NONWOVEN FILTER MEDIUM Russian patent published in 1997 - IPC

FIELD: materials of industrial application for cleaning hot gases of cement, asphalt-concrete production plants, boiler units and nonferrous metallurgy enterprises. SUBSTANCE: nonwoven filter medium is made at least one outside layer from aromatic polyamide fibers based on polybenzimidazoletherephthalamide or its copolymer and carcass layer of the same fibers fastened by needle-puncturing. Outside layer is made of cut heat-treated threads or their mixture with cut freshly formed threads with ratio of (50-70):30:50. Carcass layer is made of twill weave fabric containing weft and warp in the form of freshly formed threads in the amount of 45-50% of total mass of material. If the carcass material is made of linen weave fabric containing warp and weft from heat-treated threads or staple threads or two warp outside layers and carcass material amounting to 20-25% of the fibrous layer. One layer also may contain 0.005-0.01 mas.% of polyvinyl alcohol. EFFECT: higher efficiency. 3 cl, 1 tbl