US4178218A — Cation exchange membrane and use thereof in the e…

Claim 1

Independent Claim 93 words

A process for the electrolysis of an aqueous sodium chloride solution which comprises passing an electric current through said solution in an electrolytic cell separated into an anode chamber and a cathode chamber by a cation exchange membrane consisting essentially of a fluorocarbon polymer containing pendant carboxylic acid and sulfonic acid groups, the total ion exchange capacity of sulfonic and carboxylic acid groups being from 0.5 to 4.0 milliequivalents per gram of dry resin, the ratio of carboxylic acid groups to sulfonic acid groups being in the range of from 1:100 to 100:1.

Claim 2

Dependent Claim 93 words

A process for the electrolysis of an aqueous sodium chloride solution which comprises passing an electric current through said solution in an electrolytic cell separated into an anode chamber and a cathode chamber by a cation exchange membrane consisting essentially of a fluorocarbon polymer containing pendant carboxylic acid and sulfonic acid groups, the total ion exchange capacity of sulfonic and carboxylic acid groups being from 0.5 to 4.0 milliequivalents per gram of dry resin, the ratio of carboxylic acid groups to sulfonic acid groups being in the range of from 1:100 to 100:1.

Claim 3

Dependent Claim 28 words

The process of claim 1, wherein the ion exchange capacity of the carboxylic acid groups in said membrane is at least 0.005 milliequivalent per gram of dry resin.

Claim 4

Dependent Claim 22 words

The process of claim 1, wherein a fluorocarbon polymer containing pendant carboxylic acid groups is present on the surface of the membrane.

Claim 5

Dependent Claim 22 words

The process of claim 1, wherein a fluorocarbon polymer containing pendant carboxylic acid groups is present on one surface of the membrane.

Claim 6

Dependent Claim 24 words

The process of claim 1, wherein the membrane in the sodium salt form has a water content of from 5 to 50% by weight.

Claim 7

Dependent Claim 29 words

The process of claim 1, wherein said membrane comprises a combination of a fluorocarbon polymer having pendant carboxylic acid groups with a fluorocarbon polymer having pendant sulfonic acid groups.

Claim 8

Dependent Claim 21 words

The process of claim 1, wherein said fluorocarbon polymer comprises a perfluorocarbon polymer having carboxylic acid groups and sulfonic acid groups.

Claim 9

Dependent Claim 13 words

The process of claim 1, wherein the cation exchange membrane is fiber reinforced.

Claim 10

Dependent Claim 63 words

The process of claim 1, wherein said fluorocarbon polymer comprises a copolymer of at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms with fluorocarbon vinyl monomers containing carboxylic acid groups and sulfonic acid groups or functional groups which can be converted to carboxylic acid or sulfonic acid groups.

Claim 11

Dependent Claim 165 words

The process of claim 1, wherein said fluorocarbon polymer comprises a copolymer of a fluorocarbon vinyl monomer having the general formula: CF.sub.2 =CF--O--(CF.sub.2).sub.n --X wherein n is an integer of 2 to 12, and X is CN, COF, COOH, COOR, COOM or CONR 2 R 3 where R is an alkyl group containing 1 to 10 carbon atoms, R 2 and R 3 are individually hydrogen or an alkyl group containing 1 to 10 carbon atoms, and M is sodium, potassium or cesium; and a perfluorocarbon sulfonyl fluoride having the general formula: F--SO.sub.2 --CFR.sub.g --CF.sub.2 --O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and m is an integer of 1 to 3, with at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, which copolymer is hydrolyzed, if necessary, to form said acid groups.

Claim 12

Dependent Claim 120 words

The process of claim 1, wherein said fluorocarbon polymer comprises a copolymer of a perfluoroacrylic acid having the general formula: CF.sub.2 ═CF--COZ wherein Z is fluorine, an alkoxy group containing 1 to 10 carbon atoms, amino or hydroxy; and a perfluorocarbon sulfonyl fluoride having the general formula: F--SO.sub.2 --CFR.sub.g --CF.sub.2 --O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and m is an integer of 1 to 3, with at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, which copolymer is hydrolyzed, if necessary, to form said acid groups.

Claim 13

Dependent Claim 133 words

The process of claim 1, wherein said cation exchange membrane is prepared by impregnating or coating a membrane comprising a copolymer of (A) a perfluorovinyl ether having the general formula: LSO.sub.2 CFR.sub.g CF.sub.2 O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein L is hydroxy, fluorine or OA, where A is a quaternary ammonium radical; R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms; Y is fluorine or a trifluoroemethyl group; and m is an integer of 1 to 3, and (B) at least one of tetrafluoroethylene and CF 2 ═CFOR f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, with a vinyl compound having carboxylic acid groups or derivatives thereof, polymerizing said impregnated or coated vinyl compound, and hydrolyzing, if necessary, to form said acid groups.

Claim 14

Dependent Claim 108 words

The process of claim 12, wherein said vinyl compound is at least one member selected from the group consisting of compounds having the formula: CF.sub.2 ═CF--O--(CF.sub.2).sub.n --X wherein n is an integer of 2 to 12, and X is CN, COF, COOH, COOR, COOM or CONR 2 R 3 , where R is an alkyl group containing 1 to 10 carbon atoms, R 2 and R 3 are individually hydrogen or an alkyl group containing 1 to 10 carbon atoms, and M is sodium, potassium or cesium, and compounds having the formula: CF.sub.2 ═CF--COZ wherein Z is fluorine or an alkoxy group containing 1 to 10 carbon atoms.

Claim 15

Dependent Claim 128 words

The process of claim 1, wherein said cation exchange membrane is prepared by impregnating or coating a membrane comprising a copolymer of (A) a perfluorovinyl ether having the general formula: LSO.sub.2 CFR.sub.g CF.sub.2 O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein L is hydroxy, fluorine or OA, where A is a quaternary ammonium radical; R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms; Y is fluorine or a trifluoromethyl group; and m is an integer of 1 to 3, and (B) at least one of tetrafluoroethylene and CF 2 ═CFOR f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, with a solution of a polymer having carboxylic acid groups or derivatives thereof, and hydrolyzing, if necessary, to form said acid groups.

Claim 16

Dependent Claim 22 words

A process according to claims 12, 13 or 14, wherein the impregnating or coating is conducted on one surface of the membrane.

Claim 17

Dependent Claim 46 words

The process of claim 15, wherein said carboxylic acid groups are contained predominantly on said one surface of the membrane and wherein the membrane is disposed in said electrolytic cell such that said surface having the carboxylic acid groups faces the cathode side of the cell.

Claim 18

Dependent Claim 20 words

A process according to claims 9, 10, 11, 12, 13 or 14, wherein the cation exchange membrane is fiber reinforced.

Claim 19

Dependent Claim 16 words

The process of claim 1, wherein the thickness of the membrane is 0.05 to 1.5 mm.

Claim 20

Dependent Claim 54 words

The process of claim 1, wherein the electrolysis is conducted at a temperature of 0° to 150° C. while charging an aqueous sodium chloride solution into the anode chamber and adding water or an aqueous dilute sodium hydroxide solution into the cathode chamber to adjust the concentration of sodium hydroxide to more than 20%.

Claim 21

Dependent Claim 23 words

The process of claim 1, wherein the aqueous sodium chloride solution charged to the anode compartment is purified with an ion exchange resin.

Claim 22

Dependent Claim 20 words

The process of claim 20, wherein the aqueous sodium chloride solution has a calcium content of less than 1 ppm.

Claim 23

Dependent Claim 70 words

A cation exchange membrane suitable for use in the electrolysis of an aqueous sodium chloride solution consisting essentially of a fluorocarbon polymer containing pendant carboxylic acid and sulfonic acid groups, the total ion exchange capacity of sulfonic and carboxylic acid groups being from 0.5 to 4.0 milliequivalents per gram of dry resin, the ratio of carboxylic acid groups to sulfonic acid groups being in the range of 1:100 to 100:1.

Claim 24

Dependent Claim 70 words

A cation exchange membrane suitable for use in the electrolysis of an aqueous sodium chloride solution consisting essentially of a fluorocarbon polymer containing pendant carboxylic acid and sulfonic acid groups, the total ion exchange capacity of sulfonic and carboxylic acid groups being from 0.5 to 4.0 milliequivalents per gram of dry resin, the ratio of carboxylic acid groups to sulfonic acid groups being in the range of 1:100 to 100:1.

Claim 25

Dependent Claim 32 words

A cation exchange membrane in accordance with claim 22, wherein the ion exchange capacity of the carboxylic acid groups in said membrane is at least 0.005 milliequivalent per gram of dry resin.

Claim 26

Dependent Claim 26 words

A cation exchange membrane in accordance with claim 22, wherein a fluorocarbon polymer containing pendant carboxylic acid groups is present on the surface of the membrane.

Claim 27

Dependent Claim 26 words

A cation exchange membrane in accordance with claim 22, wherein a fluorocarbon polymer containing pendant carboxylic acid groups is present on one surface of the membrane.

Claim 28

Dependent Claim 26 words

A cation exchange membrane in accordance with claim 22, which has a water content in the sodium salt form of from 5 to 50% by weight.

Claim 29

Dependent Claim 31 words

A cation exchange membrane in accordance with claim 22, which comprises a combination of a fluorocarbon polymer having pendant carboxylic acid groups with a fluorocarbon polymer having pendant sulfonic acid groups.

Claim 30

Dependent Claim 25 words

A cation exchange membrane in accordance with claim 22, wherein said fluorocarbon polymer comprises a perfluorocarbon polymer having carboxylic acid groups and sulfonic acid groups.

Claim 31

Dependent Claim 14 words

A cation exchange membrane in accordance with claim 22, which includes a fiber reinforcement.

Claim 32

Dependent Claim 67 words

A cation exchange membrane in accordance with claim 22, wherein said fluorocarbon polymer comprises a copolymer of at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms with fluorocarbon vinyl monomers containing carboxylic acid groups and sulfonic acid groups or functional groups which can be converted to carboxylic acid or sulfonic acid groups.

Claim 33

Dependent Claim 170 words

A cation exchange membrane in accordance with claim 22, wherein said fluorocarbon polymer comprises a copolymer of a fluorocarbon vinyl monomer having the general formula: CF.sub.2 ═CF--O--(CF.sub.2).sub.n --X wherein n is an integer of 2 to 12, and X is CN, COF, COOH, COOR, COOM or CONR 2 R 3 , where R is an alkyl group containing 1 to 10 carbon atoms, R 2 and R 3 are individually hydrogen or an alkyl group containing 1 to 10 carbon atoms, and M is sodium, potassium or cesium; and a perfluorocarbon sulfonyl fluoride having the general formula: F--SO.sub.2 --CFR.sub.g --CF.sub.2 --O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and m is an integer of 1 to 3, with at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, which copolymer is hydrolyzed, if necessary, to form said acid groups.

Claim 34

Dependent Claim 124 words

A cation exchange membrane in accordance with claim 22, wherein said fluorocarbon polymer comprises a copolymer of a perfluoroacrylic acid having the general formula: CF.sub.2 ═CF--COZ wherein Z is fluorine, an alkoxy group containing 1 to 10 carbon atoms, amino or hydroxy; and a perfluorocarbon sulfonyl fluoride having the general formula: F--SO.sub.2 --CFR.sub.g --CF.sub.2 --O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and m is an integer of 1 to 3, with at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, which copolymer is hydrolyzed, if necessary, to form said acid groups.

Claim 35

Dependent Claim 137 words

A cation exchange membrane in accordance with claim 22, wherein said cation exchange membrane is prepared by impregnating or coating a membrane comprising a copolymer of (A) a perfluorovinyl ether having the general formula: LSO.sub.2 CFR.sub.g CF.sub.2 O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein L is hydroxy, fluorine or OA, where A is a quaternary ammonium radical; R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms; Y is fluorine or a tetrafluoromethyl group; and m is an integer of 1 to 3, and (B) at least one of tetrafluoroethylene and CF 2 ═CFOR f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, with a vinyl compound having carboxylic acid groups or derivatives thereof, polymerizing said impregnated or coated vinyl compound, and hydrolyzing, if necessary, to form said acid groups.

Claim 36

Dependent Claim 112 words

A cation exchange membrane in accordance with claim 33, wherein said vinyl compound is at least one member selected from the group consisting of compounds having the formula: CF.sub.2 ═CF--O--(CF.sub.2).sub.n --X wherein n is an integer of 2 to 12, and X is CN, COF, COOH, COOR, COOM or CONR 2 R 3 , where R is an alkyl group containing 1 to 10 carbon atoms, R 2 and R 3 are individually hydrogen or an alkyl group containing 1 to 10 carbon atoms, and M is sodium, potassium or cesium, and compounds having the formula: CF.sub.2 ═CF--COZ wherein Z is fluorine or an alkoxy group containing 1 to 10 carbon atoms.

Claim 37

Dependent Claim 132 words

A cation exchange membrane in accordance with claim 22, wherein said cation exchange membrane is prepared by impregnating or coating a membrane comprising a copolymer of (A) a perfluorovinyl ether having the general formula: LSO.sub.2 CFR.sub.g CF.sub.2 O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein L is hydroxy, fluorine or OA, where A is a quaternary ammonium radical; R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms; Y is fluorine or a trifluoromethyl group; and m is an integer of 1 to 3, and (B) at least one of tetrafluoroethylene and CF 2 ═CFOR f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, with a solution of a polymer having carboxylic acid groups or derivatives thereof, and hydrolyzing, if necessary, to form said acid groups.

Claim 38

Dependent Claim 25 words

A cation exchange membrane in accordance with claims 33, 34 or 35, wherein the impregnating or coating is conducted on one surface of the membrane.

Claim 39

Dependent Claim 20 words

A cation exchange membrane in accordance with claim 22, wherein the thickness of the membrane is 0.05 to 1.5 mm.

Claim 40

Dependent Claim 103 words

An electrolytic cell comprising an anode chamber and a cathode chamber separated by a cation exchange membrane which is suitable for the production of aqueous sodium hydroxide in the cathode chamber wherein an aqueous solution of sodium chloride is charged into the anode chamber, said membrane consisting essentially of a fluorocarbon polymer containing pendant carboxylic acid and sulfonic acid groups, said membrane having a total ion exchange capacity of sulfonic and carboxylic acid groups of from 0.5 to 4.0 milliequivalents per gram of dry resin, the ratio of carboxylic acid groups to sulfonic acid groups being in the range of 1:100 to 100:1.

Claim 41

Dependent Claim 103 words

An electrolytic cell comprising an anode chamber and a cathode chamber separated by a cation exchange membrane which is suitable for the production of aqueous sodium hydroxide in the cathode chamber wherein an aqueous solution of sodium chloride is charged into the anode chamber, said membrane consisting essentially of a fluorocarbon polymer containing pendant carboxylic acid and sulfonic acid groups, said membrane having a total ion exchange capacity of sulfonic and carboxylic acid groups of from 0.5 to 4.0 milliequivalents per gram of dry resin, the ratio of carboxylic acid groups to sulfonic acid groups being in the range of 1:100 to 100:1.

Claim 42

Dependent Claim 31 words

An electrolytic cell in accordance with claim 38, wherein the ion exchange capacity of the carboxylic acid groups in said membrane is at least 0.005 milliequivalent per gram of dry resin.

Claim 43

Dependent Claim 25 words

An electrolytic cell in accordance with claim 38, wherein a fluorocarbon polymer containing pendant carboxylic acid groups is present on the surface of the membrane.

Claim 44

Dependent Claim 25 words

An electrolytic cell in accordance with claim 38, wherein a fluorocarbon polymer containing pendant carboxylic acid groups is present on one surface of the membrane.

Claim 45

Dependent Claim 27 words

An electrolytic cell in accordance with claim 38, wherein the membrane in the sodium salt form has a water content of from 5 to 50% by weight.

Claim 46

Dependent Claim 32 words

An electrolytic cell in accordance with claim 38, wherein the membrane comprises a combination of a fluorocarbon polymer having pendant carboxylic acid groups with a fluorocarbon polymer having pendant sulfonic acid groups.

Claim 47

Dependent Claim 24 words

An electrolytic cell in accordance with claim 38, wherein said fluorocarbon polymer comprises a perfluorocarbon polymer having carboxylic acid groups and sulfonic acid groups.

Claim 48

Dependent Claim 16 words

An electrolytic cell in accordance with claim 38, wherein the cation exchange membrane is fiber reinforced.

Claim 49

Dependent Claim 66 words

An electrolytic cell in accordance with claim 38, wherein said fluorocarbon polymer comprises a copolymer of at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms with fluorocarbon vinyl monomers containing carboxylic acid groups and sulfonic acid groups or functional groups which can be converted to carboxylic acid or sulfonic acid groups.

Claim 50

Dependent Claim 169 words

An electrolytic cell in accordance with claim 38, wherein said fluorocarbon polymer comprises a copolymer of a fluorocarbon vinyl monomer having the general formula: CF.sub.2 ═CF--O--(CF.sub.2).sub.n --X wherein n is an integer of 2 to 12, and X is CN, COF, COOH, COOR, COOM or CONR 2 R 3 , where R is an alkyl group containing 1 to 10 carbon atoms, R 2 and R 3 are individually hydrogen or an alkyl group containing 1 to 10 carbon atoms, and M is sodium, potassium or cesium; and a perfluorocarbon sulfonyl fluoride having the general formula: F--SO.sub.2 --CFR.sub.g --CF.sub.2 --O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and m is an integer of 1 to 3, with at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, which copolymer is hydrolyzed, if necessary, to form said acid groups.

Claim 51

Dependent Claim 121 words

An electrolytic cell in accordance with claim 38, wherein said fluorocarbon polymer comprises a copolymer of a perfluoroacrylic acid having the general formula: CF.sub.2 ═CF--COZ wherein Z is fluorine, an alkoxy group containing 1 to 10 carbon atoms, amino or hydroxy; and a perfluorocarbon sulfonyl fluoride having the general formula: F--SO.sub.2 --CFR.sub.g --CF.sub.2 --O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms, Y is fluorine or a trifluoromethyl group, and m is an integer of 1 to 3, with at least one of tetrafluoroethylene and CF 2 ═CF--O--R f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, and hydrolyzing, if necessary, to form said acid groups.

Claim 52

Dependent Claim 136 words

An electrolytic cell in accordance with claim 38, wherein said cation exchange membrane is prepared by impregnating or coating a membrane comprising a copolymer of (A) a perfluorovinyl ether having the general formula: LSO.sub.2 CFR.sub.g CF.sub.2 O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein L is hydroxy, fluorine or OA, where A is a quaternary ammonium radical; R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms; Y is fluorine or a trifluoromethyl group; and m is an integer of 1 to 3, and (B) at least one of tetrafluoroethylene and CF 2 ═CFOR f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, with a vinyl compound having carboxylic acid groups or derivatives thereof, polymerizing said impregnated or coated vinyl compound, and hydrolyzing, if necessary, to form said acid groups.

Claim 53

Dependent Claim 111 words

An electrolytic cell in accordance with claim 49, wherein said vinyl compound is at least one member selected from the group consisting of compounds having the formula: CF.sub.2 ═CF--O--(CF.sub.2).sub.n --X wherein n is an integer of 2 to 12, and X is CN, COF, COOH, COOR, COOM or CONR 2 R 3 , where R is an alkyl group containing 1 to 10 carbon atoms, R 2 and R 3 are individually hydrogen or an alkyl group containing 1 to 10 carbon atoms, and M is sodium, potassium or cesium, and compounds having the formula: CF.sub.2 ═CF--COZ wherein Z is fluorine or an alkoxy group containing 1 to 10 carbon atoms.

Claim 54

Dependent Claim 131 words

An electrolytic cell in accordance with claim 38, wherein said cation exchange membrane is prepared by impregnating or coating a membrane comprising a copolymer of (A) a perfluorovinyl ether having the general formula: LSO.sub.2 CFR.sub.g CF.sub.2 O(CFYCF.sub.2 O).sub.m --CF═CF.sub.2 wherein L is hydroxy, fluorine or OA, where A is a quaternary ammonium radical; R g is fluorine or a perfluoroalkyl group having 1 to 10 carbon atoms; Y is fluorine or a trifluoromethyl group; and m is an integer of 1 to 3, and (B) at least one of tetrafluoroethylene and CF 2 ═CFOR f wherein R f is a perfluorinated alkyl group containing 1 to 3 carbon atoms, with a solution of a polymer having carboxylic acid groups or derivatives thereof, and hydrolyzing, if necessary, to form said acid groups.

Claim 55

Dependent Claim 24 words

An electrolytic cell in accordance with claims 49, 50 or 51, wherein the impregnating or coating is conducted on one surface of the membrane.

Claim 56

Dependent Claim 49 words

An electrolytic cell in accordance with claim 38, wherein said carboxylic acid groups are contained predominantly on said one surface of the membrane and wherein the membrane is disposed in said electrolytic cell such that said surface having the carboxylic acid groups faces the cathode side of the cell.

Claim 57

Dependent Claim 19 words

An electrolytic cell in accordance with claim 38, wherein the thickness of the membrane is 0.05 to 1.5 mm.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1982-12-10	1983-06-11	1983-12-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1986-12-10	1987-06-11	1987-12-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1990-12-10	1991-06-11	1991-12-11	$7700.00	Window Closed / Lapsed

Cation exchange membrane and use thereof in the electrolysis of sodium chloride

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