Multilayer nonwoven fabrics for filtration of micron and submicron particles

Abstract

Nonwoven fabrics are widely used for filtration of particles due to higher air permeability, better filtration performance and no slippage of yarn than woven filter media.2–5 Due to the random fibrous web of the nonwoven fabric, effective filtration was achieved. The filtration performance of the nonwoven fabric was influenced by thickness of the fabric, areal density and pore size. A majority of nonwoven fabrics are spun bonded and in general, the mechanically bonded nonwoven fabrics are thicker, with larger pore opening than thermal bonded nonwoven fabric. Needle punched nonwoven fabrics are used to filter coarse particles such as separations of coal, dust and chemical particles. Other nonwoven based on melt blown, spun bond and needle felting techniques are used in disposable cartridge, membrane and for food filtration. The mean flow pore diameter was achieved as for non-thermal bonded fabrics as 1-500 microns and it was reduced as 10-15 micron by thermal calendaring. Thermal bonded staple fibre nonwoven fabrics were developed for depth filtration and its performance was better than meltblown nonwoven fabric.6