| Bicomponent spunbond-spunlace is a nonwoven technology which combines bicomponent spunbond process with spunlace process. The PA6 and PET resin are melted in the extruder, and the melt is filtered and metered before being extruded into filaments from the spinneret. After being cooled and drawn, the filaments sucked on the belt form the fiber web, and then the fiber web form the bicomponent spunbond-spunlace nonwoven materials by hydrotangling.Spunbond-spunlace process was highly efficient due to the one step polymer-to-nonwoven fabrication process. The bicomponent nonwoven materials with excellent properties are widely applied in filtration, artificial leather wiper and other fields. Although there are two enterprises realization the production of bicomponent spunbond-spunlace nonwoven materials, but the research of process still in initial stage.In this paper, the hollow bicomponent fibers and bicomponent superfine fibers nonwoven materials are prepared using PET and PA6 rwwesins by spunbond-spunlace equipment. First of all, the melting flow index, thermal stability and rheological properties of chips are studied. In addition, we also investigate the influence of drawing airflow pressure of spunbond process on thermal properties, crystallization properties, orientation structure, surface morphology and tensile properties of the bicomponent fibers. Finally, the influence of surface density, PET/PA6 ratio and hydroentangling energy on surface morphology, thickness, pore size distribution,filtration performance, tensile properties and tear properties of bicomponent superfine fibers nonwoven materials. The results are given as follow:1. The melting flow index of PET and PA6 increase with the increase of temperature, but the flow property of PET is superior than that of PA6. PET and PA6 melt are both pseudo plastic fluid, and their apparent viscosity increase with the increase of shear rate. At the same sheer rate,the apparent viscosity decreases with the increase of temperature. At low shear rate, the shear rates of PET and PA6 melt decrease rapidly with the increase of shear rate. When the shear rate increases to a certain extent, the variation of melt apparent viscosity decreases with the increase of the shear rate.2. With increasing of drawing pressure, the melting point of PET component increases, but the melting point of PA6 component changes little. When drawing pressure is greater than 1.5Bar, the melting curves of PET component appeared two consecutive melting peaks, fold-chain and extended-chain coexisting. With increasing of drawing pressure, both crystallinity and orientation degrees of composite fiber increased gradually. According to the figures of fibers cross-section and surface, it is easy find that there are 16 segments in the component fiber cross section with alternating 8 segments PET and 8 segments PA6. The hollow pie wedge bicomponent fiber has a distinct interface between the two polymers due to poor compatibility.When drawing pressure increases, the tensile strength of bicomponent fibers increases gradually,but their average diameter, linear density and elongation decrease.3. With increasing of the surface density, the thickness of nonwovens increases, but the average pore size decreases. Filtration efficiency of bicomponent also increases with the increase of the surface density, meanwhile the filtration resistance increases gradually. When the surface density increases, the transverse and longitudinal tensile strength of nonwovens increase, and breaking elongation and tear strength also increase. What’s more, the longitudinal tensile strength is greater than the transverse tensile strength, and longitudinal tear strength is less than the transverse tear strength.4. When PET/PA6 configuration of bicomponent nonwovens are 50/50, 60/40 and 70/30,the fibers of nonwoven surface were mostly split into superfine fibers, while the intermediate fibers stayed complete hollow structure. The average pore size, tensile strength and elongation of the nonwoven materials are the largest when the PET/PA6 configuration is 50/50, but the filtration efficiency and filtration resistance are the smallest. The average pore size, tensile strength and elongation of bicomponent nonwovens decrease with increasing of the PET content,while the filtration efficiency and filtration resistance increase.5. With increasing of hydroentangling energy, thickness and average pore diameter of nonwoven materials decrease, but filtration efficiency and filtration resistance increase, while the transverse and longitudinal tensile strength, breaking elongation and tear strength of nonwoven materials increase at first and then decreased. When the hydroentangling energy was 24.46J/g,the tensile and tearing properties of bicomponent nonwovens were the best. |
