Process for forming a web of synthetic fibers

Claim 1

IN THE PROCESS FOR FORMING A NON-WOVEN, FUSION BONDED, COMPOSITE SHEET FROM SYNTHETIC POLYMER STAPLE FIBER AND FLUID BINDING AGENT, SAID POLYMER BEING SELECTED FROM THE GROUP CONSISTING OF POLY(HEXAMETHYLENE ADIPAMIDE), POLYCAPROAMIDE, POLYETHYLENE TEREPHTLALATE, COPOLYMERS CONTAINING HEXAMETHYLENE ADIPAMIDE AND CAPROAMIDE UNITS, AND COPOLYMERS CONTAINING ETHYLENE TEREPHTHALATE AND ETHYLENE ISOPHTHALATE UNITS, BY CONCOMITANTLY DEPOSITING AN AQUEOUS SLURRY OF A MIXTURE OF SAID STAPLE FIBER AND AT LEAST 10% BY WEIGHT OF FIBRID BINDING AGENT TO FORM A SHEET, DRYING, AND THEREAFTER HEAT CALENDERING THE SHEET TO INCREASE THE BONDING ACTION OF THE FIBRID BINDING AGENT UPON THE STAPLE FIBERS; THE IMPROVEMENT FOR PROVIDING A STRONGER AND MORE UNIFORM SHEET WITHOUT DESTRUCTIVE COALESCENSE OF THE FIBROUS CHARACTER OF THE FIBRID BINDING AGENT AND STAPLE FIBERS WHEREIN SAID CALENDERING IS CONDUCTED (A) UPON SAID SHEET WHILE CONTAINING AN INITIAL AMOUNT OF AT LEAST 10% BY WEIGHT OF WATER AND (B) AT A TEMPERATURE AT LEAST 20* C. BELOW THE MELTING POINT OF THE LOWEST MELTING POLYMERIC COMPONENT IN THE SHEET, AND BETWEEN ABOUT 105* C. AND ABOUT 140*C., AND AT A NIP PRESSURE OF AT LEAST 45 POUNDS PER INCH.