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The Manufacturing Process for Viscose
Rayon
The pictures below show how viscose rayon was
made about the middle of the 20th century.
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A river of spruce logs floating downstream to the mills . . |
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. where they are debarked, chipped into small pieces and boiled
in these digesters with sodium bisulphite. The boiled pulp is
then washed, shredded and made into sheets of pure wood pulp. |
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Here the sheets of wood pulp have been transported to the
viscose manufacturer where they are being weighed prior to steeping
in the required amount of caustic soda solution. |
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After steeping for the required period, the sheets are squeezed
to remove excess caustic soda before being kneaded into 'alkali
cellulose crumbs' in a pfleiderer such as that shown here. The
crumbs are then emptied out and left to mature for a short
period. |
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The crumbs are then churned with the correct amount of carbon
disulphide, in what is a scaled-up version of the butter churn
used by The Viscose Spinning Syndicate. The cellulose is
converted into cellulose xanthate (viscose) during this process. |
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The viscose is aged and stored in tanks from whence it is forced
by air pressure to the a large array of spinning machines. |
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Each spinning machine has a spinnerette containing many holes,
each producing a strand. (enlarged view) |
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A gear pump (lower part of picture) controls the flow of viscose
through the candle filter (top of picture) which removes any
particles which might block the spinnerette (left of picture)
The viscose is forced through the spinnerette into an aqueous
solution where it is converted back to cellulose in the form of
continuous filaments. The strand of filaments is collected on
the rim of a wheel (godet) turning at a constant speed. The
filaments are then stretched whilst still wet by passing over a
second godet rotating at a faster rate. |
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The strand passes down a funnel and drops into a rotating
spinning box (Topham box) shown at the top of this picture. This
twists the filaments of the strand which is forced to the
outside of the box by centrifugal action, and is wound into a
'cake'. Each Topham box is connected by a short spindle to a
high speed motor shown at the bottom of picture. The Topham box
was typically moulded from bakelite and Courtaulds set up their
own moulding department for their manufacture. |
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The 'cakes' are conditioned, marked with identification and
wrapped, before being washed, bleached and rewashed by machine. |
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The cakes are dried in hot air. After drying, the strands are
then wound from the 'cake' into a form, such as 'cakes' or
'cones' suitable waeving or knitting processes. |
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Here yarn is being wound from cones onto a 'warping swift' prior
to weaving. |
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