| 摘要 |
PURPOSE:To contrive an improvement in film manufacturing rate and to enable stabilized flow casting of a film, by a method wherein two kinds of dopes to be obtained by dissolving cellulose triacetate into two kinds of mixed solvents whose poor solvent mixture ratios are different with each other is cocasted under a specific terms. CONSTITUTION:(A) A dope to be obtained by dissolving cellulose triacetate (hereinafter referred to as CTA) into a mixed solvent of methylene chloride with methanol or the mixed solvent to be obtained by adding a poor solvent of the CTA other than the methanol to the foregoing mixed solvent and (B) a dope to be obtained by dissolving the CTA into the mixed solvent whose mixture ratio of said poor solvent is higher than that of the mixed solvent of the dope A are cocasted for manufacture of a film so that the dope B is come into contact with the surface of a supporting material and a thickness of casting of the dope B becomes more than 5mum under a wet state. In addition to the above, as for a casting method, a method wherein the dopes A, B are made to join with each other in the midst of a slit by making use of a composite slit die is favorable. |
