JPH078899B2 - Curable composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a one-component curable epoxy resin composition. More specifically, the present invention relates to a one-component curable epoxy resin composition which has excellent storage stability at room temperature and is cured in a short time under heat curing conditions to give excellent curing performance.

[Conventional technology]

Epoxy resins are used in various fields such as adhesives, paints, laminates and castings because of their excellent physical properties. The epoxy resin composition currently generally used is of a two-component type in which a main agent containing an epoxy resin as a main component and a curing agent containing a polyamine as a main component are mixed when used. Although the two-component type can be cured at room temperature, it requires accurate weighing, uniform mixing, and has a limited pot life, so it is not possible to mix a large amount at a time. Since it is necessary to weigh and mix each time, the work performance is poor and it is difficult to obtain uniform physical properties.

Several one-component epoxy resin compositions have been proposed so far for the purpose of solving the drawbacks of these two-component epoxy resin compositions. For example, one in which a latent curing agent such as amine, BF ₃ complex, amine salt, guanidine compound, hydrazide compound, etc. is mixed with epoxy resin, or microcapsules of amine curing agent or one in which a curing agent is adsorbed on a molecular sieve. Is compounded with an epoxy resin.

[Problems to be solved by the invention]

As described above, the conventionally proposed one-component epoxy resin composition has a drawback that one having excellent storage stability requires a high temperature for curing, and one that can be cured at a relatively low temperature has poor storage stability. Yes, it is not practically satisfactory,
There has been a great demand for the advent of a one-component epoxy resin composition that satisfies both storage stability and curability.

The present inventors have conducted intensive studies to overcome the drawbacks of the conventional one-component type epoxy resin composition, and have completed the present invention.

[Means for solving problems]

The present invention provides a curable composition comprising (1) an epoxy resin and (2) a fine powder latent curing agent obtained by surface-treating a fine powder epoxy resin curing agent with an aluminum alcoholate and / or an aluminum chelate compound. It is related to.

The curable composition according to the present invention will be described in detail below.

The epoxy resin used in the present invention has an average of two or more glycidyl groups per molecule, and examples thereof include polyhydric phenols such as bisphenol A, bisphenol F, catechol and resorcin, or glycerin and polyethylene glycol. Polyglycidyl ether obtained by reacting polyhydric alcohol with epiclohydrin, or glycidyl ether ester obtained by reacting epicarboxylic acid with hydroxycarboxylic acid such as P-oxybenzoic acid or β-oxynaphthoic acid, or dimer acid, phthalate Polyglycidyl ester obtained from polycarboxylic acid such as acid, glycidylamine compound obtained from 4,4′-diaminodiphenylmethane or m-aminophenol, and epoxidized novolak or epoxidized Although Li-olefin and the like,
It is not limited to these.

The fine powder epoxy resin curing agent which is the raw material of the latent curing agent used in the present invention, when the curing agent itself is solid and is hardly soluble or insoluble in the epoxy resin at room temperature,
If necessary, crush and use. Examples of such a curing agent include diaminodiphenyl sulfone, 2,4-diaminopyridine, methylenebis-o-toluidine, diaminodiphenylamine, bis (3-chloro-4-aminophenyl).
Methane, aromatic amine compounds such as diaminobenzoic acid, dicyandiamide, ethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, guanidine compounds such as ditolylguanidine, tolylbiguanide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecane Hydrazide compounds such as acid dihydrazide, 1,3-bis (hydrazinocarboethyl-5-isopropylhydantoin, isophthalic acid dihydrazide, thiosemicarbazide, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-cyanoethyl- 2-phenylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-mercaptobenzimidazole, 2,4-diamino-6- [2 ' Methylimidazolyl -
(1) ′] Imidazole compounds such as ethyl-s-triazine, phenyldimethylurea, monochlorophenyldimethylurea, dichlorophenyldimethylurea, diethylthiourea, dibutylthiourea, ethylene compounds such as ethylenethiourea, benzotriazole, 2,4- Triamino compounds such as diamino-6-phenyl-s-triazine and 2,4,6-triamino-1,3,5-triazine, 2-mercaptobenzothiazole, N-cyclohexyl-2-benzothiazole sulfenamide, tetramethyl Examples thereof include sulfur-containing compounds such as thiuram monosulfide, 2-benzothiazoyl disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole zinc salt and zinc diethyldithiocarbamate.

When the epoxy resin curing agent, which is the raw material of the latent curing agent, is easily dissolved in the epoxy resin at room temperature or is liquid, it reacts with the curing agent, and the reaction product functions as a curing agent. A compound that is solid at room temperature without being lost and is hardly soluble or insoluble in an epoxy resin is reacted and modified, and this is used as a fine powder. Examples of epoxy resin curing agents belonging to this category include dimethylamine, diethylamine, propylamine, ethylenediamine, diethylenetriamine, triethylenetetramine,
Aliphatic amine compounds such as diethylaminopropylamine, dimethylaminoethanol, 2-hydroxyethylaminopropylamine, tri (dimethylaminomethyl) phenol, piperazine, N-aminoethylpiperazine,
Aliphatic amine compounds such as isophoronediamine, mensendiamine, 1,3-bisaminomethylcyclohexane, m-xylylenediamine, diaminodiphenylmethane, metaphenylenediamine, diaminotoluene, 4,4′-diamino-3,3 ′ -Aromatic compounds such as dimethyldiphenylmethane, aniline-formalin initial condensation product, imidazole, 4-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4 -Imidazole compounds such as methylimidazole, and polyamide amine compounds synthesized from dimer acid and aliphatic amines.

Compounds that react with these epoxy resin curing agents and can achieve the above-mentioned objects include formic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, and methylhexahydroanhydride. Carboxylic acid compounds such as phthalic acid, ethanesulfonic acid, sulfonic acid compounds such as P-toluenesulfonic acid, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, hexamethylene diisocyanate, metaxylylene diisocyanate, etc. Isocyanate compound of P-
Examples thereof include hydroxystyrene resin, brominated P-hydroxystyrene resin, phenol resin, resorcin resin, and epoxy resin. The reaction of these compounds with the above-mentioned epoxy resin curing agent can be easily obtained by following a conventionally known general synthetic method. Therefore, if the reaction product is pulverized by an appropriate method, a small amount of the latent curing agent can be obtained. A powdered epoxy resin hardener is obtained. In this case, there is no problem even if the above-mentioned curing agent is applied to an amine compound which is solid and hardly soluble or insoluble in the epoxy resin at room temperature.

The particle size of the fine powder epoxy resin curing agent for the latent curing agent is not particularly limited, but if the particle size is too large, the curing of the curable composition may be delayed or the physical properties of the cured resin may be impaired. If it is too small, problems such as mixing and filtering may occur. It is preferably smaller than 300 microns, optimally between 1 and 100 microns.

The obtained fine-powder epoxy resin curing agent can be used as it is as a latent epoxy resin curing agent for a short time, for example, for about 2 to 7 days, but it needs to be stored in a cool place and is not suitable for summer use. The value as a product is low.

As the surface treatment agent for the fine powder epoxy resin curing agent prepared in this manner, for example, aluminum ethylate,
Aluminum isopropylate, mono-s-butoxy aluminum diisopropylate, aluminum alcoholate compounds such as aluminum-s-butyrate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), hexyl acetoacetate aluminum diisopropylate, Examples thereof include aluminum chelate compounds such as cetoacetate aluminum diisopropylate, aluminum monoacetylacetonate bis (ethylacetoacetate), and aluminum tris (acetylacetonate). The amount of these surface-treating agents used is sufficient to react with the amino groups exposed on the powder surface of the fine powder epoxy resin curing agent, and if the amount is too large, the curing time of the epoxy resin will increase and If the amount is too small, the storage stability of the curable composition is not improved. Therefore, the amount of surface amine is quantified in advance with a part of the sample before surface treatment,
It is preferable to determine the amount of the surface treatment agent to be used, but the amount is not limited to this.

As a surface treatment method for the fine powder epoxy resin curing agent, a non-reactive solvent that does not dissolve the powder curing agent before and after the treatment, for example, ether, n-hexane, chloroform,
After dispersing and immersing the powder to be treated in a dilute treating agent solution such as benzene, toluene, butanol, and isopropanol,
(2) A method of obtaining a finely powdered latent curing agent by overdrying, as well as a non-reactive solubilizing agent, such as dibutyl phthalate, dioctyl phthalate, dioctyl adipate, a petroleum-based solvating agent, etc. There is a method of obtaining a masterbatch of a fine powder latent curing agent by dispersing and mixing the powder to be treated in a dilute treating agent solution such as an epoxy resin.

The curable composition of the present invention is obtained by simply uniformly mixing an epoxy resin with the finely divided latent curing agent, or masterbatch thereof, obtained as described above. Since the mixing amount varies depending on the type of curing agent, it is determined by calculating from the amine value and active hydrogen equivalent.
The fine powder latent curing agent is preferably 0.1 to 50 parts by weight per 100 parts by weight.

The curable composition of the present invention obtained as described above contains guanidine, which is a known epoxy resin latent curing accelerator,
It is possible to use hydrazide, amidine, triazine, urea, peroxide and the like together. Specifically, for example, dicyandiamide, merguanidine, sebacic acid dihydrazide, dodecanoic acid-dihydrazide, dicyandiamidine, 2,4,6-triamino-1,3,5-triazine, chlorophenyldimethylurea, dichlorophenyl-dimethyl. Urea, diethyl thiourea, hexamethylene (1,6) biscyanoacetate, dibutyl peroxide, cumyl hydroperoxide and the like can be mentioned, and the amount thereof is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the epoxy resin. Further, additives used for ordinary epoxy compositions, such as oleaginants, solvents, viscosity modifiers, reactive diluents, flexibility-imparting agents, fillers, colorants and other modifiers having various purposes. May be blended, and these blends also meet the object of the present invention and are included in the scope thereof.

〔The invention's effect〕

The epoxy resin composition of the present invention thus obtained has excellent storage stability at room temperature, can be stored for one month or more even in the summer, and is harder than the conventional one-component epoxy resin composition. The curing property of the epoxy resin composition is much improved as compared with that of the epoxy resin composition, and a cured product having good performance is provided. Therefore, the resin can be prepared and stored at one time in advance, and there is an advantage that a complicated operation is not required each time unlike the two-pack type.

〔Example〕

The present invention will be described below with reference to examples, but the scope of the present invention is not limited by these examples. "Parts" in the examples indicate parts by weight.

Reference Example 1 Sumiepoxy ESCN-220L (cresol novolac type epoxy resin manufactured by Sumitomo Chemical Co., Ltd., softening point 70 ° C, epoxy equivalent 212) 150 parts was dissolved in 400 parts ethylcellosolve,
100 parts dimethylamine aqueous solution (40
%) As soon as possible. After reacting at 50-80 ° C for 3 hours, the unreacted amine and solvent are distilled off under reduced pressure with heating at 100-160 ° C. Then, after dissolving the reaction product in 150 parts of toluene, the reaction product was similarly distilled off under reduced pressure to distill off unreacted amine in the resin to obtain 170 parts of an adduct. The adduct was pulverized with an atomizer and then further pulverized with an experimental jet pulverizer to obtain a fine powder having a particle size of 1 to 20 μm. This is a latent curing agent (I)
And

Reference Example 2 100 parts of Sumiepoxy ELA128 (Epibis type epoxy resin manufactured by Sumitomo Chemical Co., Ltd., particle size: 150P, 25 ° C, epoxy equivalent: 190) and 53 parts of 2ethyl-4-methylimidazole are mixed.
Gradually raise the temperature with stirring. When thickening begins, the contents are taken out in a vat and kept at 80 ° C for 3 hours, and then allowed to cool at room temperature. The obtained reaction product was made into fine powder in the same manner as in Reference Example 1. This is a latent curing agent (II).

Reference Example 3 115 parts of Sumiepoxy ELA128 (described above) and 25 parts of methylhexahydrophthalic anhydride are mixed well at room temperature. Next, 25 parts of dimethylaminoethanol are mixed appropriately while stirring.
Gradually raise the temperature with stirring. After thickening, incubate at 80 ℃ for 1 hour and 100 ℃ for 1 hour. After keeping warm, the contents are taken out in a vat and allowed to cool at room temperature. The obtained reaction product was made into fine powder in the same manner as in Reference Example 1. This is a latent curing agent (II
I).

Reference Example 4 According to Example 1 of US Pat. No. 3,488,742, 100 parts of diethylenetriamine and 36 parts of phthalic anhydride were reacted at 100 to 110 ° C. for 3 hours. Subsequently, the reaction product was dissolved in 100 parts of toluene under heating, the pressure was reduced to 5 to 20 mmHg, and toluene, unreacted diethylenetriamine and water produced by the reaction were distilled off. Thus, 53 parts of a reaction product at SP106 ° C. was obtained.
A fine powdery reaction product was obtained in the same manner as in Reference Example 1. This is a latent curing agent (IV).

Reference example 5 40 parts of 2-methylimidazole, 30 parts of 1,6 hexamethylene diisocyanate and 150 parts of methyl ethyl ketone were charged and reacted at 70 ° C. for 2 hours while stirring. Then, the solvent was distilled off under reduced pressure to obtain a reaction product. This fine powdery reaction product is used as a latent curing agent (V).

Reference Example 6 After dissolving 4 parts of mono-s-butoxyaluminum diisopropylate in 140 parts of Epicoat 871 (Epoxy resin manufactured by Showa Yuka Shell Co., Ltd., viscosity 5P25 ° C., epoxy equivalent 400),
Finely ground ditolylguanidine (abbreviation VI)
100 parts) and kneaded for 1 hour at room temperature to obtain a surface-treated latent curing agent masterbatch.

Reference Example 7 After dissolving 4 parts of ethyl acetoacetate aluminum diisopropylate in 200 parts of n-hexane, 100 parts of the latent curing agent (I) obtained in Reference Example 1 was added and well mixed at room temperature for 1 hour with stirring. . Then, it was filtered and dried under reduced pressure to obtain a surface-treated latent curing agent.

Reference Example 8 A latent curing agent was obtained by using the pretreatment hardener pulverized in the same manner as in Reference Examples 6 and 7 using the treatment agents and treatment solvents shown in Table 1.

In the table, Adeka EP-4000 is an epoxy resin manufactured by Asahi Denka Co., Ltd. and is an abbreviation for Adeka Resin EP-4000. Viscosity 35P25 ℃. Epoxy equivalent 320.

Examples 1 to 9 and Comparative Examples 1 to 9 Using the latent curing agent obtained by the method described in Reference Example and its masterbatch, fine pulverulent dicyandiamide and fine powdery dicyandiamide having the composition shown in Table 2 were used. A curable composition was prepared by blending chlorophenyldimethylurea and Sumiepoxy ELA128 with a disper.

The results of measuring the curing time, the adhesive strength and the storage stability of the composition using this composition are shown in Table 2.

In Comparative Example, a composition having the same composition as above was prepared by using an untreated fine powder curing agent, and the same tests as those in Examples were conducted. The results are shown in Table 2.

Curing time is measured by hot plate gel timer (Nissin Kagaku Co., Ltd.)
Manufactured). The storage stability was determined from the change with time of viscosity, and the pass was determined to be within 3 times the initial viscosity. Adhesive strength is 25 × 100 × 1.6 (mm) using mild steel plate that has been degreased by polishing.
After wrapping 12.5 (mm) wrap and pressing with a clip to perform prescribed curing, the average tensile shear strength (n
= 5) was measured.

In the table, DICY: dicyandiamide.

DCMU: dichlorophenyl-dimethylurea.

From the results of Table 2, the curable composition using the latent curing agent treated with the aluminum alcoholate and / or the aluminum chelate compound has the same curing performance as that of the curable composition using the untreated curing agent. It can be seen that the performance is shown and the storage stability is greatly improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-192722 (JP, A) JP-A 61-4722 (JP, A) JP-A 59-59720 (JP, A) JP-A 54- 100 (JP, A) JP-A-50-2798 (JP, A)

Claims (1)

[Claims] 1. A curable composition comprising (1) an epoxy resin and (2) a fine powder latent curing agent obtained by surface-treating a fine powder epoxy resin curing agent with an aluminum alcoholate and / or an aluminum chelate compound. object.