Solution casting method

Abstract

A dope containing Tac is cast onto a belt. When having self-supporting properties, the dope is peeled as a wet film from the belt, and transported to a tenter dryer. In an entrance section, a preheating is made and in an stretching section a stretching is made at a stretch speed Y(% / min). In a relaxation section, the width of the film was becomes shorter, and in the exit section, the width was kept to be uniform and transported toward the tenter dryer. A difference of a content of the remaining solvent between the stretching starting point and a relaxation end position is X. In this case, the following formula is satisfied to reduce the generation of bowing phenomena. Thus the axial diffractive of a slow axis can be reduced.

Description

technical field [0001] The present invention relates to a solution casting method for producing films, preferably for use in electronic displays. Background technique [0002] Polymers are used in several ways. For example, cellulose acetate (hereinafter referred to as TAC) is used to prepare a film, and the film is used as a base film for a photosensitive material or a protective film for a polarizing filter in a liquid crystal display (LCD). As a known method for producing a polymer film, there are a melt-extrusion method in which a polymer is melted by heating and extruded to obtain a film; and a solution casting method in which a coating paint containing a polymer, a solvent, etc. is prepared and The paint was cast to obtain a film. The film obtained in the solution casting method has excellent optical isotropy, and thus the film is used as an optical film (Japan Institute of Invention and Innovation (JIII) JOURNAL of Publication No. 2001-1745). [0003] Considering s...

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Problems solved by technology

Therefore, the structure becomes complicated and the cost for the device is higher

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