Process of forming a microperforated polymeric film for sound absorption

A process of forming a microperforated plastic film having first and second sides and 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 microperforations 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, by applying a flame treatment to the first side of the solidified microperforated plastic film while a metal roll is provided against the second side of the solidified microperforated plastic film, so that each tapered microperforation has a length corresponding to the thickness of the solidified microperforated plastic film.