Cellulose acylate film, method of producing the same, cellulose derivative film, optically compensatory film using the same, optically-compensatory film incorporating polarizing plate, polarizing plate and liquid crystal display device

摘要

A method of producing a cellulose derivative film, the method comprising: forming a film with a solvent cast method from a dope including a cellulose derivative satisfying following conditions (a) and (b): (a) at least one among three hydroxyl groups included in a glucose unit of cellulose is substituted by a substituent of which a polarizability anisotropy Δα represented as following Expression (1) is 2.5×10⁻²⁴ cm³ or higher: Expression (1): Δα=αx−(αy+αz)/2, wherein αx, αy and αz is as defined in the specification; and (b) when a substitution degree by a substituent of which Δα is 2.5×10⁻²⁴ cm³ or higher is P_A, and a substitution degree by a substituent of which Δα is lower than 2.5×10⁻²⁴ cm³ is P_B, the P_A and P_B satisfy following Expressions (3) and (4): Expression (3): 2P_A+P_B3.0; and Expression (4): P_A0.2.