Method for producing porous membrane and drying device of porous membrane

Patent metadata

Field	Value
Publication number	US-9528760-B2
Application number	US-201314383946-A
Country	US
Kind code	B2
Filing date	Mar 12, 2013
Priority date	Mar 12, 2012
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

The present invention of a method for producing a porous membrane including a solidification step of forming a porous membrane, and a heating step of drying the porous membrane, wherein the heating step includes at least a water reduction step of the porous membrane, the water reduction step uses a heating medium, and the temperature of the heating medium (T gh ) satisfies a relation of t gh >T d , when T d represents the heat deformation temperature of a membrane material. The present invention of a drying device of a porous membrane including a water reduction unit, and a final drying unit, wherein the drying device includes a membrane-surface-temperature measurement means for measuring the surface temperature of the porous membrane and the final drying unit, and a control means for controlling the temperature and/or the flow speed of the heating medium of the water reduction unit.

First claim

The invention claimed is:

1. A method for producing a porous membrane comprising:
a solidification step of forming a porous membrane by solidifying a membrane-forming solution by a solidification solution; and
a heating step of drying the porous membrane,
wherein the heating step includes at least a water reduction step of reducing moisture contained in the porous membrane,
the water reduction step uses a heating medium that heats the porous membrane, and
the temperature of the heating medium used in the water reduction step satisfies a relation of the following formula (a):
t gh >T d   (a)

In formula (a), t gh represents the temperature of the heating medium used in the water reduction step and T d represents the heat deformation temperature of a membrane material.

2. The method for producing a porous membrane according to claim 1 ,
wherein the heating step includes a final drying step of drying the porous membrane after the water reduction step,
the final drying step uses a heating medium that heats the porous membrane, and
the temperature of the heating medium used in the final drying step satisfies a relation of the following formula (b):
t sh ≦T d   (b)

In formula (b), t sh represents the temperature of the heating medium used in the final drying step and T d represents the heat deformation temperature of the membrane material.

3. The method for producing a porous membrane according to claim 1 ,
wherein the temperature of the heating medium used in the water reduction step is equal to or higher than a melting point of the membrane material.

4. The method for producing a porous membrane according to claim 1 ,
wherein the maximum surface temperature of the porous membrane in the water reduction step is lower than the heat deformation temperature (T d ) of the membrane material.

5. The method for producing a porous membrane according to claim 1 ,
wherein the water reduction step reduces moisture contained in the porous membrane until the moisture content of the porous membrane reaches at least 70% or less of initial moisture content.

6. The method for producing a porous membrane according to claim 2 ,
wherein the maximum surface temperature of the porous membrane in the final drying step satisfies a relation of the following formula (c):
T gh <T sh <T d   (c)

In formula (c), T gh represents the maximum surface temperature of the porous membrane in the water reduction step, T sh represents the maximum surface temperature of the porous membrane in the final drying step, and T d represents the heat deformation temperature of the membrane material.

7. The method for producing a porous membrane according to claim 6 ,
wherein the temperature of the heating medium used in the final drying step is 120° C. or less.

8. The method for producing a porous membrane according to claim 1 ,
wherein the moisture content of the porous membrane after the heating step is 1% or less, and a reduction rate of the amount of permeated water is 30% or less.

9. The method for producing a porous membrane according to claim 1 ,
wherein the surface temperature of the porous membrane after performing the water reduction step is measured, and the temperature and/or the flow speed of the heating medium used in the water reduction step are controlled according to the surface temperature of the porous membrane.

10. The method for producing a porous membrane according to claim 2 ,
wherein the surface temperature of the porous membrane after performing the final drying step is measured, and the temperature and/or the flow speed of the heating medium used in the final drying step are controlled according to the surface temperature of the porous membrane.

11. The method for producing a porous membrane according to claim 2 ,
wherein the final drying step dries the porous membrane while regulating the tension of the porous membrane.

12. A drying device of a porous membrane including a water reduction unit that reduces moisture contained in a porous membrane with a heating medium, and a final drying unit that is provided in the downstream of the water reduction unit and dries the porous membrane with the heating medium, wherein the drying device of a porous membrane comprises a membrane-surface-temperature measurement means for measuring the surface temperature of the porous membrane and provided between the water reduction unit and the final drying unit; and
a control means for controlling the temperature and/or the flow speed of the heating medium of the water reduction unit according to a measured result of the surface temperature.

13. The drying device of a porous membrane according to claim 12 , further comprising:
a membrane-surface-temperature measurement means for measuring the surface temperature of the porous membrane and provided in the downstream of the final drying unit; and
a control means for controlling the temperature and/or the flow speed of the heating medium of the final drying unit according to a measured result of the surface temperature.

14. A drying device comprising:
a water reduction unit that reduces moisture contained in a porous membrane with use of a heating medium; and
a final drying unit that is provided in the downstream of the water reduction unit and dries the porous membrane,
wherein the final drying unit includes a control mechanism that regulates the tension of the porous membrane,
a temperature of the heating medium used in the water reduction step satisfies a relation of the following formula (a):
t gh >T d   (a)

wherein, in formula (a), t gh represents the temperature of the heating medium used in the water reduction step and T d represents a heat deformation temperature of a membrane material.

15. The method for producing a porous membrane according to claim 9 ,
wherein the surface temperature of the porous membrane after performing the final drying step is measured, and the temperature and/or the flow speed of the heating medium used in the final drying step are controlled according to the surface temperature of the porous membrane.

Assignees

• Mitsubishi Rayon Co

Inventors

• Maehara Osamu
• Kurashina Masaki
• Sumi Toshinori

Classifications

• F26B21/35

  Temperature; Pressure · CPC title

• B01D67/0095

  Drying · CPC title

• C08J9/26

  by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out · CPC title

• B01D2323/42

  Details of membrane preparation apparatus · CPC title

• F26B3/00 Primary

  Drying solid materials or objects by processes involving the application of heat (in specific machines or apparatus F26B9/00 - F26B19/00) · CPC title