OPTICAL FILM, PROCESS FOR PRODUCING OPTICAL FILM, POLARIZER, AND LIQUID-CRYSTAL DISPLAY

摘要

An optical film which is formed from a material having a low melt viscosity and which is reduced in coloration and fluctuates little in retardation; a process for producing the optical film; a polarizer employing the optical film and having satisfactory durability over long; and a liquid-crystal display having a high contrast. The optical film is characterized by comprising a cellulose ester in which the kinds of substituents and the degrees of substitution therewith per one glucose unit of the cellulose ester satisfy all of the following relationships (1) to (3). Relationship (1) 6.30<=2×X+3×Y<=7.50 Relationship (2) 1.10<=Y<=1.50 Relationship (3) 0.35<=Y6<=0.50[In the relationships, X represents the total of the average degrees of substitution with acetyl in the 2-, 3-, and 6-positions; Y represents the total of the average degrees of substitution with propionyl in the 2-, 3-, and 6-positions; and Y6 represents the average degree of substitution with propionyl in the 6-position.]