Amine modified polysaccharide urethane/urea microcapsules
Core shell microcapsules are provided wherein the capsule shell is an interfacial copolymer formed of an amine modified polysaccharide cross-linked with an isocyanate.
1. A microcapsule comprising a core material and a shell encapsulating the core material wherein the shell comprises the reaction product of a) an amine modified polysaccharide and b) an isocyanate component comprising one or more di- and/or poly-isocyanates wherein i) the amine modified polysaccharide is characterized as having from 0.005 up to 8 mole percent of the hydroxy groups substituted with a moiety having a free or reactive amino group, and either A) the amine modified polysaccharide is the reaction product of a polysaccharide and one or more di- or poly-functional amines and/or aminating agents selected from one or more amino-silanes, one or more amino-(meth)acrylates, one or more amine free radical initiators or a combination of any two or more of the foregoing, wherein when the amine modified polysaccharide is a maltodextrin, the amine modified polysaccharide has at least 1 amino functional group per molecule, or B) the amine modified polysaccharide is or includes a maltodextrin having at least 4 amino functional groups per molecule, and ii) the weight ratio of the polysaccharide to isocyanate is from 40:60 to 99:1.
2. The microcapsule of claim 1 wherein the amine modified polysaccharide is the reaction product of a polysaccharide and one or more di- or poly-functional amines and/or aminating agents selected from one or more amino-silanes, one or more amino-(meth)acrylates or one or more amine free radical initiators or a combination of any two or more of the foregoing.
3. The microcapsule of claim 2 wherein the di- or polyfunctional amine is or includes an amino-(meth)acrylate.
4. The microcapsule of claim 1 wherein the amine modified polysaccharide is or includes a maltodextrin.
5. The microcapsule of claim 4 wherein the maltodextrin has at least 4 amino function groups and the free or reactive amino group of the polysaccharide is a primary amine, a secondary amine, an amide and/or an amidine group.
6. The microcapsule of claim 4 wherein the amine modified maltodextrin has at least 4 amino function groups and is the reaction product of a maltodextrin and one or more di- or poly-functional amines and/or aminating agents.
7. The microcapsule of claim 6 wherein the one or more di- or poly-functional amines and/or aminating agents is selected from one or more amino-silanes, one or more amino-(meth)acrylates or one or more amine free radical initiators or a combination of any two or more of the foregoing.
8. The microcapsule of claim 7 wherein di- or poly-functional amine is or includes an amino-(meth)acrylate.
9. The microcapsule of claim 1 wherein the amine modified polysaccharide is characterized as having from 0.01 up to 6 mole percent of the hydroxy groups substituted with a moiety having a free or reactive amino group.
10. The microcapsule of claim 1 wherein the amine modified polysaccharide is characterized as having from 0.05 up to 4 mole percent of the hydroxy groups substituted with a moiety having a free or reactive amino group.
11. The microcapsule of claim 1 wherein the amine modified polysaccharide is or includes a hydrophobically modified polysaccharide.
12. The microcapsule of claim 11 wherein the hydrophobically modified polysaccharide is an esterified starch.
13. The microcapsule of claim 1 wherein at least 50 mole percent of the isocyanates are di-isocyanates.
14. The microcapsule of claim 1 wherein at least 75 more percent of the isocyanates are di-isocyanates.
15. The microcapsule of claim 1 whose reactants further include up to 50 mole percent of one or more polysaccharides which have not been amine modified.
16. The microcapsule of claim 1 wherein the weight ratio of the total wall forming polysaccharide content to isocyanate is from 50:50 to 99:1.
17. The microcapsule of claim 1 wherein the weight ratio of the total wall forming polysaccharide content to isocyanate is from 70:30 to 98:2.
18. An oil-in water microencapsulation process comprising dispersing an oil phase composition comprising a core material and an isocyanate wall forming material comprising one or more di- or poly-isocyanates, in an aqueous phase composition and subjecting the dispersion to polymerization conditions; said aqueous phase composition, prior to subjecting the dispersion to polymerization conditions, comprising an amine modified polysaccharide wall forming material, whereby the isocyanate and the amine modified polysaccharide form a cross-linked shell wall encapsulating the core material; wherein i) the amine modified polysaccharide is characterized as having from 0.005 up to 8 mole percent of the hydroxy groups substituted with a moiety having a free or reactive amino group, and either A) the amine modified polysaccharide is the reaction product of a polysaccharide and one or more di- or poly-functional amines and/or aminating agents selected from one or more amino-silanes, one or more amino-(meth)acrylates or one or more amine free radical initiators or a combination of any two or more of the foregoing, wherein when the amine modified polysaccharide is a maltodextrin the amine modified polysaccharide has at least 1 amino functional group per molecule, or B) the amine modified polysaccharide is or includes a maltodextrin having at least 4 amino functional groups per molecule, and ii) the weight ratio of the polysaccharide to isocyanate is from 40:60 to 99:1.
19. The process of claim 18 wherein the amine modified polysaccharide is the reaction product of a polysaccharide and one or more di- or poly-functional amines and/or aminating agents selected from one or more amino-silanes, one or more amino-(meth)acrylates or one or more amine free radical initiators or a combination of any two or more of the foregoing.
20. The process of claim 19 wherein the di- or polyfunctional amine is or includes an amino-(meth)acrylate.
21. The process of claim 18 wherein the amine modified polysaccharide is or includes a maltodextrin.
22. The process of claim 21 wherein the maltodextrin has at least 4 amino function groups and the free or reactive amino group of the polysaccharide is a primary amine, a secondary amine, an amide and/or an amidine group.
23. The process of claim 21 wherein the maltodextrin has at least 4 amino function groups and the amine modified maltodextrin is the reaction product of a maltodextrin and one or more di- or poly-functional amines and/or aminating agents.
24. The process of claim 23 wherein the one or more di- or poly-functional amines and/or aminating agents is selected from one or more amino-silanes, one or more amino-(meth)acrylates or one or more amine free radical initiators or a combination of any two or more of the foregoing.
25. The process of claim 24 wherein di- or poly-functional amine is or includes an amino-(meth)acrylate.
26. The process of claim 18 wherein the amine modified polysaccharide is characterized as having from 0.01 up to 6 mole percent of the hydroxy groups substituted with a moiety having a free or reactive amino groups.
27. The process of claim 18 wherein the amine modified polysaccharide is characterized from 0.05 up to 4 mole percent of the hydroxy groups substituted with a moiety having a free or reactive amino group.
28. The process of claim 18 wherein the amine modified polysaccharide is or includes a hydrophobically modified polysaccharide.
29. The process of claim 28 wherein the hydrophobically modified polysaccharide is an esterified starch.
30. The process of claim 18 wherein at least 50 mole percent of the isocyanates are di-isocyanates.
31. The process of claim 18 wherein at least 75 more percent of the isocyanates are di-isocyanates.
32. The process of claim 18 whose reactants further include up to 50 mole percent of one or more polysaccharides which have not been amine modified.
33. The process of claim 18 wherein the weight ratio of the total wall forming polysaccharide content to isocyanate is from 50:50 to 99:1.
34. The process of claim 18 wherein the weight ratio of the total wall forming polysaccharide content to isocyanate is from 70:30 to 98:2.
35. The process of claim 18 further comprising, as preliminary steps, a) preparing an aqueous solution of a polysaccharide and one or more di- and/or polyfunctional amines or aminating agents selected from one or more amino-silanes, one or more amino-(meth)acrylates or one or more amine free radical initiators or a combination of any two or more of the foregoing, b) reacting the polysaccharide and the di- and/or polyfunctional amine(s) or aminating agent(s) to form the amine modified polysaccharide and c) either i) isolating the amine modified polysaccharide and using it to form the aqueous phase composition or ii) employing the reaction solution as the aqueous phase composition.
36. The process of claim 35 wherein the mole ratio of the amine or aminating agent to polysaccharide is from 7:1 to 1:7, wherein when the polysaccharide is a maltodextrin, the mole ratio may be up to 15:1.