FIELD: process engineering.
SUBSTANCE: invention relates to production of microporous polyolefin membranes to be sued in storage battery separators. Membrane is made from polyethylene resin, the main component, and features (a) cutout temperature of 135°C or lower whereat air permeability measured at heating at temperature rise rate of 5°C/minute reaches 1×105 s/100 cm3, (b) air permeability variation degree of 1×104 a/100 cm3/°C or higher that makes gradient of curve describing dependence of said air permeability upon temperature at air permeability of 1×104 s/100 cm3, and (c) fusion temperature of 150°C or higher whereat air permeability measured at further increase of temperature after reaching cutout temperature, again, equals 1×105 s/100 cm3.
EFFECT: well-balances air permeability variation after cutout start, low cutout temperature and better fusion properties.
11 cl, 7 dwg, 2 tbl, 13 ex
