The poor color fastness of reactive dyes is generally related to the incomplete cleaning after dyeing, and consumers are increasingly demanding the color fastness of reactive dyes. The paper will explore the issue of cost-effective anti-staining soaping.
Because reactive dyes have complete chromatogram, easy color matching, bright color, low price, simple process and good fastness, reactive dyes are widely used in the printing and dyeing of cellulose and other fibers. The use of reactive dyes for dyeing and printing has accounted for a considerable proportion.
Because in the dyeing process, there are many dyes, hydrolysis dyes, alkaline agents and other chemicals in the dyeing solution that have not been dyed and fixed, it must be washed and soaped to wash away some impurities and improve the color of the fabric. Brightness, color fastness and cleanliness to meet product requirements.
Reactive dye printing is about 30% of unfixed dye. Together with the printing paste, it must be washed off the fabric. The washed feet will still be stained on the printed fabric, so that the dyeing fastness at the pattern will be reduced, and the white soil without pattern will be stained. Therefore, the detergent should be selected. The anti-white staining detergent ensures that the dirt is thoroughly washed off and all the dirt that has been washed away is no longer contaminated on the fabric.
For reactive dyes, the development is very rapid. Through years of hard work by scientists and technicians at home and abroad, various application technologies, production management, dye wastewater control and treatment technologies for reactive dyes have been continuously developed. This article will focus on the anti-staining soaping process in reactive dye printing and dyeing processes.
1. Trends in anti-staining and soaping of reactive dyes
The reactive dye contains a reactive group of one or more functional groups, and has a wide variety of chemical structures, and therefore, the reaction efficiency is also different. However, one thing these different types of reactive dyes have in common is that they do not completely react with the cellulose fibers during dyeing.
After printing and steaming, the fiber contains:
a reactive dye that has been reacted;
b. unfixed reactive dye;
c. Hydrolysis dye produced by the action of alkali (acid) and water.
d. Residual additives
They are related to the pH value, the temperature and the length of time during dyeing, and can generally be solved by soaping.
In the high-temperature alkaline dyeing bath and the washing bath, the phenomenon that the reactive dye-fiber bond is unstable and breaks the bond is easy to occur, and the dye itself is also hydrolyzed. Since the produced hydrolysis dye has a large affinity, it is easy to cause the dye. Contamination and other issues.
Unfixed dye or dyes are generally difficult to clean hydrolysis, such as easily lead to bleeding, white stain, and redeposition is poor wet fastness and wash fastness problems. Therefore, the soaping agent for cleaning the reactive dye must have a strong detergency and a strong function of preventing re-staining.
Research on soaping technology of reactive dyes is very active at home and abroad. The technician usually uses the simulation device to process the dye content in each tank after the treatment in the formal production process, the hot and cold cleaning temperature, time and speed, and analyze the relationship between various influencing factors and the dye (floating color) removal rate. .
Recent research hotspots:
1) Energy saving, water saving and time saving;
2) Reasonable and simple production process and operation (such as small bath than short time cleaning);
3) low cost,
4) Reduce waste water treatment and environmental rationalization.
Luttringer's research suggests that the temperature difference caused by the continuous soaping treatment of monofunctional groups and difunctional group reactive dyes is different [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 suggests that washing with hot water will give better results when washing high-affinity ingredients, but will cause hue changes. Improper temperature or pH will cause hydrolysis [2]. Thomsen's research suggests that 50% of high affinity hydrolyzed dyes are eluted at high temperature rinses (95-70 ° C). GLBhalla's research suggests that the use of a bimolecular nucleophilic substitution reaction results in alkaline hydrolysis of the dye during alkaline soaping, rearrangement of the dye, and partial bonding. The research by Xiaogu et al. describes the optimal washing conditions; the application technology of soaping agents which have the ability to prevent white soil staining. These studies have provided a basis for the development of reactive dyes to prevent staining soaping agents.
2, the role of anti-stain soaping agent
After the reactive dyed or printed fabric is fixed, it must be washed with water and soaped to remove floating color, paste and additives. The role of anti-staining agents is:
a. When washing, it has an directional adsorption effect on the surface of the fabric;
b. By reducing the interfacial tension, penetrate into the unfixed dye and the fiber, weakening the adhesion of the unfixed dye on the fiber;
c. mechanically acting to remove the unfixed dye from the fibers;
d. If the affinity between the anti-staining agent and the floating dye is greater than the affinity of the fiber for the floating dye and has colloidal properties, the anti-staining agent can disperse the floating dye on the fiber in the washing liquid. Forming a stable suspension dispersion system;
e. The strong complexing and dispersing power of the anti-staining agent allows the floating dye to be dispersed in the washing liquid without re-staining
fiber;
f. the weak cation of the anti-staining agent is combined with the floating dye anion, so that the floating dye does not re-stain the fiber;
g. Anti-staining agent to prevent staining and fabric washing fastness.
3. Raw materials for anti-staining soap lotion for reactive dyes
The main purpose of soaping is to remove unfixed dyes and hydrolyzed dyes. When it is desired to focus on cleaning unfixed dyes, it can be soaped at a high temperature, but it also causes negative effects such as diffusion and penetration of the dye into the interior of the fabric.
In addition, the higher the dye concentration, the greater the amount of paste adsorption, and the greater the affinity of the dye, paste and fiber, the more difficult it is to wash thoroughly. Therefore, it is necessary to use a highly effective soaping agent capable of preventing re-staining for soaping treatment.
Soluble soaping products on the market are everywhere, but the effects are different. The key is the raw materials and chemical composition of the soaping agent.
The current raw materials are:
3.1 Prevent re-adsorption and staining, prevent dye transfer
3.1.1 Adsorption dye particle type
Alkali metal salt such as aluminosilicate: Zn16AI2(0H)35CI2*H20 Mg8AI2(0H)16(N03)2*H2O
3.1.2 Prevent dye transfer, polymer type
For example, a copolymer of PVP with 1-vinylimidazolium and dimethylaminoethylmethacrylate.
Polyvinylpyrrolidone (PVP) is a homopolymer of vinylpyrrolidone with a molecular weight of tens of thousands to hundreds of thousands. The high molecular weight PVP is used as a raw paste for two-phase printing of vat dyes, which can be solidified by alkali. PVP with lower molecular weight can be used as anti-staining agent for embedding dyes and dirt. Because pyrrolidone molecules have C-0 groups and -N--H groups, they can form hydrogen bonds with dyes and other substances to adsorb dyes. It can thus be used as an anti-staining agent. Its anti-staining ability is greater than acrylic, but the price is very expensive. The anti-staining effect of PVP with a copolymer of 1-vinyl quinone and dimethylaminoethyl methacrylate is significantly higher than that of PVP.
3.1.3 Prevent dye transfer, polymer and chemical combination
Such as polyamine ethyleneimine polymer and ethanol-propylene glycol and non-ionic active agent.
3.2 unfixed dyes off the wash
3.2.1 Surfactant type
Wash, disperse, and prevent staining. Such as β-naphthol (PO) (EO) formaldehyde condensate, AEO series, 1860 and so on. Cationic surfactants use the action of cationic surfactants and anionic dyes to remove the floating color on the fibers and prevent the dye from rewet.
3.2.2 Polymer type
For example, organic phosphonate, pentasodium methylene phosphate, polyacrylic acid, copolymer of methic acid-acrylic acid, and the like.
Polyacrylic acid is a copolymer mainly composed of acrylic acid. The low molecular weight PAA with a molecular weight of ≤800 is used as a water treatment agent, 1000-5000 is used as a dispersing agent, and 200,000 to 100,000 is used as a detergent, and the amount is more than 100,000 to 10 million. It is used as a thickener, and it is used as a thickener and flocculant in millions to 100 million. If it has a molecular weight of more than 100 million, it is insoluble in water, swells in water to form a hydrogel, and is used as a water absorbing agent. It can therefore act as a detergent because it has both chelation and can complex metal ions without affecting dye washing. It also has a surface active effect and is one of the polymer surfactants. At the same time, it can form hydrogen bonds with the dye to adsorb the dye, and has the function of embedding the dye. These combined effects can make the printed cloth clean and prevent. It is contaminated again. However, its chelation ability is small, calcium chelation is 4200mg/g, and iron chelation is 480mg/g. It can be adsorbed by suspended particles. After adsorption, the surface of the particles has an electric double layer, which causes electrostatic repulsion when the particles collide, avoiding the aggregation of particles into large particles and indirectly dispersing. The dispersion performance of PAA is the most excellent, and the optimum molecular weight is preferably in the range of 2000-5000. The dispersion efficiency is 93% at a concentration of 20 ppm, and the optimum addition amount is 18.5 mg/L. PAA is available in full acid, semi-nano and full sodium depending on the pH of the medium used.
The horse/propylene copolymer has a block and a homopolymer product due to different dropping methods, and the properties thereof are different, and the product with a small block has a better effect. At the same time, the performance varies greatly due to the ratio. In general, the higher the acrylic acid content, the better the dispersibility of the copolymer, and the higher the content of tannin, the higher the chelating power. It is therefore possible to adjust its proportioning component as needed. In general, horse/propene has good chelation and dispersing ability, and its complexing ability to calcium and magnesium ions is stronger than that of iron ions. Very suitable for use in dyeing. It can also be compounded with zeolite to replace sodium tripolyphosphate for washing, which can improve the washing effect. It can also be used in pre-treatment and printing pastes, as well as in resin finishing baths.
3.2.3 Chemical type
Such as Na6P3O10 K4P207 (or K6P3010) and formaldehyde-sulfonaphthalene condensate.
It is easier to fall off and promotes the diffusion, dispersion and dissolution of the eluted dye.
e. Strong removal ability, effectively preventing re-staining of shed dyes.
f. Efficient removal of some contamination. The ability to decontaminate and prevent recontamination is strong.
g. It has the advantages of saving time and high efficiency, small bath ratio, preventing fading dye re-contamination, saving rinsing times, low or no blistering.
4.2 Example: (Anti-staining soap lotion JM series developed by this research)
2M-101 JM-102 JM-103
Appearance brown liquid liquid yellow liquid light brown liquid
Special cation/nonionic active agent special weak cation/nonionic active agent special yin/nonionic active agent
Ionic anion tooth weak cation anion/nonion
pH 9-10 (1% sol) about 7 (1% sol) about 10 (1% sol)
Solubility is easy to be easily proportioned in any proportion at any ratio in any ratio
Dissolved in water, dissolved in water, dissolved in water
Features can effectively remove reactive dyes from floating and white. Excellent cleaning of cationic dyes. The anti-dye mutual staining effect used in the dyeing of the blended fabric is particularly remarkable. Effectively removes white stains from colored fabrics or knitted gingham fabrics and printed fabrics. Significantly improved color fastness.
In addition to the removal of reactive dyes, direct dyes and acid dyes; polyester-cotton fabrics of polyester, reactive dyes.
5. Method for determining the effect of anti-staining detergent
(Compared with other products and other products developed by the company at the same market cost)
5.1 Wash a piece of dyed or printed unwashed fabric and a white cloth into the washing liquid of the anti-staining detergent, wash it, compare the white cloth to stain and determine the soaping fastness of the dyed or printed cloth. And the washing liquid of ordinary detergent is used as a comparative test, and the staining fastness is obviously improved compared with the ordinary detergent, and the anti-staining ability of the white cloth is not stained.
5.2 Color fastness test after dyeing and soaping (infiltration of dye)
Cotton dyeing (dye such as CIReactive Black 5) → soaping (80 ° C × 10 min) → drying → stained white cloth stitching (long strip) → the lower end of the dyed cloth is immersed in 0.5 g / L nonionic active agent → shelving (20 °C × 10 min) → Measure (the degree of permeation of the unfixed reactive dye (floating color) on the dyed cloth against the white cloth).
6, the conclusion
The removal performance of the unfixed dye and the hydrolyzed dye having high affinity on the dyed cloth. Since the washing effect is due to the fixing rate of the dye used, the affinity , the depth of the dyed cloth, the processing method (printing or dyeing), the washing device, the washing conditions (bath ratio, temperature, time, washing and rinsing of the front section), etc. And change, but the key is still the raw materials and chemical composition of the soaping agent. The soaping agents of different compositions will have different conditions of use, and the same soaping agent will have different effects in different applications. Therefore, we should develop different compositions of anti-staining soap lotion for different situations, and explore the best conditions of use and use according to the characteristics of various soaping agents.
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