POLYETHYLENE AND POLYPROPYLENE BLENDS FOR LIQUID PACKAGING FILMS

摘要

There is disclosed a flowable material packaging film comprising at least a resin blend of (a) from about 33 wt% to about 80 wt% of at least one ethylene-C₄ to C₁₀-a-olefin interpolymer having a melt index of from 0.4 to 1.5 g/10min (190°C, 2.15kg), a density of from 0.900 to 0.916 g/cc; and (b) from about 67 wt% to about 20 wt% of at least one heterogeneous interpolymer of propylene with ethylene or ethylene and butene comprising from about 71 mol% to about 86 mol% propylene and from about 29 mol% to about 14 mol% ethylene or ethylene and butene, the interpolymer having an overall weight average molecular weight (M_w) of at least about 400,000, a xylene soluble phase of not less than 30% (wt), with the xylene soluble phase having a M_w of at least about 275,000 and said heterogeneous interpolymer of polypropylene has a density of from 0.875 to 0.91 g/cc; and the film has a Hot Tack Initiation Temperature in the range of from about 100°C to about 140°C and a Hot Tack Strength of not more than about 5 N/inch in the temperature range of about 100^oC to about 150oC, when fabricated at a thickness of about 50 microns and tested using a JB Instrument Hot Tack Tester set at a 0.5 second dwell, 0.2 second delay time, 40 psi seal bar pressure and 250 mm/second peel rate; and the film has a flex crack resistance such that it develops 5 or less pinholes per 300cm² in 10,000 cycles of Gelbo Flex testing as measured according to ASTM F392. The film exhibits flex crack resistance and thus is useful in the manufacture of pouches and bags made from such films. Processes for making such pouches and bags which may include aseptic conditions are also described.