AN IMPROVED PROCESS OF UTILIZING WASTE VULCANIZED INDIA-RUBBER AND MANUFACTURING HARD RUBBER THEREFROM
Year: 1866

page_text: LETTERS PATENT to George Tomlinson Bousfield, of Loughborough Park,
Brixton, in the County of Surrey, for the Invention of "AN IMPROVED
PROCESS OF UTILIZING WASTE VULCANIZED INDIA-RUBBER AND MANUFACTURING
HARD RUBBER THEREFROM."A communication from abroad by Charles
McBurney. residing at. Roxbury, in the County of Norfolk, and State
of Massachusetts, United States of America.
COMPLETE SPECIFICATION filed by the said George Tomlinson Bousfield
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 19th June 1866, pursuant to the 9th Section of the
Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, GEORGE
TOMLINSON BOUSFIELD. of Loughborough Park, Brixton, in the County of
Surrey, do hereby declare the nature of the said Invention for "AN IMPROVED
PROCESS OF UTILIZING WASTE VULCANIZED INDIA-RUBBER AND MANUFACTURING
HARD RUBBER THEREFROM," (being a communication to me from abroad by Charles
MBurney, a person resident at Roxbury, in the County of Norfolk, and
State of Massachusetts, 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. thereof, that is to say:
The processes heretofore employed for the purpose of reusing waste vul-
canized rubber are objectionable for the reason that expensive chemicals or
Paine 8d1

page_text: the submission to steam of a high temperature or superheated steam are
necessary to said processes, either of which to a more or less extent injure
the quality of the material, and in some cases decompose it or burn it so as
to render it useless. besides the mode of treatment with high or superheated
steam is attended with danger as the rubber is liable to ignite and be des-
troyed, at the same time endangering the safety of the buildings.
The first part of the Invention has for its object to avoid the expensive
and dangerous modes of treatment referred to, and to restore to the rubber
those properties of which it has been deprived by the process of vulcanization
to which it had been previously subjected. This I accomplish by adding to
the rubber after it has been suitably comminuted a portion of some vege-
table oil which having no solvent action on the rubber simply restores to it
those propertices and that capability of being vulcanized which it possessed
in the crude state.
Waste scraps or worn out articles of vulcanized rubber, such as old boots.
shoes, car springs, &c. &c. are reduced by any suitable process to a fine
powder or dust. This is best accomplished by the ordinary friction rolls used
in grinding crude rubber and mixing rubber compound. This powder after
being placed in barrels is sprinkled very slightly with cold water to cause
it to occupy less bulk, the moisture of the water also serving to soften the
rubber, which after standing in a cool cellar or shed for a few weeks is ready
for use. To render it further suitable for use 1 put twenty pounds of the
powder, as above prepared, together with from two to four pounds of crude
rubber into a set of common friction grinding rolls and grind them thoroughly
till well combined, after which I gradually mix in from three to five pounds
of oil, such as cotton seed oil, olive oil, castor oil, palm oil, or cocoa-nut oil;
these ingredients amalgamate completely. forming a valuable compound
which can be used in the manufacture of many kinds of vulcanized rubber
goods. In order the more perfecily to prepare this compound for use 1.
submit it to a low steam heat (not exceeding 230° Fahrenheit) for from
four to ten hours. It is thus evident to anyone having a knowledge of the
art of manufacturing vulcanized rubber that the compound produced has in
no way been subjected to a decomposing or injurious process, but on the
contrary that a new and valuable product is formed which may be extensively
used in connection with other rubber compounds.
The proportions above given may be varied, but they are what I find in
practice to he gond, and I think the best.
The second part of the Invention consists in a new method of employing
waste vulcanized rubber in the manufacture of hard rubber or vulcanite,

page_text: which I will now proceed to describe. The product known as hard rubber
or vulcanite is composed chiefly of the best quality of gum (or at least more
than half its weight of the best gum), the other ingredients being sulphur,
litharge, white lead, magnesia, and lampblack in various quantities; some
of these articles may be omitted, but in all cases more than half of the compound
must be of the best (and consequently most expensive) quality of gum, hence
the compound is too expensive for application to many purposes in which it
would be very useful. if it could be obtained at a less cost than the present.
This part of the Invention has for its object the production of a compound
possessing mainly the properties of the hard rubber now in use at a much
smaller cost, and thus extending its application to many useful purposes
from which it is excluded by its present high cost. I take twenty pounds of
the compound consisting of the ingredients mixed in the manner and in the
proportions above described, four pounds best crude rubber, four to six pounds
sulphur. one or two pounds lampblack, from one quarter to one pound
calcined magnesia, and for some purposes one or more pounds litharge or
white lead. The proportions of all these articles may vary or some of them
may be omitted in some cases. These are thoroughly mixed and ground
together in the usual manner (namely. in friction roll machines, such as are
in common use in rubber factories), when after the mass is thoroughly amal-
gamated it is reduced to thin sheets of any required thickness by means of
calendering rolls (such as are in common use in rubber factories for similar
purposes), and these sheets may then be cut up, moulded, and used for any
purpose to which they may be found applicable.
To explain myself more fully I will describe the manner of covering an
iron roll or shaft of any dimensions.
The sheet is taken from the calendering machine, and while still in a
plastic state is cut into pieces of the necessary dimensions to cover the roll,
and one or more plies fitted on to produce the required thickness; the roll is
then wrapped very tightly with cotton or linen cloth. as many wrappings
being used as may be necessary to prevent its swelling during the heating or
vulcanizing process. These wrappings may be omitted if desired. and the
article to be vulcanized placed in any suitable metal flask. In this condition
it is submitted to steam heat in any suitable receptacle (usually in an iron
cylinder), steam being admitted by a pipe from a steam boiler. The duration
and temperature of the heat must be varied according to the bulk and
thickness of the articles to be heated, therefore it is impossible to give precise
rules applicable to all cases, judgment and experience being necessary: but
the heat may range from 250° to 280° Fahrenheit, and the time from three

page_text: to eight hours. Articles of an irregular form which cannot be wrapped in
cloth may be embedded in and covered with dry sand. pipe clay. or similar
materials in a suitable receptacle for the purpose of undergoing the vul-
canizing process.
I am aware that oils have been used in the manufacture of rubber, but
this has been done with an entirely different object and result. I therefore lay
no claim to such employment of fixed vegetable oils, neither do I lay claim
to any essential oils. or other solvents for the purpose of restoring waste vul-
canized rubber. for I do not use such oils or solvents, nor do I claim cither
hard rubber or the use of any of the mineral ingredients or the heating
process: but what claim as the Invention and desire to secure by Letters
Patent is,
The use of the oils mentioned in combination with waste vulcanized
rubber and crude gum or rubber as set forth, for the purpose specified.
Second claim the use of waste rubber for the production of hard rubber
as set forth.
GEO. T. BOUSFIELD. (...)