Controlled release fertilizer composition

Abstract

A controlled release fertilizer composition and methods to produce the controlled release fertilizer composition are described. The controlled release fertilizer composition comprises a water soluble fertilizer core that is coated with a polymeric layer, intermediate layer, and a sulfur layer. If desired, the sulfur layer can be coated with an outer water-insoluble layer.

1 . A controlled release fertilizer composition, comprising:
 a) a core comprising one or more plant nutrient materials;   b) a polymer layer coating the core, wherein the polymer layer comprises a polymer formed on the core from two or more precursor compounds;   c) a sulfur layer overlying the polymer layer;   d) an intermediate layer between the polymer layer and the sulfur layer, wherein the intermediate layer functions as a lubricant when applying the sulfur layer; and   e) optionally an outer, water-insoluble layer.   
     
     
         2 . The control release fertilizer of  claim 1 , wherein the core comprises nitrogen, phosphorus, potassium, sulfur, micronutrients and mixtures thereof. 
     
     
         3 . The controlled release fertilizer of  claim 1 , wherein the core comprises urea. 
     
     
         4 . The controlled release fertilizer of  claim 1 , wherein the precursor compounds comprise an isocyanate and a polyol. 
     
     
         5 . The controlled release fertilizer of  claim 4 , wherein the isocyanate comprises a diisocyanate, 
     
     
         6 . The controlled release fertilizer of  claim 4 , wherein the isocyanate comprises a polyisocyanate. 
     
     
         7 . The controlled release fertilizer of  claim 4 , wherein the isocyanate comprises 4,4 diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4′-diphenylmethane diisocyanate, or 4,4′-diphenylmethanie diisocyanate. 
     
     
         8 . The controlled release fertilizer of  claim 1 , wherein the precursor compounds comprise a polyol. 
     
     
         9 . The controlled release fertilizer of  claim 8 , wherein the polyol comprises a glycol. 
     
     
         10 . The controlled release fertilizer of  claim 8 , wherein the polyol comprises diethylene glycol polyol, orthophathalate diethylene glycol based polyester polyols, terephthalate-diethylene glycol based polyester polyols, castor oil, oils modified to contain amine or OH groups comprising modified tung oil, soybean oil, canola oil, sunflower oil, or linseed oil, oleo-polyols comprising epoxidized castor oil, epoxidized sunflower oil, or epoxidized linseed oil, polyether polyols, castor oil derivatives comprising partial hydrolysates of castor oil formed by reacting castor oil with a polyol selected from diols comprising ethylene glycol or dipropylene glycol, or esters formed by reactions between ricinoleic acid and ethylene glycol, or dipropylene glycol. 
     
     
         11 . The controlled release fertilizer of  claim 1 , wherein the precursor compounds comprise a polyol and a polyisocyanate and the polymer comprises a polyurethane. 
     
     
         12 . The controlled release fertilizer of  claim 1 , wherein the precursor compounds comprise MDI and DEG-TEA polyol. 
     
     
         13 . The controlled release fertilizer of  claim 1 , wherein the intermediate layer is a wax. 
     
     
         14 . The controlled release fertilizer of  claim 13 , where wax comprise intermediate petroleum wax, alpha olefin wax, polyethylene wax, paraffin wax, silicon wax, slack wax, microcrystalline wax, or natural wax. 
     
     
         15 . The controlled release fertilizer of  claim 13 , wherein wax comprise intermediate wax, paraffin wax, or polyolefin wax. 
     
     
         16 . The controlled release fertilizer of  claim 1 , wherein the one or more plant nutrients are about 37%-44% N on a weight basis, the polymer is about 1.2%-3.0% on a weight basis, the intermediate layer is about 0.1%-0.8% on a weight basis, the sulfur layer is about 1.7%-15% on a weight basis and the optional outer layer is about 0.1%-0.8% on a weight basis. 
     
     
         17 . A controlled release fertilizer composition, comprising:
 a) a core comprising one or more plant nutrient materials;   b) a polymer layer coating the core, wherein the polymer layer comprises a polymer formed on the core from two or more precursor compounds;   c) a sulfur layer overlying the polymer layer;   d) an intermediate layer coated between the polymer layer and the sulfur layer, wherein the intermediate layer comprises a lubricant; and   e) optionally an outer, water-insoluble layer.   
     
     
         18 . A method of producing a controlled release fertilizer composition, comprising the steps of:
 a) coating one or more plant nutrient materials with two or more precursor compounds under conditions effective to form a polymer layer coating a core comprising the one or more plant nutrient materials;   b) coating a lubricant onto the polymer layer;   c) applying molten sulfur onto the lubricant under conditions effective to form a sulfur layer comprising solidified sulfur; and   d) optionally applying an outer layer onto the sulfur layer.   
     
     
         19 . The method of  claim 18 , wherein the one or more plant nutrients comprise urea. 
     
     
         20 . The method of  claim 18  wherein after the lubricant comprises intermediate petroleum wax, alpha olefin wax, polyethylene wax, paraffin wax, silicon wax, slack wax, microcrystalline wax, or natural wax. 
     
     
         21 . The method of  claim 18 , wherein the two or more than two precursor compounds are a polyisocyanate and a polyol and the step of coating the one or more plant nutrients with two or more than two precursor compounds reactive to form a polymer is at a temperature sufficient to form a polyurethane polymer. 
     
     
         22 . The method of  claim 11 , wherein the one or more plant nutrients are about 37%-44% N on a weight basis, the thermoset polymer is about 1.2%-3.0% on a weight basis, the lubricant is about 0.1%-0.8% on a weight basis, the sulfur is about 1.7%-15% on a weight basis and the optional outer layer is about 0.1%-0.8% on a weight basis. 
     
     
         23 . A method of producing a controlled release fertilizer composition, comprising the steps of:
 a) coating a lubricant onto a particle comprising a polymer layer that coats a core comprising at least one plant nutrient material;   b) coating molten sulfur onto the lubricant under conditions such that the lubricant helps the molten sulfur form a more uniform sulfur coating comprising solidified sulfur.   
     
     
         24 . A method of producing a controlled release fertilizer particle comprising the steps of:
 a) coating one or more plant nutrients with two or more than two precursor compounds reactive to form a polyurethane polymer layer;   b) applying a lubricant onto the polymer layer;   c) spraying molten elemental sulfur onto the lubricant to form a sulfur layer; and   d) applying a wax layer onto the sulfur layer to form the controlled release fertilizer particle.   
     
     
         25 . The controlled release fertilizer of  claim 24 , wherein the lubricant comprises a component selected from the group consisting of a wax, an oil, a lubricant, a surfactant, and a combination thereof. 
     
     
         26 . The controlled release fertilizer of  claim 25 , wherein the lubricant comprises a wax. 
     
     
         27 . The controlled release fertilizer of  claim 26 , wherein the lubricant comprises intermediate petroleum wax, alpha olefin wax, polyethylene wax, paraffin wax, silicon wax, slack wax, microcrystalline wax, or natural wax. 
     
     
         28 . The controlled release fertilizer of  claim 24 , wherein the wax layer comprises intermediate petroleum wax, alpha olefin wax, polyethylene wax, paraffin wax, silicon wax, slack wax, microcrystalline wax, or natural wax.