Technology | Methods to improve the color fastness of fabrics to wet rubbing

The main factors affecting the color fastness to wet rubbing

1. The type of fabric and the structure of fabric

2. Pre-treatment of textiles, such as desizing, scouring, bleaching, mercerizing, etc.

3. Whether the selection of textile dyes and the control of process, temperature, time, etc. are strict

4. Whether the selection and use of additives are correct

5. Post-processing of textiles, etc.

Improve from the following points

1.According to the analysis of textile materials, general chemical fiber fabrics have better color fastness to wet rubbing than natural fabrics such as cotton, and thin fabrics are better than heavy fabrics. Therefore, in the processing of textiles, each process must be evenly processed to improve the absorbability of the fiber and the reactivity of the dye or the adsorption and fixation, so that the dye is fully dyed. In the process, strict control is required, and additives must be selected and used correctly. In order to improve the color fastness to wet rubbing of textile products, sufficient soaping can be carried out in the post-treatment of textiles. For example, the high temperature setting of polyester fiber after dyeing with disperse dyes causes the dye to migrate to the surface of the fiber, causing the rubbing fastness to decrease. In response to this situation, a reinforcing color agent or a smoothing agent can improve the color fastness to rubbing to a certain extent.

2. When choosing dyes, choose dyes with good liftability and levelling properties. Good liftability and levelling properties are conducive to the penetration and diffusion of dyes, which can improve wet rubbing fastness to a certain extent. The dye should have a certain degree of water solubility and directness, and there should not be too many water-soluble groups, otherwise it will affect the wet rubbing fastness later. And the directness should also choose medium as the best. The directness of the selected dye should not be too high, under normal circumstances it should be greater than 70%.

3. The color fastness to wet rubbing of natural fabrics such as cotton is relatively poor. Therefore, for cotton grey fabrics, we should choose grey fabrics with uniform yarn count and smooth surface. If pretreatment is required, high-efficiency pretreatment agents should be used.

4. Use soft water or deionized water as much as possible for the dyeing water of reactive dyes, so as to reduce the influence of calcium and magnesium plasma in the water on the dye, thereby improving the fiber's absorption of the dye and making the dye fixation in the fiber molecule more stable.

5. Use high-efficiency fixing agent. The selected fixing agent should be able to link the dye and fiber to form a compound. When reacting with the dye, it can react and crosslink with the cellulose fiber, so that the dye and fiber can be tight and firm. The ground is connected together to strengthen the combination of dye and fiber, prevent the dye from falling off the fiber or migrating to the surface of the fiber, and avoiding the decrease of color fastness.

6. Use special additives, such as darkening agents, to finish the dyed fabrics, which can reduce the amount of dyes to obtain a deep color effect and improve the color fastness to wet rubbing.

7. Pay attention to the pH value of the fabric surface after dyeing. Because under normal circumstances, the dyeing process of dark and dense cotton fabrics uses a higher amount of alkali, and then strengthens the washing, soaping and neutralization, and the fabric cannot be carried with alkali, so as to prevent the dye from being hydrolyzed after dyeing and causing the wet rubbing fastness to decrease. Usually the pH value of the cloth surface is controlled at 6.5-7.5, not more than 9 or less than 3.

8. Starting from the improvement of the characteristics of the dyed fabric surface, finishing the fabric, such as biological enzyme polishing treatment, etc., makes the fabric surface smoother and less frictional, thereby improving its wet rubbing color fastness.

9. The floating color on the fiber is extremely unfavorable to the color fastness to wet rubbing. For fabrics dyed with deep and dense reactive dyes, it is better to soap twice, but too many times of soaping will damage the dyed dyes and cause bond breaking. , Resulting in reduced effectiveness. There has been a test, washing the dyed fabric with anti-staining detergent (amount of 2-3g/L, treatment at 95°C for 10min), which can make the wet rubbing fastness reach level 3. In actual mass production, many situations often occur, such as fluctuations in steam supply pressure, so that the temperature does not rise within the specified time; errors in blocking operations or sudden equipment failures cause the scheduled program to deviate and add dyes after color differences occur. Make process changes, etc., resulting in differences in color fastness (including cylinder differences). For some mechanical equipment, dyes, alkalis and other chemical agents, it is not practical to make the cleaning after dyeing very thorough in large-scale production, so it should be selected reasonably.

10. It is difficult to remove the floating color after dyeing with reactive dyes. Therefore, after soaping, an appropriate color stripping agent can be used to remove the floating color, so that the fabric dye and fiber after the floating color can be removed. Form a complete body, thereby improving its wet rubbing color fastness.

11. In view of the situation that the covalent bond formed by reactive dyes and fibers may become unstable or even broken under acid or alkali conditions, a soft, strong, and water-resistant film can be formed on the surface, which is water-repellent. And soft smoothness to improve wet rubbing fastness. The sol-gel method (Sol Gel method) is an important method for preparing inorganic membranes. Through sol-gel technology, thin films with different components are formed on the fabric, which can improve the abrasion resistance and water and oil repellency of the fabric. It can improve the wet rubbing fastness to a certain extent. However, it has a strong impact on its feel.?