U.S. patent application number 11/757976 was filed with the patent office on 2007-11-15 for lubricant composition for ball joint and ball joint.
This patent application is currently assigned to NIPPON OIL CORPORATION. Invention is credited to Takashi Arai, Hirotsugu Kinoshita, Kiyomi Sakamoto.
Application Number | 20070265179 11/757976 |
Document ID | / |
Family ID | 19043664 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070265179 |
Kind Code |
A1 |
Kinoshita; Hirotsugu ; et
al. |
November 15, 2007 |
LUBRICANT COMPOSITION FOR BALL JOINT AND BALL JOINT
Abstract
A lubricant composition for ball joints exhibits excellent low
friction not only at ordinary temperatures but also from higher to
lower temperatures, and will not leak out of ball joints at higher
temperatures. A ball joint has the lubricant composition sealed
therein. The lubricant composition contains a base oil including a
synthetic hydrocarbon oil, a thickener, and a fatty acid salt of a
compound represented by the formula (1):
R.sup.1--NH--R.sup.2--NH.sub.2 (1) (R.sup.1: hydrocarbon group of
C1 to C24; R.sup.2: alkylene group of C2 to C4).
Inventors: |
Kinoshita; Hirotsugu;
(Yokohama-Shi, JP) ; Arai; Takashi; (Gunma,
JP) ; Sakamoto; Kiyomi; (Yokohama-Shi, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770
Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
NIPPON OIL CORPORATION
Minato-ku
JP
|
Family ID: |
19043664 |
Appl. No.: |
11/757976 |
Filed: |
June 4, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10482511 |
Dec 31, 2003 |
|
|
|
PCT/JP02/06884 |
Jul 8, 2002 |
|
|
|
11757976 |
Jun 4, 2007 |
|
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Current U.S.
Class: |
508/558 |
Current CPC
Class: |
C10M 169/06 20130101;
Y10T 403/32631 20150115; C10M 2207/128 20130101; C10M 2207/126
20130101; F16C 33/102 20130101; F16C 2326/24 20130101; C10M 2205/16
20130101; C10M 2205/0206 20130101; C10M 2215/04 20130101; C10M
2215/08 20130101; C10M 2205/024 20130101; C10M 2205/026 20130101;
C10N 2030/08 20130101; C10M 2207/1265 20130101; C10M 2205/18
20130101; C10M 2207/1285 20130101; C10N 2050/10 20130101; F16C
2326/05 20130101; C10M 2205/0225 20130101; C10N 2020/02 20130101;
C10N 2040/02 20130101; C10M 2215/065 20130101; C10M 2223/043
20130101; F16C 11/068 20130101; C10N 2040/046 20200501; C10N
2030/06 20130101 |
Class at
Publication: |
508/558 |
International
Class: |
C10L 1/22 20060101
C10L001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2001 |
JP |
2001-207722 |
Claims
1. A lubricant composition for ball joints comprising: a base oil
comprising a synthetic hydrocarbon oil; a thickener; and a fatty
acid salt of a compound represented by the formula (1):
R.sup.1--NH--R.sup.2--NH.sub.2 (1) wherein R.sup.1 is a hydrocarbon
group having 1 to 24 carbon atoms, and R.sup.2 is an alkylene group
having 2 to 4 carbon atoms; and wherein a coefficient of friction
of said lubricant composition is 0.059 to 0.067 at -20.degree.
C.
2. The composition of claim 1, wherein said synthetic hydrocarbon
oil is selected from the group consisting of copolymers of ethylene
and propylene, copolymers of ethylene and .alpha.-olefin having 5
to 12 carbon atoms, polybutene, polyisobutene, polymers of
.alpha.-olefin having 5 to 12 carbon atoms, and mixtures
thereof.
3. The composition of claim 1, wherein said thickener is selected
from the group consisting of soap thickeners, urea thickeners, and
mixtures thereof.
4. The composition of claim 1 comprising 10 to 87 wt % of said base
oil, 3 to 30 wt % of said thickener, and 10 to 87 wt % of said
fatty acid salt of a composition of formula (1), based on a total
amount of said composition.
5. The composition of claim 1 further comprising an additive
selected from the group consisting of a solid lubricant, an extreme
pressure agent, an antioxidant, an oiliness agent, a rust
inhibitor, a viscosity index improver, waxes, a metal deactivator,
and mixtures thereof.
6. A ball joint comprising a metal ball stud and a synthetic resin
seat, wherein said ball joint has a composition of claim 1 sealed
therein.
Description
[0001] This application is a Continuation of U.S. Ser. No.
10/482,511, filed Dec. 31, 2003, which is a 371 National Phase
application of PCT International Application No. PCT/JP02/06884,
filed Jul. 8, 2002, which claims priority to Japanese Patent
Application No. 2001-207722, filed Jul. 9, 2001. The contents of
all three applications is hereby incorporated by reference in their
entireties.
FIELD OF ART
[0002] The present invention relates to a lubricant composition for
ball joints and a ball joint, more specifically a lubricant
composition for ball joints having a metal ball stud and a
synthetic resin seat for use in steering or suspension systems of
automobiles, and a ball joint having such composition sealed
therein.
BACKGROUND ART
[0003] In ball joints used in steering or suspension systems of
automobiles, lubricants are sealed in. Lubricants known for such
use include a composition containing Duomeen T dioleate as a base
oil and a diamide compound (JP-62-54155-B), a composition
containing a urea-base compound as a thickener and polyethylene
wax, paraffin wax, microcrystalline wax, and/or a fatty acid amide
wax (JP-2-194095-A), and a composition containing a base oil or a
wax mixed with an amidoamine compound and a fatty acid salt for
inhibiting fluttering during high speed driving
(JP-6-240274-A).
[0004] These compositions exhibit excellent low friction at
ordinary temperatures, which property is required for ball joints,
but cannot maintain the property in higher and lower temperature
ranges, causing increased friction.
[0005] With recent progress in automobile technologies, temperature
in the engine compartment has been remarkably rising, which
requires lubricants for ball joints to exhibit low friction in a
higher temperature range. On the other hand, opportunity to use
lubricants for ball joints in cold regions has also been
increasing, which requires the lubricants to exhibit low friction
in a lower temperature range as well.
SUMMARY OF THE INVENTION
[0006] It is therefore an object of the present invention to
provide a lubricant composition for ball joints and a ball joint
which composition has an excellent friction property in ball joints
not only at ordinary temperatures but also from higher to lower
temperatures, and which will not leak out of the ball joint even at
higher temperatures.
[0007] According to the present invention, there is provided a
lubricant composition for ball joints comprising:
[0008] a base oil comprising a synthetic hydrocarbon oil;
[0009] a thickener; and
[0010] a fatty acid salt of a compound represented by the formula
(1):
[0011] R.sup.1--NH--R.sup.2--NH.sub.2 (1)
wherein R.sup.1 stands for a hydrocarbon group having 1 to 24
carbon atoms, and R.sup.2 stands for an alkylene group having 2 to
4 carbon atoms.
[0012] According to the present invention, there is also provided a
ball joint comprising a metal ball stud and a synthetic resin seat,
wherein said ball joint has the above composition sealed
therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic view of a Bowden friction apparatus
used in the friction test performed in Examples and Comparative
Examples.
PREFERRED EMBODIMENTS OF THE INVENTION
[0014] The present invention will now be discussed in detail.
[0015] In the composition of the present invention, the base oil is
a synthetic hydrocarbon oil.
[0016] Examples of the synthetic hydrocarbon oil may include
polyolefin, alkylbenzene, alkylnaphthalene, biphenyl,
diphenylalkane, and di(alkylphenyl)alkane oils, with polyolefin
oils being preferred.
[0017] The polyolefin oils may be of any kind, and those obtained
by polymerizing one or more olefins having 2 to 12 carbon atoms are
particularly preferred. More preferred polyolefins are those
obtained by polymerizing one or more of ethylene, propylene,
1-butene, 2-butene, isobutene, and straight-chain terminal olefins
having 5 to 12 carbon atoms (referred to as .alpha.-olefins
hereinbelow).
[0018] Among these, copolymers of ethylene and propylene,
copolymers of ethylene and .alpha.-olefin having 5 to 12 carbon
atoms, polybutene, polyisobutene, and polymers of .alpha.-olefin
having 5 to 12 carbon atoms are preferred, and copolymers of
ethylene and .alpha.-olefin having 5 to 12 carbon atoms, and
polymers of .alpha.-olefin having 5 to 12 carbon atoms are more
preferred.
[0019] The above olefin polymers may be subjected to hydrotreatment
before use as the base oil in the composition of the present
invention.
[0020] The synthetic hydrocarbon oil may either be a single oil or
a mixture of two or more different oils.
[0021] The base oil in the composition of the present invention may
have any viscosity. The kinematic viscosity of the base oil at
100.degree. C. is usually 1 to 600 mm.sup.2/s, preferably 2 to 150
mm.sup.2/s, and more preferably 5 to 50 mm.sup.2/s.
[0022] In the composition of the present invention, the content of
the base oil is not particularly limited. The minimum content is
preferably 10 wt %, more preferably 20 wt %, and most preferably 40
wt % of the total amount of the composition, for the friction
property at lower temperatures. The maximum content is preferably
87 wt %, more preferably 70 wt %, and most preferably 60 wt % of
the total amount of the composition, for the friction property.
[0023] The base oil in the present composition may additionally
contain base oils other than the synthetic hydrocarbon oil, for
example, oxygen-containing synthetic oils such as ester,
polyglycol, and polyphenyl ether oils, or mineral oils. However,
the mineral oils may impair the performance at lower temperatures,
and the ester oils may have adverse effects on the seat material.
Thus the content of the other base oils is preferably not higher
than 15 wt %, more preferably not higher than 10 wt %, and still
more preferably not higher than 5 wt % of the total amount of the
composition, and most preferably the other base oils are not
contained.
[0024] The thickener in the composition of the present invention is
not particularly limited, and may be of any kind. Examples of the
thickener may include soap thickeners, urea thickeners, bentone,
and silica gel. Among these, soap thickeners and urea thickeners
are preferred for not damaging the seat materials of ball
joints.
[0025] Examples of the soap thickeners may include sodium,
potassium, aluminum, and lithium soaps, with lithium soaps being
preferred for their water resistance and thermal stability. The
lithium soap may be, for example, lithium stearate or lithium
12-hydroxystearate.
[0026] Examples of the urea thickeners may include urea compounds,
urea-urethane compounds, urethane compounds, and mixtures
thereof.
[0027] Examples of the urea compounds, urea-urethane compounds, and
urethane compounds may include diurea compounds, triurea compounds,
tetraurea compounds, polyurea compounds (other than di-, tri-, and
tetraurea compounds), urea-urethane compounds, diurethane
compounds, and mixtures thereof, with diurea compounds,
urea-urethane compounds, diurethane compounds, and mixtures thereof
being preferred. Specifically, for example, one or a mixture of
compounds represented by the formula (2) is preferred:
A-CONH--R.sup.3--NHCO--B (2) wherein R.sup.3 stands for a divalent
hydrocarbon group, A and B may be the same or different and each
stands for --NHR.sup.4, --NR.sup.5R.sup.6, or --OR.sup.7, with
R.sup.4 to R.sup.7 being the same or different and each standing
for a hydrocarbon residue having 6 to 20 carbon atoms.
[0028] In the formula (2), R.sup.3 stands for a divalent
hydrocarbon group having preferably 6 to 20, more preferably 6 to
15 carbon atoms. Examples of the divalent hydrocarbon group may
include a straight or branched alkylene group, a straight or
branched alkenylene group, a cycloalkylene group, and an aromatic
group. R.sup.3 may specifically be an ethylene group, a
2,2-dimethyl-4-methyl hexylene group, or groups of the following
formulae, with the formulae (a) and (b) being particularly
preferred. ##STR1##
[0029] Examples of R.sup.4 to R.sup.7 may include a straight or
branched alkyl group, a straight or branched alkenyl group, a
cycloalkyl group, an alkylcycloalkyl group, an aryl group, an
alkylaryl group, and an arylalkyl group. Specifically, a straight
or branched alkyl group such as hexyl, heptyl, octyl, nonyl, decyl,
undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,
heptadecyl, octadecyl, nonadecyl, and eicosyl groups; a straight or
branched alkenyl group such as hexenyl, heptenyl, octenyl, nonenyl,
decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl,
pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl,
and eicosenyl groups; a cyclohexyl group; an alkylcycloalkyl group
such as methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl,
diethylcyclohexyl, propylcyclohexyl, isopropylcyclohexyl,
1-methyl-3-propylcyclohexyl, butylcyclohexyl, amylcyclohexyl,
amylmethylcyclohexyl, hexylcyclohexyl, heptylcyclohexyl,
octylcyclohexyl, nonylcyclohexyl, decylcyclohexyl,
undecylcyclohexyl, dodecylcyclohexyl, tridecylcyclohexyl, and
tetradecylcyclohexyl groups; an aryl group such as phenyl and
naphthyl groups; an alkylaryl group such as tolyl, ethylphenyl,
xylyl, propylphenyl, cumenyl, methylnaphthyl, ethylnaphthyl,
dimethylnaphthyl, and propylnaphthyl groups; or an arylalkyl group
such as benzyl, methylbenzyl, and ethylbenzyl groups, may be used.
Among these, cyclohexyl, octadecyl, and tolyl groups are
particularly preferred.
[0030] The above-mentioned diurea compound, urea-urethane compound,
or diurethane compound may be prepared, for example, by reacting a
diisocyanate represented by the formula OCN--R.sup.3--NCO and a
compound represented by the formula R.sup.4NH.sub.2,
R.sup.5R.sup.6NH, or R.sup.7OH, or a mixture thereof, in a base oil
at 10 to 200.degree. C. Here, R.sup.3 to R.sup.7 are the same as
those in the formula (2).
[0031] In the composition of the present invention, the content of
the thickener is not particularly limited. The minimum content is
preferably 3 wt %, more preferably 5 wt %, and most preferably 10
wt % of the total amount of the composition, for the friction
performance at higher temperatures and for preventing leakage from
the joint at higher temperatures. The maximum content is preferably
30 wt %, more preferably 25 wt %, and most preferably 20 wt % of
the total amount of the composition, for the friction performance
at lower temperatures and workability, in particular readiness for
injection into the joint.
[0032] The composition of the present invention contains a fatty
acid salt of a compound represented by the formula (1), in other
words, a salt of a compound of the formula (1) and a fatty
acid.
[0033] In the formula (1), R.sup.1 stands for a hydrocarbon group
having 1 to 24 carbon atoms, with an alkyl group having 12 to 18
carbon atoms, an alkenyl group having 12 to 18 carbon atoms, and an
alkadienyl group having 12 to 18 carbon atoms being preferred.
R.sup.1 may be a residue derived from natural oils and fats, such
as a hydrocarbon residue of beef tallow fatty acid.
[0034] R.sup.2 in the formula (1) stands for an alkylene group
having 2 to 4 carbon atoms, with an ethylene group being preferred
for its availability.
[0035] The fatty acid may have 1 to 24 carbon atoms, may either be
straight or branched, and saturated or unsaturated. As the fatty
acid, oleic acid is particularly preferred for its availability and
friction property.
[0036] The fatty acid salt may be prepared by reacting the compound
of the formula (1) with a fatty acid at an arbitrary mixing ratio.
The mixing ratio is arbitrary, and it is preferred to use 2 moles
of a fatty acid to 1 mole of the compound of the formula (1).
[0037] In the composition of the present invention, the content of
the fatty acid salt of the compound represented by the formula (1)
is not particularly limited. The minimum content is preferably 10
wt %, more preferably 20 wt %, and most preferably 30 wt % of the
total amount of the composition, for the friction performance at
ordinary temperatures. The maximum content is preferably 87 wt %,
more preferably 70 wt %, and most preferably 50 wt % of the total
amount of the composition, for the friction performance at lower
and higher temperatures.
[0038] The composition of the present invention may optionally
contain a solid lubricant, an extreme pressure agent, an
antioxidant, an oiliness agent, a rust inhibitor, a viscosity index
improver, and/or waxes, as long as the properties of the
composition are not impaired, or for further improving the
performance.
[0039] Examples of the solid lubricant may include graphite,
fluorinated carbon black, polytetrafluoroethylene, molybdenum
disulfide, antimony sulfide, borates of alkali metals, and borates
of alkaline earth metals.
[0040] Examples of the extreme pressure agent may include
organozinc compounds such as zinc dialkyl dithiophosphate and zinc
diaryl dithiophosphate; phosphates; and phosphites.
[0041] Examples of the antioxidant may include phenol compounds
such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol; amine
compounds such as dialkyl diphenylamine,
phenyl-.alpha.-naphthylamine, and p-alkylphenyl-.alpha.-naphthyl
amine; sulfur compounds; and phenothiazine compounds.
[0042] Examples of the oiliness agent may include amines such as
laurylamine, myristylamine, palmitylamine, stearylamine, and
oleylamine; higher alcohols such as lauryl alcohol, myristyl
alcohol, palmityl alcohol, stearyl alcohol, and oleyl alcohol;
higher fatty acids such as lauric acid, myristic acid, palmitic
acid, stearic acid, and oleic acid; fatty acid esters such as
methyl laurate, methyl myristate, methyl palmitate, methyl
stearate, and methyl oleate; amides such as laurylamide,
myristylamide, palmitylamide, stearylamide, and oleylamide; and
oils and fats.
[0043] Examples of the rust inhibitor may include metal soaps;
partial esters of a polyhydric alcohol such as sorbitan fatty acid
ester; amines; phosphoric acid; and phosphates.
[0044] Examples of the viscosity index improver may include
polymethacrylate, polyisobutylene, and polystyrene.
[0045] Examples of the waxes may include various waxes such as
natural waxes, mineral oil waxes, and synthetic waxes, more
specifically, montan wax, carnauba wax, amide compounds of a higher
fatty acid, paraffin wax, microcrystalline wax, polyolefin wax, and
ester wax.
[0046] Since the composition of the present invention contains a
synthetic hydrocarbon oil as a base oil, a thickener, and a
particular fatty acid salt, the composition, when used in a ball
joint, exhibits excellent low friction not only at ordinary
temperatures, which is characteristic of conventional greases for
ball joints, but also at higher and lower temperatures. Thus the
present composition is useful for various ball joints.
[0047] The ball joint of the present invention has a metal ball
stud and a synthetic resin seat, and has the lubricant composition
of the present invention sealed therein. The structure of the ball
joint is not particularly limited, and may be, for example, those
of conventional ball joints used in steering or suspension systems
of automobiles.
[0048] The lubricant composition of the present invention may be
sealed in the ball joint by any conventional manners.
EXAMPLES
[0049] The present invention will now be explained with reference
to Examples and Comparative Examples, but the present invention is
not limited thereto.
Examples 1-7 and Comparative Examples 1-5
[0050] A composition for each Example and Comparative Example as
shown in Table 1 was prepared by first melting the base oil and the
thickener under heating, adding and dissolving the other additives,
and passing the resulting mixture through a roll mill. The
components of the compositions are shown below. The unit for the
amounts of the components shown in Table 1 is weight percent.
Base Oils
Poly-.alpha.-olefin oil (kinematic viscosity at 100.degree. C.: 8
mm.sup.2/s)
Oligomer of ethylene-.alpha.-olefin (kinematic viscosity at
100.degree. C.: 2000 mm.sup.2/s)
Mineral oil (kinematic viscosity at 100.degree. C.: 10
mm.sup.2/s)
Thickeners
Urea thickener: diurea compound
Lithium soap: lithium stearate
Additives
Duomeen T dioleate: salt of compound of the formula (1) wherein
R.sup.1 is a hydrocarbon group of beef tallow fatty acid and
R.sup.2 is an ethylene group, and oleic acid (1:2 in molar
ratio)
Diamide compound: diamide compound of ethylene diamine and oleic
acid
Other Additives: mixture of the following additives (contents are
based on the total amount of the composition)
[0051] 1 wt % of antioxidant 1 (YOSHINOX BHT.TM., manufactured by
YOSHITOMI FINE CHEMICALS, LTD.), 0.5 wt % of antioxidant 2 (Irganox
L101.TM., manufactured by CIBA SPECIALTY CHEMICALS, CORP.), 0.45 wt
% of rust inhibitor (Peretex OS100 (trade name), manufactured by
MIYOSHI OIL & FAT CO., LTD.), and 0.05 wt % of metal
deactivator (Irgamet.TM. 39, manufactured by CIBA SPECIALTY
CHEMICALS, CORP.)
[0052] Next, the lubricant compositions prepared in Examples 1 to 5
and Comparative Examples 1 to 3, and commercially available greases
for ball joints (Comparative Examples 4 and 5) were subjected to
measurements of the coefficient of friction and the dropping point
in accordance with the methods explained below. The results are
shown in Table 1.
Method for Testing Friction Property: Bowden Test
[0053] The friction property was tested using a commercially
available Bowden friction apparatus, which is shown schematically
in FIG. 1. This apparatus has a sliding material 11 fixed on a
sample stand 10 capable of reciprocating horizontally, and a steel
ball 12 fixed in a holder and capable of pressing onto the sliding
material 11 as shown in FIG. 1. The frictional force is measured
with a strain gauge load cell 13 connected to the holder for the
steel ball 12, and recorded with a recorder, while the sample stand
10 having the sliding material 11 fixed thereon is reciprocated
horizontally in the direction of arrow H. The load may be adjusted
by selecting a weight 14, and the average moving speed of the
sample stand 10 may be adjusted steplessly. The sample was fed by
applying 0.5 g of the sample oil to the sliding material 11 before
the test.
[0054] The coefficient of friction at the initial stage of sliding
was measured under the test conditions such that the horizontal
moving speed was 3.6 mm/s and the load was 4.9 N, a commercially
available 5/32 inch precision steel ball for ball bearings was used
as the steel ball 12, and the sliding material 11 was made of a
polyacetal resin.
Performance at Higher Temperatures: Propping Point Test
[0055] The dropping point test was conducted using a tester
prescribed in JIS K2220 5.4.2 under the conditions prescribed in
5.4.4. TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 5
6 7 1 2 3 4 5 Base oil Poly-.alpha.- 18.0 13.5 27.0 18.0 18.0 40.0
18.0 -- Commer- Commer- olefin cial cial oil Product A Product B
Oligomer of 22.0 16.5 33.0 22.0 22.0 -- 22.0 -- Li-base + Li-base +
ethylene mineral poly- .alpha.-olefin oil butene Mineral oil --
45.0 45.0 Viscosity 75 75 75 75 75 8 75 -- 10 10 (mm.sup.2/sec)
(100.degree. C.) Thickener Lithium 15.0 15.0 15.0 10.0 10.0 20.0 --
13.0 soap Urea -- 10.0 -- Thickener Additive Duomeen T 43.0 53.0
23.0 43.0 43.0 38.0 48.0 85.0 40.0 40.0 dioleate Micro- 5.0 --
crystal- line wax Diamide -- 5.0 -- 13.0 13.0 -- compound Other 2.0
additives Coeffi- -20.degree. C. 0.063 0.067 0.059 0.065 0.065
0.061 0.063 1.5.ltoreq. 1.5.ltoreq. 1.5.ltoreq. 1.5.ltoreq.
1.5.ltoreq. cient 25.degree. C. 0.043 0.042 0.046 0.043 0.043 0.044
0.042 0.041 0.043 0.044 0.075 0.082 of 70.degree. C. 0.046 0.051
0.047 0.047 0.046 0.046 0.043 0.042 0.046 0.044 0.075 0.082
friction Dropping point .degree. C. 130 115 160 120 120 138 160 60
60 120 200 205
[0056] From Table 1, it is understood that the compositions of
Examples 1 to 7 according to the present invention had low
coefficients of friction not only at the ordinary temperature, but
also at the high and low temperatures, and also had proper dropping
points. On the other hand, the composition without a base oil and a
thickener (Comparative Example 1), and the composition containing a
mineral oil as a base oil and not containing a thickener
(Comparative Example 2) exhibited large coefficients of friction at
the low temperature and low dropping points. Further, the
composition containing a mineral oil as a base oil (Comparative
Example 3) exhibited a large coefficient of friction at the low
temperature. It is also understood that the commercial products in
Comparative Examples 4 and 5 exhibited higher coefficients of
friction not only at the ordinary temperature, but also at the high
and low temperatures, compared to the composition of the present
invention.
* * * * *