JPS6390539A - Forming of carbon fiber-reinforced plastics - Google Patents

Abstract

PURPOSE:To obtain a void-free formed article outstanding in heat resistance and mechanical strength, capable of readily wrapping on a mandrel because of the low viscosity, by filament winding of a specific epoxy resin-carbon fiber composite. CONSTITUTION:First, a composition is prepared by incorporating (A) a blend of (i) 50-80wt% of an epoxy resin having in one molecule two or more N,N- diglycidylamino groups and (ii) 50-20wt% of an N,N-diglycidylaniline-based epoxy resin with (B) 30-45pts.wt. per 100pts.wt. of the component A of diaminodiphenyl sulfone and/or diaminodiphenylmethane. This composition is then heated to 70-90 deg.C, being impregnated in carbon fiber followed by filament winding of the resultant composite on a mandrel with the ambient temperature kept at 80-120 deg.C, thus obtaining the objective formed article. Said composition may be further incorporated with 25pts.wt. per 100pts.wt. of the blend A, of a third epoxy resin.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for molding carbon fiber reinforced plastics used in fields where heat resistance is particularly required. The present invention relates to a method for producing a heat-resistant molded article by filament wind molding using an epoxy resin composition.

[Prior art and problems]

Regarding the filament winding method, which is one of the molding methods for carbon fiber reinforced plastics, in recent years there has been a demand for high heat resistance for the molded products. When used in the filament winding method, due to its generally high viscosity, it is difficult to continuously impregnate the fiber with resin and wind it around a mandrel, making it unsuitable for filament winding. There is. In order to solve this problem, methods have been proposed to lower the viscosity of the resin using reactive diluents, etc., but this generally does not avoid the tendency of sacrificing heat resistance.

[Purpose of the invention]

The purpose of the present invention is to use a resin composition that has a moderately low viscosity that allows filament wind molding while avoiding a decrease in heat resistance, so that the molded product has no voids and has excellent heat resistance and mechanical strength. The object of the present invention is to obtain a molded article using a filament winding method.

[Structure of the invention]

The present invention is as follows.

An epoxy resin composition containing the following components [A] to [C] in the following amounts is heated to 70 to 90°C, and this is heated to 70 to 90°C.
After impregnating with
A method for molding fiber-reinforced plastics with 1 gram of charcoal, which is characterized by being kept at 120°C and rolled.

[A] 50 to 80% by weight of an epoxy resin having two or more N,N-diglycidylamino groups in one molecule ([A] and C
(B) N,N-diglycidylaniline (epoxy resin)
50 to 20% by weight (same as above) (C) Epoxy resin mixture 10 of the above [A] and [B]
0 parts by weight, 30 to 45 parts by weight of diaminodiphenylsulfone or diaminodiphenylmethane The epoxy resin having two or more N,N-diglycidylamino groups in one molecule of component (A) in the present invention includes, for example, N, N, N-.

N'-tetraglycidyl metaxylene diamine, or N, N, N'', N',-tetraglycidyldiaminodiphenylmethane, or N.

N, N-, N=-tetraglycidyl-3,5-dimethyl-4-aminophenylparadiisopropylbenzene,
Alternatively, there is N , N , N', N''-tetraglycidyl-4-aminophenylvaradiisoprobylbenzene.

In the present invention, it is necessary to contain N,N-diglycidylaniline as component CB) as an epoxy resin in addition to component (A). Furthermore, if desired, (△), (B)
It is also possible to blend a small amount of other epoxy resins as component CD). As the epoxy resin of component (D),
Bisphenol A type epoxy resin, phenol novolak type epoxy resin, etc. are preferred.

In the present invention, component (C) diaminodiphenyl sulfate or diaminodiphenylmethane is blended as a curing agent for these epoxy resins.

The relationship between the amounts of ingredients will be described.

Component [△] 50-80%, component to be mixed (B
) is 50 to 20% by weight. Component (B) is 201
If the viscosity is less than ffi%, an appropriately low viscosity that enables filament wind molding cannot be obtained, and if it exceeds 500 sph, the heat resistance decreases, which is disadvantageous.

The amount of component (C) is 30 to 45 parts by weight per 100 parts by weight of the mixture of [A] and [B]. Component (C) is 30
ff! If it is less than 45 parts ffi, curing will be insufficient and the desired heat resistance cannot be imparted to the molded product, and if it exceeds 45 parts ffi, not only will no effect commensurate with the increased amount be obtained, but it will even have a negative effect on the physical properties of the molded product. . Furthermore, if necessary, there is no problem in using a curing accelerator.

■ of component (D) to be blended as desired is (A) and ([3
) is less than 21 parts per 100 parts of the mixture. If the amount of component (D) exceeds 25 parts by weight, this is disadvantageous as it leads to a decrease in heat resistance.

In the present invention, when impregnating carbon fibers with the resin composition, it is necessary to maintain the 'fA degree of the resin at 70 to 90°C. If it is less than 70°C, the viscosity necessary for resin impregnation cannot be obtained, and if it exceeds 90°C, the pot life will be shortened, which is disadvantageous. Furthermore, when winding the carbon fiber bundle impregnated with this (1) fat crude product around a mandrel, it is necessary to maintain the ambient temperature around the mandrel at 80 to 120°C to obtain a good molded product. At this time, if the ambient temperature around the mandrel is less than 80°C, the resulting molded product will have many voids, and if it exceeds 120°C, the resin will flow down, making it impossible to control the amount of resin in the molded product. There will be more voids, and the resin may harden during winding.

(Effects of the Invention) According to the method of the present invention, there are fewer voids in the molded product after molding, and as a result, a molded product with excellent mechanical properties and heat resistance can be obtained.

[Examples and comparative examples]

Example 1 N, N, N=, N=-tetraglycidyldiaminodiphenylmethane [trade name f MY-720J
70 parts by weight of N, N-diglycidylaniline (manufactured by Ciba Geigy Co., Ltd.) [trade name: rGANJ Nippon Kayaku Co., Ltd.]
J) 30 parts by weight and 34.5 parts by weight of diaminodiphenylsulfone
ffi ffi part was added, BF as a curing accelerator, and monoethylamine [trade name "△NCl-1ORIO40J"
A, C, f (manufactured by Japan Limited) 0.5 parts (m) of epoxy resin composition were blended and thoroughly stirred (2 q) of the epoxy resin composition.

While heating this to 80°C, the temperature around the mandrel was raised to 100°C using the filament winding method while impregnating it with carbon fiber (trade name: "Besufuite I- (TA-6000J manufactured by Toho Rayon Co., Ltd.)"). This was then wound around a mandrel at an angle of ±45° to form a tubular body.
It was heated and cured at 0°C for 1 hour and then at 180°C for 4rRMJ.

The molded product thus obtained had a carbon fiber content of 55% by volume and a void ratio of 0.3% by volume determined by the sulfuric acid decomposition method.

Example 2 70 parts by weight of N,N,N',N'-tetraglycidyldiaminodiphenylmethane [trade name MY-720J, manufactured by Diba Geigy Co., Ltd.] was mixed with N,N-diglycidylaniline ([Ippon Kayaku Co., Ltd.)]. )?fJ) Add 30 parts and 1 part of 34.5 mff of diaminodiphenylsulfone, stir and mix thoroughly, and add BF>Monoethylamine (trade name: rANC) (OR1040J A) as a curing accelerator.
, manufactured by C,I Japan Limited] was blended to obtain an epoxy resin composition. 80% of this resin composition
The viscosity at °C was about 10 poise, and the pot life at the same temperature was sufficiently long. The resin composition thus obtained was heated to 80°C, impregnated with carbon fiber [trade name: Besphite 3-3-60004 manufactured by Toho Rayon Co., Ltd.], and wound in parallel onto a flat plate using the filament winding method. Wearing.

This was inserted into a hydraulic press, pressurized to 1 kg/cm', and cured at 130°C for 1 hour and then at 180°C for 2 hours to obtain a molded plate with a thickness of 3Il1m.

The molded plate thus prepared had a carbon fiber content of 66% by volume, and an interlayer PJ measured according to ΔSTM-D-2844 and [)-790. J breaking strength (
ILSS) and bending strength were as shown in Table 1.

Table 1 As is clear from Table 1, the molded plate has bending strength and r
The LSS is extremely high, and the retention rate at temperatures as high as 135°C is over 76% ((153/202) x 100%,
Bending strength], 60% ((8,7/ 14.5) X10
0%, ILSS), indicating that it has excellent heat resistance.

Example 3 N,N-diglycidylaniline (Nippon Kayaku Co., Ltd.) was added to 60 parts by weight of N,N,N',N'-tetraglycidyldiaminodiphenylmethane (trade name: MY-720J, manufactured by Ciba Geigy Co., Ltd.). N) 20 fl [parts] and bisphenol △ type epoxy resin (product name "Epicote 82")
8" manufactured by Shell Kagaku Co., Ltd.] was added, 34.5 parts by weight of diaminodiphenylsulfone was added as a hardening agent, and B F s monoethylamine [trade name: rANcI→OR1040] was added as a curing accelerator. No A, C, I
Made by Japan Limited) 0.51f! 1 part was blended to obtain an epoxy resin composition.

While heating this to 80℃, 1 carbon! Using the filament winding method while impregnated with fiber [trade name: "Besphite HT A-6000J manufactured by Toho Rayon Co., Ltd.], the temperature around the mandrel was set to 100°C, and the tube was wound around the mandrel at an angle of ±45° to form a tubular body. This was heated and cured at 130°C for 1 hour and then at 180°C for 4 hours.

The thus obtained molded product had a carbon 11M content of 57% by volume, and a void ratio of 1:7 by the sulfuric acid decomposition method of 0.2% by volume.

In addition, in order to evaluate the performance of this resin composition, Example 2
Wait for the molded plate in the same manner as above. The carbon fiber content of this molded plate was 66 volumes, and AsTM-D-284
4 and []-790, and the ILSS and bending strength were as shown in Table 2.

Table 2 As is clear from Table 2, both ILSS and bending strength are extremely high (and the retention rate at temperatures as high as 135°C is approximately 60% ((7,9/13.6) x 100%, ILS
S), approximately 80% ((164/211) x 100%
, bending strength], and it can be seen that the molded product and the resin composition have excellent heat resistance.

Comparative Example 1 (component (B) not used) 40 parts by weight of diaminodiphenylsulfone was added to 100 parts by weight of N,N,N',N'-tetraglycidyldiaminodiphenylmethane (trade name: MY-720J, manufactured by Ciba Geigy Co., Ltd.). Add BF! as a hardening accelerator to this and mix thoroughly. Monoethylamine [Product name rAN
cHOR1o4oJ A, manufactured by C6I Javan Limited] 0.5 layer part was blended to obtain a resin composition. The viscosity of this resin composition is higher than the viscosity of the epoxy resin composition shown in Example 1, and with such a low viscosity, the impregnation of the resin into the fibers is poor and the pot life is short. It is difficult to apply the resin composition to the filament winding method.

Comparative Example 2 (component CB not used) N, N, N', N-tetraglycidyldiaminodiphenylmethane (trade name r MY-7204 manufactured by Ciba Geigy Co., Ltd.) 7Offiffi part and low viscosity bisphenol A diglycidyl ether type epoxy Resin [Product name: "Epicote 815" manufactured by Yuka Shell Epoxy Co., Ltd.] 3
34.5 parts by weight of diaminodiphenylsulfone was added to 1 part by weight of 0 weight, and 0.5 parts by weight of BF1 monoethylamine (trade name "ANCHOR1040J manufactured by A, C, I Japan Limited) was blended as a curing accelerator to obtain a matrix resin. Ta.

While heating this resin to 80°C and impregnating it into the same carbon fiber as in Example 1, by the filament winding method,
A molded article was obtained in the same manner as in the example. This molded product has a carbon fiber content of 56 vol.
-2844: The I LSS value measured at 25°C was 9. +3k (Jf/1m', 4 at 135℃,
It was 0k(if/mm').

Comparative Example 3 (heating temperature of the resin composition is outside the range of the present invention) *The same resin as in Zetsutou 1 was heated to 60°C, and while impregnated with 11M carbon, which was the same as in Example 1, a mandrel was formed by the filament winding method. The surrounding mold was heated to 80° C. and cured by winding it around a mandrel.

The molded product obtained by this method has a carbon fiber content of 53% by volume, and a void ratio of 2.3% compared to 17% by the sulfuric acid decomposition method.
Volume ffi % T-Ali, and AsTM-D-2844
The ILSS value measured according to the measurement temperature was 8.9 at 25℃.
kof/mm'. The heating temperature of the resin composition is 1
When I tried to mold the resin composition using the filament winding method in the same manner as above except that the temperature was 00°C, the viscosity of the resin composition began to increase after 2 hours, impregnating the fibers deteriorated, and filament wind molding became difficult. Ta.

Comparative Example 4 (Ambient temperature around the mandrel is outside the range of the present invention) Using the same resin composition as in Example 1, this resin composition was
While impregnating the fibers while heating them to 0°C, the ambient temperature around the mandrel was raised to 7°C using the filament winding method.
The molded product is heated to 0°C, wound around a mandrel and cured.
is.

The thus obtained molded product had a carbon lI fiber content of 53% by volume, a void ratio of 1.0% by volume obtained by the sulfuric acid decomposition method, and an II fiber content measured according to ASTM-D-2844. LSS value is 11.4kgf at measurement temperature 25℃
/IRI2.

A molded product was made in the same manner as above except that the ambient temperature around the mandrel was changed to 130°C.
II fiber content is 70% by volume, and I
The fP void rate was 2.2% by volume.

From the results of the above Examples and Comparative Examples, it is clear that the resin composition used in the present invention has a low viscosity suitable for filament winding molding, and has excellent heat resistance.
When using this resin composition, the necessary condition for applying the filament winding method is that the heating temperature of the resin composition during impregnation is 7.
0 to 90℃, and the atmospheric temperature around the mandrel is 8℃.
It is clear that the temperature is between 0 and 120°C.

Claims (2)

[Claims] (1) After heating an epoxy resin composition containing the following components [A] to [C] in the following amounts to 70 to 90°C and impregnating it into carbon fibers, the ambient temperature around the mandrel was lowered to 80°C.
A method for molding carbon fiber reinforced plastics, which comprises winding the plastics while maintaining the temperature at ~120°C. [A] 50 to 80% by weight of an epoxy resin having two or more N,N-diglycidylamino groups in one molecule ([A] and [
[B] N,N-diglycidylaniline (epoxy resin)
50 to 20% by weight (same as above) [C] Epoxy resin mixture 10 of the above [A] and [B]
30 to 45 parts by weight of diaminodiphenylsulfone or diaminodiphenylmethane per 0 parts by weight (2) The epoxy resin mixture is further added as component [D]
The molding method according to claim (1), which contains epoxy resins other than A] and [B] in an amount of 25 parts by weight or less per 100 parts by weight of the mixture of [A] and [B].