Process for producing maleic anhydride
CA 2008178 C · Owner: Mitsui Chemicals, Incorporated · Inventors: Okawa, Takasi; Sugawara, Harusige
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Crude maleic anhydride produced by catalytic oxidation is distilled and then n-propyl gallate cuprous chloride and, zinc chloride are added thereto. Alternatively crude maleic anhydride is distilled in the presence of tridecyl phosphite. Further these, procedures can be used in combination. Thermal stability and color stability of the maleic anhydride is improved. - 20 -
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 19, 1990 and granted February 8, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 19, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 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.