Soaking in caustic soda
In this
process the wood pulp is soaked in sodium hydroxide to produce soda cellulose
which is squeezed to remove the extra caustic soda solution .
Shredding
The crumbs
of soda cellulose are shredded to produce small flakes.
Ageing
In this
process, the shredded soda cellulose is aged for a certain time to adjust the
molecular structure.
Xanthating
The aged
cellulose is mixed with carbon disulphide to produce by chemical reaction
xanthate
Dissolving
The xanthat
is dissolved in sodium hydroxide to produce xanthate solution for spinning.
De-aeration and filtration
In this
process, the xanthate solution is stored in tanks under vacuum to remove any
air bubbles, and is passed through multi stage filters to remove any trash
particles, and when
the viscose solution is ready for extrusion after a period
of ageing, it is pumped to the extrusion spinnerettes
Spinning
Viscose
solution is pumped to the spinnerettes, which are Immersed in dilute sulphuric
acid bath, and when the solution emerges it reacts with the acid and is
solidified to a continuous filament that is subjected to stretching and wound
inside a rotating pot to form the viscose yarn package.
Scouring
The viscose
yarn packages are scoured and washed to remove residual salts and acid.
Winding
The finished
viscose filament yarn is then wound on winding machines to the required forms
of packages.
Scouring and crimping
This process(for
filament tows) is especially for the production of viscose fibers, and
is carried out on a separate production line, where the tows of continuous
filaments coming out of spinneretts, are collected scoured, washed, crimped and
dried.
Cutting and pressing
At this stage a layer of viscose crimped filaments transforms
the filaments to fibers with length similar to cotton or similar to wool. The
resulting fibers are pressed into bales as final product.