Method of producing a foam fibrillated web

Claim 1

A process of producing a foam fibrillated fibrous web comprising heating a blend of from 75 to 98 weight percent as based on said blend of isotactic polypropylene having a melt index below 30 and from 2 to 25 weight percent as based on said blend of ethylene-vinyl acetate copolymer containing from 60 to 98 weight percent ethylene and from 2 to 40 weight percent vinyl acetate and having a melt index from 1 to 400 in an extruder to from 175° to 260°C whereby a molten blend is formed, extruding said molten blend and from 0.1 to 20 percent by weight as based on said blend of a material which is gaseous under the extrusion conditions used mixed with said molten blend from a die into a zone of reduced pressure to produce an extrudate, quenching said extrudate to a temperature below about 150°C while withdrawing said extrudate from said die by a first linear take-up means at a linear rate of from 2 to 25 times the linear rate at which said blend reaches the lips of said die whereby the foam cells forming are ruptured and a foam fibrillated web is formed, and stretching said foam fibrillated web from 1.5 to 10 times in the machine direction at a temperature of from about 90°C to about 150°C to increase the strength thereof.