Process of Impregnating Fibrous, Porous, and Cellular Bodies, Working the Impregnating Material or Compound, and the New Article resulting therefrom.
Year: 1890

page_text: Date of Application, 11th July, 1890
Complete Specification Left, 7th Apr., 1891-Accepted, 16th May. 1891
PROVISIONAL SPECIFICATION.
Process of Impregnating Fibrous, Porous, and Cellular Bodies,
Working the Impregnating Material or Compound, and the New
Article resulting therefrom.
I, BENJAMIN JOSEPH BARNARD MILLS of 23 Southampton Buildings in the
County of Middlesex, Patent Agent, do hereby declare the nature of this inven-
tion, a communication to me from abroad by Edwin Trueman Greenfield, Manu-
facturer, and Junius Nagel, Chemist, both of the City, County and State of New
York in the United States of America, to be as follows:-
This invention relates to a process, the working of the process, and the new
article of manufacture which results from that process. The process relates to the
impregnation of a fibrous, porous, or cellular body with a bituminous material or
compound, and the object of the process is to thoroughly combine the fibrous, porous
or cellular bodies with the impregnating material or compound, to the end that a
homogeneous article may result.
The new article of manufacture which it is specially desired to claim is made up
in the form of a tube. This tube is formed by combining a base of fibrous, porous
or cellular material such as sheathing paper, asbestos paper, or felt paper with a
filling of a bituminous material or compound such as black petroleum pitch. When
completed a coalescing of the bituminous substance and the base of the tube. has
taken place and the result is, a tube homogeneous throughout.
Our process is based on the discovery that in order to thoroughly impregnate a
fibrous, porous or cellular body with a bituminous material or compound, such as
black petroleum pitch, it is necessary to subject the body undergoing treatment to
alternate immersions and rests in the bath of impregnating material, preferably the
rests taking place in a cooler medium than the impregnating material. Experience
has shown that with fibrous, porous or cellular bodies of organic origin, it is
absolutely necessary in order to effect a thorough impregnation thereof, with a
bituminous material or compound, that the compound be maintained in a liquid
condition by high heat, so that it runs freely like water and that the said materials
be treated by alternate immersions and rests as above stated. If the impregnating
material or compound is maintained at a high heat, sufficiently so that it will run
free like water, there is danger of charring organic fibrous, porous, or cellular bodies
if they are allowed to remain in the impregnating compound, but by subjecting the
same to an immersion for a brief period, then allowing a rest and continuing the
alternate immersions and rests until there is a thorough impregnation, the danger
of charring is avoided.
When an inorganic, fibrous, porous or cellular body such as asbestos paper, is to
be treated with a bituminous, impregnating compound, then although there is no
danger of charring, the feature of alternate immersions and rests seems to be
beneficial because one of its actions seems to be to allow the impregnation material
taken up by any immersion to congeal somewhat and on the succeeding immersion
the high heat remelts it and drives it further into the body undergoing treatment,
so that a more thorough coalescing takes place than would occur if the body was
left in the impregnating material once, for a considerable time. It is found that a
heat of about 350° Fahrenheit, will maintain petroleum pitch in the proper working
liquid state, but it may be worked at a temperature as low as 260° Fahrenheit but
the process then is slower.
At either of these heats if an organic body was permitted to remain for any
length of time in the compound it would be charred and thereby rendered useless.
Petroleum pitch being a high boiling hydro-carbon, under the action of the hich

page_text: heat employed in carrying out our process gradually gives up its volatile ingredients
so that the residuum becomes very much thickened and if the process were carried
on for a considerable length of time would finally become so thick as to be very
difficult of working. By adding or mixing with the black petroleum pitch, from
time to time, a quantity of lower boiling hydrocarbon, for instance, such as tbat
which is known as "yellow tailings" an equivalent for the volatile matter driven off
from the black petroleum pitch is supplied and the impregnating material rendered
easily workable.
In carrying out the process in order to produce the new article of manufacture
when the same is in the form of a tube, it has been found that for a tube of sheathing
paper, one-quarter inch inside diameter with a thickness of wall of one-sixteenth
inch, that the following periods of immersions and rests produce good results. For
the first immersion, one quarter of a minute with a rest of two minutes. For the
second immersion, one-half of a minute with a rest of one and three-quarter minutes.
For a third immersion three quarters of a minute with a rest of one and a half
minutes. For the fourth immersion, one minute with a rest of one and one-quarter
minutes, and for the fifth immersion, one and one-quarter minutes, when the tube is
finished and may be taken out and allowed to cool.
Dated July 11th 1890.
B. J. B. MILLS.
}
By Harris & Mills,
23, Southampton Buildings, London, Agents.
COMPLETE SPECIFICATION.
Process of Impregnating Fibrous, Porous, and Cellular Bodies,
Working the Impregnating Material or Compound, and the New
Article resulting therefrom.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23 Southampton Buildings, in the
County of Middlesex, Patent Agent, do hereby declare the nature of this inven-
tion, à communication to me from abroad by Edwin Trueman Greenfield Manu-
facturer and Junius Nagel, Chemist, both of the City, County and State of New
York in the United States of America, 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 a process, the working of the process, and the new article
of manufacture which results from that process.
The process relates to the impregnation of a fibrous, porous, or cellular body with
a bituminous material or compound, and the object of the process is to thoroughly
combine the fibrous, porous or cellular body with the impregnating material or
compound, to the end that a homogeneous article may result.
In explanation of this process I may state that heretofore the treatment of
organic bodies with a water-proofing material or compound in a liquid state, has
been effected either by a surface coating applied to the material by a brush or
similar method, or by immersing the body in the compound.
The latter method of treating such bodies with such material or compound, when
the same was maintained in a liquid state below a temperature which would char
them was to immerse the bodies in the material or compound for an indefinite period.
This method, however, did not result in thoroughly impregnating the organic body
with the material or compound, as the temperature at which such material or
compound was maintained was too low to properly liquify the same so that it would
penetrate easily.
If the compound is maintained at a temperature high enough to properly liquify
it, then great care is necessary to avoid charring or carbonizing the organic body.
By immersing the organic body in the liquid material or compound once for a brief

page_text: period, the immersion being quickly effected, charring is avoided, but the product
resulting is not thoroughly impregnated.
In carrying out this process a compound may be employed which is maintained
at a high heat, so that it will be thoroughly liquified, and which would, if the
organic body to be treated were permitted to remain for any length of time in the
molten compound be charred or carbonized-and thereby rendered valueless.
The main features of this process are founded on the discovery new to the
inventors that to thoroughly impregnate organic fibrous, porous or cellular bodies
with a water proofing material or similar compound, alternate immersions and rests
in a bath of the impregnating material or compound maintained in a liquid condition
by high heat avoids charring or carbonization of the said bodies while effecting a
thorough impregnation of the body throughout its mass with the material or
compound.
I will describe the process as carried out using petroleum pitch as the water-
proofing material. This material in order to effectively impregnate an organic body
is maintained in a liquid state by a heat of about 350 degrees F., constantly, but it
may be worked at a temperature as low as 260 degrees F. but the process then is
slower. At either of these heats if the organic bodies were permitted to remain
for any length of time in the compound, they would be charred and thereby rendered
useless.
When the bodies to be treated have dried so that as much moisture as possible is
expelled from them, they are immersed for a very short period in the impregnating
compound. They are then raised and held out of said compound preferably for a
period considerably longer than the duration of the immersion. Preferably the
bodies undergoing treatment are raised above the impregnating compound into a
cooler medium where the compound will become to some extent congealed. This
first short immersion and comparatively long rest permits the impregnating liquid
to penetrate into the pores or fibres of the body undergoing treatment, and to some
extent prepares it to remain a longer time in the liquid on the next immersion.
The bodies are again immersed for a longer period than the first immersion and aro
then withdrawn from the liquid and held out of the same for a shorter period than
that succeeding the first immersion. This second immersion effects a further
penetration of the impregnating material into the body undergoing treatment and
further prepares it, so that on the next immersion it will without injury to it staud
a still longer immersion than the second immersion, and so on for each succeeding
immersion until the bodies are thoroughly impregnated, the rests between immersions
being preferably shorter as the immersions are longer.
The process of working the impregnating material or compound is as follows:-
Petroleum pitch heretofore mentioned as a water-proofing material is a high boiling
hydro-carbon obtained in the distillation of coal oil as a bituminous black residuum.
The boiling point of this petroleum pitch varies but is generally about 900 degrees F.
When, as in the process described above, high heat is employed, the petroleum
pitch gradually gives up its volatile ingredients, so that the residuum becomes very
much thickened, and if the process were carried on for a considerable length of
time would finally become so thick as to be very difficult of working.
By adding or mixing with the black petroleum pitch from time to time a quantity
of a lower boiling hydro-carbon, as, for instance such as what is known as "yellow
tailings" an equivalent for the volatile matter driven off from the black petroleum
pitch is supplied and the impregnating material rendered easily workable. This
"yellow tailings" is a yellow brownish viscous residuum obtained in refining
paraffine oil and has a variable boiling point but most generally found about 600° F.
In practice it has been found that with a kettle started with 4000 pounds of
petroleum pitch alone, using about 250 pounds daily, that in about three days the
material became thick and practically unworkable. By, however, supplying to the
kettle enough petroleum pitch and "yellow tailings" to bring the weight of its
contents to about the original 4000 pounds, in the proportion of three of petroleum
pitch to one of "yellow tailings" the tendency to thicken was overcome."

page_text: "
While petroleum pitch has been described as the high boiling hydro-carbon and
yellow tailings " as the preferable lower boiling hydro-carbon to be used
therewith to effect a useful result in carrying out these processes, I am aware that
other compounds may be used, as for instance instead of the petroleum pitch what
is known as "native asphaltum may be used together with a lower boiling
hydro-carbon, and instead of
yellow tailings may be used paraffine oil or
equivalent hydro-carbon.
وو
"
The new article of manufacture which I specially desire to claim is in the form
of a tube made up by combining a base of two or more thicknesses of a fibrous,
porous or cellular material, such as sheathing paper, asbestos paper or felt paper,
with a filling of a bituminous material or compound such as black petroleum pitch.
When completed by the alternate dipping process herein described, a coalescing of
the bituminous filling substance and the base of the tube has taken place and the
result is a tube homogeneous throughout, possessing high insulating properties,
strong durable, not affected by hygrometric or ordinary thermal changes and of
comparatively low first cost.
The advantages of a tube possessing insulating qualities as a conduit for
electrical conductors have long been recognised and attempts have been made to
produce such a tube which would be economical, durable, strong and water and acid
proof, but, so far as we are aware, without any pronounced success.
Among other kinds of tubes used have been those formed by highly compressing
paper pulp into the desired form and depending upon the compressed pulp only for
insulation; another and the most common kind for economical tubes have been
tubes formed of layers of paper coated with a bituminous compound, as pitch,
which served both to retain the tube in proper form and add to its insulating
properties.
This latter tube was not homogeneous and proved objectionable in use as did the
first mentioned kind, notwithstanding any advantages they might possess from a
standpoint of economy in first cost, in that among other things they were affected
by dampness to such a degree as to materially lessen their durability and insulating
properties.
It has also been proposed to use tubes of a bituminous compound combined with
a material added in a pulp form, the tube being made by squirting the mixture
through a die. This form of tube is difficult of manufacture and therefore
expensive, and the tubes produced were likely to be irregular in composition, besides
it being impossible to make them of considerable length.
The tube resulting from practicing our process is a compound tube and is
distinguishable from tubing heretofore treated with a bituminous compound by its
greater density throughout its mass, which will be made apparent by cutting,
whereby it will be seen that the tube has lost almost wholly the physical structure
of its component materials and assumes new characteristics possessed by none of
these materials separately.
The brittle character of the bituminous material or compound, which would be a
serious objection to its use alone for a tube, is supplemented by the fibrous
character of the formed base, which imparts the desirable strength, and the
hygroscopic character of the formed base is supplemented by the bituminous
compound which effectually obviates all tendency in the compound tube to absorb
moisture.
The fibrous porous material used as a base may be either of a vegetable nature,
as sheathing paper, or of an animal nature, as felt paper, or of a mineral nature, as
asbestos.
When made of animal or vegetable fibre the base is first formed in the desired
shape, preferably for large sizes by serving longitudinal layers thereof one over the
other each layer breaking joint with its next inner layer and for small sizes by a
longitudinal core with a spiral wrap or wrappings. When asbestos is used as the
base the tube is first formed in any desirable manner, as for instance, by wrapping
a sheet of what is known as asbestos paper in concentric layers on a mandrel.

page_text: The material which it is preferred to use as the base for the tubes of large size
is that known as felt paper, which possesses an exceedingly open, porous structure
well adapted for combining throughout its mass with the filling material or
compound.
For smaller sizes of tubing it is preferred to make use as a base of what is known
as sheathing paper which possesses a somewhat less open or porous structure than
the felt paper but is yet sufficiently open to combine with a large quantity of the
filling material or compound throughout its mass.
The large size tubing is especially adapted for use as a conduit in a system of.
underground distribution where difficulties from moisture are most to be appre-
hended, while the small tubing is especially adapted for use as a conduit for
interior systems of distribution where danger from moisture is less great and where,
therefore, the small sizes do not require the presence of so much compound as do
the conduits for underground work.
The paper base having been shaped from the required quality of animal or
vegetable porous material has the compound combined with it by the process of
alternate dipping herein before set forth.
As before stated of organic bodies, if the paper bases were left in the highly
heated impregnating material for any length of time they would become charred
and thereby made worthless.
These bases are therefore subjected to alternate immersions and rests as stated
generally for organic bodies when the base is of an inorganic fibrous, porous or
cellular body, such as asbestos paper the feature of alternate immersions and rests
in the operation of the process is then still employed, as the same seems to be
beneficial, one of its actions being, as far as has been observed, to allow the
impregnating material to congeal somewhat and on the succeeding immersion the
high heat remelts it and drives it further into the body undergoing treatment, so
that a more thorough coalescing takes place than if the inorganic base was left n
the impregnating material once for a considerable time.
For a base one inch in internal diameter with a wall of three-eighths inch
thickness made of felt paper it is found that the following periods of immersions
and rests, using black petroleum pitch as the filler, will produce a compound tube
homogeneous in physical characteristics;
0 A twelve inch length of felt base of the diameter and thickness of wall above
stated will weigh four ounces; when combined with the filler by the process above
set out it will weigh twelve ounces without having increased perceptibly in
dimensions. Such a compound tube is well adapted for underground conduits.
For a base of sheathing paper, one-quarter inch inside diameter with a thickness

page_text: of wall of one-sixteenth inch, using black petroleum pitch as a filler we find that the
following periods of immersions and rests will produce a homogeneous tube:
No. of immersions
Immersions minutes.
Rests, minutes.
A twelve inch length of base made of sheathing paper having an internal
diameter of three-eighths inch and a wall of one-sixteenth of an inch in thickness
will weigh one and three quarter ounces; when combined wih the filler by the
process above set forth it will weigh two and three quarter ounces without having
increased perceptibly in dimensions. Such a tube is well adapted as a conduit for
interior wiring.
When a mineral fibrous material is used as a base the same may have the filler
combined with it without employing the process of alternate immersions and rests
above set forth, as there is no danger of charring the mineral fibre, although even
with mineral fibre it is preferred to employ this process for combining the base
and filler.
So far as the inventors are able to observe the action which takes place in treating
fibrous, porous or cellular bodies as above described, is as follows:
The first rapid immersion results in a penetration of the impregnating material
to some extent and serves to drive out moisture and air; the subsequent rest, when
effected in a cooler medium than the molten compound in the kettle, results in a
change in the consistency of the impregnating compound and serves to prepare the
bodies for the next immersion by exposing to the action of the impregnating
material a compound, somewhat congealed which forms a superior heat non-
conducting envelope or jacket, thereby protecting the organic fibrous body from
charring to a considerable extent. The subsequent immersions and rests in their
action are similar to the first as they have been observed each immersion serving
to drive in the compound taken up by the previous one. The result is a body
which is penetrated throughout its mass by the impregnating compound and not
simply provided with successive coatings by the alternate immersions and rests.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. The process of treating an organic fibrous, porous or cellular body, which
consists in impregnating it with a suitable material or compound maintained in a
liquid condition by heat by alternate immersions and rests, substantially as set forth.
2. The process of treating a fibrous, porous, or cellular body, which consists in
impregnating it with a suitable material or compound maintained in a liquid
condition by heat by alternate immersions and rests, substantially as set forth.
3. The process of treating an organic fibrous, porous, or cellular body, which
consists in impregnating it with a suitable material or compound maintained in a
liquid condition by heat by alternate immersions and rests, the time of immersions
and rests being varied in relation to one another, substantally as set forth.
4. The process of treating an organic fibrous, porous or cellular body, which
consists in impregnating it with a suitable material or compound maintained in a
liquid condition by heat by alternate immersions and rests, the rests being effected
in a medium cooler than the impregnating compound, substantially as set forth.
5. The process of working high boiling hydro-carbons for impregnating fibrous,
porous or cellular bodies which consists in maintaining the same in a liquid condition
by heat, and adding thereto from time to time a lower boiling hydro-carbon or
equivalent to supply the volatile matters evaporated, substantially as set forth.

page_text: 6. As a new article of manufacture, a compound tube comprising a formed base of
two or more thicknesses of a porous, fibrous material, and a filling of bituminous
material or compound combined with said formed base throughout its mass,
substantially as specified.
7. As a new article of manufacture a compound tube having a formed base of
two or more thicknesses of paper, and a filling of a bituminous compound combined
with said base throughout its mass, substantially as specified.
8. As a new article of manufacture, a compound tube having a formed base of
two or more thicknesses of paper, and a filling of a bituminous compound combined
with said base throughout its mass, when made by the process herein set forth.
1 1001
B. J. B. MILLS.
By Harris & Mills,
23, Southampton Buildings, London, Agents.