abstract |
An optical film is provided which has high elasticity and a low humidity expansion rate. This optical film contains a polyamide-imide resin which has a weight average molecular weight of 200,000-1,000,000 and which has at least a constituent unit represented by formula (1) [in formula (1), Ar1 represents a divalent aromatic group having a fluoroalkyl group with 1-12 carbons, and X represents a divalent organic group], and a constituent unit represented by formula (2) [In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group]. |