PURPOSE: To provide a separator having sufficient electrolyte holding ability, decreased battery performance deterioration in long use, and easy production by adding one layer of synthetic fiber nonwoven sheet to two layers of mixed nonwoven sheet comprising mercerized cotton and synthetic fibers.
CONSTITUTION: The first separator paper sheet 2, the second separator paper sheet 3, and the third separator paper sheet are spirally wounded in order on a revolving shaft 1. The first and second separator paper sheets 2 and 3 consist of a nonwoven sheet of 30∼80wt% mercerized cotton and 20∼80wt% synthetic fibers and have a unit weight of 0.2∼0.35g/m2 and a thickness of 0.12±0.04mm. The third separator paper sheet consists of a synthetic resin fiber nonwoven sheet such as one or a mixture of PVA derivative, nylon or polypropylene and has a thickness of 0.12±0.04mm. They are wounded by forming a plurality of line- like adhesive layers 2a, 3a, and 4a mainly comprising vinyl acetate with adhesive coators 5, 6, and 7 and each sheet is bonded to form a three layer cylindrical separator.
NAGASHIMA TSUNEHIKO
YONEYAMA KUNIO
ITOU YUKIHIRO
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