Traditional thick-count twill denim fabrics are generally made of pure cotton or weft elastic fabrics. Pure cotton fabrics are inelastic and easy to wrinkle. Although cotton fabrics are comfortable and breathable, their warp and weft The application fields of pure cotton denim fabrics are greatly limited due to their lack of elasticity.

Weft elastic denim fabric generally uses white spandex core-spun yarn as the middle weft yarn, and the outer yarn is generally cotton or linen , viscose or other short fiber yarns, and the application of spandex elastic fiber brings more functional choices to denim fabrics. Its good stretchability, lightness and comfort improve the added value of denim fabrics. The warp and weft two-way four-way stretch fabrics Compared with weft elastic fabric, it has superior wearing performance, giving consumers a wearing experience of free stretching and continuous shape retention.

However, with the increased use of polyester fibers, viscose fibers and various other fiber blends in denim fabrics, Loss of elasticity in trouser seams has become one of the most serious quality challenges faced by the denim industry. Loss of elasticity in trouser seams will cause wrinkling and deformation of the fabric surface, thereby affecting the appearance of the fabric. This will not only cause consumer dissatisfaction with quality and aesthetics, but also cause It will also cause product rejection and return.

Spandex is not resistant to chlorine bleaching, high temperature, and is soluble in some chemical treatment agents. It has been washed with enzymes and sand. After washing processes such as , rinsing and rinsing, it is easy to cause the elasticity and loss of elasticity of the spandex fiber in the fabric. The elasticity of the spandex fiber in the denim fabric directly determines the progress of denim washing in the finishing process. The spandex fiber in the denim fabric is mainly The problems faced include bullet loss, slippage, dimensional stability and other issues.

The slip-elastic phenomenon of spandex refers to the gap between the core yarn and the outer yarn of the core-spun yarn Relative sliding occurs due to insufficient friction, which is detrimental to fabric performance. Especially at the stitching positions of denim products, sewing needles are required for threading and sewing, which can easily lead to slippage of the spandex core yarn and even surface damage. The spandex core Yarn slippage will cause the fabric to be uneven at the seam location, affecting the appearance of the garment. Today, the slippage of spandex fibers in denim fabrics is generally achieved by adjusting the fabric structure or the performance of the spandex-wrapped yarn.

For example, the dual-core yarn elastic fabric mentioned in the published patent is to cover the filament on the surface of the spandex core yarn between the core yarn and the outer covering yarn. This increases the friction between the fiber and the yarn, making it difficult for the spandex to come out easily; and the adjustment of the fabric structure is generally achieved by adjusting the density of warp and weft yarns or the tightness of the tissue. The core-spun yarn and the outer yarn can be single-wrapped. Increase the degree of twisting, or use double-wrapping technology and double fixation to reduce spandex slippage.

Of course, the anti-slip effect can also be improved by improving the properties of spandex raw silk. The key point is By adjusting the content of different types of additives in the polymerization process and using an oil with a higher friction coefficient in the spinning process, the friction properties of the spandex fiber surface are improved, and the relative friction between the spandex fiber and the outer yarn is increased, thereby preventing the spandex fiber from being damaged. The relative slippage between the spandex core-spun yarn and the outsourcing yarn is used to improve the slippage phenomenon of spandex, and combined with other anti-slip elasticity measures in the weaving process, such as increasing the twist of the spandex core-spun yarn, the outsourcing fiber generates greater centripetal pressure, further Increase the friction between the outer fiber and the spandex core yarn to meet the requirements of the special field of denim fabrics.

In addition, modification of raw material ends such as PTMEG during production is also an effective means to prepare spandex with anti-slip elastic properties.

For example, the comfortable spandex (PT SOFT) based on PolyTHF™Inside jointly launched by Hangzhou Federation and BASF uses raw material chemical grade innovationBASF has innovated and changed raw materials at the molecular level, combined with Hangzhou Federation’s unique production process, to jointly develop high-quality special spandex products, including customized anti-slip PT spandex for denim.

And LYCRA® (Lycra®) Anti-Slip anti-slip elastic fiber is also a kind of special filament structure and proprietary chemical composition Spandex fiber has higher adhesion and friction, and has the same tensile force and recovery force as LYCRA® (Lycra®) fiber. It can effectively prevent the seams of fabric edges from slipping and can be used in the development and development of a variety of fabrics. Construction, including open construction, polyester/viscose blends and cotton blends, combines anti-slip elastic properties with excellent shrinkage, residual elongation and recovery performance, providing a soft feel and natural appearance.