8 ways to help improve wet rubbing fastness
1. Selection of dyes
There are many varieties of reactive dyes, and their quality varies greatly. It is important to choose dyes that meet the coloring quality standards.
1. Use dyes with double reactive groups and multi-reactive groups
S-triazine reactive dyes react with fibers to form ester bonds, which have poor acid resistance and stability. Vinyl sulfone dyes react with fibers to form ether bonds and have poor alkali resistance. Dyes with dual reactive groups are acid and alkali resistant. Improved stability.
2. Choose dyes with suitable directness
If the substantivity of reactive dyes (such as vinyl sulfone-based reactive dyes) is too high, the diffusion performance is poor. The dyes tend to accumulate on the surface of the fabric and are difficult to diffuse and transfer into the fibers, which can easily cause floating colors and difficult to Wash, but the directness cannot be too low to affect the fixation rate, so the directness of reactive dyes should be medium. The directness can be obtained from the data provided by the dye supplier.
3. Choose dyes with high fixation rate
Dye with high fixation rate has less floating color, fixation rate >80%, and the amount of floating color after dyeing is relatively small, which is beneficial to removing floating color; fixation rate 15% are difficult to remove floating colors and are not suitable for dyeing medium and dark colors.
4. Choose dyes with high lifting power
Dyeing process design, the amount of dye should generally not exceed 10% of the color saturation value. Excessive dye cannot be completely dyed, and the color fixation is insufficient. The unfixed dye is attached to the surface of the dyed object. Affects the wet rubbing fastness of the dyed object. When dyeing dark colors, dyes with high absorption rate, high fixation rate and high lifting power must be used, such as reactive dyes with dual reactive groups and multi-reactive groups.
2. Choose natural cotton with even yarn count and clean surface. When pretreatment is required, use a high-efficiency pre-treatment agent.
3. Use soft water or deionized water as much as possible for coloring to reduce the impact of calcium, magnesium and other ions in the water on coloring.
4. Selection of fixing agent
High-efficiency fixing agent should be able to “bridge” between the dye and the fiber to form a compound. When reacting with the dye, it can react and cross-link with the cellulose fiber, so that the dye fiber can be tight and firm. It is connected with the ground to prevent the dye from falling off the fiber and causing a decrease in color fastness. The color-fixing effect is achieved by the color-fixing agent neutralizing the fiber and cationic groups in the medium and then forming salts with the dye anions to achieve the color-fixing effect.
Excellent formaldehyde-free color fixing agent can improve the wet rubbing fastness of fabrics dyed with reactive dyes by 0.5-1 level. The performance of the fixing agent is: a film-forming polymer compound, polyurethane or silicone with -OH, -NH2, and a cross-linking agent and high-molecular polymer cross-linking, making it durable and fast film-forming It is non-toxic, does not change color, does not turn yellow, and does not reduce the light fastness. It can make the dyed objects feel smooth, reduce the surface friction coefficient, and maintain the breathable and breathable wearing properties of the dyed objects.
5. Special additives can reduce the amount of dye used in post-finishing to obtain deep and concentrated color effects, and the wet rubbing fastness is also improved.
6. The pH value of the cloth after dyeing.
When dyeing dark-colored cotton fabrics, a higher amount of alkali is used. After dyeing, strengthen washing, soaping, neutralization and alkali removal. Do not allow alkali on the fabric, otherwise it will cause the dye to be hydrolyzed after dyeing. Wet rubbing fastness decreases. Generally, the pH value of the cloth surface is controlled at 6.5-7.5, and cannot exceed 9 or less than 3.
7. Improve the properties of the cloth after dyeing. The post-finishing of the fabric can be done by biological enzyme polishing, etc., which can increase the cleanliness of the cloth surface and also improve its wet rubbing fastness.
8. It is difficult to remove the floating color after reactive dyes are colored. After the soap is boiled, appropriate color stripping agent can be used to remove the floating color and improve the wet rubbing fastness. .
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