Acid Dyes is a water -soluble dye with acid groups on a type of structure, which is stained in an acidic medium. Most of the acid dyes contain sodium sodium salt, which can dissolve in water, bright color and complete chromatography. It is mainly used for dyeing such as wool, silk and nylon, and can also be used for leather, paper, ink, etc. There is generally no color for cellulose fiber.
The acid dye chromatography is complete and the color is bright. Compared with direct dyes, the acidic dye structure is simple and lacks a longer common two bonds and the same plane structure. Therefore, it lacks directability to cellulose fiber and cannot be used for chromosomes of cellulose fiber. Different types of acidic dyes, due to different molecular structures, their dyeing performance is also different, and the dyeing methods are also different.
It is mainly used for dyeing such as wool, silk and nylon, and can also be used for leather, paper, ink, etc. There is generally no color for cellulose fiber.
(1) Strong acidic dye
The earliest developed acid dye requires dyeing in a strong acidic dye bath. Its molecular structure is simple, the molecular weight is low, containing a sulfonic acid or carboxyl group, which has little combination of wool. It is evenly called acidic dye, but the color light is not deep, the fastness of the washing resistance is poor, and the wool is damaged during dyeing. Such as acid red G (that is, C.I. Acid Red 1).
(2) weak acidic dye
By increasing molecular weight, introducing groups such as molecular weight, introducing various groups of molecular weight, introducing long carbon chains, etc., weak acid dyes are generated. The molecular structure is more complicated, and the combination of wool is large. It can dye wool in the weak acidic medium, no damage to wool, darker color and light, and improve the firmness, but uniform dyeing. Such as weak acid blue raw (that is, C.I. acid blue 80).
(3) Acid media dyes
After treatment with certain metal salts (such as chromium salt, copper salt, etc.), the acidic dyes of metal complexes are formed on the fabric. Media dyeing procedures are relatively comprehensive, but they can get better performances such as sun -resistant, washing, and frictionality, such as acid -sex media black T (that is, C.I. Media Black 11).
(4) acidic complexity dye
It consists of some acidic dyes with metal such as chromium and cobalt. It is soluble in water, its dyeing products, and excellent light resistance. Its dye mother is similar to the acid media dye, but when preparing dyes, metal atoms have been introduced into puppet nitrogen dye molecules. The metal atom to dye molecules is 1: 1, so it is also called 1: 1 metal complex dye. There is no need to use media dyeing agents when dyeing. Such as acidic collusion yellow GR (that is, C.I. acid yellow 99).
Acid dyes are only suitable for fiber with positive charge, such as: dye polyamide fiber on an acidic bath, but cotton fiber can also be stained with acid dyes after cationization.
When using two dyes dyeing, the structure structure of the dye structure and ceda cotton dominates.
Increasing the number of cations on the caddy cotton crocestation can get better washing fast.
In any case, the overall color fastness of the yang -dyed cotton cotton on the acid dye is equivalent to the same as the same acid dye -dye -dye -dyeing nylon.
1. Choose dyes with caution
Metal dyes containing copper, chromium and nickel are dyes that are pre -made into metal complex with specific structured dyes and metal complexes. There are 93 acidic metal complex dyes. EU regulations: When it is used for fibrous dyeing, each metal complexyl dye is dyed, and the amount of dyeing liquid is discharged into the wastewater for treatment should be less than 7 %, that is, the color of the metal complex dye should be More than 93 %; at the same time, copper or nickel should not exceed 75ms / KS fiber, and chromium should not exceed 50M ore KS fiber. Therefore, the selected dye requires a certain degree of purity.
2. Dyeing water
The hardness of the dyeing of acid dyes is best for 100-150 mg/kg if the water quality is high, and 0.5-2s/L chelating agent can be added to improve water quality and ensure staining. However, chelating agents such as phosphate or surfactants will destroy the integrated effect of the dye itself to varying degrees, affecting the color of the color and the color fastness. The experiment found that the chelating agent 88 provided by Ortho Chemical Co., Ltd. has a small impact on metal ions in the dye. Therefore, the chelating agent must be screened when dyeing. Do not use it blindly.
3. Duration method
Due to the inconsistency of the dissolving of acid complexation dyes, it should be treated differently during the gauge. Generally, use cold water to make a slurry shape, and then dilute it with hot water or boiling water to dissolve it. Sometimes because the commercial dye is added to the dye, it is difficult to dissolve. If necessary, stir it while cooking until it is fully dissolved. Finally, the sieve is filtered slowly into the cylinder to prevent the formation of color points (spots).
4. Pre -fabric processing
Due to oil, slurry, impurities and natural pigments in the fabric. Sometimes it is not only removed from the slurry, but even half drift to dye. Practice has proved that the pre -processing of pure textiles is easier, while the blended textiles are difficult, but it must have good penetration (wet) before dyeing, depending on the specific variety.
5. The role of acid
Regardless of sulfuric acid, antic acid (methic acid), and acetic acid, they are acidic and acidic complexyl dyes. Sometimes in order to further dye the dye (as exhausted), the amount of acid is often added in the dyeing and later period. However, it is necessary to dilute in advance when adding, turn off the steam valve, stop heating, and slowly add people to prevent dyeing flowers.
6. The role of Yuanming powder
Sometimes acid complexyl dyes require pH value below 4, so Yuanming powder can be used as a slow dye. Conversely, if the pH value of the dyeing bath is above 4, it is not appropriate to use Yuanming powder, because it will increase the tendency of dyes, but non -ion surfactants, such as flat plus O and emulsifier OP as slow dye agents as slow dye agents Essence Dosage should be dependent on the shades of color and dyeing equipment. Too much dosage will make the wool perfume, rough feel, affect the absorption of the dyes in the dyeing solution, and will also affect the normal operation of the circulating switching system due to the increase in the foam on the liquid flow machine; if the amount is less, the effect is not good.