US 4,639,331 AGranted

Process for making pulverulent ammonium polyphosphates stable to hydrolysis

AssigneeHoechst Aktiengesellschaft

InventorsGeorg Elsner, Horst Staendeke, Gero Heymer

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Abstract

The disclosure relates to a process for making a particulate agent stable to hydrolysis based on free-flowing, pulverulent ammonium polyphosphate by treating the ammonium polyphosphate with a thermosetting, artificial resin being water-insoluble when cured. More specifically, the disclosure provides for the ammonium polyphosphate, an aliphatic alcohol as a diluent, and a melamine/formaldehyde-resin or phenol/formaldehyde-resin to be placed in an autoclave and intimately mixed at room temperature; for the mixture to be heated to a temperature of about 80.degree. to about 180.degree. C. and allowed to remain over a period of 15 to 240 minutes at that temperature and under the pressure corresponding to the vapor pressure of the diluent; for the diluent to be separated and for the product so obtained to be dried.

Claims8

Dependent claims

Process for making a particulate, free-flowing, pulverulent ammonium polyphosphate of the general formula

H.sub.(n-m)+2 (NH.sub.4).sub.m P.sub.n O.sub.3n+1
in which n stands for a whole number having an average value of about 20 to 800 and the m/n ratio is about 1, wherein 75 to 99 parts by weight ammonium polyphosphate are encapsulated with 1 to 25 parts by weight melamine/formaldehyde-resin or phenol/formaldehyde-resin, which comprises:
placing particulate ammonium polyphosphate, an aliphatic C.sub.1 -C.sub.4 alcohol as a diluent, and melamine/formaldehyde-resin or phenol/formaldehyde-resin in an autoclave and initmately mixing them as a suspension at room temperature therein, heating the suspension to a temperature of 80.degree. to 180.degree. C., allowing the mixture to remain over a period of 15 to 240 minutes at that temperature, cooling the mixture to room temperature, separating the alcohol and dring the product so obtained.

Dependencies are inferred from the claim text.