Improvements in the Manufacture and Production of a Material in Film, Sheet, or Web Form.
Year: 1898

page_text: Date of Application, 13th Jan., 1898
Complete Specification Left 10th Oct. 1898-Accented 3rd Dec.
1898
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture and Production of a Material in
Film, Sheet, or Web Form.
I, CHARLES HENRY STEARN, of 47, Victoria Street, in the City of Westminster,
Electrician, do hereby declare the nature of my invention to be as follows;-
ог
The object of my invention is to manufacture a material in film sheet
web form suitable for example for the production of thin sheets films or webs
for various purposes such as sheets for printing or writing purposes or films
for photographic or cinematographic pictures or for other purposes for which
film sheets or webs of material are required. According to my invention I
employ for this purpose a solution of cellulose made by treating cellulose with
strong alkali and then with carbon bisulphide and then dissolving the product
in water. A process for the production of such a preparation is described in the
Specification of Letters Patent No. 8700 of 1892. I precipitate the cellulose in
the form of films sheets or webs by passing the solution thereof into, or into and
through a precipitating solution such for instance as alcohol, brine chloride, or
sulphate of ammonium or other suitable precipitant in a thin layer of the required
width; which may be done for example by projecting it from a long narrow
slit, or by spreading it upon a surface upon which it is passed into, or into and
through the precipitating solution. The thickness of film sheet or web produced
may be regulated by the speed with which the cellulose solution is drawn or
carried through the precipitating solution. The sheets films or webs may after
precipitation be passed through rollers to reduce their thickness or to impart
to them any required polished embossed or other surface. The solution of cellu-
lose should be as perfect as possible and it may be filtered to remove any
impurities or undissolved cellulose. After precipitation the film sheet or web
may be purified by treatment with any of the usual reagents such for instance
as sulphites or sulphurous acid and if desired be bleached with a bleaching
solution such as sodium hypochlorite.
Dated this 12th day of Ion 1000
Improvements in the Manufacture and Production of a Material in
Film, Sheet, or Web Form.
I, CHARLES HENRY STEARN, of 47, Victoria Street, in the City of Westminster,
Electrician, do hereby declare the nature of this invention and in what manner
[Price 8d.]

page_text: the same is to be performed, to be particularly described and ascertained in and
by the following statement;-
-
The object of my invention is to manufacture a material in film, sheet, or
web, form, suitable, for example, for the production of thin sheets, films, or webs,
for various purposes, such as sheets for printing, or writing, purposes or films
for photographic, or cinematographic pictures, or for other purposes to which such
films, sheets, or webs, of material are applicable. According to my invention I
employ, for this purpose, a solution of cellulose made by treating cellulose with
strong alkali, and then with carbon bi-sulphide, and then dissolving the product
in water. A process for the production of such a preparation, (which is com-
monly known as viscose), is described in the Specification of British Letters
Patent No. 8700 of 1892. I precipitate the cellulose in the form of films, sheets,
or webs, by passing the solution thereof into, or into and through, a precipitating
or setting solution or liquid. This can be done by projecting the solution of
cellulose from a long narrow slit directly into the precipitating or setting solution
or liquid or by spreading it upon a surface upon which it is passed into, or into
and through; the precipitating or setting solution or liquid. The said surface
may be a cylinder or endless band which carries the cellulose solution through
the precipitating or setting solution or liquid and as the said surface emerges,
the cellulose material is drawn or otherwise removed from the cylinder, band or
the like, which, as it revolves, or moves round, receives continuously the cellulose
solution which becomes set in the precipitating or setting solution or liquid and
the sheet, or web, of cellulose material can be continuously removed. Alcohol,
brine, and sulphate of ammonium solution, for example, are precipitating or
setting liquids, or solutions; but I have found that a solution of chloride of
ammonium gives the best results, as, at the proper strength, it is of a specific
gravity which will allow the cellulose solution to pass downwards therein, and
it has the effect of immediately setting the said cellulose solution. By providing
means whereby the cellulose solution can be drawn rapidly through the precipi-
tating, or setting, solution, or liquid, the sheets, films, or webs, formed, can be
obtained of a thickness in accordance with the speed adopted, (the size of the
slit, and the pressure on the vessel, being the same). A suitable strength of the
chloride ammonium solution is one of a specific gravity of 1.050 to 1060, but I
do not limit myself to this particular strength. The sheets, films, or webs, may
be produced singly, or in any required number simultaneously, and can be wound
on rollers, or cut into lengths, or pieces, as desired.
In the preparation of the viscose solution the greatest care must be taken to
render the solution perfectly homogeneous and free from all undissolved particles
of cellulose.
The ordinary viscose of commerce generally consists of a mixture of a true
solution of cellulose with a jelly-like substance and contains many undissolved
fibres, or parts of fibres. This character remains in the viscose even after the
most careful filtering, and if sheets, films, or webs be made of such a material
the outlines, when viewed under the microscope, will be seen to be more, or less,
wavy, or sinuous, presenting sections of unequal thickness, and of unequal
strength, in various parts of the sheet, film, or web.
The non-homogeneous nature of such a solution is clearly apparent by the
variations in colour displayed, when viewed under the microscope in a thin film,
or layer, under polarised light.
A perfectly homogeneous solution can be obtained as follows:-
I first obtain the purest bleached cellulose and subject it to the action of
alkali, as in the well known process of mercerisation, continuing the process
until the solution of alkali has thoroughly penetrated through the mass. The
cellulose used should be as loose in structure as possible so as to admit of the
ready penetration of the alkali solution. When the mercerisation is thoroughly
accomplished, the excess of alkali is squeezed out and the alkali-cellulose is

page_text: treated with carbon bisulphide. When the reaction is complete sufficient water
is added to make a solution containing say, from 9½ to 10 per cent. of cellulose
and the mixture is thoroughly stirred for a considerable time by means of a
mixer revolving at high speed, the vessel containing the viscose being kept cool
during stirring.
The mixture must now be filtered very thoroughly and freed from air by the
air pump;
The solution, if carefully prepared and treated as aforesaid, will be perfectly
clear and structureless, or homogeneous, and of high viscosity, and is fit for pre-
cipitation, or setting, as aforesaid, and sheets, films, or webs, of great tensile
strength, and of even thickness throughout, are obtained.
The cellulose solution can be squirted through the slit under any suitable
pressure (air, or hydraulic, or mechanical) into the precipitating, or setting,
solution, or liquid, the slit being of the requisite width and length to give the
width and thickness of sheet, film, or web, required, which can be allowed to coil
upon itself, or be drawn off by a revolving roller, as may be desired.
The material should be placed, and remain from 6 to 12 hours in fresh chloride
of ammonium solution, or other setting solution, or liquid, so as to remove soluble
products as thoroughly as possible.
After digestion in the cold, the material is removed from the liquid and intro-
duced, for a few minutes, into a boiling solution of the same liquid, to regenerate
the cellulose by completing the decomposition of the sulpho-carbonate after which
it is washed in boiling water to remove all traces of the chloride. The resulting
cellulose may then be purified in any suitable way. The following way is suit-
able. The material is immersed in a hot solution of sodium carbonate, (washing
soda), and immersed in a solution of sodium hypochlorite, or other bleaching
solution, till colourless. It is then thoroughly washed and then may be treated
with dilute acids and washed. It is then dried in the air under tension, or
passed, under tension, through a heated chamber.
By providing a number of slits more than one sheet, film, or web, can be
made at the same time.
The sheets, films, or webs, produced may be reduced, polished, or otherwise
acted upon, by passing them between rollers.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is;
-
1. The manufacture of films, sheets, or webs, by projecting the aforesaid solution
of cellulose (viscose) into, or passing it into, or through, a precipitating, or setting,
solution, or liquid.
2. The manufacture of films, sheets, or webs, by projecting the aforesaid solu-
tion of cellulose (viscose) into, or passing it into, or through a solution of chloride
of ammonium.
3. The manufacture of films, sheets, or webs, by projecting the aforesaid solu-
tion of cellulose (viscose) through a slit into a precipitating, or setting, solution,
or liquid, and drawing it therethrough.
4. The preparation of films, sheets, or webs, by first subjecting the aforesaid
solution of cellulose (viscose) to stirring and filtering and then projecting, it from
a slit, into a solution of chloride of ammonium.
5. Films, sheets, or webs, for photographic, or printing, or other, purpose;
prepared from the aforesaid solution of cellulose (viscose) substantially as herein-
before set forth.
D thin 10th dow of October 1898
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.