Curable compositions and membranes

Abstract

A membrane obtainable from curing a composition comprising: (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation:
MW<(300+300n) wherein: MW is the molecular weight of the said curable compound; and n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound; and optionally (ii) a curable compound having one ethylenically unsaturated group; wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.

Claims

1. An ion exchange membrane obtainable from curing a composition comprising: (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation:
MW<(300+300n) wherein: MW is the molecular weight of the said curable compound; and n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound; optionally (ii) a curable compound having one ethylenically unsaturated group; optionally (iii) a curable compound comprising at least two (meth)acrylic groups and being free from sulphonic acid groups; optionally (iv) a radical initiator; and (v) a solvent; wherein the composition comprises: (a) 2 to 80 wt % of component (i), 1 to 70 wt % of component (ii), 0 to 40 wt % of component (iii), 0 to 10 wt % of component (iv); and 15 to 70 wt % of component (v); or (b) 5 to 75 wt % of component (i), 0 to 60 wt % of component (ii), 0 to 30 wt % of component (iii), 0.1 to 10 wt % of component (iv); and 20 to 45 wt % of component (v); wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.

2. The ion exchange membrane according to claim 1 wherein the (meth)acrylic groups are independently selected from methacrylate groups, acrylate groups, methacrylamide groups and acrylamide groups.

3. The ion exchange membrane according to claim 1 wherein the solvent comprises water or a mixture comprising water and a water-miscible organic solvent.

4. The ion exchange membrane according to claim 1 wherein the (meth)acrylic groups in component (i) are (meth)acrylamide groups.

5. The ion exchange membrane according to claim 1 wherein component (ii) further comprises an anionic group.

6. The ion exchange membrane according to claim 1 wherein the molecular weight of the curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group satisfies the equation:
MW<(200+200n).

7. The ion exchange membrane according to claim 1 wherein the composition comprises at most 10 wt % of compounds comprising one or more methacrylic groups.

8. The ion exchange membrane according to claim 1 wherein the composition is free from divinyl benzene and derivatives thereof.

9. The ion exchange membrane according to claim 1 wherein the composition is free from styrene and derivatives thereof.

10. The ion exchange membrane according to claim 1 wherein the composition is free from dyes and pigments.

11. The ion exchange membrane according to claim 1 wherein the total amount of components (i)+(ii) is 58 to 70 wt %.

12. 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 polymeric ion exchange membranes according to claim 1.

13. 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 polymeric ion exchange membranes according to claim 11.

Description

EXAMPLES 1 TO 7 AND COMPARATIVE EXAMPLES 1 TO 7

(1) Compositions Ex 1 to Ex 7 and comparative compositions CE1 to CE7 were prepared by mixing the ingredients expressed as wt % shown in Tables 1 and 2.

(2) The resultant compositions were applied to an aluminium underground carrier using a 150 m wire wound bar, at a speed of approximately 5 m/min, by hand, followed by application to a non-woven support (Novatexx 2226-14E) levelled using a 4 micrometer wire wound rod coater. The temperature of the compositions was 20-60 C.

(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-00001 TABLE 1 Ingredient Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 AMPS 24.6 30.8 37.4 15.9 16.2 0 0 BAMPS 37.3 23.3 28.2 45.0 46.4 62.6 67.2 Water 37.1 44.9 33.4 28.2 36.4 36.4 31.8 LiOHH.sub.2O 0 0 0 9.9 0 0 0 Genorad 16 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Darocur 1173 0.5 0.5 0.5 0.5 0.5 0.5 0.5 MF 0.53 0.36 0.36 0.68 0.68 1.0 1.0 CD (mmol/g) 2.1 1.5 1.5 2.6 2.6 3.6 3.6 IEC (meq/g) 4.0 4.2 4.2 3.8 3.9 3.6 3.6 Results PS ( (%)) 95.5 89.8 92.5 95.3 95.9 97.1 97.2 ER (ohm .Math. cm.sup.2) 4.1 2.0 2.2 3.2 3.1 4.1 3.9 Membrane % weight 0.3 0.8 0.9 0.3 0.1 0.1 0.2 loss after ultrasonic treatment

(6) TABLE-US-00002 TABLE 2 Ingredient CE1 CE2 CE3 CE4 CE5 CE6 CE7 AMPS 50.3 52.1 45.3 32.1 39.3 44.2 25.8 MBA 12.0 0 0 0 0 0 0 BAHP 0 0 0 0 0 0 39.0 BAMPS 0 10.2 17.1 12.1 14.8 16.7 0 Water 28.4 36.7 36.6 54.8 44.9 38.1 10.6 IPA 8.3 0 0 0 0 0 18.5 LiOHH.sub.2O 0 0 0 0 0 0 5.1 Genorad 16 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Darocur 1173 0.5 0.5 0.5 0.5 0.5 0.5 0.5 MF 0.24 0.13 0.22 0.22 0.22 0.22 0.60 CD (mmol/g) 1.2 0.6 1.0 1.0 1.0 1.0 2.8 IEC (meq/g) 3.8 4.6 4.4 4.4 4.4 4.4 1.9 Results PS ( (%)) 94.1 86.6 92.9 79.3 87.8 90.8 89.9 ER (ohm .Math. cm.sup.2) 3.2 2.3 2.8 1.1 1.4 1.4 10.4 Membrane % weight 3.9 8.0 6.9 7.9 6.9 11.6 0.1 loss after ultrasonic treatment Note: An ER value higher than 10 is considered too high for most applications; the ER is preferably below 5 ohm .Math. cm.sup.2.