Patent ID: 8889047

Claim:
A process for making a micro-voided film, comprising: a) compounding into pellets or granules having an at least substantially homogeneous composition comprising, by weight, i) from about 20% to about 60% of high density polyethylene having a molecular weight of at least about 500,000 and a melt index of less than 0.2 dg/min, and ii) from about 40% to about 80% of low aspect ratio filler having a mean particle size from about 1 to about 25 microns, wherein the weight ratio of the low aspect ratio filler to the polyethylene is at least about 0.7, b) extruding the composition into a film having a thickness of from about 50 to about 300 microns, and c) orienting said extruded film using a high stalk, blown film process, the resulting film having a thickness of from about 10 to about 75 microns and a void fraction of from 0.60 to about 0.75 and a density of from about 0.40 to about 0.70 g/cm 3 , wherein the voids are in the interior of the film.