摘要 |
The invention aims at providing an air filter which is improved in the tight adhesion between an ePTFE membrane and a permeable support material without impairing the mechanical strength and permeability of the support material. An air filter produced by laminating a permeable support material (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 support material (1) is smaller than that of the back of the support material (1). |