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 of the Formula (1) comprising at least two (meth)acrylic groups and a sulphonic acid group: ##STR00005## wherein: R1 and R2 are each independently H or methyl; R3 and R4 are each independently H or alkyl, or R3 and R4 together with the N atoms to which they are attached and Y form an optionally substituted 6- or 7-membered ring; and Y is an optionally substituted and optionally interrupted alkylene or arylene group; provided that the compound of Formula (1) has 1, 2, 3 or 4 sulphonic acid groups; and having a molecular weight which satisfies the equation:
MW<(300+300n) wherein: MW is the molecular weight of the said curable compound of the Formula (1); 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 of the Formula (1); 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 0.5.

2. The ion exchange membrane according to claim 1 wherein the composition further comprises a radical initiator.

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

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

5. The ion exchange membrane according to claim 1 comprising a structural unit of Formula (1): ##STR00006## wherein: R.sub.1 and R.sub.2 are each independently H or methyl; R.sub.3 and R.sub.4 are each independently H or alkyl, or R.sub.3 and R.sub.4 together with the N atoms to which they are attached and Y form an optionally substituted 6- or 7-membered ring; and Y is an optionally substituted and optionally interrupted alkylene or arylene group; provided that the structural unit of Formula (1) has 1, 2, 3 or 4 sulphonic acid groups.

6. A process for preparing an ion exchange membrane comprising the following steps: a) applying a composition to a support; and b) curing the composition to form an ion exchange membrane; wherein the composition comprises: (i) a curable compound of the Formula (1) comprising at least two (meth)acrylic groups and a sulphonic acid group: ##STR00007## wherein: R1 and R2 are each independently H or methyl; R3 and R4 are each independently H or alkyl, or R3 and R4 together with the N atoms to which they are attached and Y form an optionally substituted 6- or 7-membered ring; and Y is an optionally substituted and optionally interrupted alkylene or arylene group; provided that the compound of Formula (1) has 1, 2, 3 or 4 sulphonic acid groups; and having a molecular weight which satisfies the equation:
MW<(300+300n) wherein: MW is the molecular weight of the said curable compound of the Formula (1); 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 of the Formula (1); 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 0.5.

7. The process according to claim 6 wherein the curing is performed using electron beam or UV radiation.

8. The process according to claim 6 wherein the composition is applied continuously to a moving support by means of a manufacturing unit comprising a composition application station, an irradiation source for curing the composition, an ion exchange membrane collecting station and a means for moving the support from the composition application station to the irradiation source and to the ion exchange membrane collecting station.

9. 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.

10. The ion exchange membrane according to claim 5 wherein the composition further comprises a radical initiator and water or a mixture comprising water and a water-miscible organic solvent.

11. The ion exchange membrane according to claim 1 wherein the composition further comprises a radical initiator and water or a mixture comprising water and a water-miscible organic solvent and component (ii) further comprises an anionic group.

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 5.

13. The ion exchange membrane according to claim 1 wherein the composition further comprises: (iii) a curable compound comprising at least two (meth)acrylic groups and being free from sulphonic acid groups; (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).

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) leveled 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.