e., a space big enough for dye adsorption and diffusion into inner zones of a fibre. The presence of non-ionic tensides slightly slows down dye adsorption, proportionally to the concentration increase. Significant changes in the adsorption speed have been noticed when anionic tenside was used at the maximum concentration. Changes in acid dye adsorption speed on wool and polyamide caused by tenside addition into dyeing solution influence dye diffusion speed into the fibres interior, which has been confirmed by half-dyeing time values determination, and a relative diffusion coefficient determination.
Tenside addition into dyeing solution increases half-dyeing time several times in both fibres, and this increase is proportional to the tenside concentration. With the FN-10 concentration increase half- dyeing time for wool increases 1,4 to 2,3 times, and for PA6 1,4 to 2,4 times in comparison to the systems without additives, and this tenside can be said to almost identically influence the half- dyeing time increase in both fibres.
However, FN-20 addition at the concentration of 0,4 g/d 3 increases half-dyeing time for wool 2.4 times, and for polyamide 1.4 times. It means that the initial relation of half-dyeing time wool/ polyamide 10 is now increased to over 17, which additionally increases the difference in dyeing speed of these fibres and has a negative impact on even colouration of their mixtures. When anionic tenside is used for acid dye wool dyeing, a slight increase of half-dyeing time occurs, and at the concentration of 3 g/dm3 it is 1.3 times.
At the same time, in PA fibre, under the same conditions the half-dyeing time increase is 3.13 times, so the relation of half-dyeing times wool/polyamide is 4.2, which means that it is about 2.5 times less in comparison to the case without additives. These results suggest that for successful dyeing of wool/polyamide mixture anionic tenside is better than non-ionic one, but increased tenside concentration and proper regulation of other dyeing parameters should be borne in mind.
In systems with non-ionic tensides for wool fibre, relative diffusion coefficient values are decreased 3-4 times in comparison to the system with no additives, and when anionic tenside is used the decrease in D, is below 15 percent. This points out to the greater retarding power of non-ionic agents in comparison to anionic. On the other hand, in PA substrate, anionic tenside has greater retarding influence.
Changes in acid dye adsorption and diffusion speeds in wool and polyamide when non-ionic tensides are added are results of the changed state of acid dyes in aqueous solution. It has been confirmed that through the interaction between anionic dyes and non-ionic tensides, dye/ tenside associations of the limited stability can be created.
Decreased concentration of diffusely active (monomeric) form of acid dye and associations robustness slow down the adsorption on the fibre surface and diffusion into the fibre interior. In time (and with the increase in temperature) unstable associations were destroyed, and the equilibrium state moved in the direction of single ions formation that could penetrate into the fibre. In that way, dye ions were more slowly transferred onto the dyed material and distributed more evenly on its surface.
The way of action of Etopon LSP can be described as an action of a retarder locking protonised amino groups through which acid dye binds to polyamide and wool fibre with ionic bond. The type of tensides has an affinity for a dyed substrate, i.e., by ionic interaction; it can be fixed for active fibre centres in the same way as dye. Anionic tensides action mechanism is explained by the competition between dye and tenside in making a connection with the fibre.
Tenside molecules are more mobile and penetrate faster into the fibre, selectively taking first more accessible places, thus reducing differences in speed of adsorption and dye diffusion between more accessible places and less accessible ones, which improves the evenness of colouration. In the dyeing process, due to smaller affinity, anionic tenside ions got pushed out of the active places in the fibre and replaced with dye anionis. Through the ion exchange mechanism, anionic tenside slowed down dye adsorption and diffusion, thus producing even colouration.
Conclusion
In multiple-component ionic dyeing system amphoteric fibre/acid dye, addition of a new component increases the number of potential inter-actions, which is exhibited (shown) by the acid dye state change in a solution, i.e., by the change of substrate functional groups state. In a solution non-ionic tensides and acid dyes form associations dye/tenside the oversize of which impairs dye diffusion through the solution towards the fibre surface (dye adsorption), which subsequently slows down dye diffusion into fibre interior.
Factors that increase non-ionic tenside action are increasing concentration and increased number of etoxy groups in a tenside molecule. The addition of anionic tenside causes blocking of amino groups in places, also decreasing the speed of the examined system. On the basis of the obtained results, it can be concluded that non-ionic tensides are better for acid dye wool dyeing, while anionic tensides are preferable for polyamide and PA/wool mixtures dyeing.
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