JPS63223027A - Curable composition - Google Patents

Abstract

PURPOSE:To obtain a one-pack curable epoxy resin composition having excellent storage stability at normal temperature and curable in a short time under heating to form a cured product having excellent cured properties, by compounding an epoxy resin with fine powder of a specific latent curing agent. CONSTITUTION:The objective composition is composed of (A) an epoxy resin and (B) fine powder of a latent curing agent produced by the surface treatment of fine powder of an epoxy resin hardener (e.g. piperazine) with an aluminum alcoholate (e.g. aluminum ethylate) and/or an aluminum chelate compound [e.g. aluminum tris(acetylacetonate)].

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] 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 that has excellent storage stability at room temperature, cures in a short time under heat curing conditions, and provides excellent curing performance.

[Conventional technology]

Epoxy resins are used in a variety of applications such as adhesives, paints, lamination, and casting due to their excellent physical properties. Epoxy resin compositions commonly used at present are of a two-component type, in which a main component mainly composed of an epoxy resin and a curing agent mainly composed of a polyamine are mixed at the time of use. Although two-component types can cure at room temperature, they require accurate measurement and uniform mixing, and their pot life is limited, making it impossible to mix a large amount at once. Not only is work efficiency poor, such as having to measure and mix each time, but also it is difficult to obtain uniform physical properties.

A number of one-component epoxy resin compositions have been proposed to overcome the drawbacks of these two-component epoxy resin compositions. For example, amines, BF, complexes, amine salts, guanidine compounds.

A latent curing agent such as a hydrazide compound is blended with epoxy resin, or an epoxy resin is blended with microcapsules of an amine curing agent or a curing agent adsorbed onto a molecular sieve.

[Problem that the invention seeks to solve]

As described above, the one-component epoxy resin compositions that have been proposed so far have the disadvantage that those with excellent storage stability require high temperatures for curing, and those that can be cured at relatively low temperatures have poor storage stability. However, it is not practically satisfactory,
There has been a great demand for a one-component epoxy resin composition that satisfies both storage stability and curability.

The present inventors have conducted extensive research to overcome the drawbacks of such conventional one-component epoxy resin compositions, and have now accomplished the present invention.

[Means for solving problems]

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

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

The epoxy resin used in the present invention has on average two or more glycidyl groups per molecule, such as polyhydric phenols such as bisphenol A, bisphenol F, catechol, and resorcinol, or glycerin and polyethylene glycol. Polyglycidyl ether obtained by reacting polyhydric alcohol with epichlorohydrin, or glycidyl ether ester obtained by reacting epichlorohydrin with a hydroxycarboxylic acid such as l-oxybenzoic acid β-oxynaphthoic acid, or dimer acid, Examples include polyglycidyl esters obtained from polycarboxylic acids such as phthalic acid, glycidylamine compounds obtained from 4,4'-diaminodiphenylmethane, m-aminophenol, etc., as well as epoxidized novolacs and epoxidized polyolefins. However, it is not limited to these.

When the fine powder epoxy resin curing agent that is the raw material for the latent curing agent used in the present invention is solid and poorly soluble or insoluble in the epoxy resin at room temperature,
If necessary, crush and use.

Examples of such curing agents include diaminodiphenylsulfone, 2,4-diaminopyridine, methylenebis-o
-Toluidine, diaminodiphenylamine, bis(3-
Aromatic amine compounds such as chloro-4-aminophenyl)methane and diaminobenzoic acid.

Dicyandiamide, ethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine,
Guanidine compounds such as ditolylguanidine and tolylbiguanide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, 1,3-bis(hydrazinocarboethyl-5-isopropylhydantoin, isophthalic acid dihydrazide, thiosemicarbazide, etc.) hydrazide compounds, 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) 1-ethyl-S-triazine and other imidazole compounds, phenyldimethylurea, monochlorophenyldimethylurea, dichlorophenyldimethylurea, diethylthiourea, dibutylthiourea, ethylenethio Urea compounds such as urea, benzotriazole, 2,4-diamino-6-
Triazine compounds such as phenyl-5-triazine, 2,4.6-triamino-1,3,5-triazine, 2-
Mercaptobenzothiazole, N-cyclohexyl-2
Examples include sulfur-containing compounds such as -benzothiazole sulfenamide, tetramethylthiuram monosulfide, 2-benzothiazoyl disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole zinc salt, and zinc diethyldithiocarbamate.

The epoxy resin curing agent that is the raw material for the latent curing agent is easily soluble in the epoxy resin at room temperature, or if it is liquid, it will react with the curing agent and the reaction product will not function as a curing agent. It is modified by reacting with a compound that is solid at room temperature without loss and is insoluble or insoluble in epoxy resin, and this is used as a fine powder. An example of an epoxy resin curing agent belonging to this category is dimethylamine.

diethylamine, propylamine, ethylenediamine,
Diethylenetriamine, triethylenetetramine, diethylaminopropylamine, dimethylaminoethanol, 2-hydroxyethylaminopropylamine, tri(
Aliphatic amine compounds such as dimethylaminomethyl)phenol, alicyclic amine compounds such as piperazine, N-aminoethylpiperazine, isophoronediamine, menthenediamine, 1,3-bisaminomethylcyclohexane, m-xylylenediamine, diamino diphenylmethane.

Metaphenylene diamine, diaminotoluene, 4°4'
-Aromatic compounds such as diamino-3,3'-dimethyldiphenylmethane, aniline-formalin initial clamping products, imidazole, 4-methylimidazole, 2-ethyl-4-
Examples include imidazole compounds such as methylimidazole, 1-benzyl-2-methylimidazole, and ■-cyanoethyl-2-ethyl-4-methylimidazole, and polyamide amine compounds synthesized from dimer acid and aliphatic amine.

Compounds that can react with these epoxy resin curing agents and achieve the above purpose include formic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, and methyl hexahydro anhydride. Carboxylic acid compounds such as phthalic acid, sulfonic acid compounds such as ethanesulfonic acid and P-toluenesulfonic acid, 4,4'-diphenylmethane diisocyanate, and 2,4-tolylene diisocyanate.

Examples include isocyanate compounds such as hexamethylene diisocyanate and metaxylylene diisocyanate, P-hydroxystyrene resin, brominated P-hydroxystyrene resin, phenol assay, resorcinol resin, and epoxy resin. The reaction between these compounds and the above-mentioned epoxy resin curing agent can be easily obtained by following conventionally known general synthesis methods, so if this reaction product is powdered by an appropriate method, it can be used as a latent curing agent. A powdered epoxy resin curing agent is obtained. In this case, there is no problem in applying the curing agent itself to an amine compound that is solid and poorly soluble or insoluble in the epoxy resin at room temperature.

The particle size of the fine powder epoxy resin curing agent for latent curing agent is not particularly limited, but if the particle size is too large, curing of the curable composition may be delayed or the physical properties of the cured resin may be impaired. If it is too small, it may cause trouble in operations such as mixing and passing one mouthful. Preferably smaller than 300 microns.

Optimally it is between 1 and 100 microns.

The obtained fine powder epoxy resin curing agent can be used as a latent epoxy resin curing agent for a short period of time, for example, 2 to 7 days, but it must be stored in a cool place and cannot be used in summer. Therefore, the value as a product is low.

Examples of surface treatment agents for the finely powdered epoxy resin curing agent prepared in this way include aluminum ethylate,
Aluminum alcoholate compounds such as aluminum isopropylate, mono-8-butoxyaluminum diisopropylate, aluminum-S-butyrate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetate), hexylacetoacetate aluminum diisopropylate.

Examples include aluminum chelate compounds such as aluminum cetoacetate diisopropylate, aluminum monoacetylacetonate bis(ethylacetoacetate), and aluminum tris(acetylacetonate).

The amount of these surface treatment agents used should be sufficient to react with the amino groups exposed on the powder surface of the finely powdered epoxy resin curing agent.If the amount used is too large, the curing time of the epoxy resin will become longer. , affects the physical properties of the cured product, and if it is too small, the storage stability of the curable composition will not be improved.

Therefore, it is preferable to previously quantify the amount of surface amine using a portion of a sample before one surface treatment and determine the amount of surface treatment agent to be used, but the method is not limited thereto.

As a surface treatment method for the fine powder epoxy resin curing agent, non-reactive solvents that do not dissolve the powder curing agent before and after treatment, such as ether, n-hexane, chloroform, benzene, toluene, butanol, isopropanol, etc. A method of dispersing and immersing the powder to be treated in a dilute treatment agent solution and then drying the powder to obtain a fine powder latent hardener. There is a method of obtaining a masterbatch of fine powder latent curing agent by dispersing and mixing the powder to be treated in a dilute treatment agent solution such as adipate, petroleum-based solubilizing agent, or relatively low viscosity epoxy resin. .

The curable composition of the present invention can be obtained by simply uniformly mixing the finely powdered latent curing agent or its masterbatch obtained as described above with the epoxy resin. The amount to be mixed varies depending on the type of curing agent, so it is determined by calculating from the amine value and active hydrogen equivalent, but it is necessary to mix 0.1 to 50 parts of the fine powder latent curing agent to 100 parts by weight of the epoxy resin.
Parts by weight are preferred.

The curable composition of the present invention obtained as described above contains guanidine, which is a known epoxy resin latent curing accelerator,
Hydrazide, amidine, triazine, urea, peroxide, etc. can be used in combination. Specifically, for example, dicyandiamide, merguanidine, sebacic acid dihydrazide, dodecanoic acid dihydrazide, dicyancyamidine, 2,4.6-triamino-1,3,5-triazine,
Chlorphenyldimethylurea, dichlorphenyl-dimethylurea, diethylthiourea, hexamethylene (1,6
) biscyanoacetate, dibutyl peroxide, cumyl hydroperoxide, etc., and the amount used is preferably 1 to 20 parts by weight per 100 parts by weight of the epoxy resin. Furthermore, additives used in ordinary epoxy compositions, such as solubilizing agents, solvents, viscosity modifiers, reactive diluents, flexibility agents, fillers, coloring agents, and other modifiers for various purposes, etc. There is no problem in blending these blends, and these blends also meet the purpose of the present invention and are included within its scope.

〔Effect of the invention〕

The epoxy resin composition of the present invention obtained in this way has excellent storage stability at room temperature, can be stored for more than one month even in summer, and has a higher hardness than conventional one-component epoxy resin compositions. Its curability is greatly improved compared to that of highly separable epoxy resin compositions, providing a cured product with good performance.

Therefore, the resin can be prepared and stored all at once, and has the advantage of not requiring complicated operations each time unlike the two-component type.

〔Example〕

The present invention will be explained 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 (Resol novolak type epoxy resin manufactured by Sumie Chemical Industry Co., Ltd. Softening point: 70°C.

150 parts of epoxy equivalent (212) are dissolved in 400 parts of ethyl cellosolve, and 100 parts of a dimethylamine aqueous solution (40%) is immediately added dropwise while stirring with heating.

After reacting at 50-80°C for 3 hours, the reacted amine and solvent are distilled off under reduced pressure at 100-160°C under heating. then 150
After dissolving the reactant in 30 parts of toluene, the unreacted amine in the resin was similarly distilled off under reduced pressure to obtain 170 parts of an adduct. The adduct was pulverized with an atomizer and then finely pulverized with an experimental jet pulverizer to obtain a fine powder with a particle size of 1 to 20 μm. This is referred to as latent curing agent (1).

Reference example 2 Sumiepoxy ELA128 (Epivis type epoxy resin manufactured by Sumien Kagaku Kogyo ■. Viscosity 150F25℃.

100 parts of epoxy equivalent (190) and 53 parts of 2ethyl-4-methylimidazole are mixed. Gradually raise the temperature while stirring. When it starts to thicken, take out the contents into a vat.80
After incubating at ℃ for 3 hours, it is 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 referred to as a latent curing agent (TI).

Reference Example 3 115 parts of Sumiepoxy ELA128 (described above) and 25 parts of methylhexahydrophthalic anhydride are thoroughly mixed at room temperature. Next, 25 parts of dimethylaminoethanol are added dropwise to the mixture while stirring. Gradually raise the temperature while stirring. After it starts to thicken, keep it warm at 80°C for 1 hour and at 100°C for 1 hour. After keeping warm, take out the contents into a vat and leave 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 referred to as a latent curing agent (U). Reference Example 4 According to Example 1 of U.S. Patent No. 3,488,742, 100 parts of diethylene triamine and 36 parts of phthalic anhydride were
The reaction was carried out at ~110°C for 3 hours. Subsequently, the reactant was dissolved in 100 parts of toluene while heating, and the pressure was reduced to 5 to 20 mmHg to distill off toluene, unreacted diethylenetriamine, and water produced by the reaction. In this way, S, P
, 53 parts of a reaction product at 106°C was obtained. A finely powdered reaction product was obtained in the same manner as in Reference Example 1. This is used as a latent curing agent (IV)
shall be.

Reference Example 5 40 parts of 2-methylimidazole, 30 parts of 1,6 hexamethylene diisocyanate, and 150 parts of methyl ethyl ketone
of the mixture and reacted at 70° C. for 2 hours with stirring. rear,
The solvent was distilled off under reduced pressure to obtain a reaction product. This finely powdered reactant is used as a latent curing agent (V).

Reference Example 6 After dissolving 4 parts of mono-8-butoxyaluminum diisopropylate in 140 parts of Epicoat 871 (epoxy resin manufactured by Showa Yuka Shell ■, viscosity 5P 25°C, epoxy equivalent 400), it was finely ground to 1 to 20 μm. 100 parts of ditolyl guanidine (abbreviated as ■) was added and mixed in a kneader 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 20'0 parts of 0-hexane, Reference Example 1
100 parts of the latent curing agent (1) obtained in step 1 was added, and the mixture was thoroughly stirred and mixed at room temperature for 1 hour. The mixture was then passed through the mouth 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 pre-processing curing agent finely pulverized in the same manner as in Reference Examples 6 and 7 and using the processing agent and processing solvent shown in Table 1.

In the table, ADEKA EP-4000 is an epoxy resin manufactured by Asahi Denka Kogyo ■ and is an abbreviation of ADEKA RESIN EP-4000. Viscosity 35P
25℃. Epoxy equivalent: 320° Examples 1 to 9. Comparative Examples 1 to 9 Using the latent curing agent and its masterbatch obtained by the method shown in Reference Example, finely powdered dicyandiamide, finely powdered dichlorophenyldimethylurea, and sumiepoxy were prepared with the composition shown in Table 2. A curable composition was prepared by blending ELA128 with a disper.

Table 2 shows the results of measuring the curing time, adhesive strength, and storage stability of the composition using this composition.

Further, in a comparative example, a composition was prepared with the same composition as above using an untreated fine powder curing agent, and the same test as in the example was conducted, and the results are shown in Table 2.

Measure the curing time using a hot plate gel timer (manufactured by Nissin Scientific)
This was done using Storage stability was determined from the change in viscosity over time, and a value within 3 times the initial viscosity was considered acceptable. Adhesive strength is determined by lap bonding of 25 x 12.5 (nu) using polished and degreased 25 x 100 x 1゜6 (+nm) mild steel plates, compressed with clips, and cured for the specified period, then averaged at 25°C. It was determined by measuring the tensile shear strength (n=5).

In the table, DICY dicyandiamide.

DCMU dichlorophenyl-dimethylurea.

The results in Table 2 show that the curable composition using a latent curing agent treated with aluminum alcoholate and/or aluminum chelate compound has the same curing performance as that of the curable composition using an untreated curing agent. It can be seen that the performance and storage stability were greatly improved.

Claims (1)

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