The dyeing and printing of textile products need to be done in a certain way to remove impurities and oil stains on the cloth surface. This cooking process is often called scouring. And in the refining of various types of infiltration, emulsification, washing, dispersing, wetting function of chemical auxiliaries, called scouring agent.
During the refining process, the scouring agent is through its wetting effect, the weakened adhesion of the oil wax and the fiber in the fabric, and the gradually reduced interface, to make the oil wax fall off the fabric. At this time, the oil wax particles and water contact surface increased, forming a very unstable system, the surfactant in scouring agent has emulsifying and dispersing effect, which is easy to form micelles in water, and the oil wax wrapped in the micelle to form a comparatively stable system, which can prevent the oil grains from being deposited on the fabric. On the other hand, with the help of the wetting effect of surfactants, in a certain temperature and sufficient time conditions, the caustic soda and fiber impurities fully effect the decomposition, and the decomposition of its solution or the use of surfactants dispersed in scouring fluid, by washing and removal.
In a broad sense, the addition of acid, alkali, oxidant, reducing agent and all kinds of surfactants can be called scouring agent in scouring process. But in the textile industry, generally speaking of scouring agent in textile, mostly the concept of narrow sense, mainly refers to all kinds of anion, non-ionic surfactants and appropriate additives, through a certain proportion of the method to get a washing effect, and with infiltration, emulsification, dispersion, complexion and other synergistic effects of the complex. Because the scouring of fabrics is a very complex physical and chemical process, in the surface chemistry scouring agent emulsification, dispersion, and chelate metal ions ability are very important properties, and these properties alone in some surfactants is difficult to complete. All kinds of surfactants have their own advantages and disadvantages, thus the scouring agent is often composed of a number of different types of surfactants. The current scouring agent in the market is generally composed of nonionic and anionic surfactants.
Scouring process is that the desizing of cotton cloth boiling in a certain concentration of caustic soda solution for several hours, or soaking up in the alkali steam for a certain time, which make the fat wax in cotton fiber saponification, emulsification, pectin for pectin salt; the cotton seed shell easy to wash away; and the residual slurry further expanded and removed. Synthetic fibers do not contain natural impurities, generally in no need of scouring. However, in the cotton blended fabric, the cotton fiber contains more impurities, scouring is still required.