| 摘要 |
The invention aims at providing an air filter which is improved in the tight adhesion between an ePTFE membrane and an air-permeable substrate without impairing the mechanical strength and air permeability of the substrate. An air filter produced by laminating an air-permeable substrate (1) having a region wherein fibers different in fiber diameter are entangled and a porous polytetrafluoroethylene membrane (2), wherein the mean fiber diameter of the membrane-side face of the substrate (1) is smaller than that of the back of the substrate (1). |
