The Whole Workflow Process Of Knitted Cotton Fabrics At Low Temperature

In traditional pretreatment of cotton knitted fabrics, exceedingly high temperatures (normally～98°C) are usually used in the scouring/bleaching process. High temperature, strong alkali andmany auxiliaries are necessary for the removal of cotton hulls, wax, and pectin. These conditionscan give the fabrics a good capillary effect, satisfactory whiteness, and they are beneficial to thesubsequent dyeing process. In order to improve the color fastness, high temperature, repeatedsoaping and washing processes are used to remove the fabric floating color in the soaping process.In summary, such harsh conditions will lead to high energy consumption, serious pollution, highfabric mass loss, rough hand feeling and other issues. In order to solve these problems, the studyon the whole workflow process of fabrics at low temperature is urgent.As a cooperation with the enterprise, this topic studied the application of low-temperaturescouring agent, hydrogen peroxide activator in the pretreatment of cotton knitted fabrics and theapplication of low-temperature soaping agent in the soaping process, and it could control theentire process of cotton knitted fabric at60℃. For the realization of low-temperature processesand the solution of those problems, the research was aimed to provide theoretical and technicalsupport by the selection of low-temperature bleaching auxiliaries and the process optimization.Firstly, this paper mainly studied the application of low temperature scouring agent DM-1377,hydrogen peroxide bleaching activators DM-1430/DM-1436/DM-1435and the bio-scouringenzyme DM-8654in the pretreatment of cotton knitted fabric at60℃. After the optimal processes(60℃) were determined by orthogonal experiments, we compared the low-temperaturepretreatment effects with the traditional process. The results showed that the fabric of lowtemperature pretreatment has slightly lower whiteness, better bursting strength, handfeeling, weight loss, and wax reservation than the fabric of traditional pretreatment.Secondly, based on the current dyes and traditional dyeing processes of the company, wedyed the above pretreatment methods’ fabrics by the active dyestuff red BF-3B (1%o.w.f.), then,we compared the color indexes (K/S value and color difference) of these different pretreatment processes with the traditional process. According to the comparison and analysis of step1, weselected the best pretreatment additive. Among those low-temperature bleaching pretreatmentmethods’ pretreatment effects (whiteness and capillary effect, bursting strength, hand feeling, waxcontent, pectin content and the wastewater COD value), we saw that their effects were similar.Considering the dyeing effects, low temperature scouring agent DM-1377and hydrogen peroxideactivator DM-1430were better, but the DM–1430is solid powder, which could bring trouble toworkshop actual production. Finally, DM-1377was identified as the most suitable pretreatmentauxiliary, and its pretreatment process was bath ratio1:10, pH11, DM-13773.0g/L, H2O2(35%),15g/L,60℃,60minutes.Then, the cotton knitted fabrics were processed by low-temperature scouring agent DM-1377,biochemical method and traditional bleaching method. After that, we dyed the above pretreatmentmethods’fabrics by the active dye stuffs (0.1%,0.5%,1%,2%,4%o.w.f.) BF-3B, BF-3R, blue R,black B and blue G, and fabric (without soaping)’s cotton wax, dyeing wastewater COD weretested. We found that cotton fabric’s wax retention rate of DM-1377method was more than thetraditional method; their wastewater COD values were similar.Finally, the fabrics of low temperature scouring/bleaching and dyeing were soaped by low-temperature soaping agent DM-1542(1g/L) at60℃. The fabrics of traditional scouring/bleachingand dyeing were soaped by traditional soaping agent at90℃. The results showed that, the fabricsof low temperature processes got similar dyeing performances with the traditional process, thecolor difference was controlled in an acceptable range, and it has a good handfeeling, high strength retention rate and high wax retention rate.In conclusion, the research of the whole workflow process of fabrics at low temperature willmeet the needs of practical production, and it will bring considerable economic benefits for thesociety.