MULTILAYER CATION EXCHANGE CHLORALKALI MEMBRANE
A multilayer cation exchange membrane for use in a chloralkali process comprising an carboxylate layer comprising a fluorinated ionomer containing carboxylate groups on one side of the membrane, an exterior sulfonate layer comprising a fluorinated ionomer containing sulfonate groups on the side of the membrane opposite the carboxylate layer, and an interior sulfonate layer comprising a fluorinated ionomer containing to sulfonate groups between the carboxylate layer and the exterior sulfonate layer, the exterior sulfonate layer having an ion exchange ratio greater than about 11.3, and the interior sulfonate layer having an ion exchange ratio less than about 11.
1 . A multilayer cation exchange membrane for use in a chloralkali process comprising a carboxylate layer comprising a fluorinated ionomer containing carboxylate groups on one side of the membrane, an exterior sulfonate layer comprising a fluorinated ionomer containing sulfonate groups on the side of the membrane opposite the carboxylate layer, and an interior sulfonate layer comprising a fluorinated ionomer containing sulfonate groups between the carboxylate layer and the exterior sulfonate layer, the exterior sulfonate layer having an ion exchange ratio greater than about 11.3, and the interior sulfonate layer having an ion exchange ratio less than about 11.
2 . The membrane of claim 1 wherein the interior sulfonate layer has an ion exchange ratio less than the ion exchange ratio of the exterior sulfonate layer by at least about 0.6.
3 . The membrane of claim 1 wherein the carboxylate layer has an IXR of about 13.8 to about 16.
4 . The membrane of claim 1 wherein the exterior sulfonate layer has an ion exchange ratio greater than about 11.5.
5 . The membrane of claim 1 wherein the exterior sulfonate layer has an ion exchange ratio of about 11.3 to about 17.5.
6 . The membrane of claim 1 wherein the exterior sulfonate layer has an ion exchange ratio of about 11.3 to about 15.5.
7 . The membrane of claim 1 wherein the exterior sulfonate layer has an ion exchange ratio of about 11.3 to about 13.5.
8 . The membrane of claim 1 wherein the exterior sulfonate layer has an ion exchange ratio or about 11.3 to about 12.4.
9 . The membrane of claim 1 wherein the interior sulfonate layer has an ion exchange ratio less than about 10.9.
10 . The membrane of claim 1 wherein the interior sulfonate layer has an ion exchange ratio of about 9.3 to about 11.
11 . The membrane of claim 1 wherein the interior sulfonate layer has an ion exchange ratio of about 10 to about 11.
12 . The membrane of claim 1 wherein the interior sulfonate layers has an ion exchange ratio of about 10 to about 10.9.
13 . The membrane of claim 1 further comprising a woven fabric reinforcement.
14 . The membrane of claim 13 wherein the woven fabric reinforcement is embedded at least partially in the membrane.
15 . The membranes of claim 13 wherein the woven fabric comprises fluoropolymer yarns having a denier less than about 100.
16 . The membrane of claim 1 wherein the interior sulfonate layer has a thickness of at least about 40 micrometers.
17 . The membrane of claim 1 wherein the interior sulfonate layer has a thickness of about 50 micrometers to about 200 micrometers.
18 . The membrane of claim 1 wherein the interior sulfonate layer has a thickness of about 60 micrometers to about 100 micrometers.
19 . The membrane of claim 1 wherein the exterior sulfonate layer has a thickness less than about 30 micrometers.
20 . The membrane of claim 1 wherein the exterior sulfonate layer has a thickness of about 5 micrometers to about 30 micrometers.
21 . The membrane of claim 1 wherein the exterior sulfonate layer has a thickness of about 7 micrometers to about 25 micrometers.
22 - 42 . (canceled)
43 . A multilayer cation exchange membrane for use in a chloralkali process comprising a carboxylate layer comprising a fluorinated ionomer containing carboxylate groups on one side of the membrane, an exterior sulfonate layer comprising a fluorinated ionomer containing sulfonate groups on the side of the membrane opposite the carboxylate layer, and first and second interior sulfonate layers comprising fluorinated ionomer containing sulfonate groups between the carboxylate layer and the exterior sulfonate layer, the first interior sulfonate layer being between the carboxylate layer and the second interior sulfonate layer and the second interior sulfonate layer being between the first interior sulfonate layer and the exterior sulfonate layer, the exterior sulfonate layer having an ion exchange ratio greater than about 11.3, the first interior sulfonate layer having an ion exchange ratio greater than about 11.3, and the second interior sulfonate layer having an ion exchange ratio less than about 11.
44 . The membrane of claim 43 wherein the second interior sulfonate layer has an ion exchange ratio less than the ion exchange ratio of the exterior sulfonate layer by at least about 0.6.
45 . The membrane of claim 43 wherein the first interior sulfonate layer has an ion exchange ratio greater than the ion exchange ratio of the second interior sulfonate layer by at least about 0.6.
46 . The membrane of claim 43 wherein the carboxylate layer has an ion exchange ratio of about 13.8 to about 16.
47 . The membrane of claim 43 wherein the first interior sulfonate layer has an ion exchange ratio that differs from the ion exchange ratio of the carboxylate layer by no more than about 3.3.
48 - 52 . (canceled)