| 摘要 |
PURPOSE:To contrive a reduction of a peeling off period of time from the surface of a supporting material of the titled film and a drying period of time of the film, by performing under specific terms cocasting of a dope, whose concentration is thin and mixture ratio of a poor solvent is high, on both sides of a dope whose concentration of cellulose triacetate is thick. CONSTITUTION:A film is manufactured by so constituting the titled manufacture that (A) to both sides of a dope, which is obtained by dissolving cellulose triacetate (hereinafter referred to as CTA) into a mixed solvent of methylene chloride and methanol or a mixed solvent to be obtained by adding a poor solvent of the CTA other than the methanol, (B) a mixed solvent, whose mixing ratio of a poor solvent is thicker than that of the mixed solvent of the dope A, is applied, a dope whose concentration of the CTA is thinner than that of the dope A is made to cocast and, moreover, a thickness of casting of the dope B, which has been made to cast on a surface side of a supporting material, becomes 5-150mum under a wet state. In addition to the above, as for the concentration of the CTA of the dope A, it is desirable to be 20-30% and as for the mixing ratio of the poor solvent of the dope B, it is desirable to be 5-15wt%. |
