POROUS POLYIMIDE MEMBRANE AND PROCESS FOR PRODUCTION OF SAME

摘要

A porous polyimide membrane which has a three-layer structure composed of two surface layers (a) and (b) and a macro-void layer sandwiched therebetween.  The macro-void layer comprises both partition walls joined to the surface layers (a) and (b) and multiple macro-voids enclosed by the partition walls and the surface layers (a) and (b), with the mean void diameter of said macro-voids in the membrane-plane direction being 10 to 500µm.  The partition walls and the surface layers (a) and (b) each have a thickness of 0.1 to 50µm and each contain multiple pores having a mean pore diameter of 0.01 to 5µm.  The pores interconnect with each other and with the micro-voids.  The total thickness of the membrane is 5 to 500µm and the void content thereof is 70 to 95%.