (E) -1
Was a reaction mixture containing a compound having the formula of 1: 1 as well as a reaction product with an —NH— group, and a polymer compound which had further advanced the reaction.

Reference Example 2 Synthesis of N-phenyl-N- (2-hydroxy-3-phenoxypropyl) -acetoacetamide [(E) -2] Acetoacetanilide and phenylglycidyl ether were reacted at 170 ° C. for 1 hour at a molar ratio of 1: 1.2 in the same manner as in Reference Example 1 to obtain a reaction product (E) -2. This (E) -2 was a reaction mixture containing a polymer compound that had further reacted in addition to the indicated 1: 1 compound.

Reference Example 3 Synthesis of N- (2-hydroxy-2-cyclohexeneoxideethyl) -aniline [(E) -3] Aniline and vinylcyclohexenedioxyside were reacted in the same manner as in Reference Example 1 by heating at 1: 2.1 (molar ratio) at 100 ° C. for 45 minutes to obtain a viscous liquid reactant (E) -3. This (E) -3 was a reaction mixture containing a further advanced polymer compound in addition to the 1: 1 reactant as in Reference Example 1.

Example 1 After homogenizing 60 parts by weight of Ep154 and 20 parts by weight of Ep828, 20 parts by weight of Ep1004 and 30 parts by weight of triglycidyl-m-aminophenol (ELM-120 manufactured by Sumitomo Chemical Co., Ltd.) were added. After sufficiently stirring and mixing, 30 parts by weight based on 4 parts of DICY, 5 parts of DCMU and the total mixture of the above components (A) to (D)
(E) -1 was added and mixed by stirring to obtain an epoxy resin composition for prepreg.

Next, this resin composition was heated to form a hot melt film having a thin film formed on release paper. This film was wound around a drum and heated and impregnated with carbon fibers (Pyrofilm T-1 manufactured by Mitsubishi Rayon Co., Ltd.) which were aligned in one direction to prepare a prepreg. The obtained prepreg had appropriate tackiness and hardness, and even after being stored at 25 ° C. for 1.5 months, the prepreg had little change in tackiness and hardness, and had good storage stability.

Furthermore, after laminating this prepreg in one direction and adjusting so that the carbon fiber content after molding becomes 60% by volume,
The mixture was charged in a mold and cured by heating at 130 ° C. under a pressure of 6 kg / cm ² for 1 hour to form a molded body.

 The results of measuring the obtained CFRP are shown in Table 1.

It can be seen that the composite has good physical properties.

Example 2 Using the prepreg prepared in Example 1, 12 sheets were orthogonally laminated in a configuration of (0 ゜ 90 ゜) ₆ and heated at 130 ° C. under a pressure of 6 kg / cm ^{2 for} 1 hour using a press to obtain a 1 mm thick sheet. CFRP of the board was obtained. Specimen thickness 1
A 0 ° bending test was carried out in exactly the same manner except that the length was set to 40 mm and the span length was set to 40 mm. Bending strength 168 kg / cm ^2, the flexural modulus 6.3T /
mm ² was obtained.

Comparative Example 1 In the same manner as in Examples 1 and 2 except that (E) -1 was not added, a resin composition was prepared to produce a molded product, and measurement was performed in the same manner as in Example 1. The results are shown in Table 2.

Compared with the results of Examples 1 and 2, it is clear that the CFRP using the resin composition of the present invention has high physical properties, and that the physical properties of the orthogonal laminate, which is particularly important in practical use, are extremely high.

Example 3 and Comparative Example 2 The prepregs prepared in exactly the same manner as in Example 1 and Comparative Example 1 were each adhered orthogonally, and then wrapped around a 5φ iron mandrel three times and a polypropylene tape (15 mm wide) with a tape tension of 3 kg. / 15mm, wrapping at 130 ℃, 2 in curing oven
After curing, the mixture was gradually cooled in a furnace-closed state and cooled to room temperature to form a pipe having a length of 600 mm.

The pipe using the resin composition shown in Comparative Example 1 was warped, while the pipe using the resin composition of the present invention was bent during molding and the number of defects caused by cracks was 4% or less. It occurred and showed a remarkably high value of 52% of defective products (evaluated with 50 pipes).

The bend was made by rotating the pipe while supporting it at two points with a width of 500 mm, and measuring the deflection at the center.

Example 4 (E) -2 in Example 1 instead of (E) -1
30% by weight of a resin composition containing 25% by weight of (E) -3
A CFRP plate was obtained in exactly the same manner as in Examples 1 and 2 using the two types of the added resin compositions. Table 3 shows the measurement results of the physical properties of the obtained CFRP plate.

As in Example 1 in which (E) -1 was added, it can be seen that the unidirectional CFRP physical properties and the cross-laminated CFRP physical properties have good values.

Comparative Example 3 A unidirectional carbon fiber prepreg was prepared in exactly the same manner as in Example 1 except that 30 parts by weight of ELM-120 were not used in the epoxy resin composition of Example 1. The tack and drape properties of the obtained prepreg were almost the same as those of Example 1, and the storage stability at 25 ° C was good for 1.5 months. However, the curability at 130 ℃ is poor, especially for ILSS
Was 9.5 kg / mm ^2, which was significantly lower than the others.

Comparative Example 4 A prepreg was obtained in exactly the same manner as in Example 1 except that 30 parts by weight of Ep154, 35 parts by weight of Ep828, and 35 parts by weight of Ep1004 were added. This prepreg had good tack and drape properties, and also had good curability at 130 ° C.

Therefore, a unidirectional compact was prepared using this prepreg, and a bending test was performed. FS = 188 kg / mm ² , ILSS =
It was 9.3 kg / mm ² , which was lower than when the resin of the present invention was used.

〔The invention's effect〕

The carbon fiber composite material obtained in the present invention has good storage stability at room temperature and is capable of being cured at low temperature, and has excellent mechanical properties of the composite material, and is particularly important for practical use in the orthogonal laminate,
Excellent mechanical properties such as pseudo-isotropic bodies.

It has the major feature that the warpage of molded products such as pipes and fishing rod ears is reduced, yield is improved, and productivity and economic efficiency are significantly improved.

Therefore, the present invention can be applied to a wide range of uses such as fishing rods, golf shafts, and other sports, as well as industrial fields such as automobiles, aircraft, and rockets, in addition to fields of registrars.

Claims (3)

(57) [Claims] 1. The following components (A) (B) (C) (D) (E)
An epoxy resin composition for a carbon fiber composite material, comprising: (A) phenol novolak type epoxy resin (B) bisphenol A diglycidyl ether type epoxy resin (C) N, N, O-triglycidylaminophenol or a derivative thereof (D) dicyandiamide, 2,6-xylenyl biguanide At least one curing agent and curing accelerator selected from the group consisting of, 0-tolylbiguanide, diphenylguanidine, adipyl dihydrazide, azelyl dihydrazide and isophthalic dihydrazide; (Where X is hydrogen, chlorine, bromine or a hydroxyl group, R is hydrogen, Amide or amine represented by the general formula (Wherein X is the same as described above), and a reaction product obtained by reacting with an epoxy compound represented by the formula: 2. The composition according to claim 1, wherein the component (E) is P-hydroxyacetanilide or a reaction product of acetoacetanilide with phenylglycidyl ether. 3. The composition according to claim 1, wherein the component (E) is a reaction product of aniline and 4-vinylcyclohexenedioxide.