Three dyeing methods for clothing washing and dyeing

1. Carrier staining method
The carrier staining method is carried out by heating under normal pressure. It utilizes chemicals that have direct effects on both dyes and fibers. When these chemicals enter the interior of polyester during dyeing, they also carry dye molecules in. This type of chemical is called a carrier or dye carrier.
The principle of using a carrier to dye polyester is that there is a strong intermolecular attraction between the benzene ring in polyester and the aromatic nucleus in dye molecules. Polyester can adsorb simple hydrocarbons, phenols, and other chemicals, which become carriers. Due to the interaction between the carrier and polyester, the molecular structure of polyester is relaxed, the fiber voids are increased, and molecules are easily able to enter the interior of the fiber. At the same time, due to the direct interaction between the carrier itself and the fiber and dye molecules, it can not only help dissolve the dye and bring the dye molecules to the fiber surface, increasing the concentration of the dye on the fiber surface, but also reduce the surface tension of the fiber, allowing the moving dye molecules to quickly enter the fiber void area, increasing the diffusion rate of the dye molecules, promoting the binding of the dye with the fiber, and thus completing the dyeing step. After staining, use alkaline washing to completely remove the carrier. Common carriers include ortho phenylphenol, biphenyl, methyl salicylate, etc. Due to their toxicity and harm to human health, they are rarely used. Therefore, this article only provides a general introduction.
2. High temperature and high pressure dyeing method
The high-temperature and high-pressure dyeing method is carried out in a humid and hot state under high temperature and pressure. The dyeing rate of dyes is very slow within 100 ℃. Even when dyed in a boiling dye bath, the dyeing rate and percentage are not high. Therefore, the pressure must be kept below 2atm (2.02 × 105Pa), and the dyeing bath temperature can be increased to 120-130 ℃. Due to the increase in temperature, the chain segments of fiber molecules move vigorously, producing more and larger instantaneous pores. At this time, the diffusion of dye molecules also increases, increasing the diffusion rate of dye into the fiber interior, accelerating the dyeing rate until the dye is completely absorbed and completed.
The high-temperature and high-pressure dyeing method of dispersed dyes is an important approach, suitable for low-temperature dye varieties with low sublimation fastness and small molecular weight. This type of dye has good dyeing uniformity, bright color, good hand feel, high fabric transparency, suitable for small batch and multi variety production, and is commonly used for dyeing polyester cotton blended fabrics.
The high-temperature and high-pressure dyeing of dispersed dyes can be carried out on high-temperature and high-pressure roll dyeing machines, jet and overflow dyeing machines, suitable for dyeing deep and concentrated colors. The pH value of dyeing is generally controlled at 5-6, and acetic acid and ammonium dihydrogen phosphate are commonly used to adjust the pH value. To maintain the stability of the dyeing bath, dispersants and high-temperature leveling agents need to be added during dyeing.
Example of overflow dyeing machine dyeing process:
Dyeing prescription:
Disperse dye X
High temperature leveling agent 0.2-1.2g/L
Diffuser O 0.5-1g/L
Acetic acid (98%) 0.5-1.5g/L
Restoration cleaning
caustic soda
Caustic soda (360Be) 6ml/L
Insurance powder
Insurance powder 2.5g/L
Dispersant 0.1-0.5g/L
technological process:
Fabric sewing head → pre-treatment → dyeing → reduction cleaning → hot water washing → water washing → dehydration → setting.
Generally, it can be dyed at 50-60 ℃, gradually heated to 130 ℃ after about 1 hour, dyed for 1-2 hours, and then thoroughly washed with water. Reducing cleaning instead of soap washing when dyeing dark colors can maintain the bright color of the dyed product.
3. Hot melt dyeing method
Dispersed dyes are used to dye polyester/cotton fabrics using the hot melt method, which is similar to general dip dyeing. The fabric is first immersed in a dip dyeing solution and then dried, followed by hot melt treatment. At a high temperature of 200 ℃, the dye deposited on the fabric can diffuse into the fibers in a single-molecule form, completing the dyeing of polyester in a very short time. If it is a polyester cotton blend fabric, the dye attached to the cotton can be transferred to the polyester by gas phase or contact through hot melt treatment. Hot melt dyeing is currently the main method for dyeing polyester cotton blended fabrics, mainly using continuous pad dyeing production, with high production efficiency, especially suitable for large-scale production. The disadvantage of hot melt dyeing method is that the equipment occupies a large area, and there are certain limitations on the use of dyes, resulting in a lower utilization rate of dyes compared to high-temperature and high-pressure methods.
The example of hot melt dyeing process is as follows (45 × 45 count, light blue, 65/35 polyester/cotton fine textile):
(1) Dyeing prescription
Disperse Blue 2BLN1.5g/L
Wetting agent JFC 1ml/L
Diffusion agent 1g/L
3% sodium alginate slurry 5-1Og/L
When in use, adjust the pH to 5-6 with acetic acid or ammonium dihydrogen phosphate.
(2) Process flow
Rolling dyeing
(Two immersion and two rolling, residual rate of 65%, room temperature) → pre drying (80-120 ℃) → hot melting (180-210 ℃, 2-1min) → cotton dyeing.
In high-temperature hot melt dyeing, attention should be paid to preventing dye migration during pre drying and baking. The hot melt baking stage is an important stage for the transfer of dispersed dyes from cotton to polyester. The appropriate hot melt temperature and time should be selected based on the heat resistance of the dye, namely its sublimation fastness. In actual dyeing, the transfer of dye cannot be complete. There is always a residual dye on cotton, which causes cotton staining. Restoration cleaning or soap washing can be used for post dyeing treatment. If cotton part needs to be counterstained after hot-melt dyeing, post-processing can be performed after counterstaining.