Dyeing uniformity guarantee of Colored Fancy Polyester Yarn: Dye selection and process optimization

1. Dye selection: foundation and key
Polyester yarn itself has no reactive groups, and its dyeing conditions are relatively harsh. At high temperatures, the molecular chains of polyester fibers move, and the internal space of the fibers increases, allowing tiny dye particles to enter the fibers and bind and fix in the form of covalent bonds. In this process, disperse dyes are the first choice for dyeing polyester yarns due to their good dispersibility and permeability.

Selection principles of disperse dyes:

High fastness: Select disperse dyes with high fastness to ensure that the dyed polyester yarn is not easy to fade during use.

High affinity: The dye has a strong affinity for polyester fibers to ensure that the dye can evenly penetrate into the fibers.

Good lifting power: Good lifting power means that the dye can achieve the ideal dyeing effect at a lower concentration, which helps to reduce the amount of dye and reduce production costs.

Avoid color flower and color spot problems:

Some disperse dyes, especially bright blue dyes with large molecular structures, poor solubility, and poor migration, are prone to color flower and color spot problems. When choosing dyes, try to avoid using such dyes, or improve their dyeing uniformity by adding leveling agents, adjusting dyeing processes, etc.

2. Dyeing process optimization: details determine success or failure
After selecting the right dye, the optimization of the dyeing process is also crucial. The following are some key process optimization measures:
Pretreatment process:
Refining and degreasing: Polyester yarn needs to be refined and degreased before dyeing to remove oil and impurities on the surface. The degreasing process should be uniform to avoid oil stains from returning and affecting dyeing uniformity.
Degreasing and dyeing in the same bath process: For pure polyester knitted fabrics, degreasing and dyeing in the same bath process can be used. This process can ensure that degreasing and dyeing are carried out at the same time, thereby improving dyeing uniformity and production efficiency.
Dyeing condition control:
Temperature: Colored Fancy Polyester Yarn dyeing needs to be carried out at high temperature, usually around 130°C. The temperature control should be precise to avoid excessively high or low temperatures that lead to uneven dyeing.
Time: The dyeing time should be long enough to ensure that the dye can fully penetrate into the fiber. It is also necessary to avoid dyeing for too long to avoid excessive hydrolysis of the dye or fiber damage.
Bath ratio: The choice of bath ratio should be determined according to the nature of the dye and the capacity of the dyeing equipment. The appropriate bath ratio helps to improve the dispersibility and permeability of the dye, thereby improving the uniformity of dyeing.
Use of leveling agent:
Adding an appropriate amount of leveling agent, such as polyester leveling agent DPA, during the dyeing process can significantly improve the dispersibility and permeability of the dye, thereby improving the uniformity of dyeing. The choice of leveling agent should be determined according to the nature of the dye and the dyeing process, and avoid using leveling agents that are incompatible with the dye or fiber.
Equipment factors:
The selection of dyeing and finishing equipment is equally important for dyeing uniformity. The equipment should have strong process adaptability and be able to meet the requirements of uniformity for process parameters such as equipment temperature, pressure, speed, and processing time. The degree of automation of the equipment should also be high to reduce the problem of uneven dyeing caused by human factors.
Post-processing process:
Reduction cleaning after dyeing helps to remove floating colors and unfixed dyes, and improve dyeing fastness and uniformity. During the cleaning process, attention should be paid to controlling the amount of detergent and the cleaning temperature to avoid damage to the fiber.

3. Quality control and testing
During the dyeing process, quality control and testing should not be ignored. By testing the quality of the dyed polyester yarn, including indicators such as dyeing uniformity and color fastness, problems in the dyeing process can be discovered and solved in a timely manner. Establishing a strict quality control system to monitor and manage key links such as dyes, auxiliaries, and equipment is also an important measure to ensure dyeing uniformity.