Heat-resistant microporous film and battery separator

摘要

A heat-resistant microporous film and a battery separator are provided, which each include a substrate formed by using a porous film and include a heat-resistant layer formed on at least one surface of the substrate so as to contain a heat-resistant resin and heat-resistant particles, and in which a protrusion is formed on a surface of the heat-resistant layer in number not exceeding 60 per surface area of 0.0418 mm2 and has an area not exceeding 500 μm2 per surface area of 0.0418 mm2 in a direction normal to a surface of the heat-resistant layer, the protrusion being formed as a result of aggregation of the heat-resistant particles and having a height of at least twice the average particle size of the heat-resistant particles with reference to the height average surface of the heat-resistant layer.

主权项

1. A heat-resistant microporous film comprising:
a substrate comprising a porous film; and a heat-resistant layer formed on at least one surface of the substrate, the heat-resistant layer containing a heat-resistant resin and heat-resistant particles, wherein: at least one protrusion is formed on a surface of the heat-resistant layer, a total number of protrusions not exceeding 60 per surface area of 0.0418 mm2, a total area of the protrusions is 500 μm2 or less per surface area of 0.0418 mm2 in a direction normal to a surface of the heat-resistant layer, each protrusion being formed as a result of aggregation of the heat-resistant particles, and a height of each protrusion is at least twice an average particle size of the heat-resistant particles with reference to a height average surface of the heat-resistant layer.