There are two types of soft segments in the spandex fiber chain structure: polyester and polyether, which are divided into polyester spandex and polyether spandex. Generally, polyether spandex has a lower glass transition temperature and better elasticity than polyester spandex.
The soft segment part of the spandex fiber chain structure has two types: polyester and polyether, which are divided into polyester spandex and polyether spandex. Generally, polyether spandex has a lower glass transition temperature and better elasticity than polyester spandex.
Spandex can be directly used to weave elastic fabrics in the form of bare silk, or the bare silk can be processed into a certain form of elastic yarn before use For weaving stretch fabrics. The most common forms include spandex core-spun yarn, spandex twisted yarn and spandex covered yarn.
The processing principles of the three elastic yarns are different, which determines that their fiber structures are quite different, which is the fundamental factor affecting the performance of the yarns. Spandex core-spun yarn can be spun by ring spinning, vortex spinning, electrostatic spinning and other methods. The most widely used method is ring spinning. Spandex twisted yarn is also called plied yarn. It is processed by using a twisting machine after modification. Spandex covered yarn is processed on special equipment with hollow core spindles. When one hollow core spindle is used, single-layer coating is performed, and when two hollow-core spindles are used, double-layer coating is performed.
Structure characteristics and performance analysis of spandex core-spun yarn
Spandex core-spun yarn is a yarn spun with spandex yarn as the yarn core and one or several non-elastic short fibers wrapped around it. The core filament of the core-spun yarn is surrounded by the outer fiber, and the two are closely combined. The core filament and the outer fiber have the same twist.
It has three significant characteristics: First, it has the same feel and appearance as the outer fiber (cotton, wool, polyester, cotton, etc.); The outer sheath composed of natural fibers has good hygroscopicity; secondly, it has good elasticity; thirdly, the elasticity percentage can be controlled below 20%.
Compared with other elastic yarns, spandex core-spun yarn has a significant feature that the core yarn is not exposed when the yarn is stretched tightly. Therefore, the dyeing effect is good and it is suitable for making products of various colors including dark colors.
Compared to other types of stretch yarns, the strength of core-spun yarns is relatively low. Under normal circumstances, the strength of a single yarn is only equivalent to 80% to 90% of that of the same specification of outer fiber when it is yarned alone. The first thing to break in the core-spun yarn is the outer fiber, and the strength formed by the outer fiber is the strength of the core-spun yarn. Spandex yarn is a low-strength and high-elongation filament. It does not contribute to the strength of the yarn in the core-spun yarn, but destroys the cohesion between fibers. Therefore, the higher the spandex content, the lower the strength of the core-spun yarn.
Structure characteristics and performance analysis of spandex twisted yarn
Spandex twisted yarn is made by twisting the stretched and stretched spandex yarn and two inelastic yarns. If this kind of yarn is unwound and the tension is relaxed while a lighter impact is applied to the entire yarn, the yarns will move to a stable state. As a result, the spandex yarn will enter the yarn core, and other inelastic yarns will Becomes an outer cladding, giving it a corresponding look and feel.
The spandex yarn of this kind of yarn has the same twist as the outer yarn. In the tensioned state, there is no obvious core-sheath relationship between the spandex yarn and other yarns. It’s a mutually intertwined relationship. Therefore, the spandex filaments of the yarn are exposed under tension. Since the coloring properties of spandex yarn are inconsistent with other inelastic yarns, which can easily lead to color differences, it is not suitable for dark-colored products.
Spandex elastic twisted yarn has the following advantages: first, the spandex yarn can be matched with various yarns or filaments; second, it is suitable for small batch production of multiple varieties, and even one twist The thread machine can process several types at the same time; thirdly, the elasticity can be determined according to the use of the product; fourthly, it can be used with the outer cladding yarn that is consistent with the fabric, so that the appearance of the product is consistent with the raw material of the fabric, and the same hue can be achieved after dyeing.
The strength of elastic twisted yarn is the strength of non-elastic yarn combined with spandex yarn. Therefore, it has higher strength than spandex core-spun yarn of the same specifications.
The degree of cohesion between the spandex yarn and other non-elastic yarns in the elastic twisted yarn is lower than the cohesion between the spandex yarn and the outer fiber in the spandex core-spun yarn. Therefore, , the elasticity of twisted yarn is higher than that of core-spun yarn.
Structural Characteristics and Performance Analysis of Spandex Covered Yarn
Covered yarn is also called wrapped yarn. One of the most obvious differences between covered yarn and other elastic yarns is that the core yarn has no twist. The core-sheath relationship between the spandex yarn and the outer cladding in the covered yarn is obvious, but the degree of cohesion between the core yarn and the outer cladding is significantly lower than that of the core-spun yarn and twisted yarn, so its elasticity is higher than the first two. The elongation can reach 200% (double wrapped yarn), and about 50% elasticity can be obtained in high-elastic fabrics.
The covered yarn has a core phenomenon when it is tensioned, so it is not suitable for dark products. The feel of the covered yarn is better than that of the core The yarn is hard, and the strength of the covered yarn is the strength of the outer filament or yarn, so it is higher than the strength of the core-spun yarn of the same specification.
From the processing process of covered yarn It can be seen that the covered yarn is relaxedly wound, and the winding rate generally ranges from 60% to 95% depending on the use. This is different from core-spun yarn and twisted yarn, and has a greater impact on the weaving process parameters.</p
