Patent ID: 7947752
Filing Date: 2011-05-24
Classification: C08J,C08L,H01M,Y02E

Abstract:
1. A method of producing a microporous high density polyethylene film, comprising: (a) melt-extruding a composition, including 20-50 wt % high density polyethylene with a weight average molecular weight of 2×10 (b) stretching the sheet at a temperature range, where 30-80 wt % of a crystalline portion of the sheet is molten, according to a tenter-type simultaneous stretching manner such that stretching ratios are 3 times or more in machine and transverse directions, respectively and a total stretching ratio is 25-50 times to produce a film; (c) extracting the diluent from the film; and (d) heat-setting the resulting film at a temperature range where 10-30 wt % of a crystalline portion of the film is molten, the microporous high density polyethylene film having tensile strengths of 1,100 kg/cm