POROUS THERMOPLASTIC FLUOROPLASTIC BODY, ITS PRODUCTION AND PRODUCTION OF BATTERY

摘要

PROBLEM TO BE SOLVED: To obtain a porous thermoplastic fluoroplastic body being lightweight and having improved chemical resistance, mechanical strength and mass transfer by melt-extruding a thermoplastic fluoroplastic containing vinylidene fluoride and cold-stretching the extrudate to form flat pores therein. SOLUTION: A thermoplastic fluoroplastic containing at least 90wt.% vinylidene fluoride and having and MFR of 0.1-500g/10min is mole-extruded into a sheet or a hollow body, and this sheet or body is heat-treated at 70-155 deg.C to increase its degree of crystallinity to 40% or above. It is then cold-stretched at a draw ratio of 1.1-6 to obtain a porous thermoplastic fluoroplastic body having a large number of flat pores having a width of 0.1-3μm and a length of 0.5-20μm and an apparent specific gravity of 1.7 or below.