Preparation And Application Of Soaping Agent For Reactive Dyes

Soaping is needed to wash off the unfixed dyes on the surface of the fabrics afterdyeing with reactive dyes. Traditional soaping methods cannot achieve the purpose ofcomplete elimination of the unfixed dyes because of the substantivity between dyes andfibres. Some surfactants used in the traditional soaping agents are forbidden because oftheir environmental pollution and toxicity. It is more and more necessary to develop newsoaping agents to accord with environmental protection demand.In this paper, considering from the aspect of environmental protection, free stimulating,biodegradable, good water-soluble polymeric surfactant PVP(10％), PAAS (4～5％),nonionic surfactant AEO-9(10％), anionic surfactant SDS (1～3％)were chosen andmixed together to make excellent soaping agent HY for reactive dyes. HY was used inthe washing procedures after dyeing of knitted cotton fabrics with reactive dyes. Throughmeasuring the absorption values of liquor with spectrophotometer device, stainingchromatism values of white fabrics and color changing detected by X-Rite (USA)spectrophotometer, the influence on washing-off unfixed reactive dyes, prevention ofback-staining of hydrolyzed reactive dyes in different hydrolysis percentage and color offabrics were researched and discussed. The optimum application conditions of HY weresoaping temperature 95～98℃, soaping time 15～20min, dosage of HY 2～6g/L.The results showed that the higher washing temperature and the longer time werebeneficial for the washing-off unfixed dyes, which could also lead to an increase instaining. The higher hydrolysis rate dye solution, the more amount of staining on whitefabrics. High dosage of HY should be avoided and low amount could obtain betterwashing and anti-staining effect such as lighter, more saturated and purer color of fabrics.In addition, the fastness to rubbing and soaping could be enhanced by 1～1.5 grades. HYbelongs to new green auxiliary in dyeing field due to its low pollution, low consumptionof water as well as simple operating procedure.