STUDY OF THE INFLUENCE OF THE CHEMICAL STRUCTURE OF ACID DYES ON THE LIGHTFASTNESS OF COLOURS

Abstract

The  purpose  of  the  work  is  to  determine  the  dependence  of  the  lightfastness  of  colours obtained on wool fabric with acid dyes on their chemical structure, namely, the chemical class, the structure of chromophore and the number of sulfo groups. The  study  was  carried  out  using  seven  acid  dyes  with  a  different  structure  of  the chromophore  and  the  number  of  sulfo  groups  in  the  molecule.  All-wool  fabric  previously  prepared  by peroxide bleaching was subjected to dyeing. Dyeing of wool textile material was carried out in a method that was determined by the leveling power of each dye. The insolation of the dyed samples was carried out on a device with a mercury-tungsten lamp. The light fastness of the samples was evaluated according to BS 1006 UK/TN standard by determining color differences using a colorimeter. Findings. The article presents the results of a study of the effect of the structure of acid dyes on the
lightfastness  of  the  colours  obtained.  It  is  established  the  chemical  structure  of  chromophore  and  the required number of sulfo groups in the acid dye molecule to provide light resistant colors on wool fabric. It has been proven that the number of sulfo groups is decisive for acid dyes from the point of view of chemical
structure. It has also been established that azo dyes that have an oxy group at ortho-position to azo group form the light-resistant colours. Originality. The influence of the chemical structure of acid dye molecules — the chemical class of chromophore and the number of sulfo groups — on the lightfastness of the colours obtained on wool fabric has been studied. Practical value. The chemical structure of acid dyes, providing colours with high resistance to light exposure, was determined.