JPS6030334B2 - curable mixture - Google Patents

Description

[Detailed description of the invention] The present invention relates to one-component curable epoxy resin mixtures.

More specifically, it is a one-component thermosetting epoxy that is stable for long periods at room temperature, but cures in a relatively short time under heat curing conditions to form a tough polymeric cured product with good general properties. It concerns resin mixtures. When epoxy resin is cured using organic polyamines, organic polybasic acid anhydrides, etc. as a curing agent, it becomes a cured product with excellent electromechanical and chemical properties, so it is widely used in paints, cast products, adhesives, etc. ing.

Current common epoxy resin compositions are of a two-component type consisting of a main component containing an epoxy resin as a main component and a curing agent component containing a curing agent as a main component, and there are very few one-component compositions. Although two-component epoxy resin compositions can be cured at room temperature or lower temperatures, they have various drawbacks associated with the two-component mixture.

Therefore, techniques have been developed to make it into a one-component type. Namely, '1 - Dispersion of curing agent powder insoluble at room temperature into liquid epoxy resin t2 - Addition of soluble and room temperature unreactive complex to liquid epoxy resin, {3' Dry blending of high temperature active epoxy resin and curing agent. , [4] Five methods such as mixing a room temperature insoluble curing agent into a solid epoxy resin in solution (forming a dry film by evaporating the solvent), molecular sieve adsorption of the '5' curing agent, or microencapsulation. It is. The most commonly used method among these is [1'], and it is known that dicyandiamide is the most commonly used curing agent in this case. Dicyandiamide is often used because it has excellent properties as a latent curing agent, which guarantees a practically sufficient shelf life of the mixed composition, but also because it has good general properties when cured at high temperatures. This is based on the fact that it has the ability to provide However, curing of this composition requires treatment at a high temperature of at least 14,000 °C or higher for a long time. Furthermore, if the amount exceeds 170 q0 even in a small batch, a violent exothermic reaction and decomposition will occur, and the properties of the cured product will be significantly impaired. Thus, latent curing agents have been developed that have a fast curing rate and do not impair the shelf life of the system. Tokuko Showa 4
2-11500, Mochiko Showa 43-24 Nezumi 4 Tokuko Showa 46-12
8304, Tokuko Showa 49-11 Soui Hakamako Showa 49-2132
0 and others, all of which utilize salts such as imidazole and piperazine, or salts, reaction products of organic acid salts and dicyandiamide, alcoholates, etc., as curing agents. Mixed compositions based on these technologies have the performance required of one-component epoxy resin compositions, but they foam during curing, creating cured products with many voids, and do not cure in a short time. There are many products that require high temperature conditions of 130 to 170°C, and products that do not have a sufficiently long shelf life. The inventors of the present invention, while proceeding with studies on improving one-component epoxy resin compositions, reacted epoxy resin with dimethylamine in a solvent, removed excess amine, and mixed the resulting reaction product with phenol resin or hydroxystyrene. The present invention was achieved by discovering that by applying a powdered reaction product obtained by reacting with a resin and removing the solvent as a curing agent, the drawbacks of conventional curing agents can be fully satisfied.

The purpose of the present invention is to provide a one-component epoxy resin composition that is stable for a long time at room temperature, cures quickly under relatively mild heating conditions, and provides a cured product with good general properties, and to provide a two-component epoxy resin composition. Alternatively, the purpose is to explore potential uses that have been inhibited by various drawbacks associated with existing one-component types, and thereby provide expanded applications.

The curable mixture according to the present invention is obtained by adding a powder of a reaction product obtained by reacting an epoxy resin with a dialkylamine in a solvent and a phenol resin or a hydroxystyrene resin to an epoxy resin as a latent curing agent. The basic composition is

The epoxy resin used in the present invention has an average of two or more epoxy groups per molecule, such as polyhydric phenols such as bisphenol A and resorcinol, or polyhydric alcohols such as glycerin and polyethylene glycol. Polyglycidyl ether obtained by reacting piclorhydrin, or glycidyl ether ester obtained by reacting epichlorohydrin with a hydroxycarboxylic acid such as P-oxybenzoic acid or B-oxynaphthoic acid, Alternatively, there are polyglycidyl esters derived from polycarboxylic acids such as phthalic acid and terephthalic acid, and furthermore, epoxidized novolaks and epoxidized olefins.

The epoxy resins to be reacted with the dialkylamine used in the present invention include epoxy resins derived from bisphenol A, phenol novolac resins, cresol novolac resins, etc., and any one or more of these can be mixed. It is possible to obtain a reactant with a softening point of .

Phenol resins used in the present invention include phenol, cresol, ethylphenol, butylphenol,
Examples include novolac resins obtained by the usual reaction of cumyl fer/- and formaldehyde, acetaldehyde, etc., and resins that are solid at room temperature are preferred.

Furthermore, examples of the hydroxystyrene resins used in the present invention include P-hydroxystyrene resin (Resin M, manufactured by Maruzen Sekiyu Corporation), prominated P-hydroxystyrene resin (Resin MB, manufactured by Maruzen Sekiyu Corporation), and the like.

The amount of phenol resin and hydroxystyrene resin used should be sufficient to neutralize the amino groups; too little amount may reduce the storage stability of the curable mixture; too much amount may impair the curability. There is a risk that it may decrease.

Therefore, the amount used is preferably determined in advance from the epoxy equivalent used in the synthesis of the reactant, and the equivalent ratio of hydroxyl group to amino group is preferably in the range of 0.8 to 2. The solvent is preferably one that dissolves the epoxy resin, phenol resin, and hydroxystyrene resin, such as tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, toluene, chlorobenzene, methyl cellosolp, ethyl cellosolve, and the like, with ethyl cellosolp and toluene being preferred.

Synthesis of the reactants is carried out according to the following method.

An epoxy resin is dissolved in a solvent and an excess dialkylamine aqueous solution is mixed therein and reacted while heating. After the reaction is completed, unreacted amine is distilled off, and a phenol resin or hydroxystyrene resin is added in the presence of a solvent and reacted. After the reaction is completed, the reactant can be easily obtained by removing the solvent. The reactant is used after being finely pulverized, and the amount added is preferably 0.2 to 2 parts per 10 parts of the epoxy resin. If it exceeds this range, it may cause coloring and deterioration of cured properties. The curable mixture of the present invention can be obtained simply by uniformly mixing the epoxy resin and curing agent powders described above.

The curable mixture of the present invention thus obtained has excellent storage stability and can be stored for 2 weeks or more even at 50% zero, and when cured, it rapidly cures even at a relatively low temperature of about 125 qo.

Therefore, preparing the resin all at once has the advantage of not requiring complicated operations each time unlike the conventional two-component type. Generally, various compounds are often added to epoxy compositions.

The mixture according to the invention may also contain additives used in conventional epoxy compositions, such as plasticizers, solvents, viscosity modifiers, reactive diluents, fillers, colorants, and other modifiers for various purposes. There is no problem in blending these, and these blends also meet the purpose of the present invention and are included within its scope. An example of producing a curing agent is shown below. In the examples, "parts" indicate parts by weight. Reference example 1 ESCN-220M (cresol novolac type epoxy resin manufactured by Sumitomo Chemical ■, softening point 7000, epoxy equivalent weight 20
0) 30 parts and ESAOI 1 (Epipis type epoxy resin manufactured by Sumitomo Chemical, softening point 6 Pa○, epoxy equivalent 482) 7
Dissolve 30 parts of ethyl cellosolve in 30 parts of ethyl cellosolve, and quickly add 45 parts of dimethylamine water (40%) dropwise while heating.

After reacting at 5030 for 2 hours, unreacted amine and solvent were removed at 100
The residue was distilled off under reduced pressure while heating at ~160q0 to obtain 113 parts of a reactant having a softening point of 7500.

This is called reactant A.・Reference example 2 ESAO14 (Epivis type epoxy resin manufactured by Sumitomo Chemical ■,
Softening point pseudo°C, epoxy equivalent 950) 8 base and 20 parts of Epicoat 834 (Epivis type epoxy resin manufactured by Shell Chemical ■, softening point 2 ○, epoxy equivalent 240) were dissolved in 30 $ parts of ethyl cellosolve and heated. Immediately add dimethylamine water (40%) of No. 3 dropwise.

108 parts of a reactant having a softening point of 80% was obtained in the same manner as in the previous example. This is called reactant B. Reference Example 3 Add 5 parts of toluene, 108 parts of 0-cresol, 8 parts of 37% formalin, and 0.3 part of 35% hydrochloric acid to make 90 qo.
It reacted for 4 hours.

After the reaction, the final reactant and the solvent were distilled off under reduced pressure under heating at 100 to 160 qo to obtain 113 parts of a phenol resin. The resulting resin had a softening point of 10 o. This will be referred to as resin C. Examples 1 to 5 Toluene 5 Ikarito' The reactant A obtained in Example 1 and the resin C obtained in Example 3 were mixed in the proportions shown in Table 1, dissolved while heating to 12,000 ℃, and continued for 30 minutes.

Then, toluene was removed under reduced pressure while heating at 170 ooohesium to obtain a reaction product. The obtained reaction product was finely pulverized with an atomizer and Table 2
A curable mixture was prepared with the composition shown below, and the curing time, storage stability, and appearance of the cured product were investigated. table-
1 Table 1 2 a Sumieboxy AI28 (Eboxy resin manufactured by Yukagaku ■, softening point 8-12C, eboxy equivalent 184-194
)use.

Measure the curing time using a hot plate gel timer (manufactured by Nissin Scientific)
This was done using

Examples 6 to 10 Reactant B obtained in Reference Example 2, 5 parts of ethyl cellosolve, 1 part of Koto, and Diso M (manufactured by Maruzen Sekiyu, P-hydroxystyrene resin, softening point 17〆0) were mixed in the proportions shown in Table 3. Examples 1-5
A powdered reaction product was obtained in the same manner as above.

-3-4 b) Use in powder form A curable mixture was prepared with the composition shown in Table 4, and the curing time and storage stability of the composition were determined.

Example 11 Similar to Reference Example 1, ESCN220M was changed to 3 no Miyako and ES
70 parts of AOI I was dissolved in 30 parts of ethyl cellosolve, reacted with 27 parts of diethylamine, and the solvent was removed to obtain a reaction product.

In the same manner as in Example 1, 10 parts of toluene, 5 parts of the reaction product and 25 parts of resin C were mixed and reacted under heating, and after removing the solvent, the mixture was pulverized to obtain a curing agent. As a result of measuring the curing time (at125qo) and gelling time (at5000) by mixing 10 parts of ELA128 with 2 parts of the present curing agent, the result was 34 parts, respectively.
It was over 2 weeks.

Claims (1)

[Claims] 1. A curable mixture comprising an epoxy resin and a curing agent obtained by reacting the epoxy resin with a dialkylamine and further reacting the phenol resin with a hydroxystyrene resin.