There are many kinds of spandex yarn industry

Classification of spandex covered yarn

1. According to the number of coating layers, it can be divided into two types: single-covered yarn and double-covered yarn. Among them, nylon and polyester are mostly covered by single-wrap.

2. According to different equipment, it can be divided into two types: mechanical covered yarn and air covered yarn.

Main process

In the spinning process, the spandex stretch is an important process parameter, which affects the elasticity of the Covered Yarn and the fabric, as well as the strength and elongation of the covered yarn, evenness and creep performance. The pre-draft ratio of spandex is too small to give full play to the elasticity of the elastic fabric. When the draft is too high, spinning is difficult, and it is easy to cause yarn breakage, and the product quality will decrease; in addition, the percentage of spandex yarn will also affect The covered yarn has high elasticity, high content and good elasticity.

The strength and elongation of the air-covered yarn increases with the increase of the spandex pre-draft ratio. After the spandex yarn is drawn to a certain value, the shrinkage of the spandex yarn makes the outer fiber curled; appropriately increase the pre-draft ratio, and the spandex The percentage content is reduced, and the degree of curling of the outer fiber is large. However, when the drafting is too large, the deformation range of the spandex yarn is close to the critical value of deformation, which will reduce the strength and elongation of the covered yarn, but it is beneficial to the evenness of the covered yarn.

The phenomenon that the deformation changes with time under the action of a constant drafting force is called creep. Conventional covered yarn has creep resistance when spandex yarn is pre-drawn 3.5 times. Specifically, it should be adjusted appropriately according to the purpose and the style of downstream fabrics.

In addition to the requirements of the spandex drafting ratio in the air-covered yarn, another important process parameter is the twist. The twist affects the yarn quality, strength, elongation and evenness. Increasing the twist can increase the cohesive force between the outer fiber and the spandex yarn, so that the strength of the covered yarn is improved. If the twist is too low, the outsourcing fiber will be loose, which will affect the coating effect and cause core exposure. Therefore, the twist should be high during mechanical coating. However, the twist is too high, the fabric feels hard, and the drape is poor. Generally, the twist is adjusted according to the denier of the yarn and the style of the fabric. The elongation of the machine bag is also mainly determined by the performance of the spandex core yarn. The twist is too large and the outer fiber is wrapped too tightly. On the contrary, the elastic effect of silk cannot be fully exerted, which reduces the elongation.