JPH0557739A - Casting film forming method - Google Patents

Abstract

PURPOSE:To provide the above method for obtaining a uniform planar film without damaging flatness by specifying the content of a volatile component and a temp. condition at the time of peeling without relying on the selection of a solvent. CONSTITUTION:A polymer solution is cast on a metal support to form a film and this film is dried to be peeled off from the support and further subjected to after-drying. In this casting film forming method, the percentage of a volatile component at the time of peeling is set to 10-30wt.% on a dry basis and the surface temp. of the support at the peeled part is held to the temp. range of 14-20 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a flow in which a polymer solution is cast on a metal support to form a film, which is then dried, peeled off from the support and further dried. The present invention relates to a film-forming method.

[0002]

2. Description of the Related Art A polymer solution is cast on a metal support,
As a casting film-forming method in which a film-shaped material is formed, dried, peeled off from the support, and post-dried, for example, 3
After casting a dope prepared by dissolving fibrin acetate in a mixed solvent of methylene chloride and methylene alcohol to form a film,
Perform drying, take care when peeled off from the support,
It was extremely difficult to improve the film forming speed so as not to impair the flatness and transparency of the film when stripped off.
In order to solve this problem, the solvent of the dope is methylene chloride 80-93% ethyl alcohol 2-7%,
A method using a mixed solvent composed of 5 to 13% of n-butyl alcohol (see Japanese Patent Publication No. 459074), or a solvent for the dope is methylene chloride and 1 to 2 carbon atoms.
Is disclosed, and the solvent is a solvent containing 13 to 30% by weight of an alcohol having 1 to 2 carbon atoms (JP-A-54-48862).

[0003]

However, when it is not desirable to use a plurality of solvents for promoting peeling as described above, or when it is difficult to select an appropriate solvent as described above, for example, solutes are used. There has been a demand for countermeasures when using polycarbonate. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a casting film forming method which does not impair the flatness under the conditions of stripping volatile matter and stripping temperature without depending on the selection of a solvent.

[0004]

Means for Solving the Problems The above object of the present invention is to cast a polymer solution on a metal support to form a film, then dry the film, and peel it off from the support. Further, in the casting film-forming method in which post-drying is performed, the content of the solvent at the time of stripping is set to 10 to 30% by weight on the dry basis, and the surface temperature of the support is kept at 20 ° C. or lower and 14 ° C. or higher at the stripped portion. And a casting film forming method.

In the case of casting film formation, when the casting film is peeled from the support (band and drum), if the casting film has a strong adhesive force with the support, stepwise unevenness may occur at the time of peeling. become. If the time from peeling after casting is shortened, the amount of solvent evaporated is small and the film becomes less stiff, and elongation occurs during peeling, resulting in unevenness in the width direction. In general, the volatile content of the film and the peeling load from the support during solution casting have a shape as shown in FIG. In this case, if the volatile content is higher, the stiffness of the film may be weakly stretched or slackened, and in some cases, a peeling residue phenomenon may occur in which a part of the film remains on the support. That is, if the content of the solvent at the time of peeling exceeds 30% by dry weight, the peeling load becomes large, and there is a risk of occurrence of stepwise unevenness at the time of peeling. At 40% by dry weight, the peeling load decreases. However, the stiffness of the film becomes weak and elongation occurs at the time of peeling, resulting in unevenness in the width direction. If the amount of solvent contained is 10% on a dry basis, film peeling will occur spontaneously and there is a risk of scratching the film. The dry amount is preferably 15 to 27% by weight. In the present invention, the dry amount basis means (solvent amount / dry solid content) × 100%.
The surface temperature of the support is 20 ° or less and 14 ° at the peeled portion.
Keeping the temperature above is a means for weakening the adhesive force of the film to the support at the time of peeling, and when the temperature of the peeling part reaches 22 ° C., the peeling property is poor and step-like unevenness is generated in the film. At 12 ° C., dew condensation occurs on the surface of the support, and brushing that causes the surface of the film to become cloudy is not preferable.

[0006]

【Example】

(Example-1) When a dope of 17.5% by weight of polycarbonate was cast on a band support and the amount of the solvent contained at the time of stripping was set to 19% by weight on a dry basis, when stripped from the support. A good film with no resistance and no unevenness was obtained.

(Comparative Example-1) The amount of the solvent contained is the dry standard 3
In the case of 3% by weight, there was resistance to peeling and unevenness in the width direction of the film occurred. Further, when the dry amount was 10% by weight or less, the film spontaneously peeled off from the support, and a trouble occurred during production.

(Example-2) When the temperature of the support at the peeling portion of the support was set to 15.5 ° C, the peelability was improved.

(Comparative Example 2) When the temperature of the support at the peeling portion was 22 ° C., the peelability was poor and stepwise unevenness was produced. 12 ° C
In the following, dew condensation occurred on the surface of the support, and brushing which turned the surface of the film into a cloudy state occurred and the surface condition of the film deteriorated.

[0010]

EFFECTS OF THE INVENTION By the casting film forming method of the present invention, a uniform planar film can be formed without spoiling the flatness depending on the amount of solvent contained during stripping and the temperature conditions during stripping, without selecting the solvent. I was able to manufacture it.

[Brief description of drawings]

FIG. 1 is a graph of a stripping load against a dry weight standard (weight%) of a solvent content when stripping a dope.

Claims (1)

[Claims] 1. A casting film-forming method in which a polymer solution is cast on a metal support to form a film, which is then dried, peeled off from the support, and post-dried. The casting film-forming method, wherein the content of the solvent at the time of stripping is set to 10 to 30% by weight on a dry basis, and the surface temperature of the support is kept at 20 ° or less and 14 ° C. or more in the stripped portion.