PRODUCTION OF FILTER HAVING HIGH COLLECTING EFFICIENCY

摘要

PURPOSE: To provide a method for readily producing a filter having high collecting efficiency and low pressure loss. CONSTITUTION: A water dispersion obtained by uniformly dispersing ultrafine short fibers having <=1 denier and thermally fusible short fibers in the ratio of (90-50):(10-50) is used and made into a sheet on nonwoven fabric of filament so as to have 25g/m<2> to 100g/m<2> weight. A high-pressure water column flow is jetted to the surface of the sheet to entangle the filaments constituting the nonwoven fabric with ultrafine short fibers and the thermally fusible short fibers to form a density-gradient type nonwoven fabric. Then the entangled nonwoven fabric is thermally fused.