Purification of fluoroionomer compositions

1. A process for the purification from ionic impurities of a fluoroionomer liquid composition, said process comprising:

contacting a liquid composition, said liquid composition comprising at least one fluoroionomer (I-1) and ionic impurities in a liquid medium, with a solid particulate comprising at least one fluoroionomer (I-2) having ion exchange groups, wherein H + or OH − ions are bound to at least a fraction of said ion exchange groups; and

separating said liquid composition from said solid particulate, wherein fluoroionomer (I-1) and fluoroionomer (I-2) are selected from fluoroionomers (I) comprising recurring units derived from at least one fluorinated functional monomer selected from:

sulfonated perfluoroolefins of formula (M1):

wherein n is an integer between 0 and 6; and X′ is selected from the group consisting of Cl, F, Br, I and —O − M + , wherein M + is a cation selected from the group consisting of H + , NH 4 + , K + , Li + , Na + , and mixtures thereof;

sulfonated perfluorovinylethers of formula (M2):

wherein m is an integer between 1 and 10; and X′ is selected from the group consisting of Cl, F, Br, I and —O − M + , wherein M + is a cation selected from the group consisting of H + , NH 4 + , K + , Li + , Na + , and mixtures thereof;

sulfonated perfluoroalkoxyvinylethers of formula (M3):

wherein w is an integer between 0 and 2, RF 1 and RF 2 , equal or different from each other and at each occurrence, are independently —F, —Cl or a C 1-10 perfluoroalkyl group, y is an integer between 0 and 6; and X′ is selected from the group consisting of Cl, F, Br, I and —O − M + , wherein M + is a cation selected from the group consisting of H + , NH 4 + , K + , Li + , Na + , and mixtures thereof;

sulfonated aromatic (per)fluoroolefins of formula (M5):

wherein Ar is a C 3-15 aromatic or heteroaromatic moiety and X′ is selected from the group consisting of Cl, F, Br, I and —O − M + , wherein M is a cation selected from the group consisting of H + , NH 4 + , K + , Li + , Na + , and mixtures thereof; and

(M6) mixtures thereof.

2. The process of claim 1 , wherein the fluoroionomer (I) is selected from the group consisting of tetrafluoroethylene (TFE) copolymers comprising recurring units derived from at least one functional per(halo)fluoromonomer.

3. The process of claim 2 , wherein the fluoroionomer (I) is selected from the group consisting of TFE copolymers comprising recurring units derived from perfluoro-2-(2-fluorosulfonylethoxyl)propylvinyl ether [formula (M3-A)]:

and/or from perfuoro-5-sulphonylfluoride-3-oxa-1-pentene [formula (M2-D)]:

in their —SO 2 F or —SO 2 X″ form, wherein X″ is selected from the group consisting of Cl, Br, I and —O − M + , wherein M + is a cation selected from the group consisting of H + , NH 4 + , K + , Li + , Na + , and mixtures thereof.

4. The process according to claim 1 , wherein the solid particulate comprises, in addition to the fluoroionomer (I-2) having H + or OH − ions bound to at least a fraction of its ion exchange groups, an inert support at least partially coated with said fluoroionomer (I-2).

5. The process according to claim 1 , wherein the solid particulate consists essentially of fluoroionomer (I-2).

6. The process according to claim 1 , wherein the solid particulate is in the form of powder.

7. The process according to claim 6 , wherein the solid particulate is in the form of coagulated latex powder.

8. The process according to claim 1 , wherein the separation of the liquid composition from the solid particulate is effected using a technique selected from the group consisting of filtration, decantation, sedimentation, and centrifugation.

9. The process according to claim 1 , said process being a process for the purification from cationic impurities, wherein the liquid composition is purified until a residual total metal content of less than 10 ppm is obtained in the purified liquid composition.

10. The process according to claim 1 , said process being a process for the purification from cationic impurities, wherein a liquid composition comprising fluoroionomer (I-1) having cations selected among NH 4 +, K + , Li + , Na + bound to its ion exchange groups is purified until a liquid composition comprising fluoroionomer (I-1) having H + cations bound to its ion exchange groups is obtained.

11. The process according to claim 6 wherein the solid particulate consists of ground, pulverized, or finely dispersed solid particles.

12. The process according to claim 11 , wherein the solid particulate is in the form of coagulated latex powder.

13. The process according to claim 1 , wherein fluoroionomer (I-1) and fluoroionomer (I-2) are the same fluoroionomer (I).

14. The process according to claim 1 , wherein fluoroionomer (I-1) is selected from fluoroionomers (I) wherein X′ is Na + .

15. The process according to claim 1 , wherein the liquid medium comprises water or a water/alcohol mixture.

16. The process according to claim 1 , wherein the liquid composition has a solid content of between about 5% and about 40% by weight.

17. The process according to claim 1 , wherein the liquid composition has a viscosity of less than about 400 Cpoise.