Colorants in Ink Jet Printers

The ink jet printing of coloured images is a subtractive process and requires a YMC trichromat as in colour photography. Some of the properties required in the dyes are listed below. 

A wide range of dyes have been evaluated but only a few of existing dye ranges have found commercial use, the best are listed in Table 2.14. 

Many of these dyes suffer from poor wet fastness and light fastness properties, especially in the magenta shade area, or they are not the right shade for the desired trichromat. 

Much research work has been done and continues to be done on the development of new dyes for this outlet. For instance, Avecia have a range of yellow magenta and cyan dyes, based on the ammonium salt principle above, which do show improved wet fastness properties. An alternative approach adopted by workers at Ilford, based on their experience in colour photography, involves the molecular tailoring and formulation of dyes which aggregate and hence have light fasmess properties nearer to pigments (Archiva Inks). 

The current position in the dye-pigment debate is that, where light fasmess is not a problem, dyes take precedence because of brighter shade, better colour gamut and inherently more stable inks. Commercial printers prefer to use pigments as they have 

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