| 摘要 |
PURPOSE:To prepare a filter having a very low pressure loss and superb collecting performance compared with the existing HEPA filter by providing an electret non-woven cloth layer of dense structure on the dust collecting face and a non-woven cloth of rough structure on the downstream side. CONSTITUTION:An electret non-woven cloth 4 of dense structure is provided on the dust collecting face by the relationship of fiber filling rate Y and fiber medium diameter X which satisfies formulas I-IV. The non-woven cloth is preferably of melt-blow method having a 0.2-30mum fiber diameter distribution. Electret characteristics should be more than 1.4X10<-10> coulomb/cm<2> of ther mostimulating depolarized charge amount. Weight per unit area is around 10-180g/m<2>. Collecting performance is superbly enhanced by providing in paral lel the electret non-woven cloth layer and the non-woven cloth layer 5 of rough structure. The non-woven cloth of rough structure having a low pressure loss and high reinforcing support effect should be selected. |
