GB908493A - Fertilizer compositions - Google Patents

Abstract

A fertilizer composition of reduced caking tendency and improved resistance to leaching by water comprises a fertilizer and one or more polyoxyalkylene compounds with average molecular weights at least 10,000. The proportion of such compounds may be high, e.g. 30-40% by weight of the composition, but is preferably 0,5-1% by weight. Preferably at least 50%, generally more than 90%, of the surface area of each particle or granule of fertilizer is coated with the polymer. The fertilizer may be slurried or sprayed with a solution of the polyoxyalkylene compounds in an organic solvent, e.g. an aromatic hydrocarbon, an alcohol, ether, glycol or glycol ether, with subsequent removal of solvent, e.g. by evaporation. When more than one polyoxyalkylene compound is used, the fertilizer granules may be coated successively with each one, or granules coated with different compounds may be subsequently mixed. The polyoxyalkylene compounds have the formula R1-O-[CnH2nO]m-R2 or R1-O-(XO)m-R2 where R1 and R2 are hydrogen or hydrocarbon or acyl radicals, X is an alpha-phenylethylene group and n and m are integers. The oxyalkylene compounds comprising the polyoxyalkylene chain preferably contain 2-4 carbon atoms; compounds prepared from ethylene oxide and 1,2-propylene oxide are particularly suitable. Among the catalysts are mentioned complexes of an alkylene oxide with ferric or stannic chloride. The oxyalkylene radicals in the chain may be of one type or may be different, either randomly distributed or in blocks. In addition to polyoxyalkylene compounds, the composition may contain other polymers, e.g. a polysiloxane, which may be incorporated into the polyoxyalkylene chain. The fertilizer may contain, e.g. phosphates, superphosphates, nitrates or sulphates of alkali or alkaline-earth metals or of ammonium, urea and its salts, and trace elements, e.g. cobalt and manganese. In an example, a mixture of ammonium nitrate, potassium chloride and diammonium phosphate is coated with 20, 30 and 40% by weight of polyethylene glycol of approximately molecular weight 300,000.ALSO:A fertilizer composition of reduced caking tendency and improved resistance to leaching by water comprises a fertilizer and one or more polyoxyalkylene compounds with average molecular weights at least 10,000. The proportion of such compounds may be high, e.g. 30-40% by weight of the composition, but is preferably 0,5-1% by weight. Preferably at least 50%, generally more than 90%, of the surface area of each particle or granule of fertilizer is coated with the polymer. The fertilizer may be slurred or sprayed with a solution of the polyoxyalkylene compounds in an organic solvent, e.g. benzene, with subsequent removal of solvent, e.g. by evaporation. When more than one polyoxyalkylene compound is used, the fertilizer granules may be coated successively with each one, or granules coated with different compounds may be subsequently mixed. The polyoxyalkylene compounds have the formula R1-O- [CnH2nO]mR2 or R1-O-(XO)m-R2 where R1 and R2 are hydrogen or hydrocarbon or acyl radicals, X is an alphaphenylethylene group and n and m are integers. The oxyalkylene compounds comprising the polyoxyalkylene chain preferably contain 2-4 carbon atoms; compounds prepared from ethylene oxide and 1, 2- propylene oxide are particularly suitable. The oxyalkylene radicals in the chain may be of one type or may be different, either randomly distributed or in blocks. In addition to polyoxyalkylene compounds, the composition may contain other polymers, e.g. a polysiloxane, which may be incorporated into the polyoxyalkylene chain. The fertilizer may contain, e.g., phosphates, superphosphates, nitrates or sulphates of alkali or alkaline earth metal or of ammonium, urea and its salts, and trace elements, e.g. cobalt and manganese. In an example, a mixture of ammonium nitrate, potassium chloride and diammonium phosphate is coated with 20, 30 and 40% by weight of polyethylene glycol of approx, molecular weight 300,000.