Patent ID: 6291105
Filing Date: 2001-09-18
Classification: H01M,Y02E,Y02P

Abstract:
A battery separator, comprising a non-woven fabric that comprises a mixture of staple fibers that are entangled and partially bonded to each other, the mixture of staple fibers comprising 15-75 weight % of ultra fine fibers having fineness of 0.1 to 0.5 denier split from splittable bi-component fibers comprising polyolefin polymer, component A, and polyolefin polymer containing oxygen atoms, component B, arranged adjacent to each other, 20-60 weight % of thermal bonding fibers and 0-50 weight % of single component synthetic fibers that have a greater fineness than that of the ultra fine fibers having fineness of 0.1 to 0.5 denier, wherein a surface of the non-woven fabric is modified by corona discharge, and functional groups are present in the fibers on the surface of the non-woven fabric and carbon atoms have said functional groups or bonds in the following ranges according to an analysis by using an electron spectroscopy of elemental composition on the non-woven fabric:1. aldehyde groups (--CHO) or aldehyde bonds (--C.sup.+ H--O.sup.-): 10-40%2. carbonyl groups or carbonyl bonds (--CO--): 3-30%3. carboxyl groups (--COO.sup.-) or ester bonds (--COO--): 0-15%4. residual carbon atoms: 15-87%;wherein the thermal bonding fibers are sheath-core bi-component fibers having a sheath of high-density polyethylene and a core of polypropylene, and wherein a longitudinal elongation of the battery separator is no more than 20%.