Single Step System for Core Wrappped Yarn

WASHINGTON - May 14/02 - SNS -- The USDA holds a patent on a system for producing core wrapped yarn in a single step for a 10-fold increase in productivity, which it is making available for licensing.

Called tandem spinning, it combines two different spinning technologies and the USDA claims it produces soft, yet strong, bicomponent yarn. It was developed by Agricultural Research Service scientists at the Southern Regional Research Center (SRRC) in New Orleans, La.

To improve the strength or performance of fabrics, many textile manufacturers combine two fiber classes, such as cotton and polyester, into one strand of yarn. Fabrics made from such yarn are called intimate blends. Although stronger than 100 percent cotton, these intimate-blend fabrics sometimes exhibit undesirable properties. For example, they frequently pill, or make lint balls on their surface as they wear, and they do not provide the comfort of a 100-percent-cotton surface.

A few years ago, scientists at the SRRC developed new spinning technologies to form bicomponent, or "core-wrap," yarn in which the core material is usually a strong, synthetic fiber and the wrap/sheath is 100 percent cotton. The core contributes excellent mechanical and functional properties to the yarn, such as wrinkle resistance, and the cotton wrap provides the desired comfort characteristics. Fabric made from core-wrap yarn has added strength because of the yarn's synthetic core, yet it maintains the soft texture of cotton.

To increase the productivity of core-wrap spinning, SRRC scientists, led by cotton technologist Paul Sawhney, successfully developed a tandem spinning system. The resulting yarn is exceptionally soft and well-covered and is produced at a speed at least 10 times greater than that allowed by the conventional method.

In a test at SRRC, a prototype of the tandem spinning system produced a bicomponent yarn with a polyester core and a cotton sheath. The yarn was converted to twill fabric that had an almost 100-percent-cotton surface. After it was heat-set, the fabric showed unusual properties of softness, satisfactory shrink resistance and acceptable wrinkle resistance upon laundering.