At present, starch and polyvinyl alcohol are widely used in our country as sizing materials for fabrics. Among them, mixed slurries are used more in weaving factories because they have a better effect on weaving. However, it is more difficult for printing and dyeing factories to remove mixed pulp than pure starch pulp, especially using fiber grade polyvinyl alcohol. Because of its high degree of polymerization and alcoholysis, and poor water solubility, desizing is more difficult.
Taking polyester-cotton fabrics as an example, because the desizing is not clean, it will seriously affect the future training and bleaching, silk finishing, coloring, printing and finishing. If the desizing is not clean, singe the singeing. When the top of the polyester is melted into small balls, the synthetic pulp can be mixed into the fiber, so that the softening point of the polyester can be lowered, and the dye can enter the fiber in advance during thermosetting, resulting in a lower sublimation point of the dye. . When printing and cleaning, this kind of "modified" polyester is easy to be stained by reactive dyes, and it can also make the polyvinyl alcohol content in the lye after the silk is too much. When the concentrated evaporation is recovered, the pipeline of the three-effect evaporator is blocked, which affects the normal operation. When dyeing dark colors, it can produce dye-rejection phenomenon, which is similar to white cloud spots on the cloth surface, commonly known as "white cloud flower". Therefore, the cotton fabric requires at least 80% of the receded pulp, and the residual pulp on the cloth must be controlled below 1% of the cloth weight.
Sizing is an effective protection measure for weaving mills, but it is a heavy burden for printing and dyeing mills. Due to the unclean desizing, the fabric penetration is not good, the hand feel is rough and the color is dull, which reduces the finishing quality. Therefore, attention must be paid to desizing. And weaving mills must also consider the difficulty of printing and dyeing production when choosing sizing and process. Only in this way can the quality of the final product be improved in all aspects.