Patent ID: 9242201
Filing Date: 2016-01-26
CPC Classification: B01D,B32B

Claim Text:
1. A filter medium for an air filter collecting dust in an air flow, the filter medium comprising: a principal collection layer including a porous polytetrafluoroethylene film, a pre-collection layer located at an upstream side of the air flow relative to the principal collection layer, the pre-collection layer being configured to collect a part of dust in the air flow; and an air-permeable cover layer positioned as an outermost layer of the filter medium at the upstream side of the air flow, the air-permeable cover layer allowing dust in the air flow to pass therethrough, and the air-permeable cover layer suppressing deformation of a surface of the filter medium by pressing force from outside, a surface of the filter medium being provided with a plurality of embossed projections, the filter medium being maintained in a zigzag shape obtained by folding so as to create mountain folds and valley folds, and the plurality of embossed projections being provided between each adjacent mountain fold and valley fold.