LARGE-PORE-DIAMETER POROUS HOLLOW YARN MEMBRANE OF POLYETHYLENE, PRODUCTION THEREOF, AND HYDROPHILIC POROUS HOLLOW YARN MEMBRANE OF POLYETHYLENE

摘要

A large-pore-diameter porous hollow yarn membrane of polyethylene, which has a layered structure wherein slit-shaped micropores surrounded by microfibrils arranged in the longitudinal direction of the filament and knots composed of stacked lamellae interconnect the inner and outer wall surfaces of the hollow filament and which has an average diameter of the micropore of more than 2 µm up to 10 µm as measured with a mercury porosimeter, a porosity of 75 to 95 %, and an air permeation rate of 8 x 10⁵ l/m².hr.0.5 atm or above. This membrane is produced by melt spinning polyethylene and subjecting the obtained unstretched yarn to annealing, cold stretching and hot stretching under specified conditions.