Filtering medium for air filters and process for producing the same

摘要

A filtering medium for air filters wherein its surface conditions have been improved, whereby the porous PTFE membrane is not damaged even after pleating, thus appropriately meeting needs for clean space in clean rooms. The filtering medium comprises a porous polytetrafluoroethylene membrane (2) and an air-permeable supporting member (1) which are laminated such that at least one of exposed surfaces comprises a surface of the air-permeable supporting member (1) having a maximum frictional resistance of 25 gf or less. This filtering medium can be obtained by, for example, press bonding the air-permeable supporting member (1) to the porous membrane (2) under heating and then pressing the surface of the air-permeable supporting member (1) to a silicone roll (4) for smoothing.