Micronaire is a transliteration of English Micronaire. The micronaire value is a comprehensive indicator reflecting the linear density and maturity of cotton fibers. It is one of the important intrinsic quality indicators of cotton fibers and is closely related to the use value of cotton fibers. The intrinsic quality indicators of cotton fiber mainly include fiber length, fiber linear density, fiber strength and fiber maturity.
Classification of micronaire values
Micronaire values are divided into three levels of A, B, and C, and B is the standard level. Grade A ranges from 3.7 to 4.2, with the best quality; Grade B ranges from 3.5 to 3.6, and 4.3 to 4.9; Grade C ranges from 3.4 and below, and 5.0 and above, with the worst quality. The specific measurement method is to use an airflow meter to measure the air permeability of a constant weight cotton fiber after being compressed into a fixed volume, and the value is expressed on this scale. The larger the value, the thicker the cotton fiber and the higher the maturity.
Relationship between micronaire value and yarn quality
Cotton fibers with high micronaire value can withstand mechanical shock, easy to remove impurities, uniform yarn sliver, smooth appearance, few defects, and high finished product yield. However, the micronaire value is too high, which will affect the yarn strength. Cotton fibers with a low micronaire value often have poor maturity, are prone to harmful defects, and have poor dyeability. Therefore, only cotton with a moderate micronaire value can take both aspects into consideration and obtain comprehensive economic benefits.
The relationship between the micronaire value and the yarn quality cannot be generalized, and is closely related to the thickness of the yarn number. The coarse yarn has a high micronaire value, and the quality of the fiber yarn is good; the fine yarn, especially the extra fine yarn, requires a lower micronaire value, and the yarn quality is good; the yarn number is large, and the number of fibers per unit section is directly affected by the strength of the fiber The yarn strength is small, and the number of fibers per unit cross section is small. The number of fibers directly affects the yarn strength.
The micronaire level is a linear density index range. The original unit was 10 g / inch to 6 g / inch. Due to the instability of the test, the current micronaire value is treated as a dimensionless value.
Relationship between micronaire value and spinning process
To spin a certain thickness of yarn so that the yarn has a certain strength to withstand various stresses in the process and give the necessary performance to the textile, the yarn must have a certain minimum number of fibers in the cross section. Therefore, coarse fibers are spun coarse yarns, and fine fibers are spun fine yarns. Under the same conditions, the finer the fiber, the higher the yarn strength, and the better the uniformity of the yarn. However, the finer the fibers, the easier it is to kinks and breaks during processing, and it is easier to form neps.
Micronaire value is a comprehensive reflection of cotton linear density and maturity. Therefore, it is closely related to the yarn quality and spinning process. Cotton fibers with high micronaire value can withstand mechanical shock, easy to remove impurities, uniform yarn sliver, smooth appearance, few defects, and high finished product yield. However, the micronaire value is too high, which will affect the yarn strength. Cotton fibers with a low micronaire value often have poor maturity, are prone to harmful defects, and have poor dyeing properties. Therefore, only cotton with a moderate micronaire value can take both aspects into consideration and achieve a more comprehensive economic effect.
High maturity cotton fibers have good strength, can withstand processing and cleaning machinery, easily remove impurities, and are not easy to produce neps and ropes. The finished product has a high yield. Cotton fibers with poor maturity tend to form more harmful defects, and the finished product yield is also low. Cotton fibers with high maturity have high yarn strength and good evenness. But too mature cotton fibers have poor cohesion, yarn strength and evenness. Cotton fibers with high maturity have good color absorption and uniform fabric dyeing.
The USDA's spinning tests and the use experience of Chinese and foreign textile mills have shown that a low micronaire value will produce more clear steel noil, and the appearance of the yarn will deteriorate, but the yarn strength and spinnable number will be improved, and vice versa , Will cause the cotton yarn cohesion to decrease, increase the cotton yarn break, reduce the number of spun yarns can be spun, but can reduce the amount of noil, improve the appearance of the yarn.
Therefore, cotton with a micronaire value of 3.5 to 4.9 is regarded as a normal micronaire cotton. In particular, for cotton with a micronaire value in the range of 3.7 to 4.2, the price must be increased. This is why in the new standard, cottons with a 3.7 to 4.2 micronaire value are classified as A, and those below 3.5 and 5.0 are classified as C.
The significance of micronaire
Micronaire values can provide accurate basis for cotton distribution in textile mills to ensure optimal use of cotton. Dividing and depositing according to the micronaire value index can improve and stabilize the quality of gauze. The micronaire value indicator is in the test, the operation of the instrument is simple and the data is clear. Persuasive; the micronaire value is related to the quality of the yarn and the spinning process. The moderate micronaire value of cotton has high strength, good spinning quality, good appearance on the cloth, and solid and durable. When identifying cotton grades, Adding the micronaire indicator can reduce the quality disputes between buyers and sellers, and can effectively prevent the phenomenon of second-rate charging.
