Dyeinyg Of Cotton Fibers With Indigo Bule Dyes In Liquid Paraffin System And The Related Dyeing Theory

Indigo dyeing often uses the method of repeated rolling-oxidation–rolling.It has many problems,such as low dyeing rate,complex dyeing process and low production.Repeated staining will lead to a significant reduction in spinnability for loose cotton,so it is used in warp dyeing process.Therefore,the variety of indigo dyeing for all-cotton products is greatly restricted.Our research group had studied the once dyeing technology for indigo dye/D5 system and the dyeing mechanism to solve the above problems.However,D5 is a volatile siloxane of expensive and complex recycling processes.Recently,it had been listed as a highly regarded substance by the European Union.In this paper,liquid paraffin charging of low price and stable performance was selected as new non-water medium and studied dyeing processes,dyeing mechanism.Firstly,the effect of the pretreatment process on the whiteness,water absorption and other scouring properties of the treated loose cotton fibers,the K/S value of the dyed loose cotton fibers and the homogeneity of the dyed loose cotton fibers was studied.The optimal pretreatment process was established.The effects of sodium hydroxide concentration,insurance powder concentration and temperature on the reduction process of indigo dye were studied.The effects of dyeing medium,dyeing time,temperature and bath ratio in indigo dye/liquid paraffin medium were studied.The optimal dyeing process was established and then matched oxidation process.Finally,FTIR,SEM,XRD and other instruments were used to characterize cotton fibers dyed by different non-water media.The dyeing kinetics model,adsorption isotherm and thermodynamic parameters were studied and determined.The results showed that the optimum process of pretreatment for loose cotton fiber is:NaOH3 g/L,TF101C 3 g/L,scouring temperature 90?,scouring time 40 min,scouring bath 1:20.The optimized process for 30 g/L indigo dye leuco is:NaOH 50 g/L,insurance powder 160 g/L,reduction temperature 60?,reduction time 20 min.The optimal dyeing conditions of cotton fiber in liquid paraffin medium is:cotton fiber with liquid rate 80%,m _{cotton fiber}:m _leuco=1:2,dyeing temperature 60?,dyeing time 50 min,m _{cotton fiber}:m _{Liquid paraffin}=1:50.After dyeing,the best oxidation process is:oxidant a 3 mL,bath ratio of 1:10,oxidation time 6 s,oxidation temperature90?.In terms of dry rubbing fastness and light fastness,loose cotton fibers dyed with high viscosity liquid paraffin are the best.Cotton fibers dyed with different non-water media and water bath are very similar in appearance,chemical structure and crystalline state.The adsorption kinetics model of loose cotton fiber in different non-aqueous media conforms to pseudo-second-order kinetics.The adsorption isotherm conforms to the Freundlich.Dyeing heat,dyeing affinity and dyeing entropy are all negative values.Which viscosity is higher,the absolute value is greater.