POROUS HOLLOW YARN MEMBRANE COMPRISING POLYVINYLIDENE FLUORIDE AND PREPARATION THEREOF

摘要

PURPOSE:To prepare a porous hollow yarn membrane comprising groups of pores resulting high void content and having superior characteristics useful for precision filtration membrane or ultra filtration membrane by blending polyvinyl pyrrolidone with polyvinylidene fluoride. CONSTITUTION:The material is a porous hollow yarn membrane comprising a polymer consisting primarily of polyvinylidene fluoride contg. 1-20wt% polyvinyl pyrrolidone blended therewith. The agglomerated body of the polymers forms a network structure having communicating pores. Further, the polyvinylidene fluoride has a II type crystal structure, and the average pore size of pores distributed on the internal and external surfaces of the hollow yarn membrane is 0.05-10mu and the void content is 60-90%. Such membrane is prepared by dissolving the polymers in a solvent to prepare feed liquid having >=100 poise viscosity at 20 deg.C and coagulating the soln. in a coagulating bath after extruding the soln. through a double tubular nozzle.