GB1103772A - Phosphates - Google Patents

Abstract

Acyclic chain condensed ammonium phosphates or ammonium metal phosphates are made in a process wherein (I) at least one ammonium orthophosphate and/or (II) at least one metal phosphate containing at least one acid hydrogen atom or (III) a mixture of (I) and/or (II) with phsophoric acid in an amount such that there are at most 4 P atoms for every NH4 group or metal equivalent present is reacted with at least one carbon-nitrogen compound, or an adduct thereof with phosphoric acid, at a temperature of 110-450 DEG C. In the starting mixture the N:P ratio is not greater than 5:1. Preferably in this mixture there is at least 0.3 gm. atom of nitrogen for every mole of water evolved. In the final product the N:P ratio is not lower than 0.5:1 if ammonium polyphosphates are produced, and if ammonium metal polyphosphates are produced the N:P ratio is not lower than 0.3:1 and the ratio of nitrogen atoms metal equivalents to P atoms is at least 0.5:1. The carbon-nitrogen compound releases ammonia on heating or hydrolysis and may have the general formula <FORM:1103772/C1/1> or <FORM:1103772/C1/2> wherein X represents O, S, or NH. R1 represents H, alkyl, alkoxy or acid amide having up to 3 carbon atoms or an NH2, NHNH2 or an HN.CX.R6 group wherein R6 represents any R1 group except the last or X and R1 or X and R6 together represent (­N); R2 represents an NH2, SNH4 or ONH4 group; and R3, R4 and R5 are the same or different and each represent one of the groups OH or NH2. Specified carbon-nitrogen compounds are formamide, oxamide or acetamide, biuret, semicarbazide, dicyandiamide, urea, urea - phosphoric acid addition product, thiourea, guanidine, ethylurethane, cyanuric acid, melamine, ammeline, ammelide and cyanamide. The metal may be K, Na, Ca, Mg, Sr, Ba, Al, Fe, Cu, Mn, Co, Ni, Cr, Zn, Sn, Pb or Hg. Water or ammonia may be added to the mixture. The reaction may be conducted at ordinary, elevated or reduced pressures, and may be in an inert solvent. Polyphosphates having an average degree of condensation between 2 and 1000 may be produced and they can be amorphous or crystalline. A 1% aqueous sol. has a pH in the range 2 to 9. A modification of the process is to react the carbon-nitrogen compound (other than urea or a urea phosphoric acid adduct) with H3PO4 or a mixture of H3PO4 and (B1) an NH4 orthophosphate (B2) urea, (B3) a urea phosphoric acid addition product, or (B4) a mixture of (B1), (B2) or (B3).