IMPROVED METHOD OF TREATING CAOUTCHOUC AND GUTTA-PERCHA
Year: 1881

page_text: LETTERS PATENT to Edgar Edmonds, of the Firm of Robertson, Brooman,
and Company, of 166, Fleet Street, in the City of London, Patent Agents, for
an Invention of 'IMPROVED METHOD OF TREATING CAOUTCHOUC AND
GUTTA-PERCHA." A communication from abroad by George M. Mowbray,
of North Adams, Massachusetts, U.S.A.
PROVISIONAL SPECIFICATION left by the said Edgar Edmonds at the Office
of the Commissioners of Patents on the 14th January 1881.
EDGAR EDMONDS, of the Firm of Robertson, Brooman, and Company, of
166, Fleet Street, in the City of London, Patent Agents. "IMPROVED METHOD
OF TREATING CAOUTCHOUC AND GUTTA-PERCHA." [A communication from abroad
by George M. Mowbray, of North Adams, Massachusetts, U.S.A.]
This Invention relates to a new method of treating caoutchouc, gutta percha,
and analogous gums before, during, and after mastication.
As heretofore practised the process of masticating caoutchouc and gutta percha
induces a peculiar molecular change, which continues and is accelerated by
exposure to light and air. This change lessens their peculiar ductile, elastic, and
insulating properties besides impairing their durability.
Selected gutta percha, provided the process of mastication has been conducted
at a moderate temperature and not prolonged, if submerged in salt water seems to
be protected from this progressive decomposition whilst immersed, but a few weeks
of exposure to the solar rays and air rapidly renews decay, and thus gutta percha
also loses its tensile strength and insulating properties, becoming so friable as to be
easily reduced to powder between the finger and thumb.
This Invention prevents these decomposing changes taking place, and enables
the manufacturer to reduce caoutchouc, gutta percha, and their analogues to a
plastic form without starting decomposition during the process of manipulation.
It consists in heating these gums with melted napthaline at a low temperature,
say, about 212° F. until perfect combination takes place, and subsequently
removing every particle of the excipient by spontaneous evaporation.
The proportions found suitable to effect this purpose are for caoutchouc from
fifty (50) to seventy five (75) per cent. of napthaline, and for gutta percha about
twenty five (25) per cent is sufficient.

page_text: The gum is first purified by subdivisions, washing, drying, and warming to
about 212° to remove dirt and water; the napthaline is meanwhile melted in a
steam jacketed pan, and the gum previously cut into thin slices being introduced,
is stirred in the melted napthaline so as to uniformly coat each piece of gum
therewith. The gum and the napthaline are now allowed to digest together until
the former is thoroughly permeated with the napthaline, and the sufficiency of
this digestion is ascertained by testing, drawing the napthalised gum apart with
the fingers.
With gutta percha two hours digestion is sufficient; caoutchouc requires from
four to twelve hours, in both cases the pan should be covered, and if the cover is
of metal it should be protected from cooling with blankets or some non-conductor
of heat. A temperature not exceeding 230° F. is sufficient.
The warm plastic mass may now be removed to a double grooved roller steam
jacketed masticator. The rollers being set in motion for from fifteen minutes to
one hour until the compound is reduced to a homogeneous mass, whose edges when
drawn out are semi-translucent.
It is now in condition for admixture either with gum resins, sulphur, sulphides,
phosphorus (amorphous) or phosphides, iodine; and iodides, bromine or bromides,
corrosive sublimate, creszlic or carbolic acid, and these materials being soluble in
napthaline should be melted therewith, digested until dissolved or mixed perfectly,
and added to the plastic napthalised gum, caoutchouc, or gum gutta percha before
they chill or solidify.
Matters that are insoluble in napthaline may be added in a pulverulent form
before removing from the masticator.
Finally, after a homogeneous composition has been prepared, and either rolled
into sheets, formed into moulds, pressed through a die over wire, rolled onto plain,
perforated, or woven metal, or onto or over fibrous or woven textile fabrics or
felted material, the product is suspended in a well ventilated room maintained at
a temperature of about 70° F., and after a period of from ten to forty days,
dependent on the thickness of the mass, all the napthaline will leave the com-
position, and if sulphur and sulphides have been added in suitable proportions, it
may be submitted to the process of vulcanisation in the usual manner, either for
elastic or hard rubber, being less capable of change than by the processes of
manufacture heretofore in use.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Edgar Edmonds in the Great Seal Patent Office on the 14th July
1881.
EDGAR EDMONDS, of the Firm of Robertson, Brooman, and Company, of
"IMPROVED METHOD OF
166, Fleet Street, in the City of London, Patent Agents.
TREATING CAOUTCHOUC AND GUTTA-PERCHA." (A communication from abroad
by George M. Mowbray, of North Adams, Massachusetts, U.S.A.)
The nature of my Invention consists in a new method of treating caoutchouc and
gutta percha before, during, and after the process known in the art as "mastication,"
and in the new products arising therefrom.
As heretofore practiced the process of masticating caoutchouc induces a peculiar
molecular change, causing the gum to lose its tenacious, elastic, and insulating
properties, besides impairing its durability. Such change once commenced
continues with fatal rapidity under the combined influences of the solar rays and
air, nor is it entirely arrested when light is excluded; hence, after mastication by
present methods, caoutchouc, being in a condition of gradual decay, is unsuitable
as an insulator for the conducting-wires of a submarine cable and for many other
purposes.
Precisely the same change takes place with gutta percha, except that exclusion
of light and air seems to arrest this progress to gradual decay as when immersed
under water, so that gutta percha can be successfully used for submarine cables,
but if exposed to sun and air then gutta percha changes more rapidly than
caoutchouc.
My Invention obviates this change and preserves unimpaired during and after
mastication the valuable properties of elasticity, capacity for resisting conduction,
and durability possessed by the natural unmanufactured gums, and further enables
a manufacturer to intimately combine with the material, treated as described
hereinafter, certain other materials, thereby originating a series of new and useful
compounds suitable for electric and other purposes; and my Invention therein
consists in the new processes and new product arising therefrom which I now
proceed to describe.
I first cut caoutchouc into small pieces and free it from moisture in any suitable
way. If the final product is required to be nearly pure caoutchouc with slight
admixture of foreign matter, then to twenty (20) pounds of the gum I add from
five (5) to ten (10) pounds of naphthaline. If however the final product sought
be caoutchouc in combination with a large proportion of other materials, in that
case to twenty pounds of caoutchouc I add from fifteen to twenty pounds of
naphthaline. I place the pieces of cut caoutchouc and naphthaline in a covered
copper pan heated by steam or boiling water, and digest these together for a period
of from twenty-four to forty-eight hours at a temperature between 180° and 230°
Fahrenheit. After the digestion is completed I introduce the hot mass before its
temperature lowers to 175° Fahrenheit into a machine for masticating, which has
been previously heated to 212° Fahrenheit, taking care to maintain the tempe-
rature of the compound during mastication between 212° and 230° Fahrenheit,
" masticated
until it forms a plastic homogeneous compound which I term
naphthalized caoutchouc."
If it is desired to form a new series of compounds with this naphthalized
caoutchouc or with the naphthalized gutta percha I proceed as follows, viz. :-
With gutta percha I proceed by first finely dividing the impure blocks as received
from Singapore, or it may be other places, and washing in cold water to get rid of
the bark,-sand, clay, and other impurities, then boil, pass between teethed rollers,

page_text: and strain through a suitable strainer; of this strained gum I take, say, twenty
(20) pounds, and add thereto five (5) pounds only of napthaline as free as possible
from leucoline oil, and proceed exactly as hereinbefore described with caoutchouc,
and the plastic homogeneous compound thereby formed I term "masticated
naphthalized gutta percha." While the masticating process just described is going
on I dissolve in melted and, if necessary, in boiling naphthaline such materials as
are soluble therein, which I wish to combine with the above gums or either of
them, for instance, sulphur, sulphide of antimony, of arsenic, and of tin, colophony,
the resins dammar, sandarac, shellac, amber, New Zealand kauri, bitumen, or
asphaltum, all of which easily dissolve in naphthaline; or mercuric chloride,
mercuric iodide, arsenious oxide, succinic, benzoic, or oxalic acids, indigo, which
dissolve less readily, and combine any or several of these solutions (first lowering
their temperature however to 240° Fahrenheit) before adding them to the hot
naphthalized gum in the masticator. After being so added about fifteen minutes
time masticating is usually sufficient to form of the mixture a homogeneous
compound. Cresylic and carbolic acids may be added without previous solution
in naphthaline, it being simply necessary to heat them to 212° Fahrenheit before
introducing them into the masticator, which contains the hot naphthalized gum.
By varying the ingredients above specified and their proportions, a series of new
and useful naphthalized-caoutchouc and naphthalized gutta percha compounds can
be made. Materials which are insoluble in naphthaline, such as the oxides of lead,
of zinc, of tin, oxalate of lime, the sulphates of lime, of barytes, dry paper, pulp,
fibre, cotton, coloring-matters, chalk, rotten stone, required either to give solidity,
increased hardness, color or durability to the product, should first be deprived of
moisture in any suitable way, and heated to 212° Fahrenheit before they are
introduced into the masticating mass, otherwise less perfect mixture ensues.
Naphthalized caoutchouc and naphthalized gutta percha either alone or combined
with materials soluble in naphthaline, or simply mixed with material not soluble
in naphthaline, before cooling to 176° Fahrenheit, may be rolled between rolls
steam heated to about 212° Fahrenheit, or in cold rollers so as to form sheets, or
between woven or felted fibrous fabric, or over paper or sheet wire gauze or
perforated metals for harness-mounting, or introduced into an electric-wire covering
machine and pressed through a die over wires forming a seamless envelope thereon;
or pressed through an annular opening either alone to form tubing which may be
cut into bands or rings or to serve for cartridges or cases for fixed ammunition, or
pressed through an annular opening with a woven fabric or spirally turned wire, to
form a tubing impermeable to water or pressed into moulds.
In brief the various compositions of matter made by the processes herein described
may be shaped by many of the well known methods used in the manufacture of
rubber and gutta percha goods into a great variety of forms for a great variety of
uses. Having received the desired form, the compound must now be exposed to a
current of warm air at a temperature between 60° and 120° Fahrenheit from ten
to forty days to be determined by the thickness of the mass, until the persistent
odour of the naphthaline has departed. This exposure evaporates nearly all the
naphthaline leaving the caoutchouc or gutta percha and other materials intimately
combined.
It will be observed that the caoutchouc itself thus treated possesses the same
properties as the natural gum itself, unchanged in respect to elasticity, durability,
and extreme flexibility, so also with the gutta percha.
or
In order to manufacture a very superior quality of vulcanized rubber or
vulcanized gutta percha, either soft or hard, naphthalized caoutchouc
naphthalized gutta percha is combined with its required proportion of sulphur or
sulphides, in the mode above described. Then the excess of naphthaline is
evaporated by exposure to a current of warm air as directed. The combination of
gum and sulphur or of gum and sulphide is then submitted to a temperature varying
from 280° to 320° Fahrenheit for the required length of time to effect the proper
degree of vulcanization, the production of hard or soft product depending on the

page_text: proportion of sulphur, more or less, and also the higher or lower degree of
temperature, together with the greater or less length of time the compound is
exposed to heat, as is well known to the trade.
Having thus described my Invention, what I claim as new therein and desire to
secure by Letters Patent is as follows:-
First. The process of treating caoutchouc and gutta percha with melted
naphthaline, substantially as and for the purposes set forth.
Secondly. The process of masticating naphthalized caoutchouc and gutta percha,
substantially as and for the purposes set forth.
Thirdly. The process of combining with naphthalized caoutchouc or naphthalized
gutta percha materials soluble in naphthaline, substantially as and for the purpose
set forth.
Fourthly. The process of mixing with naphthalized caoutchouc or naphthalized
gutta percha.materials not soluble in naphthaline, substantially as and for the
purposes set forth.
Fifthly. As a new product naphthalized caoutchouc or naphthalized gutta percha
either alone or in combination or mixed with other materials herein mentioned, or
their equivalents, rolled, moulded, pressed, or covering or forming articles,
substantially as described and for the purposes set forth.
Sixthly. The process of removing naphthaline by spontaneous evaporation from
naphthalized caoutchouc or from naphthalized gutta percha either alone or in
combination or mixed with other materials, whether the same be in mass or has
been worked by moulding, pressing, rolling, or covering metals, substantially as
described and for the purposes set forth.
Seventhly. The process of subjecting naphthalized caoutchouc, and naphthalized
gutta percha which has been combined with sulphur or sulphides, after removing
excess of naphthaline by evaporation to the further process of hard or soft
vulcanization, substantially as and for the purposes set forth.
In witness whereof, I, the said Edgar Edmonds, have hereunto set my hand
and seal, this Fourteenth day of July, One thousand eight hundred and
eighty one.
EDGAR EDMONDS. (L.S.)