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: Aluminum oxide dispersion, which is stable in a pH range 5 from 5 to 9 and has an aluminum oxide content of at least 40 wt. %, obtainable by dispersing pyrogenically produced aluminum oxide particles in an aqueous phase, wherein one or several at least dibasic hydroxycarboxylic acids present dissolved in the dispersion and at least one salt of a 10 dialkali metal hydrogen phosphate and/or alkali metal dihydrogen phosphate are added to the aqueous phase each mutually independently in a quantity of 0.3?3×10?6 mol/m2 of aluminum oxide specific surface area.

Abstract: Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps: water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt.

Abstract: Reactor for carrying out chemical and physical materials transformations, which comprises a reaction space enclosed by a reactor housing, where the reactor housing has at least two lateral fluid inlets having adjustably mounted nozzles which include an angle of about 20-160 degrees and through which fluid jets which impinge on one another at a common collision point within the reaction space are passed and the reactor has a fluid outlet at the bottom of the reaction space, which is characterized in that—an exchangeable bottom plate•which has a hole as fluid outlet and•on which moveably supported spheres are located so as to block the original path of the individual fluid jets in the unaligned state rests on the bottom of the reaction space and—a half shell standing upright on the bottom of the reaction space is located between each moveably supported sphere and the wall of the reactor space and—bottom plate, half shell and moveably supported spheres comprise one or more hard materials.

Abstract: An aqueous dispersion for use as a finishing agent for textiles, wherein the dispersion contains a pyrogenically produced, aggregated silicon dioxide powder and a cationic polymer which is soluble in the dispersion, wherein the cationic polymer is present in a quantity such that the particles of the silicon dioxide powder exhibit a positive zeta potential.

Abstract: Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps: water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt.

Abstract: An aqueous dispersion for use as a finishing agent for textiles, wherein the dispersion contains a pyrogenically produced, aggregated silicon dioxide powder and a cationic polymer which is soluble in the dispersion, wherein the cationic polymer is present in a quantity such that the particles of the silicon dioxide powder exhibit a positive zeta potential.

Abstract: Dispersion comprising water and mixed potassium silicon oxide powder, where—the mixed oxide powder is in the form of aggregates of primary particles, has a BET surface area of 100 to 400 m2/g, has an average aggregate diameter in the dispersion of less than 100 nm, and possesses a potassium fraction of 0.05% to 1.5% by weight, calculated as K2O and based on the mixed oxide powder, and—the dispersion has a fraction of mixed oxide powder in the dispersion of 25% to 40% by weight, the sum of water and mixed oxide powder is at least 98% by weight and the pH is 9 to 11.5.

Abstract: Reactor for carrying out chemical and physical materials transformations, which comprises a reaction space enclosed by a reactor housing, where the reactor housing has at least two lateral fluid inlets having adjustably mounted nozzles which include an angle of about 20-160 degrees and through which fluid jets which impinge on one another at a common collision point within the reaction space are passed and the reactor has a fluid outlet at the bottom of the reaction space, which is characterized in that—an exchangeable bottom plate•which has a hole as fluid outlet and•on which moveably supported spheres are located so as to block the original path of the individual fluid jets in the unaligned state rests on the bottom of the reaction space and—a half shell standing upright on the bottom of the reaction space is located between each moveably supported sphere and the wall of the reactor space and—bottom plate, half shell and moveably supported spheres comprise one or more hard materials.

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: An aqueous dispersion for use as a finishing agent for textiles, wherein the dispersion contains a pyrogenically produced, aggregated silicon dioxide powder and a cationic polymer which is soluble in the dispersion, wherein the cationic polymer is present in a quantity such that the particles of the silicon dioxide powder exhibit a positive zeta potential.

Abstract: Dispersion comprising water and mixed potassium silicon oxide powder, where—the mixed oxide powder is in the form of aggregates of primary particles, has a BET surface area of 100 to 400 m2/g, has an average aggregate diameter in the dispersion of less than 100 nm, and possesses a potassium fraction of 0.05% to 1.5% by weight, calculated as K2O and based on the mixed oxide powder, and—the dispersion has a fraction of mixed oxide powder in the dispersion of 25% to 40% by weight, the sum of water and mixed oxide powder is at least 98% by weight and the pH is 9 to 11.5.

Abstract: Aqueous dispersion which comprises hydrophobized silicon dioxide powder with a content of between 5 and 50 wt. % and which comprises at least one compound of the general formula R & supl; —COO—(CH2-CH(Ph)—O)a-(CnH2n-xR2x-O)b-R3 (I). It is prepared by dispersing the hydrophobic silicon dioxide powder, dispersing agent and optionally pH-regulating substances and further additives in an aqueous medium. It can be employed as an additive to waterborne fillers in the automobile industry, as a coating constituent in can and coil coating processes, as an additive in water-based UV-curable formulations e.g. for wood preservation and as a constituent of protective lacquer films.

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: An aqueous dispersion containing pyrogenically prepared oxide particles of titanium, zinc, iron or cerium with an average particle size, expressed as the median, in the dispersion of less than 250 nm, that the particle sizes of the oxide particles in the dispersion are not distributed symmetrically and the dispersion contains, as a dispersant, at least one compound of the formula (I) and/or a maleic anhydride/acrylate copolymer of the general formula (IIa) and/or a maleate/acrylate copolymer of the general formula (IIb). It is prepared by dispersing a predispersion stream by means of a high energy mill. It can be used in sunscreen formulations.

Abstract: Aluminium oxide dispersion, which is stable in a pH range 5 from 5 to 9 and has an aluminium oxide content of at least 40 wt. %, obtainable by dispersing pyrogenically produced aluminium oxide particles in an aqueous phase, wherein one or several at least dibasic hydroxycarboxylic acids present dissolved in the dispersion and at least one salt of a 10 dialkali metal hydrogen phosphate and/or alkali metal dihydrogen phosphate are added to the aqueous phase each mutually independently in a quantity of 0.3?3×10?6 mol/m2 of aluminium oxide specific surface area.