Manufacturing Viscose Rayon

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Manufacturing Viscose Rayon 2015-09-22T06:35:58+00:00

The Manufacturing Process for Viscose Rayon

The pictures below show how viscose rayon was made about the middle of the 20th century.

A river of spruce logs floating downstream to the mills . . 
. 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.
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.
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.
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.
The viscose is aged and stored in tanks from whence it is forced by air pressure to the a large array of spinning machines.
Each spinning machine has a spinnerette containing many holes, each producing a strand. (enlarged view)
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.
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.
The ‘cakes’ are conditioned, marked with identification and wrapped, before being washed, bleached and rewashed by machine.
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.
Here yarn is being wound from cones onto a ‘warping swift’ prior to weaving.