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Polyimide membranes made of polymerization solutions

a technology of polymerization solution and polymer, which is applied in the field of polymerization solution polymer membranes, can solve the problems of high brittleness of film and membrane produced therefrom, uniform production of polymer membranes only possible with great difficulty, and good separation properties of gases

Inactive Publication Date: 2012-05-17
EVONIK FIBERS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0002]This invention has for its object to provide a production process for polyimides that does not use any substances which would be a disruptive influence in the subsequent membrane production process. It further has for its object that the process provided by the invention shall make it possible to produce membranes having sufficient mechanical properties.

Problems solved by technology

However, various customers (e.g., Air Liquide Medal, US 2006 / 156920) report that the films and membranes produced therefrom are very brittle and only blends with other polymers lead to stable films and hollow fiber membranes.
Therefore, uniform production of polymer membranes is only possible with great difficulty.
But the disadvantage here is that very good separation properties for gases, plasticization stabilities to CO2 and chemical stabilities to many solvents are in part disruptively influenced, or even destroyed, by admixing other polymers.
There are the same problems here as in the production of hollow fiber membranes.

Method used

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  • Polyimide membranes made of polymerization solutions
  • Polyimide membranes made of polymerization solutions
  • Polyimide membranes made of polymerization solutions

Examples

Experimental program
Comparison scheme
Effect test

example 1

Producing a P84 Type 70 Polyimide Solution in Dimethylacetamide

[0115]A 3 l glass reactor equipped with stirrer and reflux condenser is initially charged with 1622 g of anhydrous dimethylacetamide. A quantity of 456.4 g of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride are dissolved therein and the solution is heated to 90° C. To this solution is added 0.45 g of sodium hydroxide. Under nitrogen, 266.8 g of a mixture of 64% of 2,4-tolylene diisocyanate, 16% of 2,6-tolylene diisocyanate and 20% of 4,4′-diisocyanatodiphenylmethane are metered during several hours. In the process, CO2 escapes as by-product and a polyimide results directly in solution.

[0116]The highly viscous solution obtained has a golden color, a solids content of 25% and a viscosity of 49 Pa·s.

[0117]The molar masses are determined by gel permeation chromatography as follows: Mn=80 600 g·mol−1, Mp=139 600 g·mol−1, Mw=170 000 g·mol−1 PDI=2.11

example 2

Producing a P84 Type 70 Polyimide Solution in Dimethylformamide

[0118]A 3 l glass reactor equipped with stirrer and reflux condenser is initially charged with 1622 g of anhydrous dimethylformamide. A quantity of 456.4 g of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride are dissolved therein and the solution is heated to 90° C. To this solution is added 0.45 g of sodium hydroxide. Under nitrogen, 266.8 g of a mixture of 64% of 2,4-tolylene diisocyanate, 16% of 2,6-tolylene diisocyanate and 20% of 4,4′-diisocyanatodiphenylmethane are metered during several hours. In the process, CO2 escapes as by-product and a polyimide results directly in solution.

[0119]The highly viscous solution obtained has a golden color, a solids content of 27% and a viscosity of 48 Pa·s.

[0120]The molar masses are determined by gel permeation chromatography as follows: Mn=76 600 g·mol−1, Mp=130 500 g·mol Mw=146 200 g·mol−1 PDI=1.91

example 3

Producing a P84 Type 70 Polyimide Solution in N-methylpyrrolidone

[0121]A 3 l glass reactor equipped with stirrer and reflux condenser is initially charged with 1800 g of anhydrous N-methylpyrrolidone. A quantity of 456.4 g of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride are dissolved therein and the solution is heated to 90° C. To this solution is added 0.45 g of sodium hydroxide. Under nitrogen, 266.8 g of a mixture of 64% of 2,4-tolylene diisocyanate, 16% of 2,6-tolylene diisocyanate and 20% of 4,4′-diisocyanatodiphenylmethane are metered during several hours. In the process, CO2 escapes as by-product and a polyimide results directly in solution.

[0122]The highly viscous solution obtained has a golden color, a solids content of 25% and a viscosity of 45 Pa·s.

[0123]The molar masses are determined by gel permeation chromatography as follows: Mn=65 700 g·mol−1, Mp=107 200 g·mol−1, Mw=147 000 g·mol−1 PDI=2.24

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Abstract

The invention relates to polyimide membranes and to a phase inversion method for the production thereof. The polyimide membranes can be used to separate different gas mixtures.

Description

FIELD OF INVENTION[0001]The invention concerns polyimide membranes produced directly from a polyimide polymerization solution without the polyimide having been isolated in the form of a solid material, particularly not as dried solid material and more particularly not as dried powder, and then redissolved. The polyimide membranes concerning the invention can be either flat sheet membranes or hollow fiber membranes. The polyimide membranes can be not only porous membranes in the form of micro-, ultra- or nanofiltration membranes but also aporous membranes for separation of gases. All the membranes are integrally asymmetrical membranes and are produced by a phase inversion process.OBJECT[0002]This invention has for its object to provide a production process for polyimides that does not use any substances which would be a disruptive influence in the subsequent membrane production process. It further has for its object that the process provided by the invention shall make it possible to...

Claims

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Application Information

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IPC IPC(8): B01D71/64B29D22/00C08G18/76B05D5/00B01D53/22B01D67/00C01B32/50
CPCB01D53/228B01D67/0009B01D71/64C08G73/1042B01D2325/022C08L79/08B01D69/087B01D2323/18C08G73/1067Y02C20/40B01D67/0011B01D67/0013B01D67/00091
Inventor UNGERANK, MARKUSBAUMGARTEN, GOETZ
Owner EVONIK FIBERS
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