Effect Of Surfactants On The Hydrolysis Of Reactive Dyes And Silicone Deepening During Domestic Washing

Laundering textiles is necessary in order to remove stains and odors which accumulated during daily use. However, textiles laundered with synthetic detergents may undergo physical and chemical damages during the multiple laundering process. The textiles tend to become harsher and stiffer and the damages would also result in color fading, fabric wear and other undesirable consumer issues. The introduction of deepening agent could effectively achieve color protection during the washing process.On the other hand, improving the rate of dye fixation could reduce the amount of unfixed dyes in the dyeing process, and could help to reduce color fading of fabrics during domestic washing.As is known to all, surfactant is wildly used in dyeing industry and detergent products. From the viewpoint of color protection, effects of surfactant on thehydrolysis of reactive dye and deepeningof silicone oil were studied.In this paper, vinyl sulfone reactive dyes KN-R is used as model dye and the interaction between surfactant and dye is investigated using UV-Vis method. Then high-performance liquid chromatography(HPLC) is used to study the hydrolysis of KN-R in the surfactant solutions. Two commonly used surfactants are used here, one is anionic surfactant sodium dodecyl benzene sulfonate(LAS) and the other is non-ionic surfactants fatty alcohol ethoxylates(AEO-9). Results showed that the hydrolysis reaction in water and surfactant system are all subject to pseudofirst-order reaction. And the hydrolysis rate constants are greatly influenced by surfactant concentration and temperature.When the concentration of surfactant is below the critical micelle concentration(CMC), surfactant serves as dispersing agent in the system, which can promote the hydrolysis of KN-R. And the hydrolysis rate constants were 3 times(LAS) and 3.5 times as in the water system.When the concentration of surfactant is above CMC, formed micelles could solubilize dye into the hydrophobic core, inhibit the hydrolysis of dye and the hydrolysis rate constants were smaller than that in the water system.On the other hand, silicone oil emulsions are used as deepening agents in the finishing period. Here we use amino silicone 8040 A as the deepening agent for domestic washing. Two black cotton fabrics dyed by reactive dye and sulfur dye are washed 15 times in washing machine to simulate the worn fabric. Then the effect of diameter and concentration of emulsion on the deepening are studied. Results showed smaller diameter and higher concentration could improve the deepening during washing. However, the deepening results are reduced with the presence of surfactants. Maybe the surfactant absorb onto the fabric and prevent the deposition of amino silicon emulsion.