Porous products and processes therefor

Claim 1

A POROUS SHEET-LIKE STRUCTURE COMPRISING: A. FORMING SHAPED ARTICLES BY MELT EXTRUDING WITH DRAWING AN IMMISCIBLE FIBER FORMING POLYMER MIXTURE, WHEREIN AT LEAST ONE POLYMER OF SAID MIXTURE IS CONVERTED TO AN EXTRACTABLE FIBER AND AT LEAST ONE OTHER POLYMER OF SAID MIXTURE IS CONVERTED TO A NON-EXTRACTABLE FIBER HAVING A CROSS-SECTIONAL DIAMETER NORMAL TO ITS ELONGATED SHAPE OF LESS THAN ABOUT FIVE MICRONS, B. FORMING SAID SHAPED ARTICLES INTO AN UNBONDED SHEET, C. HEATING SAID SHEET MADE IN (B) TO A TEMPERATURE WHEREBY TO INTERFUSE SUBSTANTIALLY ALL OF THE NON-EXTRACTABLE FIBERS THEREIN SUFFICIENT TO UNITE ALL OF THE FIBERS IN THE SHEET, D. EXTRACTING AS A SOLUTION AT LEAST A PORTION OF THE EXTRACTABLE FIBERS FROM SAID SHEET IN AN AMOUNT SUFFICIENT TO HAVE SAID SHEET POSSES MOISTURE VVAPOUR TRANSMISSION, AND E. SEPARATING THE SOLUTION FROM THE SHEET IN AN AMOUNT TO PRODUCE A POROUS SHEET POSSESSING MOISTURE VVAPOUR TRANSMISSION AND CONTAINING THE ULTRAFINE, THERMOFORMABLE, MOLECURLARLY ORIENTED NONEXTRACTABLE FIBERS THEREIN, WHICH NONEXTRACTABLE FIBERS ARE INTERACTABLE BY FUSION AT A PLURALITY OF POINTS WHERE SUCH NONEXTRACTABLE FIBERS INTERCONNECT AND SAID FIBERS DEFINE OPEN AND UNFILLED PORES WHICH ARE INCONNECTED AND EXTEND FROM SURFACE O SURFACE OF SAID SHEET, AND SAID FIBERS HAVE A CROSS-SECTIONAL DIAMETER NORMAL TO THEIR ELONGATED SHAPE END LESS THAN ABOUT 5 MICRONS.