Disperse dyes fastness

The sulfur dyes are widely used in piece dyeing of traditionally woven cotton goods such as drill and corduroy fabrics (see Textiles). The ceUulosic portion of polyester—cotton and polyester—viscose blends is dyed with sulfur dyes. Their fastness matches that of the disperse dyes on the polyester portion, especiaUy when it is taken into account that these fabrics are generaUy given a resin finish. 

Dyestuffs. The use of thiophene-based dyestuffs has been largely the result of the access of 2-amino-3-substituted thiophenes via new cycHzation chemistry techniques (61). Intermediates of type (8) are available from development of this work. Such intermediates act as the azo-component and, when coupled with pyrazolones, aminopyrazoles, phenols, 2,6-dihydropyridines, etc, have produced numerous monoazo disperse dyes. These dyes impart yeUow—green, red—green, or violet—green colorations to synthetic fibers, with exceUent fastness to light as weU as to wet- and dry-heat treatments (62-64). 

Application Techniques, Structural Variations, and Fastness Properties. When appHed to polyester fiber, many of the disperse dyes originally developed for ceUulose acetate were found to be deficient in Hghtfastness, build-up properties, and especially fastness to the high temperatures employed in the newer dyeing and finishing, printing, and Thermosol (dry heat) processes. 

Deep shades and full fastness properties on polyester can be achieved using disperse dyes and carriers, or temperatures over 100°C with or without carriers. 

In the 1950s acid dyes were successively developed to dye nylon carpet with excellent fastness and uniform leveling. Development of polyacrylonitrile fiber stimulated the invention of anthraquinone basic dyes, modified disperse dyes in which quaternary ammonium groups are introduced. 

Nylon Blends. Differential dyeiag nylon types and cationic dyeable nylon blends are used primarily ia the carpet iadustry. The selection of cationic dyes for nylon is rather limited most products have very poor fastness to light. These blends are dyed ia a one-bath procedure at 95—100°C. Selected acid dyes are used for differential dyeiag. Disperse dyes will dye all different types ia the same depth. 

On polyamide, disperse dyes have generally low wetfastness properties, making them unsuitable for ptinted textiles that require even moderate wash or perspiration fastness. 

As already mentioned, some lubricants can be difficult to remove by washing and surfactants are often added to overcome this problem [463]. Lubricants can impair fastness properties, particularly those of disperse dyes. They may influence the uptake of dyes either positively or negatively, although seldom seriously except where it results in unlevelness. For example, knitting oils can increase the yield of relatively oleophilic reactive dyes on cotton and yet with highly hydrophilic types they may cause dye-resist effects [467]. 

For the same disperse dyes on various hydrophobic fibres the highest light fastness is... 

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