Bisazo pigments

Figure 5 Bisazo pigments used in dual-layer photoreceptors.

There are several reports on the effects of different substituents with a given parent and the importance of crystal modification. In a study by Hashimoto (1986), several bisazo pigments based on diaminofluorenone were synthesized and characterized. Table 1 shows the results for AZO-FO and related pigments used by Ricoh in Fig. 6. The transport layer contained the hydrazone CTM-2. 

Table 1 The Effects of X Substituents of the Anilide Functionality on the Absorption and Sensitivity of a Series of Dual Layer Photoreceptors Using a Diaminofluorenone bisazo Pigment in the Generation Layer. (After Hashimoto, 1986)...

Law, K. Y, Tarnawsky, J. I. W. and Popovic, Z. D. (1994). Azo pigments and their intermediates—a study of the structure-sensitivity relationship of photogenerating bisazo pigments in bilayer xerographic devices. J. Imag. Sci. Technol, 38, 118-24. [204]... 

Diarylide yellows are bisazo pigments derived from 3,3 -dichloroben-zidene (Fig. 7.7). They have high color strengths and a high chroma. They are of low cost and have reasonable heat and chemical resistance and improved bleed resistance when compared to the monoarylide yellows. However, they have poor light-fastness [9]. 

Scheme 5. Molecular structures and ionization potentials of the bisazo pigments and hole transport materials used in [34b], (Reprinted with permission from Ref. [34b].)...

Umeda, M. and Yokoyama, M. (1997) Carrier photogeneration processes in layered organic systems incorporating bisazo pigment xerographic and electroabsorption study. J. Appl. Phys., 81, 6179. 

Figure 10.14. Solid state absorption spectra of bisazo pigments (a) Vila, (b) Vllb, (c) VIIc, (d) Vllj, (e) VIII and (f) Vllm. (Reproduced from ref. 184, Copyright 1993, The Society for Imaging Science and Technology.)...

Thus photoconductive bisazo pigments from 2-hydroxy-3-naphthanilide couplers are only sensitive from 450 to 650 nm and are primarily used in copiers. 

Figure 10.15. Spectral response curve and absorption spectrum of bisazo pigment Vlln in a bilayer photoreceptor device. (Reproduced from ref 4, Copyright 1993, The American Chemical Society.)...

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