Process for producing a polypropylene fibrous product bonded with polyethylene

Claim 1

A PROCESS FOR THE PRODUCTION OF A POLYPROPYLENE FIRBROUS PRODUCT BONDED AT THE INTERSECTS OF THE POLYPROPYLENE FIBERS THEREOF WITH POLYETHYLENE COMPRISING. (1) MIXING LOW MOLECULAR WEIGHT POLYETHYLENE FIBERS HAVING A LOW VISCOSITY AT ELEVATED TEMPERATURES IN THE NEIGHBORHOOD OF 8,000 CENTIPOISES AT 20*C. ABOVE THEIR ASTM D36-26 RING AND BALL SOFTENING POINTS, A MELTING POINT CLOSE TO 160*C. AND A DENIER PER FILAMENT OF 2 TO 10 WITH POLYPROPYLENE FIBERS HAVING A DENIER PER FILAMENT OF 2 TO 16, A STAPLE LENGTH OF 1 TO 10 INCHES AND A MELTING POINT HIGHER THAN THE MELTING POINT OF SAID POLYETHYLENE FIBERS TO MAKE A BLEND CONTAINING FROM 60 TO 80 PERCENT BY WEIGHT POLYPROPYLENE FIBERS, BALANCE POLYETHYLENE FIBERS, (2) FORMING THE BLEND OBTAINED BY SAID MIXING INTO A CARD WEB, (3) SUBJECTING SAID CARD WEB TO STEAM UNDER MODERATE PRESSURE FOR ABOUT 1 TO 5 MINUTES, (4) MELTING THE POLYETHYLENE FIBERS, (5) FLOWING THE MELTED POLYETHYLENE TO THE INTERSECTS OF THE POLYPROPYLENE FIBERS, (6) BONDING THE POLYPROPYLENE FIBERS AT THE INTERSECTS WITH THE MELTED POLYETHYLENE, (7) REMOVING THE CARD WEB FROM SUBJECTION TO THE STEAM TO COMPLETE THE BONDING OF THE POLYPROPYLENE BY POLYETHYLENE AT THE INTERSECTS, (8) AND COMPRESSING SUFFICIENTLY DURING THE BONDING OPERATION TO PRODUCE A COHERENT, WELL BONDED MASS OF POLYPROPYLENE FIBERS HAVING A HIGH STRENGTH IN ALL DIRECTIONS, A DENSITY OF 1 OUNCE PER SQUARE YARD TO 4 OUNCES PER SQUARE YARD AT 1/2-INCH THICKNESS, THE POLYPROPYLENE FIBERS IN SAID WELL BONDED MAS BEING ARRANGED IN A RANDOM DISTRIBUTION WITH BONDS CLEARLY SHOWN AT A LARGE NUMBER OF THEIR INTERSECTS UPON MICROSCOPIC EXAMINATION WHILE RETAINING THEIR IDENTIFY AS INDIVIDUAL FIBERS.