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Патент USA US2406458

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Patented Aug. 27, 1946
UNITED snares
earn-m‘ orFioE ‘ .1
vGlerndt and John .A. Hannu-m, Detroit,
' . .Midh.,.assignors ‘to United States Rubber Com
pany, New‘York, ,N. .Y., a corporation ‘of New
Jersey ‘
'NpDrawing. Application July .15, 19.44,
Serial No. 545,204
iThisinvention relates to i-azmethod .of removing
rubber "from metal. More particularly the inven
tion relates ‘to the art of weakening the bond .be
‘tween rubber and metaLin composite rubber .and ,_-;
metal structures so ‘that the rubber can be readily
mechanically separated .“from .the metal.
According to the present invention, the com
posite rubber and metal structure is subjected to
vention .may be used to strip the .rubberirom .the
metal .partsof such composite rubber-.and-metal
assemblies as tank tread links, tank blocks, tank
,pins,.motor mounting parts, and .tire bead wires
embeddedinirub‘ber casings. It mayalso be used
for cleaning molds used ‘in the manufacture of
rubbervarticles where rubber adhered .to themolds
mus'tbe removed.
the action .of ammonia, monomethylamine, di-; =
"."In treating .a structure
which a rubber is
methylamine, or monoethylamine for a time and
adhered to metal with ammonia or an amine ac
under pressure and temperature conditions such
cording to the present invention, both heat and
that the bond between the rubber and metal is
pressure are desirable but not essential. The
materially weakened, whereupon the rubber may
higher the concentration of the solution of am
be separated readily from the metal, as by pulling
monia or amine where a solution is used, and the
off by hand or stripping. The composite rubber 15 higher the temperature and pressure where the
and metal assembly may be subjected to the am
ammonia or amine is used in the gaseous state
monia or amine in gaseous form or in aqueous
or in aqueous solution, the faster the ammonia or
solution. The ammonia or amine readily diffuses
amine will diffuse through the rubber to attack
through the rubber to the rubber-to-metal bond
the rubber-to-metal bond. The thicker the rub—,
whether from the gaseous statelor from aqueous 20 ber portion through which the ammonia or amine
solution to weaken or destroy the bond. In the
must penetrate the longer will be the time neces
case of aqueous solutions, the ammonia is drawn
sary to effect the weakening or destruction of the
from solution in the water and readily permeates
rubber-to-metal bond. It may readily be seen
through the rubber to the rubber and metal inter~
that no ranges of time, temperature or pressure
face. It has been proposed to weaken the rubber 25 can be given in exact ?gures for various concen
to-metal bond in composite rubber and metal as
trations of the ammonia or amine or for the vari
semblies by treatment of the composite structure
ous thicknesses of rubber that will be encountered
with water or aqueous solutions of ?xed alkalis
or for all types of rubber-to-metal bond. How
under pressure at elevated temperature and there
ever, it is a simple matter in any given case to
after to mechanically separate the rubber from 3 empirically determine the speci?c conditions
the metal. The present method has the great ad
which will weaken the bond so as to permit the
vantage over these prior proposals in that water
rubber to be removed from the metal by a me
itself or the ?xed alkali dissolved in the water will
chanical separation.
di?use through the rubber only with great dif?
The preferred material used according to the
culty and then only very slowly, whereas with the " present invention is ammonia, and for economic
much higher permeability of the ammonia and
reasons, it is desirable to use it in its commercial
amines through rubber, the ammonia or amine,
form as approximately a 30% aqueous solution,
as in the present case, will diffuse through the
which may be diluted to as low as '10% in many
rubber very rapidly to attack the rubber-to-metal
cases. With a 20% to 24% aqueous ammonia so
bond. Further, ammonia, mono_ and di-methyl
lution, corresponding to diluting commercial
amine, and monoethylamine are gases at room
29.4% aqua ammonia with 20% to 40% water by
temperature and atmospheric pressure and hence
volume, heating to 300° F. in a closed chamber
vwill readily di?use out of the rubber after the
creates a pressure of 200 to 250 pounds per square
treatment to give a rubber that does not contain
inch. The treatment of small parts in an aqueous
any foreign materials that would interfere with
solution of 10% to 30% by weight of ammonia in
the reclaiming of the rubber by conventional re
a closed container at a temperature from 150° to
claiming procedures.
1 325° F. for one-half to ?ve hours is generally satis
The present invention is applicable to cured or
factory to suf?ciently weaken the rubber-to-metal
uncured natural or synthetic rubber stocks which
bond to permit mechanical separation of the rub
may be adhered to metals such as brass, bronze, 50 ber from the metal without di?iculty.
and ferrous metals. The rubber may be bonded
As a speci?c villustration, a pressure tank of
to the metal by direct vulcanization of the rubber
about 30 inches internal diameter and about 60
to the metal, or by the use of an intermediate ad
inches high is equipped with a removable top
hesive, as for example, a rubber isomer cement or
cover and steam coils in the bottom of the tank
a rubber hydrochloride cement. The present in
' which are also pipes to cold water for cooling
should be made to the appended claims for a
purposes. The tank is built to operate up to 300
pounds per square inch pressure. Commercial
aqua‘ ammonia (29.4% NH3) diluted with 40%
by volume of water to give an aqueous solution
' understanding of the scope of the protection af
forded the invention.
of approximately 20% by weightjof ammonia is
run into the tank to about the half-way mark.
A wire basket containing rubber-and-metal as
semblies, in this case small rubber covered metal ,
discs from scrapped motor mountings, was low-’
erecl into the container below the level 'of the
Having thus described our invention, what we
claim and desire to protect by Letters Patent is:
1. The mmethod of removing a rubber from
'metal in a structure in which the rubber is ad
hered to metal which comprises subjecting the
composite rubber and metal structure to the ac
tion of ‘material selected from the group con
ammonia solution. ' After the cover was vsecurely
sisting of ammonia, monomethylamine, dimeth
bolted in place, the ammonia solution was heated
, ylamine and monoethylamine, and thereafter me
between the rubber coatings and the metal discs.
' composite rubber and metal structure to the ac
> tion of ammonia, and thereafter mechanically
separating the rubber from the metal. ,
chanically separating the rubber from the metal.
by means of the steam coil'to about 300°_ F., cre
1' 2. The method of removing a rubber from
ating a pressure of 200 to 250 pounds per square
'inch. This pressure was maintained for two 15' metal in a structure in which the rubber is ad
hered to metal which comprises subjecting the
hours which was su?icient to break the bond
:At the conclusion of this pressure period, cold
water was circulated through the steam coils un
til the entire apparatus was cold, and the am
monia almost entirely reabsorbed into the solu
tion, preventing wasteand minimizing the objec
3. The method ofremoving a rubber from
metal in a structure in which the rubber is ad
hered to metal ‘which comprises immersing the
composite rubber and metal structure in an aque;
tionablei smell of ammonia when the cover is _
ous solution of 10% to 30% by weight of am
removed. is The'cover was ‘taken, off, the basket
raised, and the discs removed, whereupon the 25 monia in a closed container at a temperature
rubbercoatings could be easily stripped by hand 1' from 150° to 325° F.'for one-half to'?ve hours,
and thereafter mechanically separating the rub
from the metal discs.
ber from theametal.
In view of the many changes'and modi?cations
that may be made without departing from the
principles underlying ‘the. invention, reference 80
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