Method of producing colored precipitated calcium carbonate
CA 2034190 C · Owner: Oji Paper Co. Ltd. · Inventors: Yokoi, Akira; Ebinuma, Osamu; Sakaguchi, Takashi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A colored precipitated calcium carbonate having a strong color fastness in water is produced by preparing an aqueous slurry containing calcium hydroxide and a water-soluble dye, for example, a direct dye introducing a carbon dioxide-containing gas into the aqueous slurry, and collecting the resultant colored precipitated calcium carbonate from the aqueous slurry at a pH of 8.2 or more thereof.
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 January 15, 1991 and granted December 1, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 15, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 15, 2013.
- 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.