ORGANIC SILICONE FINE PARTICLE, METHOD OF PRODUCING ORGANIC SILICONE FINE PARTICLE, MODIFIED POLYOLEFIN MICROPOROUS FILM, METHOD OF PRODUCING MODIFIED POLYOLEFIN MICROPOROUS FILM AND SEPARATOR FOR NONAQUEOUS ELECTROLYTE ELECTRIC CELL

摘要

PROBLEM TO BE SOLVED: To provide a silicone fine particle suitable for production of a modified polyolefin microporous film especially for separators for lithium ion cells, a modified polyolefin microporous film which uses the silicone fine particle, is reduced in thermal shrinkage and has excellent shutdown properties, and a separator for lithium ion cells.SOLUTION: A solid organic silicone fine particle is composed of a polysiloxane crosslinked structure and formed with a plurality of concave parts in the surface, is fusiform-like as a whole and has an average value of the major axis (D) of the fusiform shape of 0.01-20μm and an average value of the minimum minor axis (R) of the fusiform shape of 0.005-15μm, average values being for 100 fusiform shapes extracted from a scanning electron microscope image of the organic silicone fine particle. A modified polyolefin microporous film, in which a heat-resistant porous layer composed of the organic silicone fine particle and an organic binder is formed on one or both sides of a polyolefin microporous film, and a separator for lithium ion cells using the film are also provided.