Novel trialcoxy-substitued metaphenylenediamines, process for their preparation, and use as coupling agents for the oxidative dyeing of keratinic fibers and specially human hair

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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 November 22, 1989. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 22, 2009.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 22, 2011.
• We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.