What is a micronaire value? What is the relationship between the size of micronaire and cotton yarn?

Micronaire is a transliteration of Micronaire in English. Micronaire value is a comprehensive index reflecting the fineness and maturity of cotton fiber. It is one of the important intrinsic quality indicators of cotton fiber and closely related to the use value of cotton fiber. The intrinsic quality indicators of cotton fiber are fiber length, fiber fineness, fiber strength and fiber maturity.

First, the classification of micronaire value

The micronaire value is divided into three levels: A, B, and C. Level B is the standard level. Class A values ​​range from 3.7 to 4.2, with the best quality; Class B values ​​range from 3.5 to 3.6 and 4.3 to 4.9; Class C values ​​range from 3.4 to less than 5.0 and above, with the worst quality. The specific measurement method is to use an air flow meter to measure the air permeability of a constant weight cotton fiber after being pressed into a fixed volume, and the scale value is expressed. The larger the value, the thicker the cotton fiber and the higher the maturity.

Second, there is a close relationship between the value of micronaire and yarn quality.

High-micron-cotton cotton fiber can withstand mechanical impact, easy to remove impurities, into a uniform yarn, smooth appearance, fewer defects, the finished product rate is high. However, the high micronaire value will affect the strength of the yarn. Cotton fibers with too low micronaire values ​​tend to have poor maturity and are prone to deleterious defects and poor dyeability. Therefore, only the cotton with a moderate micronaire value can take into consideration both aspects and achieve more comprehensive economic benefits.

The relationship between micronaire value and yarn quality can not be generalized, and it is closely related to the thickness of the yarn. The low count yarn has a high micronaire value. The fiber pile has good yarn quality, and the fine-count yarn, especially the ultra fine yarn, has a relatively low requirement. The coarse unit yarns of the yarn support have many fiber roots. The strength of the fibers directly affects the strength of the yarns. The number of fiber yarns at the cross-section of the yarns is small, and the number of fibers directly affects the yarn strength.

The micronaire value range is a range of fineness indicators. The original unit is 10-6 g/inch. Due to the instability of the test, the current micronaire value is treated as a dimensionless value.

Third, the relationship between micronaire value and spinning technology

To spin a certain thickness of the yarn, so that the yarn has a certain degree of strength, in order to withstand the various stresses in the process, give the necessary performance of the textile, the yarn must have a certain minimum number of fibers in the cross-section. Therefore, coarse fiber spun rovings and fine fiber spun yarns. Under the same conditions, the finer the fibers, the higher the strength of the yarns and the better the evenness of the strips. However, the finer the fiber, the easier it is to kink and break during processing and it is easier to form neps.

The cotton fiber with high maturity has good strength, can withstand the impact of processing and cleaning machinery, easy to remove impurities, not easy to produce neps and cable, high finished product rate. Poorly mature cotton fibers tend to form more harmful defects, and the finished product yield is also low. High-maturity cotton fibers have high yarn strength and good evenness. However, over-mature cotton fibers have poor cohesion, and the yarn strength and uniformity are not good. Cotton fiber with high maturity has good color absorption and uniform fabric dyeing.

The micronaire value is a comprehensive reflection of cotton fineness and maturity. Therefore, it has a close relationship with yarn quality and spinning process. High-micron-cotton cotton fiber can withstand mechanical impact, easy to remove impurities, into a uniform yarn, smooth appearance, fewer defects, the finished product rate is high. However, the high micronaire value will affect the strength of the yarn. Cotton fibers with too low micronaire values ​​are often poorly matured, prone to deleterious defects, and have poor dyeability. Therefore, only the cotton with a moderate micronaire value can give consideration to both aspects and obtain a more comprehensive economic effect.

The United States Department of Agriculture's spinning test and the experience of Chinese and foreign textile mills all show that the low micronaire value will produce more steel-cleaved cotton and the appearance of the yarn will deteriorate, but it will increase the yarn strength and the number of spinnable yarns. It will cause the decline of the cohesion of the cotton yarn, increase the breakage of the cotton yarn, reduce the spinning count of the spun yarn, but it can reduce the amount of cotton and improve the appearance of the yarn.

Therefore, cotton that has a micronaire value between 3.5 and 4.9 is used as a normal micronaire value cotton. In particular, cotton with a micronaire value in the range of 3.7 to 4.2 will have to increase its price. This is also the reason why the cotton of 3.7~4.2 micronaire value is classified as A grade in the new standard, and the grade of 3.5 or more is rated as C grade.

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