Granted Patent B2

US 7,459,501 · App. 12/018,090 · Granted Dec 2, 2008

Abstract

Claims (19)

1. A method for preparing a superabsorbent polymer, comprising:

graft polymerizing a monomer onto a starch in the presence of an initiator to form a starch graft copolymer, wherein the monomer is at least one of the following: acrylic acid, acrylamide, methacrylamide, 2-acrylamido-2-methyl-propanesulfonic acid, methacrylic acid, vinyl sulfonic acid, ethyl acrylate, potassium acrylate, derivatives thereof or mixtures thereof;

adding a cross-linking agent to cross-link the starch graft copolymer;

isolating the starch graft copolymer by extruding the starch graft copolymer into strands after cross-linking the starch graft copolymer;

applying an alcohol to the strands to reduce tackiness of the extruded strands, the alcohol chosen from: methanol, ethanol, propanol or isopropanol; and

forming granules of starch graft copolymer from the extruded strands.

2. The method of claim 1 , further comprising drying the starch graft copolymer.

3. The method of claim 1 , further comprising adjusting a pH of the starch graft copolymer.

4. The method of claim 3 , wherein the pH is adjusted to within a range of about 6.0 to about 8.0.

5. The method of claim 1 , wherein the monomer is a mixture of acrylic acid and acrylamide.

6. The method of claim 1 , wherein forming granules of starch graft copolymers comprises forming granules having a mesh size of between about 8 mesh and about 25 mesh.

7. The method of claim 1 , wherein forming granules of starch graft copolymers comprises forming granules having a mesh size of between about 8 mesh and about 16 mesh.

8. The method of claim 1 , wherein forming granules of starch graft copolymers comprises forming granules having a mesh size of between about 20 mesh and about 40 mesh.

9. A method for preparing a superabsorbent polymer product for agricultural applications, comprising:

graft polymerizing a mixture of acrylic acid and acrylamide onto a starch in the presence of an initiator to form a starch graft copolymer;

adding a cross-linking agent to form a cross-linked starch graft copolymer;

adjusting a pH of the cross-linked starch graft copolymer to within a pH range of about 6.0 and about 8.0;

isolating the superabsorbent polymer product through extruding the cross-linked starch graft copolymer; and

applying an alcohol to the extruded cross-linked starch graft copolymer to reduce its tackiness, the alcohol chosen from: methanol, ethanol, propanol or isopropanol.

Assignments (8)