| 摘要 |
PROBLEM TO BE SOLVED: To provide a separator for a battery hardly generating cracks even in blanking in the specified shape and dimension by forming a hydrophilic material layer having the specified water content on the surface of a graft copolymer. SOLUTION: A separator for a battery is prepared by graft copolymerizing vinyl monomers capable of giving ion permeability, to a plastic film. A hydrophilic material layer having a water content of 5-30% is formed on at least one side of the graft copolymer. A cellophane is laminated on the other side if necessary. Or cellophane is laminated on each side of the graft copolymer, and the hydrophilic material layer is laminated on at least one of the cellophane. The thickness of the base plastic film is usually made about 5-200μm. The graft ratio of vinyl monomer is usually 10-100%. The hydrophilic material layer is formed with polyvinyl alcohol, carboxymethylcellulose, polyacrylic acid or the like.
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