abstract |
(57) [Summary] [Purpose] Epoxy resin prepolymers are varnished using alcoholic solvents as solvents, and odor countermeasures at the time of prepreg manufacturing are inexpensive and unnecessary. [Structure] A bifunctional epoxy resin selected from a bifunctional epoxy resin having an epoxy equivalent of 250 or less and a brominated bifunctional epoxy resin having an epoxy equivalent of 500 or less, a polyfunctional phenol having more than 2 phenolic hydroxyl groups in one molecule, and Dicyandiamide was added in an alcoholic solvent in the presence of a catalyst to 1 equivalent of an epoxy resin to give phenols of 0. 05-0.6 equivalent, solid content concentration 30-95%, temperature 50 The reaction is performed at ˜130 ° C. in an inert atmosphere, and the resulting varnish is impregnated into a glass substrate and dried to obtain a prepreg. |