FINELY DISPERSED PRECIPITATED ALUMINUM HYDROXIDE AND METHOD FOR ITS PRODUCTION Russian patent published in 2022 - IPC C01F7/34 C01F7/14 B22F9/16 

FIELD: technological processes.

SUBSTANCE: invention relates to production of highly dispersed precipitated aluminum hydroxide used as fire retardant and filler. Highly dispersed precipitated aluminum hydroxide is presented in the form of rounded particles in an amount of not less than 90 %, note here that D50 particle size makes not over 10 mcm while D99/D10 particle size makes 7–12. When producing highly dispersed precipitated aluminum hydroxide, alkaline aluminate and neutralizing solutions are mixed. Neutralizing solution used is an aqueous solution containing bicarbonates and carbonates of alkali metals. Neutralization is carried out until residual content of Na₂O_ku in the mixed solution is 7–15 g/l. Pulp formed after mixing the solutions is stirred for at least 30–240 minutes under the effect of a liquid phase shear rate of 10–210 s^-1, after which the precipitate is thickened, filtered and washed. Obtained aluminum hydroxide can be modified by at least one surface-treating agent and/or a binding silane agent.

EFFECT: considerable reduction of polymer melt viscosity and filler abrasiveness, minimized chalking of compound surfaces.

6 cl, 4 dwg, 3 tbl, 8 ex