Method for preparing dope and method for producing cellulose triacetate film

摘要

A dope is prepared by quickly and completely dissolving a polymer in a solvent. The solvent is supplied from a solvent tank to a solution tank. A measuring apparatus measures 15 to 20% by weight of a polymer with respect to the solvent and feeds the polymer to the solution tank. 5 to 15% by weight of a plasticizer with respect to the polymer is fed from a plasticizer tank to the solution tank. Stirring is carried out at 80 rpm for 30 minutes using a stirring blade in the solution tank so as to obtain a roughly dissolved solution. The roughly dissolved solution is heated at 85° C. for 10 minutes with a heater, so that all components necessary for a dope are dissolved, and only impurities are filtrated with a filtration filter. This filtrate is supplied to a dope tank, and it is used as a dope which is used in production of a film by solution film processing. A film produced from the dope has a retardation of 40 nm, and the film has little optical anisotropy and excellent optical performances.