Improvements in the Process of and in Means and Apparatus for Ungreasing Hides, Skins, Leather, and other materials.
Year: 1893

page_text: Date of Application, 16th Mar., 1893
Complete Specification Left, 16th May, 1893—Accepted, 24th June, 1893
PROVISIONAL SPECIFICATION.
Improvements in the Process of and in Means and Apparatus for
Ungreasing Hides, Skins, Leather, and other materials.
We, GEORG POPP, Ph.D., and JOHANN HEINRICH BECKER Ph.D., both of
153 Fenchurch Street, in the City of London, Chemists, do hereby declare the
nature of this invention to be as follows:-
The ungreasing of skins, leather, etc., has hitherto been performed by treating
the goods with benzene, ether, or other solvent, and working them in vats, but the
results are unsatisfactory, both as regards uniformity and otherwise, the solvent
remaining in the goods treated generally containing fatty matter which, after
removing the goods from the vats and volatilizing the solvent, shews itself in the
goods (more especially after the dyeing) in the form of ugly spots. Upon the
completion of the ungreasing operation the solvent containing the fatty matter is
passed into stills in order to recover the solvent which is used over and over again,
but in consequence of the distance which separates the stills from the extractors
which is necessary on account of the inflammability of the materials employed, a
great loss of the solvents has occurred.
All processes hitherto employed for ungreasing skins, etc., possess, besides the
above, the following drawbacks-Being intermittent they necessitate the employ-
ment of complicated apparatus, the consumption of large quantities of solvent, and
a great amount of labor, while the solvents are but imperfectly utilized and their
use involves great risk of fire and danger to human life so that very onerous
insurance premiums have to be paid. As above stated the use of benzene and the
like exerts a very prejudicial effect on the goods the solvents moreover separating
out albuminous bodies, thus materially enfeebling the skins and rendering them
very liable to tear during the subsequent operations.
Our invention has for its object to overcome the whole of these objections, and
it consists essentially in-
(1) A continuous process carried out in closed vessels by means of which not
only is the waste reduced to a minimum but the rational utilization of the solvents
ensured, the application of mechanical means serving to cheapen the entire
operation;
(2) The employment of a solvent which has no action upon the goods and is
neither highly inflammable nor dangerous to life.
In carrying out our invention the skins or other goods are placed in cylinders or
containers closed at top and provided with a perforated diaphragm or false bottom.
Supposing the process to have been started, the solvent is then run out of one
container into another in such manner that the goods containing most fatty matter
are treated with the solvent most heavily laden therewith, the goods in the most
advanced stage of ungreasing being treated with fresh solvent. With this operation
in closed containers is combined the regular supply and discharge of the solvent.
After having passed automatically through the series of containers, the solvent
finally passes into a distilling apparatus in which it is distilled from the dissolved
matters and condensed into a liquid again in a cooling coil, so that the supply of the
solvent to the containers and its discharge therefrom to the still is dependent on
the quantity of distilled solvent. As this continuous and repeated operation is
performed in a completely closed apparatus, any loss of solvent which may occur
through leakage is infinitesimal. On the completion of an operation the partially
exhausted solvent in one of the containers is transferred to another, either by
mechanical means such as a pump in connection with a pipe communicating with
the whole of the containers or by a steam or water jet or by letting in water or

page_text: other liquids which forces the solvent out but does not mix with it. In the latter
case it is unnecessary to employ a pump. A further advantage to be obtained by
the employment of a head of water being the recondensation of any portions of the
solvent evaporated. In order that no interruption of the process may be
occasioned, a receiver for the fresh solvent is placed between the cooling coil and
the containers, and a collecting box for the exhausted solvent to be distilled is
interposed between a discharge pipe common to all the containers and the still.
The still is provided with a safety-valve, a manhole, a cock for drawing-off the
fatty residue and a charging funnel.
For forcing the solvent as above described from one container to another a water
tank is connected at a convenient point to the pipe which conveys the fresh solvent
from the receiver to the containers. The solvent is transferred from one container
to another through a system of pipes controlled by suitable valves, etc., by which
the solution may be conveyed from the space below the perforated diaphragm of
one container to the upper portion of another container, this method being used for
solvents which become heavier by taking up fat, etc., whereas for those which by
the same process become lighter the direction is reversed. These pipes may of
course be replaced by suitable intermediate parts and partition walls or by
disposing the containers close above one another. The containers are closed at the
top by covers fitting tightly, say, by means of a screw-joint or a liquid seal to
prevent evaporation of the solvent and are provided with counterweights to enable
them to be readily removed or raised. To equalize any inequalities of pressure in
the containers, a pipe connects them all with the pump. The containers are
furnished with draw-off cocks for cleaning purposes, and with gauges, with which
the stiil is also provided.
In order to obviate the necessity of first hanging the goods on frames to dry, as
hitherto, and to recover as thoroughly as possible the solvent absorbed by the goods
where it is not practicable to syringe them with water, a slow current of air is
driven or drawn through the containers by means of an exhauster, blower, or water-
spray apparatus, the outflowing gases being compressed by a cooler or directly by
cold water whereby they are condensed and then separated from the water by means
of suitable vessels.
It is
It is evident that some such continuous process as that above described for the
proper utilization of a cold solvent is greatly needed, as the skins and leather must
not be heated, or at any rate but very slightly, otherwise they will shrink.
true that extracting apparatus for ungreasing leather parings is now employed but
always in conjunction with hot solvents which is detrimental to the leather. So
long as no process existed for the proper utilization of the solvent and the reduction
of the dangers and losses incidental to its use, there was no inducement to employ
solvents recoverable by distillation other than benzene and ether because they all
possess the same drawbacks besides being dearer and more dangerous to evaporate.
With the apparatus above described, however, in which the solvents are used to the
utmost extent, it is profitable under certain conditions to employ other solvents,
such as chloroform, carbon bisulphide etc. In making experiments in this latter
direction we have operated with carbon tetrachloride on dyed and undyed leather,
skins, cloth, textile stuffs, etc., for ungreasing same and we have found it to be
particularly well adapted for the purpose. Carbon tetrachloride is a substance of
uniform character which may be completely distilled (B.P. 76° C.) by indirect
steam heating. It is less volatilizable than ether and benzene and possesses the
quality of dissolving fatty matter in an extremely high degree and without being
heated it has no action on skins and leather, etc. It has the further advantage of
being uninflanimable and not capable of overcoming the workpeople, in the manner
of chloroform for instance. These combined advantages render carbon tetra-
chloride specially applicable for use in this industry, notwithstanding that it is
comparatively expensive, having only recently become a commercial article, which
its increased sale will reduce, although the above described apparatus in conjunction
with a continuous process, such as we have described, enables a costly solvent to

page_text: be profitably employed. In short, the treatment of hides, etc., with carbon tetra-
chloride yields such superior results that the cost, which is not excessive, is very
much more than counterbalanced by the advantages obtained.
Dated this 16th day of March 1893.
U. r rr,
J. H. BECKER,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION.
Improvements in the Process of and in Means and Apparatus for
Ungreasing Hides, Skins, Leather, and other materials.
We, GEORG POPP Ph.D. and JOHANN HEINRICH BECKER Ph.D., both of
153, Fenchurch Street, in the City of London, Chemists, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
-
The ungreasing of skins, leather, bones etc., has hitherto been performed by
treating the goods with benzene, ether, or other solvent, and working them in vats,
but the results are unsatisfactory, both as regards uniformity and otherwise, the
solvent remaining in the goods treated generally containing fatty matter which,
after removing the goods from the vats and volatilizing the solvent, shews itself in
the goods (more especially after the dyeing) in the form of ugly spots. Upon the
completion of the ungreasing operation the solvent containing the fatty matter is
passed into stills, in order to recover the solvent which is used over and over
again, but in consequence of the distance which separates the stills from the
extractors, which is necessary on account of the inflammability of the materials
employed, a great loss of the solvents has occurred.
All processes hitherto employed for ungreasing skins, etc., possess, besides the
above, the following drawbacks. Being intermittent, they necessitate the employ-
ment of complicated apparatus, the consumption of large quantities of solvent, and
a great amount of labor, while the solvents are but imperfectly utilized and their
use involves great risk of fire and danger to human life, so that very onerous
insurance premiums have to be paid. As above stated, the use of beuzene and the
like exerts a very prejudicial effect on the goods, the solvents, moreover, separating
out albuminous bodies, thus materially enfeebling the skins and rendering them very
liable to tear during the subsequent operations.
Our invention has for its object to overcome the whole of these objections, and
it consists essentially in :-
(1) A continuous process carried out in closed vessels by means of which not
only is the waste reduced to a minimum but the rational utilization of the solvents
ensured, the application of mechanical means serving to cheapen the entire
operation;
(2) The employment of a solvent which has no action upon the goods and is
neither highly inflammable nor dangerous to life.
The invention will be described with reference to the accompanying drawing,
forming part of this Specification, which shews the apparatus employed, in part
sectional elevation.
In carrying out our invention, the skins or other goods are placed in cylinders or
containers a closed at top and provided with a perforated diaphragm or false
bottom b. Supposing the process to have been started, the solvent is then run out
of one of these containers a into another, in such manner that the goods containing
the largest amount of fatty matter are treated with the solvent most heavily
laden therewith, the goods in the most advanced stage of ungreasing being treated
with fresh solvent. With this operation in closed containers is combined the
regular supply and discharge of the solvent. After having passed automatically

page_text: through the series of containers, the solvent finally passes into a distilling
apparatus d in which it is distilled from the dissolved matters and condensed
into a liquid again in a cooling coil k, so that the supply of the solvent to the
containers and its discharge therefrom to the still is dependent on the quantity of
distilled solvent. As this continuous and repeated operation is performed in a
completely closed apparatus, any loss of solvent which may occur through leakage
is infinitesimal. On the completion of an operation the partially exhausted solvent
in one of the containers is transferred to another, either by mechanical means such
as a pump p in connection with a pipe e communicating with the whole of the
containers or by a steam or water-jet, or by letting in water or other liquids,
which forces the solvent out but does not mix with it. In the latter case it is
unnecessary to employ a pump, a further advantage to be obtained by the employ-
ment of a head of water being the re-condensation of any portions of the solvent
evaporated. In order that no interruption of the process may be occasioned a
receiver for the fresh solvent is placed between the cooling coil K and the
containers a and a collecting box for the exhausted solvent to be distilled is
interposed between a discharge pipe u common to all the containers a and the still d.
The still is provided with a safety-valve S, a manhole m, a cock x for drawing off
the fatty residue, and a charging funnel f.
For forcing the solvent as above described from one container to another, a
water-tank w is connected at a convenient point by a pipe w¹ to the pipe o which
conveys the fresh solvent from the receiver / to the containers. The solvent is
transferred from one container to another through the system of pipes c controlled
by suitable valves, etc., by which the solution may be conveyed from the space
below the perforated diaphragm of one container to the upper portion of another
container, this method being used for solvents which become heavier by taking up
fat, etc., whereas for those which by the same process become lighter the direction
is reversed. These pipes may of course be replaced by suitable intermediate parts
and partition walls or by disposing the containers close above one another.
containers are closed at the top by covers a fitting tightly, say, by means of a screw-
joint or a liquid seal to prevent evaporation of the solvent and are provided with
counterweights to enable them to be readily removed or raised. To equalize any
inequalities of pressure in the containers a pipe e connects them all with the pump.
Each container is furnished with a draw-off cock for cleaning purposes, and with
a gauge i with which the still is also provided.
The
In order to obviate the necessity of first hanging the goods on frames to dry, as
hitherto, and to recover as thoroughly as possible the solvent absorbed by the
goods where it is not practicable to syringe them with water, a slow current of air
is driven or drawn through the containers by means of an exhauster, blower, or
water-spray apparatus Z the outflowing gases being compressed by a cooler, or
directly by cold water, whereby they are condensed and then separated from the
water by means of suitable vessels.
It is
So
It is evident that some such continuous process as that above described for the
proper utilization of a cold solvent is greatly needed, as the skins and leather must
not be heated, or at any rate but very slightly, otherwise they will shrink.
true that extracting apparatus for ungreasing leather parings is now employed but
always in conjunction with hot solvents which is detrimental to the leather.
long as no process existed for the proper utilization of the solvent and the reduction
of the dangers and losses incidental to its use, there was no inducement to employ
solvents recoverable by distillation other than benzene and ether, because they all
possess the same drawbacks besides being dearer and more dangerous to evaporate.
With the apparatus above described, however, in which the solvents are used to the
utmost extent, it is profitable, under certain conditions, to employ other solvents,
such as chloroform, carbon bi-sulphide, etc. In making experiments in this latter
direction we have operated with carbon tetrachloride on dyed and undyed leather,
skins, cloth, textile stuffs, etc., for ungreasing same and we have found it to be
particularly well adapted for the purpose, Carbon tetrachloride is a substance of

page_text: uniform character which may be completely distilled (B.P. 76° C.) by indirect
steam heating. It is less volatilizable than ether and benzene and possesses the
quality of dissolving fatty matter in an extremely high degree and without being
heated it has no action on skins and leather, etc. It has the further advantage of
being uninflammable and not capable of overpowering the workpeople, in the
manner of chloroform, for instance. These combined advantages render carbon
tetrachloride especially applicable for use in this industry, notwithstanding that it is
comparatively expensive, having only recently become a commercial article, but its
increased sale will reduce the cost although the above described apparatus in
conjunction with a continuous process, such as we have described, permit a costly
solvent to be profitably employed. In short the treatment of hides, etc., with
carbon tetrachloride yields such superior results that the cost, which is not excessive,
is very much more than counterbalanced by the advantages obtained.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is-
1st. The ungreasing of hides, skins, bones, textile goods, and the like, by carbon
tetrachloride as a solvent for the fatty matter contained in the goods substantially
as specified.
2nd. The herein described continuous process of ungreasing hides, skins, leather,
textile goods, and the like, in the cold, which consists in passing the solvent through
the goods while in closed vessels in such manner that the solvent containing the
greatest amount of fatty matter is brought into contact with the goods most heavily
laden with fatty matter and the goods in the more advanced stage of ungreasing are
treated with fresh solvent, the solvent being distilled off, recondensed, and used
again, and the goods dried and the solvent retained by the goods recovered by
drawing or forcing air or other inert gases through the same apparatus and
condensing the solvent, substantially as specified.
3rd. The herein described continuous process of ungreasing hides, skins, leather,
textile goods, and the like, in the cold, which consists in passing carbon tetra-
chloride through the goods while in closed vessels, in such manner that the carbon
tetrachloride containing the greatest amount of fatty matter is brought into contact
with the goods containing the greatest amount of fatty matter, and the goods in the
more advanced stage of ungreasing treated with fresh carbon tetrachloride, the
carbon tetrachloride being distilled off, recondensed, and used again, and the goods
dried and the carbon tetrachloride retained by the goods recovered by drawing or
forcing air or other inert gases through the same apparatus, and condensing the
carbon tetrachloride, substantially as specified.
4th. The apparatus for carrying out the above claimed process continuously and
in the cold, consisting of the closed vessels a, and the distilling and condensing
apparatus d, k, and their adjuncts, the arrangement being such that the solvent is
separated from the fatty matter it has taken up from the goods and returned to the
vessels for re-use continuously.
5th. In the process and apparatus above claimed, transferring the solvent from
one container to another by a head of water or other liquid not capable of mixing
with the solvent, or by a pump or like mechanical contrivance.
6th. The herein described process of ungreasing hides, skins, leather, and other
goods, substantially as specified.
thi 14h daw f Mo 1002
Dated this 10th day of May 1902
G. POPP,
J. H. BECKER,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.