Improvements in Devulcanizing Indiarubber.
Year: 1893

page_text: Date of Application, 13th Oct., 1893
Complete Specification Left, 18th July, 1894-Accepted, 18th Aug., 1894
PROVISIONAL SPECIFICATION.
Improvements in Devulcanizing Indiarubber.
I, Maximilien Gerber, Chemist, of Clermont-Ferrand, in the Republic of
France, do hereby declare the nature of this invention to be as follows:-
According to this invention vulcanized india-rubber is heated with a metal
having an affinity for sulphur and a solvent having no chemical action either on the
gum or the metal.
The process may be conducted either in an open or a closed vessel according to
the boiling point of the solvent and the nature of the metal employed.
The resulting solution of the gum is separated from the sulphide of the metal
and other matters by decantation or otherwise and the gum may be obtained by
evaporating the solvent or the solution may be used for waterproofing or
otherwise.
Amongst the metals which may be employed are :-Iron, copper, tin, lead, zinc,
mercury or their alloys, amalgams or mixtures of them, or mixtures with other
metals such as bismuth, sodium, potassium, or with metalloids, such as antimony,
arsenic or small quantities of sulphur or phosphorus for rendering the metal or
alloy pulverable or fusible. It is advisable that the metal be finely divided or else
that it be fusible at the temperature of reaction in order to offer as much active
surface as possible.
The following solvents may be used:-Hydrocarbons such as benzene and its
homologues, toluene, the xylenes, naphthalene, or their mixtures, more or less pure,
heavy or light benzoles, crude creosote of tar, the essences or oils of schist,
petroleum, naphtha, neutral organic compounds, such as chloroform, carbon
disulphide, carbon tetrachloride, ether, essence of terebenthene or other analogous
solvents of india-rubber. These may be mixed or not with small quantities of other
compounds such as ethyl or methyl alcohol.
The following examples may be given of the process :—
Either tin precipitated by zinc from a solution of its chloride, or sheet tin divided
by passing it through rollers at the same time as the india rubber waste &c. may
be used.
The materials are heated (a pressure of 3 to 4 atmospheres being employed in
the double bottom, corresponding to a temperature of 139 to 144° C.) for about
eight hours, the agitator being kept in motion. The inside pressure attains
4 to 5 atmospheres.
After cooling, the contents of the vessel are placed in a receiver and left at rest
for 24 hours and are then decanted.

page_text: The mixture is heated for eight hours to 130, 135° agitating continuously. The
product is diluted with 15 litres of light petroleum to render it more fluid, allowed
to settle, decanted and the operation finished as before.
Of course the proportions named in these examples are not obligatory and may
vary within very extended limits as may also the duration of the operation and the
temperature employed.
Dated this Tenth day of October 1902
COMPLETE SPECIFICATION.
Improvements in Devulcanizing Indiarubber.
I, MAXIMILIEN GERBER, Chemist, of Clermont-Ferrand, in the Republic of
France, 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 :-
According to this invention vulcanized india-rubber is heated with a metal
having an affinity for sulphur and a solvent having no chemical action either on the
gum or the metal.
The process may be conducted either in an open or a closed vessel according to
the boiling point of the solvent and the nature of the metal employed.
The resulting solution of the gum is separated from the sulphide of the metal
and other matters by decantation or otherwise and the gum may be obtained by
evaporating the solvent or the solution may be used for waterproofing or
otherwise.
Amongst the metals which may be employed are:-Iron, copper, tin, lead, zinc,
mercury or their alloys, amalgams or mixtures of them, or mixtures with other
metals such as bismuth, sodium potassium or with metalloids, such as antimony,
arsenic or small quantities of sulphur or phosphorus for rendering the metal or
alloy pulverable or fusible. It is advisable that the metal be finely divided or else
that it be fusible at the temperature of reaction in order to offer as much active
surface as possible.
The following solvents may be used:-Hydrocarbons such as benzene and its
homologues, toluene, the xylenes, naphthalene, or their mixtures more or less pure,
heavy or light benzoles, crude creosote of tar, the essences or oils of schist,
petroleum, naphtha, neutral organic compounds, such as chloroform, carbon
disulphide, carbon tetrachloride, ether, essence of terebenthene or other analogous
solvents of india rubber. These may be mixed or not with small quantities of
other compounds such as ethyl or methyl alcohol.

page_text: Pulverized iron
»
"
The mixture is heated for eight hours to 130, 135° agitating continuously. The
product is diluted with 15 litres of light petroleum to render it more fluid, allowed
to settle, decanted and the operation finished as before.
Of course the proportions named in these examples are not obligatory and may
vary within very extended limits as may also the duration of the operation and the
temperature employed.
The gum devulcanized by this process still contains a small quantity of sulphur
varying according to the nature of the gum and the duration and conditions of the
treatment nevertheless it has many of the characteristics of natural india-rubber
vulcanizing under the same conditions and dissolving in the same solvents on the
other hand it has properties not possessed by natural gum for example not
hardening with cold."
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. Devulcanizing vulcanised india-rubber by heating it with a metal alloy or
amalgam having an affinity for sulphur and a solvent having no chemical action
either on the gum or on the metal.
2. The processes for devulcanizing india-rubber substantially as described.
DL: 10L
T
CTI 1004