Prevent the form

Color stains are stains that appear on the dyed fabric with regular, similar shape and size or irregular, not fixed shape and size, and the color of the dyed fabric is the same color. This kind of defect is difficult to repair once it occurs, which has a great impact on the quality of dyeing products, and must be paid attention to.

The reasons causing

The causes of color spot defects are as follows. 1, dye condensation due to the direct collision of dye molecules and gather into larger dye aggregates (or dye association), these larger dye aggregates, deposited on the fabric in the process of dyeing, resulting in color defects. When dyeing:

· The dissociated dye molecules will recrystallize in the process of heating (or cooling) to form new grains;

· In the process of heating up (or cooling down), the free dye molecules will gradually adsorb on the crystal surface of the original dye, making the original dye crystal grow from small to large;

· Dye particles in free and semi-free states will collide directly without dissolution to form larger dye aggregates. These larger dye aggregates are one of the important factors that cause color stains.

In the color rendering (or fixing) process of dyeing, strong cohesion between dye molecules, resulting in dye aggregation, will also cause color defects. Its characteristics are distributed and irregular. 2, dye taring of the so-called dye taring, refers to the process of dye particles and surfactants condensed into coal tar like substances under high temperature conditions. There are usually four factors that cause the taring of dyes

· Improper pretreatment and insufficient purification. Fabric contains oil (in the process of spinning and weaving, additional lubricant, emulsifying agent, antistatic agent, etc.) and oil (sticky dirty) in the process of machining processing not dye bath in net, under the condition of high temperature dyeing, the oil repellent once contact with dye particles, and mutual adsorption, the product is bigger, the final formation of tar.

, when using the cloud point temperature below dyeing of non-ionic additives or non-ionic and anionic complex additives (such as refining agent) do before processing, if you don't net washing, will be a lot to the dye bath, with the increase of temperature of the dye, non-ionic composition will gradually lose water soluble, or with anionic components from hydrophobic oil and grain of precipitation. At this point, the dye particles in an unstable state in the dye bath facilitate the precipitation of these hydrophobic oil particles. At this time, dye bath in the unstable state of the dye particles and these hydrophobic oil particles adsorb each other, forming sticky colored tar like material, adhere to the fabric, produce color stains.

· When dyeing with non-ionic and anionic compound additives such as high temperature leveller, if the dosage is too high (more than 2g/L) or the dye is mixed with high concentration and directly added into the water bath above 90℃, the binding force between non-ionic and anionic components is weak and the turbidity point of non-ionic components is not high enough. It often causes the non-ionic component to dissociate from the colloidal particle of the anionic component and aggregate with the dye to form a tarified substance.

· When the diffusion agent and other anionic surfactants are used for dyeing, if the auxiliaries are not well dissolved, the granular dyes and auxiliaries will adsorb each other. Once put into the pot, they will form a sticky paste that will adhere to the fabric and produce color stains.

3. Due to improper operation and foaming of additives in the dyeing process, the dye often floats the colored lake on the surface. If the lake is not treated, it is brought to the fabric by the dye foam, which will cause the sticky stain.