JPH03258853A - Thermosetting resin composition - Google Patents

Abstract

PURPOSE:To obtain a thermosetting resin composition giving a composite material having high strength and suitable as a matrix resin of a prepreg by compounding an epoxy resin, a cyclic carbonate (derivative) containing norbornene ring and a curing agent. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of an epoxy resin preferably having an epoxy equivalent of <=2,500 with (B) 0.1-10 pts.wt. (preferably 2-7 pts.wt.) of a cyclic carbonate of formula and/or its derivative containing norbornene ring and produced by reacting cyclopentadiene with acrolein, reacting the resultant aldehyde containing norbornene ring with formaldehyde to obtain 5-norbornene-2,2'-dimethanol and finally reacting the compound with a carbonate compound or phosgene and (C) a curing agent (e.g. diethylenetriamine or BF3-monoethylamine complex).

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thermosetting resin composition for a matrix resin of a composite material, which provides a high strength composite material. Composite materials using the composition of the present invention can be applied to primary structural materials for aerospace.

<Prior Art> In recent years, a so-called prepreg, which is a heterogeneous material made by impregnating reinforcing fibers with a matrix resin composition, has come to be used as an advanced composite material for various structures.

A thermosetting resin is used as the matrix resin for such prepregs.

By the way, it is well known that thermosetting resins undergo curing shrinkage and leave internal stress at that time. It is also known that residual internal stress causes warping, distortion, and even cracking in the prepreg. In addition, the mechanism of expression of internal stress is explained by Shinbo and Female Tube (Shinbo, Female Tube, Journal of Japan Adhesive Association, Vol. 17, p. 501, 198
1, 18%, p. 203, 1983), it is thought that this is due to cooling after curing rather than shrinkage during curing.

Therefore, a method for controlling curing shrinkage of thermosetting resin is
Suggested by IGGOTT.

PIGGOTT (PIGGOTT, In
internationalSAMPE Symp, p
, 541. (Pril, 1986), if a monomer that expands during curing is added to a thermosetting resin composition, curing shrinkage is suppressed and residual internal stress is significantly suppressed. Among such monomers that expand during curing, norbornene spiro orthocarbonate exhibits a particularly great effect.

The effect of suppressing curing shrinkage expressed by the addition of norbornene spiro-orthocarbonate is thought to be related to the fact that norbornene spiro-orthocarbonate has the effect of improving the adhesion between the reinforcing fibers and the matrix resin. Addition of a small amount improves the properties of a laminate formed by laminating and curing prepregs.

However, this norbornene spiro orthocarbonate has a major drawback of being difficult to dissolve in epoxy resins. Therefore, the state of dispersion of norbornene spiro-orthocarbonate in the thermosetting resin composition affects the physical properties of the laminate after curing, making it impossible to obtain a stable product.

<Problems to be Solved by the Invention> As described above, there is no known compound that can suppress curing shrinkage of thermosetting resins and does not have fatal drawbacks.

The present invention has been made in view of the above facts, and is a composition for matrix resin of prepreg, which can be easily mixed with epoxy resin, and which has characteristics of epoxy resin, particularly wettability between epoxy resin and reinforcing fibers. The purpose of the present invention is to provide a thermosetting resin composition to which a compound is added that improves the properties of the thermosetting resin, suppresses curing shrinkage, and improves the hydration properties.

<Means for Solving the Problems> The present invention provides an epoxy resin and a cyclic carbonate containing a norbornene ring represented by the following formula I in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin and/or The present invention provides a thermosetting resin composition containing the derivative thereof and a curing agent.

...I The present invention will be explained in detail below.

The epoxy resin used in the present invention is not particularly limited as long as it is an epoxy resin. In other words, epoxy resins include widely used glycidyl ether epoxy resins such as bisphenol A epoxy resins, bisphenol F epoxy resins, novolac epoxy resins, and brominated epoxy resins, as well as cycloaliphatic epoxy resins and glycidyl epoxy resins. There are special epoxy resins such as ester-based epoxy resins, glycidylamine-based epoxy resins, and heterocyclic epoxy resins, and any of them may be used, and one type or two or more types may be used in combination.

Further, the epoxy resin may be one that is liquid at room temperature, one that is semi-solid, or one that is solid, or any of them may be used. In addition, when using an epoxy resin that is solid at room temperature,
In preparing the thermosetting resin composition of the present invention, an organic solvent is usually used in combination.

Regarding epoxy resins suitably used in the present invention, those with an epoxy equivalent of 2500 or less, such as Epicoat 828.834.1001.1004.1007 (manufactured by Yuka Shell Epoxy Co., Ltd.) Stainless Epoxy ELA1
28.134, Sumiepoxy ESAO11,014,0
17 (manufactured by Sumitomo Chemical Industries, Ltd.), etc.

The cyclic carbonate containing a norbornene ring used in the present invention is a compound whose chemical formula is represented by the following formula I.

...I A cyclic carbonate containing a norbornene ring can be prepared by a known method (Endo et al., Polyner preprints).

Japan, vol, 36. p, 1349.198
7), the outline of which is as follows.

First, cyclopentadiene and acrolein are reacted to synthesize an aldehyde containing a norbornene ring.
Next, this aldehyde is reacted with formaldehyde (Cannizzaro reaction) to obtain 5-norbornene-2,2'-dimetatool. When this dimethator is reacted with a carbonate compound or phosgene, a cyclic carbonate containing a norbornene ring represented by Formula I is synthesized.

The cyclic carbonate derivative containing a norbornene ring represented by formula I is one in which a substituent is attached to the norbornene ring, for example, one synthesized using methylcyclopentadiene as a raw material instead of cyclopentadiene, or a derivative in which an acrolein moiety is substituted. Those with groups, for example, those synthesized using α-methylacrolein as a raw material instead of acrolein.

In the thermosetting resin composition of the present invention, a cyclic carbonate containing a norbornene ring represented by formula (2) and/or a derivative thereof is added in an amount of 0.0% per 100 parts by weight of the epoxy resin.
It is contained in an amount of 1 to 10 parts by weight, preferably 2 to 7 parts by weight.

This is because if it is less than 0.1 part by weight, no effect will be exhibited, and if it exceeds 10 parts by weight, the heat resistance and water resistance will be significantly reduced.

Any curing agent that is generally used as a curing agent for epoxy resins and resins may be used.

Curing agents are classified into amine compounds, acid anhydrides, carboxylic acids, etc. and latent curing agents.

To describe each specifically, examples of amine compounds include diethylenetriamine, triethylenetetramine, menthenediamine, influorondiamine, 1.3-
Aliphatic amines such as bisaminocyclohexane, aromatic amines such as metaphenylenediamine, cyanodiphenylmethane, dichlorodiaminodiphenylmethane, diaminodiphenylsulfone, various amine ducts, cyanoethylated polyamines, modified amines such as ketimine, etc. However, acid anhydrides include phthalic anhydride, trimellitic anhydride,
In addition to aromatic acid anhydrides such as pyromellitic anhydride, cyclic aliphatic acid anhydrides such as maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, nadic anhydride, and methylnadic anhydride, aliphatic acid anhydrides, Examples include halogenated acid anhydrides and the like.

Even one type of these hardening agents is 2f! The above may be used in combination, and the content is not limited.

Further, as a latent curing agent, BF is used.

Monoethylamine complex, BF3-piperidine, BF3-
Examples include Lewis acid-amine complexes such as pyridine complexes, dicyandiamide and derivatives thereof, and organic acid hydrazites.

The content of these latent curing agents is not limited either.

Note that these latent curing agents are not used in combination with curing agents such as the amine compounds, acid anhydrides, and carboxylic acids.

In addition to the above, for epoxy resins and curing agents, see "New Epoxy Resins" edited by Hiroshi Kakiuchi (Shokodo, 1985)
I am familiar with

The thermosetting resin composition of the present invention contains the above-mentioned components as essential components, but in addition, diluents such as butyl glycidyl ether and phenyl glycidyl ether, as long as the spirit of the present invention is not impaired. Fillers such as silica, calcium carbonate, titanium oxide, colorants, anti-aging agents, etc.
It may also contain various known additives.

The thermosetting resin composition of the present invention is suitable as a matrix resin for prepregs, and the method for preparing prepregs using the composition is as follows.

That is, after forming the thermosetting resin composition of the present invention into a film, it may be impregnated into organic or inorganic fibers (reinforcing fibers).

Examples of the organic or inorganic fibers include polyamide fibers, polyester fibers, carbon fibers, glass M fibers, silicon carbide IA fibers, alumina fibers, polyethylene fibers, silicon carbide-titanium fibers, and the like.

In addition, a composite material can be obtained by laminating the prepregs obtained in this way and curing the resin in an autoclave or the like.
It is preferable to harden at ~300°C while applying a pressure of about 0.1~500 kg/cm2.

<Example> EXAMPLES The present invention will be specifically explained below with reference to Examples.

First, the synthesis of a cyclic carbonate containing a norbornene ring will be described.

(Synthesis Example 1) (1) Synthesis of 5-norbornene-2-carboxaldehyde Organic Reactions, vol, 4.
Synthesized from cyclopentadiene and acrolein according to p. 90 (yield: 80%).

(2) Synthesis of 5-norbornene-2,2'-dimetatool The 5-norbornene-2-carboxaldehyde obtained in (1) was reacted with formaldehyde using a potassium hydroxide catalyst under refluxing methanol. ,2′
-Dimethatol was synthesized (yield: 58%, melting point = 1
09.5~itt, 0°C).

(3) Synthesis of cyclic carbonate containing norbornene ring The 5-norbornene-2,2'-dimetatool obtained in (2) was treated with a sodium methoxide catalyst while refluxing toluene.
Synthesized by reacting with ethyl carbonate (yield: 44
%).

References: S, 5arel, L, ^, Poho
ryles and R, Ben-5hoshan, J.
, Am, Chew, Soc,, vol.

81, p, 1873.1959 The analysis results of this cyclic carbonate are as follows.

Melting point = 91.5-92.5°C Infrared absorption spectrum c5° 17361/cmν, 6
11801/cm IH-NMR spectrum: δ=0, 93-1, 13 ppm (1) 1)
1,40-1,87 ppm(3H)2,,
9 3 ppm (m, 2H) 4, 0 6
ppm (s, 2H) 4, 3 7 ppm (d,
2H) 6, 23 ppm (m, 2H) Elemental analysis: Actual value C(67,01), H(6,89, calculated value C(66,64t), H(6,73) (Synthesis Example 2) 5-norbornene-2,2'- obtained in Synthesis Example 1-(2)
Dimethatol was synthesized by reacting with an equivalent amount of phosgene in toluene using pyridine as a catalyst (yield: 85%).

There was no polymer formation.

(Synthesis Example 3) 5-norbornene-2,2' obtained in Synthesis Example 1-(2)
-Dimetatool was dissolved in toluene, ethyl chloroformate was charged therein, and a triethylamine-toluene solution was added dropwise to cause a reaction (yield: 58%).

There was almost no polymer formation.

(Examples 1 to 3, Comparative Example 1) The ingredients shown in Table 1 were measured and mixed to prepare a thermosetting resin composition. At this time, the cyclic carbonate containing a norbornene ring was easily mixed with the epoxy resin. Note that the cyclic carbonates containing a norbornene ring synthesized in Synthesis Examples 1 to 3 described above all exhibited similar properties, so the cyclic carbonates synthesized in Synthesis Example 3 were used in Examples 1 to 3.

Each thermosetting resin composition thus prepared was formed into a film and impregnated into a unidirectional carbon fiber (TORAYCAT-300 manufactured by Toshi Co., Ltd.) to produce a prepreg. These prepregs were laminated and cured in an autoclave to produce a laminate.

The following tests were conducted on these laminates, and the results are shown in Table 1.

(Test method) (1) 0° tensile strength: Based on A37M3039.

(2) 0° compressive strength: Based on ASTM3410.

(3) ILSS (interlaminar shear strength): Based on ASTM2344.

(4) 90" tensile strength: Based on ASTM3039 &:.

(5) 4-point bending strength: Based on JIS K7074.

(6) Compressive strength after aj impact (1000LB-IN/IN
(7) Load): Based on Boeing standard B557260.

As is clear from Table 1, the prepreg spores using the thermosetting resin compositions of Examples 1 to 3 containing a cyclic carbonate containing a norbornene ring were the same as those of Comparative Example 1.
It was superior in interlaminar shear strength, 90" tensile strength, and bending strength, and other properties were also equal to or higher than Comparative Example 1. This is thought to be due to improved wettability.

Table 1 <Effects of the Invention> According to the present invention, it can be easily mixed with an epoxy resin, which is suitable for the matrix support resin of prepreg, and it improves the properties of the epoxy resin, especially the wettability of the epoxy resin and reinforcing fibers, and reduces curing shrinkage. Thermoset resin compositions are provided that have added compounds that inhibit and improve lamination properties.

Therefore, a composite material with improved interlaminar shear strength, bending strength, 90' tensile strength, etc. can be provided to the extent that it can be applied as a primary structural material for aerospace applications.

*1) Bisphenol A type epoxy resin (Sumi Epoxy ELA134, epoxy equivalent + 250) manufactured by Sumitomo Chemical Co., Ltd. *2) Synthesis example 3 *4) Latent curing agent (B F s-monoethylamine complex), manufactured by Sumitomo Chemical Co., Ltd.

Claims (1)

[Claims] (1) Contains an epoxy resin, 0.1 to 10 parts by weight per 100 parts by weight of the epoxy resin, of a cyclic carbonate and/or its derivative containing a norbornene ring represented by the following formula I, and a curing agent. A thermosetting resin composition characterized by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... I