An introduction to Acetate rayon,manufacturing process,properties and end uses

1. Acetate Rayon

2. Introduction
• 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

3. 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
It is soluble in toxic and expensive solvents like
chloroform

4. 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
this new material was formed by complete
acetylation and subsequent partial hydrolysis and is
called secondary acetate
It is soluble in relatively cheap and non toxic solvent
like acetone

5. Commercializationon
• In world War 1, the usage of acetate rayon started to
increase
• But the commercialization started in 1921 when all
technical difficulties were removed and filament
yarn was being made in Britain by the name
“ Celanase”
• 1934 million pound yarn was exported to USA and
also at that time the problem of dyeability was
solved

6. Acetate Rayon
Trade name Manufacturer
Acele du pont, USA
Aceta Bayer, Germany
Albuna Snia Viscose, Itlay
Arnel Celanase Corp, USA
Atlon Toho Rayon Co., Japan

7. • Raw Material:
• Cotton linters or wood pulp
• Chemicals: Glacial Acetic Acid
Acetic Anhydride
• Catalyst: Sulphuric Acid or Zink chloride

8. Introduction:
Acetate Rayon is modified regenerated
cellulose fiber
Cotton linters or wood pulp sheets are used
for manufacturing “Acetate Yarn”
Cellulose acetate is manufactured by
dissolving cellulose and then regenerating into
cellulose acetate: (primary or secondary)

9. • The two acetates are formed by following
reaction:
The triacetate ( Primary acetate) is soluble in
chloroform (CHCl3) but insoluble in Acetone
(CH3COCH3)
the secondary acetate (Acetate Rayon) is
soluble in “ Acetone” and is obtained from
triacetate

12. Manufacturing of Acetate Rayon:
Takes place in four stages;
• Acetylation process
• Hydrolysis
• Preparation of Dope solution
• Spinning

13. 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
It is soluble in toxic and expensive solvents like
chloroform

14. • 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 25-30 degree centigrade
• Triacetate is formed at this stage

15. Hydrolysis (Partial deacetylation)
• Triacetate is stored for ageing
• 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

16. • 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

17. Preparation of dope solution:
Dried flakes are dissolved in a solvent
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

18. • 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.

19. Spinning:
A dope is fed from the feed tank
A 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

20. • 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

21. 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
this new material was formed by complete
acetylation and subsequent partial hydrolysis and is
called secondary acetate
It is soluble in relatively cheap and non toxic solvent
like acetone

22. • The hot air at 100 ◦C 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

23. • 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’’

24. `

25. Acetate Fiber Blends:
a. Acetate and Wool
b. Acetate and Viscose Rayon

26. Properties
Tensile strength
In dry state the tenacity is 1.1-1.3 g/denier
It does not lose strength as viscose does when wet;
the tensile strength of acetate is 18000-22000 lb/sq
inch
Elongation:
23-30 % dry
35-45 % wet

27. 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
Handle:
Soft
Drape:
Very satisfactory quality

28. Commercializationon
• In world War 1, the usage of acetate rayon started to
increase
• But the commercialization started in 1921 when all
technical difficulties were removed and filament
yarn was being made in Britain by the name
“ Celanase”
• 1934 million pound yarn was exported to USA and
also at that time the problem of dyeability was
solved

29. • Melting point:
It is a thermoplastic material. It becomes sticky at
190 ◦C and at 205 ◦C soften enough to deform under
pressure. It melts at 232 ◦C
Effect of High temperature:
After a week at 120 ◦C, it retains much of its original
strength
Effect of age:
Slight decline in tensile strength over prolonged
period of time

30. 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 conc. acids

31. 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
Biological Resistance:
Acetate is highly resistant to mildew, moulds
and bacteria

32. • Shrinkage:
Acetate has good dimensional stability and retain its
shape in washing and laundering
Heat Conductivity:
It act as insulator
Solubility:
Soluble in Acetone, Methyl Ethyl Ketone

33. • 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

34. End uses:
Dresses and fabrics
Curtains, Bed sheets
Pillow covers
Wedding dresses