Improvements in the Process and Machinery for Producing a Thread or Filament similar to Silk.
Year: 1892

page_text: Date of Application, 10th Dec., 1892
Complete Specification Left, 11th Sept., 1893-Accepted, 4th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Process and Machinery for Producing a Thread
or Filament similar to Silk.
I, Dr. FRIEDRICH LEHNER, Chemist of Neptunstrasse 30, Zurich, Hottingen
in the Republic of Switzerland, do hereby declare the nature of this invention to
be as follows:-
It is known that a thread having according to its method of preparation more or
less resemblence to natural silk may be produced by carrying through a solidifying
fluid such as terpentine oil water or petroleum a fine stream or filament composed of
nitrocellulose dissolved in aethylic alcohol, wood spirit, acetic acid with addition if
desired of dissolved silk resin, salts or organic compounds. Such thread is either
drawn fine in the air and several threads are combined together and wound in
bobbins, or the necessary thickness is given to it while in the solidifying fluid and it
is then simply wound without further manipulation.
The improved process which is carried on by help of the machine hereinafter
described differs from previous processes mainly in the following particulars;
1. The production of the thread is different. The material for production of
the thread must be thin flowing in order that a pressure of a few decimeters only
will be sufficient to bring the material out of the outlets into the fluid.
2. The formation of the thread is different, the same being drawn fine while in
the solidifying fluid.
3. There are no special mechanical drawing devices used for this purpose, to draw
the threads in the fluid.
4. There is an always constant and equal drawing off of all threads by a special
roller drawer, whereas formerly where the threads were simply wound they were
drawn off unequally.
5. The present machinery operates the union of several threads or filaments by
the simple and known mechanical operation of twisting them together as in spinning
by which a dense smooth thread is produced which when it is afterwards unwound
from the bobbins will not stick to other threads.
This improvement also simplifies the process and apparatus.
6. The threads are dried and the volatilized solvents are also regained by passing
the thread during a part of its course through a heated chamber as far as possible
air-tight, whence the vaporised solvents are led or drawn off for condensation in the
usual way.
7. The process also comprises a denitrification of the thread that is to say a
partial or total reduction of the nitrocellulose therein to cellulose by passing the
thread through a chemical solution, such as aqueous solution of sulfate of potash
or by which a part of the nitro groups are removed. The thread is thus made less
inflammable.
8. The invention further comprises an improvement relating to the solution of or
from which the thread or filament is composed. When nitrocellulose is dissolved
as aforesaid in wood spirit, aethylic alcohol and acetic acid to form a five per cent.
solution, a slight overpressure causing it to flow out of a narrow opening into water
petroleum or the like will produce a thread.
When however the nitrocellulose is raised to 10% the solution is so thick that
the production of a thread requires a pressure of several atmospheres. This is a
serious drawback in practice.
The improvement consists in warming this thick solution with sulphuric acid
of 60° Réaumur or compact precipitate separates which is probably a cellulose
sulphate (such a compound has been shown to be separated in the cold by action

page_text: of concentrated sulphuric acid or nitrocellulose). This precipitate re-dissolves on
shaking and the solution is much clearer and easier flowing than before. Solutions
containing up to 25% or even more of nitrocellulose can be in this way rendered
suitable for the production of threads. under very slight pressure. The amount of
sulphuric acid necessary is according to the weight of nitrocellulose employed being
about 5 to 10% thereof.
Thus for producing a 20% solution of nitrocellulose 20 parts of the latter,
1 to 2 parts of sulphuric acid and 78 parts of the wood spirit or other solvent are
employed. Hydrochloric, nitric or sulphurous acid produces a similar result but the
amount of acid necessary is considerably greater.
In the machine the reservoir of solution of nitrocellulose may be fixed at different
heights, it is provided with a glass gauge glass and is connected by a rubber pipe
with a cross tube from which project a number of branches to which a number of
small tubes-shaped somewhat like a letter S are connected by rubber joints.
These S pipes dip into a vessel which may be of glass, (or the sides of which at
least should be of glass) in which is the solidifying fluid such as water, petroleum etc.
Small glass partitions separate the pipes but without interfering with the circulation
of the liquid in the vessel. Inflow and outflow pipes are provided for supply of said
liquid. The filaments which form from the material as it issues from the ends of
the S pipes are gathered in groups, say seven of them in a group and each group
is passed through the axis of a hollow rotary tube the entrance of which is
preferably slightly, towards one side. Any other thread such as a cotton thread
which is to be spun with the threads is here introduced. The revolution of the tube
gives a certain cohesion to the filaments. Hence the threads pass through small
orifices into a closed chamber with a double or jacketted bottom heated by hot
water or steam. The filaments pass back and forth over pulleys in this chamber
and there lose the remainder of the solvent which is drawn off for condensation.
The threads leaving this chamber through similar small holes pass over rollers
dipping in any denitrifying chemicals as aforesaid and thence pass between rollers
revolving at the desired speed these rollers being intended to draw the threads at
the desired rate. From there the threads pass to suitable spinning devices such as
on a usual bobbin and fly-frame for twisting and winding the thread in cops.
Dated this 10th day of December 1892.
R. HADDAN,
Agent for Applicant.
COMPLETE SPECIFICATION.
Improvements in the Process and Machinery for Producing a Thread
or Filament similar to Silk.
I, Dr. FRIEDRICH LEHNER, Chemist, of Neptunstrasse 30, Zurich, Hottingen,
in the Republic of Switzerland, 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:-
This invention relates to improvements on the process and machinery for
producing a thread or filament similar to silk described in the Specification of a
former Patent granted to ne No. 11831 of 1891. In this process a solution mainly
composed of nitro-cellulose is caused to flow from small orifices into a liquid such
as water, turpentine, oil, petroleum or other hydro-carbon, and is drawn out into a
fine thread from each orifice before it leaves the solidifying liquid.
When nitro-cellulose is dissolved in wood spirit, ethylic alcohol and acetic acid.
to form a solution containing say about 5 per cent. of solid material such a solution
will with slight over-pressure flow out of a narrow opening into water, petroleum or
the like, and will produce a thread.
When however in order to obtain stronger threads the nitro-cellulose in solution
is raised to 10% the solution is so thick that the production of a thread requires a

page_text: pressure of several atmospheres to make it now througn nne orinces. IDIS IS &
serious drawback in practice.
According to this invention I manufacture the threads or filaments from a strong
nitro-cellulose solution which has previously been warmed with sulphuric or with
hydrochloric or nitric or sulphurous acid.
As solvents, wood spirit, ethylic alcohol, acetic acid, acetic ether, are usually
employed. These solvents however produce a solution which is exceedingly thick
and tough. A solution of about 10%, for instance, can only be filtered by very
considerable pressure, several atmospheres, and such thick solutions are for many
reasons most difficult to treat or handle economically for technical purposes on a
large scale.
When however the thick solution is warmed with sulphuric acid of about
66° Beaumé, a compact precipitate separates which redissolves on shaking, and the
solution is then much clearer and easier flowing than before. Solutions containing
up to 25% or even more of nitro-cellulose can be in this way rendered suitable for
the production of threads under very slight pressure. The amount of sulphuric
acid necessary is according to the weight of nitro cellulose employed, being about
5 to 10% thereof.
Thus for producing a 20% solution of nitro-cellulose 20 parts of the latter,
1 to 2 parts of sulphuric acid, and 78 parts of the wood spirit or ether or other
solvent are employed. Hydrochloric or nitric or sulphurous acid produces a similar
result, but the amount of acid necessary is considerably greater.
The machine for manufacturing the threads I now construct as follows. The
reservoir of solution of nitro-cellulose may be fixed at any desired height, it is
provided with a gauge glass, and is connected by a rubber pipe with a cross tube
from which project a number of branches to which a number of small tubes shaped
somewhat like a letter S are connected by rubber joints. These S pipes dip into a
vessel which may be of glass (or the sides of which at least should be of glass) in
which is the solidifying fluid, such as water, petroleum &c. The upper bend of
each pipe hooks over the top edge of the vessel whilst the end of the lower bend.
is drawn out so that it terminates in a small orifice. Small glass partitions separate
the pipes but without interfering with the circulation of the liquid in the vessel.
Inflow and outflow pipes are provided for supply of said liquid.
The filaments which form from the material as it issues from the ends of the
S pipes are gathered in groups, say-seven of them in a group, each such group
may be passed through the axis of a hollow rotary tube the entrance of which is
preferably slightly to one side. Any other thread such as a cotton thread which
is to be spun with the threads is here introduced. The revolution of the tubes
gives a certain cohesion to the filaments. Hence the threads pass through small
orifices into a closed chamber with a double or jacketted bottom heated by hot
water or steam. The filaments there lose the remainder of the solvent, which is
drawn off from the chamber for condensation.
The threads leaving this chamber through similar small holes pass under or over
cylindrical rollers which dip into any denitrifying chemicals and thence pass
between cylindrical rollers revolving at the desired speed, these rollers being
intended to draw the threads at the desired rate. The rollers being cylindrical
and driven at one uniform rate the filaments are produced in a perfectly even and
uniform manner. From there the threads pass to suitable spinning devices such as
on a usual bobbin and fly frame for twisting and winding the thread in cops.
In the accompanying drawings
Figure 1 shows an elevation and Figure 2 a plan of the machine.
The reservoir A which contains the solution from which the threads or filaments
are to be formed is provided with a gauge glass w and can be adjusted higher or
lower on the support b. The reservoir is also connected by a rubber tube 7 to
a pipe C. This pipe C has a number of outlets c, these are connected by a number
of rubber tubes to a corresponding number of glass tubes e, these glass tubes are
$ shaped. The upper bend hooks over one side of a basin G the lower bend iş

page_text: close to the bottom of this basin and the bent up end is made to terminate in a
narrow aperture.
From this narrow aperture of the glass tubes e the solution enters the solidifying
liquid contained in the basin G and are drawn out or extended whilst they pass
through the liquid. Any suitable solidifying liquid may be used as for example
turpentine or water or petroleum.
The glass tubes are kept separate in the basin G by loosely inserted glass
partitions g which do not impede the liquid from circulating. These prevent the
filaments becoming entangled should any filament break. The glass tubes e may fit
into slots or grooves which can be provided either at the sides or at the bottom of
the basin G in order to prevent their shifting. Such an arrangement admits of any
single one of the glass Sehaped tubes being taken out without interrupting the
work of the others. The basin G is made of glass with inlet and outlet for the
solidifying liquid.
Any required number of the filaments i are, as they form, conducted jointly to
guides. at E; seven filaments are shown in the drawing. At E, if desired, a thread
or filament p of any other material, natural or artificial, may be added, for instance,
a cotton thread, real silk thread or others, this additional thread is contained on
the spool P and is guided from the spool below the tube Cover the basin G to
guide E.
The united filaments i and the natural filaments or threads p are now steadily
drawn off by the drawing off mechanism T from the basin G and the spool P. For
drawing off and carrying forward the filament I find it best to employ a roller T¹
with a break roller T resting on it, the two rollers being actuated as in ordinary
twisting machines, the two rollers carry forward the filaments between them, or
I take a single larger roller and let the filaments run once round this roller when
by friction they cling sufficiently to the roller so as to be drawn off evenly and
steadily from the basin G.
When the various filaments have been gathered at E, they show very little
adhesion to each other, in order therefore to better guide them they may be
subjected to a temporary false twist. This is effected at O where the filaments are
guided through the narrow tube placed slightly sideways, this tube rapidly revolves
thereby giving the filaments a false twist, the tube is arrranged as hollow axle of
the disc which serves for setting it in rotation.
The filaments having a temporary false twist are then guided through a narrow
aperture m to the drying chamber Q, which is closed as air tight as possible and
is provided with a lid D.
This chamber Q has a false or double bottom R and in the space between the
two bottoms hot water or steam is circulated which enters the first drying chamber
by the tube a, leaving it again at z in Figure 2, then entering and leaving the
second and third drying chamber and so forth.
The filaments traverse the upper part of the drying chambers, remaining in the
chamber for a little time, they are for instance drawn over the guides f¹ and f² in
order to keep them for a longer time in the drying chamber and to extract from
them by evaporation in this way as much as possible any solvents which may remain
in them. Any wood-spirit or ethylic alcohol remaining are evaporated and the
vapours are carried off, by the outlet tube l, and are afterwards condensed and
recovered in a suitable way.
When leaving the drying chamber Q the filaments reach the denitrating
appliance J. This consists of a roller partly immersed in a denitrating liquid, the
latter consists of sulphide of ammonia or other sulphur alkalis, etc., and as already
stated, serves to deprive the filaments of a further portion of the nitro-groups which
may remain in them and it also neutralises any free acid which may adhere to the
filaments, or a liquid may be used for impregnating the filaments.
By the drawing forward mechanism T the filaments are then drawn over the
guides S to the spinning apparatus a which may be of any known construction
suitable for the purpose.

page_text: The filaments are led through the flyers y to the spools and are wound on the spools
with any desired twist. By this means I produce an even and excellent twisted
filament or thread and do away with the winding on winsels, unwinding therefrom
of single filaments and subsequent uniting before they can be spun as has been the
case previously.
Of the working of the various parts of the machine, the following must be
mentioned:
The shaft W gives the motive power and is the actuating mechanism of the
twister O and the drawing off and carrying rollers and also of the spinning
apparatus proper ¹, as well as of the rising and falling frame h which carries the
spools. The pulley U on shaft W by a rope belt rotates one of the filament false-
twisting tubes O, these tubes O are then belted one to the other.
The drawing-off and carrying mechanism is also actuated from the shaft W.
The raising and lowering of the frame and the spinning apparatus is caused by
the eccentric disc a (as shown on the drawing).
By the raising and lowering of the frame the spools are evenly raised and
lowered so that the winding of the twisted filament on the spools is done as evenly
as possible.
During the motion of the spindles they are rotated from the shaft w³, which
receives its notion from the shaft W. Small weights N can be used as a break on
the spools.
As soon as these spools are wound full they can be exchanged without interrupting
the machine. The filaments which are feeding forward are quickly transferred to
a fresh spool which is placed on the frame while the machine is kept running.
The driving or guiding arrangement can be varied and for the purpose of twisting
the filaments any other spinning machine can be combined with the other parts of
the machinery, or the filaments as they are drawn from one or more drawing-out
basins can be guided direct to any convenient spinning machine without the inter-
mediary apparatus.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The manufacture of threads or filaments from nitro-cellulose solutions previously
treated with sulphuric acid or other suitable acid which will effect the same result
substantially as described.
2. The arrangement of the filament forming tubes each dipping down into the
bath containing the solidifying liquid and bent upwards at its lower end and
contracted to a small orifice at its extremity substantially as described.
3. Dividing the bath which contains the solidifying liquid into compartments
by partitions which allow of a free circulation of the liquid but separate the
filament forming tubes one from another.
4. The arrangement of the heated drying chamber through which the filaments
are made to travel as they pass from the bath to the drawing forward mechanism
substantially as described.
5. The arrangement of mechanism for treating the filaments with denitrating
liquid as they pass to the drawing forward mechanism substantially as described.
6. Drawing the filaments forward from the filament forming orifices by a con-
tinuously rotating cylindrical roller or rollers substantially as described.
7. The construction of machinery for producing threads or filaments similar to
silk substantially as hereinbefore described and illustrated in the drawing annexed.
Dated this 9th day of September 1893.
CARPMAEL & Co.,
Agents for the Applicant.