A method of de-inking waste paper materials
CA 2048618 C · Owner: Woodfree Limited · Inventors: Blum, Stanley
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method of de-inking waste paper materials consists in pulping the paper material in a hydropulper (I) to form a fibrous stack, and adding a substance in the form of a mixture of phosphated and carbonated sodium salts to the fibrous stock to disperse ink particles from the stock, The stock and dispersed ink particles pass through washing stages (4), (7) and (8) in a centrifu-, gal cleaner (3), in order to remove the ink particles from the fibrous stock.
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 14, 1990 and granted April 23, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 14, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 14, 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.