Micronaire is the transliteration of English Micronaire. Micronaire value is a comprehensive index that reflects the linear density and maturity of cotton fiber. It is one of the important intrinsic quality indicators of cotton fiber and is closely related to the use value of cotton fiber. The intrinsic quality indicators of cotton fiber mainly include fiber length, fiber linear density, fiber strength and fiber maturity.
Micronaire classification
The micronaire value is divided into three levels: A, B, and C. Level B is the standard level. The value range of grade A is 3.7~4.2, which is the best quality; the value range of grade B is 3.5~3.6 and 4.3~4.9; the value range of grade C is 3.4 and below and 5.0 and above, which is the worst quality. The specific measurement method is to use an air flow meter to measure the air permeability of a constant weight of cotton fiber after being pressed into a fixed volume, and express it as a numerical value on this scale. The larger the value, the thicker the cotton fiber and the higher its maturity.
The relationship between micronaire value and yarn quality
Cotton fiber with a high micronaire value can withstand mechanical impact, is easy to remove impurities, has uniform yarn dryness, smooth appearance, few defects, and high yield of finished products. However, if the micronaire value is too high, it will affect the yarn strength. Cotton fibers with too low micronaire tend to have poor maturity, are prone to harmful defects, and have poor dyeability. Therefore, only cotton with a moderate micronaire value can take into account both aspects and obtain more comprehensive economic benefits.
The relationship between micronaire value and yarn quality cannot be generalized, and is closely related to the thickness of the yarn number. Coarse yarns have a high micronaire value, and the fiber yarn quality is good; fine yarns, especially extra-fine yarns, require a relatively low micronaire value, and the yarn quality is good; thick yarns have a large number of fibers per unit cross-section, which directly affects the strength of the fibers. The strength of the yarn is that the number of fibers per unit cross-section is small when the yarn size is fine, and the number of fibers directly affects the strength of the yarn.
The micronaire level is a range of linear density indicators. 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.
The relationship between micronaire and spinning technology
In order to spin a yarn of a certain thickness so that the yarn has a certain strength to withstand various stresses in the process and give the textile the necessary performance, the yarn must have a certain minimum number of fibers in the cross-section. Therefore, coarse fibers are spun into coarse yarns, and thin fibers are spun into fine yarns. Under the same conditions, the finer the fiber, the higher the yarn strength and the better evenness. However, the finer the fiber, the easier it is to kink and break during processing, and to form neps.
The micronaire value is a comprehensive reflection of cotton linear density and maturity. Therefore, it is closely related to yarn quality and spinning technology. Cotton fiber with a high micronaire value can withstand mechanical impact, is easy to remove impurities, has uniform yarn dryness, smooth appearance, few defects, and high yield of finished products. However, if the micronaire value is too high, it will affect the yarn strength. Cotton fibers with too low micronaire tend to have poor maturity, are prone to harmful defects, and have poor dyeing performance. Therefore, only cotton with a moderate micronaire value can take into account both aspects and achieve a more comprehensive economic effect.
Highly mature cotton fibers have good strength, can withstand processing and cleaning machinery, are easy to remove impurities, are less likely to produce neps and strings, and have a high yield of finished products. Cotton fibers with poor maturity are prone to form more harmful defects, and the yield of finished products is also low. Cotton fibers with high maturity have high yarn strength and good evenness. However, over-mature cotton fibers have poor cohesion, poor yarn strength and evenness. Highly mature cotton fiber has good color absorption and even fabric dyeing.
The spinning test of the United States Department of Agriculture and the use experience of Chinese and foreign textile mills have shown that a low micronaire will produce more steel waste and deteriorate the appearance of the yarn, but it can improve the yarn strength and spinnable number, and vice versa. , will cause a decrease in cotton yarn cohesion, increase cotton yarn breakage, and reduce the spinnable number of spun yarns, but it can reduce the amount of waste and improve the appearance of the yarn.
Therefore, internationally, cotton with a micronaire value of 3.5 to 4.9 is regarded as normal micronaire cotton. Especially cotton with a micronaire value in the range of 3.7 to 4.2 will be priced higher. This is why in the new standard, cotton with a micronaire value of 3.7 to 4.2 is designated as grade A, while cotton with a micronaire value of less than 3.5 and above 5.0 is designated as grade C.
The importance of micronaire
The micronaire value can provide an accurate basis for cotton allocation in textile factories to ensure the best use of high-quality cotton; dividing and storing according to the micronaire value index can improve and stabilize the quality of gauze; the micronaire value index is under inspection, the instrument is simple to operate, and the data is clear , persuasive; the micronaire value is related to the quality of the yarn and the spinning process. Cotton with a moderate micronaire value has high yarn strength, good spinning quality, good cloth appearance, and is solid and durable; when identifying cotton grades, Coupled with the micronaire index, it can reduce quality disputes between buyers and sellers and effectively prevent shoddy goods.
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