| 摘要 |
PURPOSE:To obtain the titled polyester film having lowered apparent specific gravity, by compounding an aromatic polyester with a specific crystalline polypropylene homopolymer and a surfactant, extruding the composition in the form of a sheet and drawing the sheet to form a film. CONSTITUTION:A film having fine closed cells can be produced by (1) compounding (A) an aromatic polyester, preferably polyethylene 2,6-naphthalate, etc., having an intrinsic viscosity of 0.5-1.2, preferably 0.55-0.85 with (B) 3-20wt.% crystalline polypropylene homopolymer containing >=95mol% propylene unit and having a melt flow index of 0.2-120, preferably 0.5-50 and (C) 0.001-3%, preferably 0.005-1% surfactant, preferably nonionic surfactant, especially silicon-based surfactant, (2) extrusion molding the obtained composition in the form of a sheet and (3) drawing the sheet along at least one direction. |
