PURPOSE: To provide the title laminated sheet having no color irregularity, improved in appearance, reduced in voids and enhanced in electric characteristics and heat resistance by coating and impregnating a cellulosic fiber base material with a water-soluble resin and, after drying, further coating and impregnating the same with a thermosetting resin.
CONSTITUTION: Long sheet-like cellulosic fiber base material 1 are passed through a phenol or melamine resin impregnation tank 2 to be introduced into a drying oven 3 and further introduced into a resin impregnation chamber 4. This resin impregnation chamber composed of a double wall structure and a thermosetting resin impregnation tank 5 is provided within the inner wall thereof and dry dehumidified air 6 is sent in the atmosphere of said tank 5 from one end part thereof to be discharged from the other end part thereof as exhaust gas 7. Subsequently, the obtained superposed prepregs are continuously sent in a double belt press 8 to be molded under heating and pressure to form a laminated sheet which is, in turn, continuously sent to be formed into a prepreg laminated sheet 9. As the thermosetting resin, a phenol resin, a urea resin, an epoxy resin, a polyimide resin and a sulfoneamide resin are used. The water content of the cellulosic fiber base material is set to 5% or less in order to keep the characteristics of a laminated sheet product.
SOTOKI TAKEYUKI
NAKAMURA FUMITAKA
