Curable compositions and membranes

Abstract

A composition comprising: a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7. Also described are a process for making composite membranes and the resultant membranes.

Claims

1. A curable composition comprising: a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7.

2. The composition according to claim 1 wherein the molar ratio of component c) to a) is at least 0.9.

3. The composition according to claim 1 wherein the crosslinking agent has a melting point below 80 C., when measured at atmospheric pressure.

4. The composition according to claim 1 wherein the anionic group is selected from sulpho, carboxy and phosphato groups.

5. The composition according to claim 1 wherein the anionic group is a sulpho group.

6. The composition according to claim 1 which comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent.

7. The composition according to claim 1 wherein the said crosslinking agent has a solubility in water of less than 0.03 mol/l, when measured at 25 C.

8. The composition according to claim 1 wherein the weight ratio of component b) to component a) is greater than 0.3.

9. The composition according to claim 1 which further comprises 0.05 to 10 wt % of photoinitiator.

10. The composition according to claim 1 wherein the said crosslinking agent comprises at least two groups selected from acrylamide groups.

11. The composition according to claim 1 wherein the said tertiary amine has a melting point below 50 C.

12. The composition according to claim 1 wherein the said tertiary amine is selected from tri(C.sub.1-12-alkyl)amines and heterocyclic N(C.sub.1-12-alkyl) amines.

13. The composition according to claim 1 wherein the said curable compound has a MW of less than 1000 Dalton and/or said crosslinking agent has a MW of less than 1000 Dalton.

14. The composition according to claim 1 wherein the said tertiary amine has a MW of less than 400 Dalton.

15. The composition according to claim 1 which has a viscosity of below 12 Pa.s when measured at 50 C.

16. A process for preparing a membrane comprising the following steps: a) applying a curable composition to a support; and b) curing the composition to form a membrane; wherein the composition is as defined in claim 1.

17. The process according to claim 16 wherein the curing is performed by a process comprising irradiating the composition for less than 30 seconds.

18. A cation exchange membrane including a cured composition comprising, prior to curing, a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7.

19. An electrodialysis or reverse electrodialysis unit, a flow through capacitor device, an electrodeionization module, a continuous electrodeionization module, a fuel cell, a diffusion dialysis apparatus, a membrane distillation module or a membrane electrode assembly comprising one or more membranes including a cured composition comprising, prior to curing, a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7.

20. The composition according to claim 1 wherein: (a) the crosslinking agent has (i) a melting point below 80 C., when measured at atmospheric pressure; and (ii) a solubility in water of less than 0.03 mol/l, when measured at 25 C.; (b) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (c) the composition further comprises 0.05 to 10 wt % of photoinitiator; (d) the weight ratio of component b) to component a) is greater than 0.3; and (e) the anionic group is a sulpho group.

21. The composition according to claim 1 wherein: (a) the said tertiary amine has a melting point below 50 C.; (b) the said tertiary amine is selected from tri(C.sub.1-12-alkyl)amines and heterocyclic N(C.sub.1-12-alkyl) amines; and (c) the said curable compound has a MW of less than 1000 Dalton; (d) the said crosslinking agent has a MW of less than 1000 Dalton; and (e) the said tertiary amine has a MW of less than 400 Dalton.

22. The composition according to claim 1 wherein: (a) the crosslinking agent has a melting point below 80 C., when measured at atmospheric pressure; (b) the anionic group is a sulpho group; (c) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (d) the said crosslinking agent has a solubility in water of less than 0.03 mol/l, when measured at 25 C., and has a MW of less than 1000 Dalton; (e) the weight ratio of component b) to component a) is greater than 0.3; and (f) the composition comprises 0.05 to 10 wt % of photoinitiator; (g) the said tertiary amine is selected from tri(C.sub.1-12-alkyl)amines and heterocyclic N(C.sub.1-12-alkyl) amines and has a melting point below 50 C. and a MW of less than 400 Dalton; and (h) the said curable compound has a MW of less than 1000 Dalton.

23. The process according to claim 16 wherein: (a) the composition comprises a crosslinking agent having a melting point below 80 C., when measured at atmospheric pressure; (b) the anionic group is a sulpho group; (c) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (d) the said crosslinking agent has a solubility in water of less than 0.03 mol/l, when measured at 25 C. and has a MW of less than 1000 Dalton; (e) the weight ratio of component b) to component a) is greater than 0.3; (f) the composition comprises 0.05 to 10 wt % of photoinitiator; (g) the said tertiary amine is selected from tri(C.sub.1-12-alkyl)amines and heterocyclic N(C.sub.1-12-alkyl) amines and has a melting point below 50 C. and a MW of less than 400 Dalton; and (h) the said curable compound has a MW of less than 1000 Dalton.

24. A cation exchange membrane including a cured composition comprising, prior to curing, a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7, wherein (e) the composition comprises a crosslinking agent having a melting point below 80 C., when measured at atmospheric pressure; (f) the anionic group is a sulpho group; (g) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (h) the said crosslinking agent has a solubility in water of less than 0.03 mol/l, when measured at 25 C. and has a MW of less than 1000 Dalton; (i) the weight ratio of component b) to component a) is greater than 0.3; (j) the composition comprises 0.05 to 10 wt % of photoinitiator; (k) the said tertiary amine is selected from tri(C.sub.1-12-alkyl)amines and heterocyclic N(C.sub.1-12-alkyl) amines and has a melting point below 50 C. and a MW of less than 400 Dalton; and (l) the said curable compound has a MW of less than 1000 Dalton.

25. A cation exchange membrane including a cured composition comprising, prior to curing, a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7, wherein (e) the crosslinking agent has (i) a melting point below 80 C., when measured at atmospheric pressure; and (ii) a solubility in water of less than 0.03 mol/l, when measured at 25 C.; (f) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (g) the composition further comprises 0.05 to 10 wt % of photoinitiator; (h) the weight ratio of component b) to component a) is greater than 0.3; and (i) the anionic group is a sulpho group.

26. An electrodialysis or reverse electrodialysis unit, a flow through capacitor device, an electrodeionization module, a continuous electrodeionization module, a fuel cell, a diffusion dialysis apparatus, a membrane distillation module or a membrane electrode assembly comprising one or more membranes including a cured composition comprising, prior to curing, a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7, wherein (e) the composition comprises a crosslinking agent having a melting point below 80 C., when measured at atmospheric pressure; (f) the anionic group is a sulpho group; (g) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (h) the said crosslinking agent has a solubility in water of less than 0.03 mol/l, when measured at 25 C. and has a MW of less than 1000 Dalton; (i) the weight ratio of component b) to component a) is greater than 0.3; (j) the composition comprises 0.05 to 10 wt % of photoinitiator; (k) the said tertiary amine is selected from tri(C.sub.1-12-alkyl)amines and heterocyclic N(C.sub.1-12-alkyl) amines and has a melting point below 50 C. and a MW of less than 400 Dalton; and (l) the said curable compound has a MW of less than 1000 Dalton.

27. An electrodialysis or reverse electrodialysis unit, a flow through capacitor device, an electrodeionization module, a continuous electrodeionization module, a fuel cell, a diffusion dialysis apparatus, a membrane distillation module or a membrane electrode assembly comprising one or more membranes including a cured composition comprising, prior to curing, a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7, wherein (e) the crosslinking agent has (i) a melting point below 80 C., when measured at atmospheric pressure; and (ii) a solubility in water of less than 0.03 mol/l, when measured at 25 C.; (f) the composition comprises at least 5 wt % and less than 70 wt % of the said crosslinking agent; (g) the composition further comprises 0.05 to 10 wt % of photoinitiator; (h) the weight ratio of component b) to component a) is greater than 0.3; and (i) the anionic group is a sulpho group.

Description

EXAMPLES 1 TO 15 AND COMPARATIVE EXAMPLES 1 AND 2

(1) Compositions Ex 1 to Ex 15 and comparative compositions CE1 and CE2 were prepared by mixing the ingredients expressed as wt % shown in Tables 6, 7 and 8.

(2) The resultant compositions were applied to an aluminium support using a 150 m wire wound bar, at a speed of approximately 5 m/min, by hand, followed by application of a non-woven support (Novatexx 2226-14E). The non-woven support was completely soaked with the composition and subsequently leveled using a 4 micrometer wire wound rod coater. The temperature of the compositions was about 20 C. (ambient temperature) except where indicated differently.

(3) A membrane was prepared by curing the coated support using a Light Hammer LH6 from Fusion UV Systems fitted with a D-bulb working at 100% intensity with a speed of 30 m/min (single pass). The exposure time was 0.47 seconds.

(4) After curing, the membrane was stored in a 0.1 M NaCl solution for at least 12 hours.

(5) TABLE-US-00006 TABLE 6 Cmp Ex1 Ex2 Ex3 Ex4 Ex5 Ex6 Ex7 a) AMPS 36.8 27.8 37.3 36.2 41.2 33.3 35.9 b) TCD 27.1 0 0 0 0 0 0 CD536 0 21.9 29.3 28.1 32.0 26.0 27.9 c) BIm 22.1 0 22.3 0 0 20.0 0 MIm 0 11.0 0 0 0 0 0 TEA 0 0 0 17.4 19.9 0 0 Epip 0 0 0 0 0 0 19.6 d) DMSO 13.0 38.5 0 0 0 0 0 MeOH 0 0 10.4 17.7 0 20.0 16.0 Acetone 0 0 0 0 6.1 0 0 e) HDMAP 0.5 0.4 0.6 0.5 0.6 0.5 0.5 Genorad 0.5 0.4 0.1 0.1 0.2 0.2 0.1 Molar ratio c)/a) 1.00 1.00 1.00 0.99 0.99 1.00 1.00 (%) 90.2 89.8 92.1 90.7 89.2 90.0 90.1 ER (ohm .Math. 3.4 3.3 3.6 3.8 3.5 3.9 4.7 cm.sup.2)

(6) TABLE-US-00007 TABLE 7 Cmp Ex8 Ex9 Ex10 Ex11 Ex12 Ex13 Ex14 a) AMPS 44.5 44.5 44.5 38.8 40.6 38.8 40.6 b) MBA 16.0 16.0 16.0 0 0 0 0 SR259 8.3 0 0 0 0 0 0 TCD 0 8.3 0 0 0 0 0 CD536 0 0 8.3 30.2 31.5 30.2 31.5 c) MIm 17.7 17.7 17.7 0 0 0 0 TEA 0 0 0 18.7 15.1 18.7 15.1 d) Water 12.5 12.5 0 0 0 0 0 MeOH 0 0 12.5 11.6 12.1 0 0 Acetone 0 0 0 0 0 11.6 12.1 e) HDMAP 0.7 0.7 0.7 0.6 0.6 0.6 0.6 Genorad 0.3 0.3 0.3 0.1 0.1 0.1 0.1 Viscosity 213 387 (mPa .Math. s) Molar ratio c)/a) 1.00 1.00 1.00 0.99 0.76 0.99 0.76 (%) 90.4 91.3 89.2 92.3 93.5 93.4 93.5 ER (ohm .Math. 5.8 5.3 5.6 4.7 5.7 5.2 5.3 cm.sup.2)

(7) The composition of Ex8, Ex9 and Ex10 were dissolved at a temperature of 90 C. and coated at a temperature of 65 C.

(8) TABLE-US-00008 TABLE 8 Cmp Ex15 CE1 CE2 a) AMPS 37.5 37.5 43.2 b) MBA 0 0 16.3 SR259 0 0 0 TCD 28.1 28.1 0 c) Blm 22.5 0 0 d) Water 0 0 15.2 MeOH 11.2 33.7 0 IPA 0 0 15.7 e) HDMAP 0.6 0.6 0.5 Genorad 0.1 0.1 0.5 LiOHH.sub.2O 0 0 8.6 Viscosity (mPa .Math. s) 371 >10.sup.5 Molar ratio c)/a) 1.00 0 0 (%) 89.7 93.2 ER (ohm .Math. cm.sup.2) 3.8 3.6

(9) Cmp is an abbreviation for component, Ex is an abbreviation for Example and CE is an abbreviation for Comparative Example.

(10) The viscosity of composition of CE1 was too high to achieve a defect free coating layer (no membrane could be made).

(11) CE2 required the use of LiOH.H.sub.2O to obtain a homogeneous composition which is not preferred.

(12) A membrane made with SR259 as the only crosslinking agent showed good initial properties but was less stable at pH4 and pH8 than membranes comprising a crosslinking agent that had a solubility in water of less than 0.03 mol/l.

(13) The (%) and ER of a reference membrane (CMX of Astom, Japan) were measured and were found to be 95.3% and 4.1 ohm.Math.cm.sup.2.