In the dyeing process of reactive dyes, an alkali agent is generally added to fix the color. The alkali agent used is generally soda ash, but also an alkali substitute powder. These alkali agents need to be fully dissolved. After the color fixation is completed, these alkali agents will make the colored cloth more alkaline, while those undissolved solid alkali agents may make the colored cloth more alkaline, which requires printing and dyeing manufacturers to After the color fixation is completed, rinse thoroughly with a large amount of water in time, and even add dilute acetic acid solution for neutralization to remove these excess alkali agents.
However, in the actual production operation process of the printing and dyeing factory, due to various practical conditions, the excess alkali agent on the colored cloth cannot be removed in time, which may cause wind printing problems on the dyed cotton cloth. Printing and dyeing manufacturers use vinyl sulfone reactive dyes to produce wind marks during the dyeing process of cotton cloth, mainly in the following situations:
(1) At present, after printing and dyeing factories use reactive dyes to fix the cotton cloth, the colored cloth often needs to wait for cleaning because the flat washing equipment cannot be arranged. The waiting time is as short as a few hours or as long as more than ten hours. , The colored cloth has strong alkalinity due to the delayed cleaning of the alkali agent. Especially the part of the colored cloth exposed to the outside is often caused by the evaporation of moisture on the cloth to make the color cloth more alkaline and unevenly distributed. At this time, the vinylsulfone reactive dyes are prone to bond breaking. Including dyes that have reacted with cotton fibers to form covalent bonds, some bonds may also be broken, resulting in windmark problems.
(2) After the reactive dye fixes the cotton cloth, if the color cloth floats too much, the concentration of the alkali agent is too strong, and even undissolved solid alkali agent remains, plus the use of flat washing equipment with low flat washing efficiency , The colored cloth may also continue to have a strong alkalinity due to the inadequate cleaning of the alkaline agent, incomplete neutralization, and uneven distribution. At this time, the vinyl sulfone reactive dyes are prone to bond breaking, including the The dyes that react with cotton fibers to form covalent bonds may also partly break the bonds, causing windmark problems.
(3) After fixing and cleaning the reactive dyes on the cotton cloth, failure to dry in time or uneven cooling after drying (such as piled in the air duct after drying and blowing cold air) may also cause wind printing problems.
The solution to the windmark
In the process of processing dyed cotton fabrics (bed covers, bed sheets and other textiles), printing and dyeing enterprises in Wuxi, Jiangsu often have inexplicable wind printing when using some reactive dyes such as turquoise blue and dark gray. The specific manifestation is that irregular and irregular light-colored blocks or light-colored prints appear on the dyed cotton cloth, which causes quality problems of dyed cotton products, and also causes enterprises to often contradict the unstable quality of dyed cotton products. For this reason, some institutions set up a project to study this problem. After the cooperation of Donghua University and dye companies, a large number of experiments were carried out on the improvement of dye performance and the selection of related auxiliaries, which basically solved the problem of cotton dyeing. In the end, a satisfactory result was achieved on the wind seal problem.
In view of the actual situation of printing and dyeing factories in the actual production operation process, due to various actual situations, the excess alkali agent on the colored cloth cannot be removed in time, and the actual situation of the dyed cotton cloth producing wind printing problem, the solution is: from vinyl sulfone reactive dyes Based on the analysis of the bond breaking mechanism, the key factors to prevent and reduce the bond breaking of vinyl sulfone reactive dyes were developed to develop a high-concentration liquid fixing agent with good washability to replace the traditional soda ash (including alkali powder, which are all powders). Shape), used for fixing of reactive dyes.
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