JPS636087B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy curable composition having excellent flexibility and comprising an epoxy resin internally plasticized with caprolactone and a polyamine. It is well known that a polyamine is blended into an epoxy resin and cured at room temperature or by heating. This cured product generally has good chemical resistance, mechanical properties, and thermal properties, and is used in many industrial fields such as electrical parts and adhesives. However, these cured products have problems in that they are very hard and lack flexibility, such as being susceptible to shrinkage distortion. Therefore, various attempts have been made to provide flexibility. For example, a method of adding a polybutadiene oligomer having a carboxyl group, a hydroxyl group, etc. at both ends, an acid type polyester resin having a carboxyl group, a polyether having a hydroxyl group, a polyester resin, etc. as a flexibility imparting agent;
Various attempts have been made, including the addition of flexible epoxy resins such as glycidyl ethers made from polyether polyols and epichlorohydrin. However, both methods reduce heat resistance and
This leads to a decrease in chemical resistance and mechanical strength.
It is hard to say that it is completely satisfactory. The present inventors conducted intensive studies on epoxy resin curable compositions having excellent flexibility, and found that
The inventors have discovered that a curable composition having excellent flexibility can be obtained by curing an epoxy resin modified with caprolactone with a polyamine at room temperature or by heating, leading to the present invention. That is, the present invention provides a curable epoxy resin obtained by blending a polyamine into a lactone-modified epoxy resin obtained by polymerizing 3 to 95 parts by weight of ε-caprolactone to 97 to 5 parts by weight of hydroxyl groups in an epoxy resin having hydroxyl groups. Regarding the composition. The lactone-modified epoxy resin used in the present invention has ε-caprolactone polymerized to the hydroxyl groups present in the epoxy resin itself, and is directly bonded to the epoxy resin as a polycaprolactone side chain, so it is not only highly flexible. It has excellent characteristics as polycaprolactone, such as heat resistance, water resistance, low temperature resistance, and compatibility. In the case of other additive-type flexibility-imparting agents, compatibility with epoxy resins may be a problem, but in the present invention, any epoxy resin having a hydroxyl group can be used with ε-caprolactone. Denaturation is possible. Therefore, the present invention is extremely useful in that flexibility can be imparted to epoxy resin curable compositions used in all industrial fields. As the epoxy resin used for producing the lactone-modified epoxy resin used in the present invention, any resin can be used as long as it has a hydroxyl group in the resin. For example, bisphenol A diglycidyl ether produced from bisphenol A and epichlorohydrin and represented by the following structural formula, An epoxy resin produced from bisphenol A and β-methylepichlorohydrin and represented by the following structural formula, Furthermore, a flame-retardant epoxy resin produced from 2,6-dibromobisphenol A and epichlorohydrin or β-methylepichlorohydrin. Alicyclic epoxy resin represented by the following formula, Epoxy resin with the following structural formula synthesized from dicarboxylic acid and epichlorohydrin Furthermore, instead of bisphenol A, it is possible to use bisphenol F synthesized from formalin and phenol, and a glycidyl ether type epoxy resin produced from epichlorohydrin. ε-caprolactone, which is reacted with these hydroxyl group-containing epoxy resins, is industrially produced by the Bayer-Villiger reaction of cyclohexanone with peracid. It is also possible to copolymerize other lactones with ε-caprolactone as long as the characteristics of the present invention are not impaired. The proportion of epoxy resin and ε-caprolactone to be reacted is 97 to 5 parts by weight of epoxy resin.
3 to 95 parts by weight of caprolactone. If the amount of modification of ε-caprolactone is too small, sufficient flexibility cannot be imparted to the cured product, and if it is too large, the cured product becomes soft. To react ε-caprolactone with epoxy resin, 100 to 240℃, preferably 120℃ in the presence of a catalyst.
Perform at ℃~200℃. If the reaction temperature is lower than 100°C, the reaction rate will be low, and if it is higher than 240°C, ε-caprolactone will vaporize and escape from the reaction system, which is not preferable. A catalyst is required for the ring-opening addition of ε-caprolactone to the secondary hydroxyl group of the epoxy resin. As catalysts, titanium compounds such as tetrabutyl titanate, tetrapropyl titanate, and tetraethyl titanate, organic tin compounds such as tin octylate, dibutyl tin oxide, and dibutyl tin laurate, and further stannous chloride, stannous bromide, A stannous halide such as stannous iodide can be used. In particular, when it is desired to obtain a substance with a narrow molecular weight distribution, stannous halides are preferred. The amount of catalyst used varies depending on the reaction temperature, but is generally 0.01~
Use 1000 ppm, preferably 0.2 to 500 ppm. The reaction may be carried out without a solvent or in a solvent containing no active hydrogen such as toluene or xylene. However, solvents having ester bonds are not preferred. This is because, during the reaction, a transesterification reaction occurs between the ester bond in the polycaprolactone chain and the solvent, producing polycaprolactone that is not bonded to the epoxy resin. Any polyamine may be used in the cured composition of the present invention, but commonly used aliphatic polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, menthenediamine, metaxylylenediamine, and N-aminoethylpiperazine. and aromatic polyamines such as metaphenylene diamine, diaminodiphenylmethane, diaminodiphenyl sulfone, dicyandiamide, melamine resin, urea resin, imidazole amino acid, etc. The amount used is 0.1 to 0.1 to 0.1 to 0.1 to 1 equivalent of the curing agent's active hydrogen per equivalent of epoxy group. 3.0 equivalents are used. In addition, alumina as a filler is added to this formulation.
Inorganic compounds such as silica, other pigments, etc. can also be mixed. Further, a flexibility imparting agent known in the art, such as butadiene acrylonitrile copolymer oligomer, polybutadiene dicarboxylic acid, polycaprolactone, dimer acid, polyether polyol, etc., is further added to this epoxy resin curable composition. You can also do that. In addition to ε-caprolactone used in the present invention, other cyclic lactones such as trimethylcaprolactone and valerolactone may be partially mixed, and ε
- These lactones may be used alone in place of caprolactone. The present invention will be described in detail below with reference to Examples, but the present invention is not limited by these. Note that parts in the examples mean parts by weight. Synthesis Example 1 2000 parts of epoxy resin "Araldite GY250" (trade name of Ciba Geigy, epoxy equivalent: 185) manufactured from bisphenol A and epichlorohydrin was placed in a four-necked flask equipped with a nitrogen inlet tube, thermometer, cooling tube, and stirring device. , 200 parts of ε-caprolactone,
0.022 part of tetrabutyl titanate was charged, and the reaction was carried out at 170°C for 8 hours under a nitrogen stream. Unreacted ε-caprolactone was 0.62%. The obtained resin had an epoxy equivalent of 210, a viscosity (Gardner) of Z ₆ , an acid value of 0.03, and a hue (Gardner) of 1.
It was a viscous liquid. Synthesis Example 2 In the same apparatus as Synthesis Example 1, "Araldite GY-
250'', 360 parts of ε-caprolactone, and 0.022 parts of tetrabutyl titanate were charged, and the mixture was reacted at 170° C. for 8 hours under a nitrogen stream. Unreacted ε-caprolactone was 0.31%. The obtained resin has an epoxy equivalent of 230, a viscosity (Gardner) of _Z4 , and an acid value of
It was a viscous liquid with a hue (Gardner) of less than 0.05 and 1. Example 1 Lactone-modified epoxy resin 100 obtained in Synthesis Example 1
25.8 parts of diaminodiphenylmethane (hereinafter abbreviated as DDM) was added to the mixture, and after pre-curing at 130℃ for 2 hours, the temperature was 150%.
Cure was carried out for 4 hours at °C. Table 1 shows the heat deformation temperature, impact strength, elongation at break, and hard strength of the obtained cured product.
Shown below. Example 2 Lactone-modified epoxy resin 100 obtained in Synthesis Example 2
22.8 parts of DDM was added to each part, and the mixture was cured under the same conditions as in Example 1. Table 1 shows the physical properties of the obtained cured product. Comparative Example 1 28.3 parts of DDM was blended with 100 parts of Araldite GY-250 that was not modified with ε-caprolactone.
It was cured under the same conditions as in Example 1. Table 1 shows the physical properties of the obtained cured product. Comparative Example 2 100 parts of "Araldite GY-250" not modified with ε-caprolactone, 10 parts of polycaprolactone triol (trade name "Plaxel 308", trade name of Daicel Chemical Industries, Ltd.) as a flexibility imparting agent and 28.3 parts of DDM was blended and cured under the same conditions as in Example 1. Table 1 shows the physical properties of the obtained cured product. Comparative Example 3 100 parts of "Araldite GY-250" not modified with ε-caprolactone was mixed with 20 parts of "Plaxel 308" as a flexibility imparting agent and 28.3 parts of DDM under the same conditions as in Example 1. I did some hardening. Table 1 shows the physical properties of the obtained cured product.

[Table] As shown in the Examples and Comparative Examples above, the cured composition using the lactone-modified epoxy resin of the present invention showed superior flexibility compared to the case where a flexibility imparting agent was simply added. There is.

Claims (1)

[Claims] 1 An epoxy resin curable composition obtained by blending a polyamine with a lactone-modified epoxy resin obtained by polymerizing 3 to 95 parts by weight of ε-caprolactone to 97 to 5 parts by weight of hydroxyl groups in an epoxy resin having hydroxyl groups. .