Evonik Degussa Gmbh

Degussa Gmbh

Rene Allerdisse

Karl Meier

Christian Panz

Helga Obladen

Mario Scholz

Markus Ruf

Michael Kempf

Dieter Kuhn

Roland Bergmann

Mario Loebbus

Anja Lukas

Aziz El Moussaoui

A precipitated silica having an SiOHabsorbance ratio of greater than or equal to 1.5, a silanol group density of 1 to 3.0 SiOH/nm, a modified tapped density of 1 to 50 g/l, and a pH of 3-5, when measured as a aqueous suspension of 5.00 g of the precipitated silica in 100 ml. of deionized water allows preparation of storage-stable RTV-1 silicone rubber formulations without stabilizer. A process for preparing the precipitated silica and its use in thickening sealants is provided.

Precipitated silicas for storage-stable RTV-1 silicone rubber formulations without stabilizer

Hydrophilic precipitated silicas which combine a particularly low initial moisture content with low moisture absorption over time, a low tapped density and a low silanol group density, have the following physicochemical parameters: equilibrium moisture content (at 70% relative humidity/20&#xb0; C.) of 0.5%-5.0% by weight, based on the weight of the hydrophilic precipitated silica, BET surface area of 50-250 m/g, CTAB surface area of 50-250 m/g, and DBP (anhydrous) of 200-350 g/100 g.

Hydrophilic silica for sealants

A hydrophobic precipitated silica having a BET of less than 110 m/g, a CTAB of less than 150 m/g, a BET/CTAB ratio of less than 3, a carbon content of greater than 3.1%, a pH of 9.7 to 10.5, a DBP of less than 230 g/(100 g), and a methanol wettability of more than 50%. The hydrophobic precipitated silica is used in compositions including defoamers, silicone rubber and HTV crosslinkable silicone rubber compositions. The hydrophobic precipitated silica is also useful as a flow assistant and carrier or anti-blocking agent.

Hydrophobic precipitated silica for defoamer formulations

Precipitated silicas with a high pH and their use in applications as defoamers having optimum silanol group density and a process for preparing precipitated silicas and to their use, particularly in defoamer formulations.

Hydrophilic precipitated silica for defoamer formulations

Precipitated silicas having an SiOHabsorbance ratio of greater than or equal to 1, may be used as reinforcers and thickeners for sealants.

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Bornheim, Germany

Rene Allerdisse