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

摘要

A method of manufacturing a filter medium that has a PF value that exceeds 32, the PF value calculated from the pressure loss and the collection efficiency of the filter medium according to the following formula: ÄFormula 1Ü PF = Ä-log (permeability (%)/100)/(pressure loss (Pa)Ü x 1000 in which permeability (%) = 100 - collection efficiency (%). In this method, 380 ml or more of a liquid lubricant at 20 DEG C is added per 1 kg of a PTFE fine powder, this compound is processed into a tape shape and elongated to obtain a PTFE porous film, and an air permeable support member is heat laminated to at least one surface of the PTFE porous film.