PRODUCTION OF PHASE DIFFERENCE FILM

摘要

PROBLEM TO BE SOLVED: To obtain a phase difference film improved in mechanical strengths and durability without being colored yellow to green by treating an oriented polyvinyl alcohol film with an aqueous borax solution. SOLUTION: A polyvinyl alcohol film which is not optically anisotropic is uniaxially oriented in air or water at 20-50 deg.C at a draw ratio of 1.05-2 and optionally dried to obtain a phase difference film. This film is treated with an aqueous borax solution having a concentration of 0.1-10% or oriented in an aqueous borax solution having a concentration of 0.1-5% to obtain a polyvinyl alcohol phase difference film having a retardation value (R) of 300-800nm [wherein R is defined by the formula: R=Δn .d (wherein Δm is a value of birefringence; and d is the thickness of the film)].