Abstract
Polyester non–woven fabrics are widely used as functional filters, and as support materials in the preparation of UF/RO membranes. When used for these purposes, generally, various polymer solutions are coated on the one side surface of the fabrics. However, low viscosity polymer solutions often penetrate through down to the back side of the non-woven fabrics, and often leads to the deterioration of filtration/separation performance. When manufacturing bilayer–type polyester non–woven fabrics, we designed to slightly reduce the pore size of front layer side by mixing fine fibers of a few micrometers in diameter. By using such a surface layer side as coating surface, penetration of polymer solution to the back side of non–woven fabric was remarkably suppressed. Furthermore, we successfully produced an asymmetric polyether sulfone UF membrane with surface pores of less than 30 nm and high water flux of 250 L/m 2 h at 80 kPa. The prevention of the back leakage of polymer solution is derived from the large Laplace pressure in the front layer side. Such non–woven fabrics have advantages in effectively reducing the volume of the coating solution and the weight of the separation membrane, and improving the filtration performance.
