In the dyeing process of fiber yarn, thread or fabric, it is added to promote uniform dyeing without producing defects such as color streaks and stains.
Most leveling agents are water-soluble surfactants. According to the effect of leveling agents on the diffusion and aggregation of dyes, they are mainly divided into two types: fibrophilic leveling agents and dye-philic leveling agents.
The fibrophilic level dyeing agent has a certain affinity to the fiber. During the dyeing process, it will compete with the dye to dye the mat, and then it will be gradually replaced by the dye to slow the dyeing. Some anionic surfactants are used, such as fatty alcohol sulfates. Dye-philic leveling agents can significantly increase the degree of dye aggregation, and the affinity for dyes is greater than that for fibers. Before dyes are dyed, leveling agents combine with dyes to form a stable aggregate, thereby reducing the dye The diffusion rate delays the dyeing time. With the change of conditions, the dye gradually separates from the leveling agent and combines with the fiber, but at this time, the leveling agent still has a certain affinity for the dye. For non-dyed fabrics, the dye can be pulled down from the fiber and dyed up to Where the color is light, so the dye-friendly leveling agent has the effect of slow dyeing and migration dyeing at the same time. Substances in this category include certain non-ionic surfactants, such as polyoxyethylene ethers of fatty alcohols or alkyl phenols.
In addition, according to the types of fibers used, leveling agents can also be divided into leveling agents for natural fibers, leveling agents for nylon, leveling agents for acrylic, leveling agents for polyester, and leveling agents for blended fabrics.