| 摘要 |
PURPOSE:To obtain the title highly pure film excellent in open-cellular quality of micropores, cost, etc., by melt-molding a mixture of a PP with a specified organic solid and extracting the organic solid from the molding. CONSTITUTION:A mixture is obtained by mixing 100pts.vol. PP (A) of an intrinsic viscosity of 2.1-3.3dl/g and an isotactic index >=97% with 80-180pts.vol. extractable solid (B) (e.g., dicyclohexyl phthalate or triphenylene phosphate) having an m.p. of 35-100 deg.C, an MW of 200-1,000 and a molecular structure having a polarizable or polar group. This mixture is pelletized by melt kneading with, e.g., a twin-screw extruder and cast with an extruder at a draft ratio >=4 and 60-110 deg.C, and the obtained film or the like is treated with an extracting solvent, such as trichloromethane, methyl ethyl ketone or toluene, which is a good solvent for component B but is a poor solvent for PP to extract component B and dried to obtain the title film having a porosity of 40-90% and an average pore diameter of 0.05-5mu and being excellent in open-cellular quality in the direction of thickness.
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