Magnesium process
AssigneeFlamemag International Gie
InventorsDagwin Elsner, Roger Norman Rothon
Life of this patent
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Abstract
The present invention provides a process for preparing a flame retardant quality magnesium hydroxide which includes providing a magnesium salt solution; and a source of ammonia; adding a stochiometric excess of ammonia to the solution to form a magnesium hydroxide precipatate; and subjecting the magnesium hydroxide to a hydrothermal recrystallization.
Claims20
A process for preparing a flame retardant quality magnesium hydroxide which includes
- providing
- a magnesium oxide-containing material;
- an
- ammonium salt selected from the group consisting of ammonium nitrate (NH.sub.4 NO.sub.3) and ammonium chloride (NH.sub.4 Cl);
- and
- a source of ammonia;
- leaching the magnesium oxide-containing material with the ammonium salt to form a magnesium salt solution;
- adding a stoichiometric excess of ammonia to the magnesium salt solution to form a magnesium hydroxide precipitate;
- recycling at least a portion of the ammonium nitrate or ammonium chloride formed as a by-product in the addition step to the leaching step;
- and
- subjecting the magnesium hydroxide to a hydrothermal recrystallisation at a superatmospheric pressure.
A process for preparing a flame retardant quality magnesium hydroxide which includes
- providing
- a magnesium chloride solution;
- and
- a source of ammonia;
- adding a stoichiometric excess of ammonia to the solution to form a magnesium hydroxide precipitate;
- and
- subjecting the magnesium hydroxide to a hydrothermal recrystallisation at a superatmospheric pressure.
A process for preparing flame retardant quality magnesium hydroxide which includes
- providing
- a relatively pure magnesium salt solution;
- and
- a source of ammonia;
- adding a stoichiometric excess of ammonia to the relatively pure magnesium salt solution to form a magnesium hydroxide precipitate;
- and
- subjecting the magnesium hydroxide to a hydrothermal recrystallisation at superatmospheric pressure and at a temperature of approximately 170.degree. C. to approximately 185.degree. C.
A flame retardant quality magnesium hydroxide having
- a BET surface area of less than approximately 8 m.sup.2 per gram (uncoated),
- an average particle size of approximately 0.5 to 5.0 micron, less than approximately 0.5% of particles over 10 micron (average particle size measured by laserlight scattering method), and an oil absorption less than approximately 60 ml/100 g (oil absorption measured under International Standard (ISO 787/5-1980(E)).
A coated magnesium hydroxide product including
- a flame retardant quality magnesium hydroxide containing hexagonal crystals or crystals being generally oval in cross-section, with a low BET specific surface area less than approximately 7 m.sup.2 /g, a median particle size of approximately 0.5 to 5.0 micron and an oil absorption less than approximately 60 mL/100 g (oil absorption measured under International Standard ISO 787/5-1980(E));
- and
- an anionic surface active agent selected from the group consisting of stearic acid, oleic acid, lauric acid, palmitic acid, sodium stearate, potassium behenate, sodium montanate, potassium stearate, sodium oleate, potassium oleate, sodium palmitate, potassium palmitate, sodium laurate, potassium laurate, sodium dilauryl benzenesulfonate, potassium octadecylsulfate, sodium laurylsulfonate, disodium 2-sulfoethyl .alpha.-sulfostearate and ammonium salts of fatty acids, and mixtures thereof coated on the magnesium hydroxide.
A polymeric composition including
- a thermoplastic polymer;
- and
- a magnesium hydroxide component containing hexagonal crystals or crystals being generally oval in cross section with a low BET specific surface area less than 7 m.sup.2 /g, a median particle size of approximately 0.5 to 5.0 micron and an oil absorption less than approximately 60 mL/100 g (oil absorption measured under International Standard ISO 787/5-1980(E)).
Dependencies are inferred from the claim text.