U.S. patent application number 10/590775 was filed with the patent office on 2007-08-02 for grease composition for constant velocity joint.
Invention is credited to Takashi Arai, Yukiharu Beppu, Kazuhiko Ishibashi, Hirotsugu Kinoshita, Kiyomi Sakamoto, Hiroyuki Shibuya.
Application Number | 20070179066 10/590775 |
Document ID | / |
Family ID | 34908661 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070179066 |
Kind Code |
A1 |
Sakamoto; Kiyomi ; et
al. |
August 2, 2007 |
Grease composition for constant velocity joint
Abstract
The grease composition for constant velocity joints of the
invention is characterized by comprising a lubricating base oil, a
thickener, carbon black with a mean particle size of not greater
than 500 nm, and an organic molybdenum compound. A grease
composition for constant velocity joints according to the invention
can achieve a highly satisfactory balance between anti-flaking,
anti-seizure and anti-wear without using lead compounds, and can
sufficiently maintain these properties with long-term use.
Inventors: |
Sakamoto; Kiyomi; (Kanagawa,
JP) ; Beppu; Yukiharu; (Kanagawa, JP) ;
Shibuya; Hiroyuki; (Tokyo, JP) ; Arai; Takashi;
(Kanagawa, JP) ; Kinoshita; Hirotsugu; (Kanagawa,
JP) ; Ishibashi; Kazuhiko; (Kanagawa, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
34908661 |
Appl. No.: |
10/590775 |
Filed: |
February 22, 2005 |
PCT Filed: |
February 22, 2005 |
PCT NO: |
PCT/JP05/02820 |
371 Date: |
August 25, 2006 |
Current U.S.
Class: |
508/113 |
Current CPC
Class: |
C10M 2207/126 20130101;
C10M 2201/041 20130101; C10N 2040/046 20200501; C10M 2215/065
20130101; C10M 2221/041 20130101; C10M 2215/16 20130101; C10N
2020/06 20130101; C10M 2203/1065 20130101; C10M 2223/042 20130101;
C10M 2203/1025 20130101; C10M 2219/024 20130101; C10M 2219/02
20130101; C10M 2223/045 20130101; C10M 2215/1026 20130101; C10M
2203/1006 20130101; C10M 2223/041 20130101; C10M 169/02 20130101;
C10M 2219/068 20130101; C10M 2219/022 20130101; C10N 2020/02
20130101; C10N 2010/12 20130101; C10M 2207/1285 20130101; C10M
2201/041 20130101; C10M 2207/021 20130101; C10M 2215/044 20130101;
C10M 2223/045 20130101; C10N 2010/04 20130101; C10M 2219/068
20130101; C10N 2010/12 20130101; C10M 2223/042 20130101; C10N
2010/12 20130101; C10M 2207/1285 20130101; C10N 2010/02 20130101;
C10M 2219/068 20130101; C10N 2010/12 20130101; C10M 2223/042
20130101; C10N 2010/12 20130101; C10M 2207/1285 20130101; C10N
2010/02 20130101; C10M 2223/045 20130101; C10N 2010/04
20130101 |
Class at
Publication: |
508/113 |
International
Class: |
C10M 169/04 20060101
C10M169/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 26, 2004 |
JP |
2004-052202 |
Claims
1. A grease composition for constant velocity joints, comprising a
lubricating base oil, a thickener, carbon black with a mean
particle size of not greater than 500 nm, and an organic molybdenum
compound.
2. The grease composition for constant velocity joints according to
claim 1, further comprising at least one from among sulfur-based
extreme pressure agents, phosphorus-based extreme pressure agents
and zinc-based extreme pressure agents.
3. The grease composition for constant velocity joints according to
claim 1, further comprising at least one selected from among
complexes of fatty acid salts and carbonates, wherein said fatty
acids are overbased by the carbonates, and organic acid salts.
Description
TECHNICAL FIELD
[0001] The present invention relates to a grease composition for
constant velocity joints.
BACKGROUND ART
[0002] Constant velocity joints are joints for a shaft transmitting
a driving force from a transmission of a car to its tires Types of
constant velocity joints include fixed constant velocity joints
such as Barfield joints, Rzeppa joints and undercutting free
joints, and slide type constant velocity joints such as
double-offset joints, tripod joints, and cross-groove joints; and
the like.
[0003] Constant velocity joints must exhibit performance such as
anti-flaking, anti-seizure, anti-wear and low-friction properties.
Such performance is ensured by using constant velocity joint
greases that in most cases are produced by mixing a base grease
comprising a lubricating oil base and lithium soap or urea-based
thickener, with additives such as molybdenum disulfide and lead
compounds. [0004] [Patent document 1] Japanese Unexamined Patent
Publication HEI No. 04-304300 [0005] [Patent document 2] Japanese
Unexamined Patent Publication HEI No. 06-57283
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0006] The higher performance and smaller and lighter weights of
automobiles in recent years has led to a tendency toward increasing
loads on constant velocity joints. However, the aforementioned
conventional greases are not always satisfactory from the viewpoint
of anti-flaking, anti-seizure, anti-wear and low-friction
properties, and much room for improvement still remains for
achieving high-performance, long-lived constant velocity joints
used under heavy loads.
[0007] As mentioned above, lead compounds are sometimes used as
additives in conventional greases, and the use of lead compounds is
preferably minimized due to human safety and environmental
considerations.
[0008] It is an object of the present invention to provide a grease
composition for constant velocity joints that achieves a highly
satisfactory balance between anti-flaking, anti-seizure, anti-wear
and low-friction properties without using lead compounds, and that
can sufficiently maintain these properties with long-term use.
MEANS FOR SOLVING THE PROBLEMS
[0009] In order to achieve this object, the grease composition for
constant velocity joints is characterized by comprising a
lubricating base oil, a thickener, carbon black with a mean
particle size of not greater than 500 nm, and an organic molybdenum
compound.
[0010] By combining the aforementioned carbon black with an organic
molybdenum compound and a thickener in a lubricating base oil, it
is possible to achieve a high-level balance between anti-flaking,
anti-seizure and anti-wear, and to sufficiently maintain these
properties with long-term use. Thus, a grease composition for
constant velocity joints according to the invention can effectively
increase performance and lengthen the practical life of constant
velocity joints without using lead compounds.
[0011] The grease composition for constant velocity joints
according to the invention preferably further comprises at least
one selected from among sulfur-based extreme pressure agents,
phosphorus-based extreme pressure agents and zinc-based extreme
pressure agents. This will permit further improvements in
anti-flaking, anti-seizure and anti-wear.
[0012] Moreover, the grease composition for constant velocity
joints according to the invention preferably also further comprises
at least one selected from among complexes of fatty acid salts and
carbonates, wherein the fatty acid is overbased by the carbonate,
and organic acid salts. This will permit further improvements in
anti-flaking and anti-seizure.
EFFECT OF THE INVENTION
[0013] According to the invention there is provided a grease
composition for constant velocity joints that can achieve a
high-level balance between anti-flaking, anti-seizure and
anti-wear, and can sufficiently maintain these properties with
long-term use, without the use of lead compounds.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] Preferred embodiments of the invention will now be described
in detail.
[0015] As lubricating base oils for the grease composition for
constant velocity joints of the invention there may be mentioned
mineral oils and/or synthetic oils. As mineral oils there may be
mentioned mineral oils obtained by lubricating oil production
processes ordinarily employed in the petroleum refining industry,
and more specifically these include naphthene-based and
paraffin-based mineral oils purified by subjecting crude oil to
atmospheric distillation or vacuum distillation to yield
lubricating oil fractions, and then applying one or more types of
treatment such as solvent deasphalting, solvent extraction,
hydrocracking, solvent dewaxing, catalytic dewaxing, hydrogenation
refining, sulfuric acid cleaning, clay treatment and the like.
[0016] As synthetic oils there may be mentioned, specifically, poly
.alpha.-olefins such as polybutene, 1-octene oligomers and 1-decene
oligomers, and their hydrogenated forms; diesters such as
ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate,
ditridecyl adipate and di-3-ethylhexyl sebacate, polyol esters such
as trimethylolpropane caprylate, trimethylolpropane pelargonate,
pentaerythritol 2-ethyl hexanoate and pentaerythritol pelargonate,
alkylnaphthalenes; alkylbenzenes; polyoxyalkylene glycols;
polyphenyl ether; dialkyldiphenyl ether; silicone oils, and
mixtures thereof.
[0017] The kinematic viscosity of the lubricating base oil at
100.degree. C. is preferably 2-40 mm.sup.2/s and more preferably
3-20 mm.sup.2/s. The viscosity index of the lubricating base oil is
preferably 90 or greater and more preferably 100 or greater.
[0018] According to the invention, any one of the aforementioned
lubricating base oils may be used alone or two or more thereof may
be used in combination, but preferably naphthene-based mineral oils
are used from the standpoint of excellent anti-flaking,
anti-seizure and anti-wear. The boot used for the constant velocity
joint is composed of a rubber material such as chloroprene rubber
(CR) or chlorinated polyethylene rubber (CM), or a resin material
such as a polyester-based thermoplastic elastomer (TPE) or the
like, and naphthene-based mineral oils are preferred from the
viewpoint of compatibility with the boot material.
[0019] Here, "compatibility with the boot material" means minimal
adverse effect on the boot material and a property of adequately
preventing grease leakage due to strength reduction or damage to
the boot.
[0020] Also, "naphthene-based mineral oil" means the lubricating
oil fraction obtained by refining of naphthene crude oil with a
high naphthene content. Specifically, there may be mentioned
lubricating oil fractions obtained by atmospheric distillation and
vacuum distillation of naphthene crude oil, and then refinement by
one type of treatment alone or two or more types of treatment in
appropriate combination selected from among solvent deasphalting,
solvent extraction, hydrocracking, solvent dewaxing, catalytic
dewaxing, hydrogenation refining, sulfuric acid cleaning, clay
treatment and the like.
[0021] The properties of the naphthene-based mineral oil used for
the invention are not particularly restricted, but the
naphthene-based mineral oil preferably has a % Cn of 35-70, more
preferably 40-65 and even more preferably 45-60. Also, the
naphthene-based mineral oil preferably has a % Cp of 20-55, more
preferably 25-50 and even more preferably 30-45. Here the % Cn and
% Cp are, respectively, the % Cn and % Cp measured based on
"Standard Test Method for Calculation Distribution and Structural
Group Analysis of Petroleum Oils by the n-d-M Method" specified by
ASTM-D-3238.
[0022] The aniline point of the naphthene-based mineral oil is
preferably not higher than 90.degree. C., more preferably not
higher than 85.degree. C. and even more preferably not higher than
80.degree. C. Here, "aniline point" means the aniline point
measured according to "Test Method for Petroleum Product Aniline
Point and Mixed Aniline Point" of JIS K 2256.
[0023] The pour point of the naphthene-based mineral oil is
preferably not higher than -20.degree. C., more preferably not
higher than -30.degree. C. and even more preferably not higher than
-40.degree. C. Here, "pour point" means the pour point measured
according to "Test Method For Crude Oil and Petroleum Product Pour
Point and Petroleum Product Clouding Point" of JIS K 2269.
[0024] From the standpoint of reducing adverse effects on thermal
stability, the sulfur content of the naphthene-based mineral oil is
preferably not greater than 1500 ppm by mass, more preferably not
greater than 800 ppm by mass, even more preferably not greater than
500 ppm by mass, yet more preferably not greater than 100 ppm by
mass and most preferably not greater than 50 ppm by mass based on
the total amount of the naphthene-based mineral oil. Here, "sulfur
content" means the sulfur content measured according to
"Inductively Coupled Plasma-Atomic Emission Method", an attachment
to "Crude Oil and Petroleum Products--Test Method For Sulfur
Content" of JIS K 2541, and the sulfur content includes disulfide
sulfurs, mercaptanes, alkyl sulfides, alkyl disulfides, thiophane,
thiophene, sulfonic acid and the like.
[0025] From the standpoint of reducing adverse effects on thermal
stability, the nitrogen content of the naphthene-based mineral oil
is preferably not greater than 500 ppm by mass, more preferably not
greater than 200 ppm by mass, even more preferably not greater than
150 ppm by mass, yet more preferably not greater than 100 ppm by
mass and most preferably not greater than 50 ppm by mass based on
the total amount of the naphthene-based mineral oil. Here,
"nitrogen content" means the nitrogen content measured according to
the trace coulometric titration method specified by "Crude Oil and
Petroleum Products--Test Method For Nitrogen Content" of JIS K
2609, and the nitrogen content includes inorganic ammonia compounds
such as ammonia, ammonium sulfate, ammonium carbonate and ammonium
chloride, and heterocyclic compounds such as pyridine, quinoline
and naphthene bases.
[0026] From the standpoint of low-temperature pour properties, the
viscosity index of the naphthene-based mineral oil is preferably at
least -10, more preferably at least 0, even more preferably at
least 10, yet more preferably at least 20 and most preferably at
least 30. Here, "viscosity index" means the viscosity index
calculated according to the "Crude Oil and Petroleum
Products--Kinematic viscosity Test Method and Viscosity Index
Calculation Method" of JIS K 2283.
[0027] When the grease composition of the invention comprises a
naphthene-based mineral oil, the content of the naphthene-based
mineral oil is preferably 3-40% by mass and more preferably 5-30%
by mass based on the total amount of the composition. If the
naphthene-based mineral oil content is less than 3% by mass, the
addition will tend to be insufficient for improving the
anti-flaking, anti-seizure, anti-wear and compatibility with the
boot material. Also, if the naphthene-based mineral oil content
exceeds 40% by mass, an improving effect in the anti-flaking,
anti-seizure and anti-wear will be obtained, but compatibility with
the boot material will tend to be reduced.
[0028] As thickeners there may be used various types of thickeners
including soap-based thickeners such as metal soaps and complex
metal soaps, and non-soap-based thickeners such as bentone, silica
gel and urea-based thickeners (urea compounds, urea/urethane
compounds, urethane compounds, etc.). From the viewpoint of heat
resistance, urea compounds, urea/urethane compounds, urethane
compounds and their mixtures are preferred.
[0029] As specific examples of soap-based thickeners there may be
mentioned sodium soaps, calcium soaps, aluminum soaps and lithium
soaps.
[0030] As examples of urea-based thickeners there may be mentioned
urea compounds such as diurea compounds, triurea compounds,
tetraurea compounds and polyurea compounds (other than diurea
compounds, triurea compounds and tetraurea compounds), urethane
compounds such as urea compounds, urea/urethane compounds and
diurethane compounds, and mixtures thereof, among which diurea
compounds, urea/urethane compounds, diurethane compounds and
mixtures thereof are preferred.
[0031] As preferred examples of urea-based thickeners there may be
mentioned compounds represented by general formula (1) below. The
compounds represented by general formula (1) include diurea
compounds, urea/urethane compounds and diurethane compounds.
A-CONH--R.sup.1--NHCO--B (1) In general formula (1), R.sup.1
represents a divalent organic group and preferably a divalent
hydrocarbon group. As divalent hydrocarbon groups there may be
mentioned, specifically, straight-chain or branched alkylene
groups, straight-chain or branched alkenylene groups, cycloalkylene
groups, arylene groups, alkylarylene groups, arylalkylene groups
and the like. The number of carbon atoms of the divalent organic
group represented by R.sup.1 is preferably 6-20 and more preferably
6-15.
[0032] As preferred examples of divalent organic groups represented
by R.sup.1 there may be mentioned ethylene,
2,2-dimethyl-4-methylhexylene and groups represented by the
following formulas (2)-(11), among which groups represented by
formulas (3) and (5) are preferred. ##STR1## ##STR2## In general
formula (1), A and B may be the same or different, and each
represents an NHR.sup.2, --NR.sup.3R.sup.4 or --OR.sup.5 group.
Here, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may be the same or
different, and each represents a monovalent organic group and
preferably a C6-20 monovalent hydrocarbon group.
[0033] As examples of C6-20 monovalent hydrocarbon groups
represented by R.sup.2, R.sup.3, R.sup.4 and R.sup.5 there may be
mentioned straight-chain or branched alkyl, straight-chain or
branched alkenyl, cycloalkyl, alkylcycloalkyl, aryl, alkylaryl and
arylalkyl. More specifically, there may be mentioned straight-chain
or branched alkyl groups such as hexyl, heptyl, octyl, nonyl,
decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,
hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl;
straight-chain or branched alkenyl groups such as hexenyl,
heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl,
tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl,
nonadecenyl and eicosenyl; cyclohexyl groups; alkylcyclohexyl
groups 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; aryl groups such as
phenyl and naphthyl; alkylaryl groups such as tolyl, ethylphenyl,
xylyl, propylphenyl, cumenyl, methylnaphthyl, ethylnaphthyl,
dimethylnaphthyl and propylnaphthyl; and arylalkyl groups such as
benzyl, methylbenzyl and ethylbenzyl, among which alkyl,
cycloalkyl, alkylcycloalkyl, aryl and alkylaryl groups are
preferred from the viewpoint of heat resistance and anti-acoustic
properties.
[0034] A compound represented by general formula (1) may be
obtained, for example, by reacting a diisocyanate represented by
OCN--R.sup.1--NCO with a compound represented by R.sup.2NH.sub.2,
R.sup.3R.sup.4NH or R.sup.5OH or a mixture thereof, in a base oil
at 10-200.degree. C. R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5
in the formulas representing the starting material compounds have
the same respective definitions as R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 of the compounds represented by general formula
(1).
[0035] From the standpoint of heat resistance, particularly
preferred compounds among those represented by general formula (1)
are compounds wherein A and B are NHR.sup.2, i.e. compounds
represented by general formula (12) below. In general formula (12),
R.sup.1 is a divalent organic group and R.sup.2 is a monovalent
organic group, and they are equivalent to R.sup.1 and R.sup.2
mentioned above. ##STR3## The thickener content is preferably at
least 2% by mass and more preferably at least 5% by mass based on
the total amount of the composition. If the thickener content is
less than 2% by mass the effect of adding the thickener will be
insufficient, making it difficult to satisfactorily produce a
grease from the grease composition. The thickener content is
preferably not greater than 30% by mass and more preferably not
greater than 20% by mass based on the total amount of the
composition. If the thickener content is greater than 30% by mass
the grease composition will become excessively hard, making it
difficult to obtain satisfactory lubricating performance.
[0036] The grease composition for constant velocity joints
according to the invention also comprises as essential components
carbon black with a mean particle size of not greater than 500 nm
and an organic molybdenum compound, in addition to the
aforementioned lubricating base oil and thickener.
[0037] Carbon black consists of black particles with a diameter of
about 3-500 nm obtained by momentarily (for a few milliseconds)
heating crude hydrocarbons (oil, gas, etc.) at high temperature
(for example, 300-1800.degree. C. and preferably 800-1800.degree.
C.) for conversion to carbon, and it is distinguished from
graphite. For example, the crystal structure of graphite consists
of hexagonal (or trigonal polygonal) flat sheets, whereas carbon
black consists of unit particles of a type of amorphous carbon with
fine crystals aggregated in a complex manner, and the fine crystals
have a random layer structure with aggregation of several layers of
aromatic planar molecules with average diameters of 20-30 .ANG..
Carbon black also forms a structure with the unit particles linking
together into chains, and acidic fuinctional groups may be present
on the surfaces of the particles. When graphite is used instead of
carbon black, insufficient anti-flaking, anti-seizure and anti-wear
properties are exhibited.
[0038] As mentioned above, the mean particle size of the carbon
black used for the invention is preferably not greater than 500 nm
and more preferably not greater than 100 nm. If the mean particle
size of the carbon black is greater than 500 nm, insufficient
anti-flaking, anti-seizure and anti-wear properties are exhibited.
There is no particular restriction on the lower limit for the mean
particle size, but from the standpoint of production ease and
availability, it will normally be at least 10 nm and preferably at
least 15 nm. Here, the "mean particle size" is the mean particle
size (mean diameter) of the unit particles of the carbon black, and
it is the average value of measurement with an electron
microscope.
[0039] The process for producing the carbon black used for the
invention is not particularly restricted so long as the mean
particle size is within the aforementioned range. As typical
production processes there may be mentioned the furnace process,
acetylene process, lamp process, thermal process and channel
process.
[0040] The carbon black content is preferably at least 0.05% by
mass and more preferably at least 0.1% by mass based on the total
amount of the composition. If the carbon black content is below
this lower limit, the effect of improving the anti-flaking,
anti-seizure and anti-wear by addition of the carbon black will
tend to be inadequate. The carbon black content is preferably at
least not greater than 15% by mass and more preferably not greater
than 10% by mass based on the total amount of the composition. If
the carbon black content is above this upper limit, no further
effect of improving the anti-flaking, anti-seizure and anti-wear
will be achieved corresponding to the increased content.
[0041] As examples of organic molybdenum compounds to be used for
the invention there may be mentioned the phosphoric acid or
thiophosphoric acid ester derivatives represented by general
formula (13) below, and the dithiocarbamic acid ester derivatives
represented by general formula (14) below. ##STR4## In general
formulas (13) and (14), each R.sup.6 may be the same or different
and represents a Cl or greater hydrocarbon group, each X may be the
same or different and represents oxygen or sulfur, and a, b and c
each represent an integer of 1-6.
[0042] As examples of hydrocarbon groups represented by R.sup.6 in
general formulas (13) and (14) there may be mentioned C1-24 alkyl,
C5-7 cycloalkyl, C6-11 alkylcycloalkyl, C6-18 aryl, C7-24 alkylaryl
and C7-12 arylalkyl.
[0043] As the aforementioned alkyl groups there may be mentioned,
specifically, methyl, ethyl, propyl (including all branched
isomers), butyl (including all branched isomers), pentyl (including
all branched isomers), hexyl (including all branched isomers),
heptyl (including all branched isomers), octyl (including all
branched isomers), nonyl (including all branched isomers), decyl
(including all branched isomers), undecyl (including all branched
isomers), dodecyl (including all branched isomers), tridecyl
(including all branched isomers), tetradecyl (including all
branched isomers), pentadecyl (including all branched isomers),
hexadecyl (including all branched isomers), heptadecyl (including
all branched isomers), octadecyl (including all branched isomers),
nonadecyl (including all branched isomers), eicosyl (including all
branched isomers), heneicosyl (including all branched isomers),
docosyl (including all branched isomers), tricosyl (including all
branched isomers) and tetracosyl (including all branched isomers).
As the aforementioned cycloalkyl groups there may be mentioned,
specifically, cyclopentyl, cyclohexyl and cycloheptyl.
[0044] As the aforementioned alkylcycloalkyl groups there may be
mentioned, specifically, methylcyclopentyl (including all
substituted isomers), ethylcyclopentyl (including all substituted
isomers), dimethylcyclopentyl (including all substituted isomers),
propylcyclopentyl (including all branched isomers and substituted
isomers), methylethylcyclopentyl (including all substituted
isomers), trimethylcyclopentyl (including all substituted isomers),
butylcyclopentyl (including all branched isomers and substituted
isomers), methylpropylcyclopentyl (including all branched isomers
and substituted isomers), diethylcyclopentyl (including all
substituted isomers), dimethylethylcyclopentyl (including all
substituted isomers), methylcyclohexyl (including all substituted
isomers), ethylcyclohexyl (including all substituted isomers),
dimethylcyclohexyl (including all substituted isomers),
propylcyclohexyl (including all branched isomers and substituted
isomers), methylethylcyclohexyl (including all substituted
isomers), trimethylcyclohexyl (including all substituted isomers),
butylcyclohexyl (including all branched isomers and substituted
isomers), methylpropylcyclohexyl (including all branched isomers
and substituted isomers), diethylcyclohexyl (including all
substituted isomers), dimethylethylcyclohexyl (including all
substituted isomers), methylcycloheptyl (including all substituted
isomers), ethylcycloheptyl (including all substituted isomers),
dimethylcycloheptyl (including all substituted isomers),
propylcycloheptyl (including all branched isomers and substituted
isomers), methylethylcycloheptyl (including all substituted
isomers), trimethylcycloheptyl (including all substituted isomers),
butylcycloheptyl (including all branched isomers and substituted
isomers), methylpropylcycloheptyl (including all branched isomers
and substituted isomers), diethylcycloheptyl (including all
substituted isomers) and dimethylethylcycloheptyl (including all
substituted isomers).
[0045] As the aforementioned aryl groups there may be mentioned,
specifically, phenyl and naphthyl.
[0046] As the aforementioned alkylaryl groups there may be
mentioned, specifically, tolyl (including all substituted isomers),
xylyl (including all substituted isomers), ethylphenyl (including
all substituted isomers), propylphenyl (including all branched
isomers and substituted isomers), methylethylphenyl (including all
substituted isomers), trimethylphenyl (including all substituted
isomers), butylphenyl (including all branched isomers and
substituted isomers), methylpropylphenyl (including all branched
isomers and substituted isomers), diethylphenyl (including all
substituted isomers), dimethylethylphenyl (including all
substituted isomers), pentylphenyl (including all branched isomers
and substituted isomers), hexylphenyl (including all branched
isomers and substituted isomers), heptylphenyl (including all
branched isomers and substituted isomers), octylphenyl (including
all branched isomers and substituted isomers), nonylphenyl
(including all branched isomers and substituted isomers),
decylphenyl (including all branched isomers and substituted
isomers), undecylphenyl (including all branched isomers and
substituted isomers), dodecylphenyl (including all branched isomers
and substituted isomers), tridecylphenyl (including all branched
isomers and substituted isomers), tetradecylphenyl (including all
branched isomers and substituted isomers), pentadecylphenyl
(including all branched isomers and substituted isomers),
hexadecylphenyl (including all branched isomers and substituted
isomers), heptadecylphenyl (including all branched isomers and
substituted isomers) and octadecylphenyl (including all branched
isomers and substituted isomers).
[0047] As examples of the aforementioned arylalkyl groups there may
be mentioned benzyl, phenethyl, phenylpropyl (including all
branched isomers) and phenylbutyl (including all branched
isomers).
[0048] As specific compounds represented by general formulas (13)
and (14) above there may be mentioned molybdenum phosphate,
molybdenum thiophosphate, molybdenum dithiophosphate and molybdenum
dithiocarbamate.
[0049] The phosphoric acid or thiophosphoric acid ester derivatives
represented by general formula (13) and the dithiocarbamic acid
ester derivatives represented by general formula (14) are usually
obtained by reacting a phosphoric acid ester, thiophosphoric acid
ester or dithiocarbamic acid ester with an inorganic molybdenum
compound (molybdenum trioxide, molybdic acid or its salt, etc.),
together with a sulfur source if necessary.
[0050] Molybdenum can adopt different valence states, and therefore
the aforementioned reaction generally yields a mixture of
compounds. The most typical compounds among these are compounds
represented by the following formulas (15) and (16). ##STR5##
(wherein R.sup.6 and X have the same definitions as R.sup.6 and X
in formula (13)).
[0051] According to the invention, any one of the compounds
represented by general formulas (13) and (14) above may be used
alone as an organic molybdenum compound or both may be used in
combination, but from the standpoint of thermal stability it is
preferred to use a compound represented by general formula
(14).
[0052] The organic molybdenum compound content is preferably at
least 0.1% by mass and more preferably at least 0.5% by mass based
on the total amount of the composition. If the organic molybdenum
compound content is not at least 0.1% by mass, the anti-flaking,
anti-seizure and anti-wear of the grease will not be adequate. The
upper limit is 20% by mass and preferably 10% by mass. If the
content exceeds 20% by mass, no further improvement in
anti-flaking, anti-seizure and anti-wear will be obtained
corresponding to the greater amount.
[0053] The grease composition for constant velocity joints
according to the invention comprises the lubricating base oil, the
thickener, the carbon black with a mean particle size of not
greater than 500 nm and. the organic molybdenum compound as
described above, but it also preferably further contains at least
one selected from among sulfur-based extreme pressure agents,
phosphorus-based extreme pressure agents and zinc-based extreme
pressure agents.
[0054] As sulfur-based extreme pressure agents there may be
mentioned dihydrocarbyl polysulfides, sulfurized esters, sulfurized
mineral oils, thiazole compounds and thiadiazole compounds.
[0055] Dihydrocarbyl polysulfides are sulfur-based compounds
generally known as polysulfides or sulfurized olefins, and
specifically they are represented by the following general formula
(17). R.sup.7--S.sub.x--R.sup.8 (17)
[0056] In general formula (17), R.sup.7 and R.sup.8 may be the same
or different and each represents C3-20 straight-chain or branched
alkyl, C6-20 aryl, C6-20 alkylaryl or C6-20 arylalkyl, and x
represents an integer of 2-6 and preferably 2-5.
[0057] As alkyl groups represented by R.sup.7 and R.sup.8 above
there may be mentioned, specifically, n-propyl, isopropyl, n-butyl,
isobutyl, sec-butyl, tert-butyl, straight-chain or branched pentyl,
straight-chain or branched hexyl, straight-chain or branched
heptyl, straight-chain or branched octyl, straight-chain or
branched nonyl, straight-chain or branched decyl, straight-chain or
branched undecyl, straight-chain or branched dodecyl,
straight-chain or branched tridecyl, straight-chain or branched
tetradecyl, straight-chain or branched pentadecyl, straight-chain
or branched hexadecyl, straight-chain or branched heptadecyl,
straight-chain or branched octadecyl, straight-chain or branched
nonadecyl and straight-chain or branched eicosyl.
[0058] As aryl groups represented by R.sup.7 and R.sup.8 there may
be mentioned, specifically, phenyl and naphthyl.
[0059] As alkylaryl groups represented by R.sup.7 and R.sup.8 there
may be mentioned, specifically, tolyl (including all structural
isomers), ethylphenyl (including all structural isomers),
straight-chain or branched propylphenyl (including all structural
isomers), straight-chain or branched butylphenyl (including all
structural isomers), straight-chain or branched pentylphenyl
(including all structural isomers), straight-chain or branched
hexylphenyl (including all structural isomers), straight-chain or
branched heptylphenyl (including all structural isomers),
straight-chain or branched octylphenyl (including all structural
isomers), straight-chain or branched nonylphenyl (including all
structural isomers), straight-chain or branched decylphenyl
(including all structural isomers), straight-chain or branched
undecylphenyl (including all structural isomers), straight-chain or
branched dodecylphenyl (including all structural isomers), xylyl
(including all structural isomers), ethylmethylphenyl (including
all structural isomers), diethylphenyl (including all structural
isomers), di(straight-chain or branched) propylphenyl (including
all structural isomers), di(straight-chain or branched) butylphenyl
(including all structural isomers), methylnaphthyl (including all
structural isomers), ethylnaphthyl (including all structural
isomers), straight-chain or branched propylnaphthyl (including all
structural isomers), straight-chain or branched butylnaphthyl
(including all structural isomers), dimethylnaphthyl (including all
structural isomers), ethylmethylnaphthyl (including all structural
isomers), diethylnaphthyl (including all structural isomers),
di(straight-chain or branched) propylnaphthyl (including all
structural isomers) and di(straight-chain or branched)
butylnaphthyl (including all structural isomers).
[0060] As arylalkyl groups represented by R.sup.7 and R.sup.8 there
may be mentioned, specifically, benzyl, phenylethyl (including all
isomers) and phenylpropyl (including all isomers).
[0061] R.sup.7 and R.sup.8 are both preferably C3-18 alkyl, C6-8
aryl, C7-8 alkylaryl or C7-8 arylalkyl derived from propylene,
1-butene or isobutylene.
[0062] Specifically, as preferred alkyl groups there may be
mentioned isopropyl, isopropyl, branched hexyl derived from
propylene dimer (including all branched isomers), branched nonyl
derived from propylene trimer (including all branched isomers),
branched dodecyl derived from propylene tetramer (including all
branched isomers), branched pentadecyl derived from propylene
pentamer (including all branched isomers), branched octadecyl
derived from propylene hexamer (including all branched isomers),
sec-butyl, tert-butyl, branched octyl derived from 1-butene dimer
(including all branched isomers), branched octyl derived from
isobutylene dimer (including all branched isomers), branched
dodecyl derived from 1-butene trimer (including all branched
isomers), branched dodecyl derived from isobutylene trimer
(including all branched isomers), branched hexadecyl derived from
1-butene tetramer (including all branched isomers) and branched
hexadecyl derived from isobutylene tetramer (including all branched
isomers). Phenyl may be mentioned as a preferred aryl group. As
preferred alkylaryl groups there may be mentioned tolyl (including
all structural isomers), ethylphenyl (including all structural
isomers) and xylyl (including all structural isomers). As preferred
arylalkyl groups there may be mentioned benzyl and phenethyl
(including all isomers).
[0063] From the standpoint of achieving superior anti-flaking and
anti-seizure, more preferably R.sup.7 and R.sup.8 each separately
represent a C3-18 branched alkyl group derived from ethylene or
propylene, and most preferably a C6-15 branched alkyl group derived
from ethylene or propylene.
[0064] The dihydrocarbyl polysulfide used may be one with any
sulfur content, but from the viewpoint of anti-flaking and
anti-seizure, it is preferred to use one with a sulfur content of
10-55% by mass and preferably 20-50% by mass.
[0065] As specific examples of sulfurized esters there may be
mentioned esters obtained by using desired methods for
sulfidization of animal and vegetable oils such as beef tallow,
lard, fish oil, rapeseed oil and soybean oil; unsaturated fatty
acid esters obtained by reacting unsaturated fatty acids (including
oleic acid, linoleic acid and fatty acids extracted from the
aforementioned animal and vegetable oils) with various alcohols;
and mixtures thereof, which have been sulfurized by any desired
process.
[0066] Although the sulfurized ester may have any desired sulfur
content, from the standpoint of anti-flaking and anti-seizure the
sulfur content is usually 2-40% by mass and preferably 5-35% by
mass.
[0067] Sulfurized mineral oils are obtained by dissolving elemental
sulfur in mineral oils. There are no particular restrictions on
mineral oils to be used for the invention, and specifically there
may be mentioned the mineral oil-based lubricating base oils
mentioned above as examples of lubricating base oils. The elemental
sulfur may be used in any of various forms such as bulk, powder or
molten liquid forms, but using it in powder or molten liquid form
is preferred as it allows efficient dissolution in the base oil.
Using elemental sulfur in molten liquid form is advantageous in
that the liquids will mix together allowing the dissolution process
to be accomplished in a very short time, but this requires the
handling temperature to be above the melting point of elemental
sulfur and therefore necessitates special equipment such as heating
devices, while handling in such high-temperature environments is
dangerous and difficult. In contrast, elemental sulfur powder is
inexpensive and easy to manage while its dissolution time is
sufficiently short, and it is therefore particularly preferred.
There are no particular restrictions on the sulfur content of the
sulfurized mineral oil, but for most purposes it is preferably
0.05-1.0% by mass and more preferably 0.1-0.5% by mass based on the
total amount of the sulfurized mineral oil.
[0068] As thiazole compounds there are preferably used compounds
represented by the following general formulas (18) and (19).
##STR6## (wherein R.sup.9 and R.sup.10 each represent hydrogen, a
C1-30 hydrocarbon group or an amino group, R.sup.11 represents
hydrogen or a C1-4 alkyl group and d and e represent integers of
0-3).
[0069] Particularly preferred among these are benzothiazole
compounds represented by general formula (19) above. As mentioned
above, Rlo in general formula (19) represents hydrogen, a C1-30
hydrocarbon group or an amino group, but R.sup.10 is preferably
hydrogen or a C1-18 hydrocarbon group and more preferably it is
hydrogen or a C1-12 hydrocarbon group. Also as mentioned above,
R.sup.11 represents hydrogen or a C1-4 alkyl group, but R.sup.11 is
preferably hydrogen or a C1-3 alkyl group and more preferably it is
hydrogen or a C1-2 hydrocarbon group. Also, "e" in general formula
(19) is an integer of 0-3 as mentioned above, but it is preferably
0-2. As specific examples of such benzothiazole compounds there may
be mentioned benzothiazole, 2-mercaptobenzothiazole,
2-(hexyldithio)benzothiazole, 2-(octyldithio)benzothiazole,
2-(decyldithio)benzothiazole, 2-(dodecyldithio)benzothiazole and
2-(N,N-diethyldithiocarbamyl) benzothiazole.
[0070] As thiadiazole compounds there are preferably used
1,3,4-thiadiazole compounds represented by general formula (20)
below, 1,2,4-thiadiazole compounds represented by general formula
(21) below, and 1,4,5-thiadiazole compounds represented by general
formula (22) below. ##STR7## [In general formulas (20), (21) and
(22), R.sup.12, R.sup.13, R.sup.14 R.sup.15, R.sup.16 and R.sup.17
may be the same or different and each represents hydrogen or a
C1-20 hydrocarbon group, and c, d, e, f, g and h may be the same or
different and each represents an integer of 0-8.]
[0071] As mentioned above, R.sup.12, R.sup.13, R.sup.14, R.sup.15,
R.sup.16 and R.sup.17 in general formulas (20)-(22) above each
represent hydrogen or a C1-20 hydrocarbon group, but R.sup.12,
R.sup.13, R.sup.14, R.sup.15, R.sup.16 and R.sup.17 are preferably
each hydrogen or a C1-18 hydrocarbon group and more preferably
hydrogen or a C1-12 hydrocarbon group. Also as mentioned above, c,
d, e, f, g and h in general formulas (7)-(9) each represent an
integer of 0-3, but c, d, e, f, g and h are preferably each an
integer of 0-2. As specific examples of such thiadiazole compounds
there may be mentioned 2,5-bis(n-hexyldithio)-1,3,4-thiadiazole,
2,5-bis(n-octyldithio)-1,3,4-thiadiazole,
2,5-bis(n-nonyldithio)-1,3,4-thiadiazole,
2,5-bis(1,1,3,3-tetramethylbutyldithio)-1,3,4-thiadiazole,
3,5-bis(n-hexyldithio)-1,2,4-thiadiazole,
3,5-bis(n-octyldithio)-1,2,4-thiadiazole,
3,5-bis(n-nonyldithio)-1,2,4-thiadiazole,
3,5-bis(1,1,3,3-tetramethylbutyldithio)-1,2,4-thiadiazole,
4,5-bis(n-hexyldithio)-1,2,3-thiadiazole,
4,5-bis(n-octyldithio)-1,2,3-thiadiazole,
4,5-bis(n-nonyldithio)-1,2,3-thiadiazole and
4,5-bis(1,1,3,3-tetramethylbutyldithio)-1,2,3-thiadiazole.
[0072] As sulfur-based extreme pressure agents to be used for the
invention there are particularly preferred dihydrocarbyl
polysulfides and sulfurized esters among those mentioned above,
from the viewpoint of anti-flaking, anti-seizure and anti-wear.
[0073] When a sulfur-based extreme pressure agent is included in
the grease composition for constant velocity joints of the
invention, the content is not particularly restricted but is
preferably 0.05-20% by mass, more preferably 0.1-15% by mass and
even more preferably 0.5-10% by mass based on the total
composition.
[0074] As phosphorus-based additives there are preferred one or
more selected from among phosphoric acid esters, acidic phosphoric
acid esters, acidic phosphoric acid ester amine salts, phosphorous
acid esters and phosphorothionates.
[0075] Among these phosphorus-based additives, the phosphoric acid
esters, acidic phosphoric acid esters, acidic phosphoric acid ester
amine salts and phosphorous acid esters are esters of phosphoric
acid or phosphorous acid with alkanols or polyether-type alcohols,
or derivatives thereof.
[0076] More specifically, as phosphoric acid esters there may be
mentioned tributyl phosphate, tripentyl phosphate, trihexyl
phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl
phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl
phosphate, tritridecyl phosphate, tritetradecyl phosphate,
tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl
phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl
phosphate, tricresyl phosphate, trixylenyl phosphate,
cresyldiphenyl phosphate and xylenyldiphenyl phosphate; [0077] as
acidic phosphoric acid esters there may be mentioned monobutyl acid
phosphate, monopentyl acid phosphate, monohexyl acid phosphate,
monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid
phosphate, monodecyl acid phosphate, monoundecyl acid phosphate,
monododecyl acid phosphate, monotridecyl acid phosphate,
monotetradecyl acid phosphate, monopentadecyl acid phosphate,
monohexadecyl acid phosphate, monoheptadecyl acid phosphate,
monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl
acid phosphate, dipentyl acid phosphate, dihexyl acid phosphate,
diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid
phosphate, didecyl acid phosphate, diundecyl acid phosphate,
didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl
acid phosphate, dipentadecyl acid phosphate, dihexadecyl acid
phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate
and dioleyl acid phosphate; [0078] as acidic phosphoric acid ester
amine salts there may be mentioned salts of amines, such as
methylamine, ethylamine, propylamine, butylamine, pentylamine,
hexylamine, heptylamine, octylamine, dimethylamine, diethylamine,
dipropylamine, dibutylamine, dipentylamine, dihexylamine,
diheptylamine, dioctylamine, trimethylamine, triethylamine,
tripropylamine, tributylamine, tripentylamine, trihexylamine,
triheptylamine and trioctylamine, with the aforementioned acidic
phosphoric acid esters; [0079] as chlorinated phosphoric acid
esters there may be mentioned tris-dichloropropyl phosphate,
tris-chloroethyl phosphate, tris-chlorophenyl phosphate and
polyoxyalkylene-bis[di(chloroalkyl)]phosphate; and as phosphorous
acid esters there may be mentioned dibutyl phosphite, dipentyl
phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl
phosphite, dinonyl phosphite, didecyl phosphite, diundecyl
phosphite, didodecyl phosphite, dioleyl phosphite, diphenyl
phosphite, dicresyl phosphite, tributyl phosphite, tripentyl
phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl
phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl
phosphite, tridodecyl phosphite, trioleyl phosphite, triphenyl
phosphite and tricresyl phosphite. These compounds may also be used
in admixture.
[0080] As phosphorothionates there are preferably used compounds
represented by the following general formula (23). ##STR8## [In
this formula, R.sup.18, R.sup.19 and R.sup.20 may be the same or
different, and each represents C1-24 hydrocarbon group.]
[0081] As C1-24 hydrocarbon groups represented by R.sup.18,
R.sup.19 and, R.sup.20 there may be mentioned, specifically, alkyl,
cycloalkyl, alkenyl, alkylcycloalkyl, aryl, alkylaryl and
arylalkyl.
[0082] As examples of alkyl groups there may be mentioned alkyl
groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,
octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,
pentadecyl, hexadecyl, heptadecyl. and octadecyl (where the alkyl
groups may be straight-chain or branched).
[0083] As examples of cycloalkyl groups there may be mentioned C5-7
cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl.
As examples of the aforementioned alkylcycloalkyl groups there may
be mentioned C6-11 alkylcycloalkyl groups such as
methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl,
diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl,
methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl,
dimethylcycloheptyl, methylethylcycloheptyl and diethylcycloheptyl
(with any positions of substitution of the alkyl groups on the
cycloalkyl groups).
[0084] As examples of alkenyl groups there may be mentioned alkenyl
groups such as butenyl, pentenyl, hexenyl, heptenyl, octenyl,
nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl,
pentadecenyl, hexadecenyl, heptadecenyl and octadecenyl (where the
alkenyl groups may be straight-chain or branched, and the double
bonds may be at any positions).
[0085] As examples of aryl groups there may be mentioned aryl
groups such as phenyl and naphthyl. As examples of the
aforementioned alkylaryl groups there may be mentioned C7-18
alkylaryl groups such as tolyl, xylyl, ethylphenyl, propylphenyl,
butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl,
nonylphenyl, decylphenyl, undecylphenyl and dodecylphenyl (where
the alkyl groups may be straight-chain or branched and substituted
at any positions on the aryl groups).
[0086] As examples of arylalkyl groups there may be mentioned C7-12
arylalkyl groups such as benzyl, phenylethyl, phenylpropyl,
phenylbutyl, phenylpentyl and phenylhexyl (where the alkyl groups
may be straight-chain or branched).
[0087] The C1-24 hydrocarbon groups represented by R.sup.18,
R.sup.19 and R.sup.20 are preferably alkyl, aryl or alkylaryl, and
more preferably C4-18 alkyl, C7-24 alkylaryl or phenyl.
[0088] As phosphorothionates represented by general formula (23)
there may be mentioned, specifically, tributyl phosphorothionate,
tripentyl phosphorothionate, trihexyl phosphorothionate, triheptyl
phosphorothionate, trioctyl phosphorothionate, trinonyl
phosphorothionate, tridecyl phosphorothionate, triundecyl
phosphorothionate, tridodecyl phosphorothionate, tritridecyl
phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl
phosphorothionate, trihexadecyl phosphorothionate, triheptadecyl
phosphorothionate, trioctadecyl phosphorothionate, trioleyl
phosphorothionate, triphenyl phosphorothionate, tricresyl
phosphorothionate, trixylenyl phosphorothionate, cresyldiphenyl
phosphorothionate, xylenyldiphenyl phosphorothionate,
tris(n-propylphenyl) phosphorothionate, tris(isopropylphenyl)
phosphorothionate, tris(n-butylphenyl) phosphorothionate,
tris(isobutylphenyl) phosphorothionate, tris(s-butylphenyl)
phosphorothionate and tris(t-butylphenyl) phosphorothionate. These
compounds may also be used in admixture.
[0089] When a phosphorus-based extreme pressure agent is included
in the grease composition for constant velocity joints of the
invention, the content is not particularly restricted but is
preferably 0.01-15% by mass, more preferably 0.05-10% by mass and
even more preferably 0.1-5% by mass based on the total
composition.
[0090] As zinc-based extreme pressure agents there may be mentioned
the zinc dithiophosphate compounds represented by general formula
(24) below, the zinc dithiocarbamate compounds represented by
general formula (25) below and zinc salts of the phosphorus
compounds represented by general formulas (26) and (27) below.
##STR9## (wherein R.sup.21, R.sup.22, R.sup.23 and R.sup.24 may be
the same or different and each represents a C1 or greater
hydrocarbon group) ##STR10## (wherein R.sup.25, R.sup.26, R.sup.27
and R.sup.28 may be the same or different and each represents a C1
or greater hydrocarbon group) ##STR11## (wherein each Y represents
oxygen or sulfur, at least two of the three Ys are oxygen, and
R.sup.29, R.sup.30 and R.sup.31 may be the same or different and
each represents hydrogen or a C1-30 hydrocarbon group) ##STR12##
(wherein each Y represents oxygen or sulfur, at least three of the
four Ys are oxygen, and R.sup.32, R.sup.33 and R.sup.34 may be the
same or different and each represents hydrogen or a C1-30
hydrocarbon group)
[0091] As examples of hydrocarbon groups represented by
R.sup.21-R.sup.28 in general formulas (24) and (25) there may be
mentioned C1-24 alkyl, C5-7 cycloalkyl, C6-11 alkylcycloalkyl,
C6-18 aryl, C7-24 alkylaryl and C7-12 arylalkyl groups.
[0092] As alkyl groups there may be mentioned, specifically,
methyl, ethyl, propyl (including all branched isomers), butyl
(including all branched isomers), pentyl (including all branched
isomers), hexyl (including all branched isomers), heptyl (including
all branched isomers), octyl (including all branched isomers),
nonyl (including all branched isomers), decyl (including all
branched isomers), undecyl (including all branched isomers),
dodecyl (including all branched isomers), tridecyl (including all
branched isomers), tetradecyl (including all branched isomers),
pentadecyl (including all branched isomers), hexadecyl (including
all branched isomers), heptadecyl (including all branched isomers),
octadecyl (including all branched isomers), nonadecyl (including
all branched isomers), eicosyl (including all branched isomers),
heneicosyl (including all branched isomers), docosyl (including all
branched isomers), tricosyl (including all branched isomers) and
tetracosyl (including all branched isomers).
[0093] As cycloalkyl groups there may be mentioned, specifically,
cyclopentyl, cyclohexyl and cycloheptyl.
[0094] As alkylcycloalkyl groups there may be mentioned,
specifically, methylcyclopentyl (including all substituted
isomers), ethylcyclopentyl (including all substituted isomers),
dimethylcyclopentyl (including all substituted isomers),
propylcyclopentyl (including all branched isomers and substituted
isomers), methylethylcyclopentyl (including all substituted
isomers), trimethylcyclopentyl (including all substituted isomers),
butylcyclopentyl (including all branched isomers and substituted
isomers), methylpropylcyclopentyl (including all branched isomers
and substituted isomers), diethylcyclopentyl (including all
substituted isomers), dimethylethylcyclopentyl (including all
substituted isomers), methylcyclohexyl (including all substituted
isomers), ethylcyclohexyl (including all substituted isomers),
dimethylcyclohexyl (including all substituted isomers),
propylcyclohexyl (including all branched isomers and substituted
isomers), methylethylcyclohexyl (including all substituted
isomers), trimethylcyclohexyl (including all substituted isomers),
butylcyclohexyl (including all branched isomers and substituted
isomers), methylpropylcyclohexyl (including all branched isomers
and substituted isomers), diethylcyclohexyl (including all
substituted isomers), dimethylethylcyclohexyl (including all
substituted isomers), methylcycloheptyl (including all substituted
isomers), ethylcycloheptyl (including all substituted isomers),
dimethylcycloheptyl (including all substituted isomers),
propylcycloheptyl (including all branched isomers and substituted
isomers), methylethylcycloheptyl (including all substituted
isomers), trimethylcycloheptyl (including all substituted isomers),
butylcycloheptyl (including all branched isomers and substituted
isomers), methylpropylcycloheptyl (including all branched isomers
and substituted isomers), diethylcycloheptyl (including all
substituted isomers) and dimethylethylcycloheptyl (including all
substituted isomers).
[0095] As examples of aryl groups there may be mentioned phenyl and
naphthyl.
[0096] As examples of alkylaryl groups there may be mentioned tolyl
(including all substituted isomers), xylyl (including all
substituted isomers), ethylphenyl (including all substituted
isomers), propylphenyl (including all branched isomers and
substituted isomers), methylethylphenyl (including all substituted
isomers), trimethylphenyl (including all substituted isomers),
butylphenyl (including all branched isomers and substituted
isomers), methylpropylphenyl (including all branched isomers and
substituted isomers), diethylphenyl (including all substituted
isomers), dimethylethylphenyl (including all substituted isomers),
pentylphenyl (including all branched isomers and substituted
isomers), hexylphenyl (including all branched isomers and
substituted isomers), heptylphenyl (including all branched isomers
and substituted isomers), octylphenyl (including all branched
isomers and substituted isomers), nonylphenyl (including all
branched isomers and substituted isomers), decylphenyl (including
all branched isomers and substituted isomers), undecylphenyl
(including all branched isomers and substituted isomers),
dodecylphenyl (including all branched isomers and substituted
isomers), tridecylphenyl (including all branched isomers and
substituted isomers), tetradecylphenyl (including all branched
isomers and substituted isomers), pentadecylphenyl (including all
branched isomers and substituted isomers), hexadecylphenyl
(including all branched isomers and substituted isomers),
heptadecylphenyl (including all branched isomers and substituted
isomers) and octadecylphenyl (including all branched isomers and
substituted isomers).
[0097] As examples of arylalkyl groups there may be mentioned
benzyl, phenethyl, phenylpropyl (including all branched isomers)
and phenylbutyl (including all branched isomers).
[0098] As specific C1-30 hydrocarbon groups represent by
R.sup.29-R.sup.34 for zinc salts of the phosphorus compounds
represented by general formulas (26) and (27) above, there may be
mentioned alkyl, cycloalkyl, alkenyl, alkylcycloalkyl, aryl,
alkylaryl and arylalkyl groups.
[0099] As examples the aforementioned alkyl groups there may be
mentioned alkyl groups such as methyl, ethyl, propyl, butyl,
pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl,
tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and
octadecyl (where the alkyl groups may be straight-chain or
branched).
[0100] As examples of the aforementioned cycloalkyl groups there
may be mentioned C5-7 cycloalkyl groups such as cyclopentyl,
cyclohexyl and cycloheptyl. As examples of the aforementioned
alkylcycloalkyl groups there may be mentioned C6-11 alkylcycloalkyl
groups such as methylcyclopentyl, dimethylcyclopentyl,
methylethylcyclopentyl,. diethylcyclopentyl, methylcyclohexyl,
dimethylcyclohexyl, methylethylcyclohexyl, diethylcyclohexyl,
methylcycloheptyl, dimethylcycloheptyl, methylethylcycloheptyl and
diethylcycloheptyl (with any positions of substitution of the alkyl
groups on the cycloalkyl groups).
[0101] As examples of the aforementioned alkenyl groups there may
be mentioned alkenyl groups such as butenyl, pentenyl, hexenyl,
heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl,
tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl
and octadecenyl (where the alkenyl groups may be straight-chain or
branched, and the double bonds may be at any positions).
[0102] As examples of the aforementioned aryl groups there may be
mentioned aryl groups such as phenyl and naphthyl. As examples of
the aforementioned alkylaryl groups there may be mentioned C7-18
alkylaryl groups such as tolyl, xylyl, ethylphenyl, propylphenyl,
butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl,
nonylphenyl, decylphenyl, undecylphenyl and dodecylphenyl (where
the alkyl groups may be straight-chain or branched and substituted
at any positions on the aryl groups).
[0103] As examples of the aforementioned arylalkyl groups there may
be mentioned C7-12 arylalkyl groups such as benzyl, phenylethyl,
phenylpropyl, phenylbutyl, phenylpentyl and phenylhexyl (where the
alkyl groups may be straight-chain or branched).
[0104] The C1-30 hydrocarbon groups represented by
R.sup.29-R.sup.34 are preferably C1-30 alkyl groups or C6-24 aryl
groups, and are more preferably C3-18 alkyl groups and even more
preferably C4-12 alkyl groups.
[0105] R.sup.29, R.sup.30 and R.sup.31 may be the same or different
and each represents hydrogen or one of the aforementioned
hydrocarbon groups, but preferably one to three from among
R.sup.29, R.sup.30 and R.sup.31 are the aforementioned hydrocarbon
groups, more preferably one or two are the aforementioned
hydrocarbon groups, and even more preferably two are the
aforementioned hydrocarbon groups.
[0106] Also, R.sup.32, R.sup.33 and R.sup.34 may be the same or
different and each represents hydrogen or one of the aforementioned
hydrocarbon groups, but preferably one to three from among
R.sup.32, R.sup.33 and R.sup.34 are the aforementioned hydrocarbon
groups, more preferably one or two are the aforementioned
hydrocarbon groups, and even more preferably two are the
aforementioned hydrocarbon groups.
[0107] In the phosphorus compounds represented by general formula
(26), at least two of the three Ys must be oxygen, but preferably
all of the Ys are oxygen.
[0108] In the phosphorus compounds represented by general formula
(27), at least three of the four Ys must be oxygen, but preferably
all of the Ys are oxygen.
[0109] As examples of phosphorus compounds represented by general
formula (26) there may be mentioned phosphorous acid and
monothiophosphorous acid; phosphorous acid monoesters and
monothiophosphorous acid monoesters having one of the
aforementioned C1-30 hydrocarbon groups; phosphorous acid diesters
and monothiophosphorous acid diesters having two of the
aforementioned C1-30 hydrocarbon groups; phosphorous acid triesters
and monothiophosphorous acid triesters having three of the
aforementioned C1-30 hydrocarbon groups; and mixtures thereof.
Among these, phosphorous acid monoesters and phosphorous acid
diesters are preferred, and phosphorous acid diesters are
especially preferred.
[0110] As examples of phosphorus compounds represented by general
formula (27) there may be mentioned phosphoric acid and
monothiophosphoric acid; phosphoric acid monoesters and
monothiophosphoric acid monoesters having one of the aforementioned
C1-30 hydrocarbon groups; phosphoric acid diesters and
monothiophosphoric acid diesters having two of the aforementioned
C1-30 hydrocarbon groups; phosphoric acid triesters and
monothiophosphoric acid triesters having three of the
aforementioned C1-30 hydrocarbon groups; and mixtures thereof.
Among these, phosphoric acid monoesters and phosphoric acid
diesters are preferred, and phosphoric acid diesters are especially
preferred.
[0111] Zinc salts of phosphorus compounds represented by general
formulas (26) and (27) will differ in structure depending on the
number of OH groups or SH groups of the phosphorus compound, and
therefore no restrictions are placed on the structure. For example,
when 1 mole of zinc oxide is reacted with 2 moles of a phosphoric
acid diester (one OH group), a compound with the structure
represented by the following formula (28) may be obtained as the
main component, although polymerized molecules may also be present
(where R in the formula represents a C1-30 hydrocarbon group).
##STR13## Also, for example, when 1 mole of zinc oxide is reacted
with 1 mole of a phosphoric acid monoester (two OH groups), a
compound having the structure represented by the following formula
(29) may be obtained as the main component, although polymerized
molecules may also be present (where R in the formula represents a
C1-30 hydrocarbon group). ##STR14## Moreover, the grease
composition for constant velocity joints according to the invention
preferably also further contains at least one selected from among
complexes of fatty acid salts and carbonates, wherein the fatty
acid is overbased by the carbonate (hereinafter this will be
referred to as "carbonate-dispersed overbased fatty acid salt"),
and organic acid salts.
[0112] The carbonate-dispersed overbased fatty acid salt has a
carbonate dispersed in the fatty acid salt, with the fatty acid
salt being overbased by the carbonate.
[0113] The fatty acid salt in the carbonate-dispersed overbased
fatty acid salt may have a straight-chain or branched fatty acid.
The fatty acid may be saturated or unsaturated, but from the
viewpoint of solubility in the base oil it is preferably an
unsaturated fatty acid. There is no particular restriction on the
number of unsaturated bonds, but the preferred number is one. The
number of carbon atoms in the fatty acid is also not particularly
restricted, but C10-25 fatty acids are preferred from the viewpoint
of dispersibility of the carbonate fine particles.
[0114] As specific examples of preferred fatty acids to be used in
the carbonate-dispersed overbased fatty acid salt of the invention
there may be mentioned oleic acid (C18, one unsaturated bond),
erucic acid (C22, one unsaturated bond), linoleic acid (C18, two
unsaturated bonds) and linolenic acid (C18, three unsaturated
bonds), among which oleic acid is most preferred.
[0115] The fatty acid salt in the carbonate-dispersed overbased
fatty acid salt may be an alkali metal salt or alkaline earth metal
salt of any of the aforementioned fatty acids, but salts of
alkaline earth metals such as magnesium, barium and calcium are
preferred, with calcium being more preferred.
[0116] The carbonate in the carbonate-dispersed overbased fatty
acid salt may be an alkali metal carbonate or alkaline earth metal
carbonate, and specifically there may be mentioned carbonates of
lithium, sodium, potassium, magnesium, calcium and barium, although
carbonates of alkaline earth metals are preferred and calcium
carbonate is more preferred.
[0117] The carbonate is present as fine particles in the
carbonate-dispersed overbased fatty acid salt. There are no
particular restrictions on the mean particle size thereof, but from
the viewpoint of conferring sufficient performance for anti-flaking
and anti-seizure, the mean particle size is preferably at least 50
nm, more preferably at least 100 nm, even more preferably at least
300 nm, yet more preferably at least 500 nm, even yet more
preferably at least 1000 nm and most preferably at least 2000 nm.
Here, "mean particle size" refers to the mean particle size
calculated by the Marquadt method with measurement in a dynamic
light scattering particle distribution system.
[0118] There are no particular restrictions on the mixing ratio of
the fatty acid salt and carbonate in the carbonate-dispersed
overbased fatty acid salt of the invention, but from the viewpoint
of further improving the anti-flaking and anti-seizure, the
carbonate content is preferably at least 10 parts by mass, more
preferably at least 20 parts by mass, even more preferably at least
30 parts by mass, yet more preferably at least 40 parts by mass and
most preferably at least 50 parts by mass, with respect to 100
parts by mass of the fatty acid salt. From the standpoint of
solubility in the lubricating base oil, the carbonate content is
preferably not greater than 1000 parts by mass, more preferably not
greater than 500 parts by mass, even more preferably not greater
than 400 parts by mass, yet more preferably not greater than 300
parts by mass and most preferably not greater than 200 parts by
mass, with respect to 100 parts by mass of the fatty acid salt.
[0119] Any process may be used to produce the carbonate-dispersed
overbased fatty acid salt, and as a specific example, the fatty
acid salt may be dissolved in a carrier oil, and then carbon
dioxide gas blown in with a system containing an alkali metal base
or alkaline earth metal base. The carrier oil used here may be one
of those mentioned as the lubricating base oil for the grease
composition for constant velocity joints of the invention. As
alkali metal and alkaline earth metal bases there may be mentioned
hydroxides and oxides, and more specifically calcium hydroxide,
calcium oxide, magnesium oxide, barium oxide and the like.
[0120] The carbonate-dispersed overbased fatty acid salt used for
the invention is generally obtained as a solution in the carrier
oil, and from the viewpoint of solubility in the lubricating base
oil the carrier oil is preferably used in an amount of at least 10
parts by mass, more preferably at least 15 parts by mass, even more
preferably 20 parts by mass and most preferably 25 parts by mass
with respect to 100 parts by mass as the total of the fatty acid
salt and carbonate. Also, the carrier oil is preferably used at not
greater than 1000 parts by mass, more preferably not greater than
700 parts by mass, even more preferably not greater than 500 parts
by mass and most preferably not greater than 400 parts by mass with
respect to 100 parts by mass as the total of the fatty acid salt
and carbonate.
[0121] A methanol compound may be added to the reaction system
during production of the carbonate-dispersed overbased fatty acid
salt in order to promote production of carbonate fine
particles.
[0122] The carbonate-dispersed overbased fatty acid salt used for
the invention may also be an overbased mixture of a fatty acid salt
with another organic acid salt such as a sulfonate.
[0123] The content of the carbonate-dispersed overbased fatty acid
salt of the invention is preferably not less than 0.05% by mass and
more preferably not less than 0.1% by mass based on the total
composition. If the content of the carbonate-dispersed overbased
fatty acid salt is not at least 0.05% by mass, an insufficient
improving effect will tend to be obtained for the anti-flaking and
anti-seizure by addition of the carbonate-dispersed overbased fatty
acid salt. The content of the carbonate-dispersed overbased fatty
acid salt is preferably not greater than 10% by mass and more
preferably not greater than 5.0% by mass based on the total
composition. If the content of the carbonate-dispersed overbased
fatty acid salt exceeds 10% by mass, no fuirther effect of
improving the anti-flaking and anti-seizure will be achieved
corresponding to the increased content. Here, the content of the
carbonate-dispersed overbased fatty acid salt is the total of the
fatty acid salt content and the carbonate content, without the
carrier oil or other components.
[0124] The base number of the carbonate-dispersed overbased fatty
acid salt of the invention is not particularly restricted, but from
the standpoint of more excellent anti-flaking and anti-seizure, it
is usually at least 50 mgKOH/g, preferably at least 100 mgKOH/g,
more preferably at least 150 mgKOH/g, even more preferably at least
200 mgKOH/g and most preferably at least 250 mgKOH/g, when
dissolved in the carrier oil. There is no particular restriction on
the upper limit, but it will generally be not greater than 600
mgKOH/g. The base value referred to here is the base value
(mgKOH/g) determined by the hydrochloric acid method, based on JIS
K 2501 "Petroleum Products and Lubricants--Test Method for
Neutralization", Section 6.
[0125] As organic acid salts there are preferably used sulfonates,
phenates and salicylates, as well as mixtures thereof. As cation
components for these organic acid salts there may be mentioned
alkali metals such as sodium and potassium; alkaline earth metals
such as magnesium, calcium and barium; and amines such as ammonia,
alkylamines with C1-3 alkyl groups (monomethylamine, dimethylamine,
trimethylamine, monoethylamine, diethylamine, triethylamine,
monopropylamine, dipropylamine, tripropylamine and the like), and
alkanolamines with C1-3 alkanol groups (monomethanolamine,
dimethanolamine, trimethanolamine, monoethanolamine,
diethanolamine, triethanolamine, monopropanolamine,
dipropanolamine, tripropanolamine and the like). Preferred among
these are alkali metals and alkaline earth metals, among which
calcium is particularly preferred. Using an alkali metal or
alkaline earth metal as the cation component of the organic acid
salt will tend to produce even higher lubricity.
[0126] The base value of the organic acid salt is preferably 50-500
mgKOH/g and more preferably 100-450 mgKOH/g. If the base value of
the organic acid salt is less than 100 mgKOH/g the
lubricity-enhancing effect of the organic acid salt addition will
tend to be unsatisfactory, while organic acid salts with a base
value of greater than 500 mgKOH/g are also not preferred because
they are generally very difficult to produce and obtain. The base
value referred to here is the base value [mgKOH/g] determined by
the perchlorate method, with measurement according to JIS K 2501
"Petroleum Products and Lubricants--Determination of Neutralization
Number", Section 7.
[0127] The content of the organic acid salt is preferably 0.1-30%
by mass, more preferably 0.5-25% by mass and even more preferably
1-20% by mass based on the total amount of the composition. If the
organic acid salt content is less than this lower limit, the
improving effect on the anti-flaking and anti-seizure by addition
of the organic acid salt will tend to be inadequate, while if it
exceeds the upper limit, the stability of the grease composition
will be lowered and precipitates will tend to be produced.
[0128] The sulfonate used may be one produced by any desired
process. For example, there may be used an alkali metal salt,
alkaline earth metal salt or amine salt of an alkylaromatic
sulfonic acid compound obtained by sulfonation of an alkylaromatic
compound with a molecular weight of 100-1500 and preferably
200-700, or a mixture thereof. As the alkylaromatic sulfonic acid
compounds referred to here, there may be mentioned synthetic
sulfonic acids including sulfonated alkylaromatic compounds of
lubricating oil fractions of common mineral oils, petroleum
sulfonic acids such as "mahogany acid" yielded as a by-product of
white oil production, sulfonated products of alkylbenzenes with
straight-chain or branched alkyl groups, which are by-products in
production plants for alkylbenzenes used as starting materials for
detergents and are obtained by alkylation of benzene with
polyolefins, or sulfonated alkylnaphthalenes such as
dinonylnaphthalene. There may also be mentioned, specifically,
neutral sulfonates obtained by reacting the aforementioned
alkylaromatic sulfonic acid with an alkali metal salt (alkali metal
oxide, hydroxide or the like), an alkaline earth metal salt
(alkaline earth metal oxide, hydroxide or the like) or one of the
aforementioned amines (ammonia, alkylamine, alkanolamine, etc.);
basic sulfonates obtained by heating a neutral sulfonate with an
excess of an alkali metal base, alkaline earth metal base or amine
in the presence of water; "carbonated overbased sulfonates"
obtained by reacting a neutral sulfonate with an alkali metal base,
alkaline earth metal base or amine in the presence of carbon
dioxide gas; "borated overbased sulfonates" produced by reacting a
neutral sulfonate with an alkali metal base, alkaline earth metal
base or amine and a boric acid compound such as boric acid or boric
anhydride, or by reacting a carbonated overbased sulfonate with a
boric acid compound such as boric acid or boric anhydride; and
mixtures of these compounds.
[0129] As phenates there may be mentioned, specifically, neutral
phenates obtained by reacting an alkylphenol having one or two
C4-20 alkyl groups with an alkali metal salt (alkali metal oxide,
hydroxide or the like), an alkaline earth metal salt (alkaline
earth metal oxide, hydroxide or the like) or one of the
aforementioned amines (ammonia, alkylamine, alkanolamine, etc.) in
the presence or in the absence of elemental sulfur; basic phenates
obtained by heating a neutral phenate with an excess of an alkali
metal base, alkaline earth metal base or amine in the presence of
water; "carbonated overbased phenates" obtained by reacting a
neutral phenate with an alkali metal base, alkaline earth metal
base or amine in the presence of carbon dioxide gas; "borated
overbased phenates" produced by reacting a neutral phenate with an
alkali metal base, alkaline earth metal base or amine and a boric
acid compound such as boric acid or boric anhydride, or by reacting
a carbonated overbased phenate with a boric acid compound such as
boric acid or boric anhydride; and mixtures of these compounds.
[0130] As salicylates there may be mentioned, specifically, neutral
salicylates obtained by reacting an alkylsalicylic acid having one
or two C4-20 alkyl groups with an alkali metal salt (alkali metal
oxide, hydroxide or the like), an alkaline earth metal salt
(alkaline earth metal oxide, hydroxide or the like) or one of the
aforementioned amines (ammonia, alkylamine, alkanolamine, etc.) in
the presence or in the absence of elemental sulfur; basic
salicylates obtained by heating a neutral salicylate with an excess
of an alkali metal base, alkaline earth metal base or amine in the
presence of water; "carbonated overbased salicylates" obtained by
reacting a neutral salicylate with an alkali metal base, alkaline
earth metal base or amine in the presence of carbon dioxide gas;
"borated overbased salicylates" produced by reacting a neutral
salicylate with an alkali metal base, alkaline earth metal base or
amine and a boric acid compound such as boric acid or boric
anhydride, or by reacting a carbonated overbased salicylate with a
boric acid compound such as boric acid or boric anhydride; and
mixtures of these compounds.
[0131] The worked penetration of the grease composition for
constant velocity joints according to the invention is preferably
220 or greater and more preferably 265 or greater. If the worked
penetration is not at least 220, the grease will be excessively
hard and the effect of the invention may not be satisfactorily
exhibited. Also, the worked penetration is preferably not greater
than 430 and more preferably not greater than 400. If the worked
penetration exceeds 430, the grease will be excessively soft and it
may be difficult for the grease composition to fill constant
velocity joints. Here, "worked penetration" refers to the
penetration immediately after 60 working passes, as measured
according to JIS K2220, "Grease", Section 5.3 "Penetration Test
Method".
[0132] The grease composition for constant velocity joints of the
invention may also contain solid lubricants, antioxidants, oiliness
agents, rust preventing agents, viscosity index improvers and the
like, so long as the properties of the composition are not
impaired.
[0133] As specific examples of solid lubricants there may be
mentioned boron nitride, fluorinated graphite,
polytetrafluoroethylene, molybdenum disulfide, antimony sulfide,
alkali (earth) metal borates and the like.
[0134] As specific antioxidants there may be mentioned phenol-based
compounds such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol;
amine-based compounds such as dialkyldiphenylamine,
phenyl-.alpha.-naphthylamine and
p-alkylphenyl-.alpha.-naphthylamine; sulfur-based compounds;
phenothiazine-based compounds and the like.
[0135] As oiliness agents there may be mentioned, specifically,
amines such as lauryl amine, myristyl amine, palmityl amine,
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 lauryl amide, myristyl
amide, palmityl amide, stearyl amide and oleyl amide; and other
fats and oils.
[0136] As rust preventing agents there may be mentioned,
specifically, metal soaps; polyhydric alcohol partial esters such
as sorbitan fatty acid esters; amines; phosphoric acid; phosphoric
acid salts; and the like.
[0137] As viscosity index improvers there may be mentioned,
specifically, polymethacrylate, polyisobutylene, polystyrene and
the like.
[0138] For preparation of a grease composition for constant
velocity joints according to the invention, for example, a
lubricating base oil may be combined with a thickener, carbon black
having a mean particle size of not greater than 500 nm, an organic
molybdenum compound and if necessary other additives, and the
mixture stirred and passed through a roll mill or the like.
Alternatively, it may be produced by pre-adding the starting
component for a thickener to the lubricating base oil and melting
and stirring the mixture to prepare the thickener in the
lubricating base oil, and then adding the carbon black having a
mean particle size of not greater than 500 nm, the organic
molybdenum compound and if necessary other additives, stirring the
mixture and passing it through a roll mill or the like.
[0139] The grease composition for constant velocity joints of the
invention having the construction described above exhibits
excellent anti-flaking, anti-seizure, anti-wear and low-friction
properties, and can contribute to a high degree of increased
performance and extended life of constant velocity joints. There is
no restriction on the constant velocity joints to which the grease
composition for constant velocity joints of the invention is
applied, and for example, there may be mentioned fixed constant
velocity joints such as Barfield joints, Rzeppa joints and
undercutting free joints, and slide type constant velocity joints
such as double offset joints, tripod joints and cross groove
joints.
EXAMPLES
[0140] The present invention will now be explained in further
detail by examples and comparative examples, with the understanding
that the invention is in no way limited by the examples.
Examples 1-7 and Comparative Examples 1-4
[0141] For Examples 1-6 and Comparative Examples 1-4, a
solvent-refined paraffin-based mineral oil with a kinematic
viscosity of 126 mm.sup.2/s at 40.degree. C. was used as the
lubricating base oil, diphenylmethane-4,4'-diisocyanate was heated
to dissolution in the base oil, and the amine and alcohol listed in
Tables 1 to 3 were then heated to dissolution in the same base oil.
Next, the different additives listed in Table 1 were added to the
resulting gel-like substance, and after stirring the mixture it was
passed through a roll mill to obtain a grease composition.
[0142] In Example 7, lithium 12-hydroxystearate was added to the
lubricating base oil as the thickener instead of the diisocyanate,
alcohol and amine. Next, the different additives listed in Table 2
were added, and after stirring the mixture it was passed through a
roll mill to obtain a grease composition.
[0143] In Tables 1 to 3, the dihydrocarbyl polysulfide is
sulfurized polyisobutylene (sulfur content: 45% by mass), the
sulfurized oil is sulfurized lard (sulfur content: 30% by mass) and
the antioxidant is an amine-based antioxidant
(phenyl-.alpha.-naphthylamine).
[0144] [Bench Durability Test]
[0145] The grease compositions of Examples 1-7 and Comparative
Examples 1-3 were subjected to the following bench durability
test.
[0146] In consideration of the traveling pattern of an automobile,
a commercially available #82-size Birfield joint was used under
conditions where 1 cycle was a mode with modified rpm, torque and
operating angle, and the number of cycles until seizing of the
joint or flaking at sites was evaluated. The results are shown in
Tables 1 to 3. TABLE-US-00001 TABLE 1 Example 1 2 3 4 Lubricant
base oil [% by mass] 78.0 86.0 86.5 84.0 Thickener [% by mass] 16.0
8.0 8.0 8.0 Thickener Diphenylmethane 4,4'- 1 5 5 5 raw materials
diisocyanate (molar ratio) Cyclohexylamine 2 8 8 8 Octadecyl
alcohol -- 2 2 2 Carbon black (mean particle size: 40 nm) 2.0 1.0
-- 1.0 [% by mass] Carbon black (mean particle size: 100 nm) -- --
1.0 -- [% by mass] Molybdenum dithiocarbamate [% by mass] 2.0 1.0
2.0 2.0 Molybdenum dithiophosphate [% by mass] -- 3.0 -- --
Dihydrocarbyl polysulfide [% by mass] 1.0 -- 1.0 1.0 Sulfurized oil
[% by mass] -- -- -- -- Tricresyl phosphate [% by mass] -- -- 0.5
-- Zinc dithiophosphate [% by mass] -- -- -- 3.0 Overbased calcium
sulfonate [% by mass] -- -- -- -- Graphite [% by mass] -- -- -- --
Antioxidant [% by mass] 1.0 1.0 1.0 1.0 Worked penetration 280 330
320 330 Bench durability test [cycles] 450 400 500 500
[0147] TABLE-US-00002 TABLE 2 Example 5 6 7 Lubricant base oil [%
by mass] 85.5 87.0 84.5 Thickener [% by mass] 6.5 7.0 10.0
Thickener Diphenylmethane 4,4'- 5 5 Lithium 12- raw materials
diisocyanate hydroxy- (molar ratio) Cyclohexylamine 8 8 stearate
Octadecyl alcohol 2 2 Carbon black (mean particle size: 40 nm) 1.0
1.0 [% by mass] Carbon black (mean particle size: 100 nm) -- -- 1.0
[% by mass] Molybdenum dithiocarbamate [% by mass] 1.0 2.0 2.0
Molybdenum dithiophosphate [% by mass] 3.0 -- -- Dihydrocarbyl
polysulfide [% by mass] -- 1.0 1.0 Sulfurized oil [% by mass] 2.0
-- -- Tricresyl phosphate [% by mass] -- -- 0.5 Zinc
dithiophosphate [% by mass] -- -- -- Overbased calcium sulfonate [%
by mass] -- 1.0 -- Graphite [% by mass] -- -- -- Antioxidant [% by
mass] 1.0 1.0 1.0 Worked penetration 370 350 330 Bench durability
test [cycles] 450 600 300
[0148] TABLE-US-00003 TABLE 3 Comp. Ex. 1 2 3 4 Lubricant base oil
[% by mass] 80.0 90.0 89.5 84.0 Thickener [% by mass] 16.0 8.0 8.0
8.0 Thickener Diphenylmethane 4,4'- 1 5 5 5 raw materials
diisocyanate (molar ratio) Cyclohexylamine 2 8 8 8 Octadecyl
alcohol -- 2 2 2 Carbon black (mean particle size: 40 nm) -- 1.0 --
-- [% by mass] Carbon black (mean particle size: 100 nm) -- -- --
-- [% by mass] Molybdenum dithiocarbamate [% by mass] 2.0 -- -- 2.0
Molybdenum dithiophosphate [% by mass] -- -- -- -- Dihydrocarbyl
polysulfide [% by mass] 1.0 -- 1.0 1.0 Sulfurized oil [% by mass]
-- -- -- -- Tricresyl phosphate [% by mass] -- -- 0.5 -- Zinc
dithiophosphate [% by mass] -- -- -- 3.0 Overbased calcium
sulfonate [% by mass] -- -- -- -- Graphite (mean particle size: 3
.mu.m) -- -- -- 1.0 [% by mass] Antioxidant [% by mass] 1.0 1.0 1.0
1.0 Worked penetration 285 320 330 300 Bench durability test
[cycles] 60 20 60 100
Examples 8-11
[0149] For Examples 8 to 11, the solvent-refined paraffin-based
mineral oil and hydrogenation-refined naphthene-based mineral oil
listed in Table 4 were used together as the lubricating base oil,
diphenylmethane-4,4'-diisocyanate was heated to dissolution in the
base oil, and the amine and alcohol listed in Table 5 were then
heated to dissolution in the same base oil. Next, the different
additives listed in Table 5 were added to the resulting gel-like
substance, and after stirring each mixture it was passed through a
roll mill to obtain the grease compositions listed in Table 5.
TABLE-US-00004 TABLE 4 Solvent-refined Hydrogenation-refined
paraffin-based naphthene-based mineral oil mineral oil Kinematic
40.degree. C. 175 238 viscosity 100.degree. C. 16 12.4 [mm.sup.2/s]
Viscosity index 96 -41 Ring analysis % C.sub.A 7.36 13.9 % C.sub.N
26.22 45.9 % C.sub.P 66.42 40.2 Aniline point [.degree. C.] 113.4
81.5 Pour point [.degree. C.] -16 -15 Sulfur content [% by mass]
0.546 0 Nitrogen content [wt ppm] 104 60
In Table 5, the dihydrocarbyl polysulfide is sulfurized
polyisobutylene 5 (sulfur content: 45% by mass).
[0150] [Boot Material Immersion Test]
[0151] The grease compositions of Examples 8 to 11 were subjected
to the following boot material immersion test.
[0152] Following the procedure of JIS K 6258, a chloroprene-based
rubber material was immersed in the grease composition and held at
120.degree. C. for 500 hours, and the weight change of the rubber
material, volume change, tensile strength change and tensile
elongation change before and after immersion were determined. The
results are shown in Table 5.
[0153] [Bench durability test] The grease compositions of Examples
8 to 11 were subjected to the following bench durability test.
[0154] In consideration of the traveling pattern of an automobile,
a commercially available #95-size tripod joint was used under
conditions where 1 cycle was a mode with modified rpm, torque and
operating angle, and the time until seizing of the joint or flaking
at sites was evaluated. The results are shown in Table 5.
TABLE-US-00005 TABLE 5 Example 8 9 10 11 Solvent-refined
paraffin-based 76.0 66.5 58.0 76.0 mineral oil [% by mass]
Hydrogenation-refined naphthene- 10.0 20.0 30.0 10.0 based mineral
oil [% by mass] Thickener [% by mass] 8.0 8.0 8.0 8.0 Thickener
Diphenylmethane 5 5 5 5 raw materials 4,4'-diisocyanate (molar
ratio) Cyclohexylamine 8 8 8 8 Octadecyl alcohol 2 2 2 2 Carbon
black (mean particle size: 0.5 1.0 1.0 2.0 40 nm)[% by mass]
Molybdenum dithiocarbamate 3.0 3.0 3.0 3.0 [% by mass] Molybdenum
dithiophosphate -- -- 1.0 1.0 [% by mass] Tricresyl phosphate [% by
mass] 0.5 0.5 -- 0.5 Dihydrocarbyl polysulfide 2.0 1.0 -- 1.0 [% by
mass] Boot material Strength change -7 -1 -4 -16 immersion test [%]
Elongation change -15 -10 -12 -18 [%] Bench durability test
[cycles] 900 1000 1000 1100
* * * * *