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Abstract

Provided is a microporous polyolefin multilayer film which may be used as a separator for a battery, and a method for preparing the same. At least one layer of the microporous polyolefin multilayer film contains 90˜100 wt % of polyethylene having a melting temperature of 130˜140° C. and at least the other layer has 20 wt % or more of a heat resistant resin and 80 wt % or less of a filler selected from the group consisting of an organic filler, an inorganic filler and a mixture thereof. The heat resistant resin is preferably a semi crystalline polymer or an amorphous polymer. Preferably, the semi crystalline polymer has a degree of crystallinity of 10-45% or a heat of fusion for melting of 20˜90 J/g and has a melting temperature of 145˜250° C. and a glass transition temperature of −100˜90° C. Also, preferably, the amorphous polymer has no crystal and has a glass transition temperature of 90˜120° C.

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First Claim