Patent ID: 8221855
Filing Date: 2012-07-17
Classification: C09K,G02B,G02F

Abstract:
1. A cellulose derivative film comprising a cellulose derivative having a substituent, the substituent having a polarizability anisotropy Δα of 2.5×10 the polarizability anisotropy Δα being represented by equation: wherein Δα is the largest of the eigenvalues obtained by diagonalization of a polarizability tensor; ay is the second largest of the eigenvalues obtained by diagonalization of a polarizability tensor; and az is the smallest of the eigenvalues obtained by diagonalization of a polarizability tensor, and the cellulose derivative film having an Re and an Rth satisfying the respective inequalities: wherein Rth(λ) is a retardation in the thickness direction at a wavelength λ nm; and Re(λ) is an in-plane retardation at a wavelength λ nm.