Slow release nitrogen fertilizer
View Patent ↗A slow release, particulate urea-formaldehyde polymer useful as a fertilizer for enhancing the extended delivery of nitrogen needed for plant development and growth and a granular fertilizer made with the particulate urea-formaldehyde polymer.
1. A particulate urea-formaldehyde polymer made by acidifying a aqueous methylol urea solution, wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of from 0.7:1 to 1.25:1 and wherein the aqueous methylol urea solution either contains a dispersing agent or is subjected to a high shear condition during the acidifying, to form an aqueous dispersion of insoluble urea-formaldehyde polymer particles and drying the dispersion to recover the urea-formaldehyde polymer particles.
2. The particulate urea-formaldehyde polymer of claim 1 wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of approximately 1:1.
3. The particulate urea-formaldehyde polymer of claim 1 wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of approximately 1:1 and wherein the methylol urea solution contains a dispersing agent during the acidifying.
4. The particulate urea-formaldehyde polymer of claim 2 wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of from 0.83:1 to 1.1:1.
5. The particulate urea-formaldehyde polymer of claim 3 wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of from 0.83:1 to 1.1:1.
6. The particulate urea-formaldehyde polymer of claim 1 wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of from 0.95:1 to 1.05:1 and wherein the methylol urea solution contains a dispersing agent during the acidifying.
7. The particulate urea-formaldehyde polymer of claim 1 wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of from 0.95:1 to 1.05:1.
8. The particulate urea-formaldehyde polymer of claim 1 , 2 , 3 , 4 , 5 , 6 , or 7 wherein the aqueous dispersion of urea-formaldehyde polymer particles is dried by spray drying.
9. A granular fertilizer made by granulating the particulate urea-formaldehyde polymer of claim 8 with a fertilizer-enhancing solid and a binder.
10. The granular fertilizer of claim 9 wherein said fertilizer-enhancing solid is selected from the group consisting of calcium carbonate; gypsum; metal silicates; metal chelates of a metal selected from iron, zinc and manganese; talc; elemental sulfur; activated carbon; pesticides; herbicides; fungicides; super absorbent polymers; wicking agents; wetting agents; plant stimulants; urea; a potassium source and a phosphorus source.
11. A method of producing a particulate urea-formaldehyde polymer comprising forming an aqueous solution of methylol urea by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of 0.95:1 to 1.05:1; acidifying the aqueous methylol urea solution, wherein the aqueous methylol urea solution either contains a dispersing agent or is subjected to a high shear condition during the acidifying, to form an aqueous dispersion of insoluble urea-formaldehyde polymer particles and drying the dispersion to recover the urea-formaldehyde polymer particles.
12. The method of claim 11 wherein the wherein the methylol urea solution contains a dispersing agent during the acidifying and the aqueous dispersion of urea-formaldehyde polymer particles is dried by spray drying.
13. The particulate urea-formaldehyde polymer of claim 1 wherein the urea-formaldehyde polymer particles have a number average particle size between 25 and 35 microns.
14. A particulate urea-formaldehyde polymer made by acidifying an aqueous methylol urea solution, wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:formaldehyde mole ratio of from 0.7:1 to 1.25:1 and wherein the aqueous methylol urea solution either contains a dispersing agent or is subjected to a high shear condition during the acidifying, to form an aqueous dispersion of insoluble urea-formaldehyde polymer particles, wherein most of the urea-formaldehyde particles have a size between 1 and 150 microns.
15. The particulate urea-formaldehyde polymer of claim 14 wherein most of the urea-formaldehyde particles have a size between 10 and 80 microns.
16. The particulate urea-formaldehyde polymer of claim 15 wherein the urea-formaldehyde particles have a number average particle size between 25 and 35 microns.
17. The particulate urea-formaldehyde polymer of claim 14 wherein the dispersing agent is selected from the group consisting of a condensed naphthalene sulfonate, a polyacrylate, a lignosulfonate salt and lignin.
18. The particulate urea-formaldehyde polymer of claim 6 wherein the dispersing agent is selected from the group consisting of a condensed naphthalene sulfonate, a polyacrylate, a lignosulfonate salt and lignin.
19. The particulate urea-formaldehyde polymer of claim 12 wherein the dispersing agent is selected from the group consisting of a condensed naphthalene sulfonate, a polyacrylate, a lignosulfonate salt and lignin.