Diarylide yellow pigments
A diarylide yellow pigment formed by a coupling reaction of a benzidine and a mixture comprising 4-chloro-2,5-dimethoxy-acetoacetanilide and 2,4-dimethyl-acetoacetanilide. The diarylide yellow pigment has a desirable reddish shade than C.I. Pigment Yellow 83, exists in a solid solution, and contains fewer aromatic amine impurities.
1. A diarylide yellow pigment produced from a process comprising: coupling tetrazotized 3,3′-dichlorobenzidine and a mixture comprising 25-90% by weight of 4-chloro-2,5-dimethoxy-acetoacetanilide and 75-10% by weight of 2,4-dimethyl-acetoacetanilide; where the resulting diarylide yellow pigment is a solid solution.
2. The diarylide yellow pigment of claim 1 , where the pigment has a redder color than C.I. Pigment Yellow 83.
3. The diarylide yellow pigment of claim 1 , where the pigment has X-ray diffraction pattern Bragg angles at 6.7°, 10.0°, 25.4°, 28.5° and 30.5° (approximate 2Θ values, Cu K α ) or an absence of peaks at 7.5°, 11.0° and 26.9° (approximate 2Θ values).
4. The diarylide yellow pigment of claim 1 , where the mixture comprises from about 30% to about 70% by weight of 4-chloro-2,5-dimethoxy-acetoacetanilide and from about 70% to about 30% by weight of 2,4-dimethyl-acetoacetanilide.
5. The diarylide yellow pigment of claim 4 , where the pigment has an X-ray diffraction pattern Bragg angles at 6.7°, 9.7°, 10.5°, 25.2° and 26.9° (approximate 2Θ values, Cu K α ) or an absence of peaks at 11.0° (approximate 2Θ values).
6. The diarylide yellow pigment of claim 5 , where the mixture comprises from about 35 to about 65% by weight of 4-chloro-2,5-dimethoxy-acetoacetanilide and from about 65% to about 35% by weight of 2,4-dimethyl-acetoacetanilide.
7. The diarylide yellow pigment of claim 1 comprising less than 500 ppm of an aromatic amine.
8. The diarylide yellow pigment of claim 1 comprising no aromatic amine.
9. A substrate colored with the pigment from claim 1 .
10. Printing inks colored with the pigment from claim 1 .
11. Plastics colored with the pigment from claim 1 .
12. Paints colored with the pigment from claim 1 .
13. Polymeric materials colored with the pigment from claim 1 .