Bulking and Texturizing, Staple Formation of Textile Fiber

Thermoplastic synthetic fibers will be for good heat set after drawing and orientation. The fiber can possess structural integrity and can’t shrink up to it setting temperature. Also, thermoplastic fibers or yarns from these fibers will be texturized to provide three-dimensional loft and bulkiness:

1.        Through fiber deformation and setting at or close to their softening temperature.

2.        Through air entanglement.

3.        Through differential setting among fibers or yarns (Table).

Schematic representations of those methods are given in Fig.

·        Heat-Setting Techniques.

Six heat-setting techniques are presently in use.

·        False Twist Heat-Setting Technique.

The false twist heat-setting technique is extremely speedy, cheap, and also the most generally used. The filament fiber tow is brought in touch with a high-speed spindle running vertically to the moving tow. This action leads to a high twist within the tow up to the spindle. The twisted tow is heated close to its softening purpose before passing the spindle, then cooled, and straight to offer a wavy, bulky yarn.

Heat-setting Techniques	Air Entanglement	Differential Setting
False twist Knife edge Stuffer box Gear crimping Auto twist Knit-de-knit	Air Jet	Bicomponent-biconstituent Fiber orientation Heat shrinkage of thermoplastic fibers in a blend

 

Fig: Texurizing Methods

     Knife-Edge Texturizing.

In knife-edge texturizing, filament tows or yams below tension are ignored a heated knife edge. The fibers close to the knife edge are modified in overall orientation in relevance the unheated yarns or portion of the filaments far from the knife edge, thereby inflicting bulking of the yarn.

Stuffer Box Texturizing.

In stuffer box texturizing, the filament tow is fed into a heated box, inflicting the tow to double up against itself On removal, the cooled tow retains the zigzag configuration caused by the process.

Gear Crimping.

Geared crimping, the tow is passed between heated intermeshing gears. On cooling, the fibers retain the form induced by the heated gears.

Autotwisting.

In autotwisting, two tows or yarns are twisted along then heat set. On untwisting, the yams have equal, however opposite twists that cause a spiral bulking of the yarn.

Knit-de-Knit.

Within the knit-de-knit process, a yarn is fill-knitted, heat set, cooled, and de-knitted to provide a bulked yarn retaining the form and curvature of the knit.

Air entanglement.

In air entanglement texturizing, a fiber tow is loosely fed into and through a restricted area and a high-speed air jet is impinged on the fibers at a 45° angle. The loose fibers among the tow are looped to provide a texturized result.

 Differential Setting.

Heat shrinkage techniques cause a bulking of fiber tows containing totally different fibers through heating one part of the mix sufficiently to cause heat shrinkage of the fiber and compaction, contraction, and bulking. Side-by-side bicomponent and biconstituent fibers recover completely different degrees on all sides from fiber stretching inflicting a waving, crimping, or bulking of the fiber.

Staple Formation

Continuous filaments will be cut into staple by wet or dry cutting techniques. In wet cutting, the wet-spun fiber is cut to uniform lengths right after spinning, whereas dry cutting involves partial cutting, debonding, and shuffling of the dry tow to create a sliver. Before the filament or staple is employed in yarn spinning, spin finishes are added to provide lubricity and antistatic characteristics to the fibers and to provide a larger degree of fiber cohesiveness. The finishes are typically mixtures including such materials as fatty acid esters, mineral oils, synthetic esters, silicones, cationic amines, phosphate esters, emulsifiers, and/or nonionic surfactants. Spin finishes are developed to be oxidation resistant, to be simply removed by scouring, to provide a controlled viscosity, to be stable to corrosion, to resist odor and color formation, and to be nonvolatile and without delay emulsifiable.