FINE PARTICLE CAPTURING FILTER MEMBRANE AND PRODUCING METHOD THEREOF, AND POROUS MEMBRANE AND PRODUCING METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a fine particle capturing filter membrane and producing method thereof obtained in formation of communicating hole by anodization, which has an average pore diameter smaller than conventional one.SOLUTION: There is provided fine particle capturing filter membrane obtained in formation of communication pores by anodization of aluminum material, which has a small pore diameter part comprising communication pores opening on one surface of filter membrane, a middle pore diameter part comprising communication pores which are communicated with the communication pores of the small pore diameter part and having a diameter larger than that of the communication pores of the small pore diameter part, and a large pore diameter part comprising communication pores which are communicated with the communication pores of the middle pore diameter part and having a diameter larger than that of the middle pore diameter part. On the small pore diameter part, formed are communication pores having 4 to 20nm pore diameter in average from one surface to a position at least 400nm of the filter membrane. Total film thickness of the filter membrane is 50 μm or less.SELECTED DRAWING: Figure 1