CERTAIN MEANS OF DEVULCANIZING INDIA-RUBBER AND OTHER SIMILAR GUMS, OR OF TREATING SUCH GUMS AFTER HAVING BEEN VULCANIZED
Year: 1855

page_text: LETTERS PATENT to Richard Archibald Brooman, of 166, Fleet Street,
in the City of London, Patent Agent, for the Invention of "CERTAIN
MEANS OF DEVULCANIZING INDIA-RUBBER AND OTHER SIMILAR GUMS, OR OF
TREATING SUCH GUMS AFTER HAVING BEEN VULCANIZED."A communication.
Sealed the 26th June 1855, and dated the 12th January 1855.
PROVISIONAL SPECIFICATION left by the said Richard Archibald
Brooman at the Office of the Commissioners of Patents, with his
Petition, on the 12th January 1855.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention for
"CERTAIN MEANS OF DEVULCANIZING INDIA-RUBBER AND OTHER SIMILAR GUMS, OR
OF TREATING SUCH GUMS AFTER HAVING BEEN VULCANIZED," (communicated to me
by a foreigner residing abroad,) to be as follows:
In treating or manufacturing native caoutchouc and other gums of similar
chemical character, there is for most purposes a process performed, commonly
called vulcanizing," as is well known.. This vulcanizing is the effect, pro-
duced by the employment of sulphur or other suitable matter, in combination
with heat, and in the opinion of most chemists is nothing more than an altered
condition of the cohesive properties of the material. This alteration is such,
however, as to prevent any after use of the old or spoiled caoutchouc articles
-

page_text: in the way of new manufacture; hence, many attempts have been made to
effect the restoration, which is at length accomplished by the present Invention.
In order to attain this end the caoutchouc or other gum must be restored to
its orginal condition as respects cohesion and elasticity, for this is the only true
devulcanization. Many have supposed that the extraction of the sulphur or
other foreign ingredient would effect the desired result, but such is not the
case, for the whole of the sulphur may be extracted, and yet the principle of
vulcanizing remain, and this arises from the fact that the foreign ingredient
alone will not vulcanize; it must have the additional element, heat. The pro-
cess may be separated into two parts, viz., devulcanization and purification.
The first relates to the restoration of the gum to its original conditions of
cohesion and elasticity; and the second, to the extraction of the foreign sub-
stances which may have been used in the previous manufacture, such as sulphur,
oxide of lead, zinc, &c.
The process is as follows:-In the first place the vulcanized gum is prepared
by grinding it in a suitable mill, such as is common in rubber factories. A
quantity is then put into a proper vessel, and submitted to the action of the
vapors of turpentine or camphine for a sufficient length of time. By this means
the ground gum will be melted, as it were, into a mass, and may be taken out
in a cohesive elastic state, when it will be found fully devulcanized, so that not-
withstanding the sulphur and other foreign ingredients are still remaining, the
gum is capable of being re-manufactured. This process is usually completed
in about three hours. Instead of the vapors of turpentine, that of other spirits
might be used, such as ether, &c. ; but as the boiling point of those is at a much
lower temperature than that of turpentine, it will be necessary to heat their
vapors up to at least 200° Fahrenheit, before submitting the caoutchouc or
other gum to their action.
Purification may be performed either before or after devulcanizing, as may
be preferred. This is for the purpose of extracting all foreign matters, and is
effected by boiling the rubber in caustic alkali, or by a combination of alkalies
and fixed or essential oils. The boiling must be repeated until the purification
is complete. Although the vapors of turpentine or camphine are especially
applicable, yet the vapors of any other materials, which are capable of dissolving
or swelling the gums, will answer. After the process of devulcanizing has been
gone through, the gum is then capable of being completely dissolved by the
liquid turpentine, naphtha, camphine, &c.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Richard Archibald Brooman in the Great Seal Patent Office
on the 12th July 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of London, Patent
Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria; by Her Letters
Patent, bearing date the Twelfth day of January, in the year of our Lord
One thousand eight hundred and fifty-five, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Richard Archibald Brooman, Her special licence, that I, the said
Richard Archibald Brooman, my executors, administrators, and assigns, or
such others as I, the said Richard Archibald Brooman, my executors, admi-
nistrators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "CERTAIN MEANS OF DEVULCANIZING INDIA-RUBBER AND
OTHER SIMILAR GUMS, OR OF TREATING SUCH GUMS AFTER HAVING BEEN VULCANIZED,"
(communicated to me by a foreigner residing abroad,) upon the condition
(amongst others) that I, the said Richard Archibald Brooman, by an instru-
ment in writing under my hand and seal, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.,
.
NOW KNOW YE, that I, the said Richard Archibald Brooman, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:-
This Invention consists in a process for treating india-rubber and gutta
percha or their compounds, after they have been cured or vulcanized with
sulphur; such treatment having for its object the restoring of the said gums to
a condition or state wherein they may be again employed, either as a substitute
for the original or native material, or in combination or mixture with it. This
treatment may be called devulcanization, because it effects a change from the
state of cohesion existing in the vulcanized gum to another state, nearly if
not quite identical with that of the original native material...

page_text: thaise
The operation is as follows:-In the first place the vulcanized gum is
prepared by grinding between rollers into small pieces or to powder. The
sulphur may now be extracted by the application of several chemical agents,
such as alkaline leys, soap, and mixtures of alkalies with essential or fixed
oils; grease, rosin, naptha, bisulphiuret. of carbon, ether, &c. It is preferable
first to boil the ground rubber in an alkaline ley, and afterwards to give it a
second boiling in an alkaline solution to which are added spirits of turpentinė.
This latter facilitates the operation by causing the gum to soften and swell," and
thus allows the alkali to act more energetically in dissolving the sulphur. This
process is to be continued for a greater for less time, and the operation to be
repeated until the sulphur is fully extracted: The rubber is then washed,
pressed, and dried; when it will be ready for the second or devulcanizing
process
In the manufacture of rubber it is often adulterated with other substances,
such as chalk, white lead; metals; oxides, &c. If it is desirable to separate
these also (although this is not essential), the rubber may be treated with acetic
or pyroligneous acid, or other chemical agents, all of which are well known
and to give clearness and transparency to the gum, it may still further be treated
with a solution of cyanide of potassium, hypochloride of lime, or other 'like
de-oxidizing substance.
or
ין
The devulcanization or change in the state of cohesion is effected by means
of certain substances which are known to be solvents of the native gums, in
connection with the employment of heat. Some of the materials which have
been found applicable' are spirits of turpentine, naptha, bicarburet of sulphur,
and any
essential fixed oils, or combinations of such substances; or others, as
a' mixture of turpentine" and alcohol, or ether. It is preferred to employ
spirits of turpentine as the principal material, that being the most economical
and readily obtained. This is applied' in one of two ways, according as it is
wished to obtain a compact and solid, or a softer and more liquid, product.
For the former, the gum is submitted to the vapors of turpentine in a suitable
vessel for a certain length of time, which may vary according to circumstances;
as for instance, if the gum has been more or less purified in the preliminary
preparation, the time of treatment will be more or less prolonged. This can in
all cases be ascertained by experimenting with sinall pieces of the gum taken
out from time to time and kneading them in the fingers, when as soon as it
appears compact and elastic, the process is completed. The gum is then taken
out of the vaporing vessel and dried, when it is fit for use, as before stated:
To perform the operation with the least expenditure of turpentine, the vapour
may be collected and condensed in a still in a manner well known. When

page_text: the
gum is required to be obtained in a softer state, it is to be immersed in the
turpentine and subjected to heat as before, until by trial it is found to have
the necessary cohesion and elasticity. When this latter process is employed,
it is proper, in order to prevent the mass from being tacky, to introduce alcohol,
or a small quantity of sulphur into the solution.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that I do not limit myself
precisely to the use of the particular ingredients or process named, as the
same are undoubtedly susceptible of considerable variation without in the least
changing the character of the Invention or the results produced thereby; but
I claim, the restoration of caoutchouc, gutta percha, or other similar gums,
which have undergone the process of being cured or vulcanized, in such manner
that these gums may be available to be used again, either as a substitute for
native gums of like character, or in combination with them by means sub-
stantially of the process herein described.
In witness whereof, I, the said Richard Archibald Brooman, have
hereunto set my hand and seal, this Twelfth day of July, One thousand
eight hundred and fifty-five.
R. A. BROOMAN. (L.S.)