JPS59232117A - Curing of epoxy resin - Google Patents

Abstract

PURPOSE:To effect curing quickly at relatively low temperatures, and to obtain a cured article of a long vat life and good adhesion, by curing an epoxy resin with a polythiol-bare curing agent with the aid of an aliphatic tert. amine as a curing catalyst. CONSTITUTION:An epoxy resin is cured with a polythiol-type curing agent by using a cyclic or acyclic aliphatic tert. amine as a curing catalyst. The polythiol- base curing agents which can be used include thiol compounds having at least 2 thiol groups on the average per molecule, and examples of these include 1,4- butanediol, 1,8-octadienethiol compounds, and thiol compounds obtained by the esterification between thioglycolic acid and trimethyolpropane trithioglycolate. Examples of the amines include N,N-diemthylethylamine and N,N'-dimethylpiperidine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for curing an epoxy resin, and particularly to a method for curing an epoxy resin that can be cured extremely quickly at a relatively low temperature, for example, room temperature or lower. In particular, the present invention relates to a method for curing an epoxy resin that cures quickly at low temperatures and provides a cured product with a long pot life and good adhesive properties by using a polythiol curing agent in combination with a specific curing catalyst. .

Conventionally, when curing epoxy resins at room temperature, polyamines or polyamides have been used alone as curing agents, or phenols, alcohols, etc. have been used as curing accelerators for these. A fully satisfactory curing rate could not be obtained. Furthermore, if polythiols are used as a curing agent, the epoxy resin can be cured even at room temperature, but this also has the drawback of slow curing speed. In addition, in many cases, a basic substance is used in combination with a polythiol curing agent to improve the curing speed, but the compatibility is poor or an appropriate pot life and sufficient curing speed cannot be obtained, making it impractical for practical use. It wasn't satisfying.

For example, when a polythiol-based curing agent is used in combination with polyethylene polyamines, the curing speed is insufficient, and even when a polythiol-based curing agent is used together with diethylenetriamine, which has a relatively fast curing rate, a sufficient curing speed cannot be obtained. It had the disadvantage of poor compatibility with Further, even when a polyamide was used in combination with a polythiol curing agent, the curing speed was not sufficient. Furthermore, when a diazabicycloalkene (DBI) was used in combination with a polythiol curing agent, the pot life was extremely short and it was impossible to use it in practical soil. When 2.4.6-tris(dimethylaminomethyl)phenol is used in combination with a polythiol-based curing agent, curing is relatively fast, but it is still not sufficient, and it is necessary to develop a curing method for epoxy resins that cures quickly. there were. Furthermore, 2.4.6-tris(dimethylaminomethyl)phenol has high skin toxicity, and it has been desired to develop a curing catalyst with lower toxicity.

The present inventors have conducted intensive research on a practical low-temperature curing method for epoxy resins, and found that by using a polythiol-based curing agent in combination with an aliphatic tertiary amine, the pot life is long enough to enable work even at low temperatures. The inventors have discovered that the present invention can be achieved by discovering that it can be cured quickly and without curing.

In the present invention, when curing an epoxy resin with a polythiol curing agent, a cyclic or acyclic aliphatic compound is used as a curing catalyst.
This is an epoxy resin curing method characterized by using a class amine.

As the epoxy resin in the present invention, various commonly used epoxy resins can be used. For example, bisphenol-based glycidyl-type epoxy resin (Shell Chemical Co., Ltd.,
Epikote 828, etc.), novolac type epoxy resin (
Shell Chemical Co., Ltd., Epicote 152, etc.) are used.

As the polythiol curing agent used in the present invention, a thiol compound having an average of two or more thiol groups in one molecule is used. That is, thiols obtained by esterification reactions of alkylthiol compounds such as 1,4-butanedithiol and 1,8-octadienedithiol, thiogluconic acid and trimethylolpropane 1-lithioglycolate, pentaerythritol tetrathioglycolate, etc. compound, a thiol compound obtained by the reaction of an epoxy compound and hydrogen sulfide, a thiol compound obtained by the reaction of bis(dichloroethyl) formal and sodium polysulfide, 2.2' ~ bismercapto diethyl ether compound and an epoxy compound Examples include thiol compounds having a terminal thiol group obtained by the reaction of

3- Furthermore, as a preferable polythiol curing agent used in the present invention, the general formula % formula %] (However, the average value of × is 1.5 to 2.5, R□, R2 is a carbon number of 2, 6 is an alkyl group containing 1 to 2 thiol groups, mi and m2 are O or 1, and n is 1 to 20), and more preferably has an average molecular weight of 500 to 20. 2000 liquid polysulfide polymer.

The amines used as a curing catalyst in the present invention include 1 \ - R2 L 5- 4- or (where R is a methyl group, a piperidine group, R2
is an alkyl group having 1 to 20 carbon atoms, and R3 is an alkyl group having 1 to 20 carbon atoms.
N,N-dimethylethylamine, N,N-dimethylpropylamine, N,
N-dimethylpentylamine, N,N-dimethyldodecylamine, N,N-dimethylhexadodecylamine, N
, N-dimethylethanolamine, N,N-dimethylpropanol-6-amine, N,N-dimethylisopropanolamine, N
-dimethylbutanolamine, N,N-dimedylcyclohexylamine, N,N,N',N'-te1, ramedelmethylenediamine, N,N,N',N'-de1
~ Ramedyl ethylene diamine, NXN, N', N'-tetramethylpropanediamine, N, N, N', Yin-tetramethylhexamethylene diamine, N, N, N',
N'-teramylenediamine, N-
Methylpiperidine, N,N'-dimethylpiperazine, N
, N, N', N', N", N"-hexamyl-1,6
, 11-undecamethylene triamine, N1N', N''
-Tris(dimethylaminopropyl)hexahydro-8
-1-Ryazine, NXN1N-tris(dimethylaminopropyl)amine, N1N-bis(dimethylaminoethyl)methylamine, and the like.

The use W of the tertiary amine curing catalyst in the present invention varies depending on the type of epoxy resin, the type of polythiol curing agent, and the type of curing catalyst. Use 3 to 20 parts by weight for a 10O heavy lifting part.

In addition, the amount of polythiol curing agent used in the present invention varies depending on the type of epoxy resin, the type of polythiol curing agent, and the type of curing catalyst. For, 1
Approximately 0 to 150 parts by weight should be used.

In the curing method of the present invention, various additives such as fillers, pigments, softeners, flow inhibitors, and diluents can be added as necessary. These additives can be added in advance to one or both of the epoxy resin and the polythiol curing agent, or can also be added to the curing catalyst. Furthermore, it can also be added at the time of mixing the epoxy resin or polythiol curing agent.

The cured product obtained by the curing method of the present invention has excellent water resistance, chemical resistance, flexibility, and adhesive properties, and is used as a water-resistant low-temperature curing adhesive that exhibits particularly good properties for adhesion not only to dry surfaces but also to wet surfaces. can do.

The cured product obtained by the curing method of the present invention is important as an adhesive for household use, industry, and civil engineering and construction, but it can also be used as a paint, casting, and laminated resin.

Next, Examples and Comparative Examples will be given and further details will be given.

Examples 1 to 7 ■ 4.0 g of Bicoat 828 (Shell Chemical Co., Ltd., bisphenol A-based epoxy resin, epoxy 11190) and a polythiol-based curing agent represented by the general formula (1) (Toshi Thiokol Co., Ltd., trade name E1) --70, mercaptan equivalent 2
00-250>4. OQ and curing catalyst 0.40 are mixed uniformly, and the pot life (time from the start of mixing until the viscosity suddenly increases) at 20°C and the curing time (the mixture hardens and becomes tack-free to the touch) are determined. The results are shown in Table 1.

Comparative Examples 1-3 The pot life and curing time were measured in the same manner as in Examples 1-7. The results are shown in Table 1.

Examples 8-10 9- 8- Epicote 828.2. 0.2° of Oo curing catalyst was mixed uniformly. The mixture was used as an adhesive at 24°C at 20°C.
The tensile shear adhesive strength of the IC8 cured product was determined by J
Measured according to I5K6850.

The measurement results are shown in Table 2.

Examples 11 to 13 After curing at 20°C for 8 hours, adhesive strength was measured in the same manner as Examples 8 to 1o, except that the samples were immersed in water at 20°C for 16 hours. The results are shown in Table 2.

10-

Claims (1)

[Claims] A method for curing an epoxy resin, which comprises using a cyclic or acyclic aliphatic tertiary amine as a curing catalyst when curing the epoxy resin with a polythiol-based curing agent.