Methods of forming superabsorbent polymer products for use in agriculture

• US 7,009,020 B2
• Filed: 01/21/2004
• Issued: 03/07/2006
• Est. Priority Date: 10/07/2002
• Status: Expired due to Term

• Current Assignee: UPL Mauritius Limited
• Original Assignee: Milan H. Savich
• Inventors: Doane, Steven William, Doane, William McKee
• Primary Examiner(s): TRAN, THAO T
• Application Number:
  US10/762,956
• Publication Number:
  US 20040148854A1
• Time in Patent Office: 776 Days
• Field of Search: 527/103, 527/312, 106/31.71, 47/576
• US Class Current: 527/103
• CPC Class Codes: C08B 31/00 Preparation of derivatives of starch derivatives of amylose C08B33/00; derivatives of amylopectin C08B35/00
• CPC Class Codes: C08F 251/00 Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
• CPC Class Codes: C08H 99/00 Subject matter not provided for in other groups of this subclass , e.g. flours, kernels
• CPC Class Codes: C09K 17/32 of natural origin, e.g. cellulosic materials
• CPC Class Codes: C09K 8/12 containing synthetic organic macromolecular compounds or their precursors

Abstract

Methods of making and using a superabsorbent starch graft copolymer involve producing starch graft copolymers having particle sizes useful in granule applicators for application to agricultural fields. Starch graft copolymers applied to field crops provide excellent anti-crusting properties, increased seed germination and stand, increased crop growth, increased yields, and reduced water requirements.

Claims

1. A method of producing a superabsorbent polymer product for use in agricultural applications, comprising:

providing grafting reactants and a starch;

graft polymerizing the grafting reactants onto the starch to form a starch graft copolymer;

saponifying the starch graft copolymer;

precipitating the starch graft copolymer; and

forming granules of superabsorbent polymer product by pelletizing the starch graft copolymer, the granules having a size that is between about 5 mesh and about 25 mesh and a density that is between about 30 pounds per cubic foot and about 35 pounds per cubic foot.

2. The method of claim 1, wherein the grafting reactants include an initiator and an acrylonitrile.

3. The method of claim 2, wherein the grafting reactants further include a chemical selected from a group consisting essentially of acrylic acid, acrylamide, and 2-acrylonitrile-2-methyl-propanesulfonic acid.

4. The method of claim 2, wherein the starch and the acrylonitrile are present in a weight ratio of between about 1:

2 and about 1;

5.

5. The method of claim 2, wherein the initiator is a cerium salt.

6. The method of claim 2, wherein the initiator is ceric ammonium nitrate.

7. The method of claim 1, wherein the starch is selected from a group consisting essentially of pure starches, flours, and meals.

8. The method of claim 1, wherein the starch is a gelatinized starch.

9. The method of claim 1, wherein the starch is cornstarch.

10. The method of claim 1, wherein the size is between about 8 mesh and about 25 mesh.

11. The method of claim 1, wherein precipitating the saponified starch graft copolymer involves mixing an alcohol with the saponified starch graft copolymer.

12. The method of claim 11, wherein the alcohol is selected from a group consisting essentially of methanol, ethanol, propanol, and isopropanol.

13. The method of claim 1, wherein the process of pelletizing includes extruding the starch graft copolymer into strands and grinding the strands to form the granules.

14. The method of claim 1, further comprising:

drying the granules of superabsorbent polymer product.

15. A method of producing a superabsorbent polymer product for use in agricultural applications, comprising:

graft polymerizing grafting reactants onto a starch to form a starch graft copolymer;

saponifying the starch graft copolymer;

precipitating the starch graft copolymer; and

forming granules of superabsorbent polymer product by passing the starch graft copolymer through a die plate, the granules having a size that is between about 5 mesh and about 25 mesh and a density that is between about 30 pounds per cubic foot and about 35 pounds per cubic foot.

16. The method of claim 15, wherein the grafting reactants include an initiator and an acrylonitrile.

17. The method of claim 15, wherein the grafting reactants further include a chemical selected from a group consisting essentially of acrylic acid, acrylamide, and 2-acrylonitrile-2-methyl-propanesulfonic acid.

18. The method of claim 16, wherein the starch and the acrylonitrile are present in a weight ratio of between about 1:

2 and about 1;

5.

19. The method of claim 16, wherein the initiator is a cerium salt.

20. The method of claim 15, wherein the starch is selected from a group consisting essentially of pure starches, flours, and meals.

21. The method of claim 15, wherein the starch is a gelatinized starch.

22. The method of claim 15, wherein the starch is cornstarch.

23. The method of claim 15, wherein the size is between about 8 mesh and about 25 mesh.

24. The method of claim 15, further comprising:

drying the granules of superabsorbent polymer product.