GB2040803A - A method for joining fluorinated polymer cation exchange membranes - Google Patents
A method for joining fluorinated polymer cation exchange membranes Download PDFInfo
- Publication number
- GB2040803A GB2040803A GB7943687A GB7943687A GB2040803A GB 2040803 A GB2040803 A GB 2040803A GB 7943687 A GB7943687 A GB 7943687A GB 7943687 A GB7943687 A GB 7943687A GB 2040803 A GB2040803 A GB 2040803A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fluorinated polymer
- cation exchange
- groups
- exchange membranes
- joining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000012528 membrane Substances 0.000 title claims abstract description 57
- 238000005341 cation exchange Methods 0.000 title claims abstract description 37
- 229920002313 fluoropolymer Polymers 0.000 title claims abstract description 25
- 238000005304 joining Methods 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 15
- 125000000542 sulfonic acid group Chemical group 0.000 claims abstract description 14
- 125000000565 sulfonamide group Chemical group 0.000 claims abstract description 12
- 150000003512 tertiary amines Chemical class 0.000 claims abstract description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims abstract description 4
- 150000003839 salts Chemical class 0.000 claims abstract description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 7
- 229910052708 sodium Inorganic materials 0.000 claims description 7
- 239000011734 sodium Substances 0.000 claims description 7
- 150000001412 amines Chemical class 0.000 claims description 3
- 239000004094 surface-active agent Substances 0.000 claims description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 2
- 229920001577 copolymer Polymers 0.000 claims description 2
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 claims description 2
- 239000006185 dispersion Substances 0.000 claims description 2
- 238000006116 polymerization reaction Methods 0.000 claims description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 2
- 238000007796 conventional method Methods 0.000 abstract description 2
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 18
- 229920000557 Nafion® Polymers 0.000 description 17
- 239000007864 aqueous solution Substances 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- 238000007654 immersion Methods 0.000 description 5
- 238000003825 pressing Methods 0.000 description 4
- 239000002585 base Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- VDZOOKBUILJEDG-UHFFFAOYSA-M tetrabutylammonium hydroxide Chemical compound [OH-].CCCC[N+](CCCC)(CCCC)CCCC VDZOOKBUILJEDG-UHFFFAOYSA-M 0.000 description 3
- 150000003863 ammonium salts Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- NHGXDBSUJJNIRV-UHFFFAOYSA-M tetrabutylammonium chloride Chemical compound [Cl-].CCCC[N+](CCCC)(CCCC)CCCC NHGXDBSUJJNIRV-UHFFFAOYSA-M 0.000 description 2
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910001514 alkali metal chloride Inorganic materials 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 125000001453 quaternary ammonium group Chemical group 0.000 description 1
- 150000003385 sodium Chemical class 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/20—Manufacture of shaped structures of ion-exchange resins
- C08J5/22—Films, membranes or diaphragms
- C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
- C08J5/2218—Synthetic macromolecular compounds
- C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
- C08J5/2237—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds containing fluorine
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
Abstract
A method for joining fluorinated polymer cation exchange membranes is provided, wherein fluorinated polymer cation exchange membranes containing pendent groups of sulfonic acid groups or sulfon amide groups are treated with a tertiary amine, a quarternary ammonium base, or a salt thereof, then a porous hydrophilic fluorinated polymer film is interposed between them, thereafter being heat-pressed. The invention provides more improved joining than conventional methods.
Description
SPECIFICATION
A method for joining fluorinated polymer cation exchange membranes
The present invention relates to a method for joining a fluorinated polymer cation exchange membrane with a fluorinated polymer cation exchange membrane. More specifically, it relates to a joining method fluorinated polymer cation exchange membranes, wherein fluorinated polymer cation exchange membranes containing pendent groups of sulfonic groups or sulfonic amide groups are first treated with a tertiary amine, or base, then a porous hydrophilic fluorinated polymer film is interposed between them, thereafter being heat-pressed.
Joining of cation exchange membranes is of exceeding use industrially. In the industrial utilization of the joining art of cation exchange membranes, there are included, for example, formation of the cation exchange membrane in any desired shape, production of a sufficient size of the cation exchange membrane required for an industrial use when such a large size is difficult to be produced. It is also useful in repairing a tear or a hole of cation exchange membranes which took place during utilization or handling. The present invention provides a joining method of cation exchange membranes which is exceedingly useful industrially. The joining method of the present invention is characterized by interposition of a porous hydrophilic fluorinated polymer film between the cation exchange membranes, then being heat-pressed.The cation exchange membrane used in the present invention contains pendent groups of sulfonic acid groups or sulfon amide groups on, at least, one side of the membrane.
It is known to the art to join cation exchange membranes having pending groups of sulfonic acid groups or sulfon amide groups. For example, the cation exchange membrane is melt-processed by a method described in the Japanese Patent Publication (non-examined) No. 49394/1975. The method, nevertheless, does not provide a sufficient joining strength.
In orderto improve a joining method giving increased joining strength, a series of studies have been made by the present inventors and the present invention has been completed. That is, it has now been discovered by the inventors that joining strength can be surprisingly increased by interposing a porous hydrophilicfluorinated polymer film between the cation exchange membranes whose pendent groups of sulfonic acid groups or sulfon amide groups are converted to ammonium salt type, then being heat-pressed.
That is, the portions to be joined of the membranes are preferably heated up to the range of from 100,0 to 300"C, more preferably 150"C to 300"C. The portions so heated up are then pressed under the pressure within the range of from 0.01 to 150
Kg/cm2G to achieve joining of the membranes. In addition to heat-pressing, ultrasonic wave heating, impulse heating and the like may be also employed.
The cation exchange membrane having pendent groups of sulfonic acid groups or sulfon amide groups on, at least, one side of the membrane may be preferably used in the present invention. Examples of the cation exchange membrane are membranes having sulfonic acid groups or sulfon amide groups on both sides of the membrane, membranes whose one side is treated with ethylene diamine, membrane, or the like. As a diaphragm for twochamber orthree-chamber ion exchange electrolysis method of an aqueous alkali metal chloride solution, perfluorocarbon cation exchange membranes are useful, which normally contain pendent groups of sulfonic acid groups, sulfon amide groups, carboxylic acid groups or the like as cation exchange groups.
As perfluorocarbon cation exchange membranes, there are included, for example, "Nafion" #215, #290, #295, #315, #415, #417, #427 and the like, which are sold by E.l. Du Pont de Nemours & BR<
Company.
Porous fluorinated polymer film includes membranes having pendent groups of sulfonic acid groups or sulfon amide groups. The membranes contain pendent groups of sulfonic acid groups or sulfon amide groups on, at least, one side of the membrane, and the pendent groups are converted to ammonium salt type by treatment with a tertiary amine, a quaternary ammonium base, or a salt of the foregoing amine or base, prior to heat-pressing.
Examples of porous fluorinated polymer membranes are "Nafion" #701, #710, and the like, sold by E.l. Du Pont de Nemours & Company.
Porous fluorinated polymer films further include a film of a polymer or a copolymer obtained by polymerization of 4-fluoroethylene, 6fluoropropylene, perfluoroalkylvinylether; and poly3-fluorochloroethylene, polyfluorovinylidene and the like.
The hydrophilic characteristic is afforded to the porous fluorinated polymer film by corona discharge or the treatment with activated sodium such as metallic sodium, sodium dispersion, stabilized metallic sodium and the like. The fluorinated polym er film subjected to hydrophilic treatment with a surface active agent such as fluoride surface active agents may be also employed. The fluorinated polymer film hydrophile-treated with a titanium compound such as potassium titanate, titanium oxide and the like may be effectively used.
It is not made clear why the joining strength can be markedly improved by the interposition of a porous hydrophilic fluorinated polymer film, then being heat-pressed, but, is surmised as below; That is, heat-melted cation exchange membranes, upon heat-pressing, penetrate into perforations then solidify in the perforations. By such, as it were, an "anchor shape" joining effect, a superior joining strength is achieved as compared with a conventional method.
The present invention will be explained in more detail by way of examples that follow, which examples are not construed to limit the scope of the present invention.
Example 1
"Nafion #315" having pendent groups of sulfonic acid groups, produced and sold by E.l. Du Pont de
Nemours & Co., was converted to NA+ type, then treated with a 50% methanol aqueous solution containing tetra(n-butyl) ammonium chloride. On the other hand, "Nafion #701" having pendent groups of sulfonic acid groups was converted to H+ type, and then treated with a 50% methanol aqueous solution containing tetra(n-butyl) ammonium hydroxide. Between two pieces of"Nafion #315" so treated, was "Nafion #701" sandwiched, then heat-pressed at 240"C under the pressure of 15 kg/cm2G. Joining strength of the joined membranes was 8.0 kg/cm2G. The so obtained joined membranes was immersed in depleted brine removed from a mercury electrolytic cell. Peeling off of the joined portion was not observed even after 11 months.
Example 2
With the exception that "Nafion #710" was employed in the place of "Nafion #701", experiment was carried out in the similar manner to that in
Example 1. Joining strength of the membranes joined was 8.5 kg/cm2G. Immersion test was conducted for 11 months according to Example 1. No tear of the joined portion was observed.
Example 3
The experiment was effected in the similar fashion to that of Example 1, excepting that "Nafion #215" in the place of "Nafion #315" was used. Immersion test was performed similarly to Example 1. Even after 6 months, no peeling off could be seen.
Example 4
Similar experiment to that of Example 1 was effected, with the exception that a cation exchange membrane containing pendent groups of carboxylic acids obtained by modifying one side of the membrane "Nafion #415" was employed. Immersion test was continued for 3 months but no tear of the joined portion took place.
Example 5
The experiment was performed in the similar fashion to that of Example 1, excepting that both sides of a porous poly-4-fluoroethylene film were treated by corona discharge, then interposed between the cation exchange membranes treated.
Immersion test was effected for 3 months but no peeling off occured.
Example 6
The experiment was conducted similarly to Example 1, excepting that a porous polytetrafluoroethylene film whose both sides were treated with a stabilized metallic sodium (tradename, "TET
RECCHI"'), produced by JUNKOSHA K.K., was interposed between treated cation exchange membranes. The obtained joined membrane was immersed for 3 months. No tear of the joined portion took place.
Comparative Example 1
A Na+ type cation exchange membrane "Nafion #315" was treated with a 50% methanol aqueous solution containing tetra(n-butyl) ammonium chloride. Two pieces of the so treated membranes were heat-pressed at 240 C under the pressure of 15 kg/cm2G. Joining strength of the joined membranes was 4.2 kg/cm2G. Immersion test was conducted similarly to Example 1. After 3 months peeling off of the joined portion was observed.
Comparative Example 2
A H+ type cation exchange membrane, "Nafion #315" was treated with a 50% methanol aqueous solution containing a tetra(n-butyl) ammonium hydroxide. Two pieces of the membranes so treated were heat-pressed at 240do under the pressure of 15 kg/cm2G. The obtained joined membranes showed the joining strength of 4.5 kg/cm2G.
Comparative Example 3
"Nafion #315", a Na+ type cation exchange membrane was treated with a 50% methanol aqueous solution containing tetra(nbutyl)ammonium/chloride. On the other hand, "Nafion #415", a H+ type cation exchange membrane was treated with a 50% methanol aqueous solution containing tetra(n-butyl) ammonium hydroxide. The non-porous "Nafion #415" so treated was sandwiched between two pieces of "Nafion #315" treated, then subjected to heat-pressing in the similar fashion as in Example 1. Joining strength was 4.7 kg/cm2G.
Claims (5)
1. A method for joining fluorinated polymer cation exchange membranes which comprises treating fluorinated polymer cation exchange membranes containing pendent groups of sulfonic acid groups or sulfon amide groups with a tertiary amine, a quarternary ammonium base, or a salt of the amine or base, then interposing a porous hydrophilic fluorinated polymer film between so treated cation exchange membranes, thereafter heatpressing them.
2. The method of Claim 1, wherein said porous hydrophilic fluorinated polymer film is a porous cation exchange membrane containing pendent groups of sulfonic acid groups or sulfon amide groups, whose sulfonic acid groups of sulfon amide groups are treated with a tertiary amine, a quarternary ammonium base, or a salt of the amine or base.
3. The method of Claim 1,wherein said porous hydrophilic fluorinated polymer film comprises a film of a olymer or a copolymer obtained by polymerization of 4fluoroethylene, 6fluoropropylene, perfluoroalkylvinylether; or poly-3fluorochloroethylene or polyfluorovinylidene.
4. The method of Claim 1,wherein said porous hydrophilic fluorinated polymer film comprises a porous fluorinated polymer film subjected to hydrophilic treatment by corona discharge, or treatment with metallic sodium, sodium dispersion, stabilized metallic sodium, potassium titanate, titanium oxide or surface active agents.
5. A method for joining fluorinated polymer cation exchange membranes substantially as described in any one of the examples herein.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16289678A JPS5586535A (en) | 1978-12-26 | 1978-12-26 | Method of bonding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2040803A true GB2040803A (en) | 1980-09-03 |
Family
ID=15763293
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7943687A Withdrawn GB2040803A (en) | 1978-12-26 | 1979-12-19 | A method for joining fluorinated polymer cation exchange membranes |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5586535A (en) |
| DE (1) | DE2951475A1 (en) |
| FR (1) | FR2455615A1 (en) |
| GB (1) | GB2040803A (en) |
| IT (1) | IT1164036B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4414338A (en) * | 1978-07-11 | 1983-11-08 | Asahi Kasei Kogyo Kabushiki Kaisha | Cation exchange membrane |
| EP0249316A1 (en) * | 1986-06-10 | 1987-12-16 | Tosoh Corporation | Method for recovering a metal |
| GB2363796A (en) * | 2000-04-17 | 2002-01-09 | Innogy Technology Ventures Ltd | Ion exchange membranes |
-
1978
- 1978-12-26 JP JP16289678A patent/JPS5586535A/en active Pending
-
1979
- 1979-12-19 GB GB7943687A patent/GB2040803A/en not_active Withdrawn
- 1979-12-20 DE DE19792951475 patent/DE2951475A1/en not_active Withdrawn
- 1979-12-24 IT IT51189/79A patent/IT1164036B/en active
- 1979-12-24 FR FR7931572A patent/FR2455615A1/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4414338A (en) * | 1978-07-11 | 1983-11-08 | Asahi Kasei Kogyo Kabushiki Kaisha | Cation exchange membrane |
| EP0249316A1 (en) * | 1986-06-10 | 1987-12-16 | Tosoh Corporation | Method for recovering a metal |
| GB2363796A (en) * | 2000-04-17 | 2002-01-09 | Innogy Technology Ventures Ltd | Ion exchange membranes |
| GB2363796B (en) * | 2000-04-17 | 2002-12-24 | Innogy Technology Ventures Ltd | Process for the preparation of ion exchange membranes |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1164036B (en) | 1987-04-08 |
| FR2455615A1 (en) | 1980-11-28 |
| IT7951189A0 (en) | 1979-12-24 |
| JPS5586535A (en) | 1980-06-30 |
| DE2951475A1 (en) | 1980-07-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3969285A (en) | Heat-treated fluorocarbon sulfonylamine cation permselectivity | |
| US4090931A (en) | Anode-structure for electrolysis | |
| CA1046457A (en) | Electrolytic diaphragms, and method of electrolysis using the same | |
| NO843527L (en) | PROCEDURE FOR PREPARING A MEMBRANE OF POOD POLYMES | |
| JPS6134515B2 (en) | ||
| US4147844A (en) | Reverse-side treatment of fabric reinforced membranes | |
| US4670125A (en) | Production of bipolar membranes | |
| JPH08506613A (en) | Single film membrane, its manufacturing method and its use | |
| GB2052382A (en) | A process for joining fluorinated polymer cation exchange membrane | |
| GB1468694A (en) | Melt processing of fluorinated polymers | |
| CA2571502A1 (en) | Hydrophilic membranes | |
| CA1208867A (en) | Method of regenerating cation exchange membrane | |
| GB2040803A (en) | A method for joining fluorinated polymer cation exchange membranes | |
| US4030988A (en) | Process for producing halogen and metal hydroxides with cation exchange membranes of improved permselectivity | |
| EP1421126B1 (en) | Process for preparing graft copolymer membranes | |
| US4026783A (en) | Electrolysis cell using cation exchange membranes of improved permselectivity | |
| GB2040222A (en) | A method for joining a fluorinated polymer film and a fluorinated polymer cation exchange membrane | |
| US4154909A (en) | Process for producing cation exchange membrane by treatment of fluorinated polymer containing sulfonyl halide groups with amine and vinyl monomer | |
| US4376140A (en) | Method for producing a fluorinated copolymer membrane | |
| US4339549A (en) | Process for fusion bonding of fluorocarbon type polymers which comprises counter-ion substitution prior to fusion bonding | |
| US4076571A (en) | Method of bonding electrolytic diaphragms of perfluorosulfonic acid resins | |
| US4316790A (en) | Cation exchange membranes | |
| US4284460A (en) | Heat sealing untreated sulfonamide-type cation exchange membranes | |
| US4366262A (en) | Method for catalyzed conversion of perfluorocarbon cationic exchange functionality with SF4 | |
| GB2052381A (en) | A process for joining fluorinated polymer cation exchange membrane |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |