Colouring agent
CA 2249710 A1 · Owner: Kaufmann, Rainer · Inventors: Kaufmann, Rainer
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention concerns a colouring agent which contains water and one or a plurality of water-soluble dyes with anionic groups which have a pKa value which is essentially not above A, combined with the precursor of a first auxiliary substance, the first auxiliary substance as such having the pKa value C and C being greater or smaller than A or equal to A. The invention further concerns a printing or writing process using a colouring agent of this type.
Read the whole patent
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 18, 1997. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended March 18, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 18, 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
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.