Method of producing film

Details Method of producing film Method of producing film

2003-09-16

2008-11-25

Vargot, Mathieu D. (Department: 1791)

Plastic and nonmetallic article shaping or treating: processes

Forming continuous or indefinite length work

By casting liquids on a solid supporting or shaping surface

C264S001340, C264S288400, C264S290200

Reexamination Certificate

active

07455801

ABSTRACT:
The method of producing a film includes the steps of: casting a dope prepared by dissolving a macromolecular material in a solvent on a casting band; stripping the cast dope from the casting band to form a film; subjecting the stripped film to tentering to stretch or regulate the same in its width direction; and subjecting the tentered film to roll drying to dry the film while conveying the same in such a manner that it engages with a plurality of rolls, the method being characterized in that the solvent content in the film at the beginning of roll drying after tentering is kept within the range of 3 to 8% by weight, the surface temperature of the film during the roll drying is kept within the range of the film's Tg (glass transition temperature) −15° C. to the Tg, and the rate of the film expansion in the film conveying direction is kept within the range of −2% to 3%. Thus, the method enables both wrinkles and cast non-uniformity occurring on the film surface to be improved utilizing the tentering and roll drying steps of the conventional solvent casting method without any modifications, while avoiding the decrease in productivity.

REFERENCES:
patent: 5806834 (1998-09-01), Yoshida
patent: 2003/0223026 (2003-12-01), Morishima et al.
patent: 04-286611 (1992-10-01), None
patent: 08-142209 (1996-06-01), None
patent: 11-048271 (1999-02-01), None

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