Processing conditions of abrasion and heat resistance for hybrid needle-punched nonwoven bag filters

Two nonwoven fabrics and a polyester grid (C) were laminated together to form nonwoven composite for use as filter bags. One nonwoven composite (A) was with polyester fibers of various levels of fineness and with low melting-temperature (Tm) polyester fibers on the surface layer; the other (B) was made of 2.22 dtex polyester fibers. The nonwoven composites were laminated together with the grid in an A/B/C/B order to form a sandwich structure with a constant basic weight of 500 g/m2, thermal calendared and needle punched to bond the layers in the fabricated composite nonwoven fabrics.The physical properties of the filter at different conditions are discussed. The specify type results demonstrated that the filter's heat shrinkage ratio was less than 2%, and its shrinkage ratio in the longitudinal direction (also called machine direction (MD)) was lower than that in the transverse direction (also called cross-machine direction (CD)) perpendicular to the MD when the thermal pressing temperature was less than 130 °C. The abrasion resistance for the surface layers of the nonwoven fabrics increased when basic weight and thickness increased. When the basic weight of the surface layers of nonwoven fabrics was increased from 50 to 100 g/m2, the abrasion resistance increased from 10 to 70%. When the filter thickness was 1.8 mm, the degree of abrasion resistance increased by roughly 20–30% over that for the filter of 1.2 mm thick.