The yarn is made from two kinds of different shrinkage polymers in each filament, and the yarn after heat treatment become spiral structure. In the other words, the mechanical stretch has stretch property, but without spandex. It’s not a new technology, but why it has been become a popular issue in recent years? This is related to people has started to concern about recycle issue. The first step of improvement is from production, then dyestuff and yarn. Many brands even have announced they will carry out the garment recycle in the near future. However, it can’t be recycled if spandex is involved in fabrics, because spandex can’t be biodegradable.
Comparing with mechanical stretch yarn and spandex, mechanical stretch yarn only can replace around 4%~6% of spandex. However, it is already enough for most of sportswear except yoga wear or something need super stretch wear. Besides, mechanical stretch fabrics are 100% polyester or 100% nylon, so the color fastness is better than the other fabrics which are composed by spandex. Generally to say, dyeing spandex fabrics and 100% polyester fabrics are also different. If dyeing spandex fabrics, it needs scouring and bleaching before dyeing. However, it means more water and energy will be used. Dyeing mechanical stretch fabrics will not have this problem due to the dyeing process is as same as 100% polyester fabrics. It can be at least more energy efficient than spandex fabrics.
Mechanical Stretch Fabric VS Regular Polyester Fabric VS Spandex Fabric
Source: www.npc.com.tw, www.singtex.com