Patent ID: 10084172

Abstract:
Provided is a nonaqueous electrolyte secondary battery separator excellent in voltage-withstanding property. This nonaqueous electrolyte secondary battery separator has (i) a film thickness of not more than 20 μm, (ii) a peeling strength, measured by a blocking test, of not less than 0.2 N, and (iii) a puncture strength that changes through the blocking test by not more than 15%. The blocking test is carried out by (i) sandwiching, by a jig of 100 mm×100 mm, two 80 mm×80 mm pieces of a separator, (ii) allowing the two 80 mm×80 mm pieces to rest for 30 minutes under a load of 3.5 kg at a temperature of 133° C.±° C., (iii) removing the load, (iv) cooling the two 80 mm×80 mm pieces to room temperature, (vi) cutting out a specimen of 27 mm×80 mm from the two 80 mm×80 mm pieces, and then (vi) measuring a peeling strength of the specimen at 100 mm/min.