Technical Field
[0001] The present invention relates to a lubricating oil composition.
Background Art
[0002] Hydraulic equipment to be mounted on a construction machinery, such as a hydraulic
excavator, a crane, a wheel loader, and a bulldozer, is required to be operated at
a high pressure, a high temperature, or a high speed, or under a high load. For that
reason, a hydraulic fluid which is used in the hydraulic equipment for construction
machinery is demanded to have wear resistance or oxidation stability such that even
when used at a high pressure, a high temperature, or a high speed, or under a high
load over a long period of time, it does not impair performances of the hydraulic
equipment.
[0003] In addition, for lubrication of a wet type brake or a wet type clutch of a traction
motor, a swing motor, etc., or a wet type disc brake-equipped winch, etc., equipped
in these construction machineries, it is general that a hydraulic fluid which is used
for the hydraulic equipment is also used.
[0004] For that reason, the hydraulic fluid which is used for construction machinery equipped
with a wet type brake or a wet type clutch is required to have not only the aforementioned
performances as the hydraulic fluid but also a lubricating performance for a wet type
brake or a wet type clutch.
[0005] For that reason, in the hydraulic fluid which is used for construction machinery
equipped with a wet type brake or a wet type clutch, a brake control or the like at
the time of swinging is typically performed by increasing a friction coefficient required
to be decreased to a certain extent from the standpoint of application to the hydraulic
equipment.
[0006] For example, PTL 1 investigates a hydraulic fluid composition for construction machinery
having excellent wear resistance and sludge generation suppression properties even
under a high-temperature and high-pressure condition while it is a zinc-based one,
having a low kinematic friction coefficient for controlling the actions at the time
of starting or just before stop, and having a high static friction coefficient to
such an extent that a brake performance by a wet type brake is not impaired.
[0007] In addition to that, PTL 1 discloses a hydraulic fluid composition for construction
machinery containing a base oil, a zinc dialkyldithiophosphate, basic calcium salicylate,
and an ashless friction modifier containing a nitrogen atom or an oxygen atom but
not containing phosphorus atom in specified ranges.
Citation List
Patent Literature
Summary of Invention
Technical Problem
[0009] Now, for the purpose of suppressing the sludge generation under a high-temperature
and high-pressure condition, the hydraulic fluid composition for construction machinery
as described in PTL 1 contains calcium salicylate as a dispersant. In the hydraulic
fluid compositions specifically disclosed as the working examples, though an effect
for suppressing the sludge generation due to the matter that it contains calcium salicylate
is perceived, a ratio of a kinematic friction coefficient µ
0 just before stop to a kinematic friction coefficient µ
d during operation [µ
0/µ
d] is considerably low as 0.750 or less.
[0010] For that reason, the hydraulic fluid composition for construction machinery as described
in PTL 1 involves such a concern that a problem of generation of squeal in the wet
type clutch test or worsening of braking properties is caused, and it is not suited
for an application to machines for which braking properties are particularly required
as in a crane.
[0011] In view of the aforementioned problems, the present invention has been made, and
an object thereof is to provide a lubricating oil composition which is not only excellent
in oxidation stability but also favorable in an effect for suppressing the generation
of squeal and braking properties, and which is suitably applicable to machines equipped
with a wet type brake or a wet type clutch.
Solution to Problem
[0012] The present inventors have found that a lubricating oil composition containing zinc
dithiophosphate and further containing a metal sulfonate and an ashless friction modifier
containing a boronated alkenyl succinimide is able to solve the aforementioned problem,
thereby leading to accomplishment of the present invention.
[0013] Specifically, the present invention relates to the following [1] to [3].
- [1] A lubricating oil composition, which is to be used for a machine equipped with
at least one of a wet type brake and a wet type clutch, containing a base oil (A),
zinc dithiophosphate (B), a metal sulfonate (C), and an ashless friction modifier
(D) containing a boronated alkenyl succinimide (D1).
- [2] A machine equipped with at least one of a wet type brake and a wet type clutch,
including the lubricating oil composition as set forth in the above [1].
- [3] A method of using a lubricating oil composition, including using the lubricating
oil composition as set forth in the above [1] for a machine equipped with at least
one of a wet type brake and a wet type clutch.
Advantageous Effects of Invention
[0014] The lubricating oil composition of the present invention is not only excellent in
oxidation stability but also favorable in an effect for suppressing the generation
of squeal and braking properties. For that reason, it is suitably applicable to machines
equipped with a wet type brake or wet type clutch.
Description of Embodiments
[0015] In this specification, the content of each of atoms means a value as measured in
conformity with the following standards.
- Zinc atom (Zn), calcium atom (Ca), boron atom (B), and phosphorus atom (P): Measured
in conformity with JPI-5S-38-03.
- Sulfur atom (S): Measured in conformity with JIS K2541-6.
- Nitrogen atom (N): Measured in conformity with JIS K2609.
[Lubricating Oil Composition]
[0016] The lubricating oil composition of the present invention contains a base oil (A),
zinc dithiophosphate (B), a metal sulfonate (C), and an ashless friction modifier
(D) containing a boronated alkenyl succinimide (D1).
[0017] The lubricating oil composition of an embodiment of the present invention may further
contain an antioxidant (E) according to the content of the zinc dithiophosphate (B).
[0018] The lubricating oil composition of an embodiment of the present invention may also
contain other additives for lubricating oil not corresponding to the aforementioned
components within a range where the effects of the present invention are not impaired.
[0019] In the lubricating oil composition of an embodiment of the present invention, the
total content of the component (A), the component (B), the component (C), and the
component (D) based on the total amount (100% by mass) of the lubricating oil composition
is preferably 60% by mass or more, more preferably 70% by mass or more, still more
preferably 75% by mass or more, and yet still more preferably 80% by mass or more,
and it is typically 100% by mass or less, preferably 99.0% by mass or less, and more
preferably 98.0% by mass or less.
[0020] In the lubricating oil composition of an embodiment of the present invention, the
total content of the component (A), the component (B), the component (C), the component
(D), and the component (E) based on the total amount (100% by mass) of the lubricating
oil composition is preferably 65% by mass or more, more preferably 70% by mass or
more, still more preferably 75% by mass or more, and yet still more preferably 80%
by mass or more, and it is typically 100% by mass or less, preferably 99.5% by mass
or less, and more preferably 99.0% by mass or less.
[0021] The lubricating oil composition of the present invention is one to be used for a
machine equipped with at least one of a wet type brake and a wet type clutch.
[0022] As mentioned above, in a machine equipped with a wet type brake or a wet type clutch,
it is general that a lubricating oil composition which is used for the hydraulic equipment
is also used for a wet type brake or a wet type clutch of a traction motor or a swing
motor, etc. with which the foregoing machine is equipped.
[0023] For that reason, the lubricating oil composition which is used for a machine equipped
with a wet type brake or a wet type clutch is required to have not only excellent
oxidation stability that is a performance as the hydraulic fluid but also such characteristics
that a friction coefficient is high to a certain extent, and an effect for suppressing
the generation of squeal or braking properties are favorable so as to make it applicable
for lubrication of a wet type brake or a wet type clutch.
[0024] Now, in the lubricating oil composition as disclosed in PTL 1, etc., which is obtained
by blending a metal salicylate as a dispersant together with a base oil and zinc dithiophosphate,
a ratio of a kinematic friction coefficient µ
0 just before stop to a kinematic friction coefficient µ
d during operation [µ
0/µ
d] tends to become low. For example, in the lubricating oil compositions shown in the
working examples of the PTL 1, the foregoing ratio [µ
0/µ
d] is considerably low as 0.750 or less.
[0025] As mentioned above, in such a lubricating oil composition, on the occasion when applied
to a wet type brake or a wet type clutch, the generation of squeal or worsening of
braking properties to be caused due to a decrease of the friction coefficient is feared.
In particular, when applied to a machine for which braking properties are required,
such as a crane and a winch, it is expected to be difficult for control of delicate
movements of the winch.
[0026] On the other hand, in the lubricating oil composition of the present invention, in
view of the fact that it contains, as a dispersant, the metal sulfonate (C) but not
a metal salicylate, together with the base oil (A) and the zinc dithiophosphate (B)
and further contains, as a friction modifier, the ashless friction modifier (D) containing
the boronated alkenyl succinimide (D1) containing a nitrogen atom and an oxygen atom,
not only excellent oxidation stability is kept, but also an effect for suppressing
the generation of squeal is high, and braking properties are improved, too.
[0027] Each of the components which are contained in the lubricating oil composition of
an embodiment of the present invention is hereunder described.
<Base Oil (A)>
[0028] The base oil (A) which is contained in the lubricating oil composition of the present
invention may be a mineral oil, may be a synthetic oil, or may be a mixed oil of a
mineral oil and a synthetic oil.
[0029] Examples of the mineral oil include atmospheric residues obtained through atmospheric
distillation of crude oils, such as paraffin-based crude oils, intermediate-base crude
oils, and naphthene-based crude oils; distillates obtained through reduced-pressure
distillation of such atmospheric residues; mineral oils obtained by purifying the
distillates through one or more purification treatments, such as solvent deasphalting,
solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining;
and mineral oils (GTL) obtained by isomerizing a wax (GTL wax (Gas To Liquids WAX))
which is obtained by synthesis of a natural gas through the Fischer-Tropsch method,
etc.
[0030] These mineral oils may be used alone or may be used in combination of two or more
thereof.
[0031] Of these, as the mineral oil which is used in an embodiment of the present invention,
it is preferred to contain a mineral oil having been subjected to one or more purification
treatments, such as solvent deasphalting, solvent extraction, hydrocracking, solvent
dewaxing, catalytic dewaxing, and hydrorefining, or a mineral oil obtained by isomerizing
a GTL wax.
[0032] As the mineral oil, it is preferred to contain a mineral oil grouped in Group 2 or
Group 3 in the base oil category by API (American Petroleum Institute) or a mineral
oil obtained by isomerizing a GTL wax; and it is more preferred to contain a mineral
oil grouped in the foregoing Group 3 or a mineral oil obtained by isomerizing a GTL
wax.
[0033] Examples of the synthetic oil include synthetic oils, such as poly-α-olefins, e.g.,
an α-olefin homopolymer and an α-olefin copolymer (for example, an α-olefin copolymer
having 8 to 14 carbon atoms, e.g., an ethylene-α-olefin copolymer); isoparaffins;
esters, e.g., a polyol ester and a dibasic acid ester; ethers, e.g., polyphenyl ether;
polyalkylene glycols; alkylbenzenes; and alkylnaphthalenes.
[0034] These synthetic oils may be used alone or may be used in combination of two or more
thereof.
[0035] Of these, as the synthetic oil which is used in an embodiment of the present invention,
it is preferred to contain one or more synthetic oils selected from poly-α-olefins,
various esters, and polyalkylene glycols.
[0036] A kinematic viscosity at 40°C of the base oil (A) is preferably 10 to 150 mm
2/s, more preferably 12 to 120 mm
2/s, and still more preferably 15 to 100 mm
2/s.
[0037] A viscosity index of the base oil (A) is preferably 80 or more, more preferably 100
or more, and still more preferably 110 or more.
[0038] In this specification, the "kinematic viscosity at 40°C" and the "viscosity index"
mean values as measured in conformity of JIS K2283.
[0039] In the case where the base oil (A) is a mixed oil of two or more selected from mineral
oils and synthetic oils, the kinematic viscosity and the viscosity index of the mixed
oil have to only fall within the aforementioned ranges, respectively.
[0040] In the lubricating oil composition of an embodiment of the present invention, the
content of the base oil (A) based on the total amount (100% by mass) of the lubricating
oil composition is typically 55% by mass or more, preferably 60% by mass or more,
more preferably 65% by mass or more, still more preferably 70% by mass or more, and
yet still more preferably 75% by mass or more, and it is preferably 98% by mass or
less, more preferably 97% by mass or less, still more preferably 95% by mass or less,
and yet still more preferably 93% by mass or less.
<Zinc Dithiophosphate (B)>
[0041] Since the lubricating oil composition of the present invention contains the zinc
dithiophosphate (B), it improves wear resistance and oxidation stability and effectively
suppresses metal wear and oxidation degradation generated following the use.
[0042] The zinc dithiophosphate (B) which is contained in the lubricating oil composition
of an embodiment of the present invention is preferably a compound represented by
the following general formula (b-1).
[0043] The zinc dithiophosphate (B) may be used alone or may be used in combination of two
or more thereof.
[0044] In the formula (b-1), R
1 to R
4 each independently represent a hydrocarbon group and may be the same as or different
from each other.
[0045] Specific examples of the hydrocarbon group which may be selected as R
1 to R
4 include alkyl groups, such as a methyl group, an ethyl group, a propyl group, a butyl
group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl
group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl
group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group,
and an octadecyl group; alkenyl groups, such as an octenyl group, a nonenyl group,
a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl
group, and a pentadecenyl group; cycloalkyl groups, such as a cyclohexyl group, a
dimethylcyclohexyl group, an ethylcyclohexyl group, a methylcyclohexylmethyl group,
a cyclohexylethyl group, a propylcyclohexyl group, a butylcyclohexyl group, and a
heptylcyclohexyl group; aryl groups, such as a phenyl group, a naphthyl group, an
anthracenyl group, a biphenyl group, and a terphenyl group; alkylaryl groups, such
as a tolyl group, a dimethylphenyl group, a butylphenyl group, a nonylphenyl group,
a methylbenzyl group, and a dimethylnaphthyl group; and arylalkyl groups, such as
a phenylmethyl group, a phenylethyl group, and a diphenylmethyl group.
[0046] Of these, an alkyl group is preferred as R
1 to R
4.
[0047] Though the alkyl group may be either a linear alkyl group or a branched alkyl group,
it is preferably a branched alkyl group.
[0048] The carbon number of the hydrocarbon group which may be selected as R
1 to R
4 is preferably 1 to 20, more preferably 3 to 16, still more preferably 4 to 12, and
yet still more preferably 5 to 10.
[0049] In the lubricating oil composition of an embodiment of the present invention, from
the viewpoint of not only more improving the oxidation stability and enhancing the
effect for suppressing the sludge deposition, but also providing a lubricating oil
composition with excellent wear resistance, the content of the component (B) as expressed
in terms of a zinc atom based on the total amount (100% by mass) of the lubricating
oil composition is preferably 100 ppm by mass or more, more preferably 150 ppm by
mass or more, still more preferably 200 ppm by mass or more, and yet still more preferably
250 ppm by mass or more, and from the viewpoint of more improving the wear resistance,
it is even yet still more preferably 500 ppm by mass or more, and especially preferably
600 ppm by mass or more.
[0050] So long as the content of the component (B) as expressed in terms of a zinc atom
is 500 ppm by mass or more, even when an antioxidant (E) as mentioned later is not
separately blended, it becomes possible to prepare a lubricating oil composition having
an effect for suppressing the sludge deposition.
[0051] From the viewpoint of providing a lubricating oil composition capable of regulating
the friction coefficient to a predetermined value or more and suppressing evils, such
as generation of squeal and worsening of braking properties, the content of the component
(B) as expressed in terms of a zinc atom based on the total amount (100% by mass)
of the lubricating oil composition is preferably 2,000 ppm by mass or less, more preferably
1,500 ppm by mass or less, still more preferably 1,200 ppm by mass or less, and yet
still more preferably 1,000 ppm by mass or less.
[0052] In the lubricating oil composition of an embodiment of the present invention, as
for the content (blending amount) of the component (B), though the content as expressed
in terms of a zinc atom may be regulated so as to fall within the aforementioned range,
it is typically 0.01 to 2.00% by mass, preferably 0.01 to 1.50% by mass, more preferably
0.01 to 1.00% by mass, still more preferably 0.05 to 0.90% by mass, yet still more
preferably 0.10 to 0.85% by mass, and especially preferably 0.20 to 0.80% by mass
based on the total amount (100% by mass) of the lubricating oil composition.
<Metal Sulfonate (C)>
[0053] Since the lubricating oil composition of the present invention contains the metal
sulfonate (C), not only the effect for improving the oxidation stability owing to
addition of the component (B) is effectively revealed, but also evils, such as worsening
of braking properties, can be suppressed.
[0054] From the aforementioned viewpoint, the metal sulfonate (C) is preferably a metal
sulfonate containing a metal atom selected from alkali metals and an alkaline earth
metals; and more preferably a metal sulfonate containing a metal atom selected from
a sodium atom, a calcium atom, a magnesium atom, and a barium atom. In particular,
from the viewpoint of providing a lubricating oil composition in which the friction
coefficient in a high-speed region is appropriately increased, and the braking properties
are more improved, it is still more preferred to contain calcium sulfonate.
[0055] In this specification, the "alkali metal atom" refers to a lithium atom (Li), a sodium
atom (Na), a potassium atom (K), a rubidium atom (Rb), a cesium atom (Cs), and a francium
atom (Fr).
[0056] The "alkaline earth metal atom" refers to a beryllium atom (Be), a magnesium atom
(Mg), a calcium atom (Ca), a strontium atom (Sr), and a barium atom (Ba).
[0057] In the lubricating oil composition of an embodiment of the present invention, the
content of the calcium sulfonate in the component (C) based on the total amount (100%
by mass) of the component (C) which is contained in the lubricating oil composition
is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably
90 to 100% by mass, and yet still more preferably 95 to 100% by mass.
[0058] The metal sulfonate (C) which is contained in the lubricating oil composition of
an embodiment of the present invention is preferably a compound represented by the
following general formula (c-1).
[0059] The metal sulfonate (C) may be used alone or may be used in combination of two or
more thereof.
In the general formula (c-1), M is a metal atom; preferably an alkali metal or an
alkaline earth metal; more preferably a sodium atom, a calcium atom, a magnesium atom,
or a barium atom; still more preferably a calcium atom or a magnesium atom; and yet
still more preferably a calcium atom.
p is a valence of M and is 1 or 2.
[0060] Examples of R include a hydrogen atom, an alkyl group having 1 to 18 carbon atoms,
an alkenyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 ring
carbon atoms, an aryl group having 6 to 18 ring carbon atoms, an alkylaryl group having
7 to 18 carbon atoms, and an arylalkyl group having 7 to 18 carbon atoms.
[0061] Though the metal sulfonate (C) may be any of a neutral salt, a basic salt, an overbased
salt, and a mixture thereof, it is preferred to contain an overbased salt.
[0062] In the case where the metal sulfonate (C) is a neutral salt, a base number of the
neutral salt is preferably 0 to 30 mgKOH/g, more preferably 0 to 25 mgKOH/g, and still
more preferably 0 to 20 mgKOH/g.
[0063] In the case where the metal sulfonate (C) is a basic salt or an overbased salt, a
base number of the basic salt or overbased salt is preferably 100 to 600 mgKOH/g,
more preferably 120 to 550 mgKOH/g, still more preferably 160 to 500 mgKOH/g, and
yet still more preferably 200 to 480 mgKOH/g.
[0064] In this specification, the "base number" means a base number measured by the perchloric
acid method in conformity with Item 7 of JIS K2501 "Petroleum Products and Lubricating
Oils-Neutralization Number Testing Method."
[0065] In the lubricating oil composition of an embodiment of the present invention, from
the viewpoint of providing a lubricating oil composition in which the friction coefficient
in a high-speed region is appropriately increased, and the braking properties are
improved, the content of the component (C) as expressed in terms of a metal atom based
on the total amount (100% by mass) of the lubricating oil composition is preferably
200 ppm by mass or more, more preferably 300 ppm by mass or more, still more preferably
400 ppm by mass or more, yet still more preferably 500 ppm by mass or more, even yet
still more preferably 1,000 ppm by mass or more, and even still more preferably 1,200
ppm by mass or more.
[0066] From the viewpoint of providing a lubricating oil composition which may more effectively
suppress the generation of squeal, the content of the component (C) as expressed in
terms of a metal atom based on the total amount (100% by mass) of the lubricating
oil composition is preferably 4,000 ppm by mass or less, more preferably 3,500 ppm
by mass or less, still more preferably 2,500 ppm by mass or less, and yet still more
preferably 2,000 ppm by mass or less.
[0067] In the lubricating oil composition of an embodiment of the present invention, as
for the content (blending amount) of the component (C), though the content as expressed
in terms of a metal atom may be regulated so as to fall within the aforementioned
range, it is preferably 0.01 to 3.0% by mass, more preferably 0.05 to 2.7% by mass,
still more preferably 0.10 to 2.4% by mass, and yet still preferably 0.20 to 2.0%
by mass based on the total amount (100% by mass) of the lubricating oil composition.
[0068] In the lubricating oil composition of an embodiment of the present invention, though
a metal salicylate may be contained within a range where the effects of the present
invention are not impaired, from the viewpoint of providing a lubricating oil composition
in which the friction coefficient in a high-speed region is appropriately increased,
and the braking properties are more improved, it is preferred that the content of
the metal salicylate is low as far as possible.
[0069] Specifically, the content of the metal salicylate based on the total amount (100%
by mass) of the lubricating oil composition is preferably less than 0.03% by mass,
more preferably less than 0.01% by mass, still more preferably less than 0.001% by
mass, and yet still more preferably less than 0.0001% by mass.
[0070] The content of the metal salicylate relative to the total amount (100% by mass) of
the component (C) which is contained in the lubricating oil composition is preferably
less than 10% by mass, more preferably less than 6% by mass, still more preferably
less than 3% by mass, and yet still more preferably less than 1% by mass.
<Ashless Friction Modifier (D)>
[0071] Since the lubricating oil composition of the present invention contains the ashless
friction modifier (D) containing the boronated alkenyl succinimide (D1), not only
the effect for improving the oxidation stability owing to addition of the component
(B) is effectively revealed, but also evils, such as worsening of braking properties,
can be suppressed.
[0072] In particular, in view of the fact that the component (D1) is contained, the effect
for suppressing evils, such as generation of squeal and worsening of braking properties,
may be conspicuously improved as compared with the case of using only the component
(C).
[0073] In the lubricating oil composition of an embodiment of the present invention, from
the viewpoint of not only more effectively revealing the effect for improving the
oxidation stability owing to addition of the component (B) but also more suppressing
evils, such as generation of squeal and worsening of braking properties, it is preferred
that the component (D) contains the boronated alkenyl succinimide (D1) and an alkenyl
group-containing unsaturated amine (D2).
[0074] A content ratio of the component (D1) to the component (D2) [(D1)/(D2)] is preferably
2 to 100, more preferably 3 to 80, still more preferably 4 to 60, yet still more preferably
5 to 50, and even yet still more preferably 7 to 40 in terms of a mass ratio.
[0075] When the aforementioned mass ratio [(D1)/(D2)] is 2 or more, the effect for suppressing
worsening of braking properties is more readily revealed. On the other hand, when
the mass ratio [(D1)/(D2)] is 100 or less, the effect for suppressing the generation
of squeal is more readily revealed.
[0076] The lubricating oil composition of an embodiment of the present invention may contain,
as the ashless friction modifier (C), other ashless friction modifier than the components
(D1) and (D2) within a range where the effects of the present invention are not impaired.
[0077] However, in the lubricating oil composition of an embodiment of the present invention,
the content of the component (D1) based on the total amount (100% by mass) of the
component (D) which is contained in the lubricating oil composition is preferably
50% by mass or more, more preferably 60% by mass or more, still more preferably 70%
by mass or more, and yet still more preferably 80% by mass or more.
[0078] In the lubricating oil composition of an embodiment of the present invention, the
total content of the components (D1) and (D2) based on the total amount (100% by mass)
of the component (D) which is contained in the lubricating oil composition is preferably
60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to
100% by mass, and yet still more preferably 90 to 100% by mass.
[0079] In the lubricating oil composition of an embodiment of the present invention, the
content (blending amount) of the component (D) based on the total amount (100% by
mass) of the lubricating oil composition is preferably 0.05 to 7.0% by mass, more
preferably 0.10 to 5.0% by mass, still more preferably 0.20 to 4.0% by mass, and yet
still more preferably 0.30 to 3.2% by mass.
[0080] In the lubricating oil composition of an embodiment of the present invention, the
content of a nitrogen atom derived from the component (D) based on the total amount
(100% by mass) of the lubricating oil composition is preferably 15 to 900 ppm by mass,
more preferably 40 to 700 ppm by mass, still more preferably 55 to 500 ppm by mass,
and yet still more preferably 100 to 350 ppm by mass.
[Boronated Alkenyl Succinimide (D1)]
[0081] The boronated alkenyl succinimide (D1) which is used in the present invention is
a boronated product of an alkenyl succinimide, and examples of the boronated product
include boron oxide, a boron halide, boric acid, boric anhydride, a boric acid ester,
and an ammonium salt of boric acid.
[0082] In an embodiment of the present invention, the boronated alkenyl succinimide (D1)
is preferably a boronated product of a compound represented by the following general
formula (d-11) or (d-12).
[0083] The component (D1) may also be a boronated product of polybutenyl succinimide obtained
through a reaction between a compound represented by the following general formula
(d-11) or (d-12) and at least one compound selected from an alcohol, an aldehyde,
a ketone, an alkylphenol, a cyclic carbonate, an epoxy compound, and an organic acid.
In the general formulae (d-11) and (d-12), RA, RA1, and RA2 are each independently an alkenyl group having a weight average molecular weight
(Mw) of 500 to 3,000 (preferably 1,000 to 3,000).
RB, RB1, and RB2 are each independently an alkylene group having 2 to 5 carbon atoms.
x1 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably
3 or 4.
x2 is an integer of 0 to 10, preferably an integer of 1 to 4, and more preferably
2 or 3.
[0084] Examples of the alkenyl group which may be selected as R
A, R
A1, and R
A2 include a polybutenyl group, a polyisobutenyl group, and a group containing an ethylene-propylene
unit. Of these, a polybutenyl group or a polyisobutenyl group is preferred.
[0085] The compound represented by the general formula (d-11) can be, for example, produced
by allowing an alkenyl succinic anhydride obtained through a reaction between a polyolefin
and maleic anhydride, to react with a polyamine.
[0086] Examples of the polyolefin include polymers obtained through polymerization of one
or more compounds selected from α-olefins having 2 to 8 carbon atoms. Of these, a
copolymer of isobutene and 1-butene is preferred.
[0087] Examples of the polyamine include simple diamines, such as ethylenediamine, propylenediamine,
butylenediamine, and pentylenediamine; polyalkylenepolyamines, such as diethylenetriamine,
triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di(methylethylene)triamine,
dibutylenetriamine, tributylenetetramine, and pentapentylenehexamine; and piperazine
derivatives, such as aminoethylpiperazine.
[0088] The compound represented by the general formula (d-12) can be, for example, produced
by allowing an alkenyl succinic anhydride obtained through a reaction between the
aforementioned polyolefin and maleic anhydride, to react with the aforementioned polyamine.
[0089] In the lubricating oil composition of an embodiment of the present invention, from
the viewpoint of effectively suppressing evils, such as generation of squeal and worsening
of braking properties, a mass ratio [B/N] of a boron atom to a nitrogen atom constituting
the component (D1) is preferably 0.2 to 3.0, more preferably 0.4 to 2.5, still more
preferably 0.6 to 2.0, and yet still more preferably 0.7 to 1.5.
[0090] In the lubricating oil composition of an embodiment of the present invention, the
content of the component (D1) as expressed in terms of a boron atom based on the total
amount (100% by mass) of the lubricating oil composition is preferably 30 to 600 ppm
by mass, more preferably 50 to 500 ppm by mass, still more preferably 60 to 400 ppm
by mass, and yet still more preferably 80 to 300 ppm by mass.
[0091] In the lubricating oil composition of an embodiment of the present invention, the
content of the component (D1) as expressed in terms of a nitrogen atom based on the
total amount (100% by mass) of the lubricating oil composition is preferably 10 to
800 ppm by mass, more preferably 30 to 600 ppm by mass, still more preferably 50 to
400 ppm by mass, and yet still more preferably 80 to 300 ppm by mass.
[0092] In the lubricating oil composition of an embodiment of the present invention, as
for the content (blending amount) of the component (D1), though the content as expressed
in terms of a boron atom may be regulated so as to fall within the aforementioned
range, it is preferably 0.05 to 4.0% by mass, more preferably 0.10 to 3.0% by mass,
still more preferably 0.20 to 2.5% by mass, and yet still more preferably 0.30 to
2.0% by mass based on the total amount (100% by mass) of the lubricating oil composition.
[Alkenyl Group-Containing Unsaturated Amine (D2)]
[0093] Examples of the alkenyl group-containing unsaturated amine (D2) which is used in
an embodiment of the present invention include primary to tertiary unsaturated amines
having 1 to 3 alkenyl groups.
[0094] The carbon number of the alkenyl group is preferably 2 to 30, more preferably 4 to
26, still more preferably 8 to 24, and yet still more preferably 10 to 20.
[0095] Though the alkenyl group may be either a linear alkenyl group or a branched alkenyl
group, it is preferably a linear alkenyl group.
[0096] In an embodiment of the present invention, it is preferred that the unsaturated amine
(D2) contains a primary unsaturated amine (D21) having an alkenyl group having 2 to
30 carbon atoms.
[0097] In the lubricating oil composition of an embodiment of the present invention, the
content of the primary unsaturated amine (D21) in the component (D2) based on the
total amount (100% by mass) of the component (D2) which is contained in the lubricating
oil composition is preferably 70 to 100% by mass, more preferably 80 to 100% by mass,
still more preferably 90 to 100% by mass, and yet still more preferably 95 to 100%
by mass.
[0098] The primary unsaturated amine (D21) is preferably a compound represented by the following
general formula (d-2).
H
2N-(CH
2)
z1-CH=CH-(CH
2)
z2-H (d-2)
[0099] In the general formula (d-2), z1 and z2 are each independently an integer of 0 or
more, and (z1 + z2) is an integer of 0 to 28. (z1 + z2) is preferably 2 to 24, more
preferably 6 to 22, and still more preferably 7 to 18.
[0100] In the lubricating oil composition of an embodiment of the present invention, the
content of the component (D2) as expressed in terms of a nitrogen atom based on the
total amount (100% by mass) of the lubricating oil composition is preferably 5 to
100 ppm by mass, more preferably 10 to 80 ppm by mass, still more preferably 15 to
60 ppm by mass, and yet still more preferably 20 to 50 ppm by mass.
[0101] In the lubricating oil composition of an embodiment of the present invention, as
for the content (blending amount) of the component (D2), though the content as expressed
in terms of a nitrogen atom may be regulated so as to fall within the aforementioned
range, it is preferably 0.001 to 3.0% by mass, more preferably 0.005 to 2.0% by mass,
still more preferably 0.01 to 1.5% by mass, and yet still more preferably 0.02 to
1.2% by mass based on the total amount (100% by mass) of the lubricating oil composition.
[Other Ashless Friction Modifier (D) than Components (D1) and (D2)]
[0102] The lubricating oil composition of an embodiment of the present invention may contain,
as the ashless friction modifier (C), other ashless friction modifier than the components
(D1) and (D2) within a range where the effects of the present invention are not impaired.
[0103] Examples of the other ashless friction modifier include an aliphatic amine having
an alkyl group having 2 to 30 carbon atoms, other than the components (D1) and (D2);
a compound having an alkenyl group or an alkyl group each having 2 to 30 carbon atoms,
which is selected from a fatty acid ester, a fatty acid amide, a fatty acid, an aliphatic
alcohol, and an aliphatic ether; a phosphoric acid ester; and a non-boronated alkenyl
succinimide.
[0104] In the lubricating oil composition of an embodiment of the present invention, a non-boronated
alkenyl succinimide may be contained within a range where the effects of the present
invention are not impaired; however, it is preferred that the content of the non-boronated
alkenyl succinimide is low.
[0105] Specifically, the content of the non-boronated alkenyl succinimide based on the total
amount (100% by mass) of the component (D1) which is contained in the lubricating
oil composition is preferably less than 10% by mass, more preferably less than 6%
by mass, still more preferably less than 3% by mass, and yet still more preferably
less than 1% by mass.
<Antioxidant (E)>
[0106] The lubricating oil composition of an embodiment of the present invention may further
contain an antioxidant (E) according to the content of the zinc dithiophosphate (B).
[0107] Examples of the antioxidant (E) include a phenol-based antioxidant, an amine-based
antioxidant, a molybdenum-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based
antioxidant.
[0108] In an embodiment of the present invention, the antioxidant (E) may be used alone
or may be used in combination of two or more thereof.
[0109] Of these, in an embodiment of the present invention, from the viewpoint of more improving
the oxidation stability, it is preferred that the antioxidant (E) contains a phenol-based
antioxidant (E1) and an amine-based antioxidant (E2).
[0110] Examples of the phenol-based antioxidant (E1) include monophenol-based antioxidants,
such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol,
isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate;
diphenol-based antioxidants, such as 4,4'-methylenebis(2,6-di-t-butylphenol) and 2,2'-methylenebis(4-ethyl-6-t-butylphenol);
and hindered phenol-based antioxidants.
[0111] The amine-based antioxidant (E2) is preferably an aromatic amine compound, and more
preferably at least one selected from a diphenylamine compound and a naphthylamine-based
compound.
[0112] Examples of the diphenylamine-based compound include monoalkyldiphenylamine-based
compounds having one alkyl group having 1 to 30 carbon atoms (preferably 4 to 30 carbon
atoms, and more preferably 8 to 30 carbon atoms), such as monooctyldiphenylamine and
monononyldiphenylamine; dialkyldiphenylamine compounds having two alkyl groups having
1 to 30 carbon atoms (preferably 4 to 30 carbon atoms, and more preferably 8 to 30
carbon atoms), such as 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine,
4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, and 4,4'-dinonyldiphenylamine;
polyalkyldiphenylamine-based compounds having three or more alkyl groups having 1
to 30 carbon atoms (preferably 4 to 30 carbon atoms, and more preferably 8 to 30 carbon
atoms), such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine,
and tetranonyldiphenylamine; and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.
[0113] Examples of the naphthylamine-based compound include 1-naphthylamine, phenyl-1-naphthylamine,
butylphenyl-1-naphthylamine, pentylphenyl-1-naphthylamine, hexylphenyl-1-naphthylamine,
heptylphenyl-1-naphthylamine, octylphenyl-1-naphthylamine, nonylphenyl-1-naphthylamine,
decylphenyl-1-naphthylamine, and dodecylphenyl-1-naphthylamine.
[0114] Examples of the molybdenum-based antioxidant include a molybdenum amine complex obtained
through a reaction between molybdenum trioxide and/or molybdic acid and an amine compound.
[0115] Examples of the sulfur-based antioxidant include dilauryl-3,3'-thiodipropionate.
[0116] Examples of the phosphorus-based antioxidant include a phosphite and diethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate.
[0117] In the lubricating oil composition of an embodiment of the present invention, from
the viewpoint of more improving the oxidation stability, a mass ratio [(E1)/(E2)]
of the component (E1) to the component (E2) is preferably 1/6 to 6/1, more preferably
1/5 to 5/1, still more preferably 1/4 to 4/1, and yet still more preferably 1/3.5
to 3.5/1.
[0118] In the lubricating oil composition of an embodiment of the present invention, the
total content of the components (E1) and (E2) based on the total amount (100% by mass)
of the component (E) which is contained in the lubricating oil composition is preferably
60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to
100% by mass, and yet still more preferably 90 to 100% by mass.
[0119] In the lubricating oil composition of an embodiment of the present invention, the
content (blending amount) of the component (E) based on the total amount (100% by
mass) of the lubricating oil composition is preferably 0.01 to 10.0% by mass, more
preferably 0.05 to 7.0% by mass, still more preferably 0.10 to 5.0% by mass, and yet
still more preferably 0.20 to 3.0% by mass.
[0120] In the lubricating oil composition in which the content of the component (B) as expressed
in terms of a zinc atom is 500 ppm by mass or more, even when the antioxidant (E)
is not blended, the effect for suppressing the sludge deposition can be made high.
[0121] For that reason, the lubricating oil composition may not contain the antioxidant
(E).
<Other Additives for Lubricating Oil>
[0122] The lubricating oil composition of an embodiment of the present invention may contain
other additives for lubricating oil not corresponding to the aforementioned components
(B) to (E) within a range where the effects of the present invention are not impaired.
[0123] Examples of the other additives for lubricating oil include a viscosity index improver,
a flow point depressant, an anti-wear agent, an extreme pressure agent, a metal-based
friction modifier, a rust inhibitor, a metal deactivator, a demulsifier, and an anti-foaming
agent.
[0124] Each of such additives for lubricating oil may be used alone or may be used in combination
of two or more thereof.
[0125] Though the content of each of such additives for lubricating oil can be properly
regulated within a range where the effects of the present invention are not impaired,
it is typically 0.001 to 15% by mass, preferably 0.005 to 10% by mass, and more preferably
0.01 to 8% by mass based on the total amount (100% by mass) of the lubricating oil
composition.
[0126] In this specification, taking into consideration handling properties and solubility
in the base oil (A), the additive, such as a viscosity index improver and an anti-foaming
agent, may be blended in a form of a solution having been diluted with and dissolved
in a part of the based oil (A), with other components. In such a case, in this specification,
the aforementioned content of the additive, such as an anti-foaming agent and a viscosity
index improver, means the content as expressed in terms of the effective component
excluding a diluent oil (expressed in terms of the resin content).
[0127] Examples of the viscosity index improver include polymers, such as a non-dispersant-type
polymethacrylate, a dispersant-type polymethacrylate, an olefin-based copolymer (for
example, an ethylene-propylene copolymer), a dispersant-type olefin-based copolymer,
and a styrene-based copolymer (for example, a styrene-diene copolymer and a styrene-isoprene
copolymer).
[0128] Though a weight average molecular weight (Mw) of such a viscosity index improver
is typically 500 to 1,000,000, preferably 5,000 to 100,000, and more preferably 10,000
to 50,000, it is properly set according to the kind of the polymer.
[0129] In this specification, the weight average molecular weight (Mw) of each of the components
is a value as expressed in terms of standard polystyrene as measured by means of gel
permeation chromatography (GPC).
[0130] Examples of the flow point depressant include ethylene-vinyl acetate copolymers,
condensation products of chloroparaffin and naphthalene, condensation products of
chloroparaffin and phenol, polymethacrylates, and polyalkylstyrenes.
[0131] Examples of the anti-wear agent or the extreme pressure agent include zinc phosphate
that is a phosphorus compound other than the component (B); sulfur-containing compounds,
such as zinc dithiocarbamate, molybdenum dithiocarbamate, molybdenum dithiophosphate,
disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates,
thiocarbamates, and polysulfides; phosphorus-containing compounds, such as phosphorous
acid esters, phosphoric acid esters, phosphonic acid esters, and amine salts or metal
salts thereof; and sulfur- and phosphorus-containing compounds, such as thiophosphorous
acid esters, thiophosphoric acid esters, thiophosphonic acid esters, and amine salts
or metal salts thereof.
[0132] Examples of the metal-based friction modifier include molybdenum-based friction modifiers,
such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and
amine salts of molybdic acid.
[0133] Examples of the rust inhibitor include fatty acids, alkenylsuccinic acid half esters,
fatty acid soaps, alkylsulfonic acid salts, polyhydric alcohol fatty acid esters,
fatty acid amines, oxidized paraffins, and alkyl polyoxyethylene ethers.
[0134] Examples of the metal deactivator include benzotriazole-based compounds, tolyltriazole-based
compounds, thiadiazole-based compounds, imidazole-based compounds, and pyrimidine-based
compounds.
[0135] Examples of the demulsifier include anionic surfactants, such as sulfuric acid ester
salts of castor oil and petroleum sulfonic acid salts; cationic surfactants, such
as quaternary ammonium salts and imidazolines; polyoxyalkylene polyglycols and dicarboxylic
acid esters thereof; and alkylene oxide adducts of an alkylphenol-formaldehyde polycondensate.
[0136] Examples of the anti-foaming agent include silicone oils, fluorosilicone oils, and
fluoroalkyl ethers.
[Various Properties of Lubricating Oil Composition]
[0137] A kinematic viscosity at 40°C of the lubricating oil composition of an embodiment
of the present invention is preferably 10 to 100 mm
2/s, more preferably 13 to 75 mm
2/s, and still more preferably 25 to 55 mm
2/s.
[0138] A viscosity index of the lubricating oil composition of an embodiment of the present
invention is preferably 100 or more, more preferably 120 or more, and still more preferably
130 or more.
[0139] The lubricating oil composition of the present invention not only has excellent oxidation
stability but also is favorable in an effect for suppressing the generation of squeal
and braking properties, and therefore, it is suitably applicable to machines equipped
with at least one of a wet type brake and a wet type clutch.
[0140] With respect to the lubricating oil composition of an embodiment of the present invention,
on the occasion of performing the "Test of Oxidation Stability of Lubricating Oils
for Internal Combustion Engine" (ISOT) in conformity with JIS K2514-1 at a test temperature
of 150°C for 168 hours, the amount of sludge generated after the test as measured
in conformity with JIS B9931 is preferably less than 2.0 mg/100 mL, more preferably
less than 1.5 mg/100 mL, and still more preferably less than 1.0 mg/100 mL.
[0141] It may be said that as the amount of sludge is lower, the lubricating oil composition
has more excellent oxidation stability even at a high temperature.
[0142] In this specification, the aforementioned amount of sludge means a value as measured
in conformity with the method described in the section of Examples as mentioned later.
[0143] With respect to the lubricating oil composition of an embodiment of the present invention,
on the occasion of performing a high-pressure piston pump test with a high-pressure
piston pump test apparatus (pump: BOSCH-REXROTH A2F10) in conformity with JCMAS P045
under a condition of a pump pressure of 35 MPa, a sample oil temperature of 80°C,
and an air blowing amount of 1.0 L/h for 500 hours, the amount of sludge generated
after the test as measured in conformity with JIS B9931 is preferably less than 3.0
mg/100 mL, more preferably less than 2.0 mg/100 mL, and still more preferably less
than 1.0 mg/100 mL.
[0144] It may be said that as the amount of sludge is lower, the lubricating oil composition
has more excellent oxidation stability even under a high pressure.
[0145] In this specification, the aforementioned amount of sludge means a value as measured
in conformity with the method described in the section of Examples as mentioned later.
[0146] With respect to the lubricating oil composition of an embodiment of the present invention,
on the occasion of measuring a kinematic friction coefficient at an oil temperature
of 80°C under a load of 0.5 MPa by using a low-speed slip test apparatus in conformity
with JASO M349, from the viewpoint of making the effect for suppressing the generation
of squeal and the braking properties favorable, a ratio of a kinematic friction coefficient
µ
1 at a rotational speed of 1 rpm to a kinematic friction coefficient µ
50 at a rotational speed of 50 rpm [µ
1/µ
50] is preferably 0.80 or more and less than 1.00, more preferably 0.80 or more and
less than 0.95, and still more preferably 0.81 or more and less than 0.90.
[0147] The kinematic friction coefficient µ
1 at a rotational speed of 1 rpm is preferably 0.100 or more and less than 0.150, more
preferably 0.105 or more and less than 0.140, and still more preferably 0.110 or more
and less than 0.130.
[0148] The kinematic friction coefficient µ
1 can be considered to be a kinematic coefficient just before stop, whereas the kinematic
friction coefficient µ
50 can be considered to be a kinematic coefficient during operation. The ratio [µ
1/µ
50] is a physical properties value serving as an index of the braking properties, and
so long as it falls within the aforementioned range, it may be said that the braking
properties are favorable.
[0149] In this specification, the aforementioned kinematic friction coefficient µ
1 and ratio [µ
1/µ
50] mean values as measured in conformity with the method described in the section of
Examples as mentioned above.
[0150] With respect to the lubricating oil composition of an embodiment of the present invention,
the wear amount of vanes and a cam ring as measured under a condition described in
the section of Examples as mentioned later in conformity with ASTM D2882 on the occasion
of driving a base pump (a product name: "V-104C", manufactured by Vickers) for 100
hours is preferably less than 40 mg, more preferably less than 36 mg, still more preferably
less than 30 mg, and yet still more preferably less than 25 mg.
[Application of Lubricating Oil Composition]
[0151] Even if the lubricating oil composition of the present invention is applied for lubrication
of a wet type brake or a wet type clutch, it is able to suppress the generation of
squeal and to make the braking properties favorable, and therefore, it is preferred
that the lubricating oil composition of the present invention is used for machines
equipped with a wet type brake or a wet type clutch and used as a hydraulic fluid
composition.
[0152] The machine is preferably a construction machinery, and more preferably a crane.
[0153] Examples of the construction machinery as referred to herein include cranes, such
as a mobile crane, a stationary crane, and a derrick; excavators, such as a hydraulic
excavator, a compact excavator, and a wheel type hydraulic excavator; land grading
machines, such as a bulldozer; loaders, such as a wheel loader; transporting machines,
such as a rough terrain hauler; compacting machines, such as a vibratory roller; dismantling
machines, such as a breaker; foundation work machines, such as a pile driver and an
earth auger; concrete/asphalt machines, such as a concrete pump vehicle; an elevating
work platform, a paving machine, a shielding machine, a boring machine, and a snow
blower.
[0154] Namely, since the lubricating oil composition of the present invention has excellent
braking properties, it is preferably a hydraulic fluid composition which is used for
construction machineries for which braking properties are especially required, and
specifically, it is more preferably a hydraulic fluid composition which is used for
cranes.
[0155] That is, the present invention may also provide the following machines and method
of using a lubricating oil composition.
- (1) A machine equipped with at least one of a wet type brake and a wet type clutch,
using a lubricating oil composition containing a base oil (A), zinc dithiophosphate
(B), a metal sulfonate (C), and an ashless friction modifier (D) containing a boronated
alkenyl succinimide (D1).
- (2) A method of using a lubricating oil composition, including using a lubricating
oil composition containing a base oil (A), zinc dithiophosphate (B), a metal sulfonate
(C), and an ashless friction modifier (D) containing a boronated alkenyl succinimide
(D1) for a machine equipped with at least one of a wet type brake and a wet type clutch.
[0156] Preferred embodiments of the lubricating oil composition as prescribed in the above
(1) and (2) are those as mentioned above.
[0157] The aforementioned machine is preferably a construction machinery, and more preferably
a crane.
[Production Method of Lubricating Oil Composition]
[0158] The present invention also provides a production method of a lubricating oil composition,
including the following step (I).
[0159] Step (I): A step of blending a base oil (A) with zinc dithiophosphate (B), a metal
sulfonate (C), and an ashless friction modifier (D) containing a boronated alkenyl
succinimide (D1).
[0160] The components (A), (B), (C), and (D) which are blended in the aforementioned step
(I), and the component (E) and the other additives for lubricating oil, which are
blended, as the need arises, are those as mentioned above, and the kinds of suitable
components and the content of each of the components are also those as mentioned above.
[0161] In the present step, the other additives for lubricating oil than these components
may also be blended at the same time.
[0162] Each of the components which are blended in the step (I) may be blended after being
converted into a form of a solution (dispersion) upon addition with a diluent oil
or the like. It is preferred that after blending the respective components, the blend
is stirred and uniformly dispersed by a known method.
Examples
[0163] Next, the present invention is described in more detail by reference to Examples,
but it should be construed that the present invention is by no means limited by these
Examples. Various properties of the respective components used in the Examples and
Comparative Examples and the obtained lubricating oil compositions were measured in
conformity with the following methods.
<Kinematic Viscosity at 40°C and 100°C>
[0164] Measured in conformity with JIS K2283.
<Viscosity Index>
[0165] Measured in conformity with JIS K2283.
<Content of Each of Zinc Atom, Calcium Atom, Boron Atom, and Phosphorus Atom>
[0166] Measured in conformity with JPI-5S-38-03.
<Content of Nitrogen Atom>
[0167] Measured in conformity with JIS K2609.
<Content of Sulfur Atom>
[0168] Measured in conformity with JIS K2541-6.
<Base Number (Perchloric Acid Method)>
[0169] Measured in conformity with JIS K2501.
<Weight Average Molecular Weight (Mw) and Number Average Molecular Weight (Mn)>
[0170] A value obtained by performing the measurement with a gel permeation chromatograph
("1260 Type HPLC", manufactured by Agilent) under the following condition and expressing
in terms of standard polystyrene was used.
(Measurement Condition)
[0171]
- Column: Two "Shodex LF404" columns connected in order
- Column temperature: 35°C
- Developing solvent: Chloroform
- Flow rate: 0.3 mL/min
Examples 1 to 3 and Comparative Examples 1 to 3
[0172] The following mineral oil and various additives were added in blending amounts shown
in Table 1 and thoroughly mixed to prepare lubricating oil compositions, respectively.
[0173] Details of the mineral oil and various additives used in the Examples and Comparative
Examples are as follows.
(Component (A))
[0174]
- "Mineral oil": Mixed mineral oil of 100N mineral oil grouped in Group 3 and 500N mineral
group in Group 2 by the API category ((100N mineral oil)/(500N mineral oil) = 86/14
(mass ratio)), kinematic viscosity at 40°C = 23.57 mm2/s, viscosity index = 118
(Component (B))
[0175]
- "ZnDTP": Zinc dialkyldithiophosphate (a compound represented by the general formula
(b-1), wherein R1 to R4 are each a 2-ethylhexyl group), content of zinc atom = 9.9% by mass, content of phosphorus
atom = 8.0% by mass, content of sulfur atom = 16.6% by mass
(Component (C))
[0176]
- "Ca sulfonate": Overbased calcium sulfonate, base number (perchloric acid method)
= 450 mgKOH/g, content of calcium atom = 20.0% by mass, content of sulfur atom = 1.4%
by mass
(Component (D1))
[0177]
- "Boronated alkenyl succinimide": Boronated product of polybutenyl succinic monoimide
having a polybutenyl group and having a number average molecular weight (Mn) of 1,000
(a boronated product of a compound represented by the general formula (d-11)), content
of boron atom = 3.1% by mass, content of nitrogen atom = 3.8% by mass, mass ratio
(B/N) of boron atom to nitrogen atom = 0.82
(Component (D2))
[0178]
- "Oleylamine": Primary unsaturated amine represented by the general formula (b-2),
wherein z1 = z2 = 8, content of nitrogen atom = 5.2% by mass (Component (E1))
- "Phenol-based antioxidant": 2,6-Di-t-butyl-4-methylphenol (DBPC)
(Component (E2))
[0179]
- "Amine-based antioxidant": Alkylated diphenylamine, content of nitrogen atom = 4.6%
by mass
(Other additives)
[0180]
- "Viscosity index improver": Polymethacrylate having a weight average molecular weight
(Mw) of 30,000 to 45,000
- "Other additives": Mixed additive of a flow point depressant, an extreme pressure
agent, a rust inhibitor, a copper deactivator, a demulsifier, and an anti-foaming
agent
[0181] With respect to the lubricating oil compositions prepared in the Examples and Comparative
Examples, the following tests were performed. The results thereof are shown in Table
1.
(1) Test of Oxidation Stability of Lubricating Oils for Internal Combustion Engine
(ISOT)
[0182] The test of oxidation stability of lubricating oils for internal combustion engine
(ISOT) in conformity with JIS K2514-1 was performed at a test temperature of 150°C
for 168 hours. Then, the amount of sludge generated after the test (mg/100 mL) was
measured in conformity with JIS B9931.
(2) High-Pressure Piston Pump Test
[0183] The high-pressure piston pump test with a high-pressure piston pump test apparatus
(pump: BOSCH-REXROTH A2F10) in conformity with JCMAS P045 was performed under a condition
of a pump pressure of 35 MPa, a sample oil temperature of 80°C, and an air blowing
amount of 1.0 L/h for 500 hours. Then, the amount of sludge generated after the test
(mg/100 mL) was measured in conformity with JIS B9931.
(3) Low-Speed Slip Friction Test
[0184] A kinematic friction coefficient µ
1 at a rotational speed of 1 rpm and a kinematic friction coefficient µ
50 at a rotational speed of 50 rpm were measured with a low-speed slip test apparatus
(a product name: "L.V.F.A", manufactured by Automax Co., Ltd.) in conformity with
JASO M349-12 under a condition of an oil temperature of 80°C and a load of 0.5 MPa.
Then, a ratio of the kinematic friction coefficient µ
1 to the kinematic friction coefficient µ
50 [µ
1/µ
50] was calculated.
(4) Vane Pump Wear Test
[0185] Using a vane pump (a product name: "V-104C", manufactured by Vickers), on the occasion
of driving for 100 hours in conformity with ASTM D2882 under a condition of a pump
pressure of 13.8 MPa, an oil temperature of 66°C, a rotational speed of 1,200 rpm,
a sample oil amount of 60 L, and a flow rate of 25 L/min, the wear amount (unit: mg)
of vanes and a cam ring was measured.
[0186] From Table 1, the lubricating oil compositions prepared in Examples 1 to 3 are low
in the amount of sludge in the ISOT and the high-pressure piston pump test, and therefore,
it may be said that the lubricating oil compositions prepared in Examples 1 to 3 are
high in the oxidation stability at a high temperature and a high pressure. In addition,
in the lubricating oil compositions prepared in Examples 1 to 3, in view of the fact
that the µ
1/µ
50 value is 0.80 or more and less than 1.00, it may be said that the effect for suppressing
the generation of squeal is high, and the braking properties are favorable. Furthermore,
the lubricating oil compositions prepared in Examples 1 to 3 are also excellent in
the wear resistance.
[0187] On the other hand, in the lubricating oil compositions prepared in Comparative Examples
1 to 3, since the µ
1/µ
50 value is low, it may be said that the squeal is liable to be generated, and the braking
properties are problematic; and in addition, there were brought such results that
the wear resistance is inferior as compared with Examples 1 to 3.