Abstract Production of chain ammonium polyphosphates of the general formula (NH4)n 2PnO3n 1 by the reaction of a polyphosphoric acid with gaseous ammonia. Ammonium polyphosphates with a chain length n longer than that of the feed polyphosphoric acid are produced by heating a polyphosphoric acid with a P2O5-content higher than 76 weight percent to a temperature between 80* and 100* C.; introducing gaseous ammonia thereinto while arresting the supply of further heat; allowing the temperature in the reaction mixture to increase under the action of the heat of neutralization set free; maintaining the reaction mixture, if necessary by cooling, between 300* and 330* C. until the temperature itself commences to fall below 300* C; allowing the reaction mixture to stand at temperatures between 230* and 270* C., which are maintained, if necessary by supplying further heat, until formation of a viscous crystalline magma which practically ceases to absorb further ammonia; cooling the reaction product, washing it and drying it at temperatures lower than 100* C.
The process of claim 1, wherein ammonium polyphosphates with a mean chain length n between 20 and 90 are produced by annealing the isolated reaction product for a period of at least 15 minutes, at a temperature between 100* and 320* C. in an atmosphere of ammonia having between 1 and 5 percent by volume steam therein.
Claim 2
Dependent Claim
44 words
The process of claim 1, wherein ammonium polyphosphates with a mean length n between 100 and 400 are produced by annealing the isolated reaction product for a period of at least 15 minutes, at temperatures between 220* and 320* C. in an ammonia atmosphere.
Claim 3
Dependent Claim
18 words
The process of claim 1, wherein the polyphosphoric acid has a P2O5-content between 82 and 86 weight percent.
Claim 4
Dependent Claim
28 words
The process of claim 1, wherein the reaction mixture is maintained at a temperature between 310* and 320* C. by cooling it while the ammonia is introduced thereinto.
Claim 5
Dependent Claim
34 words
The process of claim 1, wherein, once the temperature has dropped down to 300* C., the reaction mixture is maintained at a temperature between 245* and 255* C. until formation of a crystalline magma.