JPH01201321A - Matrix resin composition - Google Patents

Abstract

PURPOSE:To obtain the title matrix resin composition well balanced between heat resistance and elongation and improved in resin flow-out resistance during molding by curing as a carbon fiber reinforced plastic, by constituting it from three specified types of epoxy resins and dicyandiamide. CONSTITUTION:A matrix resin composition is formed by mixing 10-70pts.wt., desirably, 20-50pts.wt. cresol novolac epoxy resin (A) (e.g., ECN-1273, a product of Japan Ciba-Geigy) is mixed with 10-70pts.wt., desirably, 20-50pts.wt. bisphenol epoxy resin (B) (e.g., Araldite 6071, a product of Japan Ciba-Geigy) and 3-40pts.wt., desirably, 5-20pts.wt. phenoxy resin or its epoxy-modified resin (C) (e.g., PKHM-30, a product of UCC), 1-10pts.wt., based on 100pts.wt. in total of A, B and C, dicyandiamide (D) and 1-10pts.wt. cure accelerator (E) (e.g., 3-(3,4-dichlorophenyl)-1,1-N-dimethylurea.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a matrix resin composition, more specifically, a matrix resin composition that has a good balance between heat resistance and elongation, and has excellent resin flow resistance during molding and curing. The present invention relates to a resin composition for carbon fiber-reinforced plastics that can provide composite physical properties.

[Conventional technology]

Because carbon fiber is lightweight, has high strength, and high modulus of elasticity, it is used as a composite material with resin in the form of so-called prepreg, for example, for sports leisure goods such as fishing rods, golf clubs and badminton shafts, temporary springs, etc. At present, it is widely used in the field of molding materials, including industrial materials such as honeycomb structural materials, as well as materials for automobiles, aircraft, and medical materials.

However, conventionally, such carbon fiber reinforced plastics (hereinafter referred to as C
It is abbreviated as FRP. ) Many patents have been filed for resin compositions used in As for the main composition, for example, Japanese Patent Publication No. 60-58420 or Japanese Patent Publication No. 58
As seen in Publication No. 167625, 50% or more of phenol novolac type epoxy resin or bisphenol A type epoxy resin is mixed and used in a mixture of novolac type epoxy resins such as phenol novolac type and cresol novolac type epoxy resin. something is known. However, when such CFRP is molded into various products, it is subjected to cutting processing, and in order to withstand the temperature rise at that time, it is usually heated at a glass temperature of about 150°C (n>A degrees (Tg)).
Is required. Therefore, resin compositions containing a large amount of novolac-type epoxy resin with good heat resistance have been conventionally used. However, if the proportion of novolac-type epoxy resin is too high, the molded product tends to become brittle.

In addition, when molded products are made from resin compositions with a high proportion of novolac type epoxy resin, there is no problem if the carbon fibers are aligned in the same direction, but when used as CFRP, C
In order to reduce the anisotropy exhibited by FRP, it is common for the fibers to be aligned in an angle of 0°/±45° or 10°. Stress is generated due to the difference in thermal contraction caused by the fibers, which causes peeling between layers where fibers intersect, and in severe cases, cracks and cracks occur.This is because resin compositions with a high proportion of novolac type epoxy resin This is thought to be because the elongation of the resin composition is lower than that of resin compositions containing a small proportion of novolac-type epoxy resin.

In addition, in order to fully bring out the high strength and high p property of carbon fiber, the matrix resin needs to have a certain degree of elongation.

In order to improve the elongation of these resins, resin compositions containing, for example, rubbery polymers have been proposed. The glass transition temperature decreases, and as described above, the problem of insufficient heat resistance during secondary processing after molding remains.

In addition, a resin obtained by mixing one or more of bisphenol A (BPA) type, phenol novolak (PN) type, and cresol novolac (CN) type epoxy resin in an appropriate ratio is gradually cured with dicyandiamide and a curing accelerator. When curing by applying heat, the disadvantage is that the minimum viscosity becomes too low. When making a pipe molded product using a prepreg in which carbon fiber is impregnated with a resin whose minimum viscosity is too low, a large amount of resin freezes out during heat curing.

If the amount of resin flowing out is large, the weight of the pipe molded product will vary (D), the distribution of carbon fiber and resin will be uneven (D)
For this reason, in severe cases, warpage occurs in the pipe molded product.

[Problem to be solved by the invention]

As described above, the conditions for the matrix resin of CFRP were that it should have high elongation, heat resistance, and the amount of resin flowing out of the molded product should be small.

However, when a rubber component is added for the purpose of increasing the elongation of the matrix resin to prevent embrittlement of CFRP molded products, the heat resistance temperature decreases. On the other hand, if you improve heat resistance,
This causes embrittlement of the matrix resin. Also, BPA type,
Simply mixing and using PN-type and CN-type epoxy resins lowers the minimum viscosity and increases the amount of resin that flows out, causing the aforementioned problems.1 The present invention improves the matrix resin composition and reduces heat resistance. It is an object of the present invention to provide a matrix resin composition that has high elongation and a high minimum viscosity during heat curing without causing any viscosity.

(Means for Solving the Problem) The present inventors have completed the present invention as a result of intensive studies to achieve the above object, and the gist thereof is as follows: C, D and E components are essential components,
The matrix resin composition contains 1 to 10 parts by weight of component D and 1 to 10 parts by weight of component E, based on 100 parts by weight of the total amount of components A, B, and C.

However, A, 10 to 70 parts by weight of a cresol novolac type epoxy resin B, 10 to 70 parts by weight of a bisphenol A type epoxy resin C, 3 to 40 parts by weight of either a phenoxy resin or its epoxy modified resin, or a mixture of both D. Dicyandi-7mide E, which is a curing accelerator, will be described in detail below.

First, as the cresol novolak type epoxy resin used as component A in the present invention, for example, ECN-1273 manufactured by Ciba Geigy Japan, which is known as a commercial product,
ECN-1280, or ESCN manufactured by Sumiya Chemical Industry ■
-220 series, or products equivalent to these can be appropriately selected and used. All of these epoxy resins have a small Evoquine equivalent and a high crosslinking density, so the resulting cured molded product has excellent elastic modulus and heat resistance, but if used in excess, the molded product It reduces the elongation and causes embrittlement.

Therefore, in consideration of such characteristics, the blending amount in the composition is 10 to 7 of the &8 amount of component A, component B, and component C.
It is added in an amount of 0 parts by weight, preferably 20 to 50 parts by weight. If the amount of resin as component A is less than 10 parts by weight, sufficient elastic modulus or heat resistance cannot be imparted to the cured CFRP body, while if it is more than 70 parts by weight, the respective CFR
The elongation of the P cured product decreases and the material becomes brittle.

In addition, the bisphenol A type epoxy resin used as component B is specifically Epicote 828 and Epicote 8.
34, Epicote 1001, Epicote 1004 (manufactured by Yuka Shell Epoxy ■), Araldite CY2O5, C
Y230, GY250, GY260, Araldite 60
71 (manufactured by Nippon Chiha Geigy Co., Ltd.), etc., and equivalent products thereof can be appropriately selected and used.

These bisphenol A type epoxy resins, which are component B, come in various grades from solid to liquid due to the difference in molecular weight. When blended into matrix resin for prepreg, the viscosity is adjusted by appropriately mixing these. Furthermore, the elongation of the molded product after curing is higher than that of the novolak type epoxy, which is component A. However, the heat resistance is poor. Therefore, component B is added in an amount of 10 to 70 parts by weight, preferably 20 to 50 parts by weight, out of the total amount of components A, B, and C. If the weight of component B is less than 10 parts by weight, sufficient elongation cannot be obtained, and if it is more than 70 parts by weight, sufficient heat resistance cannot be imparted.

Next, the phenoxy resin which is component C used in the present invention is a linear polymer, has good compatibility with epoxy resins, is highly polar, and contains functional groups such as hydroxyl groups in the molecule. Furthermore, due to its high molecular weight, the temperature dependence of the viscosity is low, and by adding it to the above-mentioned A+B component, the minimum viscosity can be increased, making it a good property as a prepreg matrix. give.

The molded product obtained by mixing these three components A, B, and C and curing with components D and E does not have a complete three-dimensional network structure, but a structure in which crosslinked polymers and linear polymers are entangled. The molded product has excellent heat resistance, high elongation, and has a small amount of resin flowing out, resulting in a uniform product.

Depending on the usage conditions of the molded article, for example, when solvent resistance is required, a resin obtained by modifying a phenoxy resin with epoxy may be used. Even if an epoxy-modified phenoxy resin is used, the above-mentioned excellent properties do not change.In this case, it goes without saying that either one of the C components or a mixture of both can be used. The temperature dependence of the viscosity of the matrix resin for prepreg is A,
It becomes duller than a mixed resin containing only component B.

This has the advantage that when prepregs are laminated at room temperature, the viscosity does not change much even with a temperature difference of about 2 to 3° C. in the workplace, and the workability (tackiness, drapeability) is less likely to change.

Also, as mentioned earlier, when heat forming, the minimum viscosity is high;
C
It can be controlled by adding the amount of the component. This makes it possible to control the weight of the molded product, which is very advantageous in terms of quality control, and also makes it possible to obtain a so-called non-bleed molded product without resin flowing out depending on the amount of components D and C added. The amount of component C to be blended in the composition is 3 to 40 parts by weight, preferably 5 to 20 parts by weight out of 100 parts by weight of the total amount of components A+B+C. If the amount is less than 3 parts by weight, the above-mentioned effects will not be obtained, and if it exceeds 40 parts by weight, the viscosity will be high.
, it becomes unusable as a matrix resin for prepreg. Note that the phenoxy resin used as component C here has an average molecular weight of usually 10,000 to 100.000.
It refers to a high molecular weight epoxy resin of approximately D. Specific commercially available products include Ebito 0L-53-B-40° Epicoat 0L-55-840 (Yuka Shell Epokin!
111), DER684EK40 (manufactured by Dow Chemical), Phenotote YP50EX40 (manufactured by Tobu Kasei), PKHH,, PKHM-30 (manufactured by UCC)
etc., and further equivalents thereof can be selected and used as appropriate.

Next, for the matrix resin consisting of the above-mentioned A, B, and C components, in the present invention, dicyandiamide is used as a curing agent as the D component, and 1 to 10 parts by weight are added to the total ff 1100 parts of the matrix resin A + B + C components. It is to be blended. In this case, if it is less than 1 part by weight, the curing rate is slow and it takes time to mold, while if it is more than 10 parts by weight, the properties such as interlaminar shear strength when formed into a laminated prepreg molded product will deteriorate.

Dicyandiamide, component D, exhibits the desired effect when used in combination with the curing accelerator, component E, in the present invention. That is, by using a suitable compound that can act as a curing accelerator for dicyandiamide, 140
D can be cured at a low temperature of 20°C or lower, and has a shelf life of 2 months or more at 20°C. Such curing accelerators include imitazole derivatives, such as Curazole 2P4MH71 manufactured by Shikoku Kasei Kogyo 2, carboxylic acid salts and metal complex salts of imitazole, or urea compounds, such as 3-(3,4-dichlorophenyl)-1,1 -N dimethylurea and the like exhibit excellent effects as component E. In this case, the blending amount of component E, A+B+C, per 100 weight parts of the total resin amount is 1 to 10 parts by weight, and if it is less than 1 part by weight, it will be difficult to accelerate the curing speed of the component D curing agent, and if it is less than 10 parts by weight. If the amount is too large, the strength of the cured molded product will decrease.

The composition of the present invention essentially requires the components A, B, C, D, and E described above, but in the present invention, anhydrous silica, pigments, etc. may be added as necessary.

Further, carbon fibers used with the matrix resin composition of the present invention include rayon-based, polyacrylonitrile-based,
Any carbon fiber such as pitch type (graphite fiber in a broad sense)
There is no problem even if it is.

〔Example〕

The present invention will be explained in more detail with reference to Examples below.

As component A, Talesol novolank type epoxy resin,
ECN-1273 manufactured by Ciba Geigy Japan, Araldite 6071 manufactured by Ciba Geigy Japan as bisphenol A type epoxy resin as component B, oil-based shell epoxy ■
Epikote 828 manufactured by Manufacturer Co., Ltd., PKHM-30 manufactured by UCC ■ as the phenoxy resin for the C component, dicyandiamide (hereinafter referred to as DTCY) as the curing agent for the D component, and 3-(3,4-dichlorophenyl)-1 as the curing accelerator for the E component. ,1
~ N dimethyl urea (hereinafter referred to as D CM [+)] were used to obtain prepreg matrix resin compositions having the formulations shown in Table 1 by simple mixing.

Next, a commercially available polyacrylonitrile carbon fiber ANC high-strength type (manufactured by Asahi Nippon Carbon ■) was impregnated with the mixture by the true melt method to obtain a unidirectional carbon fiber prepreg.

Next, regarding the prepreg obtained in this way, on the one hand, the thickness was 21 and the axial direction was 1 so that the fiber direction was in the 0° direction.
A test material for measuring the glass transition temperature (Tg) was obtained by laminating 3 flat plates of 3 mm, and a 21 m thick and 25 mm inner diameter plate was laminated alternately so that the fiber directions were in the 0° direction and 45° direction. It was rolled up into a pipe shape and used as a test material for measuring the amount of resin flowing out. For a flat plate, the surface pressure is 8 kg/aa, for a pipe, it is 4
Ruffing tape was wrapped over the prepreg so that tensions k and f were applied, and both were cured at 140° C. for 120 minutes.

These measurement results are also shown in Table 1.

〔Effect of the invention〕

As is clear from the above examples, according to the present invention, it is possible to obtain a CFRP that has a good balance between heat resistance and elongation, and has excellent resin flow resistance during molding and curing. D. There is an extremely significant contribution to the development of industry.

Claims (1)

[Claims] The following components A, B, C, D and E are essential components, and A, B
and 1 to 1 part of D component per 100 parts by weight of the total amount of C component.
A matrix resin composition containing 0 parts by weight and 1 to 10 parts by weight of component E. A, 10 to 70 parts by weight of a cresol novolak epoxy resin B, 10 to 70 parts by weight of a bisphenol A epoxy resin C, 3 to 40 parts by weight of either a phenoxy resin or its epoxy modified resin, or a mixture of both D, dicyandiamide E, curing accelerator