Aminated ion exchange resins and production methods thereof
This invention relates to certain novel anion exchange resins and methods of making them. It relates more particularly to aminated cross-linked resin bead polymers containing an inert and/or chloromethylated core, and an aminated outer shell, and to methods for preparing the same. These resins exhibit improved anion exchange properties.
1. Anion exchange resin in bead form, comprising:
aminated functional groups; and
a matrix of a cross-linked polymer containing a core area and a shell area,
wherein the concentration of aminated functional groups is lower in the core area relative to the shell area.
2. The anion exchange resin according to claim 1 , wherein the core area is substantially free of aminated functional groups.
3. The anion exchange resin according to claim 1 , wherein a ratio of the shell area radius to the bead radius is below 0.8.
4. The anion exchange resin according to claim 1 , wherein a ratio of the shell area radius to bead radius is in the range of 0.6 to 0.8.
5. The anion exchange resin according to claim 1 , wherein the aminated functional groups are derived from secondary and tertiary amines.
6. The anion exchange resin according to claim 5 , wherein the aminated functional groups are derived from triethylamine.
7. A process for preparing the anion exchange resin beads according to claim 1 comprising the steps of:
providing cross-linked chloromethylated copolymer intermediate resin beads, the bead containing a core area and a shell area, the core area being substantially free of chloromethyl functional groups; and
aminating the chloromethylated copolymer intermediate resin beads to form an aminated anion exchange resin in which the core area is substantially free of aminated functional groups.
8. The process according to claim 7 , wherein the anion exchange resin beads have a ratio of shell radius to bead radius of below 0.80.
9. The process according to claim 7 , wherein the anion exchange resin beads have a ratio of shell radius to bead radius is in the range of 0.6 to 0.8.
10. The process according to claim 7 , wherein the chloromethylated copolymer intermediate is prepared by reacting a chloromethylating agent with a copolymer in the presence of a catalyst and an acid.
11. The process according to claim 10 , wherein the copolymer comprises a vinyl polymer.
12. The process according to claim 10 , wherein the copolymer is a styrene-divinylbenzene copolymer.
13. The process according to claim 10 , wherein the copolymer is made from multiple vinyl monomers.
14. The process according to claim 10 , wherein the catalyst is iron (III) chloride.
15. The process according to claim 10 , wherein the acid is sulfuric acid.
16. The process according to claim 10 , wherein the copolymer is a styrene-divinylbenzene copolymer, the catalyst is iron (III) chloride, and the acid is sulfuric acid.
17. The process according to claim 10 , wherein the reaction is carried out at a temperature of about 15° C. for about 4 hours.
18. The process according to claim 10 , wherein the reaction is carried out in the absence of any additional solvent.
19. The process according to claim 18 , wherein the solvent is the chloromethylating agent.
20. The process according to claim 10 , wherein the ratio of chloromethylating agent to co-polymer is in the range of about 2 to about 20.
21. The process according to claim 20 , wherein the ratio of chloromethylating agent to co-polymer is in the range of about 4 to 9.
22. The process according to claim 10 , wherein the chloromethylating agent is prepared in situ.
23. A process for preparing the anion exchange resin beads according to claim 1 , comprising the steps of:
providing cross-linked chloromethylated copolymer intermediate resin beads; and
aminating the chloromethylated copolymer intermediate to form aminated resin beads containing a core area and a shell area,
wherein the concentration of aminated functional groups is lower in the core area relative to the shell area.
24. The process according to claim 23 , wherein the amination reaction is carried out in the absence of an organic solvent.
25. The process according to claim 24 , wherein the amination reaction is carried out in water without organic solvent.
26. The process according to claim 23 , wherein a ratio of shell area radius to bead radius is below 0.8.
27. The process according to claim 23 , wherein a ratio of shell area radius to bead radius is in the range of 0.6 to 0.8.
28. The process according to claim 23 , wherein the aminated functional groups are derived from secondary and tertiary amines.
29. The process according to claim 28 , wherein the aminated functional groups are derived from triethylamine.
30. The anion exchange resin according to claim 1 , wherein the polymer is a styrene-divinylbenzene copolymer.