Polymer film producing apparatus and method

Abstract

A polymer film producing apparatus has a moving support on which dope containing polymer and solvent is cast to form a cast film. The cast film is stripped from the support to obtain a polymer film containing the solvent, and the polymer film is dried. A first gas flow duct has gas nozzles for causing a first dry gas to flow toward the cast film. A second gas flow duct has a gas outlet disposed downstream from the gas nozzles, and positioned higher than a height of the gas nozzles relative to the support, for causing a second dry gas to flow toward the cast film in a moving direction of the support. Furthermore, the first gas flow duct includes a gas blow wall for defining the first flow path by opposing to the support. The gas blow wall has the gas nozzles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which:

FIG. 1 is an explanatory view illustrating a dope producing system;

FIG. 2 is an explanatory view in side elevation illustrating a polymer film producing system; and

FIG. 3 is an explanatory view in side elevation illustrating a drier.

Claims

1. A polymer film producing apparatus, having a moving support on which dope containing polymer and solvent is cast to form a cast film, wherein said cast film is stripped from said support to obtain a polymer film containing said solvent, and said polymer film is dried, said polymer film producing apparatus comprising: a first gas flow device, having a first gas outlet for causing a first dry gas to flow toward said cast film; anda second gas flow device, having a second gas outlet disposed downstream from said first gas outlet, and positioned higher than a height of said first gas outlet relative to said support, for causing a second dry gas to flow in a moving direction of said support.

2. A polymer film producing apparatus as defined in claim 1, further comprising: a first flow path, disposed to extend in said moving direction, for flowing of said first dry gas from said first gas flow device on said cast film;a second flow path, disposed to extend downstream from said first flow path with respect to said moving direction, for flowing of said second dry gas from said second gas flow device on said cast film;wherein a height H1 of said first flow path relative to said support is equal to or more than 20 mm and equal to or less than 300 mm.

3. A polymer film producing apparatus as defined in claim 2, wherein a length La of said first flow path is smaller than a length Lb of said second flow path.

4. A polymer film producing apparatus as defined in claim 3, further comprising a flow regulator, disposed at an upper end of said second gas outlet, for directing said second dry gas in said moving direction.

5. A polymer film producing apparatus as defined in claim 3, wherein said first gas flow device further comprises a vent channel, formed near to said first gas outlet, for passage of said first dry gas, and for causing said first dry gas to flow in said moving direction near to said cast film.

6. A polymer film producing apparatus as defined in claim 5, wherein each of α1 and α2 is equal to or more than 20 and equal to or less than 150, where α1 and α2 satisfy conditions of: α1=V1/(H11/2)α2=V2/(H21/2)where V1 is a flow rate (m/sec) of said first dry gas;V2 is a flow rate (m/sec) of said second dry gas;H2 is a height of said second flow path with reference to said support.

7. A polymer film producing apparatus as defined in claim 5, wherein time of lapse after a start of contact of said dope on said support until supply of said first dry gas to said cast film is 15 seconds or less.

8. A polymer film producing apparatus as defined in claim 7, wherein upon or before lapse of 15 seconds after a start of forming said cast film, said first gas flow device starts operation and supplies said first dry gas to said cast film for at least three seconds.

9. A polymer film producing apparatus as defined in claim 7, wherein temperature of said first and second dry gases is equal to or more than 40 deg. C. and equal to or less than 150 deg. C.

10. A polymer film producing apparatus as defined in claim 2, further comprising a flow regulator, disposed between said first and second gas flow devices, for directing said first dry gas in said moving direction.

11. A polymer film producing apparatus as defined in claim 2, wherein said first gas outlet is constituted by plural gas nozzles.

12. A polymer film producing apparatus as defined in claim 2, wherein said first gas flow device includes a gas blow wall for defining said first flow path by opposing to said support, said gas blow wall having said first gas outlet; said second gas flow device includes:a middle wall for constituting one inner edge of said second gas outlet; andan upper wall, disposed higher than said middle wall, opposed to said middle wall, for defining said second gas outlet, and for further extending downstream, to define said second flow path by opposing to said support.

13. A polymer film producing method in which dope containing polymer and solvent is cast on a moving support to form a cast film, said cast film is stripped from said support to obtain a polymer film containing said solvent, and said polymer film is dried, said polymer film producing method comprising steps of: causing a first dry gas to flow toward said cast film through a first gas outlet positioned to face said support; andcausing a second dry gas to flow through a second gas outlet being open in a moving direction of said support and positioned higher than a height of a first flow path of a flow of said first dry gas relative to said support.

14. A polymer film producing method as defined in claim 13, wherein in said flow of said first dry gas, an outer layer portion of said cast film is dried, to form a surface layer on a surface of said cast film with a higher surface tension than an undried portion; and in said flow of said second dry gas, drying of said cast film is promoted.

15. A polymer film producing method as defined in claim 14, wherein a second flow path is disposed to extend downstream from said first flow path with respect to said moving direction, for flowing of said second dry gas on said cast film; a length La of said first flow path is smaller than a length Lb of said second flow path.

16. A polymer film producing method as defined in claim 14, wherein time of lapse after a start of contact of said dope on said support until supply of said first dry gas to said cast film is 15 seconds or less.

17. A polymer film producing method as defined in claim 16, wherein upon or before lapse of 15 seconds after a start of forming said cast film, said first dry gas starts to flow and is supplied to said cast film for at least three seconds.

18. A polymer film producing method as defined in claim 16, wherein temperature of said first and second dry gases is equal to or more than 40 deg. C. and equal to or less than 150 deg. C.

19. A polymer film producing method as defined in claim 13, wherein a height H1 of said first flow path relative to said support is equal to or more than 20 mm and equal to or less than 300 mm.

20. A polymer film producing method as defined in claim 13, wherein each of α1 and α2 is equal to or more than 20 and equal to or less than 150, where α1 and α2 satisfy conditions of: α1=V1/(H11/2)α2=V2/(H21/2)where V1 is a flow rate (m/sec) of said first dry gas;V2 is a flow rate (m/sec) of said second dry gas;H2 is a height of said second flow path with reference to said support.