The Method Of Cold Pad-batch Sample Dyeing With Reactive Dyes On Cotton Knitted Fabrics

Compared with traditional exhausting dyeing technology, the cold pad-batch (CPB) dyeingprocess with reactive dyes is low energy, dyestuff consumption and effluent discharge and highfixation. However, the low rate of color conformity of test samples and production is a bigproblem for practical production. Current production requires "small batch, many varieties, fastdelivery", but routine cold pad-batch dyeing technology in laboratory is hard to meet theserequirements. Therefore, a rapid and convenient method of sample dyeing with high veracity,applicability and fixation is very important.Two main topics were discussed in this paper: first, comparative study of acid dissolutionmethod and urea stripping method on fixation rate determination of reactive dyes. second,systematic research of different methods of rapid sample dyeing of CPB with reactive dyes.Finally, a rapid and convenient method with high veracity was selected through comparing theconsistency of rapid dyeing samples and criterio at room temperature, fixation rate and K/S valueunder different conditions.First, the determination methods of fixation rate of CPB dyeing with reactive dyes wasdiscussed. The fixation rate of dyed cotton knitted fabric were measured and compared by aciddissolution method and urea stripping method, respectively. The results showed that there weresignificant differences between the two methods of fixation rate determination. Under differentconditions of dyeing, the fixation rate and RSD value of acid dissolution method of dyed fabricwere between91.06%~113.55%and0.61%~113.55%respectively, while the results of ureastripping method were84.98%~90.86%and0.56%~2.15%. The results of urea strippingmethod was closer to the practical situation, and has higher accuracy and reliability than aciddissolution method. It was also found that sulfuric acid would bring changes in visible lightabsorption performance of reactive dyes, which affected the accuracy of fixation ratedetermination. Second, three methods of rapid sample dyeing at ovens, microwave ovens and constanttemperature water baths were discussed in this paper.In the constant temperature oven method, the fixation effects of time and temperature onstability and consistency with criterio were compared. The batching condition with oven of70℃,40min～60min or80℃,20min～40min were chosen. Under that conditions, the K/Svalue of dyed fabrics were between17.78～19.80and the color aberration DECMCwas less than0.8, which showed good fixation effects.The heating method of microwave oven and its effects on fixation were researched andprocess conditions of rapid sample dyeing at microwave ovens was obtained. Through discussingthe effects of heating methods of microwave oven, water volume and pick-up of fabrics to thetemperature of water and fabrics at microwave ovens, it was found that low heat and extra water atthe microwave oven could make temperature controllable, and less than80℃. Setting samplesgot with Argazol dark red CBS reactive dyes20g/L, Na2CO350g/L under room temperature for8h as criterio, with which we compared samples gaining under different heating methods, themanner of laminated fabric and pressure. The results showed that choosing single layer, tiling, nopressure, low heating method could get good and stable fixation effects with fixation rate between72.71%～89.84%,K/S value between72.71%~89.84and color aberration is low to4AATCCgrey grade.Fabrics dyed with three primary colors of Argazol CBS reactive dyes were batched atconstant temperature water baths with different temperature and time. The results demonstratedthat fabrics batched at70℃for30～60min could keep fixation rate between84.68%～89.64%,K/S value between17.18～19.44and color aberration DECMCless than1.0. It was found that thismethod was universally applicable by the expanded experiment of Argazol CBS and Shenxin SNEreactive dyes.Comparing the fixation effect of methods with ovens, microwave ovens and constanttemperature water baths with criterio at room temperature, we found the constant temperaturewater baths method was convenient, accurate, controllable and stable, which was suitable for rapidsample dyeing with reactive dyes.Third, mixed alkali agent and batching time were optimized at35℃by the research of dyedfabrics with three primary colors of50g/L Argazol CBS reactive dyes, and the result showed thatunder the condition of Na2CO350g/L and NaOH4g/L, batched for10h, the fabrics dyed withArgazol dark red CBS, orange CBS and dark blue CBS could reach best fixation rate and K/Svalue, which were87.95%、90.03%、88.09%and29.96、28.01、25.66, respectively. Under the samedyes and alkali agent, dyed fabrics batched at60℃for30～70min could gain the same fixation effect with criterio. The color aberration DECMCwas less than0.8, and the color fastness torubbing and washing with soap generally meet the requirements.Finally, the fixation method of constant temperature water baths was used on dyed fabricswith three primary colors of Argazol CBS reactive dyes together. Calculating the fixation rate ofthese dyes with the maximum absorption wavelength-simultaneous equations method andabsorption spectrum-peak area method. The results showed that the fixation rate could reach to76.29%～87.45%, and Integ value is between42.59～42.75, which indicates that this method wasalso applicable to mixed dyeing. The appropriate condition: mixed alkali agent Na2CO350g/L andNaOH4g/L，60℃,30～70min。...