Bicomponent fibers are comprised of two polymers extruded from the same spinneret within the same filament. They can have side-by-side, sheath-core, islands-in-the-sea, or segmented pie cross-section structures. Bicomponent fibers provide capabilities like thermal bonding, self-bulking, very fine fibers, and use of special polymers at reduced cost. Common polymer combinations include polyester core with copolyester or polyethylene sheath. Major applications are in nonwovens as bonding fibers.

1. BICOMPONENT FIBERS

2. Prepared By : Mazadul Hasan sheshir
ID: 2010000400008
13th Batch (session 2009-2013)
Department : Wet Processing Technology
Email: mazadulhasan@yahoo.com
Blog : www. Textilelab.blogspot.com (visit)
Southeast University
Department Of Textile Engineering
I/A 251,252 Tejgaon Dhaka Bangladesh
Prepared By :
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3. Total Textile Process at a Glance

4. The first commercial bicomponent application in the mid 1960s
Bicomponent fibers can be defined as "extruding two polymers from the same
spinneret, that is, both polymers contained within the same filament.” The
term "conjugate fibers" is often used, particularly in Asia, as synonymous with
bicomponent fibers. Bicomponent fibers are commonly classified by their
BICOMPONENT FIBERS

5. Bicomponent fiber is comprised of two polymers of
different chemical and / or physical properties extruded
from the same spinneret with both polymers within the
same filament.
Definition:

6. 1.Side-by-Side,
2.Sheath and Core
3.Islands-in-the-Sea and
4.Segmented-pie cross-section types
5.Tipped
6.Mixed Fiber
7.Micro Fiber
fiber cross-section structures as:

9.  Uniform distribution of adhesive
 Fiber remains a part of structure and adds integrity
 Customized sheath materials to bond various materials
 Wide range of bonding temperatures
 Cleaner, environmentally friendly (no effluent)
 Recyclable
 Lamination / molding / densification of composites.
Advantages of Bicomponent Thermal Binder Fibers

10. 1. Polyester Core (250C melt point) with Copolyester Sheath (melt
points of 110C to 220C)
2. Polyester Core (250C melt point) with Polyethylene Sheath
(130C melt point)
3. Polypropylene Core (175C melt point) with Polyethylene Sheath
(130C melt point)
Common Polymer Combinations in Bicomponent Thermal Binder
Fibers

11. Bicomponents can provide:
1. Thermal bonding
2. Self bulking
3. Very fine fibers
4. Unique cross sections
5. The functionality of special polymers or additives at
reduced cost
Bicomponent Fiber Capabilities

12. POLYMERS
The polymers given below can be used as either of the components in the cross
sections
PET (polyester) PEN polyester
Nylon 6,6 PCT polyester
Polypropylene PBT polyester
Nylon 6 co-polyamides
Polylactic acid polystyrene
Acetal polyurethane
Soluble co polyester HDPE, LLDPE

13. Worldwide, Japan and Korea led in bicomponent output with a total of 200 million
pounds annually. The production of the U.S. is currently around 60 million pounds
with Hoechst Celanese holding the lead. Other U.S. players in the Bicomponent
sector include Foss manufacturing, International Polymers Inc. and Fiber Visions.
The present production of bicomponent fibers worldwide is only a fraction of the
25 million metric tons of manmade fiber market, but the producers are confident
of significant growth in the next 10 years or so .
PRODUCERS

14. These fibers contain two
components lying side-by-
side. Generally, these fibers
consist of two components
divided along the length into
two or more distinct regions.
Sheath-core Bicomponent
fibers are those fibers where
one of the componentsis fully
surrounded by the second
component.
These fibers are widely used
as bonding fibers in
Nonwoven industry.

15. MATRIX-FIBRIL BICOMPONENT FIBERS
These are also called islands-in-the-sea fibers. Technically these are complicated
structures to make and use. In cross section, they are areas of one polymer in a
matrix of a second polymer. These types of bicomponent structure facilitate the
generation of micro denier fibers. The ‘islands' are usually a melt spinnable
polymer such as nylon, polyester or polypropylene. Polystyrene water-soluble
polyesters and plasticized or saponified polyvinyl alcohol can form the sea or
matrix. The finer deniers that can be obtained are normally below 0.1 denier

16. Bicomponent Fibers Variants
Islands-in-the-Sea Islands-in-the-Sea Sixteen Segment Pie

21. Nanofibers from splitting bicomponent fibers

22. SEGMENTED PIE STRUCTURE

23. PET
Nylon
Figure
Standard pie wedge fiber

24. Nylon
PET
Figure Figure

25. Spin head of single
component spinning
Configuration of part of bicomponent
spinning equipment

26. Different Types of Nozzle part
of island-in-the-sea type fiber
Photo of the island observed
under polarizing microscope

27. Nano fibers from splitting bicomponent fibers:
Figure . Nanofibers from Bicomponent fibers .

29. This is a 10% sheath, 90% core of Co-PET/PET. In bicomponent fibers used for bonding, it is
generally desirable to minimize sheath ratio. However, due to equipment and process
limitations, most commercial products in such applications have historically used a sheath
ratio of up to ~50%. With Hills Technology, a sheath ratio of 10% or less can be commercially
produced. In addition, some Hills customers have commercially produced perfect
sheath/core fibers with spinneret orifice spacing of <1.6mm. Other equipment
manufacturers may claim to be able to offer such high hole density, but the cross-sections
they obtain are poor; the sheath ratios are high and non-uniform; and the polymer
selections useful with a specific spin pack design are very limited.
Sheath/Core Fibers, Round Cross-Section

30. Sheath/Core Fiber, Trilobal Cross-Section
This photomicrograph demonstrates our ability to produce low sheath ratios in the
complex non-round fiber cross-sections.

31. This is an example of self-bulking fibers commercialized in products where complex
jet texturing has historically been required
Side-by-Side, Trilobal Cross-Section

32. Sixteen Segment Pie
This is an example of splittable fibers for microdenier applications. In this photomicrograph
please note the high degree of perfection of the cross-sections; i.e., the segments closely
touching in the middle of each fiber, and no segment significantly sheaths another. This type
of near perfection is required to control various properties such as split-ability and dyability.
Achievement of this level of perfection requires precision in both the polymer distribution
system and the melt viscosity of the two polymers. With Hills Technology, great attention is
also paid to machine designs required to control melt viscosity. This includes properly
selecting machine materials and designs for uniform heat transfer, as well as for uniform
residence time from the initial melt to the spinneret face. We have even had to design our
own polymer prefilters to obtain the necessary uniform residence times that are not available
with commercial polymer pre-filters.

33. While 16 pie segments is the most common number we have commercialized, it is not the
limit.
As shown in this photomicrograph, equal uniformity can be achieved in commercial
applications with 36 or more segments
Thirty-Six Segment Pie

34. This cross-section was produced with a spinneret designed to produce hollow fibers.
In certain applications, these fibers can be made to split in-line with fiber extrusion.
It is also noteworthy to point out that these filaments as well as the filaments shown in
Photographs 4 and 5 were all produced on a spinneret with the orifices on ~6.0mm centers.
This is the same orifice spacing commonly used to produce homopolymer filaments of
comparable denier per filament.
Therefore, it is confirmed that with Hills Technology, these most complex bicomponent cross-
sections can now be produced at conventional machine rates.
Sixteen Segment Hollow Pie

35. Islands-in-the-Sea, 64 Islands
• The sea/island ratio shown in this fiber is 20%/80%; yet, all the islands are separated.
• This fiber was also produced on a spinneret with the orifices on ~6.0mm centers.
• In producing these filaments it is necessary to precisely meter and distribute over 65
polymer streams to each spinneret orifice.
• Hills' unique micromachining capabilities and knowledge of polymer flows make this
possible at the high spinneret orifice density.

36. In June 1999, Hills extended its capabilities to produce INS fibers to higher island counts.
This photomicrograph shows 600 polypropylene islands in a sea of PVA polymer. The
polymer ratio is 30%/70%.After being spun the fiber is drawn and the PVA polymer is
dissolved away with hot water. The fiber shown was produced in this manner and then
dipped in a cup of boiling water leaving the 600 island fibers in the area exposed to the hot
water and a single solid filament in the area not exposed to the hot water. This technique as
been used to produce fibers on 6 mm hole centers with over 1100 island fibers in each
filament. When drawn, final total filament denier of 1 dpf was produced, resulting in island
fibers of approximately 500 nanometer diameter. Basically, these fibers are spun from the
mixture of two polymers in the required proportion; where one polymer is suspended in
droplet form in the second melt. An important feature in production of matrix-fibril fibers is
the necessity for artificial cooling of the fiber immediately below the spinneret orifices.
Different spinnability of the two components would almost disable the spinnability of the
mixture, except for low concentration mixtures (less than 20%).
600 Island-in-the-Sea

37. 1. Thermal bonding
2. Self bulking
3. Very fine fibers
4. Unique cross sections
5. The functionality of special polymers or additives at reduced cost
Bicomponent Fiber Capabilities:

38. 1. Uniform distribution of adhesive
2. Fiber remains a part of structure and adds integrity
3. Customized sheath materials to bond various materials
4. Wide range of bonding temperatures
5. Cleaner, environmentally friendly (no effluent)
6. Recyclable
7. Lamination / molding / densification of composites.
Advantages of Bicomponent Thermal Binder Fibers:

39. There are far too many different end-uses for bicomponent fibers to cover in a brief article,
but a few illustrative examples are discussed below.
Even the basic sheath/core binder fiber has been updated since the early days. Today, there is
access to a range of copolymers of polyesters, polyamides, and polyolefins that allow precise
targeting of the desired thermal bonding behavior.
The bonding temperature can be set from a low of about 110°C to a high of about 180°C. It is
even possible to select bonding polymers outside this range, but these options can impose
significant caveats.
Beyond the bonding temperature, the adhesive character of the bonding polymer can be
adjusted to adhere better to polar surfaces or nonpolar ones. And the crystalline nature of the
polymer can be adjusted to give a broader or narrower melt-temperature range. Binder fibers
for high-loft nonwovens used as seat cushions in place of polyurethane foam use a sheath
polymer with elastic recovery, so that repeated stressing of the bond points does not fracture
the bond.
Uses Of Bicomponent Fibers:

40. The fundamental sheath/core cross section is also useful in many applications
demanding engineering polymers.
Typically, such an application depends entirely on the surface properties of the more
exotic, and more expensive, polymer. In these cases, the fiber's core can be made with a
suitable lower-cost polymer to deliver all of the benefit of the more expensive polymer at
a materials cost well below that of a fiber made from the surface polymer alone.
Side-by-side bicomponent fibers typically rely on the difference in shrinkage between the
two polymers.
At any point in the fabric formation process, if the fibers are not physically constrained,
shrinkage can be induced by the application of heat. Since the two polymers shrink at
different rates, the fiber resolves the resulting tension by curling into a helix.
This behavior allows a fabric to be made flat and then bulked when and where it suits the
application.
Uses Of Bicomponent Fibers:

41. The pie wedge cross sections typically are used to make microfibers. Direct spinning of
microfibers is difficult - and practically impossible below about 0.3 to 0.5 denier per filament
(dpf) - and expensive, as throughputs are low. But a 2- to 3-dpf pie-wedge fiber does not
suffer throughput limitations, and is robust through fiber and fabric production processes.
Once a nonwoven web is formed from these fibers, it can be subjected to mechanical
agitation - typically, a hydroentangling process - which will split the segments into
microfibers - typically, about 16 segments per bicomponent fiber.
The result is a microfiber fabric at significantly reduced cost compared to one made using
direct-spun microfibers. The hollow and partial-wrap versions of this cross section are
refinements that allow adjustment of the fiber's relative splittability.
Uses Of Bicomponent Fibers:

42. Finally, the entire range of polymer additives that can be used in single-polymer fibers can
also be used in one or both of the polymers in a bicomponent fiber to achieve targeted
performance characteristics. These additives include such things as colorants, flame
retardants, antimicrobials, conductive materials and carbon nanotubes, among other
additives.
With this very large matrix of material properties and ways of combining them into each
fiber, it will be apparent that bicomponent fibers are no longer a one-trick pony. Whereas
in the past, fabric design meant trying to optimize the fixed attributes of a commodity fiber
into each different application, bicomponent fibers now offer a way to engineer finely-
tuned performance into the fiber. Each application can now seek a fiber that is precisely
tailored to fit the specific needs of that application.
Conclusion:

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