Color fastness is a kind of color fastness, also called color fastness or color fastness. It refers to the migration and stain of dye or residual floating color on fabric, which mainly reflects the fabric after washing or being rained. Causes the degree of contamination of the dye at the dyeing point to be dissolved and transferred to a white background or a light colored base fabric. Color fastness has become one of the common testing items in Japan. It is generally required to reach level 4 or above, mainly in the middle and dark colors. It is often associated with color fastness. If the color fastness is good, the color fastness will be good.
The improvement of the color fastness of cotton fabric can be improved and strengthened from the following main aspects:
1. Choose the right dye
Since the dye is often accompanied by a small portion of the dye that is not completely reactive in the synthesis, the presence of these dyes will not only affect the color fastness but also other color fastness, so the color fastness test should be performed before use. At the same time, it should be noted that it is preferred to use a reactive dye which does not have a water-soluble group in the dye structure and is not too high in directness.
2. Pay attention to the impact of water quality
Calcium and magnesium ions in water will form insoluble matter with dyes and adsorb on the surface of the fiber, which will become floating color and hinder the diffusion and penetration of dyes. It will reduce the color fastness and even affect the color and vividness. Therefore, it is necessary to use soft water or add chelating dispersant. Wait.
3. Strengthen the washing and soaping process
The alkali salt remaining on the fiber, the hydrolyzed and unbonded dye float color, etc. are the key factors affecting the fastness. The high-performance anti-stick soaping agent with excellent performance should be selected, and the soap should be soaped under neutral or weak acid as much as possible. Higher temperatures are used to wash away unbonded dyes inside the fabric, but care should also be taken that excessive temperatures can cause broken bonds of the bound dye, especially under alkaline conditions.
4. Using solid color processing
The use of excellent cationic and reactive fixing agents can block the water-soluble groups of the dye to make the dye become a poorly soluble lake and deposit in the fiber, which reduces the water solubility of the dye, and a small amount of hydrolyzed dye can also participate in fixing Cross-linking further increases the bonding force with the fiber, thereby effectively improving the wet treatment of the dye, the color fastness, and the like, and if necessary, the individual deep dark color can also be subjected to the re-fixing process.
Of course, in addition to paying attention to the above points, whether the quality of the grey cloth itself and the pretreatment, whether it is well-drained or not, and whether the dyeing process is reasonable or not, will be related to whether the dye can fully adsorb, diffuse and fix the dye, further standardize the operation and optimize the process to avoid dyeing. Excessive dyeing on the surface of the fiber and the formation of the dyeing phenomenon are the basis and guarantee for ensuring the color fastness of the reactive dye and also improving the color fastness.