NONWOVEN FILTER MEDIUM Russian patent published in 1998 - IPC

FIELD: filter media. SUBSTANCE: filter medium consists of layers of polyester fibers joint by needle puncturing and woven frame located between layers. Woven frame includes polyester and cotton thread used additionally with diameter not smaller than that of warp threads forming sections whose width equals to or is not smaller than the width of filter seam and arranged in frequency equalling width of filter. Beginning from the edge of filter medium, one of outer layers consists of two layers: web adjoining frame and layer punctured by needle, which are joined by needle puncturing. Ratio of surface densities of all layers of nonwoven filter medium amounts to 1:1.15: 2.0; needle puncturing degree 1:1:2. One of outer layers or both layers are coated with air-permeable melt. EFFECT: higher efficiency. 2 cl, 1 dwg, 2 tbl