IMPROVEMENTS IN DISSOLVING OR TREATING RUBBER, GUTTA PERCHA, COPAL, AND SIMILAR GUMS OR RESINS, AND THEIR COMPOUNDS
Year: 1866

page_text: LETTERS PATENT to Edmund Hunt, of No. 87, St. Vincent Street, in the
City of Glasgow, and No. 1, Serle Street, Lincoln's Inn, in the County
of Middlesex, for the Invention of "IMPROVEMENTS IN DISSOLVING OR
TREATING RUBBER, GUTTA PERCHA, COPAL, AND SIMILAR GUMS OR RESINS, AND
THEIR COMPOUNDS."
Sealed the 18th December 1866, and dated the 22nd June 1866.
PROVISIONAL SPECIFICATION left by the said Edmund Hunt at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
June 1866.
I, EDMUND HUNT, of No. 87, St. Vincent Street, in the City of Glasgow,
and No. 1, Serle Street, Lincoln's Inn, in the County of Middlesex, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN DISSOLVING OR
TREATING RUBBER, GUTTA PERCHA, COPAL, AND SIMILAR GUMS OR RESINS, AND
THEIR COMPOUNDS," to be as follows, that is to say:
This Invention consists in employing an acid or alkaline substance which
is an oleaginous fluid at any temperature below 300 degrees Fahrenheit for
dissolving or treating difficultly soluble gums or resins, such as rubber,
gutta percha, or copal, and their compounds. Oleic acid, carbolic acid,
cresylic acid, creosote, and aniline appear to be the most suitable or con-
venient substances of the kind indicated for the purpose in view, but various
homologues thereof may be used if obtainable at a low enough cost.

page_text: An important application of the Invention is that to the compounds of
rubber known as vulcanised or mineralised rubber, as it permits of the hitherto
waste pieces of such compounds being renovated and re-manufactured. The
hard compound of rubber known as vulcanite or ebonite may also be dissolved
by the substances herein-before indicated, or some of them.
In practising the Invention the gum or resin is first, by preference, reduced
to small particles, which are then mixed with the solvent. The dissolving
action is hastened by heat, which is essential, if the solvent is not fluid at
ordinary temperatures, but the beat need not exceed 300 degrees Fahrenheit.
The proportion of solvent will vary with the kind of solvent and with the
gum, resin, or compound treated, but it is not of the slightest practical
importance, as when the solvent is in excess the gum, resin, or compound
may be added until the solvent will take no more; whilst if the solvent does
not dissolve the whole at first, it may be poured off when saturated and fresh
solvent may be added. Agitation also hastens the dissolving action. After the
solution is formed it may be modified or treated in various ways according to
manufacturing requirements. More or less of the solvent may be removed
by washing with an alkaline or acid solution accordingly as the solvent is acid
or alkaline, and the solvent can afterwards be recovered by well-known means.
If oleic acid is the solvent the solution may be diluted with benzene, naphtha,
or a similar bydrocarbon; and then if methylated alcohol is added the rubber
or other gum or resin not soluble in alcohol will be precipitated in a soft
plastic condition.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edmund Hunt in the Great Seal Patent Office on the 20th
December 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDMUND
HUNT, of No. 87, St. Vincent St., in the City of Glasgow, and No. 1, Serle
St., Lincoln's Inn, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of June, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Edmund Hunt, Her special licence that I, the said Edmund Hunt,
my executors, administrators, and assigns, or such others as I, the said
Edmund Hunt, my executors, administrators, and assigns, should at any tinie

page_text: 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 "IMPROVEMENTS IN
DISSOLVING OR TREATING RUBBER, GUTTA PERCHA, COPAL, AND SIMILAR GUMS OR
RESINS, AND THEIR COMPOUNDS," upon the condition (amongst others) that I,
the said Edmund Hunt, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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
the said Edmund Hunt, do. hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, that is to say :-
My said Invention consists in employing an acid or alkaline substance
which is an oleaginous fluid at any temperature below 300 degrees Fahrenheit
for dissolving or treating difficultly soluble gums or resins, such as rubber,
gutta percha, or copal, and their compounds. Oleic acid, carbolic acid,
cresylic acid, creosote, and aniline appear to be the most suitable and con-
venient substances of the kind indicated for the purpose in view, but various
homologues thereof may be used if obtainable at a low enough cost. Of the
substances named oleic acid is to be preferred, on account of its comparatively
low cost.
An important application of my Invention is that to the compounds of
rubber known as vulcanised or mineralised rubber, as it permits of the
hitherto waste pieces of such compounds being renovated and re-manu-
factured. The utility of the Invention in this application arises from the fact
that on account of the nature of the solvent the rubber after being first
dissolved in it can be again separated from it by economical and convenient
means in a state suitable for re-manufacture. The hard compound of rubber
known as vulcanite or ebonite may also be dissolved by the substances herein-
before indicated, or some of them.
In practising my said Invention in the case of vulcanised rubber, for
example, the rubber is first, by preference, reduced to small particles, which
are mixed with the oleic acid. Commercial oleic acid may be used, but
should, if necessary, be freed from sulphuric acid by washing with water. I
prefer to hasten the dissolving action by the aid of heat, but the temperature

page_text: should not exceed 300 degrees Fahrenheit. Agitation or stirring of the
mixture also hastens the dissolving action. The proportion of solvent will
vary with the quality of the vulcanised rubber, and inversely with the tem-
perature employed, but I prefer to use a comparatively low temperature,
say, 240 degrees Fahrenheit, and to have the solvent in excess of the
minimum that will dissolve the quantity of rubber treated. Convenient
proportions for the solvent are easily determined in practice by trials with
small quantities of the various qualities of rubber treated. It is also to be
observed that as the solvent is for the most part subsequently recovered,
there arises no waste from using a little more of it than may be absolutely
requisite.
In order to separate the rubber from the oleic acid 1 allow the solution to
cool, and then add methylated spirit, which causes the rubber to be pre-
cipitated. I pour off the mixture of oleic acid and spirit, and wash the
precipitated rubber once or twice with fresh spirit. Finally, to remove the
last apparent traces of oleic acid from the rubber, I boil it in a very weak
solution of caustic soda, and afterwards in pure water. The rubber thus
treated is in a plastic condition, and on being dried and heated to the ordinary
"curing" temperature has thereby restored to it the properties of ordinary
vulcanised rubber. It may of course be manufactured into various forms
before being re-cured either alone or in combination with new rubber. When
in the plastic condition, but freed from water by slowly drying at a low tem-
perature, it dissolves with great facility in benzene and similar volatile fluids,
and may be used for waterproofing. If sulphur is the vulcanising ingredient
in the waste rubber treated a part of the sulphur is removed by the oleic acid
unless that acid holds as much sulphur in solution as it can from being used
with previous lots of rubber. If wished additional sulphur may be added to
the rubber when in solution in the oleic acid, and a comparatively large
proportion may be completely dissolved in the solution, becoming thus most
intimately combined with the rubber. Fresh rubber may be dissolved
combined with it by solution in
in oleic acid in order to have sulphur
this way.
The methylated spirit is separated by distillation from its mixture with
the oleic acid, and it is unimportant whether a fresh quantity of rubber
is added to the mixture before the distillation, or to the oleic acid afterwards.
The treatment of vulcanised rubber with the other solvents herein-before
indicated is similar to that with oleic acid, but if an alkaline solvent, such as
hniline is used, the precipitated rubber is to be boiled in very dilute hydro-
caloric or sulphuric acid, and finally in pure water. In some cases benzene

page_text: or other similar fluid may be used instead of methylated spirit to precipitate
the rubber or other gum or resin from its solvent.
Common rosin is an acid substance which is oleaginous when fluid, and
which has already been used with vulcanised rubber and other ingredients as
a compound varnish or preservative coating for metal and other surfaces.
There is no doubt that in this compound varnish the vulcanised rubber is
dissolved more or less by the rosin, and I do not therefore claim as new the
dissolving of vulcanized rubber or other gum or resin by means of rosin; but
the recovering of vulcanised rubber by first dissolving it in melted rosin and
then separating the rosin I believe to be new, and do claim.
Having now particularly described my said Invention, and the manner in
which the same is to be performed, I have to state that I do not restrict
myself to the precise details herein-before described, but that what I believe
to be novel and original and claim as the Invention secured to me by the
herein-before in part recited Letters Patent is, with the exception herein-
before pointed out, the employing of an acid or alkaline substance which is
an oleaginous fluid at any temperature below 300 degrees Fahrenheit for
dissolving or treating difficultly soluble gums or resins, such as rubber,
gutta percha, or copal, and their compounds, and especially the recovering or
renovating of vulcanised or mineralised rubber by means substantially such as
are herein-before described.
In witness whereof, I, the said Edmund Hunt, have hereunto set my
hand and seal, this Nineteenth day of December, in the year of our
Lord One thousand eight hundred and sixty-six.
EDMUND HUNT. (L.S.)