U.S. patent application number 17/289993 was filed with the patent office on 2021-12-23 for lubricating oil composition.
This patent application is currently assigned to ENEOS Corporation. The applicant listed for this patent is ENEOS Corporation. Invention is credited to Yasushi ONUMATA, Yohei SUSUKIDA, Akira TADA.
Application Number | 20210395635 17/289993 |
Document ID | / |
Family ID | 1000005867321 |
Filed Date | 2021-12-23 |
United States Patent
Application |
20210395635 |
Kind Code |
A1 |
SUSUKIDA; Yohei ; et
al. |
December 23, 2021 |
LUBRICATING OIL COMPOSITION
Abstract
A lubricating oil composition including: a lubricant base oil;
(A) a calcium salicylate detergent in an amount of 0.005 to 0.03
mass % in terms of calcium on the basis of the total mass of the
composition; and (B) a phosphite ester compound represented by the
following general formula (1) in an amount of 0.01 to 0.06 mass %
in terms of phosphorus on the basis of the total mass of the
composition: ##STR00001## wherein in the general formula (1),
R.sup.1 and R.sup.2 are each independently a C5-20 group
represented by the following general formula (2): ##STR00002##
wherein in the general formula (2), R.sup.3 is a C2-17 linear chain
hydrocarbon group, and R.sup.4 is a C3-17 linear chain hydrocarbon
group, and X.sup.1 is an oxygen atom or a sulfur atom.
Inventors: |
SUSUKIDA; Yohei; (Tokyo,
JP) ; ONUMATA; Yasushi; (Tokyo, JP) ; TADA;
Akira; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENEOS Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
ENEOS Corporation
Tokyo
JP
|
Family ID: |
1000005867321 |
Appl. No.: |
17/289993 |
Filed: |
November 6, 2019 |
PCT Filed: |
November 6, 2019 |
PCT NO: |
PCT/JP2019/043569 |
371 Date: |
April 29, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10N 2030/04 20130101;
C10M 2207/144 20130101; C10M 169/04 20130101; C10M 129/54 20130101;
C10N 2040/04 20130101; C10N 2030/02 20130101; C10N 2030/42
20200501; C10M 133/44 20130101; C10M 137/02 20130101; C10M 2223/049
20130101; C10N 2040/40 20200501; C10M 141/10 20130101; C10M
2203/003 20130101; C10M 2215/30 20130101 |
International
Class: |
C10M 141/10 20060101
C10M141/10; C10M 169/04 20060101 C10M169/04; C10M 129/54 20060101
C10M129/54; C10M 137/02 20060101 C10M137/02; C10M 133/44 20060101
C10M133/44 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2018 |
JP |
2018-209255 |
Nov 6, 2018 |
JP |
2018-209266 |
Nov 6, 2018 |
JP |
2018-209267 |
Claims
1. A lubricating oil composition comprising: a lubricant base oil;
(A) a calcium salicylate detergent in an amount of 0.005 to 0.03
mass % in terms of calcium on the basis of the total mass of the
composition; and (B) a phosphite ester compound represented by the
following general formula (1) in an amount of 0.01 to 0.06 mass %
in terms of phosphorus on the basis of the total mass of the
composition: ##STR00010## wherein in the general formula (1),
R.sup.1 and R.sup.2 are each independently a C5-20 group
represented by the following general formula (2): ##STR00011##
wherein in the general formula (2), R.sup.3 is a C2-17 linear chain
hydrocarbon group, and R.sup.4 is a C3-17 linear chain hydrocarbon
group, and X.sup.1 is an oxygen atom or a sulfur atom.
2. The lubricating oil composition according to claim 1, wherein a
sum (Ca+P) of a calcium content (Ca) and a phosphorus content (P)
in the composition is 0.015 to 0.075 mass %.
3. The lubricating oil composition according to claim 1, wherein
the composition has a kinematic viscosity at 40.degree. C. of 4 to
20 mm.sup.2/s; and the composition has a kinematic viscosity at
100.degree. C. of 1.8 to 4.0 mm.sup.2/s.
4. The lubricating oil composition according to claim 1, further
comprising: (C) a tolyltriazole metal deactivator and/or a
benzotriazole metal deactivator, in an amount of 0.001 to 0.1 mass
% on the basis of the total mass of the composition.
5. The lubricating oil composition according to claim 1, wherein an
oxidatively deteriorated oil of the composition has a volume
resistivity at 80.degree. C. of no less than 1.0.times.10.sup.9
.OMEGA.cm, wherein the oxidatively deteriorated oil is obtained by
oxidatively treating the composition for 150 hours by ISOT method
conforming to JIS K2514-1.
6. The lubricating oil composition according to claim 1, wherein
the composition is used to lubricate an electric motor or to
lubricate the electric motor and a transmission, in an automobile
comprising the electric motor.
7. A method for lubricating an electric motor, the method
comprising: lubricating an electric motor installed in an
automobile, by means of the lubricating oil composition as defined
in claim 1.
8. A method for lubricating an electric motor and a transmission,
the method comprising: lubricating an electric motor and a
transmission installed in an automobile, by means of the
lubricating oil composition as defined in claim 1.
Description
FIELD
[0001] The present invention relates to a lubricating oil
composition, and specifically to a lubricating oil composition
suitable for lubrication of electric motors.
BACKGROUND
[0002] In recent years, electric vehicles which use an electric
motor as a power source for running, and hybrid vehicles which use
an electric motor and an internal combustion engine together as a
power source for running are attracting interest in view of energy
efficiency and environmental compatibility. While generating heat
during operation thereof, electric motors include heat-sensitive
components such as a coil and a magnet. Those vehicles using an
electric motor as a power source for running are thus provided with
means for cooling the electric motor. Known means for cooling the
electric motor include air cooling, water cooling and oil cooling.
Among them, oil cooling is to circulate oil in the electric motor,
to directly make parts in the electric motor which generate heat
(such as a coil, a core and a magnet) contact with a coolant (oil),
which makes it possible to obtain a high cooling effect. In the
electric motor using oil cooling, oil (lubricating oil) is
circulated in the electric motor, to cool and lubricate the
electric motor at the same time. Electrical insulation is required
of a lubricating oil (electric motor oil) of the electric
motor.
[0003] The vehicle using the electric motor as a power source for
running usually includes a transmission having a gear mechanism.
Various additives are incorporated into a lubricating oil to
lubricate the gear mechanism since anti-wear performance and
anti-fatigue performance are required of the lubricating oil.
CITATION LIST
Patent Literature
[0004] [Patent Literature 1] JP 2003-113391 A [0005] [Patent
Literature 2] JP H9-328698 A [0006] [Patent Literature 3] JP
2018-053017 A
SUMMARY
Technical Problem
[0007] A lubricating oil used for lubricating the electric motor is
usually different from that used for lubricating the transmission.
If the electric motor and the transmission (gear mechanism) can be
lubricated using the same lubricating oil, a lubricating oil
circulation system can be simplified. Recently, an electric drive
module into which the electric motor and the transmission (gear
mechanism) are integrated as one device (package) has been also
proposed. For lubrication of such an electric drive module, it is
desirable to lubricate the electric motor and the transmission
(gear mechanism) using the same lubricating oil in view of
downsizing and weight reduction.
[0008] Disadvantageously, conventional transmission oils suffer
insufficient electrical insulation when oxidatively deteriorated by
the use thereof even if electrical insulation of fresh oils thereof
is improved for the use for lubrication of the electric motor.
Anti-wear performance and anti-fatigue performance of conventional
electric motor oils are not enough for the use for lubrication of
the transmission (gear mechanism).
[0009] An object of the present invention is to provide a
lubricating oil composition having electrical insulation of the
oxidatively deteriorated composition, and anti-wear performance and
anti-fatigue performance in a well-balanced manner.
Solution to Problem
[0010] The present invention encompasses the following [1] to
[15].
[0011] [1] A lubricating oil composition comprising:
[0012] a lubricant base oil;
[0013] (A) a calcium salicylate detergent in an amount of 0.005 to
0.03 mass % in terms of calcium on the basis of the total mass of
the composition; and
[0014] (B) a phosphite ester compound represented by the following
general formula (1) in an amount of 0.01 to 0.06 mass % in terms of
phosphorus on the basis of the total mass of the composition:
##STR00003##
wherein in the general formula (1), R.sup.1 and R.sup.2 are each
independently a C5-20 group represented by the following general
formula (2):
##STR00004##
wherein in the general formula (2), R.sup.3 is a C2-17 linear chain
hydrocarbon group, and R.sup.4 is a C3-17 linear chain hydrocarbon
group, and X.sup.1 is an oxygen atom or a sulfur atom.
[0015] [2] The lubricating oil composition according to [1],
[0016] wherein a sum (Ca+P) of a calcium content (Ca) and a
phosphorus content (P) in the composition is 0.015 to 0.075 mass
%.
[0017] [3] The lubricating oil composition according to [1] or [2],
wherein the composition has a kinematic viscosity at 40.degree. C.
of 4 to 20 mm.sup.2/s; and
[0018] the composition has a kinematic viscosity at 100.degree. C.
of 1.8 to 4.0 mm.sup.2/s.
[0019] [4] The lubricating oil composition according to any one of
[1] to [3], further comprising:
[0020] (C) a tolyltriazole metal deactivator and/or a benzotriazole
metal deactivator, in an amount of 0.001 to 0.1 mass % on the basis
of the total mass of the composition.
[0021] [5] The lubricating oil composition according to any one of
[1] to [4], optionally further comprising:
[0022] an amine antioxidant as (D) an antioxidant in an amount of
no more than 0.15 mass % in terms of nitrogen on the basis of the
total mass of the composition.
[0023] [6] The lubricating oil composition according to any one of
[1] to [5], optionally comprising: (F) a nitrogen-containing
oiliness agent-based friction modifier in an amount of no more than
0.03 mass % in terms of nitrogen on the basis of the total mass of
the composition, a content of the component (F) being a total
content of any aliphatic amine compound having a C8-36 aliphatic
hydrocarbyl group other than a succinimide ashless dispersant and
an amine antioxidant, and any compound having a C8-36 aliphatic
hydrocarbyl or aliphatic hydrocarbylcarbonyl group and an amide
bond other than a succinimide ashless dispersant and an amine
antioxidant.
[0024] [7] The lubricating oil composition according to any one of
[1] to [6],
[0025] wherein a total content of any metallic detergent is no more
than 0.03 mass % in terms of metal on the basis of the total mass
of the composition.
[0026] [8] The lubricating oil composition according to any one of
[1] to [7],
[0027] wherein a proportion of any salicylate in a total soap group
content of any metallic detergent is no less than 65 mass %.
[0028] [9] The lubricating oil composition according to any one of
[1] to [8], wherein a total phosphorus content in the lubricating
oil composition is no more than 0.06 mass % in terms of phosphorus
on the basis of the total mass of the composition.
[0029] [10] The lubricating oil composition according to any one of
[1] to [9], wherein a total content of any metal element in the
lubricating oil composition is no more than 0.03 mass % in terms of
metal on the basis of the total mass of the composition.
[0030] [11] The lubricating oil composition according to any one of
[1] to [10], wherein a total content of any compound having an
O/N-based active hydrogen-containing group is 0 to 500 mass ppm in
terms of the sum of oxygen content and nitrogen content on the
basis of the total mass of the lubricating oil composition, the
compound not contributing to any content of the metallic detergent,
a succinimide ashless dispersant, the amine antioxidant, a
succinimide friction modifier, a phosphite diester compound that
does not have an O/N-based active hydrogen-containing group in its
alcohol residue, and a triazole metal deactivator, the O/N-based
active hydrogen-containing group representing a non-phenolic OH
group that may be part of any other functional group, or a salt
thereof, >NH group, or --NH.sub.2 group.
[0031] [12] The lubricating oil composition according to any one of
[1] to [11], wherein an oxidatively deteriorated oil of the
composition has a volume resistivity at 80.degree. C. of no less
than 1.0.times.10.sup.9 .OMEGA.cm, wherein the oxidatively
deteriorated oil is obtained by oxidatively treating the
composition for 150 hours by ISOT method conforming to JIS
K2514-1.
[0032] [13] The lubricating oil composition according to any one of
[1] to [12], wherein the composition is used to lubricate an
electric motor or to lubricate the electric motor and a
transmission, in an automobile comprising the electric motor.
[0033] [14] A method for lubricating an electric motor, the method
comprising: lubricating an electric motor installed in an
automobile, by means of the lubricating oil composition as defined
in any one of [1] to [13].
[0034] [15] A method for lubricating an electric motor and a
transmission, the method comprising: lubricating an electric motor
and a transmission installed in an automobile, by means of the
lubricating oil composition as defined in any one of [1] to
[13].
Advantageous Effects
[0035] According to the first aspect of the present invention, a
lubricating oil composition having electrical insulation of the
oxidatively deteriorated composition, and anti-wear performance and
anti-fatigue performance in a well-balanced manner can be
provided.
[0036] The lubricating oil composition according to the first
aspect of the present invention may be preferably used in the
lubricating method according to the second aspect of the present
invention.
DESCRIPTION OF EMBODIMENTS
[0037] The present invention will be hereinafter described. In the
present description, expression "A to B" concerning numeral values
A and B means "no less than A and no more than B" unless otherwise
specified. In such expression, if a unit is added only to the
numeral value B, the same unit is applied to the numeral value A.
Also, a word "or" means a logical sum unless otherwise specified.
In the present description, expression "E.sub.1 and/or E.sub.2"
concerning elements E.sub.1 and E.sub.2 means "E.sub.1, or E.sub.2,
or the combination thereof", and expression "E.sub.1, . . . ,
E.sub.N-1, and/or E.sub.N" concerning elements E.sub.1, . . . ,
E.sub.N (N is an integer of 3 or more) means "E.sub.1, . . . ,
E.sub.N-1, or E.sub.N, or any combination thereof".
[0038] <Lubricating Base Oil>
[0039] As a lubricating base oil in the lubricating oil composition
according to the present invention (hereinafter may be referred to
as "lubricating oil composition" or simply "composition"), at least
one mineral base oil, at least one synthetic base oil, or any mixed
base oil thereof may be used, and in one embodiment, a Group II
base oil, a Group III base oil, a Group IV base oil, or a Group V
base oil of API base stock categories, or a mixed base oil thereof
may be preferably used. An API Group II base oil is a mineral base
oil containing no more than 0.03 mass % sulfur and no less than 90
mass % saturates, and having a viscosity index of no less than 80
and less than 120. An API Group III base oil is a mineral base oil
containing no more than 0.03 mass % sulfur and no less than 90 mass
% saturates, and having a viscosity index of no less than 120. An
API Group IV base oil is a poly-.alpha.-olefin base oil. An API
Group V base oil is a base oil other than the foregoing Groups I to
IV base oils, and preferred examples thereof includes ester base
oils.
[0040] The mineral base oil may be, for example, a paraffinic or
naphthenic mineral base oil obtained through application of one or
at least two of refining means in suitable combination, such as
solvent deasphalting, solvent extraction, hydrocracking, solvent
dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing,
and white clay treatment, to lubricant oil fractions that are
obtained by distillation of crude oil under atmospheric pressure
and under reduced pressure. API Group II and Group III base oils
are usually produced via hydrocracking. A wax isomerized base oil,
a base oil produced by a process of isomerizing GTL WAX (gas to
liquid wax), or the like may be also used.
[0041] Examples of API Group IV base oils include
ethylene-propylene copolymers, polybutene, 1-octene oligomers, and
1-decene oligomers, and hydrogenated products thereof.
[0042] Examples of API Group V base oils include monoesters (such
as butyl stearate, octyl laurate, and 2-ethylhexyl oleate);
diesters (such as ditridecyl glutarate, bis(2-ethylhexyl) adipate,
diisodecyl adipate, ditridecyl adipate, and bis(2-ethylhexyl)
sebacate); polyesters (such as trimellitate esters); and polyol
esters (such as trimethylolpropane caprylate, trimethylolpropane
pelargonate, pentaerythritol 2-ethylhexanoate, and pentaerythritol
pelargonate).
[0043] The lubricating base oil (total base oil) may comprise one
base oil, or may be a mixed base oil comprising at least two base
oils. In the mixed base oil comprising at least two base oils, the
API base stock categories of these base oils may be the same, or
may be different from each other. The content of the API Group V
base oil is preferably 0 to 20 mass %, and more preferably 0 to 15
mass %; and in one embodiment, may be 0 to 10 mass %, on the basis
of the total mass of the lubricating base oil. The content of the
ester base oil at the above described upper limit or less can
improve oxidation stability of the lubricating oil composition.
[0044] The kinematic viscosity of the lubricating base oil (total
base oil) at 100.degree. C. is preferably 1.7 to 4.0 mm.sup.2/s,
and more preferably 2.2 to 3.0 mm.sup.2/s; and in one embodiment,
may be 1.7 to 3.5 mm.sup.2/s. The kinematic viscosity of the
lubricating base oil at 100.degree. C. at the above described upper
limit or less can improve fuel efficiency. The kinematic viscosity
of the lubricating base oil at 100.degree. C. at the above
described lower limit or more can further improve anti-wear
performance, and anti-fatigue performance, and can also improve
electrical insulation of a fresh oil. In the present description,
"kinematic viscosity at 100.degree. C." means a kinematic viscosity
at 100.degree. C. specified in ASTM D-445.
[0045] The kinematic viscosity of the lubricating base oil (total
base oil) at 40.degree. C. is preferably 5.0 to 20.0 mm.sup.2/s,
and more preferably 7.0 to 12.0 mm.sup.2/s; and in one embodiment,
may be 5.0 to 14.7 mm.sup.2/s. The kinematic viscosity of the
lubricating base oil at 40.degree. C. at the above described upper
limit or less can improve fuel efficiency. The kinematic viscosity
of the lubricating base oil at 40.degree. C. at the above described
lower limit or more can further improve anti-wear performance and
anti-fatigue performance, and can also improve electrical
insulation of a fresh oil. In the present description, "kinematic
viscosity at 40.degree. C." means a kinematic viscosity at
40.degree. C. specified in ASTM D-445.
[0046] The viscosity index of the lubricating base oil (total base
oil) is preferably no less than 100, and more preferably no less
than 105; and in one embodiment, may be no less than 110, may be no
less than 120, and may be no less than 125. The viscosity index of
the lubricating base oil at the above described lower limit or more
can improve viscosity-temperature characteristics and thermal and
oxidation stability, can reduce a friction coefficient, and can
further improve anti-wear performance of the lubricating oil
composition. In the present description, a viscosity index means a
viscosity index measured conforming to JIS K 2283-1993.
[0047] The sulfur content in the lubricating base oil (total base
oil) is, in view of oxidation stability, preferably no more than
0.03 mass % (300 mass ppm), more preferably no more than 50 mass
ppm, and especially preferably no more than 10 mass ppm, and may be
no more than 1 mass ppm.
[0048] The lubricating base oil (total base oil) is a major
constituent of the lubricating oil composition. The content of the
lubricating base oil (total base oil) in the lubricating oil
composition is preferably 80 to 98 mass %, and more preferably 83
to 90 mass %; and in one embodiment, may be 83 to 93 mass %, on the
basis of the total mass of the composition.
[0049] <(A) Calcium Salicylate Detergent>
[0050] The lubricating oil composition of the present invention
comprises (A) a calcium salicylate detergent (hereinafter may be
simply referred to as "component (A)"). As the component (A), a
calcium salicylate, or a basic salt or overbased salt thereof may
be used. As the component (A), one calcium salicylate detergent may
be used alone, or at least two calcium salicylate detergents may be
used in combination. Examples of the calcium salicylate include any
compound represented by the following general formula (3).
##STR00005##
[0051] In the general formula (3), R.sup.5 each independently
represent a C14-30 alkyl or alkenyl group; and a represents 1 or 2,
and is preferably 1. The compound represented by the general
formula (3) may be a mixture of any compound of the general formula
(3) where a=1 and any compound of the general formula (3) where
a=2. When a=2, R.sup.5 may be any combination of different
groups.
[0052] One preferred embodiment of the calcium salicylate detergent
may be a calcium salicylate represented by the above general
formula (3) where a=1, or a basic salt or overbased salt
thereof.
[0053] The method for producing the calcium salicylate is not
particularly restricted, and a known method for producing
monoalkylsalicylates or the like may be used. For example, the
calcium salicylate may be obtained by: making a calcium base such
as oxides and hydroxides of calcium react with a monoalkylsalicylic
acid obtained by alkylating a phenol as a starting material with an
olefin, and then carboxylating the resultant product with carbonic
acid gas or the like, or with a monoalkylsalicylic acid obtained by
alkylating a salicylic acid as a starting material with an
equivalent of the olefin, or the like; converting the above
monoalkylsalicylic acid or the like to an alkali metal salt such as
a sodium salt and a potassium salt, and then performing
transmetallation with a calcium salt; or the like.
[0054] The method for obtaining the overbased calcium salicylate is
not particularly restricted. For example, a calcium salicylate is
made to react with a calcium base such as calcium hydroxide in the
presence of carbonic acid gas, which makes it possible to obtain
the overbased calcium salicylate.
[0055] The base number of the component (A) is not particularly
limited, but is preferably 50 to 350 mgKOH/g, more preferably 100
to 350 mgKOH/g, and especially preferably 150 to 350 mgKOH/g. The
base number of the component (A) at the above described lower limit
or more can further improve electrical insulation of the
oxidatively deteriorated composition.
[0056] The content of the component (A) in the lubricating oil
composition is 0.005 to 0.03 mass %, and preferably 0.005 to 0.02
mass %, in terms of calcium on the basis of the total mass of the
lubricating oil composition. The content of the component (A) at
the above described upper limit or less can improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. The content of the component (A) at the above
described lower limit or more can improve anti-fatigue
performance.
[0057] The lubricating oil composition may comprise the component
(A) only, and may further comprise at least one metallic detergent
other than the calcium salicylate detergent (such as a calcium
sulfonate detergent and a calcium phenate detergent) in addition to
the component (A), as a metallic detergent. The total content of
the metallic detergent in the lubricating oil composition is
preferably 0.005 to 0.03 mass % in terms of metal on the basis of
the total mass of the composition. The total content of the
metallic detergent in the lubricating oil composition at the above
described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. The proportion of total salicylates in the total soap
group content of the metallic detergent, that is, the proportion of
mass of the total soap group of the salicylate detergent in terms
of organic acid to mass of the total soap group of the metallic
detergent in terms of organic acid is preferably 65 to 100 mass %,
and more preferably 90 to 100 mass %. Contribution of salicylates
to the total soap group content of the metallic detergent at the
above described lower limit or more can further improve
anti-fatigue performance. In the present description, a soap group
of the metallic detergent means a conjugate base of an organic acid
which constitutes the soap content of the metallic detergent
(examples thereof in the salicylate detergent include
alkylsalicylate anions, examples thereof in the sulfonate detergent
include alkylbenzenesulfonate anions, and examples thereof in the
phenate detergent include alkylphenate anions).
[0058] <(B) Phosphite Ester Compound>
[0059] The lubricating oil composition according to the present
invention comprises a phosphite ester compound represented by the
general formula (1) (hereinafter may be referred to as "component
(B)"). As the component (B), one phosphite ester compound may be
used alone, or at least two phosphite ester compounds may be used
in combination.
##STR00006##
In the general formula (1), R.sup.1 and R.sup.2 are each
independently a C5-20 group represented by the following general
formula (2).
##STR00007##
In the general formula (2), R.sup.3 is a C2-17 linear chain
hydrocarbon group, preferably an ethylene group or a propylene
group, and in one embodiment, an ethylene group; R.sup.4 is a
C3-17, preferably a C3-16, and especially preferably a C6-10 linear
chain hydrocarbon group. X.sup.1 is an oxygen atom or a sulfur
atom, preferably a sulfur atom.
[0060] Using a phosphite ester compound having the foregoing
structure as the component (B) can improve anti-wear performance
and anti-fatigue performance, and also makes it possible to
suppress deterioration of electrical insulation of a fresh oil and
an oxidatively deteriorated oil.
[0061] Preferred examples of R.sup.1 and R.sup.2 include
3-thiahexyl group, 3-thiaheptyl group, 3-thiaoctyl group,
3-thianonyl group, 3-thiadecyl group, 3-thiaundecyl group,
4-thiahexyl group, 3-oxapentyl group, 3-oxahexyl group, 3-oxaheptyl
group, 3-oxaoctyl group, 3-oxanonyl group, 3-oxadecyl group,
3-oxaundecyl group, 3-oxadodecyl group, 3-oxatridecyl group,
3-oxatetradecyl group, 3-oxapentadecyl group, 3-oxahexadecyl group,
3-oxaheptadecyl group, 3-oxaheptadecyl group, 3-oxanonadecyl group,
4-oxahexyl group, 4-oxaheptyl group, and 4-oxaoctyl group.
[0062] The content of the component (B) in the lubricating oil
composition is 0.01 to 0.06 mass %, preferably 0.02 to 0.06 mass %,
more preferably 0.02 to 0.05 mass %, and especially preferably 0.02
to 0.04 mass %; and in one embodiment, may be 0.02 to 0.06 mass %,
in terms of phosphorus on the basis of the total mass of the
composition. The content of the component (B) at the above
described upper limit or less can improve electrical insulation of
a fresh oil and the oxidatively deteriorated composition. The
content of the component (B) at the above described lower limit or
more can improve anti-wear performance.
[0063] <(C) Triazole Metal Deactivator>
[0064] In one preferred embodiment, the lubricating oil composition
may further comprise a tolyltriazole metal deactivator and/or a
benzotriazol metal deactivator (hereinafter may be referred to as
"component (C)"). As the component (C), any tolyltriazole metal
deactivator and/or benzotriazol metal deactivator used in
lubricating oils may be used without particular limitations. As the
component (C), one compound may be used alone, or at least two
compounds may be used in combination.
[0065] The lubricating oil composition may optionally comprise the
component (C). When the lubricating oil composition comprises the
component (C), the content of the component (C) is preferably 0.001
to 0.1 mass %, more preferably 0.001 to 0.075 mass %, and
especially preferably 0.001 to 0.05 mass %. The content of the
component (C) at the above described lower limit or more can
further improve copper corrosion inhibition performance.
[0066] The content of the component (C) at the above described
upper limit or less can further improve anti-wear performance, and
electrical insulation of a fresh oil and the oxidatively
deteriorated composition.
[0067] <(D) Succinimide Ashless Dispersant>
[0068] In one preferred embodiment, the lubricating oil composition
may further comprise (D) a succinimide ashless dispersant
(hereinafter may be referred to as "component (D)"). The component
(D) may include a boronated succinimide ashless dispersant, may
include a non-boronated succinimide ashless dispersant, or may
include any combination thereof. In view of oxidation stability,
the component (D) preferably includes a boronated succinimide
ashless dispersant.
[0069] As the component (D), for example, succinimide having at
least one alkyl or alkenyl group in its molecule, or any derivative
(modified compound) thereof may be used. Examples of succinimide
having at least one alkyl or alkenyl group in its molecule include
any compound represented by the following general formula (4) or
(5).
##STR00008##
[0070] In the general formula (4), R.sup.6 represents a C40-400
alkyl or alkenyl group; and b is an integer of 1 to 5, preferably 2
to 4. The carbon number of R.sup.6 is preferably no less than 60,
and preferably no more than 350.
[0071] In the general formula (5), R.sup.7 and R.sup.8 each
independently represent a C40-400 alkyl or alkenyl group, and may
be any combination of different groups; and c is an integer of 0 to
4, preferably 1 to 4, more preferably 1 to 3. The carbon numbers of
R.sup.7 and R.sup.8 are preferably no less than 60, and preferably
no more than 350.
[0072] The carbon numbers of R.sup.6 to R.sup.8 in the general
formulae (4) and (5) at the above described lower limits or more
make it possible to obtain good solubility in the lubricating base
oil. In contrast, the carbon numbers of R.sup.6 to R.sup.8 at the
above described upper limits or less can improve low-temperature
fluidity of the lubricating oil composition.
[0073] The alkyl or alkenyl groups (R.sup.6 to R.sup.8) in the
general formulae (4) and (5) may be linear chain or branched, and
preferred examples thereof include branched alkyl groups and
branched alkenyl groups derived from oligomers of olefins such as
propylene, 1-butene, and isobutene, or from co-oligomers of
ethylene and propylene. Among them, a branched alkyl or alkenyl
group derived from oligomers of isobutene which are conventionally
referred to as polyisobutylene, or a polybutenyl group is most
preferable.
[0074] Preferred number average molecular weights of the alkyl or
alkenyl groups (R.sup.6 to R.sup.8) in the general formulae (4) and
(5) are 800 to 3500, and in one embodiment 1000 to 3500.
[0075] Succinimide having at least one alkyl or alkenyl group in
its molecule includes so-called monotype succinimide represented by
the general formula (4) where only an amino group at one terminal
of a polyamine chain is imidated, and so-called bistype succinimide
represented by the general formula (5) where amino groups at both
terminals of a polyamine chain are imidated. The component (D) may
comprise either monotype or bistype succinimide, or may comprise
both as a mixture. The content of bistype succinimide or any
derivative (modified compound) thereof in the component (D) is
preferably no less than 50 mass %, and more preferably no less than
70 mass %, on the basis of the total mass of the component (D) (100
mass %).
[0076] The method for producing succinimide having at least one
alkyl or alkenyl group in its molecule is not specifically limited.
For example, such succinimide may be obtained as a condensation
reaction product by: reaction of alkyl- or alkenyl-succinic acid
having a C40-400 alkyl or alkenyl group or anhydride thereof, with
a polyamine. As the component (D), such a condensation product may
be used as it is, or may be converted into a derivative (modified
compound) described later to be used. The condensation product of
alkyl- or alkenyl-succinic acid or anhydride thereof, and a
polyamine may be bistype succinimide where both terminals of a
polyamine chain are imidated (see the general formula (5)), may be
monotype succinimide where only one terminal of a polyamine chain
is imidated (see the general formula (4)), or may be a mixture
thereof. Here, an alkenyl-succinic acid anhydride having a C40-400
alkenyl group may be obtained by reaction of a C40-400 alkene and
maleic anhydride, and an alkyl-succinic acid anhydride having a
C40-400 alkyl group may be obtained by a catalytic hydrogenation
reaction of such an alkenyl-succinic acid anhydride. Examples of an
alkene to react with maleic anhydride may include oligomers of
olefins and co-oligomers of ethylene and propylene as described
above, and may include isobutene oligomers. Examples of a polyamine
include diethylenetriamine, triethylenetetramine,
tetraethylenepentamine, and pentaethylenehexamine, and any mixtures
thereof, and a polyamine raw material comprising at least one
selected therefrom may be preferably used. The polyamine raw
material may further or optionally comprise ethylenediamine. In
view of improvement of the performance of the condensation product
or derivative (modified compound) thereof as a dispersant, the
content of ethylenediamine in the polyamine raw material is
preferably 0 to 10 mass %, and more preferably 0 to 5 mass %, on
the basis of the total mass of the polyamine raw material.
Succinimide obtained as the condensation reaction product of alkyl-
or alkenyl-succinic acid having a C40-400 alkyl or alkenyl group or
anhydride thereof, and a mixture of at least two polyamines is a
mixture of the compounds of the general formula (4) or (5) having
different values of b or c.
[0077] As the derivative (modified compounds) of succinimide, a
boron-modified compound (boronated succinimide) where a part or all
of the residual amino and/or imino groups is/are neutralized or
amidated by reacting succinimide as described above with boric acid
may be preferably used.
[0078] The weight average molecular weight of the succinimide
ashless dispersant is preferably 1000 to 20000, in one embodiment,
2000 to 20000, and in one embodiment, 4000 to 9000.
[0079] The lubricating oil composition may optionally comprise the
component (D). When the lubricating oil composition comprises the
component (D), the content of the component (D) is preferably 1 to
8 mass %, and in one embodiment, may be 1 to 6 mass %, on the basis
of the total mass of the lubricating oil composition. The content
of the component (D) at the above described lower limit or more can
improve electrical insulation of a fresh oil. The content of the
component (D) at the above described upper limit or less can
further improve electrical insulation of a fresh oil and the
oxidatively deteriorated composition. In view of further
improvement of electrical insulation of the oxidatively
deteriorated composition, the content of the component (D) in the
lubricating oil composition is preferably no more than 0.25 mass %
in terms of nitrogen on the basis of the total mass of the
lubricating oil composition.
[0080] <(E) Antioxidant>
[0081] In one preferred embodiment, the lubricating oil composition
may further comprise (E) an antioxidant (hereinafter may be
referred to as "component (E)"). As the component (E), one
antioxidant may be used alone, and at least two antioxidants may be
used in combination. As the component (E), any known antioxidant
such as a phenolic antioxidant and an amine antioxidant may be used
without particular limitation.
[0082] Examples of the amine antioxidant include aromatic amine
antioxidants and hindered amine antioxidants. Examples of the
aromatic amine antioxidant include primary aromatic amine compounds
such as phenyl-.alpha.-naphthylamine; and secondary aromatic amine
compounds such as alkylated diphenylamine,
alkylated-.alpha.-naphthylamine, alkylated
phenyl-.alpha.-naphthylamine, and phenyl-.beta.-naphthylamine. As
the aromatic amine antioxidant, alkylated diphenylamine, or
alkylated phenyl-.alpha.-naphthylamine, or the combination thereof
may be preferably used. Examples of the hindered amine antioxidant
include compounds each having a 2,2,6,6-tetraalkylpiperidine
skeleton (2,2,6,6-tetraalkylpiperidine derivatives). There may be
no substituent in N-position of the 2,2,6,6-tetraalkylpiperidine
skeleton, and an alkyl group may be substituted in N-position
thereof. The 2,2,6,6-tetraalkylpiperidine derivative may have a
substituent (such as acyloxy group, alkoxy group, alkylamino group,
and acylamino group) in 4-position. Two
2,2,6,6-tetraalkylpiperidine skeletons may be bonded with each
other via a substituent (such as hydrocarbylene bis(carbonyloxy)
group, hydrocarbylene diamino group, and hydrocarbylene
bis(carbonylamino) group) in their respective 4-positions. As the
amine antioxidant, the aromatic amine antioxidant may be used, the
hindered amine antioxidant may be used, or any combination thereof
may be used. The aromatic amine antioxidant may be preferably
used.
[0083] Examples of the phenolic antioxidant include
4,4'-methylenebis(2,6-di-t-butylphenol);
4,4'-bis(2,6-di-tert-butylphenol);
4,4'-bis(2-methyl-6-tert-butylphenol);
2,2'-methylenebis(4-ethyl-6-tert-butylphenol);
2,2'-methylenebis(4-methyl-6-tert-butylphenol);
4,4'-butylidenebis(3-methyl-6-tert-butylphenol);
4,4'-isopropylidenebis(2,6-di-tert-butylphenol);
2,2'-methylenebis(4-methyl-6-nonylphenol);
2,2'-isobutylidenebis(4,6-dimethylphenol);
2,2'-methylenebis(4-methyl-6-cyclohexylphenol);
2,6-di-tert-butyl-4-methylphenol; 2,6-di-tert-butyl-4-ethylphenol;
2,4-dimethyl-6-tert-butylphenol;
2,6-di-tert-butyl-4-(N,N'-dimethylaminomethyl)phenol;
4,4'-thiobis(2-methyl-6-tert-butylphenol);
4,4'-thiobis(3-methyl-6-tert-butylphenol);
2,2'-thiobis(4-methyl-6-tert-butylphenol);
bis(3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide;
bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide; 2,2'-thiodiethylene
bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];
tridecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;
pentaerythritol
tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; octyl
3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; octadecyl
3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; and
3-methyl-5-tert-butyl-4-hydroxyphenol fatty acid esters. As the
component (E), at least one amine antioxidant may be used, at least
one phenolic antioxidant may be used, or any combination thereof
may be used. In one embodiment, at least one aromatic amine
antioxidant or at least one phenolic antioxidant, or any
combination thereof may be preferably used.
[0084] The lubricating oil composition may optionally comprise the
component (E). When the lubricating oil composition comprises the
component (E), the content of the component (E) is preferably 0.1
to 1.5 mass %, and more preferably 0.1 to 1.0 mass %, on the basis
of the total mass of the lubricating oil composition. The content
of the component (E) at the above described lower limit or more can
further improve electrical insulation of the oxidatively
deteriorated composition. The content of the component (E) at the
above described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. In one embodiment, when the lubricating oil
composition comprises an amine antioxidant as the component (E),
the content of the amine antioxidant is preferably more than 0 mass
% and no more than 0.15 mass %, and in one embodiment, may be more
than 0 mass % and no more than 0.12 mass %, in terms of nitrogen on
the basis of the total mass of the lubricating oil composition. The
content of the amine antioxidant at the above described upper limit
or less can further improve electrical insulation of a fresh oil
and the oxidatively deteriorated composition. The lower limit of
the content of the amine antioxidant is not particularly limited,
but in one embodiment, may be no less than 0.005 mass % in terms of
nitrogen.
[0085] When the lubricating oil composition comprises a phenolic
antioxidant as the component (E), the content of the phenolic
antioxidant is preferably more than 0 mass % and no more than 1.5
mass %, and in one embodiment, may be more than 0 mass % and no
more than 1.0 mass %, on the basis of the total mass of the
lubricating oil composition. The content of the phenolic
antioxidant at the above described upper limit or less can further
improve electrical insulation of a fresh oil and the oxidatively
deteriorated composition. The lower limit of the content of the
phenolic antioxidant is not particularly limited, but in one
embodiment, may be no less than 0.1 mass %.
[0086] <(F) Nitrogen-Containing Oiliness Agent-Based Friction
Modifier>
[0087] In one embodiment, the lubricating oil composition may
further comprise a nitrogen-containing oiliness agent-based
friction modifier (hereinafter may be simply referred to as
"component (F)"). Examples of the nitrogen-containing oiliness
agent-based friction modifier include a succinimide friction
modifier described later, and oiliness agent-based friction
modifiers such as amine friction modifiers and amide friction
modifiers. The component (F) encompasses aliphatic amine compounds
each having a C8-36 aliphatic hydrocarbyl group other than the
succinimide ashless dispersant (component (D)) and amine
antioxidant (component (E)), and compounds each having a C8-36
aliphatic hydrocarbyl or aliphatic hydrocarbylcarbonyl group and an
amide bond other than the succinimide ashless dispersant (component
(D)) and amine antioxidant (component (D)).
[0088] Examples of the amine friction modifier include aliphatic
amine compounds each having a C10-30, preferably a C12-24, more
preferably a C12-20 alkyl or alkenyl, preferably linear chain alkyl
or linear chain alkenyl group.
[0089] Examples of the amide friction modifier include condensation
products of a linear or branched chain, preferably linear chain
fatty acid, and ammonia, an aliphatic monoamine or an aliphatic
polyamine.
[0090] One example of the amide friction modifier is a fatty acid
amide compound having a C10-30, preferably a C12-24 alkylcarbonyl
or alkenylcarbonyl group. For example, such an amide compound can
be obtained by a condensation reaction of a C10-30, preferably a
C12-24 fatty acid or an acid chloride thereof, and an aliphatic
primary or secondary amine compound, an aliphatic primary or
secondary alkanolamine compound, or ammonia. The foregoing amine
compound and alkanolamine compound each preferably have a C1-30,
more preferably a C1-10, further preferably a C1-4 aliphatic group,
and in one embodiment have a C1 or C2 aliphatic group.
[0091] Examples of the fatty acid amide friction modifier include
lauramide, myristamide, palmitamide, stearamide, oleamide,
cocamide, and C12-13 synthetic mixed fatty acid amide.
[0092] Other examples of the amide friction modifier include fatty
acid hydrazides, fatty acid semicarbazides, aliphatic ureas, fatty
acid ureides, and aliphatic allophanamides each having a C10-30
alkyl or alkenyl group, or a C10-30 alkylcarbonyl or
alkenylcarbonyl group, and derivatives (modified compounds)
thereof. Examples of the derivative (modified compound) of the
amide friction modifier include boric acid-modified compounds
obtained by reacting any amide compound as described above with
boric acid or a boric acid salt.
[0093] Examples of the aliphatic urea friction modifier include
aliphatic urea compounds each having a C12-24, preferably a C12-20
alkyl or alkenyl group such as dodecylurea, tridecylurea,
tetradecylurea, pentadecylurea, hexadecylurea, heptadecylurea,
octadecylurea, and oleylurea, and acid-modified derivatives thereof
(acid-modified compounds such as boric acid-modified
compounds).
[0094] Examples of the fatty acid hydrazide friction modifier
include fatty acid hydrazide compounds each having a C12-24
alkylcarbonyl or alkenylcarbonyl group, such as dodecanoic
hydrazide, tridecanoic hydrazide, tetradecanoic hydrazide,
pentadecanoic hydrazide, hexadecanoic hydrazide, heptadecanoic
hydrazide, octadecanoic hydrazide, oleic hydrazide, erucic
hydrazide, and acid-modified derivatives thereof (acid-modified
compounds such as boric acid-modified compounds).
[0095] Other examples of the amide friction modifier include amide
compounds of aliphatic hydroxy acids each having a C1-30
hydroxy-substituted alkyl or alkenyl group. Such an amide compound
can be obtained by, for example, a condensation reaction of any
aliphatic hydroxy acid as described above with an aliphatic primary
or secondary amine compound, or an aliphatic primary or secondary
alkanolamine compound. The carbon number of a hydroxy-substituted
alkyl or alkenyl group of the above described aliphatic hydroxy
acid is preferably 1 to 10, more preferably 1 to 4, and in one
embodiment 1 or 2. The aliphatic hydroxy acid is preferably a
linear chain aliphatic .alpha.-hydroxy acid, and in one embodiment
is a glycolic acid. The above described amine compounds and
alkanolamine compounds each preferably have a C1-30, more
preferably a C10-30, further preferably a C12-24, and especially
preferably a C12-20 aliphatic group.
[0096] Other examples of the amide friction modifier include amide
compounds of a C10-30, preferably a C12-24 fatty acid, and an amino
acid (N-acylated amino acid). Examples of the N-acylated amino acid
friction modifier include N-acylated-N-methylglycine (such as
N-oleoyl-N-methylglycine).
[0097] Examples of the succinimide friction modifier include
bis-succinimide compounds and mono-succinimide compounds each
having a C8-36 alkyl or alkenyl group, and derivatives (modified
compounds) thereof. For example, such a succinimide compound is
represented by the following general formula (6) or (7).
##STR00009##
In the general formulae (6) and (7), R.sup.9 and R.sup.10 each
independently represent a C8-36, preferably a C8-30, more
preferably a C12-22, and in one embodiment a C12-18 alkyl or
alkenyl group. R.sup.11 and R.sup.12 each independently represent a
C1-4, preferably a C2-3 alkylene group, and especially preferably
an ethylene group. R.sup.13 is a hydrogen atom or C1-36 alkyl or
alkenyl group, preferably a hydrogen atom or C1-30 alkyl or alkenyl
group, and preferably a hydrogen atom. d represents an integer of
1-7, preferably 1-4, more preferably 1-3. e represents an integer
of 1-7, preferably 1-5, more preferably 2-5, further preferably
2-4.
[0098] The method for producing the succinimide friction modifier
is not specifically limited. For example, the succinimide compound
of the general formula (6) or (7) may be obtained as a condensation
reaction product by: reaction of alkyl- or alkenyl-succinic acid
having a C8-36, preferably a C8-30, preferably a C12-22 alkyl or
alkenyl group or anhydride thereof, with a polyamine, a
N-mono-C1-36 alkylated product of the polyamine or a N-mono-C1-36
alkenylated product of the polyamine, or a mixture thereof. As the
succinimide friction modifier, such a condensation product may be
used as it is, and may be converted into a derivative (modified
compound) described later to be used. The condensation product of
alkyl- or alkenyl-succinic acid or anhydride thereof, and a
polyamine may be bistype succinimide where both terminals of a
polyamine chain are imidated (see the general formula (6)), may be
monotype succinimide where only one terminal of a polyamine chain
is imidated (see the general formula (7)), or may be a mixture
thereof. Here, examples of polyamines include diethylenetriamine,
triethylenetetramine, tetraethylenepentamine, and
pentaethylenehexamine, and any mixtures thereof, and a polyamine
raw material comprising at least one selected therefrom may be
preferably used. The polyamine raw material may further or
optionally comprise ethylenediamine. In view of improvement of the
performance of the condensation product or derivative thereof as a
friction modifier, the content of ethylenediamine in the polyamine
raw material is preferably 0 to 10 mass %, and more preferably 0 to
5 mass %, on the basis of the total mass of the polyamine raw
material. As the N-mono-C1-36 alkylated product of the polyamine, a
N-mono-C1-36 alkylated polyamine having a C1-36 alkyl group on a
nitrogen atom at an end of a chain of the polyamine may be
preferably used. As the N-mono-C1-36 alkenylated product of the
polyamine, a N-mono-C1-36 alkenylated polyamine having a C1-36
alkenyl group on a nitrogen atom at an end of a chain of the
polyamine may be preferably used. In the present description,
"Ci-j" (i and j are integers) means that the carbon number is no
less than i and no more than j.
[0099] Examples of derivatives (modified compounds) of succinimide
compounds which may be used as the succinimide friction modifier
include modified compounds obtained by reacting any succinimide
compound as described above with at least one selected from boric
acid, phosphoric acid, a C1-20 carboxylic acid, and a
sulfur-containing compound. Among them, a boric acid-modified
compound may be preferably used.
[0100] The lubricating oil composition may optionally comprise the
component (F). The content of the component (F) in the lubricating
oil composition is preferably 0 to 0.03 mass %, and in one
embodiment, may be 0 to 0.02 mass %, in terms of nitrogen on the
basis of the total mass of the composition. The content of the
component (F) at the above described upper limit or less can
further improve electrical insulation of a fresh oil and the
oxidatively deteriorated composition.
[0101] <Other Additives>
[0102] In one embodiment, the lubricating oil composition may
further comprise at least one additive selected from viscosity
index improvers, pour point depressants, anti-wear agents or
extreme-pressure agents other than the component (B), friction
modifiers other than the component (F), corrosion inhibitors other
than the component (C), metal deactivators other than the component
(C), anti-rust agents, demulsifiers, anti-foaming agents, and
coloring agents.
[0103] As the viscosity index improver, any viscosity index
improver that is used in lubricating oils may be used without
particular limitations. Examples of such a viscosity index improver
include polymethacrylates, ethylene-.alpha.-olefin copolymers and
hydrogenated products thereof, copolymers of an .alpha.-olefin and
an ester monomer having a polymerizable unsaturated bond,
polyisobutylene and hydrogenated products thereof, hydrogenated
products of styrene-diene copolymers, styrene-maleic
anhydride/ester copolymers, and polyalkylstyrene. Among them, a
polymethacrylate, an ethylene-.alpha.-olefin copolymer or a
hydrogenated product thereof, or any combination thereof may be
preferably used. The viscosity index improver may be dispersant
type, or may be non-dispersant type. In one embodiment, the weight
average molecular weight of the viscosity index improver may be,
for example, 2000 to 30000. The lubricating oil composition may
optionally comprise the viscosity index improver. When the
lubricating oil composition comprises the viscosity index improver,
the content of the viscosity index improver is preferably no more
than 12 mass %, and more preferably no more than 8 mass %, on the
basis of the total mass of the composition. The content of the
viscosity index improver at the foregoing upper limit or less can
further improve electrical insulation of a fresh oil and the
oxidatively deteriorated composition. The lower limit of this
content is not particularly limited, but in one embodiment, may be
no less than 1 mass %.
[0104] As the pour point depressant, for example, any known pour
point depressant such as a polymethacrylate polymer may be used
without particular limitations. The lubricating oil composition may
optionally comprise the pour point depressant. When the lubricating
oil composition comprises the pour point depressant, the content of
the pour point depressant in the lubricating oil composition is
preferably no more than 1 mass %, and more preferably no more than
0.5 mass %, on the basis of the total mass of the composition. The
content of the pour point depressant at the above described upper
limit or less can further improve electrical insulation of a fresh
oil and the oxidatively deteriorated composition. The lower limit
of this content is not particularly restricted, but in one
embodiment, may be no less than 0.1 mass %.
[0105] Examples of the anti-wear agent or extreme-pressure agent
other than component (B) include sulfur-containing compounds such
as disulfides, sulfurized olefins, sulfurized oils, and
dithiocarbamates, and phosphorus-containing anti-wear agents other
than the component (B). Examples of the phosphorus-containing
anti-wear agent other than the component (B) include phosphoric
acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric
acid, and complete or partial esters thereof; phosphorous acid,
thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid,
monoesters thereof, diesters thereof (excluding diesters
represented by the general formula (1)), and triesters thereof. The
lubricating oil composition may optionally comprise the anti-wear
agent other than the component (B). When the lubricating oil
composition comprises the anti-wear agent other than the component
(B), the content of this anti-wear agent is preferably no more than
10 mass %, and more preferably no more than 5 mass %, on the basis
of the total mass of the composition. The content of this anti-wear
agent at the above described upper limit or less can further
improve electrical insulation of a fresh oil and the oxidatively
deteriorated composition. The lower limit of this content is not
particularly limited, but in one embodiment, may be no less than 1
mass %.
[0106] The lubricating oil composition may optionally comprise a
phosphorus-containing additive other than the component (B). The
total phosphorus content in the lubricating oil composition is
preferably no more than 0.06 mass % on the basis of the total mass
of the composition. The total phosphorus content in the lubricating
oil composition at the above described upper limit or less can
further improve electrical insulation of a fresh oil and the
oxidatively deteriorated composition. In one embodiment, the total
content of the phosphorus-containing additive other than the
component (B) in the lubricating oil composition is preferably no
more than 0.05 mass %, more preferably no more than 0.03 mass %,
and further preferably no more than 0.02 mass %, in terms of
phosphorus on the basis of the total mass of the composition. The
total content of the phosphorus-containing additive other than the
component (B) at the above described upper limit or less can
further improve electrical insulation of a fresh oil and the
oxidatively deteriorated composition.
[0107] As the friction modifier other than the component (F), for
example, at least one friction modifier selected from organic
molybdenum compounds and oiliness agent-based friction modifiers
other than the component (F) may be used. The lubricating oil
composition may optionally comprise the friction modifier other
than the component (F). When the lubricating oil composition
comprises the friction modifier other than the component (F), the
total content of this friction modifier is preferably no more than
2 mass %, more preferably no more than 1 mass %, and especially
preferably no more than 0.5 mass %, on the basis of the total mass
of the composition. The content of this friction modifier at the
above described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. The lower limit of this content is not particularly
limited, but in one embodiment, may be no less than 0.01 mass
%.
[0108] Examples of the organic molybdenum compound include
sulfur-containing organic molybdenum compounds, and organic
molybdenum compounds which do not contain sulfur as a constituent
element. Examples of the sulfur-containing organic molybdenum
compound include sulfur-containing organic compounds such as
molybdenum dithiocarbamate compounds; molybdenum dithiophosphate
compounds; complexes of molybdenum compounds (examples thereof
include: molybdenum oxides such as molybdenum dioxide and
molybdenum trioxide; molybdenum acids such as orthomolybdic acid,
paramolybdic acid, and sulfurized (poly)molybdic acid; molybdic
acid salts such as metal salts and ammonium salts of these molybdic
acids; molybdenum sulfides such as molybdenum disulfide, molybdenum
trisulfide, molybdenum pentasulfide, and molybdenum polysulfide;
thiomolybdic acid; metal salts and amine salts of thiomolybdic
acid; and molybdenum halides such as molybdenum chloride), and
sulfur-containing organic compounds (examples thereof include:
alkyl (thio)xanthate, thiadiazole, mercaptothiadiazole,
thiocarbonate, tetrahydrocarbylthiuram disulfide,
bis(di(thio)hydrocarbyl dithiophosphonate) disulfide, organic
(poly)sulfide, and sulfurized ester) or other organic compounds;
and sulfur-containing organic molybdenum compounds such as
complexes of sulfur-containing molybdenum compounds such as the
above described molybdenum sulfides and sulfurized molybdic acids,
and alkenylsuccinimide. The organic molybdenum compound may be a
mononuclear molybdenum compound, or may be a polynuclear molybdenum
compound such as binuclear molybdenum compounds and trinuclear
molybdenum compounds. Examples of the organic molybdenum compound
which does not contain sulfur as a constituent element include
molybdenum-amine complexes, molybdenum-succinimide complexes,
molybdenum salts of organic acids, and molybdenum salts of
alcohols.
[0109] The lubricating oil composition may optionally comprise a
metal-containing additive other than the metallic detergent (such
as organic molybdenum compounds and zinc dialkyl dithiophosphate).
The total content of metal elements in the lubricating oil
composition is preferably no more than 0.03 mass % in terms of
metal on the basis of the total mass of the composition. The total
content of metal elements in the lubricating oil composition at the
above described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. In one embodiment, the total content of a
metal-containing additive other than the metallic detergent in the
lubricating oil composition is preferably no more than 0.010 mass
%, more preferably no more than 0.0075 mass %, and further
preferably no more than 0.0050 mass %, in terms of metal on the
basis of the total mass of the composition. The total content of
the metal-containing additive other than the metallic detergent at
the above described upper limit or less can further improve
electrical insulation of a fresh oil and the oxidatively
deteriorated composition.
[0110] Examples of the oiliness agent-based friction modifier other
than the component (F) include compounds such as fatty acid esters,
fatty acids, fatty acid metal salts, aliphatic alcohols, and
aliphatic ethers. These compounds each preferably have a C10-30
aliphatic hydrocarbyl or aliphatic hydrocarbylcarbonyl group, more
preferably a C10-30 alkyl or alkenyl group or a C10-30
alkylcarbonyl or alkenylcarbonyl group, further preferably a C10-30
linear chain alkyl or linear chain alkenyl group or a C10-30 linear
chain alkylcarbonyl or linear chain alkenylcarbonyl group.
[0111] As the corrosion inhibitor other than the component (C), for
example, any known corrosion inhibitor such as thiadiazole
compounds and imidazole compounds may be used without particular
limitations. The lubricating oil composition may optionally
comprise the corrosion inhibitor other than the component (C). When
the lubricating oil composition comprises the corrosion inhibitor
other than the component (C), the content of this corrosion
inhibitor is preferably no more than 1 mass %, and more preferably
no more than 0.5 mass %, on the basis of the total mass of the
composition. The content of this corrosion inhibitor at the above
described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. The lower limit of the content of this corrosion
inhibitor is not particularly restricted, but in one embodiment,
may be no less than 0.01 mass %.
[0112] As the metal deactivator other than the component (C), for
example, any known metal deactivator such as imidazoline,
pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles,
1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis(dialkyl
dithiocarbamate), 2-(alkyldithio)benzimidazole, and
.beta.-(o-carboxybenzylthio)propionitrile may be used without
particular limitations. The lubricating oil composition may
optionally comprise the metal deactivator other than the component
(C). When the lubricating oil composition comprises the metal
deactivator other than the component (C), the content of this metal
deactivator is preferably no more than 1 mass %, and more
preferably no more than 0.5 mass %, on the basis of the total mass
of the composition. The content of this metal deactivator at the
above described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. The lower limit of the content of this metal
deactivator is not particularly restricted, but in one embodiment,
may be no less than 0.01 mass %.
[0113] As the anti-rust agent, for example, any known anti-rust
agent such as petroleum sulfonate, alkylbenzenesulfonate,
dinonylnaphthalenesulfonate, alkenylsuccinate esters, and polyol
esters may be used without particular limitations. The lubricating
oil composition may optionally comprise the anti-rust agent. When
the lubricating oil composition comprises the anti-rust agent, the
content of this anti-rust agent is preferably no more than 1 mass
%, and more preferably no more than 0.5 mass %, on the basis of the
total mass of the composition. The content of this anti-rust agent
at the above described upper limit or less can further improve
electrical insulation of a fresh oil and the oxidatively
deteriorated composition. The lower limit of the content of this
anti-rust agent is not particularly restricted, but in one
embodiment, may be no less than 0.01 mass %. In the present
description, the content of any metal sulfonate shall contribute to
the content of the metallic detergent even when used as the
anti-rust agent.
[0114] As the demulsifier, for example, any known demulsifier such
as polyoxyalkylene glycol-based nonionic surfactants including
polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and
polyoxyethylene alkylnaphthyl ether may be used without particular
limitations. The lubricating oil composition may optionally
comprise the demulsifier. When the lubricating oil composition
comprises the demulsifier, the content of this demulsifier is
preferably no more than 5 mass %, and more preferably no more than
3 mass %, on the basis of the total mass of the composition. The
content of this demulsifier at the above described upper limit or
less can further improve electrical insulation of a fresh oil and
the oxidatively deteriorated composition. The lower limit of this
content is not particularly restricted, but in one embodiment, may
be no less than 1 mass %.
[0115] As the anti-foaming agent, any known anti-foaming agent such
as silicones, fluorosilicones, and fluoroalkyl ethers may be used.
The lubricating oil composition may optionally comprise the
anti-foaming agent. When the lubricating oil composition comprises
the anti-foaming agent, the content of this anti-foaming agent is
preferably no more than 0.5 mass %, and more preferably no more
than 0.1 mass %, on the basis of the total mass of the composition.
The content of this anti-foaming agent at the above described upper
limit or less can further improve electrical insulation of a fresh
oil and the oxidatively deteriorated composition. The lower limit
of this content is not particularly restricted, but in one
embodiment, may be no less than 0.0001 mass %.
[0116] As the coloring agent, for example, any known coloring agent
such as azo compounds may be used.
[0117] <Lubricating Oil Composition>
[0118] The kinematic viscosity of the lubricating oil composition
at 100.degree. C. is preferably 1.8 to 4.0 mm.sup.2/s. The
kinematic viscosity of the composition at 100.degree. C. at the
above described upper limit or less can improve fuel efficiency.
The kinematic viscosity of the composition at 100.degree. C. at the
above described lower limit or more can further improve
anti-seizure performance, anti-wear performance, anti-fatigue
performance, and electrical insulation of a fresh oil and the
oxidatively deteriorated composition.
[0119] The kinematic viscosity of the lubricating oil composition
at 40.degree. C. is preferably 4 to 20 mm.sup.2/s. The kinematic
viscosity of the composition at 40.degree. C. at the above
described upper limit or less can improve fuel efficiency. The
kinematic viscosity of the composition at 40.degree. C. at the
above described lower limit or more can further improve
anti-seizure performance, anti-wear performance, anti-fatigue
performance, and electrical insulation of a fresh oil and the
oxidatively deteriorated composition.
[0120] In one embodiment, the sum (Ca+P) of the calcium content
(Ca) and the phosphorus content (P) in the lubricating oil
composition is preferably 0.015 to 0.075 mass %. This sum Ca+P at
the foregoing upper limit or below can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated
composition. This sum Ca+P at the foregoing lower limit or over can
further improve anti-wear performance and anti-fatigue
performance.
[0121] In one embodiment, the volume resistivity of an oxidatively
deteriorated oil of the lubricating oil composition at 80.degree.
C. is preferably no less than 1.0.times.10.sup.9 .OMEGA.cm. In the
present description, the volume resistivity of an oxidatively
deteriorated oil is volume resistivity of an oxidatively
deteriorated oil measured at 80.degree. C. in oil temperature,
conforming to the volume resistivity test specified in JIS C2101:
this oxidatively deteriorated oil is obtained by oxidation
treatment on a fresh oil at 165.degree. C. for 150 hours by the
ISOT method (Indiana Stirring Oxidation Test) specified in JIS
K2514-1.
[0122] In one embodiment, the total content of any compound having
a non-phenolic OH group (which may be part of any other functional
group (such as carboxy group and phosphoric acid group)) or a salt
thereof, >NH group, or --NH.sub.2 group (hereinafter may be
referred to as "O/N-based active hydrogen-containing group"), and
not contributing to any content of the metallic detergent, the
succinimide ashless dispersant, the amine antioxidant, a phosphite
diester compound that does not have an O/N-based active
hydrogen-containing group in its alcohol residue, and the
tolyltriazole metal deactivator is preferably 0 to 500 mass ppm; in
one embodiment, may be 0 to 300 mass ppm; and in another
embodiment, may be 0 to 150 mass ppm, on the basis of the total
mass of the lubricating oil composition in terms of the sum of the
oxygen element content and the nitrogen element content. Examples
of such an O/N-based active hydrogen compound include phosphoric
acid (which may be in a form of a salt) and partial esters thereof;
phosphorous acid (which may be in a form of a salt) and partial
esters thereof (it is noted that any phosphite diester compound
that does not have the above described O/N-based active
hydrogen-containing group in its alcohol residue (such as the
component (B)) shall not fall under the O/N-based active hydrogen
compound); nitrogen-containing oiliness agent-based friction
modifiers each having a N--H bond (such as primary fatty amines,
secondary fatty amines, fatty acid primary amides, fatty acid
secondary amides, aliphatic ureas each having a N--H bond, and
fatty acid hydrazides); nitrogen-containing oiliness agent-based
friction modifiers each having a hydroxy group (such as amides of
fatty acids and primary or secondary alkanolamines, and amides of
primary or secondary fatty amines and aliphatic hydroxy acids);
nitrogen-containing oiliness agent-based friction modifiers each
having a carboxy group (which may be in a form of a salt) (such as
N-acylated amino acids); oiliness agent-based friction modifiers
each having a hydroxy group (such as glycerol monooleate), and
oiliness agent-based friction modifiers each having a carboxy group
(which may be in a form of a salt) (such as fatty acids and fatty
acid metal salts). When one O/N-based active hydrogen compound
comprises both an oxygen element and a nitrogen element, the
amounts of both an oxygen element and a nitrogen element derived
from this compound shall contribute to the total content of the
O/N-based active hydrogen compound (total amount of oxygen and
nitrogen elements) irrespective of whether each oxygen atom of the
compound is bonded to a hydrogen atom and irrespective of whether
each nitrogen atom of the compound is bonded to a hydrogen atom.
The total content of the O/N-based active hydrogen compound at the
above described upper limit or less can further improve electrical
insulation of a fresh oil and the oxidatively deteriorated oil.
[0123] (Use)
[0124] The lubricating oil composition according to the present
invention has balanced electrical insulation of the oxidatively
deteriorated composition, anti-wear performance, and anti-fatigue
performance, and thus may be preferably used as an electric motor
oil, a transmission oil, a common lubricating oil for electric
motors and transmissions (gear mechanisms), or a lubricating oil
for electric drive modules including an electric motor and a
transmission (gear mechanism). In one embodiment, the lubricating
oil composition according to the present invention may be
preferably used for lubrication of electric motors in automobiles
including the electric motor. In another embodiment, the
lubricating oil composition according to the present invention may
be preferably used for lubrication of electric motors and
transmissions (gear mechanism) in automobiles including the
electric motor and the transmission (gear mechanism).
EXAMPLES
[0125] Hereinafter the present invention will be further
specifically described based on examples and comparative examples.
The present invention is not limited to these examples.
Examples 1 to 18 and Comparative Examples 1 to 8
[0126] As shown in tables 1 to 5, lubricating oil compositions
according to the present invention (examples 1 to 18), and
lubricating oil compositions for comparison (comparative examples 1
to 8) were each prepared. In the tables, "mass %" for the base oil
means mass % on the basis of the total mass of the base oils (the
total mass of the base oils is defined as 100 mass %), "mass %" for
the other components means mass % on the basis of the total mass of
the composition (the total mass of the composition is defined as
100 mass %), and "mass ppm" for the other components means mass ppm
on the basis of the total mass of the composition. Details of the
components are as follows.
[0127] (Lubricating Base Oil)
[0128] O-1: hydrorefined mineral oil (Group II, kinematic viscosity
(40.degree. C.): 7.7 mm.sup.2/s, kinematic viscosity (100.degree.
C.): 2.3 mm.sup.2/s, viscosity index: 118, sulfur content: less
than 1 mass ppm)
[0129] O-2: hydrorefined mineral oil (Group III, kinematic
viscosity (40.degree. C.): 19.5 mm.sup.2/s, kinematic viscosity
(100.degree. C.): 4.2 mm.sup.2/s, viscosity index: 125, sulfur
content: less than 1 mass ppm)
[0130] O-3: wax isomerized base oil (Group III, kinematic viscosity
(40.degree. C.): 9.3 mm.sup.2/s, kinematic viscosity (100.degree.
C.): 2.7 mm.sup.2/s, viscosity index: 125, sulfur content: less
than 1 mass ppm)
[0131] O-4: wax isomerized base oil (Group III, kinematic viscosity
(40.degree. C.): 15.7 mm.sup.2/s, kinematic viscosity (100.degree.
C.): 3.8 mm.sup.2/s, viscosity index: 143, sulfur content: less
than 1 mass ppm)
[0132] O-5: poly-.alpha.-olefin (Group IV, kinematic viscosity
(40.degree. C.): 5.0 mm.sup.2/s, kinematic viscosity (100.degree.
C.): 1.7 mm.sup.2/s)
[0133] O-6: poly-.alpha.-olefin (Group IV, kinematic viscosity
(40.degree. C.): 18.4 mm.sup.2/s, kinematic viscosity (100.degree.
C.): 4.1 mm.sup.2/s, viscosity index: 124)
[0134] O-7: monoester base oil (Group V, kinematic viscosity
(40.degree. C.): 8.5 mm.sup.2/s, kinematic viscosity (100.degree.
C.): 2.7 mm.sup.2/s, viscosity index: 177)
[0135] ((A) Calcium detergent)
[0136] A-1: calcium salicylate detergent, base number: 325
mgKOH/g
[0137] A-2': calcium sulfonate detergent, base number: 300
mgKOH/g
[0138] ((B) Phosphite ester)
[0139] B-1: bis(3-thiaundecyl) hydrogen phosphite
[0140] B-2': diphenyl hydrogen phosphite
[0141] B-3': dibutyl hydrogen phosphite
[0142] B-4': bis(2-ethylhexyl) hydrogen phosphite
[0143] ((C) Triazole metal deactivator)
[0144] C-1: tolyltriazole metal deactivator
[0145] ((D) Succinimide ashless dispersant)
[0146] D-1: boronated succinimide ashless dispersant
[0147] ((E) Antioxidant)
[0148] E-1: amine antioxidant
[0149] E-2: phenolic antioxidant
TABLE-US-00001 TABLE 1 examples 1 2 3 4 5 6 base oil composition
O-1 mass % 85 60 -- -- -- 75 O-2 mass % 15 -- 50 -- -- 15 O-3 mass
% -- 40 -- -- -- -- O-4 mass % -- -- -- 55 -- -- O-5 mass % -- --
50 45 50 -- O-6 mass % -- -- -- -- 50 -- O-7 mass % -- -- -- -- --
10 kinematic viscosity of base oil 40.degree. C. mm.sup.2/s 8.7 8.6
9.1 8.9 8.9 8.8 100.degree. C. mm.sup.2/s 2.5 2.5 2.5 2.5 2.5 2.5
(A) Ca detergent A-1 mass % (Ca) 0.015 0.015 0.015 0.015 0.015
0.015 A-2* mass % (Ca) -- -- -- -- -- -- (B) phosphite ester B-1
mass % (P) 0.035 0.035 0.035 0.035 0.035 0.035 B-2* mass % (P) --
-- -- -- -- -- B-3* mass % (P) -- -- -- -- -- -- B-4* mass % (P) --
-- -- -- -- -- (C) metal deactivator C-1 mass % 0.05 0.05 0.05 0.05
0.05 0.05 (D) ashless dispersant D-1 mass % 5 5 5 5 5 5 (E)
antioxidant E-1 mass % 0.5 0.5 0.5 0.5 0.5 0.5 E-2 mass % 0.5 0.5
0.5 0.5 0.5 0.5 Ca + P mass % 0.050 0.050 0.050 0.050 0.050 0.050
kinematic viscosity of composition 40.degree. C mm.sup.2/s 9.7 9.1
10.5 10.1 10.2 9.6 100.degree. C. mm.sup.2/s 2.7 2.6 2.8 2.8 2.8
2.7 viscosity index 131 121 114 125 116 116 volume resistivity
(80.degree. C.) fresh oil 10.sup.10.OMEGA. cm 0.34 0.34 0.34 0.34
0.34 0.35 oxidatively deteriorated oil 10.sup.10.OMEGA. cm 0.21
0.21 0.21 0.21 00.21 0.20 high-speed four-ball test size of wear
mark mm 0.50 0.50 0.50 0.50 0.50 0.50 unisteel test fatigue life
L50 h 20 20 20 20 20 20
TABLE-US-00002 TABLE 2 examples 7 8 9 10 11 12 base oil composition
O-1 mass % -- 50 27 85 85 85 O-2 mass % -- 50 73 15 15 15 O-3 mass
% -- -- -- -- -- -- O-4 mass % -- -- -- -- -- -- O-5 mass % 100 --
-- -- -- -- O-6 mass % -- -- -- -- -- -- O-7 mass % -- -- -- -- --
-- kinematic viscosity of base oil 40.degree. C. mm.sup.2/s 5.0
11.8 14.7 8.7 8.7 8.7 100.degree. C. mm.sup.2/s 1.7 3.0 3.5 2.5 2.5
2.5 (A) Ca detergent A-1 mass % (Ca) 0.015 0.015 0.015 0.005 0.01
0.03 A-2* mass % (Ca) -- -- -- -- -- -- (B) phosphite ester B-1
mass % (P) 0.035 0.035 0.035 0.035 0.035 0.035 B-2* mass % (P) --
-- -- -- -- -- B-3* mass % (P) -- -- -- -- -- -- B-4* mass % (P) --
-- -- -- -- -- (C) metal deactivator C-1 mass % 0.05 0.05 0.05 0.05
0.05 0.05 (D) ashless dispersant D-1 mass % 5 5 5 5 5 5 (E)
antioxidant E-1 mass % 0.5 0.5 0.5 0.5 0.5 0.5 E-2 mass % 0.5 0.5
0.5 0.5 0.5 0.5 Ca + P mass % 0.050 0.050 0.050 0.040 0.045 0.065
kinematic viscosity of composition 40.degree. C mm.sup.2/s 5.7 13.1
16.1 9.7 9.7 9.7 100.degree. C. mm.sup.2/s 1.9 3.3 3.8 2.7 2.7 2.7
viscosity index 114 124 126 131 131 131 volume resistivity
(80.degree. C.) fresh oil 10.sup.10.OMEGA. cm 0.27 0.40 0.45 0.40
0.36 0.28 oxidatively deteriorated oil 10.sup.10.OMEGA. cm 0.15
0.27 0.31 0.23 0.22 0.20 high-speed four-ball test size of wear
mark mm unisteel test 0.55 0.48 0.48 0.51 0.50 0.52 fatigue life
L50 h 18 21 21 20 20 20
TABLE-US-00003 TABLE 3 examples 13 14 15 16 17 18 base oil
composition O-1 mass % 85 85 85 85 85 85 O-2 mass % 15 15 15 15 15
15 O-3 mass % -- -- -- -- -- -- O-4 mass % -- -- -- -- -- -- O-5
mass % -- -- -- -- -- -- O-6 mass % -- -- -- -- -- -- O-7 mass % --
-- -- -- -- -- kinematic viscosity of base oil 40.degree. C.
mm.sup.2/s 8.7 8.7 8.7 8.7 8.7 8.7 100.degree. C. mm.sup.2/s 2.5
2.5 2.5 2.5 2.5 2.5 (A) Ca detergent A-1 mass % (Ca) 0.015 0.015
0.015 0.015 0.015 0.015 A-2* mass % (Ca) -- -- -- -- -- -- (B)
phosphite ester B-1 mass % (P) 0.02 0.05 0.06 0.035 0.035 0.035
B-2* mass % (P) -- -- -- -- -- -- B-3* mass % (P) -- -- -- -- -- --
B-4* mass % (P) -- -- -- -- -- -- (C) metal deactivator C-1 mass %
0.05 0.05 0.05 -- 0.05 0.05 (D) ashless dispersant D-1 mass % 5 5 5
5 5 -- (E) antioxidant E-1 mass % 0.5 0.5 0.5 0.5 -- 0.5 E-2 mass %
0.5 0.5 0.5 0.5 -- 0.5 Ca + P mass % 0.035 0.065 0.075 0.050 0.050
0.050 kinematic viscosity of composition 40.degree. C mm.sup.2/s
9.7 9.7 9.7 9.7 9.7 9.5 100.degree. C. mm.sup.2/s 2.7 2.7 2.7 2.7
2.7 2.7 viscosity index 131 131 131 131 131 116 volume resistivity
(80.degree. C.) fresh oil 10.sup.10.OMEGA. cm 0.38 0.25 0.20 0.34
0.35 0.32 oxidatively deteriorated oil 10.sup.10.OMEGA. cm 0.25
0.15 0.11 0.21 0.13 0.23 high-speed four-ball test size of wear
mark mm 0.52 0.48 0.48 0.49 0.47 0.48 unisteel test fatigue life
L50 h 20 20 20 20 21 20
TABLE-US-00004 TABLE 4 comparative examples 1 2 3 4 base oil
composition O-1 mass % 85 85 85 85 O-2 mass % 15 15 15 15 O-3 mass
% -- -- -- -- O-4 mass % -- -- -- -- O-5 mass % -- -- -- -- O-6
mass % -- -- -- -- O-7 mass % -- -- -- -- kinematic viscosity of
base oil 40.degree. C. mm.sup.2/s 8.7 8.7 8.7 8.7 100.degree. C.
mm.sup.2/s 2.5 2.5 2.5 2.5 (A) Ca detergent A-1 mass % (Ca) -- --
0.015 0.015 A-2* mass % (Ca) 0.015 0.03 -- -- (B) phosphite ester
B-1 mass % (P) 0.035 0.035 -- -- B-2* mass % (P) -- -- 0.035 0.06
B-3* mass % (P) -- -- -- -- B-4* mass % (P) -- -- -- -- (C) metal
deactivator C-1 mass % 0.05 0.05 0.05 0.05 (D) ashless dispersant
D-1 mass % 5 5 5 5 (E) antioxidant E-1 mass % 0.5 0.5 0.5 0.5 E-2
mass % 0.5 0.5 0.5 0.5 Ca + P mass % 0.050 0.065 0.050 0.075
kinematic viscosity of composition 40.degree. C. mm.sup.2/s 9.7 9.7
9.7 9.7 100.degree. C. mm.sup.2/s 2.7 2.7 2.7 2.7 viscosity index
131 131 131 131 volume resistivity (80.degree. C.) fresh oil
10.sup.10.OMEGA. cm 0.34 0.28 0.30 0.20 oxidatively deteriorated
oil 10.sup.10.OMEGA. cm 0.22 0.22 0.15 0.10 high-speed four-ball
test size of wear mark mm 0.50 0.51 0.75 0.86 unisteel test fatigue
life L50 h 10 9 20 20
TABLE-US-00005 TABLE 5 comparative examples 5 6 7 8 base oil
composition O-1 mass % 85 85 85 85 O-2 mass % 15 15 15 15 O-3 mass
% -- -- -- -- O-4 mass % -- -- -- -- O-5 mass % -- -- -- -- O-6
mass % -- -- -- -- O-7 mass % -- -- -- -- kinematic viscosity of
base oil 40.degree. C. mm.sup.2/s 8.7 8.7 8.7 8.7 100.degree. C.
mm.sup.2/s 2.5 2.5 2.5 2.5 (A) Ca detergent A-1 mass % (Ca) 0.015
0.015 0.035 0.015 A-2* mass % (Ca) -- -- -- -- (B) phosphite ester
B-1 mass % (P) -- -- 0.035 0.065 B-2* mass % (P) -- -- -- B-3* mass
% (P) 0.035 -- -- -- B-4* mass % (P) -- 0.035 -- -- (C) metal
deactivator C-1 mass % 0.05 0.05 0.05 0.05 (D) ashless dispersant
D-1 mass % 5 5 5 5 (E) antioxidant E-1 mass % 0.5 0.5 0.5 0.5 E-2
mass % 0.5 0.5 0.5 0.5 Ca + P mass % 0.015 0.050 0.070 0.080
kinematic viscosity of composition 40.degree. C. mm.sup.2/s 9.7 9.7
9.7 9.7 100.degree. C. mm.sup.2/s 2.7 2.7 2.7 2.7 viscosity index
131 131 131 131 volume resistivity (80.degree. C.) fresh oil
10.sup.10.OMEGA. cm 0.19 0.17 0.18 0.10 oxidatively deteriorated
oil 10.sup.10.OMEGA. cm 0.09 0.08 0.05 0.015 high-speed four-ball
test size of wear mark mm 0.70 0.73 0.48 0.48 unisteel test fatigue
life L50 h 11 12 21 20
[0150] (Volume Resistivity)
[0151] The volume resistivity of a fresh oil, and the volume
resistivity of an oxidatively deteriorated oil were measured for
each lubricating oil composition. The oxidatively deteriorated oil
was obtained by oxidation treatment on the fresh oil at 165.degree.
C. in oil temperature for 150 hours by the ISOT (Indiana Stirring
Oxidation Test) method, conforming to JIS K2514-1. The volume
resistivity of the fresh oil, and the volume resistivity of the
oxidatively deteriorated oil were each measured at 80.degree. C. in
oil temperature, conforming to the volume resistivity test
specified in JIS C2101. The results are shown in tables 1 to 5. In
this test, higher volume resistivity at 80.degree. C. means better
electrical insulation. The volume resistivity of the oxidatively
deteriorated oil at 80.degree. C. in this test is preferably no
less than 1.0.times.10.sup.9 .OMEGA.cm.
[0152] (High-Speed Four-Ball Test)
[0153] Anti-wear performance of each of the lubricating oil
compositions was evaluated by a high-speed four-ball test
conforming to JPI-5S-40-93: the size of a wear mark after driving
at 1800 rpm in rotation speed at 392 N in load and 80.degree. C. in
oil temperature for 30 minutes was measured. The results are shown
in tables 1 to 5. In this test, a smaller size of a wear mark means
better anti-wear performance.
[0154] (Unisteel Test)
[0155] For each lubricating oil composition, a rolling fatigue life
of a thrust bearing was measured by a Unisteel test (IP305/79, The
Institute of Petroleum) using a Unisteel rolling fatigue testing
machine (triple-type high-temperature rolling fatigue testing
machine (TRF-1000/3-01H) manufactured by Tokyo Koki Testing Machine
Co. Ltd.). Time until either a roller or a test piece suffered
fatigue damage was measured for a test bearing made by replacing a
bearing ring in one side of a thrust needle bearing (FNTA-2542C
manufactured by NSK Ltd.) with a flat test piece (material: SUJ2),
under the conditions of: 7000 N in load; 2 GPa in surface pressure;
1450 rpm in rotation speed; and 120.degree. C. in oil temperature.
It was determined that fatigue damage occurred when the vibration
acceleration of a testing portion measured by a vibration
accelerometer installed in the Unisteel rolling fatigue testing
machine reached 1.5 m/s.sup.2. The test was repeated ten times, and
then a fatigue life was calculated as the 50% life (L50: time for
the cumulative probability to be 50%) by a Weibull plot based on
the time it had taken for fatigue damage to occur in the tests. The
results are shown in tables 1 to 5. A longer 50% life measured in
this test means better anti-fatigue performance.
[0156] (Evaluation Results)
[0157] The lubricating oil compositions of examples 1 to 18 showed
good results in electrical insulation of the oxidatively
deteriorated composition, anti-wear performance, and anti-fatigue
performance.
[0158] The lubricating oil compositions of comparative examples 1
and 2, which comprised a calcium sulfonate detergent instead of the
component (A) (calcium salicylate detergent), showed results
inferior in anti-fatigue performance.
[0159] The lubricating oil compositions of comparative examples 3
to 6, which comprised a phosphite ester compound having a side
chain that did not meet the requirements for the component (B),
instead of the component (B), showed results inferior in anti-wear
performance. Particularly, the lubricating oil compositions of
comparative examples 5 and 6, which comprised dialkyl hydrogen
phosphite as a phosphite ester compound, showed results inferior in
electrical insulation of the fresh oil and the oxidatively
deteriorated composition, and anti-fatigue performance as well.
[0160] The lubricating oil composition of comparative example 7,
which comprised too high a content of the component (A), showed
results inferior in electrical insulation of the fresh oil and the
oxidatively deteriorated composition.
[0161] The lubricating oil composition of comparative example 8,
which comprised too high a content of the component (B), showed
results inferior in electrical insulation of the fresh oil and the
oxidatively deteriorated composition.
* * * * *