Patent ID: 8512626

Claim:
A process for making a nonwoven web product comprising: flowing at least one polymer fluid stream through at least one bounded polymer passage which ends in at least one opening in a heated wall of at least one of a first and second opposing walls of a slot, wherein each polymer fluid stream extrudes in the form of a film from each said opening to provide an extruded polymer film on a heated wall surface, wherein aggregate polymer throughput of the slot is from about 10 kg/hr/m to about 200 kg/hr/m; combining each extruded polymer film with a pressurized gas stream flowing within a gas passage confined between the first and second opposing walls to fibrillate the polymer film to form fibers comprising sub-micron diameter fibers which exit from an exit end of the gas passage, forming a fibrous web comprising the sub-micron fibers, wherein the sub-micron fibers of said fibrous web have a standard deviation of fiber diameter distribution that is less than about 0.5 micron, and the fibrous web having a shot amount below an average of 10 shot particles per square-millimeter, wherein the shot comprises discrete polymer mass in spherical, ellipsoidal, or combined shapes thereof with a largest dimension ranging from 10 to 500 microns, and the fibrous web has a mean pore diameter of less than about 15 microns.