Poromeric material and method of making same

Claim 2

A POROMERIC SHEET COMPRISING LAYER A, A VAPOR-PERMEABLE NONWOVEN FABRIC COMPRISED OF FIBERS WHICH ARE IN ENTANGLED AND INTERLOCKED RELATIONSHIP WITH ONE ANOTHER, AND LAYER B, IN SUPERPOSED ADHERENCE WITH NONWOVEN FABRIC LAYER A, A VAPOR-PERMEABLE FIBER-CONTAINING LAYER OF FLEXIBLE POLYMERIC MATERIAL, SAID LAYER B HAVING (1) AN INTER-COMMINICATING MICROPOROUS STRUCTURE, (2) A DENSITY OF AT LEAST 0.4 GRAM PER CUBIC CENTIMETER, (3) STAPLE FIBERS IN A RANDOM STATE OF DISPERSION THROUGHOUT THE LAYER, A MAJORITY OF THE FIBERS BEING FREE OF CONTACT WITH ONE ANOTHER, AND (4) A POLYMERIC MATERIAL:STAPLE FIBER WEIGHT RATIO OF ABOUT 80:20 TO 97:3.

Claim 3

A METHOD WHICH COMPRISES (1) APPLYING TO A NONWOVEN FABRIC AS DEFINED IN CLAIM 1 A DISPERSION OF FLEXIBLE POLYMERIC MATERIAL AND STAPLE FIBERS IN A LIQUID WHICH IS SOLVENT FOR THE POLYMERIC MATERIAL AND A NON-SOLVENT FOR THE FIBERS, THE POLYMERIC MATERIAL:STAPLE FIBER WEIGHT RATIO BEING ABOUT 80:20 TO 97:3, (2) COAGULATING THE LAYER APPLIED IN (1) INTO AN INTERCOMMUNICATING MICROPOROUS STRUCTURE BY BATHING IT WITH A LIQUID NON-SOLVENT FOR THE POLYMER THAT IS AT LEAST PARTIALLY MISCIBLE WITH THE LIQUID USED IN (1), (3) REMOVING SUBSTANTIALLY ALL OF THE SOLVENT FROM THE MICROPOROUS LAYER, (4) REMOVING SUBSTANTIALLY OF THE NON-SOLVENT FROM THE RESULTING SOLVENT-FREE MICROPOROUS LAYER, AND (5) PRESSING THE RESULTING COMPOSITE STRUCTURE UNDER CONDITIONS SUFFICIENT TO INCREASE THE DENSITY OF THE COATING PERMANENTLY TO AT LEAST 0.4 GRAM PER CUBIC CENTIMETER, BUT NOT SUFFICIENT TO RENDER THE COATING NONPOROUS.