1. * GB780124 (A)
Description: GB780124 (A) ? 1957-07-31
Improvements in and relating to the manufacture of viscose
Description of GB780124 (A)
PATENT SPECIFICATION
Inventors: IHARIOLD BAR1RATT and TIOMAS NEWTONFORRESTER ___ 7809124
Date of filing Complete Specification Nov. 4, 1955
Application Date Nov. 5, 1954.
No. 32050/54.
Complete Specification Published July 31, 1957.
Index at acceptance:-Classes 2(2), AS2B; and 59, A17.
International Classification:-B02d. C08b.
COMPLETE SPECIFICATION
Improvements in and relating to the Manufacture of Viscose We,
CoUrTAULDs LiMITED, a British Company, of 16, St. Martin's-le-Grand,
in the City of London, England, do hereby declare the invention, for
which we pray that a patent may be granted to us, and the method by
which it is to be performed, to be particularly described in and by
the following statement:-
This invention relates to the manufacture of viscose.
In one method for the manufacture of viscose, alkali cellulose is
converted to cellulose xanthate by churning in the presence of carbon
disulphide and the resultant cellulose xanthate is agitated with
dilute aqueous caustic alkali solution in a mixer to effect
dissolution.
Usually, d(luring the churning operation, the cellulose xanthate forms
ball-like lumps which are difficult to dissolve in caustic soda
solution and it is customary to pass the lumps together with the
solution in the form of a slurry through a granulator to break the
lumps into small particles.
The use of one type of granulator is described in British Patent
Specification
No. 042,270 in which the slurry of cellulose xanthate and caustic soda
solution is passed into a vertical cylinder divided into a number of

2. compartments by perforated plates in which the perforations are of
diminishing size on passing downwardly through the compartments.
Rotating paddles are placed above each plate to force the solid
particles of cellulose xanthate through the perforations.
The object of the present invention is to facilitate the dissolution
of cellulose xanthate in aqueous caustic soda solution.
According to the present invention an apparatus for breaking up lumps
of cellulose xanthate in a slurry of cellulose xanthate and an aqueous
caustic soda [Price 3s. 6d.] solution comprises a vertical cylinder
having a circular, rotatable perforated plate upon which the slurry is
deposited and a roller, rotatably mounted so that it 50 lies across a
radial line of the plate and capable of being rotated by frictional
contact with the plate, for squeezing the lumps of cellulose xanthate
through the perforations in the plate. 55 The apparatus according to
the invehtion may form a stage of a conventional granulator, for
example of the type described in British Patent Specification
No. 642,27.0, or may be mounted directly 60 upon a mixer.
When the roller is conical in shape it is preferably mounted freely on
an axis inclined at an angle of about 10 from the vertical. The
perforated plates may 65 comprise grids made up of bars of tapering
cross section set apart with the narrowest portions pointing downwards
so defining between them spaces which diverge in a downwards
direction. 70 A specific apparatus constructed in accordance with the
present invention in combination with a conventional granulator is
illustrated in the drawings accompanying the provisional
specification, in 75 which Figure 1 is a front elevation in section,
Figure. 2 is a plan view of part of Figure 1, and Figure 3 is an
enlargement of part of 80 a section through Figure 2 along the line !l
I- -III.
Ir, Figure 1, a vertical cylinder 1 has a centrally disposed shaft 2
rotatable by driving means (not shown) in bearings 3, 85 3'. The
bearing 3 is supported centrally inl the cylinder l by a spider 4.
A webbed support 5 fixred to the top end of the shaft 2 and rotated by
the shaft 2 carries a circular grid plate 6 90 upon which rests a
conical roller 7 freely mounted on a stub shaft 8 which is set at aii
angle of T' to the shaift 2 and fixed to a dome 9 of the cylinder I.
The roller 7 makes a radial line contact with the plaie t3 and is
rotated by frictional contact with the plate 6. The plate 6 is made up
of a number of segmnents, 10, one of which is shown in Figure 2. Each
segmnent 10 comprises a, number of taper section bars 11 fixed at
spaced intervals onl rods 12(igr 3). The bars 11 are so fixed that the
-narrowest parts in section point downwards thus forming spaces
between them that diverge in a down-ward direct-ion.
Be-low the suniport 5 is a granulator of conventional con-struction

3. consisting1 of a -unumber of statienary webbed supports 13 (-two onuly
eigshown) each fixed to the fylinder 1 and each supporting a g-rid
plate 14 swept by paddles 1.5 fixed to the shaft 2.
The grid plates 14 have the same constoruction as the grid plate 6,
with the exception that the bars 11 are set closer tg,'e t)er in ea
esesive plate 14 on lsigdownwardlx through the cylinder 1. A discharge
pi-n le,1 having a valve 17 is fitted to the bsa'e of the cylinder I
and leads to a conventional mixer IS.
In operation, a slurry of cellulose xanithate in auuscstcsoda
soluntion containing bali iike lumps 19 is introduced into the dloin J
through an inlet rpipe 20 dimt Pyopposite the line contact between
I-ie 1lote fi end the roller 7. The lumps 19' are trIrnped in a space
21 between the ioller 'mad the plate 6.
As the plate 6 ls otated by the shaft 2, the Ilunips 192 re cariried
into the nil) formed between ibie roller 7 and the plate 6 and are
forced throutgh the spaces - between the bars 11 in the plate 0.
Sinice the spaces diverge in a downwvards direction there is no
tendency for cellulose xanthate to block the plate 6.
If an excess c.[ celluilose x-anthate is - -introdluced to the nip,
the roller 7 is forced up the shaft 8 and Jamming is thereby
prevented. The roller i al under gravulY to its n-ormal1 position as
the (cellulose xanth-a.te is forced through the --plate 6.
The cellulose xanithate iio-w in a more finely divided formn falls on
to tho -upperMost Plate 14 truhwhich it is forced by the paddle 1.5.
The cellulose xanthate jpases thirough ech successive lplate 14 cud is
r'dil aoe down into smaller l:Cr'ci Yhich ziit finally delivered to
ret.i'4i w ib1 11e aqu11eous sodiuni 60 hit(lrioxide oltu, oni to the
mixer 18 by way U. the p)itpe"' In ihe miixer I. the slurry is
agtrated, anid owin2' to iteaa fueness of division of the celllose- x
mlh tulie ljdirtieles dissolution iapuid tly plate y ielding a visCose
tartn 0 iee fiom lumps of m'ldi;olved eel'ulose xant'iate.
It. de ised the islates 14 amd paddles 1.5 inay be omitteli arid dhe
shunrv discharged 70 fronr the plate;i ill my be piased directly to
thc mixe ci I The cylinder 1 miay be mnountea directlyv on the mtixr
18, the shalt 2 tlhei paessing into the mixler 18 and having one 75 or
mnore paddies lixed thereto for the agitation of the slurry.
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