U.S. patent application number 15/556713 was filed with the patent office on 2018-03-01 for grease composition.
This patent application is currently assigned to JXTG NIPPON OIL & ENERGY CORPORATION. The applicant listed for this patent is JXTG NIPPON OIL & ENERGY CORPORATION. Invention is credited to Yusuke AYAME, Kazumi SAKAI, Hisayuki WADA.
Application Number | 20180057768 15/556713 |
Document ID | / |
Family ID | 56879607 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180057768 |
Kind Code |
A1 |
SAKAI; Kazumi ; et
al. |
March 1, 2018 |
GREASE COMPOSITION
Abstract
Provided herein is a grease composition capable of reducing an
amount of wear in sliding parts of various members of automobiles,
electrical devices, and the like. The grease composition includes a
lubricant base oil, a thickener, an amide compound, and at least
one of an .alpha.-hydroxycarboxylic acid metal salt, and an
.omega.-hydroxycarboxylic acid metal salt. The hydroxycarboxylic
acid metal salts are contained in a total content of 0.1 to 2 mass
% with respect to the total amount of the grease composition.
Inventors: |
SAKAI; Kazumi; (Tokyo,
JP) ; WADA; Hisayuki; (Tokyo, JP) ; AYAME;
Yusuke; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JXTG NIPPON OIL & ENERGY CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
JXTG NIPPON OIL & ENERGY
CORPORATION
Tokyo
JP
|
Family ID: |
56879607 |
Appl. No.: |
15/556713 |
Filed: |
March 9, 2016 |
PCT Filed: |
March 9, 2016 |
PCT NO: |
PCT/JP2016/057275 |
371 Date: |
September 8, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 169/06 20130101;
C10M 129/44 20130101; C10M 2215/1026 20130101; C10M 2207/2835
20130101; C10M 2215/08 20130101; C10M 133/16 20130101; C10N 2050/10
20130101; C10M 2207/1285 20130101; C10M 2215/221 20130101; C10N
2030/06 20130101; C10N 2040/02 20130101; C10M 2207/1206 20130101;
C10N 2010/04 20130101; C10M 2205/0285 20130101; C10M 2207/128
20130101; C10M 169/00 20130101; C10M 2207/1236 20130101; C10M
2201/061 20130101; C10M 2207/1236 20130101; C10M 2207/1285
20130101 |
International
Class: |
C10M 169/00 20060101
C10M169/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2015 |
JP |
2015-046213 |
Claims
1. A grease composition comprising: a lubricant base oil; a
thickener; an amide compound; and at least one of an
.alpha.-hydroxycarboxylic acid metal salt, and an
.omega.-hydroxycarboxylic acid metal salt, wherein the
hydroxycarboxylic acid metal salts are contained in a total content
of 0.1 to 2 mass % with respect to a total amount of the grease
composition.
2. The grease composition according to claim 1, wherein the
hydroxycarboxylic acid metal salt is an alkali metal salt, or an
alkali earth metal salt.
3. The grease composition according to claim 2, wherein the
hydroxycarboxylic acid metal salt is a calcium salt, or a barium
salt.
4. The grease composition according to claim 1, wherein the
hydroxycarboxylic acid is a monovalent hydroxycarboxylic acid of 8
to 24 carbon atoms.
5. The grease composition according to claim 1, wherein the
thickener contains at least one of a urea-based thickener, and a
metal soap-based thickener.
6. The grease composition according to claim 1, which further
comprises a solid lubricant component.
7. A lubrication method comprising using the grease composition of
claim 1 at a sliding part.
Description
TECHNICAL FIELD
[0001] The present invention relates to a grease composition
capable of reducing an amount of wear in sliding parts.
BACKGROUND ART
[0002] Grease has been mainly used for slide bearings and rolling
bearings (bearings), or for sliding surfaces where a lubricant film
cannot easily remain attached because of moving contact surfaces.
Typically, grease is prepared by mixing a thickener, and, as
required, additives, to a lubricant base oil.
[0003] With the advancement in machine technology such as in
automobiles and electrical devices, these devices are used in
increasing severe operating conditions the trend or downsizing and
lighting, higher output, and longer life continues to grow. This
has increased the demand for higher performance, for example,
lubricity, in greases used for these devices.
[0004] Various options are proposed for the base oil, thickener,
and additives to improve grease lubricity. For example, it has been
proposed to add an amide compound and a solid lubricant to improve
grease lubricity, for example, such as abrasion resistance (see PTL
1, and PTL 2). However, a grease having better lubricity is
needed.
[0005] Hydroxyfatty acid metal salts are used as a thickener for
grease (see, for example, PTL 3). However, the hydroxyfatty acid
metal salts used as a thickener are mostly lithium
12-hydroxystearate, and an .alpha.- or .omega.-hydroxyfatty acid
metal salt is not used. It is also known that use of this type of
compound as an grease additive results in a shorter life, though it
improves antirust performance (for example, PTL 4).
CITATION LIST
Patent Literature
PTL 1: JP-A-2013-181154
PTL 2: JP-A-2013-181156
PTL 3: WO2012/141222
PTL 4: JP-B-7-000796
SUMMARY OF INVENTION
Technical Problem
[0006] The present invention was made under these circumstances,
and it is an object of the present invention to provide a grease
composition that is capable of reducing an amount of wear in
sliding parts of various members of automobiles, electrical
devices, and the like.
Solution to Problem
[0007] The present inventors diligently worked to achieve the
foregoing object, and found that an amount of wear can be greatly
reduced by the synergy between metal salts of specific
hydroxycarboxylic acids and an amide compound. The present
invention was completed on the basis of this finding, and includes
the following.
[0008] (1) A grease composition comprising:
[0009] a lubricant base oil;
[0010] a thickener;
[0011] an amide compound; and
[0012] at least one of an .alpha.-hydroxycarboxylic acid metal
salt, and an .omega.-hydroxycarboxylic acid metal salt,
[0013] wherein the hydroxycarboxylic acid metal salts are contained
in a total content of 0.1 to 2 mass % with respect to a total
amount of the grease composition.
[0014] (2) The grease composition according to item (1), wherein
the hydroxycarboxylic acid metal salt is an alkali metal salt, or
an alkali earth metal salt.
[0015] (3) The grease composition according to item (2), wherein
the hydroxycarboxylic acid metal salt is a calcium salt, or a
barium salt.
[0016] (4) The grease composition according to any one of items (1)
to (3), wherein the hydroxycarboxylic acid is a monovalent
hydroxycarboxylic acid of 8 to 24 carbon atoms.
[0017] (5) The grease composition according to any one of items (1)
to (4), wherein the thickener contains at least one of a urea-based
thickener, and a metal soap-based thickener.
[0018] (6) The grease composition according to any one of items (1)
to (5), which further comprises a solid lubricant component.
[0019] (7) A lubrication method comprising using the grease
composition of any one of items (1) to (6) at a sliding part.
Advantageous Effects of Invention
[0020] The grease composition of the present s highly effective at
greatly reducing wear in sliding parts of various members of
automobiles, electrical devices, and the like.
DESCRIPTION OF EMBODIMENTS
Lubricant Base Oil
[0021] A lubricant base oil of the present invention may be a
mineral or a synthetic lubricant base oil, as long as it is a
lubricant base oil commonly used for grease. The lubricant base oil
has a kinetic viscosity at 40.degree. C. of preferably 1 to 500
mm.sup.2/s, more preferably 5 to 100 mm.sup.2/s. A grease
composition having desirable consistency can be prepared with ease
when the kinetic viscosity at 40.degree. C. is 1 to 500 mm.sup.2/s.
In order to prepare a grease having excellent lubricity, it is
preferable to use a lubricant base oil of physical properties with
a viscosity index of 90 or more, particularly 95 to 250, a pour
point of -10.degree. C. or less, particularly -15 to -70.degree.
C., and a flash point of 150.degree. C. or more.
[0022] When containing a solid lubricant, the lubricant base oil
preferably has a density of 0.75 to 0.95 g/cm.sup.3 at a lubricant
base oil temperature of 15.degree. C. The density is particularly
preferably 0.8 to 0.9 g/cm.sup.3.
[0023] The mineral lubricant base oil may be a lubricant oil
fraction obtained through purification of a nil by various
purification processes after distillation of a crude oil under
ordinary pressure or under ordinary pressure and reduced pressure.
The purification processes include, for example, hydrorefining,
solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid
washing, and clay treatment. The base oil of the present invention
can be obtained from a combination of these processes performed in
appropriate order. A mixture of different refined oils of different
qualities obtained by treating different crude oils or different
distillate oils with a combination of different processes in
different order is also useful. Regardless of the method, the base
oil can be desirably used when the base oil quality is adjusted to
satisfy the foregoing density.
[0024] The synthetic lubricant base oil uses preferably a base
material having desirable hydrolytic stability. Examples of such
base materials include polyolefins such as poly-.alpha.-olefins,
polybutene, and a copolymer of two or more olefins; polyesters,
polyalkylene glycols, alkylbenzenes, and alkylnaphthalenes.
Poly-.alpha.-olefins are preferred for availability, cost,
viscosity characteristics, oxidation stability, and compatibility
with system components. Further preferred for cost are
poly-.alpha.-olefins made by polymerizing olefins such as
1-dodecene, and 1-decene.
[0025] Also preferred as the synthetic lubricant base oil are
ester-based base oils, for example, such as a polyolester of a
polyalcohol and a monovalent carboxylic acid, and a diester of a
divalent carboxylic acid and an alcohol. Preferred are polyolesters
obtained from a polyalcohol selected from neopentyl glycol,
trimethylolpropane, and pentaerythritol, and a fatty acid of 4 to
22 carbon atoms. The fatty acid is particularly preferably a fatty
acid of 12 to 20 carbon atoms, particularly an unsaturated fatty
acid.
[0026] The lubricant base oil may use base oils other than the
poly-.alpha.-olefinic base oil and the ester-based base oil. It is,
however, preferable to contain 80 mass % or more, particularly 90
mass % or more of the poly-.alpha.-olefin or ester-based base oil
with respect to the mass of the lubricant base oil.
[0027] The synthetic lubricant base oil may be used alone or as a
mixture of two or more. It is also possible to use the synthetic
lubricant base oil as a mixture with the mineral base oil.
[0028] The content of the lubricant base oil is preferably 50 to 95
mass %, particularly preferably 60 to 85 mass % with respect to the
total amount of the grease composition. A grease composition having
desirable consistency can be prepared with ease when the lubricant
base oil content is 50 to 95 mass %.
Thickener
[0029] A thickener commonly used for grease may be used as the
thickener of the present invention without causing trouble. It is,
however, preferable to use a metal soap-based thickener, or a
urea-based thickener. The thickener may be used alone or as a
mixture of two or more. The thickener may be contained in any
amount, as long as the desired consistency is obtained. For
example, the thickener content is preferably 2 to 30 mass %,
further preferably 5 to 20 mass % with respect to the total amount
of the grease composition.
[0030] The metal soap-based thickener is a thickener of a
carboxylic acid metal salt. The carboxylic acid may be a derivative
of carboxylic acids having a hydroxy group.
[0031] The carboxylic acids may be aliphatic carboxylic acids such
as stearic acid, and azelaic acid, or aromatic carboxylic acids
such as terephthalic acid. Monovalent or divalent aliphatic
carboxylic acids, particularly aliphatic carboxylic acids of 6 to
20 carbon atoms are used. Particularly preferred for use are
monovalent aliphatic carboxylic acids of 12 to 20 carbon atoms, and
divalent aliphatic carboxylic acids of 6 to 14 carbon atoms.
Monovalent aliphatic carboxylic acids having one hydroxyl group are
preferred.
[0032] The metal may be an alkali metal such as lithium and sodium,
an alkali earth metal such as calcium, or an amphoteric metal such
as aluminum. Preferred are alkali metals, particularly lithium.
[0033] Metal salts of .alpha.- or .omega.-hydroxyfatty acids are
not preferred as thickener because of poor thickening
capability.
[0034] The thickener may be added in the form of a metal soap, or
as a metal-soap thickener by separately adding the carboxylic acid
and a metal source (e.g., a metal salt, a metal salt hydroxide),
and causing these to react at the time of grease production.
[0035] The carboxylic acid metal salt may be used alone or as a
mixture of two or more. For example, a mixture of lithium
12-hydroxystearate and lithium azelate is particularly
preferred.
[0036] The urea-based thickener may be, for example, a diurea
compound obtained by a reaction of a diisocyanate and a monoamine,
or a polyurea compound obtained by a reaction of a diisocyanate
with a monoamine or a diamine.
[0037] Diisocyanates are compounds in which two of the hydrogen
atoms of the hydrocarbon are substituted with isocyanate groups.
Preferred examples of the diisocyanates include phenylene
diisocyanate, tolylene diisocyanate, diphenyl diisocyanate,
diphenylmethane diisocyanate, octadecane diisocyanate, decane
diisocyanate, and hexane diisocyanate. The hydrocarbon may be a
non-cyclic hydrocarbon or a cyclic hydrocarbon, or an aromatic
hydrocarbon, an alicyclic hydrocarbon, or an aliphatic hydrocarbon.
Preferably, the hydrocarbon is an aromatic hydrocarbon. The
hydrocarbon has preferably 4 to 20 carbon atoms, particularly 8 to
18 carbon atoms.
[0038] Monoamines are compounds in which one of the hydrogen atoms
of the ammonia is substituted with a hydrocarbon group. Preferred
examples of the monoamines include octylamine, dodecylamine,
hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine, and
cyclohexylamine. Diamines are compounds in which two of the
hydrogen atoms of the ammonia are substituted with hydrocarbon
groups. Preferred examples of the diamines include ethylenediamine,
propanediamine, butanediamine, hexanediamine, octanediamine,
phenylenediamine, tolylenediamine, xylenediamine, and
diaminodiphenylmethane. The hydrocarbon groups of the monoamines
and diamines may be non-cyclic hydrocarbon groups or cyclic
hydrocarbon groups, or aromatic hydrocarbon groups, alicyclic
hydrocarbon groups, or aliphatic hydrocarbon groups. Preferably,
the monoamines and diamines contain aliphatic hydrocarbon groups.
The monoamines and diamines have preferably 2 to 20 carbon atoms,
particularly preferably 4 to 18 carbon atoms.
Hydroxycarboxylic Acid Metal Salt
[0039] The present invention contains at least one of an
.alpha.-hydroxycarboxylic acid metal salt, and an
.omega.-hydroxycarboxylic acid metal salt. It is preferable to
contain both an .alpha.-hydroxycarboxylic acid metal salt, and an
.omega.-hydroxycarboxylic acid metal salt, though only one of these
may be contained. The metallic element forming the salt is
preferably an alkali metal or an alkali earth metal, particularly
preferably calcium or barium. The total content of the
hydroxycarboxylic acid metal salts is 0.1 to 2 mass %, preferably
0.2 to 1 mass % with respect to the total amount of the grease
composition. The wear reducing effect will not be obtained when the
total content of the hydroxycarboxylic acid metal salts is less
than 0.1 mass %, whereas the hydroxycarboxylic acid metal salt may
inhibit the effects of other components when the content is above 2
mass %.
[0040] In the present invention, the .alpha.- and
.omega.-hydroxycarboxylic acids are preferably monovalent, more
preferably monovalent acids of 8 to 24 carbon atoms. The monovalent
.alpha.-hydroxycarboxylic acid is represented by
R.sup.1--CH(--OH)--COOH, and the .omega.-hydroxycarboxylic acid is
represented by HO--CH.sub.2--R.sup.2--COOH. In the present
invention, R.sup.1 is preferably an alkyl group of 1 to 38 carbon
atoms, or an alkenyl group of 2 to 38 carbon atoms, more preferably
an alkyl group of 6 to 22 carbon atoms, or an alkenyl group of 6 to
22 carbon atoms. R.sup.2 is preferably an alkylene group of 1 to 38
carbon atoms, or an alkenylene group of 2 to 38 carbon atoms, more
preferably an alkylene group of 6 to 22 carbon atoms, or an
alkenylene group of 6 to 22 carbon atoms.
[0041] Preferably, the present invention further contains metal
salts of hydroxycarboxylic acids other than .alpha.- and
.omega.-hydroxycarboxylic acids, or metal salts of carboxylic acids
containing no hydroxyl group. Preferred examples of such carboxylic
acid metal salts include alkali metal salts or alkali earth metals,
preferably calcium or barium salts of .alpha.- and
.omega.-hydroxycarboxylic acids in which the hydroxyl group is
substituted at different positions from the foregoing .alpha.- and
.omega.-hydroxycarboxylic acids, or in which two or more hydroxyl
groups are substituted, and alkali metal salts or alkali earth
metals, preferably calcium or barium salts of carboxylic acids that
do not have a substitution of the hydroxyl group.
[0042] The hydroxycarboxylic acids, and the carboxylic acids may be
obtained by chemical synthesis. It is, however, preferable to use a
lanolin fatty acid--an acid obtained through purification (e.g.,
hydrolysis) of a wax-like substance adhering to sheep hairs--as a
raw material these acids. When using a lanolin fatty acid as a raw
material, the .alpha.- and .omega.-hydroxycarboxylic acids, and
other preferred carboxylic acids may be separately used. It is,
however, preferable to prepare the lanolin fatty acid directly into
a metal salt, without separating these acids.
Amide Compound
[0043] The present invention further contains an amide compound.
The amide compound, which is a compound having at least one amide
group (--NH--CO--), may be a compound containing one amide group
(monoamide), or a compound containing two amide groups (bisamide).
Preferably, saturated aliphatic monoamides, or saturated aliphatic
bisamides are used.
[0044] The saturated aliphatic bisamides are most preferred for
their advantages including desirable heat resistance, and the
ability to reduce the frictional resistance at a sliding part even
with a relatively small amount.
[0045] The saturated aliphatic monoamides are amide compounds of a
saturated aliphatic monoamine and a saturated aliphatic
monocarboxylic acid. The saturated aliphatic bisamides may be amide
compounds of a saturated aliphatic diamine and a saturated
aliphatic monocarboxylic acid, or amide compounds of a saturated
aliphatic dicarboxylic acid and a saturated aliphatic
monoamine.
[0046] A preferred saturated aliphatic amide compound has a melting
point of 100 to 170.degree. C., and a molecular weight of 298 to
876.
[0047] The saturated aliphatic monoamides are represented by the
following general formula (1). The saturated aliphatic bisamides
are represented by the following general formulae (2) and (3).
R.sup.11--CO--NH--R.sup.12 (1)
R.sup.13--CO--NH-A.sup.1-NH--CO--R.sup.14 (2)
R.sup.15--NH--CO-A.sup.2-CO--NH--R.sup.16 (3)
[0048] In the formulae, R.sup.11, R.sup.12, R.sup.13, R.sup.14,
R.sup.15, and R.sup.16 each independently represent a saturated
aliphatic hydrocarbon group of 5 to 25 carbon atoms. In general
formula (1), R.sup.12 may be hydrogen. A.sup.1 and A.sup.2
represent divalent saturated aliphatic hydrocarbon groups of 1 to
10 carbon atoms, and are preferably divalent saturated chain
hydrocarbon groups of 1 to 4 carbon atoms.
[0049] Specifically, preferred examples of the saturated aliphatic
monoamides include lauramide, palmitamide, stearamide, and
behenamide.
[0050] Preferred examples of the saturated aliphatic bisamides
represented by formula (2) include ethylene bis(stearamide),
ethylene bis(isostearamide), ethylene bis(lauramide), and methylene
bis(lauramide). Preferred examples of the saturated aliphatic
bisamides represented by formula (3) include
N,N'-bisstearylsebacamide.
[0051] The bisamides are preferably amide compounds in which
R.sup.13, R.sup.14, R.sup.15, and R.sup.16 in formulae (2) and (3)
are each independently a saturated chain hydrocarbon group of 12 to
20 carbon atoms.
[0052] The amide compounds may be used alone or in a combination of
two or more in any proportions. The content of the amide compound
is preferably 1 to 30 mass %, more preferably 5 to 20 mass % with
respect to the total amount of the grease composition.
[0053] It is to be noted here that the amide compound, when
thermofused in the presence of the lubricant base oil, produces a
state in which the lubricant base oil is held in the amide compound
forming a three-dimensional network structure. This further lowers
the coefficient of friction at a sliding part than when the amide
compound is simply dispersed or mixed in the grease.
Solid Lubricant Component
[0054] Preferably, the present invention further contains a solid
lubricant component.
[0055] The solid lubricant component may be, for example, melamine
cyanurate, molybdenum disulfide, boron nitride, graphite, mica,
fluororesin, fluorinated graphite, or a molybdenum organic compound
commonly used for lubricants. The content of the solid lubricant
component is preferably 0.1 to 10 mass %, more preferably 0.2 to 5
mass % with respect to the total amount of the grease
composition.
[0056] In the present invention, it is more preferable to use boron
nitride or melamine cyanurate as the solid lubricant component.
Particularly preferably, a hexagonal, atmospheric-phase boron
nitride (h-BN) powder of a particle size suited for the intended
purpose may be appropriately selected and used. The solid lubricant
component has a particle diameter of preferably 1 to 10 .mu.m.
Other Additives
[0057] Additives commonly used for lubricant oils and greases may
be appropriately added, as required, to the grease composition of
the present invention, in addition to the foregoing components.
Examples of such additives include cleaners, dispersants, antiwear
agents, viscosity index improvers, antioxidants, extreme-pressure
agents, anti-rusting agents, and corrosion inhibitors.
Subject of Lubrication
[0058] The grease composition of the present invention is
preferably used at sliding parts, preferably for lubrication of
various sliding members, for example, between metal parts, metal
and resin parts, and resin parts.
[0059] The sliding member resin may be a natural resin or a
synthetic resin. Preferred as synthetic resins are general-purpose
plastics (e.g., polyethylene, polystyrene, polypropylene, and
polyvinyl chloride), and engineering plastics. Engineering plastics
are particularly preferred in terms of heat resistance, and
mechanical strength. Examples of synthetic resins include polyamide
resins, polyacetal resins, polycarbonate resins, polysulfone
resins, polyphenylene sulfide resins, polyamideimide resins,
polyetheretherketone resins, phenolic resins, polyester resins, and
epoxy resins. The grease composition is particularly preferred for
lubrication of polyamide resins, and polyoxymethylene resins.
[0060] Examples of the applicable areas of the grease composition
of the present invention include transport machinery such as
automobiles, railway, and aircraft; industrial machines such as
machine tools; home electrical appliances such as washing machines,
refrigerators, and vacuum cleaners; and precision machines such as
watches and cameras. The grease composition has use for, for
example, bearings, gears, sliding surfaces, belts, joints, and cams
used for these machines. The grease composition is particularly
useful for improving the abrasion resistance of gears (e.g., spur
wheels, helical gears, crossed helical gears, hypoid gears, worm
gears, and wheel gears) exposed to a high-surface-pressure sliding
environment.
EXAMPLES
[0061] The present invention is described below using Examples
representing implementations of the present invention. The present
invention, however, is not limited to the following
implementations.
Preparation Method
[0062] Each component was put in a container in the amounts (mass
%) shown in Tables 1 and 2, and heated to 150.degree. C. (a
temperature equal to or greater than the melting point of the amide
compound). The mixture was then stirred with a magnetic stirrer,
and cooled to room temperature. The product was subjected to a
dispersion process under applied pressure using rollers (three
rolls) to prepare a grease composition.
[0063] The components used are as follows.
1. Lubricant Base Oil:
[0064] (1) Poly-.alpha.-Olefin (Durasyn 170 Available from
INEOS)
[0065] Kinetic viscosity at 40.degree. C.: 68 mm.sup.2/s
[0066] Density at 15.degree. C.: 0.83 g/cm.sup.3
[0067] Viscosity index: 133
[0068] Pour point: -45.degree. C.
[0069] Flash point: 250.degree. C.
(2) Polyolester (an Ester of Trimethylolpropane and an Oleic Acid
of 18 Carbon Atoms)
[0070] Kinetic viscosity at 40.degree. C.: 46 mm.sup.2/s
[0071] Density at 15.degree. C.: 0.92 g/cm.sup.3
[0072] Viscosity index: 146
[0073] Pour point: -32.5.degree. C.
[0074] Flash point: 310.degree. C.
2. Thickener:
(1) Urea-Based Thickener
[0075] Alicyclic diurea of cyclohexylamine and methylene diphenyl
diisocyanate
(2) Lithium-Based Thickener
[0076] A lithium salt of a mixed acid of 12-hydroxystearic acid and
azelaic acid
3. Solid Lubricant Component:
(1) Boron Nitride
[0077] Hexagonal boron nitride having an average particle size of 2
.mu.m as measured by laser diffractometry
(2) Melamine Cyanurate (MCA)
[0078] Melamine cyanurate having an average particle size of 1
.mu.m as measured by laser diffractometry
4. Amide Compound:
(1) Ethylene Bis(Stearamide) (Guaranteed Reagent)
(2) Ethylene Bis(Lauramide) (Guaranteed Reagent)
5. Carboxylic Acid Metal Salt
(1) Barium Lanolate
[0079] Content of .alpha.-hydroxycarboxylate: 30 mass %
[0080] Content of .omega.-hydroxycarboxylate: 5 mass %
[0081] Content of hydroxycarboxylates other than .alpha.- and
.omega.-hydroxycarboxylates: 1 mass %
[0082] Content of carboxylate having no hydroxyl group: 40 mass
%
[0083] Number of carbon atoms in hydroxycarboxylic acid: 8 to
24
[0084] Number of carbon atoms in carboxylic acid having no hydroxyl
group: 8 to 24
(2) Calcium Lanolate
[0085] Content of .alpha.-hydroxycarboxylate: 30 mass %
[0086] Content of .omega.-hydroxycarboxylate: 5 mass %
[0087] Content of hydroxycarboxylates other than .alpha.- and
.omega.-hydroxycarboxylates: 1 mass %
[0088] Content of carboxylate having no hydroxyl group: 40 mass
%
[0089] Number of carbon atoms in hydroxycarboxylic acid: 8 to
24
[0090] Number of carbon atoms in carboxylic acid having no hydroxyl
group: 8 to 24
Evaluation of Amount of Wear
[0091] Evaluation was made according to the ASTM D 3233 test method
for measurement of load bearing properties of lubricant oil, using
a Falex friction tester. In this test, a resin (polyamide resin
(PA66)) pin was held between two steel (SUJ-2) V blocks, and a
sample was charged into a sample container. A 55-MPa load was
applied with the rotational axis held stationary, and the lubricant
oil was tested for load bearing properties at an oil temperature of
120.degree. C. under a rotation speed of 360 rpm. The amount of
wear was measured by measuring the reduction of the pin weight
after 10 minutes. The results are presented in Tables 1 and 2.
Evaluation Result
[0092] The amount of wear was considerably smaller in the grease
compositions of Examples that contained at least one of the
.alpha.-hydroxycarboxylic acid metal salt and the
co-hydroxycarboxylic acid metal salt with the thickener and the
amide compound. On the other hand, there was no large reduction in
the amount of wear when the hydroxycarboxylic acid metal salts were
not contained, even when simple carboxylates, or a phosphite ester
(a known antiwear agent) were added (Comparative Examples 1 to
7).
TABLE-US-00001 TABLE 1 Compar- Compar- Compar- Compar- Compar-
Compar- Exam- Exam- Exam- Exam- ative ative ative ative ative ative
ple 1 ple 2 ple 3 ple 4 Example 1 Example 2 Example 3 Example 4
Example 5 Example 6 Lubricant base oil Poly-.alpha.-olefin Balance
Balance Balance Balance Balance Balance Balance Balance Balance
Balance Thickener Urea-based 10 10 10 10 10 10 10 10 10 10
thickener Amide compound Ethylene bis- 15 15 15 15 15 15 15 15 15
15 stearylamide Solid lubricants Boron nitride 1.0 1.0 1.0 -- 1.0
1.0 1.0 1.0 1.0 1.0 Carboxylic acid Barium lanolate 1.0 2.0 -- 2.0
-- -- -- -- -- -- metal salt Calcium lanolate -- -- 1.0 -- -- -- --
-- -- -- Content of .alpha.-hydroxycarboxylic acid 0.35 0.70 0.35
0.70 -- -- -- -- -- -- metal salt and .omega.-hydroxycarboxylic
acid metal salt Other additive Oleylamide -- -- -- -- -- 1.0 -- --
-- -- compounds Aluminum stearate -- -- -- -- -- -- 1.0 -- -- --
Zinc naphthenate -- -- -- -- -- -- -- 1.0 -- -- Phosphite ester --
-- -- -- -- -- -- -- 1.0 -- Phosphate -- -- -- -- -- -- -- -- --
1.0 Evaluation results Worked penetration 324 308 321 330 315 293
306 316 330 328 Amount of wear 0.5 0.6 0.8 0.8 1.3 0.9 1.0 1.0 0.9
1.2 (mg)
TABLE-US-00002 TABLE 2 Comparative Example 5 Example 6 Example 7
Example 8 Example 9 Example 10 Example 7 Lubricant base oil
Poly-.alpha.-olefin Balance Balance Balance Balance -- Balance
Balance Polyolester -- -- -- -- Balance -- -- Thickener
Litium-based 10 10 10 10 10 10 10 thickener Amide compound Ethylene
bis- 15 15 -- 15 15 15 -- stearylamide Ethylene bis- -- -- 15 -- --
-- -- laurylamide Solid lubricants Boron nitride -- 2.0 2.0 -- 2.0
2.0 -- MCA -- -- -- 2.0 -- -- -- Carboxylic acid metal Barium
lanolate 1.0 1.0 1.0 1.0 1.0 -- -- salt Calcium lanolate -- -- --
-- -- 1.0 -- Content of .alpha.-hydroxycarboxylic acid 0.35 0.35
0.35 0.35 0.35 0.35 -- metal salt and .omega.-hydroxycarboxylic
acid metal salt Evaluation results Worked penetration 320 280 300
274 298 280 300 Amount of wear 1.2 0.8 1.0 1.0 1.0 1.0 1.6 (mg)
INDUSTRIAL APPLICABILITY
[0093] The grease composition of the present invention can greatly
reduce an amount of wear in sliding members, and is useful for
lubrication of sliding parts of various members of automobiles,
electrical devices, and the like.
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