Improvements in the Manufacture of Artificial Silk.” PREPARATION OF PYROXIL
Year: 1893

page_text: Date of Application, 21st Dec., 1893
. Complete Specification Left, 11th Sept., 1894-Accepted, 17th Nov., 1894
66
Improvements in the Manufacture of Artificial Silk.”
I, COMTE HILAIRE DE CHARDONNET, of 43 Rue Cambon, Paris, France, do hereby
declare the nature of this invention to be as follows :--
.1. PREPARATION OF PYROXIL.
As I have explained in my former Patents Nos. 2211 of 1886, 1656 of 1890 and
19560 of 1891, I can employ in working my invention, the manufacture of artificial
silk, by the thread drawing of liquids, any material containing cellulose. When wood
pulps are employed, they must undergo certain treatments for purifying them and
separating foreign substances; but when cotton is employed, it may be taken direct
from the gin or card without farther preparation.
1. kilo of cellulose is soaked in a mixture of 9 litres nitric acid of density 1:3 and
15.litres sulphuric acid of density 1.835, the whole at a temperature of 28° to 30° C.
The reaction is allowed to go on for 12 to 24 hours.
The whole (pyroxyl and acid) is subjected to the action of a filter press squeezing
out as much as possible of the acid. For subsequent nitrations, 85 per cent by volume
of. the acid used already, has added to it 15 per cent of fresh acid consisting of
3 volumes of nitric acid of density 1.48 and 4 volumes of monohydrated sulphuric
acid. This bath acts as the first bath.
The pyroxyl, pressed and drained, is washed with abundance of water for 8 to 12
hours as paper pulp is washed. During the washing the pyroxyline is bleached with
a little chloride of lime having added to it excess of nitric or hydrochloric acid.
When the pyroxyl is freed from the acids, it is dried by centrifugal action until it
contains not more than 25 or 30 per cent of water.
The pyroxyl, washed but not dried, as above stated, constitutes a special hydrate
much more soluble than dried pyroxyl. This hydrate is not produced by. putting
dried pyroxyl in contact with water.
In order to avoid the drying of the pyroxyl and its dangers, it may be centrifugally
treated or pressed in two operations and methodically treated.while it is moist, either
with alcohol or hydrated ether, the same ether serving indefinitely. In the former
case the dehydrated variety of pyroxyl is obtained, in the second case the more
soluble variety is obtained.

page_text: 28 or 30 kilos of moist pyroxyl are mixed 40 litres of alcohol and 60 litres of ether.
Solution takes place rapidly, producing liquid collodion.
This collodion is passed through a series of two or three filters under pressure of
air or a hydraulic piston, through layers of carded cotton and it is then ready for
thread drawing.
The fluidity of the collodion, or the solubility of the pyroxyl may be increased by
adding a few hundredth parts of the following bodies:-
Ethers, ethyl and methyl hydrochlorate, metallic chlorides (magnesium, aluminium,
manganese, tin &º), acetic acid, aldehyde, acetone, carbon bisulphide, hydrochloric,
nitric or sulphuric acids.
3. THREAD DRAWING OF THE COLLODION.
All thick collodions containing more than 15 to 20 per cent of their weight of
pyroxyl may be thread drawn either by discharging the threads into water, as
described in my former Patents 2211 of 1886, 1656 of 1890 and 19500 of 1891, or by
discharging them simply into the air. In the latter case, part of the guides may be
left or suppressed, or the threads may be made to rub along a sponge or other moist
body so as to coagulate them more rapidly by the presence of water.
The same machines may therefore serve, without modification, to thread draw with
or without water collodions prepared as above. The drawing without water is possible
because collodion containing the water of combination of the hydrated pyroxyl becomes
rapidly firm in air, the threads do not get glued together and the multiple threads
remain more open and supple than when any other process is employed.
4. DENITRATION OF THE SKEINS.
After milling and floating, the skeins of pyroxyl thread are subjected to denitration
in the following manner.
8 kilos of monosulphide of calcium and 4 kilos of commercial sulphate of ammonia
are introduced into a hectolitre of water. The mixture is agitated and left to react
for an hour or two. The solid precipitate is then separated by filtration or centrifugal
action, and the clear bath is used for denitration of the skeins. For this purpose the
bath is heated in a wooden tank to 28° or 30° by a steam coil, the skeins are
plunged and moved about in it for about an hour, 2 kilos of silk being treated for
each hectolitre of bath.
The spent bath is rendered scarcely acid by an addition of sulphuric acid. A
quantity of calcium sulphide is added proportioned to the sulphate and nitrate of
ammonia existing in the bath; the precipitate is separated as before, and the bath is
ready for subsequent use.
The calcium monosulphide for this denitrating bath is prepared by heating for
several hours in gas retorts, 1,000 parts of plaster and 400 parts of bruised charcoal.
There is nothing special in the furnace except that the heads of the retorts are turned
down so that the outlet for the gas is below. Thus by acting with a rake passing
through a hole of the door the sulphide can be made to fall, when once it is formed,
into a receptacle, by acting without access of air. The product is ground to a fine
powder, by millstones, rollers or centrifugal bruisers.
For the calcium sulphide may be substituted an equivalent quantity of hydro.
sulphate of calcium sulphide, enough to saturate exactly the sulphate of ammonia, or
soda ash may be used. For the sulphate of ammonia may be substituted the
nitrate or the hydrochlorate of ammonia or any other ammoniacal salt capable
of decomposing calcium monosulphide.
Dated this 21st day of December 1893.

page_text: 66
Improvements in the Manufacture of Artificial Silk.'
"
I, COMTE HILAIRE DE CHARDONNET, of 43 Rue Cambon, Paris, France, 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 :-
1. PREPARATION OF PYROXYL.
As I have explained in my former Patents No. 2211 of 1886, 1656 of 1890, and
19560 of 1891, I can employ in working my invention, the manufacture of artificial
silk by the thread drawing of liquids, any material containing cellulose.
When wood pulps are employed, they must undergo certain treatments for purifying
them and separating foreign substances; but, when cotton is employed, it may be
taken direct from the gin or card without farther preparation.
1 kilo. of cellulose is soaked in a mixture of 9 litres nitric acid of density 1.3, and
15 litres sulphuric acid of density 1-835, the whole at a temperature of 28° to 30° C.
The reaction is allowed to go on for 12 to 24 hours.
The whole (pyroxyl and acid) is subjected to the action of a filter press squeezing
out as much as possible of the acid. For subsequent nitrations 85 per cent by volume
of the acid used already, has added to it 15 per cent of fresh acid consisting of 3
volumes of nitric acid of density 1.48 and 4 volumes of monohydrated sulphuric acid
(oil of vitriol). This bath acts as the first bath.
The pyroxyl, pressed and drained, is washed with abundance of water for 8 to 12
hours as paper pulp is washed. During the washing, the pyroxyl is bleached with a
little chloride of lime having added to it excess of nitric or hydrochloric acid.
When the pyroxyl is freed from the acids, it is dried by centrifugal action until it
contains not more than 25 or 30 per cent of water.
The pyroxyl, washed but not dried, as above stated, constitutes a special hydrate
much more soluble than dried pyroxyl. This hydrate is not reproduced by putting
dried pyroxyl in contact with water.
In order to avoid the drying of the pyroxyl and its dangers, it may be centrifugally
treated or pressed in two operations and methodically treated while it is moist, either
with alcohol or hydrated ether (ether containing 1 30th of its weight of water) the
same ether serving repeatedly. In the former case, the dehydrated variety of pyroxyl
is obtained, in the second case, the more soluble hydrated variety is obtained.

page_text: 3. THREAD DRAWING OF THE COLLODION.
All thick collodions containing more than 15 to 20 per cent of their weight
of pyroxyl may be thread drawn either by discharging the threads into water,
as described in my former Specifications to Patents No. 2211 of 1886, 1656 of 1890,
and 19560 of 1891, or by.discharging them simply into the air. In the latter case,
part of the guides may be left or suppressed, or the threads may be made to rub
along a sponge or other moist body, so as to coagulate them more rapidly by the
presence of water.
The same machines may therefore serve, without modification, to thread draw,
with or without water, collodions prepared as above described. The drawing without
water is possible because collodion, containing the water of combination of the
hydrated pyroxyl, becomes rapidly firm in air, the threads do not get glued together
and the multiple threads remain more open and supple than when any other process
is employed.
4. DENITRATION OF THE SKEINS.
After spinning and reeling, the skeins of pyroxyl thread are subjected to denitration
in the following manner.
8 kilos of calcium monosulphide and 4 kilos of commercial ammonium sulphate
are introduced into a hectolitre of water. The mixture is agitated and left to react
for an hour or two. The solid precipitate is then separated by filtration or
centrifugal action and the clear bath is used for denitration of the skeins. For this
purpose the bath is heated in a wooden tank to 28° or 30° C. by a steam coil, the
skeins are plunged and moved about in it for about an hour, 2 kilos of silk being
treated for each hectolitre of bath.
The spent bath is rendered scarcely acid by an addition of sulphuric acid. A
quantity of calcium sulphide is added proportioned to the ammonium sulphate and
nitrate existing in the bath; the precipitate is separated as before, and the bath is
ready for subsequent use.
The calcium monosulphide for this denitrating bath is prepared by heating for
several hours in gas retorts 1000 parts of plaster and 400 parts of bruised charcoal.
There is nothing special in the furnace except that the heads of the retorts are
turned down so that the outlet for the gas is below. Thus, by acting with a rake
passing through a hole of the door, the sulphide can be made to fall, whon once it is
formed into a receptacle, by operating without permitting access of air. The product
is ground to a fine powder, by millstones, rollers or centrifugal bruisers.
For the calcium sulphide may be substituted an equivalent.quantity of hydro-
sulphate of calcium sulphide (CaS.HS.), enough to saturate exactly the ammoniumi
sulphate, or soda ash may be used. For the ammonium sulphate may be substituted
the ammonium nitrate or hydrochlorate or any other ammoniacal salt capable of
decomposing calcium monosulphide.
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, as improvements in the manufacture of artificial silk, is :—
1. The preparation, substantially as herein described, of a new body, hydrate of
nitrocellulose differing from ordinary nitrocellulose or pyroxylin in having in its
composition & quantity of water of condensation.
2: The use of the hydrate of nitrocellulose above referred to in the preparation of
collodions distinguished by their fluidity and their facility of coagulating in air.
3. In preparing the collodions, in order to increase fluidity, the admixture there-
with in small proportions of ethers, ethyl or methyl hydrochlorates, metallic
chlorides, acetic acid, acetic ether, aldehyde, acetone, carbon bisulphide, hydro-
chtoric or nitric acid.
4. The use of the collodions above referred to in the manufacture of artificial silk,

page_text: the filament being discharged into water or air or passed in contact with a moist
body, substantially as described.
5. The preparation of the denitrating bath by a mixture of calcium-monosulphide.
and ammonium sulphate or other-ammoniacal salt capable of decomposing the
calcium monosulphide, and the regeneration of the spent bath by addition of
sulphuric acid, and, after separation of the precipitate, by addition of calcium
monosulphide.
Dated this 11th day of September 1894.
ABEL & IMRAY-
Agents for Applicant.