Denim is a thicker yarn-dyed warp twill. The warp yarn is dark in color, generally indigo blue, and the weft yarn is light in color, generally light gray or white yarn after scouring. Also known as indigo labor cloth. In the denim market, although cotton is undoubtedly the most important, there are also a series of blended fabrics, such as cotton/polyester (50/50) blended fabrics, and cotton and other fibers such as Tencel, linen, and even jute, Wool yarns are woven together. Compared with the yarns of general fabrics, denim yarns have certain special characteristics, so the requirements for the original yarns are also different. Mainly manifested in:
1. The warp yarn has higher breaking strength and elongation
The warp yarn has a long process flow and is often subjected to repeated bending and elongation, and the machine tension is relatively high during weaving. Therefore, warp yarns have higher requirements for yarn breaking strength and elongation.
2. Good maturity, level dyeing and permeability of raw cotton
Indigo dyes have poor dyeing properties and poor color fastness to rubbing. Cotton yarns spun from cotton with poor maturity can easily cause uneven dyeing, resulting in stains, white spots, and other defects. Therefore, the content of dead petals, dead cotton, and neps in cotton yarn should be reduced as much as possible.
3. Fewer yarn hairiness
The amount of yarn hairiness directly affects the quality of the subsequent products. The hairiness and sizing process and the warping process are difficult to divide, and the end breaks increase. At the same time, it will also cause the dye liquor to become turbid and thick, and even the pipeline is blocked.
4. Less yarn defects such as evenness and slub
For general denim, the yarn requires less yarn defects such as evenness and slub, otherwise it will affect the appearance and color of the cloth surface and increase the rate of breakage in production.
5. Large winding capacity
Generally, the denim yarn count is low, and the winding capacity of the single cone yarn should be increased as much as possible to reduce the knots on the cloth surface, which is more obvious when weaving on a shuttleless loom.
6. The yarn fineness is correct, the weight deviation and weight unevenness are small
Denim yarn still needs to ensure that the yarn fineness, weight deviation, and weight unevenness are within a reasonable range, otherwise it will directly affect the control of the weight per square meter.