Aromatic polyimide, polyester and polyamide separation membranes

Abstract

Gas separation membranes are made from aromatic polyimides, polyesters and polyamides in which the repeating unit of the main polymer chain (a) has at least one rigid divalent subunit, the two main chain single bonds extending from which are not colinear, (b) is sterically unable to rotate 360° around at least one of these bonds, and (c) has 50% or more of its main chain atoms as members of aromatic rings.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. The process of separating .[.fluids.]. .Iadd.a mixture of gases .Iaddend.using a semipermeable membrane of which at least 50% by weight consists essentially of a polymer whose main chain has a repeating unit containing at least one group selected from the group consisting of aromatic imide, aromatic ester and aromatic amide groups, in which said repeating unit (a) contains at least one rigid divalent subunit, the two main chain single bonds extending from which are not colinear,   (b) is sterically unable to rotate 360° around one or more of said main chain single bonds, and   (c) has more than 50% of its main chain atoms in aromatic groups, the said aromatic imide repeating unit having the formula ##STR83## R and R 1  are, respectively, a divalent and tetravalent organic radical, the said aromatic ester repeating unit having the formula ##STR84## wherein each of R 2  and R 3 , alike or different, is a divalent organic radical, and the said aromatic amide repeating unit having the formula ##STR85## wherein R and R 3  are as defined above and R 7  is hydrogen, lower alkyl or phenyl.     
     
     
       2. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 1 in which the polymer is a polyimide. 
     
     
       3. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 2 in which the polymer is polypyromellitimide of 4-isopropyl-1,3-diaminobenzene. 
     
     
       4. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 2 in which the polymer is poly(4,4'-[bis(trifluoromethyl)methylene]dibenzene-1,2,1',2'-tetracarboxylic diimide) of 1,5-naphthylenediamine. 
     
     
       5. The process of separating .[.fluids in 173  .Iadd.gases .[.in.]. .Iadd.of .Iaddend.claim 2 in which the polymer is poly(4,4'-[bis(trifluoromethyl)methylene]dibenzene-1,2,1',2'-tetracarboxylic diimide) of 4,5-diaminodiphenyl ether. 
     
     
       6. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 2 in which the polymer is poly(4,4'-[bis(trifluoromethyl)methylene]dibenzene-1,2,1',2'-tetracarboxylic diimide) of metaphenylenediamine. 
     
     
       7. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 2 in which the polymer is poly(4,4'-[bis(trifluoromethyl)methylene]dibenzene-1,2,1',2'-tetracarboxylic diimide) of paraphenylenediamine. 
     
     
       8. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 1 in which the polymer is a polyester. 
     
     
       9. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 8 in which the polymer is poly[4,4'-(ditrifluoromethylmethylene)dibenzene-1,1'-diyl] isophthalate/terephthalate. 
     
     
       10. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 8 in which the polymer is poly[4,4'-(ditrifluoromethylmethylene)di(2,6-dichlorobenzene)-1,1'-diyl] isophthalate/terephthalate. 
     
     
       11. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 8 in which the polymer is poly[4,4'-(ditrifluoromethylmethylene)di(2,6-dibromobenzene)-1,1'-diyl] isophthalate/terephthalate. 
     
     
       12. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 8 in which the polymer is poly[4,4'-dimethylmethylene)di(2,6-chlorobenzene)-1,1'-diyl] isophthalate/terephthalate. 
     
     
       13. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 8 in which the polymer is poly[4,4'-(dimethylmethylene)di(2,6-dichlorobenzene)-1,1'-diyl] isophthalate/terephthalate. 
     
     
       14. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 1 in which the polymer is a polyamide. 
     
     
       15. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly(4,4'-[bis(trifluoromethyl)methylene]di-p-phenylene) isophthalamide/terephthalamide. 
     
     
       16. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly(4-isopropyl-m-phenylene) isophthalamide. 
     
     
       17. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly(2,5,2',5'-tetrachlorobiphenylene) isophthalamide. 
     
     
       18. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly(1,5-naphthylene) isophthalamide/terephthalamide. 
     
     
       19. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly(4,6-dichloro-m-phenylene) isophthalamide/terephthalamide. 
     
     
       20. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly(2,6-dichloro-p-phenylene) isophthalamide/terephthalamide. 
     
     
       21. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim 14 in which the polymer is poly[(3,3'-dichlorobiphenylene)/(m-phenylene)] isophthalamide. .[.22. The process of separating fluids of claim 1 in 
     
     
        which the fluid is a mixture of gases..]. 23. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim .[.22.]. .Iadd.1 .Iaddend.in 
     
     
        which the polymer is a polyimide. 24. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim .[.22.]. .Iadd.1 .Iaddend.in 
     
     
        which the polymer is a polyester. 25. The process of separating .[.fluids.]. .Iadd.gases .Iaddend.of claim .[.22.]. .Iadd.1 .Iaddend.in 
     
     
        which the polymer is a polyamide. .[.26.  A fluid-separation apparatus comprising: a fluid-permeation cell;   a fluid inlet and a fluid outlet connected to said cell; and   a semipermeable membrane dividing the cell between the inlet and the outlet; at least 50% by weight of said membrane consisting essentially of a polymer whose main chain has a repeating unit containing at least one group selected from the group consisting of aromatic imide, aromatic ester and aromatic amide groups, in which said repeating unit     (a) contains at least one rigid divalent subunit, the two main chain single bonds extending from which are not colinear,   (b) is sterically unable to rotate 360° around one or more of said main chain single bonds, and   (c) has more than 50% of its main chain atoms in aromatic groups, the said aromatic imide repeating unit having the formula ##STR86## wherein R and R 1  are, respectively, a divalent and tetravalent organic radical, the said aromatic ester repeating unit having the formula ##STR87## wherein each of R 2  and R 3 , alike or different, is a divalent organic radical, and the said aromatic amide repeating unit having the formula ##STR88## wherein R and R 3  are as defined above and R 7  is hydrogen, lower     
     
     
        alkyl or phenyl..]. .[.27.  The fluid-separation apparatus of claim 26 in which the polymer is a polyimide..]. .[.28. The fluid-separation apparatus of claim 26 in which the polymer is a polyester..]. .[.29. The fluid-separation apparatus of claim 26 in which the polymer is a polyamide..].