Improvements in a method of reclaiming styrene and other products from polystyrene based materials
CA 2303082 C · Owner: Ponsford, Thomas E. · Inventors: Ponsford, Henry T.; Ponsford, Thomas E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method of reclaiming styrene from polystyrene-containing materials wherein a solution of polystyrene from such materials in a solvent is heated in distillation equipment to depolymerize the polystyrene and produce a styrene fraction and a heavier fraction, the styrene fraction being separated from the heavier fraction. Prior to heating, an inert gas is used to purge the distillation equipment of oxygen. The method preferably is carried out at the lowest temperature which will achieve the desired rate of depolymerization.
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 10, 1998 and granted November 18, 2003. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 10, 2018.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 10, 2020.
- 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.