Microfilament Yarns Take Hold


M
icrofibers have been produced on an industrial scale since 1970. For many years they were
manufactured exclusively for high-priced specialty articles such as imitation leather, extremely
high-density sportswear and high-performance cleaning cloths. Thus, the production of microfilament
yarns worldwide had yet to reach 100,000 metric tons per year by 1992.

In recent years, however, microfilament yarns have experienced an unbelievably sustained
boom in that they have been applied to high-value, but attractively priced, stylish silk-like
garments. By 2004, annual production had risen significantly above 1 million metric tons and it
continues to increase. The main producers of microfibers today are found in the Far East —
predominantly in Japan, Taiwan and Korea; and increasingly also in China.

China, Taiwan and Korea together produce 870,000 metric tons of microfilament yarn — a
73.8-percent share of the amount produced worldwide.

Almost all microfilament yarns are spun from partially oriented yarn and subsequently
false-twist drawn textured yarn (DTY). They range in count from 33 decitex (dtex) to 200 dtex with
filaments from 0.90 denier per filament (dpf) to 0.52 dpf. The trend is to even finer filaments
down to 0.24 dpf.

It goes without saying that the manufacture of microfilament yarns is much more demanding
than that of standard yarns. The yarn quality required for efficient further processing demands a
superior polymer quality; optimized process technology; outstanding yarn preparation; and, above
all, an intermingling designed for the processes described below.

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Figure A (top) shows typical microfilament yarn compaction and Figure B shows yarn
compaction when Heberlein Fiber Technology Inc.’s MigraJet® technology is used during
processing.


Intermingled Microfilament Yarns

A significant step in the improvement of microfilament yarn quality, especially yarn
cleanliness during spinning, was achieved by the development of the MigraJet™ migration jet by
Switzerland-based Heberlein Fiber Technology Inc. Its application provides for a reduction in the
number of yarn breaks. The MigraJet compacts the individual filaments of the yarn and thereby
achieves an exact spacing between the thread lines. It also causes an even spreading of the spin
finish into the center of the yarn.

For trouble-free processing and a homogeneous woven fabric appearance, a high number of
knots and, generally, a soft, gentle, uniform interlacing are necessary.

In some markets, such as India and China, a more stable interlacing is often also demanded.
These quality criteria are not achieved by the interlacing jets that have been available up to now.
These traditional jets produce insufficient interlacing knots at low pressure without the required
regularity.

The jet plates of the new series 4 (142-2) — specially developed for this application with
the patent-pending Air Twist Chamber (ATC) for use in the SlideJet™-FT15-2/P142-2 — meet these
requirements. The P142-2 jet plate at 1.2 bar pressure achieves more than 120 very regular
interlacing knots. The air consumption in the high stability range is approximately 20-percent
lower than previous models.

Significant savings of spin finish are achieved compared with roll or weir application. The
MigraJet causes the filaments to intermingle without interlacing knots. This also has a positive
influence on drawing quality.


Microfilament Yarns Have Found Their Niche

Textured polyester microfilament yarns have established themselves with a solid 14 percent
of the total DTY market. Under the aspect of rapidly growing polyester textured yarn production,
that is more than remarkable.

This development can no longer be seen only as a specialty or short-term fashion example.
Rather, it shows a strong upward trend. This also is because consumption of this yarn not only is
limited to a few niches, but also is widely supported already in the outerwear sector.

The manufacture of fault-free microfilament yarns for further processing without
interruption necessitates corresponding adjustments in spinning and false-twist texturing. The
correct yarn compaction is especially important.

In spinning, the MigraJet provides yarn interlacing without knots and enables significant
savings and an improved spreading of the spin finish.

The SlideJet-FT15-2/P142-2 interlacing jet, developed for this yarn category in texturing,
sets new standards not hitherto reached. It is the only jet that achieves such an intensive, soft
but nevertheless regular interlacing at less than 1 bar air pressure.


Editor’s Note: Ferdinand Bösch is responsible for marketing coordination at Heberlein Fiber
Technology Inc.





January/February 2006
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