Document 3N1RzLvBZzy6mZneykKrDX913
FILE NAME Brakes BRK
DATE 1986 DOC BRK192
DOCUMENT DESCRIPTION European Patent Application
19
Europ^/ischesPatentamt European Patent Office Office europ^'endes brevets
11 Publication number
0 194 989 A2
12
EUROPEAN PATENT APPLICATION
21 Application number 86870033.7
22 Date of filing 13.03.86
Cl.4 F 16 D 69/02
30 Priority 14.03.85 US 711894
14.03.85 US 711893
43 Date of publication of application
17.09.86 Bulletin 86/38
Designated Contracting States
AT BE CH DE FR GB IT LI LU NL SE
71 Applicant Monsanto Company
Patent Department 800 North Lindbergh Boulevard St. Louis Missouri 63167
72 Inventor Crutchfield Marvin Mack
1529 Cerulean Drive Creve Coeur Missouri 63146
72 Inventor Griffith Edward Jackson
310 Coventry Lane Manchester Missouri 63021
72 Inventor John HinkebeArinon ld
2450 Barrett Station Road Ballwin Missouri 63021
74 Representative Lunt John Cooper et al Monsanto Europe S.A. Patent Department Avenue de Tervuren 270-272 Letter Box No 1 1150 Brussels
Friction material composites containing crystalline phosphate fibers and a process for the preparation thereof
Asbestos friction material composites containing asbestiform crystalline calcium M phosphate fibers wherein M is a metal cation selected from the group consisting of sodium and lithium and mixtures thereof are useful as brake pads brake linings clutch facings and the like where friction material composites are needed Such composites are prepared by a blending asbestiform crystalline calcium M phosphate fibers wherein M is a metal cation selected from the group consisting of sodium and lithium and mixtures thereof a thermosetting based binder e@
AZ particulate friction modifier and a particulate inorganic filler to form a uniform mixture b placing the mixture within a mold cavity having a shape approximately that of the desired composite and c compressing the mixture at a tempera-
989 ture and a pressure and for a time sufficient to form the asbestos friction material composites
194
"
HE
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60460 94989
FRICTION MATERIAL COMPOSITES CONTAINING
CRYSTALLINE PHOSPHATE FIBERS AND A PROCESS FOR
THE PREPARATION THEREOF
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to asbestos
friction material composites and a process for the preparation of such composites More particularly
this invention relates to asbestos friction
10
material composites containing asbestiform crystal-
line calcium M phosphate fibers wherein M is a metal
cation selected from the group consisting of sodium
and lithium and mixtures thereof and a process for
the preparation The friction material composites are
15
suitable for use as brake pads brake linings clutch
facings and other similar uses where friction material
composites are needed
Description of the Prior Art
Friction material composites for use as
20
brake elements in automotive truck bus or similar
vehicles are known in the art In general such com-
posites contain asbestos fibers as an inorganic
fibrous reinforcement material The popularity
enjoyed by asbestos fibers for such uses resides in
25
the fact that asbestos has been considered to be
relatively inexpensive is easily preformed and pro-
vides a brake element having excellent wear durability friction and strength properties However
asbestos has recently been found to expose workers
30
making or installing the brake elements as well as
the public to a potentially serious health hazard
It has been determined that the inhalation of small
asbestos fibers can result in a disease known as
asbestosis in which these fibers accumulate in the
35
lungs scar lung tissue and cause many respiratory
problems It has become increasingly clear that
0194989
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43-21
inhalation of asbestos fibers over an extended period of time can lead to a cancer of the lining of the
lungs known as mesothelioma as well as lung cancer
10 15 20 25
30
In addition in the operation of conventional asbestos-
based brake some of the
elements as the brake element wears away
asbestos discharges into the atmosphere in
its fibrous form to thereby pose a potential hazard
In view of the potential hazard of asbestos material
it has become increasingly desirable to find substi-
tutes for asbestos in those applications involving the
manufacture and use of materials containing asbestos and more specifically for manufacturers of friction
materials such as asbestos brake elements to
find
suitable substitutes for asbestos U.S. Patent 4,137,214 discloses
friction
compositions containing nonasbestos fibrous materials Suitable nonasbestos materials include for example fiber glass mineral wool silica fibers carbon
fibers boron fibers and the like and tungsten
fibers or steel fibers and the like In U.S. Patent 4,278,584 an asbestos
organic friction material reportedly having favorable mechanical thermal and frictional properties is described Such materials contain phenolic resins
carbon fibers steel fibers and filler materials and are useful as brakes and clutches of automobile
and brake blocks of railroad railway vehicles
U.S. Patent 4,374,211 discloses a non-
asbestos friction material composite Such composites are comprised of a thermosetting binder a nonasbestos
fibrous material such as for example those disclosed
in U.S. Patent 4,137,214 discussed hereinabove and an effective amount of an aramid polymer an aromatic
polycarbonamide pulp fiber Such friction material
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10 15 20 25 30 35
reportedly results in good structural integrity of
preforms made therefrom
Although these prior art friction materials
are effective to eliminate asbestos in products
utilizing such friction materials none have been
found to provide strength wear resistance and fric-
tional properties comparable to those provided by
containing friction materials coupled with
economical materials and
manufacturing costs
For
example glass fibers the mixing procedures
have used
a tendency
to prepare
to fracture in the friction
compositions with the result that they contribute
poor
reinforcement Furthermore glass fibers are brittle
and tend to break down at the braking interface dur-
ing service of the brake element and high wear rates
are thereby encountered Moreover the
glass fibers have a low surface area as
nonporous compared with
asbestos and the glass fibers do not absorb products
of decomposition of the organic components caused by heat which occurs during braking As a result when
glass fibers are used as the reinforcing material friction drops precipitously at the temperatures generated during braking This friction drop due to poor absorbtion by the reinforcing fibers is known in the
brake industry as fade Similarly organic fibers
such as cotton wood pulp and rayon synthetic fibers
composed of such organic polymers as polyacrylonitrile
polyamide polyester and the like have low surface
area and exhibit poor heat resistance These latter
fiber materials tend to lose strength at temperatures in the range of 93 C - 149 C 240 F - 300 F and
break down in the same manner as the binder material
The discovery of the friction material composites of
the instant invention which exhibits properties com-
parable to and in many instances superior to
conventional containing friction material in
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10 15 20 25 30 35
wear durability friction and strength while at
the for
same time presenting no health hazard and their preparation therefore is believed
a process to be a
decided advance in the asbestos friction material
composite art
SUMMARY OF THE INVENTION
novel
It is an object of this invention to provide asbestos friction material composites con-
taining asbestiform
fibers wherein M is
crystalline calcium M phosphate
a metal cation selected from the
group consisting of sodium and lithium and mixtures
thereof which exhibit wear and strength characteristics
durability friction
comparable to or exceed-
ing those of conventional asbestos friction
material composites
health hazard
and at the same time present no
It is also an object of this invention to provide an asbestos friction material composite
which can be shaped into brake pads brake lining segments clutch facings and the like using conventional
processes
Another object of this invention is to provide a process for preparing novel asbestos friction material composites containing asbestiform crystalline calcium M phosphate fibers wherein M is a metal cation selected from the group consisting of sodium and lithium and mixtures thereof which exhibit wear durability friction and strength
characteristics comparable to or exceeding those of
conventional asbestos friction material com-
posites and at the same time present no health
hazard
Yet another object of this invention is to provide a process for preparing an asbestos friction material composite which can be shaped into
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43-21 6046 0194989
brake pads brake lining segments clutch the like using conventional processes
facings
and
These and other objects will become apparent
from the accompanying description and claims The
provision of the friction material composites objects is achieved by friction material composites which
comprise
a asbestiform crystalline calcium M
phosphate fibers wherein M is a metal
10
cation selected from the group con-
sisting of sodium and lithium and
mixtures thereof
b a thermosetting based binder
c a particulate friction modifier and
15
d a particulate inorganic filler
The provision of the process for the preparation of such friction material composites objects is achieved by a process which comprises
a blending asbestiform crystalline
20
calcium M phosphate fibers wherein
M is a metal cation selected from
the group consisting of sodium and
lithium and mixtures thereof a
thermosetting based binder a
25
particulate friction modifier and
a particulate inorganic filler to
form a uniform mixture
b placing the mixture within a mold
cavity having a shape approximately
30
that of the desired composite and
c
compressing the mixture at a temperature and a pressure and for a time
sufficient to form the asbestos
friction material composites
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10 15 20 25 30
35
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with this invention novel
asbestos friction material composites and a
process for the preparation thereof are provided The friction material composites exhibit wear durability friction and strength characteristics comparable to or exceeding those of conventional asbestos friction materials while at the same time present no health hazard Such composites
comprise
a asbestiform crystalline calcium M phosphate fibers wherein M is a metal
cation selected from the group con-
sisting of sodium and lithium and mixtures thereof b a thermosetting based binder c a particulate friction modifier and d a particulate inorganic filler The composites are prepared by a process
which comprises a blending asbestiform crystalline calcium M phosphate fibers wherein
M is a metal cation selected from
b c
the group consisting of sodium and lithium and mixtures thereof a thermosetting based binder a particulate friction modifier and a particulate inorganic filler to form a uniform mixture placing the mixture within a mold cavity having a shape approximately that of the desired composite and compressing the mixture at a temper-
ature and a pressure and for a time sufficient to form the asbestos
friction material composites
0194989
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43-21 6046
It is contemplated that in use the
asbestos friction material composites of the
instant invention may be fastened unto standard brake
shoe members by conventional means either by integral molding riveting or bonding with a rubber solventbased adhesive as desired for installation into
conventional brake assemblies
The asbestiform crystalline calcium M phos-
phate fibers wherein M is a metal cation selected
10
from the group consisting of sodium and lithium and
mixtures thereof are high molecular phosphates
CaM 3 wherein n is a number representing the
number of repeating CaM units Advantageously
such fibers have an aspect ratio average
15
diameter ratio D of at least 30 and an average
diameter in the range of from about 0.5 micron ...m
to about 20 ...m Preferred fibers are those having an
aspect ratio of from about 40 to about 100 and an average diameter from about 1 micron to about 10
20
microns Among such fibers particularly preferred
are calcium M phosphate fibers wherein M is sodium
Details of the preparation crystallinity
and other characterizing properties of asbestiform
crystalline calcium M phosphate fibers are described
25
in U.S. Patent 4,346,028 the disclosure of which is
herein incorporated by reference
It is contemplated within the scope of the
instant invention that the asbestiform crystalline
calcium M phosphate fibers may be used alone as the
30
fibrous reinforcement material or in combination with
suitable auxiliary fibers When employed the auxil-
iary fibers preferably will be present in an amount
such that the phosphate auxiliary fiber weight
ratio will be about 2/1 or higher that is at least
35
2/1 Representative of suitable auxiliary fibers are
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glass fibers mineral wool fibers aramid fibers steel fibers and the like and mixtures thereof
The thermosetting based binder mate-
rials suitable to prepare the asbestos friction
material composites of the instant invention are those which provide the desired physical properties
and characteristics in the final product and in
general may be any thermosetting resin generally known to be useful in the production of brake pads
10
brake lining segments clutch facings and the like
Representative thermosetting resins include phenol-
formaldehyde resins furfural resins melamine-
formaldehyde resins epoxy resins linked alkyd
resins diallyl phthalate resins and formalde-
15
hyde resins Preferred resins are formaldehyde
resins A formaldehyde resin suitable for use
in the instant invention is available commercially
from Schenectady Chemicals Co. Inc. as SP6416
As will be apparent to those skilled in the
20
friction art the thermosetting resins suit-
able for use in the instant invention may be used
alone or in combination with a heat and chemical
resistant vulcanized rubber Examples of such rubber
include nitrile rubber butyl rubber styrene
25
diene copolymer rubber acrylonitrile rubber and
chlorinated butyl rubber A preferred rubber is
nitrile rubber
When a rubber is used in the instant inven-
tion it preferably constitutes less than 50 of the
30
thermosetting based binder It may be incor-
porated into the asbestos friction material
composite in the form of a solution in an organic solvent such as trichlorethylene or more preferably in
the form of a powder and a vulcanizing agent --
35
sulfur mercaptobenzothiazole tetramethylthiuram
0194989
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disulfide and mixtures thereof
can be used
for example -- also
The particulate friction modifier component
employed in the instant invention is incorporated to
stabilize the coefficient of friction of the composite
materials under a variety of operating and climactic conditions to which a typical brake element will be
exposed during use so as to provide wear resistance for such composites The particulate friction modi10 fier preferably is a cashew material such as
cashew nut shell based friction particles Suit-
able cashew friction particles are an aldehyde
condensation product of cashew nut shell liquid and
are available commercially from Colloid Chemicals
15
Laboratories Inc. as Collan 10A
Particulate inorganic filler materials em-
ployed in the instant invention may be crystalline or amorphous in structure as long as they are able to maintain stability at temperatures up to 538 C
1000 F and higher Representative of
suitable
particulate inorganic filler materials include barytes barium sulfate carbon or graphite calcium car-
bonate silica and the like In general however dolomite a conventional filler is not preferred for use in the instant invention due to low normal friction exhibited by such composites It will be recog-
nized of course that this characteristic may vary
depending to some extent upon the remaining components of such composites
The particle size of the particulate materials that is the particulate friction modifier and
the particulate inorganic filler is not particularly
critical The particle sizes normally employed in friction materials are satisfactory but wide devia-
tions therefrom will have no substantial effect on
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10 15 20 25
30 35
performance Particle sizes from about 0.5 ...mto
about 500 ...mmay be used
In the practice of the instant invention
the components of the asbestos friction material composites are blended in the desired proportions in a mixer such as a Waring blender The mixed compon-
ents are then placed in a preform mold cavity having approximately the desired product shape The mixture is then compressed at ambient temperatures and at a pressure of about 18.0 MPa 2600 psi for a period of about one minute The preform is then cured by heat-
ing to a temperature
about one hour while
of about 171 C
maintaining the
340 F pressure
for at about
18.0 MPa Alternatively the preform step may be
omitted and the mixture immediately subjected to the
171 C curing step For larger test pieces which may be trimmed to any desired size by conventional means known to the art the formed pieces are sub-
jected to a post cure in drying oven at about 177 C
350 F for about four hours
Any convenient concentration ona weight
basis of the components of the asbestos friction material composites may be used In general the com-
posites of the instant invention will comprise on a weight basis from about % to about 20 of the phosphate fibers from about 10 to about 30 of the thermosetting based binder from about % to about 25 of the particulate friction modifier and from about 40 to about 70 of the particulate inor-
ganic filler In a preferred embodiment the concentration for the phosphate fiber will range from about 10 to about 17.5 for the thermosetting based binder from about 15 to about 25 for the particulate friction modifier from about 10 to about 15
for the particulate to about 65 In a
inorganic filler from about 45 most preferred embodiment the
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concentration for the phosphate fiber will be as
previously noted about 10 to about 17.5 for the
thermosetting based binder about 15 for the
particulate friction modifier about 10 with the
balance being particulate inorganic filler If de-
sired an auxiliary fiber may be substituted for a
portion of the particulate inorganic filler and
employed in combination with the phosphate fibers in
an amount such that the auxiliary fibers will consti-
10
tute about % to about 10 of the friction material
composite so long as the aforementioned phosphate auxiliary fiber weight ratio is at least 2/1 In a similar manner a rubber with nitrile rubber
being preferred may be substituted for a portion of
15
the particulate inorganic filler and employed in com-
bination with the thermosetting resin of the thermo-
setting based binder in an amount such that the
rubber will constitute about 0.5 to about % of the
friction material composite
20
The asbestos friction material compos-
ites of and prepared in accordance with the instant
invention exhibit excellent wear durability friction
and strength characteristics and at the same time
present no health hazard
25
The following specific examples illustrating
the best presently methods of practicing this
invention are described in detail in order to facili-
tate a clear understanding of the invention It
should be understood however that the detailed
30
exposition of the application of the invention while
indicating preferred embodiments are given by way of
illustration only and are not to be construed as
limiting the invention since various changes and modi-
|
fications within the spirit of the invention will
35
become apparent to those skilled in the art from this
detailed description
-12-
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10 15 20 25 30
35
EXAMPLES 1-14
a Calcium Sodium Phosphate Fibers - Asbesti-
form crystalline
prepared in five
calcium batches
sodium phosphate fibers were of 29.0 kg to 70.3 kg 64 lb
to 155 lb each by scale of the general procedures
described in the previously referenced U.S. Patent
4,346,028 In a typical preparation 20.452 parts
85.2 phosphoric acid 4.880 parts calcium carbonate
3.241 parts sodium carbonate and about 8.1 parts
distilled water providing an anhydrous basis mole
percent ratio of 50.60 P205 32.45 Cao and 16.95
Na
Owere placed in a large alumina crucible and
heated slowly in a furnace at a rate of 5 hr up to
1000 C at which point essentially all the water and
CO2 had been driven off and the contents were molten
The melt was held at 1000 C for 24 hr cooled to
740 C at which time several small seed crystals of
CaNa were added
which was held at 740 C
to the for 72
surface of the melt
hr to crystallize
The temperature was reduced to 720 C and held for an additional 72 hr to complete the crystallization after
which the crystallized mass was slowly cooled to room
temperature and removed from the crucible The crystallized mass was broken apart passed through a mechanical
jaw crusher and then fiberized by dry milling in an air
classification mill The fibers had an average aspect
ratio of 64.5 an average diameter of 2.09 ...m and a
surface area of 6773 cm b Friction Material Composite Preparation Sample asbestos friction material com-
posites were prepared in two sizes -- 1.27 cm wide
x 15.24 cm long x 0.64 cm thick 0.5 in x 6 in x
0.25 in with a weight of about 20.0 g and 5.08 cm x 15.24 cm long x 0.64 cm thick 2 in x 6 in x 0.25 in with a weight of about 100.0 g
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Dry ingredients in the amount of either
20.0 g or 100.0 g depending upon the composite size desired and having the desired composition were dry blended thoroughly in a Waring blender The blended
material was loaded into a rectangular steel mold
having a shape approximately that of the desired pro-
duct and pressed for one hour at 18.3 MPa 2650 psi
and a temperature of 171 C 340 F The 5.08 cm wide
pressed pieces were subjected to a post cure in a
10
drying oven at 177 C 350 F for a period of four
hours For green flexural strength tests the samples
were compressed at 18.3 MPa 2650 psi at ambient tem-
perature for one minute The parameters and property
data for the asbestos friction material composites
15
are tabulated in Table 1
TABLE 1
EXAMPLE 2
COMPOSITION1COMPSITON1
wt % 45.0 Barytes
10.0 PF9
FLEXURAL STRENGTH 2.MPa
GREENS
CURED
won
69912.84
,
GROWTH %
0.58
FRICTION COEFFICIENT
FRICTION CLASS6
NORMAL
0.372
HOT
0.391
11
3
86.18
64638.3646538.35
0.38
0.330
0.382
410 55.0 Asbestos
--
510
--~
55.0 Fiberglass
10
610 55.0 Dolomite 33.09
710 45.0 Dolomite 29.65 10.0 PF9
810 50.0 Dolomite 406.79
5.0 Kevlar Ara-
15
mid Fiber Pulp
9
45.0 Barytes
87.56
69175.10
51662.42
37107.58 48042.67
45850.1458540.14
0.75 0.18
0.290 0.530
0/0
0.448
0.80
0.220
0.20
0.330
0.321 0.380 0.313 0.293 0.320
69933.52 69933.52
0.57
0.332
0.428
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6046
01948
TABLE 1 cont'd
EXAMPLE
WEAR %
WT
5.99
THICKNESS 3.49
MINIMUM
REQUIREMENTS7 REQUIREMNTS7
Pass
QUALITY CONTROLfi
Good standard test
high fade in extended
test
6.75
4.04
Pass
Good standard test excessive fade in
10
410
9.11
7.65
510
11.81
10.66
610
3.04
1.93
Pass Pass
Pass
extended test
Acceptable performance Excessive fade high
pitched screech
Excessive variation in
friction coefficient
15
4.55
10.53
Fail
Low normal friction
2.11
2.27
Fail
Excessive variation in friction coefficient
6.69
2.98
Pass
Good standard test
excessive fade in
20
extended test
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6046
01948
TABLE cont'd
FRICTION COEFFICIE/NT
COMPOSITION,, FLEXURAL STRENGTHMPa
FRICTION CLASS
EXAMPLE
wt %
GREENS
CURED4 GROWTH % NORMAL
HOT
5
10
53.5 Barytes 248.21
37790.137 960.16
0.20
0.668
0.546
1.5 NR10
11
43.5 Barytes 386.11
64245.35 64245.35
0.18 0.368
0.396
1.5 NR10
10.0 PF9
10
12
36.0 Barytes
434.37
1.5 NR10
70436.84
0.53
0.312
0.367
17.5 PF9
1310 Commercial
o=-
Asbestos Pad
15
1410 Commercial Semi- <--
fated
0.26
0.438
0.467
-16-
0.96
0.338
0.334
metallic Pad
43-21
6046
01948
TABLE 1 cont'd
EXAMPLE 10
WEAR %
WT
THICKNESS
5.31
3.76
MINIMUM
REQUIREMENTS7REQUIREMNTS7
Pass
QUALITY CONTROL
Excessive fade
5
11
6.03
3.35
12
4.74
2.82
10
1310
11.77
8.45
Pass Pass Pass
Good standard test
excessive fade in extended test
Good standard test
excessive fade in extended test
Acceptable performance
1410
---
0.91
Pass
Excellent performance
low wear
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01948
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5 10 15 20
25 30 35
1 A base formulation was employed which had a weight % composition as follows 33.33 formaldehyde thermosetting resin containing hexamethylene-
tetramine as curing agent
available commercially from
22.22
Schenectady Chemicals Inc. particulate friction modifier which was an aldehyde condensation product
of cashew nut shell liquid available
commercially from Colloid Chemicals Laboratories Inc. as Collan 10A
44.44
barytes barium sulfate available commercially from Pfizer Minerals
Pigments & Metals Div
55 additive material ]
In use the fiber and other additives if em-
ployed to be tested was
formulation in an amount
added to the base sufficient to consti-
tute 55 by weight of the final composition
This resulted in the 33.33 22.22 and
44.44 in the base formulation being reduced
to 15 10 and 20 respectively all by
weight in the
than 55 fiber
final composition If less
was used the balance was made
up with filler material for example barytes and rubber for example nitrile rubber
2,3,9 The test was carried out according to ASTM D790-80 test method for plastics on a flexural
jig
The
on an
15.24
Instrom Universal testing instrument
cm long green uncured strength
samples were cut in half to provide two 7.62
cm 3 in test pieces
tested with a 50.8 mm
and each piece was 2 in span The cured
samples were broken with a 101.60 mm 4 in
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span and the two resulting pieces were rebroken with a 50.8 mm 2 in span
5
The test was carried out according to SAE Test
J160
10 The test was carried out according to SAE Test J661a by Greening Testing Laboratories Inc. and
the classifications were made in accordance with
SAE Test J866a The standard J661a test has 343 C
650 F as the upper temperature limit The
10
extended test has an upper temperature limit of
454 C 850 F a more severe test
7 This test was carried out according to SAE Test
J998.
8
Qualitative observations and comments regarding
15
performance of test pieces during the SAE Test
J661a
Phosphate fibers Comparative example
Nitrile rubber
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Thus it is apparent that there has been
provided in accordance with the instant invention asbestos friction material composites containing crystalline phosphate fibers and a process for preparing same that fully satisfy the objects and advan-
tages set forth hereinabove While the invention has
been described with respect to various specific examples and embodiments thereof it is understood
that the invention is not limited thereto and that
10
many alternatives modifications and variations will
be apparent to those skilled in the art in light of the foregoing description Accordingly it is intended to embrace all such alternatives modifica-
tions and variations as fall within the spirit and
15
broad scope of the invention
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WHAT IS CLAIMED IS
1. An asbestos friction material
composite containing phosphate fibers comprising a asbestiform crystalline calcium M
phosphate fibers wherein M is a
metal cation selected from the
group consisting of sodium and
lithium and mixtures thereof
b a thermosetting based binder
10
c a particulate friction modifier and
d a particulate inorganic filler
2. The asbestos friction material
composite of claim 1 wherein M is sodium
3. The asbestos friction material
15
composite of claim 1 wherein the phosphate fibers
have an aspect ratio of at least 30
4. The asbestos friction material
composite of Claim 3
have an aspect ratio
wherein of from
the phosphate
about 40 to
fibers about
20
100
5. The asbestos friction material
composite of claim 1 wherein the have an average diameter of from
about 20 ...m
phosphate
about 0.5
fibers
...m to
25
6. The asbestos friction material
composite of Claim 5 wherein the phosphate fibers
have an average diameter of from about 1 ...m to about
10 ...m
7 The asbestos friction material
30
composite of claim 1 wherein the composite further
comprises an auxiliary fiber selected from the group
consisting of glass fibers mineral wool fibers
aramid fibers steel fibers and mixtures thereof
8. The asbestos friction material
35
composite of claim 1 wherein the thermosetting
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based binder comprises a formaldehyde thermosetting resin
9. The asbestos friction material
composite of Claim 8 wherein the thermosetting based binder further comprises a rubber
10. The asbestos friction material
composite of Claim 9 wherein the rubber is a nitrile
rubber
11. The asbestos friction material
10
composite of Claim 1 wherein the particulate friction
modifier is an aldehyde condensation product of
cashew nut shell liquid
12. The asbestos friction material
composite of claim 1 wherein the particulate inor-
15
ganic filler is selected from the group consisting of
barytes calcium carbonate silica and mixtures
thereof
13. The asbestos friction material
composite of claim 11 wherein the particulate inor-
20
ganic filler is barytes
14. The asbestos friction material
composite of claim 1 wherein the particulate friction
modifier and the particulate inorganic filler have an
average particle size from about 0.5 ...mto about
25
500 ...m
15. The asbestos friction material
composite of claim 1 wherein the composite comprises
a from about % to about 20 by
weight of the phosphate fibers
30
b from about 10 to about 30 by
weight of the thermosetting
based binder
c from about % to about 25 by
weight of the particulate fric-
35
tion modifier and
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d from about 40 to about 70 by weight of the particulate inorganic filler
16. An asbestos friction material
5
composite containing phosphate fibers comprising
a from about 10 to about 17.5 by
weight of asbestiform crystal-
line calcium sodium phosphate
having an aspect ratio of from
10
about 40 to about 100 and
an average diameter of from
about 1 ...m to about 10 ...m
b from about 15 to about 25 by
weight of a formaldehyde
15
thermosetting resin
binder
c
from about 10 to about 15 by weight of a particulate alde-
cashew nut shell liquid
20
condensation product and
d from about 45 to about 65 by
weight of particulate barytes
17. A process for the preparation of an
asbestos friction material composite containing
25
phosphate fibers which comprises
a blending asbestiform crystalline
calcium M phosphate fibers wherein
M is a metal cation selected from
the group consisting of sodium and
30
lithium and mixtures thereof a
thermosetting based binder
a particulate friction modifier and
a particulate inorganic filler to
form a uniform mixture
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35
b placing the mixture within a mold
cavity having a shape approximately that of the desired composite and
c
compressing the mixture at a temper-
ature and a pressure and for a time
sufficient to form the asbestos
friction material composites
18 The process of claim 17 wherein M is
sodium
19. The process of Claim 17 wherein the phosphate fibers have an aspect ratio of at least 30
20. The process of Claim 19 wherein the phosphate fibers have an aspect ratio of from about 40
to about 100
21. The process of Claim 17 wherein the phos-
phate fibers have an average diameter of from about
0.5 ...mto about 20 ...m
22. The process of Claim 21 wherein the phos-
phate fibers have an average diameter
1 pm to about 10 ~fl oo 23. The process of Claim 17
of from wherein
about the com-
posite further comprises an auxiliary fiber selected
from the group consisting of glass fibers mineral
wool fibers aramid fibers steel fibers and mixtures
thereof
24. The process of Claim 17 wherein the
thermosetting based binder comprises a phenolformaldehyde thermosetting resin
25. The process of Claim 24 wherein the
thermosetting based binder further comprises a
rubber 26. The process of Claim 25 wherein the
rubber is a nitrile rubber 27. The process of claim 17 wherein the
particulate friction modifier is an aldehyde condensation product of cashew nut shell liquid
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28. The process of claim 17 wherein the
particulate inorganic filler is selected from the
group consisting of barytes
and mixtures thereof
calcium carbonate
silica
29. The process of Claim 28 wherein the
particulate inorganic filler is barytes
30. The process of claim 17 wherein the
particulate friction modifier and the particulate inorganic filler have an average particle size from
about 0.5 ...m to about 500 m 31. The process of Claim 17 wherein the com-
posite comprises
a from about % to about 20 by weight of the phosphate fibers
b from about 10 to about 30 by
weight of the thermosetting
based binder c from about % to about 25 by
weight of the particulate friction modifier and d from about 40 to about 70 by weight of the particulate inorganic filler
32. The process of Claim 17 wherein the mixture is compressed at ambient temperature and a pressure of about 18.0 MPa for about one minute
33. The process of Claim 32 wherein the mix-
ture is further compressed for a period of about one hour at a temperature of about 171 C and a pressure
of about 18.0 MPa
34. The process of Claim 17 wherein the mix-
ture is compressed at a temperature of about 171 C
and a pressure of about 18.0 MPa for about one hour
35. The process of Claim 17 wherein the com-
posite is subjected to a post cure at a temperature
of about 177 C for about four hours
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15-
20 25 30 35
36. A process for the preparation of an asbestos friction material composite containing
phosphate fibers which comprises
a blending from about 10 to about 17.5 by weight of asbestiform crystalline calcium sodium phosphate having an aspect ratio of
from about 40 to about 100
b c
and an average diameter of from about 1 ...mto about 10 ...m from
about 15 to about 25 by weight of a formaldehyde thermosetting based binder from about 10 to about 15 by weight of a particulate aldehyde nut shell liquid condensation product and from about 45 to about 65 by weight of particulate barytes to form a uniform mixture placing the mixture within a mold cavity having a shape approximately that of the desired composite compressing the mixture at a tem-
perature and a pressure and for a time sufficient to form the asbestos friction material
composite
37. The process of Claim 36 wherein the mixture is compressed at ambient temperature and a pressure of about 18.0 MPa for about one minute
38. The process of Claim 37 wherein the mix-
ture is further compressed for a period of about one hour at a temperature of about 171 C and a pressure of about 18.0 MPa
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39. The process of Claim 35 wherein the mixture is compressed at a temperature of about 171 C and a pressure of about 18.0 MPa for about one hour
40. The process of Claim 35 wherein the com-
posite is subjected to a post cure at a temperature
of about 177 C for about four hours