2. OUTLINE
Definition of dry spinning
Reaction
Raw materials
Process
Characteristics
Applications
References
3. Dry spinning
The polymer is dissolved in
a volatile solvent and the
solution is pumped through
a spinneret (die) with
numerous holes (one to
thousands).
As the fibers exit the
spinneret, air is used to
evaporate the solvent so
that the fibers solidify
6. Raw materials
CELLULOSE: [C6 H7O2(OH)3]n from pulp
ACETIC ACID: CH3COOH and ACETIC
ANHYDRIDE: CH3CHO
SULFURIC ACID: H2SO4
7. Process: Fiber formation
Purified cellulose from wood pulp or cotton linters.
Mixed with glacial acetic acid, acetic anhydride and
a catalyst (sulfuric acid).
Put through a controlled 20 hour partial hydrolysis to
remove the sulfate and the required amount of
acetate molecules to obtain the product’s desired
properties.
9. Process: Fiber formation
Precipitated as acid-resin flakes
Flakes is dissolved into acetone
Solution is filtered
10. Process: Fiber formation
The liquid substance of
cellulose is forced
through a metal cap
called a spinneret
The filaments extruded
from the holes in the
spinneret, the liquid
polymer becomes
rubbery and then
solidifies by hot air
Solvent recovered
13. Process: Stretching & Orientation
While extruded fibers are solidifying, or in some
cases even after they have hardened, the filaments
may be drawn to impart strength
The filaments are stretched while till plastic to
increase strength
The filaments are then spun into fiber
14. Characteristics
Classify: diacetate fiber and triacetate fiber
Diacetate (acetate): 74% - 92% hydroxyl has been
acetylated
Triacatate: > 92% hydroxyl has been acetylated
15. Characteristics
Feels natural and is gentle on the skin
Elegant gloss and chromogenic quality
Drapes lightly and flexibly
Ideal water absorption and quick-drying qualities
Does not shrink easily, so provides stability for
dimensions and measurements
Strong pleating durability (triacetate)
17. Applications
Filter cigarette tow :good
filtration properties with
good acceptance of the
taste signature, good
biodegradability profile
Separation technology
Drinking water
purification, waste water
treatment
18. References
Synthesis of Material: An approach from Chemistry
Dr: Le Minh Thang, HUST, 2008
www.kpatents.com
Mitsubishi Rayon Textile Co. LTD
Wikipedia. Org and other sourses