JPS6330558A - Thermosetting resin composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which has excellent resistance to heat, impact and moisture and is suitable for use in impregnating carbon fiber having high elongation and medium modulus of elasticity, consisting of a resin composed of a cyanic ester component and a maleimide component, a liquid epoxy resin and a specified satd. polyester. CONSTITUTION:96-40 wt. resin (A) composed of a cyanic ester component and a bismaleimide component (e.g., a bismaleimide/triazine resin) is mixed with 2-50 wt% liquid epoxy resin (B) having an MW of not higher than 500 and an epoxy equivalent of not higher than 300, such as a diepoxide of a bisphenol, and 2-20 wt% satd. polyester (C) having a glass transition temp. of not lower than 40 deg.C at 150-200 deg.C. The mixture is mixed while heating at 80-120 deg.C. If desired, a catalyst (D) (e.g., triethylamine) is added thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermosetting resin composition that has excellent impact resistance and water resistance without impairing heat resistance.

[Prior art]

Recently, composite materials obtained by impregnating carbon fibers with resin and curing them, so-called carbon fiber reinforced plastics (hereinafter referred to as CFRP), have come to be widely used as primary structural materials for aircraft. .

Conventionally, epoxy resin compositions have been mainly used as carbon fiber impregnating resins, and in particular when heat resistance is desired, epoxy resins of tetraglycidyl diaminodiphenylmethane (TGDDM) and diaminodiphenylsulfone (DDS) are used as a curing agent. ) have been widely used. However, this TGD
Although DM/DDS-based epoxy resin compositions have excellent initial heat resistance and adhesion to carbon fibers, they have drawbacks such as a significant decrease in heat resistance due to moisture absorption and low compressive strength after impact. As described above, conventional epoxy resin compositions are not satisfactory for use as secondary structural materials for aircraft, which require high heat resistance and impact resistance. Furthermore, a thermosetting resin composed of a cyanate ester component and a bismaleimide component (Japanese Patent Publication No. 52-31279,
54-30440) have excellent heat resistance, but have a problem of insufficient impact resistance.

[Purpose of the invention]

An object of the present invention is to provide a thermosetting resin composition for prepreg that has excellent heat resistance and impact resistance and is suitable for impregnating high elongation and medium elasticity carbon fibers.

[Structure of the invention]

For this reason, the present invention provides 96 to 40% by weight of a resin composed of a cyanate ester component and a bismaleimide component;
The gist of the invention is a thermosetting resin composition comprising 2 to 50% by weight of a liquid epoxy resin and 2 to 20% by weight of a saturated polyester having a glass transition temperature of 40°C or higher.

Hereinafter, the configuration of the present invention will be explained in detail.

fl) A resin composed of a cyanate ester component and a bismaleimide component.

Resins composed of a cyanate ester component and a bismaleimide component are known (for example, Japanese Patent Publication No. 52-312
No. 79, Japanese Patent Publication No. 54-30440), and as this resin, a commercially available product (BT resin, manufactured by Mitsubishi Gas Chemical Co., Ltd.) can be used. The amount of this resin used is 96 to 40% by weight,
Preferably it is 90 to 60% by weight.

(2) Liquid epoxy resin.

The epoxy resin used in this invention must be in liquid form. This is due to the following reasons. The resin itself, which is composed of a cyanate ester component and a bismaleimide component, has a small tank capacity and is not preferred as a prepreg resin because it does not fit into the shape of a jig when forming prepreg layers. In addition, epoxy resin is
Because it reacts with a resin composed of a cyanate ester component and a bismaleimide component, curing time can be shortened. Therefore, epoxy resins are advantageous because they increase tack and cure in a short time.

The liquid epoxy resin that can be effectively used in the present invention preferably has a molecular weight of 500 or less and an epoxy equivalent of 300 or less, such as the following bisphenol diepoxides.

Shell Chemical Company: Ebicoat 801.802.807゜8
08, 815.819.827.828.871゜Dow Chemical Company: D, E, R, 317,330,331
゜332, 333. 337. 383. 324.
325° 36L 365° Ciba Geigy: Araldite GY 250
．． 260°280.

Susumu Kagaku Kogyosha: ELA115.117.121.1
27°128.134° The amount of liquid epoxy resin used in the present invention is from 2 to 50% by weight to provide the above-mentioned tack.

(3) Saturated polyester.

This saturated polyester is added to improve impact resistance. This saturated polyester is a known one synthesized by polycondensation of dialcohol and dicarboxylic acid. For example, it is synthesized by a polycondensation reaction between adipic acid and ethylene glycol. This saturated polyester has a glass transition temperature (Tg) of 40°C or higher.

If the glass transition temperature is less than 40° C., the saturated polyester is soft and can improve flexibility and impact resistance, but on the other hand, the compressive strength of the resin decreases. Therefore, it is unsuitable as a matrix resin for primary structural materials of aircraft.

Therefore, in the present invention, in order to improve the impact resistance while maintaining the compressive strength of the resin, a saturated polyester having a glass transition temperature of 40° C. or higher is used.

Examples of the saturated polyester having a glass transition temperature of 40°C or higher include Vylon 103.200.290 (manufactured by Toyobo Co., Ltd., Tg = 47°C, 67°C, 77°C).

The amount of saturated polyester used in the present invention ranges from 2 to 20
Weight%. If more than 20% by weight is added, the heat resistance of the resin will be significantly reduced.

It is not easy to mix a saturated polyester with a glass transition temperature of 40° C. or higher into a resin composed of a bismaleimide component and a cyanate ester component. Therefore, saturated polyester and liquid epoxy resin were heated in advance at a high temperature (150~150℃).
200°C), and the mixture was mixed into a resin composed of a bismaleimide component and a cyanate ester component.
It is preferable to mix the mixture while heating at 120°C, add a catalyst, etc., form a sheet, and impregnate fibers with the sheet to prepare a prepreg.

(4) Although the resin composition of the present invention itself has the property of being cured by heating to become a heat-resistant resin, it is usually used by containing a catalyst for the purpose of accelerating curing. Such catalysts are known ones (for example, Japanese Patent Publication No. 52-3
A tertiary amine such as triethylamine and a metal compound such as lead octylate described in Japanese Patent No. 1279 are used.

The temperature for curing the resin composition of the present invention varies depending on the presence or absence of a curing agent and catalyst, the types of composition components, etc., but it may be generally selected within the range of 150 to 300°C. It is preferable to apply pressure during heat curing, and the pressure is appropriately selected within the range of 0.1 to 500 kg/d.

The composition of the present invention contains various known additives such as flame retardants within the range that does not impair the inherent performance of the resin composition.

EXAMPLES The effects of the present invention will be specifically explained below with reference to Examples and Comparative Examples.

(1) Example 1 Epoxy resin ELA with the blending amount (wt%) shown in Table 1 below
128 (manufactured by Sumima Kagaku Kogyo Co., Ltd., epoxy equivalent: 190) and saturated polyester Byron 200 (manufactured by Toyobo Co., Ltd., T
g = 67°C) was heated to 180'C and melt mixed. This was mixed with BT resin BT2160 (manufactured by Mitsubishi Gas Chemical Industries, Ltd., bismaleimide triazine resin) at 120°C, a predetermined amount of catalyst was added, and a sheet was formed. 1 of this resin
Table 1 shows the properties of the samples cured at 80''C for 12 hours.

σ, z, 'c are dynamic viscoelastic spectrometer (DM
A) is the rigidity modulus at 121℃ measured at σ1□1℃/
σ4°C is the ratio of 121'C to 40C. This resin sheet was impregnated with carbon fiber to produce a unidirectional carbon fiber prepreg. 36 plies of this prepreg were laminated and cured at 177° C. for 2 hours. The sample's impact H
The compressive strength after (1500 fb-in/in) is shown in Table 1.

(2) Example 2 Samples were prepared in the same manner as in Example 1 using the amounts shown in Table 1, and the evaluation results are shown in Table 1.

(3) Example 3 Samples were prepared in the same manner as in Example 1 using the amounts shown in Table 1, and the evaluation results are shown in Table 1.

(4) Example 4 Saturated polyester Vylon 290 with the blending amount shown in Table 1
(Manufactured by Toyobo ■, 'rg = 77℃), ELA128
, BT2160 samples were prepared in the same manner as in Example 1, and the evaluation results are shown in Table 1.

(5) Example 5 Saturated polyester Vylon 103 with the blending amount shown in Table 1
(manufactured by Toyobo ■, Tg = 47°C), ELA128
, BT2/160 was prepared in the same manner as in Example 1, and the evaluation results are shown in Table 1.

(6) Comparative Example 1 A sample was prepared in the same manner as in Example 1 by mixing the amounts shown in Table 1 at 100°C, and the evaluation results are shown in Table 1.

If saturated polyester is not added, the compressive strength after impact is low.

(7) Comparative Example 2 Samples were prepared in the same manner as in Example 1 using the amounts shown in Table 1, and the evaluation results are shown in Table 1.

Increasing the amount of saturated polyester increases the stiffness ratio (σ1□+
'c/σ4°C) decreased significantly, and toughness was lost.

(8) Comparative Examples 3 and 4 Samples were prepared in the same manner as in Example 1 using the amounts shown in Table 1, and the evaluation results are shown in Table 1.

Although the impact resistance of Comparative Example 3 is improved to some extent, the rigidity is lower than that of the example.

The ratio of the glass transition temperature of saturated polyester to the rigidity of the cured product is plotted in FIG. 1, and the rigidity cannot be maintained unless the glass transition temperature of saturated polyester is 40°C or higher.

(9) Comparative Example 5 Samples were prepared in the same manner as in Example 1 using the amounts shown in Table 1, and the evaluation results are shown in Table 1.

It was very dangerous because it contained a large amount of epoxy.

〔Effect of the invention〕

As explained above, according to the present invention, by mixing a liquid epoxy resin and a saturated polyester with a resin composed of a cyanate ester component and a bismaleimide component, a high A thermosetting resin composition for prepreg suitable for impregnating carbon fibers with medium elongation and elasticity can be obtained. Therefore, the composition of the present invention is extremely useful for applications such as primary structural materials of aircraft.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the glass transition temperature and the ratio of rigidity of saturated polyester.

Claims (1)

[Claims] 96 to 40% by weight of a resin composed of a cyanate ester component and a bismaleimide component, and 2 to 40% by weight of a liquid epoxy resin.
50% by weight, and 2 to 20% by weight of a saturated polyester having a glass transition temperature of 40°C or higher.