Dyeing and Finishing Process for Modal/Spandex Knits

1   Dyeing and finishing process

Blank Inspection → Slotting → Preformed → Buckle (Front Inward) → Scouring → Polishing → Dyeing → Soaping → Drying → Soft Finishing.

2   Dyeing and finishing conditions

2.1   Preform

In order to prevent the shrinkage of the pre-treatment moist heat conditions, reduce the generation of fine lines, setting temperature 195 °C, speed 15 ~ 20m/min.

2.2   Pre-processing

Modal fibers are finer than cotton fibers, and the fineness of 1.3 tex Modal fibers is equivalent to the fineness of 1. 7 to 1.8 dtex cotton. The cross-section of the fiber is uniform and circular, and there is no longitudinal three-dimensional curl similar to cotton fibers. With the increase in the number of yarn cross-sections and the smooth surface of the fiber, more fiber ends are released from the yarn during wet finishing and handling, resulting in the tendency of surface pilling and pilling. It is possible to maintain low tension and low speed to reduce friction, thereby reducing the occurrence of fluffing, pilling and hole formation. In the actual production process, the following points must be noted:

a The process must be completely dip dyed;

b. The front of the fabric is folded and buckled, so that the front surface of the fabric is processed inwardly to reduce the friction between the fabric surfaces;

c. Use a larger bath ratio as much as possible, according to the different fabrics, adjust the bath ratio of 1:10 to 1:12, while adding antistatic bath softener in the bath to reduce the mutual friction between the fabric;

d. In the process of bleaching, dyeing and finishing, the fabric maintains a gentle movement state, controls the temperature, avoids the phenomenon of waterfall boiling, and controls the speed of the dyeing machine.

2.2.1 cooking and bleaching process

Modal, spandex fiber Knitted Fabric generally do not need to bleach, as long as a slight scouring, remove the spinning and weaving process on the oil and wax can be. If the products used for dyeing bright colors or modal and cotton blends are mostly bleached, in order to save energy and reduce production costs, a one-bath process of boiling and bleaching is used. The bleaching process should be based on the composition of the fabric.

Boil and float a bath process:

Multifunctional pre-treatment agent JINSCOUR® EX 2g/L

Softener in antistatic bath JINSOFT® 3988 1～1.5g/L

50%H202 3～5g/L

NaOH 2～3g/L

pH 10.5～11

Bath ratio 1:15

Temperature 85～90°C

45~60min

The craft curve is shown as in Fig. 1:

Figure 1 cooking and bleaching process curve

2.2.2 scouring process

If the Modal/Spandex knit fabric is dyed in dim colors, the pre-treatment does not require a high degree of whiteness on the fabric. Simply scouring it to remove the spinning oil and wax.

Ordinary scouring process:

Multifunctional pre-treatment agent JINSCOUR® EX 2g/L

Bath ratio 1:10

Temperature 85～90°C

Time 20～30min

The main ingredient of JINSCOUR®EX, a multifunctional pre-treatment agent, is a nano-dispersion-surfactant formulation with a white viscous nonionic/anionic ion structure with a pH of 7-8. The product has a unique degreasing and washing ability and fiber protection, low foaming, without APE0. The scouring with the multifunctional pre-treatment agent eliminates the need for alkalis and avoids damage to fiber strength due to alkali scouring.

Anti-static bath softener JINSOFT® 3988 is a polymer, transparent mucus, non-ionic structure, neutral, can give good lubrication between fiber and fiber, fiber and mechanical parts, can effectively prevent the fabric in the dyeing and finishing process The scratches, creases, and foams produced during the process are compatible with other additives and are easy to clean.

2.2.3 Polishing

The modal fiber structure determines the hairiness on the surface of the fabric, and the prolonged wet heat treatment makes it easier to expose the end of the fiber yarn, and it is easy to play a ball during the course of taking. The polishing process uses cellulase to remove fluff from the surface of the fabric, so that the surface of the fabric is smooth and smooth, thereby reducing the phenomenon of pilling. The polishing treatment can be performed before and after the dyeing.

Treatment process:

Polishing enzyme BPF 0.6% to 1.0%

HAc adjusts pH to 5-6

Temperature 50～55°C

Bath ratio 1:10

Time 30～40min

The process curve is shown in Figure 2.

Figure 2 polishing process curve

Modal/spandex fiber knitted fabrics have excellent whiteness and mascara effect after being processed by the above processes, and the fibers are well protected, creases are not generated, pilling is not easy, and the style of the product is ensured.

2.3   dyeing

Modal fiber is a kind of cellulose fiber, so it has similar dyeing performance with viscose fiber and cotton fiber. It can be dyed with reactive dyes and direct dyes. However, due to the particularity of modal fibers, it is sensitive to dye auxiliaries, and has a strong affinity for reactive dyes. It has a high initial dyeing rate and a short half-dyeing time. Once the dye is dyed, it is not easy to be transposed, and it is easy to produce colored flowers and Spots. Therefore, pay attention to the following points in the dyeing and finishing process:

a. Choose dyes with good reproducibility, compatibility, and levelness, and with moderate directness to modal fibers (Dymax's Raymarine dyes are optional);

b. Dye, Yuan Mingfen, soda ash to be added in batches, adopt the process curve shown in Figure 3;

C. Yuan Ming powder is easy to agglomerate, so Yuan Mingfen, soda ash should be slowly added to the dye solution to prevent uneven distribution on the fabric;

d. Pay attention to the change of water hardness, if the hardness does not meet the requirements, softener should be added;

e. Detect the pH value of the dyeing solution when the reactive dyeing is in the range of 10.8 to 11.2;

f After the fabric has been boiled and bleached, it is generally necessary to use oxygen scavenging enzymes to remove residual hydrogen peroxide, otherwise it will easily cause color flowers;

g. For deep dyed fabrics, they need to be fixed after re-soaping.

Modal fiber dyeing process prescription:

Dye x%

Leveling agent for cotton JINLEVEL®   CD 0.5 ~ 1.0g/L

Antistatic Bath Softener JINSOFT®   3988 1~1.5g/L

Yuan Mingfen 5～60g/L

Soda 5~20g/L

Bath ratio 1:10 to 1:12

Fig. 3 Dyeing process curve

The levelling agent for cotton JINLEVEL®CD is a special nonionic/anionic surfactant compound with excellent wetting, dispersing, slow dyeing, alkali resistance, salt resistance, hard water resistance, low foaming, and can increase dyes. The solubility, effectively prevent color points, color blemishes and so on. Modal fabrics are dyed by the above process, obtaining uniform color, bright color, no creases on the fabric, less hair, soft and smooth.

2.4   Soft finish

The finishing of the fabric is critical, and the quality of the product depends largely on the quality of the finishing. Modal fibers have a uniform circular cross-section, and the cohesion between the fibers is worse than that of cotton fibers. If the conventional aminosilicone oil smoothing agent is used for finishing, the cohesive force of the yarn is often reduced more or less to make the fabric surface. More pilling and pilling. Therefore, the softness of the process and the softener will determine the feel of the fabric and the style of the product. The biggest drawback of modal fabrics is pilling, which has a certain relationship with static electricity. Therefore, antistatic agent and anti-pilling ball agent can be added in the finishing process for composite finishing. Modal and Spandex fabrics have a rich and soft touch, good drape and luster, and in order to further improve the grade of the products and give the fabric a soft and smooth feel, after many tests, the following soft formula can be used to make the fabrics have a good The hydrophilicity at the same time to get a special feeling of cool shots, and has a sense of body.

Soft process:

Imitation silk fabric finishing agent JINSOFT® WNS 40g/L

Anti-pilling finishing agent JINSOFT® 6750 40g/L

Setting temperature 160～175°C

Overfeed 20% to 25%

Speed ​​15 to 20 m/min

3   in conclusion

Modal fiber is a kind of regenerated cellulose fiber, which not only has the characteristics of natural fiber, but also has the characteristics of some synthetic fibers. It is non-toxic, non-polluting and degradable. It is a kind of green environment-friendly fiber and has its unique performance. The modal fabric after the addition of spandex is prone to scratches, creases, unstable width, poor quality, easy hairiness on the fabric surface, and easy pilling. Choosing the right process is the key.

a. Modal and spandex fibers after scouring by the multi-functional pretreatment agent JINSCOUR@EX have less damage to the fiber, and the fabric surface is not easy to pill and pill, and can maintain the original characteristics of the fiber, avoiding damage to the modal fiber caused by strong alkali pretreatment.

b. Anti-static bath softener JINSOFT@3988 is added to the pre-treatment and dyeing to prevent the fabric from scratching, hooking, creases, and uneven dyeing throughout the entire process.

c. During the dyeing process, the cotton leveler JINLEVEL@CD was added to evenly disperse the dye. After dyeing, the fabric was uniform in color and bright in color.

d. In the softening process, the imitated silk fabric finishing agent JINSOFT@WNS is used to further obtain a good hydrophilicity, fullness, softness, smoothness and handfeel of the fabric, and it has antistatic function and improves the taking performance of the product.

e. Strengthen the finishing, such as adding anti-pilling pilling agent, so that the performance of the fabric to be further improved.

  references:

(1) He Liqing, Kang Yuehong: "Dyeing and finishing production practice of Modal knitwear", Knitting Industry, 2006 (2), 37-38.

(2) Jialiang Liang: "Dyeing and Finishing of Modal Fabrics", Knitting Industry, 2003 (4), (56-59)

(3) Peng Zhizhong: "Dyeing and finishing of Modal/cotton stretch knitwear", printing and dyeing, 2007 (8), 16-17