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Патент USA US2404293

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Patented July 16, 1946
.V. l .
Alexander Johnston, Edinburgh 3, Scotland, as
signor to The North British Rubber Company
Limited, Edinburgh, Scotland
No Drawing. ‘ Application November '12, ‘1942, se
‘ rial No. 465,400. In Great Britain January 30,
5 Claims.
(01. 260—-720) -
This inventionv relates to :the regeneration or
reclaiming of vulcanised waste rubber and/or
vulcanised waste rubber containing ?brous mate
rial, so that it may be re-used for manufacturing
goods or articles. The inventionmay include the
rubber obtainable fromj'used motor-car and other
tyres, andotherarticle's. '
jected tova re-heating treatment. Thus in a rub
ber motor tyre, the tread and side wall portions
may be separated from‘the carcase, and the‘ dif
ferent parts worked up separately, or if necessary
returned for-further‘ heating. in such separated ,
If'any ofthe portions thus treated be found
to‘contain appreciable quantities of incompletely
One object’ of the invention. is to treat such
waste rubber by heatediinert ?ue or exhaust gases
decomposed ?brous material, they may be read
so that high pressure conditions are not required 10 ily removed by treatment in a washing mill or
and such a gas being cheap and easily obtained.
The waste rubber can be heated in a stream of
A further object is to regenerate waste rubber
the aforesaid gases at slightly increased pressure
so as to effect a considerable saving of time, power
that is, at a pressure not substantially above at
and expense. ' '
mospheric pressure, either in a tunnel plant or in
A still further object of the invention is to
an oven or vessel such as a digestor.
conveniently separate all-rubber portions from
The invention may be carried into effect in
various ways and ?ve examples will now “be given:
other portions'comprising rubber and ?brous ma
terial and so obtain different grades of rubber. .
According to the invention to‘be now described
" Example 1 Y
the process for regenerating waste rubber com '20
The heating of fabric containing ‘waste rubber
prises heating such waste rubber in and by con
such as motor tyres in 'a stream of boiler ?ue
tact with heatedinert ?ue or exhaust gases until
Y .
the rubber is in a condition in which itcan be
This process depends > upon the utilisation of
easily, plasticised.
Furthermore when treating rubber which con 25 the hot gases in the boiler ?ue at some stage
disintegration or carbonisation of the ?brous ma
prior to their passage up the chimney, and the
combined action of heat at 450° to 550° F. and
relative inertness bring about the necessary re
terial within a relativelyshort time, and at the
duction of the cotton to carbon, and the'rubber
dition of plasticity.
ily milled into a smooth sheet, and Without danger
of over-oxidation. The rubber of a tyre heated
tains ?brous material, the temperature of’the
gases should be sufficiently high to bring about
same timev reduce the rubber to the required con_ .30 to a soft plastic condition capable of being vread
The temperature of the gas or gases used may
be within av range of 300° to r700° F., but it will
in this way becomes plasticised, and the ?brous
material disintegratedfwithout any appreciable
be found that they aregenerally most effective
within a rangeof 450° to 500° F.
ca. L1
The treatment is preferably carried out in such
consumption of power.
' The waste rubber, cut‘ ‘into large, segments may
a manner as to control the temperature (by ther
mostat or otherwise) and/or the composition of
the heating gases, by suitable dilution with other
be- pocked into a suitable container, where the
has been completed, the mass of rubber is allowed
to cool in an inert, or, relatively inert atmosphere,
the temperature being maintained constant at ap
proximately 475° F. during this period. It is es
sential that the temperature‘iof the gases does not
become ‘too high as this results in the excessive
decomposition of the rubber and it is equally im
portant that the temperature is not too low,
otherwise the destruction of the ?brous material
takes toolong. Heat must be applied equally to
all parts of the material being treated, as other
contents will be exposed to a stream of 'hot gases
for about 2 hours, so that the heat penetrates
inert vapours or gases. When the heating stage 10 uniformly to all parts of the packed material,
before being exposed to air.
Should the waste rubber comprise portions or
layers which are substantially free from ?brous
material such as canvas, whilst other portions or
layers contain a substantial proportion of ?brous
material, it may be desirable to separate the lay
ers or portions before mastication and further
processing, or even before the heating operation 50 wise some portions are excessively'reduced and
has been completed.
This separation may be readily effected as by
stripping or pulling apart, and should it be desir
able to expose the material to the further action
of the gases such portion or portions may be sub- ,
are di?icult to handle on the sheeting mill, while
the ?brous material in other portions is insu?i
ciently reduced or decomposed, so that the result- '
ant sheet is not sufficiently smooth and takes too
much re?ning. After heating for the required
2,404,293 '
‘period, the container is withdrawn and the con
tents allowed to cool before being exposed to at
mosphere, after which the products will be found
to be in a suitable condition for milling and fur
ther processing to give a uniform smooth sheet.
injections of one minute duration each are made
every 15 minutes. At the end of this period the
product is cooled down by further steam injec~
tions and removed from the trays to be milled
and processed to give a smooth sheet.
In any one of the above examples, it will be
Example 2
seen that the treatment period is not of long du
Scrap motor tyres in’ a similar condition are
treated as in Example 1, except that during the‘ -_ ration, and that as the coolinghas been effected
heating process, steam is injected along with the .in an inert or relatively inert atmosphere, there
is no risk of ?re on exposure of the material to
?ue gases for one minute periods every 15 minutes
‘the air.
throughout the heating period. This injection of:
It' is to be understood that the treatment ac
steam-has the effect of assisting the separation
cording to the present invention does not involve
of the carcase from the tread and the side walls,‘
materialponsumption of power, and that
this operation being subsequently readily carried‘ 15 any
the gases preferably used are readily obtainable
out by hand after the product has been removed inasmuch as they are waste gases, and that no
from the container. The tread and side wall
high pressures are; necessary.
rubber is then milled and processed separately
I claim:
from the carcase rubber, and both kinds of rub-.
from vulcan
ber may, if desired, be washed on a washing mill. 20
ized rubber waste containing ?brous carbonizable
to remove completely any residual partially de
materials; the process whichrcompris'es heating
composed fabric before further processing.
pieces of: such a rubber waste in an atmosphere
'In this way two separate reclaim rubbers are‘ '
?ue gases at a pressure not substantially ex
obtained,v one from the tread and sidewall por- '
seeding‘ atmospheric pressure and at a tempera
tionsand one from the carcase portion. It may I25
ture varying from about 450° to 500° F; for a time
be stated that the steam, which is admitted in
varying from about 1 to 2 hours‘ sufficient to car
termittently, may be superheated, and that the '
bonize the ?brous material While softening the
use of seam induces a tendency for initiating the
rubber to the plastic stage'and agitating the rub
ber pieces during the heating.
separation of the layers.
Example 3
Scrap motor tyres in a similar condition are
j treated as in Example 2, except that the heating ‘
processis interrupted after one to one and a
quarter hours and the tread and side walls then
2. The process of claim 1 wherein the-rubber
pieces are agitated by tumbling them in a rotary
foraminous container.
3. In the reclamation of rubber from vulcanized
rubber tire waste containing tire fabric, the proc
I separated from the carcase. Usually the tread. 35 ess which comprises heating pieces of such a rub
ber waste in an atmosphere of ?ue gases and
‘ and side wall portion is suf?ciently‘heated after
steam at a pressure not substantially exceeding this period and may then be milled and proc
atmospheric pressure and at a temperature rang
‘ essed without further heating. It is however
1 usually necessary after this shorter period of 40 ing from about 450° to 500° F. for a time period
heating to subject the carcase rubber to a further 1 varying from about 1 to 2 hours su?icient to
‘ short period of heating.
Example '4
loosen the carcass portion from' the tread and
side wall‘ portions, the steam being introduced
for periods of about 1 minute between intervals
of about 15 minutes during the heating, separat
Scrap gas masks either in the form of complete
face piecesor the spew from moulding are packed 45 ing the carcass portion from the tread and side
wall portions and separately processing the por
into thecontainers and heated for a period of
tions for recevery of the rubber contained‘therein.
one hour at 450‘? F. At the end of this period
4. The process of claim 3 wherein the sepa
‘the product is cooled, removed from the con
rated‘c'arcass portion is subjected to a further
tainer and is then found to be suf?ciently plasti
‘ cised to be milled and processed into a smooth
heat treatment under the same conditions for a
time suf?cient to carbonize said ?brous material
Example 5
Scrap motor tyres are cut into small sections
and to soften the rubber to the plastic stage.
portions are washed on a washing mill to remove
‘ and packed on trays which'are placed in an oven, 55 residual partially decomposed fabric before fur
I and through which oven ?ue gases at a temper
ther processing.
fature of from 475° to 500° F. are passed for a
period 'of two hours. During this period steam
'5. The process pf claim '3 wherein the separated
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