| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat resistant modified polyolefin microporous film excellent in gas permeability rate, compressive resistance, electrolyte impregnation properties, mechanical properties, and a low shrinkage property at high temperature, and having relatively large surface roughness and high productivity, and useful as a separator for enhancing safety of a lithium ion secondary battery; and to provide its manufacturing method.SOLUTION: A polyolefin mixture containing a super high molecular weight polyethylene of 1 to 85 mass%, polyethylene of 10 to 60 mass%, a copolymer resin of 4-methyl-1-pentene andα-olefin having 3 or more carbon atoms of 5 to 30 mass%, polypropylene of 0 to 30 mass%, a block polymer of polypropylene, ethylene and propylene copolymer of 0.5 to 12 mass%, a polyolefin-based elastomer resin of 0.5 to 10 mass%, and an inorganic filler of fine particles if needed are added to obtain a single layer, high productive heat resistant polyolefin microporous film having a shut down temperature around 130°C, and a feature so-called non-melt down which is not broken at a high temperature up to 160°C or higher. Due to a relatively large surface roughness, the heat resistant polyolefin microporous film is excellent in a property balance of a gas permeability rate, compressive resistance, electrolyte impregnation properties, mechanical properties, and a low shrinkage property at high temperature. |
