Claims
- 1. A process for preparing a heterogeneous anion exchange membrane having enhanced current efficiency and reduced reverse diffusion of protons, which comprises:
- (a) treating from about 1 to 80% of the thickness of a carboxylate membrane made of a copolymer having repeating units of the formula; ##STR12## wherein X is F or CF.sub.3, l is an integer of from 0 to 5, m is 0 or 1, n is an integer of from 1 to 5, and p/q is from 4 to 16, and R is a lower alkyl group, with a mineral acid which is effective as an acid catalyst for hydrolysis; or a base which is effective as a base catalyst for hydrolysis; and
- (b) reacting the treated membrane with
- (i) a lower dialkylamine of the formula: ##STR13## wherein R.sup.1 and R.sup.2 are lower alkyl groups; or (ii) a diamine of the formula: ##STR14## wherein R.sup.6 is a hydrogen atom or a lower alkyl group, each of R.sup.7 and R.sup.8 is a lower alkyl group, or R.sup.6 and R.sup.7 together form a polyethylene group of the formula (CH.sub.2).sub.a, wherein a is an integer of 2 or 3; or
- (iii) a diamine of the formula: ##STR15## wherein R.sup.9 is a hydrogen atom or a lower alkyl group, each of R.sup.10 and R.sup.11 is a lower alkyl group, or R.sup.9 and R.sup.10 together form a polymethylene chain of the formula CH.sub.2).sub.2, wherein c is an integer of 2 or 3, and b is an integer of from 3 to 7; to thereby form a carboxylic acid amide membrane, which is treated with a reducing agent to form a corresponding amine membrane, which is then alkylated with a lower alkyl group to form a quaternary ammonium group-containing membrane.
- 2. The process according to claim 1, wherein the acid or base treatment is applied to one side or both sides of the membrane.
- 3. The process according to claim 1, wherein the acid treatment is conducted by using hydrochloric acid as the acid.
- 4. The process according to claim 1, wherein the acid treatment is conducted by using sulfuric acid as the acid.
- 5. The process according to claim 1, wherein the acid treatment is conducted by using nitric acid as the acid.
- 6. The process according to claim 1, wherein the base treatment is conducted by using aqueous ammonia as the base.
- 7. The process according to claim 1, wherein the base treatment is conducted by using sodium hydroxide as the base.
- 8. The process according to claim 1, wherein said quaternary ammonium group has the formula: ##STR16## wherein each of R.sup.1, R.sup.2 and R.sup.3 is a lower alkyl group, or R.sup.1 and R.sup.2 together form a tetramethylene group or a pentamethylene group, and Z.sup.- is a counter ion for the quaternary ammonium ion, selected from the group consisting of a halogen anion, NO.sub.3.sup.-, 1/2(SO.sub.4.sup.2-), BF.sub.4.sup.-, SbCl.sub.6.sup.-, .sup.- OSO.sub.2 R.sup.5 and .sup.- OCOR.sup.5 wherein R.sup.5 is a lower alkyl group, a phenyl group or a lower perfluoroalkyl group.
- 9. The process according to claim 1, wherein said quaternary ammonium group has the formula: ##STR17## wherein R.sup.6 is a hydrogen atom or a lower alkyl group, each of R.sup.7 and R.sup.8 is a lower alkyl group, or R.sup.6 and R.sup.7 together form a polymethylene chain of the formula (CH.sub.2).sub.a wherein a is an integer of 2 or 3, R.sup.3 is a lower alkyl group, Z.sup.- is a counter ion for the quaternary ammonium ion, selected from the group consisting of a halogen anion, NO.sub.3.sup.-, 1/2(SO.sub.4.sup.2-), BF.sub.4.sup.-, SbCl.sub.6.sup.-, .sup.- OSO.sub.2 R.sup.5 and .sup.- OCOR.sup.5, wherein R.sup.5 is a lower alkyl group, a phenyl group or a lower perfluoroalkyl group.
- 10. The process according to claim 1, wherein said quaternary ammonium group has the formula: ##STR18## wherein R.sup.9 is a hydrogen atom or a lower alkyl group, each of R.sup.10 and R.sup.11 is a lower alkyl group, or R.sup.9 and R.sup.10 together form a polymethylene group of the formula (CH.sub.2).sub.c wherein c is an integer of 2 or 3, b is an integer of from 3 to 7, R.sup.3 is a lower alkyl group, and Z.sup.- is a counter ion for the quaternary ammonium ion, selected from the group consisting of a halogen anion, NO.sub.3.sup.-, 1/2(SO.sub.4.sup.2-), BF.sub.4.sup.-, SbCl.sub.6.sup.-, .sup.31 OSO.sub.2 R.sup.5 and .sup.- OCOR.sup.5, wherein R.sup.5 is a lower alkyl group, a phenyl group or a lower perfluoroalkyl group.
- 11. The process according to claim 1, wherein said base is an alkali metal hydroxide or an alkaline earth metal hydroxide.
- 12. The process according to claim 1, wherein said anion exchange membrane has an ion exchange capacity of from 0.16 to 30 meq/g of dry membrane.
- 13. The process according to claim 12, wherein said anion exchange membrane has an ion exchange capacity of from 0.5 to 2.8 meq/g of dry membrane.
- 14. The process according to claim 1, wherein said anion exchange membrane has a thickness of from 40 to 500 .mu.m.
- 15. The process according to claim 1, wherein said carboxylate membrane is made of methyl carboxylate.
- 16. The process according to claim 1, wherein said dialkylamine of clause b)i) is selected from the group consisting of dimethylamine, diethylamine, dipropylamine and methyl ethyl amine.
- 17. The process according to claim 1, wherein said diamine of clause b)ii) is selected from the group consisting of N,N-dimethylkethylenediamine, N,N,N'-trimethylethylenediamine, N-methylpiperazine and N-propylpiperazine.
- 18. The process according to claim 1, wherein said diamine of clause (b)(iii) is selected from the group consisting of N,N-dimethylpropanediamine, N,N,N'-trimethylpropanediamine, N,N-dimethyl-butylenediamine, N,N,N'-trimethylbutylenediamine and N,N-diethylpropanediamine.
- 19. The process according to claim 1, wherein said carboxylic acid amide membrane is reduced with lithium aluminum hydride or diborane.
- 20. The process according to claim 1, wherein said corresponding amine membrane is alkylated with an alkylating agent selected from the group consisting of methyl iodide, ethyl bromide, n-propyl bromide, trimethyloxonium fluoroborate, triethyloxonium fluoroborate, trimethyl oxonium hexachloroantimonate and methyl trifluoromethanesulfonate.
- 21. An anion exchange membrane produced by the process of claim 1.
Priority Claims (2)
Number |
Date |
Country |
Kind |
60-228290 |
Oct 1985 |
JPX |
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60-228291 |
Oct 1985 |
JPX |
|
Parent Case Info
This application is a continuation of application Ser. No. 918,061 filed on Oct. 14, 1986, now abandoned.
US Referenced Citations (6)
Continuations (1)
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Number |
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Parent |
918061 |
Oct 1986 |
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