Claims
- 1. A method for producing a perfluorocarbon copolymeric ion-exchange membrane separator having superior gas release properties on at least one surface thereof comprising the steps of:
- (a) dispersing particulate copolymeric perfluorocarbon ion-exchange resin in a liquid dispersion medium containing a sufficient proportion of at least one highly effective solvent as illustrated in Table 1 herein to dissolve a significant amount of said resin;
- (b) mixing into the resultant resin dispersion formed in (a) finely-divided, non-conductive, inorganic particles insoluble therein to form a suspension of same in said resin dispersion;
- (c) applying said suspension directly or after removal of some of the dispersion medium therefrom to at least one side of a preformed sheet membrane composed principally of the same type of copolymeric perfluorocarbon ion-exchange resin as said particulate in (a); and
- (d) removing remaining dispersion medium under conditions causing said inorganic particles to become adhered to the surface of said preformed sheet membrane by the binding action of dissolved resin.
- 2. The method of claim 1, a pore precursor being included in the suspension and including the step of removing the pore precursor subsequent to removal of the dispersion medium.
- 3. The method of claim 1 wherein step (a) of dispersing the particulate copolymeric perfluorocarbon resin includes the sub-steps of:
- (i) heating the dispersion medium and the particulate copolymer resin to a temperature between about 50.degree. C. and about 250.degree. C.; and
- (ii) maintaining said temperature at least until the dispersion medium contains between about 1 percent and 15 percent by weight of dissolved copolymer resin;
- and wherein step (d) removing dispersion medium includes the sub-steps of:
- (i) cooling the dispersion medium containing the copolymer resin until a gelatinous dispersion forms, and continuing to cool the dispersion whereby syneresis of dispersion medium from the dispersion forms dispersion medium droplets within the dispersion;
- (ii) continuing to cool the dispersion until dispersion medium droplets crystallize;
- (iii) removing the non-crystallized dispersion medium at a temperature below the melting point of the crystallized droplets; and
- (iv) removing said crystallized droplets to leave voids forming thereby a porous layer of resin and inorganic particles.
- 4. The method of claim 3, wherein said dispersion medium includes at least one of perfluorooctanoic and perfluorodecanoic acids.
- 5. The method of claim 1 wherein the preformed sheet of membrane of copolymeric resin has a thickness of between 1 and 150 mils.
- 6. The method of claim 1, wherein said solvent is N-butylacetamide or tetrahydrothiophene-1, 1-dioxide.
- 7. The method of claim 1, wherein the suspension is applied directly upon a copolymeric perfluorocarbon ion-exchange sheet membrane.
- 8. The method of claim 1, wherein the inorganic particles are selected from the group consisting of a metal oxide, a metal nitride, a metal carbide, a metal nitrate, a metal hydroxide, or mixtures thereof.
- 9. The method of claim 8, wherein said metal is selected from Ti, Zr, Nb, Ta, V, Mn, Mo, Sn, Sb, W, Bi, In, Co, Ni, Be, Al, Cr, Fe, Ga, Ge, Se, Y, Ag, Hf, Pb, Th or mixtures thereof.
- 10. A perfluorocarbon copolymeric ion-exchange membrane separator having superior gas release properties on at least one of its side faces and consisting essentially of:
- (a) a resinous ion-exchange sheet membrane composed essentially of perfluorocarbon copolymer resin; and
- (b) adhered to at least one side face of said membrane, a coating of finely divided, non-conductive inorganic particles deposited thereon as a suspension of same in a dispersion medium containing particulate copolymeric perfluorocarbon ion exchange resin of the same type as the perfluorocarbon copolymer resin in said membrane and a sufficient proportion of a highly effective solvent as illustrated in Table 1 herein to dissolve a significant amount of said particulate resin, said coating of particles being adhered to said membrane face by the binding action of dissolved resin upon removal of said dispersion medium from said deposited suspension.
- 11. An ion-exchange membrane separator as described in claim 10 wherein said coating is porous as a result of a pore precursor being included in said suspension and then removed from the coating after removal of said dispersion medium.
- 12. An ion-exchange membrane separator as described in claim 10 wherein said inorganic particles are selected from metal oxides, metal nitrides, metal carbides, metal nitrates, metal hydroxides and mixtures thereof.
- 13. An ion exchange membrane separator as described in claim 12 wherein said metal is selected from Ti, Zr, Nb, Ta, V, Mn, Mo, Sn, Sb, W, Bi, In, Co, Ni, Be, Al, Cr, Fe, Ga, Ge, Se, Y, Ag, Hf, Pb, Th and mixtures thereof.
- 14. An ion-exchange membrane separator as described in claim 10, 11, 12 or 13 wherein said particles and said membrane both consist essentially of copolymeric perfluorocarbon resin polymerized from at least one fluorinated vinyl monomer and at least one monomer of the structures CF.sub.2 .dbd.CFX, CF.sub.2 CFR.sub.1 X, or CF.sub.2 .dbd.CFOR.sub.1 X, wherein R.sub.1 is a bifunctional perfluorinated radical of from 2 to 8 carbon atoms that can be at least once interrupted by an oxygen atom, and X is selected from a group consisting of sulfonyl fluoride, carbonyl fluoride, sulfonate ester and carboxylate ester.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of copending U.S. patent application Ser. No. 419,922, filed Sept. 20, 1982, now U.S. Pat. No. 4,469,579 which in turn is a continuation-in-part of U.S. patent application Ser. No. 277,918, filed June 26, 1981, now U.S. Pat. No. 4,421,579.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4411749 |
Sato et al. |
Oct 1983 |
|
4486278 |
Oda |
Dec 1984 |
|
Foreign Referenced Citations (2)
Number |
Date |
Country |
56-163287 |
Dec 1981 |
JPX |
2064586A |
Jun 1981 |
GBX |
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
419922 |
Sep 1982 |
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Parent |
277918 |
Jun 1981 |
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