Degussa Aktiengesellschaft

Deutsche Gold- Und Silber-scheideanstalt Vormals Roessler

Evonik Degussa Gmbh

Degussa - Huls Ag

Degussa Aktiengsellschaft

Robert Kuhlmann

Heinz Esch

Peter Nauroth

Ralf Rausch

Gunter Turk

Rudolf Bode

Arthur Reisert

Karl Meier

Udo Goerl

Mustafa Siray

Claus-Peter Drexel

Udo Gorl

Gottlieb-Georg Lindner

Udo Görl

Juergen Schubert

Harald Buhler

Adam Becker

Andrea Hunsche

Helmut Reinhardt

Hans-Dieter Christian

Karin Otto

Hans Dieter Christian

Gunther Turk

Edith Eisenmenger

Mattias Neumueller

Walter Meon

Guenter Tuerk

Matthias Neum&uuml;ller

Otto Kuhnert

Klaus-Peter Thomas

Buhler, Harald

Jürgen Schubert

Precipitated silicas and wax-coated precipitated silicas, their preparation, and their use as matting agents in inks and paints, the precipitated silicas characterized by: 

Efficient matting agents based on precipitated silicas

Precipitated silica or silicates, obtainable by acid precipitation of aqueous silicate solutions while maintaining a constant alkali number of at least 1.

Silica by precipitation at constant alkali number, and its use

A precipitated silica having the following physico-chemical characteristics: 

High-structure precipitated silicas

Silica and silicate by precipitation at constant alkali number, and its use

Rubber compositions comprising a precipitated silica with the following physico-chemical properties: 

Precipitated silicas

A precipitated silica with the following physicochemical properties: is produced by reacting alkali silicate with mineral acids at temperatures of 60&#xb0; C. to 95&#xb0; C. while maintaining a pH of 7.5 to 10.5 and continuously stirring, continuing the reaction to a solids concentration in the precipitation suspension of 90 g/l to 120 g/l, adjusting the pH value to a value of less than or equal to 5, filtering out, washing, drying and optionally grinding or granulating the precipitated silica. The precipitated silica is used as a filler in vulcanizable rubber compounds and vulcanizates.

A precipitated silica which contains an active substance with a characteristic, delayed release of active substance is prepared by adding the active substance during preparation of the precipitated silica. The precipitated silica containing the active substance may be added to oral hygiene agents such as toothpastes, topical fluoride preparations, dental materials or medicinal chewing gums.

Precipitated silicas which contain an active substance

A precipitated silica with the following physicochemical properties:

Precipitated silica with a sodium sulphate content of 4 to 18 wt. %, particularly with the physical-chemical data:

Precipitated silica

Precipitated silicas, characterized in that they have a CTAB surface area (in accordance with ASTM D 3765-92) of 200 to 400 m.sup.2 /g, a DBP index (in accordance with ASTM D 2414) between 230 and 380 ml/100 g as powder and 180-250 g/100 g as granulate, a silanol group density (V.sub.2 -NaOH consumption) of 20 to 30 ml and the following macropore size distribution which is typical of the surface area range involved, determined by means of Hg porosimetry (DIN 66 133) for specific pore size intervals (incremental mode of application):

Precipitated silicas, a process for their preparation and their use in

Precipitated silica which has a BET surface area of 10-130 m.sup.2 /g, a CTAB surface area of 10-70 m.sup.2 /g , an average particle diameter of 5-20 .mu.m, a Cu abrasion value in a 10% glycerol dispersion of 4-50 mg and thickening behavior in a CMC solution (20% dispersion) of 300-3500 mPa.multidot.s, is produced by simultaneously adding alkali silicate (weight modulus SiO.sub.2 :alkali oxide=2.5-3.9:1) and a mineral acid to an initial amount of water which has been adjusted to a pH value of 7.0 to 9.9 or 10.0 to 10.7 by the addition of water glass, holding the pH value constant between 7.0 and 9.9 or 10.0 to 10.7 during addition, wherein the initial precipitation temperature is 50.degree.-90.degree. C. and an increase in viscosity occurs after at most 25% of the duration of precipitation, adjusting the pH value to .ltoreq.6, preferably 3.5, once a silica content of greater than 120 g/l or greater than 150 g/l, preferably .gtoreq.160 g/l to 240 g/l, has been reached, separating the solid by filtration, washing, drying and grinding it. The precipitated silica may be used as an abrasive and/or thickening component in toothpastes.

Process for the production of precipitated silica

Process for the production of cleansing, polishing and thickening silica for use in toothpastes, which is characterized in that using the conventional precipitation processes, silica suspensions are obtained of various particles sizes and particle densities and are mixed thoroughly together until the mixture is homogenous in the suspension phase and the resulting suspension mixture is treated in the conventional manner by filtering, drying and comminuting.

Precipitated silicas and process for their production and use

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Robert Kuhlmann