JPH0259168B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for curing epoxy resin in a short time. It has been known to use N-aminoethylpiperazine as a curing agent for epoxy resins. For example, in ``Epoxy Resin'' edited by Kuniyuki Hashimoto, Nikkan Kogyo Shimbun, published on May 30, 1960, pages 102-103, there is an article containing Epicoat 828, manufactured by Yuka Ciel Epoxy Co., Ltd., which is a diglycidyl ether of bisphenol A, and N.
- It is stated that the cured product obtained by pre-curing aminoethylpiperazine at 20°C for 4 days and then post-curing at 100°C for 1 hour has a heat distortion temperature of 100°C and good impact resistance. ing. Epoxy resin compositions containing N-aminoethylpiperazine, which can be cured at room temperature, can be used as adhesives for joining old and new concrete, as repair agents for concrete cracks, as adhesives between mortar, and as adhesives and repair agents used outdoors. Useful. however,
Since the curing time of 4 days is not practical, accelerators such as phenols, ethanolamines, triphenyl phosphite, etc. are further added to speed up the curing process. However, even with these accelerators, it takes a long time, 2 to 7 days, to harden during construction work in winter (5° C. or lower), and during that time it is necessary to use other means to temporarily fix the material into mortar or pipes. As a result of various studies on rapid curing methods in winter, the present inventors found that N-aminoethylpiperazine has excellent low-temperature curing properties when an alkali metal thiocyanate or an alkaline earth metal thiocyanate is used as an accelerator. find out that
We have arrived at the present invention. That is, the present invention provides a method for curing a polyepoxy compound using N-aminoethylpiperazine in the presence of an alkali metal thiocyanate or an alkaline earth metal thiocyanate. Ethylpiperazine 100
Used in a ratio of 2 to 20 parts by weight to parts by weight, and N
- Provides a method for curing an epoxy resin, characterized in that aminoethylpiperazine and thiocyanate are diluted with an organic substance selected from cresol, phenol, furfuryl alcohol, nonylphenol, and propylene glycol. In the present invention, as the polyepoxy compound, for example, the general formula (In the formula, R ₁ is a divalent alkylene group having 1 to 6 carbon atoms or -S- group,

【formula】

[Formula] -O- group and

[Formula] One of the groups, R ₂ is -CH ₃ or -H, n is a number from 0 to about 2), a novolak obtained from an epoxy resin, a novolak type phenolic resin and epichlorohydrin Type epoxy resins include epoxy resins obtained from phthalic acid and epichlorohydrin, epoxy resins obtained from parahydroxybenzoic acid and epichlorohydrin, and epoxy resins obtained from aromatic amines such as toluidine and aniline and epichlorohydrin. Among these, diglycidyl ether of bisphenol A or diglycidyl ether of bisphenol F, which has an epoxy equivalent of 165 to 230 and is liquid at room temperature (20°C), is easy to blend with curing agents and fillers. preferred. A portion (within 30% by weight) of these epoxy resins can be added to glycidyl esters of higher fatty acids; alicyclic epoxy resins; phenyl glycidyl ether; oxides of olefins such as octylene and dodecene; butanol, 2-ethylhexyl alcohol, dodecyl alcohol, and ethylene. Reactive diluents such as glycidyl ethers of alcohols such as glycol, butanediol, polyethylene glycol, polypropylene glycol, pentaerythritol, glycerin, neopentyl glycol, and propanetriol can be used. Next, as a thiocyanate which is an accelerator used in combination with N-aminoethylpiperazine,
NaSCN, KSCN, Ca(SCN) ₂ , LiSCN, Mg
(SCN) ₂ , Ba(SCN) ₂ and the like. Among these, NaSCN, KSCN, and Ca(SCN) ₂ are preferable from an economical point of view. As thiocyanate
NH ₄ SCN is also known as an accelerator when using amine as an epoxy resin curing agent (Special Publication No. 41
-22172), but this is not preferred because it generates ammonia when mixed with N-aminoethylpiperazine. Mixing N-aminoethylpiperazine and thiocyanate usually requires heating between 40 and 200°C.
Heating is 40-200 for 10 minutes to 3 hours, preferably 80
A good time is 30 minutes to 2 hours at ~150℃. The thiocyanate is used in an amount of 2 to 30 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of N-aminoethylpiperazine. In order to improve the storage stability of the mixture and to obtain a viscosity that is easy to work with, an organic substance selected from phenol, cresol, nonylphenol, furfuryl alcohol, and propylene glycol having an alcoholic hydroxyl group or a phenolic hydroxyl group is used. It is useful to dilute N-aminopiperazine and thiocyanate. These organic substances can be used in an amount of 5 to 100 parts by weight, preferably 8 to 80 parts by weight, based on 100 parts by weight of the total of the curing agent and accelerator. Dioctyl phthalate, dibutyl phthalate, pine oil, etc., which are known as extenders and diluents for epoxy resins, are undesirable because they have poor compatibility with N-aminoethylpiperazine and thiocyanate and form gel-like substances (Reference (see Examples 1, 2 and 3). The amount of N-aminoethylpiperazine used is theoretically calculated so that the amino group is equivalent to the epoxy group of the polyepoxy compound. Note that up to 50% by weight of N-aminoethylpiperazine can be replaced with another room temperature curing agent. Other preferred room temperature curing agents include polyethylene polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, and pentaethylene hexamine, polyamide resins produced from long chain dibasic acids and polyethylene polyamines, xylene diamine,
Hydrogenated xylene diamine, amidoamine produced from long chain monomer acid and polyethylene polyamine;
Examples include isophorone diamine, heterocyclic diamine (trade name: Epomate, manufactured by Yuka Ciel Epoxy Co., Ltd.), and polyoxypropylene diamine (trade name, Diefamine). If these room temperature curing agents are used in an amount exceeding 50% by weight of the amount of N-aminoethylpiperazine used, the curing rate becomes extremely slow or a gel-like substance is formed, which is not preferable. Curing can be done at room temperature or at a low temperature below room temperature (-15 to 20
It can also be done at ℃). The epoxy resin composition can be used not only as an adhesive but also as a paint, grout, resin mortar, and the like. Hereinafter, the present invention will be explained in more detail using Examples. Note that parts and percentages in the examples are based on weight unless otherwise specified. Examples 1 to 11, Comparative Examples 1 to 6, and Reference Examples 1 to 6 A curing agent solution was produced by heating and stirring the compositions shown in Table 1 at 100° C. for 1 hour. The appearance and viscosity of this solution were as shown in the same table. Then, the curing agent solution was stored in thermostatic chambers at 20°C, 5°C, and -5°C to examine its storage stability. The results after two weeks are shown in Table-1. This prepared curing agent solution and bisphenol A
diglycidyl ether [Yuka Ciel Epoxy Co., Ltd.]
Epicoat 828 (product name), epoxy equivalent 190]
An epoxy resin composition was prepared by mixing 90 parts of n-butyl diglycidyl ether with a mixed epoxy resin solution of 10 parts of n-butyl diglycidyl ether at 20°C in the proportions shown in Table 1. and the time to reach the same temperature was measured. The results are shown in the same table. In addition, the curing agent solution and the epoxy resin solution, each kept at 0°C, were mixed at the same mixing ratio as when measuring pot life, and a 5cm long x 15cm wide x 5mm thick film was prepared in a room controlled at 0°C. It was injected into the cavity of a steel mold, and the Shore A hardness of the cast product was measured at regular intervals. The results are shown in the same table. Separately, mix the curing agent solution kept at 10°C and the epoxy resin solution at the same mixing ratio as when measuring pot life.
Casting was performed in a room controlled at 10°C using molds for tensile strength, compressive strength, and bending strength. 10℃
After curing for one day at room temperature, it was cured for one week at room temperature to obtain JIS K
The strength was measured by 6911. The results are shown in the same table. Further, the shear adhesive strength was determined by coating the surface of a sandblasted steel plate with the composition, leaving it for one week at room temperature, and measuring the adhesive strength (ASTMT-1002-64) of the obtained film. The results are shown in the same table.

【table】

Claims (1)

[Claims] 1. A method for curing a polyepoxy compound using N-aminoethylpiperazine in the presence of an alkali metal thiocyanate or an alkaline earth metal thiocyanate, comprising: Used in a proportion of 2 to 20 parts by weight per 100 parts by weight of aminoethylpiperazine,
and A method for curing an epoxy resin, characterized in that N-aminoethylpiperazine and thiocyanate are diluted with an organic substance selected from cresol, phenol, furfuryl alcohol, nonylphenol, and propylene glycol.