The percentage of immature fibers in cotton generally occupies more than 50% of the short-staple rate, and more than 50% of the floating fibers in the spinning process are caused by immature fibers. A large number of neps and white stars are caused by As a result of the changes in the movement trajectory of the immature fiber in the fiber bundle, a large number of uneven dyeing and horizontal stripe defects will appear in cotton yarn dyeing and cotton dyeing, resulting in a large number of defective yarns and defective fabrics, resulting in a lot of waste. Therefore, analyzing the percentage of immature fibers, the percentage of immature fibers in cotton generally accounts for more than 50% of the short-staple rate. In the spinning process, more than 50% of the floating fibers are caused by immature fibers. Knots and white stars are both the result of changes in the trajectory of immature fibers in the fiber bundle. A large number of uneven dyeing and horizontal defects will occur in cotton yarn dyeing and cotton dyeing, resulting in a large number of defective yarns and fabrics. , Causing a lot of waste. Therefore, analyzing the change of the percentage of immature fiber is helpful to the cotton yarn quality positioning of the spinning mill. On the one hand, it can reduce production costs, and on the other hand, it can rationally use cotton of different quality.
One-The influence of raw cotton on yarn quality
According to the long-term experience of using American cotton in large quantities, the number of cotton yarn defects produced by machine-picked cotton is large, especially the cotton yarn has many neps and stubby knots, and these defects are difficult to remove during the spinning process. Sometimes even if the spinning is increased The production cost of yarn and the neps of cotton yarn have not been significantly improved. This has always been a very difficult problem for machine-picked cotton for high-quality, less neps spinning. Production practice shows that the +200% neps of cotton yarn produced by machine-picking cotton are 10-40% more than the +200% neps produced by manually picking cotton. Most of these neps are used in the weaving of the subsequent process. It is expressed in the form of cotton balls. In terms of +140% of neps, the cotton yarn produced by machine-picked cotton is 10%-60% more than the cotton yarn produced by hand-picked cotton. At the same time, the hairiness of cotton yarn produced by machine-picked cotton is also higher than that of manually picked cotton. 20-50% more hairiness.
Especially long hairiness is even more obvious. High-quality dyed knitted fabrics are very afraid of such hairiness and neps. That is to say, the need for high-quality knitted fabrics for cotton yarn is best not to use machine-picked cotton spinning. yarn. Because the fiber of this kind of cotton yarn has the phenomenon of mixing cotton with good maturity and poor maturity, there are differences between the fiber with good maturity and the fiber with poor maturity in cotton yarn.
The fabric is not uniform, and it is generally forbidden to use dark and light-colored fabrics of knitted fabrics, otherwise the knitted fabrics are prone to horizontal stripes, hair particles, hair balls and white stars. The best use of this type of cotton yarn is on knitted fabrics, woven fabrics, white cloth, and bleached cloth, because the number of foreign fibers in this type of cotton yarn is very small.
In recent years, due to the continuous renewal of ginning technology, people in order to chase the reduction of cotton impurities and the whiteness of cotton, and improve the grade in order to improve the economic benefits, thus producing the skin cleaning of cotton. According to production practice, information review, and peer exchanges, although the function of the skin cleaner can remove some impurities and make the cotton beautiful, it seriously damages the cotton fiber, increases the rate of lint, and also increases the number of fine impurities. At the same time, it makes the raw cotton more difficult in the spinning process. Not only is there a lot of neps, but also the fine impurities are difficult to eliminate to the ideal state no matter how the process parameters are changed during the cleaning process, which leads to an increase in the number of fine impurities in the yarn and gives the fabric style Have a negative impact. At present, my country uses machine-picked cotton in Xinjiang (the sixth agricultural division). Compared with manual cotton-picked cotton, cotton leaves and cotton stalks have more impurities but also a lot of foreign fibers.
Xinjiang cotton foreign fiber is 0.8 g/ton. Proceeding from the actual production, it is best not to use these machines for cotton picking and percutaneous cleaning.
After the processing of machine-picked cotton, there is a certain quality gap between the quality of cotton and the quality of manually-picked cotton, which is mainly manifested in the short length of cotton, poor maturity consistency, poor neatness, and short pile rate High, high nep, large number of small defects, many fiber-bearing seed chips, and poor color consistency of cotton. In the spinning process of machine-picked cotton, due to the influence of the large number of small defects in the cotton, the large number of fiber seeds and the defects contained in the fiber, the blowing-carding process can open, remove impurities, remove short lint, and comb the cotton. Obviously restricted.
Two-Requirements of different yarns on the quality of raw cotton
According to the customer's quality requirements of our company, after production practice, data inspection and peer exchanges, the following conclusions are drawn:
1. The content of foreign fibers used in bleaching blanks should be emphatically considered. The content of foreign fibers in cotton varies in different countries, regions, production areas, and different picking and processing methods. In terms of countries and regions, the cotton of the United States, Australia, and some Uzbekistan has the least amount of foreign fibers.
2 At present, our company's domestic cotton is almost made of dyed knitting cotton yarn, so it is best not to use machine-picked cotton and cotton that has been cleaned.
3. For inland cotton, the micronaire value of early and mid-term cotton in some areas is higher than 4.8, while the micronaire value of late and mid-term cotton is generally below 4.5 and the neps are around 300. Although the micronaire is at 4.5, the physical indicators are poor due to factors such as climate and variety. The content of foreign fiber is generally high (mainly polypropylene fiber), which has a greater impact on the coloring of the cloth and the electric cleaning and shearing. In the processing process, almost all pass through the skin cleaning machine, although the impurity content is small and bright , The grade is higher, but the number of neps, short linters, fine foreign fibers, and fine impurities also increase, which has a negative impact on the process of producing cotton yarn.
4. You can use some cotton with a lower color grade and better internal physical indicators, and the relative cost will be lower. For example, the last time I purchased several batches of cotton from Yancheng, Jiangsu, although the color grade was low, the intrinsic physical index was good, the SCI value was high, and the utilization value was also high.
5. Early and mid-term cotton in northern Jiangsu has better physical indicators (without lint-clean cotton), and a higher moisture regain, some of which are above 10.0 in almost every batch, which brings inconvenience to cotton storage.
