Low-pilling fibers

Low-pilling fibers are common used on a la scale espedally in blends with cotton, wool, and othor synthetic fibers, for the manufacture of soft fabrics, knits, pQe, and in othm areas. 

Copolyesters containing strong acid groups generally have a lower molecular weight and a higher melt viscosity than standard PET. They can also be used Ccht the manufacture of low-pilling fibers (see Secticm 2.3). 

Greater success was achieved by DuPont who copolymerized, the sodium salt of 5-sulfoisophthalic acid into PET to render the polymer dyeable with cationic (basic) dyes. Basic dyeable PET was successfully launched as Dacron 64 in the form of a low-pill staple product [64]. The presence of the sulfonate groups in the polymer chain also acts as an ionic dipolar cross-link and increases the melt viscosity of the polymer quite markedly. Thus, it is possible to melt-spin polymer with IV 0.56 under normal conditions, giving a low-pill fiber variant. The fiber also has a greater affinity for disperse dyes due to the disruption of the PET structure. Continuing this theme, there are deep dye variant PET fibers, often used in PET carpet yarns, which are copolymers of PET with chain-disrupting copolymer units like polyethylene adipate. They have less crystallinity and a lower Tg. therefore, they may be dyed at the boil without the use of pressure equipment or carrier at the cost of some loss of fiber physical properties. 

Properties Fine fiber unstabilized Fine fiber stabilized Wool type normal Wool type low-pilling... 

In recent times TROL-type PO fibers—showing good behavior up to 125°C—have also been obtained, in low amounts [50]. PO fibers pilling effect takes average values, while wrinkling depends on the fibers fineness (being generally quite pronounced). 

The cotton fiber has sufficient strength in the dry and wet states to make it suitable for most consumer textile applications. The increased strength of cotton on wetting adds to its long useful life. Cotton wears well without undue abrasion, and pills do not tend to fomi as it wears. Cotton s low resiliency and poor recovery from deformation means that it wrinkles easily in both the dry and wet states and exhibits inferior crease retention. Starching of cotton improves these properties, but the effect is only temporary, and it is necessary to renew this finish after each laundering. 

The low to moderate strength of wool fibers is compensated for by its good stretch and recovery properties. Wool is fairly abrasion resistant and does not tend to forni pills due to its low strength. It resists wrinkling except under warni, moist conditions. Its crease retention is poor unless creases have been set using chemical reducing agents. 

The degree of polymerization or the molecular weight of the polymers on which manufactured fibers are based can be controlled as part of one of the early steps in the process. The polymer molecular weight chosen for a fiber has a strong influence on process economics, ease of conversion to fiber, and end-use performance. Commercially acceptable fibers are based on the best balance of these factors. However, in fabrics that are open in texture and made from standard polyester staple spun yarns of low twist, a condition known as pilling will develop as a result of wearing. The pills are made up of fiber ends that have worked loose from the yarn bundles as a result... 

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