| 摘要 |
PURPOSE: To obtain an optical PES film wherein an optical main axis is vertical with respect to the flowing direction with a specified angle as an allowable range without deteriorating other properties by specifying a thickness of the film, a plane birefringence index, and an angle within an allowable range with which the optical main axis is vertical with respect to the flowing direction. CONSTITUTION: In a PES(polyether sulfone) film or sheet, a thickness is 20-500μm, a plane birefringence indexΔNXY is 0.00001-0.00050, and an optical main axis is vertical with respect to the flowing direction with an allowable range of±10 deg.. A PES film 6 to be extruded by a T-die l is adhered and fixed by electrification fixing devices 3 and 4 arranged in parallel in the cross direction on a first roll 2, and cooled. Then, it is further cooled by a second cooling roll 5 so as to form the PES film 6. The temperature of the die is preferably 320-380 deg.C, the temperature of the first cooling roll 2 is uniformly controlled at 180-240 deg.C, and the temperature of the second cooling roll 5 is uniformly controlled at 140-210 deg.C. |
