Polyurethane core-spun yarn is a yarn spun with spandex yarn as the core and one or more non-elastic short fibers wrapped around it. The core yarn of the core-spun yarn is surrounded by the outer fiber, and the two are closely combined. The core yarn has the same twist as the outer fiber.

It has three remarkable characteristics: first, it has the same feel and appearance as the wrapped fibers (cotton, wool, polyester, cotton, etc.), and the sheath composed of natural fibers has good hygroscopicity; Second, good elasticity; Third, the elastic percentage can be controlled below 20%.

Covered yarn is also called wrapped yarn, and one of the most obvious differences between covered yarn and other elastic yarns is that the core yarn has no twist. The core-sheath relationship between spandex yarn and outer covering is obvious, but the degree of cohesion between core yarn and outer covering is obviously lower than that of core-spun yarn and twisted yarn, so its elasticity is higher than the former two. The elongation can reach 200% (double-wrapped yarn), and the elasticity can be about 50% in high elastic fabric.