Patent ID: 9321227
Filing Date: 2016-04-26
CPC Classification: B29D,B29L,G02B,G02F

Claim Text:
1. A method for manufacturing a phase difference plate, comprising: a step of forming a layered body including a resin layer (a) containing a resin A having positive intrinsic birefringence, a resin layer (b) containing a resin B having negative intrinsic birefringence, the resin layer (b) being provided on one side of the resin layer (a), and a resin layer (c) containing a resin C having positive intrinsic birefringence, the resin layer (c) being provided on a side of the resin layer (b) that is the opposite to the resin layer (a); a first stretching step of stretching the layered body in a first direction at a temperature T1; and a second stretching step of, after the first stretching step, stretching the layered body in a second direction that is approximately orthogonal to the first direction at a temperature T2 which is lower than the temperature T1 to obtain a phase difference plate, a slow axis of the resin layer (a) after the stretching treatment being approximately parallel to each of a slow axis of the resin layer (b) after the stretching treatment and a slow axis of the resin layer (c) after the stretching treatment in the phase difference plate, and wherein a thickness of the resin layer (a), a thickness of the resin layer (b), a thickness of the resin layer (c), and a stretching ratio and a stretching temperature in the first stretching step and the second stretching step being controlled such that in-plane retardation Rea and NZ coefficient NZa in the resin layer (a) after the stretching treatment, in-plane retardation Reb and NZ coefficient NZb in the resin layer (b) after the stretching treatment, and in-plane retardation Rec and NZ coefficient NZc in the resin layer (c) after the stretching treatment satisfy Formulae 5 to 10: