Cooling staple

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. 

Terephthahc acid (TA) or dimethyl terephthalate [120-61 -6] (DMT) reacts with ethyleae glycol (2G) to form bis(2-hydroxyethyl) terephthalate [959-26-2] (BHET) which is coadeasatioa polymerized to PET with the elimination of 2G. Moltea polymer is extmded through a die (spinneret) forming filaments that are solidified by air cooling. Combinations of stress, strain, and thermal treatments are appHed to the filaments to orient and crystallize the molecular chains. These steps develop the fiber properties required for specific uses. The two general physical forms of PET fibers are continuous filament and cut staple. 

Figure 12.11 Schematic of a modern staple drawline for PET fibers 1, spun yarn supply cans 2, lubricating bath 3, two-stage drawing 4, heatsetting 5, cooling 6, reheating 7, crimping 8, dyeing 9, cutting 10, baling...

Figure 1-26. Flowchart showing steps in the manufacture of nylon 6, 6. facture of nylon 6,6. Specific amounts of the two chemicals are combined in solution to form nylon salt. The salt is purified, polymerised, extruded in ribbon form and chipped into small flakes or pellets. The polymer is then melted and extruded through a spinnerette into cool air, where the filaments are formed. The filaments are then stretched or cold drawn to develop desired properties. Nylon staple is obtained by crimping filament tow and then cutting into short uniform lengths.

In addition to the category of heating or cooling, a large variety of foods including staple foods like plain rice, noodles, and steamed buns, are categorized as neutral... 

There are several process requirements for the preparation of polypropylene staple with permanent three-dimensional helical curvature. Specifically, a rectangular spinneret-pack assembly is used to produce flow perturbation and to impart high internal stress. A specially designed cooling device cools the fiber quickly to form a paracrystalline structure in the fiber. The process principle is that the flow perturbed in the polypropylene melt creates internal stress on one side of the fiber section. Because of the stress memory of polypropylene, the internal stress difference at the interface of streamlined and perturbed flows can sustain in the fiber after it has been cooled and solidified. This leads to different crystal structures and shrink properties, and thus a fiber in the shape of a three-dimensional helix. 

Figure 2 Spinning section of a compact spinning plant for polypropylene staple fibers 1, cooling air 2, ring spinneret 3, threads 4, 5, rollers 6, take up.

Fig. 10. Staple fiber line (1) spim yam supply cans, (2) lubricating bath, (3) two-stage drawing, (4) heatsetting, (5) cooling, (6) reheating, (7) crimping, (8) drying, (9) cutting, and (10) baling.

In this process, as the filaments exit the spinneret they immediately pass in front of a cold air blower, which rapidly cools and solidifies the strands. Then they travel down to a series of advancing rollers, which guide the filaments through various processes, such as stretching, crimping, heat setting, etc., before they are wound up as rolls of continuous filaments or cut into short staple fibers. 

The technology used to manufacture ICS yams evolved over several years and different prototype machines. While the concept of the final version may have been part of the original vision, it is evident that several alternative approaches were also tried. The key feature of the earlier proposals was to embed staple fibers into an extruded, but not fuUy cooled, thermoplastic... 

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