Patent ID: 7494689
Filing Date: 2009-02-24
Classification: C09K,G02B

Abstract:
1. A method for manufacturing a birefringent film having a birefringent index ΔNxz=nx−nz in a thickness direction, which is determined by ΔNxz=nx−nz being (i) 0.002 or larger and (ii) smaller than 0.12, comprising the steps of: coating a base with a polymer solution obtained by dissolving a polyimide-containing polymer in a solvent so as to form a coating film; and drying the coating film so as to form a birefringent film, wherein the drying step comprises at least two stages of drying processes, and an amount of a remaining solvent in the birefringent film after a latter stage of the drying process is 3 wt % or less.