| 摘要 |
PROBLEM TO BE SOLVED: To produce a polyester film base for a photographic film satisfying having absolute minimum in character indispensable for the base, that is, cleavage resistance and little unevenness in thickness. SOLUTION: When an unoriented film 61 is drawn vertically and horizontally in plural stages with a drawing apparatus consisting of heating rolls 31, 34 and cooling rolls 32, 35 to produce a biaxially oriented polyester film, the heating rolls 31, 34 and the cooling rolls 32, 35 are arranged at 5-40 mm intervals and the film 61 is drawn vertically in the 1st stage, cooled to a temperature below the glass transition temperature, reheated and drawn in the 2nd stage. |
