Patent ID: 7101496

Claim:
An optical film comprising at least one resin-layer comprising a thermoplastic norbornene resin formed of a copolymer comprising: a structural unit a represented by formula (1) below: wherein, m is 1, p is 0, and the definitions of X and R 1 to R 4 are consistent with the specifically named monomers A as follows: 8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-ethoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7.10 ]-3-dodecene, 8-n-propoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-isopropoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-n-butoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-phenoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-methyl-8-ethoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-methyl-8-n-propoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-methyl-8-isopropoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 8-methyl-8-n-butoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, and 8-methyl-8-phenoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene; and a structural unit b represented by formula (2) below: wherein, Y represents formula —CH═CH— or formula —CH 2 CH 2 —, R 5 to R 8 each represent, independently, a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group of 1 to 30 carbon atoms which may contain a linkage group incorporating any one of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, or a polar group, provided that said groups R 5 to R 8 each exclude a group represented by formula (a) below: —(CH 2 ) q —O—C(O)—R′ (a) where q represents 0 or an integer of at least 1, and R′ represents an organic group, a plurality of X's present in a molecule of said copolymer being the same or different, and a plurality of Y's present in a molecule of said copolymer being the same or different, wherein the weight ratio (a/b) of said structural unit a to said structural unit b in the copolymer is in the range of 95/5 to 60/40.