Filter unit and dust-proof mask therewith
AssigneeMine Safety Appliances Company
InventorsTomoaki Kanno, Kunio Yamada, Hirohisa Umezaki
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Abstract
The present invention provides a filter containing a filter material folded into a chrysanthemum shape. While such a filter can be made of an electret fiber nonwoven fabric or a fiberglass nonwoven fabric, preferably it is made of a polytetrafluoroethylene porous film that is extended lengthwise and widthwise such that the overall area is extended by more than fifty-fold.
Claims8
A folded filter unit comprising a biaxially expanded polytetrafluoroethylene porous film such that the extended area scaling factor is at least 45 and wherein the film has a fiber diameter of 0.05 to 0.2 μm, an average pore diameter of 0.1 to 0.5 μm, a thickness of 0.1 to 20 μm, and a porosity of 40 to 97%.
A folded filter unit comprising a biaxially expanded polytetrafluoroethylene porous film such that the extended area scaling factor is at least 100 and wherein the film has a fiber diameter of 0.05 to 0.2 μm, an average pore diameter of 0.1 to 0.5 μm, a thickness of 0.1 to 20 μm, and a porosity of 40 to 97%.
Dependencies are inferred from the claim text.