Improvements relating to the Solution of Cellulose.
Year: 1899

page_text: Date of Application, 27th Mar., 1899
Complete Specification Left, 21st Dec., 1899-Accepted, 27th Jan., 1900
PROVISIONAL SPECIFICATION.
Improvements relating to the Solution of Cellulose.
We, Dr. MAX FREMERY, Chemist, and JOHANN CRBAN, Engineer, both of Dorf-
strasse, Oberbruch, Reg. Bez. Aachen, in the German Empire, do hereby declare
the nature of this invention to be as follows:
-
The process forming the subject of the present invention relates to the pre-
liminary treatment of cellulose to facilitate its direct solution in suitable sol-
vents, such as an ammoniacal solution of cupric oxide, zine chloride and the like.
In the known solvents, the cellulose dissolves very slowly and often in small
quantities. The disadvantages which thereby result to practical operations
involving the solution of cellulose, such as are performed in works for the manu-
facture of artificial silk and the like, are obvious.
Investigations were therefore undertaken, which led to the present invention,
with a view of obviating this disadvantage, by various methods. In the course
of these investigations, it was discovered that the cellulose can be made access-
ible to the action of direct solvents by a preliminary energetic treatment with
oxidising or reducing bleaching agents, or with chemical agents, such as sulphur-
ous acid salts, sulphurous acid, sulphuric acid, soda lye, and bisulphide of carbon,
whereby the cellulose can also be converted, as in the treatment with weak
mineral acids, into hydrocellulose, or, in the treatment with sulphuric acid of
suitable strength (parchmentising process), into amyloid.
This prepared cellulose dissolves in the known solvents, not only in a much
shorter time, but also to more than double the percentage heretofore possible.
This may be explained by means of an example, riz:-
If purified, unbleached or even slightly bleached cotton of commerce, for
example, the cotton wool used for surgical purposes and from which the grease
has been removed, be treated with an ammoniacal solution of cupric oxide, it is
not possible to bring more than 3 to 4 per cent. of this cellulose into solution;
moreover the solution requires a period of several days. If the same cotton be
subjected to a preliminary energetic bleaching with chlorine so as to leave it
during 12 to 18 hours in a bleaching bath of a strength corresponding to 15
grams of chloride of lime per litre, the cotton so treated dissolves, after pre-
liminary washing and drying, in the same ammoniacal solution of cupric oxide,
in a proportion of 10 per cent. and more, this being moreover effected in a period
of a few hours. If the bleaching take place more energetically, there is formed,
for example, on solution in an ammoniacal solution of cupric oxide, no longer a
sticky, viscous mass, but a thin liquid product which is not suitable for the fur-
ther technical treatment of cellulose solution in the manufacture of artificial
silk, etc. The cellulose recovered from the above mentioned about 10 per cent.
solution of cellulose shows all the reactions of pure cellulose and contains only
traces of oxycellulose. It is in no way different from cellulose which is separated
from a solution which is made by means of slightly bleached or unbleached cellu-
lose. The action of the bleaching agent depends upon the percentage of oxidising
or reducing agents which it contains, as well as on the duration of the action.
The procedure is varied somewhat according to the various kinds of cellulose.
Whilst, for example, a relatively weak bleach will produce the desired effect
with cotton, ramie fibre requires a stronger treatment; the bleach must be of

page_text: a still higher percentage for treating wood cellulose in order to obtain the desired
effect. Cellulose which has been subjected to the so-called parchmentising pro-
cess by treating it with strong sulphuric acid, and which is often termed amy-
loid, dissolves in ammoniacal solution of cupric oxide in a substantially higher
percentage than cellulose not prepared in this manner. Thus parchment paper
made, for example, by means of sulphuric acid or chloride of zine, dissolves up
to 10 per cent. and over that. An amyloid solution of this kind can be manufac-
tured into artificial silk quite as well as a cellulose solution. Further it has
resulted that so-called hydrocellulose dissolves to quite as high a percentage as
the cellulose prepared by energetic bleaching. Hydrocellulose of this kind can
be obtained, amongst other ways, by treating pure cellulose which is free from
grease, for example, the cotton wool used for surgical purposes, with a 3 per cent.
solution of sulphuric acid, the cotton wool is then pressed out and allowed to dry
in the air without washing, then dried completely at 40 degrees, washed and
again dried. There is only mentioned here one of a number of methods which
have been shown to be suitable for converting cellulose into hydrocellulose. The
employment of parchmentised cellulose is the more advantageous the more
complete the parchmentisation is effected, that is to say, the more thoroughly
the original organised cellulose is converted into a transparent, horny, amor-
phous mass. The sulphite cellulose and soda cellulose produced by treatment
with sulphite lye or soda lye likewise dissolve in a considerably higher percent-
age than natural cellulose."
The proposed treatment forming the subject of the present invention, for
example, the described strong bleach, parchmentising, appears in some degree
to effect a kind of opening of the cellulose, in many cases depending upon destroy-
ing the cuticle surrounding the natural cellulose, so that the cellulose then enters
directly into reaction with the particular solvent in use. This preliminary treat-
ment is preferably to be conducted in such a manner that the foreign substances
accompanying the cellulose are completely destroyed without causing a deep-
seated decomposition of the cellulose molecule.
In the experiments made in connection with the present invention, it was also
established that chemically pure cellulose as this is separated from its solution,
for example, in ammoniacal solution of cupric oxide, dissolves again to quite
as high a percentage as the cellulose prepared in the manner described.
By employing the above process, which renders it possible to dissolve more
than double the percentage of cellulose than heretofore, processes which are
based on the manufacture of cellulose solution, as for example, the manufacture
of artificial silk, are rendered less expensive so that their economy is beyond
doubt.
improvements relating to the Solution of Cellulose.
We, Dr. MAX FREMERY, Chemist, and JOHANN URBAN, Engineer, both of Dorf-
strasse, Oberbruch, Reg. Bez. Aachen, in the German Empire. do hereby declare
the nature of this invention and in what manner the same is to he performed
to be particularly described and ascertained in and by the following statement:-
The
process forming the subject of the present invention relates to the pre-

page_text: liminary treatment of cellulose to facilitate its direct solution in suitable sol-
vents, such as an ammoniacal solution of cupric oxide, zinc chloride and the like.
In the known solvents the cellulose which has not undergone the preliminary
treatment of the present invention dissolves only to such extent that e.g. by means
of an ammoniacal solution of cupric oxide (cuprammonia), a cellulose solution
could be produced which contained only up to 44% cellulose
Investigations were therefore undertaken by us in the course of which it was
discovered that the cellulose (as such or in the form of hydrate of cellulose or
hydrocellulose) can be made more accessible to the action of direct solvents by
a preliminary energetic treatment with oxidizing or reducing agents, e.g., bleach-
ing agents, or with chemical agents, such as sulphurous acid salts or sulphurous
acid the cellulose can also be converted, as in the treatment with weak mineral
acids, into hydrocellulose, or, in the treatment with sulphuric acid of suitable
strength (parchmentising process), into amyloid.
This prepared cellulose dissolves in the known solvents, not only in a much
shorter time, but also to more than double the percentage heretofore possible.
This may be so explained by means of an example riz:—
If purified, unbleached or even slightly bleached cotton of commerce, for
example, the cotton wool used for surgical purposes and from which the grease
has been removed, he treated with an ammoniacal solution of cupric oxide, it is
not possible to bring more than 3 or 4 per cent. of this cellulose into solution :
moreover, the solution requires a period of several days. If the same cotton be
subjected to a preliminary energetic bleaching with chlorine so as to leave it dur-
ing 12 to 18 hours in a bleaching bath of a strength corresponding to 15 grams
of chloride of lime per litre, the cotton so treated dissolves after preliminary
washing and drying, in the same ammoniacal solution of cupric oxide, in a pro-
portion of 10 per cent, and more, this being moreover effected in a period of a
few hours. If the bleaching take place more energetically there is formed, for
example, on solution in an ammoniacal solution of cupric oxide, no longer a
sticky, viscous mass, but a thin liquid product which is not suitable for the fur-
ther technical treatment of cellulose solution in the manufacture of artificial silk.
The action of the bleaching agent depends upon the percentage of oxidizing
or reducing agents which it contains as well as on the duration of the action.
The procedure is varied somewhat according to the various kinds of cellulose.
Whilst, for example, a relatively weak bleach will produce the desired effect
with cotton, ramie fibre requires a stronger treatment, the bleach must be of a
still higher percentage for treating wood cellulose in order to obtain the desired
effect. Cellulose which has been subjected to the so-called parchmentising pro-
cess by treating it with strong sulphuric acid of 59 Bé. and which is often termed
amyloid, dissolves in ammoniacal solution of cupric oxide in a substantially
higher percentage than cellulose not prepared in this manner.
The proposed treatment forming the subject of the present invention, for
example, the described strong bleach or parchmentising, appears in some degree
to effect a kind of opening of the cellulose.
This preliminary treatment is preferably to be conducted in such a manner
that no deep-seated decomposition of the cellulose molecule takes place.
By employing the above process, which renders it possible to dissolve more than
double the percentage of cellulose than heretofore, processes which are based on
the manufacture of cellulose solution, as for example, the manufacture of arti-
ficial silk, are rendered less expensive so that their economy is beyond doubt.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
A process for increasing the solubility of cellulose or hydrates of cellulose or
of hydrocellulose in direct solvents of cellulose, such as, e.g., in cuprammonia

page_text: solution or in a solution of zinc-chloride, characterized by subjecting the said
materials, previously to the dissolving of the same to an energetic treatment
with oxidizing or reducing agents, e.g., with bleaching agents or with parch-
mentising agents such as sulphuric acid of, e.g., 59 Bé., substantially as, and
for the purpose, set forth.
5
Tinded that
1000
D. YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.