Spandex Yarn Introduction

Spandex is the earliest developed and most widely used elastic fiber with the most mature production technology. But for some consumers in the market,Lycra is much better known than spandex, and many in the industry only know Lycra, not spandex. And some businesses in the product promotion is also a generalization, confused. Some “professionals” simply referred to Lycra as a common name for spandex, exacerbating the misperception of ordinary consumers.

1 development history of spandex

In fact,Lycra is just the trade name of spandex produced by Invista, a former wholly owned subsidiary of DuPont in the United States. Because of the company’s leading market position in spandex,Lycra has almost become a synonym for all spandex.

1.1 International development history of spandex

The research of polyurethane began in Germany at the earliest. In 1937, Bayer company of Germany synthesized polyurethane polymer for the first time and applied for a patent. DuPont company in the United States in the late 1950s was the first to use dry spinning route for the industrialization of spandex production, initially known as “T-80”, L962 with the trademark “Lycra” for the full design scale of polyurethane bond silk, complex silk production. At the same time, the United States Rubber Co., Ltd. introduced a thick round monofilament made of polyester – polyurethane, the trade name “Vyrene”. In 1963, the Japanese Toyo Textile Company began the production of spandex, the trade name “Espa”. In 1964,Bayer and Fujibo Spandex began to produce Spandex. Toray — DuPont, a joint venture between DuPont and Toray, Japan, also began to produce Lycra in 1966. By 1967, the annual output of spandex in the world has reached 6800T, and the production plants have developed to 28. But the obstacles in the manufacturing technology of spandex and the immaturity of the post-processing technology, coupled with the speculation that the demand was too large, made spandex products unsalable accumulation, many manufacturers in Europe and the United States have stopped production or reduced production. In the 1970s, except for DuPont, there was almost no new equipment in other spandex production factories, and spandex industry developed slowly.

In the 1980s, spandex production began to recover, and the world spandex production increased slowly from 20,000 t/a in 1980 to 25,000 t/a in 1985. In the 1990s, the economically developed countries such as the United States, Germany and Japan expanded the production capacity of spandex and accelerated the development of spandex elastic fabrics. The spandex output increased rapidly from 40,000 t/a in 1990 to 92,000 t/a in 1994, including 23,000 t/a in North America, 23,000 t/a in Western Europe and 4.6 t/a in Asia-pacific and other regions t/a.

1.2 Development History of Chinese Spandex

Asia is the region where the consumption of spandex has surged, and it is also the region with the fastest expansion capacity of spandex production. Before 1995, most of the world’s largest spandex yarn manufacturers were concentrated in Europe and the United States, but with the adjustment of demand structure, this format is gradually changing. Among them, spandex in South Korea and Japan has developed the most rapidly, and China’s rapid development in this field in recent years cannot be underestimated.

The development of spandex in China started relatively late. In 1987, Shandong Yantai Spandex Group first introduced the spandex production equipment and technology of Toyobo Corporation of Japan, and produced polyether spandex by dry method, with a production capacity of 320t/a. It was put into operation in 1989 and expanded in 1998. , the production capacity has reached 2500t/a. So far, not only has the technology changed from introduction to independent development, but most of the production equipment and raw materials have also been localized. In 1998, the fifth phase of the project was built, and the investment in this joint venture project totaled 500 million yuan. , with a production scale of 4,000 t/a. It was completed and put into operation at the end of 2000. After it was put into operation, the total production capacity reached 6,500 t/a, ranking first in China. The original Lianyungang Zhongshan Spandex Co., Ltd. imported spandex dry spinning with a production capacity of 320 t/a from Japan’s Toyobo Co., Ltd. Silk production technology and equipment, after being put into production in 1992, was expanded in the second and third phases, with a production capacity of 1,500 t/a. In 1998, the fourth phase of expansion with a scale of 2,000 t/a began, with a total production capacity of 3,500 t/a. Guangdong Heshan Spandex Factory signed a contract with Italian NOY Company in 1992 to introduce China’s first wet-process spandex production equipment, and it was put into operation in 1996 with a production capacity of 500t/a. In 2000, the total domestic spandex production capacity reached 17,600t/a.

In recent years, China’s spandex industry has shown a trend of simultaneous and substantial development in production capacity, output, export volume and benefits. According to statistics, from 2001 to 2006, China’s spandex production capacity has soared from 25,100 t/a to 235,600 t/a, with an average annual rate of 235,600 t/a. The growth rate is as high as 56.5%; the production capacity in 2007 reached 262,600 t/a, and the new production capacity in 2008 reached 12.73t, and the total production capacity reached 389,900 t/a. The rising star China’s development started late, but the speed is rapid, and it has now become the world’s largest Largest producer of spandex yarn.

2 Main specifications and uses of spandex yarn

2.1 Spandex Specifications

The size of spandex yarn ranges from 11dtex to 3750dtex. The most commonly used specifications are 20D, 30D, 40D, 70D, 140D, of which 40D is used more than 50%. Paralleling, weft knitting and warp knitting are widely used; the amount of 70D is basically second only to 40D in the past few years, and it is mainly used in covering and knitting; in the past two years, 20D and 30D and other fine denier yarns The proportion of the use of filaments has grown very fast, especially in underwear, socks and circular knitting machines; 140D/210D is widely used in lace, webbing, and socks; coarse denier silk with larger fineness is mainly used in webbing. Some brands also use spandex extensively in diapers.

2.2 Application fields of spandex

The elongation of ordinary fabrics is only 5%-25%, but in many fields, the fabrics need to have higher elongation. The human body has a large expansion and contraction change during exercise. If the clothes have a corresponding expansion and contraction ratio, the pressure on the human body is reduced when wearing, and the feeling is comfortable. The stretch rate of fabrics varies with the type of clothing. Underwear and sportswear require a larger stretch rate as the human body moves, while loose outerwear requires a lower stretch rate.

2.3 Downstream Yarn

In actual production, spandex can be used directly as bare silk, but it is mostly used as processed yarn. Depending on the type of fiber or yarn used and the processing method, spandex processed yarn can be divided into core-spun yarn, covered yarn and twisted yarn. Spandex bare yarn and processed yarn have different applications due to the difference in performance. Processed yarn is expensive though. However, it can provide better control flexibility and feel, and the scope and number of applications are growing rapidly. Spandex bare filament has high elasticity, is not easy to control, and has the problem of breakage during use, but the price is relatively low, so the number of applications is large. For example, in the total consumption of 30 kt spandex yarn in Western European countries in 1997, about 70% was used in the form of bare silk.

2.3.1 Spandex bare yarn

The bare spandex yarn is 100% spandex yarn, and the bare yarn is generally not used directly on the fabric. Most of it is produced together with other materials and requires special equipment to produce. Generally, it is mainly 22-78Dtex, which is the most widely used in knitwear. When used, it is generally interwoven with nylon yarn or polyester yarn on the knitting machine. The main application products are tights, sportswear, swimwear, stockings, pantyhose belt parts, surgical bandages, sock cuffs, cuffs, warp knitted fabrics, diapers, etc.

2.3.2 Spandex processed yarn

① Spandex Core Spun Yarn (CSY)

Spandex core-spun yarn uses spandex as the core, and the outer yarn is a yarn spun from one or several inelastic staple fibers (cotton, polyester-cotton, acrylic, polyester, etc.). The spandex yarn is not exposed, which can fully reflect the surface characteristics of the outer fiber. The cotton core-spun yarn fabric has the style, feel and performance of cotton cloth; the wool core-spun yarn fabric complements the excellent properties of the two fibers, which not only has good elasticity, but also maintains the high-grade feeling of wool fabrics; silk core-spun yarn fabrics , can also reflect the characteristics of natural silk.

Spandex core-spun yarn can be spun by processing methods such as ring spinning, air spinning, and vortex spinning. The yarn has the advantages of low spinning cost, wide yarn count range, wide outer fiber and optional elasticity. The elastic elongation of the core-spun yarn is 150%-200%, and the amount of spandex is 7%-12%, generally 22-235Dtex. Mainly, core-spun yarn such as 40D spandex wrapped with 40S cotton yarn, can be used to weave elastic denim, corduroy and knitted fabrics (neckline, cuffs, hem) and other clothing accessories.

②Spandex covered yarn (CY)

Spandex covered yarn is an elastic yarn formed by using spandex yarn as the core, and inelastic filament or short fiber yarn wrapping the stretched spandex yarn in a spiral manner. According to the number of covering layers and the number of turns per centimeter of the outer layer, it can be divided into single-covered yarn (SCY) and double-covered yarn (DCY); it can also be divided into air-covered yarn (ACY), There are two types of mechanical core-spun yarn (SCY).

The covered yarn is made of pre-stretched spandex elastic yarn through the center of the hollow spindle to become the core wire. The yarn or filament on the spindle is wound on the spandex evenly and spirally as the outer covering yarn, and then synchronously crimped. Spandex covered yarn has the characteristics of elastic elongation (300%-400%), stiff hand, thick yarn count and high strength. Covered yarn is the most commonly used variety of spandex processed yarn, accounting for about 65% of the entire processed yarn type. The outer yarn is mostly polyester, nylon or cotton yarn, and polypropylene is also used as the outer yarn.

Since the quality requirements of covered yarns are not too harsh on spandex, new domestic factories will first consider developing the spandex covered yarn market. The domestic consumption of this market is also relatively large. The following is a useful exploration of the development prospects of covered yarns in the socks industry and clothing.

2.4 Application of Spandex in Hosiery Industry

2.4.1 Nylon covered spandex yarn

At present, in the hosiery market, nylon covered spandex yarns are the main covered yarn products. It is mainly divided into orthodox etiquette socks for men, women and children, convenient socks, sports socks and ultra-thin transparent socks that are currently popular. Among them, the largest number are the stockings and pantyhose for modern women, as well as the abdominal and hip-raising socks that are popular with beauty-loving women, and ultra-thin transparent socks. These are all made of covered yarns formed by organically combining the good elasticity of spandex with the high strength and wear resistance of nylon. The product sales and prospects are very promising, which advantageously promotes the development of nylon covered yarns.