Process for the whitening of paper coating compositions and also whitener preparations for this process
CA 2021559 A1 · Owner: Bayer Aktiengesellschaft · Inventors: Hunke, Bernhard; Konig, Joachim; SCHUßLER, ULRICH
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Process for the whitening of paper coating compositions and also whitener preparations for this Process A b s t r a c t, Combinations of cellulose powder (average particle size below 50 µm) and anionic cellulose optical brighteners and also optionally coating pigments are eminently suitable for the whitening of paper coating compositions. Besides an excellent optical brightening effect, the resulting papers have an improved light fastness.
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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 July 19, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended July 19, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 19, 2012.
- 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
Timeline From CIPO dates
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.