Why mercerizing and singeing the yarn?

The market demand for pure cotton mercerized fabrics is getting stronger and stronger, and high-quality mercerized cotton knitted fabrics are in short supply in the market. However, some knitting enterprises often have defects such as color difference, color pattern, color profile and stripe pattern when producing this type of fabric, resulting in lower product quality and low price. To improve the quality of pure cotton mercerized knitted fabrics, it is necessary to control the production processes of singeing, mercerizing, dyeing, weaving and finishing.

1. Pure cotton yarn singeing

After textile processing, there will be a lot of fluff on the surface of the yarn, and the pure cotton mercerized fabric requires a smooth surface and clear texture, so the yarn should be singeed. The pure cotton yarn singeing adopts the gas singeing machine. When singeing, a single yarn is passed through the singeing machine burner to burn off the fluff on the surface of the pure cotton yarn. The flame temperature of singeing is usually 900-1000℃. After singeing the yarn, the weight per unit length is reduced and the count is increased. Therefore, the loss of singeing should be considered in the process design to ensure that the finished yarn count meets the design requirements.

2. Mercerizing process conditions
In order to improve the appearance quality of cotton yarn and improve the dyeing performance of the yarn, a concentrated alkali (NaOH) solution is generally used to mercerize the cotton yarn. The gloss of cotton yarn is improved after mercerization; the hygroscopicity is generally 20% to 30% higher than that of unmercerized yarn, and the dyeing depth is increased by 15% to 40% (depending on the depth of dyeing); the yarn structure is more compact; Increase by 10% to 20%. At present, the domestic mercerized cotton yarn production process is divided into dry yarn mercerization and wet yarn mercerization (that is, mercerized after cooking). Theoretically speaking, the mercerizing effect is better after cooking, but the moisture content of wet yarn mercerizing is difficult to control, which is easy to cause uneven mercerization; after drying, mercerizing, paraffin wax emulsion, although the technological process is elongated, the quality is easy to control. Therefore, the current cotton yarn for knitting is basically mercerized with dry yarn, that is, the original yarn is mercerized.