Drying device and film producing method from solution

Abstract

Provided are a drying device and a film producing method from solution. A second drying unit for drying a curtain coating film (30) comprises a case-like feeding pipe, vertical nozzles (32b) venting drying wind (402), and suction pipes (32c) sucking drying wind (402). A feeding pipe is arranged at the upside of the curtain coating film (30). The vertical nozzles (32b), from the bottom of the feeding pipe, protrude toward the curtain coating film (30). The suction pipes (32c) are arranged at both sides of the B direction of the vertical nozzles (32) which are arranged along the direction toward the A direction. The suction pipes (32c) are provided with suction ports (32cx) for sucking the drying wind (402). The suction ports (32cx) are arranged at the position farther away from the curtain coating film (30) than the blowing-in slots (32bx) arranged upon the vertical nozzles (32b). A suction path is formed among the vertical nozzles (32b).

Description

technical field [0001] The invention relates to a drying device and a solution film forming method. Background technique [0002] A light-transmitting polymer film (hereinafter, referred to as a film) is widely used as an optical film because it is light in weight and easy to mold. Among them, cellulose ester-based films such as cellulose acylate are used for optical films (for example, retardation films, polarizing plate protective films, etc.) ). [0003] Such membranes are produced by solution membrane-forming methods. The outline of the solution film forming method is as follows. First, a polymer solution (hereinafter referred to as a dope) containing a polymer and a solvent is made to flow, and a cast film is formed on a support. Second, the solvent is evaporated from the cast film until the cast film is in a state where it can be transported independently. 3. Peel off the cast film from the support as a wet film. Thereafter, a film can be obtained from the wet fi...

AI Technical Summary

Problems solved by technology

However, since the suction port 202b is extended, it is difficult to make the suction amount of the drying air uniform in the width direction.

Therefore, resulting in unstable drying conditions in the width direction of the cast film

The optical film subjected to the drying process under such conditions causes the optical characteristics (such as Re, Rth) to be unstable in the width direction

Images