US4687651A
Expired / Lapsed
US
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Method for producing ammonium polyphosphate
Assignee: NU-CHEM A CORP OF
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Filing: 1985-10-15
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Granted: 1987-08-18
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Expires: 2005-10-15
Abstract
Abstract A method of continuously producing ammonium polyphosphate by the reaction of urea and polyphosphoric acid, over a wide range of molecular weights, in a pre-mix slurry, under controlled temperature of about 315°+/-15° C. The slurry is reacted on a hot, continuously moving surface and forms ammonium polyphosphate in an ammonia atmosphere. Preferably, the pre-mixed slurry is added to a screw-type extruder, where the material comes in contact with the ammonia along the preheated moving surfaces of the extruder. The ammonium polyphosphate is scraped from the extrusion screw into a container with minimum handling. The material can be ground to a finer consistency if desired.
Inventors
- 👤 John A. Parker
- 👤 Rubin Feldman
- 👤 Robert L. Bryant
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:57
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/38; C01B25/40; C01B25/405
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
86 words
A process for the manufacture of substantially water-insoluble ammonium polyphosphate, comprising a step of mixing one part of a polyphosphoric acid having an equivalent phosphoric acid content of at least about 110% and an excess of urea, to form a partially soluble ammonium polyphosphate having a solubility of about 8% in water, and a second step of heating the partially soluble ammonium polyphosphate under an ammonia atmosphere to a temperature of at least 300° C. for a period sufficient to form a substantially water-insoluble ammonium polyphosphate.
Claim 2
Dependent Claim
86 words
A process for the manufacture of substantially water-insoluble ammonium polyphosphate, comprising a step of mixing one part of a polyphosphoric acid having an equivalent phosphoric acid content of at least about 110% and an excess of urea, to form a partially soluble ammonium polyphosphate having a solubility of about 8% in water, and a second step of heating the partially soluble ammonium polyphosphate under an ammonia atmosphere to a temperature of at least 300° C. for a period sufficient to form a substantially water-insoluble ammonium polyphosphate.
Claim 3
Dependent Claim
24 words
The process of claim 1 wherein said second step is carried out with constant stirring for a period of at least about thirty minutes.
Claim 4
Dependent Claim
20 words
The process of claim 2 wherein said partially soluble ammonium polyphosphate is heated to a temperature of 315° +/-15° C.
Claim 5
Dependent Claim
16 words
The process of claim 1 wherein the reactants consist essentially of said polyphosphoric acid and urea.
Claim 6
Dependent Claim
20 words
The process of claim 4 wherein said partially soluble ammonium polyphosphate is heated to a temperature of 315° +/-15° C.
Claim 7
Dependent Claim
34 words
The process of claim 1 wherein said second step is carried out in a heated extrusion device providing continuous heating of an extruder screw which continuously forces the reaction mixture through a reaction barrel.
Claim 8
Dependent Claim
31 words
The process of claim 6, wherein said second step is carried out in a heated extrusion device having an extruder screw which continuously forces the reaction mixture through a reaction barrel.
Claim 9
Dependent Claim
24 words
The process of claim 7 wherein a mixture of said polyphosphoric acid and said urea is continuously fed into the barrel of said extruder.
Claim 10
Dependent Claim
22 words
The process of claim 1 wherein said ammonium polyphosphate has an equivalent phosphoric acid content of from about 115% to about 120%.
Claim 11
Dependent Claim
26 words
The process of claim 1 wherein said urea is mixed in a quantity of from about 0.5 to 3.0 parts by weight of the polyphosphoric acid.
Claim 12
Dependent Claim
49 words
The process of claim 1 wherein said urea is mixed in a quantity of from about 0.8 to 1.2 parts by weight of the polyphosphoric acid, and wherein the reaction is carried out at a temperature of 305°+/-5° C. for a period of from 30 minutes to 180 minutes.
Claim 13
Dependent Claim
26 words
The process of claim 1 wherein the reaction mixture is heated for a period sufficient to provide an ammonium polyphosphate which is less than 1% soluble.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-17 | 1991-02-16 | 1991-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-17 | 1995-02-16 | 1995-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-17 | 1999-02-16 | 1999-08-18 | $7700.00 | Window Closed / Lapsed |