U.S. patent application number 14/007120 was filed with the patent office on 2014-01-16 for lubricating oil composition.
This patent application is currently assigned to JX NIPPON OIL & ENERGY CORPORATION. The applicant listed for this patent is Noriko Abe, Yasushi Onumata. Invention is credited to Noriko Abe, Yasushi Onumata.
Application Number | 20140018271 14/007120 |
Document ID | / |
Family ID | 46929864 |
Filed Date | 2014-01-16 |
United States Patent
Application |
20140018271 |
Kind Code |
A1 |
Onumata; Yasushi ; et
al. |
January 16, 2014 |
LUBRICATING OIL COMPOSITION
Abstract
The present invention provides a lubricating oil composition
that maintains properties necessary to lubricating a transmission
and other devices and has more excellent insulation properties and
anti-wear properties and more improved anti-seizure properties than
the prior art and comprises (A) a lubricating oil base oil; (B) at
least one type of phosphorus compound selected from the group
consisting of phosphorus compounds having at least one hydroxyl
group and/or at least one thiol group; and (C) an ashless
dispersant having a functional group containing as a dispersion
group in an amount of less than 0.001 percent by mass on the basis
of nitrogen on the total composition mass basis or no such an
ashless dispersant at all, the composition having a 80.degree. C.
volume resistivity of 5.times.10.sup.8 .OMEGA.m or greater.
Inventors: |
Onumata; Yasushi;
(Chiyoda-ku, JP) ; Abe; Noriko; (Chiyoda-ku,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Onumata; Yasushi
Abe; Noriko |
Chiyoda-ku
Chiyoda-ku |
|
JP
JP |
|
|
Assignee: |
JX NIPPON OIL & ENERGY
CORPORATION
Chiyoda-ku, Tokyo
JP
|
Family ID: |
46929864 |
Appl. No.: |
14/007120 |
Filed: |
September 13, 2011 |
PCT Filed: |
September 13, 2011 |
PCT NO: |
PCT/JP2011/070814 |
371 Date: |
September 24, 2013 |
Current U.S.
Class: |
508/433 ;
508/441 |
Current CPC
Class: |
C10N 2010/04 20130101;
C10M 141/10 20130101; C10M 2223/06 20130101; C10M 2209/084
20130101; C10M 2223/043 20130101; C10M 2223/047 20130101; C10M
2207/2825 20130101; C10N 2040/04 20130101; C10M 2223/049 20130101;
C10M 137/02 20130101; C10N 2030/06 20130101; C10M 2223/02 20130101;
C10M 2215/08 20130101; C10N 2030/40 20200501; C10M 137/00 20130101;
C10N 2020/02 20130101; C10M 2215/28 20130101; C10M 2203/1025
20130101; C10M 2223/04 20130101; C10N 2040/16 20130101; C10M
2215/28 20130101; C10N 2020/04 20130101; C10N 2060/14 20130101;
C10M 2215/28 20130101; C10N 2020/04 20130101; C10M 2215/28
20130101; C10N 2020/04 20130101; C10M 2215/28 20130101; C10N
2020/04 20130101; C10N 2060/14 20130101 |
Class at
Publication: |
508/433 ;
508/441 |
International
Class: |
C10M 137/02 20060101
C10M137/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2011 |
JP |
2011-072464 |
Claims
1. A lubricating oil composition comprising: (A) a lubricating oil
base oil; (B) at least one type of phosphorus compound selected
from the group consisting of phosphorus compounds having at least
one hydroxyl group and/or at least one thiol group; and (C) an
ashless dispersant having a functional group containing as a
dispersion group in an amount of less than 0.001 percent by mass on
the basis of nitrogen on the total composition mass basis or no
such an ashless dispersant at all, the composition having a
80.degree. C. volume resistivity of
5.times.10.sup.8.OMEGA..quadrature.m or greater.
2. The lubricating oil composition according to claim 1, wherein
(B) the phosphorus compound having a hydrocarbon group having 16 or
fewer carbon atoms.
3. The lubricating oil composition according to claim 1, wherein
the composition is used for the transmission, both transmission and
electric motor, or the device in which a lubricating system is
shared by the transmission and electric motor, mounted in a fuel
cell electric vehicle, an electric vehicle or a hybrid vehicle.
4. The lubricating oil composition according to claim 2, wherein
the composition is used for the transmission, both transmission and
electric motor, or the device in which a lubricating system is
shared by the transmission and electric motor, mounted in a fuel
cell electric vehicle, an electric vehicle or a hybrid vehicle.
Description
TECHNICAL FIELD
[0001] The present invention relates to lubricating oil
compositions with excellent insulation properties and
lubricity.
BACKGROUND ART
[0002] A variety of electronic control devices have been used in
the mechanisms of an automobile. Some of them may be used in
lubricating oil and thus the insulation properties thereof have
become important. In particular, lubricating oils for the
transmission, both the transmission and electric motor, or the
device in which a lubricating system is shared by the transmission
and electric motor, mounted in a fuel cell electric vehicle, an
electric vehicle or a hybrid vehicle have been required to have
higher insulation properties because these devices operate using a
high electric voltage. Furthermore, in recent years, the
transmission has been required to be improved in power transmission
efficiency and down-sized as well as weight-reduced so as to
improve fuel efficiency and thus has been applied with a higher
load. The lubricating oil has, therefore, been demanded to have
insulation properties as well as more improved anti-wear properties
and anti-seizure properties.
[0003] In addition to the above-described properties, the
lubricating oil for transmissions are required to have friction
characteristics conforming with the characteristics of a clutch,
viscosity characteristics ranging from low temperatures to high
temperatures so that an appropriate hydraulic pressure control can
be achieved, i.e., viscosity retention which is not affected on
temperature as much as possible, and oxidation stability and
detergent dispersibility to keep the device clean so that the
control device thereof can operate appropriately. Furthermore,
these characteristics are generally needed to be retained during
the working life of the device. For this purpose, a variety of
additives are used in a transmission lubricating oil.
[0004] So far, as such transmission lubricating oils, some oils
have been proposed such as an automobile transmission oil
composition comprising a base oil selected from mineral oils,
synthetic oils and mixtures thereof and a phosphorus compound
selected from hydrocarbon group-containing zinc dithiophosphate,
triaryl phosphate, triaryl thiophosphate and a mixture thereof in
an amount of 0.1 to 15.0 percent by mass on the total mass
composition basis and having a 80.degree. C. volume resistivity of
1.times.10.sup.7 .OMEGA.m or greater (Patent Literature 1) and a
transmission oil composition comprising a base oil selected from
mineral oils, poly-.alpha.-olefins and hydrogenated compounds
thereof, alkylbenzenes, ester-based compounds and mixtures thereof
and having a 80.degree. C. kinematic viscosity of 1.5 to 4.0
mm.sup.2/s, a phosphorus compound selected from hydrocarbon
group-containing zinc dithiophosphate, triaryl thiophosphates and
mixtures thereof in an amount of 0.1 to 4.0 percent by mass on the
total composition mass basis, and an ashless dispersant and having
a 80.degree. C. volume resistivity of 1.times.10.sup.8 .OMEGA.m or
greater (Patent Literature 2).
CITATION LIST
Patent Literature
[0005] Patent Literature 1: WO2002/097017 [0006] Patent Literature
2: Japanese Patent Application Publication 2008-285682
SUMMARY OF INVENTION
Technical Problem
[0007] As described above, a variety of additives are used in a
transmission oil but would alone or in combination degrade the
insulation properties, anti-wear properties or anti-seizure
properties. The present invention aims at providing a lubricating
oil composition maintaining properties necessary for a transmission
and having more excellent insulation properties and anti-wear
properties and more improved anti-seizure properties than the prior
art.
Solution to Problem
[0008] That is, the present invention relates to a lubricating oil
composition comprising: (A) a lubricating oil base oil; (B) at
least one type of phosphorus compound selected from the group
consisting of phosphorus compounds having at least one hydroxyl
group and/or at least one thiol group; and (C) an ashless
dispersant having a functional group containing as a dispersion
group in an amount of less than 0.001 percent by mass on the basis
of nitrogen on the total composition mass basis or no such an
ashless dispersant at all, the composition having a 80.degree. C.
volume resistivity of 5.times.10.sup.8 .OMEGA.m or greater.
[0009] The present invention also relates to the above-described
lubricating oil composition wherein (B) the phosphorus compound
having a hydrocarbon group having 16 or fewer carbon atoms.
[0010] The present invention also relates to the above-described
lubricating oil composition used for the transmission, both
transmission and electric motor, or the device in which a
lubricating system is shared by the transmission and electric
motor, mounted in a fuel cell electric vehicle, an electric vehicle
or a hybrid vehicle.
Advantageous Effects of the Invention
[0011] The lubricating oil composition of the present invention
maintains properties necessary to lubricate a transmission and
other devices and has more excellent insulation properties and
anti-wear properties than the prior art and can be improved in
anti-seizure properties.
DESCRIPTION OF EMBODIMENT
[0012] The present invention will be described in more detail
below.
[0013] The lubricating base oil referred to as Component (A) used
in the present invention may be a mineral base oil and/or a
synthetic base oil or alternatively a mixture of two or more types
of mineral oils or synthetic base oils, or a mixture of a mineral
base oil and a synthetic base oil. The mix ratio in these mixtures
may be selected arbitrarily.
[0014] Examples of the mineral lubricating base oil which may be
used in the present invention include paraffinic or naphthenic
mineral base oils which can be produced by subjecting a lubricating
oil fraction produced by atmospheric- or vacuum-distillation of a
crude oil, to any one of or any suitable combination of refining
processes selected from solvent deasphalting, solvent extraction,
hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining,
sulfuric acid treatment, and clay treatment; n-paraffins; and
iso-paraffins. These base oils may be used alone or in combination
at an arbitrary ratio.
[0015] Examples of preferred mineral lubricating base oils include
the following base oils:
[0016] (1) a distillate oil produced by atmospheric distillation of
a paraffin base crude oil and/or a mixed base crude oil;
[0017] (2) a whole vacuum gas oil (WVGO) produced by vacuum
distillation of the topped crude of a paraffin base crude oil
and/or a mixed base crude oil;
[0018] (3) a wax produced by a lubricating oil dewaxing process
and/or a Fischer-Tropsch wax produced by a GTL process;
[0019] (4) an oil produced by mild-hydrocracking (MHC) one or more
oils selected from oils of (1) to (3) above;
[0020] (5) a mixed oil of two or more oils selected from (1) to (4)
above;
[0021] (6) a deasphalted oil (DAO) produced by deasphalting an oil
of (1), (2) (3), (4) or (5);
[0022] (7) an oil produced by mild-hydrocracking (MHC) an oil of
(6); and
[0023] (8) a lubricating oil produced by subjecting a mixed oil of
two or more oils selected from (1) to (7) used as a feed stock
and/or a lubricating oil fraction recovered therefrom to a normal
refining process and further recovering a lubricating oil fraction
from the refined product.
[0024] No particular limitation is imposed on the normal refining
process used herein. Therefore, there may be used any refining
process having been conventionally used upon production of a
lubricating base oil. Examples of the normal refining process
include (a) hydro-refining processes such as hydrocracking and
hydrofinishing, (b) solvent refining such as furfural extraction,
(c) dewaxing such as solvent dewaxing and catalytic dewaxing, (d)
clay refining with acidic clay or active clay and (e) chemical
(acid or alkali) refining such as sulfuric acid treatment and
sodium hydroxide treatment. In the present invention, any one or
more of these refining processes may be used in any combination and
order.
[0025] The mineral lubricating base oil used in the present
invention is particularly preferably a base oil produced by further
subjecting a base oil selected from (1) to (8) described above to
the following treatments.
[0026] That is, preferred are a hydrocracked mineral oil and/or
wax-isomerized isoparaffinic base oil produced by hydrocracking or
wax-isomerizing a base oil selected from (1) to (8) described above
as it is or a lubricating fraction recovered therefrom and
subjecting the resulting product as it is or a lubricating fraction
recovered therefrom to dewaxing such as solvent dewaxing or
catalytic dewaxing, followed by solvent refining or followed by
solvent refining and then dewaxing such as solvent dewaxing or
catalytic dewaxing. The hydrocracked mineral oil and/or
wax-isomerized isoparaffinic base oil are used in an amount of
preferably 30 percent by mass or more, more preferably 50 percent
by mass or more, and particularly preferably 70 percent by mass or
more, on the total base oil mass basis.
[0027] The lubricating base oil referred to as Component (A) used
in the transmission lubricating oil composition of the present
invention is a lubricating base oil adjusted so that the
100.degree. C. kinematic viscosity is from 1.5 to 4.5
mm.sup.2/s.
[0028] Component (A) is preferably one or more types selected from
the following (A-a) to (A-c):
[0029] (A-a) a mineral base oil having a 100.degree. C. kinematic
viscosity of between 1.5 and lower than 3.5 mm.sup.2/s, preferably
1.9 to 3.2 mm.sup.2/s;
[0030] (A-b) a mineral base oil having a 100.degree. C. kinematic
viscosity of between 3.5 and lower than 7 mm.sup.2/s, preferably
3.6 to 4.5 mm.sup.2/s; and
[0031] (A-c) a synthetic base oil having a 100.degree. C. kinematic
viscosity of between 1.5 and lower than 7 mm.sup.2/s, preferably
3.8 to 4.5 mm.sup.2/s.
[0032] Mineral base oils (A-a) to (A-b) have a % C.sub.A of
preferably 2 or less, more preferably 1 or less, more preferably
0.5 or less, particularly preferably substantially 0. Lubricating
oil (A-c) has a % C.sub.A of substantially 0. The use of
lubricating base oil (A) having a % C.sub.A of 2 or less renders it
possible to produce a lubricating oil composition with an excellent
oxidation stability.
[0033] The % C.sub.A used herein denotes the percentage of the
aromatic carbon number in the total carbon number, determined in
accordance with ASTM D 3238-85.
[0034] No particular limitation is imposed on the viscosity index
of lubricating base oils (A-a) to (A-c), which is, however,
preferably 80 or greater, more preferably 100 or greater,
particularly preferably 120 or greater and usually 200 or less,
preferably 160 or less. The use of a lubricating base oil having a
viscosity index of greater than 80 renders it possible to produce a
composition exhibiting excellent viscosity characteristics from low
temperatures to high temperatures. The use of a lubricating base
oil having a too high viscosity index results in a too much normal
paraffins in the resulting composition and also deteriorates the
low temperature fluidity thereof.
[0035] No particular limitation is imposed on the sulfur content of
mineral base oils (A-a) to (A-b) used in the present invention,
which is, however, preferably 0.05 percent by mass or less, more
preferably 0.02 percent by mass or less, particularly preferably
0.005 percent by mass or less. The sulfur content of lubricating
base oil (A-c) is substantially 0%. Reduction of the sulfur content
of Component (A) renders it possible to produce a composition
having a more excellent oxidation stability.
[0036] In the present invention, any one or more of the
above-described base oils (A-a) to (A-c) may be used. Above all,
preferably (A-a) and (A-b) and/or (A-c) are used in combination.
When Component (A-a) and/or Component (A-b) and Component (A-c) are
used in combination, the content of Component (A-c) is preferably 1
to 50 percent by mass, more preferably 3 to 20 percent by mass,
more preferably 3 to 10 percent by mass on the total base oil mass
basis. In particular, blending of Component (A-c) in an amount of
on the order of 3 to 10 percent by mass renders it possible to
produce a composition exhibiting excellent effects in fatigue life,
low temperature characteristics, and oxidation stability at a low
cost.
[0037] Lubricating base oil (A) used in the present invention has a
100.degree. C. kinematic viscosity of preferably 1.5 to 4.5
mm.sup.2/s, more preferably 2.8 to 4.0 mm.sup.2/s, particularly
preferably 3.6 to 3.9 mm.sup.2/s. The use of a lubricating base oil
with a 100.degree. C. kinematic viscosity of 4.5 mm.sup.2/s or
lower renders it possible to produce a lubricating oil composition
having a smaller frictional resistance at lubricating sites because
of its small fluid resistance and thus having excellent low
temperature viscosity (for example, the -40.degree. C. Brookfield
viscosity is 20,000 Pas or less). The use of a lubricating base oil
with a 100.degree. C. kinematic viscosity of 1.5 mm.sup.2/s or
higher renders it possible to produce a lubricating oil composition
which is sufficient in oil film formation and thus more excellent
in lubricity and less in evaporation loss of the base oil under
elevated temperature conditions.
[0038] The synthetic oil referred to as (A-c) may be a synthetic
lubricating oil such as poly-.alpha.-olefins (1-octene oligomer,
1-decene oligomer, ethylene-propylene cooligomer) and hydrogenated
compounds thereof; isobutene oligomers and hydrogenated compounds
thereof; isoparaffins; alkylbenzenes; alkylnaphthalenes;
alkyldiphenyl ethanes; monoisopropyl biphenyl; dimethyl silicone;
diesters (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl
adipate, ditridecyl adipate and di-2-ethylhexyl sebacate); polyol
esters (trimethylolpropane caprylate, trimethylolpropane
pelargonate, pentaerythritol 2-ethylhexanoate and pentaerythritol
pelargonate); polyoxyalkylene glycols; dialkyldiphenyl ethers;
polyphenyl ethers; or a mixture thereof. Among these oils,
preferably used are poly-.alpha.-olefins and hydrogenated compounds
thereof; isobutene oligomers and hydrogenated compounds thereof;
isoparaffins; alkylbenzenes; alkylnaphthalenes;
alkyldiphenylethane; monoisopropyl biphenyl; and dimethyl silicone
because they have a 80.degree. C. volume resistivity of
1.times.10.sup.13 .OMEGA.m or greater and thus can enhance the
insulation properties of the resulting lubricating oil composition.
In general, ester-based compounds have a 80.degree. C. volume
resistivity of on the order of 1.times.10.sup.9 to
1.times.10.sup.13 .OMEGA.m and are preferably those from which the
remaining moisture and impurities have been sufficiently
removed.
[0039] The term "80.degree. C. volume resistivity" used herein is
measured in accordance with JIS C 2101 24. (volume resistivity
test).
[0040] The synthetic oil used in the present invention is
preferably selected from poly-.alpha.-olefins and hydrogenated
compounds thereof, alkylbenzenes, ester-based compounds and
mixtures thereof. In this case, the resulting composition can
maintain low temperature fluidity and low volatility in
well-balance under the conditions where it is used.
[0041] Typical examples of poly-.alpha.-olefins include oligomers
or cooligomers of .alpha.-olefins having 2 to 32, preferably 6 to
16 carbon atoms, such as 1-octene oligomer, 1-decene oligomer,
ethylene-propylene cooligomer, and hydrogenated compounds
thereof.
[0042] These synthetic oils may be used alone. No particular
limitation is imposed on the viscosity thereof. However, synthetic
oils with different viscosities may be used in combination so that
the 100.degree. C. kinematic viscosity is adjusted to preferably
from 1.5 to 4.5 mm.sup.2/s. This is because the combination of a
synthetic oil having a high viscosity with that of a low viscosity
results in a base oil having a higher viscosity index.
[0043] The lubricating oil base oil referred to as Component (A) in
the present invention is as described above but is preferably mixed
with a solvent refined base oil having a kinematic viscosity of 20
mm.sup.2/s to 50 mm.sup.2/s if the resulting composition has a
problem in fatigue life. Furthermore, it is preferably mixed with
such a solvent refined oil in such an extent that the mixture is
adjusted to have a % C.sub.A of 2 or less and a 100.degree. C.
kinematic viscosity of 1.5 to 4.5 mm.sup.2/s.
[0044] The lubricating oil composition of the present invention
contains (B) at least one type of phosphorus compound selected from
phosphorus compounds having at least one hydroxyl group and/or at
least one thiol group.
[0045] The phosphorus compound referred to as Component (B) in the
present invention is at least one type of compound selected from
phosphorus compounds represented by formula (1), phosphorus
compounds represented by formula (2), amine salts thereof, and
derivatives thereof.
##STR00001##
[0046] In formula (1), X.sup.1, X.sup.2 and X.sup.3 are each
independently oxygen or sulfur and at least one of them is
preferably oxygen, at least one of R.sup.1, R.sup.2 and R.sup.3 is
hydrogen and the others are hydrocarbon groups having 1 to 30
carbon atoms.
##STR00002##
[0047] In formula (2), X.sup.4, X.sup.5, X.sup.6 and X.sup.7 are
each independently oxygen or sulfur (one or two of X.sup.4, X.sup.5
and X.sup.6 may be a single bond or (poly) oxyalkylene group) and
at least one of them is preferably oxygen, at least one of R.sup.4,
R.sup.5 and R.sup.6 is hydrogen and the others are hydrocarbon
groups having 1 to 30 carbon atoms.
[0048] Examples of the hydrocarbon groups having 1 to 30 carbon
atoms for R.sup.1 to R.sup.6 include alkyl, cycloalkyl, alkenyl,
alkyl-substituted cycloalkyl, aryl, alkyl-substituted aryl, and
arylalkyl groups. The hydrocarbon groups are preferably alkyl
groups having 1 to 30 carbon atoms and aryl groups having 6 to 24
carbon atoms, more preferably alkyl groups having 3 to 18 carbon
atoms, more preferably alkyl groups having 4 to 12 carbon
atoms.
[0049] Examples of phosphorus compounds represented by formula (1)
include phosphorous acid; monothiophosphorous acid;
dithiophosphorous acid; phosphorous acid monoesters,
monothiophosphorous acid monoesters, dithiophosphorous acid
monoesters, and trithiophosphorous acid monoesters, each having any
one of the above-described hydrocarbon groups having 1 to 30 carbon
atoms; and phosphorous acid diesters, monothiophosphorous acid
diesters, dithiophosphorous acid diesters, and trithiophosphorous
acid diesters, each having any two of the above-described
hydrocarbon groups having 1 to 30 carbon atoms; and a mixture
thereof.
[0050] In order to further enhance the properties such as high
temperature detergency and oxidation stability in the present
invention, preferably two or more, particularly preferably all of
X.sup.1 to X.sup.3 in formula (1) are oxygen.
[0051] Examples of phosphorus compounds represented by formula (2)
include phosphoric acid; monothiophosphoric acid; dithiophosphoric
acid; trithiophosphoric acid; tetrathiophosphoric acid; phosphoric
acid monoesters, monothiophosphoric acid monoesters,
dithiophosphoric acid monoesters, trithiophosphoric acid
monoesters, and tetrathiophosphoric acid monoesters, each having
any one of the above-described hydrocarbon groups having 1 to 30
carbon atoms; phosphoric acid diesters, monothiophosphoric acid
diesters, dithiophosphoric acid diesters, trithiophosphoric acid
diesters, and tetrathiophosphoric acid diesters, each having any
two of the above-described hydrocarbon groups having 1 to 30 carbon
atoms; phosphonic acid, phosphonic acid monoesters, and phosphonic
acid diesters, each having any one or two of the above-described
hydrocarbon groups having 1 to 30 carbon atoms; the phosphoric acid
compounds exemplified above but having a (poly)oxyalkylene group
having 1 to 4 carbon atoms; derivatives of the phosphorus compounds
exemplified above, such as .beta.-dithiophosphorylated propionic
acid and reaction products of dithiophosphates and olefin
cyclopentadiene or (methyl)methacrylates; and mixtures thereof.
[0052] In order to further enhance the properties such as high
temperature detergency and oxidation stability in the present
invention, preferably two or more, more preferably three or more,
particularly preferably all of X.sup.4 to X.sup.7 in formula (2)
are oxygen. One or two of X.sup.4, X.sup.5 and X.sup.6 may be a
single bond or a (poly)oxyalkylene group.
[0053] Examples of the salts of phosphorus compounds represented by
formula (1) or (2) include salts produced by allowing a nitrogen
compound such as ammonia or an amine compound having in its
molecules only a hydrocarbon group having 1 to 30 carbon atoms or a
hydroxyl group-containing hydrocarbon group having 1 to 30 carbon
atoms to react with a phosphorus compound and neutralize the whole
or part of the remaining acid hydrogen.
[0054] Specific examples of the nitrogen-containing compound
include ammonia, monoamines, diamines, and polyamines. Preferred
examples include aliphatic amines having an alkyl or alkenyl group
having 10 to 20 carbon atoms, which may be straight-chain or
branched, such as decylamine, dodecylamine, dimethyldodecylamine,
tridecylamine, heptadecylamine, octadecylamine, oleylamine, and
stearyl amine.
[0055] The phosphorus compound referred to as Component (B) is
preferably at least one type of compound selected from the group
consisting of amine salts of phosphorus compounds of formula (1)
wherein all of X', X.sup.2 and X.sup.3 are oxygen and amine salts
of phosphorus compounds of formula (2) wherein all of X.sup.4,
X.sup.5, X.sup.6 and X.sup.7 are oxygen (one or two of X.sup.4,
X.sup.5 and X.sup.6 may be a single bond or a (poly)oxyalkylene
group) because they are excellent in oxidation stability.
[0056] Alternatively, the phosphorus compound referred to as
Component (B) is preferably a phosphorus compound of formula (2)
wherein all of X.sup.4, X.sup.5, X.sup.6 and X.sup.7 are oxygen
(one or two of X.sup.4, X.sup.5 and X.sup.6 may be a single bond or
a (poly) oxyalkylene group), at least one of R.sup.4, R.sup.5 and
R.sup.6 is hydrogen and the others are each independently a
hydrocarbon group having 1 to 30 carbon atoms in terms of oxidation
stability.
[0057] The hydrocarbon group of the phosphorus compound referred to
as Component (B) has preferably 16 or fewer carbon atoms. This is
based on the fact that fewer the carbon atoms, higher the volume
resistivity is as set forth in Table 1 below.
TABLE-US-00001 TABLE 1 Structure of phosphorus compound
Diphenylhydrogen Trialkyl phosphite Dialkylhydrogen phosphite
phosphite Dialkyl acid phosphate Structure of hydrocarbon group iC8
nC12 nC18 iC4 iC8 nC18 phenyl NC10 nC18 Garnbon number of
hydrocarbon group 8 12 18 4 8 18 8 10 18 Volume resistivity
10.sup.10 .OMEGA. m 358 315 27.9 1200 104 12.8 800 1.44 1.4 *
Phosphoric compounds were each dissolved in a base oil with the
following physical properties to compare the volume resistivity.
They were each added in an amount of 100 mass ppm by phosphorus.
Kinematic viscosity (40.degree. C.) 19.7 mm.sup.2/s, Kinematic
viscosity (100.degree. C.) 4.3 mm.sup.2/s, Viscosity index 125, %
C.sub.P 78.5, % C.sub.N 21.5, % C.sub.A 0
[0058] In Table 1, the volume resistivity designates the value
measured at an oil temperature of 80.degree. C. in accordance with
JIS C 2101 24. (volume resistivity test). In the above examples,
each of the phosphorus compound was added and dissolved in a
mineral base oil so that it is contained in an amount of 100 mass
ppm on the basis of phosphorus.
[0059] No particular limitation is imposed on the content of
Component (B) that is the above-described phosphorus compound of
the lubricating oil composition of the present invention, which is,
however, 0.01 percent by mass or more, preferably 0.02 percent by
mass or more, particularly preferably 0.03 percent by mass or more
and preferably 0.1 percent by mass or less, more preferably 0.08
percent by mass or less, particularly preferably 0.05 percent by
mass or less on the basis of phosphorus on the composition mass
basis. If the content of the phosphorus compound is less than 0.01
percent by mass on the basis of phosphorus, the resulting
composition would be less effective in anti-wear properties.
Whilst, if the content of the phosphorus compound is more than 0.01
percent by mass on the basis of phosphorus, the resulting
composition would be poor in insulation properties, degraded in
oxidation stability and enhanced in aggressivity against sealing
materials.
[0060] The lubricating oil composition of the present invention is
characterized in that it contains (C) an ashless dispersant having
a functional group containing nitrogen as a dispersion group in an
amount of less than 0.001 percent by mass on the basis of nitrogen
on the composition mass basis or does not contain such an ashless
dispersant at all.
[0061] As described above, the lubricating oil composition of the
present invention contains (B) at least one type of phosphorus
compound selected from phosphorus compounds having at least one
hydroxyl group and/or at least one thiol group. The inclusion of
the phosphorus compound enhances significantly the anti-wear
properties and anti-seizure properties of the composition. However,
this type of phosphorus compound degrades drastically the volume
resistance of the composition compared with a phosphorus compound
having no hydroxyl group and/or thiol group if an ashless
dispersant having a functional group containing nitrogen as a
dispersion group is contained. Therefore, the composition contains
necessarily (C) an ashless dispersant having a functional group
containing nitrogen as a dispersion group in an amount of less than
0.001 percent by mass on the basis of nitrogen on the composition
mass basis or does not contain such an ashless dispersant at all in
order to improve the anti-wear properties and anti-seizure
properties of the composition.
[0062] Examples of the ashless dispersant having a functional group
containing nitrogen as a dispersion group referred to as Component
(C) include succinimide, benzylamine, and polyamines, each having a
hydrocarbon group having 40 to 400 carbon atoms.
[0063] However, among these compounds, those having been modified
to have a structure wherein nitrogen cannot constitute a salt
structure together with Component (B) that is the phosphorus
compound are excluded from the examples. Fox example, compounds
wherein the amino group is acylated or modified with a boron
compound or a sulfuric compound and incapable of constituting a
salt structure with Component (B) that is the phosphorus compound
are excluded.
[0064] What is meant by "containing an ashless dispersant having a
functional group containing nitrogen as a dispersion group in an
amount of less than 0.001 percent by mass on the basis of nitrogen
on the composition mass basis" is a structure or amount wherein
even though an ashless dispersant has an amino group remained so as
to be able to constitute a salt structure with Component (B) that
is the phosphorus compound, the content thereof is such a level
that the volume resistance at 80.degree. C. of the resulting
composition is 5.times.10.sup.8 .OMEGA.m or greater. Specifically,
the ashless dispersant is contained in such an amount that nitrogen
is contained in an amount of less than 0.001 percent by mass, more
preferably less than 0.0008 percent by mass on the composition mass
basis.
[0065] No particular limitation is imposed on the use of compounds
with a structure of thiadiazole or triazole that is an amine-based
anti-oxidant or a corrosion inhibitor because it can be ignored if
the content thereof is 1 percent by mass or less.
[0066] The lubricating oil composition of the present invention has
a 80.degree. C. volume resistivity of preferably 5.times.10.sup.8
.OMEGA.m or greater, more preferably 6.times.10.sup.8 .OMEGA.m or
greater, particularly preferably 10.times.10.sup.8 .OMEGA.m or
greater. The composition having a 80.degree. C. volume resistivity
of 5.times.10.sup.8 .OMEGA.m or greater can keep the insulation
properties high not only when it is fresh but also when it is
degraded thereby avoiding an electric motor from having a trouble
such as shorting out for a long period of time.
[0067] If necessary, the lubricating oil composition of the present
invention may be blended with various additives such as viscosity
index improvers, extreme pressure additives, dispersants other than
the above-described dispersant compounds, metallic detergents,
friction modifiers, anti-oxidants, corrosion inhibitors, rust
inhibitors, demulsifiers, metal deactivators, pour point
depressants, seal swelling agents, anti-foaming agents, and dyes,
alone or in combination in order to further enhance the properties
of the composition or impart the composition with properties
required for a lubricating oil.
[0068] Examples of the viscosity index improvers include
non-dispersant or dispersant type poly(meth)acrylate;
non-dispersant or dispersant type ethylene-.alpha.-olefin
copolymers and hydrogenated compounds thereof; polyisobutylene and
hydrogenated compounds thereof; styrene-diene hydrogenated
copolymers; styrene-maleic anhydride ester copolymers;
polyalkylstyrenes; and copolymers of (meth)acrylate monomers
represented by formula (1) and unsaturated monomers such as
ethylene/propylene/styrene/maleic anhydride.
[0069] The amount of the viscosity index improver in the
lubricating oil composition of the present invention is such an
amount that the resulting composition has a 100.degree. C.
kinematic viscosity of 5 to 10 mm.sup.2/s, preferably 6 to 9
mm.sup.2/s and a viscosity index of 120 to 270, preferably 150 to
250, more preferably 170 to 220. More specifically, the amount is
15 percent by mass or less, preferably 10 percent by mass or less,
more preferably 8 percent by mass or less and 2 percent by mass or
more, preferably 4 percent by mass or more, more preferably 5
percent by mass or more on the composition mass basis. An amount of
more than 15 percent by mass causes a too high viscosity while an
amount of less than 2 percent by mass causes a too high viscosity
and thus cannot secure a sufficient composition viscosity.
[0070] Examples of the metallic detergent include those such as
alkaline earth metal sulfonates, alkaline earth metal phenates, and
alkaline earth metal salicylates.
[0071] Any one or more compounds selected from these metallic
detergents may be contained in an amount of usually 0.01 to 10
percent by mass, preferably 0.1 to 5 percent by mass on the total
composition mass basis.
[0072] The friction modifier may be any compound that has been
generally used as a friction modifier for lubricating oils.
Specific examples include amine compounds, imide compounds, fatty
acid esters, fatty acid amides, and fatty acid metal salts, each
having per molecule at least one alkyl or alkenyl group having 6 to
30 carbon atoms, particularly a straight-chain alkyl or alkenyl
group having 6 to 30 carbon atoms.
[0073] Any one or more compounds selected from these friction
modifiers may be contained in an amount of usually 0.01 to 5.0
percent by mass, preferably 0.03 to 3.0 percent by mass on the
total composition mass basis.
[0074] The anti-oxidant may be any anti-oxidant that has been
usually used in lubricating oils, such as phenol- or amine-based
compounds.
[0075] Specific examples of the anti-oxidant include alkylphenols
such as 2-6-di-tert-butyl-4-methylphenol; bisphenols such as
methylene-4,4-bisphenol(2,6-di-tert-butyl-4-methylphenol);
naphthylamines such as phenyl-.alpha.-naphthylamine;
dialkyldiphenylamines; zinc dialkyldithiophosphoric acids such as
di-2-ethylhexyldithiophosphoric acid; and esters of
(3,5-di-tert-butyl-4-hydroxyphenyl)fatty acid (propionic acid) or
(3-methyl-5-tert-butyl-4-hydroxyphenyl)fatty acid (propionic acid)
with a monohydric or polyhydric alcohol such as methanol, octanol,
octadecanol, 1,6-hexanediol, neopentyl glycol, thiodiethylene
glycol, triethylene glycol and pentaerythritol.
[0076] Any one or more of compounds selected from these compounds
may be contained in any amount, which is, however, usually from
0.01 to 5 percent by mass, preferably from 0.1 to 3 percent by mass
on the total composition mass basis.
[0077] Examples of the corrosion inhibitor include benzotriazole-,
tolyltriazole-, thiadiazole-, and imidazole-types compounds.
[0078] Examples of the rust inhibitor include petroleum sulfonates,
alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl
succinic acid esters, and polyhydric alcohol esters.
[0079] Examples of the demulsifier include polyalkylene
glycol-based non-ionic surfactants such as polyoxyethylenealkyl
ethers, polyoxyethylenealkylphenyl ethers, and
polyoxyethylenealkylnaphthyl ethers.
[0080] Examples of the metal deactivator include imidazolines,
pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles,
benzotriazoles and derivatives thereof,
1,3,4-thiadiazolepolysulfide,
1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate,
2-(alkyldithio)benzoimidazole, and
.beta.-(o-carboxybenzylthio)propionitrile.
[0081] The pour point depressant may be any of the known pour point
depressants selected depending on the type of lubricating base oil
but are preferably poly(meth)acrylates having a weight average
molecular weight of preferably 20,000 to 500,000, more preferably
50,000 to 300,000, particularly preferably 80,000 to 200,000.
[0082] The anti-foaming agent may be any compound that has been
usually used as an anti-foaming agent for lubricating oils.
Examples of such an anti-foaming agent include silicones such as
dimethylsilicone and fluorosilicone. Any one or more of compounds
selected from these compounds may be contained in any amount.
[0083] The seal swelling agent may be any compound that has been
usually used as a seal swelling agent for lubricating oils.
Examples of such a seal swelling agents include ester-, sulfur- and
aromatic-based seal swelling agents.
[0084] The dye may be any compound that has been usually used and
may be blended in any amount. The amount is usually from 0.001 to
1.0 percent by mass on the total composition mass basis.
[0085] When these additives are blended with the lubricating oil
composition of the present invention, the corrosion inhibitor, rust
inhibitor, and anti-foaming agent are each contained in an amount
of 0.005 to 5 percent by mass, the pour point depressant and metal
deactivator are each contained in an amount of 0.005 to 2 percent
by mass, the seal swelling agent is contained in an amount of 0.01
to 5 percent by mass, and the anti-foaming agent is contained in an
amount of 0.0005 to 1 percent by mass, all on the total composition
mass basis.
EXAMPLES
[0086] The present invention will be described more specifically
with reference to the following Examples and Comparative Examples
but not limited thereto.
Examples 1 to 6 and Comparative Examples 1 to 5
[0087] Lubricating oil compositions according to the present
invention (Examples 1 to 6) and those for comparison (Comparative
Examples 1 to 5) were prepared in accordance with the formulations
set forth in Table 2. The performances of each composition were
evaluated with the following tests. The results are set forth in
Table 2.
TABLE-US-00002 TABLE 2 Compar- Compar- Compar- Compar- Compar-
Total Base ative ative ative ative ative Base Oil Mass Exam- Exam-
Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Oil Basis ple
1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 1 ple 2 ple 3 ple 4 ple 5 A-1
Base Oil 1 .sup.1) inmass 100 100 100 100 100 100 100 100 100 % A-2
Base Oil 2 .sup.2) inmass 100 % A-3 Base Oil 3 .sup.3) inmass 100 %
Addi- Total mass % tives Composition Mass Basis B-1 Oil soluble
mass % 0.5 0.1 0.1 0.1 0.1 0.1 phosphorus additive 1 .sup.4) B-2
Oil soluble mass % 0.1 phosphorus additive 2 .sup.5) B-3 Oil
soluble mass % 0.1 phosphorus additive 3 .sup.6) B-4 Oil soluble
0.3 phosphorus additive 4 .sup.7) C-1 Ashless mass % 4 4 dispersant
1 .sup.8) C-2 Ashless 4 dispersant 2 .sup.9) D-1 Viscosity mass %
12 12 12 17 12 12 12 12 12 12 12 index improver .sup.10) Additive
mass % 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 package .sup.11)
P content of masspm 500 100 100 100 100 100 0 100 0 100 100 the
composition Evalution results Four - ball test .sup.12) WL
mm.sup.2/s 1961 1961 1961 1961 1961 1961 1961 1961 1961 1961 1961
LNSL % 785 785 785 785 785 785 490 785 490 785 785 Four - ball
(wear mm.sup.2/s 0.5 0.5 0.5 0.5 0.5 0.5 0.7 0.5 0.8 0.5 0.5 scar
diameter) .sup.13) Volume resistivity .sup.14) 10.sup.10 0.06 0.15
0.12 0.06 0.13 0.05 0.16 0.005 0.031 0.001 0.01 .OMEGA. m .sup.1)
kinematic viscosity (40.degree. C.) 19.7 mm.sup.2/s, kinematic
viscosity (100.degree. C.) 4.3 mm.sup.2/s, viscosity index 125, %
C.sub.P 78.5, % C.sub.N 21.5, % C.sub.A 0 .sup.2) kinematic
viscosity (40.degree. C.) 22.7 mm.sup.2/s, kinematic viscosity
(100.degree. C.) 4.3 mm.sup.2/s, viscosity index 102, % C.sub.P
66.4, % C.sub.N 29.0, % C.sub.A4.6 .sup.3) di-2-ethylhexyl azelate
kinematic viscosity (40.degree. C.) 10.1 mm.sup.2/s, kinematic
viscosity (100.degree. C.) 3.0 mm.sup.2/s, viscosity index 144
.sup.4) amine salt of acidic phosphoric acid ester (P content: 10%,
phosphoric acid ester: 2-ethylhexy, amine: mixed amine of C11to14)
.sup.5) hydrogen phosphite. isoC4 P content: 16% .sup.6) acidic
phosphoric acid ester, 2-ethylhexyl P: 9.4% .sup.7)
trioleylphosphite P: 3.7% .sup.8) boronated succinimide, PIB
M.sub.W 2000, bis type, TEPA crosslinking .sup.9) succinimide, PIB
M.sub.W 1000, bis type, TEPA crosslinking .sup.10) non-dispersant
type PMA M.sub.W 25,000 .sup.11) containing Ca metallic detergent
(0.1 mass %), metal deactivator (0.1 mass %), anti-oxidant (2.0
mass %), anti-foaming agent ( 30 mass ppm) .sup.12) 1800 rpm
.sup.13) 392N, 1800 rpm, 80.degree. C., 30 min .sup.14) in
accordance with JIS C2101, measured at 80.degree. C.
APPLICABILITY IN INDUSTRY
[0088] The lubricating oil composition of the present invention is
a composition improved in anti-wear properties and anti-seizure
properties and can be used as a lubricating oil for an electric
motor-equipped vehicle such as an electric vehicle or a hybrid
vehicle, an electric motor oil, an oil both for a transmission and
an electric motor, and an oil for a device wherein a transmission
and an electric motor are packaged in one and a lubricating system
is shared by the transmission and an electric motor.
[0089] The present invention can provide the above-described
transmission, electric motor and device including the lubricating
oil composition of the present invention and a method for
lubricating, insulating and cooling the above-described
transmission, electric motor and device using the lubricating oil
composition of the present invention.
* * * * *