Production of stretch yarn

Stretch filament yarn has advantage of eveness,good elongation of breakage,excellent stretch,high strength,however,it is also has bad moisture absortion,bright surface,hard hand feeling and tends to pill, Moreover,the price of filament yarn is often times higher than normal fibers,and it is difficult to control the width and shrinkage when weaving due to its elasticity.thus,it is not normally singly used but often combined with other fibers as core spun yarn,covered yarn,twisted yarn and texturised yarn.

1.core spun yarn There are many kinds of core spun yarn,stretch core spun yarn most widely used,it consists of core yarn and sheath yarn.Core yarn is filament yarn such as spendax,PTT,PBT,DOW XLA,etc.Cover yarn has natural fiber such as cotton,wool,silk,bean composite fibers, Modal,Tencel,bean fiber,bamboo fiber,etc.

1.1 strcture of stretch core spun yarn Stretch core yarn gives elasticity,sheath yarn has surface feature,fibers can be chosen according to application and requirement of fibers.The finess of fiber is 10-60tex.

With good elasticity and easy control,can be give full play of covered yarn's surface feature,it have wide application due to its comfort,fitness and moisture absortion and applied to woven machine,knitting machine and warp knitting.

Normally used on denim fabrics, corduroy,knitting fabrics and for the development of high end stretch textile such as socks,underwear,medical bandage,intimate appare.

The disadvantage is cost of development is high and the production volumn rate is low.

2.The process of stretch core spun yarn: Roving—Draft---twist and winder—spooling—steaming Elastic filament—pre-draft Pre-draw ratio is 3-4.5,over drawing will cause breakage of yarn

3. Quality properties of stretch core spun yarn Phisical property:linear density,tensile strength,ratio of eveness,content of spandex,twist degree and irregularity of twist.