Synthetic diaphragm and process of use thereof

Claim 2

A liquid permeable diaphragm for an electrolytic cell, said diaphragm consisting essentially of organic material, the organic material comprising polymer fibers containing functional groups selected from the group consisting of --COOR, --COOM, --COX, --CN, --CONR'R", --SO 3 M, --SO 2 NH 2 , --PO(OR) 2 , --PO(OM) 2 , --PO(OX) 2 , --OPO(OR) 2 , --OPO(OM) 2 , and --OPO(OX) 2 where R is an aryl or a C 1 to C 10 alkyl group; M is H, an alkali metal or an ammonium group; R' and R" are each independently either H or a C 1 to C 10 alkyl group; and X is Cl or F.

Claim 3

The diaphragm of claim 1 wherein the organic polymer fibers are perfluorinated.

Claim 4

The diaphragm of claim 2 further including a diluent polymer material.

Claim 5

The diaphragm of claim 3 wherein the diluent material is fibrous.

Claim 6

The diaphragm of claim 4 wherein the diluent material is fibrillated polytetrafluoroethylene.

Claim 7

The diaphragm of claim 1 wherein the functional groups are selected from the group consisting of --COOR, --COOM, --COX, --CN, and --CONR'R" where R is an aryl or a C 1 to C 10 alkyl group; M is H, an alkali metal or an ammonium group; R' and R" are each independently either H or a C 1 to C 10 alkyl group; and X is Cl or F.

Claim 8

A liquid permeable, cation exchange diaphragm for an electrolytic cell, said diaphragm consisting essentially of organic material, the organic material comprising polymer fibers containing functional groups selected from the group consisting of --COOM, --SO 3 M, --PO(OM) 2 , and --OPO(OM) 2 , where M is H, an alkali metal or an ammonium group.

Claim 9

A liquid permeable, cation exchange diaphragm for an electrolytic cell, said diaphragm consisting essentially of organic material, the organic material comprising polymer fibers containing functional groups selected from the group consisting of --COOM, --SO 3 M, --PO(OM) 2 , and --OPO(OM) 2 , where M is H, an alkali metal or an ammonium group.

Claim 10

The diaphragm of claim 7 wherein the organic polymer fibers are perfluorinated.

Claim 11

The diaphragm of claim 8 further including a diluent polymer material.

Claim 12

The diaphragm of claim 9 wherein the diluent material is fibrous.

Claim 13

The diaphragm of claim 10 wherein the diluent material is fibrillated polytetrafluoroethylene.

Claim 14

The diaphragm of claim 7 wherein the functional groups are --COOM where M is H, an alkali metal or an ammonium group.

Claim 15

A non-asbestos, liquid permeable, fibrous diaphragm for an electrolytic cell wherein the fibers of the diaphragm consist essentially of organic polymer material containing functional groups selected from the group consisting of --COOR, --COOM, --COX, --CN, --CONR'R", --SO 3 M, --SO 2 NH 2 , --PO(OR) 2 , --PO(OM) 2 , --PO(OX) 2 , --OPO(OR) 2 , --OPO(OM) 2 , and --OPO(OX) 2 where R is an aryl or a C 1 to C 10 alkyl group; M is H, an alkali metal or an ammonium group; R' and R" are each independently either H or a C 1 to C 10 alkyl group; and X is Cl or F.

Claim 16

A non-asbestos, liquid permeable, fibrous diaphragm for an electrolytic cell wherein the fibers of the diaphragm consist essentially of organic polymer material containing functional groups selected from the group consisting of --COOR, --COOM, --COX, --CN, --CONR'R", --SO 3 M, --SO 2 NH 2 , --PO(OR) 2 , --PO(OM) 2 , --PO(OX) 2 , --OPO(OR) 2 , --OPO(OM) 2 , and --OPO(OX) 2 where R is an aryl or a C 1 to C 10 alkyl group; M is H, an alkali metal or an ammonium group; R' and R" are each independently either H or a C 1 to C 10 alkyl group; and X is Cl or F.

Claim 17

The diaphragm of claim 13 wherein the functional groups are selected from the group consisting of --COOR, --COX, --CN, and --CONR'R" where R is an aryl or a C 1 to C 10 alkyl group; M is H, an alkali metal or an ammonium group; and R' and R" are each independently either H or a C 1 to C 10 alkyl group; and X is Cl or F.

Claim 18

The diaphragm of claim 13 wherein the organic polymer material is perfluorinated.

Claim 19

The diaphragm of claim 15 further including a perfluorinated diluent polymer material.

Claim 20

A non-asbestos, liquid permeable, fibrous cation exchange diaphragm for an electrolytic cell wherein the fibers of the diaphragm consist essentially of organic polymer material containing functional groups selected from the group consisting of --COOM, --SO 3 M, --PO(OM) 2 , and --OPO(OM) 2 , where M is H, an alkali metal or an ammonium group.

Claim 21

A non-asbestos, liquid permeable, fibrous cation exchange diaphragm for an electrolytic cell wherein the fibers of the diaphragm consist essentially of organic polymer material containing functional groups selected from the group consisting of --COOM, --SO 3 M, --PO(OM) 2 , and --OPO(OM) 2 , where M is H, an alkali metal or an ammonium group.

Claim 22

The diaphragm of claim 17 wherein the functional groups are --COOM where M is H, an alkali metal or an ammonium group.

Claim 23

The diaphragm of claim 17 wherein the organic polymer material is perfluorinated.

Claim 24

The diaphragm of claim 19 further including a perfluorinated diluent polymer material.

Claim 27

The method of claim 21 wherein the organic polymer material is perfluorinated.

Claim 28

The method of claim 22 wherein the thermoplastic organic polymer material is substantially fibrous.

Claim 29

The method of claim 22 wherein the slurry further includes a minor structurally reinforcing amount of a diluent polymer material.

Claim 30

The method of claim 24 wherein the diluent material is a fibrillated polytetrafluoroethylene.

Claim 31

The method of claim 25 wherein the liquid medium comprises water including a minor amount of a nonionic surfactant and a minor amount of a thickening agent.

Claim 32

The method of claim 25 further including covering the foraminous cathode with a removable, temporary mat prior to deposition, thereafter vacuum-depositing the layer of organic polymer material onto the temporary mat and subsequently removing the temporary mat after treatment to bind the organic polymer material.

Claim 33

The method of claim 25 wherein the treatment comprises heating the organic polymer material and fibrillated polytetrafluoroethylene-coated cathode at temperatures beneath the sintering or decomposition temperatures of the fibrillated polytetrafluoroethylene and the organic polymer material having the functional groups to secure the diaphragm upon the cathode.

Claim 34

The method of claim 25 wherein the slurry further includes a pore forming material.

Claim 35

The method of claim 25 wherein the slurry further includes a pore forming material and the thermoplastic organic polymer material is present as a solution of such material.

Claim 36

The method of claim 22 wherein the liquid medium comprises an organic liquid capable of softening the organic polymer material and swelling the polymer material to a substantially similar extent as the organic polymer material swells in an operating cell environment.

Claim 37

The method of claim 31 wherein the organic liquid is selected from the group consisting of N-methylpyrrolidone, propylene carbonate, dimethyl formamide, dimethyl sulfoxide, isopropanol and ethanol.

Claim 38

The method of claim 21 wherein the treatment of the organic polymer material-coated cathode comprises heating the organic polymer material-coated cathode at temperatures and for a time sufficient to bind the organic polymer material.

Claim 39

The method of claim 21 wherein the slurry further includes a pore forming material.

Claim 40

A process for producing chlorine and alkali metal hydroxide in an electrolytic cell comprising: (a) feeding aqueous alkali metal chloride brine into an anolyte compartment of the cell; (b) percolating said brine through an electrolyte permeable, asbestos-free, cation exchange diaphragm consisting essentially of organic polymer material, the organic polymer material comprising fibers containing functional groups selected from the group consisting of --COOM, --SO 3 M, --PO(OM) 2 and --OPO(OM) 2 , where M is an alkali metal, into a catholyte compartment of the cell, said diaphragm dividing the anolyte compartment having an anode therein and the catholyte compartment having a cathode therein; (c) passing an electric current from the anode to the cathode; and (d) recovering chlorine from the anolyte compartment and alkali metal hydroxide from the catholyte compartment.

Claim 41

A process for producing chlorine and alkali metal hydroxide in an electrolytic cell comprising: (a) feeding aqueous alkali metal chloride brine into an anolyte compartment of the cell; (b) percolating said brine through an electrolyte permeable, asbestos-free, cation exchange diaphragm consisting essentially of organic polymer material, the organic polymer material comprising fibers containing functional groups selected from the group consisting of --COOM, --SO 3 M, --PO(OM) 2 and --OPO(OM) 2 , where M is an alkali metal, into a catholyte compartment of the cell, said diaphragm dividing the anolyte compartment having an anode therein and the catholyte compartment having a cathode therein; (c) passing an electric current from the anode to the cathode; and (d) recovering chlorine from the anolyte compartment and alkali metal hydroxide from the catholyte compartment.

Claim 42

The process of claim 35 wherein the cation exchange diaphragm further includes a minor structurally reinforcing amount of unsintered fibrillated polyfluorocarbon.

Claim 43

The process of claim 36 wherein the polyfluorocarbon is polytetrafluoroethylene.

Claim 44

The process of claim 35 wherein the brine feed contains less than 50 parts per billion alkaline earth metal ions and less than 500 parts per billion iodine.