U.S. patent application number 13/818329 was filed with the patent office on 2013-11-21 for lubricating oil composition for internal combustion engines.
The applicant listed for this patent is Masaki Maruyama, Yasushi Naito, Kazuhiro Umehara, Kenji Yamamoto, Satoru Yoshida. Invention is credited to Masaki Maruyama, Yasushi Naito, Kazuhiro Umehara, Kenji Yamamoto, Satoru Yoshida.
Application Number | 20130310289 13/818329 |
Document ID | / |
Family ID | 45723399 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130310289 |
Kind Code |
A1 |
Umehara; Kazuhiro ; et
al. |
November 21, 2013 |
LUBRICATING OIL COMPOSITION FOR INTERNAL COMBUSTION ENGINES
Abstract
Provided is a lubricating oil composition for an internal
combustion engine, including: an organic molybdenum compound as a
component (A); a base oil having a kinematic viscosity at
100.degree. C. of 25 mm.sup.2/s or more as a component (B); and a
base oil having a kinematic viscosity at 100.degree. C. of less
than 12.5 mm.sup.2/s as a component (C), in which the composition
has a kinematic viscosity at 100.degree. C. of 5 mm.sup.2/s to 12.5
mm.sup.2/s and a phosphorus content of 800 ppm or less.
Inventors: |
Umehara; Kazuhiro; (Tokyo,
JP) ; Yamamoto; Kenji; (Tokyo, JP) ; Maruyama;
Masaki; (Saitama, JP) ; Naito; Yasushi;
(Saitama, JP) ; Yoshida; Satoru; (Saitama,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Umehara; Kazuhiro
Yamamoto; Kenji
Maruyama; Masaki
Naito; Yasushi
Yoshida; Satoru |
Tokyo
Tokyo
Saitama
Saitama
Saitama |
|
JP
JP
JP
JP
JP |
|
|
Family ID: |
45723399 |
Appl. No.: |
13/818329 |
Filed: |
August 19, 2011 |
PCT Filed: |
August 19, 2011 |
PCT NO: |
PCT/JP2011/068747 |
371 Date: |
August 8, 2013 |
Current U.S.
Class: |
508/363 |
Current CPC
Class: |
C10N 2040/252 20200501;
C10N 2040/255 20200501; C10M 2205/0285 20130101; C10N 2030/54
20200501; C10M 2207/026 20130101; C10N 2030/04 20130101; C10M
2223/045 20130101; C10M 2219/068 20130101; C10M 2203/1025 20130101;
C10N 2040/25 20130101; C10N 2010/12 20130101; C10N 2030/02
20130101; C10M 2203/1085 20130101; C10M 2209/084 20130101; C10M
2215/064 20130101; C10M 2207/289 20130101; C10M 2207/262 20130101;
C10N 2030/42 20200501; C10M 2215/28 20130101; C10N 2020/02
20130101; C10N 2030/10 20130101; C10M 169/04 20130101; C10M 2215/06
20130101; C10N 2030/08 20130101; C10M 135/18 20130101; C10M
2219/068 20130101; C10N 2010/12 20130101; C10M 2207/262 20130101;
C10N 2010/04 20130101; C10M 2223/045 20130101; C10N 2010/04
20130101; C10M 2219/068 20130101; C10N 2010/12 20130101; C10M
2207/262 20130101; C10N 2010/04 20130101; C10M 2223/045 20130101;
C10N 2010/04 20130101 |
Class at
Publication: |
508/363 |
International
Class: |
C10M 169/04 20060101
C10M169/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2010 |
JP |
2010-186834 |
Claims
1. A lubricating oil composition for an internal combustion engine,
comprising: an organic molybdenum compound as a component (A); a
base oil having a kinematic viscosity at 100.degree. C. of 25
mm.sup.2/s or more as a component (B); and a base oil having a
kinematic viscosity at 100.degree. C. of less than 12.5 mm.sup.2/s
as a component (C), wherein the composition has a kinematic
viscosity at 100.degree. C. of 5 mm.sup.2/s to 12.5 mm.sup.2/s and
a phosphorus content of 800 ppm or less.
2. The lubricating oil composition for an internal combustion
engine according to claim 1, wherein the lubricating oil
composition for an internal combustion engine contains 200 to 2,000
ppm in terms of a molybdenum content of the component (A), 1 to 30
mass % of the component (B), and 50 to 95 mass % of the component
(c) with respect to a total amount thereof.
3. The lubricating oil composition for an internal combustion
engine according to claim 1, wherein the component (A) comprises a
compound represented by the following general formula (1):
##STR00003## where R.sup.1 to R.sup.4 each represent a linear or
branched alkyl group or alkenyl group having 4 to 18 carbon atoms,
and X.sup.1 to X.sup.4 each represent an oxygen atom or a sulfur
atom.
4. The lubricating oil composition for an internal combustion
engine according to claim 1, wherein the lubricating oil
composition for an internal combustion engine further comprises one
or more kinds of additives selected from the group consisting of a
viscosity index improver, a pour point depressant, an
extreme-pressure agent, an oiliness improver, an antioxidant, a
metal-based detergent, an ashless dispersant, a metal deactivator,
a rust inhibitor, and an anti-foaming agent.
5. The lubricating oil composition for an internal combustion
engine according to claim 4, wherein the lubricating oil
composition for an internal combustion engine contains 300 to 800
ppm in terms of a phosphorus content of a zinc dithiophosphate as
an extreme-pressure agent with respect to a total amount
thereof.
6. The lubricating oil composition for an internal combustion
engine according to claim 2, wherein the component (A) comprises a
compound represented by the following general formula (1):
##STR00004## where R.sup.1 to R.sup.4 each represent a linear or
branched alkyl group or alkenyl group having 4 to 18 carbon atoms,
and X.sup.1 to X.sup.4 each represent an oxygen atom or a sulfur
atom.
7. The lubricating oil composition for an internal combustion
engine according to claim 2, wherein the lubricating oil
composition for an internal combustion engine further comprises one
or more kinds of additives selected from the group consisting of a
viscosity index improver, a pour point depressant, an
extreme-pressure agent, an oiliness improver, an antioxidant, a
metal-based detergent, an ashless dispersant, a metal deactivator,
a rust inhibitor, and an anti-foaming agent.
8. The lubricating oil composition for an internal combustion
engine according to claim 3, wherein the lubricating oil
composition for an internal combustion engine further comprises one
or more kinds of additives selected from the group consisting of a
viscosity index improver, a pour point depressant, an
extreme-pressure agent, an oiliness improver, an antioxidant, a
metal-based detergent, an ashless dispersant, a metal deactivator,
a rust inhibitor, and an anti-foaming agent.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lubricating oil
composition for an internal combustion engine, and more
specifically, to a lubricating oil composition for an internal
combustion engine having excellent fuel-saving property and
high-temperature deposit-preventing performance.
BACKGROUND ART
[0002] A lubricating oil for internal combustion engines of
automobiles or the like plays roles such as the lubrication and
cooling of the inside of the engine, and the cleaning and
dispersion of combustion products. In recent years, to prevent
global warming, there has been a growing demand for the suppression
of carbon dioxide emissions through improvements in the fuel
efficiency of automobiles or the like. Accordingly, a
fuel-saving-type lubricating oil for an internal combustion engine
obtained by providing a lubricating oil for an internal combustion
engine with a function of improving fuel efficiency has been
studied and used.
[0003] Fuel-saving-type lubricating oils for internal combustion
engines reduce friction occurring in an internal combustion engine
to improve the fuel efficiency of the engine. Specifically, an
organic molybdenum-based friction modifier such as a molybdenum
dithiocarbamate is generally blended as an additive (friction
modifier) for reducing the friction. However, lubricants for
internal combustion engines blended with organic molybdenum-based
friction modifiers are apt to generate high-temperature deposits
because of poor oxidation stability under high temperatures. In
particular, recent lean-burn engines, direct-injection engines, or
the like have higher efficiency than conventional engines, and
their combustion temperatures tend to increase. Accordingly,
problems due to generation of high-temperature deposits have become
serious.
[0004] In view of the foregoing, various methods have been proposed
for reducing the high-temperature deposits. For example, Patent
Document 1 discloses a multigrade engine oil composition for an
engine with a turbocharger, the composition being characterized by
using a mineral oil and/or a synthetic oil having a kinematic
viscosity of 1.5 to 13 cSt (100.degree. C.) as a base oil, and
containing, as essential components, 2 to 40 mass % of (A) a
mineral oil and/or a synthetic oil having a kinematic viscosity of
16 to 45 cSt (100.degree. C.) and 0.5 to 15 mass % of (B) a
viscosity index improver. In addition, Patent Document 2 discloses
a lubricating oil composition for an internal combustion engine
characterized by using, as a base oil, a lubricating oil component
that has a kinematic viscosity at 100.degree. C. of 2 cSt to 13 cSt
and contains 1 mass % or more of a heavy component having a boiling
point of 480.degree. C. or more in a boiling point range measured
by gas chromatograph distillation with reference to the total mass
of the lubricating oil base oil. In addition, the paragraphs [0021]
to [0026] of Patent Document 2 disclose that an organic
molybdenum-based compound can be used as a friction modifier.
PRIOR ART DOCUMENTS
Patent Documents
[0005] Patent Document 1: JP 59-122595 A
[0006] Patent Document 2: JP 09-328694 A
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0007] However, even when an organic molybdenum-based friction
modifier is blended with the compositions described in Patent
Documents 1 and 2, the high-temperature deposits cannot
sufficiently be reduced, and hence fuel-saving-type lubricating oil
compositions for internal combustion engines capable of
additionally reducing high-temperature deposits are still
desired.
[0008] Therefore, a problem to be solved by the present invention
is to provide a lubricating oil composition of ran internal
combustion engine having high-temperature deposit-preventing
performance while maintaining excellent fuel-saving property.
Means for Solving the Problem
[0009] In view of the foregoing, the present inventors have made
extensive studies to find that excellent fuel-saving performance
and high-temperature deposit-preventing performance can be imparted
by blending a lubricating oil composition for an internal
combustion engine with an organic molybdenum compound and a
plurality of base oils each having a specific viscosity. Thus, the
inventors have reached the present invention.
[0010] That is, the present invention provides a lubricating oil
composition for an internal combustion engine, including: an
organic molybdenum compound as a component (A); a base oil having a
kinematic viscosity at 100.degree. C. of 25 mm.sup.2/s or more as a
component (B); and a base oil having a kinematic viscosity at
100.degree. C. of less than 12.5 mm.sup.2/s as a component (C), in
which the composition has a kinematic viscosity at 100.degree. C.
of 5 mm.sup.2/s to 12.5 mm.sup.2/s and a phosphorus content of 800
ppm or less.
EFFECT OF THE INVENTION
[0011] An effect of the present invention resides in he provision
of the lubricating oil composition for an internal combustion
engine having high-temperature deposit-preventing performance while
maintaining excellent fuel-saving property.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a schematic view of a TEOST33C tester.
[0013] FIG. 2 is a graph showing a temperature change during 1
cycle in a case in a TEOST33C test.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] A lubricating oil composition for an internal combustion
engine of the present invention contains an organic molybdenum
compound as a component (A). Any one of the known organic
molybdenum compounds can be used as the organic molybdenum
compound, and examples thereof include: a molybdenum
dithiocarbamate; a molybdenum dithiophosphate; a molybdenum amine
compound listed in JP 05-62639 B or the like [an oil-soluble
molybdenum compound selected from molybdenum trioxide, and molybdic
acid and an alkali salt thereof, and an amino compound represented
by R.sup.1R.sup.2R.sup.3N (R.sup.1, R.sup.2, and R.sup.3 each
represent a hydrogen atom or a hydrocarbon group having 1 to 30
carbon atoms and may be identical to or different from one another,
and the total number of carbon atoms of R.sup.1, R.sup.2, and
R.sup.3 is 4 or more) with each other]; and a molybdenum compound
containing phosphorus and sulfur listed in JP 04-30959 B or the
like [a compound obtained by reacting (a) at least one hexavalent
molybdenum compound; (b) at least one compound selected from
hydrogen sulfide, an alkali hydrosulfide, and an alkali sulfide
represented by M.sub.2S (M represents an alkali metal or an
ammonium group); (c) a compound represented by the following
formula or a salt thereof.
##STR00001##
where X.sub.1, X.sub.2, Y.sub.1 and Y.sub.2 each represent an
oxygen or sulfur atom and may be identical to or different from one
another, n represents 0 or 1, and R.sub.1 and R.sub.2 each
represent an organic residue and may be identical to or different
from each other; and (d) a reducing agent capable of reducing the
hexavalent molybdenum compound to pentavalent or tetravalent
(provided that the components b and c are excluded) with one
another].
[0015] Among such organic molybdenum compounds, a molybdenum
dithiocarbamate represented by the following general formula (1) is
preferred because of its large friction-reducing effect.
##STR00002##
where R.sup.1 to R.sup.4 each represent a linear or branched alkyl
group or alkenyl group having 4 to 18 carbon atoms, and X.sup.1 to
X.sup.4 each represent an oxygen atom or a sulfur atom.
[0016] R.sup.1 to R.sup.4 of the general formula (1) represent a
linear or branched alkyl group or alkenyl group having 4 to 18
carbon atoms. Examples of such group include: alkyl groups such as
a butyl group, an isobutyl group, a tertiary buytl group, a pentyl
group, an isopentyl group, a neopentyl group, a tertiary pentyl
group, a hexyl group, an isohexyl group, a heptyl group, an
isoheptyl group, an octyl group, a 2-ethylhexyl group, an isooctcyl
group, an undecyl group, an isononyl group, a decyl group, an
isodecyl group, an undecyl group, an isoundecyl group, a dodecyl
group, an isododecyl group, a tridecyl group, an isotridecyl group,
a tetradecyl group, an isotetradecyl group, a hexadecyl group, an
isohexadecyl group, a stearyl group, a 2-butyloctyl group, a
2-butyldecyl group, a 2-hexyloctyl group, a 2-hexyldecyl group, a
2-octyldecyl group, a 2-hexyldodecyl group, and a monomethyl
branched-isostearyl group; and alkenyl groups such as a butenyl
group, an isobutenyl group, a pentenyl group, an isopentenyl group,
a hexenyl group, a heptenyl group, an octenyl group, a nonenyl
group, a decenyl group, an undecenyl group, a dodecenyl group, a
tetradecenyl group, and an oleyl group. Among them, an alkyl group
is preferred because of its high friction-reducing effect, an alkyl
group having 6 to 16 carbon atoms is more preferred, and an alkyl
group having 8 to 13 carbon atoms is still more preferred. It
should be noted that R.sup.1 to R.sup.4 may be identical to or
different from one another.
[0017] X.sup.1 to X.sup.4 each represent an oxygen atom or a sulfur
atom, all of X.sup.1 to X.sup.4 may be oxygen atoms or sulfur
atoms, and X.sup.1 to X.sup.4 may be a mixture of oxygen atoms and
sulfur atoms. However, the ratio of oxygen atom/sulfur atom (molar
ratio) preferably falls within the range of 1/3 to 3/1 because a
high friction-reducing effect and low corrosiveness are
obtained.
[0018] The organic molybdenum compound may be one kind or a mixture
of two or more kinds. The amount of the compound to be added to the
lubricating oil composition of ran internal combustion engine of
the present invention is not specified. However, when the addition
amount is small, there are cases where a friction-reducing effect
is not obtained. In addition, when the addition amount is
excessively large, high-temperature deposits outstripping the
effect of the high-temperature deposit-preventing performance of
the lubricating oil composition for an internal combustion engine
of the present invention may be generated. Accordingly, the
compound is added at a molybdenum content of preferably 200 to
2,000 ppm, more preferably 200 to 1,500 ppm, still more preferably
300 to 1,000 ppm with respect to the total amount of the
lubricating oil composition for an internal combustion engine of
the present invention.
[0019] The component (B) used in the present invention is a base
oil having a kinematic viscosity at 100.degree. C. of 25 mm.sup.2/s
or more, and a mineral oil-based base oil, a synthetic base oils,
or a mixed oil thereof can be used as such base oil. A
paraffin-based mineral oil and a naphthene-based base oil, and a
solvent-refined oil, oil obtained by a hydrogenation treatment,
wax-isomerized oil, or the like of any such oil may be used. For
example, a ply-.alpha.-olefin, a polyisobutylene (polybutene), a
diester, a polyol ester, or a polyphenyl ether can be used as the
synthetic base oil. Among them, a paraffin-based mineral oil such
as a bright stock and a high-viscosity poly-.alpha.-olefin are
preferred.
[0020] One kind of these base oils can be used alone, or a mixture
of two or more kinds thereof can be used, as the component (B).
However, the kinematic viscosity at 100.degree. C. of the component
must be 25 mm.sup.2/s or more, and is preferably 25 to 100
mm.sup.2/s, more preferably 25 to 80 mm.sup.2/s, still more
preferably 30 to 60 mm.sup.2/s. When the kinematic viscosity at
100.degree. C. is less then 25 mm.sup.2/s, the high-temperature
deposit-preventing performance is not sufficiently exerted. In
addition, when the viscosity is excessively high, there are
problems such as cases where it may be difficult to handle the
component or it takes a long time to uniformly blend the component.
Accordingly, the kinematic viscosity is preferably 100 mm.sup.2/s
or less.
[0021] The blending amount of the component (B) is not particularly
specified. However, when the blending amount is excessively small,
there are cases where the effect of the high-temperature
deposit-preventing performance may not be exerted. In addition,
when the blending amount is excessively large, it may be difficult
to set the kinematic viscosity at 100.degree. C. of the lubricating
oil composition for an internal combustion engine of the present
invention to 12.5 mm.sup.2/s or less, or its low-temperature
viscosity may increase to reduce its fuel-saving effect. In view of
the foregoing, the blending amount of the component (B) is
preferably 1 to 30 mass %, more preferably 3 to 25 mass %, still
more preferably 5 to 20 mass % with respect to the total amount of
the lubricating oil composition for an internal combustion engine
of the present invention.
[0022] The component (C) used in the present invention is a base
oil having a kinematic viscosity at 100.degree. C. of less than
12.5 mm.sup.2/s. A mineral oil-based base oil, a synthetic base
oil, or a mixed oil thereof can be used as such as oil, and
examples of such base oil include: mineral oil-based base oils such
as a paraffin-based mineral oil and a naphthene-based mineral oil,
oils obtained by subjecting thee mineral oils to a solvent refining
treatment, a hydrogenation treatment, and a was isomerization
treatment, and a mineral oil obtained by combining two or more of
these treatments; and synthetic oils such as poly-.alpha.-olefins
and polyisobutylenes.
[0023] When the kinematic viscosity of the component (C) is 12.5
mm.sup.2/s or more, a lubricating oil composition having a
kinematic viscosity in the range specified in the present invention
cannot be produced. In addition, even when the kinematic viscosity
of the component (C) is less than 12.5 mm.sup.2/s, in the case
where the component is a base oil having an excessively high
viscosity, the amount of the high-viscosity base oil that can be
added is reduced, and hence it may be unable to efficiently
alleviate the generation of high-temperature deposits or the
low-temperature viscosity of the lubricating oil composition of ran
internal combustion engine of the present invention may increase to
reduce its fuel-saving effect. Accordingly, the kinematic viscosity
at 100.degree. C. of the component (C) is preferably 1 to 11
mm.sup.2/s, more preferably 2 to 8 mm.sup.2/s, still more
preferably 2 to 5 mm.sup.2/s.
[0024] Further, the viscosity index of the component (C) is
preferably 100 or more, more preferably 110 or more, still more
preferably 120 or more from the viewpoint of improving fuel-saving
properties. When the viscosity index of the low-viscosity base oil
is less than 100, the low-temperature viscosity of the lubricating
oil composition for an internal combustion engine as the end
product increases, with the result that the fuel-saving effect is
not obtained in some cases.
[0025] The component (C) has only to be blended in such an amount
that the lubricating oil composition for an internal combustion
engine of the present invention blended with any other additive or
the like has a kinematic viscosity at 100.degree. C. of 5
mm.sup.2/s to 12.5 mm.sup.2/s. Specifically, the component has only
to be blended in an amount of 50 to 95 mass %, preferably 60 to 85
mass % with respect to the total amount of the lubricating oil
composition of the present invention.
[0026] In addition, the lubricating oil composition for an internal
combustion engine of the present invention containing the
components (A) to (C) must have a phosphorus content of 800 ppm or
less. Although trace amounts of phosphorus may be present in a base
oil, most of phosphorus is derived from a phosphorus-based additive
to be added to the lubricating oil composition of ran internal
combustion engine. Examples of the phosphorus-based additive
include metal-containing additives such as molybdenum
dithiophosphate and zinc dithiophosphate; extreme-pressure agents
such as monoocytl phosphate, dioctyl phosphate, monooleyl
phosphate, dioleyl phosphate, tributyl phosphate, triphenyl
phosphate, tircresyl phosphate, triphenyl phosphite, tributyl
phosphite, tricresyl phosphite, and a thiophosphoric acid ester;
and detergents such as calcium phosphate, magnesium phosphate, and
barium phosphate.
[0027] Although one or more kinds of those phosphorus-based
additives may be added, the addition amount thereof must be 800 ppm
or less in terms of a phosphorus content. As long as the addition
amount is 800 ppm or less, the amount of high-temperature deposits
generated is nearly immune to the phosphorus concentration.
However, when the phosphorus concentration exceeds 800 ppm, the
amount of high-temperature deposits generated abruptly increases.
However, when the phosphorus concentration is excessively low, the
lubricating oil for an internal combustion engine may be poor in
wear resistance or oxidation-preventing property. Accordingly,
phosphorus is preferably present in a certain amount or more.
Specifically, the phosphorus content is preferably 300 to 800 ppm,
more preferably 500 to 800 ppm. Further, the phosphorus compound
most suitable for the addition is a zinc dithiophosphate excellent
in wear resistance and oxidation-preventing property. The
lubricating oil composition for an internal combustion engine of
the present invention has a kinematic viscosity at 100.degree. C.
of 5 mm.sup.2/s to 12.5 mm.sup.2/s. When the kinematic viscosity is
less than 5 mm.sup.2/s, there is a possibility that oil film does
not sufficiently form and hence wear occurs at sliding surfaces.
When the kinematic viscosity is more than 12.5 mm.sup.2/s, the
following problem arises. The oil film becomes so thick that
friction loss increases to impair fuel-saving performance.
[0028] The term "high-temperature deposit" as used in the present
invention refers to insoluble matter resulting from the lubricating
oil composition for an internal combustion engine, the insoluble
matter being produced at high temperatures of 300.degree. C. or
400.degree. C. or more. The adhesion and deposition of such
high-temperature deposits to, for example, the inside of an engine
or the bearings of a supercharger may induce a reduction in
performance of the engine or the supercharger, or trouble in the
engine or the supercharger. The major feature of the lubricating
oil composition for an internal combustion engine of the present
invention is that the amount of high-temperature deposits generated
is small. Although the composition may be evaluated by any one of
the known test for observing high-temperature deposits, the
composition is preferably evaluated by a TEOST33C test (ASTM D6335)
adopted by the International Lubricant Standardization and Approval
Committee (ILSAC) because an additionally strict evaluation can be
performed. The smaller the amount of high-temperature deposits, the
better. Specifically, the amount is preferably 40 mg or less, more
preferably 30 mg or less in the TEOST33C test because nearly no
reduction in performance of an engine or in performance of a
supercharger is observed at the time of practical use.
[0029] One or more kinds of additives such as viscosity index
improvers, pour point depressants, extreme-pressure agents,
oiliness improvers, antioxidants, metal-based detergents, ashless
dispersants, metal deactivators, rust inhibitors, and anti-foaming
agents are preferably added to the lubricating oil composition for
an internal combustion engine of the present invention as long as
the effects of the present invention are not impaired. Further,
when any such additive is blended, particular attention needs to be
paid so that the phosphorus content with respect to the total
amount of the lubricating oil composition for an internal
combustion engine will be 800 ppm or less, preferably 300 to 800
ppm.
[0030] Examples of viscosity index improvers include poly (C1 to
C18)alkyl methacrylates, (C1 to C18)alkyl crylate/(C1 to C18)alkyl
methacrylate copolymers, diethylaminoethyl methacrylate/(C1 to
C18)alkyl methacrylate copolymers, ehtylene/(C1 to C18)alkyl
mehacrylate copolymers, polyisobutylenes, polyalkylstyrenes,
ethylene/propylene copolymers, styrene/maleic acid ester
copolymers, and styrene/isoprene hydrogenated copolymers.
Alternatively, a dispersion-type or multi-functional viscosity
index improver to which dispersing performance has been imparted
may be used. Its weight-average molecular weight is about 10,000 to
1,500,000, preferably about 30,000 to 1,000,000. Such viscosity
index improver is blended in an amount of preferably 0.1 to 20 mass
%, more preferably 0.3 to 15 mass % with respect to the lubricating
oil composition for an internal combustion engine.
[0031] Examples of pour point depressants include polyalkyl
methacrylates, polyalkyl acrylates, polyalkylstyrenes, and
polyvinyl acetates. Its wieght-average molecular weight is about
1,000 to 100,000, preferably about 3,000 to 80,000. Such pour point
depressant is blended in an amount of preferably 0.005 to 3 mass %,
more preferably 0.01 to 2 mass %, with respect to the lubricating
oil composition for an internal combustion engine.
[0032] Examples of extreme-pressure agents include: sulfur-based
additives such as sulfurinzed oils and fats, olefin polysulfides,
and dibenzyl sulfides; phosphorus-based compounds such as monoocytl
phosphate, tributyl phosphate, triphenyl phosphite, tributyl
phosphite, and thiophosphoric acid esters; and organic metal
compounds such as metal salts of thiophosphoric acid, methal salts
of thiocarbamic acid, and metal salts of an acidic phosphoric acid
ester. Such extreme-pressure agent is blended in an amount of
preferably 0.01 to 2 mass %, more preferably 0.05 to 1 mass % with
respect to the lubricating oil composition of ran internal
combustion engine.
[0033] Examples of oiliness improves include: high alcohols such as
oleyl alcohol and stearyl alcohol; fatty acids such as oleic acid
and stearic acid; esters such as oleyl glycerine ester, stearyl
glycerine ester, and lauryl glycerine ester; amids such as lauryl
amide, oleyl amide, and stearyl amide; amines such as laurylamine,
oleylamine, and stearylamine; and ethers such as lauryl glycerine
ether and oleyl glycerine ether. Such oiliness improver is blended
in an amount of preferably 0.1 to 5 mass %, more preferably 0.2 to
3 mass % with respect to the lubricating oil composition for an
internal combustion engine.
[0034] Examples of antioxidants include: phenol-based antioxidants
such as 2,6-ditertiary butylphenol (hereinafter, tertiarybutyl is
abbreviated as t-butyl), 2,6-di-t-butyl-p-cresol,
2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol,
2,4-dimethyl-6-t-buytlphenol, 4,4'-methylene
bis(2,6-di-t-buytlphenol), 4,4'-bis(2,6-di-t-buytlphenol),
4,4'-bis(2-methyl-6-t-buylphenol), 2,2'-methylene
bis(4-methyl-6-t-butylphenol), 2,2'-methylene
bis(4-ethyl-6-t-buytlphenol), 4,4'-butylidene
bis(3-methyl-6-t-butylphenol), 4,4'-isopropylidene
bis(2,6-di-t-butylphenol), 2,2'-methylene
bis(4-methyl-6-cyclohexylphenol), 2,2'-methylene
bis(4-methyl-6-nonylphenol), 2,2'-isobutylidene
bis(4,6-dimethylphenol),
2,6-bis(2'-hydroxy-3'-t-butyl-5'-mehtylbenzyl)-4-methylphenol,
3-t-butyl-4-hydroxyanisole, 2-t-butyl-4-hydroxyanisole, octyl
3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, stearyl
3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, oleyl
3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, dodecyl
3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, decyl
3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, octyl
3-(4-hydroxy-3,5-di-t-butylphenyl)propionate,
tetrakis{3-(4-hydroxy-3,5-di-t-butylphenyl)propionyl
oxymethyl}methane, 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid
glycerine monoester, an ester of
3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid and glycerine
monooleyl ether, 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid
butylene glycol diester,
3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid thiodiglycol
diester, 4,4'-thiobis(3-methyl-6-t-butylphenol),
4,4'-thiobis(2-methyl-6-t-butylphenol),
2,2'-thiobis(4-methyl-6-t-butylphenol),
2,6-di-t-butyl-.alpha.-dimethylamino-p-cresol,
2,6-di-t-butyl-4-(N,N'-dimethylaminomethylphenol),
bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide,
tris{(3,5-di-t-butyl-4-hydroxyphenyl)propionyl-oxyethyl}
isocyanurate, tris(3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate,
1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, a
bis{2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl}sulfide,
1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate,
tetraphthaloyl-di (2,6-dimethyl-4-t-butyl-3-hydroxybenzyl sulfide),
6-(4-hydroxy-3,5-di-t-butyl
anilino)-2,4-bis(octylthio)-1,3,5-triazine,
2,2-thio-{diethyl-bis-3-(3,5,-di-t-butyl-4-hydroxyphenyl)}
propionate, N,N'-hexamethylene
bis(3,5-di-t-butyl-4-hydroxy-hydrocinnamiide),
3,5-di-t-butyl-4-hydroxy-benzyl-phosphate diester,
bis(3-methyl-4-hydroxy-5-t-butylbenzyl)sulfide,
3,9-bis[1,1-dimethyl-2-{.beta.-(3-t-butyl-4-hydroxy-5-methylphenyl)
propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane,
1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,
and bis{3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid}glycol
ester; naphthylamine-based antioxidants such as 1-naphthylamine,
phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine,
p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-napythylamine, and
phenyl-2-naphthylamine; phenylenediamine-based antioxidants such as
N,N'-diisopropyl-p-phenylenediamine,
N,N'-diisobutyl-p-phenylenediamine,
N,N'-diphenyl-p-phenylenediamine,
N,N'-di-.beta.-naphthyl-p-phenylenediamine,
N-phenyl-N'-isopropyl-p-phenylenediamine,
N-cyclohexyl-N'-phenyl-p-phenylenediamine,
N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine,
dioctyl-p-phenylenediamine, phenylhexyl-p-phenylenediamine, and
phenyloctyl-p-phenylenediamine; diphenylamine--based antioxidants
such as pipyridylamine, diphenylamine,
p,p'-di-n-butyldiphenylamine, p,p'-di-t-buytldiphenylamine,
p,p'-di-t-pentyldiphenylamine, p,p'-dioctyldiphenylamine,
p,p'-dinonyldiphenylamine, p,p'-didecyldiphenylamine,
p,p'-didodecyldiphenylamine, p,p'-distyryldiphenylamine,
p,p'-dimethoxydiphenylamine,
4,4'-bis(4-.alpha.,.alpha.-dimethylbenzoyl)diphenylamine,
p-isopropoxydiphenylamine, and dipyridylamine; phenothiazine-based
antioxidants such as phenothiazine, N-methylphenothiazine,
N-ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazine
carboxylic acid ester, and phenoselenazine; and zinc
dithiophosphate. Such antioxidant is blended in an amount of
preferably 0.01 to 5 mass %, more preferably 0.05 to 4 mass % with
respect to the lubricating oil composition for an internal
combustion engine.
[0035] Examples of metal-based detergents include sulfonates,
phenates, salicylates, and phosphates of calcium, magnesium, and
barium, and perbasic salts thereof. Of those, perbasic salts are
preferred. Of the perbasic salts, a perbasic salt having a total
basic number (TBN) of 30 to 500 mgKOH/g is more preferred. A
salicylate-based detergent free of phosphorus and sulfur atoms is
still more preferred. Such metal-based detergent is blended in an
amount of preferably 0.5 to 10 mass %, more preferably 1 to 8 mass
% with respect to the lubricating oil composition for an internal
combustion engine.
[0036] Examples of ashless dispersants include succinimide, a
succinic acid ester, and benzylamine to each of which an alkyl
group or an alkenyl group has been added and each of which has a
weight-average molecular weight of about 500 to 3,000, and
boron-denatured products thereof. Such ashless dispersant is
blended in an amount of preferably 0.5 to 10 mass %, more
preferably 1 to 8 mass % with respect to the lubricating oil
composition for an internal combustion engine.
[0037] Examples of metal deactivators include benzotriazole,
benzimidazole, benzothiazole, and a tetraalkylthiuram disulfide.
Such metal deactivator is blended in an amount of preferably 0.01
to 3 mass %, more preferably 0.02 to 2 mass % with respect to the
lubricating oil composition for an internal combustion engine.
[0038] Examples of rust inhibitors include sodium nitrite, oxidized
paraffin wax calcium salts, oxidized paraffin was magnesium salts,
beef tallow fatty acid alkali metal salts, alkaline earth metal
salts, or amine salts, alkenyl succinic acids or alkenyl succinic
acid half esters (the molecular weight of the alkenyl group is
about 100 to 300), sorbitan monoester, nonylphenol ethoxylate, and
calcium salt of a lanolin fatty acid. Such rust inhibitor is
blended in an amount of preferably 0.01 to 3 mass %, more
preferably 0.02 to 2 mass % with respect to the lubricating oil
composition for an internal combustion engine.
[0039] Examples of anti-foaming agents include
polydimethylsilicone, trifluoropropylmethylsilicone, colloidal
silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol
ethoxy/propoxylate, fatty acid ethoxy/propoxylate, and sorbitan
partial fatty acid ester. Such anti-foaming agent is blended in an
amount of preferably 0.001 to 0.1 mass %, more preferably 0.001 to
0.01 mass % with respect to the lubricating oil composition for an
internal combustion engine.
[0040] The lubricating oil composition for an internal combustion
engine of the present invention can be used as a lubricating oil
for any internal combustion engine as long as the internal
combustion engine is, for example, a gasoline engine, a diesel
engine, and a natural gas engine (liquefied petroleum gas engine)
and among these the compostion can be favorably used as an engine
oil for gasoline engines.
EXAMPLES
[0041] hereinafter, the present invention is specifically described
by way of examples. It should be noted that the term "%" in the
following examples and the like refers to "mass %" unless otherwise
stated.
[0042] Lubricating oil compostions for internal combustion engines
(test oils) used in test were produced in accordance with the
recipes shown in Table 1 and Table 2 below, and were then subjected
to the TEOST33C test and a fuel-saving property test by the
following methods. Table 1 and Table 2 shows the results. It should
be noted that Table 3 shows a base oil used in blending and its
properties.
[0043] <TEOST33C Test: High-Temperature Deposit Test>
[0044] A test was performed in conformity with the test method of
ASTM D6335 with a TEOST33C tester (manufactured by Tannas Co.).
FIG. 1 is a schematic view of the TEOST33C tester. The specific
test method is as described below. While a rod (metal rod) (2) in a
case (1) of the apparatus illustrated in FIG. 1 was heated and
cooled so that its temperature was as shown in FIG. 2, a certain
amount of a test oil was made to flow from a reaction chamber (4)
storing the test oil into the rod (2) in the case (1) by a pump
(3). The step is defined as 1 cycle and the cycle was repeated 12
times. After that, the rod was taken out, and then the mass of
deposits adhering thereto and the mass of deposits in the test oil
obtained by filtering the total amount of the test oil through a
filter were measured. The total of the masses was defined as a
high-temperature deposit amount. Further, certain amounts of air
containing moisture and a nitrogen monoxide gas were blown into the
test oil in the reaction chamber (4). Further, air bubbled in 30 ml
of water in a 50-ml flask was used as the air containing
moisture.
[0045] Detailed test conditions are described below.
(Test Condition)
Temperature: 200 to 480.degree. C
[0046] Test cycle: 12 cycles Testing time: 9.5 minutes per cycle
(total testing time: 114 minutes) Amount of test oil: 106 ml
[0047] Catalyst: iron maphthenate (added to the test oil in an
amount of 100 ppm in terms of iron content)
Pump rate: 0.49 ml/min
[0048] Flow rate of N.sub.2O gas: 3.5 ml/min
[0049] Flow rate of air: 3.5 ml/min
[0050] <Fuel-Saving Property Test>
[0051] The coefficient of friction of each test oil was measured
with an SRV tester under the following conditions. A lower
coefficient of friction means higher fuel-saving property.
Upper test piece: a columnar test piece (.phi.15.times.22 mm,
material: USJ-2) Lower test piece: a disc-like test piece
(.phi.24.times.6.85 mm, material: SUJ-2)
Load: 200 N
Amplitude: 1.0 mm
Cycle: 50 Hz
[0052] Measurement temperature: 80.degree. C. Measurement time: 15
minutes
TABLE-US-00001 TABLE 1 Inventive Product 1 2 3 4 5 6 Viscosity
index improver 3.4 3.4 3.4 3.4 3.4 3.4 Detergent 2.0 2.0 2.0 2.0
2.0 2.0 Dispersant 4.0 4.0 4.0 4.0 4.0 4.0 Antioxidant 2.0 2.0 2.0
2.0 2.0 2.0 Zinc dithiophosphate 0.9 0.9 0.7 0.9 0.9 0.9 Molybdenum
dithiocarbamate 0.4 0.4 0.4 0.4 0.4 0.4 Base oil Mineral oil 1 9 9
28 1 9 Synthetic oil 1 9 Mineral oil 2 Balance Balance Balance
Balance Mineral oil 3 Balance Synthetic oil 2 Balance Phosphorus
content (ppm) 780 780 600 780 780 780 Mo content (ppm) 700 700 700
700 700 700 Test result Product viscosity at 9.7 8.1 9.7 12.1 9.7
9.8 100.degree. C. (mm.sup.2/s) High-temperature 22 26 23 23 34 22
deposit amount (mg) Fuel-saving property 0.52 0.53 0.52 0.58 0.52
0.56 test *The amount of the entirety was adjusted to 100 with the
base oil described as "balance."
TABLE-US-00002 TABLE 2 Comparative Product 1 2 3 4 5 6 Viscosity
index improver 3.4 3.4 3.4 3.4 3.4 3.4 Detergent 2.0 2.0 2.0 2.0
2.0 2.0 Dispersant 4.0 4.0 4.0 4.0 4.0 4.0 Antioxidant 2.0 2.0 2.0
2.0 2.0 2.0 Zinc dithiophosphate 0.9 0.9 0.9 1.1 0.9 0.9 Tricresyl
phosphate 0.5 Molybdenum dithiocarbamate 0.4 0.4 0.4 0.4 0.4 Base
oil Mineral oil 1 9 9 Synthetic oil 1 Mineral oil 2 Balance Balance
Balance Balance Mineral oil 3 Balance Synthetic oil 2 Balance
Phosphorus content (ppm) 780 780 780 950 1,200 780 Mo content (ppm)
700 700 700 700 700 700 Test result Product viscosity at 8.6 7.0
5.2 9.7 9.7 8.6 100.degree. C. (mm.sup.2/s) High-temperature 60 63
92 44 58 21 deposit amount (mg) Fuel-saving property 0.52 0.52 0.53
0.52 0.52 1.08 test *The amount of the entirety was adjusted to 100
with the base oil described as "balance."
[0053] Further, the details of each component include in the
products of the present invention and the comparative products are
as follows.
Viscosity index improver: polymethacrylate-based viscosity index
improver Detergent: calcium salicylate (TBN280) Dispersant:
polyalkenyl succinimide Antioxidant: mixture of benzenepropanoic
acid 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxyoctyl ester and
dioctyldiphenylamine (mass ratio: 1/1) Zinc dithiophosphate: zinc
dialkyldithiophosphate whose alkyl group is linear and a mixture of
alkyl groups having 4 to 6 carbons atoms (phosphorus content:
8.67%) Molybdenum dithiocarbamate: molybdenum dithiocarbamate of
the general formula (1) in which R.sup.1 to R.sup.4 each represent
a mixture of groups having 8 or 13 carbon atoms, X.sup.1 and
X.sup.2 each represent an oxygen atom, and X.sup.3 and X.sup.4 each
represent a sulfur atom (molybdenum content: 17.5%) The kind and
properties of each base oil used in the experiments are as
described in Table 3 below.
TABLE-US-00003 TABLE 3 Kinematic viscosity Viscosity at 100.degree.
C. (mm.sup.2/s) Index Component B Mineral oil 1 32.8 95 (bright
stock) Synthetic oil 1 39.5 149 (PAO) Component C Mineral oil 2
4.24 122 (hydocracked oil) Mineral oil 3 4.39 102 (solvent-refined
oil) Synthetic oil 2 4.04 119 (PAO) PAO: Poly-.alpha.-olefin
* * * * *