Slow-release microcapsule composition for safe delivery of agriculturally active material
A slow-release microcapsule composition for the safe delivery of agriculturally active material is formed using an encapsulation process. A microencapsulated suspension of agriculturally active material includes an encapsulating agent formed from a graft copolymer of starch and at least on vinyl monomer.
1. A slow-release microcapsule for safe delivery of an agriculturally active material comprising,
(a) an inner core including an agriculturally active material;
(b) an outer shell including a graft copolymer comprising a starch and at least one vinyl monomer and having a core to polymer shell ratio of 1:10 to 10:1.
2. The slow-release microcapsule of claim 1 wherein the starch and the vinyl monomer are present in a ratio is 1:5 to 5:1.
3. The slow-release microcapsule of claim 1 wherein the microcapsule have a size of 5 to 500 microns.
4. The slow-release microcapsule of claim 1 wherein the agriculturally active material is a pyrethroid.
5. The slow-release microcapsule of claim 4 wherein the pyrethroid is lambda Cyhalothrin.
6. The slow-release microcapsule of claim 1 wherein the vinyl monomer is selected from the group consisting of vinyl acetate, vinyl halide, vinyl ethers, alkyl vinyl ketones, N-Vinyl carbzole, N-Vinyl pyrolidone, Vinyl pyrridine, styrene, alkyl styrene, and acrylic acid.
7. The slow-release microcapsule of claim 1 wherein the starch is selected from the group consisting of potato, oat, wheat, sorghum, rice, corn, and combinations thereof.
8. An encapsulation process for preparing a slow-release microencapsulated suspension for a safe delivery system of an agriculturally active material, comprising the steps of:
a) preparing an organic phase comprising an agriculturally active water immiscible material and a solvent, in the presence of at least one surfactant;
b) preparing an aqueous phase comprising water, a starch, and a protective colloid;
c) heating the aqueous phase to obtain a gelatinized aqueous phase followed by cooling;
d) adding the organic phase of step (a) into the gelatinized aqueous phase of step (c) under low shear to form an oil-in-water emulsion;
e) adding an initiator by maintaining an acidic pH to the oil-in-water emulsion of step (d) in an inert atmosphere;
f) adding a vinyl monomer for graft reaction to occur and resulting in obtaining a microencapsulated suspension; and
g) neutralizing the microencapsulated suspension of step (f) followed by adding a structuring agent.
9. The encapsulation process of claim 8 , wherein the vinyl monomer is selected from the group consisting of vinyl halide, vinyl ethers, alkyl vinyl ketones, N-vinyl carbzole, N-Vinyl pyrolidone, vinyl pyrridine, styrene, alkyl styrene, vinyledenehalides, itaconic acid, and 1,3-butadine.
10. The encapsulation process of claim 8 wherein the starch is selected from the group consisting of potato, oat, wheat, sorghum, rice and combinations thereof.
11. The encapsulation process of claim 8 , wherein the starch and the vinyl monomer are present in a ratio of 1:5 to 5:1.
12. The encapsulation process of claim 8 , wherein said initiator is a free radical initiator.
13. The encapsulation process of claim 8 , wherein said initiator is ceric ammonium nitrate.
14. The encapsulation process of claim 8 , wherein said surfactant is an anionic surfactant or a non-ionic surfactant or a combination thereof.
15. The encapsulation process of claim 8 , wherein said step of preparing an aqueous phase further comprises a biocide.
16. The encapsulation process of claim 15 , wherein said biocide is selected from the group consisting of methyl paraban, ethyl paraban and butyl paraban.
17. The encapsulation process of claim 8 , wherein said step of preparing an aqueous phase further comprises a dispersant.
18. The encapsulation process of claim 17 , wherein said dispersant is selected from the group consisting of Emulsol 101, Soprophor FL, Soprophor FLK and combinations thereof.
19. The encapsulation process of claim 8 , wherein said protective colloid is an alkyl metal or an alkaline earth metals of alkyl naphthalene sulphonate.
20. The encapsulation process of claim 8 , wherein said agriculturally active water immiscible material is a pyrethroid.
21. The encapsulation process of claim 8 , wherein said agriculturally active water immiscible material is Lambda Cyhalothrin.
22. The encapsulation process of claim 8 , wherein said step of preparing an aqueous phase further comprises a second surfactant.
23. The encapsulation process of claim 8 , wherein said step of preparing an aqueous phase further comprises an anti-freezing agent.
24. The encapsulation process of claim 8 , wherein said step of heating said aqueous phase includes heating at a temperature of 65-85° C.
25. The encapsulation process of claim 8 , wherein the structuring agent is selected from the group consisting of xanthan gum, guar gum, and arabic gum.
26. The encapsulation process of claim 8 , wherein said step of adding an initiator to the oil-in-water emulsion includes maintaining a pH between 2-5.
27. The encapsulation process of claim 8 , wherein said step of adding an initiator to the oil-in-water emulsion includes maintaining a temperature ranging between 15-30° C.
28. The encapsulation process of claim 8 , wherein said step of adding vinyl monomer includes maintaining a temperature of 15-30° C.
29. The encapsulation process of claim 8 , wherein said step of neutralizing the microencapsulated suspension includes neutralizing with an organic aliphatic amine.
30. The encapsulation process of claim 8 , wherein said step of preparing an organic phase includes continuously stirring to get a clear solution.
31. The encapsulation process of claim 8 , wherein said step of heating the aqueous phase is followed by cooling to a temperature of 20-45° C.
32. The encapsulation process of claim 8 , wherein said inert atmosphere is an oxygen-free inert atmosphere.