Method for manufacturing a fine crystalline boehmite and application of the boehmite as a flame retardant agent in plastics

摘要

Process for the production of boehmite (I) comprises: mixing aluminum monohydrate with a boehmite crystal structure in water to form an aqueous dispersion of the aluminum monohydrate in the water; grinding the formed dispersion, while maintaining the dispersion in a pH of 2-4 and forming boehmite seed crystals; mixing a hydrate and the boehmite seed crystals in a basic aqueous solution to form a sufficient dispersion; and heating the obtained dispersion at 110-180[deg]C to autocatalytically convert at least a substantial portion or essentially all of the aluminum monohydrate to boehmite. Process for the industrial production of boehmite (I) comprises: mixing aluminummonohydrate with a boehmite crystal structure in water to form an aqueous dispersion of the aluminum monohydrate in the water; grinding the formed dispersion, while maintaining the dispersion in a pH of 2-4 and forming boehmite seed crystals; mixing a hydrate and the boehmite seed crystals in a basic aqueous solution to form a sufficient dispersion of the hydrate and the boehmite seed crystals in the basic aqueous solution; and heating the obtained dispersion at 110-180[deg]C to autocatalytically convert at least a substantial portion or essentially all of the aluminum monohydrate to boehmite with a median grain size diameter of 50-400 nanometers and a surface of 10-40 meters squared per gram, measured by the Braunauer-Emmet-Teller method. An independent claim is included for a boehmite comprising a median grain size diameter of 50-400 nanometers, a Braunauer-Emmet-Teller surface of 10-40 meters squared per gram and a pore volume of 0.05-0.5 centimeters cubed per gram measured according to Gurwitsch method.