English Views: 0 Author: Site Editor Publish Time: 2022-05-02 Origin: Site
Cotton fabric is a common fabric for dyeing and finishing. Often used: direct dyes, reactive dyes and sulfide dyes dyeing processing methods.
Direct dyes are water-soluble dyes that can dye cellulose fibers directly in neutral dyeing bath.
Direct dye chromatography complete, easy to use, low price, washing fastness is not good, poor sun fastness.Curing agent is often required.
1. Dyeing performance:
Direct dyes are soluble in water and their solubility increases significantly with increasing temperature.
Common promoters used in direct dye dyeing are salt and sodium sulfate. Bright color can be obtained by using sodium sulfate as dye promoter.
Direct dyes are not resistant to hard water and must be dyed with soft water.
2. Dyeing method:
It is generally carried out on the ordinary rope dyeing machine, and the dyeing bath ratio is 1:15-30. The light-colored bath ratio is larger than the dark one.
The dyeing temperature is generally used near the boiling point to obtain good dye
transfer (so-called dye diffusion from high concentration to low concentration on the fiber) and good color light and fastness. Dyeing generally starts at room temperature (dark can start from 60℃to 80℃).
3. The fixation of direct dyes
The use of cationic fixing agent, fixing agent Y and fixing agent M treatment, to improve its fastness. Reactive dyes for cotton knitting.
Reactive dyes are soluble in water and contain active genes in their molecular structure. Under certain conditions, they can covalently bond with hydroxyl groups on cellulose fibers.
Reactive dyes have bright color, good wet treatment fastness and friction fastness, good evenness, uniform chromatography, convenient application and good light fastness.
The effect of affinity: When dyes with great affinity are used for dyeing, they have a relatively high dyeing percentage, which is conducive to improving the utilization rate of dyes. However, it is necessary to strengthen washing, otherwise it will affect the washing and rubbing fastness of dyes.
The effect of bath ratio: When dyeing reactive dyes, the bath ratio should be reduced as far as possible without affecting the evenness, which can improve the color fixing rate and reduce the hydrolysis of reactive dyes in the dyeing bath.
K reactive dyes, it is necessary to dye at a higher temperature. X-type reactive dyes, with the increase of temperature, can promote the hydrolysis of the dye, but can not be dyed at high temperature.
Influence of alkali agent: Under the condition of ensuring solid color, a lower PH should be selected as far as possible. Generally, the PH should be controlled within 10-11.
Influence of electrolyte: Reactive dyes have small molecules, good diffusion performance and good leveling effect. Therefore, dyeing promotes dyeing by adding more electrolytes.
Vulcanized dyes are cheap in price and convenient in application. They are suitable for dyeing cellulose fibers.
Vulcanized dyes are not bright color, poor chlorine fastness, chromatography is not complete, brittle damage to fiber, sunburn fastness with different varieties have great differences, generally black 6-7, blue 4-5, yellow orange 3-4, soap fastness, most can reach 3-4.
Soap Treatment: remove the floating color attached to the surface of the fiber, improve the color fastness and improve the color of the dye.
Taikoo Oil Treatment: dyeing by Taikoo oil treatment can improve the color of dyeing, especially to increase the vulcanized black, and also has a certain anti-brittle effect.
Fixing Treatment: commonly used fixing agent M for fixing treatment.
Anti-Brittle treatment: some vulcanized dye dyes, such as placed for a long time will produce brittle phenomenon, so that the fiber strength is seriously reduced. Anti-brittle treatment, often with urea 0.8-1%, add 5-5.8% taikoo oil.
