Light weight polyester article
CA 2007073 C · Owner: Cheung, Tak Man · Inventors: Davis, Charles Leo; Cheung, Tak Man; Prince, Jack Edward
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
This invention relates to a process for making a lightweight article which comprises: (1) feeding a thermoplastic resin composition into an extruder wherein the thermoplastic resin composition is comprised of (a) from about 94 to about 99 weight percent polyethylene terephthalate, and (b) from about 1 to about 6 weight percent of at least one polyolefin; (2) mixing an inert gas into the thermoplastic resin composition in the extruder while the thermoplastic resin composition is in the molten state; (3) extruding the thermoplastic resin composition containing the inert gas through a sheet forming die to produce a substantially amorphous cellular sheet which contains a sufficient amount of …
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 3, 1990 and granted December 21, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 3, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 3, 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.