Patent ID: 9581747
Date: 2017-02-28
CPC Classifications: C08L,G02B

Claim:
1. A method for producing an optical film, the method comprising: forming an applied film by applying a solution containing a non-liquid crystalline material with a birefringence (Δnxz) in a thickness direction thereof, represented by the following formula, of 0.0007 or more directly on a shrinkable film; and then solidifying the solution to form the applied film; and wherein the non-liquid crystalline material is at least one material selected from the group consisting of polyarylate, polyvinyl alcohol, polyfumaric acid ester, polyether sulfone, and polysulfone, and forming a birefringence layer having a refractive index distribution that satisfies nx>nz>ny by shrinking the applied film through shrinking the shrinkable film, wherein nx′: in a case where the non-liquid crystalline material is solidified so as to be a solidified layer, a refractive index in a direction (a slow axis direction) in which an in-plane refractive index of the solidified layer reaches its maximum, nz′: a refractive index in a thickness direction of the solidified layer that is orthogonal to each of an nx′ direction and a direction (a fast axis direction) that is orthogonal to the nx′ direction within a plane of the solidified layer, nx: a refractive index in a direction (a slow axis direction) in which an in-plane refractive index of the birefringence layer reaches its maximum, ny: a refractive index in a direction (a fast axis direction) that is orthogonal to an nx direction within a plane of the birefringence layer, and nz: a refractive index in a thickness direction of the birefringence layer that is orthogonal to each of the nx direction and an ny direction.