Fertilizer compositions having slow-release nitrogen compounds and methods of forming thereof
Methods of forming a fertilizer composition having slow-release nitrogen compounds with a molten process are disclosed. The methods include mixing of a crystalline polyethylene wax with urea and formaldehyde to form a molten methylene urea mixture. The contents of the molten methylene urea mixture react to form slow-release nitrogen compounds. Fertilizer compositions formed of or including the slow-release nitrogen compounds are also disclosed.
1. A method of forming a fertilizer composition having slow-release nitrogen compounds, the method comprising:
mixing urea, formaldehyde, and crystalline polyethylene wax at a first temperature to form a molten methylene urea mixture;
increasing the temperature of the molten methylene urea mixture from the first temperature to a reaction temperature to initiate a reaction of the urea and the formaldehyde to form a fertilizer composition; and
heat treating the fertilizer composition at a second temperature above the reaction temperature.
2. The method of claim 1 , wherein the crystalline polyethylene wax has one or more of:
a molecular weight of about 600 to about 1,200;
a polydispersity of about 1.02 to about 1.7; and
a degree of crystallinity of about 65% to about 96%.
3. The method of claim 1 , wherein the crystalline polyethylene wax has a polydispersity of about 1.08 to about 1.09.
4. The method of claim 1 , wherein the first temperature is in a range from about 50° C. to about 120° C.
5. The method of claim 1 , wherein the reaction temperature is in a range from about 125° C. to about 135° C.
6. The method of claim 1 , wherein the molten methylene urea mixture is held at the reaction temperature for about 15 minutes to about 30 minutes.
7. The method of claim 1 , wherein the second temperature is in a range from about 135° C. to about 150° C.
8. The method of claim 1 , wherein the heat treating of the fertilizer composition is performed for about 5 minutes to about 15 minutes.
9. The method of claim 1 , wherein the mole ratio of urea to formaldehyde is about 3.1:1 to about 3.35:1.
10. The method of claim 1 , wherein the molten methylene urea mixture comprises about 2.5% to about 7.5%, by weight, of the crystalline polyethylene wax.
11. The method of claim 1 , wherein the molten methylene urea mixture is substantially free of added water.
12. The method of claim 1 , wherein the crystalline polyethylene wax is added to a mixture of the urea and the formaldehyde.
13. The method of claim 1 , wherein the formaldehyde is added to a mixture of the urea and the crystalline polyethylene wax.
14. The method of claim 1 , wherein fertilizer composition comprises at least one of methylenediurea (“MDU”) and dimethylenetriurea (“DMTU”) and wherein the at least one of MDU and DMTU comprises about 35% or more of the total nitrogen in the fertilizer composition.
15. The method of claim 14 , wherein the least one of MDU or DMTU comprises about 45% or more of the total nitrogen in the fertilizer composition.
16. The method of claim 1 , wherein the fertilizer composition comprises about 8% or less cold-water insoluble nitrogen.
17. The method of claim 1 , wherein the crystalline polyethylene wax at least partially occludes the slow-release nitrogen compounds.
18. The method of claim 1 , wherein the fertilizer composition exhibits a complex viscosity of about 0.1 Pas to about 0.20 Pas when measured at a temperature of about 150° C.
19. The method of claim 1 , wherein the fertilizer composition exhibits a viscous modulus of about 0.5 Pa to about 1.2 Pa when measured at a temperature of about 150° C.
20. The method of claim 1 , wherein the fertilizer composition has a tan delta of about 3.0 or greater.