Improvements in Processes for Extracting Caoutchouc.
Year: 1898

page_text: Date of Application, 15th July, 1898-Accepted, 8th Oct., 1898
COMPLETE SPECIFICATION.
Improvements in Processes for Extracting Caoutchouc.
I, OTTO ZURCHER, of Kingston, Isle of Jamaica, Merchant, 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:-
This invention relates to an improved process for the extraction of caoutchouc
and in the utilization for this purpose, of musa-plants (as for instance bananas,
pisang, etc.) whereby it is possible not only to obtain a natural caoutchouc of
superior quality but at the same time to effect the utilization of the said musa-
plants to a much greater extent than heretofore; said utilization hitherto having
consisted almost entirely in the sale of minimal quantities of the ripe fruit of said
plants.
This more complete utilization of the musa-plants, or more precisely, the employ-
ment of musa-plants for the purpose in question is an important feature of the
invention and will be hereinafter more fully referred to. The process is based
upon the discovery that at a certain stage of ripeness, from the peel or skin surround-
ing the banana fruit proper, as also from the leaves encompassing the fruit (when
incisions are made in the said peel and leaves, at suitable distances apart), a
milk-like liquid is emitted, from which a considerable quantity of caoutchouc
can be obtained, said caoutchouc being identical with and equal to the caoutchoue
obtained from other caoutchouc plants.
As regards the most suitable stage of ripeness which the above mentioned musa-
plants must have reached in order to obtain the best results as regards the caout-
chouc extraction, it is to be remarked, that the appropriate time for gathering
the fruit must vary within somewhat considerable limits, for the reason, that the
most suitable time of harvest must be to a large extent dependent upon and
influenced by various circumstances, such as for instance, the kind of ground,
in which the fruit is planted, the general position of the same, the ordinary
temperature during the ripening of the fruit, the height of the plantation, the
special class and kind of plant selected and the age of the plants, each of these
matters have an influence upon the period when the maximum yield would be
obtainable from these caoutchouc plants. It can, however, be assumed as an
average, that the most suitable time to cut the plants would be approximately the
middle of the ripening period.
I will now proceed to describe my process for obtaining caoutchouc from musa
plants, more especially bananas, as follows:
The gathered fruit before being cut, is subjected to a powerful water-jet for
the purpose of removing loose leaves and other impurities, the fruit is then cut
from the stem in such manner, that the end of the stem remains upon the fruit.
The pointed ends of the stem are now removed from the fruit and after the
pointed portion at the opposite end of the fruits is separated, the said stems, the
leaves surrounding the fruit, and the said pointed portions of the fruit, are on the
one hand separately treated and the remaining portions of the fruit, on the other
hand also separately treated.

page_text: Referring again more especially to the most suitable time of harvest, I will
remark, that the liquid obtained from fruit gathered in the rainy season will,
(when the fruit is cut) flow from the same, as it were of itself without any
difficulty. Whatever valuable liquid contents may still remain can be extracted
by treating the fruit with oil of turpentine or any other suitable solvent (if
necessary in rarefied air) or the remaining liquid can be extracted by the employ-
ment of centrifugal machines.
As regards the use of centrifugal machines in the case of fruit gathered in
the dry season and containing a caoutchouc sap of a higher percentage, I prefer-
ably place the same in a longitudinal direction within a centrifugal machine, in
such manner, that the fruit is placed radially to the middle of the centrifugal
machine with regard to its length. In this manner almost the entire sap contents
can be extracted with ease by the operation of said centrifugal machine, and
whatever may still remain can be recovered by treating the fruit taken from the
centrifugal machine, with the solvent described in the previous paragraph.
..It is not desirable to employ pressure for the extraction of the caoutchouc liquid,
as in such a case the liquid would become mixed with the fruit juice in such
manner that a separation of the latter from the caoutchouc liquid would be im-
possible, and it should also be remarked, that in such cases the before mentioned
extraction by means of solutions could not be applied.
+
The cutting of the fruit and parts of the plant containing caoutchouc sap, I
prefer to effect in a cross-direction to the sap channels.
The fruit ends, the leaves and the fruit stems are treated in the following
manner:
Said fruit stems are first subjected to a crushing pressure in order to open the
caoutchouc channels and then placed in a centrifugal machine together with the
ends and the said leaves, these latter having been cut into small pieces. (If
necessary this mixture is first treated with a suitable dissolving liquid, such as
oil of turpentine, before being placed within the centrifugal machine.)
From the liquid so obtained the caoutchouc will of itself separate, in the form
of a thick cream, as soon, as the said liquid is allowed to stand for some time, and
it should be remarked, that not only is the quantity, but also the quality of the
obtained caoutchouc influenced by the centrifugal machine process and that there-
fore it is especially desirable to subject the milky sap to the action of a centrifugal
machine, immediately after said sap has been extracted, whereby without any
further treatment the caoutchouc would separate as indicated in the form of a
white thick cream, in a similar manner to the caoutchouc sap obtained from
other plants, and would coagulate and manifest the usual chemical and physical
qualities of the same. At this point it should be mentioned, that the treating
in a centrifugal machine of the fresh caoutchouc liquid is not only applicable
to the liquid of banana-plants, such treatment (by centrifugal machines) being
also applicable for the saps of other caoutchouc-plants, and I claim that hereby
considerably better and hitherto unattainable results would be possible than
heretofore.
It is recognised as a great disadvantage that the raw caoutchouc introduced
into the market contains many impurities and foreign substances, said substances
not only considerably increasing the difficulty of the further treatment of such
caoutchouc, but also affecting the cost for the apparent reason that same are paid
for as pure caoutchouc although they are only disturbing and usually injurious
ballast. The most objectionable foreign substances met with in the manufacture
of caoutchouc, apart from mechanical impurities, such as stones, leaves, sand,
twigs of trees, etc. are the resins, the removal of which cause considerable difficulty
in the manufacture, and are often only incompletely removed, said incomplete
removal of which in many cases resulting in the caoutchouc becoming practically
worthless.
These impurities, however, both mechanical as well as chemical are all quickly
removed in the most simply manner by the above mentioned treatment of the

page_text: fresh caoutchouc-liquid in a centrifugal machine, so that my centrifugal process
for obtaining caoutchouc is of great importance when applied also for treating
plants from which caoutchouc has hitherto been obtained.
Besides this technical value of the process herein before described, my invention
confers another advantage from an agricultural point of view. This will be
seen from the fact, that it is now possible to obtain caoutchouc from a cultivated
plant, whilst hitherto said caoutchouc was only obtained from more or less wild
plants occupying a long time in growth, and moreover, the extinction of these
plants might reasonably be anticipated within certain time limits, and thus imperil
the manufacture of caoutchouc.
t
In place therefore of what may be regarded as wild plants (from which hitherto
caoutchouc has been obtained) it is now rendered possible to cultivate caoutchouc
plants in a rational manner and to so proportionate as it were the size of the
plantations, or, in other words, the total production that the amount of plants
placed in cultivation for this purpose, or more precisely, the amount of caoutchouc
obtained would keep place with the demand which it may be safely assumed would
steadily increase.
Moreover this proportioning
facilitated by taking into consideration the fact
that by my improved process caoutchouc is obtained from plants which have a
life of 10-40 years.
*
I may here draw attention to the fact, that the fruit proper of the musa-
plants" (after being used for the purpose of obtaining caoutchouc) is adapted
to another and important use which consists in the said fruit proper being ground
and dried, and a flour produced from the same, which is found to contain a high
percentage of nutritive substances and having a pleasant taste, also being suitable
both for baking and cooking purposes, or, this said fruit proper (separated from
the skin) is capable by special treatment for employment as a food for cattle.
My invention therefore affords a fourfold advantage in the cultivation of the
banana apart from the fact that a plantation owner can now protect himself from
great and previously unavoidable losses occasioned by the decomposition of the
by far larger portion of the fruit that it was not possible to utilize.
This will be apparent from the fact that up to now about 50% of the entire
production of bananas were left to rot, for the reason that the dealers only
accepted fruit of certain dimensions or suitable weight, and at a certain stage
of ripeness.
The remaining fruit was absolutely useless.
In conclusion I claim that by my invention and the employment of my improved
process, the entire and immense yearly crops of musa-plants and the like, and
bananas in particular, can be utilized to the fullest extent, apart from any question
as to the size, weight, or ripeness of the said fruit.
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:
1. An improved method of obtaining caoutchouc, consisting in extracting the
sap from musa-plants, bananas, pisang and the like, more especially in a half
ripe state and letting the cream, i.e. the caoutchouc, separate from the said sap,
substantially as described.
2. An improved process for extracting caoutchouc from musa-plants more
especially in a half ripe state consisting in cutting the fruit and other parts of the
plant containing caoutchouc sap in a cross-direction to the sap-channels, and
after allowing the chief portion of the sap to flow of itself from said channels,
subsequently extracting the remainder by centrifugal action or by the employ-
ment of a chemical solution, the latter extraction being effected in a vacuum
or not, substantially as described.
3. An improved process of extracting caoutchouc from musa-plants such as
bananas, pisang and the like, consisting in cutting such parts of the plants (con-

page_text: taining caoutchouc) in a cross-direction to the sap channels and extracting the
caoutchouc therein contained, by subjecting the said parts to centrifugal action,
these parts being placed in the centrifugal machine in a radial direction to the
centre of said machine, substantially as described.
4. The process of directly extracting caoutchouc from musa- and other caout-
chouc-containing plants, consisting in subjecting the prepared plants, or suitable
portions of such plants, to centrifugal action and in also subjecting the sap to
centrifugal action, whereby an entire separation of the caoutchouc from its
mechanical and chemical impurities such as resin and the like is effected sub-
stantially as described.
5. An improved process of extracting caoutchouc from the leaves which sur-
round the banana fruit as well as from the fruit stems, and the like, consisting
in cutting these portions of the green plant in a cross-direction to the sap-channels
and after treatment with chemical solution, subjecting the same to centrifugal
action, substantially as described.
6. An improved method of obtaining caoutchouc, in which the plants containing
caoutchouc sap, are impregnated with a chemical solvent (of caoutchouc) before
subjecting the same to centrifugal action, substantially as described.
Datod thi
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buy 30.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.