RETARDATION FILM

摘要

PROBLEM TO BE SOLVED: To obtain a retardation film of which the retardation is larger and the optical elasticity is lower as the wavelength gets longer with a single film.

SOLUTION: The retardation film is obtained by casting a solution prepared by dissolving cellulose acetate propionate in a single solvent wherein a degree of acetyl substitution (DSac) and a degree of propionyl substitution (DSpr) of the cellulose acetate propionate satisfy the following inequalities (I) and (II). 2.0≤DSac+DSpr≤3.0 (I) 1.0≤DSpr≤3.0 (II).

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