Abstract An ion exchange membrane, which is made by sulfonating a membranous polymer having functional groups suitable for introduction of ion exchange groups, under mild conditions first at the surface of the membrane and then gradually towards its interior, thereby to introduce sulfonic acid groups into said functional groups present in the surface, or its vicinitry, of the membrane, and then introducing anoion exchange groups into the remainder of the functional groups to convert said membranous polymer to an anion exchange membrane; wherein said sulfonation is carried out under conditions which will provide a sulfonic acid group equivalent of 0.05 to 20 percent based on the total ion exchange groups, and a ratio of the direct current resistance of the anion exchange membrane to its alternate current resistance of not more than the limiting resistance ratio.
AN ION EXCHANGE MEMBRANE CONTAINING BOTH CAION EXCHANGE GROUPS AND ANION EXCHANGE GROUPS, SAID CATION EXCHANGE GROUPS BEING SULFONIC ACID GROUPS WHICH ARE PRESENT ON THE SURFACE, OR ITS VICINITY, OF THE ION EXCHANGE MEMBRANE, THE DENSITY OF THE SULFONIC ACID GROUPS PROGRESSIVELY DECREASING FROM THE SURFACE OF THE MEMBRANE TOWARDS ITS INTERIOR, THE AMOUNT OF THE SULFONIC ACID GROUPS BEING 0.05 TO 20 EQUIVALENT PERCENT BASED ON THE TOTAL AMOUNT OF THE ION EXCHANGE GROUPS, THE AMOUNT OF SAID ANION EXCHANGE GROUP MEMBRANE HAVING A EQUENCY PERCENT BASED ON THE TOTAL AMOUNT OF THE ION EXCHANGE GROUPS, AND SAID ION EXCHANGE MEMBRANE HAVING A RATIO OF DIRECT MEMBRANE CURRENT RESISTANCE TO ALTERNATE CURRENT MEMBRANE RSISTANCE OF NOT MORE THAN THE LIMITING RESISTANCE RATIO.
Claim 2
Dependent Claim
124 words
AN ION EXCHANGE MEMBRANE CONTAINING BOTH CAION EXCHANGE GROUPS AND ANION EXCHANGE GROUPS, SAID CATION EXCHANGE GROUPS BEING SULFONIC ACID GROUPS WHICH ARE PRESENT ON THE SURFACE, OR ITS VICINITY, OF THE ION EXCHANGE MEMBRANE, THE DENSITY OF THE SULFONIC ACID GROUPS PROGRESSIVELY DECREASING FROM THE SURFACE OF THE MEMBRANE TOWARDS ITS INTERIOR, THE AMOUNT OF THE SULFONIC ACID GROUPS BEING 0.05 TO 20 EQUIVALENT PERCENT BASED ON THE TOTAL AMOUNT OF THE ION EXCHANGE GROUPS, THE AMOUNT OF SAID ANION EXCHANGE GROUP MEMBRANE HAVING A EQUENCY PERCENT BASED ON THE TOTAL AMOUNT OF THE ION EXCHANGE GROUPS, AND SAID ION EXCHANGE MEMBRANE HAVING A RATIO OF DIRECT MEMBRANE CURRENT RESISTANCE TO ALTERNATE CURRENT MEMBRANE RSISTANCE OF NOT MORE THAN THE LIMITING RESISTANCE RATIO.
Claim 3
Dependent Claim
16 words
The ion exchange membrane of claim 1 wherein said limiting resistance ratio is 2.0 to 3.0.
Claim 4
Dependent Claim
28 words
The ion exchange membrane of claim 1 wherein the amount of said sulfonic acid groups is 0.1 to 10 equivalent percent based on the total ion exchange groups.