Abstract:
Poor color fastness of reactive dye printed materials is generally related to incomplete cleaning after printing and dyeing, and consumers have increasingly higher requirements for the color fastness of reactive dye printed materials. This article discusses cost-effective anti-stain soaping.
Anti-stain soaping issues
Because reactive dyes have the advantages of complete color spectrum, easy color matching, bright color, low price, simple process, and good fastness, reactive dyes are widely used in fibers. Printing and dyeing processing of fibers such as plain fiber. The use of reactive dyes for dyeing and printing has accounted for a considerable proportion.
Due to the dyeing process, there are many unfixed dyes, hydrolyzed dyes, alkali agents and other chemical substances in the dyeing solution, which must be washed and soaped in multiple ways. Wash to remove these impurities and improve the color brightness, color fastness and cleanliness of the fabric, so that it can meet product requirements.
About 30% of the unfixed dyes in reactive dye printing. The printing paste must be washed off the fabric. The washed foot water will still stain the printed fabric, which will reduce the dye fastness of the pattern and stain the white ground without the pattern. Therefore, the detergent must be selected. The anti-white stain detergent ensures that the dirt will be thoroughly washed away and all the dirt will no longer be stained on the fabric.
For reactive dyes, development is very rapid. Through the long-term hard work of domestic and foreign scientific and technological personnel, various application technologies, production management, dye wastewater control and treatment technologies of reactive dyes have been continuously developed. This article will focus on the anti-stain soaping process during reactive dye printing and dyeing.
1 Research trends in anti-stain soaping of reactive dye printed materials
Reactive dyes contain one or more reactive groups with functional groups. They are of various types and have diverse chemical structures. Therefore, the reaction efficiencies are also different. However, one thing these different types of reactive dyes have in common is that they do not completely react with cellulose fibers when dyeing.
After printing, dyeing and steaming, the fiber contains:
a. Reactive dyes that have been reacted and combined;
b. Unfixed reactive dyes;
c. Hydrolyzed dyes produced by the action of alkali (acid) and water.
d. Residual additives
They are related to the pH value, temperature and time during dyeing. Generally, they can be determined by Soaping to resolve.
In high-temperature alkaline dyeing baths and washing baths, the bonding between reactive dyes and fibers is prone to instability and bond breaking. The dye itself will also be hydrolyzed. Due to the hydrolysis produced Dyes have a high affinity, so they can easily cause problems such as dye re-staining.
Unfixed dyes or hydrolyzed dyes are generally difficult to clean and can easily lead to bleeding, white ground staining, re-staining, and poor wet fastness and washing fastness. question. Therefore, the soaping agent used to clean reactive dyes must have strong cleaning power and strong prevention of re-contamination.
Research on reactive dye soaping technology is very active at home and abroad. Technicians usually use a simulation device to test the dye content falling off in each tank, hot and cold cleaning temperature, time and speed after processing according to the formal production process, and analyze the relationship between various influencing factors and the dye (floating color) removal rate .
Recent research hot spots:
1) Energy saving, water saving and time saving;
2) Reasonable and simple production processes and operations (such as small bath ratio and short time cleaning);
3) Low cost,
4) Reduce the amount of wastewater treatment and rationalize environmental protection, etc.
Luttringer’s research believes that the temperature difference during continuous soaping treatment of monofunctional and bifunctional reactive dyes causes different washability [1][4], high affinity Unfixed dyes and hydrolyzed dyes should be rinsed with hot water [3]; pH value, salt concentration and flow ratio are closely related to soaping effect. Aspland’s research shows that when washing high-affinity ingredients, washing with hot water can achieve better results, but it will cause hue changes.
Improper temperature or pH value can cause hydrolysis reaction [2]. Thomsen’s research believes that 50% of high-affinity hydrolyzed dyes are eluted during high-temperature rinsing (95-70°C). G.L.Bhalla’s research believes that bimolecular nucleophilic substitution reaction causes alkaline hydrolysis of dyes during alkaline soaping, dye rearrangement reactions and partial bonding phenomena. The research of Otani et al. elaborated on the optimal washing conditions and the application technology of soaping agents that have the ability to prevent stains on white floors. These studies provide a basis for the development of soaping agents with anti-staining properties of reactive dyes.
2 The role of anti-stain soaping agent
Reactive dye dyeing or printing After the fabric is solidified, it must be washed and soaped to remove floating color, paste and additives. The functions of the anti-fouling agent are:
a. When washing, The floating color on the surface of the fabric has directional adsorption;
b. By reducing the interfacial tension, it penetrates between the unfixed dye and the fiber, weakening the adhesion of the unfixed dye on the fiber;
c. Make the unfixed dye fall off from the fiber through mechanical action;
d. If the anti-staining agent and floating color The affinity of the dye is greater than the affinity of the fiber for the floating dye, and it has colloidal properties. The anti-fouling agent can disperse the floating dye that has fallen off the fiber into the washing liquid to form a stable suspension dispersion system;
e. The strong complexing and dispersing force of the anti-fouling agent allows the floating dye to be dispersed in the washing liquid without re-staining the fiber;
f. The weak cations of the anti-staining agent combine with the anions of the floating dye, so that the floating dye does not re-contaminate the fiber;
g. Anti-staining agent treatment It has excellent stain protection and fabric washing fastness. </p
