Melamine cyanurate-contg. mixts., useful as fire-retardant fillers - formed by heating melamine with alkaline earth metal di:hydrogen phosphate and neutralising it necessary with melamine or ammonia

摘要

A process is claimed for the prodn. of melamine cyanurate-contg. phosphate mixts. with ammonium, melamine and alkaline earth metal cations, with the formula aC3H6N6.C3H3O3N3 + bC3H6N6 + cNH3 + 2P2O5 + 2MO + dH2O (I); C3H6N6.C3H3O3N3 = melamine cyanurate (II); C3H6N6 = melamine (III); M = alkaline earth metal(s); a = 0.05-0.9; b = 0.1-1.9; c = (4-b)-(2-b); d = 1-3; the process involves heating alkaline earth dihydrogen phosphate(s) or hydrate(s) thereof (IV) (with M = Mg, Ca, Sr and/or Ba) with (III), with mol. ratio (P):(III) = (2.3:1)-(7:1) for 5-300 mins. at 150-380 deg.C, cooling the prod. and (if the reaction mixt. gives an acid reaction on mixing with water) neutralising by reaction with (III) and/or ammonia for 0.5-300 mins. at 10-250 deg.C. In more detail, reaction is carried out for 10-150 mins. at 240-320 deg.C, with mol. ratio (P):(III) = (3:1)-(4.5:1), and the acidic prod. is neutralised with 0.02-0.65 mol. (III)/2 mols. P (pref. by grinding the mixt.) or with 0.05-5 mols. ammonia/2 mols. P, for 1-180 mins. at 15-200 deg.C; reaction of (III) with (IV) is carried out as a continuous reaction in a heated conveyor/stirred reactor; (IV) also contain(s) a sulphate or sulphate hydrate of M, with mol. ratio (S):(P) = (0.01:1)-(3:1) and is obtd. by reaction of the corresp. phosphate(s) (in which mol. ratio M:P = above 0.5) with H2SO4; the resulting mixed phosphate/sulphate is pref. superphosphate. USE/ADVANTAGE - Provides a 1-stage process for the prodn. of neutral mixts. (I) from cheap starting materials such as superphosphate; the prods. are useful as fire retardant fillers for plastics, coating materials and paints etc