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Hydrophobic precipitated silica for defoamer formulations

Inactive Publication Date: 2005-09-01
EVONIK OPERATIONS GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006] Accordingly, it is an object of the present invention to provide precipitated silicas having enhanced performance properties, particularly in defoamer formulations. The invention also provides a process by which the precipitated silicas of the invention can be prepared.
[0023] It was also found that hydrophobic precipitated silicas with relatively long polysiloxane chains on the surfaces exhibit particularly good defoamer performance. A measure which can be used to value this property is the ratio of BET to CTAB surface.
[0029] They are therefore outstandingly suitable as a defoamer component in defoamer formulations. In particular they provide a short knockdown time, virtually complete knockdown and long hold down. It is possible to incorporate the precipitated silicas of the invention into defoamer formulations with particular ease and homogeneity.

Problems solved by technology

Prior art precipitated silicas have unsatisfactory values for some if not all of the stated parameters.

Method used

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  • Hydrophobic precipitated silica for defoamer formulations
  • Hydrophobic precipitated silica for defoamer formulations
  • Hydrophobic precipitated silica for defoamer formulations

Examples

Experimental program
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Effect test

example 1

[0227] 63 l of deionized water were charged to an 80 l precipitating vessel and heated to 88° C. Added to this initial charge were waterglass (modulus=3.5; density=1.343 g / ml) at a metering rate of 6.5 l / h and sulfuric acid (concentration=7.167 mol / l) with a metering rate of 1.56 l / h, metering taking place so as to maintain a pH of 8.0-8.5 (measured on a sample with a temperature of 60° C.). After 105 minutes the metered feeds are ended. Subsequently the precipitation suspension was acidified to a pH of 3.5 with sulfuric acid (concentration=7.167 mol / l), with the same metering rate as before, and the suspension was then aftertreated in a drying oven at 50° C. for a period of 12 h.

[0228] The suspension was filtered and washed sufficiently with deionized water. The resulting solids content of the filtercake is 15-17%.

[0229] With deionized water introduced initially, and with gentle stirring, the filtercake is liquefied so as to give a silica suspension with a solids content of 6-11%...

example 2

[0272] Both a mineral oil dispersion and a silicone oil dispersion were produced from the product from example 1 and were investigated for defoaming action.

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Abstract

Hydrophobic precipitated silicas with a high pH and low silanol group density, a process for preparing them and their use, particularly in deformer formulations.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to hydrophobic precipitated silicas of high pH and low silanol group density, to a process for preparing them and to their use, such as in defoamers, fillers or carriers. [0003] 2. Description of the Related Art [0004] Hydrophobic precipitated silicas and processes for preparing them are known. Hydrophobicization is accomplished generally by populating the surface of a hydrophilic precipitated silica with suitable organic compounds. Examples of such hydrophobic or partly hydrophobic precipitated silicas are disclosed in patents EP 0 798 348, U.S. Pat. No. 4,377,493 and EP 1 281 735, EP 1 281 733 and EP 1 281 735 disclose hydrophobic precipitated silicas with a pH of 5-9, while WO 2003014020 discloses those having a pH of more than 9.5. [0005] The use of hydrophilic and hydrophobic precipitated silicas in defoamer formulations is likewise known (Pigments Technical Bulletin 42, DEGUSSA, 0...

Claims

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Application Information

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IPC IPC(8): B01D19/04B01J32/00C01B33/18C01B33/193C08K3/34C08L83/04C09C1/30
CPCB01D19/0409C01B33/18C01B33/193C01P2004/61C01P2006/11Y10T428/2995C01P2006/19C09C1/3018C09C1/3081C09C1/309C01P2006/12B60P1/28B60P1/045B60Y2200/14
Inventor PANZ, CHRISTIANALLERDISSE, RENEOBLADEN, HELGALOEBBUS, MARIOLUKAS, ANJABERGMANN, ROLANDMEIER, KARL
Owner EVONIK OPERATIONS GMBH
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