Process for producing high purity alkaline or alkaline earth metal terephthalate or terephthalic acid from polyol polyterephthalate, especially from ethylene glycol polyterephthalate wastes

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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 January 30, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended January 30, 2012.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 30, 2014.
• We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.