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US 8,007,751 B2Granted
Hydrophilic precipitated silica for defoamer formulations
AssigneeEvonik Degussa GmbH
InventorsChristian Panz, Rene Allerdisse, Helga Obladen, Mario Loebbus, Anja Lukas, Roland Bergmann, Karl Meier
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Abstract
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.
Claims31
A precipitated silica having
- BET
- 100-190 m2/g,
- Modified Sears number
- 8-20 ml/(5 g),
- Sears number/BET ratio
- <0.12 ml/(5 m2), and
- pH
- >8.
5 more elements
A process for preparing a precipitated silica, comprising:
- a) precipitating a silicate solution to form a precipitated silica,
- b) filtering the precipitated silicate solution to form a filtercake of the precipitated silica,
- c) liquefying the filtercake by adding water to form a suspension of the precipitated silica,
- d) drying the suspension,
- f) milling the precipitated silica,
- wherein the process further comprises
- e) alkalifying the precipitated silica by adding at least one basic agent thereto wherein the resulting precipitated silica has the following characteristics:
- BET 100-190 m2/g, Modified Sears number 8-20 ml/(5 g), Sears number/BET ratio<0.12 ml/(5 m2), and pH>8.
5 more elements
Dependencies are inferred from the claim text.