Improvements in and in the Manufacture of Artificial Silk.
Year: 1898

page_text: Date of Application, 16th Feb., 1898-Accepted, 7th May, 1898
Improvements in and in the Manufacture of Artificial Silk.
I, HERMAN CHARles Woltereck, of 15/25 Whitehall Street, New York, in the
United States of America, Consulting Chemist, 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:-
My invention relates to the art of producing artificial silk, its object being to
obtain a thread which with all the desirable characteristics of natural silk shall
also combine its tensile strength, which heretofore has been lacking in all artificial
silk produced up to date, and which shall at the same time be produced more
cheaply and conveniently.
Briefly stated the essential features of my invention are as follows A thread of
cotton, or any other suitable material, is passed through a suitable solution of
cellulose or a compound of cellulose and is therein impregnated and covered with
said solution. The thread passes next through a coagulating solution which
removes the greater part of the solvent or solvents and next through a fixing bath,
by which the cellulose or compound of cellulose is permanently fixed on the fibre
of the thread, which has only to be washed and dried to be the finished product.
This artificial silk thread may be dyed the same as the natural product of the silk
worm.
This process in giving a high tensile strength to the artificial silk does away at
the same time with the complicated machinery and delicate apparatus heretofore
employed for obtaining a lower grade product and cheapens the cost of manufacture
considerably.
My process consists of the following steps:
1. Impregnating the thread with a solution of cellulose or compound of cellulose
or solvents of cellulose.
This may be executed in a number of ways by using the different modifications
of cellulose dissolved in cuprammonia (Schweitzer's reagent), by using the solution
resulting from the treatment of cellulose with caustic alkalies and bisulphide of
carbon (probably a thio-carbonate of cellulose) or by using the soluble nitro com-
pounds of cellulose in one of their many solvents.
If the process is to be applied to cotton, or other modifications of cellulose, and
the cuprammonia solution is to be used the thread is to be moistened with dilute
ammonia and passed through the cuprammonia solution, which may contain dis-
solved cellulose or not, according to the quality of the product desired. In the
latter case, the solution partially dissolves the surface of the fibre only and a very
brilliant lustre is obtained; if a solution of cellulose preferably saturated is em-
ployed, a heavier and stronger article is produced. All other materials may be
treated in the same way as described in the following modifications of the process.
If the solution of cellulose in caustic alkali and bisulphide of carbon or a solution
of pyroxylin is to be used the spool containing the thread may be placed in the

page_text: solution, which should contain from 5% of the compound cellulose up to
saturation.
2. Coagulating the cellulose compound on the fibre: The thread is conducted to
a spool which is submerged in water or a coagulating liquid corresponding to the
medium employed such as, benzol, tuluol, xylol, coal oil and all other solvents
which will take up the solvent of the nitro-cellulose without redissolving the
latter, and is there reeled up until the spool or reel is filled when it is removed
and placed in the fixing bath.
3. Fixing the cellulose compound on the fibre: In the fixing bath the cellulose
is fixed on the fibre by the use of dilute acids in the case of cuprammonia com-
pound having been used, or the nitro compounds are more or less completely
reduced to cellulose by the use of an alkaline sulfhydrate, ferrous acetate, ferric
chloride or the like. In the case of a solution of the thio-carbonate having been
used the coagulating and fixing baths may be combined in one operation.
I will illustrate my process in its three different stages by one of its methods of
application.
A spun cotton thread is conducted through a vessel containing a 5% solution
of pyroxylin in alcohol and ether and passes from there through the coagulating
bath, which may consist of pure water in this case and by which the solvents are
removed and the pyroxylin precipitated on the surface of the fibre; the thread is
next passed through the fixing bath containing about 5 per cent. of the reducing
agent employed. For the fixing bath a great number of chemicals may be
employed, among others, solutions of the sulfhydrates of the alkalies may be used
to advantage, others are sesquichloride of iron, ferrous acetate and others whose
action reduces the combination of cellulose with nitric acid to cellulose or a lower
degree of nitration than the pyroxylin employed. The original thread of cotton
is now covered with a fine layer of cellulose which gives it the appearance and
dyeing qualities of natural silk. The product is finished by a thorough rinsing in
water and drying.
I do not confine myself to the materials or proportions of materials described
in the above specification, since a great variety of compounds may be used or the
proportions greatly varied. I do, however, especially disclaim the simple use of
collodion or other soluble nitrocompounds without their subsequent reduction, since
their product are highly inflammable and therefore absolutely unadapted for
practical purposes.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
I. The process of producing artificial silk by producing on a thread of cotton
or other suitable material a coating or sheath of cellulose or compound of cellulose
for the purpose as set forth and described.
II. The process of providing a thread of cotton or other suitable material with
a cover or coating of cellulose or compound of the same by successively treating the
same with a solution of cellulose or compounds of the same, by treating the thread
thus impregnated with said solution of cellulose or compounds of the same with a
coagulating liquid for the purpose of removing all or part of the solvent or solvents of
said cellulose or compound of the same, and by finally treating the thread thus pre-
pared with a fixing bath for the purpose of fixing the cellulose precipitated on the
fibre of the thread or of reducing the compounds of cellulose employed either com-
pletely or partially to cellulose or other compounds of the same, all for the purpose
as set forth and described.
III. As a new article of manufacture artificial silk consisting of a body or core
of cotton or other suitable material, covered by a layer of cellulose or compounds
of the same, produced or deposited on said thread in a suitable manner, as set
forth and described.

page_text: IV. As a new article of manufacture artificial silk, consisting of a body or core
of spun cotton or other suitable material, covered with a layer of cellulose or
compound of cellulose produced on said thread in a suitable manner as described
and for the purpose as set forth.
Dated this 15th day of Fabmua 1900
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.