1. Fibers with poor maturity of raw cotton have poorer strength and elasticity than mature fibers. They are easy to break and produce neps when stress is generated due to ginning and blowroom processing during production and processing.
A foreign textile research institute divided the proportions of different mature fibers in the raw materials into three groups, namely M1R=0.85, M2R=0.75, and M3R=0.65 for spinning tests. The test results and the number of neps in the spun yarn are listed in Table 1.
Table 1
The above table shows that the greater the proportion of immature fibers in raw cotton, the more the neps content in spun yarn increases.
Although no problems can be seen on the gray fabrics when woven with yarns spun from these three groups of raw cotton, after dyeing it was found that the white spots of the final product of raw cotton with a large content of immature fibers increased significantly compared with the fabric woven from raw cotton with a large content of mature fibers.
2. The fineness and maturity of raw cotton are generally expressed by the micronaire value. The better the maturity of the raw cotton, the higher the micronaire value. Different raw cotton varieties have different micronaire values.
High-maturity fine-staple raw cotton has good elasticity and high strength, and produces fewer neps during the spinning process. Low-maturity fibers have thick fibers, poor rigidity, and low single strength. Under the same impact conditions, It is easy to produce neps and short fibers.
For example, when the beater speed of blowroom cotton is 820 rpm, due to the different micronaire values of cotton fibers, the neps and linters produced are also different. However, if the beater speed is reduced accordingly, the situation will improve, see Table 2.
Table 2
The above table shows that: different fiber fineness and maturity, and different micronaire values, have different effects on the nep content of the yarn.
3. When selecting raw cotton and designing the blowroom and carding processes, in addition to length, impurity content, short lint and other indicators, special attention should be paid to the selection of the micronaire index of raw cotton, especially when producing and processing fine-staple cotton. When it comes to long-staple cotton, the micronaire value is more important. The range of micronaire value is generally 3.8-4.2. When blending cotton and designing spinning processes, attention should also be paid to the maturity of cotton fibers to ensure that sliver neps are reduced and the quality of spinning, weaving and dyeing is steadily improved.
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