Preparation of linea, unsubstituted quinacridone pigments of the .beta.-phase
CA 2136598 A1 · Owner: Clariant Gmbh · Inventors: Dietz, Erwin; Urban, Manfred
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Preparation of linear, unsubstituted quinacridone pigments of the .beta.-phase, linear, unsubstituted quinacridone pigments of the .beta.-phase can be produced in an environmentally friendly manner by, a) cyclizing 2,5-dianilinoterephthalic acid in polyphosphoric acid or a polyphosphoric ester to the quinacridone, b) then hydrolyzing the quinacridone with water at a temperature of at least 40°C, preferably at from 60 to 100°C, to obtain a finely divided quinacridone pigment crude which is predominantly in the .alpha.-phase c) then optionally wet grinding the finely divided quinacridone pigment crude from b) (pre-pigment) and, d) then heating the crude pigment from b) or the prepigment from …
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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 24, 1994. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 24, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 24, 2016.
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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.