Superfine fiber is a new type of synthetic fiber. It is through the polymer chemical and physical modification, application of spinning and processing technology to make ultra fine fiber profile, using composite and mixed fiber; and to apply multiple deformation and new surface treatment and other means, the makes synthetic fiber have various characteristics of natural fibers, and gives the synthetic fiber the comprehensive performance of natural function, style sensory, etc..

The new synthetic fibers, such as single fiber fineness, cross sectional morphology, surface morphology, shrinkage, and polymer structure, are quite different from those of conventional synthetic fibers. Therefore, there are many differences in the process of spinning, weaving, dyeing, and finishing of conventional synthetic fiber and conventional synthetic fiber.
 
This is related to the evenness in dyeing process. Because of the dynamic equilibrium between the three states of the disperse dyes, the transition between the single molecule, the micelle and the crystalline dye will occur during the dyeing process. Especially the crystal will become large, will produce condensation between the grains, sometimes crystal changes will occur, which will affect the dyeing properties of disperse dyes, making it be easy to produce unevenness, dyeing color, flower and other defects. The superfine fiber fineness and special surface structure, unit weight of the fiber surface area will lead to relatively large adsorption rate dye in the dyeing process, which is speeding up, occurring the problems of probability towards coloring- much more than the ordinary fiber. Thus to choose appropriate processing technology with leveling agent can reasonably avoid the problem.

The solubilization effect of leveling agent for disperse dyes increases the amount of dye solution in single molecule and micelle. The single molecule dye is the main form of dyed fiber, micelle like dye releasing the dye monomer ratio of dye crystals are conducive to uniform dyeing. So the solubilization of leveling agent is a measure of the merits of the leveling agent.

Secondly, it is the effect of leveling agent on dyeing rate. Because of the large specific surface area of superfine fibers, the adsorption rate of dyes is also very fast, which is one of the factors which are easy to form uneven dyeing. If is a blend of superfine fiber, due to different fiber size, specific surface area is not only larger, and the difference is great, which is more likely to cause the difference in the uptake rate of the results that is easy to color flowers. Therefore, dyeing rate is also one of the important indicators of leveling agent.
 
Effect of leveling agent on the fabric dyes analysis and migration behavior. When the disperse dye is used to dye superfine fiber, because of the initial adsorption, it is more likely to cause uneven dyeing than ordinary fiber. If the dye to strengthen analysis and transfer of the fabric dyes is in the dyeing process, it can make the fabric dyed flowers at the dye through the analysis and re-dyeing to achieve uniform dyeing, and finally to get the leveling effect.

Effect of leveling agent on dispersion of disperse dyes at high temperature. Although disperse dyes contain dispersants, they can not completely solve the high temperature stability of disperse dyes. With the increase of dyeing temperature, dyes tend to gather, form color spots, and also stain equipment easily. Leveling agent can effectively improve the disperse dyes, and to disperse and reduce the agglomeration tendencies of dye evenly.
 
Effect of leveling agent on dyeing depth of superfine fiber. The surface area of superfine fiber is rather large, so to use the same amount of dye, the superfine fiber has the shallow color.

Effect of leveling agent on compatibility of dyes. In practical production, color matching dyeing is often used, so the compatibility between dyes becomes an important index to choose color matching dyes.

In summary, superfine fiber because of its special surface structure and size, in the dyeing process of leveling agent, is more strict. Leveling agent is an important way to improve the dyeing properties of microfiber. Leveling agent is mainly to disperse dyes dissolved state, dyeing rate and dye transfer, analytical, high temperature dispersion, which plays a relevant role in the deep dyeing and dye compatibility improvement etc.. Therefore in the superfine fiber dyeing process of leveling agent, it should be selected from many aspects in order to consider the performance of leveling agent and screening.