Patent ID: 6071559
Filing Date: 2000-06-06
Classification: B29B,B29C,B29K,B29L,B32B,C03C,C08J,D06N,H01L,H05K,Y10S,Y10T

Abstract:
A method of forming a sheet of resin-impregnated cloth comprising the steps of;a) providing a sheet of cloth having fiber strands therein separated by openings,b) providing a first thermosetting resin/solvent mixture wherein said resin is a resin which can be partially cured and thereafter fully cured, and which first resin in the partially-cured state during further curing will form an integral bond with a layer of a second resin during curing of said second resin,c) coating said sheet of cloth with said first resin/solvent mixture to coat, essentially all of the strands with said first resin/solvent mixture while maintaining at least some of said openings essentially free of said resin/solvent mixture,d) partially curing the resin of said first resin/solvent mixture on said strands to between about 70% and about 90% total cure,e) providing a second thermosetting resin/solvent mixture,f) coating said sheet of cloth having the partially-cured resin therein with said second resin//solvent mixture to cover said coated strands and to fill essentially all said spaces between said strands, andg) partially curing said resin of said second resin/solvent mixture to between about 20% to about 40% of total cure and further curing said resin of said first resin/solvent mixture to at least 80% total cure, while forming a rapid transition zone between said first and second coatings that is smooth substantially continuous with cross-linking between the first and second coatings to provide an essentially continuous polymer of two layers,whereby an essentially non-porous, partially-cured, resin-impregnated sheet of cloth resistant to forming dust is provided.