JPH02227420A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, containing tetraglycidyldiaminodiphenylmethane, bisphenol A-based epoxy resin and specific amine-based curing agent, excellent in elastic modulus, hardness, heat resistance and toughness and useful as civil engineering and building materials, coatings, etc. CONSTITUTION:The objective composition containing at least three components of (A) tetraglycidyldiaminodiphenylmethane (e.g. a reaction product of 4,4- diaminodiphenylmethane with epichlorohydrin), (B) preferably at least one of bisphenol A. based epoxy resin (preferably with 380-1300 number-average molecular weight) and (C) an amine-based curing agent (preferably a compound expressed by formula II, etc.) expressed by formula 1 (R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl; A is bivalent group).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition, and more specifically, it relates to an epoxy resin composition that is excellent in elastic modulus, hardness, and heat resistance, and particularly has excellent toughness, such as The present 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, machine 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 poxy 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 greatly 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 prepreg comprising at least two polyepoxy compounds, a polymeric epoxy resin, dicyandiamide, and/or a curing accelerator in the molecule. ing.

[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 this point, the present inventors first [contains a bisphenol A-based epoxy resin and an epoxy resin curing agent, and the bisphenol A-based epoxy resin has an epoxy equivalent of 190 or less. 1,300 to 1,300, and has a total number average molecular weight of 650 to 1,300.
No. 77325).

Such epoxy resin compositions have excellent tackiness, drapeability, workability, and storage stability when used as prepreg resins, but some improvement is needed in mechanical properties such as toughness and flexibility. It turned out that there was a point.

The present invention was made in view of the above circumstances, and its purpose is to exhibit excellent tack and drape properties not only at high temperatures but also at room temperature or lower temperatures, and which also exhibits excellent tack and drape properties over a wide temperature range. The object of the present invention is to provide an epoxy resin composition that remains stable over a long period of time and provides a molded article with excellent mechanical properties such as toughness and flexibility.

[Means to solve the problem]

According to studies conducted by the present inventors, it has been found that the above object can be achieved by using a specific epoxy resin together with a specific epoxy resin curing agent.

That is, the epoxy resin composition of the present invention comprises (A) tetraglycidyldiaminodiphenylmethane, (B) at least one bisphenol A-based epoxy resin, and (C) an amine-based curing agent represented by the following general formula R, NH-
A-NHR.

(wherein R1 and Rs represent an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A represents a divalent group).

Component (A) used in the present invention is tetraglycidyldiaminodiphenylmethane.

This product can be easily produced, for example, by reacting 4,4-diaminodiphenylmethane with epichlorohydrin.

Component CB) used in the present invention is a bisphenol A-based epoxy resin.

As the bisphenol A-based epoxy resin, any conventionally known epoxy resin can be used, but from the viewpoint of workability, it is desirable to blend it so that the number average molecular weight is 380 to 1300.

The usage ratio of the component (A) and the component (Il) is expressed as a molar ratio (
A)/(B)=IO/90 to 90/10, preferably 2
It is preferable to set it to 0/80 to 80/20. (A) Ingredients and (
B) The usage ratio of components (A)/(B) is 10/9 in molar ratio
If it is less than 0, the heat resistance will be insufficient, and if the molar ratio (A)/(B) exceeds 90/10, the toughness will be undesirable.

Component (C) of the present invention is an amine curing agent represented by the following general formula.

Ryu NH-A-NHR.

(In the formula, R2 and R2 represent an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A represents a divalent group.) In addition, A in the above structural formula represents a divalent group, but specific A is a divalent aliphatic hydrocarbon group which may have a substituent, and A is a divalent aliphatic hydrocarbon group which may have a substituent, but especially for high toughness, A is a divalent aliphatic hydrocarbon group, especially -CH,-. A is the most effective case, and A is a fullkylene group having 1 to 3 carbon atoms. Various structures are possible such that Y and Y' are hydrogen, an alkyl group, or an electron-withdrawing group, and 11 and n indicate the number of substituents and represent an integer from 1 to 4. According to the results of research experiments conducted by the present inventors, no matter which structure is selected, the toughness of the cured epoxy resin is as follows: It was found that it is advantageous in terms of heat resistance, although it is slightly inferior to that of the conventional method.

Further, as mentioned above, when A is a divalent aliphatic hydrocarbon group which may have a substituent, those having 1 to 6 carbon atoms, particularly preferably those having 1 to 3 carbon atoms, When is 7 or more, the hardness of the epoxy resin cured product.

The disadvantage is that heat resistance decreases.

In addition, y and v' in the above structural formula are selected from lower alkyl groups such as H1 having 1 to 6 carbon atoms or electron-withdrawing groups, and the electron-withdrawing groups include halogen groups such as F, CQ, and Br, or nitro group, trifluoromethyl group, etc.・Which of these is preferable?

H or an alkyl group having 1 to 3 carbon atoms, CΩ, and if the number of carbon atoms is 7 or more, the hardness and heat resistance of the cured epoxy resin product will decrease.

Among the secondary amine derivatives represented by the above general formula, particularly preferred ones are specifically exemplified.

It is as follows.

03NH C1t, Nil<82) rlllla Cl et al.NH-(C-juice horizontal circle■.

C) 13NH (C1, Juice-111) ICH.

CH3NH-Ze H6 C18% Nu Tame Soup-H6 −・ C1(, N11-CI-CI(, -NHC,H.

Glance false N1) CI-CH, -c) x CI IsCH, N)
)-C-CI, -NIICll.

side.

(Jl, N1(-CH, -<-R4-NHCH.

a et al. Open αt αi turtle-N) DI3 CH3NH-CH-C)t, -NHCH.

l la The amine curing agent which is component (C) of the present invention is the secondary amine represented by the above-mentioned - deceased, but if necessary, other conventionally known curing agents or reaction accelerators as described later may be used in combination. is also possible.

The epoxy resin curing agent which is the component (C) of the present invention has an active hydrogen equivalent ratio of 9 to the total amount of the components (^) and (B), which is usually 0.6 to 1.4, preferably 0.8. It is blended at a ratio of ~1.2. 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 as it is or dissolved in a solvent and heated to room temperature or, for example, 50°C, to the components (A) and (B). As the solvent, ketones (acetone) may be used. , methyl ethyl ketone, methyl isobutyl ketone, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), and amides (dimethylformamide, etc.) are preferable, and the curing conditions for the epoxy resin composition according to the present invention are usually 130° C. for 2 hours. , preferably 2 at 130°C
After curing for hours, post-curing was performed at 180° C. for 2 hours.

By performing such curing, the epoxy resin composition according to the present invention has a molecular crosslinked structure network chain concentration of 1.5 x 10-''-2,8 x 10-3 mold.
A cured product having a very unique value of /cd is obtained.

Generally, the network chain concentration is 1.5 x 10-3 moQ/
In the case of ad, the number of crosslinking points is too small and the heat resistance is 1.
The elastic modulus decreases significantly. Furthermore, since resistance to crack propagation decreases, both toughness and impact resistance decrease. On the other hand, the network chain concentration is 2,8×10−”m
If o12/aJ or more, the number of crosslinking points becomes too large and the elongation decreases, resulting in a brittle fracture morphology, resulting in a decrease in toughness and impact resistance.

On the other hand, the epoxy resin composition of the present invention has the above-mentioned (A
) component, (B) component, and (C) component as essential components, the network chain concentration is 1.5×10−” to 2.8×
It is within the range of 10-3 mail/aj, and it is possible to form a cured epoxy resin product with significantly improved toughness and excellent physical properties such as elastic modulus and heat resistance.

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 silica powder.

Fillers such as aluminum powder, mica, and calcium carbonate can also be added.Usually, the amount of these additives used is 0 to 15% by weight of the reactive diluent, based on the curing agent and epoxy resin formulation. The accelerator is θ~5% by weight, and the filler is 0% to 70% by weight.

〔Example〕

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

Example 1 25 parts by weight of a bifunctional epoxy resin (trade name, Epicoat 828: Yuka Shell Epoxy Co., Ltd.@), 75 parts by weight of a tetrafunctional epoxy resin (trade name, Epicoat 604: Yuka Shell Epoxy Co., Ltd.@), and the following. The chemical equivalents of the amine curing agent represented by the formula were heated and mixed at about 70° C. to obtain an epoxy resin solution. This was poured into a mold consisting of two glass plates and a Teflon spacer, heated at 100°C for 2 hours, and further heated at 200°C for 2 hours in an oven to harden. The epoxy resin cured product obtained in this way was
A test piece was cut out from a resin casting plate measuring 0 cm x 30 cm x 3 m, and the network chain concentration U, glass transition temperature (Tg
), Izod impact strength (IZOD) and tensile elongation (
T, S) were measured. The measurement results are shown in Table-1.

Example 2 In Example 1, the amount of the bifunctional epoxy resin (trade name, Epicoat 828: Yuka Shell Epoxy Co., Ltd. RTA) used was 50 parts by weight, and the amount of the tetrafunctional epoxy resin (trade name, Epicoat 604: Yuka Shell Epoxy Co., Ltd. A cured epoxy resin was obtained in the same manner as in Example 1, except that the amount of epoxy resin (manufactured by Shell Epoxy Co., Ltd.) used was changed to 50 parts by weight, and its performance was evaluated.

The results are shown in Table-1.

Example 3 In Example 1, the amount of bifunctional epoxy resin (trade name, Epicoat 828: manufactured by Yuka Shell Epoxy Co., Ltd.) used was 75 parts by weight, and the amount of tetrafunctional epoxy resin (trade name,
A cured epoxy resin product was obtained in the same manner as in Example 1, except that the amount of Epicoat 604 (manufactured by Yuka Shell Epoxy Co., Ltd.) used was changed to 25 parts by weight, and its performance was evaluated. The results are shown in Table-1.

Comparative example 1 In Example 1, a bifunctional epoxy resin (trade name) was used.

Example 1 except that Epicoat 828 (manufactured by Yuka Shell Epoxy Co., Ltd.) was deleted and the amount of tetrafunctional epoxy resin (trade name, Epicoat 604: Yuka Shell Epoxy Co., Ltd. Il) was changed to 100 parts by weight. A cured epoxy resin was obtained in the same manner as above, and its performance was evaluated. The results are shown in Table-1.

Comparative example 2 In Example 1, a bifunctional epoxy resin (trade name) was used.

Epikote 828 (manufactured by Yuka Shell Epoxy Co., Ltd.) was used in an amount of 100 parts by weight, and the amount of tetrafunctional epoxy resin (
A cured epoxy resin was obtained in the same manner as in Example 1, except that the product name: Epicoat 604 (Yuka Shell Epoxy Co., Ltd.) was omitted, and its performance was evaluated.

The results are shown in Table-1.

The network chain concentration (v) was determined from the elastic modulus of the rubbery region by measuring the elastic modulus from room temperature to the rubbery region using a viscoelasticity measuring device (Orientic Co., Ltd. ml) using the following equation.

C: Network chain concentration R: Gas constant T: Absolute temperature E: Elastic modulus of rubbery region Also, the tensile elongation rate (T, S) (%) is -7 according to JIS-7
113.

Table-1 It also shows stable tack and drape properties.

Patent applicant: Toa Fuel Industries Co., Ltd.

Claims (1)

[Claims] (1) At least one of (A) tetraglycidyldiaminodiphenylmethane (B) bisphenol A-based epoxy resin
species and (C) amine curing agent R_1NH represented by the following general formula
-A-NHR_2 (wherein R_1 and R_2 represent an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and A represents a divalent group) An epoxy resin composition characterized by containing at least three components: thing.