The poor color fastness of reactive dyes is generally related to the incomplete cleaning after printing and dyeing, and consumers have higher and higher requirements for the color fastness of reactive dyes. The article will discuss the cost-effective anti-soap soaping problem.
Because reactive dyes have the advantages of complete chromatography, easy color matching, bright color, low cost, simple process, and good fastness, reactive dyes are widely used in the dyeing and processing of cellulose and other fibers. The use of reactive dyes for dyeing, printing processing has accounted for a considerable proportion.
Due to the fact that during the dyeing process, there are many unfixed dyes, hydrolyzed dyes, alkalis and other chemicals in the dyeing liquor, it is necessary to go through multiple washings and soaping to wash away the impurities and improve the color of the fabrics. Brightness, color fastness and cleanliness, so as to meet product requirements.
Reactive dye printing unfixed dye is about 30%. Together with the printing paste, it must be washed from the fabric. The washed foot water will still be contaminated on the printed fabric, which will reduce the color fastness at the pattern and cause the white areas of the pattern to be stained. Therefore, the detergent must be selected. Anti-white soiled detergents ensure that dirt can be thoroughly washed out and all dirt washed off is no longer contaminated by the fabric.
For reactive dyes, it is developing very rapidly. Through years of arduous efforts by domestic and foreign scientific and technical personnel, various application technologies, production management, dye wastewater control and treatment technologies for reactive dyes have been continuously developed. This article will focus on reactive dye printing, dyeing process anti-staining soaping process.
1. Trends of anti-staining soaping of reactive dyes
Reactive dyes contain reactive groups of one or more functional groups, with a wide variety of chemical structures, and therefore, the reaction efficiencies vary. However, one of the common features of these different types of reactive dyes is that they do not completely react with cellulose fibers during dyeing.
After dyeing and steaming, the fiber contains:
a. reactive dyes that have reacted in combination;
b. Unfixed reactive dyes;
c. Alkaline (acid), hydrolytic dyes produced by the action of water.
d. Residual additives
They are related to the pH value of the dyeing, the temperature and time, and can be solved by soaping.
In the high-temperature alkaline dyeing bath and washing bath, reactive dye-fiber bonding tends to be unstable and broken, and the dye itself is also hydrolyzed. Since the produced hydrolyzed dye holds a large affinity, it easily causes the dye to 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, soaping agents used for cleaning reactive dyes must have a strong detergency and a strong anti-staining function.
The research on soaping technology of reactive dyes is very active at home and abroad. Technicians usually use a simulation device to perform the formal production process, test the content of dyes that fall off in each tank, heat and cold cleaning temperature, time and speed, and analyze the relationship between various influencing factors and the removal rate of dyes (floating color). .
Recent research hotspots:
1) Energy saving, water saving and time saving;
2) Reasonable and simple production processes and operations (such as a small bath for a shorter period of time);
3) Low cost,
4) Reduce the amount of wastewater treatment and environmental protection rationalization.
According to Luttringer's research, the difference in detergency caused by the temperature difference between monofunctional groups and reactive dyes with difunctional groups is different [1][4]. High-affinity unfixed dyes and hydrolyzed dyes should be rinsed with hot water [ 3]; pH, salt concentration and flow ratio are closely related to the soaping effect. Aspland's research suggests that when washing high-affinity ingredients, washing with hot water will give better results, but it will cause hue changes. Improper temperature or pH can cause hydrolysis reaction [2]. Thomsen's study concluded that 50% of high-affinity hydrolyzed dyes elute at high temperature (95-70°C). GLBhalla's research suggests that the use of a bimolecular nucleophilic substitution reaction results in alkaline hydrolysis of dyes, rearrangement of dyes, and partial bonding phenomena during alkaline soaping. Xiaogu et al.'s study describes the best washing conditions; the application technology of soap detergents that can prevent white soil contamination. These studies have provided the basis for the development of active dyes to prevent the development of soaping agents.
2, the role of anti-staining soap lotion
Reactive dyeing or printing fabrics must be washed and soaped to remove floating colors, pastes, and additives. Antifouling agents have:
a. When washing, there is a directional adsorption effect on the floating color of the fabric surface;
b. By reducing the interfacial tension, infiltrate between the unfixed dye and the fiber to weaken the adhesion of the unfixed dye on the fiber;
c. The unfixed dye is removed from the fiber by mechanical action;
d. If the affinity of 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 floating dyes on the fibers in the water washing solution. In the formation of a stable suspension dispersion system;
e. The strong complexing and dispersing force of anti-staining agent disperses the floating dye in the water washing solution without re-staining
fiber;
f. The weak cation of the antistaining agent binds to the anion of the floating dye dye, so that the floating dye does not re-stain the fiber;
g. Anti-staining agent to prevent contamination and fabric washing fastness.
3, the raw material of anti-staining soap lotion for reactive dyes
The main purpose of soaping is to remove unfixed dyes and hydrolyzed dyes. If you want to focus on cleaning unfixed dyes, you can use high-temperature soaping. However, it also causes negative effects such as diffusion and penetration of the dye into the fabric.
In addition, the higher the dye concentration, the greater the amount of paste adsorption, and the greater the affinity of dyes, pastes, and fibers, the more difficult it is to thoroughly clean. Therefore, it is necessary to use a highly effective soaping agent that can prevent re-staining and soaping treatment.
Many re-contaminated soap lotions are on the market, but the effects are not the same. The key is the raw material and chemical composition of the soap lotion.
The current raw materials are:
3.1 Prevent re-adsorption and staining to prevent dye transfer
3.1.1 Adsorption Dye Particles
Such as the alkali metal salt of aluminosilicate: Zn16AI2(0H)35CI2*H20 Mg8AI2(0H)16(N03)2*H2O
3.1.2 Preventing Dye Transfer, Polymer Type
Examples are copolymers of PVP with 1-vinylimidazole and dimethylaminoethyl methacrylate.
Polyvinylpyrrolidone (PVP) is a homopolymer of vinylpyrrolidone, molecular weight from tens of thousands to hundreds of thousands, high molecular weight PVP is used as a vat dye two-phase printing with the original paste, the case of alkali can be solidified. The lower molecular weight PVP can be used as an anti-staining agent for embedding dyes and dirt, because pyrrolidone molecules have C-0 groups and -N--H groups, which can form hydrogen bonds with dyes and other substances and adsorb dyes. It can be used as a stain-repellent agent. Its anti-staining ability is greater than acrylic acid, but it is expensive. The copolymers of PVP with 1-vinylimidazole and dimethylaminoethyl methacrylate are significantly more stain-resistant than PVP.
3.1.3 Preventing Dye Transfer, Polymers, and Chemicals Combined Use
Examples are polyurethane ethyleneimine polymers and ethanol-propylene glycol and nonionic surfactants.
3.2 Unfixed Dye Washing
3.2.1 Surfactant type
Wash, disperse and prevent stains. Such as β-naphthol (PO) (EO) formaldehyde condensate, AEO series, 1860 and so on. Cationic surfactants use cationic surfactants and anionic dyes to remove the floating color from the fibers and make the dyes no longer get back to the fibers.
3.2.2 Polymer type
Examples are organic phosphonates, pentasodium methylenephosphonates, polyacrylic acids, and maleic acid-acrylic acid copolymers.
Acrylics are copolymers based on acrylic acid. Low molecular weight PAA with molecular weight ≤ 800 is used as a water treatment agent, 1000-5000 is used as a dispersant, 2-100000 is used as a detergent, and 100,000 or more is used as a detergent. Used as a thickening agent, used as a thickening agent and a flocculant in the range of 10 to 100 million, molecular weight greater than 100 million is insoluble in water, swells in water to form a hydrogel, and is used as a water absorbing agent. It can be used as a detergent because it has both chelating effect and complexes metal ions without affecting dye washing. It also has a surface activity and is a kind of polymer surfactant. At the same time, it can form hydrogen bonds with dyes and adsorb dyes. It has the function of embedding dyes. These comprehensive functions can make nets washed and prevent It is stained again. However, its chelating ability is small, the calcium chelating power is 4200 mg/g, and the iron chelating power is 480 mg/g. It can be adsorbed by the suspended particles. After adsorption, the surface of the particles has double electric layers, so that electrostatic repulsion occurs when the particles collide, and particles are prevented from agglomerating into large particles to indirectly disperse the particles. The PAA dispersion is the best, and the optimum molecular weight is preferably in the range of 2000-5000. At a concentration of 20 ppm, the dispersion efficiency can reach 93%, and the optimal addition amount is 18.5 mg/L. PAA has all-acid, half-nano and total sodium types, which can be selected according to the pH of the medium used.
Horse/propylene copolymers have different block and near-homopolymer products because of their drop-wise addition methods, and their performance is different. Small block products have better results. At the same time, the performance varies greatly due to different proportions. In general, the higher the acrylic acid content, the better the dispersibility of the copolymer, and the higher the content of maleic acid, the higher its chelating power. Therefore, it is possible to adjust its proportioning components as needed. In general, horse/propane has a very good chelating and dispersing ability, and its complexation to calcium and magnesium ions is stronger than iron ions. It is suitable for use when dyeing. It can also be combined with zeolite to replace sodium tripolyphosphate for cleansing, which can improve the washing effect. It can also be used in pretreatment 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 and so on.
Easier to fall off, it can promote the diffusion, dispersion and dissolution of the eluted dye.
e. Strong removal ability, effectively prevent re-staining of detached dyes.
f. Efficient removal of some contamination. The ability to decontaminate and prevent re-contamination is strong.
g. Equipped with time-saving and high efficiency, small bath ratio, prevention of stain re-staining, rinsing times, low or no blistering.
4.2 Examples: (The anti-staining soap lotion JM series developed by this research institute)
2M-101 JM-102 JM-103
Appearance tea brown liquid yellow liquid light brown liquid
Ingredients Special Anions/Non-ionics Special Weak Positives/Non-ionics Special Anions/Non-ionics
Ionic Anion Dental Weak Cationic Anionic/Non-ionic
pH 9-10 (1% sol) about 7 (1% sol) about 10 (1% sol)
Solubility is easily easily proportional to any ratio in any ratio
Dissolved in water dissolved in water dissolved in water
Features can effectively remove the floating color and white ground reactive dyes. The cationic dye wash effect is particularly good. The anti-dyeing stains used in the dyeing of blended fabrics are particularly noticeable. Effectively removes white stains on colored fabrics or knitted fabrics and printed fabrics. Significantly improve color fastness.
In addition to the stains used to remove reactive dyes, direct dyes and acid dyes; Polyester, cotton, reactive dyes stained fabrics.
5, the method to determine the effect of anti-staining detergent
(Products of other companies and their own products are compared at the same cost using the market price)
5.1 Put a piece of dyed or unsteamed fabric and a white cloth into the washing solution of the anti-staining detergent. After washing, compare whether the white cloth is stained and determine the soaping fastness of the dyed or printed cloth. The common lotion was used as a comparative test. The stain-proofing ability was better if the color fastness was significantly higher than that of the ordinary detergent, and the white cloth would not stain.
5.2 Color fastness test after dyeing and soaping (permeation of dyes)
Cotton dyeing (dye such as CI Reactive Black 5) → Soaping (80°C × 10 min) → Drying → Staining with white cloth (strips) → Lower end of dyeing cloth immersed in 0.5 g/L nonionic surfactant → Shelved (20) °C × 10 min) → Measured (degree of bleeding of white cloth by unfixed reactive dye (floating) on ​​a dyed cloth).
6. Concluding remarks
Unfixed dyes with high affinity on dyed fabrics and removal performance of hydrolyzed dyes. The washing effect is due to the different fixing conditions such as fixing rate, affinity , depth of dyed cloth, processing method (printing or dyeing), washing device, washing conditions (bath ratio, temperature, time, washing, and front rinsing) of the dye used. However, the key is still the raw materials and chemical composition of the soap lotion. The use conditions of soap soaps of different compositions will be different, and the same soap lotion will have different effects in different occasions. Therefore, we must develop different compositions of anti-staining soap lotions for different situations, and discuss the best conditions and occasions for use according to the characteristics of various soaping agents.
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