This presentation is about Manufacturing of acetate fiber from cellulose...

1. Acetate Fibre :
Basically it is chemically regenerated fibre obtain from cellulose.
It is also called derivative of cellulose fibre.
Chemical composition of acetate contain ester group.
Chemical Structureof Acetate:
Chemical Structure of Viscose:
Manufacturing Of Acetate:
The basic raw material for acetate is cotton.
After that it is treated with other chemical and TRI-Acetate is formed.
Then from TRI-Acetate Di-Acetate or Acetate is form.
 In this report we will discuss production of Acetate from the raw
material to its finished products

2.  Its uses
 Many other Interesting things.
Production Of VISCOSE:
Cellulose:
Purified cellulose for rayon production usually comes from specially
processed wood pulp. It is sometimes referred to as dissolving cellulose or
dissolving pulp to distinguish it from lower grade pulps used for
papermaking and other purposes. Dissolving cellulose is characterized by a
high a -cellulose content, i.e., it is composed of long-chain molecules,
relatively free from lignin and hemicelluloses, or other short-chain
carbohydrates.
Steeping:
The cellulose sheets are saturated with a solution of caustic soda (or
sodium hydroxide) and allowed to steep for enough time for the caustic
solution to penetrate the cellulose and convert some of it into soda
cellulose , the sodium salt of cellulose. This is necessary to facilitate
controlled oxidation of the cellulose chains and the ensuing reaction to
form cellulose xanthate.
Pressing:
The soda cellulose is squeezed mechanically to remove excess caustic soda
solution
Shredding:
The soda cellulose is mechanically shredded to increase surface area and
make the cellulose easier to process. This shredded cellulose is often
referred to as white crumb
Ageing:
The white crumb is allowed to stand in contact with the oxygen of the
ambient air. Because of the high alkalinity of white crumb, the cellulose is
partially oxidized and degraded to lower molecular weights. This
degradation must be carefully controlled to produce chain lengths short

3. enough to give manageable viscosities in the spinning solution, but still
long enough to impart good physical properties to the fibre product.
Xanthation:
The properly aged white crumb is placed into a churn, or other mixing
vessel, and treated with gaseous carbon disulfide. The soda cellulose reacts
with the CS2 to form xanthate ester groups. The carbon disulfide also
reacts with the alkaline medium to form inorganic impurities, which give
the cellulose mixture a characteristic yellow color - and this material is
referred to as yellow crumb . Because accessibility to the CS2 is greatly
restricted in the crystalline regions of the soda cellulose, the yellow crumb
is essentially a block copolymer of cellulose and cellulose
xanthate.
Dissolving:
The yellow crumb is dissolved in aqueous caustic solution. The large
xanthate substituents on the cellulose force the chains apart, reducing the
inter chain hydrogen bonds and allowing water molecules to solvate and
separate the chains, leading to solution of the otherwise insoluble cellulose.
Because of the blocks of un-xanthated cellulose in the crystalline regions,
the yellow crumb is not completely soluble at this stage. Because the
cellulose xanthate solution (or more accurately, suspension) has a very high
viscosity, it has been termed viscose .
Ripening:
The viscose is allowed to stand for a period of time to ripen . Two
important processes occur during ripening: Redistribution and loss of
xanthate groups. The reversible xanthation reaction allows some of the
xanthate groups to revert to cellulosic hydroxyls and free CS2. This free
CS2 can then escape or react with other hydroxyl on other portions of the
cellulose chain. In this way, the ordered, or crystalline, regions are gradually
broken down and more complete solution is achieved. The CS2 that is lost
reduces the solubility of the cellulose and facilitates regeneration of the
cellulose after it is formed into a filament.
Filtering:

4. The viscose is filtered to remove undissolved materials that might disrupt
the spinning process or cause defects in the rayon filament.
Degassing:
Bubbles of air entrapped in the viscose must be removed prior to extrusion
or they would cause voids, or weak spots, in the fine rayon filaments.
SPINNING:
The viscose is forced through a spinneret, a device resembling a
showerhead with many small holes. Each hole produces a fine filament of
viscose. As the viscose exits the spinneret, it comes in contact with a
solution of sulphuric acid, sodium sulphate and, usually, Zn++ ions. Several
processes occur at this point, which cause the cellulose to be regenerated
and precipitate from solution. Water diffuses out from the extruded viscose
to increase the concentration in the filament beyond the limit of solubility.
The xanthate groups form complexes with the Zn++, which draw the
cellulose chains together. The acidic spin bath converts the xanthate
functions into unstable xantheic acid groups, which spontaneously lose CS2
and regenerate the free hydroxyls of cellulose. (This is similar to the well-
known reaction of carbonate salts with acid to form unstable carbonic acid,
which loses CO2). The result is the formation of fine filaments of cellulose,
or rayon.
Production Of Tri-Acetate:

5. Cellulose sheets are steeped in acetic acid for a time to make material more
reactive, after further treatment with more acetic acid, acidic anhydride is
added. The mixture is stirred througly blended but no reaction take place
until and unless Sulphuric acid is added . This begins a acetylation reaction.
The temperature is kept low because it gives out great amount of heat. The
mixture stand for 7-8 hours until it take it on a thick gelatin like. The
material form is Tri-Acetate. To produce tri-acetate fibre water is added to
the solution. This precipitated out collected , washed and dried. This
dissolves in methylene chlorine and small quantity of alcohol
Production Of Acetate or Di-Acetate:
The material form tri-acetate flakes are combined with water . The solution
strands for 24 hours. This cause acid hydrolysis and some of acetylated
hydroxyl group regain their original position back.
Tri-acetate is poured into water and cellulose acetate precipitated out into
chalky white flakes that are connected washed and dried. This is secondary
acetate. The flakes are soluble in acetone. A common nontoxic solvent. This
takes 24 hours to make the solution. This solution is extruded through
spinneret into warm air that evaporated acetone.
MolecularOf Acetate or Di-Acetate:

6.  Acetate is a polymer composed of units of cellulose acetate in which
an average 2 to 2.5 of the three OH units per glucose residue have
been re placed by acetyl radical CH3COO
 The degree of polymerization is between 350 to 400
Microscopic propertiesOf Acetateor Di-Acetate:
 In longitudinal view, acetate can be seen uniform
 In width several parallel lines to the length of fiber.
 The cross section of acetate shows that the fiber are lobed in outline,
with regular curves, but there are no sharps point such as sometimes
appear in viscose
PhysicalPropertiesOf Acetate or Di-Acetate:
ShapeAnd Appearance:
 They have the flexibility of such products that they can be made to
any length and in varity of diameters from very fine to relatively
heavy fibers.
 Spinnerettes can be made orifices shaped other then round, this
makes possible the production of variety of different-shaped acetate.

7. Luster:
 The luster of acetate can be controlled.
 Thus fiber can be obtained that are very dull, very bright and shiny
or at any stage between.
Tenacity:
 Acetate has a dry tenacity of 1.2 to 1.4 grams per denier
 In wet conditions it drops to 0.8 to 1.0 g/d
 It has low tenacity when compared to other fibers
 To make it more attractive other properties are added which may
outweight the low strength
Elongation And Elastic Recovery:
 It has good elastic recovery
 If stretch more then 1 % acetate undergoes some permanent
deformation and will not return to its size back
Resiliency:
 Regular acetate does not have good recovery from crushing or
wrinkling.
 Its resiliency is low.
MoistureRegain:
 Standard moisture regain of acetate is 6.5%
 In saturation acetate will absorb 14% moisture.

8. Density:
 Having density of 1.32
 It is lighter then cellulose.
 Making it possible
DimensionalStability:
 It is comparatively resistant to shrinkage or strength , except when
relaxation shrinkage might occurs because of tension applied in
contrasting a fabric.
 It may shrink when exposing to the high temperature.
Thermal Properties:
 Regular acetate is easily soften by by temperature above 177C
 The fiber melts and burns evenly forming a hard black bead ash.
 It gives chemical odor or an odor similar to hot vinegar.
 Because of sensitivity to high temperature the fiber should be ironed
to low temperature.
Chemical Properties:
Effect of Alkalies:
 Dilute alkalies have little effect on acetate or tei-acetate.
 Concentrated alkali causes saponification of both and eventual lost in
fiber weight and reduction in the soft hand of fabrics.
Effect Of Acids:
 Concentrated acid both organic and inorganic weaken the fibers and
in most instant cause complete fiber degradation.
 Hot acid both diluted or concentrated may cause decomposition or at
least a loss of strength.

9.  Cold diluted weaken the fiber if exposure is prolonged.
Effect Of Organic Solvents:
 Most petroleum solvents used in dry cleaning do not damage the
fibers.
 Solvents such as acetone , phenol , chloroform will destroy the fiber.
 Trichloroethylene will swell them.
 One should be cautions when using finger nail polish remover near
acetate, as it often contain acetone.
 Acetate should be handle carefully when removing stains, as some
stain removers contain chemicals that might damage the fibers.
Effect Of Sunlight, Age, AndMiscellaneousFactors:
 Acetate loses strength and may develop splits after prolonged
exposure to sunlight.
 Over time acetate will become weaker from aging. Although storage
away from sunlight and circulating air will delay the process.
Static Charges:
 All acetates, both regular and tri-acetate develop static charges when
air is very dry.
 The fibers are poor conductors or electricity, which contributes to
development of static..
BiologicalProperties:
Micro Organisms:
 Fungi such as mildew and bacteria may discolour acetate and tri-
acetate.

10.  Some weakening of acetate may occurs but tri-acetate retain its
strength.
Insects:
 Moths and other household pets do not damage acetate fibers.
 However, silverfish may attack any sizing on acetates or tri-acetates.
Uses AndCare Of Acetate:
 It is used by many designers for its outstanding drapability and its
desirable hand.
 Acetate can be made into fabrics of varying weight , thickness ,
degree of stiffness and appearance.
 Because of its thermoplastic property one should make sure that
laundering or dry cleaning is carried out at temperature below those
that might cause damage.
 Acetate fabrics should not be twisted when wet because they retain
wrinkles and crease would be require considerable ironing or steam
pressing.
 Acetate fibers are use in various industrial applications. One of the
most important use of acetate fiber as filter media for cigarettes.
 Apparel- Blouses, dresses, linings, special occasion apparel, Home
Fashion - Draperies, upholstery, curtains, bedspreads