Surface-modified silica gels
AssigneeDegussa AG
InventorsUlrich Brinkmann, Christian Götz, Hans-Dieter Christian
Life of this patent
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Abstract
The invention relates to surface-modified silica gels, to a process for preparing them, and to their use as matting agents in coating materials. As a result of the nature of the surface modification, the viscosity of 2-component coating materials is increased only slightly, or not at all, after the matting agent has been added.
Claims47
A surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5, wherein the surface of the silica gel is coated with a polyorganosiloxane having the following general structure:
- with the proviso that a, b, c and d are each not 0 simultaneously.
A surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5, wherein the surface of the silica gel is coated with a polyorganosiloxane having the following general structure:
- and the sum of the units a=0 to 100, the sum of the units b=0 to 15, the ratio of methyl to alkoxy radicals R1 being less than 50:1, and b>1 if a=0 and a>5 if b=0.
A process for preparing a surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5,
- which comprises modifying the surface of a silica gel with a polyorganosiloxane having the following general structure:
- with the proviso that a, b, c and d are each not 0 simultaneously.
A process for preparing a surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5,
- which comprises modifying the surface of a silica gel with a polyorganosiloxane having the following general structure:
- and the sum of the units a=0 to 100, the sum of the units b=0 to 15, the ratio of methyl to alkoxy radicals R1 being less than 50:1, and b>1 if a=0 and a>5 if b=0.
Dependencies are inferred from the claim text.