High efficiency wet strength resins from new cross-linkers

1. A process for preparing a resin, comprising:

a) reacting a polyamine with a symmetric cross-linker to produce a partially cross-linked polyamine;

b) adding an epihalohydrin to the partially cross-linked polyamine to produce a halohydrin-functionalized polymer; and

c) cyclizing the halohydrin-functionalized polymer to form a resin having azetidinium moieties and wherein the symmetric cross-linker is selected from a di-acrylate compound, a bis(acrylamide) compound, a di-epoxide compound, a polyazetidinium compound, N,N′-methylene-bis-methacrylamide, a poly(alkylene glycol) diglycidyl ether and any combination thereof.

2. The process according to claim 1 , wherein the polyamine has the structure

wherein R is alkyl, hydroxyalkyl, amine, amide, aryl, heteroaryl or cycloalkyl and w is an integer from 1 to about 10,000.

3. The process according to claim 1 , wherein the polyamine has a weight average molecular weight of about 2,000 to about 1,000,000.

4. The process according to claim 1 , wherein the symmetric cross-linker is selected from:

wherein R 4 is (CH 2 ) t , and wherein t is 1, 2, or 3;

wherein x is from 1 to about 100;

wherein y is from 1 to about 100;

wherein x′+y′ is from 1 to about 100;

wherein z is from 1 to about 100;

wherein a q/p ratio is from about 10 to about 1000;

a copolymer of an acrylate monomer, a methacrylate monomer, an alkene monomer, or a diene monomer, with an azetidinium-functionalized monomer selected from

 and a combination thereof, wherein a fraction of the azetidinium-functionalized monomer to acrylate monomer, methacrylate monomer, alkene monomer, or diene monomer in the copolymer is from about 0.1% to about 12%; and

any combination thereof.

5. The process according to claim 1 , wherein the symmetric cross-linker is selected from N,N′-methylene-bis-acrylamide, N,N′-methylene-bis-methacrylamide, poly(ethylene glycol)diglycidyl ether, poly(propylene glycol) diglycidyl ether, polyethylene glycol diacrylate, polyazetidinium compounds and any combination thereof.

6. The process according to claim 1 , wherein the epihalohydrin is selected from epichlorohydrin, epibromohydrin, and epiiodohydrin.

7. The process according to claim 6 , wherein the epihalohydrin is epichlorohydrin.

8. The process according to claim 1 , further comprising:

reacting the polyamine with a mono-functional modifier prior to, during, or after reacting the polyamine with the symmetric cross-linker.

9. The process according to claim 8 , wherein the mono-functional modifier is selected from a neutral acrylate compound, a cationic acrylate compound, a neutral acrylamide compound, a cationic acrylamide compound, an acrylonitrile compound, a mono-epoxide compound, or any combination thereof.

10. The process according to claim 8 , wherein the mono-functional modifier is selected from an alkyl acrylate, acrylamide, an alkyl acrylamide, a dialkyl acrylamide, acrylonitrile, a 2-alkyl oxirane, a 2-(allyloxyalkyl)oxirane, a hydroxyalkyl acrylate, an ω-(acryloyloxy)-alkyltrimethylammonium compound, an of ω-(acrylamido)-alkyltrimethylammonium compound, and any combination thereof.

11. The process according to claim 8 , wherein the mono-functional modifier comprises at least one of: methyl acrylate, alkyl acrylate, acrylamide, N-methylacrylamide, N,N-dimethylacrylamide, acrylonitrile, 2-methyloxirane, 2-ethyloxirane, 2-propyloxirane, 2-(allyloxymethyl)oxirane, 2-hydroxyethyl acrylate, 2-(2-hydroxyethoxy)ethyl acrylate, 2-(acryloyloxy)-N,N,N-trimethylethanaminium, 3-(acryloyloxy)-N,N,N-trimethylpropan-1-aminium, 2-acrylamido-N,N,N-trimethylethanaminium, 3-acrylamido-N,N,N-trimethylpropan-1-aminium, and 1-isopropyl-3-(methacryloyloxy)-1-methylazetidinium chloride.

12. The process according to claim 1 , wherein a ratio of azetidinium ions to secondary amine moieties in the resin is from about 0.4 to about 1.0.

13. The process according to claim 1 , wherein a concentration of 1,3-dichloro-2-propanol (1,3-DCP) in the resin is less than 15,000 ppm.

14. The process according to claim 1 , wherein a pH of the resin is adjusted using an acid.

15. The process according to claim 14 , wherein the acid is acetic acid, formic acid, hydrochloric acid, phosphoric acid, sulfuric acid, organic acid or mineral acid, or any combination thereof.

16. The process according to claim 14 , wherein the pH of the resin is adjusted to about 2.0 to about 4.5.

17. The process according to claim 1 , wherein the resin has a solids content of about 10% to about 50%.

18. The process according to claim 1 , wherein the resin has a charge density of about 1.0 mEq/g of solids to about 4.0 mEq/g of solids.

19. The process according to claim 1 , wherein the resin has a ratio of azetidinium ions to amide residues of about 0.5 to about 0.9.

20. The process according to claim 1 , wherein the resin has a weight average molecular weight of about 0.02×10 6 to about 3.0×10 6 .

21. The process according to claim 1 , wherein the resin has an azetidinium equivalent weight from about 1,800 to about 3,500.

22. The process according to claim 1 , wherein the resin has a concentration of 1,3-dichloro-2-propanol (1,3-DCP) of less than 10,000 ppm.

23. A composition comprising a resin having a charge density of about 1.0 mEq/g of solids to about 4.0 mEq/g of solids, wherein the resin is prepared by a process comprising:

a) reacting a polyamine with a symmetric cross-linker to produce a partially cross-linked polyamine;

b) adding an epihalohydrin to the partially cross-linked polyamine to produce a halohydrin-functionalized polymer; and

c) cyclizing the halohydrin-functionalized polymer to form the resin, wherein the resin has azetidinium moieties and wherein the symmetric cross-linker is selected from a di-acrylate compound, a bis(acrylamide) compound, a di-epoxide compound, a polyazetidinium compound, N,N′-methylene-bis-methacrylamide, a poly(alkylene glycol) diglycidyl ether and any combination thereof.

24. The composition according to claim 23 , wherein the polyamine has the structure

wherein R is alkyl, hydroxyalkyl, amine, amide, aryl, heteroaryl or cycloalkyl and w is an integer from 1 to about 10,000.

25. The composition according to claim 23 , wherein the polyamine has a weight average molecular weight of about 2,000 to about 1,000,000.

26. The composition according to claim 23 , wherein the symmetric cross-linker is selected from:

wherein R 4 is (CH 2 ) t where t is 1, 2, or 3;

wherein x is from about 1 to about 100;

wherein y is from about 1 to about 100;

wherein x′+y′ is from about 1 to about 100;

wherein z is from about 1 to about 100;

wherein a q/p ratio is from about 10 to about 1000;

a copolymer of an acrylate monomer, a methacrylate monomer, an alkene monomer, or a diene monomer, with an azetidinium-functionalized monomer selected from

 and a combination thereof, wherein a fraction of the azetidinium-functionalized monomer to acrylate monomer, methacrylate monomer, alkene monomer, or diene monomer in the copolymer is from about 0.1% to about 12%; and

any combination thereof.

27. The composition according to claim 23 , wherein the symmetric cross-linker is selected from N,N′-methylene-bis-acrylamide, N,N′-methylene-bis-methacrylamide, poly(ethylene glycol) diglycidyl ether, polypropylene glycol) diglycidyl ether, polyethylene glycol diacrylate, polyazetidinium compounds and any combination thereof.

28. The composition according to claim 23 , wherein the epihalohydrin is selected from epichlorohydrin, epibromohydrin, and epiiodohydrin.

29. The composition according to claim 28 , wherein the epihalohydrin is epichlorohydrin.

30. The composition according to claim 23 , wherein the process further comprises:

reacting the polyamine with a mono-functional modifier prior to, during, or after reacting the polyamine with the symmetric cross-linker.

31. The composition according to claim 30 , wherein the mono-functional modifier is selected from a neutral acrylate compound, a cationic acrylate compound, a neutral acrylamide compound, a cationic acrylamide compound, an acrylonitrile compound, a mono-epoxide compound, or any combination thereof.

32. The composition according to claim 30 , wherein the mono-functional modifier is selected from an alkyl acrylate, acrylamide, an alkyl acrylamide, a dialkyl acrylamide, acrylonitrile, a 2-alkyl oxirane, a 2-(allyloxyalkyl)oxirane, a hydroxyalkyl acrylate, an ω-(acryloyloxy)-alkyltrimethylammonium compound, an ω-(acrylamido)-alkyltrimethylammonium compound, and any combination thereof.

33. The composition according to claim 30 , wherein the mono-functional modifier comprises at least one of: methyl acrylate, alkyl acrylate, acrylamide, N-methylacrylamide, N,N-dimethylacrylamide, acrylonitrile, 2-methyloxirane; 2-ethyloxirane, 2-propyloxirane, 2-(allyloxymethyl)oxirane, 2-hydroxyethyl acrylate, 2-(2-hydroxyethoxy)ethyl acrylate, 2-(acryloyloxy)-N,N,N-trimethylethanaminium, 3-(acryloyloxy)-N,N,N-trimethylpropan-1-aminium; 2-acrylamido-N,N,N-trimethylethanaminium, 3-acrylamido-N,N,N-trimethylpropan-1-aminium, and 1-isopropyl-3-(methacryloyloxy)-1-methylazetidinium chloride.

34. The composition according to claim 23 , wherein a ratio of azetidinium ions to secondary amine moieties in the resin is from about 0.4 to about 1.0.

35. The composition according to claim 23 , wherein a concentration of 1,3-dichloro-2-propanol (1,3-DCP) is less than 15,000 ppm.

36. The composition according to claim 23 , wherein the process further comprises adding an acid to the resin to adjust a pH of the resin.

37. The composition according to claim 36 , wherein the acid is acetic acid, formic acid, hydrochloric acid, phosphoric acid, sulfuric acid, organic or mineral acid, or any combination thereof.

38. The composition according to claim 36 , wherein the pH of the resin is adjusted to about 2.0 to about 4.5.

39. The composition according to claim 23 , wherein the resin has a solids content of about 10% to about 50%.

40. A process for imparting wet strength to paper, comprising:

treating pulp fibers used to make a paper with a composition comprising a resin having a charge density of about 1.0 mEq/g of solids to about 4.0 mEq/g of solids, wherein the resin is prepared by a process comprising:

a) reacting a polyamine with a symmetric cross-linker to produce a partially cross-linked polyamine;

b) adding an epihalohydrin to the partially cross-linked polyamine to produce a halohydrin-functionalized polymer; and

c) cyclizing the halohydrin-functionalized polymer to form the resin, wherein the resin has azetidinium moieties and wherein the symmetric cross-linker is selected from a di-acrylate compound, a bis(acrylamide) compound, a di-epoxide compound, a polyazetidinium compound, N,N′-methylene-bis-methacrylamide, a poly(alkylene glycol) diglycidyl ether and any combination thereof.