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US 4,648,907 AGranted
High color strength diarylide yellow pigment compositions
AssigneeBASF SE
InventorsByron G. Hays, Robert J. Stanaback
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Abstract
Improved diarylide yellow pigment compositions having high color strength. The compositions are manufactured by modifying tetrazotized 3,3'-dichlorobenzidine with a solution of about 3 to about 5 mole percent of a first acetoacetarylide, followed by coupling into a second acetoacetarylide such as acetoacetanilide.
Claims6
A method of manufacturing diarylide yellow pigments comprising tetrazotizing 3,3'-dichlorobenzidine, then coupling the tetrazonium salt with an acetoacetarylide, and then filtering and washing the resulting pigment, wherein the improvement comprises:
- modifying the tetrazotized 3,3'-dichlorobenzidine by reacting with about 3 mole % to about 5 mole % of an acetic acid solution of a first acetoacetarylide;
- and
- then coupling the modified 3,3'-dichlorobenzidine tetrazonium salt into a slurry of a second acetoacetarylide,
- thereby producing diarylide yellow pigment compositions having increased color strength over diarylide yellow compositions produced by conventional methods.
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Dependencies are inferred from the claim text.