JPH02133422A - Epoxy resin curing agent - Google Patents

Abstract

PURPOSE:To prepare an epoxy resin curing agent which gives a cured product with excellent mechanical strengths e.g., tensile strength by using as an effective component a diamine having a chain structure comprising a specific rigid aramid molecule. CONSTITUTION:An epoxy resin curing agent is produced by using as an effective component a diamine having a chain structure comprising a rigid aramid molecule of formula I, II, III, or IV (wherein n>=1). When an epoxy resin mixed with the curing agent in heated, the curing agent reacts with the resin to introduce a three-dimensional crosslinked structure into the resin, and at the same time the curing agent having the rigid molecular structure exhibits, on the molecular level, reinforcing effects corresponding to that of a reinforcing fiber, thus improving mechanical strengths of the resin. The compd. of formula I is obtd. by reacting terephthaloyl chloride with p-phenylenediamine; the compd. of formula II, by reacting p-phenylenediamine with p-nitrobenzoyl chloride, and aminating the resulting reaction product followed by the reaction with p-nitrobenzoyl chloride.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to FRP (Fiber Reinforced
Regarding curing agents used to improve the mechanical performance of epoxy resins applied to matrix resins of Plastics products, specifically, synthetic raw materials or reactivity when manufacturing epoxy resins by block copolymerization method. This invention relates to a curing agent for epoxy resins that can be used as an additive or the like.

[Conventional technology]

In recent years, the use of FRP as a structural material has progressed by taking advantage of its light weight and high strength characteristics, and it has even been used as a structural material for aircraft and space equipment, and there is a strong desire to improve its performance. .

Among these, various amines have been conventionally used as curing agents for epoxy resins in order to improve the mechanical performance of epoxy resins that are widely used as matrix resins for FRP.

[Problems to be Solved by the Invention] However, as the curing agent for the above-mentioned epoxy resin, Japanese Patent Laid-Open Nos. 63-10906 and 63-63, which the present inventors previously proposed regarding the technology for molecular strengthening of thermosetting resins, With the exception of No.-21206, there were no examples in which aramid-based rigid molecules were used.

The purpose of the present invention is to propose a technology that uses this aramid-based rigid molecule as a curing agent for epoxy resin. According to this technology, mechanical performance is better than that using conventional curing agents. We can provide excellent epoxy resins.

[Means for Solving the Problems] The present invention achieves the above object with an epoxy resin curing agent comprising a diamine having a main chain of an aramid rigid molecule having the following structural formula.

〔Structural formula〕

(n≧1) (1) (n≧1) (II) (n≧1) (II[) [Function] In the present invention, the aramid-based rigid molecules represented by the above formulas (1) to (It/) are As a reinforcing molecule, it is three-dimensionally crosslinked and cured into the epoxy resin by addition polymerization reaction.

The aramid-based rigid molecules introduced through an addition polymerization reaction with the epoxy resin correspond to reinforcing fibers at the molecular level, and have the effect of improving the mechanical performance of the epoxy resin.

〔Example〕

1. Synthesis example of aramid-based rigid molecule ■ Synthesis example of rigid molecule of structural formula (1) Hexamethylphosphoramide (HMPA) and N -Methyl-2-pyrrolidone (
This compound (d
) and p-nitrobenzoyl chloride or p-phenylenediamine solution and terephthalic acid were similarly prepared (d).
was obtained, and a loride solution having the structural formula (Ir) was added dropwise to obtain the main reaction product (a). A series of compounds were obtained.

On the other hand, terephthalic acid loride? A p-phenylenediamine solution was added dropwise to the solution to obtain the main reaction product.

Similarly, a series of aramid diamines represented by structural formula (1) were synthesized by changing the concentrations of the two solutions to be reacted.

■ Synthesis example of a rigid molecule of structural formula (n) Dimethylacetamide (DMAc) of p-phenylenediamine and p-nitrohensoyl chloride? The product obtained by mixing the 8 liquids was aminated to obtain (C).

(2) Examples of synthesis of rigid and rigid molecules of structural formula (I[) A series of compounds represented by structural formula (III) were obtained from p-nitroaniline and p-ditrobenzoyl chloride in the same manner as in (1) above.

(2) Examples of synthesis of rigid and rigid molecules of structural formula (rV) A series of compounds represented by structural formula (IV) were obtained from p-nitroaniline and terephthalic acid chloride in the same manner as in (2) above.

2. Example of introduction of aramid rigid molecules into epoxy resin Curing agents (I), (II), (Ill), (IV) of the present invention
) was used to prepare a cured epoxy resin by the method shown below.

Curing agent (I) of the present invention for bisphenol A diglycidyl ether type epoxy resin having an epoxy equivalent of 190,
Table 1 shows the amounts of (II), (III), and (IV).

Table 1 Blend amount for epoxy resin (unit: phr'''
) Table 2 Tensile strength of cured epoxy resin (unit: MPa) phr is the amount based on 100 parts of resin.
Defoaming was carried out at 60° C. for 12 hours under a reduced pressure of 1.5 g.

This mixture was heated to 260°C for 2 hours and then heated to 260°C.
After continuing heating at C for 10 minutes, the mixture was cooled to room temperature over 2 hours to obtain a cured product.

Table 2 shows the tensile strength of this cured product.

〔Effect of the invention〕

As detailed above, epoxy resins prepared using the curing agent of the present invention have superior mechanical properties compared to epoxy resins prepared using conventional curing agents (for example, p, p'-diaminodiphenylsulfone). Performance (tensile strength above p
, about 10% higher than when using p''-diaminodiphenylsulfone).

Furthermore, the epoxy resin prepared using the curing agent of the present invention can be used as is as a matrix resin for FRP, and the curing agent of the present invention has great value as an industrial material.

Claims (1)

[Claims] A curing agent for epoxy resin comprising a diamine having a main chain of an aramid rigid molecule having the following structural formula. [Structural formula] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (n≧1) (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (n≧1) (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (n≧1) (III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (n≧1) (IV)