JP2003145562A5 - - Google Patents

Description

[0036]
In the tenter drying unit 14, dry air at 110 ° C. was supplied from both sides of the film 26 so that the maximum air velocity of the dry air blown to the film 26 was 10.0 m / s. Further, in the roll drying unit 16, dry air of 120 ° C. is supplied from the air surface 26B side and exhausted from the support surface 26A side, and in the roll drying unit 18, dry air of 130 ° C. from the air surface 26B side of the film 26. Was supplied and exhausted from the support surface 26A side. At this time, the maximum velocity of the drying air blown to the film 26 in each of the roll drying units 16 and 18 was 1.5 m / s. Next, steam of 145 ° C. was sprayed at an amount of 8 g / m ^{2 by} the curl correction device 28 onto the air surface 26 B of the film 26 dried by the roll drying units 16 and 18, and then the film 26 was wound up. The film thickness of the film 26 manufactured in this manner was 79 μm, and the curl radius of curvature in 25 ° C. water was 35 mm. In addition, the plasticizer content ratio (the support surface 26A side / the air surface 26B side) when dividing the film 26 into two in the thickness direction was 1.61.
(Film production conditions of Comparative Example 1)
Using the production apparatus 34 of FIG. 2, the dope A was cast to produce a film 26. That is, after the dope A was extruded from the die 24 and cast onto the band 22 and dried to have a self-supporting property, the film was peeled off as a film 26 and introduced into the tenter drying unit 14. At this time, the volatile content at peeling was 70%.