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AssigneeSeplast
InventorBernard Thiebault
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The process of the invention consists in smoothing the or each fluffy surface of the layer by exerting a slight friction under low pressure so that the projecting fibers are flattened on the subjacent fibrous mass without the latter being compressed, the friction being exerted at a softening temperature such that the superficial fibers are welded together to form a skin or porous glaze. The smoothing is preferably effected by means of a metal mass whose temperature is between 115.degree. and 150.degree. C. This process may be applied to the outer face of a filtering breathing mask constituted by an envelope made of this fibrous material covering a relatively rigid porous shell for protection of the skin; it may also be applied to at least one of the faces of filtering layers equipping filters of any type.
A process for superficially treating a highly aerated, fluffy, fibrous electret, air filtering fabric layer having fibers projecting above a subjacent mass, which comprises smoothing at least one fluffy surface of the layer by exerting a light friction under low pressure to flatten the projected fibers on the subjacent fiber mass without substantial compression of said mass, and at a softening temperature to weld the superficial fibers together and to form a skin or pourous glaze which will be unclogged and by a surface effect adds to the filtering power of the electrostatic filtering layer without reducing the gaseous flow passing through the layer.
Dependencies are inferred from the claim text.