Polyvinylidene fluoride/polyvinyl chloride blended hollow fiber membrane and process for preparing same

The invention discloses a method for preparing the hollow fiber film of mixed polyvinylidene fluoride and polyvinyl chloride. The component of the film is polyvinylidene fluoride, polyvinyl chloride and additive PVP. Said hollow film has four-layers binode unsymmetrical structure, and the four layers is outer compact stratum, finger-hole supporting layer, spongiostrome and inner compact stratum, wherein the spongiostrome has plenty of holes in it. Said invention applies the rational mass ratio of the solution and the additive, which makes the film has inside and outside double-skin construction and has five layers of binode unsymmetrical. The method can keep the viscosity of the spinning fluid properly, and can improve the permeability of water and the mechanical intensity at the same time.