Introduction of empty bag and machine bag spandex yarn composite fabric information

Spandex covered yarn (Covered? Spandex? Yarn) generally has single-pack, double-pack and other covering forms. Among them, nylon ammonia and polyester ammonia are mostly coated in a single package. Air covered yarn (abbreviated as air covered yarn, English abbreviation ACY) is a yarn in which the outer fiber filament and the spandex yarn are simultaneously drawn through a certain type of nozzle, and the rhythmic network points are formed by regular spraying of highly compressed air. . The fabric feels soft and smooth; mechanical covered yarn (abbreviated as machine package, English abbreviation as SCY) is a continuous rotation and winding of the outer fiber filament on the core spandex that is drawn at a uniform speed. It is twisted and has twist (English abbreviation TPM), the smooth and crisp fabric style is its main feature. Empty machine-wrapped yarns have their own advantages and disadvantages when weaved in downstream weaving factories. Empty bales generally need to be sized when being warped on an air-jet loom, otherwise the fabric is prone to fluffing and broken wires, etc. However, it can be used directly after beating up. Considering the cost alone, the production capacity of empty bales is much higher than that of machine bales, making the price lower than that of machine bales, which facilitates the reduction of costs for downstream weaving mills. Although the core yarn is not exposed in machine bags, it is generally not prone to quality problems during spinning and weaving except for uneven twist. However, the output is low, and the price is therefore more than RMB5000/T higher than empty bags of the same specification. The price of fine denier covered yarn It is even higher than RMB10,000/T for empty packages of the same specifications, thus greatly increasing the cost of using machine packages. In the spinning process, the pre-draft ratio of spandex (Spandex? Stretch) is an important process parameter. It affects the elasticity of the covered yarn (Covered? Yarn) and fabric, and also affects the strength and elongation of the covered yarn. Evenness and creep properties. The pre-draft multiple of spandex is too small, which cannot give full play to the advantages of elasticity of elastic fabrics. When the draft is too high, it is difficult to spin, and it is easy to cause wire breakage, and the product quality will decrease; in addition, the percentage of spandex fiber also affects The elasticity of the covered yarn is high, and the elasticity is good. When the spandex yarn specifications are certain, increasing the draft ratio will reduce the percentage of spandex yarn, that is, the pre-draft multiple of spandex is inversely proportional to the percentage of spandex in the finished yarn. The strength and stretch of the covered yarn increases with the increase of the spandex pre-drafting multiple. After the spandex is stretched to a certain value, the retractability of the spandex yarn causes the outer fiber to be curled, and the spandex core yarn is straightened; appropriately increase The pre-drafting ratio reduces the spandex percentage and the outer fiber curl degree is large. However, when the draft is too large and the deformation amplitude of the spandex yarn approaches the critical value of deformation, the strength and elongation of the covered yarn will decrease, but it will help the evenness of the covered yarn. The phenomenon of deformation changing with time under the action of constant drafting force is called creep. The creep resistance of the covered yarn is the best when the spandex yarn is pre-drafted 3.5 times. The twist of the machine package affects the quality, elongation and evenness of the yarn. Increasing the twist can increase the cohesion between the covering fiber and the spandex yarn, thereby increasing the strength of the covering yarn. The elongation of the machine bag is mainly determined by the performance of the spandex core yarn. If the twist is too large and the outer fiber is wrapped too tightly, the elastic effect of the spandex yarn cannot be fully exerted, causing the elongation to decrease. As twist increases, evenness improves. The twist is too small and the outer fibers are loose. During the spinning process, the fibers will move slightly along the axis of the yarn due to friction and other reasons, so the evenness deteriorates. The presence of spandex yarn in the machine bag will weaken the cohesion between the outer fiber filaments. The twist will be too low and the outer fiber will be loose, which will affect the covering effect and lead to core exposure. Therefore, the twist should be higher during mechanical wrapping. But if the twist is too high, the fabric will feel hard and have poor drape. Generally, the twist should be adjusted as the denier of the yarn changes. For example, for N40D+20D machine packages, the twist is 600 twists, while for N70D+40D or T150D+40D machine packages, the twist should be controlled at around 480. Some small In order to consider delivery time and reduce production costs, spinning mills will reduce twist or increase equipment speed to increase output, which is not conducive to the quality of wrapped yarn.
AAADFGTEHTRY