Document ZBYa73BaKKOmXKVOkKG3NRg18
FILE NAME: Phenolic Resins (PHR) DATE: 1986 DOC#: PHR010 DOCUMENT DESCRIPTION: European Patent Application
J Europisches Patentamt European Patent Office Office europen des brevets
Publication numbar:
EUROPEAN PATENT APPLICATION
0 194 989
A2
Application number: 86870033,7 Date of filing: 13.03.86
Int. Cl.4: F 16 D 69/02
Priority: 14.03.85 U S 711894 14.03.85 U S 711893
Date of publication of application: 17.09.86 Bulletin 86/38
Designated Contracting States: AT BE CH DE FR G B IT U LU NL SE
Applicant: Monsanto Company
Patent Department 800 North Undbergh Boulevard
St. Louia Missouri 63167IUS)
'
inventor: Crutchfield, Marvin Meek 1529 Cerulean Drive Creva Coeur M issouri 63146(US)
Inventor: Griffith, Edward Jackson 310 Coventry Lane Manchester M issouri 63021(US|
Inventor: Hinkebeln, John Arnold 2460 Barrett Station Road Ballwin Missouri 63021IUSI
Representative: Lunt, John Cooper et el, Monsanto Europe S.A. Patent Department Avenue de Tervuren 270-272 Letter Box No 1 B-1150Brussele(BE)
Friction material composites containing crystalline phosphate fibers and a process for the preparation thereof.
Asbestos-free 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 resin-based binder, a
N particulate friction modifier, and a particulate inorganic filler
4 to form a uniform mixture; (b) placing the mixture within a mold cavity having a shape approximately that of the desired
S ) composite: and |c) compressing the mixture at a tempera50 ture and a pressure, and for a time, sufficient to form the 35 asbestos-free friction material composites.
3
0194989
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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.
In addition, in the operation of conventional asbestosbased brake elements, as the brake element wears away, some of the 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-based 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
or steel fibers and the like. In U.S. Patent 4,278,584, an asbestos-free
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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reportedly results in good structural integrity of
preforms made therefrom.
Although these prior art friction materials
are effective to eliminate asbestos in products
5 utilizing such friction materials, none have been found to provide strength, wear resistance, and fric
tional properties comparable to those provided by
asbestos-containing friction materials, coupled with
economical materials and manufacturing costs. For
10 example, glass fibers have a tendency to fracture in the mixing procedures used to prepare 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
15
ing service of the brake element and high wear rates
are thereby encountered. Moreover, the nonporous
glass fibers have a low surface area as compared with
asbestos, and the glass fibers do not absorb products
of decomposition of the organic components caused by
20
heat which occurs during braking. As a result, when
glass fibers are used as the reinforcing material,
friction drops precipitously at the temperatures gen
erated during braking. This friction drop due to poor
absorbtion by the reinforcing fibers is known in the
25 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
30
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
35 parable to, and in many instances superior to, conventional asbestos-containing friction material in
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wear, durability, friction, and strength, while at the same time presenting no health hazard and a process for their preparation, therefore, is believed to be a decided advance in the asbestos-free friction material
composite art. SUMMARY OF THE INVENTION
It is an object of this invention to provide novel asbestos-free friction material composites con taining 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 exceed ing those of conventional asbestos-type friction material composites, and at the same time present no
health hazard.
_
t
It is also an object of this invention to
provide an asbestos-free friction material composite
which can be shaped into brake pads, brake lining seg
ments, clutch facings, and the like using conventional
processes. Another object of this invention is to
provide a process for preparing novel asbestos-free 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-type 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-free friction material composite which can be shaped into
" 5~
43-21(6046^
5
10
15
20
25 30
brake pads, brake lining segments, clutch facings, and the like using conventional processes.
.
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 :
(s) 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 resin-based binder; (c) a particulate friction modifier; and (d) a particulate inorganic filler. The provision of the process for the pre paration of such friction material composites objects is achieved by a process which comprises: (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 resin-based binder, a 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 temper ature and a pressure, and for a time, efficient to form the asbestos-free friction material composites.
0 1 9 4 9 8 9 -6 -
4 3 - 2 1 ( 5 0 4 6 )A
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with this invention, novel
asbestos-free friction material composites, and a
process for the preparation thereof, are provided.
5
The friction material composites exhibit wear, dura
bility, friction, and strength characteristics com
parable to, or exceeding, those of conventional
asbestos-type friction materials, while at the same
time present no health hazard. Such composites
10
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
15
mixtures thereof;
(b) a thermosetting resin-based binder;
(c) a particulate friction modifier; and
(d) a particulate inorganic filler.
The composites are prepared by a process
20 which comprises:
(a) blending asbestiform crystalline
calcium M phosphate fibers wherein
M is a metal cation selected from
the group consisting of sodium and
25
lithium, and mixtures thereof, a
thermosetting resin-based binder, a
particulate friction modifier, and
a particulate inorganic filler to
form a uniform mixture;
30
(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,
35
sufficient to form the asbestos-free
friction material composites.
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It is contemplated that, in use, the asbestos-free friction material composites of the
instant invention may be.fastened unto standard brake shoe members by conventional means, either by integral 5 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(P03 )3 Jn wherein n is a number representing the
number of repeating CaM(P03 )3 units. Advantageously,
such fibers have an aspect ratio (length-to-average ' 15 diameter ratio, L/D) of at least 30:1 and an average
diameter m the range of from about 0.5 micron (pm) to about 20 pm. Preferred fibers are those having an aspect ratio of from about 40:1 to about 100:1 and an
20 average diameter from about 1 micron to about 10 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 fiber/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 resin-based binder mate rials suitable to prepare the asbestos-free 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, brake lining segments, clutch facings, and the like. Representative thermosetting resins include phenol
formaldehyde resins, phenol-furfural resins, melamineformaldehyde resins, epoxy resins, cross-linked alkyd resins, diallyl phthalate resins, and urea-formalde hyde resins. Preferred resins are phenol-formaldehyde resins. A phenol-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 friction-material 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-buta diene copolymer rubber, acrylonitrile rubber, and chlorinated butyl rubber. A preferred rubber is
nitrile rubber.
.
When a rubber is used in the instant m v e n -
tion, it preferably constitutes less than 50% of the
thermosetting resin-based binder. It may be incor
porated into the asbestos-free friction material
composite in the form of a solution in an organic sol
vent such as trichlorethylene or, more preferably, m
the form of a powder, and a vulcanizing agent - sulfur, 2-mercaptobenzothiazole, tetramethylthiuram
-943-21(6046)A
mixtures
fr
- 1 .
employed in the
^ C" Pnent
stabilize the coefficient of friction materials under a variety of o n - *
^ ^ COmposite
preierably is a cashew-based material
cashew nut shell oil-based fri^-
1 h aS
, .
ssed friction particles
able cashew-based friction nar+--i i
* Suit-
condensation product of cashew nut shell U g ^ i f
are available commercially from Colloid Chemicals
Laboratories, m e . as collan 10A-40.
ployed in I T " ? * inr9anic filler materials emP oyed in the instant invention may be crystal!
amorphous in structure as long as teey J T . TM
maintain stability at temperatures up to 538" c
00 F), and higher. Representative of suitable
bonaT i
dolomite
, ,
filler
" ta U
h Carin r 9raPhit6' 1 C ! car
*'
^ like- In "
1, however,
tiller, is not preferr^H Fn*-
tionln
inStant inVention due t0 I normal frio-
hired, of course that 1 \ `
be re" 9`
depending to 30; extent uten te" ' ^ " " " ^ ^
Of such composites.
C"P~
rials ,th I " Particle Si2e of the Particulate mate tals (that is, the particulate friction modifier and
critical l ate lnr9anlC filler> is not particularly
r : : r ia is are satisfactory
-
tions therefrom ,,ill have no substantial effect on
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performance. Particle sizes from about 0.5 pm to
about 500 pm may be used. In the practice of the instant invention,
the components of the asbestos-free friction material
5 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
10
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 of about 171 C (340 F) for
about one hour while maintaining the pressure at about.
18.0 MPa. Alternatively, the preform step may be
15
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 a drying oven at about 177 C
20
(350 F) for about four hours.
Any convenient concentration (on a weight
basis) of the components of the asbestos-free friction
material composites may be used. In general, the com
posites of the instant invention will comprise (on a
25
weight basis) from about 5% to about 20% of the phos
phate fibers, from about 10% to about 30% of the
thermosetting resin-based binder, from about 5% to
about 25% of the particulate friction modifier, and
from about 40% to about 70% of the particulate inor
30
ganic filler. In a preferred embodiment, the concen
tration for the phosphate fiber will range from about
10% to about 17.5%, for the thermosetting resin-based
binder, from about 15% to about 25%, for the particu
late friction modifier, from about 10% to about 15%,
35
for the particulate inorganic filler, from about 45%
to about 65%. In a most preferred embodiment, the
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5 10 15 20 25 30 35
concentration for the phosphate fiber will be, as previously noted, about 10% to about 17.5%, for the thermosetting resin-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 tute about 2% to about 10% of the friction material composite (so long as the aforementioned phosphate fiber/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 the particulate inorganic filler and employed in com bination with the thermosetting resin of the thermo setting resin-based binder in an amount such that the rubber will constitute about 0.5% to about 5% of the friction material composite.
The asbestos-free 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.
The following specific examples illustrating the best presently-known 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 exposition of the application of the invention, while indicating preferred embodiments, are given by way of lHustration only and are not to be construed as limiting the invention since various changes and modi fications within the spirit of the invention will ' become apparent to those skilled in the art from this detailed description.
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EXAMPLES 1-14 (a) Calcium Sodium Phosphate Fibers - Asbesti-
form crystalline calcium sodium phosphate fibers were
prepared in five batches of 29.0 kg to 70.3 kg (64 lb
to 155 lb) each by scale-up of the general procedures 5
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 10
percent ratio of 50.60% P205 , 32.45% CaO, and 16.95%
Na20, were placed in a large alumina crucible and heated slowly in a furnace at a rate of 5 C/hr up to
1000 C, at which point essentially all the water and
15 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(P03 )3ln were added to the surface of the melt
which was held at 740 C for 72 hr to crystallize.
The temperature was reduced to 720 C and held for an 20
additional 72 hr to complete the crystallization, after
which the crystallized mass was slowly cooled to room temperature and removed from the crucible. The crystal
lized mass was broken apart, passed through a mechanics
jaw crusher, and then fiberized by dry milling in an air 25
classification mill. The fibers had an average aspect
ratio of 64.5, an average diameter of 2.09 ym, and a
surface area of 6773 cm2/g.
m
(b) Friction Material Composite Preparation -
sample asbestos-free friction material com 30
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 m 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 m
35
with a weight of about 100.0 g.
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43-21(6046)A
Dry ingredients in the amount of either
^ireV'anTh0 9'
" " " *"
blend d'ts
9 th6 d6Sired
ere dry
blended thoroughiy in a Waring blender. The blended
material ,,as loaded into a rectangular steel mold
dn : Shape approxi,"ately that Of the desired pre s e t and pressed for one hour at 18.3 MPa (2650 psi) and a temperature of 171- c (340- F>. The 5.08 cm ,,ide pressed pieces ,,ere subjected to a post cure in a 10 drying oven at 1,7 c (350- F, for a period of four hours. For green flexural strength tests, the samples ere compressed at 18.3 MPa (2650 psi) at ambient tem-
"
T 0n! "inUte- Ihe P~
a - property
L5 aarree ttalbuilaaTtedd m TablSe'flr.Se
"aterial " "Pites
COMPOSITION1,
10.0 PF9
FLEXURAL STRENGTH2 ,MPa
GREEN3 '
CURED4
,, 69912.84
3
II
86.18
64638.35
4 l 55.0 Asbestos 5 i 55.0 Fiberglass
6 10 55.0 Dolomite 33.09
710 45.0 Dolomite 29.65 10.0 PF9
8 10 50.0 Dolomite 406.79
5.0 Kevlar Ara-
mid Fiber Pulp
9
45,0 Barytes
87.56
69175.10 51662.42 37107.58 48042.67 45850.14
69933.52
TABLE 1
SWELL/GROWTH5, % 0.58/0
FRICTION COEFFICIENT,\i/
FRICTION CLASS6
NORMAL
HOT
0.372/F
0.391/F
0.38/0
0.330/E
0.382/F
0.75/0 0.18/0
0/0
0.80/0.80
0 .20/0
0.290/E 0.530/G 0.448/F 0.220/D 0.330/E
0.57/0
0.332/E
0.321/E 0.380/F 0.313/E 0.293/E 0.320/E
0.428/F
TABLE 1
EXAMPLE
2
WEAR, %
WT. THICKNESS
5.99
3.49
MINIMUM REQUIREMENTS
Pass
5
3
6.75
4.04
Pass
10
410
9.11
7.65
5 10
11.81
10.66
6 io
3.04
1.93
15
7io
4.55
10.53
gi
2.11
2.27
Pass Pass Pass Fail Fail
9
6.69
2.98
20
Pass
(cont'd)
QUALITY CONTROL8
Good standard test; high fade in extended
test. Good standard test; excessive fade in
extended test. Acceptable performance Excessive fade; high
pitched screech. Excessive variation in friction coefficient. Low normal friction.
Excessive variation in friction coefficient.
Good standard test; excessive fade in
extended test.
i H*
Cn
I
b.
CO M M CT\
O to.
co o
> A CO fti <0 CO CD
TABLE 1 ( c o n t ' d )
FRICTION COEFFICIENT,JJ/-
f r i c t i o n CLASS6 _
example
COMPOSITION1, wt. %
FLEXURAL STRENGTH2 ,MPa
2-G4-R8E-.2E1N--3,--- ------3C7U7R9E0D.146
SWELL/GROWTH5,_% - g g L
---0--. 2-0-/-0-- 0 .668/H
0 .5 46OT/ G_
10
53.5 Barytes
1.5 NR10
11
43.5 Barytes 386.11
64245.35
0,55/0.18
0.368/F
0.396/F
1.5 NR10
10.0 PF9
434.37
70436.84
1.24/0.53
0.312/E
0.367/F
10 12 361..50 BNaRr1y0tes
17.5 PF9
0 .91/ 0.26
0.438/F
0.467/G
13 10
Commercial
"
Asbestos Pad
1.23/0.96 0.338/E
0.334/E
15
14 10 Commercial Semi- -
metallic Pad
i HCT\ I
4* CjJ MI t~*
a\
o
.U CTi
o
mA
CO
CO
00
CO
EXAMPLE
10 11
WEAR, %
WT. THICKNESS
5.31
3.76
6.03
3.35
MINIMUM
REQUIREMENTS7
Pass
Pass
12
4.74
2.82
10
1310
11.77
8.45
l4 xo
0.91
Pass Pass Pass
TABLE 1 (cont'd)
QUALITY CONTROL8 Excessive fade.
Good standard test; excessive fade in
extended test. Good standard test; excessive fade in
extended test. Acceptable performance
Excellent performance; low wear.
i *-> i
Ck
u> I N> as o ** s O > X*
to
A
to
00 co
0194989
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L A base formulation was employed which had a weight % composition as follows:
33.33(15%] phenol-formaldehyde thermosetting
resin (containing hexamethylene
5
tetramine as curing agent),
available commercially from
Schenectady Chemicals, Inc.
22.22(10%] particulate friction modifier, which
was an aldehyde condensation product
10
of cashew nut shell liquid available
commercially from Colloid Chemicals
Laboratories, Inc. as Collan 10A-40. 44.44(20%] barytes (barium sulfate) available
commercially from Pfizer Minerals,
15
Pigments & Metals Div.
[55% fiber/filler/additive material.]
In use, the fiber (and other additives, if em
ployed) to be tested was added to the base
formulation in an amount sufficient to consti
20
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 final composition. If less
25
than 55% fiber was used, the balance was made
up with filler material, for example, barytes,
and/or rubber, for example, nitrile rubber.
I ' l ' l Tiie test was carried out according to ASTM
D790-80 test method for plastics on a flexural
30
jig on an Instrom Universal testing instrument.
The 15.24 cm long green (uncured) strength samples were cut in half to provide two 7.62
cm (3 in) test pieces and each piece was
tested with a 50.8 mm (2 in) span. The cured
35
samples were broken with a 101.60 mm (4 in)
0 1 9 4 9 8 9 43-21(6046)A
span and the two resulting pieces were rebroken
with a 50.8 mm (2 in) span. The test w a s .carried out according to SAE Test
J160. The test was carried out according to SAE Test j66la 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 extended test has an upper temperature limit of 454 C (850 F), a more severe test. This test was carried out according to SAE Test
J998
.
Qualitative observations and comments regarding
performance of test pieces during the SAE Test
J661a. Phosphate fibers. Comparative example. Nitrile rubber.
0194989
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43-21(6046)A
Tiius, it is apparent that there has been provided in accordance with the instant invention, asbestos-free friction material composites containing crystalline phosphate fibers and a process for pre paring 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 many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is in tended to embrace all such alternatives, modifica tions, and variations as fall within the spirit and broad scope of the invention.
WHAT IS CLAIMED IS:
- 21-
43-21(6046)A 4 9 8 9
1. An asbestos-free 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 resin-based binder;
10
(c)
a particulate friction modifier; and
( d ) a particulate inorganic filler.
2. The asbestos-free friction material
composite of claim 1 wherein M is sodium.
3. The asbestos-free friction material 15
composite of claim 1 wherein the phosphate fibers
have an aspect ratio of at least 30:1.
comn ,, \ The asbestos-f e friction material composite of claim 3 wherein the phosphate fibers
20
aspect ratl of from about 40:1 to about
5. The asbestos-free friction material
composite of claim 1 wherein the phosphate fibers
have an average diameter of from about 0.5 pm to about 20 |jm. 25
6. The asbestos-free friction material
composite of claim 5 wherein the phosphate fibers
r r aVera9e diameter 0f
^
1 p- to about
30
.
.
^be ast,estos-free friction material
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-free friction material 35
composite of claim 1 wherein the thermosetting
0194989
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resin-based binder comprises a phenol-formaldehyde
thermosetting resin. 9. The asbestos-free friction material
composite of Claim 8 wherein the thermosetting
5
resin-based binder further comprises a rubber.
10. The asbestos--free friction material
composite of Claim 9 wherein the rubber is a nitrile
rubber. 11. The asbestos-free 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-free 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-free friction material
composite of Claim 11 wherein the particulate inor
20
ganic filler is barytes.
14. The asbestos-free 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 pm to about
25
500 pm.
t
15. The asbestos-free friction material
composite of Claim 1 wherein the composite comprises
(a) from about 5% to about 20/ by weight of the phosphate fibers,
30
(b) from about 10% to about 30% by
weight of the thermosetting
resin-based binder;
(c) from about 5% to about 25% by weight of the particulate fric
35
tion modifier; and
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5
10 15
20
25 30
(d) from about 40% to about 70% by weight of the particulate inor ganic filler.
16.
An asbestos-free friction material
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
about 40:1 to about 100:1 and
an average diameter of from
about 1 pm to about 10 pm;
(b) from about 15% to about 25% by
weight of a phenol-formaldehyde thermosetting resin-based binder;
(c) from about 10% to about 15% by
weight of a particulate alde
hyde-cashew nut shell liquid
condensation product; and (d) from about 45% to about 65% by
weight of particulate barytes.
17.
A process for the preparation of an
asbestos-free friction material composite containing
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
lithium, and mixtures thereof, a
thermosetting resin-based binder,
a particulate friction modifier, and a particulate .inorganic filler to form a uniform mixture;
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5 10 15 20 25 30 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--free friction material composites.
18. The process of claim 17 wherein M is sodium.
19. The process of Claim 17 wherein the phos phate fibers have an aspect ratio of at least 30:1.
20. The process of Claim 19 wherein the phos phate fibers have an aspect ratio of from about 40:1 to about 100:1.
21. The process of Claim 17 wherein the phos phate fibers have an average diameter of from about 0-5 ym to about 20 ym.
22. The process of Claim 21 wherein the phos phate fibers have ar* average diameter of from about 1 ym to about 10 yin..
,r-/ 23. Th*process of Claim 17 wherein 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 resin-based binder comprises a phenol formaldehyde thermosetting resin.
25. The process of Claim 24 wherein the thermosetting resin-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 conden sation product of cashew nut shell liquid.
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43-21(6046)A
28. The process of Claim 17 wherein the particulate inorganic filler is selected from the
group consisting of barytes, calcium carbonate, silica, and mixtures thereof. 5
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 10 about 0.5 pm to about 500 pm.
.
31 The Process of Claim 17 wherein the com
posite comprises:
(a) from about 5% to about 20% by
weight of the phosphate fibers;
15 (b) from about 10% to about 30% by
weight of the thermosetting
resin-based binder;
(c) from about 5% to about 25% by
weight of the particulate fric
20
tion modifier; and
'
(d> from about 40% to about 70% by
weight of the particulate inor ganic filler.
32. The process of claim 17 wherein the mix 25 ture 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
30
of about 18.0 MPa.
34. The process of claim 17 wherein the mix
ture is compressed at a temperature of about 1 7 1 c
and a pressure of about 18.0 MPa for about one hour.
35. The process of Claim 17 wherein the com 35 posite is subjected to a post cure at a temperature
of about 177 c for about four hours.
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36.
A process for the preparation of an
asbestos-free friction material composite containing
phosphate fibers which comprises;
(a) blending from about 10% to about 17.5% by weight of asbestiform
crystalline calcium sodium phos
phate having an aspect ratio of
from about 40:1 to about 100:1
and an average diameter of from
about 1 (jm to about 10 pm, from
about 15% to about 25% by weight
of a phenol-formaldehyde thermo
setting resin-based binder, from
about 10% to about 15% by weight
of a particulate aldehyde-cashew
nut shell liquid condensation
product, and from about 45% to about 65% by weight of particu
late barytes to form a uniform
mixture;
(b) placing the mixture within a mold
cavity having a shape approximately
that of the desired composite;
(c) compressing the mixture at a tem
perature and a pressure, and for a
time, sufficient to form the asbestos-free friction material
composite. 37. The process of Claim 36 wherein the mix
ture 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 mix ture 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.