Teaching Materials Hanur Meku Yesuf EiTEX-Bahir Dar University

1. The wide range of manufacturing methods for nonwovens
permits the use of all commercially available fibers:
 Natural fibers,
 Man-made fibers (regenerated and synthetic )
The choice of fiber depends on :
 The required profile of the fabric (end use)
 The productivity techniques or methods
 The cost effectiveness
CHAPTER-2 : RAW MATERIALS
2.1: Fibers
1

2. A. Natural fibers
Vegetable fibers: cotton is the most important vegetable fiber
used to produce nonwoven bonded fabrics
Animal fibers: of all the animal only sheep’s wool is of any
importance for the production of nonwoven bonded fabrics
B. Man-made fibers
Synthetic organic fibers predominate the raw material for
nonwoven fabric production:
• Polypropylene
• Polyester
• Viscose
• Polyamide
2
Cont’d

3. The advantages of application of man-made fibers and particularly
of the synthetic fibers in the production of NWFs may be summed up
as following:
• Uniformity and cleanness of fibers
• Free selection of cut length and fineness of fibers
• Resistance to abrasion ( mainly in carpets and floor coverings)
• Elasticity (e.g. In elastic garments interlines)
• Resistance to aggressive environmental microorganisms and
specific solvents
• Free selection of cross section (profile) –surface smoothness,
crimp, etc. of the fibers.
• Free choice of shrinkage due to the effect of higher temperature
and environment
3
Cont’d

4.  Fibre characteristics (fibre diameter, fibre length, fibre tensile
properties, fibre finish and crimp) not only influence fabric
properties but also processing performance:
 Web cohesion
 fibre breakage
 nep formation
 web weight uniformity
 In selecting of fiber for use in NWFs the following fiber
descriptions are important and determination is based on the
requirements of the finished product:
 Crimp, Length, Deniers per filament and Finish
Cont’d
4

5. Crimp
 Almost impossible to produce NWFs from completely straight
fiber because crimp is necessary for formation of manageable
web for NWFs production.
 Highly crimped fibers tend to form more uniform web which
will retain its original structure during the subsequent process.
 During the production of man-made fibers, crimp is introduced
to increase web cohesion, bulk and sometimes elastic
recovery.
 The crimp shape and frequency as well as its uniformity
depend on the manufacturing conditions.
5
Cont’d

6. Denier per Filament
 Use of the finer fibers results in great density, strength
and softness and at the same time a more opaque sheet
(fine fiber has more covering power)
 Heavy deniers are easy to open for the production of a
uniform web at higher speeds than finer fibers.
 The adjustment of the processing equipment is very
important factor in successful production of NWFs
depending on fiber denier.
6
Cont’d

7. Length
 The staple length of the fiber to be used depends on
the type of web forming equipment.
 There is no advantage in fabric strength derived from
longer fiber.
 Use of longer fiber results:
 Excessive breakage
 Low production rates
 Poor fabric quality
7
Cont’d

8. 8
Finish
 The finish on the fiber surface is usually designated as
“bright”, “dull” or “semi-dull” and the selection is
depending on the luster or appearance desired in the
end product.
 Fibre finish modifies both fibre to fibre friction
(cohesion) and fibre to metal friction (holding power of
the wire) during carding.
Cont’d

9.  Polypropylene, polyester, and viscose fibers account for
more than 80% of consumption in Western Europe.
 Synthetic inorganic fibers (e.g. glass or mineral fibers )
are less important as raw material for nonwoven
production.
 The fibers are incorporated into the nonwovens either in
pure form or as mixtures in accordance with the
required end-use properties and the manufacturing
methods employed.
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10.  Cotton today is the most used textile fiber in the world.
 Its current market share is 56 percent
 Some properties of cotton that make it suitable for NWFs
production are:
 Good Absorbency
 Vapor permeability
 Biodegradability
 Low electrostatic build up
 Good bulk and bonding properties
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A. COTTON
 Soft Handle
 Good Wicking
 Good cover
 Crimp retention

11.  Some application areas of cotton NWFs are the following:
 Apparel: blouses, shirts, dresses, children’s wear, swimwear, suits,
jackets, skirts, pants, …
 Home Fashion:- curtains, bedspreads, comforters, sheets, towels,
table cloths, table mats, napkins
 Acoustic Insulation: cotton based needle punched NWFs used as a
backing material in tufted carpet for noise absorption.
 Geotextile: cotton canvas used to reduce the lateral force exerted
behind retaining wall; and Cotton duck used to stabilize dirt roads.
 Filtration:
 Medical/surgical and health care products
11
Cont’d

12.  Generally Polyester Fibers have the following properties:
Strong
Mildew resistant
Abrasion resistant
Retains heat-set pleats and crease
Resistant to stretching and shrinking
Resistant to most chemicals
Easy process ability
Easily washed
Quick drying
Crisp and resilient
Wrinkle resistant
B. POLYESTER
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13.  Some application areas of polyester NWFs are the following:
 Apparel: every form of clothing
 Home furnishings: carpets, curtains, sheets and pillow cases, wall
coverings,
 Medical: providing a breathable barrier between the surgeon and the
patient, which serves to significantly reduce hospital infections
 Filters and insulation materials
 Automotive seats
 Agricultural crop covers
 Interlinings,
 Coating substrates,
 Support materials for tufted carpets
13
Cont’d

14. ♣ Generally Viscose Fibers have the following properties
♥ Highly absorbent
♥ Soft and comfortable
♥ Easy to dye
♥ Drapes well
♣ Applications of Rayon Fiber
♥ Apparel: blouses, dresses, jackets, linings, millinery,
sportswear, suits, ties, work clothes, wipe (cleaning) cloths
♥ Home Furnishings: Bedspreads, blankets, curtains, sheets,
tablecloths,
♥ Industrial Uses: Industrial products, medical surgical
products, non-woven products, tire cord
♥ Other Uses: Feminine hygiene products.
C. VISCOSE RAYON
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15. ♣ It is a polyamide fiber.
♣ Generally polyamide fibers have the following properties
♥ Extremely chemically stable
♥ No mildew or bacterial effects
♥ Permanent set by heat and steam
♥ Abrasion resistant
♥ Lustrous
♥ Easy to wash
♥ Resilient
♥ smooth, soft, long lasting fabrics
D. NYLON / POLYAMIDE
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16. ♣ Some particular applications of nylon are as follows:
♥ Garment interlinings and wipes
♥ Non-wovens separators in batteries
♥ Heat insulators
♥ Automotive products
♥ Athletic wear
♥ Conveyor belts
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Cont’d

17. ♣ Olefin fiber is a generic description that covers thermoplastic
fibers derived from olefins.
♣ Olefins are products of the polymerization of propylene and
ethylene gases.
♣ Polypropylene (PP) and polyethylene (PE) are the two most
common members of the family.
♣ Polypropylene is extremely versatile as a fiber-forming
material, whereas polyethylene is not as good fiber-forming
high polymer material.
E. OLEFINS
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18. ♣ Characteristics of Olefin Fibers
♥ Good bulk and cover,
♥ Very lightweight (olefin fibers have the lowest specific gravity
of all fibers)
♥ High strength( wet or dry)
♥ Resistant to deterioration from chemicals, mildew, insects,
perspiration, rot and weather
♥ Abrasion resistant
♥ Low moisture absorption
♥ Stain and soil resistant
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Cont’d

19. ♥ Sunlight resistant
♥ Good washability, quick drying, unique wicking
♥ Resilient, moldable, very comfortable
♥ Thermally bondable
♥ Lowest static component of any man-made fiber
♣ The main drawbacks of PP fibers are listed below:
♥ Low melting temperature which prevents it from being ironed
like cotton, wool, nylon etc.,
♥ Hard to be dyed after manufacturing, except after substantial
treatment and modification,
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Cont’d

20. ♥ High crystallinity and poor thermal conductivity leads to
limited texturizability.
♥ Poor UV and thermal stability which requires addition of
expensive UV stabilizers and antioxidants to overcome this
problem,
♥ Poor resilience compared to PET and Nylon,
♥ Poor adhesion to glues and latex, and
♥ Flammable which melts and burns like wax.
20
Cont’d

21. ♣ The following are some major olefin fiber uses:
♥ Carpet and upholstery:- Since polypropylene became a
commercially available fiber more than 40 years ago, it has
historically been a fiber for carpet and upholstery. About 90%
of all carpet backing and more than 25% of all carpet face
fiber is polypropylene.
♥ Absorbent Products (Diapers):- Absorbent products are very
important in the non-wovens business. Of the absorbent
product applications, the baby diaper area is the largest volume
user. Feminine hygiene products is the next.
♥ Automotive Products
21
Cont’d

22. Figure: Most common hetero-filament fibers
composed of two different polymers (a and b)
Side-by-side Core and sheath
Orange-type Matrix and fibrils
E. BIO-COMPONENT FIBER
 Examples of polymer
combinations are :
• polypropylene –polyethylene,
• polyester – polyamide,
• polyester –polypropylene, and
• polyamide 6– polyamide 6.6
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Extruding two polymers
from the same spinnerets
with both polymers
contained within the same
filament.

23.  The properties of bicomponent fibers are governed by:
• The two raw materials
• The relative quantities of the two components
• Their arrangement within the fiber
• The thickness of the fiber
 The main applications include:
• Diapers, feminine care and elastic waistband
• Medical disposable textiles,
• Filtration products
23
Cont’d

24. 24

25. Properties of NWFs Produced Using Different Fibers
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26. 26
Cont’d

27. 27
Cont’d

28. 2.2: Binders
• Binders used for consolidating webs - they bind the fibers in a
web positively with one another.
• The bonding agents are the “glue” as it binds the web firmly
together to give the nonwoven fabric.
• These agents largely determine the wear properties of the
nonwoven fabrics.
• Typical binder fractions on nonwovens come to 10–40% by
weight.
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29. • A nonwoven attains its maximum strength at minimum bending
rigidity when all the fiber intersecting points in the staple fiber
web are bonded positively.
• Binder factors influencing NWFs performance
 Backbone structure
 Functional group
 Surfactants
 Process
• Binders can be subdivided into two large groups:
 Binder fluids
 Binder fibers
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30. Cont’d The bonding agents have such a great influence on the properties
of the fabric that the requirements of the finished product determine
the choice of bonding agent.
 The following characteristic features of nonwoven fabrics decide
which bonding agent is most suitable:
 Strength / stretch (resistance to pilling, tearing and ripping)
 Elastic tenacity and bend-ability
 Handle and draping qualities
 Washing and dry cleaning fastness
 Resistance to chemicals
 Resistance to air and oxygen
 Resistance to light and heat
 Flame resistance property
 Hydrophilic or hydrophobic properties
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31. Cont’d
 Strength: The strength of a nonwoven fabric is more closely
related to the strength of the applied binder.
 Adhesion to Fibers: Even though the mechanism of adhesion is
not completely understood, the adhesion strength of the binder-to-
fiber bond has to be considered.
 Flexibility/handle: Some movements of fibers should be allowed,
especially when a soft hand is desired.
 Elastic Recovery: To avoid the permanent deformation of fabric,
good elastic recovery is required under strain.
PROPERTIES DESIRED IN A BONDING AGENT
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32. 32
 Minimum film forming temperature: At this temperature a
bonding film will dry without cracking which will occur if the
temperature falls below this point.
 It can be reduced by adding softeners or optical brighteners.
 White point (ISO standard 2115): It is the temperature at which
the layers of polymer particles that has not yet turned into the film
below this point.
 The whitening point is always 1-2oC below the minimum film
forming temperature.
Cont’d

33. Cont’d
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 Glass or brittle temperature: It is the average temperature of the
range in which the polymer passes from being hard and brittle to
being soft and rubber like.
 This temperature will give an indication of the feel, the
flexibility and the hardness of bonding film.
 Resistance to washing/ Drying cleaning: Some nonwoven
products need durability in cleaning processes according to their
end-uses.
 Resistance to aging: The binder should be stable and not be
degraded in the fabric during storage and use.

34. Cont’d
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 Good color and color retention: Diverse ranges of colors are
required, and the colorfastness and yellowing problems should
be considered.
 Economical: Minimizing the cost is an on going requirement.
 Other special requirements: Such as Flame resistance,
resistance to chemicals, air, oxygen, light, heat, etc.

35. A. Binder Fluids
 Binder fluids are not specific to any web. They are used with
the same or similar formula in different parts of industry, for
example in textile finishing, the paper industry, printing
technology and the plastics industry.
 Advantages of binder fluids :
 The formulae of binder fluids can be customized and thus
adapted to product requirements
 The relatively low cost of many binder fluids
 The possibility of subsequently producing different
nonwovens from the same web.
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36.  Disadvantages of binder fluids during production :
 Slow process rate because of drying and cross - linking
 Additional stages in the process
 High energy consumption because of drying
 Poor overall environmental compatibility
 The most important binder fluid classes include:
 Acrylate
 Styrene acrylates
 Vinyl acetate
 Vinyl acrylate
 Ethylene vinyl acetate
 Styrene butadiene
 Polyvinyl chloride
 Ethylene vinyl chloride
 Polyvinyl alcohol
 Butadiene acrylate
Cont’d
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37.  Typical supplementing materials in binder fluids
 pH regulators
 Wetting and Antifoaming agents
 Antibacterial agents
 Plasticizers
 Substances having a repellent effect, e.g. perfluoro polymers,
silicon elastomers
 Salts for flame-resistant finishing
 Thickeners such as polyvinyl alcohol or cellulose ether
 Optical brighteners
Cont’d
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38. B. Binder Fibers / Adhesive fibers
Adhesive fibers are fibers, which able to provide adhesive bonds
to other fibers due to their solubility or their fusible character
Adhesive fibers can be subdivided in two categories:
 Soluble fibers are fibrous products, which become sticky
under the influence of a solvent, like polyvinyl alcohol- (PVA)
or alginic fibers.
 Hot melt adhesive fibers are fibers made from hot melt
adhesives or thermoplastic polymers, which exhibit a lower
softening point compared to the matrix fibers.
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39. PVA-fibers are most probably the oldest type of adhesive fibers.
If these fibers are treated with water they first swell and
afterwards dissolve under the influence of elevated temperature.
Selection of the correct temperature is very important for an
effective bonding.
The dissolving temperature can be varied within limits by
modification of the polymer.
A typical application for PVA- fibers are wet-laid nonwoven
i. Soluble Fibers
Cont’d
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40. Hot-melt adhesive fibers are available either as mono-component
fibers, which are made from 100% of a hot melt adhesive polymer, or as
bi-component fiber.
In principle, all thermoplastic polymers can be used for the manufacture
of hot-melt adhesive fibers.
Hot-melt adhesive fibers are primarily based on polyolefins, polyesters
or polyamides, but the use of fibers made of polyvinyl chloride/vinyl
acetate copolymers is also known.
In case of monocomponent hot-melt adhesive fibers,
the adhesive polymer contracts to droplets as soon as it melts and forms
relatively big bonding points with high bond strength
Ii. Hot Melt Adhesive FibersCont’d
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41. In case of bi-component fibers, the fiber sheath consists of a
polymer which has a lower melting point compared to the core
component.
Fig.: Cross-section of bi-component hot-melt adhesive fibers
Cont’d
41

42. Fig.: Nonwoven bonded with monocomponent hot-melt adhesive
fibers (20% adhesive fibers)
Cont’d
42

43. Fig.: Nonwoven bonded with bicomponent hot-melt adhesive
fibers (20% hot-melt adhesive fibers)
Cont’d
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