Tips for printing and dyeing │Master four key factors to avoid dyeing polyester cheese yarn

The dyeing of bobbins, an important dyeing method, has been adopted by most yarn dyeing and finishing plants. The dyeing process technology has been relatively mature, but the dyeing process of polyester cheese yarn is complex, and there are many influencing factors and it is difficult to control. It is slightly negligible and can easily cause color flowers. As a result, the problems of color correction, dyeing, dyeing, and re-dyeing have become prominent. It is not only costly and time-consuming, but also affects one-time success rate and instant production of dyeing. As a result, the cost is high and the product cycle is prolonged. In order to increase the primary success rate, reduce the product cost, and shorten the product delivery cycle, all factors in the polyester dyeing process must be controlled (1–2).

1, the choice of loose bobbin tube and the control of the density

1.1 bobbin selection

The pine tube is the preferred stainless steel spring tube. The advantage is that the wall hole is large, which is conducive to the diffusion and penetration of the dye. However, due to the large elasticity of the spring stainless steel tube, the loose yarn is difficult to control evenly in forming and density, and the sealing performance is difficult. Guaranteed; easily cause uneven pressure and leak pressure in the dyeing process and dye flowers. Therefore, the use of a plastic cylindrical bobbin facilitates control of the formation of loose yarns and ensures uniform density, ensuring good sealing during dyeing.

1.2 Density control

Because the spring stainless steel tube is too smooth, if the loose yarn density is too small, the yarn on the bobbin appears loose, and it easily causes the yarn to fall off; if the loose yarn density is too high, the dye solution is difficult to penetrate the yarn layer, and uneven dyeing is easily caused. The density is preferably 0.34 to 0.429/cm3.

2, process improvement and dispersant update

2.1 Pretreatment temperature

As the polyester filament contains more oil and other oligomers, it is easy to make the dye condense, which is the direct cause of dyeing. Using warm water can achieve the effect of removing oil and removing impurities. We will reduce the temperature of boiled yarn to 80°C for 20 minutes, and we have achieved good results through large cargo testing and production tracking verification. It must be noted that after the pre-treatment must be cleaned, otherwise it is easy to cause disease.

2.2 pH

It is best to control the bath pH to 4.5-5.

2.3 restore cleaning

Reduction washing can wash off the disperse dyes adsorbed on the surface of the yarn, ensure the fastness of dyeing, remove other substances adsorbed on the surface of the yarn during the dyeing process, and reduce the stain.

2.4 dyeing temperature

The heating rate and holding time have a crucial influence on the dyeing of polyester yarn. When the dyeing temperature is below 85°C, the temperature rise can be faster. 85 ~ 110 °C is the fastest increase in the speed of dyeing, the need to strictly control the heating rate of 1 °C / min, 115 ~ 130 °C can be controlled at about 2 °C / min. Due to the differences in the properties of various dyes in disperse dye combinations, the disperse dyes should be incubated for a period of time before they are dyed so that the temperature inside and outside the yarns is uniform and there should be sufficient time during the subsequent heating process. Allows uniform temperature inside and outside the yarn. Therefore, in the experiment, we used a stepwise temperature-raising method and a balanced temperature raising method so that the temperature inside and outside the yarn can always be maintained evenly and various dyes can be uniformly dyed. The dyeing process is as follows: add additives and dyes at room temperature, heat up to 85°C at full speed, keep warm for 10 minutes, raise the temperature to 110°C at 2°C/min, heat for 15 minutes, warm to 120°C at 1°C/min, heat and dye for 20 minutes, The temperature was further increased by 1.5°C/min to 130°C, and the temperature was lowered by 60 (or 30) minutes.

2.5 The choice of dye

High-temperature and high-pressure dyeing should use dyes with small molecular weight and excellent dispersibility.

2.6 Selection of dispersants

Slow dyeing and dyeing properties of dispersants directly affect the dyeing quality. JH-RP60 is a high-concentration, low-foaming leveling agent for dyeing polyester or polyester/cotton blends. Can be uniform inner and outer dyeing effect. We selected two colors (50CVCBL3298; 70DPK4256) that are most susceptible to dyeing and the color difference between inner and outer layers in the production of large goods. After dyeing, there was no color difference and dyeing phenomenon inside and outside, and the success rate was over 98%. And all the test objects' physical measurements are in compliance with the standard, which has no effect on the fastness.

3, machine operation control

(1) The main pump is stolen: The operator must diligently inspect the machine platform and the main pump and find that there is abnormality as soon as possible.

(2) The pressure is abnormal (larger, smaller).

(3) The temperature is not stable: The operator checks the machine and finds that the meter is not normal. It should be repaired as soon as possible.

(4) Leakage pressure: The operator must check the tightness by pressing the locking head (locking the warp shaft cover) before starting the machine.

(5) Pump speed is low: After the operator turns on, be sure to check the pump speed.

(6) The feeding is not standardized: The operator must add materials according to the regulations when feeding.

(7) Hardness of the yarn: Contact the loose yarn and prepare the workshop to ensure that the hardness of the yarn meets the requirements.

4, polyester yarn dyed after dyeing process

After the experiment, we adopted the first loose yarn to overturn the flower yarn and then enter the cylinder for the level dyeing procedure. After a level dyeing, the dyeing phenomenon has been completely eliminated to achieve the complete leveling effect. The amount of repair agent used is based on the degree of flower yarn, generally 2 ~ 3g/L. (If the color is too dark, you may increase the amount if you need to reduce it.) The data confirms that our solution is feasible and has received ideal results. It has improved the production quality of polyester yarns, reduced the number of cylinders for polyester yarn rework, improved the one-time OK rate of dyeing, and also improved the dyeing yield for polyester. Yarn production quality provides a strong guarantee.

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