Improvements in the Manufacture of Insulating Compositions for Electric Cables.
Year: 1889

page_text: Date of Application, 31st Oct., 1889
Com'cle Specification Left, 25th Apr., 1890-Accepted, 16th Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Insulating Compositions for
Electric Cables.
GEORG EDUARD HEYL of 8 Salzufer Charlottenburg near Berlin in Germany
Chemist do hereby declare the nature of this invention to be as follows:-
In the manufacture of cables the well known isolating compositions do not admit of
a greater strength of current than about 10,000 volts at most unless caoutchouc is
employed as an isolating material. Many experiments have been made to supplement
this costly ingredient by something cheaper, but of similar efficacy to caoutchouc or
preparations of caoutchouc. The purpose of this Invention is to secure the invaluable
qualities of caoutchouc by providing an improved basis for such composition and by
incorporating with such basis caoutchouc or caoutchouc offal as hereinafter described.
It is well known that certain oils, resins, hydrocarbons wax and other substances
either singularly or in combination have been used for isolating purposes, while at the
same time experience shows that with all these materials decomposition sets in by
degrees, whereby the isolation is deadened or annihilated. The Inventor has found
that such deterioration is prevented by introducing into such isolating compositions
certain bases (metallic oxides, alkiline earths): such bases combining with the acids
present form fresh or neutral compounds, the effect of which is twofold; first, the
isolating composition is rendered extremely stable and lasting and does not shew the
deterioration through decomposition setting in, and besides the mass becomes much
closer in grain; a vast improvment is shown in the degree of isolation, such isolating
The purpose
compounds being highly indifferent to the action of the electric current.
for which the cables are to be used determines the selection and the proportioning of
the ingredients. For the purpose of combining the caoutchouc with such mixtures it
is necessary to dissolve the caoutchouc or caoutchouc offal in a suitable solvent, and
after such incorporation of the caoutchouc, an isolating composition is obtained which
For a current
mechanically and electrically bears a great similarity to caoutchone.
under 3000 volts, the caoutchouc may be incorporated into mixtures of oils, resins, &c.
without introducing the oxides. It has been proved that by this Invention, isolation
can be secured for cables up to 10,000 volts and more.
And besides the great
indifference which this compound shows to the action of the electric current, its
durability and isolation are both greatly enhanced.
1000
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Insulating Compositions for-
Electric Cables.
1, GEORG EDUARD HEYL, of Charlottenburg near Berlin, in the Kingdom of
Prussia, German Empire, Chemist, 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 :-
The materials heretofore employed for insulating the wires and cables of electric
circuits such as oil, resin, wax, were all exposed to decomposition and hence not only
lost their insulating capacity in the course of time but also led to the corrosion of the
protecting sheath of lead and even of the conducting wire.
Moreover the use of these compounds is very limited owing to their fusing or
burning as soon as the electric current reaches a high degree of tension. Caoutchouc

page_text: and guttapercha are the only materials which do not possess these defects but as these
are very costly they can only be resorted to when all other materials have failed.
The compound hereinafter described possesses as an insulating material all the
qualities of caoutchouc while it can be produced at a far cheaper rate than the
latter.
This compound is generated by the saponification of different oils, resins and hydro-
carbons by different bases produced at a very high degree of heat.
The principles which guided the inventor in his discovery of a new compound have
been the following.
1. All parts of the compound inust penetrate into the fibres of the material spun
woven around the wire.
2. The compound must be of such a nature as not to corrode in time the conducting
wire and the protecting sheath of lead and hence it should not contain either free
acids or alcalis.
3. The material, though possessing a very great density and solidity must yet be
ductile enough not to break when the cable is bent.
4. The material must have a very high-point of fusion lest the circuit should become
imperfect, during the passage of a current of high tension which will heat the wire
and the coating intensly.
5. The material should not be liable to be decomposed so as to withstand the action
of water even when the outer protecting sheath is damaged.
We shall now see how all these conditions are carried out in my new compound.
1. IMPREGNATION OF THE FIBRES.
In order to impregnate the threads around the cable the compound should be used
in a liquid state. The compounds hitherto employed for the same purpose contained
various admixtures of oils, resin, wax and the like which did not impregnate the fibres
properly. Water was the most dangerous of these admixtures. It was impossible to
expell the latter from the materials heretofore employed, as the latter burn or become
decomposed at a degree of heat at which the vaporisation of the water takes place,
My compound however requiring a heat of 400-450° cels. for its preparation does
not contain any water and as experience has shown, will even absorb during
impregnation the water from the tissue woven around the wire.
2. PREVENTION OF CORROSION.
The copper wire and the protecting sheath of lead cannot be corroded by my
compound as the acids contained therein and the quantity of which has been
ascertamed by chemical analysis have been neutralized by the various bases. This
method of neutralizing the acids, through generally known, has never hitherto
produced satisfactory results, as bases in excess will enter into combination with the
water absorbed by the compound itself or by the fibres of the cover, and thus form
alkaline hydrates which are more dangerous than acids.
As above mentioned the quantity of acids in my compound has been determined by
an exact chemical analysis, in such a manner that the necessary quantity of bases can
be mixed thereto without a residuum thereof being left. Moreover not only one but
several bases have been used for mixing with oil, resin, wax, as experiments have
shown, that the different soaps produced by these mixtures vary as regards their
insulating power.
3. CONSISTENCE.
The materials saponified in different manners would not be immediately fit for use
in the manufacture of cables on account of their great density, solidity, and their high
point of fusion unless they are mixed with some ingredients which increase the
consistency of the material.
For this purpose I make use of bleached oxidized linseed-oil as it has been found

page_text: by experiments that owing to the oxydation of linseed-oil or wax not only will the
insulating power of the coating be increased but the material will also be completely
freed from water. Moreover the compound preserves its qualities even at a very low
temperature in such a manner that the insulated cable may be bent in every direction
without there being any risk of the coating breaking.
The compound is decomposed neither in water nor in air, which is theoretically
proved by the composition of the material and by its behaviour the cables impregnated
with compounds such as hitherto known work irregularly after having been used
for some length of time in consequence of the decomposition of the insulating
compound.
My compound however being free from water and not liable to absorb any will
never be decomposed and will thus enable the cable to work in a uniform manner.
The compound produced in the manner aforesaid will be found to answer the
purpose as well as caoutchouc and other similar materials as regards insulating
capacity, elasticity and solidity and will be a very cheap substitute for such
materials.
The compound is prepared as follows:-
I take equal parts of olive oil, poppy oil and linseed oil or 1 part of olive oil,
2 parts of linseed oil and 3 parts of poppy oil and mix them well together. These
oils should be quite free from water. Of this mixture I take 1920 parts and heat it
to a temperature of about 400 degrees in the manner and apparatus hereinafter
referred to and I add to the mass 68 parts of hydrate or carbonate of lime or an
equivalent quantity of litharge or oxide of tin, then 325 parts of nitric acid and
500 parts of water are incorporated therewith the temperature being maintained
at 400° C. The above will form compound I.
I mix part of white French resin and 2 or 3 parts (according to consistence) of
Canadian balsain, both free from water and thus form compound II.
By mixing from 3 to 600 parts of the latter (according to point of fusion) with
compound I obtain my improved compound for insulating electric cables.
I may also incorporate with my improved compound a quantity of from 10
10 25% of caoutchouc, but this although an improvement is not absolutely
indispensable. The compound is manufactured as follows reference being made to the
accompanying drawing in which Fig. 1 is a schematic view of my improved
apparatus.
The alembic A is first filled with the above mentioned oils used for the preparation
of the compound viz., olive oil, poppy oil and linseed oil which are previously
subjected to a thorough oxidation process in such a manner that the oil is gradually
heated and brought by constant beating in contact with the air. The mixture is then
heated to a temperature of approaching 400° C. by means of a paraffine bath Eraised
to the same temperature upon the open fire C. This treatment causes all the liquid
component parts such as water, liquid acids and the like to be converted into vapors
which are being continuously exhausted by an air and water pump Band subjected to
the action of water supplied from the water tank D through the pipe and which
absorbs the respective gases.
Another advantage of this process is that the manufacture of the compound is
throughout devoid of smell.
When this process is completed the various resins which
have been previously subjected to a similar treatment in an apparatus of similar
construction is added to the above mixture now free of water. The resins are freed
from the acids which act so injuriously upon the cables by the removal of all the
liquid component parts therefrom.
As there still remain some combined acids in the mixture of oils and resins
prepared in the manner before described this mixture is finally treated by means of
suitable bores.

page_text: The acid gases, vapors &c. formed during the saponification are exhausted from the
alembic by the air pump B.
The saponification has moreover for its object to raise the point of fusion of the
various component parts of the compound whereby the advantages before mentioned
with reference to electric action are fully seared.
Several bases such as hydrate of lime and of baryta may be used for the above
mentioned purpose as well as litharge, sodaic lime and oxide of tin, as the saponifications
differ in their electrical and mechanical properties and hence a different combination
of the soaps is necessary.
The consistence of the compound
relative proportion of the oils and resins.
determined before the saponification by the
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 is
1. A method of manufacturing insulating coatings for the wires and cables of
electric circuits consisting in the saponification of the different oils, resins, and hydro-
carbons mixed in the given proportions and heated in the manner shewn by means of
different hases produced at an intense heat substantially as hereinbefore described and
shewn and for the purpose set forth.
2. A method of manufacturing insulating coatings for wires and cables of electric
circuits consisting in saponifying different oils, resins and hydro-carbons with different
bases, obtained at an intense heat and in mixing caoutchouc with this solution
substantially as and for the purpose set forth.
13016 The JNTRY 48V AT 44 137′1| PAWIT
GEORGE EDUARD HEYL.
By Rayner & Cassell,.
37, Chancery Lane, London, W.C., Agents for the Applicant.