Foam Dyeing Technology On Cotton With Reactive Dye

As a new kind of low water consumption and energy-saving continuous dyeing process,foam dyeing caused an upsurge of research interest in the world.However,the aggregation of the dye molecules and the difficulty to obtain dark color need to be solved.This paper took foam dyeing of cotton fabrics with reactive dyes as the research content.The foam dyeing machine provided by Neowin Chemicals(Shanghai)CO.,LTD was used to operate the dyeing process.The K/S value and various fastness of the foam dyeing were studied and compared to those of the traditional pad dyeing.The Response Surface method was used to select,analyze and optimize the factors that influence the foam dyeing effect.The fixing velocities and rules of dyestuffs with different structures were studied and compared.Firstly,the effects of the foam dyeing and the traditional pad dyeing at the same condition and the same dyes pickup were judged using K/S value,soaping fastness,dry and wet rubbing fastness.Secondly,the foam dyeing process was divided into two kinds:one for the dark color and another one for the light color.According to the result of the single factor experiments before,dye foam ratio,wet pickup,stabilizing agent concentration,alkaline agent concentration,steaming temperature and steaming time were determined as the six most notable factors to the foam dyeing effects.The K/S value and the soaping fastness was chosen to be the response value of the foam dyeing process for the light color while the K/S value and the wet rubbing fastness for the dark color.The significance and the way of the influence of these six factors on the foam dyeing effects were obtained by the Plackett-Bunnan experiments.The level ranges of these most influential factors were determined with steepest ascent experiments.The rules of affecting the response values and the interactions of these factors were studied with Central Composite design experiments.The optimal processes of foam dyeing for light color and for dark color were predicted by the regression equation fitting.The followed verification tests were used to determine the accuracy of the predictions.Last,the fixing rules of the dyes with different structures were analyzed by drawing the fixing velocity curves of these dyes.The results indicated:The color promoting performance of the foam dyeing was apparently better than that of the traditional pad dyeing.Also,the various fastness of the foam dyeing can reach the level of that of the traditional pad dyeing with a better wet rubbing fastness than the pad dyeing.The steaming temperature,stabilizing agent concentration and steaming time were the most crucial factors that affect the foam dyeing effects with light color while the wet pickup and the steaming temperature were the most crucial factors that affect the foam dyeing effects with dark color.The optimal foam dyeing factors for light color with the goal of the dyeing effects being above 4 level in soaping fastness while obtaining a greatest K/S value were:dye foam ratio 8,wet pickup 30%,stabilizing agent concentration 0.92g/L,alkaline agent concentration 12g/L,steaming temperature 147.5? and steaming time 4.97min.While the optimal foam dyeing factors for dark color with the goal of the dyeing effects being above 3 level in wet rubbing fastness while obtaining a greatest K/S value were:dye foam ratio 8,wet pickup 41.32%,stabilizing agent concentration 0.28g/L,alkaline agent concentration 24g/L,steaming temperature 150.81? and steaming time 4.97min.According to the verification tests,the deviation between the actual values and the predicted values in both prediction was below 1%,which indicated that the predictions were accurate.Dyes with different structures have different fixing rules and need different conditions.In order to obtain optimal dyeing effects,different dyeing and fixing process need to be considered according to different structures of dye molecules.