U.S. patent application number 16/632695 was filed with the patent office on 2021-05-06 for lubricating oil composition.
This patent application is currently assigned to IDEMITSU KOSAN CO., LTD.. The applicant listed for this patent is IDEMITSU KOSAN CO., LTD.. Invention is credited to Hiroki SEKIGUCHI.
Application Number | 20210130730 16/632695 |
Document ID | / |
Family ID | 1000005345369 |
Filed Date | 2021-05-06 |
United States Patent
Application |
20210130730 |
Kind Code |
A1 |
SEKIGUCHI; Hiroki |
May 6, 2021 |
LUBRICATING OIL COMPOSITION
Abstract
Provided is a lubricating oil composition for use in
turbomachinery, compressors, hydraulic equipments, or machine
tools, which contains a mineral oil (A) and a synthetic oil (B)
containing a polyalkylene glycol (B1) and a polyol ester (B2), in
which the content of the mineral oil (A) is 5 to 95% by mass based
on the total amount of the lubricating oil composition, and which
is used in turbomachinery, compressors, hydraulic equipments, or
machine tools. The lubricating oil composition is excellent in
oxidation stability, has a strong effect of preventing sludge
precipitation and has excellent water separability even in use for
a long period of time in high-temperature environments.
Inventors: |
SEKIGUCHI; Hiroki;
(Ichihara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDEMITSU KOSAN CO., LTD. |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
IDEMITSU KOSAN CO., LTD.
Chiyoda-ku
JP
|
Family ID: |
1000005345369 |
Appl. No.: |
16/632695 |
Filed: |
February 15, 2019 |
PCT Filed: |
February 15, 2019 |
PCT NO: |
PCT/JP2019/005711 |
371 Date: |
January 21, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 101/00 20130101;
C10M 137/04 20130101; C10M 2223/041 20130101; C10M 2215/26
20130101; C10N 2030/40 20200501; C10M 2223/043 20130101; C10M
105/38 20130101; C10M 141/10 20130101; C10M 2223/047 20130101; C10M
2203/003 20130101; C10N 2040/30 20130101; C10M 137/08 20130101;
C10M 169/04 20130101; C10N 2040/08 20130101; C10M 133/12 20130101;
C10M 107/34 20130101; C10M 111/04 20130101; C10M 137/105 20130101;
C10M 2209/1065 20130101; C10M 2207/2835 20130101; C10N 2030/10
20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04; C10M 111/04 20060101 C10M111/04; C10M 101/00 20060101
C10M101/00; C10M 107/34 20060101 C10M107/34; C10M 105/38 20060101
C10M105/38; C10M 133/12 20060101 C10M133/12; C10M 137/04 20060101
C10M137/04; C10M 137/08 20060101 C10M137/08; C10M 137/10 20060101
C10M137/10; C10M 141/10 20060101 C10M141/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2018 |
JP |
2018-026369 |
Claims
1. A lubricating oil composition comprising a mineral oil (A) and a
synthetic oil (B) that comprises a polyalkylene glycol (B1) and a
polyol ester (B2); in which the content of the mineral oil (A) is
from 5 to 95% by mass based on the total amount of the lubricating
oil composition, and which is used in turbomachinery, compressors,
hydraulic equipments, or machine tools.
2. The lubricating oil composition according to claim 1, wherein
the content ratio of the component (B1) to the component (B2)
[(B1)/(B2)] is, by mass, from 10/90 to 80/20.
3. The lubricating oil composition according to claim 1, wherein
the content ratio of the component (A) to the total content of the
component (B1) and the component (B2) [(A)/((B1).+-.(B2))] is, by
mass, from 0.05 to 19.0.
4. The lubricating oil composition according to claim 3, further
comprising an antioxidant (C) that comprises an amine-type
antioxidant (C1).
5. The lubricating oil composition according to claim 4, wherein
the nitrogen atom-equivalent content of the component (C1) is,
based on the total amount of the lubricating oil composition, from
50 to 3,000 ppm by mass.
6. The lubricating oil composition according to claim 1, further
comprising one or more phosphorus compounds (D) selected from a
neutral phosphate (D1), an acid phosphate (D2), an acid phosphate
amine salt (D3) and a sulfur-phosphorus compound (D4).
7. The lubricating oil composition according to claim 6, wherein
the phosphorus atom-equivalent content of the component (D) is,
based on the total amount of the lubricating oil composition, from
10 to 1,600 ppm by mass.
8. The lubricating oil composition according to claim 1, wherein
the metal atom content is, based on the total amount of the
lubricating oil composition, less than 100 ppm by mass.
9. The lubricating oil composition according to claim 1, wherein,
when the lubricating oil composition is tested in a water
separability test at a temperature of 54.degree. C. according to
JIS K2520, the demulsibility degree that indicates a time to be
taken for an emulsion layer to reach 3 mL is 15 minutes or
less.
10. A method of using a lubricating oil composition, using the
lubricating oil composition of claim 1 in turbomachinery,
compressors, hydraulic equipments, or machine tools.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lubricating oil
composition used in turbomachinery, compressors, hydraulic
equipments, or machine tools, and a method of using the lubricating
oil composition.
BACKGROUND ART
[0002] A lubricating oil composition for use in instruments
including various turbomachinery such as steam turbines and gas
turbines, compressors such as rotary gas compressors and
reciprocating compressors, hydraulic equipments, and hydraulic
units of machine tools is used while circulating in a
high-temperature environment system for a long period of time.
[0003] When the lubricating oil composition is used for a long time
under high temperature environments, it is susceptible to sludge
precipitation according to oxidative deterioration. The
precipitated sludge adheres to, for example, a bearing of a rotor
to generate heat, thereby providing a risk of bearing damage, or
may clog a filter arranged in a circulation line, or may deposit on
a control valve, thereby often causing control system operation
failures, etc.
[0004] Therefore, improvement in the effect of preventing sludge
precipitation is required for the lubricating oil composition which
is used while circulating in a high-temperature environment system
for a long period of time.
[0005] For example, PTL 1 discloses a lubricating oil composition
for air compressors, the composition including a synthetic base oil
which is a mixed oil of a polyglycol-based synthetic oil and an
ester-based synthetic oil, and one or more amine-based antioxidants
selected from a specific compound group such as asymmetric
diphenylamine-based compounds.
[0006] According to PTL 1, the lubricating oil composition for air
compressors shows a result of preventing sludge precipitation while
appropriately preventing oxidation.
CITATION LIST
Patent Literature
[0007] PTL 1: WO2013/146805
SUMMARY OF INVENTION
Technical Problem
[0008] However, a lubricating oil composition used in instruments
such as turbines which may be contaminated with water or steam is
emulsified by contamination with water or steam, which is a factor
causing troubles in instruments.
[0009] For this reason, the lubricating oil composition used in
such instruments is required to be hardly emulsified and to be
easily separated from water even when emulsified, that is, to be
excellent in water separability.
[0010] In PTL 1, studies have not been conducted on water
separability of the lubricating oil composition.
[0011] An object of the present invention is to provide a
lubricating oil composition excellent in oxidation stability and
having a strong effect of preventing sludge precipitation even when
used for a long period of time under high temperature environments,
and having excellent water separability, wherein the lubricating
oil composition is used in turbomachinery, compressors, hydraulic
equipments, or machine tools.
Solution to Problem
[0012] The present inventors have found that a lubricating oil
composition containing a mixed base oil that contains a combination
of a predetermined mineral oil and a synthetic oil containing a
polyalkylene glycol (hereinafter also referred to as "PAG") and a
polyol ester (hereinafter also referred to as "POE") can solve the
above-mentioned problems and have completed the present
invention.
[0013] That is, the present invention provides the following [1]
and [2].
[1] A lubricating oil composition containing a mineral oil (A) and
a synthetic oil (B) that contains a polyalkylene glycol (B1) and a
polyol ester (B2);
[0014] in which the content of the mineral oil (A) is from 5 to 95%
by mass based on the total amount of the lubricating oil
composition, and
[0015] which is used in turbomachinery, compressors, hydraulic
equipments, or machine tools.
[2] A method of using a lubricating oil composition, using the
lubricating oil composition of the above [1] in turbomachinery,
compressors, hydraulic equipments, or machine tools.
Advantageous Effects of Invention
[0016] The lubricating oil composition of the present invention is
excellent in oxidation stability, has a strong effect of preventing
sludge precipitation and has excellent water separability, even
when used for a long period of time under high temperature
environments. Consequently, the lubricating oil composition is
suitable for use in turbomachinery, compressors, hydraulic
equipments, or machine tools.
DESCRIPTION OF EMBODIMENTS
[0017] In the following description, kinematic viscosity and
viscosity index mean values measured and calculated in accordance
with JIS K2283:2000.
[0018] The content of a phosphorus atom or a metal atom means a
value measured in accordance with JPI-5S-38-92.
[0019] The content of a nitrogen atom means a value measured in
accordance with JIS K2609.
[Lubricating Oil Composition]
[0020] The lubricating oil composition of the present invention is
used in turbomachinery, compressors, hydraulic equipments, or
machine tools, and contains a mineral oil (A) and a synthetic oil
(B) that contains a polyalkylene glycol (PAG) (B1) and a polyol
ester (POE) (B2).
[0021] The lubricating oil composition of the present invention
uses, as a base oil, a mixed base oil containing a synthetic oil
that contains PAG and POE, along with a mineral oil (A), and
therefore can be excellent in oxidation stability, can have a
strong effect of preventing sludge precipitation and can have
excellent water separability, even when used for a long period of
time under high temperature environments.
[0022] Mineral oil is excellent in water separability but is poor
in oxidation stability in high-temperature environments and readily
forms deterioration materials, and the deterioration materials
precipitate as sludge to cause system troubles.
[0023] PAG has a property that dissolves deterioration materials to
form in high-temperature environments and therefore prevents
precipitation of the deterioration materials as sludge, but has a
problem in water separability. In addition, since the polarity
thereof is too high, PAG is poor in compatibility with an apolar
base oil such as mineral oil, and therefore in a mixed base oil of
a mineral oil and PAG, the two oils could hardly exhibit a property
of compensating for their drawbacks.
[0024] On the other hand, POE is poorer than PAG in point of
solubility of deterioration materials that form in high-temperature
environments, but has a property of being excellent in
compatibility with other base oils, and is therefore well
compatible with both PAG and mineral oil. However, POE is also
problematic in point of water separability.
[0025] Consequently, in the present invention, three kinds of base
oils, mineral oil, PAG and POE are combined to provide a
lubricating oil composition capable of expressing both the
characteristic of "mineral oil" excellent in water separability and
the characteristic of "PAG" capable of dissolving deterioration
materials to form in high-temperature environments, in a
well-balanced manner.
[0026] In the case where a base oil containing PAG and POE but not
containing a mineral oil is used, it still has a problem in point
of water separability, and when any other additive is added
thereto, the water separability of the resultant base oil tends to
further decrease.
[0027] On the other hand, in the case where a base oil containing a
mineral oil and POE but not containing PAG is used, the base oil is
poorer than PAG alone in point of the ability to dissolve
deterioration materials to form in high-temperature
environments.
[0028] Further, in the case where a base oil containing a mineral
oil and PAG but not containing POE is used, the compatibility
between the mineral oil and PAG is poor, and therefore the
characteristic that the mineral oil has and the characteristic that
PAG has could be hardly expressed.
[0029] In other words, in the present invention, three kinds of
base oils, mineral oil, PAG and POE are combined, and therefore,
while taking advantages of their own characteristics, it is
possible to compensate for the disadvantageous of the individual
base oil components by the other constituent base oils.
[0030] As a result, the lubricating oil composition of the present
invention is excellent in oxidation stability, has a strong effect
of preventing sludge precipitation and has excellent water
separability, even in use for a long period of time in
high-temperature environments.
[0031] From the viewpoint of providing such a lubricating oil
composition that is excellent in oxidation stability and has a
strong effect of preventing sludge precipitation even in use for a
long period of time in high-temperature environments, a lubricating
oil composition of one embodiment of the present invention
preferably further contains an antioxidant (C) containing an
amine-based antioxidant (C1).
[0032] Also from the viewpoint of improving wear resistance, a
lubricating oil composition of one embodiment of the present
invention preferably further contains one or more phosphorus
compounds (D) selected from a neutral phosphate (D1), an acid
phosphate (D2) and an acid phosphate amine salt (D3).
[0033] With that, a lubricating oil composition of one embodiment
of the present invention may contain any other lubricating oil
additives than the components (C) and (D) within a range not
detracting from the advantageous effects of the present
invention.
[0034] In the lubricating oil composition of one embodiment of the
present invention, the total content of the components (A) and (B)
is, based on the total amount (100% by mass) of the lubricating oil
composition, generally 65% by mass or more, preferably 70% by mass
or more, more preferably 80% by mass or more, even more preferably
90% by mass or more, further more preferably 95% by mass or more,
and is generally 100% by mass or less, preferably 99.9% by mass or
less.
[0035] In the lubricating oil composition of one embodiment of the
present invention, the total content of the components (A), (B),
(C) and (D) is, based on the total amount (100% by mass) of the
lubricating oil composition, preferably 70 to 100% by mass, more
preferably 80 to 100% by mass, even more preferably 90 to 100% by
mass, further more preferably 97 to 100% by mass.
[0036] The components contained in the lubricating oil composition
of one embodiment of the present invention are described below.
<Mineral Oil (A)>
[0037] Examples of the mineral oil (A) for use in the present
invention include topped crudes obtained through atmospheric
distillation of crude oils such as paraffin-based crude oils,
intermediate-based crude oils and naphthene-based crude oils;
distillates obtained through reduced-pressure distillation of such
topped crudes; mineral oils obtained by purifying the distillates
through one or more purification treatments of solvent
deasphalting, solvent extraction, hydrocracking, solvent dewaxing,
catalytic dewaxing, or hydrorefining; and mineral oil waxes
obtained by isomerizing a wax produced from a natural gas through
Fischer-Tropsch synthesis (GTL wax (Gas To Liquids WAX)).
[0038] One alone or two or more kinds of these mineral oils may be
used either singly or as combined.
[0039] The mineral oil (A) for use in one embodiment of the present
invention is preferably a mineral oil grouped in Group 2 or 3 in
the base oil category of API (American Petroleum Institute).
[0040] The kinematic viscosity at 40.degree. C. of the mineral oil
(A) for use in one embodiment of the present invention is
preferably 8 to 350 mm.sup.2/s, more preferably 10 to 150
mm.sup.2/s, even more preferably 12 to 100 mm.sup.2/s, further more
preferably 15 to 68 mm.sup.2/s.
[0041] The viscosity index of the mineral oil (A) for use in one
embodiment of the present invention is preferably 80 or more, more
preferably 90 or more, even more preferably 100 or more.
[0042] In the lubricating oil composition of the present invention,
the content of the component (A) is, based on the total amount
(100% by mass) of the lubricating oil composition, 5 to 95% by
mass, preferably 10 to 95% by mass, more preferably 20 to 93% by
mass, even more preferably 40 to 92% by mass, further more
preferably 60 to 90% by mass.
[0043] When the content of the component (A) is less than 5% by
mass, the lubricating oil composition is poor in water separability
and especially when various additives are added thereto, reduction
in water separability of the composition may be greater.
[0044] On the other hand, when the content of the component (A) is
more than 95% by mass, the content of the components (B1) and (B2)
could not be secured sufficiently and, if so, sludge precipitation
readily occurs in high-temperature environments and the lubricating
oil composition is poor in oxidation stability.
[0045] In the lubricating oil of one embodiment of the present
invention, the content ratio of the component (A) to the total
content of the component (B1) and the component (B2)
[(A)/(B1)+(B2)] is, by mass, from the viewpoint of providing a
lubricating oil composition excellent in water separability,
preferably 0.05 or more, more preferably 0.10 or more, even more
preferably 0.30 or more, further more preferably 0.70 or more,
further more preferably 1.50 or more, especially more preferably
3.50 or more, and is, from the viewpoint of providing a lubricating
oil composition excellent in oxidation stability and having a
strong effect of preventing sludge precipitation even in use for a
long period of time in high-temperature environments, preferably
19.0 or less, more preferably 15.0 or less, even more preferably
12.0 or less.
<Synthetic Oil (B)>
[0046] The synthetic oil (B) contained in the lubricating oil
composition of the present invention contains a polyalkylene glycol
(B1) and a polyol ester (B2).
[0047] The synthetic oil (B) for use in one embodiment of the
present invention may further contain any other synthetic oil than
the components (B1) and (B2) within a range not detracting from the
advantageous effects of the present invention.
[0048] However, in the lubricating oil composition of one
embodiment of the present invention, the total content of the
components (B1) and (B2) in the synthetic oil (B) is, based on the
total amount (100% by mass) of the synthetic oil (B) contained in
the lubricating oil composition, preferably 70 to 100% by mass,
more preferably 80 to 100% by mass, even more preferably 90 to 100%
by mass, further more preferably 95 to 100% by mass.
[0049] In the lubricating oil composition of one embodiment of the
present invention, the content ratio of the component (B1) to the
component (B2) [(B1)/(B2)] is, by mass, from the viewpoint of
providing a lubricating oil composition excellent in oxidation
stability and having a strong effect of preventing sludge
precipitation even in use for a long period of time in
high-temperature environments, preferably 10/90 to 80/20, more
preferably 15/85 to 70/30, even more preferably 20/80 to 60/40,
further more preferably 25/75 to 55/45.
[0050] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (B) is, based on
the total amount (100% by mass) of the lubricating oil composition,
from the viewpoint of providing a lubricating oil composition
excellent in oxidation stability and having a strong effect of
preventing sludge precipitation even in use for a long period of
time in high-temperature environments, preferably 5% by mass or
more, more preferably 6% by mass or more, even more preferably 7%
by mass or more, further more preferably 8% by mass or more, and
is, from the viewpoint of providing a lubricating oil composition
excellent in water separability, preferably 95% by mass or less,
more preferably 90% by mass or less, even more preferably 80% by
mass or less, further more preferably 60% by mass or less, further
more preferably 40% by mass or less, especially more preferably 20%
by mass or less.
[Polyalkylene Glycol (B1)]
[0051] Examples of the polyalkylene glycol (B1) include polymers
obtained by polymerization or copolymerization of alkylene
oxide.
[0052] Further, the polyalkylene glycol (B1) may be used alone or
in combination of two or more kinds thereof.
[0053] A number average molecular weight (Mn) of the polyalkylene
glycol (B1) used in one embodiment of the present invention is
preferably 200 to 10,000, more preferably 240 to 5,000, still more
preferably 280 to 3,000, and even still more preferably 320 to
1,500 from the viewpoint of improving the viscosity index of the
lubricating oil composition.
[0054] In this description, the number average molecular weight
(Mn) is a value as expressed in terms of standard polystyrene,
measured by gel permeation chromatography (GPC), and measurement
conditions include conditions described in Examples.
[0055] Further, the polyalkylene glycol (B1) used in one embodiment
of the present invention is preferably a polyalkylene glycol in
which at least one end is sealed with a substituent, from the
viewpoint of providing a lubricating oil composition which is
further improved in the effect of preventing sludge
precipitation.
[0056] Examples of the substituent capable of sealing the end of
the polyalkylene glycol include a monovalent hydrocarbon group
having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon
atoms, or a heterocyclic group having 3 to 10 ring atoms, and
preferably, a monovalent hydrocarbon group having 1 to 10 carbon
atoms.
[0057] Further, examples of specific groups regarding the
monovalent hydrocarbon group, acyl group, and heterocyclic group
that can be selected as the substituent, and the range of the
preferable number of the carbon atoms or ring atoms is the same as
defined in R.sup.B1 and R.sup.B3 in the following formula
(b-1).
[0058] In one embodiment of the present invention, the polyalkylene
glycol (B1) is preferably a compound represented by the following
general formula (b-1), from the viewpoint of providing a
lubricating oil composition which is further improved in the effect
of preventing sludge precipitation.
R.sup.B1--[(OR.sup.B2).sub.n--OR.sup.B3].sub.b (b-1)
[0059] In the general formula (b-1), R.sup.B1 is a hydrogen atom, a
monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl
group having 2 to 10 carbon atoms, a divalent to hexavalent
hydrocarbon group having 1 to 10 carbon atoms, or a heterocyclic
group having 3 to 10 ring atoms.
[0060] R.sup.B2 is an alkylene group having 2 to 4 carbon
atoms.
[0061] R.sup.B3 is a hydrogen atom, a monovalent hydrocarbon group
having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon
atoms, or a heterocyclic group having 3 to 10 ring atoms.
[0062] b is an integer of 1 to 6, preferably an integer of 1 to 4,
more preferably 1 to 3, and still more preferably 1.
[0063] Further, b is determined according to the number of the
binding site with R.sup.B1 in the general formula (b-1).
[0064] For example, when R.sup.B1 is a monovalent hydrocarbon group
such as an alkyl group or a cycloalkyl group, or an acyl group, b
is 1. In other words, when R.sup.B1 is a hydrocarbon group or a
heterocyclic group, and the valence of the group is 1, 2, 3, 4, 5,
and 6, b is 1, 2, 3, 4, 5 and 6, respectively.
[0065] a is a number of 1 or more, and is a value appropriately
determined according to the value of the number average molecular
weight of the compound represented by the general formula
(b-1).
[0066] Further, when two or more different kinds of the compound
represented by general formula (b-1) are used, a is an average
value (a weighted average value), and the average value may be 1 or
more.
[0067] Further, when there are a plurality of R.sup.B2 and
R.sup.B3, R.sup.B2 and R.sup.B3 may be the same as or different
from each other.
[0068] In one embodiment of the present invention, at least one of
R.sup.B1 and R.sup.B3 in the general formula (b-1) is preferably a
monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl
group having 2 to 10 carbon atoms, a divalent to hexavalent
hydrocarbon group having 1 to 10 carbon atoms, or a heterocyclic
group having 3 to 10 ring atoms, and more preferably a monovalent
hydrocarbon group having 1 to 10 carbon atoms.
[0069] Examples of the monovalent hydrocarbon group having 1 to 10
carbon atoms which can be selected as R.sup.B1 and R.sup.B3 include
alkyl groups such as a methyl group, an ethyl group, a propyl group
(a n-propyl group, an isopropyl group), a butyl group (a n-butyl
group, an isobutyl group, an s-butyl group, a t-butyl group), a
pentyl group, a hexyl group, a heptyl group, an octyl group, a
nonyl group, and a decyl group; cycloalkyl groups such as a
cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, an
ethylcyclohexyl group, a propylcyclohexyl group, and a dimethyl
cyclohexyl group; aryl groups such as a phenyl group, a
methylphenyl group, an ethylphenyl group, a dimethyl phenyl group,
a propyl phenyl group, a trimethylphenyl group, a butylphenyl
group, and a naphthyl group; arylalkyl groups such as a benzyl
group, a phenylethyl, a methylbenzyl group, a phenylpropyl group,
and a phenylbutyl group.
[0070] Further, the alkyl group may be either linear or
branched.
[0071] The number of carbon atoms of the monovalent hydrocarbon
group is preferably 1 to 10, more preferably 1 to 6, and still more
preferably 1 to 4.
[0072] The hydrocarbon group moiety in the acyl group having 2 to
10 carbon atoms which can be selected as R.sup.B1 and R.sup.B3 may
be linear, branched, or cyclic. The hydrocarbon group moiety
includes those having 1 to 9 carbon atoms among the monovalent
hydrocarbon groups which can be selected as R.sup.B1 and
R.sup.B3.
[0073] Further, the number of carbon atoms of the acyl group is
preferably 2 to 10, and more preferably 2 to 6.
[0074] The divalent to hexavalent hydrocarbon group which can be
selected as R.sup.B1 includes residues obtained by removing 1 to 5
hydrogen atoms from the monovalent hydrocarbon group which can be
selected as R.sup.B1 and residues obtained by removing a hydroxy
group from polyhydric alcohols, such as trimethylolpropane,
glycerin, pentaerythritol, sorbitol, 1,2,3-trihydroxycyclohexane,
and 1,3,5-trihydroxycyclohexane.
[0075] Further, the number of carbon atoms of the divalent to
hexavalent hydrocarbon group is preferably 1 to 10, more preferably
1 to 6, and still more preferably 1 to 4.
[0076] The heterocyclic group having 3 to 10 ring atoms which can
be selected as R.sup.B1 and R.sup.B3 is preferably an oxygen
atom-containing heterocyclic group or a sulfur atom-containing
heterocyclic group. Further, the heterocyclic group may be a
saturated ring or an unsaturated ring.
[0077] Examples of the oxygen atom-containing heterocyclic group
include residues obtained by removing 1 to 6 hydrogen atoms from an
oxygen atom-containing saturated heterocyclic ring, such as
1,3-propylene oxide, tetrahydrofuran, tetrahydropyran, and
hexamethylene oxide, and an oxygen atom-containing unsaturated
heterocyclic ring, such as acetylene oxide, furan, pyran,
oxycycloheptatriene, isobenzofuran, and isochromene.
[0078] Examples of the sulfur atom-containing heterocyclic group
include residues obtained by removing 1 to 6 hydrogen atoms from a
sulfur atom-containing saturated heterocyclic ring, such as
ethylene sulfide, trimethylene sulfide, tetrahydrothiophene,
tetrahydrothiopyran, and hexamethylene sulfide, and a sulfur
atom-containing unsaturated heterocyclic ring, such as acetylene
sulfide, thiophene, thiapyran, and thiotripyridene.
[0079] The number of ring atoms of the heterocyclic group is
preferably 3 to 10, more preferably 3 to 6, and still more
preferably 5 or 6.
[0080] Examples of the alkylene group having 2 to 4 carbon atoms
that can be selected as R.sup.B2 include an alkylene group having 2
carbon atoms, such as an ethylene group (--CH.sub.2CH.sub.2--); an
alkylene group having 3 carbon atoms, such as a trimethylene group
(--CH.sub.2CH.sub.2CH.sub.2--), a 1-methylethylene group (a
propylene group) (--CH(CH.sub.3)CH.sub.2--); and an alkylene group
having 4 carbon atoms, such as a tetramethylene group
(--CH.sub.2CH.sub.2CH.sub.2CH.sub.2--), a 1-methyltrimethylene
group (--CH(CH.sub.3)CH.sub.2CH.sub.2--), a 2-methyltrimethylene
group (--CH.sub.2CH(CH.sub.3)CH.sub.2--), a butylene group
(--C(CH.sub.3).sub.2CH.sub.2--), a 1-ethylethylene group
(--CH(CH.sub.2CH.sub.3)CH.sub.2--, and a 1,2-dimethylethylene group
(--CH(CH.sub.3)--CH(CH.sub.3)--).
[0081] Further, when there are a plurality of R.sup.B2's,
R.sup.B2's may be the same as each other or may be a combination of
two or more kinds of alkylene groups.
[0082] Among them, R.sup.B2 is preferably an ethylene group
(--CH.sub.2CH.sub.2--) or a 1-methylethylene group (propylene
group) (--CH(CH.sub.3)CH.sub.2--).
[0083] In the compound represented by the general formula (b-1),
the content of the oxypropylene unit (--OCH(CH.sub.3)CH.sub.2--) is
preferably 50% by mol to 100% by mol, more preferably 65% by mol to
100% by mol, and still more preferably 80% by mol to 100% by mol,
based on the total amount (100% by mol) of the oxyalkylene unit
(OR.sup.B2) in the structure of the compound.
[0084] The kinematic viscosity at 40.degree. C. of the component
(B1) used in one embodiment of the present invention is preferably
8 mm.sup.2/s to 350 mm.sup.2/s, more preferably 10 mm.sup.2/s to
150 mm.sup.2/s, still more preferably 12 mm.sup.2/s to 100
mm.sup.2/s, and even still more preferably 15 mm.sup.2/s to 68
mm.sup.2/s.
[0085] Further, the viscosity index of the component (B1) used in
one embodiment of the present invention is preferably 90 or more,
more preferably 100 or more, still more preferably 120 or more, and
even still more preferably 140 or more.
[0086] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (B1) is, based on
the total amount (100% by mass) of the lubricating oil composition,
preferably 1.0 to 70% by mass, more preferably 1.2 to 50% by mass,
even more preferably 1.4 to 30% by mass, further more preferably
1.5 to 20% by mass, further more preferably 1.7 to 12% by mass, and
especially more preferably 1.9 to 6% by mass.
[Polyol Ester (B2)]
[0087] Examples of the polyol ester (B2) include a hindered ester
of a hindered polyol, which has one or more quaternary carbon atoms
in the molecule wherein at least one of the quaternary carbon atoms
has 1 to 4 methylol groups bonded thereto, with an aliphatic
monocarboxylic acid.
[0088] The polyol ester (B2) may be used alone or in combination of
two or more kinds thereof.
[0089] Further, the polyol ester (B2) is generally a complete ester
in which all the hydroxy groups of the polyol are esterified, but
may include a partial ester in which some of the hydroxy groups
remain unesterified, as long as the effects of the present
invention are not impaired.
[0090] The hindered polyol is preferably a compound represented by
the following general formula (b-2).
##STR00001##
[0091] In the general formula (b-2), R.sup.B11 and R.sup.B12 are
each independently a monovalent hydrocarbon group having 1 to 6
carbon atoms or a methylol group (--CH.sub.2OH).
[0092] n represents an integer of 0 to 4, preferably 0 to 2, more
preferably 0 or 1, and still more preferably 0. When n=0, it is a
single bond and provides a compound represented by the following
general formula (b-2').
##STR00002##
[0093] In the general formula (b-2'), R.sup.B11 and R.sup.B12 each
independently represent a monovalent hydrocarbon group having 1 to
6 carbon atoms or a methylol group (--CH.sub.2OH).
[0094] Examples of the monovalent hydrocarbon group having 1 to 6
carbon atoms which can be selected as R.sup.B11 and R.sup.B12
include alkyl groups having 1 to 6 carbon atoms (a methyl group, an
ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl
group), a cyclopentyl group, a cyclohexyl group, and a phenyl
group.
[0095] Further, the alkyl group may be either linear or
branched.
[0096] Among them, the monovalent hydrocarbon group having 1 to 6
carbon atoms which can be selected as R.sup.B11 and R.sup.B12 is
preferably an alkyl group having 1 to 6 carbon atoms, and more
preferably an alkyl group having 1 to 3 carbon atoms.
[0097] Examples of the compound represented by the following
general formula (b-2) include a hindered polyol such as a
dialkylpropanediol (wherein the alkyl group has 1 to 6 carbon
atoms), a trimethylolalkane (wherein the alkane has 2 to 7 carbon
atoms), and a pentaerythritol, and a dehydrated condensate thereof,
and more specifically, neopentyl glycol,
2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl 1,3-propanediol,
trimethylolethane, trimethylolpropane, trimethylolbutane,
trimethylolpentane, trimethylolhexane, trimethylolheptane,
pentaerythritol, 2,2,6,6-tetramethyl-4-oxa-1,7-heptanediol,
2,2,6,6,10,10-hexamethyl-4,8-dioxa-1,11-undecadiol,
2,2,6,6,10,10,14,14-octamethyl-4,8,12-trioxa-1,15-pentadecadiol,
2,6-di(hydroxymethyl)-2,6-dimethyl-4-oxa-1,7-heptanediol,
2,6,10-tri(hydroxymethyl)-2,6,10-trimethyl-4,8-dioxa-1,11-undecadiol,
2,6,10,14-tetra(hydroxymethyl)-2,6,10,14-tetramethyl-4,8,12-trioxa-1,15-p-
entadecadiol, di(pentaerythritol), tri(pentaerythritol),
tetra(pentaerythritol), and penta(pentaerythritol).
[0098] Among them, trimethylolpropane, neopentyl glycol,
pentaerythritol, and bimolecular or trimolecular dehydrated
condensates thereof are preferred, and trimethylolpropane,
neopentyl glycol, and pentaerythritol are more preferred, and
trimethylolpropane is still more preferred.
[0099] The aliphatic monocarboxylic acid includes a saturated
aliphatic monocarboxylic acid having 5 to 22 carbon atoms.
[0100] The acyl group of the saturated aliphatic monocarboxylic
acid may be either linear or branched.
[0101] Examples of the saturated aliphatic monocarboxylic acid
include a linear saturated monocarboxylic acid such as valeric
acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid,
capric acid, undecanoic acid, lauric acid, tridecanoic acid,
myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic
acid, stearic acid, nonadecanoic acid, arachic acid, and behenic
acid; and a branched saturated monocarboxylic acid such as
isomyristic acid, isopalmitic acid, isostearic acid,
2,2-dimethylpropanoic acid, 2,2-dimethylbutanoic acid,
2,2-dimethylpentanoic acid, 2,2-dimethyloctanoic acid,
2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,3,4-tetramethylpentanoic
acid, 2,5,5-trimethyl-2-t-butylhexanoic acid,
2,3,3-trimethyl-2-ethylbutanoic acid,
2,3-dimethyl-2-isopropylbutanoic acid, 2-ethylhexanoic acid, and
3,5,5-trimethylhexanoic acid.
[0102] In esterification, these aliphatic monocarboxylic acids may
be used alone or in combination of two or more kinds thereof.
[0103] The number of carbon atoms of the saturated aliphatic
monocarboxylic acid is preferably 5 to 18, more preferably 6 to 14,
and still more preferably 8 to 10.
[0104] The kinematic viscosity at 40.degree. C. of the polyol ester
(B2) used in one embodiment of the present invention is preferably
8 mm.sup.2/s to 350 mm.sup.2/s, more preferably 10 mm.sup.2/s to
150 mm.sup.2/s, still more preferably 11 mm.sup.2/s to 100
mm.sup.2/s, and even still more preferably 12 mm.sup.2/s to 68
mm.sup.2/s.
[0105] Further, the viscosity index of the polyol ester (B2) used
in one embodiment of the present invention is preferably 90 or
more, more preferably 100 or more, still more preferably 110 or
more, and even still more preferably 120 or more.
[0106] The number average molecular weight (Mn) of the polyol ester
(B2) used in one embodiment of the present invention is preferably
100 to 8,000, more preferably 200 to 4,000, still more preferably
300 to 2,000, and even still more preferably 400 to 1,000.
[0107] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (B2) is, based on
the total amount (100% by mass) of the lubricating oil composition,
preferably 2.0 to 90% by mass, more preferably 2.5 to 70% by mass,
even more preferably 3.0 to 55% by mass, further more preferably
3.5 to 40% by mass, further more preferably 4.0 to 30% by mass, and
especially more preferably 4.5 to 15% by mass.
[Synthetic Oil other than Components (B1) and (B2)]
[0108] The synthetic oil (B) for use in one embodiment of the
present invention may further contain any other synthetic oil than
the components (B1) and (B2) within a range not detracting from the
advantageous effects of the present invention.
[0109] Examples of the other synthetic oil include
poly-.alpha.-olefins such as .alpha.-olefin homopolymers or
.alpha.-olefin copolymers (for example, .alpha.-olefin copolymers
having 8 to 14 carbon atoms such as ethylene-.alpha.-olefin
copolymers); isoparaffin; various esters other than the component
(B2), such as dibasic acid esters (for example, ditridecyl
glutarate), aromatic acid esters (for example, 2-ethylhexyl
trimellitate, 2-ethylhexyl pyromellitate), and phosphate esters;
various ethers other than the component (B1), such as polyphenyl
ethers; alkylbenzenes; and alkylnaphthalenes.
[0110] One alone or two or more kinds of these synthetic oils may
be used either singly or as combined.
<Antioxidant (C)>
[0111] The lubricating oil composition of one embodiment of the
present invention preferably contains an antioxidant (C) containing
an amine-based antioxidant (C1), from the viewpoint of providing a
lubricating oil composition which is excellent in oxidation
stability, suppresses generation of deterioration products, and is
further improved in the effect of preventing sludge
precipitation.
[0112] The antioxidant (C) used in one embodiment of the present
invention may further contain any other antioxidant than the
amine-based antioxidant (C1) together with the amine-based
antioxidant (C1).
[0113] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (C1) in the
component (C) is, based on the total amount (100% by mass) of the
component (C), preferably 30 to 100% by mass, more preferably 50 to
100% by mass, even more preferably 60 to 100% by mass, and further
more preferably 70 to 100% by mass, from the viewpoint of providing
a lubricating oil composition which suppresses generation of
deterioration products, is further improved in the effect of
preventing sludge precipitation, and has excellent oxidation
stability.
[0114] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (C) is preferably
0.01 to 10% by mass, more preferably 0.05 to 7% by mass, and still
more preferably 0.1 to 5% by mass, based on the total amount (100%
by mass) of the lubricating oil composition, from the viewpoint of
providing a lubricating oil composition which suppresses generation
of deterioration products, is further improved in the effect of
preventing sludge precipitation, and has excellent oxidation
stability.
[Amine-based Antioxidant (C1)]
[0115] The amine-based antioxidant (C1) may be an amine-based
compound having antioxidant performance, and includes naphthylamine
(C11) and diphenylamine (C12).
[0116] The amine-based antioxidant (C1) may be used alone or in
combination of two or more kinds thereof.
[0117] Further, in one embodiment of the present invention, both
naphthylamine (C11) and diphenylamine (C12) are preferably
included.
[0118] In the lubricating oil composition of one embodiment of the
present invention, the content ratio [(C11)/(C12)] of the
naphthylamine (C11) and the diphenylamine (C12) is preferably 10/90
to 90/10, more preferably 15/85 to 85/15, still more preferably
20/80 to 80/20, and even still more preferably 25/75 to 75/25 by a
mass ratio.
[0119] Examples of the naphthylamine (C11) include
phenyl-.alpha.-naphthylamine, phenyl-.beta.-naphthylamine,
alkylphenyl-.alpha.-naphthylamine, and
alkylphenyl-.beta.-naphthylamine, and preferably,
alkylphenyl-.alpha.-naphthylamine and
alkylphenyl-.beta.-naphthylamine.
[0120] The number of carbon atoms of the alkyl group in the
alkylphenyl-.alpha.-naphthylamine and the
alkylphenyl-.beta.-naphthylamine is preferably 1 to 30, but is,
from the viewpoint of improving solubility with the mineral oil (A)
and the synthetic oil (B), and more improving the effect of
preventing sludge precipitation, more preferably 1 to 20, even more
preferably 4 to 16, and still more preferably 6 to 14.
[0121] The diphenylamine (C12) is preferably a compound represented
by the following general formula (c-1) and more preferably a
compound represented by the following general formula (c-2).
##STR00003##
[0122] In the general formulae (c-1) and (c-2), R.sup.x and R.sup.y
are each independently an alkyl group having 1 to 30 carbon atoms,
or an alkyl group having 1 to 30 carbon atoms substituted with an
aryl group having 6 to 18 ring atoms.
[0123] The alkyl group may be either a linear alkyl group or a
branched alkyl group.
[0124] In general formula (c-1), z1 and z2 are each independently
an integer of 0 to 5, preferably 0 or 1, and more preferably 1.
Further, when there are a plurality of R.sup.x and R.sup.y, R.sup.x
and R.sup.y may be the same as or different from each other.
[0125] Further, the number of carbon atoms of the alkyl group which
can be selected as R.sup.x and R.sup.y is 1 to 30, preferably 1 to
20, and more preferably 1 to 10.
[0126] Examples of the aryl group that can be substituted for the
alkyl group include a phenyl group, a naphthyl group, and a
biphenyl group, and preferably, a phenyl group.
[0127] Examples of the alkyl group in the alkylphenyl-naphthylamine
and the alkyl group in the diphenylamine include 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 nonyl group, a decyl
group, an undecyl group, a dodecyl group, a hexadecyl group, an
octadecyl group, a nonadecyl group, an eicosyl group, and a
tetracosyl group.
[0128] In the lubricating oil composition of one embodiment of the
present invention, the content of the amine-based antioxidant (C1)
in terms of nitrogen atom is preferably 50 to 3000 ppm by mass,
more preferably 100 to 2000 ppm by mass, still more preferably 120
to 1500 ppm by mass, even still more preferably 150 to 1000 ppm by
mass, based on the total amount (100% by mass) of the lubricating
oil composition, from the viewpoint of providing a lubricating oil
composition which suppresses generation of deterioration products,
is further improved in the effect of preventing sludge
precipitation, and has excellent oxidation stability.
[Antioxidant other than amine-based antioxidant (C1)]
[0129] The antioxidant (C) may also contain an antioxidant other
than the above amine-based antioxidant (C1). As such an
antioxidant, a phenol-based antioxidant is preferred.
[0130] Examples of the phenol-based antioxidant include monocyclic
phenol compounds such as 2,6-di-t-butyl-4-methylphenol,
2,6-di-t-butyl-4-ethylphenol, 2,4,6-tri-t-butylphenol,
2,6-di-t-butyl-4-hydroxymethylphenol, 2,6-di-t-butylphenol,
2,4-dimethyl-6-t-butylphenol,
2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol,
2,6-di-t-amyl-4-methylphenol, and
n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; and
polycyclic phenol compounds such as
4,4'-methylenebis(2,6-di-t-butylphenol),
4,4'-isopropylidenebis(2,6-cli-t-butylphenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol),
4,4'-bis(2,6-di-t-butylphenol), 4,4'-bis(2-methyl-6-t-butylphenol),
2,2'-methylenebis(4-ethyl-6-t-butylphenol), and
4,4'-butylidenebis(3-methyl-6-t-butylphenol).
[0131] In the lubricating oil composition of one embodiment of the
present invention, the content of the phenol-based antioxidant
relative to 100 parts by mass of the amine-based antioxidant (C1)
is preferably 0 part by mass to 100 parts by mass, more preferably
0 part by mass to 60 parts by mass, and still more preferably 0
part by mass to 40 parts by mass.
<Phosphorus Compound (D)>
[0132] The lubricating oil composition of one embodiment of the
present invention preferably further contains one or more
phosphorus compounds (D) selected from a neutral phosphate (D1), an
acid phosphate (D2), an acid phosphate amine salt (D3) and a
sulfur-phosphorus compound (D4), from the viewpoint of improving
wear resistance.
[0133] From the viewpoint of further improving rust-preventing
performance, the component (D) preferably contains one or more
selected from the component (D1) and the component (D3). Also from
the viewpoint of satisfying both oxidation stability and wear
resistance even in a relatively small amount, the component (D)
preferably contains one or more selected from the component (D3)
and the component (D4).
[0134] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (D) in terms of
phosphorus atom is, based on the total amount (100% by mass) of the
lubricating oil composition, preferably 10 to 1600 ppm by mass,
more preferably 20 to 1200 ppm by mass, even more preferably 50 to
1000 ppm by mass, further more preferably 100 to 800 ppm by mass,
especially more preferably 150 to 600 ppm by mass. In the case
where one or more selected from the component (D3) and the
component (D4) are used, the content thereof in terms of phosphorus
atom may be, based on the total amount (100% by mass) of the
lubricating oil composition, preferably 10 to 50 ppm by mass, more
preferably 10 to 30 ppm by mass.
[0135] In the lubricating oil composition of one embodiment of the
present invention, the content of the component (D) is, based on
the total amount (100% by mass) of the lubricating oil composition,
preferably 0.01 to 2.0% by mass, more preferably 0.02 to 1.5% by
mass, even more preferably 0.05 to 1.0% by mass, further more
preferably 0.10 to 0.70% by mass. When one or more selected from
the component (D3) and the component (D4) are used, the content of
the component (D) may be, based on the total amount (100% by mass)
of the lubricating oil composition, preferably 0.01 to 1.0 ppm by
mass, more preferably 0.01 to 0.2 ppm by mass, even more preferably
0.01 to 0.05 ppm by mass.
[Neutral Phosphate (D1)]
[0136] The neutral phosphate (D1) is preferably a compound (D11)
represented by the following general formula (d1-1).
##STR00004##
[0137] In the general formula (d1-1), R.sup.D1 to R.sup.D3 are each
independently an alkyl group having 1 to 18 (preferably 3 to 18)
carbon atoms, or an aryl group having 6 to 18 ring carbon atoms and
substituted with an alkyl group having 1 to 18 (preferably 3 to 12)
carbon atoms.
[0138] Examples of the alkyl group having 1 to 18 carbon atoms
which can be selected as R.sup.D1 to R.sup.D3 include a methyl
group, an ethyl group, a propyl group (a n-propyl group, an
isopropyl group), a butyl group (a n-butyl group, an s-butyl, a
t-butyl group, an isobutyl group), a pentyl group, a hexyl group, a
2-ethyl hexyl group, a heptyl group, an octyl 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.
[0139] These alkyl group may be either a linear alkyl group or a
branched alkyl group.
[0140] Examples of the aryl group having 6 to 18 ring carbon atoms
include a phenyl group, a naphthyl group, an anthryl group, a
phenanthryl group, a biphenyl group, a terphenyl group, and a
phenylnaphthyl group, and preferably, a phenyl group.
[0141] The "aryl group substituted with an alkyl group having 1 to
18 carbon atoms" which can be selected as R.sup.D1 to R.sup.D3
includes a group in which at least one of hydrogen atoms bonded to
the ring carbon atoms of the aryl group is substituted with the
alkyl group having 1 to 18 carbon atoms.
[0142] The compound (D11) is more preferably a compound (D12)
represented by the following general formula (d1-2).
##STR00005##
[0143] In the general formula (d1-2), R.sup.D11 to R.sup.D13 are
each independently an alkyl group having 1 to 18 carbon atoms. The
alkyl group may be the same as the alkyl group which can be
selected as R.sup.D11 to R.sup.D13.
[0144] The number of carbon atoms of the alkyl group which can be
selected as R.sup.11 to R.sup.13 is 1 to 18 but is, from the
viewpoint of providing a lubricating oil composition having
improved rust-preventing performance, preferably 3 to 12, more
preferably 3 to 8, even more preferably 3 to 6, further more
preferably 3.
[0145] p1 to p3 are each independently an integer of 1 to 5,
preferably an integer of 1 to 2, and more preferably 1.
[Acid Phosphate (D2)]
[0146] The acid phosphate (D2) is preferably one or more selected
from a compound represented by the following general formula (d2-1)
and a compound represented by the following general formula
(d2-2).
##STR00006##
[0147] In the general formulae (d2-1) and (d2-2), R.sup.a and
R.sup.b are each independently an alkyl group having 1 to 12 carbon
atoms. The alkyl group may be the same as the alkyl group having 1
to 12 carbon atoms among the alkyl group which can be selected as
R.sup.D1 to R.sup.D3 as mentioned above.
[0148] The number of carbon atoms of the alkyl group which can be
selected as R.sup.a and R.sup.b is preferably 3 to 10, more
preferably 6 to 10, and still more preferably 8 to 10.
[0149] R.sup.a and R.sup.b in the general formula (d2-1) may be the
same as or different from each other.
[Acid Phosphate Amine Salt (D3)]
[0150] The acid phosphate amine salt (D3) is preferably one or more
selected from an amine salt of a compound represented by the
above-mentioned general formula (d2-1) and an amine salt of a
compound represented by the above-mentioned general formula
(d2-2).
[0151] The amine to form the amine salt is preferably a compound
represented by the following general formula (d3). One alone or two
or more kinds of the amines may be used either singly or as
combined.
(R.sup.c).sub.q--N--(H).sub.3-q (d3)
[0152] In the general formula (d3), q represents an integer of 1 to
3.
[0153] R.sup.C is each independently an alkyl group having 6 to 18
carbon atoms, an alkenyl group having 6 to 18 carbon atoms, an aryl
group having 6 to 18 ring carbon atoms, an arylalkyl group having 7
to 18 carbon atoms, or a hydroxyalkyl group having 6 to 18 carbon
atoms, and preferably, an alkyl group having 6 to 18 carbon
atoms.
[0154] When there are a plurality of R.sup.Cs, R.sup.Cs may be the
same as or different from each other.
[0155] Examples of the alkyl group which can be selected as R.sup.C
include 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 hexadecyl
group, and an octadecyl group.
[0156] The alkyl group may be either a linear alkyl group or a
branched alkyl group.
[0157] The number of carbon atoms of the alkyl group which can be
selected as R.sup.C is 6 to 18, preferably 7 to 16, more preferably
8 to 15, and still more preferably 10 to 13.
[0158] Examples of the alkenyl group which can be selected as
R.sup.C include a hexenyl group, a heptenyl group, an octenyl
group, a nonenyl group, a decenyl group, an undecenyl group, a
dodecenyl group, a tridecenyl group, a tetradecenyl group, a
hexadecenyl group, and an octadecenyl group.
[0159] The alkenyl group may be either a linear alkenyl group or a
branched alkenyl group.
[0160] The number of carbon atoms of the alkenyl group which can be
selected as R.sup.C is 6 to 18, preferably 7 to 16, more preferably
8 to 15, and still more preferably 10 to 13.
[0161] Examples of the aryl group which can be selected as R.sup.C
include a phenyl group, a naphthyl group, an anthryl group, a
phenanthryl group, a biphenyl group, a terphenyl group, and a
phenylnaphthyl group.
[0162] The number of carbon atoms of the aryl group which can be
selected as R.sup.C is 6 to 18, preferably 6 to 16, and more
preferably 6 to 14.
[0163] The arylalkyl group which can be selected as R.sup.C
includes a group in which a hydrogen atom of the alkyl group is
substituted with the aryl group, and specifically, a phenylmethyl
group, and a phenylethyl group.
[0164] The number of carbon atoms of the arylalkyl group which can
be selected as R.sup.C is 7 to 18, preferably 7 to 16, and more
preferably 8 to 14.
[0165] The hydroxyalkyl group which can be selected as R.sup.C
includes a group in which a hydrogen atom of the alkyl group is
substituted with a hydroxy group, and specifically, a hydroxyhexyl
group, a hydroxyoctyl group, a hydroxydodecyl group, and a
hydroxytridecyl group.
[0166] The number of carbon atoms of the hydroxyalkyl group which
can be selected as R.sup.C is 6 to 18, preferably 7 to 16, more
preferably 8 to 15, and still more preferably 10 to 13.
[Sulfur-Phosphorus Compound (D4)]
[0167] The sulfur-phosphorus compound (D4) includes
monothiophosphates, dithiophosphates, trithiophosphates,
monothiophosphate amine salts, dithiophosphate amine salts,
monothiophosphites, dithiophosphites, and trithiophosphites, and
among these, dithiophosphates are preferred.
[0168] From the viewpoint of bettering wear resistance,
dithiophosphates having a carboxy group or an ester residue at the
terminal are preferred among dithiophosphates. Having a carboxy
group or an ester group at the terminal, the sulfur-phosphorus
compound (D4) can have high polarity, and therefore also in this
embodiment using the above-mentioned specific ester-based synthetic
base oil (A) as a base oil, the sulfur-phosphorus compound of the
type can readily exhibit a function as an extreme pressure
agent.
[0169] Specific examples of the dithiophosphate having a carboxy
group or an ester residue at the terminal include compounds
represented by the following general formula (d4).
##STR00007##
[0170] In the formula (d4), R.sup.d represents a linear or branched
alkylene group having 1 to 8 carbon atoms, R.sup.e and R.sup.f each
independently represent a hydrocarbon group having 1 to 20 carbon
atoms. R.sup.g represents a hydrogen atom or a hydrocarbon group
having 1 to 10 carbon atoms.
[0171] In the formula (d4), R.sup.d is from the viewpoint of
bettering solubility in base oil, preferably a linear or branched
alkylene group having 1 to 8 carbon atoms, more preferably a linear
or branched alkylene group having 2 to 4 carbon atoms, even more
preferably an alkylene group having 2 carbon atoms or a branched
alkylene group having 3 to 4 carbon atoms. Specifically,
--CH.sub.2CH.sub.2--, --CH.sub.2CH(CH.sub.3)--,
--CH.sub.2CH(CH.sub.2CH.sub.3)--, --CH.sub.2CH(CH.sub.3)CH.sub.2--,
and --CH.sub.2CH(CH.sub.2CH.sub.2CH.sub.3)-- are preferred;
--CH.sub.2CH.sub.2--, --CH.sub.2CH(CH.sub.3)--, and
--CH.sub.2CH(CH.sub.3)CH.sub.2-- are more preferred; and
--CH.sub.2CH.sub.2--, and --CH.sub.2CH(CH.sub.3)-- are even more
preferred.
[0172] R.sup.e and R.sup.f each are, from the viewpoint of
bettering extreme pressure performance and bettering solubility in
base oil, preferably a linear or branched alkyl group having 1 to 8
carbon atoms, more preferably a linear or branched alkyl group
having 3 to 6 carbon atoms. Specifically, they are preferably
selected from groups of propyl, isopropyl, butyl, isobutyl,
t-butyl, pentyl, isopentyl, hexyl, 2-ethylbutyl, 1-methylpentyl,
1,3-dimethylbutyl and 2-ethylhexyl, and among these, isopropyl,
isobutyl and t-butyl are more preferred.
[0173] R.sup.g is, from the viewpoint of bettering extreme pressure
performance and solubility in base oil, preferably a hydrogen atom,
or a linear or branched alkyl group having 1 to 4 carbon atoms.
Specifically, a hydrogen atom and groups of methyl, ethyl, propyl,
isopropyl, butyl, isobutyl and t-butyl group are preferred, and
among these, a hydrogen atom, a methyl group and an ethyl group are
more preferred.
<Other Additives for Lubricating Oil>
[0174] The lubricating oil composition of one embodiment of the
present invention may contain any other additive for lubricating
oil than the above-mentioned components (B) to (D) within a range
not detracting from the advantageous effects of the present
invention.
[0175] Examples of such additives for lubricating oil include a
rust inhibitor, a detergent dispersant, a viscosity index improver,
an anti-foaming agent, a friction modifier, and a metal
deactivator.
[0176] One alone or two or more kinds of these additives for
lubricating oil may be used either singly or as combined.
[0177] In the case where such additives for lubricating oil are
added, the content of each additive for lubricating oil may be
appropriately controlled depending on the kind of the additive
within a range not detracting from the advantageous effects of the
present invention, but is, based on the total amount (100% by mass)
of the lubricating oil composition, generally 0.001 to 10% by mass,
preferably 0.005 to 5% by mass, more preferably 0.01 to 2% by
mass.
[0178] A lubricating oil composition prepared by blending an
alkenylsuccinate in a base oil of PAG or POE suffers from worsening
of water separability.
[0179] However, the lubricating oil composition of the present
invention contains a base oil (A) that is well compatible with an
alkenylsuccinate and therefore can effectively exhibit
rust-preventing performance that the alkenylsuccinate has. In
addition, even though an alkenylsuccinate is blended therein, the
lubricating oil composition can still have good water
separability.
[0180] In the lubricating oil composition of one embodiment of the
present invention, the content of the alkenylsuccinate is, based on
the total amount (100% by mass) of the lubricating oil composition,
preferably 0.001 to 5.0% by mass, more preferably 0.005 to 2.0% by
mass, even more preferably 0.01 to 1.0% by mass, further more
preferably 0.02 to 0.50% by mass.
[0181] Preferably, the lubricating oil composition of one
embodiment of the present invention does not substantially contain
a metal atom-containing compound from the viewpoint of preventing
sludge precipitation to occur in use for a long period of time in
high-temperature environments.
[0182] Here, the metal atom in the "metal atom-containing compound"
includes an alkali metal atom, an alkaline earth metal atom and a
transition metal atom.
[0183] In this description, "does not substantially contain a metal
atom-containing compound" is a definition to deny an embodiment of
incorporating a metal atom-containing compound with a predetermined
object but is not a definition to deny even a case of containing a
metal atom-containing compound as an impurity.
[0184] However, the content of a metal atom-containing compound
contained as an impurity is preferably as small as possible.
[0185] In the lubricating oil composition of one embodiment of the
present invention, the content of a metal atom is, from the
viewpoint of preventing sludge precipitation to occur in use for a
long period of time in high-temperature environments, based on the
total amount (100% by mass) of the lubricating oil composition,
preferably less than 100 ppm by mass, more preferably less than 50
ppm by mass, even more preferably less than 10 ppm by mass, further
more preferably less than 5 ppm by mass.
[0186] In this description, the content of a metal atom means a
value measured according to JPI-5S-38-92.
[Physical Properties of Lubricating Oil Composition]
[0187] The kinematic viscosity at 40.degree. C. of the lubricating
oil composition of one embodiment of the present invention is
preferably 5 to 300 mm.sup.2/s, more preferably 10 to 200
mm.sup.2/s, even more preferably 15 to 100 mm.sup.2/s.
[0188] The viscosity index of the lubricating oil composition of
one embodiment of the present invention is preferably 90 or more,
more preferably 100 or more, even more preferably 105 or more,
further more preferably 110 or more.
[0189] When the lubricating oil composition of one embodiment of
the present invention is tested according to the oxidation
stability test (Dry-TOST method) of ASTM D7873, the amount of
sludge precipitated in 960 hours after the start of the test in an
environment of 120.degree. C. is preferably 1.0 mg/100 ml or less,
more preferably 0.7 mg/100 ml or less, even more preferably 0.5
mg/100 ml or less.
[0190] The amount of the precipitated sludge is a value measured in
accordance with ASTM D7873 using a membrane filter having an
average pore diameter of 1.0 .mu.m.
[0191] When the lubricating oil composition of one embodiment of
the present invention is tested under environment of 120.degree. C.
according to the oxidation stability test (Dry-TOST method) of ASTM
D7873, the RPVOT residual ratio in 960 hours after the start of the
test is preferably 65% or more, more preferably 70% or more, even
more preferably 72% or more.
[0192] RPVOT residual ratio is a value calculated according to the
following expression.
[RPVOT residual ratio] (%)=[RPVOT time of sample after test]/[RPVOT
time of sample before test].times.100
[0193] When the lubricating oil composition of one embodiment of
the present invention is tested in a water separability test at a
temperature of 54.degree. C. according to JIS K2520, the
demulsibility degree that indicates a time to be taken for an
emulsion layer to reach 3 mL is preferably 15 minutes or less, more
preferably 10 minutes or less, even more preferably 5 minutes or
less.
[0194] The traction coefficient of the lubricating oil composition
of one embodiment of the present invention, as measured under the
measurement conditions shown in the section of Examples given
hereinunder, is preferably 0.020 or less, more preferably 0.018 or
less.
[Use of Lubricating Oil Composition, and Lubrication Method]
[0195] The lubricating oil composition of the present invention is
used in turbomachinery, compressors (excepting refrigerators),
hydraulic equipments, or machine tools.
[0196] Specifically, the lubricating oil composition of one
embodiment of the present invention is favorably used as a
lubricating oil (pump oil, turbine oil) for turbomachinery for use
for lubrication of turbomachinery such as pumps, vacuum pumps,
blowers, turbocompressors, steam turbines, atomic force turbines,
gas turbines, and turbines for hydraulic power generation; a
bearing oil, a gear oil or a control system operating oil for
lubrication for compressors such as rotary compressor and
reciprocating compressors; a hydraulic actuation oil for use for
hydraulic machines; and a lubricating oil for machine tools for use
for hydraulic units of machine tools.
[0197] Namely, the present application also provides a use method
of the following [1],
[1] A method of using a lubricating oil composition, using a
lubricating oil composition containing a mineral oil (A) and a
synthetic oil (B) that contains a polyalkylene glycol (B1) and a
polyol ester (B2), in which the content of the mineral oil (A) is 5
to 95% by mass, in turbomachinery, compressors, hydraulic
equipments, or machine tools.
[0198] Specific constitutions of the lubricating oil composition of
the present invention, as well as specific exemplifications of
turbomachinery, compressors, hydraulic equipments, and machine
tools are as described above.
EXAMPLES
[0199] The present invention is described more specifically with
reference to Examples, but the present invention is not limited to
these Examples.
[Measurement Methods of Various Physical Property Values]
[0200] (1) Kinematic Viscosity, Viscosity Index
[0201] Measured and calculated in accordance with JIS
K2283:2000.
[0202] (2) Number Average Molecular Weight (Mn)
[0203] Mn was measured in terms of standard polystyrene according
to gel permeation chromatography (GPC) under the following
measurement conditions.
[0204] (Measurement Conditions)
[0205] Gel permeation chromatography apparatus: "1260 type HPLC"
manufactured by Agilent Co.
[0206] Standard sample: polystyrene
[0207] Column: One in which two of "Shodex LF404" were successively
connected to each other
[0208] Column temperature: 35.degree. C.
[0209] Developing solvent: Chloroform
[0210] Flow rate: 0.3 mL/min
[0211] (3) Contents of Phosphorus and Metal Atoms
[0212] Measured in accordance with JPI-5S-38-92.
[0213] (4) Contents of Nitrogen Atom
[0214] Measured in accordance with JIS K2609.
Examples 1 to 7 and Comparative Examples 1 to 5
[0215] The mineral oil, synthetic oil, amine-based antioxidant,
phosphorus compound and other additives shown below were blended at
the blending ratio shown in Table 1 and, and fully mixed to prepare
lubricating oil compositions (I) to (VII) and (i) to (v),
respectively.
[0216] The details of the respective components used in the
preparation of the lubricating oil compositions are as mentioned
below.
(Mineral Oil)
[0217] "150N Mineral Oil": mineral oil grouped in Group 2 of the
API base oil category. Kinematic viscosity at 40.degree. C.=30.6
mm.sup.2/s, viscosity index=104.
(Synthetic Oil)
[0218] "PAG": Polypropylene glycol of which one end is sealed with
butyl ether which is represented by
H--(OCH(CHOCH.sub.2).sub.a--OC.sub.4H.sub.9 (in the general formula
(b-1), R.sup.B1 is a hydrogen atom, R.sup.B2 is a propylene group,
R.sup.B3 is a n-butyl group, and b is 1). Kinematic viscosity at
40.degree. C.=37.2 mm.sup.2/s, viscosity index=173, Mn=800.
[0219] "POE": Trimethylolpropane triester (complete ester of
trimethylolpropane and carboxylic acid having 8 to 10 carbon
atoms). Kinematic viscosity at 40.degree. C.=19.6 mm.sup.2/s,
viscosity index=138.
(Amine-Based Antioxidant)
[0220] "Naphthylamine": P-octylphenyl-.alpha.-naphthylamine.
Nitrogen atom content=4.2% by mass.
[0221] "Diphenylamine": Bis(p-octylphenyl)amine, a compound
represented by the general formula (c-2) where R.sup.x and R.sup.y
are octyl group. Nitrogen atom content=3.6% by mass.
(Phosphorus Compound)
[0222] "Neutral phosphate ester": Tris(p-isopropylphenyl)phosphate,
in the general formula (d1-2), p1 to p3 are 1, and R.sup.D11 to
R.sup.D13 are isopropyl groups, wherein the isopropyl group is
bonded to the para-position. Phosphorus atom content=6.8% by
mass.
[0223] "Acid phosphate amine": Amine salt of a mixture of a
compound represented by the general formula (d2-1) and a compound
represented by the general formula (d2-2), and a compound
represented by the general formula (d3). (In the general formula
(d2-1) and the general formula (d2-2), R.sup.a and R.sup.b each are
an alkyl group having 8 or 10 carbon atoms, in the general formula
(d3), R.sup.c is an alkyl group having 12 carbon atoms, q is 1 or
2.) Phosphorus atom content=4.8% by mass.
[0224] Thiophosphate 1:
3-Diisobutoxyphosphinothioylsulfanyl-2-methylprop anoic acid.
Phosphorus atom content=9.3% by mass.
[0225] Thiophosphate 2:
Ethyl-3-[{bis(1-methylethoxy)phosphinothioyl}thio]propionate.
Phosphorus atom content=9.9% by mass.
(Other Additives)
[0226] "Rust inhibitor": Alkenylsuccinate half ester.
[0227] "Anti-foaming agent": Silicone-based anti-foaming agent,
acryl-based anti-foaming agent.
[0228] With respect to each of the prepared lubricating oil
compositions, various physical property values shown in Tables 1
and 2 were measured according to the above methods, and various
properties of the lubricating oil compositions were evaluated by
conducting the following tests. The results are shown in Tables 1
and 2.
(1) Oxidation Stability Test (Dry-TOST)
[0229] The amount of sludge precipitated and the RPVOT residual
ratio in 960 hours after initiation of the test under environment
of 120.degree. C. was measured in accordance with the oxidation
stability test (Dry-TOST) of ASTM D7873.
[0230] The amount of the precipitated sludge was measured in
accordance with ASTM D7873 using a membrane filter having an
average pore diameter of 1.0 (provided by Millipore
Corporation).
[0231] The RPVOT residual ratio was calculated according to the
following expression.
[RPVOT residual ratio] (%)=[RPVOT time of sample after test]/[RPVOT
time of sample before test].times.100
(2) Water Separability Test
[0232] A water separability test was conducted at a temperature of
54.degree. C. in accordance with JIS K2520 to measure the time
(demulsibility unit: min) taken for an emulsion layer to reach 3
mL.
(3) Measurement of Traction Coefficient
[0233] Using an EHD oil film measuring device (available from PCS
Instruments Ltd.), a traction coefficient was measured under the
following measurement conditions.
[0234] Disc: diameter 46 mm, SAE AISI52100 steel
[0235] Ball: diameter 19 mm, SAE AISI52100 steel
[0236] Load: 20 N
[0237] Rolling speed: 2.0 m/s
[0238] Oil temperature: 60.degree. C.
[0239] Slip ratio: 10%
(4) Wear Resistance Test
[0240] Using an FZG gear tester and according to ISO 14635-1, a
load was stepwise increased as prescribed, and a stage under a load
to have generated scouring was evaluated. A higher stage of load
indicates more excellent scouring resistance.
TABLE-US-00001 TABLE 1 Ex- Ex- Ex- Ex- Ex- Ex- Ex- ample ample
ample ample ample ample ample 1 2 3 4 5 6 7 Lubricating Oil
Composition (I) (II) (III) (IV) (V) (VI) (VII) Formu- Mineral Oil
150N mineral oil mass % 24.65 50.25 74.85 89.00 48.00 48.00 48.00
lation Synthetic Oil PAG mass % 22.00 14.00 7.00 3.00 34.98 34.98
34.91 POE mass % 51.00 34.00 17.00 7.00 15.00 15.00 15.00
Amine-based naphthylamine mass % 0.60 0.40 0.20 0.15 0.64 0.64 0.64
Antioxidant diphenylamine mass % 1.20 0.80 0.40 0.30 1.20 1.20 1.20
Phosphorus neutral phosphate mass % 0.40 0.40 0.40 0.40 -- -- --
Compound acid phosphate mass% -- -- -- -- 0.03 -- -- amine salt
thiophosphate 1 mass % -- -- -- -- -- 0.03 -- thiophosphate 2 mass
% -- -- -- -- -- -- 0.10 Other rust inhibitor mass % 0.05 0.05 0.05
0.05 0.05 0.05 0.05 Additives anti-foaming agent mass % 0.10 0.10
0.10 0.10 0.10 0.10 0.10 -- total mass % 100.00 100.00 100.00
100.00 100.00 100.00 100.00 Content of PAG in total amount mass %
30.1 29.2 29.2 30.0 70.0 70.0 69.9 (100% by mass) of synthetic oil
Content of POE in total amount mass % 69.9 70.8 70.8 70.0 30.0 30.0
30.1 (100% by mass) of synthetic oil Mineral oil/(PAG + POE) (ratio
by mass) -- 0.34 1.05 3.12 8.90 0.96 0.96 0.96 Nitrogen
atom-equivalent content mass 744 496 248 186 761 761 761 of
amine-based antioxidant ppm Phosphorus atom-equivalent mass 272 272
272 272 24 28 84 content of phosphorus compound ppm Content of
metal atom mass less less less less less less less ppm than 5 than
5 than 5 than 5 than 5 than 5 than 5 Properties of 40.degree. C.
kinematic mm.sup.2/s 23.6 25.2 27.4 29.6 25.3 25.2 25.3 Lubricating
viscosity Oil Composition 100.degree. C. kinematic mm.sup.2/s 4.88
5.01 5.27 5.23 5.00 5.02 5.01 viscosity viscosity index -- 134 128
127 108 128 128 128 Eval- (1) Oxidation Sludge formation mg/100 0.2
0.4 0.5 0.5 0.2 0.5 0.2 uation stability test ml RPVOT residual %
85 88 78 72 81 78 78 ratio (2) Water separability test, min 10 10
10 5 10 10 10 demulsibility degree (3) Measurement of traction --
0.014 0.014 0.017 0.018 0.013 0.014 0.014 coefficient, traction
coefficient (4) Wear resistance text, -- 6 6 6 6 12 12 12 FZG load
stage
TABLE-US-00002 TABLE 2 Com- Com- Com- Com- Com- parative parative
parative parative parative Example Example Example Example Example
1 2 3 4 5 Lubricating Oil Composition (i) (ii) (iii) (iv) (v)
Formulation Mineral Oil 150N mineral oil mass % 99.10 -- -- 99.47
99.47 Synthetic Oil PAG mass % -- 29.75 30.12 -- -- POE mass % --
68.00 68.00 -- -- Amine-based naphthylamine mass % 0.10 0.60 0.60
0.10 0.10 Antioxidant diphenylamine mass % 0.25 1.20 1.20 0.25 0.25
Phosphorus neutral phosphate mass % 0.10 0.40 -- -- -- Compound
acid phosphate amine salt mass % -- -- 0.03 0.03 -- thiophosphate 1
mass % -- -- -- -- 0.03 Other rust inhibitor mass % 0.05 0.05 0.05
0.05 0.05 Additives anti-foaming agent mass % 0.10 -- -- 0.10 0.10
-- total mass % 100.00 100.00 100.00 100.00 100.00 Content of PAG
in total amount mass % -- 30.4 30.7 -- -- (100% by mass) of
synthetic oil Content of POE in total amount mass % -- 69.6 69.3 --
-- (100% by mass) of synthetic oil Mineral oil/(PAG + POE) (ratio
by mass) -- -- 0 0 -- -- Nitrogen atom-equivalent content mass 145
744 744 145 145 of amine-based antioxidant ppm Phosphorus
atom-equivalent mass 272 272 14 14 28 content of phosphorus
compound ppm Content of metal atom mass less less less less less
ppm than 5 than 5 than 5 than 5 than 5 Properties of Lubricating
40.degree. C. kinematic viscosity mm.sup.2/s 31.6 23.7 23.6 32.0
23.7 Oil Composition 100.degree. C. kinematic viscosity mm.sup.2/s
5.34 4.96 4.98 4.41 4.96 viscosity index -- 101 139 139 102 139
Evaluation (1) Oxidation Sludge formation mg/100 1.2 0.3 0.3 27 19
stability test ml RPVOT residual ratio % 60 95 95 29 95 (2) Water
separability test, min 5 20 20 20 20 demulsibility degree (3)
Measurement of traction -- 0.025 0.012 0.012 0.024 0.025
coefficient, traction coefficient (4) Wear resistance text, -- 5 5
12 12 11 FZG load stage
[0241] The lubricating oil compositions prepared in Examples 1 to 7
were excellent in oxidation stability and had a strong effect of
preventing sludge precipitation, and had excellent water
separability. In addition, these have a low traction coefficient
and showed an effect of improving wear resistance.
[0242] On the other hand, the lubricating oil composition prepared
in Comparative Example 1 was poor in oxidation stability, and as
compared with those in Examples, this caused much sludge
precipitation and had a low RPVOT residual ratio. In addition, this
is insufficient in point of wear resistance.
[0243] The lubricating oil compositions prepared in Comparative
Examples 2, 3, 4 and 5 had good oxidation stability and wear
resistance, but were poor in water separability, and among these,
the composition of Comparative Example 4 was especially poor in
oxidation stability, and caused relatively much sludge
precipitation.
* * * * *