Process for producing polyethylene terephthalate
CA 2190274 C · Owner: Mitsui Chemicals, Inc. · Inventors: Tanaka, Yasuhiro; Miura, Kimiyoshi; Koreishi, Hiroshi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for producing a polyethylene terephthalate in which the amount of the oligomers such as cyclic trimer etc. is lower and which causes metal mold staining to occur difficultly. The process comprises an esterification stage in which dicarboxylic acids including mainly terephthalic acid or esterforming derivatives of such acids are esterified with glycols including mainly ethylene glycol or with ester-forming derivatives of such glycols; a liquid phase polycondensation stage in which the esterified product obtained in the esterification stage is subjected to a polycondensation in a liquid phase containing a polycondensation catalyst and having a content of an alkaline solubilizing …
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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 April 5, 1996 and granted July 2, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 5, 2016.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 5, 2018.
- 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
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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.