Filtration properties of staple fibre thermo-bonded nonwoven fabrics

Thermal bonded polyester staple fibre nonwoven fabrics have been produced, considering different proportions of binder fibres, directions of web laid as variables, and bonding time and bonding temperature as constant. The influence of process variables on fabric properties, such as bursting strength, air permeability, bubble point diameter, mean flow pore diameter and filtration efficiency with three different particle (1, 0.5, and 0.3µ) along with the overall filtration efficiency have been tested and the results are compared with spun laced nonwoven fabrics. The fibres are oriented in cross and parallel directions, this arrangement of fibres leads to increase in bursting strength. The trend in air permeability of cross-laid web fabrics is found similar to spunlaced fabrics. The pore sizes of the thermal bonded fabrics have been minimized by laying the web in cross direction and increasing the binder fibre proportion; it has minimum variation with spunlaced fabrics. Aerosols of different particles are fed to the upstream of the filters with the face velocity of 16.6 cm/s which is then maintained as constant. The maximum filtration efficiency achieved is found to be 93.13% which is around 13% higher than that of the spunlaced fabric. For 80g/m2 fabrics with 0.3µ particles, the filtration efficiency of spun laced fabric is only 38% which is around one and a half time lesser than 80 g/m2 of thermal bonded fabric; 90g/m2 fabrics show equal and better properties than 100g/m2 fabrics