Abstract: Stable, pourable silicon dioxide dispersion, in which the average, number-related aggregate diameter of the silicon dioxide particles in dispersion is less than 200 nm, and which comprises at least 35 wt. % of a silicon dioxide powder, 3 to 35 wt. % of at least one polyol, 20 to 60 wt. % of water, 0 to 10 wt. % of an additive and a substance having an alkaline action in an amount such that a pH of 10<pH<12 is established. It can be prepared by a procedure in which silicon dioxide powder is introduced into water and a polyol in a rotor/stator machine, the pH being less than 5, and the mixture is dispersed until the current uptake of the rotor/stator machine is largely constant, and a substance having an alkaline action is subsequently added in an amount such that a pH of the dispersion of 10<pH<12 results, the substance having an alkaline reaction being added so rapidly that no gel formation takes place.

Abstract: Provided is a process for preparing surface-modified silicon dioxide particles with a mean particle diameter of at most 100 nm, involving (A) high-pressure grinding of a predispersion having (i) surface-modified silicon dioxide particles which are at least partly aggregated, are bonded to the surface-modifying component via Si—O—Si bonds, and still have reactive groups on their surface; (ii) an organosilicon compound which has a silicon-carbon bond and a functional group which can react with the reactive groups to form a covalent Si—O—Si bond; and (iii) a solvent, to form a dispersion; and (B) removing the liquid phase of the dispersion. Also provided are redispersible, surface-modified silicon dioxide particles obtained by this process, and their use in toner powders, silicone rubber, adhesives, and scratch-resistance surface coatings.

Abstract: Aqueous dispersion which comprises hydrophobized silicon dioxide particles and in each case one or more dispersing additives, a basic composition, and which is free of color pigments, inactive fillers and binders, in which the hydrophobized silicon dioxide particles have a methanol wettability of 30 to 60 and are present in the dispersion with a proportion of 0.

Abstract: Process for preparing a dispersion of surface-modified silicon dioxide particles having an average particle diameter of not more than 100 nm by high-pressure milling of a preliminary dispersion comprising a) 10% to 50% by weight of surface-modified silicon dioxide particles, b) at least one glycol monoether of the general formula (A): H3C(CH2)m—O—(CH2)n—[O—(CH2)o]p—OH, c) at least one carboxylic ester of the general formula (B): H2x+1Cx—O—CH2—(CHR)—[O—CHR]y—O—C(?O)—CzH2z+1, d) the molar ratio A/B being 10:90 to 40:60 and m, n, o, p, x, y and z being independent of one another. Dispersion obtainable by this process. Process for producing granules of surface-modified silicon dioxide particles by separating off the liquid phase of the dispersion. Granules obtainable by this process. Use of dispersion and granules in coating materials.

Abstract: Process for preparing surface-modified silicon dioxide particles with a mean particle diameter of at most 100 nm, comprising the steps of: a) providing a predispersion b) high-pressure grinding of the predispersion to form a dispersion c) removing the liquid phase of the dispersion, the predispersion comprising a1) surface-modified silicon dioxide particles which are at least partly aggregated, are bonded to the surface-modifying component via Si—O—Si bonds and still have reactive groups on their surface, a2) one or more organosilicon compounds which have at least one silicon-carbon bond and at least one functional group which can react with the reactive groups to form a covalent Si—O—Si bond, and a3) one or more solvents. Redispersible, surface-modified silicon dioxide particles obtainable by this process. Use of these in toner powders, silicone rubber, adhesives and scratch-resistance surface coatings.

Abstract: Aqueous dispersion which comprises hydrophobized silicon dioxide particles and in each case one or more dispersing additives, a basic composition, and which is free of colour pigments, inactive fillers and binders, in which the hydrophobized silicon dioxide particles have a methanol wettability of 30 to 60 and are present in the dispersion with a proportion of 0.

Abstract: Stable, pourable silicon dioxide dispersion, in which the average, number-related aggregate diameter of the silicon dioxide particles in dispersion is less than 200 nm, and which comprises at least 35 wt. % of a silicon dioxide powder, 3 to 35 wt. % of at least one polyol, 20 to 60 wt. % of water, 0 to 10 wt. % of an additive and a substance having an alkaline action in an amount such that a pH of 10<pH?12 is established. It can be prepared by a procedure in which silicon dioxide powder is introduced into water and a polyol in a rotor/stator machine, the pH being less than 5, and the mixture is dispersed until the current uptake of the rotor/stator machine is largely constant, and a substance having an alkaline action is subsequently added in an amount such that a pH of the dispersion of 10<pH?12 results, the substance having an alkaline reaction being added so rapidly that no gel formation takes place.

Abstract: A dispersion containing aluminum oxide of pyrogenic origin and water, where the aluminum oxide is present in the form of aggregated primary particles with a BET surface area of 20 to 200 m2/g and has a mean, volume-based aggregate diameter in the dispersion of less than 100 nm, and is surface-modified with (i) organophosphonic acids, or salts thereof, and (ii) at least one hydroxycarboxylic acids or salts thereof.

Abstract: Process for preparing an alkaline dispersion of aggregated silicon dioxide particles by dividing a preliminary dispersion within a pH of 3 to 5 into at least two streams, placing these streams under a pressure of at least 50 bar and depressurizing them to a collision point, each via one nozzle, in a grinding chamber, and admixing the dispersion that runs off at the bottom, while still in the grinding chamber, with an alkaline substance in an amount such that the dispersion overall has a pH of more than 7.

Abstract: An aqueous dispersion that can be used in the coating of glass, ceramics and metal surfaces is prepared by placing, in water, an aggregated titanium dioxide powder having a specific surface area of from 20 to 150 m2/g in such an amount that the desired dispersion contains at least 20 wt. % titanium dioxide, and at least one amino alcohol having from 1 to 6 carbon atoms, and at least one carboxylic acid selected from dibasic carboxylic acids and/or hydroxycarboxylic acids having from 2 to 6 carbon atoms. A pre-dispersion is produced by introducing energy in an amount of less than 200 kJ/m3. Then a dispersion is produced in which the aggregated titanium dioxide powder has a mean, volume-related aggregate diameter of less than 150 nm by grinding the pre-dispersion with a high-energy mill at a pressure of at least 500 bar.

Abstract: Stable, pourable silicon dioxide dispersion, in which the average, number-related aggregate diameter of the silicon dioxide particles in dispersion is less than 200 nm, and which comprises at least 35 wt. % of a silicon dioxide powder, 3 to 35 wt. % of at least one polyol, 20 to 60 wt. % of water, 0 to 10 wt. % of an additive and a substance having an alkaline action in an amount such that a pH of 10<pH<12 is established. It can be prepared by a procedure in which silicon dioxide powder is introduced into water and a polyol in a rotor/stator machine, the pH being less than 5, and the mixture is dispersed until the current uptake of the rotor/stator machine is largely constant, and a substance having an alkaline action is subsequently added in an amount such that a pH of the dispersion of 10<pH<12 results, the substance having an alkaline reaction being added so rapidly that no gel formation takes place.

Abstract: Dispersion containing aluminium oxide and water, wherein the aluminium oxide is present in the form of aggregated primary particles with a BET surface area of 20 to 200 m2/g and has a mean, volume-based aggregate diameter in the dispersion of less than 100 nm, is modified with organophosphonic acids and/or salts thereof, wherein the surface is completely or partially modified, the organophosphonic acids bear at least one amino and/or hydroxy group and is present in a content of 20 to 70 wt. %, based on the total quantity of the dispersion. Preparation containing this dispersion and a melamine resin. Cured product obtainable from the preparation. Use of the dispersion, of the preparation or of the cured product for the preparation of laminates.

Abstract: Aqueous dispersion obtainable by placing in water an aggregated titanium dioxide powder having a specific surface area of from 20 to 150 m2/g in such an amount that the desired dispersion comprises at least 20 wt. % titanium dioxide, and at least onc amino alcohol having from 1 to 6 carbon atoms, and at least one carboxylic acid from the group comprising dibasic carboxylic acids and/or hydroxycarboxylic acids having from 2 to 6 carbon atoms,—the amino alcohol being present in the dispersion in an amount of from 2.5 to 7.0 ?mol./m2 specific surface area TiO2 and the carboxylic acid being present in an amount of from 1.0 to 3.5 ?mol./m specific surface area TiO2,—producing a pre-dispersion by introducing energy in an amount of less than 200 kJ/m3 and then producing a dispersion in which the aggregated titanium dioxide powder has a mean, volume-related aggregate diameter of less than 150 nm by grinding the pre-dispersion by means of a high-energy mill at a pressure of at least 500 bar.