Magnesium hydroxide having fine, plate-like crystalline structure and process therefor
AssigneeThe Dow Chemical Company
InventorSteven F. Mertz
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Abstract
Novel magnesium hydroxide having a fine, plate-like crystalline structure, a median particle size of up to about 1 micron and a particle size distribution in which about 90% of said magnesium hydroxide particles are less than about 3.5 microns is prepared by a flash precipitation process in which less than or greater than an equivalent amount of alkaline material is reacted with a magnesium salt in a concentrated aqueous mixture thereof. Ultrasonic mixing means is used to combine heated aqueous streams of an alkaline material and a magnesium containing solution followed by a post heat treatment. The magnesium hydroxide is especially useful in providing flame retardancy in admixture with thermoplastic resins.
Claims10
A process for the production of a magnesium hydroxide having a particulate, crystalline structure characterized predominantly as having a fine, plate-like form and a median particle size of about 0.7 micron to about 1 micron, a unit layer thickness of 30 to 200 Angstroms, and a particle size distribution in which 80% of said particles are within about 0.3 to about 1.4 microns comprising:
- (A) mixing by ultrasonic mixing means at ambient pressure and ambient or elevated
Dependencies are inferred from the claim text.