Process for the preparation of bis-carbonates from diphenols and polyoxyalkylene glycols lengthened by carbonate groups and their application in the preparation of macromolecular thermoplastic polycarbonate polyether block copolymers.

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Listed from its EPO record in Patent Yard's archive of European patents past their term. Its claims, description and drawings are in the EPO PDF and on Google Patents, and the Claude kit works from them.

Why it's free to use

• Filed June 6, 1978 and granted August 6, 1980. A European patent lasts at most 20 years from filing, so its term ended June 6, 1998.
• A supplementary protection certificate, which can extend a medicine or crop-protection patent, adds at most five and a half years, so even that would have ended by December 6, 2003.
• We check European rights only. A US or other national patent in its family could still be in force: check its family on Espacenet or Google Patents.