Synthesis of Melamine Polyphosphate with Low Residual Melamine Content
Patent Information
- Authority / Receiving Office
- RU · RU
- Patent Type
- Applications
- Current Assignee / Owner
- BASF SE
- Filing Date
- 2023-02-09
- Publication Date
- 2026-07-06
Claims
1. A method for producing melamine polyphosphate with a reduced melamine content, comprising heating crude melamine polyphosphate for a holding time of at least one hour to a holding temperature above 290°C.
2. The method according to claim 1, characterized in that the unrefined melamine polyphosphate has a residual melamine concentration of at least 0.2 wt.% melamine.
3. The method according to claim 1, characterized in that the melamine polyphosphate with a reduced melamine content has a residual melamine concentration of less than 0.2 wt.%, 0.1 wt.%, or 0.05 wt.%.
4. The method according to claim 1, characterized in that the holding temperature is at least 295, 300, 305, 310 or 315°C.
5. The method according to claim 1, characterized in that the holding time is at least 1, 2, 3, 4 or 5 hours.
6. The method according to claim 1, characterized in that during the holding time the unrefined melamine polyphosphate is subjected to purging with an inert gas or is subjected to a vacuum.
7. The method according to claim 1, characterized in that the crude melamine polyphosphate is obtained by polymerizing melamine phosphate with a polymerization time of at least 0.5 hours at a polymerization temperature in the range from 200 to 290°C.
8. The method according to claim 7, characterized in that the melamine phosphate contains melamine and phosphoric acid in a molar ratio of 1:1 to 2:1, preferably from 1.2:1 to 1.5:
1.
9. The method according to claim 7, characterized in that melamine phosphate is obtained by heating melamine, phosphoric acid and water above 70°C.
10. The method according to claim 7, characterized in that the melamine phosphate is obtained by adding phosphoric acid and water to melamine powder.
11. The method according to one of paragraphs 1-10, characterized in that the melamine polyphosphate with a reduced melamine content contains from 1 to 30% by weight of melam polyphosphate.
12. A melamine polyphosphate with reduced melamine content, which contains residual melamine, and the concentration of residual melamine is less than 0.2 wt.%, 0.1 wt.% or 0.05 wt.%.
13. Melamine polyphosphate with reduced melamine content according to claim 12, which contains from 1 to 30% by weight of melam polyphosphate.
14. Melamine polyphosphate with reduced melamine content according to claim 12, which contains from 0.01 to 5.0 wt.% melamine polyphosphate.
15. A melamine polyphosphate with a reduced melamine content according to one of claims 12-14, characterized in that the melamine polyphosphate with a reduced melamine content is obtainable by a method as defined in one of claims 1-11, comprising heating the crude melamine polyphosphate for a holding time of at least one hour to a holding temperature above 290°C.
16. A polymer composition comprising a melamine polyphosphate with a reduced melamine content, as defined in one of claims 13-15, or obtained by a method as defined in one of claims 1-11.