United States Patent 0 ”
3,781,205
Patented Dec. 25, 1973
2
1
from the group consisting of aromatic polyamides, carbon,
COMPOSITE BEARINGS
3,781,205‘
graphite, aromatic polysulfones, aromatic polyimides and
aromatic polyester-imides.
James Cairns and Nicholas Walton, Cherry Hill, N.J.,
assignors to Garlock, Inc., Palmyra, N.Y.
No Drawing. Filed Feb. 2, 1970, Ser. No. 8,065
signi?cantly increased load carrying capacity with in
Int. Cl. C10m 7/34
US. Cl. 2S2-12.6
12 Claims
The bearings of the invention are characterized by a
creased temperature as compared with PTFE ?ber-lined
bearing structures. By incorporating high temperature re
sistant solid lubricants in the interstices of the ?bers form
ing the low friction face of the bearings of the invention,
ABSTRACT OF THE DISCLOSURE
A composite bearing comprising a backing member to
which there is secured a dimensionally stable bearing sur
face layer comprising -a solid lubricant selected from the
group consisting of the sul?des, selenides, and tellurides
of molybdenum, tungsten, and titanium, lead diiodide,
boron nitride, carbon, graphite, and polytetra?uoroethyl
ene and ?bers of a material characterized by a heat dis
tortion temperature exceeding that of polytetra?uoro
ethylene and selected from the class consisting of aromatic
polyamides, carbon, graphite, aromatic polysulfones, aro
matic polyimides and aromatic polyester-imides.
10 they may be made to equal and to exceed the bearing
life of comparable PTFE ?ber-faced bearing structures.
Moreover, the ?brous materials used to provide the bear
ings of the invention are not handicapped by the non
adhesive properties characteristic of PTFE. Accordingly,
the ?bers used in forming the low friction surface of the
bearings of the invention can be easily and conveniently
bonded to the backing or supporting structure with con
ventional adhesives and cements without the necessity of
employing intricate interweaving operations for producing
20 a composite ?ber or a compound woven fabric in order
to facilitate bonding to the backing member as was here
tofore necessary when using PTFE ?bers.
Generally, any of the well known carbon and graphite
?bers may be used to provide the bearing surface of the
BACKGROUND OF THE INVENTION
25 bearings of the invention. For example, graphitized mono
Field of the invention
?laments or ?bers of the type described in US. Pat.
This invention relates to plain bearings and, more par
3,107,152 can be used.
.ticularly, to a composite bearing structure including a
The aromatic polyamides useful in the practice of the
high tensile strength, dimensionally stable bearing surface
invention include the linear polymers produced by the
including a solid lubricant and ?bers of a material char 30 interfacial polycondensation of an aromatic dibasic acid
acterized by a heat distortion temperature greater than
that of polytetra?uoroethylene.
chloride such, for example, as phthaloyl chloride, iso
phthaloyl chloride or terephthaloyl chloride, with an aro
matic diamine such, for example as ortho-, meta- or para
DESCRIPTION OF THE PRIOR ART
phenylenediarnine, bezidine or 4,4’-diaminodiphenylmeth
Composite bearings whose low friction or hearing sur 35 ane. A particularly preferred aromatic polyamide is poly
(m-phenyleneisophthalamide) produced and marketed by
faces are composed of ?bers of polyetetra?uoroethylene
the Du Pont Company under the trade designation
(hereinafter PTFE) are known, and are described, for ex
“Nomex” and characterized by a breaking strength at 482°
ample, in US. Pats. Reissue 24,675-—White; 2,953,4l8—
F. equivalent to 60% of that at room temperature. Other
Runton et al.; 3,110,530—Herman; 3,131,979-Sh0bert;
and 3,328,100-Spokes et al. Such composite bearings gen 40 suitable aromatic polyamides useful in the practice of
this invention as well as methods ‘for their preparation are
erally include a bearing surface layer formed of PTFE
?bers which are interwoven with other ?bers (such as
cotton) to facilitate the bonding of the low friction bear
‘ing surface to a supporting structure. Because of the low
described in New Linear Polymers, by Lee, Sto?Fey and
Neville, McGraw Hill Book Company, 1967, whose dis
closure, by reference, is hereby incorporated as part of
coe?icient of friction of PTFE and the increased physical 45 the disclosure of this invention.
The aromatic polysulfones useful in the practice of the
properties of the material in ?ber form, such bearing struc
invention include the linear, high molecular weight poly
tures have found wide acceptance in applications where
aryl sulfones such, for example, as may be produced by
relatively high bearing loads are encountered. However,
reacting the disodium salt of an aromatic dithiol with a
the inherent characteristics of PTFE have severely re
stricted use of such composite bearings in high tempera 50 dihalodiphenyl sulfone. Speci?c examples of starting ma
terials and methods used in- preparing aromatic polysul
ture-high load applications. Speci?cally, PTFE is dimen
fones are described in the aforesaid text New Linear
sionally unstable in the sense that it deforms more easily
Polymers. A preferred polysulfone useful in the practice
under load as the temperature is increased either by en
of the invention is obtained by reacting the disodium salt
vironmental temperature change or frictional heat, and is
unfortunately characterized by a heat distortion tempera 55 of bisphenol-A with p,p'-dichlorodipheny1sulfone in di
methyl sulfoxide and chlorobenzene.
ture which is unacceptable for applications in which high
The aromatic polyimides useful to provide the bearings
loads are encountered at elevated temperatures. In fact,
of the invention include the aromatic polyimides made by
PTFE ?bers exhibit a zero strength temperature of 590° F.
reacting a dianhydride such, for example, as pyromellitic
SUMMARY OF THE INVENTION
60 dianhydride, with an aromatic diamine such, for example,
as meta- or para-phenylenediamine. A speci?c example
It is accordingly a primary object of the invention to
of a polyimide which may be used is the high molecular
provide a composite bearing structure including a bearing
weight polymeric product of the reaction of 4,4’ diamine
surface layer comprising a solid lubricant and ?bers which
diphenyl methane with pyromellitic dianhydride. Further
exhibit good dimensional stability and which are useful in
high temperature applications in which PTFE ?ber bear 65 examples of typical diamines and dianhydrides useful in
the production of polyimides such as may be used in the
ings exhibit increased deformation and wear. Brie?y
practice of the invention are disclosed in the text New
stated, the composite bearing according to one form of
Linear Polymers referred to above.
the invention comprises a backing member to which there
The aromatic polyester-imides that may be used to
is secured a high tensile strength, dimensionally stable
bearing surface including a solid lubricant and ?bers of a 70 provide the low friction bearing surface layer in accord
ance with the present invention include the reaction prod
material characterized by a heat distortion temperature
ucts of an aromatic diamine, such as m-phenylenediamine,
exceeding that of polytetra?uoroethylene and selected
3
3,781,205 '
with a dianhydride containing aromatic esterv links such,
for example, as may be prepared by the reaction of tri
4
suitable metal backing-or housing such as, for example,
composed of iron, steel, copper, aluminum, brass, bronze,
mellitic anhydride with a diacetoxy derivative of an
nickel, or titanium. Metal backings of this type lend them
aromatic diol, preferably hydroquinone. A speci?c aro~
selves to platen-press manufacture of composite bearing
material of the invention. In addition, the metal backings
are useful in the production of coils of the composite
material from which the bearings of the invention may
matic polyester-imide which can be used in the practice
of the invention is the polymeric product of the reaction
of m-phenylenediamine with p-phenylene-bis(trimellitate
anhydride). Other suitable starting materials and methods
employed in the preparation of aromatic polyester-imides
be economically produced.
of the type which may be used in the practice of this
invention are disclosed in the text New Linear Polymers
referred to above.
Each of the foregoing materials useful in the practice
surface layer (or low friction lamina) to the backing
member (or supporting lamina) to provide the composite
bearing in accordance‘ with the invention may be any
The adhesives which may be used to secure the bearing
of the well known high temperature adhesives or bonding
of the invention, i.e. aromatic polyamides, carbon,
resins which do not unduly decompose at the tempera
graphite, aromatic polysulfones, aromatic polyimides, and 15 tures at which the bearing surface is to be used, and
aromatic polyester-imides are characterized by heat de
?ection temperatures (as measured by A.S.T.M. Test
Method D-648) exceeding that of PTFE, i.e., exceed 250°
which have the capacity to assure a good, high strength
bond between the ?brous low friction layer and the par
ticular backing material employed. In general many of
F. at 66 p.s.i. ?ber stress, and exceed 130° F. at 264 p.s.i.
the epoxy, modi?ed epoxy, polyimide, phenolic, or poly
?ber stress.
20 ester adhesives may be advantageously employed. Ex
The hearing or low friction surface layer of the bear
amples of suitable adhesives include “Epoxylite 5403”
ings of the invention can include a single layer or, if
and “Epoxylite 6203” sold by Epoxylite Corporation;
preferred, multiple layers of ?bers or yarns of at least
“Leal C" sold by the Leal Company; and “ERL 256” sold
one of the foregoing materials. The ?bers comprising the
by Union Carbide. Other suitable adhesives include
low friction face of the bearing can be braided or woven. 25 phenolic cements such as “Armstrong N-l01” sold by
If desired, a combination of two or more different ma
Armstrong Cork Company and “Resinox EXEL 533”
terials of the kind described above can be employed to
and “Resinox EXEL 530” sold by Monsanto. Polyimide
provide a composite ?ber or compound woven fabric for
cement such as “Metabond 840” sold by Whittaker Cor
use in preparing the bearing surface.
poration may also be used.
To produce a sleeve bearing in accordance with the
The solid lubricant employed to enhance the low fric
invention, a strip or tape woven of yarns or threads of
tion characteristics of the bearings of the invention is
the selected low friction material may be wrapped over a
generally in the form of ?ne particles, and can be dis~
mandrel to form a compact inner bearing surface com
persed in the resin used to impregnate either the low fric
posed of the yarns or threads of the low friction material.
tion fabric or ?bers, or the fabric or ?bers used to pro~
Alternatively, the yarns or threads of the selected low 35 vide the reinforcing backing member. Alternatively, the
friction material may be wound or braided over the
solid lubricant can be dispersed throughout the adhesive
mandrel under tension in any other suitable form, as
used to secure the low friction fabric layer to the backing
for example, in a pair of crossed helical layers of op
member. Thus, the solid lubricant particles can be present
posite pitch to form a compact inner bearing surface com
at the bearing surface and throughout the interstices in
posed entirely of the yarn employed. The yarn used in 40 and between the ?bers forming the bearing surface.
the practice of the invention can be formed of mono?la
The solid lubricants useful to provide the bearings of
ment thread or of a twisted thread made of smaller com
the invention can be selected from the sul?des, selenides
ponent ?bers of the material selected. If desired, the
and tellurides of molybdenum, tungsten and titanium,
yarns or threads can be preimpregnated with a suitable
lead diodide, boron nitride and carbon, graphite or PTFE.
resin impregnant adhesive to facilitate bonding with the 45 The resin impregnant or adhesive in which the solid lubri
backing member as will be described below.
cant is distributed can include up to 30% by weight of
After the desired thickness of ?bers or yarns has been
the solid lubricant. The term “solid lubricant” as used
wrapped, wound, or braided about the mandrel, the as
herein is meant to embrace a solid lubricant composition
sembly can be over-wrapped with the required thickness
which does not decompose unduly at 300° C., readily
of ?lament winding or with a wrapping of structural resin 50 smears on metal surfaces and, when tested in a dynamic
preimpregnated fabric to provide the reinforcing member
of the composite bearing. Examples of suitable material
for use in this connection are glass/epoxy, glass/poly~
friction testing machine between two metal surfaces,
shows a coe?icient of friction below 0.15.
A preferred form of the invention comprises a com
ester, glass/phenolic, linen/phenolic and cotton/phenolic.
posite bearing structure whose low friction surface in
Other ?laments, fabrics and suitable resin impregnants for 55 cludes a solid lubricant and a woven fabric of carbon
providing the backing member will readily occur to those
or graphite ?bers adhesively secured to a rigid metal back
skilled in the art.
ing, as of steel for example. The low friction characteris
Upon completion of the application of the ?lament
tics of such a structure are enhanced by utilizing particu
winding or the fabric wrapping, the resin impregnant is
late PTFE, with or without one or more particulate ?ller
cured by conventional techniques and the assembly cooled 60 materials, as the solid lubricant. In this connection, PTFE
and subsequently removed from the mandrel. The amount
of ?nish machining, if any, will depend upon the toler
ances required in a speci?c bearing application. Shaft
bushings with the bearing surface on the outside can be
impregnated graphitized mono?laments or ?bers of the
type described in U .3. Pat. 3,107,152 may be used. Alter
natively, a mixture of particulate PTFE and ?ller, if de
sired, may be spread evenly over the low friction carbon
produced by reversing the foregoing procedure. Similarly, 65 or graphite ?ber surface of the composite bearing, and
?at stock and other forms can be produced by laminat
the thus coated, bearing compressed under sufficient heat
ing a woven cloth composed of the desired low friction
and pressure to cause the particles to penetrate into and
throughout the interstices in and between the graphite or
material of the type described to an appropriate resin
carbon ?bers and to sinter the PTFE. If desired, the par
preimpregnated fabric.
As will be appreciated by those skilled in the art, other 70 ticulate PTFE (and ?ller, if any) may be applied to the
woven carbon or graphite low friction surface of the
rigid backing or supporting members may be employed
composite bearing in the form of a thin, ?exible mat such,
_to provide the composite bearing structures of the in
vention. For example, the low friction bearing surface in
for example, as described in British Pat. 1,163,950. Ex
amples of speci?c PTFE materials as well as suitable
cluding the ?bers of the materials herein contemplated
can be bonded through the means of an adhesive to a 75 ?llers are set forth in the aforesaid British patent which
5
3,781,205
is, by reference, incorporated as part of the disclosure of
this invention.
As will be appreciated by those skilled in the art, the
present invention contemplates composite bearing struc
6
and a rigid supporting lamina bonded to said low fric
tion bearing lamina by means of said resin bonding
material.
'
tures which include at least two components: (1) a low
friction bearing surface lamina including a solid lubri
2. The bearing of claim 1 wherein the solid lubricant
is selected from the group consisting of the sul?des,
selenides, and tellurides of molybdenum, tungsten, and
cant and ?bers of one or more of the aforementioned
titanium, lead diiodide, boron nitride, carbon, graphite,
materials, and (2) a rigid supporting backing lamina ad
and polytetra?uoroethylene and wherein the bonding ma
terial is selected from the group consisting of polyepoxy,
hesively secured to the low friction surface. In general,
the rigid supporting structure or backing will be composed 10 polyimide, phenolic, and polyester adhesives.
of a material other than that used to provide the bearing
or low friction surface. However, it is within the purview
of the invention to construct the backing lamina of the
same material, of which the ?bers are formed, which ma
3. The bearing of claim 1 in which said yarns
are
formed of poly(m-phenyleneisophthalamide).
4. The bearing of claim 1 in which said yarns
formed of carbon.
5. The bearing of claim 1 in which said yarns
terial has been so modi?ed or treated to render it suffi
ciently rigid to provide the support necessary in ‘any
speci?c bearing application. For example, where the bear
are
are
formed of graphite.
6. The bearing of claim 1 in which said yarns
formed of an aromatic polysulfone.
the preferred materials, the backing member may com
7. The bearing of claim 1 in which said yarns
prise additional layers of such cloth that have been im 20 formed of an aromatic polyimide.
are
8. The bearing of claim 1 in which said yarns
are
ing surface is formed of a cloth woven of ?bers of one of
pregnated with a reinforcing resin which is subsequently
cured to provide the desired rigidity. Alternatively, the
are
formed of an aromatic polyester-imide.
9. The bearing of claim 1 in which the solid lubricant
?brous bearing surface of one of the preferred materials
can be adhered to a reinforcing backing molded of the
comprises particulate polytetra?uoroethylene.
identical material. Consequently, while from a structural 25
10. The bearing element of claim 1 wherein said rigid
standpoint the bearings of the invention are considered to
supporting lamina comprises a cured, hardenable resin
be and have here been referred to as “composite bearings”
including resin bondable reinforcing ?laments of ?bers
it should be understood that the supporting backing and
embedded therein.
the ?brous low friction surface layer can be composed of
11. The bearing of claim 1 in which said backing mem
the same material.
30 ber comprises a rigid metal structure.
It should be understood that while the present inven
, 12. The bearing of claim 9 in which the solid lubricant
tion has been described in considerable detail with respect
comprises particulate polytetra?uoroethylene.
to certain speci?c embodiments thereof, it is not to be
References Cited
considered limited to those embodiments, but may be used
in other ways without departure from the spirit of the 35
UNITED STATES PATENTS
invention or the scope of the ‘appended claims.
3,533,668 10/1970 Tunis _____________ __ 252-12
What is claimed is:
3,629,103 12/ 1971 Korshak et a1. _____ __ 252-12
1. A bearing element comprising a composite structure
including, in combination,
a low friction bearing lamina consisting essentially of 40
yarns formed of mono?lament thread, multi?lament
thread or of a twisted thread made up of small com
ponent ?bers of a material characterized by a heat
de?ection temperature as measured by A.S.T.M. Test
Method 'D-648, exceeding 250° F. at 66 p.s.i. ?ber 45
stress and exceeding 130° F. at 264 p.s.i. ?ber stress,
and selected from the class consisting of aromatic
polyamides, carbon, graphite, aromatic polysulfones,
aromatic polyimides and aromatic polyesterimides,
said yarns forming said lamina being impregnated with
3/1972
Mizuno __________ __ 252—12.2
10/1963
2/ 1967
Ford et al. _______ __ 23-2092
Le Brasse et a1. ____ __ 252-12
2,849,414
2,953,418
3,110,530
3,131,979
3,405,063
8/1958
9/1960
11/1963
5/1964
10/1968
Stott ______________ _._. 252-12
Runton et a1 ________ __ 252-12
Herman _________ .__ 252-12.2
Shobert __________ __ 252-12.6
Boes et a1. _________ __ 252-12
3,480,547
11/ 1969
Van Dyk _________ __ 252-12.6
3,567,504
3/1971
Hopkins et a1. ______ 252-12.4
FOREIGN PATENTS
1,124,781
767,820
1,163,950
a resin bonding material,
said lamina including, in the interstices in and between
the yarns forming said lamina, particles ‘of a solid
lubricant selected from the group consisting of in
organic compounds, elements, and organic polymers 5
which does not decompose unduly at 300° C., which
readily smears on metal surfaces, and which when
tested on a dynamic friction testing machine between
two metal surfaces shows a coefficient of friction be
low 0.15,
3,647,500
3,107,152
3,305,325
8/1968
2/1957
9/1969
Great Britain _______ .__ 252-12
Great Britain ______ __ 252-12
Great Britain ______ .._ 252-12
vDANIEL E. WYMAN, Primary Examiner
I. VAUGHN, Assistant Examiner
US. Cl. X.R.
252-12, 12.4
60
\
'29)‘???
f iUNl'l‘l'll) s'rA'ms PATENT OFFICE
‘
CERTIFICA'L‘E OF CORRECTION
Patent'No.
317811205
7
Dated December 25, 1973
Inventory“) James Cairns and Nicholas Walton
It is certified that error appears in the above-identified patent
_ and that said Letters Patent are hereby corrected as shown below:
r.
COlumn 6, Claim 12 should be made dependent from claim ll,'
and
should ‘read as
follows:
'
‘
‘
\-
~
'12. The bearing of claim -11 in‘ which the
solid lubricant comprises particulate
polytetrafluoroethylene.
'
1
'
_ SignedIand' sealed this 9th day of July-‘1974.
(SEAL)
Attest:
i
I
I
'
‘
'
’
MCCO/Y M. GIBSON, JR;
Att'e's'ting Officer
7 ‘
'
.
a
'
C. MARSHALL DANN
Commissioner of Patents