Solution casting method for producing film

Abstract

An inner pressure of a disperser is decreased with use of a vacuum pump. TAC and a mixture solvent are supplied into the disperser. In a dispersion liquid, since the TAC is dispersed to the mixture solvent under the decreased pressure, the content of the gas becomes lower. After the swelling of the dispersion liquid into the swelling solution, the swelling solution is fed to a dope production apparatus so as to obtain a dope. The dope is supplied into a concentrating apparatus for performing the concentration and the degassing of the dope. Thus an obtained condensed dope contains only small quantity of gas components. The dope is thereafter cast from the casting die, dried and cooled to obtain the film. Since the film production was continuously made without using the storing tank, it is prevented that the foreign materials and the gas damage the film properties.

Description

technical field [0001] The present invention relates to solution casting for the production of thin films. Background technique [0002] Cellulose acylate, especially cellulose triacetate (hereinafter abbreviated as TAC), is used as a raw material for films in the solution casting method. The TAC film can be used in liquid crystal displays and as a base film for photosensitive materials. In order to produce such a TAC film, as described in PCT2001-1745 (pages 2 to 6) International Publication, TAC is dissolved in a mixed solvent to obtain a polymer solution (hereinafter referred to as a dope), the mixed solvent The main compound is dichloromethane. This dope is cast onto a support (such as a casting belt, drum, etc.) to form a cast film. When the cast film has self-supporting properties, the cast film is peeled from the carrier using a peel roll stand, dried, cooled, and then rolled into a polymer film. [0003] In the past solution casting method, the dope was stored in...

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Problems solved by technology

Cast the dope to create a thin film

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