JPH02103222A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title resin useful as a material for civil engineering and construction, having excellent heat resistance, modulus of elasticity, hardness and chemical resistance by using an epoxy resin having an epoxy equivalent in a specific range and specific number-average molecular weight. CONSTITUTION:The aimed resin containing (A) an epoxy resin of bisphenol A type which comprises <=40 pts.wt. epoxy resin having <=190 epoxy equivalent and has 600-1,300 number-average molecular weight on the whole and (B) a curing agent for epoxy resin, shown by the formula HNR1-A-HNR2 [R1 and R2 are (cyclo)alkyl, aryl or aralkyl; A is bifunctional aliphatic group hydrocarbon which may contain substituent group].

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition, and more specifically, it has excellent elastic modulus, hardness, and heat resistance, as well as particularly excellent toughness. This invention relates to an epoxy resin composition useful as a matrix resin for civil engineering and construction materials, paints, lining materials, adhesives, electrical equipment molding materials, mechanical parts, jigs, and fiber-reinforced composite materials (hereinafter abbreviated as FRP).

[Prior art]

Conventionally, epoxy resins have excellent heat resistance, elastic modulus, hardness, and chemical resistance, and are widely used as matrix resins for composite materials, especially those containing reinforcing fibers such as aramid fibers, glass fibers, and carbon fibers. However, there are various problems depending on the purpose and method of use. For example, F
When used as a matrix resin for RP, there is a problem that the mechanical strength of FRP is insufficient, especially the toughness that affects impact properties, fatigue properties, etc. Therefore, when using epoxy resin as a matrix resin,
In order to impart flexibility and further improve mechanical strength, particularly toughness, hardening agents and flexibility imparting agents are added.

However, with such conventional methods, although the flexibility of the cured epoxy resin product can be improved to some extent,
A significant decrease in physical properties such as elastic modulus, hardness, and heat resistance, which are the original characteristics of cured epoxy resins, was observed, and for example, FR
Not only is it not possible to significantly improve the toughness of P, but a new problem arises in that chemical resistance, weather resistance, water resistance, etc. are also reduced.

On the other hand, JP-A-62-127317 discloses an epoxy resin composition for prepregs comprising at least two polyepoxy compounds, a high molecular weight epoxy resin, dicyandiamide, and/or a curing accelerator in the molecule. There is.

[Problem to be solved by the invention]

However, when such epoxy resin compositions are used as prepreg epoxy resin compositions, there are problems with tackiness, drape properties, resin flow properties, workability, storage stability, etc., and improvements are desired. was.

In order to improve these points, the inventors of the present invention previously proposed that 40 parts by weight of a bisphenol A-based epoxy resin containing a bisphenol A-based epoxy resin and an epoxy resin curing agent, the bisphenol A-based epoxy resin having an epoxy equivalent of 190 or less. ``An epoxy resin composition comprising the following, and having a total number average molecular weight of 600 to 1300'' (Patent Application No. 63-7
No. 7325).

This epoxy resin composition has excellent tackiness, drapeability, workability, and storage stability when used as a prepreg resin, but according to subsequent studies by the present inventors, this epoxy resin has It was found that the tackiness and drape properties changed depending on the environmental temperature, and the properties were not stable over a wide temperature range, and there were some problems with mechanical properties such as toughness and flexibility.

The present invention was made in view of the above circumstances, and its purpose is to exhibit excellent tackiness and drapability, maintain these properties stably over a wide temperature range, and improve toughness, flexibility, etc. An object of the present invention is to provide an epoxy resin composition that gives a molded article with excellent mechanical properties.

[Means to solve the problem]

According to studies conducted by the present inventors, it has been found that the above objective can be achieved by using an epoxy resin having an epoxy equivalent in a specific range and a specific number average molecular weight, and by using a specific epoxy resin curing agent in combination. Ta.

That is, the epoxy resin composition of the present invention contains a bisphenol A-based epoxy resin and an epoxy resin curing agent,
The bisphenol A-based epoxy resin contains 40 parts by weight or less of an epoxy equivalent of 190 or less and has an overall number average molecular weight of 600 to 1300, and the epoxy resin curing agent has the following format. do.

HNRl-A-HNR2 (wherein R1 and R2 represent an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A represents a divalent aliphatic hydrocarbon group which may have a substituent) The first bisphenol A-based epoxy resin used in the invention
The feature is that it contains 40 parts by weight or less, preferably 10 to 30 parts by weight, of an epoxy equivalent having an epoxy equivalent of 190 or less. If the prepreg contains 40 parts by weight or more of an epoxy equivalent of 190 or less, the tackiness and drape properties of the resulting prepreg will be poor, the resin flow will increase during curing, and the physical properties of the cured product, especially toughness, will deteriorate. The intended purpose of the present invention cannot be achieved.

A second feature of the epoxy resin used in the present invention is that the overall number average molecular weight is in the range of 600 to 1,300.

When the number average molecular weight is less than 600, the tackiness is particularly poor when used as a prepreg resin, and the tackiness increases, resulting in a decrease in workability. Furthermore, resin flow during curing increases, making it difficult to obtain uniform molded products. On the other hand, if the number average molecular weight exceeds 1300, the tackiness, that is, the adhesiveness, becomes too low.1 For example, when used for prepreg, a problem arises in that it becomes difficult to laminate multiple sheets of prepreg. .

The bisphenol A-based epoxy resin used in the present invention is, for example, Epicoat 828, 1001 manufactured by Yuka Shell ■,
It can be prepared by appropriately mixing 1004.1007.1009.1010 (trade name) and the like.

Furthermore, according to the studies of the present inventors, general formula (1)% formula%
(1) (In the formula, R1 and R2 represent an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A represents a divalent aliphatic hydrocarbon group that may have a substituent.) When an epoxy resin composition is prepared by using an epoxy resin curing agent together with the above-mentioned bisphenol A-based epoxy resin, a chain polymer is easily formed, and a cured epoxy resin product that is particularly excellent in toughness can be obtained. It was discovered that

In the structural formula of the secondary amine derivative represented by the general formula (1) used in the present invention, R1 and R2 are preferably lower alkyl groups (for example, having 1 to 6 carbon atoms). In addition, 50 mol% or more in the total R□ and R2, preferably 80
It is desirable that mol% or more is an alkyl group. Furthermore, among the lower alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 3 carbon atoms are particularly preferable; if the number of carbon atoms is 7 or more, the hardness and heat resistance of the cured epoxy resin will decrease. come.

Further, in the secondary amine derivative represented by the above general formula (I), A is a divalent aliphatic hydrocarbon group which may have a substituent; Examples of hydrogen groups include alkylene groups having 1 to 5 carbon atoms, and examples of substituents include alkyl groups, aryl groups, halogens, and hydroxyl groups.

Specific examples of the secondary amine derivative represented by the general formula (I) are illustrated below.

cH3NH Shichigo → 閤- CH,NHCCH,l(1,H.

CB, NH(CH,)T-NHCH.

C1 et al.Nl+-+CH,)r-NHCH.

CH3NH71 □ Shiruina ■ et al. N5 et al.
-a+-co2-at□c2o.

CH.

C1l, N11-C-CIl□-NH (J+.

C1(3 C11゜C11:lN11-C11□-C-CIl2-NIIC
II.

CH3 CH CI, NH-CH-CH2-NHCI+.

r C113NH-CII-CH2-NHC)I.

■ The amine curing agent of the present invention has the general formula (1) as described above.
Although it is a secondary amine represented by the following, it is also possible to use other conventionally known curing agents and reaction accelerators as required.

The reason why the epoxy resin prepreg according to the present invention has excellent mechanical properties, particularly toughness and flexibility, as well as excellent work stability and storage stability, is not clear at present, but it is thought to be due to the following reasons.

(1) Since the curing agent of the present invention contains a secondary amine as a main component, it forms a linear molecular chain.

(2) Analysis using gel permeation chromatography (GPC) has revealed that such linear molecular chains are formed prior to the initial gelation of the curing reaction. Due to the molecular chains, the number of chain molecular components increases in the cured product, improving toughness.

(3) Since high molecular weight and low molecular weight bisphenol A-based epoxy resins are appropriately blended, the manufactured prepreg has suitable tackiness and drapability.

The epoxy resin curing agent used in the present invention is usually blended in an active hydrogen equivalent ratio of 0.6 to 1.4, preferably 0.8 to 1.2, per equivalent of the bisphenol A-based epoxy resin. If the active hydrogen equivalent ratio of the curing agent is less than 0.6 or greater than 1.4, the heat resistance and hardness of the epoxy resin curing agent will decrease, which is not preferable.

According to the present invention, the curing agent may be mixed with the bisphenol A-based epoxy resin either as it is or dissolved in a solvent, heated to room temperature or, for example, 50°C. As a solvent,
Ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), cellosolves (methyl cellosolve,
(ethyl cellosolve, etc.) and amides (dimethylformamide, etc.) are preferred. Further, the curing conditions for the epoxy resin composition according to the present invention are usually at 130°C for 2 hours, preferably at 130°C.
After curing at 0°C for 2 hours, post-curing was performed at 180°C for 2 hours.

Furthermore, when preparing the epoxy resin composition of the present invention, reactive diluents such as olefin oxide, glycidyl methacrylate, styrene oxide, and phenyl glycidyl ether; phenols, tertiary amines, imidazoles, Hardening accelerators such as complex salts of boron trifluoride, pyrazoles, and aminotriazole; and fillers such as silica powder, aluminum powder, mica, and calcium carbonate may also be added. Typically, the amounts of these additives used are 0-15% by weight2 for reactive diluents, 0-5% by weight for curing accelerators, and 0-70% by weight for fillers based on the curing agent and epoxy resin formulation. It is said that

According to another aspect of the present invention, when it is desired to improve heat resistance etc. even at the cost of some toughness, another epoxy resin other than the bisphenol A-based epoxy resin may be added as an epoxy resin component to the whole epoxy resin. It can be contained in an amount of 50 parts by weight or less per 100 parts by weight of the resin. In this case, if the content of the functional epoxy resin exceeds 50 parts by weight, the toughness will be significantly reduced, which is not preferable.

As the other epoxy resin, one or more kinds of epoxy resins that are commonly available on the market can be selected and used.
For example, glycidyl ether-based epoxy resins (bisphenol A, F, S-based epoxy resins, novolac-based epoxy resins, brominated bisphenol A-based epoxy resins), cycloaliphatic epoxy resins, glycidyl ester-based epoxy resins, glycidyl amine-based epoxy resins. , heterocyclic epoxy resins.

〔Example〕

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

Examples 1 to 6 In this example, as bisphenol A-based epoxy resins, Epicote 828 (epoxy equivalent weight 184 to 194, number average molecular weight 380), 1001 (epoxy equivalent weight 450 to
500, number average molecular weight 900), 1004 (epoxy equivalent weight 875-975, number average molecular weight 1600), 1007
(Epoxy equivalent weight 1750-2200, number average molecular weight 2
900) and 1009 (epoxy equivalent 2400-330
0, number average molecular weight 3750) (manufactured by Yuka Shell ■, trade name), using the compound shown in Table 1 as a curing agent, in the ratio shown in Table 1 to prepare a matrix resin for prepreg. did.

In Example 6, Epikote 152 (epoxy equivalent: 172 to 179, number average molecular weight: 3
70) (manufactured by Yuka Shell ■, trade name) was added in an amount of 20 parts by weight.

In each example, 1 epoxy resin component shown in Table 1 was added.
The mixture was heated and mixed at 50°C. This mixture was cooled to 80° C., and a stoichiometric amount of an epoxy resin curing agent prepared at the compounding ratio shown in Table 1 was added to prepare an epoxy resin composition having high toughness at room temperature.

This was poured into a mold consisting of two glass plates and a Teflon spacer, heated at 100°C for 2 hours, then further heated to 200°C.
It was heated in an oven for 2 hours to cure.

The epoxy resin cured product thus obtained was 30 cw.
A test piece was cut out from a resin casting plate measuring 30 cm x 3 m + hazy, and its Izod impact strength (IZOD) was measured. The results are shown in Table-1. This epoxy resin had heat resistance and particularly excellent toughness.

In addition, carbon fibers with the epoxy resin obtained above aligned in one direction (strength 350 kg/m + 1, elastic modulus 32 t/mm)
) to obtain prepreg. It was found that this prepreg had excellent tackiness, and the tackiness did not change even in the temperature range of 15 to 30°C, indicating that there was no temperature dependence of tackiness. This was laminated at 12/il and heated under the above-mentioned curing conditions to obtain a molded body. Impact extraction compressive strength of this molded body (
CAI) was measured. The results are shown in Table-1.

Further, the epoxy resin composition shown in Example 1.2 had a low viscosity and good workability during prepreg production. Further, the compositions of Examples 3 and 4 had good workability during production, and also had good properties as a prepreg, such as tackiness, drapeability, resin flowability, handling properties, and storage stability.

The composition of Example 5 was suitable as an epoxy resin for machined parts.

The composition obtained in Example 6 was an example in which a novolac type resin was blended, and the resin physical properties and prepreg properties were good like the others.

Comparative Examples 1 to 5 Epoxy resin compositions and prepregs were prepared and tested in the same manner as in the above Examples at the blending ratios shown in Table 1. The results are shown in Table-1.

From Table 1, it can be seen that the prepreg of this comparative example has poorer tackiness and toughness than the product of the present invention.

The curing agent symbols (A), (B) and (C) in Table 1 represent the following.

(A) (B) (C) CH,NH-+CH2hNl(CH3 C,)1. NH−+CI(2hN)IC,H.

(A) / Dicyandiamide = 50150 It can be seen that the tack value of the prepreg using the epoxy resin of the present invention as a matrix remains within the appropriate level even when the temperature changes, and its storage stability and workability are good. .

〔Effect of the invention〕

The epoxy resin composition according to the present invention has heat resistance, elastic modulus,
It has excellent hardness and chemical resistance, as well as toughness, flexibility,
It provides a cured product with excellent impact strength, and also has excellent breaking strength, crack resistance against thermal shock, adhesion, and adhesion. In addition, prepregs containing this material exhibit excellent tack and drape properties not only at high temperatures but also at room temperature or lower temperatures, and these properties remain stable over a wide temperature range. Workability and storage stability are dramatically increased.

Patent applicant: Toa Fuel Industries Co., Ltd.

Claims (1)

[Claims] (1) Contains a bisphenol A-based epoxy resin and an epoxy resin curing agent, and the bisphenol A-based epoxy resin contains 40 parts by weight or less of an epoxy equivalent of 190 or less, and has an overall number average molecular weight of 600 to 1300. The epoxy resin curing agent has the following general formula HNR_1-A-HNR_2 (wherein R_1 and R_2 are an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A is a dihydrogen which may have a substituent. An epoxy resin composition characterized by being an epoxy resin curing agent represented by: