| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat resistant polyolefin microporous film which is excellent in low shrinkability at high temperature as a separator enhancing safety of a lithium ion secondary battery, has a useful gas permeability rate, compression resistance, electrolyte impregnation property and mechanical properties, is relatively high in surface roughness, and is high in productivity; and a manufacturing method therefor.SOLUTION: After drawing a gelatinous sheet molded article obtained by melting and mixing a polyolefin mixture consisting of 5 to 45 mass% of ultrahigh-molecular-weight polyethylene, 10 to 40 mass% of polyethylene, 10 to 50 mass% of a copolymer resin of 4-methyl-1-pentene and an α-olefin having 3 or more carbon atoms, 5 to 30 mass% of polypropylene, 0.1 to 3 mass% of an ethylene-ethylene butylene-ethylene block copolymer, 0.1 to 3 mass% of a block polymer of polypropylene and an ethylene propylene copolymer and 0.1 to 4 mass% of a polyolefin elastomer resin with a plasticizer for making a film, if needed with adding a fine particle inorganic filler, extruding the resultant mixture from a die, and cooling the extruded product, the solvent for making a film is removed and the sheet molded article is heat fixed. There are provided a single layer heat resistant polyolefin microporous film having a shut down temperature around 130°C, a characteristic of non-melt down without breaking at high temperature by 160°C or more and low shrinkability at high temperature, and excellent in property balance of a gas permeability rate, compression resistance, an electrolyte impregnation property, mechanical properties and the like as surface roughness is relatively large; and a manufacturing method therefor.SELECTED DRAWING: None |
