U.S. patent application number 14/382851 was filed with the patent office on 2015-01-22 for grease composition.
The applicant listed for this patent is JX NIPPON OIL & ENERGY CORPORATION. Invention is credited to Yusuke Ayame, Kazumi Sakai, Yuji Shitara.
Application Number | 20150024981 14/382851 |
Document ID | / |
Family ID | 49116629 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150024981 |
Kind Code |
A1 |
Ayame; Yusuke ; et
al. |
January 22, 2015 |
GREASE COMPOSITION
Abstract
Provided is a grease composition that has high lubricity,
particularly excellent wear resistance, and shows only a small
extent of deterioration in wear resistance with long-term use under
high temperatures. The grease composition comprises at least one
base oil selected from a mineral oil-based lubricant base oil and a
synthetic lubricant base oil, an amide compound, a solid lubricant,
and a urea-based thickener, wherein the amide compound is heated
and melted at least once with the base oil.
Inventors: |
Ayame; Yusuke; (Kanagawa,
JP) ; Sakai; Kazumi; (Kanagawa, JP) ; Shitara;
Yuji; (Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JX NIPPON OIL & ENERGY CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
49116629 |
Appl. No.: |
14/382851 |
Filed: |
March 1, 2013 |
PCT Filed: |
March 1, 2013 |
PCT NO: |
PCT/JP2013/055624 |
371 Date: |
September 4, 2014 |
Current U.S.
Class: |
508/155 ;
508/181; 508/258 |
Current CPC
Class: |
C10N 2050/10 20130101;
C10M 169/00 20130101; C10N 2020/02 20130101; C10N 2020/06 20130101;
C10M 2213/062 20130101; C10M 2215/222 20130101; C10M 2215/1026
20130101; C10M 169/06 20130101; C10N 2020/017 20200501; C10M
2215/221 20130101; C10N 2040/04 20130101; C10N 2040/02 20130101;
C10M 2201/061 20130101; C10N 2020/011 20200501; C10N 2070/00
20130101; C10M 2203/1006 20130101; C10M 2205/0285 20130101; C10M
2215/064 20130101; C10N 2040/046 20200501; C10N 2030/06 20130101;
C10M 2215/0813 20130101 |
Class at
Publication: |
508/155 ;
508/258; 508/181 |
International
Class: |
C10M 169/06 20060101
C10M169/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 5, 2012 |
JP |
2012-047750 |
Claims
1. A grease composition comprising at least one base oil selected
from a mineral oil-based lubricant base oil and a synthetic
lubricant base oil, an amide compound, a solid lubricant, and a
urea-based thickener, wherein the amide compound is heated and
melted at least once together with the base oil.
2. The grease composition according to claim 1, wherein the mineral
oil-based lubricant base oil and the synthetic lubricant base oil
have a kinematic viscosity of 1 to 1000 mm.sup.2/s at 40.degree.
C.
3. The grease composition according to claim 1, wherein the amide
compound includes an alkyl group having 6 to 24 carbon atoms.
4. The grease composition according to claim 1, wherein the solid
lubricant is at least one selected from melamine cyanulate,
polytetrafluoroethylene, and boron nitride.
5. The grease composition according to claim 1, wherein the
urea-based thickener is at least one selected from an aliphatic
diurea compound, an alicyclic diurea compound, and an aromatic
diurea compound.
6. The grease composition according to claim 1, the grease
composition being used for lubrication of metal-metal sliding
parts.
7. A method for producing a grease composition that comprises at
least one base oil selected from a mineral oil-based lubricant base
oil and a synthetic lubricant base oil, an amide compound, a solid
lubricant, and a urea-based thickener, wherein the method comprises
adding the amide compound to the base oil, followed by heating to
melt the amide compound at least once.
Description
TECHNICAL FIELD
[0001] The invention relates to a grease composition that utilizes
a urea-based thickener.
BACKGROUND ART
[0002] Grease has been mainly used for slide bearings, rolling
bearings, and sliding surfaces where it is difficult to maintain
adhesion of a lubricant film due to the movement of the contact
surface. In particular, urea-based grease that utilizes a
urea-based thickener exhibits excellent water resistance,
mechanical stability, and heat resistance, and has been widely used
for metal-metal sliding parts at a low speed with a high load such
as an automotive constant-velocity joint.
[0003] A grease composition that comprises a base oil, an
organomolybdenum compound (e.g., a molybdenum
dialkyldithiocarbamate sulfide), a molybdenum disulfide, a zinc
dithiophosphate compound, and an aliphatic amide has been proposed
as a grease composition used for a constant-velocity joint (see PTL
1 to 3).
[0004] However, the above grease composition is insufficient in
terms of lubricity and particularly wear resistance, and shows a
deterioration in wear resistance during long-term use at a high
temperature.
CITATION LIST
Patent Literature
[0005] PTL 1: JP-A-2001-11481
[0006] PTL 2: JP-A-2005-226038
[0007] PTL 3: JP-A-2008-19288
SUMMARY OF INVENTION
Technical Problem
[0008] An object of the invention is to provide a grease
composition that exhibits excellent lubricity, in particular
excellent wear resistance, and shows only a small extent of
deterioration in wear resistance with long-term use at high
temperatures.
Solution to Problem
[0009] The inventors of the invention conducted extensive studies
in order to achieve the above object. As a result, the inventors
found that, in comparison with a grease composition that is
prepared by merely dispersing and mixing an amide compound powder
into grease, a grease composition obtained by heating and melting
an amide compound in the presence of a lubricant base oil forms a
three-dimensional network structure of the amide holding the
lubricant base oil therein to afford the grease composition
significantly improved wear resistance and to show only a small
extent of deterioration in wear resistance with long-term use under
high temperatures.
[0010] The invention was completed based on the above finding, and
provides the following. [0011] (1) A grease composition comprising
at least one base oil selected from a mineral oil-based lubricant
base oil and a synthetic lubricant base oil, an amide compound, a
solid lubricant, and a urea-based thickener, wherein the amide
compound is heated and melted at least once together with the base
oil. [0012] (2) The grease composition according to (1), wherein
the mineral oil-based lubricant base oil and the synthetic
lubricant base oil have a kinematic viscosity of 1 to 1000
mm.sup.2/s at 40.degree. C. [0013] (3) The grease composition
according to (1) or (2), wherein the amide compound includes an
alkyl group having 6 to 24 carbon atoms. [0014] (4) The grease
composition according to any one of (1) to (3), wherein the solid
lubricant is at least one selected from melamine cyanulate,
polytetrafluoro ethylene, and boron nitride. [0015] (5) The grease
composition according to any one of (1) to (4), wherein the
urea-based thickener is at least one selected from an aliphatic
diurea compound, an alicyclic diurea compound, and an aromatic
diurea compound. [0016] (6) The grease composition according to any
one of (1) to (5), the grease composition being used for
lubrication of metal-metal sliding parts. [0017] (7) A method for
producing a grease composition that comprises at least one base oil
selected from a mineral oil-based lubricant base oil and a
synthetic lubricant base oil, an amide compound, a solid lubricant,
and a urea-based thickener, wherein the method comprises adding the
amide compound to the base oil, followed by heating to melt the
amide compound at least once.
Advantageous Effects of Invention
[0018] The grease composition according to the invention exhibits
excellent water resistance, mechanical stability, and heat
resistance, provides excellent wear resistance to metal-metal
sliding parts at a low speed with a high load, and shows only a
small extent of deterioration in wear resistance with long-term use
under high temperatures.
DESCRIPTION OF EMBODIMENTS
[0019] The grease composition according to the invention comprises
a lubricant base oil, an amide compound, a solid lubricant, and a
urea-based thickener.
[Lubricant Base Oil]
[0020] A mineral oil-based lubricant base oil or a synthetic
lubricant base oil may be used as the lubricant base oil used in
connection with the invention. It is preferable to use a lubricant
base oil having a kinematic viscosity of 1 to 1000 mm.sup.2/s, and
more preferably 20 to 300 mm.sup.2/s at 40.degree. C. If the
kinematic viscosity (at 40.degree. C.) of the lubricant base oil
falls outside the range of 1 to 1000 mm.sup.2/s, it may be
difficult to easily prepare a grease composition having the desired
consistency.
[0021] It is preferable to use a lubricant base oil having a
density of 0.75 to 0.95 g/cm.sup.3 at 15.degree. C. since the
dispersibility of the solid lubricant is improved. In order to
prepare grease having excellent lubricity, it is preferable to use
a lubricant base oil having a viscosity index of 90 or more (more
preferably 95 to 250), a pour point of -10.degree. C. or less (more
preferably -15 to -70.degree. C.), and a flash point of 150.degree.
C. or more.
[0022] Examples of the mineral oil-based lubricant base oil include
lubricant fractions obtained by distilling crude oil under
atmospheric pressure optionally followed by distillation under
reduced pressure to obtain a distillate, and refining the
distillate using various types of refining process. Examples of the
refining process include hydrotreating, solvent extraction, solvent
dewaxing, hydrodewaxing, washing with sulfuric acid, clay
treatment, and the like. The base oil used in connection with the
invention can be obtained by combining these processes in an
appropriate order. A mixture of a plurality of refined oils having
different properties is also useful, wherein the mixture is
obtained by using different types of crude oils or distillates and
by a different combination and/or order of processes. The base oil
obtained by each method may preferably be used as long as the
properties of the base oil are adjusted to fall within the above
ranges.
[0023] It is preferable to use a material that exhibits excellent
hydrolytic stability as the synthetic lubricant base oil. Examples
of the synthetic lubricant base oil include polyolefins such as a
poly-.alpha.-olefin, a polybutene, and a copolymer of two or more
olefins, polyesters, polyalkylene glycols, alkylbenzenes,
alkylnaphthalenes, and the like. It is preferable to use a
poly-.alpha.-olefin from the viewpoint of availability, cost,
viscosity, oxidation stability, and compatibility with a system
member. A polymer of 1-dodecene or 1-decene is more preferable as
the poly-.alpha.-olefin from the viewpoint of cost.
[0024] These synthetic lubricant base oils may be used either alone
or in combination. The synthetic lubricant base oil may be used in
combination with the mineral oil-based lubricant base oil.
[0025] When using a mixture of a plurality of types of lubricant
base oil including a synthetic lubricant base oil, the properties
of each base oil are not necessary to fall within the above ranges
as long as the base oil mixture satisfies the above properties.
Therefore, each synthetic base oil need not necessarily satisfy the
above properties, but it is preferable that the properties of each
synthetic base oil fall within the above ranges.
[0026] The content of the lubricant base oil in the grease
composition is preferably 50 to 95 mass %, and more preferably 60
to 85 mass %, based on the total amount of the grease composition.
If the content of the lubricant base oil is outside the range of 50
to 95 mass %, it may be difficult to easily prepare a grease
composition having the desired consistency.
[Amide Compound]
[0027] The amide compound used in connection with the invention is
a monoamide that includes one amide group (--NH--CO--), a bisamide
that includes two amide groups, a triamide that includes three
amide groups, or the like. The bisamide and the triamide have an
advantage in that the frictional resistance in the sliding part can
be reduced even when the amide compound is used in a relatively
small amount.
[0028] The bisamide may be an acid amide of a diamine or an acid
amide of a diacid.
[0029] It is preferable to use an amide compound having a melting
point of 40 to 180.degree. C. (more preferably 80 to 180.degree.
C., and still more preferably 100 to 170.degree. C.) and a
molecular weight of 242 to 932 (more preferably 298 to 876).
[0030] The monoamide is represented by the following general
formula (1), the bisamide is represented by the following general
formulas (2) and (3), and the triamide is represented by the
following general formula (4).
R.sup.1--CO--NH--R.sup.2 (1)
R.sup.1--CO--NH-A.sup.1-NH--CO--R.sup.2 (2)
R.sup.1--NH--CO-A.sup.1-CO--NH--R.sup.2 (3)
R.sup.1-M-A.sup.1-CH(A.sup.2-M-R.sup.3)-A.sup.3-M-R.sup.2 (4)
wherein R.sup.1, R.sup.2, and R.sup.3 are independently a
hydrocarbon group having 5 to 25 carbon atoms. The hydrocarbon
group may be an aliphatic hydrocarbon group, an alicyclic
hydrocarbon group, or an aromatic hydrocarbon group. R.sup.2 in the
general formula (1) may be a hydrogen atom. A.sup.1, A.sup.2, and
A.sup.3 are independently an aliphatic hydrocarbon group having 1
to 10 carbon atoms, an alicyclic hydrocarbon group, an aromatic
hydrocarbon group, or a divalent hydrocarbon group having 1 to 10
carbon atoms formed by combining these groups, and M is an amide
group.
[0031] It is preferable that R.sup.2 is a hydrogen atom or a
saturated or unsaturated chain hydrocarbon group having 10 to 20
carbon atoms when the amide compound is the monoamide.
[0032] It is preferable that A.sup.1 is a divalent saturated chain
hydrocarbon group having 1 to 4 carbon atoms when the amide
compound is the acid amide of a diamine.
[0033] Some of the hydrogen atoms of the hydrocarbon group
represented by R.sup.1, R.sup.2, or A.sup.1 in the general formulas
(2) and (3) may be substituted with a hydroxyl group (--OH).
[0034] An amide compound in which A.sup.1, A.sup.2, and A.sup.3 are
an aliphatic hydrocarbon group is referred herein to as "aliphatic
amide", an amide compound in which at least one of A.sup.1,
A.sup.2, and A.sup.3 is an aromatic hydrocarbon group is referred
herein to as "aromatic amide", and an amide compound in which at
least one of A.sup.1, A.sup.2, and A.sup.3 is an alicyclic
hydrocarbon group or an aromatic hydrocarbon group is referred
herein to as "non-aliphatic amide".
[0035] It is preferable that R.sup.1, R.sup.2, and R.sup.3 is a
saturated or unsaturated chain hydrocarbon group having 10 to 20
carbon atoms when the amide compound is the aliphatic amide.
[0036] It is preferable that R.sup.1, R.sup.2, and R.sup.3 is a
saturated or unsaturated chain hydrocarbon group having 10 to 20
carbon atoms or an aromatic hydrocarbon group when the amide
compound is the aromatic amide.
[0037] The non-aliphatic amide may also be used as the amide
compound, but it is preferable to use the aliphatic amide as the
amide compound. It is preferable that A.sup.1 is a divalent
saturated chain hydrocarbon group having 1 to 4 carbon atoms when
the amide compound is the acid amide of a diamine (general formula
(3)).
[0038] Specific examples of the monoamide include saturated fatty
acid amides such as lauric acid amide, palmitic acid amide, stearic
acid amide, behenic acid amide, and hydroxystearic acid amide,
unsaturated fatty acid amides such as oleic acid amide and erucic
acid amide, substituted amides of a saturated or unsaturated
long-chain fatty acid and a long-chain amine such as stearylstearic
acid amide, oleyloleic acid amide, oleylstearic acid amide, and
stearyloleic acid amide, and the like.
[0039] Specific examples of the acid amide of a diamine represented
by the general formula (2) include ethylene bis-stearic acid amide,
ethylene bis-isostearic acid amide, ethylene bis-oleic acid amide,
methylene bis-lauric acid amide, hexamethylene bis-oleic acid
amide, hexamethylene bis-hydroxystearic acid amide, and the like.
Specific examples of the bisamide of a diacid represented by the
general formula (3) include N,N'-bis-stearylsebacic acid amide and
the like.
[0040] Among these, the amide compounds represented by the general
formula (2) or (3) in which R.sup.1 and R.sup.2 are independently a
saturated chain hydrocarbon group or an unsaturated chain
hydrocarbon group having 12 to 20 carbon atoms are preferable.
[0041] There are various triamide compounds that are represented by
the general formula (4). Specific examples of a compound among the
compounds represented by the general formula (4) that can be
suitably used in connection with the invention include an
N-acylamino acid diamide compound. The N-acyl group included in the
N-acylamino acid diamide compound is preferably a linear or
branched saturated or unsaturated aliphatic acyl group having 1 to
30 carbon atoms, or an aromatic acyl group in particular, a caproyl
group, a capryloyl group, a lauroyl group, a myristoyl group, or a
stearoyl group. The amino acid included in the N-acylamino acid
diamide compound is preferably aspartic acid or glutamic acid. The
amine of the amide group included in the N-acylamino acid diamide
compound is preferably a linear or branched saturated or
unsaturated aliphatic amine having 1 to 30 carbon atoms, and more
preferably butylamine, octylamine, laurylamine, isostearylamine, or
stearylamine. In particular, N-lauroyl-L-glutamic
acid-.alpha.,.gamma.-di-n-butylamide is preferable.
[0042] These amide compounds may be used either alone or in
combination. The content of the amide compound in the grease
composition is preferably 0.1 to 50 mass %, and more preferably 3
to 35 mass %, based on the total amount of the grease
composition.
[Solid Lubricant]
[0043] The solid lubricant is not particularly limited as long as
the solid lubricant is normally used as a lubricant. It is
preferable to use a layered compound or a fluororesin as the solid
lubricant due to excellent lubricity.
[0044] A compound having a layered crystal structure such as
melamine cyanulate, boron nitride, graphite, mica, and fluorinated
graphite is preferable as the layered compound. Note that it is
undesirable to use a compound that includes a heavy metal or sulfur
from the viewpoint of environmental pollution and the like.
[0045] Examples of a preferable fluororesin include a
polytetrafluoroethylene (PTFE), a
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), a
tetrafluoroethylene-hexafluoropropylene copolymer (FEP), a
tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene
fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and the
like.
[0046] These solid lubricants may be used either alone or in
combination. A solid lubricant having an appropriate particle size
may be selected depending on the application. It is preferable to
use a solid lubricant having a particle size (diameter) of 0.2 to
50 .mu.m, and more preferably 1 to 10 .mu.m.
[0047] The content of the solid lubricant in the grease composition
is preferably 0.1 to 10 mass %, and more preferably 0.2 to 5 mass
%, based on the total amount of the grease composition.
[Urea-Based Thickener]
[0048] A diurea compound obtained by reacting a diisocyanate with a
monoamine, a polyurea compound obtained by reacting a diisocyanate
with a monoamine and a diamine, or the like may be used as the
urea-based thickener.
[0049] Examples of a preferable diisocyanate include phenylene
diisocyanate, tolylene diisocyanate, diphenyl diisocyanate,
diphenylmethane diisocyanate, octadecane diisocyanate, decane
diisocyanate, hexane diisocyanate, and the like. Examples of a
preferable monoamine include octylamine, dodecylamine,
hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine,
cyclohexylamine, and the like. Examples of a preferable diamine
include ethylenediamine, propanediamine, butanediamine,
hexanediamine, octanediamine, phenylenediamine, tolylenediamine,
xylenediamine, diaminodiphenylmethane, and the like.
[0050] These urea-based thickeners may be used either alone or in
combination. The content of the urea-based thickener in the grease
composition may be appropriately determined as long as the desired
consistency can be obtained. For example, the content of the
urea-based thickener in the grease composition is preferably 2 to
30 mass %, and more preferably 5 to 20 mass %, based on the total
amount of the grease composition.
[Additive]
[0051] The grease composition according to the invention may
optionally include a detergent, a dispersant, an antiwear agent, a
viscosity index improver, an antioxidant, an extreme pressure
agent, a rust-preventive agent, a corrosion inhibitor, and the like
that are normally used for a lubricant or grease in addition to the
above components.
[Preparation Method]
[0052] The grease composition according to the invention may be
prepared using a normal grease preparation method. It is preferable
to heat a mixture comprising the amide compound to a temperature
equal to or higher than the melting point of the amide compound at
least once, after mixing the amide compound.
[0053] Specifically, the grease composition may be prepared by
heating the amide compound and the lubricant base oil to a
temperature equal to or higher than the melting point of the amide
compound, cooling the mixture, and then physically mixing the
cooled mixture with normal grease that comprises the solid
lubricant, the thickener, and the lubricant base oil.
Alternatively, all of the components including the urea-based
thickener may be mixed, heated to a temperature equal to or higher
than the melting point of the amide compound, and then cooled.
[0054] When the amide compound is heated to a temperature equal to
or higher than the melting point of the amide compound in the
presence of at least the lubricant base oil, the lubricant base oil
is held in a semi-solid gel state by the amide compound that forms
a three-dimensional network structure, but freely moves within the
network structure microscopically. This suggests that, when the
gel-like composition having lubricity comes in contact with small
voids formed in a porous material, the liquid lubricant base oil
can move into the small voids from the gel due to a capillary
phenomenon, or suggests that, when an excess liquid lubricant base
oil is present in the system, the excess liquid lubricant base oil
is incorporated in the gel due to a capillary phenomenon through
the three-dimensional structure of the gel, for example. The
urea-based thickener provides consistency in such a state. The
grease composition thus exhibits excellent water resistance,
mechanical stability, and heat resistance, provides excellent wear
resistance, and shows only a small extent of deterioration in wear
resistance with long-term use under high temperatures.
EXAMPLES
1. Lubricant Base Oil
(1) Mineral Oil-Based Lubricant Base Oil
[0055] Lubricant base oil obtained by distilling atmospheric
distillation residue under reduced pressure and subjecting the
resulting distillate to solvent refining [0056] Kinematic viscosity
at 40.degree. C.: 68 mm.sup.2/s [0057] Density at 15.degree. C.:
0.87 g/cm.sup.3 [0058] Viscosity index: 100 [0059] Pour point:
-10.degree. C. [0060] Flash point: 250.degree. C.
(2) Synthetic Lubricant Base Oil
[0060] [0061] Poly-.alpha.-olefin ("Durasyn 170" manufactured by
INEOS) [0062] Kinematic viscosity at 40.degree. C.: 68 mm.sup.2/s
[0063] Density at 15.degree. C.: 0.83 g/cm.sup.3 [0064] Viscosity
index: 133 [0065] Pour point: -45.degree. C. [0066] Flash point:
250.degree. C.
2. Amide Compound
2-1. Aliphatic Amide
[0066] [0067] (1) Ethylene bis-stearic acid amide (special grade
reagent) [0068] (2) Ethylene bis-oleic acid amide (special grade
reagent) [0069] (3) Stearic acid monoamide (special grade
reagent)
2-2. Aromatic Amide
[0069] [0070] (1) m-Xylylene bis-stearic acid amide (special grade
reagent)
3. Solid Lubricant
[0070] [0071] (1) Melamine cyanulate (MCA, average particle size: 4
.mu.m, "MELAPUR MC25" manufactured by BASF) [0072] (2)
Polytetrafluoroethylene (PTFE, average particle size: 4 .mu.m,
"KTL-8N" manufactured by Kitamura Limited) [0073] (3) Boron nitride
(average particle size: 2 .mu.m, "HP-P1" manufactured by Mizushima
Ferroalloy Co., Ltd.)
[0074] The average particle size was measured by laser
diffractometry.
4. Urea-Based Thickener
[0075] (1) Aliphatic diurea obtained by reacting octadecylamine
with methylenediphenyl diisocyanate [0076] (2) Alicyclic diurea
obtained by reacting cyclohexylamine with methylenediphenyl
diisocyanate [0077] (3) Aromatic diurea obtained by reacting
p-toluidine with methylenediphenyl diisocyanate
5. Additive
[0078] Diphenylamine was added to each composition as an
antioxidant.
[Preparation Method]
[0079] Each component was charged in a vessel in the amount (wt %)
shown in Table 1 or 2, heated to 150.degree. C., which is a
temperature equal to or higher than the melting point of the amide,
stirred using a magnetic stirrer, and then cooled to room
temperature. The mixture was dispersed under pressure using a
roller (triple roll) to prepare a grease composition.
[0080] In Comparative Example 7, each component in the amount shown
in Table 2 was dispersed directly without heating and cooling under
pressure using a roller (triple roll) to prepare a grease
composition.
[Evaluation Test]
[0081] A friction test was performed at a load of 350 lbf for 15
minutes using a FALEX Pin and Vee Block tester to evaluate the
amount of wear of the sample. In order to evaluate the performance
when the grease has been used under severe conditions, the FALEX
test was also performed using a flesh grease and a degraded grease
that is obtained by leaving the flesh grease at 150.degree. C. for
100 hours or 500 hours.
[Evaluation Results]
[0082] When only the mineral oil and the urea-based thickener were
mixed, the amount of wear was about 7 mg when using the fresh
grease, but was significantly large when using the degraded grease
(Comparative Example 6).
[0083] When the mineral oil, the urea-based thickener, and the
solid lubricant were mixed, the amount of wear decreased to some
extent when using the fresh grease, but was large when using the
degraded grease (Comparative Examples 1 to 5).
[0084] When the aliphatic amide was not heated and melted, the
amount of wear was large when using the fresh grease and when using
the degraded grease (Comparative Example 7).
[0085] When the mineral oil, the urea-based thickener, the solid
lubricant, and the aliphatic amide were mixed, the amount of wear
significantly decreased when using the fresh grease and when using
the degraded grease (Examples 1 to 9).
TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 Lubricant
Mineral oil 78 72 70 75 72 75 77 75 75 base oil PAO 75 Amide
Stearic acid monoamide 13 compound Stearic acid bisamide 10 10 10
10 10 15 5 Oleic acid bisamide 15 Aromatic amide 10 Solid MCA 4 4 4
4 4 4 4 4 lubricant PTFE 4 Boron nitride 4 Thickener Aliphatic
diurea 7 Alicyclic diurea 10 10 10 6 10 10 8 15 10 Aromatic diurea
6 Antioxidant Diphenylamine 1 1 1 1 1 1 1 1 1 1 Evaluation Fresh
grease: FALEX amount of wear 1.0 1.5 1.3 1.2 1.0 0.9 1.0 0.9 1.8
1.5 results 100 h degraded grease: FALEX amount of wear 1.5 1.2 1.5
1.5 0.8 1.3 1.4 1.0 2.5 2.0 500 h degraded grease: FALEX amount of
wear 1.8 1.2 2.0 1.5 1.3 1.0 1.3 1.0 2.2 2.1
TABLE-US-00002 TABLE 2 Comparative example 1 2 3 4 5 6 7 Lubricant
base oil Mineral oil 85 77 75 77 77 79 75 Amide compound Stearic
acid bisamide 10 Solid MCA 4 4 4 4 lubricant PTFE 4 Boron nitride 4
Thickener Aliphatic diurea 10 Alicyclic diurea 18 10 18 18 20 10
Aromatic diurea 10 Antioxidant Diphenylamine 1 1 1 1 1 1 1
Evaluation Fresh grease: FALEX amount of wear 4.5 6.0 4.0 4.5 3.5
7.0 27 results 100 h degraded grease: FALEX amount of wear 25 28 30
27 32 28 -- 500 h degraded grease: FALEX amount of wear 30 34 28 32
34 38 -- In Comparative Example 7, the grease composition was
prepared without heating and cooling after adding stearic acid
bisamide.
INDUSTRIAL APPLICABILITY
[0086] Since the grease composition according to the invention
exhibits excellent water resistance, mechanical stability, and heat
resistance, provides excellent wear resistance to metal-metal
sliding parts at a low speed with a high load, and shows only a
small extent of deterioration in wear resistance with long-term use
under high temperatures, the grease composition can be used to
lubricate a joint, a gear, and a bearing, and the like that have
metal-metal sliding parts.
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