JPS63178125A - Curable composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which is excellent in room temperature storage stability and can be cured within a short time by heating to give a product of excellent properties, by mixing an epoxy resin with a specified finely powdered latent curing agent. CONSTITUTION:A finely powdered latent curing agent (B) is obtained by mixing an inert solvent (e.g., acetone) containing a finely powdered epoxy resin curing agent (e.g., diamino-diphenyl sulfone) dispersed therein with a sultone compound (e.g., 1,3-propane sultone) in an amount to react with the amino groups exposed to the surface of the curing agent powder, and filtering and drying the mixture to treat the powder surface with the sultone compound. 100pts.wt. epoxy resin (A) is mixed with 0.1-50pts.wt. component B and 1-20pts.wt. latent cure accelerator (e.g., dicyandiamide).

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. It is not only inefficient, but also difficult to obtain uniform physical properties, such as having to measure and mix each time.

Several one-component epoxy resin compositions have been proposed to overcome the drawbacks of these two-component epoxy resin compositions. For example, epoxy resins containing latent curing agents such as amines, BF, complexes, amine salts, guanidine compounds, and hydrazide compounds, or microcapsules of amine curing agents or curing agents adsorbed onto molecular sieves, etc. is blended with epoxy resin.

[Problem that the invention attempts 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 relates to 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 a sultone compound.

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

The epoxy resin used in the present invention has two or more glycidyl groups per molecule on average, such as bisphenol A and bisphenol F.

Polyglycidyl ether obtained by reacting polyhydric phenols such as catechol and resorcin, or polyhydric alcohols such as glycerin and polyethylene glycol with evichlorohydrin, or hydroxycarboxylic acids such as P-oxybenzoic acid and β-oxynaphthoic acid. Glycidyl ether ester obtained by reacting with epichlorohydrin, polyglycidyl ester obtained from polycarboxylic acids such as dimer acid and phthalic acid, or glycidyl amine obtained from 4,4'-diaminodiphenylmethane, m-aminophenol, etc. Examples include, but are not limited to, compounds such as epoxidized novolak and epoxidized polyolefin.

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-〇-toluidine, diaminodiphenylamine, bis(3-
Aromatic amines and compounds such as chloro-4-aminophenyl)methane and diaminobenzoic acid, guanidine compounds such as dicyandiamide, ethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, ditolylguanidine, and tolylbiguanide, succinic acid dihydrazide, adipine Hydrazide compounds such as acid dihydrazide, sebacic acid dihydrazide, dodecanoic 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-
Imidazole compounds such as mercaptobenzimidazole.

Urea compounds such as phenyldimethylurea, monochlorophenyldimethylurea, dichlorophenyldimethylurea, diethylthiourea, dibutylthiourea, ethylenethiourea, benzotriazole, 2,4-diamino-6-phenyl-s-triazine, 2,4゜6 -triamino-1,3
, 5-triazine and other triazine compounds, 2-mercaptobenzothiazole, N-cyclohexyl-2-benzothiazole sulfenamide, tetramethylthiuram monosulfide, 2-benzothiazoyl disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole zinc Examples include salts, sulfur-containing compounds such as zinc diethyldithiocarbamate, and the like.

If 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 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 poorly soluble or insoluble in epoxy resin, and is used as a fine powder. Epoxy resin curing agents belonging to this category include, for example, dimethylamine, diethylamine, propylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, dimethylaminoethanol, 2-hydroxyethylaminopropylamine, tri(dimethylaminomethyl ) Aliphatic amine compounds such as phenol, piperazine.

Alicyclic amine compounds such as N-aminoethylpiperazine, isophoronediamine, menzendiamine, 1,3-bisaminomethylcyclohexane, m-xylylenediamine, and diaminodiphenylmethane.

Metaphenylene diamine, diaminotoluene, 4°4'
-Aromatic compounds such as diamino-3,3'-dimethyldiphenylmethane, aniline-formalin initial condensate, 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.

These epoxy resins react with curing agents, and.

Compounds that can achieve the above purpose include carboxylic acid compounds such as formic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, methylhexahydrophthalic anhydride, ethanesulfonic acid, P
- Sulfonic acid compounds such as toluenesulfonic acid, 4,4'
-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate.

Isocyanate compounds such as hexamethylene diisocyanate and metaxylylene diisocyanate.

Examples include P-hydroxystyrene resin, brominated P-hydroxystyrene resin, phenol resin, 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 use as a 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, it may cause problems during mixing, sifting, etc. Preferably it is less than 300 microns, optimally from 1 to 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, about 2 to 7 days, but it must be stored in a cool place and cannot withstand summer use. Therefore, the value as a product is low.

Examples of the surface treatment agent for the fine powder epoxy resin curing agent prepared in this way include sultone compounds such as 1,3-propane sultone and 1,4-butane sultone. 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. This will affect the physical properties of the cured product, and if it is too small, the storage stability of the curable composition will not be improved. Although it is preferable to decide, it is not limited to this.

As a surface treatment method for the finely powdered epoxy resin curing agent, a non-reactive solvent that does not dissolve the powdered curing agent before and after treatment, such as ether or acetone, is used.

There is a method in which the powder to be treated is dispersed and immersed in a dilute treatment agent solution such as n-hexane, chloroform, benzene, etc., and then dried to obtain a fine powder latent hardener. phthalate, dioctyl phthalate, dioctyl adipate, petroleum-based reagents, etc., or
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 solution of a treating agent such as a 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, methylguanidine, diphenylguanidine, ditolylguanidine, sebacic acid dihydrazide,
Dodecanoic acid dihydrazide, dicyancyamidine, 2,
Examples include 4,6-triamino-1,3,5-triazine, chlorphenyldimethylurea, diethylthiourea, hexamethylene (1,6) biscyanoacetate, dibutyl peroxide, cumyl hydroperoxide, and the amount used. is 1 to 100 parts by weight of epoxy resin
Preferably 20 parts by weight, and further additives commonly used in epoxy compositions, such as solubilizers, solvents, viscosity modifiers, reactive diluents, flexibility agents, fillers, colorants, and other various purposes. There is no problem in blending modifiers having the following properties, 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 thus obtained 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. It provides a cured product with greatly improved properties and good performance.

Therefore, the resin can be prepared and stored all at once, which 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. In the examples, "1 part" indicates parts by weight.

Reference example 1 Sumiepoxy ESCN-220L (resol novolac type epoxy resin manufactured by Sumie Chemical Industry Co., Ltd.). Softening point: 73℃,
150 parts of epoxy equivalent (215) are dissolved in 400 parts of ethyl cellosolve, and 234 parts of a dimethylamine aqueous solution (40%) is added dropwise as soon as possible while stirring with heating.

After reacting at 50 to 80°C for 7 hours, unreacted amine and solvent are distilled off under reduced pressure while heating at 100 to 160°C.
After dissolving the reactant in 30 parts of toluene, the unreacted amine in the resin was similarly distilled off under reduced pressure to obtain 180 parts of an adduct. The adduct was pulverized with an atomizer and further 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 ESAOII (Epivis type epoxy resin manufactured by Sumitomo Chemical Co., Ltd.) Softening point: 69°C, epoxy equivalent: 485
) was dissolved in 300 parts of methyl cellosolve, and 40 parts of a methyl cellosolve solution (50%) of 4-methylimidazole was quickly added upstream while heating and stirring. below,
100 parts of a finely powdered adduct was obtained in the same manner as in Reference Example 1.

This is referred to as a latent curing agent (T1).

Reference example 3 Sumiepoxy ELA128 (Epivis type epoxy resin manufactured by Sumien Chemical Industry ■. Viscosity 130P25℃.

115 parts of epoxy equivalent (190) and 25 parts of methylhexahydrophthalic anhydride are thoroughly mixed at room temperature.

Next, 25 parts of dimethylaminoethanol are mixed upstream with 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 at room temperature. The obtained solid was made into fine powder in the same manner as in Reference Example 1. This is referred to as latent curing agent (III).

Reference example 4 According to Example 1 of US Pat. No. 3,488,742.

100 parts of diethylene triamine and 36 parts of phthalic anhydride were reacted at 100 to 110°C for 3 hours. Subsequently, the reactant was dissolved in 100 parts of toluene under heating, and the mixture was heated to 5 to 20 asH.
Toluene, unreacted diethylenetriamine, and water produced by the reaction were distilled off under reduced pressure. In this way, 53 parts of a reaction product of S, P and 106°C was obtained. A finely powdered reaction product was obtained in the same manner as in Reference Example 1. This is treated as a latent hardener (
IV).

Reference Example 5 50 parts of 2-ethyl-4-methylimidazole, 30 parts of 1°6 hexamethylene diisocyanate and 200 parts of methyl ethyl ketone were charged and reacted at 70°C for 1 hour with stirring. Thereafter, 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 Adekal resin EP-4000 (epoxy resin manufactured by Kadenka Kogyo ■, viscosity 35P25°C. Epoxy equivalent 320) 15
After dissolving 4 parts of propane sultone in 0 parts, 100 parts of finely pulverized methylene bis-0-toluidine (abbreviated as ■) was added to 1 to 20μ, and the mixture was mixed in a kneader for 1 hour at room temperature for surface treatment. A masterbatch of curing agent was obtained.

Reference Example 7 After dissolving 4 parts of propane sultone in 200 parts of n-hexane, 100 parts of finely ground ditolylguanidine was added,
The mixture was thoroughly stirred and mixed for 1 hour at room temperature.

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, Epicote 807 is a Bis-F type epoxy resin manufactured by Showa Yuka Shell ■. Viscosity 30P 25℃.

Epoxy equivalent: 180° Epicoat 871 is an epoxy resin manufactured by Showa Yuka Shell ■, viscosity: 5P, 25°C, epoxy equivalent: 420°: Adeka EP-
4000 is an epoxy resin made by Mm Kakogyo ■ and is an abbreviation of Adekal Resin EP-4000. Viscosity 35P25℃. Epoxy equivalent of 320°DOP is dioctyl phthalate.

Examples 1 to 16 Comparative Examples 1 to 14 Finely powdered dicyandiamide and finely powdered dichloride were prepared using the latent curing agent obtained by the method shown in the reference example and its masterbatch with the composition shown in Table 2. A curable composition was prepared by blending phenyldimethylurea and Sumiepoxy 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 25xlOOxl after polishing and degreasing.

A 25 x 12.5 (nm) soft steel plate was bonded with a lap of 25 x 12.5 (nm) using a 6 (■) mild steel plate, and after being compressed with a clip and curing for a specified period, the average shear strength (n = 5) was measured at 25 °C. I asked.

In the table, DICY dicyandiamide.

DCMU dichlorophenyl-dimethylurea x1 Nidodecanoic acid-dihydrazide.

*2: Combination of 2 parts of DCMU and 2 parts of dibutyl peroxide Based on the results in Table 2, a curable composition using a latent curing agent treated with sultone was as hard as a curable composition using an untreated curing agent. It can be seen that the curing performance was equivalent to that of the previous example, and the storage stability was 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 a sultone compound.