Talking about the relationship between raw cotton and yarn quality

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According to the customer's multiple feedbacks and complaints, the author has analyzed and concluded that the customer's reaction to cotton neps and dead cotton is mostly, most of them are not cotton neps but dead cotton (white stars) immature fiber, not colored . The percentage of immature fiber in cotton generally accounts for more than 50% of the short-staple rate. More than 50% of the floating fiber in the spinning process is caused by immature fibers. A large amount of neps and white stars are produced. As a result of the change of the trajectory of the immature fibers in the fiber bundle, a large amount of uneven dyeing and horizontal strips appear in the cotton dyeing and cotton dyeing, resulting in a large amount of crepe and crepe, resulting in a large amount of waste. Therefore, analyzing the change of the percentage of immature fiber is helpful for the quality positioning of cotton yarn in the spinning mill. On the one hand, it can reduce the production cost, on the other hand, it can reasonably use different quality cotton.

First, the influence of raw cotton on the quality of yarn

According to the long-term experience of using a large amount of cotton in the United States, the cotton picked by the machine produces a large number of cotton yarn defects, especially the cotton neps, short and thick sections, and these defects are difficult to remove during the spinning process, sometimes even if the spinning is increased The production cost of the yarn and the neps of the cotton yarn have not been significantly improved, which has always been a difficult problem for the machine to pick cotton for high quality, less neps spinning. Production practice shows that the +200% neps of cotton yarn produced by machine picking cotton is 10-40% more than the +200% neps produced by hand-picked cotton. Most of these kinds of neps are used in the post-process weaving. The form of cotton balls is expressed. In terms of the number of neps of +140%, the cotton yarn produced by the machine picking cotton is 10%-60% more than the cotton yarn produced by the manual picking cotton. At the same time, the hairiness of the cotton yarn produced by the machine picking cotton is also higher than that of the cotton yarn produced by the manual picking cotton. Mao Yu is 20-50% more. Especially the long hairiness is more obvious. High-quality dyed knitwear is very scary for such hairiness and neps. That is to say, the high-quality knitwear needs cotton yarn without machine-picked cotton spinning. yarn.

Due to the cotton blending phenomenon in the fibers of such cotton yarns, the maturity of the fibers and the poor maturity of the fibers are unevenly distributed, and the dark color and light color of the knitted fabric are uneven. Fabrics are generally forbidden, otherwise knitted fabrics are prone to horizontal bars and hair, hair balls and white stars. The best use of this type of cotton yarn is on the white cloth of the knitted fabric, the woven fabric, and the bleached cloth because the amount of the foreign fibers of the cotton yarn is extremely small. In recent years, due to the continuous updating of ginning technology, in order to chase the reduction of cotton impurities and the whiteness of cotton, the level is raised to improve economic benefits, thus producing a skin clearing of cotton. According to the production practice, access to information, peer exchange, the role of the skin cleaning machine can remove some impurities and make the cotton bright, but it seriously damages the cotton fiber, increases the rate of the short pile, and also increases the number of small mixed plasmids. At the same time, the raw cotton is more difficult in the spinning process, not only the number of neps, but also the small impurities in the process of cleaning, no matter how the process parameters are changed, it is difficult to eliminate the ideal state, resulting in an increase in the number of fine impurities in the yarn, giving the style of the fabric. Have a negative impact. At present, China adopts machine-made cotton in Xinjiang (this time the six divisions of the farmer). Compared with artificial cotton-collecting cotton, cotton leaves and cotton rods have many impurities, but there are also many foreign fibers. According to the current machine, Xinjiang cotton is collected. The foreign fiber is at 0.8 g/ton. From the actual production, it is best not to use these machines for cotton and percutaneous cleaning.

After processing the cotton harvested by the machine, there is a certain quality difference between the quality of the cotton and the quality of the manually harvested cotton. The main reason is that the length of the cotton is short, the consistency of the maturity is poor, the uniformity is poor, and the short pile rate High, high cotton knots, large number of small defects, more fiber chips, and poor color consistency of cotton. In the spinning process, the cotton picked by the machine is affected by the number of small defects in the cotton, the number of fibrous seeds and the defects in the fibers, and the process of cleaning and combing the cotton to open, remove, remove, and comb the cotton. Subject to significant restrictions. The effect of the cotton picked by the machine on the pre-spun semi-finished products in spinning is very serious. Due to the serious damage of the small defects and the fibrous seed chips in the spinning process, the spinning process will be more and more expensive, and the cost will increase sharply. This problem exists in many manufacturers at present. Moreover, the quality of the card sliver and the quality of the combed strip in the main process of the pre-spinning are inferior to the quality of the card sliver produced by the hand-picked cotton and the quality of the combed strip, especially the card sliver produced by the machine-picked cotton. The sliver of the sliver has a high rate of cotton knots, fiber seed chips and short piles.

Due to the influence of climate and soil quality, the early and middle stage cotton in southern Xinjiang has a large micronaire value, coarse fiber diameter, more heterogeneous fibers, higher sugar content, lower fiber strength and neps impurities. less. Compared with foreign cotton such as American cotton, its impurity content is low, the short pile rate is relatively small, the length is long, and the uniformity is moderate. Due to the variety of varieties and geographical environment, yellowness and gray scale have no comparative value, so southern Xinjiang fine cotton (preferably artificially picked and not peeled) meets the requirements of lower spinning strength and less neps. yarn. Compared with southern Xinjiang fine cotton, Northern Xinjiang fine cotton has moderate fiber fineness, long length, good uniformity, low lint rate, slightly higher strength, good elasticity, strong color consistency and high comprehensive strength. . Compared with American cotton fine-staple cotton, the strength is lower, but the impurity content is less than that of American cotton, and the color is better than that of American cotton. It is suitable for spinning high-grade woven yarn.

At present, in southern Xinjiang or northern Xinjiang, most of them go through the skin cleaning machine, and the cotton is peeled off, so that the cottonseed epidermis falls off and is attached to the cotton fiber, which causes the fine impurities generated by the skin cleaning machine to be difficult to be in the spinning process. It is removed, which affects the appearance quality of the cotton yarn (the surface of the cheese yarn exhibits more impurities) and the intrinsic quality (the Uster instrument test shows more neps and more small impurities). Xinjiang fine cotton has a wide range of physical indicators in the early, middle and late stages, and is in the Uster 5%, 25%, 50% or even outside, and there is no strict implementation of the distinction, bringing the post-process spinning Seriously difficult. Therefore, the main physical indicators (except for strength) in the early and middle stages of Xinjiang cotton are within 5% and 25% of Uster, and some indicators are even better than Uster's 5% level, but some of the main physics of middle and late cotton. The indicator is seriously beyond the 50% level of Uster, which is why the range of physical indicators of Xinjiang cotton is large. The use of the leather cleaning machine to a certain extent causes the fiber length frequency distribution to be damaged, and the fiber uniformity is lowered, which seriously affects the spinning performance. From the perspective of cotton, it is best not to use such cotton.

Second, the requirements of different yarns on the quality of raw cotton

According to the customer's quality requirements for our company, after the production practice and data review and peer exchange, the following conclusions are drawn:

1. The content of heterogeneous fibers for bleaching blanks should be considered. The content of cotton heterogeneous fibers in different countries, different regions, different producing areas and different picking and processing methods is different. From the perspective of country and region, the United States, Australia, and some Uzbekistan cotton have the least amount of heterogeneous fibers.

2. At present, our company's domestic cotton is almost dyed knit cotton yarn, so it is best not to use cotton for machine and cotton for leather cleaning machine.

3. Cotton in the Mainland, in some areas, the cotton micronaire value in the early and middle stages is higher than 4.8, and the late and partial medium cotton clones are generally below 4.5, and the neps are around 300. Although the micronaire is in 4.5, the physical indicators are poor due to climate, variety and other reasons. The content of heterosexual fibers is generally high (mainly polypropylene fiber), which has a great influence on the coloring of cloth surface and electric cleaning, and almost all the leather cleaning machine passes through the processing process, although the content is small and bright. The grade is higher, but the number of neps, short piles, fine foreign fibers, and small impurities also increase, which has a negative impact on the production process of cotton yarn.

4, you can use some cotton with lower color grade and better physical indicators, the relative cost will be lower. For example, the last batch of cotton purchased in Yancheng, Jiangsu Province, although the color grade is low, but the internal physical indicators are good, the SCI value is high, and the utilization value is also high.

5. Early and mid-term cotton in the northern part of Jiangsu Province has good physical indicators (excluding skin cleaning), and the regain rate is relatively high. Some of them are more than 10.0 per batch, which brings inconvenience to cotton storage.

6. After consulting the relevant data, the US cotton has the same climatic conditions as the Chinese cotton in the east, middle and west. This has caused differences in the quality of cotton in the eastern, central and western cotton due to climatic conditions. This difference in cotton quality is indicative of differences in internal quality rather than differences in cotton processing quality. Southeastern Region: Alabama, Georgia, North Carolina, South Carolina, Florida, and Virginia, with an average length of more than 1-1/16 inches in medium to low grade cotton; Central and Southern regions : Arkansas, Louisiana, Mississippi, Missouri, and Tennessee cotton fibers are more than 1-3/32 inches long; Southwest: Kansas, Oklahoma, and Texas, on the market MOT's cotton is cotton in this region. The quality of cotton is mainly medium and low, with a length of 1-1/16 inches. Western cotton: Arizona, California and New Mexico. The market is called SJV. Generally, the average length is higher than 1-1/8 inches, the strength is not lower than 30GPT, the fineness is about 4.2, the uniformity is 82%, and the cotton above grade 3 accounts for more than 80%; the other type of CA cotton is produced in Galli In the Nia/AZ area, the grade is higher, but slightly lower than SJV cotton. Generally, cotton above grade 3 accounts for 75%, and the average length is higher than 1-3/32 inches. The quality of all US fine cotton cotton is divided into three categories, that is, the best quality cotton is SJV, CA cotton quality is second, and EMOT cotton quality is the worst. US cotton is normally treated by two or more skin cleaning machines. A series of decontamination treatments cause great damage to some internal quality indicators of cotton. Although the cotton content is reduced, the fine impurities and defects in cotton The number and fiber-seedings have multiplied, which is why we often say that the US cotton has a lot of fine impurities and the fiber-seedings are at least three times higher than the Chinese cotton. The length of the cotton is shortened due to excessive impact. Above 1MM, the cotton linter rate should be at least 3% higher than that of Chinese cotton.

7. Since the United States and Australia belong to developed countries, all cotton is harvested by machine, and cotton is less polluted by human factors. The cotton yarn produced by this cotton is especially suitable for the production of bleaching and bleaching white cotton cloth.

8. India and Pakistan have shorter cotton lengths and coarser fineness. The cotton has various impurities and heterogeneous fiber content, and is generally only suitable for cotton yarn production below 20S. The quality of cotton in Central Asian countries is between China's Xinjiang southern Xinjiang cotton and India and Pakistan cotton. Some cotton has better ginning quality, and some cotton ginning quality is poor, so the cotton yarn count produced by Central Asian cotton is generally At about 32; cotton yarns are not suitable for the production of high-knit fabrics due to the relative impurities and the number of defects. However, in some well-controlled areas, the production of cotton has fewer impurities and defects, and the consistency of cotton. It is also preferred that this type of Central Asian cotton is less abundant and that the cotton yarns produced are suitable for any fabric structure.

Author: Li Fuming

Author: Li Fuming; Source: Jin Kun Ying textiles; agricultural futures to reproduce this network to disseminate more information purposes only, does not mean Ben Wang approved the text of the opinion. If the author of the reprinted article believes that there is something wrong with this website, please contact us at 010-51289506. This website will immediately negotiate with you and resolve related matters. We sincerely invite you to join the elite group of cotton textile industry to build the industry development, QQ group number 386426398.

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Article Keywords: cotton neps cotton yarn

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