1 Disperse dye dyeing
Disperse dye is a kind of nonionic material with strong hydrophobicity and little water solubility. Dyes have no water-soluble groups in their structure but contain many polar groups, such as -NO2, -NH2, -CN, -OG, etc.
1. The dyeing rate of disperse dyes varies greatly due to different dye types. When color matching, try to use dyes with similar dyeing rates or compatibility. Better dyes, such as disperse dyes and weakly matched dyes or neutral dyes, are mixed and dyed to adjust the color light and improve level dyeing, so as to achieve the purpose of complementing each other’s strengths.
2. The dyeing rate of disperse dyes is highly dependent on temperature, so special attention should be paid to temperature control during dyeing.
① The increase in temperature will reduce the adsorption of dyes by the dispersant, causing collisions between dye particles and increasing the chance of agglomeration.
② On the other hand, as the temperature increases, the solubility of small particles and the growth of large particles increase, which will reduce the stability of the dispersion.
Therefore, the temperature of the prepared dye solution should be low, and prolonged heating of the dye solution should be avoided before dyeing. Generally, dyeing is started at 40~50℃, and the temperature is raised to boiling at about 0.5℃/min. According to the leveling and exhaustion of the dye, keep it warm and wash it with water.
3. Disperse dyes can dye nylon and polyurethane at the same time
The active groups in the dye and the large number of amide groups in the PA6 molecule and the amino groups at the end of the molecule are dyed and fixed through hydrogen bonds, van der Waals forces and dipole forces. In addition, the PA6 molecule contains a large number of non-polar hydrocarbon hydrophobic chains, which is why hydrophobic disperse dyes can dye brocade. Disperse dyes have small molecular weight, good diffusion properties, simple dyeing methods, good level dyeing properties, excellent light fastness, and good coverage. They can avoid nylon fibers having different weights during polymerization or different stretch levels during spinning. resulting in uneven dyeing. However, when dyeing PA6 with disperse dyes, its saturation value is very low, making it difficult to dye dark colors.
4. Disperse dyes can color polyurethane better, which is related to the polyurethane’s own molecular structure and relatively tight foaming structure.
Polyurethane forms an incompletely coherent polymer film on the surface and inside of the synthetic leather base fabric, and its structure is composed of soft segments and hard segments. The soft chain segment has a loose structure and is the main location for disperse dyes to be dyed. Polyurethane absorbs a large amount of disperse dyes, and there is less dye residue in the dyeing residue. This is very necessary when using high-strength disperse dyes to dye dark colors. Within a certain range, as the dyeing temperature increases, the color yield increases. In addition, the color fastness of disperse dyes on polyurethane is also better.
In the dyeing of island-type microfiber synthetic leather, disperse dyes are the main dye type for dyeing polyurethane.
In comparison, some other types of dyes are poor at coloring polyurethane, but on the contrary, they are good at coloring polyurethane. , but at the same time, the nylon is colored, which is very detrimental to the dyeing of finished products with uniform light and no color difference. Even for disperse dyes, the dosage must be controlled, because the coloring of nylon will not only affect its color light, but also affect the dye fastness of nylon.
When dyeing polyester, “color flowers, color differences, and color spots” often appear in Cuilan. What is the reason?
Disperse 60# Emerald Blue S-GL is a high-temperature dye with a macromolecular anthraquinone structure. Molecular formula:
Factors that should be considered when dyeing:
8. Analysis of the reasons for the yellowish and dark dyeing:
① The dyeing pH value is unstable. As the dyeing temperature increases, alkaline substances precipitate and the pH tends to be medium alkaline.
② Reducing substances such as sodium lignosulfonate in the dye and formic acid or citric acid in the dye liquor have a greater impact on the discoloration of Cuilan. It is best to add anti-dyeing agents Salt S.
③ When using emerald green as a sensitive color, it is recommended to avoid reused water as much as possible. When dyeing, the color will turn green and dark when exposed to iron ions. The color will also change slightly when exposed to copper ions. It absorbs the most Wavelength (λmax) 670nm, add chelating dispersant to reduce color change.
④ Set the shape at a low temperature as much as possible within the requirements of the fabric surface.
2 Acid dye dyeing
1. Acid dye dyeing is nylon Important dyes for dyeing, fibers and dyes are mainly bonded by ionic bonds.
2. If the pH value is low (PH<3=) during dyeing, the imino group in the molecular chain can also be positively ionized (-N+H2-) and interact with the dye. Anionic binding. In addition, hydrogen bonding and van der Waals forces also play an important role when dyeing acid dyes in weakly acidic or neutral bath dyeing, and their dyeing saturation values often exceed the saturation value calculated based on amino content. Due to the ratio of the amino group content at the end of nylon The music is light and harmonious, so when two or more dyes are used to match colors, competing dyeing problems often occur. Therefore, you should pay attention to choosing dyes with better compatibility when matching colors.
3. The molecules of nylon are linear molecules. There are no branches or large side groups on the molecular chain, but there are many groups that can form hydrogen bonds. The dye molecules easily interfere with the fiber molecules and have large van der Waals forces. Hydrogen bonds are easily generated between dyes and fibers, so acid��The affinity of dyes for nylon is generally higher than for wool. The saturation value of nylon dyed with strong acid dyes is 2.3%, and that of weak acid dyes is 5%~5.2%. Therefore, weakly acidic dyes are commonly used to dye nylon, using van der Waals forces and hydrogen bonds to improve the dye uptake rate.
4. Nylon is dyed with strong acid dyes, which are generally not dyed deeply. This is because the proportion of amphoteric groups is different (acetic acid or benzoic acid is commonly used in polyamide synthesis to adjust the molecular weight. The terminal amino groups of some macromolecules are acylated and exist in the form of acetyl groups and benzamide groups. The amino group content is lower than the carboxyl group content. In PA6, cyclic amide groups are also found). Therefore, it is difficult to dye deep and dense colors with typical leveling acid dyes, that is, dyeing only by Coulomb force.
5. Acid dyes can also dye polyurethane, because there are amide groups, urea groups, and carbamate acid groups in the polyurethane molecular structure, and the combination form is van der Waals force. , hydrogen bonds and ionic bonds, but the dyeing effect is not ideal. Especially for strong acid dyes, the dyes are almost completely fixed on the surface of the fiber and rarely penetrate into the interior of the fiber. The dye will fade seriously when washed with soap and the color fastness is very poor. The dye uptake percentage of weakly compatible dyes is slightly higher than that of strong acid dyes, and the washing fastness is also better, but the soaping fastness is still not ideal, the dye cannot penetrate into the fiber, and the light fastness is poor.
3 Neutral dye dyeing
Neutral dye is 1: Type 2 acidic mordant dyes, metal atoms and dye molecules are combined in a ratio of 1:2. The dye molecules do not contain water-soluble groups such as sulfonic acid groups, but only contain hydrophilic groups with low water solubility, such as sulfonylamino groups (-SO2NHR), methyl sulfone groups (-SO2CH3), etc., which are generally Dyeing in neutral or weakly acidic medium, hence the name. There are a large number of aminocarboxyl end groups in the nylon molecule, so neutral dyes can be used. </p
