| 摘要 |
PURPOSE:To produce the title flame-retarding laminate excellent in heat resistance and electrical properties and low in dimensional change, by impregnating paper bases with an aqueous emulsion of an epoxy resin and a melamine resin, coating them with a flame retardant phenolic resin and drying them and laminate molding the resulting coated paper bases. CONSTITUTION:An emulsion is formed by dispersing a bisphenol A diglycidyl ether epoxy resin, a novolac resin or a mixture thereof and a melamine resin precondensate at a ratio of the solid content of the epoxy resin to that of the melamine resin precondensate of 90/10-50/50 by weight in water as a dispersing medium with the aid of a nonionic surfactant. Paper bases are coated with this emulsion and dried, and these bases are further coated with a phenolic resin containing a flame retardant and dried. The resulting coated paper bases are laminate-molded to produce the title laminate. The above process makes it possible to use a combination of an epoxy resin of excellent properties with a melamine resin in a water solvent system very effective in treating paper bases, and to obtain a product improved in heat resistance and electrical properties of a laminate, low in dimensional change upon repeated heat treatment and moisture absorption treatment and excellent in flame retardancy. |
