Patent ID: 6953510
Filing Date: 2005-10-11
Classification: B29C,B29K,B32B

Abstract:
1. A method of making a microporous breathable film comprising the steps of: selecting a film forming a polyolefin precursor, said polyolefin precursor having polypropylene as a majority component; blending said film forming polyolefin precursor with a filler which is a rigid material having a low affinity for the polyolefin precursor and a lower elasticity than the polyolefin precursor, and having a non-smooth hydrophobic surface such that the filler is about 30% to about 70% of the combined weight of the filler and the polyolefin precursor; combining said polyolefin precursor/filler blend with an additive selected from a group including a plastomer, an elastomer, a styrenic block copolymer or a combination thereof, wherein said additive has a melt flow index ranging from about 0.8 to about 40 g/10 minutes; and stretching the combination of said blended polyolefin/filler blend with an additive to form a microporous breathable film having a dart impact strength in the range of from about 100 to about 300 grams; wherein said film has a WVTR in the range of from about 1000 to about 10,000 g/m2/24 hr, and wherein said film has an MD or TD elongation in the range of from about 150% to about 550%.