Process for producing ammonium polyphosphate which gives a low-viscosity aqueous suspension

US5043151A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Thomas Staffel · Grünstadt, DE
• Renate Adrian · Hürth, DE

Key dates

• Filing date: Jul 20, 1990
• Grant date: Aug 27, 1991
• Expiry date: Jul 20, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B25/405
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process for producing essentially water-insoluble, chain-type ammonium polyphosphates of the general formula (NH.sub.4 PO.sub.3).sub.n, in which n is a number from 10 to 1,000, whose 20% by weight aqueous suspension prepared at 60.degree. C. has a viscosity of less than 100 mPa.s at 20.degree. C., is indicated, which comprises allowing a reaction mixture of ammonium orthophosphate and phosphorus pentoxide to react fully at a high mixing intensity in a crumbly phase at a temperature from 100.degree. to 300.degree. C. over a period of from 10 to 60 minutes and then heat-treating the reaction material in a known manner over a period of from 50 to 200 minutes at a temperature from 200.degree. to 300.degree. C. under an ammonia atmosphere. Advantageously, the reaction is carried out in a kneader.