PURPOSE: To improve the incombustibility of a laminate plate, by adhering thermosetting resin varnish compounded with a halogenated aromatic compound with a side chain having an alkyl halide group to a base material to form a prepreg.
CONSTITUTION: A halogenated aromatic compound with a side chain having an alkyl halide group is compounded with thermosetting resin varnish composed of a phenol resin, an epoxy resin or a melamine resin as a fire retardant agent. As the fire retardant agent, there is 2,2-bis-[3,5-dibromo-4-(2,3-dipropyloxy) phenyl]propane and the compounding amount thereof is pref. 5W100pts.wt. of 100pts.wt. of the thermosetting resin. The thermosetting resin varnish compounded with the fire retardant agent is infiltrated in and adhered to a base material such as a paper base material or glass cloth and dried to form a prepreg which is, in turn, heated and molded to obtain a fire retardant laminate plate.