U.S. patent application number 10/522144 was filed with the patent office on 2006-05-25 for grease composition.
Invention is credited to Takashi Arai, Hirotsugu Kinoshita, Souichi Nomura, Kiyomi Sakamoto, Kazuhiro Yagishita.
Application Number | 20060111256 10/522144 |
Document ID | / |
Family ID | 30767938 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060111256 |
Kind Code |
A1 |
Kinoshita; Hirotsugu ; et
al. |
May 25, 2006 |
Grease composition
Abstract
A grease composition comprising a lubricating base oil combined
with (A) 2-30 wt % of a thickener and (B) 0.1-10 wt % of at least
one type of compound selected from the group consisting of
phosphorus compounds represented by general formulas (1) and (2)
below and their metal salts or amine salts, based on the total
weight of the composition. ##STR1## [wherein X.sup.1, X.sup.2 and
X.sup.3 each represent an oxygen atom or sulfur atom, with at least
two from among X.sup.1, X.sup.2 and X.sup.3 being oxygen atoms, and
R.sup.1, R.sup.2 and R.sup.3 each represent hydrogen or a C1-30
hydrocarbon group] ##STR2## [wherein X.sup.4, X.sup.5, X.sup.6 and
X.sup.7 each represent an oxygen atom or sulfur atom, with at least
three from among X.sup.4, X.sup.5, X.sup.6 and X.sup.7 being oxygen
atoms, and R.sup.4, R.sup.5 and R.sup.6 each represent hydrogen or
a C1-30 hydrocarbon group].
Inventors: |
Kinoshita; Hirotsugu;
(Kanagawa, JP) ; Nomura; Souichi; (Tokyo, JP)
; Arai; Takashi; (Kanagawa, JP) ; Sakamoto;
Kiyomi; (Kanagawa, JP) ; Yagishita; Kazuhiro;
(Kanagawa, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
30767938 |
Appl. No.: |
10/522144 |
Filed: |
July 24, 2003 |
PCT Filed: |
July 24, 2003 |
PCT NO: |
PCT/JP03/09409 |
371 Date: |
August 5, 2005 |
Current U.S.
Class: |
508/552 |
Current CPC
Class: |
C10M 2223/042 20130101;
C10M 2207/1285 20130101; C10M 2203/1006 20130101; C10M 2223/047
20130101; C10N 2010/04 20130101; C10M 2223/04 20130101; C10M
2223/045 20130101; C10N 2010/12 20130101; C10M 2205/0206 20130101;
C10N 2030/06 20130101; C10N 2050/10 20130101; C10M 2217/0456
20130101; C10M 2219/068 20130101; C10M 169/06 20130101; C10M
2223/049 20130101; C10M 2215/1026 20130101; C10M 2223/043
20130101 |
Class at
Publication: |
508/552 |
International
Class: |
C10M 115/08 20060101
C10M115/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2002 |
JP |
2002-215726 |
Claims
1. A grease composition comprising a lubricating base oil combined
with (A) 2-30 wt % of a thickener and (B) 0.1-10 wt % of at least
one type of compound selected from the group consisting of
phosphorus compounds represented by general formulas (1) and (2)
below and their metal salts or amine salts, based on the total
weight of the composition. ##STR12## [wherein X.sup.1, X.sup.2 and
X.sup.3 may be the same or different and each represents an oxygen
atom or sulfur atom, with at least two from among X.sup.1, X.sup.2
and X.sup.3 being oxygen atoms, and R.sup.1, R.sup.2 and R.sup.3
may be the same or different and each represents hydrogen or a
C1-30 hydrocarbon group] ##STR13## [wherein X.sup.4, X.sup.5,
X.sup.6 and X.sup.7 may be the same or different and each
represents an oxygen atom or sulfur atom, with at least three from
among X.sup.4, X.sup.5, X.sup.6 and X.sup.7 being oxygen atoms, and
R.sup.4, R.sup.5 and R.sup.6 may be the same or different and each
represents hydrogen or a C1-30 hydrocarbon group].
2. A grease composition according to claim 1, which further
comprises an organic molybdenum compound.
3. A grease composition according to claim 1, wherein said
thickener is a lithium soap.
4. A grease composition according to claim 1, wherein said
thickener is a urea-based thickener.
5. A grease composition according to claim 1, wherein said
thickener is a urea-based thickener represented by the following
general formula (3). A-CONH--R.sup.7--NHCO--B (3) [wherein A and B
may be the same or different and each is a group represented by
--NHR.sup.8, --NR.sup.9R.sup.10 or --OR.sup.11 (where R.sup.8,
R.sup.9, R.sup.10 and R.sup.11 may be the same or different and
each represents a C6-20 hydrocarbon group), and R.sup.7 is a
divalent hydrocarbon group].
6. A grease composition according to claim 1, which comprises at
least one compound selected from among compounds represented by
general formula (1) wherein X.sup.1, X.sup.2 and X.sup.3 are all
oxygen atoms and compounds represented by general formula (2)
wherein X.sup.4, X.sup.5, X.sup.6 and X.sup.7 are all oxygen atoms.
Description
TECHNICAL FIELD
[0001] The present invention relates to a grease composition.
BACKGROUND ART
[0002] Grease is commonly used as a lubricant for mechanical parts
such as constant velocity gears, transmission gears, ball bearings,
roller bearings and the like.
[0003] Most of the members composing such mechanical parts are made
of metal, and friction between the metal members generates heat and
wear at the sections of contact, resulting in a shorter life of the
grease or of the mechanical parts themselves. Therefore, various
additives such as friction reducers are included in lubricants to
reduce the friction between metals.
[0004] In recent years, however, the higher performance and lighter
weights of such mechanical parts have resulted in restrictions on
the conditions for their use, and friction due to contact between
the metals occurs more frequently. With these types of mechanical
parts, it is often not possible to achieve an adequate
friction-reducing effect even when using conventional greases
containing added friction reducers.
[0005] In addition, grease-filled mechanical parts are more
frequently being used at ever higher temperatures, and therefore a
grease which can provide a high friction-reducing effect even at
high temperatures has been strongly desired.
[0006] The present invention has been accomplished in light of
these circumstances of the prior art, and its object is to provide
a grease composition which can exhibit a high friction-reducing
effect even at high temperatures.
[0007] In order to achieve this object, the grease composition of
the invention is characterized by comprising a lubricating base oil
combined with (A) 2-30 wt % of a thickener and (B) 0.1-10 wt % of
at least one type of compound selected from the group consisting of
phosphorus compounds represented by general formulas (1) and (2)
below and their metal salts or amine salts, based on the total
weight of the composition. ##STR3## [wherein X.sup.1, X.sup.2 and
X.sup.3 may be the same or different and each represents an oxygen
atom or sulfur atom, with at least two from among X.sup.1, X.sup.2
and X.sup.3 being oxygen atoms, and R.sup.1, R.sup.2 and R.sup.3
may be the same or different and each represents hydrogen or a
C1-30 hydrocarbon group] ##STR4## [wherein X.sup.4, X.sup.5,
X.sup.6 and X.sup.7 may be the same or different and each
represents an oxygen atom or sulfur atom, with at least three from
among X.sup.4, X.sup.5, X.sup.6 and X.sup.7 being oxygen atoms, and
R.sup.4, R.sup.5 and R.sup.6 may be the same or different and each
represents hydrogen or a C1-30 hydrocarbon group].
[0008] According to the invention, combining a lubricating base oil
with (A) a thickener and (B) at least one type of compound selected
from the group consisting of phosphorus compounds represented by
general formulas (1) and (2) above and their metal salts or amine
salts in prescribed amounts yields a grease composition having a
sufficiently high friction-reducing effect, and maintaining the
high friction-reducing effect even at high temperature. Thus, even
with increased speeds and lighter weights of mechanical parts such
as constant velocity gears, or the use of such mechanical parts at
high temperatures, it is possible to prevent heat generation and
wear due to friction between metals, to achieve satisfactorily
lengthening of the usable life of grease and mechanical parts.
[0009] The grease composition of the invention preferably further
comprises an organic molybdenum compound.
[0010] The (A) thickener in the grease composition of the invention
is preferably lithium soap.
[0011] Alternatively, the (A) thickener in the grease composition
of the invention is preferably a urea-based thickener, and more
preferably a urea-based thickener represented by the following
general formula (3). A-CONH--R.sup.7--NHCO--B (3) [wherein A and B
may be the same or different and each is a group represented by
--NHR.sup.8, --NR.sup.9R.sup.10 or --OR.sup.11 (where R.sup.8,
R.sup.9, R.sup.10 and R.sup.11 may be the same or different and
each represents a C6-20 hydrocarbon group), and R.sup.7 is a
divalent hydrocarbon group].
[0012] The grease composition of the invention preferably comprises
at least one compound selected from among compounds represented by
general formula (1) wherein X.sup.1, X.sup.2 and X.sup.3 are all
oxygen atoms and compounds represented by general formula (2)
wherein X.sup.4, X.sup.5, X.sup.6 and X.sup.7 are all oxygen atoms.
In this case, component (B) may include both a compound wherein
X.sup.1--X.sup.7 are all oxygen atoms and a compound wherein one
from among X.sup.1--X.sup.7 is a sulfur atom while the others are
oxygen atoms, but component (B) is preferably composed of only a
compound wherein X.sup.1--X.sup.7 are all oxygen atoms.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1A and 1B are a perspective view and top view,
respectively, of a test strip used for a friction test.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] Preferred embodiments of the present invention will now be
explained in detail.
[0015] As lubricating base oils to be used in the grease
composition of the invention there may be mentioned mineral oils
and/or synthetic oils.
[0016] Mineral oils include, for example, those obtained by methods
commonly employed in lubricating oil production processes for
petroleum refining, and more specifically, there may be mentioned
oils obtained by ordinary pressure distillation or reduced pressure
distillation of crude oil, followed by purification of the
lubricating oil fraction by oil deasphalting, solvent extraction,
hydrogenating decomposition, solvent dewaxing, catalytic dewaxing,
hydrogenation refining, sulfuric acid washing, clay refining and
the like.
[0017] As specific examples of synthetic oils there may be
mentioned poly .alpha.-olefins such as polybutene, 1-octene
oligomer and 1-decene oligomer or 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-ethylhexanoate
and pentaerythritol pelargonate; alkylnaphthalenes; alkylbenzenes;
polyoxyalkylene glycols; polyphenyl ethers; dialkyldiphenyl ethers;
silicone oils; and mixtures thereof.
[0018] The dynamic viscosity of these lubricating base oils 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 base oil used is
preferably 90 or greater and more preferably 100 or greater.
[0019] According to the invention, the aforementioned lubricating
base oil is combined with (A) a thickener and (B) at least one type
of compound selected from the group consisting of phosphorus
compounds represented by general formulas (1) and (2) above and
their metal salts or amine salts in prescribed amounts. Hereunder,
these components will sometimes be referred to as component (A) and
component (B).
[0020] There are no particular restrictions on the (A) thickener,
but soap-based thickeners, for example, are preferably used. Using
a soap-based thickener can increase the effect of preventing damage
to mechanical parts.
[0021] As specific examples of soap-based thickeners there may be
mentioned sodium soaps, calcium soaps, aluminum soaps and lithium
soaps, but lithium soaps are preferred among these from the
standpoint of moisture resistance and thermal stability. As
examples of lithium soaps there may be mentioned lithium stearate
and lithium-12-hydroxystearate.
[0022] Preferred examples for the (A) thickener are urea-based
thickeners. Using a urea-based thickener can increase the effect of
preventing damage to mechanical parts.
[0023] 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-urethane compounds and diurethane compounds,
and mixtures thereof. Preferred among these are diurea compounds,
urea-urethane compounds, diurethane compounds and mixtures
thereof.
[0024] Preferred examples of urea-based thickeners are those
represented by the following general formula (3).
A-CONH--R.sup.7--NHCO--B (3)
[0025] The compounds represented by general formula (3) include
diurea compounds, urea-urethane compounds and diurethane
compounds.
[0026] In formula (3), A and B may be the same or different and
each is a group represented by --NHR.sup.8, --NR.sup.9R.sup.10 or
--OR.sup.11. Here, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 may be
the same or different and each represents a C6-20 hydrocarbon
group.
[0027] As examples of hydrocarbon groups represented by R.sup.8,
R.sup.9, R.sup.10 and R.sup.11 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 toluyl, ethylphenyl,
xylyl, propylphenyl, cumenyl, methylnaphthyl, ethylnaphthyl,
dimethylnaphthyl and propylnaphthyl; and arylalkyl groups such as
benzyl, methylbenzyl and ethylbenzyl, among which cyclohexyl,
octadecyl and toluyl groups are particularly preferred.
[0028] R.sup.7 in formula (3) is a divalent hydrocarbon group. As
specific divalent hydrocarbon groups there may be mentioned
straight-chain or branched alkylene groups and straight-chain or
branched alkenylene, cycloalkylene, arylene, alkylarylene and
arylalkylene groups. The number of carbon atoms of the divalent
hydrocarbon group represented by R.sup.7 is preferably 6-20 and
more preferably 6-15.
[0029] As preferred examples of divalent hydrocarbon groups
represented by R.sup.7 there may be mentioned ethylene,
2,2-dimethyl-4-methylhexylene and groups represented by the
following formulas (4) to (13), among which groups represented by
formulas (5) and (7) are preferred. ##STR5##
[0030] The compounds represented by formula (3) may be obtained,
for example, by reacting a diisocyanate represented by
OCN--R.sup.7--NCO with a compound represented by R.sup.8NH.sub.2,
R.sup.9R.sup.10NH or R.sup.11OH or a mixture thereof in the base
oil at 10-200.degree. C. R.sup.7, R.sup.8, R.sup.9, R.sup.10 and
R.sup.11 in the formulas for the raw material compounds have the
same respective definitions as R.sup.7, R.sup.8, R.sup.9, R.sup.10
and R.sup.11 in formula (3)
[0031] Bentone, silica gel or the like may be used as the (A)
thickener.
[0032] The content of component (A) in the grease composition of
the invention is 2-30 wt % based on the total weight of the
composition. If the content of the thickener is less than 2 wt %,
the effect of adding the thickener will be insufficient, producing
a less than satisfactory grease condition of the grease
composition. For the same reason, the content of component (A) is
preferably at least 5 wt % and more preferably at least 10 wt %
based on the total composition. If the content of component (A) is
greater than 30 wt %, the grease composition will become too hard
and will fail to exhibit sufficient lubricating performance. For
the same reason, the thickener content is preferably no greater
than 25 wt % and more preferably no greater than 20 wt % based on
the total composition.
[0033] Component (B) of the grease composition of the invention is
at least one type of compound selected from the group consisting of
phosphorus compounds represented by general formulas (1) and (2)
below and their metal salts or amine salts. ##STR6## [wherein
X.sup.1, X.sup.2 and X.sup.3 may be the same or different and each
represents an oxygen atom or sulfur atom, with at least two from
among X.sup.1, X.sup.2 and X.sup.3 being oxygen atoms, and R.sup.1,
R.sup.2 and R.sup.3 may be the same or different and each
represents hydrogen or a C1-30 hydrocarbon group] ##STR7## [wherein
X.sup.4, X.sup.5, X.sup.6 and X.sup.7 may be the same or different
and each represents an oxygen atom or sulfur atom, with at least
three from among X.sup.4, X.sup.5, X.sup.6 and X.sup.7 being oxygen
atoms, and R.sup.4, R.sup.5 and R.sup.6 may be the same or
different and each represents hydrogen or a C1-30 hydrocarbon
group].
[0034] As specific C1-30 hydrocarbon groups represented by R.sup.1
to R.sup.6 there may be mentioned alkyl, cycloalkyl, alkenyl,
alkylcycloalkyl, aryl, alkylaryl and arylalkyl.
[0035] As examples of 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 (which alkyl groups may be either straight-chain or
branched).
[0036] 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 desired position of substitution of
the alkyl groups on the cycloalkyl groups).
[0037] 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 (which alkenyl groups may be either straight-chain
or branched, and the double bond may be at any desired
position).
[0038] 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 (which
alkyl groups may be either straight-chain or branched, with any
desired position of substitution on the aryl groups).
[0039] As examples of the aforementioned arylalkyl groups there may
be mentioned C7-12 arylalkyl groups such as benzyl, phenylethyl,
phenylpropyl, phenylbutyl, phenylpentyl and phenylhexyl (wherein
the alkyl groups may be either straight-chain or branched).
[0040] The C1-30 hydrocarbon groups represented by R.sup.1 to
R.sup.6 are preferably C1-30 alkyl groups or C6-24 aryl groups,
more preferably C3-18 alkyl groups, and even more preferably C4-12
alkyl groups.
[0041] R.sup.1, R.sup.2 and R.sup.3 may be the same or different
and each represents hydrogen or one of the aforementioned
hydrocarbon groups, with preferably 1 to 3, more preferably 1-2 and
even more preferably 2 from among R.sup.1, R.sup.2 and R.sup.3
being the aforementioned hydrocarbon groups.
[0042] Also, R.sup.4, R.sup.5 and R.sup.6 may be the same or
different and each represents hydrogen or one of the aforementioned
hydrocarbon groups, with preferably 1 to 3, more preferably 1 or 2
and even more preferably 2 from among R.sup.4, R.sup.5 and R.sup.6
being the aforementioned hydrocarbon groups.
[0043] In the phosphorus compounds represented by general formula
(1), at least two from among X.sup.1 to X.sup.3 must be oxygen
atoms, but preferably all of X.sup.1 to X.sup.3 are oxygen
atoms.
[0044] In the phosphorus compounds represented by general formula
(2), at least three from among X.sup.4 to X.sup.7 must be oxygen
atoms, but preferably all of X.sup.4 to X.sup.7 are oxygen
atoms.
[0045] As examples of phosphorus compounds represented by general
formula (1) 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.
Preferred among these are phosphorous acid monoesters and
phosphorous acid diesters, with phosphorous acid diesters being
more preferred.
[0046] As examples of phosphorus compounds represented by general
formula (2) 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.
Preferred among these are phosphoric acid monoesters and phosphoric
acid diesters, with phosphoric acid diesters being more
preferred.
[0047] As salts of the phosphorus compounds represented by general
formula (1) and (2) there may be mentioned salts having all or a
portion of the acidic hydrogens of the phosphorus compound
neutralized. Such phosphorus compound salts may be obtained by
reacting phosphorus compounds with metal bases such as metal
oxides, metal hydroxides, metal carbonates and metal chlorides, or
nitrogen compounds such as ammonia or amine compounds having only
C1-30 hydrocarbon groups or hydroxyl group-containing hydrocarbon
groups in the molecule.
[0048] As metals for these metal bases there may be mentioned,
specifically, alkali metals such as lithium, sodium, potassium and
cesium, alkaline earth metals such as calcium, magnesium and
barium, and heavy metals such as zinc, copper, iron, lead, nickel,
silver and manganese. Preferred among these are alkaline earth
metals such as calcium and magnesium, and zinc.
[0049] The aforementioned phosphorus compound metal salts differ in
structure depending on the valence of the metals and the numbers of
OH groups or SH groups in the phosphorus compounds, 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 having the structure represented
by formula (14) below may be obtained as the major product,
although it may also be obtained as a polymerized molecule.
##STR8##
[0050] As another example, 1 mole of zinc oxide may be reacted with
1 mole of a phosphoric monoester (two OH groups) to obtain a
compound having the structure represented by formula (15) below as
the major product, although it may also be obtained as a
polymerized molecule. ##STR9##
[0051] As examples of the aforementioned nitrogen compounds there
may be mentioned ammonia, monoamines, diamines, polyamines and the
like. Specific examples include alkylamines with C1-30 alkyl groups
such as methylamine, ethylamine, propylamine, butylamine,
pentylamine, hexylamine, heptylamine, octylamine, nonylamine,
decylamine, undecylamine, dodecylamine, tridecylamine,
tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine,
octadecylamine, dimethylamine, diethylamine, dipropylamine,
dibutylamine, dipentylamine, dihexylamine, diheptylamine,
dioctylamine, dinonylamine, didecylamine, diundecylamine,
didodecylamine, ditridecylamine, ditetradecylamine,
dipentadecylamine, dihexadecylamine, diheptadecylamine,
dioctadecylamine, methylethylamine, methylpropylamine,
methylbutylamine, ethylpropylamine, ethylbutylamine and
propylbutylamine (wherein the alkyl groups may be either
straight-chain or branched);
[0052] alkenylamines with C2-30 alkenyl groups such as
ethenylamine, propenylamine, butenylamine, octenylamine and
oleylamine (wherein the alkenyl groups may be either straight-chain
or branched); alkanolamines having C1-30 alkanol groups such as
methanolamine, ethanolamine, propanolamine, butanolamine,
pentanolamine, hexanolamine, heptanolamine, octanolamine,
nonanolamine, methanolethanolamine, methanolpropanolamine,
methanolbutanolamine, ethanolpropanolamine, ethanolbutanolamine and
propanolbutanolamine (wherein the alkanol groups may be either
straight-chain or branched);
[0053] alkylenediamines having C1-30 alkylene groups such as
methylenediamine, ethylenediamine, propylenediamine and
butylenediamine; polyamines such as diethylenetriamine,
triethylenetetramine, tetraethylenepentamine and
pentaethylenehexamine; compounds having C8-20 alkyl groups or
alkenyl groups on the aforementioned monoamines, diamines or
polyamines, such as undecyldiethylamine, undecyldiethanolamine,
dodecyldipropanolamine, oleyldiethanolamine, oleylpropylenediamine
and stearyltetraethylenepentamine, or heterocyclic compounds such
as N-hydroxyethyloleylimidazoline; alkylene oxide adducts of these
compounds; and mixtures thereof.
[0054] Preferred among these nitrogen compounds are aliphatic
amines (either straight-chain or branched) having C10-20 alkyl
groups or alkenyl groups, such as decylamines, dodecylamines,
tridecylamines, heptadecylamines, octadecylamines, oleylamines and
stearylamines.
[0055] According to the invention, component (B) is preferably a
metal salt or amine salt of a phosphorus compound represented by
general formula (1) or (2) above, and it is more preferably a metal
salt of the phosphorus compound. Using such compounds as component
(B) will tend to produce a greater friction-reducing effect.
[0056] From the standpoint of thermal stability there are preferred
phosphorus compounds represented by general formula (2) and their
salts.
[0057] The compounds for component (B) may be used alone or in
combinations of two or more.
[0058] The content of component (B) is 0.1-10 wt % based on the
total composition. If the content of component (B) is less than 0.1
wt %, the friction-reducing effect will be insufficient, and
reduction of friction between metal members of mechanical parts
will be impossible to achieve especially at high temperature. For
the same reason, the content of component (B) is preferably 0.3 wt
% or greater and more preferably 0.5 wt % or greater based on the
total composition. If the content of component (B) exceeds 10 wt %,
no commensurate improvement in the friction-reducing effect will be
achieved. For the same reason, the content of component (B) is
preferably no greater than 7 wt % and more preferably no greater
than 5 wt % based on the total composition.
[0059] The grease composition of the invention comprises component
(A) and component (B) described above added to the lubricating base
oil, but it may also contain an organic molybdenum compound in
addition to these components.
[0060] 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 (16) below, and the dithiocarbamic acid ester derivatives
represented by general formula (17) below. ##STR10##
[0061] In general formulas (16) and (17), each R may be the same or
different and represents a C1 or greater hydrocarbon group, the c
number of X groups may be the same or different with each
representing an oxygen or sulfur atom, and a, b and c each
represent integers of 1-6.
[0062] As examples of hydrocarbon groups represented by R in
formulas (16) and (17) above there may be mentioned C1-24 alkyl
groups, C5-7 cycloalkyl groups, C6-11 alkylcycloalkyl groups, C6-18
aryl groups, C7-24 alkylaryl groups and C7-12 arylalkyl groups.
[0063] 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).
[0064] As the aforementioned cycloalkyl groups there may be
mentioned, specifically, cyclopentyl, cyclohexyl and
cycloheptyl.
[0065] As the aforementioned alkylcycloalkyl groups there may be
mentioned, specifically, methylcyclopentyl (including all
substitution isomers), ethylcyclopentyl (including all substitution
isomers), dimethylcyclopentyl (including all substitution isomers),
propylcyclopentyl (including all branched isomers, substitution
isomers), methylethylcyclopentyl (including all substitution
isomers), trimethylcyclopentyl (including all substitution
isomers), butylcyclopentyl (including all branched isomers,
substitution isomers), methylpropylcyclopentyl (including all
branched isomers, substitution isomers), diethylcyclopentyl
(including all substitution isomers), dimethylethylcyclopentyl
(including all substitution isomers), methylcyclohexyl (including
all substitution isomers), ethylcyclohexyl (including all
substitution isomers), dimethylcyclohexyl (including all
substitution isomers), propylcyclohexyl (including all branched
isomers, substitution isomers), methylethylcyclohexyl (including
all substitution isomers), trimethylcyclohexyl (including all
substitution isomers), butylcyclohexyl (including all branched
isomers, substitution isomers), methylpropylcyclohexyl (including
all branched isomers, substitution isomers), diethylcyclohexyl
(including all substitution isomers), dimethylethylcyclohexyl
(including all substitution isomers), methylcycloheptyl (including
all substitution isomers), ethylcycloheptyl (including all
substitution isomers), dimethylcycloheptyl (including all
substitution isomers), propylcycloheptyl (including all branched
isomers, substitution isomers), methylethylcycloheptyl (including
all substitution isomers), trimethylcycloheptyl (including all
substitution isomers), butylcycloheptyl (including all branched
isomers, substitution isomers), methylpropylcycloheptyl (including
all branched isomers, substitution isomers), diethylcycloheptyl
(including all substitution isomers) and dimethylethylcycloheptyl
(including all substitution isomers).
[0066] As the aforementioned aryl groups there may be mentioned,
specifically, phenyl and naphthyl.
[0067] As the aforementioned alkylaryl groups there may be
mentioned, specifically, tolyl (including all substitution
isomers), xylyl (including all substitution isomers), ethylphenyl
(including all substitution isomers), propylphenyl (including all
branched isomers, substitution isomers), methylethylphenyl
(including all substitution isomers), trimethylphenyl (including
all substitution isomers), butylphenyl (including all branched
isomers, substitution isomers), methylpropylphenyl (including all
branched isomers, substitution isomers), diethylphenyl (including
all substitution isomers), dimethylethylphenyl (including all
substitution isomers), pentylphenyl (including all branched
isomers, substitution isomers), hexylphenyl (including all branched
isomers, substitution isomers), heptylphenyl (including all
branched isomers, substitution isomers), octylphenyl (including all
branched isomers, substitution isomers), nonylphenyl (including all
branched isomers, substitution isomers), decylphenyl (including all
branched isomers, substitution isomers), undecylphenyl (including
all branched isomers, substitution isomers), dodecylphenyl
(including all branched isomers, substitution isomers),
tridecylphenyl (including all branched isomers, substitution
isomers), tetradecylphenyl (including all branched isomers,
substitution isomers), pentadecylphenyl (including all branched
isomers, substitution isomers), hexadecylphenyl (including all
branched isomers, substitution isomers), heptadecylphenyl
(including all branched isomers, substitution isomers) and
octadecylphenyl (including all branched isomers, substitution
isomers).
[0068] As examples of the aforementioned arylalkyl groups there may
be mentioned benzyl, phenethyl, phenylpropyl (including all
branched isomers) and phenylbutyl (including all branched
isomers).
[0069] As compounds represented by general formula (16) and (17)
there may be mentioned, specifically, molybdenum phosphate,
molybdenum thiophosphate, molybdenum dithiophosphate and molybdenum
dithiocarbamate.
[0070] The phosphoric acid or thiophosphoric acid ester derivatives
represented by general formula (16) above and the dithiocarbamic
acid ester derivatives represented by general formula (17) above
are usually compounds obtained by reacting phosphoric acid esters,
thiophosphoric acid esters or dithiocarbamic acid esters with
inorganic molybdenum compounds (molybdenum trioxide, molbdenic acid
or its salts, etc.), and if necessary together with a sulfur
source.
[0071] Molybdenum can take different valence states, and therefore
the compounds obtained by the aforementioned reaction will usually
be mixtures. The most typical compounds are those represented by
the following formulas (18) and (19). ##STR11##
[0072] According to the invention, the organic molybdenum compound
used may be any one of the compounds represented by general
formulas (16) and (17) above, or a mixture thereof, but from the
standpoint of thermal stability it is preferably a compound
represented by general formula (16). Addition of a compound
represented by general formula (16) can provide excellent thermal
stability particularly when the grease composition of the invention
is used as bearing grease.
[0073] The proportion of the organic molybdenum compound added is
preferably at least 0.1 wt % and more preferably at least 0.5 wt %
based on the total composition. If the proportion is less than 0.1
wt %, the addition of the organic molybdenum compound will tend to
yield no further friction-reducing effect. The proportion of the
organic molybdenum compound added is also preferably no greater
than 20 wt % and more preferably no greater than 10 wt % based on
the total composition. If the proportion is greater than 20 wt %,
there will tend to be no commensurate improvement in the
friction-reducing effect.
[0074] The grease composition of the invention may also contain, if
necessary, solid lubricants, extreme pressure agents, antioxidants,
oil agents, rust inhibitors, viscosity index improvers and the like
to further enhance the performance, in a range which does not
impair the properties.
[0075] As specific solid lubricants there may be mentioned
graphite, graphite fluoride, polytetrafluoroethylene, molybdenum
disulfide, antimony sulfide, alkali (alkaline earth) metal borates
and the like.
[0076] As specific extreme pressure agents there may be mentioned
organic zinc compounds such as zinc dialkyldithiophosphates, zinc
diaryldithiophosphates, zinc dialkyldithiocarbamates and zinc
diaryldithiocarbamates, and sulfur-containing compounds such as
dihydrocarbyl polysulfide, sulfidized esters, thiazole compounds
and thiadiazole compounds.
[0077] 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 dialkyldiphenylamines,
phenyl-.alpha.-naphthylamine and
p-alkylphenyl-.alpha.-naphthylamines; sulfur-based compounds; and
phenothiazine-based compounds.
[0078] As specific oil agents there may be mentioned amines such as
laurylamine, dimyristylamine, palmitylamine, stearylamine and
oleylamine; higher alcohols such as lauryl alcohol, myristyl
alcohol, palmityl alcohol, stearyl alcohol and oleyl alcohol;
higher fatty acids such as lauric acid, myristic acid, palmitic
acid, stearic acid and oleic acid; fatty acid esters such as methyl
laurate, methyl myristate, methyl palmitate, methyl palmitate,
methyl stearate and methyl oleate; amides such as lauryl amide,
myristyl amide, palmityl amide, stearyl amide and oleyl amide; fats
and oils, and the like.
[0079] As specific rust inhibitors there may be mentioned metal
soaps; polyhydric alcohol partial esters such as sorbitan fatty
acid esters; amines; phosphoric acid; phosphoric acid salts, and
the like.
[0080] As specific viscosity index improvers there may be mentioned
polymethacrylates, polyisobutylene, polystyrene, and the like.
[0081] The grease composition of the invention may be obtained, for
example, by adding component (A), component (B) and an organic
molybdenum compound or other additives to a lubricating base oil,
stirring the mixture, and passing it through a roll mill or the
like. The grease composition of the invention may also be obtained
by preadding the raw material of component (A) to the lubricating
base oil and melting the mixture, stirring and mixing it to prepare
component (A) in the lubricating base oil, and then further adding
component (B) and an organic molybdenum compound or other
additives, stirring the mixture and passing it through a roll mill
or the like.
[0082] The grease composition of the invention having the
composition described above exhibits a sufficiently high
friction-reducing effect, and the friction-reducing effect is
maintained at a high level at high temperature. It is therefore
highly useful as a gear grease for constant velocity gears and
transmission gears, as a bearing grease for ball bearings and
roller bearings, and as an iron-manufacturing plant grease, and is
particularly preferred as a grease for constant velocity joints,
non-stage transmission bearings, and both automotive and railroad
bearings.
EXAMPLES
[0083] The present invention will now be explained in greater
detail through examples and comparative examples, with the
understanding that these examples are in no way limitative on the
invention.
Examples 1-12, Comparative Examples 1-24
[0084] Grease compositions were prepared according to the procedure
described below, using a poly-.alpha.-olefin (dynamic viscosity at
40.degree. C.: 48 mm.sup.2/s) in Examples 1-3, Comparative Examples
1-3 and Comparative Examples 13-15, and a mineral oil (dynamic
viscosity at 40.degree. C.: 100 mm.sup.2/s) in Examples 4-12,
Comparative Examples 4-12 and Comparative Examples 16-24, as the
lubricating base oil.
[0085] In Examples 1-9, Comparative Examples 1-9 and Comparative
Examples 13-21, diphenylmethane 4,4'-diisocyanate (MDI) was added
to the lubricating base oil and heated to prepare a solution while
cyclohexylamine or additionally stearyl alcohol was added to the
lubricating base oil and heated to prepare a solution, and the two
solutions were combined so that the MDI, cyclohexylamine and
stearyl alcohol were in the molar ratios shown in Tables 1-4. The
additives listed below were then added to the produced gel-like
substance in the contents shown in Tables 1-4, and the mixture was
stirred and passed through a roll mill to obtain the desired grease
composition.
[0086] In Examples 10-12, Comparative Examples 10-12 and
Comparative Examples 22-24, lithium 12-hydroxystearate was added to
the lubricating base oil and heated to prepare a solution, and
after cooling, the additives listed below were added in the
contents shown in Tables 2-4. The mixture was then stirred and
passed through a roll mill to obtain the desired grease
composition.
Additives
ZnP: Zinc di(n-butyl)phosphate (phosphorus content: 13.2 wt %,
sulfur content: 0%, zinc content: 13.0 wt %)
MODTC: Molybdenum dioctyldithiocarbamate
MoDTP: Molybdenum dioctyldithiophosphate
ZnDTP: Zinc dipentyldithiophosphate
[0087] [Friction Test]
[0088] The grease compositions of Examples 1-12 and Comparative
Examples 1-24 were used for a friction test in the following
manner.
[0089] FIGS. 1A and 1B are a perspective view and top view,
respectively, of a test strip used for the friction test. As shown
in these drawings, 1 g of the grease composition was filled into a
needle holder 2 (14 mm.times.10 mm.times.2.5 mm) formed at the
center of a lower disk 1 (.phi.24 mm.times.7.9 mm), and then three
needles (.phi.3 mm.times.13.8 mm) were placed in the needle holder
2 and an upper disk 4 (.phi.20 mm.times.13 mm) was situated
thereover. Each of the test strips was set in an SRV friction
testing machine in such a manner as to form an angle .theta. [deg]
(the needle set angle) of 30 deg between line 1.sub.1 perpendicular
to the sliding direction of the upper disk 4 through the center O
on the upper surface of the lower disk 1 and line 1.sub.2 parallel
to the lengthwise direction of the needle 3 through the center O.
The two temperature conditions 80.degree. C. and 150.degree. C.
were used in the testing machine, and the friction test was carried
out at a frequency of 40 Hz, an amplitude of 3 mm and a load of
1000 N. The friction coefficients at 10 minutes after start of the
test are shown in Tables 1-4. TABLE-US-00001 TABLE 1 Example 1
Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example
8 Example 9 Thickener Raw MDI 1 1 1 1 1 1 5 5 5 material
Cyclohexylamine 2 2 2 2 2 2 8 8 8 ratio Stearyl alcohol -- -- -- --
-- -- 2 2 2 [mol] Lithium 12-hydroxystearate -- -- -- -- -- -- --
-- -- Content [wt %] 15 15 15 15 15 15 8 8 8 Base oil Mineral oil
[wt %] -- -- -- 83 81 81 90 88 88 PAO [wt %] 83 81 81 -- -- -- --
-- Additives ZnP [wt %] 2 2 2 2 2 2 2 2 2 MoDTC [wt %] -- 2 -- -- 2
-- -- 2 -- MoDTP [wt %] -- -- 2 -- -- 2 -- -- 2 Friction Friction
80.degree. C. 0.055 0.045 0.040 0.055 0.045 0.040 0.055 0.045 0.040
test coefficient 150.degree. C. 0.055 0.045 0.045 0.055 0.045 0.045
0.055 0.045 0.045
[0090] TABLE-US-00002 TABLE 2 Example Example Example Comp. Comp.
Comp. Comp. Comp. Comp. 10 11 12 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex.
6 Thickener Raw MDI -- -- -- 1 1 1 1 1 1 material Cyclohexylamine
-- -- -- 2 2 2 2 2 2 ratio Stearyl alcohol -- -- -- -- -- -- -- --
-- [mol] Lithium 12-hydroxystearate used used used -- -- -- -- --
-- Content [wt %] 10 10 10 15 15 15 15 15 15 Base oil Mineral oil
[wt %] 88 86 86 -- -- -- 85 83 83 PAO [wt %] -- -- -- 85 83 83 --
-- -- Additives ZnP [wt %] 2 2 2 -- -- -- -- -- -- MoDTC [wt %] --
2 -- -- 2 -- -- 2 -- MoDTP [wt %] -- -- 2 -- -- 2 -- -- 2 Friction
Friction 80.degree. C. 0.055 0.045 0.040 0.180 0.050 0.055 0.190
0.050 0.055 test coefficient 150.degree. C. 0.055 0.045 0.045 0.230
0.120 0.160 0.230 0.120 0.160
[0091] TABLE-US-00003 TABLE 3 Comp. Comp. Comp. Comp. Comp. Comp.
Comp. Comp. Comp. Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex.
14 Ex. 15 Thickener Raw MDI 5 5 5 -- -- -- 1 1 1 material
Cyclohexylamine 8 8 8 -- -- -- 2 2 2 ratio Stearyl alcohol 2 2 2 --
-- -- -- -- -- [mol] Lithium 12-hydroxystearate -- -- -- used used
used -- -- -- Content [wt %] 8 8 8 10 10 10 15 15 15 Base oil
Mineral oil [wt %] 92 90 90 90 88 88 -- -- -- PAO [wt %] -- -- --
-- -- -- 83 81 81 Additives ZnP [wt %] -- -- -- -- -- -- -- -- --
MoDTC [wt %] -- 2 -- -- 2 -- -- 2 -- MoDTP [wt %] -- -- 2 -- -- 2
-- -- 2 ZnDTP [wt %] -- -- -- -- -- -- 2 2 2 Friction Friction
80.degree. C. 0.185 0.050 0.055 0.180 0.055 0.055 0.050 0.045 0.040
test coefficient 150.degree. C. 0.235 0.130 0.165 0.225 0.125 0.230
0.195 0.090 0.130
[0092] TABLE-US-00004 TABLE 4 Comp. Comp. Comp. Comp. Comp. Comp.
Comp. Comp. Comp. Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21 Ex. 22
Ex. 23 Ex. 24 Thickener Raw MDI 1 1 1 5 5 5 -- -- -- material
Cyclohexylamine 2 2 2 8 8 8 -- -- -- ratio Stearyl alcohol -- -- --
2 2 2 -- -- -- [mol] Lithium 12-hydroxystearate -- -- -- -- -- --
used used used Content [wt %] 15 15 15 8 8 8 10 10 10 Base oil
Mineral oil [wt %] 83 81 81 90 88 88 88 86 86 PAO [wt %] -- -- --
-- -- -- -- -- -- Additives ZnP [wt %] -- -- -- -- -- -- -- -- --
MoDTC [wt %] -- 2 -- -- 2 -- -- 2 -- MoDTP [wt %] -- -- 2 -- -- 2
-- -- 2 ZnDTP [wt %] 2 2 2 2 2 2 2 2 2 Friction Friction 80.degree.
C. 0.050 0.045 0.040 0.050 0.045 0.040 0.050 0.045 0.040 test
coefficient 150.degree. C 0.190 0.085 0.130 0.185 0.090 0.135 0.190
0.085 0.135
[0093] Tables 1 and 2 show that when the grease compositions of
Examples 1-12 were used, a high friction-reducing effect was
achieved as indicated by sufficiently low friction coefficients
under both temperature conditions of 80.degree. C. and 150.degree.
C. When the grease compositions of Examples 2, 3, 5, 6, 8, 9, 11
and 12 were used, which further contained an organic molybdenum
compound, it was possible to further increase the friction-reducing
effect.
[0094] When the grease compositions of Comparative Examples 1-24
were used, however, the friction coefficient was low especially at
150.degree. C., and therefore the friction property was inadequate
at high temperature.
INDUSTRIAL APPLICABILITY
[0095] As explained above, the present invention provides a grease
composition exhibiting a sufficiently high friction-reducing
effect, and the friction-reducing effect is maintained at a high
level at high temperature. Thus, even with increased speeds and
lighter weights of mechanical parts such as constant velocity
gears, or the use of such mechanical parts at high temperatures, it
is possible to prevent heat generation and wear due to friction
between metals, to achieve satisfactorily lengthening of the usable
life of the grease and mechanical parts.
* * * * *