FILTERING MATERIAL FOR FILTER, FILTER PACK AND AIR FILTER UNIT USING THE SAME, AND METHOD FOR PREPARING FILTERING MATERIAL

摘要

A filtering material for a filter which exhibits a PF value of more than 32, the PF value being calculated from the pressure loss and capturing efficiency of the filtering material according to the following formula: PF = [-log(transmittance(%)/100)/pressure loss (Pa)] wherein transmittance(%) = 100 - capturing efficiency (%); and a method for preparing the filtering material which comprises admixing a PTFE fine powder and a liquid lubricating agent in an amount of 380 ml or more at 20 DEG C per 1 kg of the PTFE fine powder, forming the resultant mixture into a tape, stretching the tape to thereby prepare a PTFE porous film, and then laminating with heat an air-permeable support on at least one surface of the PTFE porous film.