C - Chemistry – Metallurgy – 09 – B
Patent
C - Chemistry, Metallurgy
09
B
8/26, 260/176.7,
C09B 29/32 (2006.01) C09B 29/01 (2006.01) C09B 41/00 (2006.01) C09B 67/14 (2006.01) C09B 67/54 (2006.01) D06P 1/04 (2006.01)
Patent
CA 1310634
Abstract Monoazo pigments, process for preparation and use thereof The invention relates to monoazo pigments prepared from di- or trichloroanilines as diazo components and CH-aci- dic coupling components of the acetoacetarylamide or naphthol series, these pigments only containing an extremely low level of polychlorinated biphenyls (PCBs) (at most 25 µg per g of pigment). The process for preparing the pigments takes the form of an azo coupling in an aqueous medium, wherein a) azo coupling is effected by adding the diazonium salt solution to a suspension or solution of the coupling component or by simultaneously metering the aqueous suspensions or solutions of the diazonium salt and of the coupling component into the reaction mixture, b) azo coupling is effected at a pH or uithin a pH range of less than pH 7 and b1) between pH 4 and 7 during and after azo coupling less than 0.05 mol-%, b2) at pH 2 to 4 during azo coupling less than 5 mol-%, and b3) at pH < 2 during azo coupling less than 25 mol-% of diazonium salt is detectable in the reaction mixture and in pH ranges b2) and b3) more than 0.05 mol-% of diazonium salt is not present for longer than a total of 8 hours, more than 5 mol-% diazonium salt is not pre- sent for longer than a total of 4 hours and more than 15 mol-% of diazonium salt is not present for longer than a total of 2 hours, the mol-%ages of diazonium salt each being based on the total number of moles of coup- ling component present in the reaction mixture and pig- ment already formed, c) azo coupling is effected at a temperature or tempera- tures of 0 to 50°C, preferably 20 to 40°C, d) azo coupling is effected in the absence of nitrite ions, and e) azo coupling is carried out in the absence or presence of coupling assistants or coupling accelerants. The monoazo pigments, like existing monoazo pigments of corresponding structures, are useful for coloring natural and synthetic materials.
584516
Clariant Produkte (deutschland) Gmbh
Fetherstonhaugh & Co.
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