Continuous process for producing reinforced resin laminates

In a continuous process for producing reinforced resin laminates comprising the steps of impregnating a cellulosic fibrous substrate with a liquid thermosetting unsaturated polyester resin which is free of volatile solvent and is capable of curing without generating liquid and gaseous by-products, laminating a plurality of the resin-impregnated substrates into a unitary member, sandwiching the laminate between a pair of covering sheets, and curing the laminate while supporting the same between said pair of covering sheets without applying any appreciable pressure, the improvement comprising:

• (a) pre-impregnating said substrate with a pre-impregnating liquid comprising a mixture or condensate of:
• (i) methylol melamine and/or methylol guanamine, and
• (ii) a higher aliphatic derivative having at least one group capable of condensing with said methylol group;
• and
• (b) adjusting the final resin content in said resin-impregnated substrate at 10 to 90% by weight based upon the total weight of said resin-impregnated substrate.