FILTER MEDIUM FOR AIR FILTER, AIR FILTER UNIT, AND METHOD FOR PRODUCING FILTER MEDIUM FOR AIR FILTER

摘要

A filter medium for an air filter unit for collecting dust from an airflow comprising: a pre-collection layer for collecting a part of the dust in the airflow; a principal collection layer that includes a porous polytetrafluoroethylene film and is positioned on a downstream side of the air flow relative to the pre-collection layer to collect dust that passes through the pre-collection layer; and a air-permeable cover layer that is positioned in the outermost surface layer on an upstream side of the air flow to allow dust in the air flow to pass therethrough and to suppress deformation of the surface of the filter medium for an air filter caused by pressing force from an outside.