U.S. patent application number 12/307958 was filed with the patent office on 2009-11-26 for grease compositions for constant velocity joints and constant velocity joints.
Invention is credited to Minoru Ishijima, Mitsuhiro Kakizaki, Shinya Kondo, Kenta Yamazaki.
Application Number | 20090291866 12/307958 |
Document ID | / |
Family ID | 38923229 |
Filed Date | 2009-11-26 |
United States Patent
Application |
20090291866 |
Kind Code |
A1 |
Kakizaki; Mitsuhiro ; et
al. |
November 26, 2009 |
GREASE COMPOSITIONS FOR CONSTANT VELOCITY JOINTS AND CONSTANT
VELOCITY JOINTS
Abstract
The invention provides a grease composition for constant
velocity joints and constant velocity joints in which the grease
composition is packed. The composition comprises (a) a base oil
comprising a synthetic oil; (b) a thickening agent; (c) a
molybdenum sulfurized dialkyl dithiocarbamate; (d) a thiophosphate;
and (e) a zinc sulfurized dialkyl dithiocarbamate. The composition
can reduce low temperature rotational torque and folding torque in
constant velocity joints while inhibiting deterioration of a boot
material comprising a silicone rubber.
Inventors: |
Kakizaki; Mitsuhiro;
(Kanagawa, JP) ; Kondo; Shinya; (Kanagawa, JP)
; Ishijima; Minoru; (Shizuoka, JP) ; Yamazaki;
Kenta; (Shizuoka, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Family ID: |
38923229 |
Appl. No.: |
12/307958 |
Filed: |
July 10, 2007 |
PCT Filed: |
July 10, 2007 |
PCT NO: |
PCT/JP2007/063739 |
371 Date: |
January 8, 2009 |
Current U.S.
Class: |
508/108 ;
508/365 |
Current CPC
Class: |
C10M 2219/066 20130101;
C10M 169/00 20130101; F16D 3/20 20130101; C10N 2030/36 20200501;
C10N 2060/10 20130101; C10M 2201/066 20130101; C10N 2030/06
20130101; C10N 2030/02 20130101; C10M 2205/0265 20130101; C10N
2040/046 20200501; C10M 2215/1026 20130101; C10M 2219/068 20130101;
C10N 2050/10 20130101; C10M 2205/003 20130101; C10N 2030/08
20130101; C10M 2223/045 20130101; C10M 2215/08 20130101; C10M
2205/0285 20130101; C10M 2223/047 20130101; C10M 2219/068 20130101;
C10N 2060/10 20130101; C10M 2223/045 20130101; C10N 2010/04
20130101; C10M 2219/068 20130101; C10N 2010/12 20130101; C10M
2219/068 20130101; C10N 2010/04 20130101; C10M 2219/068 20130101;
C10N 2010/12 20130101; C10M 2223/045 20130101; C10N 2010/04
20130101; C10M 2219/068 20130101; C10N 2010/04 20130101; C10M
2219/068 20130101; C10N 2060/10 20130101 |
Class at
Publication: |
508/108 ;
508/365 |
International
Class: |
C10M 135/18 20060101
C10M135/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2006 |
JP |
2006-189592 |
Claims
1. A grease composition for constant velocity joints, which
comprises the following components (a) to (e): (a) a base oil
comprising a synthetic oil; (b) a thickening agent; (c) a
molybdenum sulfurized dialkyl dithiocarbamate; (d) a thiophosphate;
and (e) a zinc sulfurized dialkyl dithiocarbamate.
2. The grease composition for constant velocity joints of claim 1,
wherein the composition further comprises (f) a mixture of 30-70%
by mass of molybdenum disulfide and 70-30% by mass of a fatty acid
amide.
3. The grease composition for constant velocity joints of claim 1,
wherein the synthetic oil in Component (a) is a synthetic
hydrocarbon oil.
4. The grease composition for constant velocity joints of claim 1,
wherein Component (b): the thickening agent is a urea compound.
5. The grease composition for constant velocity joints of claim 1,
wherein the content of Component (c): the molybdenum sulfurized
dialkyl dithiocarbamate is 0.1 to 10% by mass based on the total
mass of the grease composition.
6. The grease composition for constant velocity joints of claim 1,
wherein the content of Component (d): the thiophosphate is 0.1 to
10% by mass based on the total mass of the grease composition.
7. The grease composition for constant velocity joints of claim 1,
wherein the content of Component (e): the zinc sulfurized dialkyl
dithiocarbamate is 0.1 to 10% by mass based on the total mass of
the grease composition.
8. The grease composition for constant velocity joints of claim 2,
wherein the content of Component (f): the mixture of 30-70% by mass
of molybdenum disulfide and 70-30% by mass of a fatty acid amide is
0.1 to 10% by mass based on the total mass of the grease
composition.
9. A constant velocity joint in which the grease composition of
claim 1 is packed.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a grease composition for constant
velocity joints, which reduces low temperature rotational torque
and folding torque in constant velocity joints and constant
velocity joints in which the grease composition is packed, more
specifically, a grease composition for constant velocity joints,
which reduces low temperature start-up rotational torque and
stick-slip in constant velocity joints and which is compatible with
a boot material comprising silicone rubber (silicone resin) and
constant velocity joints in which the grease composition is
packed.
BACKGROUND ART
[0002] In the field of automobile industry, FF-car production has
recently been increasing for the purpose of reducing weight and
expanding living space. 4WD car production is also growing due to
their functionality. These FF and 4WD cars realize a power
transmission and steering by the front wheels, and therefore, it is
necessary to secure a smooth power transmission, even when the
steering wheel is fully turned, and the constant velocity joint is
inevitable as a part to transmit a rotational movement at a
constant velocity in response to the changes in crossing angles
between the crossing two axes.
[0003] Because performance of cars has recently been improved
further and the production of high-power cars is increasing,
constant velocity joints are exposed to greater stresses and
severer lubrication condition.
[0004] Meanwhile, there is a tendency that an improvement of riding
comfort in a car is also required at a higher level. The
improvement of the riding comfort is demanded in any climate
regions, for example, from extremely hot regions to extremely cold
regions.
[0005] In particular, smooth motion of constant velocity joints in
extremely cold regions is emphasized. In extremely cold regions,
cars may be started at an extremely low temperature. Under such a
condition, the rotational resistance may vary upon rotating due to
the difference in frictional resistances among parts composing the
constant velocity joint. Variation in rotational resistance may
lead to deteriorate the riding comfort. Thus, troubles unexpected
under normal circumstances may occur in extremely cold regions. To
avoid troubles in constant velocity joints in extremely cold
regions, it is important to reduce low temperature torque and
folding torque. The folding torque has a tendency to depend on
friction coefficient (resistance) of a grease and therefore, there
is a need for early development of a grease which exerts excellent
effects at low temperature. However, there have not been proposed
any grease compositions for constant velocity joints which can
sufficiently reduce low temperature rotational torque and folding
torque in extremely cold regions.
[0006] There have been proposed grease compositions for constant
velocity joints, which comprise a base oil as a lubricant, a diurea
type thickening agent, and molybdenum compounds as additives (see,
for example, Patent Documents 1.about.3, 5, and 6). Rotational
resistance of constant velocity universal joints used in cars is
greatly influenced by hardness of a boot in addition to internal
resistance of the constant velocity universal joints. In
particular, at a low temperature, start-up torque and rotational
resistance increase which leads to deterioration of operation
performance such as steering. To reduce rotational resistance of
constant velocity universal joints, there have been proposed
constant velocity universal joints equipped with a boot to inhibit
grease leak from the joints or entry of contamination into the
joints, wherein the boot is made of silicone rubber material which
has a JIS K 6253 durometer hardness A of not higher than 55 at a
normal temperature (25.degree. C.) and not higher than 85 at a low
temperature (-40.degree. C.) (see, for example, Patent Document
4).
[0007] However, when various factors overlap at extremely low
temperature these grease compositions for constant velocity joints
may be insufficient in properties to reduce low temperature
rotational torque and folding torque. Accordingly, there is a need
for further improved stable performance. Moreover, if a silicone
rubber is used as a boot material, it is required for the boot
material to have oil resistance, flex resistance, water resistance,
weather resistance, heat resistance, cold resistance and the like.
However, there have not been proposed any grease compositions which
will increase lifetime of silicone rubber boot material.
Patent Document 1 JP-A-10-273692
Patent Document 2 JP-A-2001-11481
Patent Document 3 JP-A-2003-165988
Patent Document 4 JP-A-2005-214395
Patent Document 5 JP-A-2005-226038
Patent Document 6 JP-A-2006-16481
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0008] An object of the present invention is to provide a grease
composition for constant velocity joints) which reduces low
temperature rotational torque and folding torque in constant
velocity joints, and is compatible with a boot material comprising
a silicone rubber.
[0009] Another object of the present invention is to provide a
constant velocity joint in which the above grease composition is
packed.
Means for Solving the Problems
[0010] The inventors of this invention have conducted studies to
solve the above problems and found that a grease composition
comprising specific components can reduce low temperature
rotational torque and folding torque in constant velocity joints
while inhibiting deterioration of a boot material comprising a
silicone rubber. The grease composition for constant velocity
joints of the present invention has been completed based on this
finding.
[0011] The present invention provides the following grease
composition for constant velocity joints and constant velocity
joints.
1. A grease composition for constant velocity joints, which
comprises the following components (a) to (e): (a) a base oil
comprising a synthetic oil; (b) a thickening agent; (c) a
molybdenum sulfurized dialkyl dithiocarbamate; (d) a thiophosphate;
and (e) a zinc sulfurized dialkyl dithiocarbamate. 2. The grease
composition for constant velocity joints of the above item 1,
wherein the composition further comprises (f) a mixture of 30-70%
by mass of molybdenum disulfide and 70-30% by mass of a fatty acid
amide. 3. The grease composition for constant velocity joints of
the above item 1 or 2, wherein the synthetic oil in Component (a)
is a synthetic hydrocarbon oil. 4. The grease composition for
constant velocity joints of any one of the above items 1 to 3,
wherein Component (b): the thickening agent is a urea compound. 5.
The grease composition for constant velocity joints of any one of
the above items 1 to 4, wherein the content of Component (c): the
molybdenum sulfurized dialkyl dithiocarbamate is 0.1 to 10% by mass
based on the total mass of the grease composition. 6. The grease
composition for constant velocity joints of any one of the above
items 1 to 5, wherein the content of Component (d): the
thiophosphate is 0.1 to 10% by mass based on the total mass of the
grease composition. 7. The grease composition for constant velocity
joints of any one of the above items 1 to 6, wherein the content of
Component (e): the zinc sulfurized dialkyl dithiocarbamate is 0.1
to 10% by mass based on the total mass of the grease composition.
8. The grease composition for constant velocity joints of any one
of the above items 2 to 7, wherein the content of Component (f):
the mixture of 30-70% by mass of molybdenum disulfide and 70-30% by
mass of a fatty acid amide is 0.1 to 10% by mass based on the total
mass of the grease composition. 9. A constant velocity joint in
which the grease composition of any one of the above items 1 to 8
is packed.
EFFECTS OF THE INVENTION
[0012] The grease composition for constant velocity joints of the
present invention can reduce low temperature rotational torque and
folding torque in constant velocity joints and start a car even
under extremely low temperature conditions so that it is possible
to avoid troubles in constant velocity joints in extremely cold
areas.
[0013] In addition, the grease composition for constant velocity
joints of the present invention can inhibit deterioration of a boot
material comprising a silicone rubber and make the life of the boot
material longer.
BEST MODES FOR CARRYING OUT THE INVENTION
[0014] The present invention will hereafter be described more in
detail.
[0015] The grease composition for constant velocity joints of the
present invention is characterized in that it comprises the above
mentioned components (a) to (e). Preferred embodiment of the
present invention further comprises the component (f). Each of the
components will be described.
[0016] Component (a): a base oil comprising a synthetic oil used in
the invention may be one synthetic oil alone, or a mixture of two
or more synthetic oils, or a mixture of a synthetic oil and a
mineral oil. Examples of synthetic oils include ester synthetic
oils such as polyol ethers, synthetic hydrocarbon oils such as
poly-alpha-olefin and polybutene, ether synthetic oils such as
alkyldiphenyl ethers and polypropylene glycol, silicone oils,
fluorinated oils and the like. Among them, synthetic hydrocarbon
oils are preferred. The content of synthetic oils in the base oil
is preferably at least 40% by mass, and more preferably at least
60% by mass based on the total mass of the base oil.
[0017] Examples of Component (b): a thickening agent used in the
present invention include a diurea thickening agent of the
following formula (1):
R.sup.1NH--CO--NH--C.sub.6H.sub.4-p-CH.sub.2--C.sub.6H.sub.4-p-NH--CO--N-
HR.sup.2 (1)
wherein R.sup.1 and R.sup.2 may be same or different and represent
alkyl groups having 8-20 carbon atoms, preferably 8-18 carbon
atoms, aryl groups having 6-12 carbon atoms, preferably 6-7 carbon
atoms, or cycloalkyl groups having 6-12 carbon atoms, preferably
6-7 carbon atoms.
[0018] The diurea thickening agents may be prepared by, for
example, reacting a desired diisocyanate and a desired monoamine.
Preferred specific example of diisocyanate is
diphenylmethane-4,4'-diisocyanate. Examples of monoamines include
aliphatic amines, aromatic amines, cycloaliphatic amines and
mixtures thereof. Specific examples of aliphatic amines include
octylamine, dodecylamine, hexadecylamine, octadecylamine and
oleylamine. Specific examples of aromatic amines include aniline
and p-toluidine. Specific example of cycloaliphatic amine is
cyclohexylamine.
[0019] Among them, preferred are diurea thickening agents prepared
by the use of octyl amine, octadecyl amine, cyclohexyl amine or a
mixture thereof as a monoamine.
[0020] The content of Component (b): a thickening agent is one
necessary for a desired consistency and typically, it is preferably
1-20% by mass, more preferably 2-20% by mass based on the total
mass of the grease composition.
[0021] Specific examples of Component (c): a molybdenum sulfurized
dialkyl dithiocarbamate used in the present invention are
represented by the following formula (2):
[R.sup.3R.sup.4N--CS--S].sub.2--Mo.sub.2O.sub.mS.sub.n (2)
wherein R.sup.3 and R.sup.4 independently represent alkyl groups
having 1-24, preferably 2-18 carbon atoms, m is 0 to 3, n is 1 to 4
and m+n is 4.
[0022] The content of Component (c): a molybdenum sulfurized
dialkyl dithiocarbamate is preferably 0.1-10% by mass, more
preferably 0.5-5% by mass based on the total mass of the grease
composition.
[0023] Specific examples of Component (d): a thiophosphate used in
the present invention are represented by the following formula
(3):
(R.sup.5O)(R.sup.6O)P.dbd.S(OR.sup.7) (3)
wherein R.sup.5 is alkyl group having 1-24 carbon atoms, cycloalkyl
group having 5-14 carbon atoms, alkylcycloalkyl group having 5-14
carbon atoms, aryl group having 6-24 carbon atoms, alkylaryl group
having 7-24 carbon atoms, or arylalkyl group having 7-24 carbon
atoms, R.sup.6 and R.sup.7 are hydrogen atoms, alkyl groups having
1-24 carbon atoms, cycloalkyl groups having 5-24 carbon atoms,
alkylcycloalkyl groups having 5-24 carbon atoms, aryl groups having
6-24 carbon atoms, alkylaryl groups having 7-24 carbon atoms, or
arylalkyl groups having 7-24 carbon atoms.
[0024] Preferred are thiophosphates of the formula wherein R.sup.5,
R.sup.6 and R.sup.7 are alkyl groups having 8-18 carbon atoms, or
alkylaryl groups having 7-24 carbon atoms, and particularly
preferred are trialkylphenyl thiophosphates of the formula wherein
R.sup.5, R.sup.6 and R.sup.7 are alkylphenyl groups having 8-24
carbon atoms,
[0025] The content of Component (d): a thiophosphate is preferably
0.1-10% by mass, more preferably 1-8% by mass, most preferably 2-6%
by mass based on the total mass of the grease composition.
[0026] Specific examples of Component (e): a zinc sulfurized
dialkyl dithiocarbamate used in the present invention are
represented by the following formula (4):
(R.sup.8--CS--S).sub.2Zn (4)
wherein R.sup.8 represents alkyl group having 1-18 carbon atoms,
preferably 1-5 carbon atoms.
[0027] Component (f) used in the present invention is a mixture of
30-70% by mass of molybdenum disulfide and 70-30% by mass of a
fatty acid amide. Specific examples of fatty acid amides used in
Component (f) include monoamides of the formula (5) and bisamides
of the formula (6):
R.sup.9--CO--NH.sub.2 (5)
R.sup.10--CONH--R.sup.11--NHCO--R.sup.12 (6)
wherein R.sup.9, R.sup.10 and R.sup.12 may be same or different and
represent alkyl groups having 1-24 carbon atoms, preferably 8-18
carbon atoms and R.sup.11 represents alkylene group having 2-8
carbon atoms.
[0028] Among them, preferred are palmitic acid amide and stearic
acid amide, and particularly preferred is stearic acid amide.
[0029] Molybdenum disulfide used in Component (f) of the present
invention has been widely used in constant velocity joints as a
solid lubricant. It is known as a lubricating mechanism that
molybdenum disulfide has a layered lattice structure and is easily
sheared into thin layered shapes by sliding motion to reduce
friction resistance. It is also effective to inhibit seizing of
constant velocity joints.
[0030] The content of Component (f) is preferably 0.1-10% by mass,
more preferably 0.5-5% by mass based on the total mass of the
grease composition.
[0031] The grease composition of the present invention may comprise
in addition to the above components, conventional additives usually
used in grease compositions such as other extreme pressure agents,
antioxidants, antirust agents, and anticorrosives.
[0032] Examples of constant velocity joints of the present
invention of which torque transmission element is spherical body
include fixed type constant velocity joints such as Rzeppa type and
Birfield type, and slide type constant velocity joints such as
double offset type and cross groove type. These joints use balls as
torque transmission elements which are placed on a track formed
between an outer race and an inner race of the constant velocity
joints and are fit through a cage into the groove.
[0033] Examples of fixed type constant velocity joints of the
present invention include Rzeppa type and Birfield type mentioned
above which can be operated at large angles of 45 degree or
more.
[0034] Examples of slide type constant velocity joints of the
present invention include double offset type and cross groove type
mentioned above which can not be operated at large angles
comparable to fixed type constant velocity joints but can be slid
in the direction of drive axels.
[0035] The present invention will be explained with reference to
the following Examples.
EXAMPLES
Examples 1-5 and Comparative Examples 1-8
Preparation of Grease Compositions
[0036] A base oil (460 g) and diphenylmethane-4,4'-diisocyanate
(38.7 g) were mixed in a first container and heated to
70-80.degree. C. (degrees C.). A base oil (460 g), cyclohexylamine
(24.6 g) and octadecylamine (16.7 g) were mixed in a second
container and heated to 70-80.degree. C. The mixture was added to
the first container and reacted for 30 minutes under sufficient
stirring. Then, the mixture was heated to 160.degree. C. and
allowed to cool to obtain a base urea grease. To the base grease,
additives and a base oil were added in amounts specified in Tables
1 and 2 and the mixtures were kneaded by a three roll mill to
adjust worked penetration to No. 1 grade.
Evaluation
[0037] The inventors have found that folding torque correlates with
friction coefficient measured by TE-77 friction coefficient tester
and low temperature torque correlates with data measured by low
temperature torque test (JIS K 2220) and therefore, they were
evaluated by the data measured by the tester and the test.
Friction Resistance
[0038] passed .smallcircle.: less than 0.050 of friction
coefficient by TE-77 test
[0039] failed x: not less than 0.050 of friction coefficient by
TE-77 test
Low Temperature Property
[0040] passed .smallcircle.: not higher than 600 mNm of torque at
-40.degree. C.
[0041] failed x: (higher than 600 mNm of torque at -40.degree.
C.
Compatibility with Silicone Rubber Boot Material
[0042] According to JIS K 6258 (Method for judgment of liquid
resistance for vulcanized rubber and thermoplastic rubber) and JIS
K 6251 (Method for judgment of properties for vulcanized rubber and
thermoplastic rubber), change in tensile strength (%)(change in TB
at 150.degree. C. for 72 hours) was evaluated.
Compatibility with Silicone Rubber Boot Material
[0043] passed .smallcircle.: higher than -20% of TB change
[0044] failed x: not higher than -20% of TB change
TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 (a) Synthetic oil *.sup.1
36.4 36.4 36.4 35.6 53.4 Mineral oil 54.6 53.6 53.6 53.4 35.6 (b)
Diurea 5 5 5 5 5 (c) MoDTC *.sup.2 2 2 2 2 2 (d) thiophosphate
*.sup.3 1 1 1 1 1 (e) ZnDTC *.sup.4 1 1 1 1 1 (f) MoS.sub.2 *.sup.5
-- 1 -- 1 1 Fatty acid amide *.sup.6 -- -- 1 1 1 (g) ZnDTP *.sup.7
-- -- -- -- -- Friction coefficient by 0.044 0.044 0.044 0.040
0.040 TE-77 test Low temperature torque 230 230 230 220 160
(rotation) Silicone rubber material -4 -5 -5 -4 -4 immersion test
1) Friction coefficient .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. 2) Low temperature property
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 3) Silicone rubber boot .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. material
compatibility
TABLE-US-00002 TABLE 2 Comparative Example 1 2 3 4 5 6 7 8 (a)
Synthetic oil *.sup.1 -- 37.2 36.4 36.0 36.8 36.8 36.4 36.0 Mineral
oil 89.0 55.8 54.6 54.0 55.2 55.2 54.6 54.0 (b) Diurea 5 5 5 5 5 5
5 5 (c) MoDTC *.sup.2 2 2 -- 2 2 2 2 2 (d) thiophosphate *.sup.3 1
-- 1 -- 1 -- -- -- (e) ZnDTC *.sup.4 1 -- 1 1 -- 1 -- -- (f)
MoS.sub.2 *.sup.5 1 -- 1 1 -- -- 1 1 Fatty acid amide *.sup.6 1 --
1 1 -- -- 1 1 (g) ZnDTP *.sup.7 -- -- -- -- -- -- -- 1 Friction
coefficient by 0.043 0.066 0.096 0.054 0.053 0.061 0.063 0.052
TE-77 test Low temperature torque 900 230 230 230 230 230 230 230
(rotation) Silicone rubber material -12 -4 -4 -5 -5 -4 -5 -80
immersion test 1) Friction coefficient .smallcircle. x x x x x x x
2) Low temperature x .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. property 3)
Silicone rubber boot .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. x material
compatibility *.sup.1 Synthetic oil (poly-alpha-olefin: kinematic
viscosity at 100.degree. C. is 10 mm.sup.2/s) *.sup.2 Molybdenum
sulfurized dialkyl dithiocarbamate *.sup.3 Trialkylphneyl
thiophosphate *.sup.4 Zinc sulfurized dialkyl dithiocarbamate
*.sup.5 Molybdenum disulfide *.sup.6 Stearic acid amide *.sup.7
Zinc dithiophosphate
Results
[0045] The above results show that the grease composition for
constant velocity joints of Examples 1-5 of the present invention
comprising Components (a) to (e) are superior to those of
Comparative Examples 1-8 wherein any one or more of Components (a),
(c) to (e) is not included in low temperature torque and folding
torque and also in compatibility with a silicone rubber boot
material.
[0046] The grease compositions of Examples 4 and 5 which comprise
both molybdenum disulfide and stearic acid amide show lower folding
torque than those of Examples 2 and 3 which comprises one of them.
The grease composition of Example 5 which comprises the synthetic
oil in a higher ratio is much lower in low temperature rotational
torque.
[0047] In contrast, the grease composition of Comparative Example 1
which does not comprise Component (a) (a synthetic oil) is high in
low temperature rotational torque, the grease composition of
Comparative Example 2 which does not comprise Components (d) and
(e), and that of Comparative Example 3 which does not comprise
Component (c) are high in folding torque, those of Comparative
Examples 4 to 8 which do not comprise Components (d) and/or (e) are
high in folding torque, and that of Comparative Example 8 which
comprises Component (g) (zinc dithiophosphate) is low in
compatibility with a silicone rubber boot material.
* * * * *