Pretreatment Process Of Lowalkali Oxygen Bleaching Of Cotton Yarn

The traditional pretreatment of cotton yarn cheese was one bath process with scouring and bleaching. Owingto the high pH value after the treatment, it needed to go through washing, acid pickling and other processesrepeatedly. However, the processes took much time, being more complicated, and they increased the consumptionof energy and water. The discharged sewage containing numerous impurities had a high COD value, causing ahigh-cost sewage treatment. At the present, the development trend of international textile technology was toproduce eco-textiles taking advantage of the green technologies, advocate the concepts of saving more energy andbeing environmental protection. Further optimization experiments for traditional processes were under exploring.The post processes of traditional pretreatment were likely to cause the difference of whiteness layers and thesubsequent staining. What’s more, the pretreatment of cotton cheese was directly related to the effect of yarndyeing, the improvement of weaving and winding efficiency. How to achieve a high temperature、 shortpretreatment process with keeping the yarn strength to improve the weaving and winding efficiency, had becomean important indicator of assessing pretreatment processes.The article aimed to explore a high-temperature, low-alkali, free-neutralizing and rapid bleaching process.After treatment, the whiteness and capillary effect were fairly compared to traditional crafts. We could controlthe pH value in less than8, shorten the time in less than20min. Firstly, the task did orthogonal experiments,explored the factors (such as the dosage of refining agent, alkali and hydrogen peroxide, temperature and time)which would affect the pH, whiteness and capillary effect of the working solution, and their specific influences forthat. Secondly, we discussed the activator as an separate factor. This paper mainly talked over the activation ofDM-1430, DM-1435and DM-1436. The main measurement indexes are pH, whiteness, capillary effect,decomposition rate of hydrogen peroxide, breaking strength and weight loss rate. By analyzing the polyamides peroxide activator DM-1340, metal chelate type catalyst DM-1435, the dosage of the activating agent, alkali andhydrogen peroxide, temperature and time separately, the whiteness and capillary effect could meet therequirements, but changing the above factors could not effectively solve the fundamental problem of reducing thepH values of working solutions.Activator DM-1436belongs to a highly effective biomimetic type hydrogen peroxide catalyst, Byrespectively analyzing the dosage of catalyst, alkali and hydrogen peroxide, temperature and time, we found thatthe pH value of the working solution could meet the requirements, meanwhile, other performance indicators wereequal to those of the traditional craft. The optimal process is: activator DM-1436of1.2g/L, caustic soda of0.5g/L,35%hydrogen peroxide of6g/L, the system temperature was110℃, the reaction time was20min. In thepre-processing, the pH value of the working solution was measured at around8, which was greatly improvedcompared to the pH value over11in traditional process. The whiteness of yarn could reach about70%. Thecapillary effect also could reach8.5~9.0cm. Comparing the treatments in the prototype of yarn through theimproved technology and the traditional craft, it could be concluded that the difference of whiteness layers anddyeing properties after the pretreatment by our improved fast bleaching process were relatively close to those ofthe traditional process, in addition to the advantage of saving cost.In summary, the article talked about controlling the pH value of cotton yarn solution after the scouring andbleaching treatment close to neutral by using an effective activator, in the meanwhile, achieving an ideal capillaryeffect and whiteness. Thereby reducing the subsequent washing times, avoiding the neutralisation, shortening theprocess, reducing the water and electricity consumption and being conducive to degrade the organic materials’degradation, the demands of energy conservation and environmental protection could ultimately achieved.