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Патент USA US2409760

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Oct. 22, 1946.
Y
o. w. HOSKING
‘
2,409,759
DIRECT BONDING OF RUBBER TO METAL
Filed Sep1i.'13. 1941
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BY
.
,wén;
ATTORNEYS
'
/
Patented Oct. 22, 1946
2,409,759
UNITED STATES PATENT OFFICE
'QDIREGTKBGNDING OF RUBEER T0 METAL
Oakley 'W. Hosking, Monroe, N. '-Y., as'signor to
- Composite
Rubber Products Corporation,
‘Bridgeport, Conn, a corporation of Connecti
cut
"Application September 13, 1941, Serial No.410,696
17 Claims.
(Cl. 154-430)
2
1.
‘This invention ‘ relates ' to-the art of bonding
rubber to metal, and to a process for theproduc
‘tion of-composite‘rubber-metal articles wherein
rubber or a rubber-like sub-stance is securely
bonded directly‘ to ‘a metal surface.
More speci?cally, ‘the invention relates to a .
stand the strains to which they were to ‘be sub
jected in use.
.
Fair results ‘have been ‘obtained by applying
adhesives, tie gums or cements to certain mate
‘ rials including metals, and then vulcanizing or
otherwise securing the rubber‘substance thereto.
The use of such tie gums‘and cements‘usually
provides a more uniformdegree of adhesion,‘ but,
in general, the layer of ‘cement is of consider
metal piece to 'which‘it'is‘tofbe directly bonded, 10 ably lower tensile ‘s‘trength‘than the rubber ‘and
accordingly, such methods vwere not‘ capable‘of
and then subjectedto a'treatment‘io'r e?ecting
producing a sumcient bond between "a'metal'an‘d
direct bonding of the rubber to the metal.
rubber substance to satisfy many requirements
The invention ‘especially relates‘ to ‘processes of
in the arts.
'
the 'aforesaid‘type, in which arubber composition,
adapted to be bonded'directly'to a‘ metal piece'is
‘ In prior processes for ‘bonding rubber‘to metal,‘
it has been proposed to ‘pretreat the surface
prevul'canized, either partially or completely, and
of the metal to which‘ the rubber'is to be bonded,
subsequently bonded directly to apiece of rubber‘
in such a manner that the ‘surface is rough
‘a.dherent metal.
ened, as for instance by pickling "the metaLsand
The present application .is a continuation in
blasting the same, or'forming actual protuber
part of my copending application, Serial No.
process for producing rubberemetal articles,
wherein a'r‘ubber‘or rubb‘erelike substance is pre
mcl‘ded or preformed, then assembled with the
‘234,616, ?led October 12, 1938, nowPatent No.
2,337,555, granted December ‘28, 1943, and of my \
copending application . SeriaTNo. ‘352,578, “filed
August 4, 1940.
It haslong-ibeen a desideratum in the artrto
form a strong and'lasting bondbetween rubber
ances or notches around which and "between
which the rubber is intended to' ?ow, thus ‘mak
ing possible a mechanically ‘interlocked ‘bond
between the'rubber and metal. However, since
the strength of the ‘bond depends upon the ex
tent to which ‘the rubber and‘metal interlock,
‘the .e?ectiven‘ess of such a physical union depends
upon the kind and strength of the destructive
‘force ‘app-lied'to-‘the ‘bonded rubber and‘metal
andmetal pieces ‘so-‘that therubberand metal
would remain united in?rm-and fastrelation
ship and‘resist. mechanical forces; such ‘as .afforce
tending to pullthe rubber and-metal apart, tor 30 article. The use “of metal having a roughened
surface yields somewhat better results when a
torsion tending .to twist ‘the rubber fromithe
metal.
It has ‘been attempted heretofore to produce
rubber and metal articles wherein the rubber is
bonded to-a metal surface by vulcanizingthe
rubber indirect‘ contact with said metalvysurtace.
Many proposals have ‘been, made heretoforeioi'
accomplishing-‘this result in“ this mannenibut (so
cement or tie gum is applied thereto, but the
bond produced is'still of inferior‘strength be
cause ‘of ‘the use of the cement. Furthermore,
such methods of pretreatment for the metal-sur
face are relatively “expensive ‘and ‘tedious and
materially increase the cost'of the ?nished article.
‘ It is ‘often oi‘great technical ‘advantage in pro
ducing composite articles of rubber and metal
wherein the rubber'is to be‘bonded to themetal,
40
the "metal" and ‘rubber are to‘ be'secured together
‘to mold or form the rubber prior to its assembly
by ‘direct contact between the ‘metal and ‘the
with the metal pieces, then to assemble the rub
rubber, haveproduced satisfactoryresults. The
her with apiece of metal, and ?nally ‘to bond the 5
bond produced is of ‘relativelyAinferioristrength,
rubber thereto. This is especially true in mass
and‘ upon ‘subjecting .the ‘article to stresses ‘tend
' production where it is desired to form the rubber
ing to tear the rubber v‘away’ from the 1metal.
in one part of a manufacturing plant and bond
separation occurs at thebond.
1
‘ .
it to the metal in another part thereof. In mold
far as I am aware, none of theseproposals, where
Moreover, in general, the‘strength of *the‘bond
produced accordingfto such prior art‘ processes
.‘generally occurs and in this case,‘the only method
was variable ‘and could not be "controlled; _. The
known heretofore of bonding suchpieces ‘subsee
resulting unreliability of the ‘rubber and metal
quently to metal was the use of a tie gumgcement;
articles wasespecially disadvantageous since in
ing the vrubber pieces, however, vulcanization
or adhesive. .Because‘of the inferior nature of
the bond produced with such ‘tie gums and adhe
general it is impossibleto test the'?nished arti
sives, ithe articles produced were often unsuit
cles to the point of ‘failure of 'the‘b'on‘d‘ in order
to determine whether theiarti‘cles would ‘with 55 able gfo-r the purpose for which they were destined‘.
2,409,759
3
4
Accordingly, it is an object of the present in
vention to provide a process of bonding rubber
proportions of other metals such as lead for modi
fying the properties of the alloy.
While “Monel” is a trade-mark, it is used here
in in the sense de?ned by the dictionaries. That
is, Monel metal is an alloy comprising approxi
mately 67% nickel, 28% of copper and ?ve other
elements, chiefly, iron and manganese, made by
the direct reduction from ore in which the con
stituent metals occur in these proportions. This
de?nition is very similar to the published analysis
of Monel metal as given by the exclusive pro
or rubber-like substances to metal articles, where
in the rubber may be preformed or premolded,
and vulcanized either partially or completely,
prior to its assembly with the metal piece to which
it is to be secured, and thereafter bonded di
rectly to said metal piece without the use of tie
gums, cements or the like.
It is an object to provide a process of the afore- .
said type in which the bond produced is of such
strength that it exceeds the tensile strength of
ducers thereof, namely, the International Nickel
Corporation. The analysis given by the pro
the rubber itself so that upon tearing the rub
ber away from the metal, the failure occurs in
ducers of said alloy is as follows:
the rubber and not in the bond; and especially
to produce bonds of such reliability that the proc
Per cent
Nickel ________________________________ __
ess may be used in any instance where the
strength of the bond is of critical importance.
A further object is to simplify the pretreat
68
Copper _______________________________ __
29
Iron __________________________________ __
1.6
Manganese ___________________________ __
1.0
ment of the metal surfaces to which the rubber is 20 Silicon _______________________________ __ 0.10
to be secured in order to provide a superior bond
Carbon ________________________________ __
1.15
of the aforesaid type, whereby substantial econ
Sulphur ______________________________ __ 0.005
omies may be secured.
The basis for the present invention is the dis
Throughout the speci?cation where I mention
covery that in processes wherein rubber is vu1-.,_.75 Monel metal, I refer to the alloy embraced within
canized in direct contact with metal surfaces,
the de?nition given by the dictionaries and set
bonding between the rubber and a metal to which
' out above. One of the more important advan
it may be caused to adhere directly, occurs not
tages of Monel metal is that this alloy is sub
only during the latter stages of vulcanization,
stantially uncorrodible, and is worked as easily as
but also after vulcanization of the rubber com 30 other metals of the same toughness and wearing
pound is complete. This observation has led to
qualities.
the surprising discovery that partially vulcan
In practicing the present invention, where
ized or completely vulcanized rubber can be
bonded directly to a metal surface without the
use of tie gums or cements.
In order to produce a composite rubber and
practically the entire face of the metal piece is to
be bonded to the rubber and the metal piece has
relatively little mass, the whole metal piece may
be made economically of rubber-adherent metals
metal article, according to the present invention,
of the aforesaid types.
a metal piece is used, the surface of which is
Where, however, the
metal piece has a great deal of mass and a com
made of an alloy or metal to which a given rub
paratively small surface is to be bonded to the
ber composition or rubber-like substance is 40 rubber piece, it will be found in many cases de
adapted to adhere. In order to prepare the sur
sirable to make the metal piece of a base metal
face of the rubber-adherent metal piece to which
such as iron, steel or the like and to secure by
rubber is to be bonded, the surface thereof is
any of the usual methods, for instance, by weld
rendered clean, smooth, bright and continuous.
ing, a layer such as a thin plate of the rubber
The rubber or rubber-like substance to be
adherent metal to the surface of the base metal.
bonded to the metal piece is compounded in such
I have discovered contrary to expectations that
a manner as to provide a composition adapted
in order to produce a superior bond according to
to adhere directly to the said metal. t is then
the present invention between the rubber and the
preformed or premolded in a shape having a
rubber-adherent metal, the surface of the metal
surface conforming substantially to those por
50 must be not only clean, smooth and polished, but
tions of the metal piece to which it is to be se
cured. At the same time, the mass of rubber is
also continuous, i. e., the contacting surface being
then assembled with the metal piece in the de
sired relation and con?ned, for instance in a
mold, the rubber being in direct contact with the
metal. Sufficient pressure is applied to insure
free from macroscopic or microscopic depres
sions, crevices or ?ssures. If this is not the case,
an inferior bond is produced.
I have found, for instance not only that metal
surfaces which are macroscopically roughened, as
for instance by sand blasting or pickling, are un
suitable for producing superior bonds, but also
intimate contact between the metal and the rub»
that metal surfaces having microscopic depres
vulcanized, either partially or completely.
The premolded and prevulcanized rubber is
berw and su?icient heat to cause bonding of the 60 sions, crevices, or ?ssures are similarly unsuitable.
If the nature of .the metal is such that micro
rubber to the metal surface. In general, if the
rubber has only been partially vulcanized, the
heat thus applied is also utilized to complete vul
canization of the rubber. The composite rubber 65
and metal article is then stripped from the
mold by any of the usual methods.
As metals especially adapted for bonding of
rubber thereto, I have found that Monel metal
scopic openings are present below its surface,
the metal cannot be rendered suitable for direct
bonding according to the present invention, by
polishing alone. Such metal surfaces are, for in
stance those produced by electroplating or by hot
spraying.
Although such surfaces, especially
when polished, may appear to the naked eye to be
bright and continuously smooth, the minute
and cuprous alloys of the class of brass or bronze 70 crevices or ?ssures resulting from the method of
are especially suitable.
their formation are present in the surface and
Cuprous alloys of the type of brass or bronze
impair the bond with the rubber substantially to
may contain, for instance from 60 to 85% cop
.the same extent as the visible depressions in sur
per, the principal remaining ingredients being tin
or zinc and may also include relatively small 75
faces of obviously rough nature.
It is believed that the reason for this effect
$2,409,759
$5
"almoIu-gteniperature ofisi'o"inriforrazperidd of 110
is jthat Lair 'or‘other gases are occluded "in “the
macroscopic for Lmicroscopic ‘depressions -‘ of the
minutes.
a _
,1Nnmerous-compos1tions>are also'knbwn'linTthe
metal surface when .an 3attempt -‘ is ‘made 'itob'ond
the-l rubber "thereto, holding the; rubber awayi‘from
‘alirtliai‘s suitable‘ ‘for idir‘ect‘ bonding ‘itof-fcupr‘ous Jal
the metal at these points. This resultsin‘i‘dis‘con
tinuousl‘bonding -so that vthe tensile "strength of
lloys of thetype-of ‘brass'orlb'ronz‘e.
According to the presentfinventionlivhasbeen
thefbon‘d is greatly impaired.
‘
, ifoun'd that an‘!especiallwsatisfactory‘composition
‘
iyiel'ding highly ifsfuperior T results ‘with ‘brass "or
T‘Thus the rubber-adherent metalfforming the
biforizel‘maylbe‘preparedby use 6ffa‘quantity of
v‘surface.of‘lithe-metalarticle to~which the rubber
‘composition to be ‘bonded must be ofea. continu 10 lsmoke‘dlsheetl'or pale crepe,"‘a1suitable quantity of
sulphur; an accelerator, especially of theim‘er
ous nature and 'be ‘free ‘of iminute depressions,
"captoarylthiazole type,-a softener of?the'iclass of
‘crevices ~ or the like ‘resulting "from the manner
inwhich‘it'isl-produced.
“higher ‘fatty acids; and a quantity of “chemically
pureWzin‘c» oxide. l'I'heilatterinl conjunction ‘with
‘As statediabove,“the'surface ofithel rubber-rad
here'ntlmetal must ‘also be‘ rendered" clean; smooth 15 ‘the aforesaid jtype Jof accelerator ‘appears 'to The
essential for‘ the “superior bonding properties fof
sand-‘bright andiito this *end, it
merely neces
the composition,
‘sary to-‘polishiit. “The polishingioperationlmay '
~By ‘~‘chemicallylpu‘re” zinc oxide is meant that
which “listlordinarily 1‘sold. as a chemicallreagent
buffing iwlie‘eliha'ving criocus ‘martis (a form‘of 20 rather“ than for 'te‘chnical‘purposes and which". is
prepared by ‘combustion -of pure molten Jzinc
‘ferric JoXide) thereon-as ianfabrasive. Since the
‘metaliirr air-llor‘by heatinglzinc compounds‘which
polishing ‘operation alone is a‘ satisfactory, in Lthe
yielditheoxidelby‘ thermal decompositionat rela
case ‘of rubber-adherent metals of continuous
tively moderate temperatures, such as precipi
nature, for producing the superior ‘results of ‘the
‘be carried ‘but 'for instanceiby 5 bii?i'ng ‘the :sur
ifa'cei‘o'f the metal Ionvai‘crocus” wheel, that is a
present inveritiongo‘ther?forms of pretreatment, '
'suohlas fpickling,i sand-‘blasting ‘or-‘the- like 1 are ren~
tated basic zinc carbonate or zinc nitrate. Com
amercial or technical zinc oxide which ‘is that
ordinarily used in rubber. compositions as well
was for pigmenting paints, is produced'by a dif
'dered Iunnecessary. ‘This ("results in "material
economy in the production" of the ‘composite rub
ber and metallarticles.
‘
iferent ‘method, ordinarily comprising the com
bustion of the vapors‘produced/from rheating'a
mixture ‘of zinc ore-in combination withireduc
ing agents. Apparently, the-difference between
order to ‘avoid flthelformation' of a him of
‘oxide-‘or accumulation "of “dirt, the polishing of
the (rubber-adherent metal surface is preferably
the two types of zinc oxide is a physicalzrather
than a chemical one. It is not‘fully understood
)carried x‘out-directly prior to "application‘of the
rubber thereto.
why “chemically pure” zinc ‘oxide, when used in
The-rubber‘pieces which‘ are to be bonded to
the hrubbereadherent metal article are prepared
from rubber compositions"designed to adhere to
‘rubber compositions endows 3‘ them with greatly
‘superior bonding qualities relative to brass or
"bronze, ‘as 1 compared “with similar ‘compositions
the v‘particular metal ‘to which “they are to be
b‘onded. The nature of such compositions varies .
somewhat according to vthe kind‘ of rubber-ad
'herant' metal used,‘but thena'turepf the composi
40
containing‘technioallor commercial zinc oxide,
but'i‘t‘lis thought-that the peculiar physical form
of tthe“chemically pure” zinc oxide results‘in
'
properties which render it more readily available
‘It-hasalso been‘foundac‘cording to the'pres
forreaction with the-other components of the
tions are in general well known in the~ar-t.
rubber mixture and the commercial grades
ent invention that not only ‘compositions contain
ing-natural ‘ rubber but also‘ those prepared from
; thereof.
In the speci?c composition adapted‘ for bonding
to brass or bronze by the process of ‘the present
invention, the quantity‘of sulphur may be‘fr'om
Duprene; chloroprene and the like can be similar
about'Btobparts by weight per 100 parts of crude
ly use'd with‘excellentlresultsfThus, in the present
ispelcifi'catiomwhere I have mentioned rubber ‘or ’ ‘rubber substance, about 5 parts of sulphur being
‘preferably used. As a vulcanization accelerator,
rubber-like substances, 5I intend these-terms‘ to
~mercaptoarylthiazole accelerators which com
include all natural caoutchouc, ‘derivatives there
prise mercaptobenzothiazole, its homologues and
‘of, and‘substi-tutes therefor, which ‘are vulcaniz
synthetic rubber substances, ~especially of “the
class of butedienoid polymers such ‘- as neoprene,
‘able.
derivatives such ‘as for instance the 'zinc salts and
'
In the case of Monel'm'etal;it‘hasbeen found
‘that the bond'producedwith most metal=adherent
rubber’ compositions *and- various synthetic ma
- ignated herein as mercaptoarylthiazole accelera
‘teria-ls‘such ‘as‘n‘eoprene is superior to thatpro
“duced ‘with other‘metals.
‘
A composition, suitable for’bondin‘g ‘to 'Monel
"metalfa'ccording to ‘ this invention, ‘may contain
the followingiin'gredients; parts are ‘by ‘weight.
,
thosefin which the hydrogen of the mercapto
‘group is rep-laced by an ‘organic ‘residue, are es-,
pecially satisfactory. Such compounds are des
Parts
‘tors. it is preferred, howevento use an accelera
tor of the aforesaid type wherein a mercaptoben
zothiazole radical is coupled withthe residue of
‘an aromatic amine of the benzene series through
the sulphur of the mercapto group by a methylene
‘bridge which joins the mercaptobenzothiazole
"Rubber (smoked sheet‘) _________________ __ 100
residue with the aromatic amino group. A pre
‘Mercaptobenzothiazole __________________ .._
“ferred' accelerator of this class is for instance a ,
1
fPe‘trolatum ________________ __‘___‘___; ____ __
l
mixture 00f mercaptobenzothiazoleemethylene
LSte'aric' acid __________ _’____‘____‘ _________ __.-
l
aniline and ‘ mercaptobenzothiazole-methylene-o
*3Zinc‘o$cide___
8
,
‘
_
'
_
‘Whiting--. _______ -‘. _______________ __,__‘__‘__ ‘40
"Iron oxide_____________________ __'___'__‘____"
5
‘Sulfur _______________________ _‘____,,_‘__‘____ 2.5
‘toluidine, The quantity of accelerator used may
vary fromaboutl to about 2 parts by weight per
100'parts ‘of rubber substance, but preferably
about 1 part of the accelerator is used.
'
The softeners included in the preferred com
‘Thelingre'dients‘ are-mixed on alniill‘in the ‘usual
*manner. ‘The"compositionl‘may*be-vulcanized'at
position may be higher fatty. acids, such as
‘stearic, “ole'ic "or lauric ‘acids, ‘ but *stearic ‘acid ‘is
2,409,759
7
preferred. The quantity of higher fatty acid may
8
vary Within the reasonable limits usual in com
eration may be used, but relatively high pres
sures are preferably applied, and accordingly, the
pounding rubber. About 2 to 4 parts of-higher
fatty acid ‘to each 100 parts by weight of rubber
rubber is so con?ned as to prevent lateral move
ment thereof with respect to the rubber-adherent
substance are used, and preferably about 2 parts
metal surface.
of stearic acid are used.
, The quantity of chemically pure zinc oxide
should be at least 5 parts by weight per 100 parts
of crude rubber. Larger quantities may be used,
but substantially the same effect is produced
thereby.
.
1
Heat is applied in such a manner that the
_
.
metal and rubber are raised to a temperature
su?icient to cause the rubber to bond to the metal.
Such temperatures are generally comparable
with those required for vulcanization of the rub
ber compounds suitable for use in the present
procedure. For instance, temperatures from 300
to 320° F. have been found satisfactory in the
The remaining components of the said com
position may be selected as desired. These may
comprise ?llers, such as carbon black and com
case of the rubber composition adapted for use
mercial zinc oxide; additional softeners, as for 15 with brass disclosed above, as well as for the
instance asphaltum, pine tar and the like; and
speci?c composition adapted for use with Monel
it is generally advantageous to add a, suitable
metal. As a result, if the rubber is only par
quantity of an antioxidant such as phenyl-beta
tially vulcanized prior to its assembly with the
naphthylamine in order' to prevent, premature
metal, vulcanization is completed in the present
aging of the rubber. Agents which increase the 20 process. The duration of the heating vvaries ac
heat resistance of the rubber may also be used.
cording to the composition of the rubber and
the metal used. For example in the case of
A suitable recipe for the aforesaid composi
rubber compositions which are completely vul
tion, in which parts are by weight, is as fol
lows:
canized before assembly with a metal, heating
'
Parts 25 from 3 to 10 minutes, preferably for about 5
minutes, was found suf?cient to effect the forma
Rubber (smoked sheet or pale crepe) _____ -_ 100
tion of the desired bond. In the case of partially
Phenylbetanapthylamine _______________ __
1
vulcanized rubber, the time for heating is gen
vStearic acid ____________________________ __
2
erally increased by a period su?icient to effect
Sulphur _______________________________ __
5
complete vulcanization. From about 3 to about
Chemically pure zinc oxide ______________ __
5
15 minutes is generally satisfactory. When the
Mercaptobenzothiazole methylene aniline
bonding is complete, the pressure is released, the
plus mercaptobenzothiazole methylene o
composite rubber and metal article removed from
toluidine ____________________________ __
1
the mold and allowed to cool.
Soft carbon black _______________________ __ 40
35
In the accompanying drawing, several articles
The above ingredients are thoroughly mixed by
are shown by way of illustration which may be
milling in the usual manner and calendered to a
produced according to the present process.
sheet of the desired thickness. This composi
Figs. 1 and 2 show tire valve stems partially
tion can be vulcanized in a mold temperature of
in cross-section having a tubular metal insert
about 310° F. for a period of about 10 to about 15 40 bonded to a rubber base.
minutes at a pressure of 300 pounds per square
Fig. 3 shows a cross-section of a rubber-like
inch.
"
metal tube.
In practicing the process of the present inven
Fig. 4 shows in cross-section a rubber layer
tion, the uncured rubber composition is pre
bonded to a metal plate.
formed or premolded in a shape adapted, to con
Fig. 5 shows partially in cross-section a metal
form to that of the metal article to which it
rod secured in a rubber sleeve surrounded by a
is to be subsequently ‘bonded. A slug of the rub
sleeve of metal.
ber composition is placed in the mold or form and
Fig. 6 shows in cross-section a mold adapted
con?ned under pressure. Heat is applied to- ren
for use in forming a rubber and metal article
der the mass plastic so that it acquires the form
wherein the rubber may be vulcanized and
in the mold, and the heat is continued for a su?‘i
molded separately from the metal and subse
cient period to partially or preferably to com
quently bonded thereto.
.
pletely vulcanize the rubber. The mold is then
Fig. 7 is a view similar to Fig. 6 showing the
opened, the rubber article removed, and assem
same mold during bonding of the premolded rub
bled in the desired relation with the metal piece
ber piece to a, metal piece.
having a surface of rubber-adherent metal to
Fig. 8 is a plan view of another composite arti
which itis to be bonded, the metal piece hav
cle with part of the rubber substance omitted
ing been previously prepared, as described above,
to show the way the metal may be formed so
by polishing to give it a, smooth, clean continu
that the area of the bond between the rubber and
ousrpolished surface.
’
the metal is‘ reduced.
. Sui?cient pressure is then applied, preferably
perpendicular tothe contact surface of the rub
ber and metal to maintain intimate contact at
the rubber-metal interface and in such a man
neras to prevent ‘distortion of the rubber. The
assembled article is preferably con?ned, for in
stance by placing it in a mold which ?ts snugly
around'the rubber portions and the contiguous
exposed metal surfaces thereof. Suitable means
is provided for maintaining pressure at the rub
ber-metal interface throughout the bonding oper
ation.
-
>
.
Any pressure which is su?icient to maintain an
‘intimate substantial pressure contact at the rub
'
In order to produce the valve stems shown in
Figs. 1 and 2, the rubber bases l0 and H are pre
molded and vulcanized. In order that a substan
tial pressure may be conveniently applied at the
rubber-metal interface between metal inserts l2
and I3 and rubber bases H) and H, the inside
diameter'o'f the rubber sleeves l4 and I5 into
'which'the'metal'inserts l2 and I3 ?t is- made
slightly'smaller th'a'nthe outside diameter of the
'metal inserts. The latter are made of a rubber
adher'ent metal adapted to be bonded to the com
position of the rubber bases [0 and II and their
surfaces polished ‘until they are smooth and
bright,iand are of a continuous nature. The in
ber-metal interface throughout the bonding pop‘ 75 serts are then inserted into the rubber ‘bases as
2,409,759v
10
shown,v and the" articles positioned in a mold
adapted to con?ne the rubber. The mold is closed
and'su?icient pressure‘ applied to the rubber to
maintain a‘ substantial positive pressure at the
rubber-metal interface. The contents of the mold
is heated'until bonding occurs between the rubber
and‘ the metal», and the valve‘stem thereafter is
stripped fi'cmthe mold.
Referring to Fig. 3, the‘ tubular rubber lining
I8 is premolded and vulcanized. Its outside di
ameter is preferably made. slightly larger than
the: inside diameter of the metal sleeve l‘! to
which it is to be bonded. The sleeve I1 is‘ con
the'otherfhalf'?t- of‘ the moldmay contain cavities‘
3:8'rfor1 receiving’ metal‘ pieces 34‘. Between the
two‘ molds, a plate or platen 35- may be‘ initially
inserted, on which pieces‘ of unvulcanized rub
b‘er, compounded to adhere‘ to a metal-adherent
surface are then placed under the cavities 36 in‘
the part’-
oi‘ the mold‘. The parts of the mold
are/‘brought together‘ under‘heat and pressure as j
illustrated‘ in Fig. 6, and the ‘rubber pieces 3T are
formed and vulcanized either completely or par-‘
tially, depending upon the length‘ of time they
are subjected to the vulcanizing action. When‘
this: has been done; the platen 35' is Withdrawn
structed'v of a metal such as Monel metal'or brass,
fromnbetw'een the‘ parts 32‘ and 33‘ of the mold
having a continuous surface, to which the rub 15 and‘ the metal‘pieces 34- inserted in the cavities
ber composition is adapted to be dire'ctlyibonded,
38 in the part 33 of the mold if they were‘ not
already placedthe‘re before the molding opera
and its‘ inner surface rendered clean, smooth and
bright by polishing. The rubber lining [8' is in
tion began.
serted into the bore of the sleeve l1 and the com
When the" platen 35‘ is‘ withdrawn from the
posite article placed in a mold having a‘ core pin 20 mold parts, any ?ash‘ formed by the molding of
adapted to ?t into‘ the axial bore [6 of the rubber
the- rubber pieces‘ 31 that will‘ adhere to the'
mass l8‘. On‘ closing the mold; pressure is applied
platen 555 will be carried‘ away‘ ‘with the platen to
to the surfaces‘ l9. and‘ 20“ of the rubber mass,
be scraped‘ off‘ later. The parts 32 and 33', one
whereby‘ positive‘ pressure is maintained at the
containing‘ the precured or semicured rubber
rubber-metal interface and supported by the pin - pieces‘ 3?, and the other containing the metal
extending through the bore of‘ the rubber mass
pieces 34' having? a‘ rubber-adherent metal sur
face, are‘brb‘ught together under heat and pres
i8‘. Upon application of heat, the rubber is se
sure'to bond the rubber to the‘ metal;
curely bonded to the inner surface of the sleeve.
When the’ bonding operation is completed, and’
If ‘ desired, the rubber lining l8imay be premold‘ed
the mold separated,‘ the metal and‘ rubber pieces
to have‘ the same outside diameter as the inside
being new united m‘ay be‘removed' from the mold
diameter of the sleeve ll, but the bore 16 may‘
as a composite‘ article‘by‘ any suitable‘ stripping‘
be made slightly smaller than the core pin of the
mold in which‘bonding is to be effected. Closure
means.‘ The practice of the method‘ just‘ de‘-"
of the mold thereby causes pressure to be ap
scrib'edand the apparatus‘ used therefor‘ avoids‘
plied at' the rubberemetal interface by com
the necessity'of stripping the premolded rubber"
pieces'from the mold and‘ replacing them in an‘
pression oflthe‘rubber between‘the oversized pin
and the inner’ surface of the metal sleeve, said
other mold to be bonded totne metal‘ pieces‘.
pressure being supported by the mold con?ning
The hereinbefore described process‘ can be‘a'p'l‘
plied‘ for bonding- a plurality‘ of‘ metal‘ piece‘st‘o
the‘ends l9 and“ 2B» of the rubber mass: ‘
Iii-order to bond the rubber layer‘ 21- to the
surface of ‘the plate 22, as-shownin‘ Fig. 4; the
rubber 21!? is‘ premolded and vulcanized‘ in the
desired‘ form from‘ a composition compounded
’ forms‘ allinkibetween the various metal‘pieces, or"
to have metal-adherent‘ qualities,‘ brought into“
bridge between the‘ various‘rubb'er parts‘. More
the same mass of rubber, whereby‘ the’rubb'er
several: pieces of? rubber‘ may be‘ bonded to the
same piece of metal, whereby‘the‘ latter forms a‘
contact‘ with the metal plate 22 of rubber-ad
over, if‘ it is desired, additional pieces of‘rubber
herent metal, the surface of‘ which isfcontinuous,
may- be‘ secured by any of the well-known
and polished to render-lit smooth and clean. Pres
methods‘,- for!‘- instance‘by‘ vulcanizing, to a mass
sure is applied, tending to con?ne the rubber
of ' rubber ‘secured to the metal article by? the"
and force it against the surface‘of the plate, and
above-described methods.
the temperature is raised to caus'e'bonding of‘ 50
One of the more important features‘ of‘ this‘
the rubber to the metal surface;
invention is’ that“ the metal and'rubb‘e'r m'ayibe
bonded together‘by' processes similar to‘the 'pro‘cé
In order to‘ make the rubber-metal article
essiof- vulcanizingrubber, and‘the' same apparatus,‘ .
shown in Fig. 5, a tubular‘ rubber mass 23*may be‘
premolded and vulcanized to have anoutsidedi
used for molding and vulcanizing rubber, may
ameter‘slightly larger than the inside diameter‘ 55 be usedin the present case.
‘
I
Contrary to expectations on’ the basis of the
of the cup-like metal sleeve 24; or the‘ central
bore of the rubber mass 23 which'is to receive
prior 'art, I‘ha‘ve‘ discovered that rougheningl or"
the metal rod 25‘ may be constructed slightly
serrating the surfaces of the rubber-adherent
metal prior to the application of a premolded,
smaller than the‘outside diameter: of ‘saidmetal
rod.‘ The rubber mass is inserted into the sleeve 60 prevulcani‘zed metal-adherent“ rubber composi- '
25 and the rod Z5~into the central'bore of the
tion‘thereto reduces the union between the rub
rubber. Intimate contact is maintained between
ber and metal to such an extent, when it is sub»
the metal‘ surfaces and‘the-rubber- mass‘ by the
jected to heat and pressure‘; that onlyva'pa‘rtial
oversized ‘construction of the rubber or of the rod
or very‘inferio'r bond is produced. ‘Thus; when
25; Application ofjpressure at the surface 26 of 65 it is‘ desired to reduce the bond between the rub;
the rubber con?nes it within the sleeve and causes
ber'eadh'eren‘t ‘metal surface‘ and‘ that‘ of \ rubber '
positive"pressurettorbe'maintained at’th'e'rubber
bonded thereto; it is’ merely necessary to‘ pro
vide grooves 011 the surface ‘or otherwise roughenr
metal ‘conta‘ct‘surfaces: The'temperature is'raised“
sufficiently" tobond'the rubber to ‘the metal, re‘-‘
it locally before bringing the‘ surface of the metal
70 and the rubber‘ substance into direct’ contact. ‘If
metal‘ article’ in: which the“ metal" is‘ securely‘
this is done‘solely on a portion of ‘the metal sur
sulting: in "the" formation “ of -‘ a: composite ‘rubber
bonded‘ to? the " rubber.
_
'
According to‘theistructure illustrated in Figs. 6.
and“ 7, ,one‘h‘alf‘ 32 ‘of the *mo‘ld‘may-"be'rprovided “
face contacting the rubber, while the remainder
of the 'said surfa‘ce'is continuous,‘ smooth, clean
and'polished,‘ the ‘bond “will occur“, only‘ at the‘ lat‘
with“ cavities“ 36" forrshaping “ rubber“ ‘pieces, while“ 75 ter'portions; n'o secure-bond being obtained where ‘"
2,409,759
12
11
the metal is roughened. A surface of this type
is illustrated in Fig. 8, wherein roughened
grooves 39 are provided on the surface of a
rubber-adherent metal 40 to which a mass of
article of the class consisting of brass and bronze
articles; placing said cuprous alloy article and an
untreated surface of the mass of prevulcanized
rubber in a mold; applying su?icient pressure to
the mold to maintain a pressure of at least 300
rubber M is to be bonded according to the present
pounds per square inch at the contact surface of
invention. The remainder of the surface 42 is
the rubber with the cuprous alloy article; and
continuous, smooth and polished. When the rub
heating at a temperature of from 300 to 320° F.,
ber is bonded according to the present process,
until the rubber is bonded to the polished surface
secure bonding occurs only at the portions 42 of
the said surface, while at the portions 39 sub 10 of the cuprous alloy article.
5. In the art of bonding a metal-adherent rub
stantially no bonding in the sense used herein
is produced.
ber substance, compounded to be directly bond
able to metal, to a smooth, polished and con
Variations and modi?cations may be made
tinuous rubber-adherent surface of a cuprous
within the scope of this invention and portions
of the improvements may be used without others. 15 alloy of the class consisting of bronze or brass to
which said rubber substance is adapted to be
I claim:
bonded directly, the steps which comprise pre
1. The art of bonding a completely cured metal
vulcanizing a mass of said rubber substance;
adherent rubber composition directly to a cu
bringing an untreated surface of said prevul
prous alloy article of the class consisting of brass
and bronze articles, comprising the steps of pro 20 canized mass of rubber substance into direct con
tact with said rubber-adherent surface; and sub
viding said cuprous alloy article with a clean,
jecting the rubber substance and alloy to heat and
continuously smooth polished surface; bringing
an untreated surface of the cured rubber com
pressure suflicient to cause cohesion between the
contacting areas of said rubber substance and
position into direct contact with said polished
cuprous alloy surface; maintaining sufficient 25 surface.
6. The art of bonding a metal-adherent rubber
pressure at the rubber-metal interface to in
substance directly to a smooth, polished and con
sure intimate contact between the rubber and the
tinuous rubber-adherent surface of a cuprous
cuprous alloy; and applying sufficient heat to
alloy of the class consisting of bronze or brass,
cause the rubber to adhere to said alloy surface.
which comprises partly curing said rubber sub
2. The art of bonding a partially cured mctal~
stance; bringing an untreated surface of the
adherent rubber composition directly to a cuprous
partly cured rubber substance into direct contact
alloy article of the class consisting of brass and
with said rubber-adherent surface; and subject
bronze articles, comprising the steps of providing
il'ig the rubber substance and alloy to sui?cient
said cuprous alloy article with a clean, continu
heat and pressure to completely cure said rubber
ously smooth polished surface; bringing an un
treated surface of the partly cured rubber compo
substance and to cause the latter to cohere to the
sition into direct contact with said polished
areas of said rubber-adherent surface in contact
cuprous alloy surface; maintaining sufficient
therewith.
,
7. The art of bonding a metal-adherent rubber
pressure at the rubber-'netal interface to insure
intimate contact between the rubber and the 40 substance directly to a smooth, polished and con~
cuprous alloy; and applying sufficient heat to
completely cure the rubber, and to cause the rub
ber to adhere to said alloy surface.
3. A method of forming a composite rubber and
metal article wherein the rubber is securely
bonded directly to the surface of a cuprous alloy
article of the class consisting of brass and bronze
articles, which comprises compounding a rub
ber composition to contain, in addition to a suit
able quantity of a crude rubber substance, a suit
tinuous rubber-adherent metal surface, which
comprises bringing an untreated surface of a ma
terial of a class consisting of cured and partially
cured substance into direct contact with said
rubber-adherent surface of a cuprous alloy of the
class consisting of bronze or brass; and subjecting
the rubber substance and alloy to heat and pres
sure su?icient to cause cohesion between the con
tacting areas of said rubber substance and rub
ber-adhering surface.
ableportion of sulphur, a mercapto-aryl-thiazole
8. In the art of bonding a metal-adherent rub
accelerator, stearic acid as a softener, and a pro—
ber substance, compounded to be directly bond
able to metal, to a rubber-adherent alloy of the
class consisting of brass and bronze to which said
rubber substance is adapted to be bonded di
rectly, the steps which comprise providing said
alloy with a clean, bright, continuously smooth
polished surface; prevulcanizing said rubber sub
portion of chemically pure zinc oxide; prevul
canizing a quantity of said compound in the de
sired shape; placing an untreated surface of the
prevulcanized rubber compound and a cuprous
alloy article of the class consisting of brass and
bronze articles having a continuously smooth,
stance; placing an untreated surface of said pre
clean, polished surface in a mold; applying suf?
cient pressure to maintain intimate contact at 60 vulcanized rubber substance in direct contact
the rubber-metal interface; and applying suffi
cient heat to cause bonding of the rubber to the
. surface of the metal article.
4. .A method of forming a composite rubber and
metal article wherein the rubber is securely
bonded directly to the surface of a cuprous alloy
article of the class consisting of brass and bronze
articles, which comprises compounding a rubber
composition to contain, in addition to a suitable
quantity of a crude rubber substance, a suitable
proportion of sulphur, a mercapto-aryl-thiazole
accelerator, stearic acid as a softener, and a pro
portion of chemically pure zinc oxide; prevulcan
izing a quantity of said compound in the desired
shape; polishing the surface of a cuprous alloy
with said polished rubber-adherent alloy surface;
and subjecting the rubber substance and alloy to
heat and pressure su?cient to cause cohesion be
tween the contacting areas of said rubber sub
stance and the polished surface of the rubber
adherent alloy.
9. In the art of making composite rubber and
metal articles in which the rubber is securely
bonded directly to the metal, the steps which
comprise prevulcanizing a mass of directly metal
adherent rubber substance; applying a piece of
a rubber-adherent alloy of the class consisting of
brass and bronze having a smooth, polished and
continuous surface to which said rubber is adapt
ed to be directly bonded, in surface contact with
2,409,759
‘
13
to;.cohere;,directly, in asmold adapted1to. con?ne‘
the-iirubber-iagainsti distortion, with ‘an untreated
surfaceohthe rubber compositioniin‘ direct con;
tact with said'rubber-adherent surface; applying
an untreated‘; surface. of,“ saidlrubberl substance ;
and applying‘: suf?cient “heat: and pressure to: said:
alloy ‘piece and ‘ rubber; substance - to cause-cohe
sionib'etween‘ .the ‘contacting, areas of. theirubber
andzalloy:
1
10. In thelartpflmaking: a composite-‘rubber,
5 suf?cientr pressuretothe mold ‘to ‘maintain a sub
stantialipositive pressure. atJthe contact surface
and metaliarticle, thesteps aWhiCll comprise pre
of~,the;metal piece and‘ithe-mass, of prevulcanized
rubberg-oomposition; and‘: heating; thecontents: of
vulcanizing a mass of a directly metal-adherent‘
rubber-substance; securinga thin continuous lay
the; mold: at vaztemneraturerof the same ,order- as
er of a rubber-adherent alloy of the class consist
ing of brass and bronze to which said rubber sub
that required to vulcanize the rubber until the
rubber is bonded to the rubber-adherent surface
stance is adapted to be directly bonded,‘to the
of the article.
surface of a metal piece to which the rubber is
‘
14. In a process of forming a composite article
to be bonded; polishing said rubber-adherent al
loy layer to render it continuously smooth, clean
of metal and rubber substance, the steps which
comprise premolding and precuring a body of a
and bright; bringing an untreated surface of said
prevulcanized mass of rubber into direct contact
rubber substance, compounded to cohere directly
to a rubber-adherent metal, in the desired shape;
exposing one surface of the molded rubber With
out stripping the rubber from the mold; applying
and metal to heat and pressure sufficient to cause 20 an alloy piece of the class consisting of bronze
cohesion between the contacting areas of said
and brass having a continuously smooth clean
rubber substance and the polished layer of rub
polished surface of the said alloy to which the
ber-adherent alloy.
said rubber substance is adapted to cohere di
11. In a method of forming a composite and
rectly, to the untreated exposed surface of the
rubber-metal article wherein the rubber is se 25 molded rubber substance, the polished surface
curely bonded directly to the surface of a metal
of said alloy forming direct contact with the ex
piece, the steps which comprise prevulcanizing a
posed rubber substance; reclosing the mold; and
mass of a rubber composition adapted to cohere
app-lying suflicient heat and pressure to bond the
directly to the metal of said article in the desired
rubber directly to said alloy surface.
shape; placing said mass of prevulcanized rubber
15. In a method of making a composite rubber
composition and a piece of metal, having a
and metal article wherein the rubberportion is
smooth, polished and continuous surface of a
securely bonded directly to- the surface of a metal
cuprous alloy of the class consisting of bronze or
piece, the steps which comprise preforming and
brass to which said rubber composition is adapted
at least partially prevulcanizing said rubber por
to cohere directly, in a mold adapted to con?ne D) ;'V. tion from a metal-adherent rubber composition,
adapted to be bonded directly to metal; assem
the rubber mass against distortion, an untreated
with the polished surface of said rubber-adherent
alloy layer; and subjecting the rubber substance
surface of said rubber mass being in direct con
bling said preformed rubber portion with an un
treated surface in the desired relation with a
tact with said alloy surface; applying sufficient
pressure to the 111016.130 maintain intimate contact
piece of metal of the desired shape having a
between the surface of the metal piece and the if) smooth, polished and continuous surface of a
prevulcanized rubber composition; and applying
cuprous alloy of the class consisting of bronze or
sui?cient heat to cause bonding of the rubber to
brass to which said rubber composition is adapted
the alloy surface of said metal piece.
to be directly bonded, the rubber being in direct
12. In a method of forming a composite rubber
contact with said surface; and applying sufficient
and metal article wherein the rubber is securely vi heat to bond the rubber to the metal while main
bonded to the surface of a metal piece, the steps
taining a substantial pressure at the rubber
which comprise prevulcanizing a mass of a rubber
metal interface throughout the bonding operation
composition adapted to cohere directly to the
metal of said article, in the desired shape; placing
said mass of prevulcanized rubber composition
and a piece of metal, having a smooth, polished
to insure intimate pressure contact between the
rubber and the surface.
16. In a method of making a composite rub
ber and metal article wherein the rubber portion
is securely bonded directly to the surface of a
and continuous surface of a cuprous alloy of the
class consisting of bronze or brass to which said
rubber composition is adapted to cohere directly,
in a mold adapted to con?ne the rubber mass
against distortion, an untreated surface of said
rubber mass being in direct contact with said
alloy surface; applying sufficient pressure to the
mold to maintain a substantial positive pressure
at the contact surface of the metal piece with the
prevulcanized rubber composition substantially
perpendicular to said contact surface; and apply
ing sufficient heat to cause bonding of the rubber
to the surface of said metal piece.
13. In a method of forming a composite rubber
metal piece, the steps which comprise preforming
and precuring said rubber portion from a metal
ardherent rubber composition adapted to be di
rectly bonded to metal; providing a piece of metal
of the desired shape with a continuously smooth
clean polished surface of an alloy of the class
consisting of bronze and brass to which the said
L. rubber composition is adapted to cohere directly;
assembling said preformed rubber portion in the
desired relation with said rubber-adherent sur
face with an untreated surface of the rubber in
direct contact with said surface; and applying
’ su?icient head to bond the rubber to the surface
and metal article, wherein the rubber is securely
while maintaining a substantial pressure at the
bonded directly to the surface of a metal piece,
the steps which comprise prevulcanizing a mass
of a rubber composition adapted to cohere directly
to the metal surface of said metal piece, in the
desired shape; placing said mass of prevulcanized
rubber composition and a piece of metal having a
smooth, polished and continuous surface of a
cuprous alloy of the class consisting of bronze or
brass to which said rubber composition is adapted 75
interface throughout the bonding operation to
insure intimate pressure contact between the
rubber and the rubber-adherent surface.
17. In a method of forming a composite rubber
and metal article wherein the rubber is securely
bonded directly to the surface of a metal piece,
the steps which comprise preforming and at least
partially prevulcanizing a rubber composition
adapted to be adhered to the surface of the said
2,409,759
15
metal piece in the desired shape; placing said
preformed rubber composition and said metal
piece, having a smooth, polished and continuous
rubber-adherent surface of‘ a cuprous alloy of
the class consisting of bronze or brass to which
said rubber composition is adapted to cohere di
rectly, in a mold adapted to con?ne the pre
formed rubber against distortion, an untreated
surface of said rubber being in direct contact
16
with said rubber-adherent surface, applying suf
ficient pressure to the mold to maintain intimate
contact between the said surface of the piece and
the preformed rubber composition; and applying
suf?cient heat to cause bonding of the rubber to
“the surface of the metal article, said heat being
at least suf?cient to completely vulcanize the
rubber.
OAKLEY W. HOSKENG.
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