Process for the preparation of chemical pulp
CA 2068642 A1 · Owner: Mita, Akio · Inventors: Mita, Akio
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed is a process for the continuous massproduction of chemical pulp from cellulose raw materials without adversely affecting the global environment and natural resources to a substantially hazardous extent. The process involves the step of digesting the cellulose raw materials at 130° to 200° C with a cooking liquor comprising an alkali solution, hydrogen peroxide a chelating agent, an anthraquinone and water the step, of obtaining pulp waste liquor and unbleached pulp by subjecting the cellulose raw materials to solid-liquid separation, the step of concentrating and burning the pulp waste liquor to obtain an alkali metal carbonate the step of adding, if necessary, calcium oxide to …
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 September 17, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended September 17, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 17, 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.