U.S. patent application number 09/870565 was filed with the patent office on 2002-01-31 for grease composition.
This patent application is currently assigned to Nippon Mitsubishi Oil Corporation. Invention is credited to Kinoshita, Hirotugu, Sakamoto, Kiyomi.
Application Number | 20020013232 09/870565 |
Document ID | / |
Family ID | 18669516 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020013232 |
Kind Code |
A1 |
Kinoshita, Hirotugu ; et
al. |
January 31, 2002 |
Grease composition
Abstract
A grease composition comprising a lubricant base oil and a metal
dithiocarbamate represented by the formula (1): 1 wherein R.sup.1
to R.sup.4 may be the same or different and each stands for a
hydrocarbon group having 10 to 20 carbon atoms, and X stands for a
metal or a metal-containing group. The composition has long life
even when used at a high temperature, is not harmful to humans and
the environment, and can give an extended anti-flaking life to the
rolling bearing.
Inventors: |
Kinoshita, Hirotugu;
(Yokohama-shi, JP) ; Sakamoto, Kiyomi;
(Yokohama-shi, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue, 27th Floor
New York
NY
10022
US
|
Assignee: |
Nippon Mitsubishi Oil
Corporation
|
Family ID: |
18669516 |
Appl. No.: |
09/870565 |
Filed: |
May 31, 2001 |
Current U.S.
Class: |
508/364 ;
508/363 |
Current CPC
Class: |
C10M 2201/066 20130101;
C10M 2207/283 20130101; C10M 2215/102 20130101; C10M 2219/022
20130101; C10M 2219/066 20130101; C10M 135/18 20130101; C10M
2207/021 20130101; C10M 2219/106 20130101; C10M 2219/082 20130101;
C10M 2209/02 20130101; C10M 2215/068 20130101; C10M 2201/087
20130101; C10M 2215/226 20130101; C10N 2010/12 20130101; C10M
2201/041 20130101; C10M 2209/00 20130101; C10M 2219/044 20130101;
C10M 2219/108 20130101; C10M 105/38 20130101; C10M 2209/10
20130101; C10M 2223/04 20130101; C10M 2215/067 20130101; C10M
105/18 20130101; C10M 2201/085 20130101; C10M 2201/065 20130101;
C10M 2205/04 20130101; C10M 2215/065 20130101; C10M 2215/082
20130101; C10M 2223/042 20130101; C10N 2010/10 20130101; C10M
2215/30 20130101; C10N 2010/14 20130101; C10M 133/12 20130101; C10M
2217/043 20130101; C10M 2201/105 20130101; C10M 2209/084 20130101;
C10M 2213/062 20130101; C10N 2010/02 20130101; C10N 2010/06
20130101; C10M 2201/081 20130101; C10M 2207/026 20130101; C10M
2207/125 20130101; C10M 2207/282 20130101; C10N 2010/16 20130101;
C10M 169/00 20130101; C10M 2219/046 20130101; C10M 2217/042
20130101; C10M 2207/0406 20130101; C10M 2211/06 20130101; C10M
2215/221 20130101; C10M 2215/225 20130101; C10M 2201/084 20130101;
C10M 2207/286 20130101; C10M 2219/104 20130101; C10N 2040/02
20130101; C10M 2201/082 20130101; C10M 2215/06 20130101; C10N
2010/00 20130101; C10M 2201/08 20130101; C10M 2207/04 20130101;
C10M 2201/042 20130101; C10M 2215/22 20130101; C10M 2219/102
20130101; C10N 2010/08 20130101; C10M 2219/10 20130101; C10M 119/24
20130101; C10M 2207/129 20130101; C10M 2207/2835 20130101; C10M
2207/281 20130101; C10M 2219/024 20130101; C10M 2215/066 20130101;
C10M 2219/068 20130101; C10N 2010/04 20130101; C10M 2205/026
20130101; C10M 2213/02 20130101; C10M 2215/08 20130101; C10M
2215/28 20130101; C10M 2207/289 20130101; C10M 2215/064
20130101 |
Class at
Publication: |
508/364 ;
508/363 |
International
Class: |
C10M 135/18; C10M
169/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2000 |
JP |
2000-166152 |
Claims
What is claimed is:
1. A grease composition comprising a lubricant base oil and a metal
dithiocarbamate represented by the formula (1): 6wherein R.sup.1 to
R.sup.4 are the same or different and each stands for a hydrocarbon
group having 10 to 20 carbon atoms, and X stands for a metal or a
metal-containing group.
2. The grease composition of claim 1 wherein R.sup.1 to R.sup.4 are
the same or different and each stands for a hydrocarbon group
having 12 to 20 carbon atoms.
3. The grease composition of claim 1 wherein R.sup.1 to R.sup.4 are
the same or different and each stands for a group selected from the
group consisting of a straight or branched decyl group, undecyl
group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl
group, hexadecyl group, heptadecyl group, octadecyl group,
nonadecyl group and icosyl group; a straight or branched decenyl
group, undecenyl group, dodecenyl group, tridecenyl group,
tetradecenyl group, pentadecenyl group, hexadecenyl group,
heptadecenyl group, octadecenyl group, nonadecenyl group, and
icosenyl group; a cyclopentyl group with one or more alkyl
substituents each having 1 to 15 carbon atoms; a cyclohexyl group
with one or more alkyl substituents each having 1 to 14 carbon
atoms; a cycloheptyl group with one or more alkyl substituents each
having 1 to 13 carbon atoms; naphthyl group; a phenyl group with
one or more alkyl substituents each having 1 to 14 carbon atoms;
and an alkyl group having a phenyl substituent and/or an alkylaryl
substituent.
4. The grease composition of claim 1 wherein X is a metal selected
from the group consisting of Mo, Zn, Pb, Sb, Cu and Ni.
5. The grease composition of claim 1 wherein X is a metal
containing group represented by the formula (2): 7wherein Y stands
for a metal, and each of Z.sup.1 to Z.sup.4 independently stand for
a oxygen atom or a sulfur atom.
6. The grease composition of claim 5 wherein Y stands for Mo, Zn,
Pb, Sb, Cu and Ni.
7. The grease composition of claim 1 wherein the content of said
metal dithiocarbamate is in a range of 0.05 wt % to 10 wt % with
respect to the total amount of the grease composition.
8. The grease composition of claim 1 wherein kinematic viscosity of
said base oil is in a range of 10 to 500 mm.sup.2/s at 40.degree.
C.
9. The grease composition of claim 1 further comprising a
thickener.
10. The grease composition of claim 1 wherein said thickener
comprises a compound selected from a urea compound, a urea-urethane
compound, a urethane compound and mixtures thereof.
11. The grease composition of claim 10 wherein said thickener
comprises one or more compounds represented by the following
formula (3):A--CONH--R.sup.5--NHCO--B (3)wherein R.sup.5 stands for
a divalent hydrocarbon group, A and B are the same or different and
each stands for --NHR.sup.6, --NR.sup.7R.sup.8 or --OR.sup.9, and
R.sup.6 to R.sup.9 are the same or different and each stands for a
hydrocarbon residue having 6 to 20 carbon atoms.
Description
FIELD OF ART
[0001] The present invention relates to a grease composition. More
particularly, the present invention relates to a grease composition
for preventing flaking on a race way of a rolling bearing for
electrical components and accessory devices for automotive
vehicles, e.g., alternators, electromagnetic clutches for car air
conditioners, idle pulleys and electric fan motors.
BACKGROUND ART
[0002] In automotive vehicles, there is a demand for minimizing an
engine room size for increasing cabin space and reducing size and
weight of the vehicles. To this end, size and weight of electrical
components and accessory devices such as alternators,
electromagnetic clutches for car air conditioners, idle pulleys and
electric fan motors have further been reduced. On the other hand,
there is another demand for higher performance and higher output
power of the electrical components and accessories. Therefore, for
example, reduction in output power caused by size reduction of an
alternator is compensated by increasing the designed speed.
Further, to keep up with the demand for quiet operation, the degree
of hermetic sealing of the engine room is advanced and hence the
engine room tends to be heated, so that components capable of
withstanding higher temperatures are required.
[0003] In these electrical components and accessories, rolling
bearings are used, and lubrication of the rolling bearings is
achieved mainly by using a grease.
[0004] It has been reported that the high speed rotation and heavy
load condition to meet the above demand result in early termination
of the life of the rolling bearing by flaking on the raceway.
[0005] For overcoming this problem, JP-A-1-259097, JP-A-3-28299 and
JP-A-6-17079 propose grease compositions containing an
alkyldiphenyl ether base oil and a urea type thickener. However,
none of the grease composition can sufficiently extend flaking life
of the rolling bearing. JP-A-3-210394 reports a method for
extending flaking life of the rolling bearing by addition of
passivation agent. However, when sodium nitrite, one of typical
passivation agents, is added to a grease containing amine
antioxidant for improving the life of the grease at high
temperature, sodium nitrite reacts with amine antioxidant to
produce N-nitrosoamine which is harmful to human beings.
[0006] Addition of metal dithiocarbamate has also been taken into
consideration in the art. However, a sufficient result has not been
obtained yet.
DISCLOSURE OF THE INVENTION
[0007] The object of the present invention is to provide a grease
composition which has long life even when used at a high
temperature, is not harmful to humans and the environment, and can
give an extended anti-flaking life to a rolling bearing.
[0008] According to the present invention, there is provided a
grease composition comprising a lubricant base oil and a metal
dithiocarbamate represented by the formula (1): 2
[0009] wherein R.sup.1 to R.sup.4 may be the same or different and
each stands for a hydrocarbon group having 10 to 20 carbon atoms,
and X stands for a metal or a metal-containing group.
PREFERRED EMBODIMENTS OF THE INVENTION
[0010] The grease composition of the present invention contains a
lubricant base oil and the specific metal dithiocarbamate
represented by the aforementioned formula (1).
[0011] In formula (1), R.sup.1 to R.sup.4 may be the same or
different and each stands for a hydrocarbon group having 10 to 20
carbon atoms. If the number of carbon atoms in these groups is 9 or
less, anti-flaking effect at the early stage maybe insufficient.
The number of the carbon atoms is thus 10 or more, and may
preferably be 12 or more. The number of carbon atoms is 20 or less
in terms of availability.
[0012] Examples of such hydrocarbon groups may include an alkyl
group, an alkenyl group, an alkylcycloalkyl group (i.e., an
alkyl-substituted cycloalkyl group), an aryl group, an alkylaryl
group (i.e., an alkyl-substituted aryl group), and an arylalkyl
group (i.e., an aryl-substituted alkyl group). Among these, an
alkyl group and an alkenyl group are particularly preferable for
preventing flaking at early stage.
[0013] Examples of the alkyl group may include a decyl group, an
undecyl group, a dodecyl group, a tridecyl group, a tetradecyl
group, a pentadecyl group, a hexadecyl group, a heptadecyl group,
an octadecyl group, a nonadecyl group and an icosyl group, all of
which may be straight or branched.
[0014] Examples of the alkenyl group may include a decenyl group,
an undecenyl group, a dodecenyl group, a tridecenyl group, a
tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a
heptadecenyl group, an octadecenyl group such as oleyl group, a
nonadecenyl group, and an icosenyl group, all of which may be
straight or branched.
[0015] Examples of the alkylcycloalkyl group may include a
cyclopentyl group with one or more alkyl substituents each having 1
to 15 carbon atoms (provided that the total number of carbon atoms
of all of the alkyl substituents is 5 to 15), a cyclohexyl group
with one or more alkyl substituents each having 1 to 14 carbon
atoms (provided that the total number of carbon atoms of all of the
alkyl substituents is 4 to 14), a cycloheptyl group with one or
more alkyl substituents each having 1 to 13 carbon atoms (provided
that the total number of carbon atoms of all of the alkyl
substituents is 3 to 13).
[0016] Examples of the aryl group may include a naphthyl group.
[0017] Examples of the alkylaryl group may include a phenyl group
with one or more alkyl substituents each having 1 to 14 carbon
atoms (provided that the total number of carbon atoms of all of the
alkyl substituents is 4 to 14).
[0018] Examples of the arylalkyl group may include an alkyl group
having a phenyl substituent or an alkylaryl substituent.
[0019] In formula (1), X stands for a metal or a metal-containing
group.
[0020] Examples of the metal may include Mo, Zn, Pb, Sb, Cu and Ni.
Among these metals, Zn, Cu and Ni are particularly preferable in
terms of an ecological benefit.
[0021] Examples of the metal-containing group may include the group
represented by the following formula (2) 3
[0022] In formula (2), Y stands for a metal, and each of Z.sup.1 to
Z.sup.4 independently stand for a oxygen atom or a sulfur atom. Y
may be, for example, Mo, Zn, Pb, Sb, Cu and Ni, and usually Mo.
[0023] Examples of the metal dithiocarbamate represented by the
formula (1) may include zinc didecyldithiocarbamate, zinc
diundecyldithiocarbamat- e, zinc didodecyldithiocarbamate, zinc
ditridecyldithiocarbamate, zinc ditetradecyldithicarbamate, zinc
dipentadecyldithiocarbamate, zinc dihexadecyldithiocarbamate, zinc
diheptadecyldithiocarbamate, zinc dioctadecyldithiocarbamate, zinc
dinonadecyldithiocarbamate, zinc diicosyldithiocarbamate, copper
didecyldithiocarbamate, copper diundecyldithiocarbamate, copper
didodecyldithiocarbamate, copper ditridecyldithiocarbamate, copper
ditetradecyldithiocarbamate, copper dipentadecyldithiocarbamate,
copper dihexadecyldithiocarbamate, copper
diheptadecyldithiocarbamate, copper dioctadecyldithiocarbamate,
copper dinonadecyldithiocarbamate, copper diicosyldithiocarbamate,
nickel didecyldithiocarbamate, nickel diundecyldithiocarbamate,
nickel didodecyldithiocarbamate, nickel ditridecyldithiocarbamate,
nickel ditetradecyldithiocarbamate, nickel
dipentadecyldithiocarbamate, nickel dihexadecyldithiocarbamate,
nickel diheptadecyldithiocarbamate, nickel
dioctadecyldithiocarbamate, nickel dinonadecyldithiocarbamate,
nickel diicosyldithiocarbamate, molybdenum oxysulfide
didecyldithiocarbamate, molybdenum oxysulfide
diundecyldithiocarbamate, molybdenum oxysulfide
didodecyldithiocarbamate, molybdenum oxysulfide
ditridecyldithiocarbamate- , molybdenum oxysulfide
ditetradecyldithiocarbamate, molybdenum oxysulfide
dipentadecyldithiocarbamate, molybdenum oxysulfide
dihexadecyldithiocarbamate, molybdenum oxysulfide
diheptadecyldithiocarba- mate, molybdenum oxysulfide
dioctadecyldithiocarbamate, molybdenum oxysulfide
dinonadecyldithiocarbamate, molybdenum oxysulfide
diicosyldithiocarbamate, lead didecyldithiocarbamate, lead
diundecyldithiocarbamate, lead didodecyldithiocarbamate, lead
ditridecyldithiocarbamate, lead ditetradecyldithiocarbamate, lead
dipentadecyldithiocarbamate, lead dihexadecyldithiocarbamate, lead
diheptadecyldithiocarbamate, lead dioctadecyldithiocarbamate, lead
dinonadecyldithiocarbamate, lead diicosyldithiocarbamate, antimony
didecyldithiocarbamate, antimony diundecyldithiocarbamate, antimony
didodecyldithiocarbamate, antimony ditridecyldithiocarbamate,
antimony ditetradecyldithiocarbamate, antimony
dipentadecyldithiocarbamate, antimony dihexadecyldithiocarbamate,
antimony diheptadecyldithiocarbamate- , antimony
dioctadecyldithiocarbamate, antimony dinonadecyldithiocarbamate and
antimony diicosyldithiocarbamate.
[0024] As the metal dithiocarbamate represented by the formula (1)
for use in the present invention, those which are commercially
available as a diluted form in a mineral oil or kerosene may be
employed.
[0025] The lower limit of the content of the metal dithiocarbamate
in the present grease composition (net content; i.e., if the metal
dithiocarbamate is in diluted form, the effective amount of the
metal dithiocarbamate therein with respect to the total amount of
the composition) may usually be 0.05 wt %, and preferably 0.25 wt
%. The upper limit thereof may usually be 10 wt %, and preferably 5
wt %. If the content is 0.05 wt % or more, sufficient anti-flaking
effect may be obtained and shortening of flaking life may be
prevented. If the content is more than 10 wt %, the adding amount
may fail to measure up to the expected anti-flaking effect, thus
not being preferable.
[0026] The lubricant base oil for use in the present invention may
include mineral oil and/or synthetic oil.
[0027] The mineral oil may be those obtained by conventional method
for producing lubricating oils in the field of petroleum refining.
For example, the mineral oil may be prepared by distilling crude
oil under atmospheric or reduced pressure to obtain lubricant
fractions, and purifying the fractions by one or more treatments
including solvent deasphalting, solvent extraction, hydrocracking,
solvent dewaxing, contact dewaxing, hydrofining, washing with
sulfuric acid, and clay purification.
[0028] The synthetic oil may be a poly-.alpha.-olefin such as
polybutene, a 1-octene oligomer, or a 1-decene oligomer, or a
hydride of such poly-.alpha.-olefin; a diester such as ditridecyl
glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl
adipate, or di-3-ethylhexyl sebacate; a polyol ester such as
trimethylolpropane caprylate, trimethylolpropane pelargonate,
pentaerythritol-2-ethyl hexanoate, or pentaerythritol pelargonate;
alkylnaphthalene; alkylbenzene, polyoxyalkylene glycol; polyphenyl
ether; dialkyl diphenyl ether; silicone oil or mixtures
thereof.
[0029] The kinematic viscosity of the base oil may usually be 10 to
500 mm.sup.2/s, and preferably 20 to 300 mm.sup.2/s at 40.degree.
C., but not limited thereto.
[0030] In addition to the aforementioned metal dithiocarbamate and
lubricant base oil, the grease composition of the present invention
may usually contain thickener and other optional additives.
[0031] Examples of the thickener may include soap thickeners such
as a metal soap and a complex metal soap; bentone, silica gel, a
urea compound, a urea-urethane compound, a urethane compound and
mixtures thereof.
[0032] Examples of the soap thickener may include a sodium soap, a
calcium soap, an aluminum soap, and a lithium soap.
[0033] Examples of the urea compound, urea-urethane compound and
urethane compound may include a diurea compound, a triurea
compound, a tetraurea compound, a polyurea compound (except for the
diurea compound, triurea compound and tetraurea compound), a
urea-urethane compound, a diurethane compound and mixtures thereof.
Among these, particularly preferable are diurea compound,
urea-urethane compound, diurethane compound and mixtures thereof.
More preferable are the compound represented by the following
formula (3):
A--CONH--R.sup.5--NHCO--B (3)
[0034] In formula (3), R.sup.5 stands for a divalent hydrocarbon
group. A and B may be the same or different, and each stands for
--NHR.sup.6, --NR.sup.7R.sup.8 OR --OR.sup.9. Herein R.sup.6 to
R.sup.9 may be the same or different and each stands for a
hydrocarbon residue having 6 to 20 carbon atoms.
[0035] R.sup.5 in formula (3) is preferably a divalent hydrocarbon
group having 6 to 20, particularly 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. Specific examples of
R.sup.5 may include ethylene group, 2,2-dimethyl-4-methylhexylene
group and the group represented by the following formulae: 4
[0036] Among these, the following groups are particularly
preferable: 5
[0037] Examples of the hydrocarbon residue having 6 to 20 carbon
atoms as R.sup.6 to R.sup.9 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,
or an arylalkyl group. More Specific examples thereof may include
straight or branched alkyl groups such as a hexyl group, a heptyl
group, an octyl group, a nonyl group, a decyl group, an undecyl
group, a dodecyl group, a tridecyl group, a tetradecyl group, a
pentadecyl group, a hexadecyl group, a heptadecyl group, an
octadecyl group, a nonadecyl group, or an eicosyl group; a straight
or branched alkenyl group such as a hexenyl group, a heptenyl
group, an octenyl group, a nonenyl group, a decenyl group, an
undecenyl group, a dodecenyl group, a tridecenyl group, a
tetradecenyl group a pentadecenyl group, a hexadecenyl group, a
heptadecenyl group, a octadecenyl group, a nonadecenyl group and an
eicosenyl group; a cyclohexyl group; alkylcycloalkyl groups such as
a methylcyclohexyl group, a dimethylcyclohexyl group, an
ethylcyclohexyl group, a diethylcyclohexyl group, a
propylcyclohexyl group, an isopropylcyclohexyl group, a
1-methyl-3-propylcyclohexyl group, a butylcyclohexyl group, an
amylcyclohexyl group, an amylmethylcyclohexyl group, a
hexylcyclohexyl group, a heptylcyclohexyl group, an octylcyclohexyl
group, a nonylcyclohexyl group, a decylcyclohexyl group, an
undecylcyclohexyl group, a dodecylcyclohexyl group, a
tridecylcyclohexyl group, or a tetradecylcyclohexyl group; aryl
groups such as a phenyl group or a naphthyl group; alkylaryl groups
such as a toluyl group, an ethylphenyl group, a xylyl group, a
propylphenyl group, a cumenyl group, a methylnaphthyl group, an
ethylnaphthyl group, a dimethylnaphthyl group, or a propylnaphthyl
group; or arylalkyl groups such as a benzyl group, a methylbenzyl
group, or an ethylbenzyl group. Among these, a cyclohexyl group, an
octadecyl group, and a toluyl group are particularly preferred.
[0038] The diurea compound, urea-urethane compound or diurethane
compound may be produced by reacting a diisocyanate represented by
the formular OCN--R.sup.5--NCO, with any of compounds represented
by the formulae R.sup.6NH.sub.2, R.sup.7R.sup.8NH, R.sup.9OH or
mixtures thereof, in a base oil at 10 to 200.degree. C. Herein
R.sup.5 to R.sup.9 are the same as R.sup.5 to R.sup.9 in the
formula (3).
[0039] The content of the thickener in the present composition may
usually be 2 wt % or more and preferably 3 wt % or more, and
usually 30 wt % or less and preferably 25 wt % or less.
[0040] The grease composition of the present invention may
optionally contain a solid lubricant, an extreme pressure agent, an
antioxidant, a metal deactivator, an oilness agent, a rust
inhibitor, and a viscosity index improver.
[0041] Examples of the solid lubricant may include a graphite,
fluorinated graphite, polytetrafluoroethylene, molybdenum
disulfide, antimony sulfide, alkaline (earth) metal borate,
magnesium oxide and zinc oxide.
[0042] Examples of the extreme pressure agent may include organic
zinc compounds such as zinc dialkyldithiophosphate and zinc
diaryldithiophosphate; organic molybdenum compounds such as
molybdenum dialkyldithiophosphate and molybdenum
diaryldithiophosphate; sulfur compounds such as polysulfide, and
sulfurized oil and fat; and phosphates and phosphites.
[0043] Examples of the antioxidants may include phenol compounds
such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol; amine
compounds such as dialkyldiphenylamine,
phenyl-.alpha.-naphthylamine, p-alkylphenyl-.alpha.-naphthylamine;
sulfur compounds; and phenothiazine compounds.
[0044] Examples of the metal deactivator may include benzotriazole,
benzothiazole and sodium nitrate.
[0045] Examples of the oilness 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; higher fatty acid esters such as
metyl laurate, methyl myristate, methyl palmitate, metyl stearate
and methyl oleate; amides such as laurylamide, myristylamide,
palmitylamide, stearylamide and oleylamide; and oil and fats.
[0046] Examples of the rust inhibitor may include neutral or
over-based metal sulfonates of petrol type or synthetic oil type
such as a neutral or over-based calcium sulfonate, a neutral or
over-based barium sulfonate, and a neutral or over-based zinc
sulfonate; metal soaps; polyvalent alcohol partial esters such as
sorbitan fatty acid ester; amines; phosphoric acid; and
phosphates.
[0047] Examples of the viscosity index improver may include a
polymethacryalte, a polyisobutylene and a polystylene.
[0048] There is no limitation to production method of the present
grease composition. For example, the objective grease composition
may usually be produced by adding the metal dithiocarbamate to the
base oil, stirring the mixture and optionally passing the mixture
through a roll mill.
[0049] The present grease composition may be used for lubricating a
rolling bearing, such as electrical components and accessory
devices for automotive vehicles, e.g., alternators, electromagnetic
clutches for car air conditioners, idle pulleys and electric fan
motors. The lubrication may be achieved by filling the rolling
bearing with the present grease composition.
[0050] Since the present grease composition contains the specific
metal dithiocarbamate, it can exhibit an excellent anti-flaking
property in rolling bearings such as electrical components and
accessory devices for automotive vehicles, e.g., alternators,
electromagnetic clutches for car air conditioners, idle pulleys and
electric fan motors, resulting in extension of the life of the
rolling bearings.
EXAMPLES OF THE INVENTION
[0051] The present invention will be explained in further detail
with reference to the Examples and Comparative Examples. However,
the present invention is not limited thereto.
Example 1 and 2 and Comparative Examples 1 to 3
[0052] Diphenylmethane4,4'-diisocyanate was dissolved under heat in
base oil shown in Table 1. To this mixture were added the same base
oil containing amines shown in Table 1 that had been dissolved
therein under heat. The gel substance was obtained, to which the
metal dithiocarbamate and other additives were further added. The
mixture was stirred and then passed through a roll mill, to obtain
grease compositions of Examples 1 and 2 and Comparative Examples 1
to 3.
[0053] These grease compositions of Examples 1 and 2 and
Comparative Examples 1 to 3 were then subjected to the engine
on-bench test specified as follows. The results are shown in Table
1.
[0054] <Engine On-bench Test>
[0055] A single-line deep groove ball bearing fitted with a contact
rubber seal having an inner diameter of 12 mm, an outer diameter of
37 mm and a width of 12 mm was filled with 2.0 g of the grease and
attached to an engine. The rotation of the engine was quickly
accelerated and decelerated from 1000 rpm to 6000 rpm and from 6000
rpm to 1000 rpm (rotation of outer ring of the bearing was from
1900 rpm to 11300 rpm, and from 11300 rpm to 1900 rpm), to
continuously rotate the bearing at bearing load of 190 kgf. The
running life time was measured until occurrence of flaking in a
bearing inner ring race way and fluctuation.
1 TABLE 1 Comparative Example Example 1 2 1 2 3 Base oil (wt %)
Dialkyldiphenyl ether .sup.1) 80.0 -- 82.0 80.0 80.0
Pentaerythritol ester .sup.2) -- 77.0 -- -- -- Poly-.alpha.-olefin
.sup.3) -- -- -- -- -- Thickener (wt %) 13.0 17.0 13.0 13.0 13.0
Thickener (molar ratio) Diphenylmethane-4,4'- 5 1 5 5 5
diisocyanate Cyclohexylamine 7 1 7 7 7 Octadecylamine 3 -- 3 3 3
p-toluidine -- 1 -- -- -- Zinc 2.0 -- -- -- --
ditridecyldithiocarbamate (wt %) Molybdenum -- 1.0 -- -- --
dioctadecyldithiocarbamate (wt %) Zinc dipentyldithiocarbamate --
-- -- 2.0 -- (wt %) Molybdenum -- -- -- -- 2.0
dioctyldithiocarbamate (wt %) Antioxidant .sup.4) (wt %) 3.0 3.0
3.0 3.0 3.0 Rust-preventive agent .sup.5) 2.0 2.0 2.0 2.0 2.0 (wt
%) Mixture consistency 237 272 240 243 238 Engine on-bench test
1500 1500 400 750 1000 result (h) or or more more .sup.1) Kinematic
viscosity 100 mm.sup.2/s (40.degree. C.) .sup.2) Kinematic
viscosity 50 mm.sup.2/s (40.degree. C.) .sup.3) Kinematic viscosity
40 mm.sup.2/s (40.degree. C.) .sup.4) Amine type antioxidant
.sup.5) Barium sulfonate
[0056] As obvious from the engine on-bench test results in Table 1,
the present grease composition can give a longer anti-flaking life
than the grease composition of Comparative Example 1 that does not
contain the metal dithiocarbamate and than the grease compositions
of Comparative Examples 2 and 3 that contains metal
dithiocarbamates which have hydrocarbon groups having less than 10
carbon atoms.
* * * * *