Encapsulation of herbicides to reduce crop injury

Patent metadata

Field	Value
Publication number	US-9877478-B2
Application number	US-70578910-A
Country	US
Kind code	B2
Filing date	Feb 15, 2010
Priority date	Feb 13, 2009
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

Methods of reducing injury to crop foliage and achieving weed control using encapsulated acetamide herbicides are described. Herbicidal microcapsules comprising herbicide core material and a shell wall encapsulating the core material are also described. The microcapsules provide reduced crop injury through controlled herbicide release.

First claim

What is claimed is:

1. A particulate microencapsulated acetamide herbicide comprising:
a water-immiscible core material comprising the acetamide herbicide, wherein the acetamide herbicide comprises acetochlor and
microcapsules having a shell wall comprising a polyurea, the microcapsules containing the core material,
wherein the shell wall is formed in a polymerization medium by a polymerization reaction between a polyisocyanate component comprising a polyisocyanate or mixture of polyisocyanates and a polyamine component comprising a polyamine or mixture of polyamines to form the polyurea,
wherein the ratio of amine molar equivalents contained in the polyamine component to isocyanate molar equivalents contained in the polyisocyanate component is from 1.15:1 to about 1.4:1, and
wherein the microcapsules have a mean particle size range from about 7 μm to about 15 μm.

2. The microencapsulated acetamide herbicide of claim 1 wherein the microcapsules have a mean particle size range of from about 8 μm to about 12 μm.

3. The microencapsulated acetamide herbicide of claim 1 wherein the molar equivalents ratio is from 1.15:1 to about 1.3:1.

4. The microencapsulated acetamide herbicide of claim 1 wherein the shell wall is of limited permeability, and the nature and composition of said shell wall and encapsulated acetamide is such that, when an aqueous slurry consisting of 1% by weight of the encapsulated acetamide herbicide in an aqueous medium consisting of deionized water is subjected to agitation at a rate sufficient to maintain the particles in suspension without mechanical rupturing, the acetamide content of the aqueous medium remains less than 100 ppm after agitation for 6 hours at 25° C., and less than 150 ppm acetamide after agitation for 24 hours at 25° C.

5. The microencapsulated acetamide herbicide of claim 1 wherein the weight to weight ratio of acetamide herbicide to the shell wall is from about 6:1 to about 10:1.

6. The microencapsulated acetamide herbicide of claim 1 wherein the polyisocyanate component has a minimum average of 2.5 reactive groups per polyisocyanate molecule and the polyamine component has an average of at least three reactive groups per polyamine molecule.

7. The microencapsulated acetamide herbicide of claim 1 wherein the polyisocyanate component is a blend of a triisocyanate and a diisocyanate wherein the ratio of the triisocyanate to the diisocyanate, on an isocyanate equivalent basis, is between about 90:10 and about 30:70.

8. The microencapsulated acetamide herbicide of claim 1 wherein the core material further comprises from about 1% to about 10% by weight of a water-insoluble organic solvent.

9. The microencapsulated acetamide herbicide of claim 8 wherein the water-insoluble solvent is a paraffinic hydrocarbon.

10. The microencapsulated acetamide herbicide of claim 1 wherein the core further comprises a water-insoluble solvent at a weight ratio of the acetamide herbicide to the solvent of from 15 to 1 to 20 to 1.

11. The microencapsulated acetamide herbicide of claim 1 wherein the polyamine is of the structure NH 2 (CH 2 CH 2 NH) m CH 2 CH 2 NH 2 where m is from 1 to 5.

12. The microencapsulated acetamide herbicide of claim 1 where more than 50% by weight of the polyisocyanate component is a trimer of 1,6-hexamethylene diisocyanate.

13. The microencapsulated acetamide herbicide of claim 1 wherein the polyisocyanate component comprises an aliphatic polyisocyanate or mixture of aliphatic polyisocyanates.

14. The microencapsulated acetamide herbicide of claim 13 wherein the molar equivalents ratio is from 1.15:1 to about 1.3:1.

15. The microencapsulated acetamide herbicide of claim 1 wherein the polyisocyanate component comprises an aliphatic polyisocyanate or mixture of aliphatic polyisocyanates and wherein the microcapsules have a mean particle size from 9 μm to about 12 μm.

16. The microencapsulated acetamide herbicide of claim 15 wherein the molar equivalents ratio is from about 1.2:1 to about 1.4:1.

17. The microencapsulated acetamide herbicide of claim 1 wherein the molar equivalents ratio is from about 1.2:1 to about 1.3:1.

18. The microencapsulated acetamide herbicide of claim 1 wherein the molar equivalents ratio is from about 1.2:1 to about 1.4:1.

19. The microencapsulated acetamide herbicide of claim 18 wherein:
the polyisocyanate component comprises an aliphatic polyisocyanate or mixture of aliphatic polyisocyanates;
the polyamine component comprises a polyamine of the structure NH 2 (CH 2 CH 2 NH) m CH 2 CH 2 NH 2 where m is from 1 to 5;
the weight ratio of acetamide herbicide to the shell wall is from 6:1 to 13:1; and
the microcapsules have a mean particle size from 9 μm to about 12 μm.

20. The microencapsulated acetamide herbicide of claim 19 wherein more than 50% by weight of the polyisocyanate component is a trimer of 1,6-hexamethylene diisocyanate.

21. The microencapsulated acetamide herbicide of claim 20 wherein the core material further comprises from about 1% to about 10% by weight of a water-insoluble paraffinic hydrocarbon solvent.

22. The microencapsulated acetamide herbicide of claim 1 wherein the weight to weight ratio of acetamide herbicide to the shell wall is from about 13:1 to about 6:1.

23. The microencapsulated acetamide herbicide of claim 1 wherein the weight to weight ratio of acetamide herbicide to the shell wall is from about 13:1 to about 8:1.

24. An aqueous mixture comprising the microencapsulated acetamide herbicide of claim 1 , the aqueous mixture in the form of a concentrate or diluted spray application mixture.

25. The aqueous mixture of claim 24 further comprising one or more co-herbicides selected from acetyl CoA carboxylase inhibitors, organophosphorus herbicides, auxins, photosystem II inhibitors, ALS inhibitors, protoporphyrinogen oxidase inhibitors and carotenoid biosynthesis inhibitors, salts and esters thereof, and mixtures thereof.

26. The aqueous mixture of claim 25 wherein the co-herbicide is the photosystem II inhibitor atrazine.

27. The aqueous mixture of claim 24 wherein the concentration of the acetamide herbicide microcapsules is at least about 30 weight percent but less than about 62.5 weight percent.

28. The aqueous mixture of claim 27 wherein the concentration of acetochlor is at least about 25 weight percent.

29. The aqueous mixture of claim 28 wherein the concentration of acetochlor is less than about 55 weight percent.

30. A method of controlling weeds in a field of crop plants, the method comprising:
forming an application mixture comprising the particulate microencapsulated acetamide herbicide as set forth in claim 1 and
applying the application mixture in a herbicidally effective amount post-emergent to the crop plants.

31. The method of claim 30 wherein the application mixture is applied pre-emergent to the weeds.

32. The method of claim 30 wherein the crop plant is selected from the group consisting of corn, peanuts, potatoes, soybeans, canola, sugarbeets and cotton.

33. The method of claim 30 wherein the crop plants have one or more herbicide tolerant traits.

34. The method of claim 30 wherein the application mixture further comprises glyphosate co-herbicide and the crop plants are transgenic glyphosate

Assignees

• Becher David Z
• Abraham William
• Prosch S Douglas
• Bussler Brett H
• Herr Amanda C
• Monsanto Technology Llc

Inventors

• Becher David Z
• Abraham William
• Prosch S Douglas
• Bussler Brett H
• Herr Amanda C

Classifications

• A01N37/26 Primary

  containing the group [IMAGE cpc-sch-A01N-0936.gif]; Thio analogues thereof · CPC title

• A01N25/28

  Microcapsules {or nanocapsules} · CPC title

• A01N2300/00

  Combinations or mixtures of active ingredients covered by classes A01N27/00 - A01N65/48 with other active or formulation relevant ingredients, e.g. specific carrier materials or surfactants, covered by classes A01N25/00 - A01N65/48 · CPC title