| 摘要 |
<p>A wet type nonwoven fabric for a separator of a cell, comprising 20 to 95 wt.% short fibers composed of single fibers of 20 νm or thinner of a thermoplastic polymer, and hot-melt short fibers having a melting point higher by 20 °C than the thermoplastic short fibers. The two types of fibers are entangled three-dimensionally, the mean distance of the entanglement points of the short fibers is not greater than 300 νm, and at least a part of the hot-melt short fibers is thermally fused so as to mutually bond the short fibers and to fix the nonwoven fabric structure. This nonwoven fabric has a basic weight of 10 to 350 g/m2, a thickness of 30 to 1,000 νm and an apparent density of 0.26 to 0.7 g/cm3, and it is superior in uniformity and mechanical strength. Because of its liquid retention property and liquid absorbing speed required for a separator material of a cell, the fiber is a useful material for the production of a secondary cell having excellent overcharge characteristics and cycle characteristics. Incidentally, the wet type nonwoven fabric of the present invention can be obtained by water flow entanglement processing of a web prepared by wet process by using the short fiber materials described above which has a ratio (L/D) of a fiber length (L) to a single fiber diameter (D) of 0.5 to 2.0x103, without leaving the traces of the water column.</p> |
