Manufacturing of man-made fiber

1. Man-made Fiber
Book References:
1. Hand Book of Textile Fibers 1- Natural Fibers by Cook. J. Gordan.
2. Dyeing and Chemical Technology of Textile Fibres by E.R. Trotman
3. Textile Fibres, Dyes & Processes by Howard L. Needles
4. Textiles: Fiber to Fabric by Corbman, Bernard P
5. Textile Fibers by Mathews (John Wieley & Sons Inc.)
6. Man Made Fibres by R.W Moncrieff
7. Apparel Fibers by Dr. Engr. Md. Nazirul Islam
8. A Text Book of Fiber Science and Technology by S.P. Mishra

2. Textile Fiber
A fiber that can be spun into yarn or processed in
textile by means of any appropriate process is
termed as textile fiber.
To be a textile fiber a fiber should have some
properties like length, strength, flexibility,
elasticity, fineness, uniformity etc.

3. Fiber

4. Regenerated Fiber
Regenerated fiber is created by dissolving the cellulose area
of plant fiber in chemicals and making it into fiber again
(by viscose method). Since it consists of cellulose like
cotton and hemp, it is also called "regenerated cellulose
fiber.“
Example- Lyo-cell, Viscose etc.
Chemical fiber/Synthetic fiber
The fiber which is produced by the reaction of different
chemical or by the polymerization of different chemical is
called synthetic fiber.
Example- Polyester, Nylon, Acrylic etc.

5. The main source for the formation of synthetic fibers are-
Petroleum, Natural gas deposits, Coal.
Characteristics of fiber forming polymers
Flexibility: The polymer must be a linear flexible
macromolecule with a high degree of symmetry.
Molecular mass: The polymer must have a comparatively
high molecular mass.
Crystallinity: The fiber forming polymer should have high
degree of crystallinity.
Orientation: A high degree of orientation of the molecules
in the polymer is a pre-requisite for producing good tensile
strength.

6. History of Man-made Fiber
Year Fiber Year Fiber
1910 Rayon 1949 Olefin
1924 Acetate 1950 Acrylic
1930 Rubber 1953 Polyester
1936 Glass 1959 Spandex
1939 Nylon 1961 Aramid
1939 Vinyon 1983 Sulfar
1946 Metallic 1992 Lyocell
1949 Modacrylic

7. Classification of chemical fiber
Man-made Fiber
Organic
By transformation
natural polymer
Lyo-cell, Viscose,
Acetate,
Cupramonium Rayon
From synthetic
polymer
Polyester, Acrylic
Nylon
Aramid
Inorganic
Carbon,Ceramic
Glass
Metal

8. Advantage and disadvantage
Advantage/Significance/Important
• More stronger than natural fiber.
• Do not depend on agricultural production.
• Do not easily degrade by moisture, chemicals or
bacteria.
• Cheaper than natural fiber.
• Any shape can be given as the cross-section
shape depend on spinneret.
• Production rate is high.

9. Disadvantage
Not comfortable as natural fiber.
Synthetic fibers are hydrophobic, so easily can
not be dyed.
Form static electricity which cause of discomfort.

10. Fiber Formation
The formation of synthetic fibers from polymers
involves the following principle:
a) Reduction of the polymeric material to a
liquid state by melting or by dissolving in a
solvent or in some solubilizing agent.
b) Extrusion of liquid under pressure through
fine holes of a spinneret.
c) Rapid and continuous solidification of the
extruded liquid.

11. Synthetic fiber spinning method
Spinning method of synthetic fiber formation are
determined by the physical and chemical properties of
the polymer.
Spinning
method
Melt
spinning
Solution
Spinning
Dry
spinning
Wet
spinning
Due to different
solidification process

12. Spinneret
A spinneret is a device used to extrude a polymer
solution or polymer melt to form fibers. Streams
of viscous polymer exit via the spinneret
into air or liquid leading to a phase
change which allows the polymer to solidify.

13. Melt Spinning
Melt spinning uses heat to melt the polymer to a
viscosity suitable for extrusion. This type of
spinning is used for polymers that are not
decomposed or degraded by the temperatures
necessary for extrusion. This method is used by
70% of the fibers.
Example: Melt spinning is used for the
production of polyester, nylon, olefin, saran and
glass fibers.

14. Melt Spinning Process

15. Spinning Process
 In melt spinning, polymer is heated and it melts to form a
liquid spinning solution or dope.
 Chips of polymers are fed to a hopper which is heated. There is
a grid (sieve) at the base which permits only molten liquid to
pass through.
 Then the solution is purified by filter.
 The molten polymer is extruded at high pressure and constant
rate through a spinneret into a relatively cooler air stream that
solidifies the filaments.
 Finally the filament yarn either is immediately wound onto
bobbins or is further treated for certain desired characteristics
or end use.

16. Advantages:
• High speed (Production rate 8000 m/min.).
• No solvents.
• As no solvent is used, washing is not required.
• No purification problems.
• Cost effective.
Disadvantages:
• Separate drawing step.
• Accurate temperature control is critical.
• All types of polymer can not be converted to
fiber in this process.

17. Dry spinning
Dry spinning is used for polymers that need to be dissolved in
a solvent. Solvent spinning (dry spinning and wet spinning)
are used by 30% of the fibers.
Dry spinning is used to form polymeric fibers from solution.
Dry spinning is used for those polymer which can not be melt
spun.
Example: Dry spinning is used in the production of acetate,
triacetate and some acrylic, modacrylic, spandex and vinyon
(PVC,PVA) fibers.

18. Dry Spinning Process

19. Spinning Process
In dry spinning, a volatile solvent is used to
dissolve the raw materials and form a solution.
Then the solution is purified by filter.
The solution is extruded through a spinneret
into a warm air chamber where the solvent
evaporates, solidifying the fine filaments.
Finally the filament yarn either is immediately
wound onto bobbins or is further treated for
certain desired characteristics or end use.

20. Advantages:
• Yarn does not require purification.
• Suitable for heat sensitive polymer.
• More suitable for filament yarn.
Disadvantages:
• Flammable solvent hazards
• The process required solvent and so solvent recovery
process.
• Slow (200-400 yds/min).
• Additional post spinning operation is required for
complete solvent removal.

21. Wet Spinning
This is the oldest, most complex and also the most
expensive method of man-made yarn manufacture. This
type of spinning is applied to polymers which do not
melt and dissolve only in non-volatile or thermal
unstable solvents.
Example: Wet spinning is used in the production of
aramid, Lyocell, PVC, Vinyon (PVA), viscose rayon,
spandex, acrylic and modacrylic fibers.

22. Wet Spinning Process

23. Spinning Process
In wet spinning, a non-volatile solvent is used to
convert the raw material into a solution.
The solvent is extruded through the spinneret either by
simply washing it out or by a chemical reaction between
the polymer solution and a reagent in the spinning bath.
After extrusion, the solvent is removed in a liquid
coagulation medium.
Finally the filament yarn either is immediately wound
onto bobbins or is further treated for certain desired
characteristics or end use.

24. Advantages:
• Can be used for any polymer.
• Maximum fiber strength can be achieved.
Disadvantages:
• The production rate is low (70-150 yds/min).
• More costly
• Washing is necessary to remove impurities.
• Solvent and chemical recovery process is required.

25. Dope Dyeing/Solution dyeing
Manufactured fibers are solution dyed. In
solution dyeing, the dye is added to the thick
liquid before it is forced through the spinneret.

26. Different fiber structure and their
effects on fiber properties
Fiber structure Effects on fiber properties
Fiber length Strength
Molecule orientation Strength
Fiber diameter Performance and hand feel
Length to diameter ratio Spinnability
Circular cross-section Luster of the fiber

27. Yarn texturing
Texturing is the process by which synthetic fibres are modified to
change their texture - the physical appearance of the fibre. Texturing
techniques can include bulking (where thermoplastic fibres are
twisted, heat set and untwisted), crimping and coiling, amongst
others. Texturing takes advantage of the thermoplastic nature of
synthetic fibres and uses it to set texturised features in place.
Fibres may be texturised to improve the fibre's insulation properties
(as processes like bulking allow it to trap air better), to minimise a
shiny, synthetic-looking appearance, to reduce the silky nature of
the fibre or to create special effects (fancy yarns).

29. These modifications will also affect the eventual fabric, and fibres
may be folded, looped, coiled or crinkled in order to improve the
drape, appearance, lustre, warmth, elasticity or handle of the
finished fabric. Texturising can reduce the "synthetic" appearance of
a finished fabric, bringing its appearance closer to that of a natural
fibre fabric.
Texturing is a procedure used to increase the volume and the
elasticity of a filament fibres. The essential properties of textured
yarns and the products made from them are softness, fullness, a high
degree of elasticity, thermal insulation and moisture transporting
properties. All yarns which can be shaped by heat are suitable for
texturing. The prime purpose of texturing filament yarn is to create
a bulky structure. The process of introducing crimp, loop, coils to
continuous filament yarn is called texturing. It stabilizes the
synthetic yarn through heating and drawing.

30. Method of texturing
• Gear crimping
• False twisting
• Knit-de-knit
• Stuffer box

31. Purpose of texturing
The prime purpose of texturing filament yarn is to create a bulky
structure that is desirable for the following reason:
• The voids in the structure cause the material to have good
insulation properties.
• The voids in the structure change the density of the material
(Which make a light weight yarn with good covering properties).
• The sponge like structure feels softer than a regular twisted flat
yarn.
• The crimped or coiled filament structure gives a higher elasticity
than a flat yarn.
• The less oriented surface structure of the yarn gives dispersed
light reflection which give a desirable dull appearance.

32. The End

33. Regenerated Fibers
Regenerated fibers are found by the modification of vegetable or
protein fiber.
Properties of regenerated fiber:
• Give higher strength and the properties of natural fiber.
• Fibers are hydrophilic.
• Easily dye-able.
• Easily washable and cross-section can be changed.
Regenerated fiber can be produced from cellulose fiber or from
protein fiber.
Regenerated cellulosic fibers are: Viscose, Cuprammonium,
Acetate, Lyo-cell etc.
Regenerated protein fibers are: Casein fiber, Vicara fiber, Ardil
fiber etc.

34. Rayon Fiber
Cellulose based man-made fiber is termed as Rayon fiber. During it’s
development, it has designated by various name such as artificial silk,
wood silk, fiber silk, art silk etc. The implication in this name is that, it
was originally intended to be a substitute for silk.
Rayon is a manufactured fiber composed of regenerated cellulose in
which substituents have replaced not more than 15% of the hydrogen
of the hydroxyl group.
Types of regenerated cellulose or rayon fiber:
1. Regenerated by viscose process (viscose fibers)
2. Regenerated by cuprammonium process (cuprammonium fibers)
3. Regenerated by lyocell process (lyocell fibers)
4. Regenerated by acetate process (acetate fibers)
Acetate fibers is also called cellulose ester fibers which also divided
into two categories: 1. Acetate fibers and 2. Triacetate fibers

35. Viscose Rayon/Artificial Silk
Viscose is a man made, natural polymer, cellulosic or regenerated cellulose
filament or staple fiber. According to U.S. Federal Trade Commission “Rayon is a
manufactured fiber composed of regenerated cellulose in which substituent’s have
replaced not more than 15% of the hydrogen’s of the hydroxyl groups”.
Chemical reaction for viscose rayon production:
1. The cellulose is treated with 17.5% solution of NaOH which converts
cellulose into soda-cellulose.
Cell-OH + NaOH → Cell-ONa + H2O
Cellulose Soda-cellulose
2. The soda cellulose reacts with carbon disulphide to form sodium cellulose
xanthate.
Cell-ONa + CS2 → Cell-O-CS-SNa
Sodium cellulose xanthate.
3. Then it is dissolved in a dilute solution of caustic soda. It is extruded into
H2SO4 which regenerates the cellulose in the form of long filaments.
Cell-O-CS-SNa + H2SO4 → Cell-OH + Na2SO4
Regenerated cellulose

36. Flow Chart of Viscose Rayon Production
Cellulose pulp
↓
Steeped in warm caustic soda for an hour
↓
Pressed to remove excess solution
↓
Powdery Crumbs
↓
Aged for up to a day (formation of soda cellulose)
↓
Mixed with carbon disulphide (formation of sodium cellulose xanthate)
↓
Mix into a dilute caustic soda solution (to give a viscose solution)
↓
Ripening for up to a day (Regenerated cellulose)
↓
Spinning

37. Viscose fiber formation process consists of the following
of the structural modifications:
a. Swelling of cellulose with the hydrates of NaOH.
b. Breakage of crystalline and amorphous parts.
c. Replacement of the hydroxyl group by xanthate group.
d. Removal of xanthate group in spinning and then sodium
groups by hydroxyl groups.
e. Formation of vander waals forces and hydrogen bonding.
f. Formation of regenerated cellulose structure.
Viscose manufacturing technology mainly consists of the
following three stages:
1. Purification of cellulosic material.
2. Preparation of cellulose xanthate solution.
3. Fiber formation and regeneration of cellulose.

38. Manufacturing Process
It is a regenerated cellulosic fiber and cellulose is the raw material for
producing this man made fiber. The raw material is obtained from a special
variety of wood called spruce.
1. Purification of Cellulose:
The manufacture of viscose rayon starts with the purification of cellulose.
Spruce trees are cut into timber. Their barks are removed and cut into pieces
measuring 7/8" x 1/2" x 1/4". These pieces are treated with a solution of
calcium bisulphite and cooked with steam under pressure for about 14 hours.
The cellulosic component of the wood is unaffected by this treatment but the
cementing material called lignin, which is present in the wood, is converted
into its sulphonated compound which is soluble in water. This can be washed
off, thereby purifying the remaining cellulose. This cellulose is treated with
excess of water. After this it is treated with a bleaching agent and finally
converted into paper boards or sheets. This is called wood pulp, which is
normally purchased by the manufacturers of viscose rayon.

39. 2. Conditioning of Wood Pulp:
The pulp sheets are cut by a guillotine to the required dimension and are
kept in a special room. Air moves freely among the divisors by means of
ventilators, the temperature is maintained at 30ºC. In this way the
desired moisture content can be had.
3. Steeping Process:
The conditioned wood pulp sheets are treated with caustic soda solution
(about 17.5%). It is called mercerising or steeping. The high DP
cellulose (1000) is converted into soda cellulose. The sheets are allowed
to soak until they become dark brown in color. This takes about 1-14
hours. The caustic soda solution is drained off and sheets are pressed to
squeeze out excess caustic soda solution. 100 kg of sulphite pulp gives
about 310 kg of soda cellulose.
4. Shredding or cutting process:
The wet, soft sheets of soda cellulose are passed through a shredding
machine which cuts them into small bits. In 2-3 hours the sheets are
broken into fine crumbs.

40. Viscose Rayon Production Process

41. 5. Ageing Process:
To obtain almost ideal solution of cellulose, the soda cellulose is
stored in small galvanised drums for about 48 hours at 28C. This
process is called ageing process. The ageing process is essential.
During This process, the DP od soda cellulose is decreased from
1000 to about 300 by oxygen present in the air, contained in the
drum.
6. Churning Process or Xanthation:
After ageing, the crumbs of soda cellulose are transferred to
rotating, air tight, hexagonal churners or mixers. Carbon
disulphide ( 10% of the weight of the crumbs) is added to the
mixer and churned together for 3 hours by rotating the mixers at a
slow speed of 2 rev per minutes. Sodium cellulose xanthate is
formed during this process and the colors of the product changes
from white to reddish orange.

42. 7. Mixing or dissolving Process:
The orange product i.e. soda cellulose xanthate is in the form of
small balls. These fall into a mixer called dissolver which is
provided with a stirrer. A dilute solution of caustic soda is added,
and the contents are stirred for 4-5 hours and at the same time, the
dissovler is cooled. The soda cellulose xanthate dissovles to give a
clear brown thick liquor, similar to honey. This is called 'viscose'
and it contains about 6.5% caustic soda and 7.5% cellulose.
8. Ripening Process:
This viscose solution requires to be ripened to give a solution
having best spinning qualities. Ripening is carried by storing the
viscose solution for 4-5 days at 10 to 18 deg. The viscosity of the
solution first decreases and then rises to its original value. The
ripened solution is filtered carefully and is now ready for spinning
to produce viscose rayon filaments.

43. 9. Spinning Process:
The viscose solution is forced through a spinneret, having many
fine holes ( 0.05-0.1mm) diameter. The spinneret is submerged
into a solution containing the following chemicals.
10% Sulphuric acid, 18% Sodium sulphate, 1% Zinc sulphate,
2% glucose, 69% water.
The spinning solution is kept at 40-45ºC.
Sodium sulphate precipitates the dissolved soda cellulose
xanthate. Sulphuric Acid converts xanthate into cellulose, carbon
disulphide and sodium sulphate. The glucose is supposed to give
softness and pliability to the filaments whereas zinc sulphate
gives added strength.
As a number of filaments emerge from the spinneret, they are
taken together to an eye at the surface of the spinning bath and
then guided to two rollers from where they are wound on to a
spindle.

44. The quality of viscose rayon filament formed depends upon:
1. The temperature of the spinning bath
2. The composition of the spinning bath.
3. The speed of coagulation.
4. The period of immersion of the filament in the spinning bath.
5. The speed of spinning.
6. The stretch imparted to the filaments.

45. Role of Zinc in Spinning Bath
In the non-zinc spinning process under normal conditions of acid
concentrated in the spinning bath, cellulose xanthate gel is
converted into cellulose xanthic acid and then to cellulose. The
process is very fast and regeneration takes place before the
cellulose molecules can properly oriented. This result in a rather
disorientation matrix with poor crystalline organization. The net
result is a regenerated cellulose filament with poor dry strength
and a very interior wet strength. So the zinc result in a transient
zinc cellulose xanthate complex which is more stable against acid
induced regeneration. Zinc being bivalent form a transient cross
link between the adjustment xanthate groups. Coupled with
crosslinking the strong deswelling action of zinc xanthate gel
which can be stretched to a highly oriented structure with small
crystal size and relatively large crystals.

46. Physical properties of Viscose Rayon:
• Moisture absorption: Viscose rayon absorbs moisture more
than cotton. Viscose rayon moisture content 13% at 65%
relative humidity.
• Tensile strength: Less tensile strength than cotton in wet
condition.
• Elasticity: Less elasticity than cotton, about 2-3% less.
• Abrasion resistance: Low.
• Flammability: Like as cotton.
• Melting temp: Do not decompose at 176ºC to 204ºC.

47. Chemical properties of viscose rayon:
• Effect of acid: Acid like H2SO4 or HCl, break down the
macromolecules of viscose and produce hydro-cellulose. Dilute
acid for short time do not attack.
• Effect of alkali: Concentrated alkali causes swelling and reduces
strength. But week alkali does not damage.
• Effect of bleaching: Viscose can withstand both oxidizing and
reducing bleaches.
• Biological agent: Mildew, bacteria etc. affect the color, strength
and luster of rayon.
• Dye affinity: Better affinity for dyes than cotton.
• Flammability: Burns rapidly.

48. Application of Viscose Rayon
Yarn: Embroidery, chenille, cord, novelty yarns, sewing thread.
Fabric: Crepe, gabardine, suiting, lace, outwear fabrics and lining of coats
and outwear.
Apparel: Dresses, blouses, saris, jackets, lingerie, linings, military hats,
slacks, sport shirts, sports-wear, suit, ties, work cloth, evening gowns.
Domestic textiles: Bead spreads, Bed sheets, blankets, curtain, draperies,
slip covers, table cloths, chair cover, cushions, furnishing cloth etc.
Industrial textiles: High tenacity rayon is used as reinforcement to
mechanical rubber goods(tires, conveyor belts, hoses) applications within
aerospace (tire cord of air craft), agricultural textile industries, braided cord,
tapes, power transferring belt, umbrella cloth, protective cloth etc.
Miscellaneous: Sausage casing, cellophane, feminine hygiene, beach and
sports wear, fire fabrics, (Viscose + cotton) this blend is used for reducing
cost, (Viscose + polyester) this blend is used for comfort, strength and
absorbency.

49. Acetate Rayon
Acetate Rayon is modified regenerated cellulose fiber where at least
92% of the hydroxyl groups are acetylated. Cotton linters or wood
pulp sheets are used for manufacturing “Acetate Rayon”. Cellulose
acetate is manufactured by dissolving cellulose and then regenerating
into cellulose acetate: (primary or secondary).
Alcohol + Acid --> Ester
If the cellulose is treated with acetic acid under certain conditions the
free hydroxyl groups of cellulose are converted into ester groups.
• First prepared in 1865 by heating cotton with acetic anhydride at
130-140 degree centigrade.
• In 1894, Cross and Bevan developed a more practical approach, in
which acetylation was carried at atmospheric pressure using
sulphuric acid or zinc chloride as catalyst.
• Can be produced as primary acetate (cellulose triacetate) or
secondary acetate or acetate rayon.

50. Basic Principles of Acetate Fiber Production
Acetate is derived from cellulose by reacting purified cellulose from
wood pulp with acetic acid and acetic anhydride in the presence of
sulfuric acid. It is then put through a controlled, partial hydrolysis to
remove the sulfate and a sufficient number of acetate groups to give
the product the desired properties. The anhydroglucose unit, is the
fundamental repeating structure of cellulose, has three hydroxyl
groups which can react to form acetate esters. The most common
form of cellulose acetate fiber has an acetate group on approximately
two of every three hydroxyls. This cellulose diacetate is known as
secondary acetate, or simply as “acetate”. After it is formed, cellulose
acetate is dissolved in acetone for extrusion. As the filaments emerge
from the spinneret, the solvent is evaporated in warm air (dry
spinning), producing fine filaments of cellulose acetate.

52. Primary Acetate
Completely acetylated cellulose in
which all three hydroxyl groups of
glucose unit in cellulose molecules
are acetylated. It was obtained as
tough solid and is soluble in toxic
and expensive solvents like
chloroform.
Secondary acetate
Discovered in 1906 that triacetate could be partially hydrolyzed of i.e.
by removing some of acetate group of triacetate and reconverting into
hydroxyl group. It was formed by complete acetylation and
subsequent partial hydrolysis and is called secondary acetate. It is
obtained from primary acetate. It is soluble in relatively cheap and non
toxic solvent like acetone.

53. Raw Materials
• Cotton linters or wood pulp
• Chemicals: 1. Glacial Acetic Acid
2. Acetic Anhydride
• Catalyst: Sulphuric Acid or Zinc Chloride
Manufacturing Process
Manufacturing of acetate rayon takes place in four stages:
• Acetylation process
• Hydrolysis
• Preparation of Dope solution
• Spinning

55. Acetylation process
Purified cotton linters/purified waste cotton/ bleached pulp sheets are
fed to the reactor. A mixture of acetic anhydride, glacial acetic acid and
small amount of conc. H₂SO₄ are added to reactor. The reactor is
sealed after adding the mixture of chemicals and cotton linters. A stirrer
is used to mix the ingredients thoroughly. Acetylation reaction is an
exothermic reaction. The heat liberated during acetylation is removed
by circulating cold water through jacket fitted outside the reactor. The
acetylation reaction is completed in 7-8 hrs at 25-30ºC. Triacetate is
formed at this stage.
Hydrolysis (Partial Deacetylation)
Triacetate is stored for ageing. Then acetic acid, water and sulphuric
acid are added and allowed to stand for 10-20 hrs. During this period,
partial conversion of acetate groups to hydroxyl groups takes place.
Careful control is necessary during hydrolysis. The mixture is then
diluted with water and stirred constantly. The secondary acetate
separates in the form of white flakes. The water is removed and then
reaction vessel is filled with fresh water. The water is changed several
times to obtain all the secondary acetate formed. The white flakes are
centrifuged and excess of water is removed. The flakes are then dried.

56. Preparation of dope solution
Dried flakes are dissolved in acetone and a viscous solution is
formed, this viscous solution is known as “ Dope solution”. The dried
acetate flakes are mixed with three times their weight of acetone in
the enclosed tank provided with powerful stirrer. The acetate is
dissolved slowly in the solvent. It takes about 24 hours for complete
dissolution to give a thick (viscous) clear liquid. The solution is
filtered. The spinning solution contains 25-35% of secondary acetate.

57. Spinning
A dope is fed from the feed tank and dope
is filtered through a filter to avoid trouble
due to solid particles interfering with
smooth flow of dope through jets. A
metering pump ensures a constant flow of
dope to spinneret. The spinneret consists of
metal plate through which number of small
holes are made. The number of holes in the
jet determines the number of filaments in
the yarn. As the dope is squeezed out of
jets, it emerges in filaments form into
spinning cabinet. The filaments travel
vertically down towards a feed roller from
which it is guided on to bobbin. A slight
twist is inserted as it is taken up. Take up
speed is normally between 200 and 400
meter per minute. A slight stretch is also
imparted to yarn to give some degree or
orientation to the molecules. The stretched
yarn become stronger than unstretched
yarns due to orientation of molecules.

58. The diameter of filaments depend on following three factors:
• Rate at which dope is fed by pump
• Diameter of jets
• Rate of stretching filaments
The hot air at 100℃ is fed from the bottom of cabinet. The hot air
evaporates all acetone in the dope from the jets. The acetone is
withdrawn from the top of cabinet and taken away to recovery plant.
The acetone air mixture is scrubbed in water towers. The efficient
recovery of acetone and acetic acid is essential for economic
manufacture of Acetate Rayon.
Important factors in the spinning process are:
• Temperature
• Moisture Content
• Velocity of Air
The filaments are collected on spinning bobbin. Filaments are
available from 45-600 denier. Staple fibers are 3-20 denier and cut
into 1.5’’, 2’’, 2.5’’, 3’’, 3.5’’ and 5’’.

59. Difference between triacetate and diacetate fiber
Triacetate/Primary Acetate Fiber Diacetate/Secondary Acetate Fiber
Complete hydrolysis of cellulose
is occurred.
Partial hydrolysis of cellulose is
occurred.
All –OH group is replaced by
acetate group.
All –OH group is not replaced by
acetate group.
Dissolved in chloroform. Dissolved in acetone.
Good color fastness. Color fastness is not good.
Higher strength and elasticity. Comparatively lower strength and
elasticity.
Good heat setting property. Heat setting property is somewhat
poor.

60. Properties of Acetate Fiber
Tensile strength
In dry state the tenacity is 1.1-1.3 g/denier. It does not lose strength as
viscose when it is wet.
The tensile strength of acetate is 18000-22000 lb/square inch.
Elongation
Elongation is 23-30% when dry and 35-45% when wet.
Elastic recovery
At 4% extension , acetate has recovery 48-65%. When stretched further, the
fiber undergoes plastic flow and becomes permanently deformed and does
not return to its original position.
Luster
Very bright in luster.
Handle
Soft in handle.
Drape
Very satisfactory quality.
Melting point
It is a thermoplastic material. It becomes sticky at 190ºC and at 205ºC
soften enough to deform under pressure. It melts at 232ºC.

61. Effect of Moisture
In acetate the hydroxyl groups have been replaced by acetate groups. The
inherent attraction of acetate for water molecules is less than that of viscose.
Acetate does not absorb as much water as the viscose. The standard moisture
regain is 6.5%.
Effect of High temperature
At 120ºC, it retains much of its original strength.
Effect of age
Slight decline in tensile strength over prolonged period of time
Effect of sunlight
Deterioration after prolonged exposure resulting in some loss of strength.
Retention of tenacity is improved by addition of certain color pigments.
Effect of acids
Dilute acids does not attack acetate but fibers are damaged by strong acids.
Effect of alkalis
Strong alkali can cause saponification. The acetate groups are replaced by hydroxyl
groups and cellulose acetate is gradually changed to regenerated cellulose.

62. Biological Resistance
Acetate is highly resistant to mildew, moulds and bacteria.
Shrinkage
Acetate has good dimensional stability and retain its shape in washing and
laundering.
Heat Conductivity
It acts as insulator.
Solubility
Soluble in Acetone, Methyl Ethyl Ketone.
Cleaning and washing
Soaps and mild detergents can be used safely in warm water. The garments
should not be rubbed vigorously and warm water must be squeezed.
Effect of strong oxidizing agent/ Bleaching
Acetate is attacked by strong oxidizing agents but not affected by normal
bleaching solutions the chemical properties depend on degree to which
acetate groups have replaced hydroxyl groups in cellulose molecule.

63. Acetate Fiber Blends
a. Acetate and Wool
b. Acetate and Viscose Rayon
Uses of Acetate fiber
Apparel: Blouses, linings, wedding and party dress, home
furnishings, draperies, lingerie, garment linings and certain
specialty fabrics.
Triacetate is used in sportswear, tricot fabrics, and in garments
where pleats and pleat retention is important as well as in certain
specialty fabrics.
Household uses: Curtains, Bed sheets, Pillow covers etc.
Industrial Uses: Cigarette filters.

64. LYOCELL
THE NEW AGE FIBRE
• Lyocell (lyo from Greek: lyein =
dissolve, cell from cellulose)
• Man made cellulosic fibres
• Produced by regenerating cellulose
into fibre form out of a solution
(solvent spinning) of cellulose in an
organic solvent.
• ‘Organic solvent’ - mixture of organic
chemicals and water.
• ‘Solvent spinning’ means dissolving
and spinning without the formation of
a derivative.
• Lenzing AG. is currently (2013) the
only major producer of lyocell fibres.
• Tencel is the brand name of Lyocell.

65. RAW MATERIALS
Cellulose
• Most abundant natural resource on earth.
• It is obtained from wood pulp.
• Trees like Eucalyptus , bamboo and pine tree are used.
• Eucalyptus is primarily used to produce the Tencel fibre.

66. NMMO
• Chemically produced from N methyl morpholine and hydrogen
peroxide
• Cyclic amine oxides such as N-methyl morpholine oxide have the
capacity to dissolve cellulose in large capacities
• NMMO exists in several degrees of hydration.
• At room temperature it is a crystalline mono hydrate and melts at
72 degrees
• When heated at 100 C, mono hydrate NMMO is able to dissolve
readily several percentages of high molecular weight cellulose
• Cellulose dissolution in NMMO is found to depend on:
– The temperature of the solution
– The water content of the mixtures
– The concentration and the degree of
– Polymerisation of the cellulose

67. MANUFACTURING AND PROCESSING
Preparing Wood Pulp
• Hardwood trees are harvested
and logs are taken to mill.
• Wood is cut into small chip and
fed into a chemical digesters
which removes lignin and
softens them into wet wood
pulp.
• It is then washed with water,
bleached and dried into huge
sheets of cellulose and rolled
onto spools.

68. Dissolving Cellulose
• Spools of cellulose are
unrolled and broken
into one square
inches.
• It is then loaded into
heated pressurized
vessel containing N-
methyl morpholine N-
oxide.
• Cellulose dissolves
into a clear solution.

69. Filtering
• In Amine Oxide solvent, cellulose is dissolved into a clear
solution.
• It is then pumped out and filtered.
Spinning
• Cellulose is forced through the spinnerets and long strands of
fibre comes out.
• These fibres are then dissolved in dilute Amine Oxide solution
and is later washed with water.

70. Drying And Finishing
• Fibre is passed through drying area.
• In the drying area, water is evaporated and lubricant is applied
which may be soap, silicone or other agent.

71. Solvent Recovery
After spinning and drying process, dilute solution is taken passed
through the evaporator where water is removed and amine oxide
solvent is fed back to the Dissolving process.

72. PROPERTIES
• Soft, strong, absorbent
• Fibrillated during wet processing to produce special textures
• It has high wet and dry strength, it is stronger than Cotton and
Wool.
• Wrinkle resistant
• Very versatile fabric, dyeable to vibrant colours, with a variety of
effects and textures.
• Can be hand washable
• Simulates silk, suede, or leather touch
• Good drapability
• Biodegradable
• Fine yarn counts can be spun

73. Comfort
• Soft, smooth fibre.
• Ideal for apparel that contacts skin.
• Thermal retention is poor.
Appearance Retention
• Resiliency is moderate- Wrinkles but not as severely as rayon.
• Shrinks, but not progressively.
• May have problems with fuzziness or piling.
Aesthetics
• Lustre, length and diameter can be changed depending upon end
use.
• Processed to produce a range of surface effects.
• Offers unusual combinations of strength, opacity, absorbency.
Durability
• Performs more like cotton than rayon.
• Strongest of cellulosic fibres.
• Unique combination of soft hand and good durability, produces
comfortable, long-lasting textiles for apparel and interiors.

74. Care
• Either gently machine- Washable or dry cleaned.
• Sensitive to acids.
• Resistant to mild alkalis.
• Sensitive to mildew and some insects.
• High dye affinity.
• High inherent whiteness- Bleaching is not
necessary.

75. PHYSICAL STRUCTURE
• The physical structure is a more
rounded cross section & smoother
longitudinal appearance than rayon.
• Since in the case of Lyocell we are just
dissolving cellulose in NMMO and not
making any cellulose derivatives, it has
a different molecular structure than
other regenerated cellulosic fibres.
• The structure is ‘Homogeneous’ and
‘Dense’.
Cross Section
Longitudinal Section

76. APPLICATIONS
• Professional business wear.
• Leotards
• Hosiery
• Casual wear
• Upholstery
• Window-treatment fabrics
• Filters
• Printers’ blankets
• Specialty papers
• Medical dressings
• Conveyer belts for strength &
softness
• Botanic Tencel bed
Botanic Bed