JPS5817535B2 - Epoxy resin composition for carbon fiber reinforcement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin composition for reinforcing carbon fibers that is curable at low temperatures, has excellent storage stability, and is flame retardant.

The cylindrical carbon fiber reinforced plastic (hereinafter referred to as CFRP), which is widely used in premium sports products such as golf club shafts and fishing rods, has recently been replaced by filament winding molding method from the viewpoint of improving productivity and working environment. Instead, molding using a dry lamination method using prepreg has been adopted.

The matrix resin for CFRP is an epoxy resin with excellent adhesion to carbon fibers, such as a bisphenol A diglycidyl ether type epoxy resin, ``Epicort 828'' (manufactured by Shell Chemical Co., Ltd.), which is prepolymerized with DDS (``Epicort''). Commercially available products such as DX210) are known, and boron trifluoride monoethylamine (BF3-MEA) is known as a curing agent for this epoxy resin.
) are widely used.

However, although this resin composition has good storage stability, it has a high curing temperature and usually must be cured at a temperature of 150°C or higher, and unlike carbon fiber, it hardly expands when heated, or in some cases it expands slightly. Shrinking fibers have a large residual stress during molding, and slight disturbances in the fiber arrangement can easily cause defects such as curvature and cracks in the molded product (causing problems during molding and reducing yield). There was a problem.

Moreover, when BF3-ME A is used as a curing agent, the elongation of the cured epoxy resin becomes small, resulting in low interlaminar shear strength (hereinafter abbreviated as ILSS) of CFRP, insufficient impact resistance, and the tip of a fishing rod. It is said that those that must be molded into small diameters are difficult to mold in terms of strength.

Dicyandiamide is known as a substance that lowers the curing temperature of the epoxy resin, but dicyandiamide alone has no problem with storage stability, but like BF3-MEA, the curing temperature is high, so dicyandiamide and an appropriate curing accelerator are used in combination. Attempts have been made to lower the curing temperature by

However, when dicyanamide and a curing accelerator are used in combination, the heat resistance of the cured product obtained from the epoxy resin is significantly reduced, and in the case of the above-mentioned "Epicor" DX-210, the heat resistance is said to not even reach 80°C.

The purpose of the present invention is to provide an epoxy resin composition for CFRP which does not have the above-mentioned drawbacks, has low temperature curability, excellent storage stability, and excellent heat resistance, and another purpose is to provide an epoxy resin composition for CFRP that has excellent moldability. The object of the present invention is to provide a CFRP that reflects the excellent reinforcing fiber properties of carbon fiber.

The object of the present invention is to use at least two types of epoxy resins, a phenol novolak type resin and a bisphenol A diglycidyl needle type resin, as an epoxy resin, and to add triglycidyl to this epoxy resin. This can be achieved by blending -m--aminophenol and dicyandiamide with a curing accelerator.

In the present invention, the phenol novolac type epoxy resin as component A is a reaction product whose main component is a polyfunctional epoxy compound represented by the formula (1). ” 152 (hereinafter abbreviated as Ep-152), “Epitsu 1-” 154
(hereinafter abbreviated as EP-154).

In addition, the bisphenol A diglycidyl ether type epoxy resin of the component (B) used together with the epoxy resin of the component N in both images is a reaction product whose main component is an epoxy compound represented by the formula (2). E made by Shell Chemical ■
p-sos, EP-827, ]Ep-828, Ep-1
001, Ep-1002, Ep-1004, EP-10
07, Ep-1-009, etc., and these can be used alone or in combination.

Component (C) N-N-0-)liglycidyl-m-aminephenol is a reaction product containing the compound represented by formula (3) as a main component.

Furthermore, examples of the curing accelerator used in combination with the old component dicyandiamide include mono- or dichlorophenyl-1-dimethylurea, imidazole, imidazole derivatives, etc., but mono- or dichlorophenyl-1-dimethylurea is preferred.

Constituting the epoxy resin composition of the present invention (A, (B),
(The mixing ratio of the acid components q and [F] is 25 to 100 parts by weight of the component (B) per 100 parts by weight of the component (A), 6 to 40 parts by weight, and preferably 3 to 9 parts by weight of dicyandiamide and 4 to 8 parts by weight of a curing accelerator per 100 parts by weight of components (Y33, (B) and (q). .

That is, if the blending ratio of component (B) is less than 25 parts by weight, which is outside the above range, the elongation of the cured resin will not be improved, and if it exceeds 100 parts by weight, the heat resistance will deteriorate significantly, which is not preferable.

Furthermore, the adhesiveness and flexibility of the prepreg can be controlled by adjusting the molecular weight of component (B).

(If the blending ratio of component q is less than 6 parts by weight per 100 parts by weight of both components (A) and (B), the improvement in low temperature curability will be insufficient; on the other hand, if it exceeds 40 parts by weight, the resulting CFR
This is not preferable because the water resistance of P decreases, which poses a problem in terms of practical performance in applications such as fishing rods.

Furthermore, if the dicyandiamide and curing accelerator in component (D) are blended at a ratio of 3 or 4 parts by weight or less per 100 parts by weight of the three components A, (B), and (C), the low temperature curing property will be lost and the temperature will rise to 150°C. It will not harden at temperatures below.

Moreover, if the content exceeds 9 and 8 parts, respectively, the shelf life of the prepreg will be shortened, and the moldability will deteriorate.

The resin composition of the present invention has the resin properties necessary as a resin composition for CF'RP by combining the above-mentioned four components, (B), (q, and (D). Although the action and effect cannot be explained individually, (A) component (D
CFRP containing just the ingredients can be cured at 130 to 150°C, and the physical properties of CFRP are quite good.

However, in this case, the elongation of the cured resin product is small and it becomes brittle, and when it is made into a prepreg, the adhesiveness is too thick.

In addition, in order to improve the elongation and flexibility of the cured resin,
If a polyamide or a reactive nidistomer, which is commonly used, is blended, the heat resistance of the cured product will inevitably decrease, and the tackiness will even increase, which is not preferable.

In contrast, in the present invention, by blending component (B), flexibility and adhesiveness can be simultaneously improved without substantially impairing the heat resistance of the cured product.

In particular, to improve the flexibility and adhesiveness of prepreg,
808, Ep-827, Ep-828 (all of which are liquid) and solid Ep-1001, EP-100.
2, EP-1004, EP-1,007, EP-100
It is better to use it in combination with 9.

On the other hand, in order to lower the curing temperature of component (A), which inherently has a high curing temperature, it is necessary to mix component (q), and (C
) By blending the components, it is possible to lower the curing temperature and to significantly improve the physical properties of the composite, especially the ILSS.

Furthermore, component (I) functions as a curing agent for the resin composition of the present invention, but it is difficult to sufficiently lower the curing temperature with dicyandiamide alone, and the curing temperature can be lowered by using the urea-based compound as a curing accelerator. It is possible to reduce the heat resistance and suppress a decrease in heat resistance.

Thus, the epoxy resin composition of the present invention has (1) 12
It hardens at temperatures below 0°C, and hardens at 20°C (both 1.5
It has a storage stability of more than several months.

Therefore, it is easy to mold a prepreg or the like, especially by a dry lamination method, and the yield and productivity can be improved.

(2) Although it can be cured at low temperatures, it retains excellent adhesion to carbon fibers, and the CFRP using the resin composition of the present invention as a matrix has excellent composite properties, especially heat resistance at at least 100°C. LIS
It has a large S and has excellent impact resistance.

(3) When used in prepreg, a prepreg with low resin tackiness, flexibility, moldability, and ease of handling can be obtained.

This feature makes it extremely useful as a resin composition for CFRP.

Moreover, the addition of triglycidyl-m-amine phenol significantly improved the physical properties of the composite, especially the ILSS.

The amount of C added is 6 to 40 parts by weight per 100 parts by weight of (A+B).
A range of parts by weight is desirable.

If the amount of C added is less than 6 parts by weight, no effect on improving hardenability will be observed, and if the amount added is more than 40 parts by weight, the water resistance of CFRP will decrease, causing a practical problem in fishing rods, etc. Therefore, the amount of C added is ( The preferred range is 6 to 40 parts by weight per 100 parts by weight of A and B).

Also, dicyandiamide as a hardening agent is (A0B10)
3 to 9 parts by weight per 10 parts by weight, 4 to 9 parts by weight of curing accelerator
The range of 8 parts by weight is desirable, and the curing accelerator is mono(
Alternatively, di)chlorophenylto-1-dimethylurea is also suitable.

In carrying out the present invention, other epoxy resins, anhydrous silica, thermoplastic polymers, etc. may be added as long as the purpose of the present invention is not impaired.

Furthermore, in the present invention, reinforcing fibers other than carbon fibers such as glass fibers and organic fibers may be included in addition to carbon fibers.

Further, the carbon fiber used in the present invention may be any carbon fiber such as rayon-based, polyacrylonitrile-based, pitch-based, etc.

Hereinafter, the content of the present invention will be explained in more detail with reference to Examples.

Example 1 61 parts of EP-154 manufactured by Shell Chemical ■, EP-828/
39 parts of EP-1009 (1:1 mixture), triglycidyl-m-aminephenol ELM- manufactured by Sumitomo Chemical
11 parts of 120 were added to the heated Sogou, stirred and mixed thoroughly, and then 7 parts of dicyandiamide and dichlorophenyl-1.1 were added.
- 5 parts of dimethylurea was added and thoroughly stirred and mixed to obtain an epoxy resin composition for prepreg.

Next, the carbon fiber "Train Card" T-300 made by firing and surface-treating the acrylic resin IJ fiber was aligned in one direction, and then heated and melted and impregnated with the resin composition to form a unidirectional prepreg. I got it.

The obtained prepreg had appropriate adhesiveness and flexibility.

Further, after being stored at 20°C for 1.5 months, there was little change in the adhesiveness or flexibility of the prepreg, and it had good storage stability.

Example 2 The prepreg obtained in Example 1 was made into a length of 30 and a width of 20 CI.
The pieces cut into rL were laminated so that the fiber directions were in the same direction, wrapped with Tetron tack, and then inserted between two Tetron films and placed in a press heated to 120°C and heated to 7 kg/ca. It was pressed and cured for 60 minutes.

Then, it was placed in an oven at 130°C for 2 hours of after-curing to completely cure the CFR to a thickness of 2 mm.
A P plate was obtained.

Next, the bending strength and ILSS of the obtained CFRP board were measured according to ASTM D-2344 and ASTM D-7.
Measured according to 90.

As shown in Table 1, the obtained composite had excellent physical properties and good heat resistance.

Example 3 The prepreg obtained in Example 1 was laminated on a tapered mandrel (diameter: 8 mm at one end and 3 mm at the other end) with a length of 1 m20 CrrL with a configuration of 0°/±30°, and then a release agent was applied. The resulting Tetron film was wound, placed in an oven at 120°C, cured for 60 minutes, pulled out from the mandrel, and placed in an oven at 130°C for after-curing for 2 hours to obtain a cylindrical hollow pipe.

None of the obtained products had defects such as bends or cracks, and all had good appearance and strength.

Comparative Example 1 In place of the epoxy resin in Example 1, 6% of EP-154 was used.
1 copy, 19.5 copies of EP-828, 1 copy of EP-1009
After putting 9.5 parts into a heating kneader and thoroughly stirring and mixing, add 6.3 parts of dicyandiamide and 1.1 parts of dichlorophenyl.
- A unidirectional carbon fiber prepreg was produced under the same conditions as in Example 1, except that 4.5 parts of dimethyl urea was used.

The adhesiveness and flexibility of the obtained prepreg were almost the same as those of Example 1, and the storage stability at 20° C. was good for 1.5 months.

However, when the curing behavior was investigated by DSC, the exothermic peak temperature of the prepreg of Example 1 was 145°C and the exothermic start temperature was 114°C, whereas the exothermic peak temperature of the prepreg of Comparative Example 1 was 153°C, The exothermic start temperature was 125° C., which was higher than that of Example 10 Preprege.

Therefore, by changing the temperature in 10°C increments within the range of 120°C to 150°C and curing for 60 minutes, we determined the temperature at which it would harden in 60 minutes, and found that a curing temperature of 140°C was required.

Furthermore, in order to completely cure it, it was found that it was necessary to carry out after-curing at 150°C for 2 hours.Therefore, a unidirectionally reinforced plate with a thickness of 2 mm was made in the same manner as in Example 2, and the results of measuring the physical properties are shown below. Shown in 2.

In addition to being slightly lower in strength than Example 2, the ILSS was also particularly low.

Comparative Example 2 An epoxy resin composition was obtained by adding 100 parts of EP-154 manufactured by Shell Chemical ■, 6.3 parts of dicyandiamide, and 45 parts of dichlorophenyl-1,1-dimethylurea to a heated niegu and stirring and mixing thoroughly. A unidirectional carbon fiber prepreg was obtained in the same manner as in Example 1.

The curing properties of the obtained prepreg were investigated and found to be 140°C.
After curing for 60 minutes, it was found that after-curing for 2 hours at 1-50°C was required, so a unidirectional reinforced plate with a thickness of 2 mrn was made using the same curing conditions as in Example 2 except for the curing conditions above. was created.

The physical properties of the obtained CFRP board are shown in Table 3, and the composite physical properties, especially ILSS, were extremely low.

The T2 of the obtained CFRP board measured by DSC is 170°C.
It showed good heat resistance.

Therefore, EP-1,54 was reduced to 70 parts, and 30 parts of Thiokol LP-3 manufactured by Toshi Thiokol ■ was added instead, and 6.3 parts of dicyandiamide and 4.5 parts of dichlorophenyl-1,1-dimethylurea were added. After stirring and mixing thoroughly,
After curing at 40°C for 1 hour, the product was after-cured at 150°C for 2 hours to obtain a completely cured product.

The T3 of the obtained cured product was 1.05°C, and the heat resistance was significantly lowered.

Comparative Example 3 100 parts of Shell Chemical Co., Ltd. Epicor) DX210 and BF
Three parts of 3.MEA were dissolved in methyl ethyl ketone to obtain a resin solution with a resin concentration of 40% by weight.

Next, the "Trading Card" T-300 was aligned in one direction, impregnated with the resin solution, and then heated and dried at 120° C. for 3 minutes to obtain a unidirectional prepreg.

The obtained prepreg had little tackiness and felt a little hard, but had good storage stability at room temperature for more than 2 months.

Therefore, using the same method as in Example 2, only the curing temperature was 170°C.
Table 4 shows the results of measuring the physical properties of a CFRP board produced by changing the temperature to x1 hour + 190°C x 2 hours.

Compared to Example 1, the strength ILSS was also significantly lower.

In addition, in the same manner as in Example 3, the curing temperature was set to 170°C.
When a cylindrical hollow pipe was manufactured by changing the after-cure temperature to 180°C, 23% of the bending occurred.

Claims (1)

[Scope of Claims] 1. A carbon fiber reinforced resin composition comprising the following (A), (B), (C) and the following as essential components. (A) Phenol novolac type epoxy resin (B)
Bisphenol A diglycidyl ether type epoxy resin (C) N-N-0-triglycidyl-m-aminophenol dicyandiamide and curing accelerator.