PURPOSE: To obtain a porous polyethylene hollow yarn membrane efficiently holding stable high draw ratio, high in circular opening ratio and large in pore diameter by melt-spinning polyethylene with a nozzle for producing hollow yarn, cold-drawing after annealing and next, hot-drawing under a specific temp. range, draw stages and deformation rate distribution.
CONSTITUTION: The polyethylene is melt-spinned with the nozzle for producing hollow yarn. The usable polyethylene is preferably few in branch, high and at least ≥0.960g/cm3 in density and 0.05-6.0 in M1 value. The obtained undrawn yarn is cold-drawn after annealed and next, hot-drawn. The hot-drawing is executed at 100-130°C with ≥3 hot-draw stages at a deformation rate, larger than that of the preceding stage and ≥1.5 times as much as the average deformation rate in the final deformation rate. Thus, the porous hollow yarn membrane extremely large in fine pore ratio and circular opening ratio is stably, easily and efficiently obtained.
KAMO JUN
UENISHI MICHIHARU
