PREPARATION OF PAPER SUBSTRATE PHENOLIC RESIN PREPREG

摘要

PURPOSE:To provide the subject prepare giving laminated boards having improved electric insulation properties without deterioration the punchability by impregnating a specific amount of a hydrophilic varnish into a paper substrate, drying, impregnating a hydrophobic resol varnish into the treated paper substance and subsequently drying the treated product. CONSTITUTION:The objective prepreg is prepared by impregnating 25-35wt.% of a hydrophilic varnish (e.g. melamine resin varnish) into a paper substrate, drying the product, impregnating a hydrophobic resol varnish into the dry product and subsequently drying the product.