Polyester yarn

100% polyester round thick roving yarn for hand knitting

[textile dyeing and finishing technology] polyester cheese yarn is always dyed, how to break?

Cheese dyeing features: low loss, high quality, fast delivery and good benefit.

As an important dyeing method, cheese dyeing has been widely used in yarn dyeing and finishing plants. Its dyeing technology is relatively mature. However, the dyeing process of polyester cheese yarn is complex, and there are many influencing factors which are difficult to control. If there is a little negligence, it is easy to produce colored flowers. Thus, the problems of color repair, back dyeing, modified dyeing and re dyeing become very prominent, which not only brings about high cost, but also time-consuming, which affects the first-time success rate of dyeing and instant production. In order to improve the first-time success rate, reduce the product cost and shorten the product delivery period, it is necessary to control all factors in the polyester dyeing process.

Selection of loose bobbin tube and control of density

1 Selection of bobbins

Stainless steel spring tube is preferred for loosing cylinder, which has the advantages of large wall hole, which is conducive to the diffusion and penetration of dyes. However, due to the large expansion and contraction radiance of spring stainless steel tube, it is difficult to control the evenness of loose yarn in forming and density, and it is difficult to ensure the sealing property; it is easy to cause uneven pressure and leakage pressure in dyeing process and dye flowers. Therefore, the use of plastic cylindrical bobbin is beneficial to the control of yarn forming and the uniformity of density during yarn loosening, as well as the good sealing performance during dyeing.

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 easy to fall off; if the loose yarn density is too high, the dye solution is difficult to penetrate the yarn layer, which is easy to cause uneven dyeing. The appropriate density is 0.34 ~ 0.429/cm3.

Process improvement and dispersant renewal

1 pretreatment temperature

Due to the high content of oil and other oligomers in polyester fiber, the dyestuffs are easy to agglomerate, which is the direct cause of flower dyeing. Using warm water can achieve the effect of degreasing and impurity removal. We reduce the cooking temperature to 80 ℃ for 20min. Through the large cargo test and production tracking verification, we have received good results. Attention must be paid to cleaning after pretreatment, otherwise it is easy to cause dyeing defects.

3 reduction cleaning

Reducing cleaning can wash away the disperse dyes adsorbed on the yarn surface, ensure the color fastness, and remove other substances adsorbed on the yarn surface during the dyeing process, so as to reduce the stain.

4 dyeing temperature

Heating rate and holding time have important influence on dyeing of polyester yarn. When dyeing temperature is below 85 ℃, heating can be faster. It is necessary to strictly control the heating rate of 1 ℃ / min and 2 ℃ / min at 115-130 ℃. Due to the different properties of various dyes in the combination of disperse dyes, it is necessary to keep the temperature of the inner and outer layers of the yarn uniform for a period of time before dyeing with disperse dyes. In the subsequent heating process, there should also be sufficient time to make the temperature of the inner and outer layers of the yarn even. Therefore, in order to keep the temperature of the inner and outer layers of the yarn uniform, the temperature of all kinds of dyes can be evenly dyed. The dyeing process is as follows: add auxiliaries and dyes at room temperature, heat up to 85 ℃ at full speed, heat up to 110 ℃ at 2 ℃ / min after holding for 10 min, and then heat up to 120 ℃ at 1 ℃ / min for 20 min, and then heat up to 130 ℃ at 1.5 ℃ / min for 60 (or 30) min, and then cool down.

5. Selection of dyes

Dyes with small molecular weight and good dispersion should be selected as far as possible in high temperature and high pressure dyeing.

6 selection of dispersant

The slow dyeing and migration properties of dispersant directly affect the dyeing quality. Jh-rp60 is a leveling agent with high concentration and low foaming property for dyeing polyester or polyester / cotton blends. Uniform dyeing effect of inner and outer layers can be obtained. We selected two colors (50cvcbl3298; 70dpk4256) which are most likely to appear color difference between inner and outer layers in bulk production. After dyeing, there was no color difference and flower dyeing between inner and outer layers. The success rate was more than 98%. Moreover, all the material tests of the test object are up to the standard, which has no effect on the fastness.

Machine operation control

(1) The main pump stops stealthily: the operator should check the machine and the main pump frequently, and overhaul as soon as possible if there is any abnormality.

(2) The pressure is not normal (too large, too small).

(3) Unstable temperature: the operator should check the machine frequently, if the instrument is abnormal, it should be repaired as soon as possible.

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

(5) Low pump speed: the operator must check the pump speed after starting.

(6) Nonstandard feeding: operators must add materials according to regulations when feeding.

(7) Yarn hardness: contact the loose yarn preparation workshop to ensure the yarn hardness meets the requirements.

Level dyeing process of polyester yarn after flower dyeing

Through the test, we adopt the procedure of loosening the yarn and turning it over again before entering the VAT for level dyeing. After one level dyeing, the phenomenon of flower dyeing has been completely eliminated and the effect of complete leveling is achieved. The amount of repair agent is used according to the degree of fancy yarn, which is generally 2-3g / L. (if the color is too dark and needs to be lightened, the dosage can be increased appropriately). All the data confirm that our scheme is feasible, and the ideal effect is received. It improves the production quality of polyester yarn, reduces the number of repair cylinders of polyester yarn, improves the one-time OK rate of dyeing, and increases the dyeing output, which provides a strong guarantee for the production quality of polyester yarn.