Degussa Aktiengesellschaft

Degussa - Huls Ag

Hauke Jacobsen

Stipan Katusic

Werner Hartmann

Ralph Brandes

Kai Schumacher

Andreas Schulz

Jorg Sperlich

Juergen Meyer

Stefan Wieland

Karl-Anton Starz

Uwe Schachtely

Martin Moerters

Emmanuel Auer

Naruyasu Ishibashi

Heike Riedemann

Takeyoshi Shibasaki

Matthias Rochnia

Norbert Giesecke

Hans Lansink-Rotgerink

Henning Karbe

Thomas Hennig

Pyrogenically produced silica powder with a BET surface of 30 to 90 m/g, a dibutyl phthalate number of at least 80 and a tamped density of no more than 110 g/l. It is produced in that at least one vaporous silicon compound, a gas containing free oxygen and a combustible gas are mixed together in a closed burner and then burnt in a flame in the flame tube of the burner, the solid obtained is separated from the gas mixture and optionally purified, wherein the oxygen content of the gas containing free oxygen is adjusted such that the lambda value is greater than or equal to 1, and the gamma value is between 1.2 and 1.8. It can be used in toner applications.

Pyrogenically produced silica

Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 90&#xb1;15 m/g, wherein the aggregates display an average surface area of 10000 to 20000 nm, an average equivalent circle diameter (ECD) of 90 to 130 nm and an average circumference of 1000 to 1400 nm. It is produced by a pyrogenic process in which silicon tetrachloride and a second silicon component comprising HSiCl, HSiCl, HSiCl, CHSiCl, (CH)SiCl, (CH)SiCl and/or (n-CH)SiClare mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1810 to 1890&#xb0; C. is obtained. Dispersion containing the pyrogenically produced silicon dioxide powder.

Pyrogenically produced silicon dioxide powder and dispersion thereof

The invention relates to spherical colored pigments having an average particle diameter of less than 10 .mu.m on the basis of an oxide, a mixed oxide or a silicate. The pigments are obtainable by means of spray-pyrolysis technology: a solution containing oxide-forming or silicate-forming metal compounds is converted into an aerosol and the latter is fed, preferably after predrying, to a pyrolysis reactor; the pigment is separated from the pyrolysis gas. The colored pigments according to the invention are suitable for the production of ceramic decorations and for the coloring of plastics, synthetic foils, fibers and also lacquers. By reason of the spherical shape, unusual technical application properties are achieved.

Spherical color pigments, process for their production and use thereof

The invention relates to pigments consisting of substantially spherical particles with a mean particle diameter of less than 10 .mu.m, on the basis of an oxidic or silicate substrate material with noble metal distributed extremely finely on and/or in the particles. Preferred pigments are purple-colored and are based on an oxide from the series SiO.sub.2, SnO.sub.2 and ZrO.sub.2 and gold as noble metal. The pigments are suitable for the production of ceramic decorations and for the dyeing of plastics, synthetic films and fibers as well as lacquers. Exceptional application properties are obtained by virtue of the spherical shape. The pigments are obtainable by a spray-pyrolysis process in which an aerosol consisting of a solution of at least one noble metal compound and an oxide- or silicate-forming precursor is subjected to pyrolysis; the pigment is separated from the pyrolysis gas.

Spherical pigments, process for producing them and use thereof

Silica with the following physico-chemical properties:

Silanized silica

In order to produce precious metal powders of uniform particle size and low BET specific surface, appropriate aerosols are introduced into a flame reactor, whereby the aerosols are first freed of solvent as completely as possible by a thermal treatment.

Process for producing precious metal powders

A process for the production of 2,2'-bis(4-hydroxyphenyl)propanes by reacting the corresponding phenols and carbonyl compounds in the presence of organopolysiloxanes containing sulphonate and mercapto groups and acting as a catalyst, consisting of units of the formula

Production of 2,2'-bis (4-hydroxyphenyl) propanes in the presence of

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Bruchkoebel, Germany

Hauke Jacobsen