Wet And Short Steam Dyeing Of Cellulose Fabrics With Reactive Dyes Based On Atmospheric Saturated Steam Medium

To enhance the K/S value and fixation rate of fabrics dyed using pad-steam dyeing process,the effects of electrostatic interaction,temperature variation of padded fabrics and hydrophobic effect on the dyeing properties of pad-steam process were firstly investigated and verified in this paper.Based on these researches,an industrialized pad-batch-steam dyeing process was developed and the dyeing mechanism was revealed.The main research conclusions can be summarized as follows:(1)The Zeta potential of cotton fabrics increased from-24.9 mV to+13.5 mV by modificating with Poly[Styrene-Butyl acrylate-(P-vinylbenzyl trimethyl ammonium chloride)]P(St-BA-VBT)nanospheres.Compared with untreated cotton fabrics,the Na2CO3 and steaming time of cationic cotton fabrics were reduced by 37.5%and 40%,respectively.The K/S values and dye fixation rates of dyed cationic cotton fabrics increased up to the most 39.4%and 14.3%.The excellent dyeing performance of cationic cotton fabrics indicated that weakening the electrostatic repulsion between reactive dyes and cellulosic fibers is beneficial to improve pad-steam dyeing.(2)The heating rates and pad-steam dyeing of the padded fabrics were determined by their thermal constants(thermal conductivity and volume heat capacity).The thermal conductivity and volume heat capacity of padded fabrics were reduced by 4.4%and 5.5%,meanwhile,the heating rates were enhanced by adding Na2SO4.Consequently,the K/S values and dye fixation rates of cotton fabrics dyed with pad-steam dyeing process increased by 1.1 and 10.3%via using Na2SO4.The thermal conductivity,volume heat capacity and pickup of padded fabrics satisfy the Boltzmann function,and the correlations are higher than 0.96.When the fabric pickup increased from 30%to 80%,the thermal conductivity and volume heat capacity of padded fabric increased significantly.The heating time which takes for padded fabrics to heat up to 90 ? were extended by 15 s.The K/S value and dye fixation rate decreased with increasing fabric pickup,which was consistent with the change of fabric heating rates.(3)When the number of reactive groups is the same,the higher the molecule weight per water soluble group,i.e.the stronger dye hydrophobicity,the higher dye fixation rate.The reactive dyes with less water soluble groups have the characteristics of low alkali consumption,short steaming time,dark color and high dye fixation rate.The high ethanol content in padding liquor,the high K/S value and fixation rates of dyed fabrics.It may be attributed to the fact that ethanol accelerates the heating rates of fabrics,eanhances the hydrophobilic effect of dyeing medium,and weakens the electrostatic repulsion between reactive dyes and cellulose fibers.(4)A batch procedure was incorporated in the pad-steam dyeing process to develop the pad-batch-steam dyeing process.Compared with the fabrics dyed with conventional pad-steam dyeing,the K/S values and fixation rates of fabrics dyed with pad-batch-steam dyeing process were enhanced by 0.3?2.8 and 1.7%?16.1%,respectively.The alkali concentration and steaming time were reduced by 5?10 g/L and 20%?33.3%,respectively.The excellent dyeing performance and fastness of corduroy,towel and Tencel/cotton union fabrics were be found using the pad-batch-steam dyeing process.The cross-section of padded fabrics indicated that the batching procedure facilitates the diffusion of reactive dyes.Besides,the resistance and speckle rate confirmed the change in content and distribution of free water molecules within padded fabrics during the batching procedure.The pad-batch-steam dyeing process effectively solves the problems of low dye fixation rate and poor color build-up property,and greatly reduces the content of dyes and inorganic salts in dyeing wastewater.The proposed dyeing technology is not noly a major breakthrough in pad-steam process of cellulosic fabrics dyeing with reactive dyes,bult also a major step towards cleaner dyeing of cellulosic textile industry.The pad-batch-steam dyeing process has a broad application prospects in dyeing of cellulosic fabrics with reactive dyes.