Application of spandex core-spun yarn
Spandex is a high elastic synthetic fiber, with good flexibility, the production of a variety of elastic fabrics. Cotton spandex core-spun yarn with spandex as core-spun yarn and cotton fiber as the outer-spun yarn is an ideal raw material for producing various elastic fabrics, which can not only exert the high elasticity of spandex, but also keep the advantages of cotton fiber. The fabric made of cotton p spandex core-spun yarn has comfortable, fit, breathable, hygroscopic and beautiful wearability, and is widely used.
1. Spandex core-spun yarn clothing reflects the beauty of the curve of the human body
The use of spandex in clothing started from the three-port (collar, cuffs, trousers) of knitted underwear. Before, knitted underwear used to be made of pure cotton. After washing, its elasticity disappeared, and the three-port became deformed, which could not keep warm, it's not pretty. Since the appearance of spandex, the three-point rib of knitted underwear is woven with naked spandex, which greatly improves the elasticity of the three-point.
Spandex core-spun yarn made of clothing can not only reflect the human body, especially the beauty of the curve of women, but also can wear comfortable and beautiful. At present, the main comparison of high-grade men's and women's underwear, fitness clothing, sportswear, competition clothing, casual clothing, and so on, the prospects for development are very good. Make People's dress grade further high-grade. As for polyamide and polyester polyurethane core-spun yarn fabrics, with better elasticity, wear resistance, bright color, its washing and light fastness, durable. It is the ideal fabric for making swimsuit, competition suit, training suit, sports suit, training suit, cycling suit, etc. , whether it is a world-famous brand, or other clothing manufacturers have it as the production of sportswear fabrics of choice, its products all over the world.
2. Application of spandex core-spun yarn in hosiery industry
The applications of spandex in the hosiery industry include:
- Nylon wrapped spandex
- Polyester Spandex
- Cotton-wrapped spandex
- Wool-wrapped spandex
3. The proportion of spandex used in fabric is increasing
Early spandex only in swimwear, some underwear, socks, rib mouth, some sportswear and other aspects of use, in recent years with the improvement of People's living standards and changes in consumer fashion, as well as core-spun yarn, knitting, textile and other application technology of Spandex, spandex applications, the amount of rapid expansion and increase, spandex textiles have become international fashion consumer goods. On the one hand, new uses such as casual wear, children's wear, men's wear, woolen sweater, medium and high-grade coat fabrics, women's spring and autumn wear, and medical products are constantly being developed. On the other hand, the proportion of spandex used in traditional products -- socks, underwear, sportswear -- has increased dramatically. Take our country as an example, in the early t-shirt, underwear only a small part of the addition of spandex, in recent years, most of these products added spandex, jacket is also widely started to add spandex, elastic fabric began to prevail; Spandex has also been widely used in socks. At the same time, the proportion of similar products to add spandex is also increasing, spandex in the use of horizontal and vertical development, can be said in clothing, clothing products in the use of ubiquitous.
Performance parameters of spandex core-spun yarn
1. Properties of spandex filament
The biggest characteristic of spandex filament is that it has high elasticity, its elastic elongation can reach 6 ~ 7 times, the elastic recovery rate can reach 95% ~ 98% , and it can bear repeated stretching, that is in the range of 50% ~ 250% of the tensile force and shrink back, which is unique characteristics of spandex filament.
The fabric with spandex filament wear no restraint, no pressure, and no sense of relaxation, other elastic fibers can not be compared.
2. Predrawing ratio of spandex filament
When spinning spandex core-spun yarn, the predrafting ratio of spandex filament is about 3.8 times, and the elasticity of elastic fabric can be controlled between 25% ~ 35% . Spandex core-spun yarn of 16.2 Tex ~ 18.2 tex is commonly used in knitted underwear and elastic hosiery, 77 dtex is commonly used as spandex filament of fine spandex core-spun yarn, and 3.5 ~ 3.65 times is suitable for predrafting of spandex filament. The stretch ratio of medium thick spandex core-spun yarn used for weaving warp elastic denim is about 3.8 ~ 4 times.
3. Heat setting of spandex core-spun yarn
The twist setting temperature of spandex core-spun yarn is generally 60E ~ 80e, 15min ~ 20min, two times vacuum setting, controlling its elasticity, avoiding high temperature and long time setting, so as not to damage the elasticity of the core-spun yarn. If the steam is steam, the temperature is 75E ~ 80e, the time is 40min.
Overview of core-spun spinning
In 1960s, the core-spun yarn method began to be tested in a few spinning mills in western countries. By 1968, the appearance of dupont company's wrapped yarn promoted the development of core-spun yarn. A variety of new core spun yarns have been developed to address the shortcomings of DuPont and are available on the market.
1. New core-spun spinning method
- True core-spun spinning: invented by Lisenner, USA
- Dust cage friction core spinning method should: method originally from Austria's Dreff dust cage spinning method
- Air-core spinning: this method is West Germany's Inkolstadt air spinning
- Double-tube air-jet core spinning: this method was developed by the West Germany Lautlingen Institute of Textile Technology
- ARCT has made a SR200 type self-wicking composite spinning machine with the patent of French Textile Research Institute
Structure and properties of spandex core-spun yarn
1. Structure of spandex core-spun yarn
Spandex core-spun yarn is a kind of yarn with spandex as its core and one or several non-elastic staple fibers as its outer package. The core of core-spun yarn is surrounded by outer fiber, and the two are closely combined.
2. Elastic properties of cotton-ammonia core-spun yarn
The core has the same twist as the outer fiber. It has three distinct features:
First, it has the same hand feeling and appearance as the coated fiber (cotton, wool, polyester, etc.) . The outer sheath made of natural fiber has good wettability
Second, good elasticity;
Third, the elastic percentage can be controlled below 2% .
3. Dyeing properties of polyurethane core-spun fiber
Spandex core-spun yarn has a remarkable characteristic compared with other stretch yarns that the core is not exposed under tension. Therefore, dyeing effect is good, appropriate to do, including dark, and other colors of the product.
4. Mechanical properties of polyurethane fiber core-coating
The strength of core-spun yarns is relatively low compared to other types of stretch yarns. In general, the strength of core-spun yarn is only equivalent to 80% ~ 90% of that of the outer fiber of the same yarn. The core-spun yarn is broken first by the outer fiber, and the strength formed by the outer fiber is the core-spun yarn strength. Spandex is a low strength and high elongation filament, it does not contribute to the strength of the yarn in the core-spun yarn, so the higher the spandex content, the lower the strength of the core-spun yarn.
5. Effect of twist on properties of spandex core-spun yarn
The twist of the yarn directly affects its strength, abrasion resistance and handle feeling. Low twist makes the handle feel soft. It also results in deterioration of the coating performance, poor strength and abrasion resistance. If the twist is properly increased, the strength will be increased, wear resistance is good, but feel hard. Since there is a core in the center of the yarn, the cohesion between the coated fibers is affected and the strength of the yarn is reduced. Therefore, it is necessary to increase the twist to increase the cohesion between the fibers, and to obtain a good coating.
Main properties of spandex core-spun yarn
1. The initial tension of the polyurethane core-spun yarn test
Different test standards will give different results when testing the performance indexes of yarns. Spandex core-spun yarn currently has unified national inspection standards, manufacturers are based on pure cotton yarn and customer requirements to develop quality standards. Because spandex core-spun yarn is elastic yarn, there are obvious differences in breaking elongation rate and elastic recovery rate when it is tested with different initial tension, including the test of actual number will be affected. The pre-added initial tension shall cause the core-spun yarn to straighten but not to elongate.
2. Three factors affecting elasticity of spandex core-spun yarn
- Characteristics of spandex: the thicker the spandex, the greater its elasticity.
- Spandex filament pre-draft multiple: Spandex filament if not through the draft, there will be no elasticity, spandex filament pre-draft in general 3 to 5 times, too low to play the advantages of elasticity, too high will inevitably lead to broken head, make spinning difficult.
- High spandex content, the elasticity of the yarn is large, the common elastic core-spun yarn spandex content is generally not more than 10% , for high elastic fabrics, spandex filament or spandex and other filament wrapped yarns can be added directly during the weaving process.
3. Influence of twisting parameters on coating effect
The core-spun yarn must be completely covered with the yarn-core spandex filament. If the spandex filament is exposed to form a "core-dew" phenomenon, it will affect the dyeing of the subsequent process, in the following processing process, it is inevitable that the spandex yarn will rub too much directly with the machine parts, which will cause the spandex yarn to break unexpectedly, resulting in the hollow yarn losing its elasticity and the yarn wrinkling on the cloth surface, forming defects. So the spinning process should try to make filament distribution in the central part of the yarn, to avoid exposure. A higher twist factor is the most effective way to ensure that the polyurethane filament is wrapped in the center and not exposed, because a higher twist factor can make the wrapped fibers close to each other, resulting in greater centripetal pressure, thus the spandex filament is tightly "encircled" in the center, and the twist coefficient is 380 ~ 420.
4. The steam setting technology is used to reduce the defects of the coil
Because of the larger twist coefficient of core yarn, part of twist will be lost in the process of placing or unwinding.
5. Selecting and matching high quality outer covering fiber to improve the strength of the core-spun yarn
For wrapped yarns, the strength of the yarn-core filament plays a decisive role. But core-spun yarn is different, because the strength of spandex yarn is low, it does not bear the strength of the yarn, the strength of the core-spun yarn is almost entirely determined by the outer fiber. The higher the content of spandex, the lower the yarn strength. The strength index of spandex core-spun yarn is obviously lower than that of pure cotton yarn, but the improvement of cotton blending can make up the difference.
