Crimp texturing

Texturing. The final step in olefin fiber production is texturing the method depends primarily on the appHcation. For carpet and upholstery, the fiber is usually bulked, a procedure in which fiber is deformed by hot air or steam jet turbulence in a no22le and deposited on a moving screen to cool. The fiber takes on a three-dimensional crimp that aids in developing bulk and coverage in the final fabric. Stuffer box crimping, a process in which heated tow is overfed into a restricted oudet box, imparts a two-dimensional sawtooth crimp commonly found in olefin staple used in carded nonwovens and upholstery yams. 

Bicomponent fibers have also provided a route to self-texturing (self-crimping) fibers. The crimp results from the length differential developed during processing caused by differential shrinkage in the two polymers in side-by-side or eccentric core—sheath configurations (50). 

Even when crimp is fiiUy developed it is easy to pull out (low energy) and difficult to translate into noticeably bulkier woven and knitted fabrics. It does however improve the absorbency and the cohesion of the staple (important in spun-yam and nonwoven making) and gives a subtiy different texture... 

Combinations of two or more of the above steps into consecutive processes, such as spin—draw or spin—draw—texture, reduces manufacturing costs. In addition to continuous-fHament yam, nylon is also offered in staple, tow, and flock forms. Staple is made by cutting crimped continuous-fHament yam into 3—20-cm lengths. In manufacturing, tow is made by combining many yam ends, either flat or crimped, to give a total tow size of 6—111 ktex. 

PTT POY yams were textured by the false-twist method at 140 to 160 °C. Crimp development was almost twice as high as PET, with crimp contraction reaching about 50 %. When PTT yams with a high level of crimp contraction are knitted into stretch fabrics, the amount of stretch achieved is equivalent to PET stretch fabrics incorporated with 6 to 8 % of Spandex [89], In addition to stretch, PTT fabrics tend to have softer hand and better drape than PET. Since they do not absorb moisture like nylon, PTT fabrics also have a desirable dry touch and comfort. 

The upper curve of the textured polyester is typical for crimped fibers of doubleknit fabric and sweaters. Here, the... 

The influence of the intrinsic polymer properties on the yam bulkiness is relatively small (low density and high stiffness are favourable) in contrast with that of the fibre, yarn and cloth constructions. Hence the significance of texturing (crimping) processes, which impart a greater bulkiness (crimp) to the compact filament yam. 

Conventional, low-speed spun fibers must be further finished by drawing, although POY yarns are typically draw texturized. The drawing process adds strength by orientation of the molecular structures. Normal extensibility and proper tenacity are added by drawing the spun fibers to several times their as-spun length. The texturing process produces permanent crimp, loops, coils, or crinkles in the yarn that result in properties of stretch, bulk, absorbency, and improved hand (32). There are three basic types of... 

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