| 摘要 |
PURPOSE:To provide a biaxially oriented smooth polyester film markedly improved in lubricity and wear resistance, suitable for magnetic tapes, vapor deposition, etc., incorporated with respective specified amounts of two kinds of rutile type titanium dioxide differing in average particle size each other. CONSTITUTION:The objective biaxially oriented film can be obtained from a polyester prepared by incorporating, at any point during the production process of the polyester (pref. having >=80mol% of ethylene terephthalate unit and/or ethylene-2,6-naphthalate unit), pref. after the ester interchange reaction or esterification and before the polycondensation, (A) 0.01-1(pref. 0.1-0.7)wt% of a rutile type titanium dioxide with an average particle size 0.01-0.3(pref. 0.05-0.27)mum and (B) 0.002-0.5(pref. 0.005-0.3)wt% of a second rutile type titanium dioxide with an average particle size 0.31-1(pref. 0.35-0.7)mum. |
