Study On Polymer Emulsion Coated Fertilizer For Slow/Controlled-release

Slow/controlled-release fertilizer can significantly improve the utilization rateof fertilizers, ensure food security, accelerate the income increasing of farmer, alsocan protect the environment, increase the energy conservation and emissionsreduction. Because of the high fertilizer use efficiency and long release period，Polymer-coated slow/controlled-release fertilizer is widely used, but a lot ofpollution are caused in the production and using process. To solve the problem, anew type of polymer latex coated fertilizer is developed, the emulsionpolymerization process and coated process are researched.In this paper, the coating material was synthesized by the semi-continuousseeded emulsion polymerization and pre-emulsification technology. And we alsoinvestigated the effects of weight ratio of hard and soft monomer, oil to water, thedosage of initiator, the amount of emulsifier and the amount of additives on theperformance, the intrinsic viscosity, the solid content of emulsion and slow-releaseproperty of coated urea. The optimum conditions of emulsion polymerization wereobtained as follows: the mass proportion of hard and soft monomer is2:1, oil-watermass ratio is100:120, the weight fraction of emulsifier is2.4%, theweight fraction of is0.5%, the weight fraction of additives is2.0%. The emulsionpolymerized in the conditions is white with blue light. The fertilizer coated byemulsion have excellent slow-release performance.The emulsion coating process was also studied in a drum coating machine. Theemulsion nebulized by high pressure spray gun coated hot urea. The effects of coatedangle, rotational speed, coated temperature, amount of coated emulsion, emulsionspraying time and amount of sealant on the slow-release property of coated ureawere discussed. The optimum conditions of emulsion coating process were as follows: theangle of drum is45°, the speed of drum is50r/min, the temperature is50℃, theemulsion/urea ratio is20%, coating time is30min, wax as sealants. The slow-releaseperformance of fertilizer producted in the conditions is good，the initial release rate of nutrient is9%which meet the national standard about slow release fertilizer.