Partially hydrophobic precipitated silicas
CA 2201186 C · Owner: Meier, Karl · Inventors: Oelmuller, Rolf; Meier, Karl; Lux, Heinz-Gunter
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Partially hydrophobic precipitated silica with a methanol crosslinking potential of 10-49% is new. When anhydrous the silica has a DBP absorption > 250 g/100 g. The average particle size is 1-12 µm and the silica has a carbon content of 0.3-1.85 %, and when dried, it loses 2.6-10 % of its weight. It has a pH of 5.5-10. The silica is prepared by mixing a silica suspension (which has been prepared using known methods) with a material that gives the silica hydrophobic properties. The mixing takes place for a very short time at conditions of low pH and high shear. The resulting suspension is filtered and washed in salt-free conditions, and the filter cake is dried thermally treated, and …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 27, 1997 and granted October 10, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 27, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 27, 2019.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.