Filter for gases or liq. - where substrate fabric or felt is covered by grains of thermoplastic polymer bonded to fabric by heating

摘要

Filter consists of a surface layer (I) of grains of thermoplastic material bonded to a textile substrate. Layer (I) pref. consists of several layers (Ia)-(Ic) of grains which decrease in size away from the substrate, i.e. the layer (Ia) next to substrate has the largest grains; and layer (I) may contain grains of other materials which are not thermoplastic. Substrate is pref. a felt contg. fibres bonded to grains (I); a fabric which may be fluffy or tufted; or a linen made partly or completely of monofilaments. The filter is pref. made by spreading grains (I) on a textile strip and then feeding the latter through a furnace leading to cold calendering rolls. Grains prevent the fibres in substrate from being blocked by the substances filtered out of gases or liqs.