Physical quality index of cotton yarn
The physical quality indicators of cotton yarn are the first quality information we need to understand when discussing trade. Different enterprises may have different projects, but they mainly focus on quality indicators such as cotton yarn count, twist, blending ratio, and strength. Attention should be paid to the following aspects of quality.
1. Cotton yarn count
Cotton yarn count is the main technical index that affects the thickness density (weight per unit area) of knitted fabrics, and it affects other properties of knitted fabrics. Several issues related to cotton yarn count deserve attention:
1) The conversion constant between the number of numbers and the number of branches should be clear
The number and count are two commonly used indicators to indicate the thickness of cotton yarn. The number is commonly used in spinning mills, while the count is commonly used in knitted fabric factories. The cotton yarn count and count can be converted based on the corresponding conversion constant. Generally, 583.1 is used for cotton, 590.5 is used for chemical fiber, and different proportion varieties can be calculated based on the blending ratio, such as 586 for C/T60/40, and 588 for T/C65/35. In actual trade, users generally use the number of pieces to express, and it is also recommended to use the number of pieces for packaging writing. Due to different customer usage habits of constants and significant differences in the number of pieces or numbers calculated, it is necessary to communicate with the customer in advance for confirmation on the conversion of constants to avoid unnecessary disputes due to differences in calculation.
Twist of cotton yarn
Twist size is the main factor that distinguishes between knitted and woven yarns. Knitting yarn twist is generally required to be controlled slightly to meet the soft hand feel requirements of knitted fabrics, and to facilitate smooth weaving. If the yarn twist is too large, not only does the fabric feel slightly hard, but also the yarn is prone to kink and form braided yarn during the unwinding process of weaving bobbins, resulting in broken ends, downtime, or fabric defects. According to experience, the twist coefficient control range for ordinary ring spun flat knitting yarns is around 360 for pure cotton varieties and around 350 for cotton and chemical fiber blended varieties. According to different fiber compositions, spinning methods, and cotton yarn uses, there are different requirements for twist.
Example 1: For special varieties such as slubby yarn, considering the strength of the yarn, the twist coefficient is generally 30 to 50 higher than that of plain yarn. However, excessive twist can easily lead to small braid yarns, and affect the slope and twist of the fabric surface. Especially for knitted yarns, higher requirements are required in this regard.
Example 2: For pile yarns, such as 10 count T/C65/35 pile yarns, there are also certain requirements for twist. If the twist factor is greater than 330, it is not easy to pile, resulting in high yarn hardness, difficulty in cutting pile, and the phenomenon that the loops are twisted and cannot be cut. If the twist is too small, production difficulties may occur. The twist coefficient of 10 CVC60/40 should not be greater than 340. In addition, for coarse count yarns such as TC10 or CVC10, weak twist yarns are prone to occur during spinning production. Sometimes the entire spinning yarn is weak twisted, and sometimes there are normal sections of weak twist, resulting in a shiny fabric surface; Or during weaving, due to the small twist scraping of the weaving channel, large cotton particles and coarse knots occur, resulting in downtime or fabric surface holes. The main reason for this is the high spinning tension of 10 yarns. If the spindle belt tension is insufficient, the spindle rotation speed is insufficient. Especially in the rising stage of large yarns. In addition, factors such as low twist of 10 counts of fleece yarn, high number of flying flowers in the spinning yarn, flying flowers hanging on the spindle belt, and easy winding back affect the spindle rotation speed to produce weak twist.
Spinning method problems
Currently, our spinning methods for ring spun yarns include general ring spinning, compact spinning, siro spinning, compact siro spinning, and so on. Knitting yarn has different requirements for spinning methods for different types of fabrics and fabrics. The following situations require special attention.
1. For general ring spinning, due to the soft feel and loose and thick texture of the cloth after weaving, underwear and some fabrics that require softness are very popular with consumers, making them the mainstream yarn for knitting. However, the hairiness and evenness of cotton yarn are slightly worse than those of other yarns.
2. For compact spinning and compact siro spinning, due to the characteristics of less hairiness and high strength of the yarn, some cloth types with special requirements, such as cloth with high smoothness requirements for the cloth surface, are more popular with users. However, this kind of yarn also has certain disadvantages, namely, the hand feel of the cloth after weaving is relatively hard, and even has a little prickly flesh. In addition, because the yarn is relatively tight and the diameter of the yarn is relatively small, the fabric after weaving has a relatively thin feel and a strong bone feeling, which is not suitable for underwear fabrics.
