Patent ID: 7435761
Filing Date: 2008-10-14
Classification: B01D,B29C,B29K,C08J,C08L,H01M,Y02E

Abstract:
1. A method of producing a microporous polyethylene film without the use of irradiation for the purpose of crosslinking, comprising: (a) melt-extruding a resin mixture to form a sheet, the resin mixture comprising: (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; and (c) extracting the diluent from the film, and heat-setting the resulting film, wherein, the microporous polyethylene film has gels of 50 or less per a thickness of 200 μm and area of 2000 cm