Finishes to improve colour fastness

Chemical finishing is defined as and includes all processes after coloration that provide better properties and that enable the qualified use of the treated textiles. But dyers and printers are often responsible for finishes that improve colour fastness. Nowadays coloured textiles have to fulfil many requirements. Therefore improvement in the colour fastness is a type of chemical finishing of particular practical interest and importance. 

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Almost no effect Soil-release finishes Antistatics, if not softening and smoothing Finishes to improve colour fastness Finishes for protection from UV or insects Antimicrobial finishes... 

The earliest polymeric cationic aftertreatments stemmed from the development of crease-resist finishes for cellulosic fibres. One such, promoted specifically for its colour fastness improvements when applied as an aftertreatment to direct dyeings, was a condensation product of formaldehyde with dicyandiamide (Scheme 10.82). Many similar compounds followed, such as condensation products of formaldehyde with melamine (10.212), polyethylene imine) with cyanuric chloride (10.213) and alkyl chlorides with polyethylene imine) (10.214 R = alkyl). 

Properties provided by these finishes are mostly improved wet fastness, for example washing, water, perspiration and ironing fastness, then better light fastness and only to a small extent improved crocking and rubbing fastness. For other kinds of colour fastness, for example dry ironing, chlorine, peroxide and carbonisation, there are no known possibilities for improvement by an after treatment. The market importance of these finishes is based on customer preferences and economic production demands. For abetter understanding, each of these three quite different fastness improvements will be dealt with separately. 

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