Patent ID: 8900656
Filing Date: 2014-12-02
Classification: G02B,G02F

Abstract:
1. A method for producing an optical film comprising a birefringent layer, comprising the steps of: forming a coating film by directly applying a material for forming a birefringent layer on a shrinkable film; shrinking the coating film in a first direction by shrinking the shrinkable film; and stretching a laminate of the shrinkable film and the coating film in a second direction orthogonal to the first direction, wherein the material for forming a birefringent layer contains at least one resin selected from the group consisting of norbornene resins, polycarbonate resins, cellulose resins, polyamides, and polyurethanes, wherein the birefringent layer has a refractive index distribution satisfying nx>nz>ny, where nx is a refractive index in a direction which is a slow axis direction in which an in-plane refractive index of the birefringent layer reaches its maximum, ny is a refractive index in a direction which is a fast axis direction that is orthogonal to the nx direction within a plane of the birefringent layer, and nz is a refractive index in a thickness direction of the birefringent layer that is orthogonal to each of the nx and ny directions, and wherein the birefringent layer has a front retardation in a range from 130 to 500 nm; and wherein the birefringent layer has an alignment axis accuracy within the range from −1.0° to +1.0°.