Patent ID: 8597551

Claim:
An optical film using a base resin, a cellulose ester resin with a portion of hydrogen atoms of hydroxyl groups of cellulose being substituted with an acyl group of the following formula 1 and one or more substituent groups selected from formula 2, wherein a degree of substitution with the acyl group is 2.46 to 2.72, and a total degree of substitution with the substituent groups other than the acyl group is 0.11 to 0.54, —CO—R 1 [formula 1] —X—R 2 [formula 2] wherein, X is a connection group selected from the group consisting of —CS—, —S—, —SO—, —SO 2 —, —PR 11 —, —POR 12 —, —NR 13 — and a combination of two or more of the connection groups, and R 11 , R 12 and R 13 are independently selected from the group consisting of H, (C 1 -C 10 )alkylene, (C 6 -C 30 )arylene, (C 3 -C 20 )cycloalkylene, and (C 2 -C 10 )alkenylene; R 1 is (C 1 -C 10 )alkyl; R 2 is selected from the group consisting of (C 1 -C 10 )alkyl, (C 6 - 30 )aryl, (C 3 -C 20 )cycloalkyl, (C 2 -C 10 )alkenyl, and (C 6 -C 30 )ar(C 1 -C 20 )alkyl; and alkyl, aryl, cycloalkyl, alkenyl, and aralkyl of R 1 and R 2 may be further substituted with one or more substituent groups selected from the group consisting of 5-membered to 7-membered heterocycloalkyl including one or more elements selected from the group consisting of (C 1 -C 10 )alkyl, halogen, nitro, cyano, hydroxy, amino, (C 6 -C 30 )aryl, (C 2 -C 10 )alkenyl, (C 3 -C 20 )cycloalkyl, N, O, and S, and (C 4 -C 30 ) heteroaryl including one or more elements selected from the group consisting of N, O, and S.