| 摘要 |
PURPOSE:To obtain a prepreg having low void content and suitable as a material for electrical laminate, etc., by impregnating a fibrous substrate successively with a solvent, a high-viscosity resin varnish and a low-viscosity resin varnish, and drying the impregnated product. CONSTITUTION:A fibrous substrate 8 made of glass fiber, polyester resin, cotton, kraft paper, etc., is impregnated with a solvent having a boiling point of preferably <=100 deg.C using a solvent-impregnation roll 1 and then with a high-viscosity resin varnish (e.g. epoxy resin) having a viscosity of 0.07-0.15 Pa.S and containing a solvent compatible to the above solvent using an impregnation roll 2. The impregnated substrate is further impregnated with a low-viscosity resin varnish having a viscosity of 0.03-0.07 Pa.S and containing a solvent compatible to the above solvent using an impregnation roll 3 and the impregnation product is dried with a drier 7 to obtain the objective prepreg. The distance between the impregnation roll 1 for solvent and the impregnation roll 2 for high-viscosity resin varnish is preferably <=500cm (especially <=200cm). |
