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Патент USA US2114605

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reamed Apr. is, less
cause can
William n. Nicoll, Wgton, not. assignor, a
meme assients, to IE. ll. du li’ont dc New
mom's d:
Del... is} Mill"
Duration or a.
No Drug. Application Novenoberhd, ltdél, Sc»
owed depternber 1d.
rlal No. ‘lSddW.
8 Girl.
This invention relates to an improved process
for the preparation or alkali cellulose for use in
the manufacture of viscose and cellulose others.
In the preparation of viscose and cellulose
53' others an intermediate in most processes is alkali
cellulose. In the manufacture of viscose shredded
alkali cellulose is ripened and reacted with carbon
dlsul?de to give cellulose xanthate, which is then
dissolved in alkali solution and extruded to give
in‘ ‘?lms, bands, threads, tubing and the like. In the
manufacture of cellulose ethers many processes
react shredded alkali cellu‘ "c with an etheriiy
ing agent such as ethyl cl. ride, methyl sulfate
and the like. in both viscose and etheri?cation
id processes the reaction is essentially a multiphase
reaction wherein the solid alkali cellulose reacts
(@311. tddm-lldlll
cally new or diilierent eoiupment from that ordi
narily used in the present manufacture of viscose.
The essential step of the invention, as applied to
viscose manufacture, is the use of a wetting agent
in the steeping caustic followed by the modi?ca- .
tlon of other steps in the process, such as the
use or low=press weight ratios and reduction in
the amount of carbon disulude used in nanthation.
Any organic compound or mixture of organic
compounds which is soluble in the caustic solu~ M
tion and capable oi’ effecting a marked decrease
in the interiacial tension between cellulose and
a mercerizing caustic solution may be taken to
be a wetting out agent suitable for use in this -
invention. “litre principal agents which have been 25
found to be edectlve are: alkali metal salts of
sulfuric acid esters of saturated aliphatic alco
with a reagent in another phase. _
This invention has as an object the prepara ‘hols having ii to‘ 8 carbon atoms, phenols, cre
tion or a shredded alkali cellulose of improved sols, mlenols, and their homologs, either alone
physical characteristics such as small particle size or in combination with aliphatic, aromatic, or 20
alicyclicalcohols, ketones, and others of poly
and increased bulk. A further object is the prep
aration of an alkali cellulose of improved physical hydric alcohols containing free hydroxyl groups
characteristics especially adapted for use in the
and fatty acids sulionated to such a degree that
manufacture or viscose and cellulose ethers. A they are soluble in caustic soda solutions oi‘ above
25, further object is the facilitation oi‘ the shredding 15% concentration. A particularly preferred wet
of alkali cellulose especially of alkali cellulose prev? ting agent is that wetting agent or class of wet
ting agents sold under the trade name of “Alkanol
pared from caustic solutions about 20% in con
centration. A further object is the ready main-' M” which are sodium salts of acids prepared by
tenance of lower temperatures during shredding. the oxidation of the mixture or oxygenated or
ganic compounds obtained by the catalytic hy
30 A still further object is improved viscose ?ltra
drogenation of carbon oxides under elevated tem
tion. A still further object is improved shred
peratures and pressures. Salts of varying char
, ding of alkali cellulose of press weight ratios be
low 3.0 such as 2.5. Other objects will appear acteristics are obtained from different fractions
otthe alcohols thus obtained, the salts of acids
35 These objects are accomplished by the follow‘! containing 4 to 8 carbon atoms being particu
larly useful. These acids may be prepared by
ing invention wherein alkali cellulose for the man
I ufacture of viscose or cellulose ethers is prepared the processes of U. S. Patent 1,856,263, or by the
by steeping cotton linters cellulose in a 16% to two-step oxidation of the alcohols to the acids.
These agents are employed with cotton lintersv
50% solution of caustic alkali in the presence of
40 up to 1/z% oi’ a wetting agent. Further steps in cellulose and with any grade oi’ caustic soda of
the invention in the case of viscose manufacture, suitable strength for mercerizatlon of cellulose.
include the pressing off of the mother liquor so The e?ciency oi the wetting agent has been
that the weight of the alkali cellulose is not more found to increase with the purity of the cellulose
than 2.8 times the weight of the original air-dry and caustic soda employed.
Having outlined above the generahprinciples
45 cellulose, shredding, aging, xanthation with not
more than 35% of carbon disullide, based on the oi the invention, the following applications to
dry weight of the cellulose, and dissolving in di the manufacture of viscose are given for purposes
lute caustic to form a viscose solution which may of illustration and not in limitation.
Subsequent to steeping cellulose in caustic so
be ?ltered, ripened, and spun in the usual man
50 nor; or in the case of the manufacture of cellu
lose ethers, the alkali cellulose is pressed, shred
tied, and treated with an alkylating or aralkylat
lng agent to form the desired ether.
In carrying out the various steps of the pres
55 out invention, it is not necessary to use any radi
lution containing one or more of the wetting out 50
agents referred to above, the cellulose is pressed
out to a degree such that the total weight of the
alkali cellulose is not more than 2.8'times the
weight of the original cellulose. This low-press
weight, as will be discussed later, permits vthe use.
of reduced quantities of carbon disulfide so that
after aging the alkali cellulose in conventional
manner, it may be xanthated using 10% to 20%
less carbon disul?de than is normally required,
after which it may. be dissolved in dilute caustic
soda solution to produce viscose.
The following examples disclose the carrying
out oi‘; these processes:
of a slightly more reddish color and is found to
ripen at a slightly faster rate than viscose pre
pared by the process of Example 1. The viscose
solution ?lters at a 33% higher rate than when
the same linter-s and caustic solution is used
without the wetting agent.
Example 4
Example 1_
process is characterized by substantially the same
properties as described for the product of. Ex
ample l,’ with the exception that the solution is
Six hundred parts oi’ cotton linters cellulose in
the form of heavy sheets approximately 0.033"
The process outlined under Example 1 is modi
thick are steeped for one hour at 18° C. in 6000
?ed by changing the press ratio from 2.5 to 2.8,
8000 parts of an 18% solution of caustic soda increasing the amount of carbon disul?de used
containing 0.25% of “Alkanol M”. Alkali cellu
during xanthation to 32 parts for each 100 parts
lose formed in this manner is pressed until the of cellulose and reducing the time of xantha
weight of pulp and caustic liquor is 2.5 times the tion to 3% hours at 25° C. The alkali cellulose
original weight of the cellulose and is then shreds produced in this case is somewhat easier to shred
ded or disintegrated in equipment of the type than that produced by the process outlined in
20 of a. Werner 8r Phleiderer shredder having cut
Example 1, but the e?iciency of the xanthation
ting blades and a serrated saddle and jacketed‘ reaction is slightly lower due to the increase in
for cooling the charge. This alkali cellulose dis
free alkalipresent in the alkali cellulosev and,
integrates with reasonable ease altho in the ab
therefore, it is not possible to reduce the amount
sence of such a wetting out agent alkali cellulose - of carbon dlsul?de used in this case to quite the
of like press-weight is found extremely difficult same degree as in Example land at the same
to shred. The distlntegrated alkali cellulose is time produce a, viscose of equivalent quality as
next aged at 18° C.‘for 55 hours in order to re
regards ?ltration characteristics.
duce the viscosity of the cellulose and is then
Example 5
xanthated during four and vone-half hours at
30 25° C. in a rotating drum, using 30 parts of car
The process of Example 4 is modi?ed by sub
> bon disul?de to 100 parts of air dried cellulose. stitution of an equivalent quantity of a mixture
The light orange yellow cellulose xanthate formed of three parts xylenol and one part butyl Cello
in this manner is dissolved in an excess of dilute solve for the “Alkanol M” used as wetting agent.
caustic solution in such manner that a viscose The aging time for the alkali cellulose is also
35 solution results containing approximately 7% increased approximately 15 hours because of a
cellulose and 6% total alkali. In spite of the ' retarding action which the xylenol has on the
reduced quantity of carbon disul?de used in the viscosity reduction of the cellulose. The quality
preparation of this viscose, the product is of of the viscose produced is substantially the same
excellent quality as indicated by the fact that as obtained with Example 3.
g 40 the rate of ?ltration thru a ?lter medium com
Instead of the conventional type of equipment
posed of closely woven cloth interlayed with cot
mentioned in the foregoing example, it is per
ton batting is decidedly faster than for viscose missible to use other, equipment‘ for carrying out
prepared from the same cellulose by a process any step in the process. Thus, the cellulose
involving, for instance, no wetting out agent, linter sheets may be mercerized in the form of
45 higher press-weight, such as 3.0 and 35 parts of a continuous roll by passing thru a caustic bath
carbon disul?de used for 100 parts of cellulose. containing wetting agent ‘and between squeeze
Furthermore, the low quantity of carbon disul?de rolls to secure low press-weight ratios herein
used in the formation of this viscose solution speci?ed. Shredding of the alkali cellulose may
greatly minimizes the amounts of objectionable also be accomplished in a number of di?erent
50 by-products present in the viscose and also re
ways, as by means of the hammer mill, attrition
duces the excess carbon disul?de combined with mill,>cotton picker or any equipment producing
the cellulose which it is believed is the cause of ' a similar e?ect. Aging of the alkali cellulose
milkiness in yarn.
Example 2
As illustrating the improvement due to the use
- of the wetting agent it was found in another run
using the same cotton linters and caustic solu
tion as in Example 1 that it was necessary to
00 increase the press weight to 3.0 and to use 35
parts of carbon disul?de per 100 parts of cellu
lose but that the quality of the viscose was less
satisfactory as indicated by the rate of ?ltration,
'which was 27% faster for the viscose of Exam
65 ple 1 than for the viscose of Example 2.
'Example 3
Viscose is prepared by a process closely re
sembling that outlined in Example 1 with the
70 exception that a mixture of three parts cresol
and 1 part monobutyl ether of ethylene glycol
(butyl Cellosolve) is substituted in equivalent
quantity for the “Alkanol M” and the aging time
of the alkali cellulose is made 65 hours instead of
76 55 hours. A viscose solution prepared by this
may be reduced or eliminated entirely by various
means known to the art, such as high tempera
ture shredding 'or by the use of pulp of initially
low viscosity. The xanthation operation itself
may bemodi?ed as regards the equipment used,
so long as the ratios between carbon disul?de and
alkali cellulose are maintained substantially as
While the above examples have disclosed the
application of the invention to the manufacture
of viscose, it is likewise applicable to the manu
facture of cellulose others. A very important
property of alkali cellulose necessary for the pro
duction of cellulose ethers of optimum quality is
a ?ne state of division such that a large surface
is exposed to the action of the etherifying agent.
The presence of a wetting out agent in the steep
ing caustic greatly facilitates shredding and im 70
proves the physical form of the shredded alkali
cellulose. This improvement in physical form is
reflected in the etheri?cation reaction itself.
The following examples illustrate the use of the
invention in the manufacture of cellulose others: 75
8,1 16,605
Purified cotton linters cellulose in‘ the in
thick cardboard-like sheets was steepesl in rev/z,
caustic soda. containing 0.25% of o
ture of
' 75 parts phenol end 25 ports oi monohutrl ether‘
100° C. The crude mixture obtained by t
process was cooled, dispersed in benzyl alcohol,
and coagulated in methanol, The constricted. '
material was washed with methanol, water, dilute
acid, and again with water. The benzyl cellu—'
lose obtained in this manner was of excellent
of ethylene glycol. Alter one hour in the
pins quality, being especially suited for the prepare
caustic. the ellrsli cellulose was removed from the tion of ?lms, ?laments, and plastics.
bath and pressed to three times the orlnnl
The use of a wetting agent in the caustic steep“
weight ‘of the cellulose. This moteriul was ' ing hath insures uniformity of reaction between ill)
10 shredded and nsecl for to hours ct o tempers
caustic soda, and cellulose. The wetting agent
of 10° ‘0., and then trenteri ct 25° G. with % moi. also assists the ‘shredding operation, end even
of ethylene oxide per mol. of cellulose (lull . iovombly in?uences the physical properties of the
The product obtoineu was as low suhstitutecl glycol » cllmli cellulose. The improvement in physical
ether of cellulose one
iounol to'ulssolve coni- . ‘properties of the alkali cellulose is such that
pletely in on one solution oi caustic sods to pro
duce a. high viscosity solution procticollr free of
unperseol ?bers. in contrast to the foregoing,
o. product produced from: the some cellulose in no;
exactly similar conditions in the preporntion oi
20 ollrsli cellulose sncl reoction with ethylene ornile
except that no wettinu out scent wos used in. the
steeping caustic, was iounrl to he only nortlslly
soluble in 8% caustic, nrorlucing rough solutions
contnininu ccnsiuerohle uunntities oi unsolveil
23 ?llers.
lirurngolc 7
line thousonol ports oi cotton llnters cellulose
,wos steepecl for one hour st so“ C. in lull-to ports
30 oi’ 25% caustic soils. containing 0.25% (hoses on
the totol weight of coustic solution) oi“ “Allconol
ill/i1”. This ollroli cellulose woe pressed. out to 2311'
times the orislnnl weight oi’ cellulose unrl
sln‘ericieol so ss to i’orm ?ne crannies. The shreololeol
35 slim-ll cellulose was chnrsecl into on eutocluve
together with i550 ports oi‘ sollcl caustic souls,
loco ports oi’ benzene, snil ssso ports of ethyl
chloride; The nutoclove
hearted and ethnic.
tion olloweu to proceed cluring (+3 hours st 15W C.
“lrhe crucle proéluct ohteinecl ion this process wns
press-weight ratios‘ mey be considerably re
duced below the normal value of 3.0 without cous
inu the nlltuli cellulose to become herd end dim»
cult to shred. The reduction in press-weight
rstios has in turn a. favorable influence on the
xonthstion reaction and permits a. reduction of
irom 10 to 20% in the quantity of carbon clisulhde
used in xonthetion without in any way adversely
sheeting the physiccl properties of ‘the final vie
With respect to the etheri?cetion reoction the
use of the wetting agent in the caustic steeping
tooth produces an nllrnli cellulose of improved
physical form and greater surface nreu which oi» '
lows o. luster and more uniform etheri?cotion 30
reaction than that obtained under normal con~
elitions and results in the production of ethers of
especially uniform solubility, increased toughness
and strength, and excellent working properties.
A. property of viscose which is of extreme lmpor»
tence is the dispersion of the viscose as evidenced
by the ?lterohility of the-viscosesolutlon. The
following table indicates the e?ect or the use of
wetting agents on this most important property: no
Eilectincness of wetting‘ out agents in improving viscose
Character olcellulcse
Wetting agent used
70 min.
_ ting agent
due m Wt_
None .................. ..
0.25% Alkanol M ...... _.
____________ __
Cotton linters-B . _ . . .
None ........... ..
____________ ._
_ ..
0.25% Allmuol M ______ ._
Cotton limiters-0 . . . . .
. ..
N0ne_._.; ............. ._
____________ _,
Cotton linters-
_ .v
0.25‘? Cresol and butyl
33. 3%
Ce losclve.
Mislzltlure oi linters and wood
Percent im
Cotton lintsrc—-A ........ ..
(Cotton iinters-A ........ ..
Cotton linters-B __
54 sq. m in
None .................. ..
947 ____________ __
Mllxtgre oilinters and wood‘ 0.25% Alkanol Mg. .... ..
No c?ect
ul .
oilinters and wood 0.25% Cresol and butyl
No effect
Mpulp ............... ._
None .................. . .
Wood pulp _______________ _. 035% Alkanol M ...... ..
539° ____________ __
No e?ect
° The type oi ?lter cloth was not the same in these cases as with others.
puri?ed by steam clistillotion oi the henrene cnol
woshlng the resiclue with water. The product ob
tained was an ethyl cellulose of excellent soluhih
ity in mixtures of toluene and alcohol, producing
66 ?lms, ?lents, and plastics or" superior qunllty.
Emmple 8
One hunrlrccl ports oi’ cotton. linters cellulose
was treated in a. 25% solution of coustic sous con»
70 toinlng in each 100 ports of solution 0.25 port of
"Aliranol M”. The resulting ollsoll cellulose was
pressw to 300 ports omi shreucleol in the usual
This slknli cellulose was tresteu in e
shredder with 50 ports of solicl caustic soils end
75 315 parts of benzyl chloride for 10 hos st 95%»
It will be noted from the table that the degree
of improvement in filternbility of viscose pro
duced by the use of such agents as "Allrenol M"
or or mixture of cresol and the monobutyl ether
of ethylene glycol ranges between about 27% and 65
64%. It is also of interest to note that the addi
tion of wetting agents in the mercerizotion of
100% wood pulp or even mixtures of wood pulp
,nnd linters has shown little or no advantage, a.
surprising phenomena in view of the marked ecl
vantnge with substantially 100% linters and in
dicetive of some as yet undiscovered cooperative
effect of the wetting agent on the cotton linters
which eilect seems to be substantially absent in
the case of wood pulp.
The concentration at which the wetting out
e?ect of these wetting agents reaches a maximum
varies from about 0.25% up to about 0.35% on.
the basis of 18% steeping caustic, the exact point
of maximum effect depending to some extent on
the speci?c agent used.
alkali cellulose is not‘ more than 2.8 times the
weight of the original air-dry cellulose, shredding
the alkali cellulose, ripening, xanthating with up
to 35% of carbon disul?de, based on the dry
weight of the cellulose, and dissolving the cellui
lose xanthate in dilute caustic to form a viscose
In all cases the concentration of the wetting
agent is maintained below 1/2% and in general
a, concentration at or near that giving maximum
10 wetting out effect under the conditions of use is
solution said wetting agent being taken from the
class consisting of alkali metal salts of acids
having a to 8 carbon atoms prepared by the oxi
dation of the mixture of oxygenated organic com 10.
preferred. This is due not‘merely to the fact that
excess agent is in part wasted but more particu~
larly because the excess agent interferes with
other steps in the process, e. g., the coagulation
bath. Particularly in the case of agents con
of carbon oxides under elevated temperatures and
pressures, alkali metal salts of sulfuric acid esters
of saturated aliphatic alcohols having 4 to 8 car
taining phenols the use of concentrations above
the point of maximum effect is objectionable due
3. The process of preparing cellulose ethers.
which comprises steeping cotton linters cellulose
to the building up of the excess in the coagulating
bath and to the difficulty of washing the phenols
20 out of the product.
in addition to the above advantages of the. use
of these Wetting agents in viscose manufacture, it
has been found that the yarn made in employing
the process of the present invention by reason
25 of the reduced quantities of carbon disul?de used
in xanthation has a reduced tendency to milki
ness. It has also, been found that the reduction
in carbon disul?de made possible by the use of
the process of the present invention may be such
30 that the viscose need not be ripened in the con
ventional manner but may be spun almost imme
diately after preparation.
The above description and examples are in
tended to be illustrative only. Any modi?cation
35 of or variation therefrom which conforms to the
spirit of the invention is intended to be included
within the scope of the claims.
I claim:
1. In the process of preparing alkali cellulose
40 and derivatives thereof, the step which comprises
steeping cotton linters cellulose in a 16 to 50%
aqueous caustic alkali solution containing up to
0.5% of a wetting agent taken from the class con
sisting of alkali metal salts of ‘acids having 4 to
45 8 carbon’ atoms prepared by the oxidation of the
mixture of-oxygenated organic compounds ob
pounds obtained by the catalytic hydrogenation
bon atoms, phenols, cresols, xylenols,‘ and their 15
in a 16 to 50% aqueous caustic soda solution
containing up to 0.5% of a wetting agent, pressf 20
ing, shredding, and treating the shredded alkali
cellulose with an etherifying agent of the class‘
consisting of alkyl and aralkyl etherifying agents.
4. The process of preparing viscose, which
comprises steeping 600 parts of cotton linters cel 25
lulose for one hour at 18"~ C. in 6000 to 8000 parts
of an 18% solution of caustic soda containing
25% of Alkanol M, pressing to 2.5 times the orig?
inal weight of the cellulose, shredding, aging at
18° C. for 55 hours, xanthating at 25° C. during 30
41/,» hours, using 30 parts of carbon disul?de to 100
parts cellulose, and dissolving in dilute caustic
solution to a viscose solution containing ap
proximately ‘7% cellulose and 6% free alkali.
5. The ‘process of preparing glycol cellulose, 35
which comprises steeping cotton linters cellulose
in 18% caustic soda containing .25% of a mixture
of 75 parts phenol and 35 parts monobutyl ether
of ethylene glycol for one hour, pressing to three
times the original weight of the cellulose, shred?
ding, aging-for 48 hours at 18° C.,,and treating
at 25° C. with M4 mole of ethylene oxide per glu
cose unit of the cellulose.
' 6. The process de?ned in claim 1 characterized
in that the caustic alkali is caustic soda.
7. The process of claim 1 characterized in that
tained by the catalytic hydrogenation of carbon
oxides under elevated temperatures and pres
the aqueous caustic alkali solution is an aqueous
sures, alkali metal salts of sulfuric acid esters of
of a wetting agent.
caustic soda solution containing 0.25% to 0.35%
saturated aliphtic alcohols having 4 to 8 carbon
8. The process de?ned in claim 1 characterized 50
atoms, phenols, cresols, xylenols, and their homo 'in that after steeping the cellulose is pressed to
remove mother liquors so that the weight'of the
2. The process of preparing viscose, which
comprises steeping cotton linters cellulose in a.
16 to 50% aqueous caustic soda solution contain
ing up to 0.5% of a wetting agent, pressing off the,
mother liquors so that the weight of ‘the pressed
premed alkali cellulose is not more than 2.8 times
the weight of the original air-dry cellulose, and
is shredded.
" ‘
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