| 摘要 |
PURPOSE:To obtain a biaxially oriented polyester film roll generating no meandering or lateral shift in a film processing process and excellent in processing stability by specifying the difference of TMA elongation between both sides. CONSTITUTION:In a biaxially oriented polyester film roll, TMA elongation at 100 deg.C is 0.001% or more and the difference of TMA elongation between both sides at 100 deg.C is set to 0.1% or less. TMA elongation is measured by reading dimensional elongation at a time when a sample with width of 5mm and length of 20mm to which load of 30g is applied is heated from the normal temp. at a temp. rising speed of 30 deg.C/min to reach 100 deg.C. With respect to the difference of TMA elongation, TMA elongations of both samples taken from the parts within 50mm from both ends of the film roll are measured and the difference between both measured values is calculated. Therefore, the edge temp. of the film heat-treated after stretching and grasped by a clip is set to 140 deg.C and the temp. of the film from which an edge is removed is set to 130 deg.C or lower and the temp. difference between the edge and the film is set to 50 deg.C or lower. |
