It is an object to provide a method of manufacturing a thermoplastic film capable of improving optical properties of the thermoplastic film obtained by drawing it and to provide the thermoplastic film. In a transverse drawing process part 30 for drawing a thermoplastic film 16 in a transverse direction is constituted by a preheating zone T1 and transverse drawing zones T2, T3 and cooling zones T4, T5, and the steps of the transverse drawing zone T3 and performed thereafter (cooling zone T4 and T5) are maintained at a glass transition temperature Tg or less. The temperature of the preheating zone T1 is set to be higher than that of the cooling zone T4 and falls within the range of -10 C to +30 C relative to those of the transverse drawing zones T2 and T3.
本发明旨在提供一种通过拉伸能够改善热塑性薄膜光学性能的制造方法,并提供这种热塑性薄膜。在横向拉伸过程中,横向拉伸装置30由预热区T1和横向拉伸区T2、T3以及冷却区T4、T5构成,横向拉伸区T3及其后进行的步骤(冷却区T4和T5)的温度控制在
玻璃化转变温度Tg以下。预热区T1的温度设置高于冷却区T4,且相对于横向拉伸区T2和T3的温度范围在-10℃到+30℃之间。