Metal complex dyes and pigments

A more comprehensive historical account of metal complex dyes and pigments can be found in ref. 7. 

Metal complex dyes and pigments perform key functions in both the image generation step and the toner development step. It is the metal complex pigment that produces the positive hole in the organic photoconductor. 

Unfortunately, there are some inconsistencies between this eco-label for textiles and the eco-label for bed mattresses, which was enacted in October 19981 ° and excludes the use of metal-complexed dyes or pigments based on chromium, copper, nickel and lead. It is hoped that this restriction will be removed by the next revision. 

Dyes and Pigments. Several thousand metric tons of metallated or metal coordinated phthalocyanine dyes (10) are sold annually in the United States. The partially oxidized metallated phthalocyanine dyes are good conductors and are called molecular metals (see Semiconductors Phthalocyanine compounds Colorants forplastics). Azo dyes (qv) are also often metallated. The basic unit for a 2,2 -azobisphenol dye is shown as stmcture (11). Sulfonic acid groups are used to provide solubiHty, and a wide variety of other substituents influence color and stabiHty. Such complexes have also found appHcations as analytical indicators, pigments (qv), and paint additives. 

Azo dyes and azo pigments are the most important class of both non-metallized and metallized colorants. Therefore, this section is devoted entirely to metal complex azo dyes and pigments. 

The use of metal complex dyes for textile and related applications has already been treated comprehensively.7 There have been few major advances since that review. Therefore, this section focuses on typical commercial metal complex dyes, key structure-property relationships, and some recent studies on metal complex azo pigments. 

Charge control agents (CCAs) can be either colored or colorless and are mainly metal complex dyes rather than pigments. Colored CCAs are more effective than colorless CCAs but, because of their color, are restricted to black toners. Colorless CCAs are needed for yellow, magenta, and cyan toners. 

The yellow ink jet dyes (and pigments) are metal-free azo dyes, such as Cl Direct Yellow 132 and Cl Acid Yellow 23 (Tartrazine).48,49 Most of the magentas are azo dyes derived from H-acid (l-amino-8-naphthol-3,6-disulfonic acid), such as (62), and xanthenes, such as Cl Acid Red 52 and Cl Acid Red 289.48,49 Where high lightfastness is a requirement, a copper complex azo dye, Cl Reactive Red 23 (63), is used. However, such dyes are dull (see Section 9.12.3.2). Nickel complex PAQ dyes, such as (22), are claimed to be brighter and to have similar high lightfastness... 

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