Patent ID: 7731878

Claim:
A process of forming a microperforated plastic film having a thickness, comprising: providing a tool having multiple tapered posts, each post having a tapered shape; bringing molten extrudate into contact with the tool so that the molten extrudate conforms to the tapered shape of each tapered post; solidifying the molten extrudate into a solidified microperforated plastic film having a plurality of tapered microperforations, each tapered microperforation having a tapered shape imparted by a tapered post and each tapered microperforation having a narrowest diameter of 20 mils or less and less than the film thickness and a widest diameter greater than the narrowest diameter wherein the widest diameter is about 125% or more of the narrowest diameter; and displacing any skins formed over each tapered microperforation after solidifying the molten extrudate, so that each tapered microperforation has a length corresponding to the thickness of the solidified microperforated plastic film.