Degussa Aktiengesellschaft

Evonik Degussa Gmbh

Degussa Gmbh

Michael Kempf

Mario Scholz

Christian Panz

Karl Meier

Markus Ruf

Helga Obladen

Rene Allerdisse

Dieter Kuhn

Ralf Schmoll

Uwe Schachtely

Gottlieb-Georg Lindner

Aziz El Moussaoui

Kenichi Kawamoto

René Allerdisse

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

Provided is a hydrophilic precipitated silica which is well suited to use in silicone rubber formulations (RTV-1, RTV-2, HTV and LSR), particularly well suited to use in HTV silicone rubber formulations. It has a BET surface area of 185&#x2dc;260 m/g, a CTAB surface area of 100&#x2dc;160 m/g, a BET/CTAB ratio of 1.2&#x2dc;2.6, and a conductivity of &#x3c;250 &#x3bc;S/cm. Also provided are a process for producing the precipitated silica and the use of the precipitated silica for thickening and reinforcing silicone rubber formulations.

Hydrophilic silica as filler for silicone rubber formulations

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

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

Precipitated silicas having special surface properties

A room temperature crosslinking, one component (RTV 1C) silicone rubber formulation with hydrophobic, silica featuring extremely low water absorption, a high level of whiteness, and fine-tunable, storage-stable rheological properties with a high reinforcing action in the silicone rubber vulcanizate contains A) from 0.5 to 60% by weight of a hydrophobic silica having the following properties: a carbon content of &#x3e;3.1%; a methanol wettability of &#x3e;60%; a reflectance of &#x3e;94%; a BET/CTAB ratio of from &#x3e;1 to &#x3c;3; a DBP absorption of &#x3c;230 g/100 g; a BET surface area of from 50 to 110 m/g; a CTAB surface area of &#x3e;30 m/g; a water vapor absorption at 30&#xb0; C. at an ambient humidity of 30 of &#x3c;1.3; a water vapor absorption at 30&#xb0; C. at an ambient humidity of 70 of &#x3c;1.7; and B) 40-99.5% by weight of an organopolysiloxane of the formulaZSiR&#x2014;O&#x2014;[SiRO]&#x2014;SiR&#x2014;Z'wherein each R represents independently alkyl, acetoxy, oxime, alkoxy, amido, aryl or alkenyl radicals, each having from 1 to 50 carbon atoms, each unsubstituted or substituted identically or differently by O, S, F, Cl, Br or I; or R represents independently polystyrene, polyvinyl acetate, polyacrylate, polymethacrylate, or polyacrylonitrile radicals, each having 50-10 000 repeating units; wherein each Z represents independently OH, Cl, Br, acetoxy, amino, amido, amineoxy, oxime, alkoxy, alkenyloxy, acyloxy or phosphate radicals, wherein said acetoxy, amino, amido, amineoxy, oxime, alkoxy, alkenyloxy and acyloxy radicals each have up to 20 carbon atoms; wherein each Z&#x2032; represents independently oxime, alkoxy, amido or acetoxy radicals; wherein n is 1-3; and wherein x is 100-15 000.

Room temperature crosslinking, one component silicone rubber formulation with hydrophobic silica

The present invention provides a hydrophobic precipitated silica having the following properties: The present invention also provides methods for making and using the hydrophobic precipitated silica and articles and compositions which include the same.

High-whiteness, non-heat-treated hydrophobic precipitated silica

The invention relates to silicone rubber formulations comprising organopolysiloxanes and hydrophobicized silicas, which possess an extremely high level of whiteness.

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Rodenbach, Germany

Michael Kempf