An optical film is disclosed having minimal curl, minimal coating unevenness and no cracks. The optical film is obtained by casting a dope comprising a cellulose ester and a non-chlorinated solvent on a metal support, the cellulose ester having a total acyl substitution degree of 2.6 to 2.85 and having a ratio of a weight-average molecular weight to a number-average molecular weight of 1:1 to 3:1; drying the cast dope on the metal support so as to obtain a cellulose ester film; peeling the cellulose ester film from the metal support; further drying the cellulose ester film while providing a longitudinal stretch or a lateral stretch to the cellulose ester film; and providing a metal oxide layer on the cellulose ester film.
本发明公开了一种光学薄膜,它具有最小的卷曲度、最小的涂层不均匀度和无裂纹。该光学薄膜是通过在
金属支架上浇铸由
纤维素酯和非
氯化溶剂组成的涂料而获得的,
纤维素酯的总酰基取代度为 2.6 至 2.85,且重量平均分子量与数量平均分子量之比为1:1至3:1;干燥
金属支架上的浇铸涂料,以获得
纤维素酯膜;从
金属支架上剥离
纤维素酯膜;进一步干燥
纤维素酯膜,同时对
纤维素酯膜进行纵向拉伸或横向拉伸;以及在
纤维素酯膜上形成金属氧化物层。