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Patented Sept. 17, 1946
2,407,909
UNITED STATES PATENT OFFICE
PURIFICATION OF CRUDE CELLULOSIC
MATERIAL
‘
George P, Vincent, Poughkeepsie, N. Y.-, and
ArchieL. Dubeau, Rumfcrd, R.,I., assignors to
The Mathieson Alkaii V‘Jorks, Inc., New York,
N. Y, a corporation of Virginia,
No Drawing. Application September 18, 1940-,
Serial No. 357,281
4 Claims.
( Ci. 92-43 )
1
2
This invention relates to the puri?cation of
crude cellulosic vegetable material, such‘ as
ground wood, cotton linters and carding waste,
which contain large proportions of natural non
cellulosic impurities such, for example, as lignin.
The invention contemplates the production from
such materials of relatively pure cellulose suitable
for acetylation, nitration and other uses, includ
ing paper manufacture. In one of its aspects, the
invention contemplates improvements for con
trolling the viscosity‘characteristic of the. cellu
cotton-cleaning processes, our preferred prelimi
nary treatment involves stearning the material
while it is impregnated with a decidedly'alkaline
solution, containing at least 4% caustic soda, and
loss product.-
’
"
l
I
In accordance with our invention, the crude
cellulosic vegetable material to be puri?ed, for
example ground wood, cotton linters, carding
In
also containing a suitable detergent, i. e., one that
is active in alkaline solution.
A wide variety of
detergents may be employedsince common soaps
and numerous synthetic ‘detergents. are active in
alkaline solution. If hypochlo'rite treatment is
employed, this should vfollow the. alkali-steaming
stage. , In any case, the- later treatment involves
the exposure of the material, in the presence. of
steam, to the action of a hot acid solution con
taining sodium chlorite and, preferably, also con
taining a detergent that is active in acid-solution,
Waste, bagasse and the like‘, is‘ subjected to a two
, such,.for example, as sodium ocenol sulfates‘, boro
stage steaming while impregnated'with hot aque-'
cetyl alcohol and sodium alkyl sulionate benzene.
Certain synthetic organic‘ detergents,‘ for ex
ous liquors.
In the‘ ?rst of said stages the ma
terial is exposed to the action of steam while‘ im
pregnated with a decidedly alkaline aqueous so
lution of- caustic soda, that is, one’ containing at
ample, ‘.‘Modinal? which is a completely sulfated
sodium ocenol sulfate, are‘ active in acid and a1
least about 4% of caustic’ soda. in the second
kaline solutions and may be employed in the
preliminary alkaline stage and in the acid-chlo
steaming operation the material, arteran inter
rite stage.
mediate water washing, is exposed to‘ the action
of steam while impregnated with‘ an acid aque-.
treatment liquors with various reagents, but so—
ous solution sediuin chlo'rite, in amount effective
to eliminate a substantial part of the non-cellu
lose impurities remaining in the material; ‘These
steaming operations are carried out in a steam,
chamber and are of considerable duration, gen-*
erally of the order of a half-hour‘ or more. With
Alkalinity may be imparted to the preliminary
dium hydroxide is preferred.
. A- Variety of acids may be employed to acidify‘
the chlorite liquors. We prefer, however, to use
acetic or phosphoric acids.
cotton linters, carding waste and similar low
ri‘he application of the process of our invention
to the puri?cation of ordinary raw cotton linters
which have received no preliminary cleansing is
grade cotton plant Icy-products, the preferred
illustrated by the following two examples:
preliminary treatment involves exposure in the
presence of steam'to the action‘ of a hot alkaline
aqueous solution containing a detergent.
Control of the viscosity characteristic of-the
cellulose product may be accomplished- advanta
geously by treating the cellulosic material‘, pref
era-bly at an intermediate stage, with an aqueous
‘ Example A.—-Two-stage' treatment for raw
cotton linters
A quantity of linters is immersed in a solution
containing 12% sodium hydroxide, and .5% of
a detergent,‘ say, “Modinal/i After immersion,
the linters are squeezed to drive out excess solu
hypochlorite solutiongpre'ferably in a cold state.
tion and leave a ratioot two parts by Weight '
Thus, sodium hypochlorite solutions tend to re
du‘ce the viscosity characteristic of the cellulose
of solution to one part by Weight of solid.
The
resulting Wet linters is then introduced into a
steam chamber and held at 100° C‘. for about one
and also aid in impurity removal’. When control
of the‘ viscosity characteristic’
important, as 1.15 half hour in the presence of the steam. "There
after, the partially puri?ed linters is Washed with
when the puri?ed cellulose is to be‘ converted into
nitrate, acetate or other esters,‘ hypoch‘lorite
~ The washed linters is immersed in a solution
treatment is especially recommended, for by reg
containing 1% available chlorine (C12) as sodium
ulating the contact of the material with the hy
pochldrite through control‘ of the’ time of treat iii) chlorite, 5% of a suitable detergent, say “Modi
nal,” and 3% by weight of acetic acid (56%
ment or the concentration of the hypochlorite,
strength). The‘ linters is then squeezed to re
Viscosity characteristics maybe altered at will.
hot
To consider in somewhat greater detail the
water.‘
'
‘
>
move‘ excess solution and leave a ratio of two
puri?cation of linters and similar low-grade by
parts by Weight of solution to one part by weight
products of cotton ginning, carding and similar
of solid.
The wet linters is then held at a tem
2,407,909
4
3
mersed in a sodium hypochlorite solution con
taining 1% available chlorine and, as in the pre
chamber and ?nally washed with hot water.
vious cases, thereafter squeezed to leave a ratio
A sample treated according to the foregoing
of 2:1 liquor to solids. The squeezed mass was
example was satisfactorily puri?ed, was entirely
then held at room temperature for half an hour
Cl
suitable for acetylation or nitration and had a
and thereafter washed with hot water. 1
satisfactory white appearance._
In the third stage, the mass from the pre
perature of 100° C. for one-half hour in a steam
Example B.-—Three-staqe treatment of raw cot-- ‘
' vious treatments was immersed in a solution con
ton linters
taining .5% available chlorine as sodium chlo
In this instance, a mass of dry raw linters was 10 rite, .5% “Modinal” and 1% acetic acid (56%).
After immersion, the mass was squeezed to leave
immersed in a solution containing 8% sodium
hydroxide and .5% “Modinal.” It was then
two parts by weight of liquor to one part by
weight of solids and the mass was then held at
squeezed to leave two parts by weight of solution
100° C. for about one-halfhour in the steam
to one part by weight of solid and the resulting
wet pulp was held for one-half hour at 100° C. 15 chamber. Finally, the mass was washed with}
hot water.
in a steam chamber. ‘It was then washed in hot
The resulting cellulose had a whiteness of 80+
water.
and was at least as good as that heretofore cus
The washed mass was immersed in a 1% by
tomarily employed in acetylation.
_
weight aqueous solution of sodium hvpochlorite
Linters which have been cooked in the usual
and then squeezed to leave a 2:1 liquor to solid 20
way and so partially cleansed may also. be treat
ratio therein. The squeezed mass was left at
ed with advantage in accordance With our in
room temperature (approximately 30° C.) for
vention. Such treatment, however, need not em
about half an hour and then washed in cold
ploy such strong solutions as those employed in
water.
The washed mass from the second-stage was 25 the treatment of raw and low-grade linters.
Treatment of cooked linters in accordance with
immersed in the solution containing .5% avail
ourinvention is illustrated by the following ex
able chlorine as sodium chlorite, .5% “Modinal”
and 1% acetic acid (56%). After immersion,
ample:
the mass/Was squeezed to remove excess liquor
and leave a ratio of 2:1 liquor to solids. There
after, the mass was held at 100° C. for about
half an hour in a steam chamber and ?nally
,
'
‘
.
Example E.-—-Two-stage treatment of cooked
30
lintersv
A dry mass of-‘cooked linters was immersed
in a solution containing 4% sodium hydroxide
washed with hot water.
and .5% “Modinal.” The material was then
The resulting product was satisfactory for use
in acetylation, nitration and the like, and was 35 squeezed to leave two parts by weight of liquor
to one part by weight of solids and thereafter
fully as white asv standard puri?ed linters em
held
'at 100° C.‘ for about one-half an hour. in
ployed heretofore in such processes.
a steam chamber. The steamed material'was
Very low-grade linters (cotton seed hull ?ber)
washed with hot water.
7
"
containing an especially high proportion of im
The washed linters was immersed in a solu
purities may also be treated advantageously in 40
tion containing 25% available chlorine as so
accordance with the process of our invention in
diumchlorite, .5% “Modinal” and .5%" acetic
two or three stages.
Example. C,--Two-stage treatment of low-grade
‘
acid (56%).
After immersion, the mass was
squeezed to leave two partsby weight of liquor'
to one part by weight of solids and thereafter
linters
, A mass of dry linters (cotton seed hull ?ber)
was immersed in an aqueous solution containing
held for about one-half hour at 100° C. in a steam
12% sodium hydroxide and .5% “Modinal” and
with hot water.
chamber. After heating, the material was washed ‘
.
As in the previous cases, the resulting prod
2:1 liquor. to solid ratio. The mass was then 50 uct was comparable with'cotton linters hereto
fore employed for acetylation purposes and was
held at 100° C. for about half an hour in a stem
of standard whiteness.
,
'
chamber and thereafter washed in hot water.
squeezed to remove excess liquor and leave a
The washed mass was immersed in an aque
' In the treatment of low-grade cotton by
products, such as carding waste, the process of
sodium chlorite, .5% “Modinal” and 3% acetic 55 the invention also offers advantages. Applica
ous liquor containing 1% available chlorine as
acid (56%). After immersion,'the mass was
squeezed to remove excess liquor and leave a
2:1 liquor to solid ratio. The mass was then
steamed in a chamber for one-half an hour at
Y tion of the process to carding waste with a very
high percentage of impurities and which con
tained whole seeds is illustrated by the following
example:
100° C. and ?nally washed with hot water.
60 Example’ F.—T'wo-stage treatment of carding_ ~
The resulting cellulose was suitable for acet
waste
ylation and compared favorably in whiteness with
The dry carding waste (card strip waste) was
that produced according to Examples A and B
immersed in a solution containing 8% sodium hy
from ordinary raw linters.
droxide and .5% “Modinal,” squeezed to leave a
Example D.—Three-stage treatment of loin-grade
2:1 liquor to solid ratio and held at 100° C. for
raw linters
‘ '
A mass of raw linters was immersed in a so
about one-half an hour in a steam chamber. It
was then washed with hot water.
'
The washed material was immersed in a solu-’
“Modinal.” After immersion, the mass of linters 70 tion containing 1% availablechlorine as sodium
chlorite, .5% “Modinal” and 2% acetic acid
was squeezed to leave a ratio of 2:1 liquor to
(56%). After immersion, material was squeezed
‘solids. The mass was then held at 100° C. for
to leave a 2:1 liquor to solid ratio, held at 100° C.
‘about half an hour in a steam chamber and there
for about one-half hour in a steam chamber and
after was washed with hot water.
,
lution containing 8% sodium hydroxide and .5%
The material from the ?rst stage was im
thereafter washed with hot water.
5
2,407,909
The resulting material was bleached to a color
as good as that obtained in the foregoing exam
6
3. A process for purifying crude cellulosic veg
etable materials which comprises impregnating
ples and in general all non-:cellulosic impurities
said material with an alkaline aqueous solution
were removed. The product contained a few par
etable materials which comprises impregnating
containing about 4 to 12% of caustic soda, dis
charging solution from the material until the ra
tio by weight of solution remaining in the mate
rial to the material is about 2:1, exposing the
said material while wet with the solution to the
said material with an alkaline aqueous solution
action of steam for a period of at least about one
tially bleached hulls.
We claim:
1. A process for purifying crude cellulosic veg
containing about 4 to 12% of caustic soda, dis 10 half hour in a steam chamber, thereafter wash
charging solution from the material until the ‘ra
ing the material with water, impregnating it with
tio by weight of solution remaining in the mate
an acid aqueous solution containing a detergent
rial to the material is about 2:1, exposing the
and sodium chlorite, discharging solution. there
said material while wet with the solution to the
from until the ratio by weight of solution remain
action of steam for a period of at least about 15 ing in the material to the material is about 2:1,
one-half hour in a steam chamber, thereafter
and exposing the said material while wet with
washing the material with water, impregnating
the second said solution to the action of steam
it with an acid aqueous solution containing so
dium chlorite in amount e?ective to eliminate a
substantial part of the non-cellulose impurities
remaining in the material, discharging solution
therefrom until the ratio by weight of solution
remaining in the material to the material is about
2:1, and exposing the said material while wet
with the second said solution to'the action of
steam for a period of at least about one-half hour
in a steam chamber.
2. A process for purifying crude cellulosic veg
etable materials which comprises impregnating
for a period of at least about one-half hour in a
steam chamber.
4. A process for purifying crude cellulosic veg
etable materials which comprises impregnating
said material with an alkaline aqueous solution
containing about 4 to ‘12% of caustic soda, dis
charging solution from the material until the
ratio by weight of solution remaining in the ma
terial to the material is about 2:1, exposing the
material while wet with the'solution to the ac
tion of steam for a period of at least about one
half hour in a steam chamber, thereafter wash
said material with an alkaline aqueous solution 30 ing the material with water, subjecting the
washed cellulosic material to the action of an
containing about 4 to 12% of caustic soda and a
detergent, discharging solution from the mate
rial until the ratio by weight of solution remain
ing in the material to the material is about 2:1,
exposing the said material while wet with the I
solution to the action of steam for a period of at
least about one-half hour in a steam chamber,
thereafter washing the material with water, im
pregnating it with an acid aqueous solution con
taining sodium chlorite in amount effective to ‘
eliminate a substantial part of the non-cellulose
impurities remaining in the material, discharging
aqueous solution containing sodium hypochlorite
in amount effective to eliminate a substantial
part of the non-cellulose impurities remaining
in the material, regulating the contact of the
cellulosic material with the hypochlorite solution
to control the viscosity characteristic of the ?nal
cellulosic product, thereafter washing the mate
rial with water, impregnating it with an acid
aqueous solution of sodium chlorite, discharging
solution therefrom until the ratio by weight of
solution remaining in the material to the mate
rial is about 221, and exposing the said material
solution therefrom until the ratio by weight of
while wet with the last said solution to the ac
solution remaining in the material to the mate
rial is about 2: 1, and exposing the said material 45 tion of steam for a period of at least about one
half hour in a steam chamber.
while wet with the second said solution to the ac
GEORGE P. VINCENT.
tion of steam for a period of at least about one
ARCHIE‘ L. DUBEAU.
half hour in a steam chamber.
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