| 摘要 |
PURPOSE:To prepare the title article having a fine pore structure, excellent permeability, and high dimensional stability by subjecting an unsintered molded article obtd. by paste extrusion of a fine polytetrafluoroethylene powder to a specific thermal treatment and then orienting the article. CONSTITUTION:An unsintered molded article obtd. by paste extrusion of a fine polytetrafluoroethylene powder (pref. having a number-average mol.wt. of 2000000-20000000) is thermally treated and sintered in such a way that at least one peak appears between the endothermic peak of the powder and that of the sintered article on a crystal fusion diagram by scanning differential calorimetry. Then the article is oriented at least monoaxially to give the title article, which has a fine pore structure, high permeability (high pore content), high heat resistance (low thermal shrinkage), and high dimensional stability (low solvent shrinkage), and hence is useful for a precision filter, high-functional membrane carrier, air filter, etc. |
