Patent ID: 6617412
Filing Date: 2003-09-09
Classification: C05G,C08G

Abstract:
A process for the production of an encapsulated, slow release fertilizer composition comprising:1) applying a polyisocyanate composition to fertilizer particles which contain at least one water soluble plant nutrient to form isocyanate coated fertilizer particles 2) applying an isocyanate-reactive composition containing from 2 to 4 hydroxyl groups capable of reacting with the NCO groups of the isocyanate component, and having a molecular weight of about 106 to about 400, an equivalent weight of about 31 to less than about 100, and containing 30 to 80% by weight of sulfur based on 100% by weight of said isocyanate reactive composition, to the isocyanate coated fertilizer particles from step 1) to yield polyurethane encapsulated fertilizer particles; and 3) repeating steps 1) through 2) as many times as necessary, wherein the encapsulated fertilizer particles from step 2) are substituted for the fertilizer particles in step 1) above; thereby forming encapsulated fertilizer particles which contain from about 2 to 20% by weight of sulfur containing polyurethane, based on the total weight of the encapsulated fertilizer particles, wherein the polyurethane encapsulation contains at least 5% by weight of sulfur.