Preparation and properties of hollow segmented-pie microfiber/waterborne polyurethane synthetic leather

The waterborne polyurethane (WPU) microfiber synthetic leather(PET-PA6/WPU)using segmented-pie microfiber nonwoven as the base and WPU membrane as the polymer coating was prepared through dry transfer-coating method. The method realized the greening preparation of microfiber synthetic leather. The structure and performance of PET-PA6 hollow segmented-pie microfiber nonwoven were firstly investigaed by FESEM, and then the effect of foaming ratio on the structure and performance of WPU membranes was systematically studied, finally the structure, air permeability, water vapor permeability and physical mechanical properties of PET-PA6/WPU were analyzed. The results show that the fiber diameter size of PET-PA6 hollow segmented-pie microfiber nonwoven is between 2.2-5.5 μm, and its performance meets the using demand of textiles-nonwoven for synthetic leather. When the foaming ratio is 100%, the structure of the obtained WPU membrane is dense, and its air permeability and water vapor permeability are 14.72 L/(m²·s) and 3 686.84 g/(m²·24 h), respectively. The WPU membrane exhibites connecting bubble hole and porous surface, and its mean pore size, air permeability and water vapor permeability increase with the increase of foaming ratio. When the foaming ratio is 250%, the air permeability and water vapor permeability are 169.43 L/(m²·s) and 5 209.09 g/(m²·24 h), respectively. The PET-PA6/WPU microfiber synthetic leather is in a three-layer configuration, including fabric layer, foam layer and surface layer. The air permeability of PET-PA6/WPU leather is 0.45 L/(m²·s), tensile strength of perpendicular and parallel are 138.40 N and 96.60 N, elongation at break of perpendicular and parallel are 72.70% and 101.80%, tear strength of perpendicular and parallel are 63.20 N and 88.20 N, peeling strength of before hydrolyze and after hydrolyze are 15.86 N and 15.61 N, and creasy recovery angle of perpendicular and parallel are 149.30° and 151.80°, which are better than knitting synthetic leather and real leather. The water vapor permeability of PET-PA6/WPU synthetic leather reaches 1 673.8 g/(m²·24 h) closing to real leather.