Patent ID: 6955865
Filing Date: 2005-10-18
Classification: B32B,C08J,D04H,D06M,H01M,Y02E

Abstract:
1. A battery separator composed of at least two sheets, each of which is a non-woven sheet of polyolefin fibers having opposed major surfaces, wherein some areas of one of the major surfaces of said sheets are hydrophilic as a consequence of a vinyl monomer graft polymerized with the surfaces of the fibers in those areas, said vinyl monomer being one which is capable of reacting with an acid or a base to form a salt directly or indirectly so that the product of the graft polymerization reaction can function as an ion exchange material, while the fibers in other areas of that major surface are free of the graft and, as a consequence, remain hydrophobic, and wherein a major surface of one of the sheets contacts and is substantially coextensive with a major surface of another of the sheets.