Process for producing laminates of fabric and fluorocarbon copolymer

Claim 1

An improvement in a process for preparing a laminate comprising a fluorocarbon copolymer top sheet and a knitted glass fabric, the improvement comprising placing an interlayer between the knitted glass fabric and the top sheet, said interlayer consisting essentially of a sheet about 1-5 mils thick of a fluorocarbon copolymer having a specific melt viscosity from 5 to 25 × 10 4 poises being sufficiently low to enable the copolymer to wet and penetrate the fabric at fabrication temperatures and lower than the specific melt viscosity of the fluorocarbon copolymer of the top sheet, said top sheet being about 5-100 mils thick and having a specific melt viscosity of 30-60 × 10 4 poises, and then integrally bonding the laminate by means of heat and pressure; wherein the fluorocarbon copolymer of the interlayer is selected from the group consisting of a copolymer of tetrafluoroethylene/hexafluoropropylene consisting essentially of 93.25-73 percent by weight of tetrafluoroethylene and 6.75-27 percent by weight of hexafluoropropylene or a copolymer of tetrafluoroethylene/perfluoro(alkyl vinyl ether) having 2-3 carbon atoms in the alkyl group consisting essentially of 99-93 percent by weight of tetrafluoroethylene and 1-7 percent by weight of perfluoro (alkyl vinyl ether).