U.S. patent application number 13/638997 was filed with the patent office on 2013-01-24 for lubricant composition for an internal combustion engine.
This patent application is currently assigned to Idemitsu Kosan Co., Ltd.. The applicant listed for this patent is Motoharu Ishikawa, Kazuhiro Teshima. Invention is credited to Motoharu Ishikawa, Kazuhiro Teshima.
Application Number | 20130023456 13/638997 |
Document ID | / |
Family ID | 44762817 |
Filed Date | 2013-01-24 |
United States Patent
Application |
20130023456 |
Kind Code |
A1 |
Teshima; Kazuhiro ; et
al. |
January 24, 2013 |
LUBRICANT COMPOSITION FOR AN INTERNAL COMBUSTION ENGINE
Abstract
A lubricating oil composition for an internal combustion engine
contains a component (A) of a polyalphaolefin having a kinematic
viscosity at 100 degrees C. of 5.5 mm.sup.2/s or less, a CCS
viscosity at -35 degrees C. of 3000 mPAs or less and a NOACK of 12
mass % or less, and a component (B) of a mineral oil having a
viscosity index of 120 or more. The component (A) is contained at a
content of 25 mass % or more of a total amount of the
composition.
Inventors: |
Teshima; Kazuhiro;
(Ichihara-shi, JP) ; Ishikawa; Motoharu;
(Ichihara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Teshima; Kazuhiro
Ishikawa; Motoharu |
Ichihara-shi
Ichihara-shi |
|
JP
JP |
|
|
Assignee: |
Idemitsu Kosan Co., Ltd.
Tokyo
JP
|
Family ID: |
44762817 |
Appl. No.: |
13/638997 |
Filed: |
March 31, 2011 |
PCT Filed: |
March 31, 2011 |
PCT NO: |
PCT/JP11/58291 |
371 Date: |
October 2, 2012 |
Current U.S.
Class: |
508/591 |
Current CPC
Class: |
C10N 2020/02 20130101;
C10M 2205/0285 20130101; C10N 2030/74 20200501; C10M 111/04
20130101; C10M 2203/1025 20130101; C10N 2030/54 20200501; C10N
2070/00 20130101; C10M 2209/084 20130101; C10N 2040/25 20130101;
C10N 2030/02 20130101; C10M 2203/1006 20130101 |
Class at
Publication: |
508/591 |
International
Class: |
C10M 143/08 20060101
C10M143/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2010 |
JP |
2010-086581 |
Claims
1. A lubricating oil composition for an internal combustion engine,
comprising: a component (A) of a polyalphaolefin having a kinematic
viscosity at 100 degrees C. of 5.5 mm.sup.2/s or less, a CCS
viscosity at -35 degrees C. of 3000 mPas or less and a NOACK of 12
mass % or less; and a component (B) of a mineral oil having a
viscosity index of 120 or more; wherein the component (A) is
present in an amount of 25 mass % or more of a total amount of the
composition.
2. The lubricating oil composition according to claim 1, wherein a
kinematic viscosity at 100 degrees C. of a mixed base oil provided
by blending the components (A) and (B) is 4.6 mm.sup.2/s or
less.
3. The lubricating oil composition according to claim 1, wherein
the NOACK of the composition is 10 mass % or less and the CCS
viscosity at -35 degrees C. is 6000 mPas or less.
4. The lubricating oil composition according to claim 1, wherein
the component (B) is present in an amount of 20 mass % or more of
the total amount of the composition.
5. The lubricating oil composition according to claim 1, wherein
the component (A) is provided by polymerization with a metallocene
catalyst.
6. The lubricating oil composition according to claim 1, wherein
the component (A) is a polyalphaolefin formed by at least one of
alpha-olefins having 10 to 14 carbon atoms as a monomer unit.
7. The lubricating oil composition according to claim 1, wherein
the component (A) is a trimer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a lubricating oil
composition for an internal combustion engine.
BACKGROUND ART
[0002] In an internal combustion engine such as a gasoline engine
and a diesel engine, carbon deposits called caulking may be formed
inside the engine during use. Generation of caulking causes an
insufficient cooling inside the engine or blocks a flow of the
lubricating oil, which may bring various damages. Particularly in
the engine provided with a turbo mechanism, caulking generated in a
turbo bearing, a housing or an oil supply path is a problem.
[0003] In order to prevent generation of caulking, use of a
lubricating oil having a low vaporizability is effective. As the
lubricating oil having a low vaporizability for the internal
combustion engine, a composition including a blend of a base oil of
Group II or Group III in the API classification and a low viscous
PAO has been proposed (see Patent Literatures 1 and 2).
CITATION LIST
Patent Literature(s)
[0004] Patent Literature 1 JP-T-2008-533274
[0005] Patent Literature 2 JP-T-2009-510214
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0006] On the other hand, fuel-saving performance is also an
important factor in the lubricating oil for the internal combustion
engine. However, since the lubricating oil having a low
vaporizability generally exhibits a high viscosity, fuel-saving
performance may be deteriorated. The lubricating oil compositions
disclosed in Patent Literatures 1 and 2 are not necessarily
sufficient in a balance of a low vaporizability and fuel-saving
performance.
[0007] An object of the invention is to provide a lubricating oil
composition for an internal combustion engine which exhibits a low
vaporizability, an excellent caulking resistance and an excellent
fuel-saving performance.
Means for Solving the Problems
[0008] In order to solve the above-mentioned problems, according to
an aspect of the invention, lubricating oil compositions for an
internal combustion engine as follows are provided. [0009] (1)
According to an aspect of the invention, a lubricating oil
composition for an internal combustion engine contains a component
(A) of a polyalphaolefin having a kinematic viscosity at 100
degrees C. of 5.5 mm.sup.2/s or less, a CCS viscosity at -35
degrees C. of 3000 mPas or less and a NOACK of 12 mass % or less,
and a component (B) of a mineral oil having a viscosity index of
120 or more, the component (A) being contained at a content of 25
mass % or more of a total amount of the composition. [0010] (2) In
the above aspect of the invention, a kinematic viscosity at 100
degrees C. of a mixed base oil provided by blending the components
(A) and (B) is 4.6 mm.sup.2/s or less. [0011] (3) In the above
aspect of the invention, the NOACK of the composition is 10 mass %
or less and the CCS viscosity at -35 degrees C. is 6000 mPas or
less. [0012] (4) In the above aspect of the invention, the
component (B) is contained at a content of 20 mass % or more of the
total amount of the composition. [0013] (5) In the above aspect of
the invention, the component (A) is provided by polymerization with
a metallocene catalyst. [0014] (6) In the above aspect of the
invention, the component (A) is a polyalphaolefin formed by at
least one of alpha-olefins having 10 to 14 carbon atoms as a
monomer unit. [0015] (7) In the above aspect of the invention, the
component (A) is a trimer.
Advantages(s) of the Invention
[0016] Since the lubricating oil composition for the internal
combustion engine according to the above aspect of the invention
contains a PAO having specific properties and a mineral oil having
specific properties, the lubricating oil composition exhibits a low
vaporizability, an excellent caulking resistance and an excellent
fuel-saving performance. Accordingly, the composition according to
the above aspect of the invention is also suitable to a gasoline
engine and a diesel engine which are provided with a turbo
mechanism.
DESCRIPTION OF EMBODIMENT(S)
[0017] In an exemplary embodiment of the invention, a lubricating
oil composition for an internal combustion engine contains a
component (A) of a polyalphaolefin having a kinematic viscosity at
100 degrees C. of 5.5 mm.sup.2/s or less, a CCS viscosity at -35
degrees C. of 3000 mPas or less and a NOACK of 12 mass % or less,
and a component (B) of a mineral oil having a viscosity index of
120 or more. The lubricating oil composition will be described in
detail below.
Component (A)
[0018] The component (A) in this exemplary embodiment is a
polyalphaolefin (PAO) in a form of a polymer (oligomer) of
alpha-olefins.
[0019] In terms of fuel-saving performance, the kinematic viscosity
at 100 degrees C. of the PAO (i.e., the component (A)) is required
to be 5.5 mm.sup.2/s or less. However, in terms of lubricity, the
kinematic viscosity at 100 degrees C. thereof is preferably 3
mm.sup.2/s or more. The CCS viscosity at -35 degrees C. is required
to be 3000 mPas or less. Moreover, in terms of a low
vaporizability, the NOACK is also required to be 12 mass % or
less.
[0020] The number of carbon atoms of an alpha-olefin (i.e., a
monomer unit) for such a PAO is preferably from 6 to 20 in terms of
a viscosity index, a pour point, low temperature properties (e.g.,
a low-temperature viscosity) and vaporizability, more preferably
from 8 to 16, particularly preferably 10 to 14. The PAO is
preferably a trimer of alpha-olefins in terms of a low
vaporizability, caulking resistance and a low fuel-saving
performance. In order to provide the PAO with such intended
properties, the number of carbon atoms, a blend ratio and a
polymerization degree of the alpha-olefins are adjustable.
[0021] As a polymerization catalyst for the alpha-olefins, a
BF.sub.3 catalyst, an AlCl.sub.3 catalyst, a Ziegler-type catalyst
and a metallocene catalyst are usable. Typically, the BF.sub.3
catalyst has been used for a low viscous PAO having a kinematic
viscosity at 100 degrees C. of less than 30 mm.sup.2/s while the
AlCl.sub.3 catalyst has been used for a low viscous PAO having a
kinematic viscosity at 100 degrees C. of 30 mm.sup.2/s or more. In
terms of a low vaporizability, caulking resistance and a low
fuel-saving performance, the BF.sub.3 catalyst and the metallocene
catalyst are particularly preferable.
[0022] The BF.sub.3 catalyst is used along with a promoter such as
water, alcohol and esters, among which alcohol, especially
1-butanol, is preferable in terms of the viscosity index, the low
temperature properties and a yield.
[0023] The metallocene catalyst is exemplified by a catalyst
including a combination of a metallocene compound and a promoter.
The metallocene compound is preferably a metallocene compound
represented by the following formula (1).
(RC.sub.5H.sub.4).sub.2MX.sub.2 (1)
[0024] In the formula (1), R is a hydrogen atom or a hydrocarbon
group having 1 to 10 carbon atoms, M is a transition metal element
in Group 4 of the periodic table, and X is a covalent ligand or an
ion binding ligand.
[0025] In the formula (1), R is preferably a hydrogen atom or a
hydrocarbon group having 1 to 4 carbon atoms. Specific examples of
M include titanium, zirconium and hafnium, among which zirconium is
preferable. Specific examples of X include a hydrogen atom, a
halogen atom, a hydrocarbon group having 1 to 20 carbon atoms
(preferably 1 to 10 carbon atoms), an alkoxy group having 1 to 20
carbon atoms (preferably 1 to 10 carbon atoms), an amino group, a
phosphorus-containing hydrocarbon group having 1 to 20 carbon atoms
(preferably 1 to 12 carbon atoms) (e.g., a diphenyl phosphine
group), a silicon-containing hydrocarbon group having 1 to 20
carbon atoms (preferably 1 to 12 carbon atoms) (e.g., a
trimethylsilyl group), and a boron compound containing a
hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 12
carbon atoms) or halogen (e.g., B(C.sub.6H.sub.5).sub.4 and
BF.sub.4), among which a group selected from the group consisting
of a hydrogen atom, a halogen atom, a hydrocarbon group and an
alkoxy group is preferable.
[0026] Examples of the metallocene compound represented by the
formula (1) include bis(cyclopentadienyl)zirconium dichloride,
bis(methylcyclopentadienyl)zirconium dichloride,
bis(ethylcyclopentadienyl)zirconium dichloride,
bis(iso-propylcyclopentadienyl)zirconium dichloride,
bis(n-propylcyclopentadienyl)zirconium dichloride,
bis(n-butylcyclopentadienyl)zirconium dichloride,
bis(t-butylcyclopentadienyl)zirconium dichloride,
bis(thexylcyclopentadienyl)zirconium dichloride,
bis(trimethylsilylcyclopentadienyl)zirconium dichloride,
bis(trimethylsilylmethylcyclopentadienyl)zirconium dichloride,
bis(cyclopentadienyl)zirconium chlorohydride,
bis(cyclopentadienyl)methyl zirconium chloride,
bis(cyclopentadienyl)ethyl zirconium chloride,
bis(cyclopentadienyl)methoxy zirconium chloride,
bis(cyclopentadienyl)phenyl zirconium chloride,
bis(cyclopentadienyl)dimethyl zirconium,
bis(cyclopentadienyl)diphenyl zirconium,
bis(cyclopentadienyl)dineopentyl zirconium,
bis(cyclopentadienyl)dihydro zirconium,
bis(cyclopentadienyl)dimethoxy zirconium, a compound obtained by
substituting a chlorine atom with a bromine atom, a iodine atom, a
hydrogen atom, a methyl group, a phenyl group or the like in the
above compounds, and a compound obtained by substituting zirconium
(central metal) with titanium or hafnium in the above
compounds.
[0027] The promoter is preferably methylaluminoxane.
Methylaluminoxane is subject to no specific limitation. Known
methylaluminoxane is usable, examples of which include a linear
methylaluminoxane represented by the following formula (2) and a
cyclic methylaluminoxane represented by the following formula
(3).
##STR00001##
[0028] In the formulae (2) and (3), p represents a polymerization
degree of typically 3 to 50, preferably 7 to 40.
[0029] A manufacturing method of methylaluminoxane is exemplified
by a method of contacting methyl aluminium with a condensation
agent (e.g., water), but the manufacturing method is subject to no
specific limitation and methylaluminoxane may be manufactured by
reaction according to any known method.
[0030] A blend ratio between the metallocene compound and
methylaluminoxane (methylaluminoxane/the metallocene compound (a
molar ratio)) is typically from 15 to 150, preferably from 20 to
120, more preferably from 25 to 100. At the blend ratio of 15 or
more, a catalyst activity is expressed and a yield of a trimer or a
multimer suitable for a lubricating base oil is not decreased since
a dimer of alpha-olefins are formed. On the other hand, at the
blend ratio of 150 or less, incomplete removal of the catalyst is
avoided.
[0031] Other than the above metallocene catalyst, the metallocene
catalyst is exemplified by a metallocene catalyst using a
metallocene compound having a crosslinking group. Such a
metallocene compound is preferably a metallocene compound having
two crosslinking groups, particularly preferably a metallocene
compound having meso-symmetry. The metallocene catalyst using the
metallocene compound having meso-symmetry is exemplified by a
metallocene catalyst containing: a catalyst component (a) of a
metallocene compound represented by the following formula (4); and
a catalyst component (b) containing a catalyst component (b-1) of a
compound capable of forming an ionic complex by reacting with the
metallocene compound of the component (a) or derivatives thereof,
and a catalyst component (b-2) of at least one of aluminoxanes.
##STR00002##
[0032] The compound represented by the formula (4) has
meso-symmetry. In the formula (4), M represents a metal atom in
Group 3 to Group 10 of the periodic table. X represents a a bonding
ligand. When a plurality of X exist, the plurality of X may be the
same or different. Y represents a Lewis base. When a plurality of Y
exist, the plurality of Y may be the same or different. A
represents a crosslinking group selected from a hydrocarbon group
having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group
having 1 to 20 carbon atoms, a silicon-containing group, a
germanium-containing group, a stannum-containing group, --O--,
--CO--, --S--, --SO.sub.2--, --Se--, --NR.sup.1--, --PR.sup.1--,
--PR.sup.1--, --P(O)R.sup.1--, --BR.sup.1-- and --AlR.sup.1--. Two
A may be the same or different. R.sup.1 represents a hydrogen atom,
a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms or
a halogen-containing hydrocarbon group having 1 to 20 carbon atoms.
q is an integer of 1 to 5 representing [(a valence of M)-2]. r is
an integer of 0 to 3. E represents a group represented by the
following formulae (5) and (6). Two E are the same.
[0033] It should be noted that the compound having meso-symmetry
means a transitional metal compound that crosslinks the two E with
two crosslinking groups in a bonding patterns (1,1') and
(2,2').
##STR00003##
[0034] In the formulae (5) and (6), R.sup.2 represents a group
selected from the group consisting of a hydrogen atom, a halogen
atom, a hydrocarbon group having 1 to 20 carbon atoms, a
halogen-containing hydrocarbon group having 1 to 4 carbon atoms, a
silicon-containing group and a hetero-atom-containing group. When a
plurality of R.sup.2 exist, the plurality of R.sup.2 may be the
same or different. A bond shown in a wavy line represents a bond to
the crosslinking group A.
[0035] The crosslinking group A in the formula (4) is preferably a
group represented by the following formula (7).
##STR00004##
[0036] In the formula (7), B is a skeleton of the crosslinking
group and represents a carbon atom, a silicon atom, a boron atom, a
nitrogen atom, a germanium atom, a phosphorus atom or an aluminium
atom. R.sup.3 represents a hydrogen atom, a carbon atom, an oxygen
atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon
group, an amine-containing group or a halogen-containing group. n
is 1 or 2.
[0037] Examples of the metallocene compound represented by the
formula (4) include
(1,1'-ethylene)(2,2'-ethylene)-bis(indenyl)zirconium dichloride,
(1,1'-methylene)(2,2'-methylene)-bis(indenyl)zirconium dichloride,
(1,1'-isopropylidene)(2,2'-isopropylidene)-bis(indenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(3-methylindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(4,5-benzoindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(4-isopropylindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(5,6-dimethylindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(4,7-diisopropylindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(4-phenylindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(3-methyl-4-isopropylindenyl)zirconium
dichloride,
(1,1'-ethylene)(2,2'-ethylene)-bis(5,6-benzoindenyl)zirconium
dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(cyclopentadienyl)zirco-
nium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(indenyl)zirconium
dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(3-methylindenyl)zircon-
ium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(3-n-butylindenyl)zirco-
nium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(3-i-propylindenyl)zirc-
onium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(3-trimethylsilylmethyl-
indenyl)zirconium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(3
-phenylindenyl)zirconium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(4,5-benzoindenyl)zirco-
nium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(4-isopropylindenyl)zir-
conium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(5,6-dimethylindenyl)zi-
rconium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(4,7-di-i-propylindenyl-
)zirconium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(4-phenylindenyl)zircon-
ium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(3-methyl-4-i-propylind-
enyl)zirconium dichloride,
(1,1'-dimethylsilylene)(2,2'-dimethylsilylene)-bis(5,6-benzoindenyl)zirco-
nium dichloride, and a compound obtained by substituting zirconium
of the above compounds with titanium or hafnium. The metallocene
compound is not limited to the above compounds.
[0038] As the catalyst component (b-1) of the catalyst component
(b), any compounds are usable as long as the compounds can form an
ionic complex by reacting with the metallocene compound of the
catalyst component (a). A compound represented by the following
formula (8) or (9) is preferably usable.
([L.sup.1-R.sup.4].sup.k+).sub.a([Z].sup.-).sub.b (8)
([L.sup.2].sup.k+).sub.a([Z].sup.-).sub.b (9)
[0039] In the formulae (8) and (9), L.sup.1 represents a Lewis base
and L.sup.2 represents M.sup.2, R.sup.5R.sup.6M.sup.3,
R.sup.7.sub.3C or R.sup.8M.sup.3. [Z].sup.- represents a
non-coordinating anion [Z.sup.1].sup.- or [Z.sup.2].sup.-. Herein,
[Z.sup.1].sup.- represents an anion in which a plurality of groups
are bonded to an element, namely, [M.sup.1G.sup.1G.sup.2 . . .
G.sup.f ].sup.- (in which M.sup.1 represents an element in Group 5
to Group 15 of the periodic table, preferably an element in Group
13 to Group 15. G.sup.1 to G.sup.f each represent a hydrogen atom,
a halogen atom, an alkyl group having 1 to 20 carbon atoms, a
dialkylamino group having 2 to 40 carbon atoms, an alkoxy group
having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon
atoms, an aryloxy group having 6 to 20 carbon atoms, an alkyl aryl
group having 7 to 40 carbon atoms, an aryl alkyl group having 7 to
40 carbon atoms, a halogen-substituted hydrocarbon group having 1
to 20 carbon atoms, an acyloxy group having 1 to 20 carbon atoms,
an organic metalloid group or a hetero-atom-containing hydrocarbon
group having 2 to 20 carbon atoms. Two or more of G.sup.1 to
G.sup.f may form a ring. f represents an integer of [(a valence of
the central metal M.sup.1)+1].) [Z.sup.2].sup.- represents a
Bronsted acid alone in which a logarithm (pKa) of a reciprocal
number of an acid dissociation constant is -10 or less, a conjugate
base of a combination of the Bronsted acid and a Lewis acid, or a
conjugate base of an acid defined as a superstrong acid. Moreover,
the Lewis base may be coordinated. R.sup.4 represents a hydrogen
atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an
alkyl aryl group or an aryl alkyl group having 6 to 20 carbon
atoms. R.sup.5 and R.sup.6 each represent a cyclopentadienyl group,
a substituted cyclopentadienyl group, an indenyl group or a
fluorenyl group. R.sup.7 represents an alkyl group, an aryl group,
an alkyl aryl group or an aryl alkyl group having 1 to 20 carbon
atoms. R.sup.8 represents a macrocyclic ligand such as
tetraphenylporphyrin and phthalocyanine k is an integer of 1 to 3
representing an ionic valence of [L.sup.1- R.sup.4] and [L.sup.2].
a is an integer of 1 or more and b=(k.times.a) M.sup.2 represents
an element in Group 1 to Group 3, Group 11 to Group 13, and Group
17 of the periodic table. M.sup.3 represents an element in Group 7
to Group 12.
[0040] Specific examples of L.sup.1 include: amines such as
ammonia, methylamine, aniline, dimethylamine, diethylamine,
N-methylaniline, diphenylamine, N,N-dimethylaniline,
trimethylamine, triethylamine, tri-n-butylamine,
methyldiphenylamine, pyridine, p-bromo-N,N-dimethylaniline and
p-nitro-N,N-dimethylaniline; phosphines such as triethylphosphine,
triphenylphosphine and diphenylphosphine; thioethers such as
tetrahydrothiophene; esters such as ethyl benzoate; and nitriles
such as acetonitrile and benzonitrile.
[0041] Specific examples of R.sup.4 include hydrogen, a methyl
group, an ethyl group, a benzyl group and a trityl group. Specific
examples of R.sup.5 and R.sup.6 include a cyclopentadienyl group, a
methyl cyclopentadienyl group, an ethyl cyclopentadienyl group and
a pentamethyl cyclopentadienyl group. Specific examples of R.sup.7
include a phenyl group, a p-tolyl group and a p-methoxyphenyl
group. Specific examples of R.sup.8 include tetraphenylporphyrin,
phthalocyanine, allyl and methallyl. Specific examples of M.sup.2
include Li, Na, K, Ag, Cu, Br and I. Specific examples of M.sup.3
include Mn, Fe, Co, Ni and Zn. In [Z.sup.1].sup.-, namely,
[M.sup.1G.sup.1G.sup.2 . . . G.sup.f].sup.-, specific examples of
M.sup.1 include B, Al, Si, P, As and Sb, among which B and Al are
preferable. Specific examples of G.sup.1 and G.sup.2 to G.sup.f
include: a dialkylamino group such as a dimethylamino group and a
diethylamino group; an alkoxy group or aryloxy group such as a
methoxy group, an ethoxy group, an n-butoxy group and a phenoxy
group; a hydrocarbon group such as a methyl group, an ethyl group,
an n-propyl group, an isopropyl group, an n-butyl group, an
isobutyl group, an n-octyl group, an n-eicosyl group, a phenyl
group, a p-tolyl group, a benzyl group, a 4-t-butylphenyl group and
a 3,5-dimethylphenyl group; a halogen atom such as fluorine,
chlorine, bromine and iodine; a hetero-atom-containing hydrocarbon
group such as a p-fluorophenyl group, a 3,5-difluorophenyl group, a
pentachlorophenyl group, a 3,4,5-trifluorophenyl group, a
pentafluorophenyl group, a 3,5-bis(trifluoromethyl)phenyl group and
a bis(trimethylsilyl)methyl group; an organic metalloid group such
as a pentamethyl antimony group, a trimethylsilyl group, a
trimethyl germyl group, a diphenyl arsine group, a dicyclohexyl
antimony group and diphenyl boron.
[0042] Specific examples of the non-coordinating anion
[Z.sup.2].sup.-, namely, the Bronsted acid alone having pKa of -10
or less or the conjugate base of a combination of the Bronsted acid
and a Lewis acid include a trifluoromethanesulfonate anion
(CF.sub.3SO.sub.3).sup.-, a bis(trifluoromethanesulfonyl)methyl
anion, a bis(trifluoromethanesulfonyl)benzyl anion,
bis(trifluoromethanesulfonyl)amide, a perchloric acid anion
(ClO.sub.4).sup.-, a trifluoroacetate anion
(CF.sub.3CO.sub.2).sup.-, a hexafluoroantimony anion
(SbF.sub.6).sup.-, a fluorosulfonic acid anion (FSO.sub.3).sup.-, a
chlorosulfonic acid anion (ClSO.sub.3).sup.-, a fluorosulfonic acid
anion/antimony pentafluoride (FSO.sub.3/SbF.sub.5).sup.-, a
fluorosulfonic acid anion/arsenic pentafluoride
(FSO.sub.3/AsF.sub.5).sup.- and a
trifluoromethanesulfonate/antimony pentafluoride
(CF.sub.3SO.sub.3/SbF.sub.5).sup.-.
[0043] Specific examples of the ionic compound (i.e., the catalyst
component (b-1)) for forming an ionic complex by reacting with the
transitional metal compound of the catalyst component (a) include
N,N-dimethyl anilinium tetrakis(pentafluorophenylborate),
triethylammonium tetraphenylborate, tri-n-butyl ammonium
tetraphenylborate, trimethyl ammonium tetraphenylborate, tetraethyl
ammonium tetraphenylborate, methyl(tri-n-butyl)ammonium
tetraphenylborate, benzyl(tri-n-butyl)ammonium tetraphenylborate,
dimethyldiphenyl ammonium tetraphenylborate,
triphenyl(methyl)ammonium tetraphenylborate, trimethyl anilinium
tetraphenylborate, methylpyridinium tetraphenylborate,
benzylpyridinium tetraphenylborate, methyl(2-cyanopyridinium)
tetraphenylborate, triethyl ammonium
tetrakis(pentafluorophenyl)borate, tri-n-butyl ammonium
tetrakis(pentafluorophenyl)borate, triphenyl ammonium
tetrakis(pentafluorophenyl)borate, tetra-n-butyl ammonium
tetrakis(pentafluorophenyl)borate, tetraethyl ammonium
tetrakis(pentafluorophenyl)borate, benzyl(tri-n-butyl)ammonium
tetrakis(pentafluorophenyl)borate, methyldiphenyl ammonium
tetrakis(pentafluorophenyl)borate, triphenyl(methyl)ammonium
tetrakis(pentafluorophenyl)borate, methyl anilinium
tetrakis(pentafluorophenyl)borate, dimethyl anilinium
tetrakis(pentafluorophenyl)borate, trimethyl anilinium
tetrakis(pentafluorophenyl)borate, methyl pyridinium
tetrakis(pentafluorophenyl)borate, benzyl pyridinium
tetrakis(pentafluorophenyl)borate, methyl(2-cyanopyridinium)
tetrakis(pentafluorophenyl)borate, benzyl(2-cyanopyridinium)
tetrakis(pentafluorophenyl)borate, methyl(4-cyanopyridinium)
tetrakis(pentafluorophenyl)borate, triphenyl phosphonium
tetrakis(pentafluorophenyl)borate, dimethyl anilinium
tetrakis[bis(3,5-ditrifluoromethyl)phenyl]borate, ferrocenium
tetraphenylborate, silver tetraphenylborate, trityl
tetraphenylborate, tetraphenyl porphyrin manganese
tetraphenylborate, ferrocenium tetrakis(pentafluorophenyl)borate,
(1,1'-dimethyl ferrocenium) tetrakis(pentafluorophenyl)borate,
decamethyl ferrocenium tetrakis(pentafluorophenyl)borate, silver
tetrakis(pentafluorophenyl)borate, trityl
tetrakis(pentafluorophenyl)borate, lithium
tetrakis(pentafluorophenyl)borate, sodium
tetrakis(pentafluorophenyl)borate, tetraphenyl porphyrin manganese
tetrakis(pentafluorophenyl)borate, silver tetrafluoroborate, silver
hexafluorophosphate, silver hexafluoroarsenate, silver perchlorate,
silver trifluoroacetate and silver trifluoromethane sulfonate. One
of the catalyst components (B-1) may be singularly used or at least
two thereof may be used in combination.
[0044] Examples of the aluminoxanes of the catalyst component (b-2)
include a linear aluminoxane represented by the following formula
(10) and a cyclic aluminoxane represented by the following formula
(11).
##STR00005##
[0045] In the formulae (10) and (11), R.sup.9 represents a
hydrocarbon group having 1 to 20 carbon atoms (preferably 1 to 12
carbon atoms) such as an alkyl group, an alkenyl group, an aryl
group and an aryl alkyl group, or a halogen atom. w represents an
average polymerization degree of an integer typically of 2 to 50,
preferably of 2 to 40. It should be noted that R.sup.9 may be the
same or different.
[0046] A manufacturing method of the above-described aluminoxanes
is exemplified by a method of contacting alkyl aluminium with a
condensation agent (e.g., water), but the manufacturing method is
subject to no specific limitation. The aluminoxanes may be
manufactured by reaction according to any known method.
[0047] Examples of the method include (1) a method of dissolving an
organic aluminium compound in an organic solvent and contacting the
obtained solution with water, (2) a method of initially adding an
organic aluminium compound at the time of polymerization and later
adding water, (3) a method of reacting crystallization water
contained in metal salts and the like and adsorption water on an
inorganic/organic substance with an organic aluminium compound, and
(4) a method of reacting tetraalkyl dialuminoxane with trialkyl
aluminium, followed by further reaction with water. It should be
noted that the aluminoxanes may be insoluble in toluene. One of the
aluminoxanes may be singularly used, or at least two thereof may be
used in combination.
[0048] When the catalyst component (b-1) is used as the catalyst
component (b), a ratio of the catalyst component (a) and the
catalyst component (b) in use is preferably in a range of 10:1 to
1:100 in a molar ratio, more preferably in a range of 2:1 to 1:10.
When the ratio is out of the range, a catalyst cost per unit mass
of polymer is impractically increased. When the catalyst component
(b-2) is used as the catalyst component (b), the ratio of the
catalyst component (a) and the catalyst component (b) is preferably
in a range of 1:1 to 1:1000000 in a molar ratio, more preferably in
a range of 1:10 to 1:10000. When the ratio is out of the range, a
catalyst cost per unit mass of polymer is impractically increased.
Moreover, as the catalyst component (b), one of the compounds of
the catalyst component (b-1) and the catalyst component (b-2) may
be singularly used, or at least two of the compounds may be used in
combination.
[0049] In this exemplary embodiment of the invention, a monomer for
manufacturing a PAO by a metallocene catalyst (hereinafter, also
referred to as an "mPAO") is preferably an alpha-olefin having 10
to 14 carbon atoms. A linear alpha-olefin is preferable in terms of
a viscosity index and low-temperature properties. Examples of the
linear alpha-olefin include 1-decene, 1-dodecene and 1-tetradecene,
among which 1-decene is particularly preferable.
[0050] A blend ratio between the metallocene compound represented
by the formula (1) or (4) and the alpha-olefin (the metallocene
compound (mmol)/the alpha-olefin (L)) is typically from 0.01 to
0.4, preferably from 0.05 to 0.3, more preferably from 0.1 to 0.2.
When the blend ratio is 0.01 or more, a sufficient catalyst
activity is obtained. When the blend ratio is 0.4 or less, the
yield of the oligomers of a trimer or a multimer suitable to the
lubricating base oil is improved and incomplete decalcification of
the catalyst is avoided.
[0051] Polymerization of the alpha-olefin is preferably performed
in the presence of hydrogen. A content of hydrogen is typically in
a range of 0.1 kPa to 50 kPa, preferably in a range of 0.5 kPa to
30 kPa, more preferably in a range of 1 kPa to 10 kPa. When the
content of hydrogen is 0.1 kPa or more, a sufficient catalyst
activity is obtained. When the content of hydrogen is 50 kPa or
less, the alpha-olefin (a starting material) can be inhibited from
being saturated, thereby improving a yield of the mPAO (a target
compound).
[0052] A method for polymerization of the alpha-olefin is subject
to no limitation. Polymerization may be performed either in the
absence of a solvent or in a solvent. When a reaction solvent is
used, examples of the reaction solvent include: an aromatic
hydrocarbon such as benzene, toluene, xylene and ethyl benzene; an
alicyclic hydrocarbon such as cyclopentane, cyclohexane and
methylcyclohexane; an aliphatic hydrocarbon such as pentane,
hexane, heptane and octane; and a halogenated hydrocarbon such as
chloroform and dichloromethane. A temperature for polymerization is
typically in a range of 0 degree C. to 100 degrees C., preferably
in a range of 20 degrees C. to 80 degrees C., more preferably in a
range of 30 degrees C. to 70 degrees C. When the temperature falls
within the range, a sufficient catalyst activity is obtained and
the yield of the oligomers of a trimer or a multimer suitable to
the lubricating base oil is improved. When the polymerization is
performed by the above method, the mPAO having 50% or more of a
selection ratio of a trimer or a multimer can be manufactured.
[0053] Depending on a purpose, the mPAO obtained by the above
method may be further processed. For instance, hydrotreatment may
be performed for improving thermal stability and oxidization
stability. Moreover, distillation may be performed for obtaining a
lubricating base oil having desired properties. A hydrotreatment
temperature is typically in a range of 50 degrees C. to 300 degrees
C., preferably in a range of 60 degrees C. to 250 degrees C., more
preferably in a range of 70 degrees C. to 200 degrees C. A hydrogen
pressure is typically in a range of 0.1 MPa to 10 MPa, preferably
in a range of 0.5 MPa to 2 MPa, more preferably in a range of 0.7
MPa to 1.5 MPa. In the hydrotreatment, a general hydrogenated
catalyst including Pd or Ni may be used. A distillation temperature
is typically in a range of 200 degrees C. to 300 degrees C.,
preferably in a range of 220 degrees C. to 280 degrees C., more
preferably in a range of 230 degrees C. to 270 degrees C. A
distillation pressure is typically in a range of 0.1 Pa to 15 Pa,
preferably in a range of 0.4 Pa to 7 Pa, more preferably in a range
of 0.6 Pa to 4 Pa.
[0054] The mPAO obtained by the above method and the mPAO after the
hydrotreatment and distillation have about one short-chain branch
per molecule (typically from 0.6 to 1.2 short-chain branches,
preferably from 0.7 to 1.1, more preferably from 0.8 to 1.0). It
should be noted that a methyl group, an ethyl group and a propyl
group are herein referred to as a short-chain branch. In addition,
the short-chain branch is primarily a methyl group. A ratio of the
methyl group is typically 80 mol % or more, preferably 85 mol % or
more, more preferably 90 mol % or more.
[0055] In the composition according to this exemplary embodiment of
the invention, the content of the component (A) is required to be
25 mass % or more of a total amount of the composition. When the
content of the component (A) is less than 25 mass %, the object of
the invention cannot be sufficiently achieved. The content of the
component (A) is preferably 30 mass % or more, more preferably 35
mass % or more in terms of a low vaporizability. However, the
content of the component (A) is preferably 80 mass % or less in
terms of solubility of additives and compatibility with seal
rubber.
Component (B)
[0056] The component (B) according to the exemplary embodiment of
the invention is a mineral oil having a viscosity index of 120 or
more. Such a mineral oil is preferably, for instance, a
hydrorefined mineral oil of Group III in the API
classification.
[0057] The component (B) blended with the component (A) provides an
appropriate lubricity to the composition and contributes to
improvement in the fuel-saving performance.
[0058] Moreover, blending the component (B) improves solubility of
an additive generally used for the internal combustion engine,
resulting in a large contribution to the fuel-saving
performance.
[0059] Accordingly, the component (B) to be blended is preferably
20 mass % or more of the total amount of the composition, more
preferably 25 mass % or more.
[0060] In the exemplary embodiment of the invention, a kinematic
viscosity at 100 degrees C. of a mixed base oil provided by
blending the above-described components (A) and (B) is preferably
4.6 mm.sup.2/s or less, more preferably 4.4 mm.sup.2/s or less.
[0061] The kinematic viscosity at 100 degrees C. of the mixed base
oil of 4.6 mm.sup.2/s or less contributes to improvement in the
fuel-saving performance. However, the kinematic viscosity at 100
degrees C. of the mixed base oil is preferably 3 mm.sup.2/s or more
in terms of vaporizability.
[0062] Although the composition contains the above-described mixed
base oil as a main component, it is preferable that the NOACK in
the composition is 10 mass % or less and the CCS viscosity at -35
degrees C. is 6000 mPas or less. When the NOACK and the CCS
viscosity at -35 degrees C. fall within the respective ranges, the
composition exhibits excellent caulking resistance and fluidity at
low temperatures (fuel-saving performance), so that the composition
is suitable to a lubricating oil for the internal combustion
engine.
[0063] The lubricating oil composition of the invention may be
blended as necessary with other additives such as a viscosity index
improver, a pour point depressant, a detergent dispersant, an
antioxidant, an antiwear agent or an extreme pressure agent, a
friction modifier, a metal deactivator, a rust inhibitor, a
surfactant or an anti-emulsifier and antifoaming agent as long as
an object of the invention is not hampered.
[0064] Examples of the viscosity index improver are
polymethacrylate, dispersed polymethacrylate, an olefin-based
copolymer (such as an ethylene-propylene copolymer), a dispersed
olefin-based copolymer, a styrene-based copolymer (such as a
styrene-diene copolymer and a styrene-isoprene copolymer). In terms
of blending effects, a content of the viscosity index improver is
preferably in a range of 0.5 mass % to 15 mass % of the total
amount of the lubricating oil composition, more preferably 1 mass %
to 10 mass %.
[0065] Examples of the pour point depressant include
polymethacrylate having a weight average molecular weight of
approximately 5000 to 50,000.
[0066] In terms of blending effects, a content of the pour point
depressant is preferably in a range of 0.1 mass % to 2 mass % of
the total amount of the lubricating oil composition, more
preferably 0.1 mass % to 1 mass %.
[0067] An ashless dispersant and a metal detergent are usable as
the detergent dispersant.
[0068] The ashless dispersant may be any ashless dispersant usable
in the lubricating oil. Examples of the ashless dispersant include
a mono-type succinimide compound represented by the following
formula (II) and a bis-type succinimide compound represented by the
following formula (III).
##STR00006##
[0069] In the formulae (II) and (III), R.sup.11, R.sup.13 and
R.sup.14 each are an alkenyl group or an alkyl group having a
number average molecular weight of 500 to 4,000, in which R.sup.13
and R.sup.14 may be the same or different. The number average
molecular weight of each of R.sup.11, R.sup.13 and R.sup.14 is
preferably in a range of 1,000 to 4,000. R.sup.12, R.sup.15 and
R.sup.16 each are an alkylene group having 2 to 5 carbon atoms, in
which R.sup.15 and R.sup.16 may be the same or different. r is an
integer of 1 to 10. s is 0 or an integer of 1 to 10.
[0070] When the number average molecular weight of each of
R.sup.11, R.sup.13 and R.sup.14 is less than 500, solubility of the
ashless detergent to the base oil is decreased. When the number
average molecular weight thereof exceeds 4,000, detergency of the
ashless detergent is decreased, so that an intended performance may
not be obtained.
[0071] r is preferably 2 to 5, more preferably 3 to 4.
[0072] When r is less than 1, detergency of the ashless detergent
is deteriorated. When r is 11 or more, solubility thereof to the
base oil is deteriorated.
[0073] In the formula (III), s is preferably 1 to 4, more
preferably 2 or 3.
[0074] The variables falling within the above range is preferable
in terms of detergency and solubility of the ashless detergent to
the base oil.
[0075] Examples of the alkenyl group include a polybutenyl group, a
polyisobutenyl group and an ethylene-propylene copolymer. Examples
of the alkyl group include a hydrogenated group of a polybutenyl
group, a polyisobutenyl group and an ethylene-propylene
copolymer.
[0076] Typical example of the suitable alkenyl group is a
polybutenyl group or a polyisobutenyl group. The polybutenyl group
is obtained by polymerizing a mixture of 1-butene and isobutene, or
high-purity isobutene. Typical example of the suitable alkyl group
is a hydrogenated group of a polybutenyl group or a polyisobutenyl
group.
[0077] The alkenyl- or alkyl-succinimide compound may be typically
produced by reacting an alkenylsuccinic anhydride, which is
obtained by reaction of a polyolefin and maleic anhydride, or an
alkylsuccinic anhydride, which is obtained by hydrogenation of the
alkenylsuccinic anhydride, with a polyamine.
[0078] The mono-type succinimide compound and the bis-type
succinimide compound can be produced by changing a reaction ratio
between the alkenylsuccinic anhydride or the alkylsuccinic
anhydride and the polyamine.
[0079] As an olefin monomer for forming the above polyolefin, one
of alpha-olefins having 2 to 8 carbon atoms may be singularly used
or at least two thereof may be used in a mixture. A mixture of
isobutene and butene-1 is suitably usable.
[0080] Examples of the polyamine include: a diamine such as
ethylenediamine, propylenediamine, butylenediamine and
pentylenediamine; a polyalkylenepolyamine such as
diethylenetriamine, triethylenetetramine, tetraethylenepentamine,
pentaethylenehexamine, di(methylethylene)triamine, dibutylenetri
amine, tributylenetetramine and pentapentylenehexamine; and a
piperadine derivative such as aminoethylpiperadine.
[0081] In addition to the above-mentioned alkenyl- or
alkyl-succinimide compound, at least one of a boron derivate
thereof and an organic acid-modified compound thereof may be
used.
[0082] The boron derivate of the alkenyl- or alkyl-succinimide
compound which is produced by a conventional method may be
employed.
[0083] For instance, the above polyolefin is reacted with maleic
anhydride to form an alkenylsuccinic anhydride. The alkenylsuccinic
anhydride is imidized with an intermediate body, which is obtained
by reaction of the above polyamine with a boron compound such as
boron oxide, boron halide, boric acid, boric anhydride, boric acid
ester or ammonium borate, thereby obtaining the boron
derivative.
[0084] A boron content of the boron derivate is subject to no
specific limitation, but is preferably in a range of 0.05 mass % to
5 mass %, more preferably in a range of 0.1 mass % to 3 mass %.
[0085] A content of the mono-type succinimide compound represented
by the formula (II) or the bis-type succinimide compound
represented by the formula (III) is preferably in a range of 0.5
mass % to 15 mass % of the total amount of the lubricating oil
composition, more preferably 1 mass % to 10 mass %.
[0086] At the content of less than 0.5 mass %, the mono-type
succinimide compound or the bis-type succinimide compound are less
likely to exhibit the advantages. Even when the content exceeds 15
mass %, advantages comparable to the content are not obtained.
[0087] As long as the succinimide compounds are contained at the
aforementioned content, one of the succinimide compounds may be
singularly used or at least two thereof may be used in
combination.
[0088] The metal-based detergent may be any alkyl earth metal-based
detergent usable in the lubricating oil. For example, any one of
alkaline earth metal sulfonate, alkaline earth metal phenate and
alkaline earth metal salicylate and a mixture of at least two
selected therefrom are usable.
[0089] Examples of the alkaline earth metal sulfonate include an
alkaline earth metal salt of alkyl aromatic sulfonic acid obtained
by sulfonating an alkyl aromatic compound having a molecular weight
of 300 to 1500 (preferably 400 to 700). The alkaline earth metal
salt is exemplified by magnesium salt and/or calcium salt.
Particularly, calcium salt is preferably used.
[0090] Examples of the alkaline earth metal phenate include an
alkaline earth metal salt of alkylphenol, alkylphenol sulfide and a
Mannich reaction product of alkylphenol. The alkaline earth metal
salt is exemplified by magnesium salt and/or calcium salt, among
which calcium salt is preferably used.
[0091] Examples of the alkaline earth metal salicylate include an
alkaline earth metal salt of alkyl salicylic acid, which is
exemplified by magnesium salt and/or calcium salt, among which
calcium salt is preferably used.
[0092] The alkyl group for forming the alkaline earth metal
detergent preferably has 4 to 30 carbon atoms. The alkyl group is
more preferably a linear or branched alkyl group having 6 to 18
carbon atoms, in which 6 to 18 carbon atoms may be in a linear
chain or in a branched chain.
[0093] The alkyl group may be a primary alkyl group, a secondary
alkyl group or a tertiary alkyl group.
[0094] In addition, the alkaline earth metal sulfonate, alkaline
earth metal phenate and alkaline earth metal salicylate may be
neutral alkaline earth metal sulfonate, neutral alkaline earth
metal phenate and neutral alkaline earth metal salicylate obtained
by:
[0095] directly reacting the above-described alkyl aromatic
sulfonic acid, alkylphenol, alkylphenol sulfide, a Mannich reaction
product of alkylphenol, alkyl salicylic acid or the like with
alkaline earth metal base exemplified by an oxide or a hydroxide of
alkaline earth metal such as magnesium and/or calcium; or
converting the above-described substance into alkali metal salt
such as sodium salt or potassium salt and subsequently substituting
the alkali metal salt with alkaline earth metal salt.
Alternatively, the alkaline earth metal sulfonate, alkaline earth
metal phenate and alkaline earth metal salicylate may be: basic
alkaline earth metal sulfonate, basic alkaline earth metal phenate
and basic alkaline earth metal salicylate obtained by heating
neutral alkaline earth metal sulfonate, neutral alkaline earth
metal phenate and neutral alkaline earth metal salicylate with
excess alkaline earth metal salt or alkaline earth metal base under
the presence of water; or overbased alkaline earth metal sulfonate,
overbased alkaline earth metal phenate and overbased alkaline earth
metal salicylate obtained by reacting neutral alkaline earth metal
sulfonate, neutral alkaline earth metal phenate and neutral
alkaline earth metal salicylate with carbonate or borate of
alkaline earth metal under the presence of carbon dioxide gas.
[0096] The metal detergent may be the neutral salt, the basic salt,
the overbased salt or a mixture thereof. Particularly, a mixture of
at least one of the overbased salicylate, the overbased phenate and
the overbased sulfonate with the neutral sulfonate is preferable in
terms of detergency and wear resistance.
[0097] A total base number of the metal detergent is preferably in
a range of 10 mgKOH/g to 500 mgKOH/g, more preferably in a range of
15 mgKOH/g to 450 mgKOH/g.
[0098] The total base number herein means the total base number
measured by potentiometer titration (base number perchloric acid
method) based on the Item 7 of "Petroleum Products and Lubricating
Oil--Examining Method of Neutralization Value" of JIS K2501.
[0099] The metal detergent, of which metal ratio is subject to no
particular limitation, is typically one of or a mixture of at least
two of detergents having the metal ratio of 20 or less. In terms of
excellent oxidation stability, base number maintainability and
high-temperature detergency, the metal detergent particularly
preferably contains as the main component a metal detergent that
has the metal ratio of 3 or less, more preferably 1.5 or less,
particularly preferably 1.2 or less.
[0100] The metal ratio herein is represented by (valence of metal
element in the metal detergent).times.(content of metal element
(mol %))/(content of soap base (mol %)), and the metal element
means calcium, magnesium and the like while the soap base means a
sulfonate group, phenol group, salicylic acid group and the
like.
[0101] The metal detergent, which is commercially available in a
form of a dilution with light lubricant base oil and the like,
preferably has a metal content of 1 to 20 mass %, more preferably 2
to 16 mass %. A content of the metal detergent is preferably in a
range of 0.01 mass % to 20 mass % of the total amount of the
lubricating oil composition, more preferably 0.1 mass % to 10 mass
%.
[0102] At the content of less than 0.01 mass %, the metal detergent
are less likely to exhibit the advantages. Even when the content
exceeds 20 mass %, advantages comparable to the added content are
not obtained.
[0103] As long as the metal detergent is contained at the
aforementioned content, one of the metal detergents may be
singularly used or at least two thereof may be used in
combination.
[0104] The antioxidant may be exemplified by a phenolic
antioxidant, an amine antioxidant, a molybdenum-amine complex-based
antioxidant and a sulfuric antioxidant.
[0105] Examples of the phenolic antioxidant include:
4,4'-methylenebis(2,6-di-t-butylphenol);
4,4'-bis(2,6-di-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);
2,2'-methylenebis(4-methyl-6-t-butylphenol);
4,4'-butylidenebis(3-methyl-6-t-butylphenol);
4,4'-isopropylidenebis(2,6-di-t-butylphenol);
2,2'-methylenebis(4-methyl-6-nonylphenol);
2,2'-isobutylidenebis(4,6-dimethylphenol);
2,2'-methylenebis(4-methyl-6-cyclohexylphenol);
2,6-di-t-butyl-4-methylphenol; 2,6-di-t-butyl-4-ethylphenol;
2,4-dimethyl-6-t-butylphenol; 2,6-di-t-amyl-p-cresol;
2,6-di-t-butyl-4-(N,N'-dimethylaminomethylphenol);
4,4'-thiobis(2-methyl-6-t-butylphenol);
4,4'-thiobis(3-methyl-6-t-butylphenol);
2,2'-thiobis(4-methyl-6-t-butylphenol); bis(3 -methyl-4-hydroxy-5
-t-butylbenzyl)sulfide; bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide;
n-octyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate;
n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate; and
2,2'-thio[diethyl-bis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].
[0106] A bisphenolic antioxidant and an ester group-containing
phenolic antioxidant are particularly preferable among the
above.
[0107] Examples of the amine antioxidant include an antioxidant
based on monoalkyldiphenylamine such as monooctyldiphenylamine and
monononyldiphenylamine; dialkyl diphenylamine such as
4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine,
4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine,
4,4'-dioctyldiphenylamine and 4,4'-dinonyldiphenylamine;
polyalkyldiphenylamine such as tetrabutyldiphenylamine,
tetrahexyldiphenylamine, tetraoctyldiphenylamine and
tetranonyldiphenylamine; and naphthylamine, specifically
alpha-naphthylamine, phenyl-alpha-naphthylamine and
alkyl-substituted phenyl-alpha-naphthylamine such as
butylphenyl-alpha-naphthylamine, pentylphenyl-alpha-naphthylamine,
hexylphenyl-alpha-naphthylamine, heptylphenyl-alpha-naphthylamine,
octylphenyl-alpha-naphthylamine and
nonylphenyl-alpha-naphthylamine.
[0108] A dialkyl diphenylamine antioxidant and a naphthylamine
antioxidant are preferable among the above.
[0109] As the molybdenum-amine complex-based antioxidant, a
hexahydric molybdenum compound, an example of which is a reaction
product obtained by reacting molybdenum trioxide and/or molybdenum
acid with an amine compound, may be used. The reaction product may
be, for example, a compound obtained by the manufacturing method
disclosed in JP-A-2003-252887.
[0110] The anime compound to be reacted with the hexahydric
molybdenum compound is subject to no particular limitation, and
examples thereof are monoamine, diamine, polyamine and
alkanolamine.
[0111] Specific examples of the amine compound are: alkyl amine
having an alkyl group of 1 to 30 carbon atoms (the alkyl group may
contain a linear chain or a branched chain), exemplified by
methylamine, ethylamine, dimethylamine, diethylamine,
methylethylamine, methylpropylamine and the like; alkenyl amine
having an alkenyl group of 2 to 30 carbon atoms (the alkenyl group
may contain a linear chain or a branched chain), exemplified by
ethenylamine, propenylamine, butenylamine, octenylamine and
oleylamine; alkanol amine having an alkanol group of 1 to 30 carbon
atoms (the alkanol group may contain a linear chain or a branched
chain), exemplified by methanolamine, ethanolamine,
methanolethanolamine and methanolpropanolamine; alkylenediamine
having an alkylene group of 1 to 30 carbon atoms, exemplified by
methylenediamine, ethylenediamine, propylenediamine and
butylenediamine; polyamine such as diethylenetriamine,
triethylenetetramine, tetraethylenepentamine and
pentaethylenehexamine; a heterocyclic compound obtained by reacting
monoamine, diamine and polyamine with a compound having an alkyl or
alkenyl group of 8 to 20 carbon atoms or imidazoline, monoamine,
diamine and polyamine being exemplified by undecyldiethylamine,
undecyldiethanolamine, dodecyldipropanolamine, oleyldiethanolamine,
oleylpropylenediamine and stearyltetraethylenepentamine; an
alkylene-oxide adduct of the compounds; and a mixture thereof.
[0112] In addition, sulfur-containing molybdenum complexes of
succinimide as disclosed in JP-B-03-22438 and JP-A-2004-2866 may be
used.
[0113] Examples of the sulfuric antioxidant include phenothiazine,
pentaerythritol-tetrakis-(3-laurylthiopropionate), didodecyl
sulfide, dioctadecyl sulfide, didodecyl thiodipropionate,
dioctadecyl thiodipropionate, dimyristyl thiodipropionate,
dodecyloctadecyl thiodipropionate and 2-mercaptobenzoimidazole.
[0114] A content of the antioxidant is preferably in a range of 0.1
mass % to 5 mass % of the total amount of the lubricating oil
composition, more preferably 0.1 mass % to 3 mass %.
[0115] Examples of the antiwear agent or the extreme pressure agent
include: sulfur-containing compounds such as zinc dithiophosphate,
zinc phosphate, zinc dithiocarbamate, disulfides, sulfurized
olefins, sulfurized fats and oils, sulfurized esters,
thiocarbonates, thiocarbamates and polysulfides;
phosphorus-containing compounds such as phosphite esters, phosphate
esters, phosphonate esters and amine salts or metal salts thereof;
and a sulfur-and-phosphorus-containing antiwear agent such as
thiophosphite esters, thiophosphate esters, thiophosphonate esters
and amine salts or metal salts thereof.
[0116] A content of the antiwear agent or the extreme pressure
agent is preferably in the range from 0.1 mass % to 20 mass % of
the total amount of the composition.
[0117] When the antiwear agent or the extreme pressure agent is a
zinc-containing compound, the antiwear agent or the extreme
pressure agent is preferably 600 mass ppm or less in terms of zinc
(of the total amount of the composition), more preferably 500 mass
ppm or less, further preferably 400 mass ppm or less. When the
antiwear agent or the extreme pressure agent is a
phosphorus-containing compound, the antiwear agent or the extreme
pressure agent is preferably 500 mass ppm or less in terms of
phosphorus (of the total amount of the composition), more
preferably 400 mass ppm or less, further preferably 300 mass ppm or
less. When the zinc content is 600 mass ppm or less or the
phosphorus content is 500 mass ppm or less, the composition does
not cause a basic compound to be consumed to extremely shorten an
oil replacement interval.
[0118] As the friction modifier, any compounds generally usable as
the friction modifier for lubricating oil may be used. The friction
modifier is exemplified by an ashless friction modifier such as an
aliphatic ester, an aliphatic amide, a fatty acid, aliphatic
alcohol, an aliphatic amine and an aliphatic ether that have at
least one alkyl or alkenyl group having 6 to 30 carbon atoms in the
molecule.
[0119] A content of the friction modifier is preferably in a range
of 0.01 mass % to 2 mass % of the total amount of the lubricating
oil composition, more preferably 0.01 mass % to 1 mass %.
[0120] Examples of the metal deactivator include
benzotriazole-based compounds, tolyltriazole-based compounds,
thiadiazole-based compounds, imidazole-based compounds and the
like.
[0121] A content of the metal deactivator is preferably in a range
of 0.01 mass % to 3 mass % of the total amount of the lubricating
oil composition, more preferably 0.01 mass % to 1 mass %.
[0122] Examples of the rust inhibitor include petroleum sulfonate,
alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl
succinic ester, multivalent alcohol ester and the like.
[0123] In terms of blending effects, a content of the rust
inhibitor is preferably in a range of 0.01 mass % to 1 mass % of
the total amount of the lubricating oil composition, more
preferably 0.05 mass % to 0.5 mass %.
[0124] Examples of the surfactant or the anti-emulsifier include
nonionic surfactants based on polyalkylene glycol such as
polyoxyethylenealkylether, polyoxyethylenealkylphenylether and
polyoxyethylenealkylnaphthylether.
[0125] A content of the metal deactivator or the anti-emulsifier is
preferably in a range of 0.01 mass % to 3 mass % of the total
amount of the lubricating oil composition, more preferably 0.01
mass % to 1 mass %.
[0126] Examples of the antifoaming agent include silicone oil,
fluorosilicone oil and fluoroalkylether. In terms of a balance
between antifoaming effects and economics, a content of the
antifoaming agent is preferably in a range of 0.005 mass % to 0.5
mass % of the total amount of the compound, more preferably in a
range of 0.01 mass % to 0.2 mass %.
EXAMPLES
[0127] Examples of the invention will be described below in detail.
However, it should be noted that the scope of the invention is by
no means limited by the examples.
[0128] Properties and various performances (e.g., thin-film
vaporizability and motoring performance) of a lubricating oil
composition (sample oil) in each Example were measured by the
following method.
(1) Kinematic Viscosity at 100 degrees C.
[0129] The kinematic viscosity at 100 degrees C. was measured
according to a method described in JIS K2283. The kinematic
viscosity at 100 degrees C. of the mixed base oil was also
measured.
(2) NOACK
[0130] Evaporation loss was measured according to ASTM D
5800-08.
(3) CCS Viscosity (Cold-Cranking Simulator Viscosity)
[0131] A shear viscosity at -35 degrees was measured according to
JIS K2010.
(4) Viscosity Index:
[0132] The viscosity index was calculated according to a method
described in JIS K2283.
(5) Thin-Film Vaporizability
[0133] 0.5 g of the sample oil was dropped into an aluminum
container having a 35-mm diameter. The aluminum container was
placed in a hot-air constant-temperature bath and left at 175
degrees C. for 24 hours. Subsequently, a residual mass of the
sample oil was measured to calculate an evaporation rate.
(6) Motoring Performance (Fuel-Saving Performance)
[0134] The following motoring test was performed.
[0135] Using a 1500-cc in-line four cylinder DOHC engine, a driving
torque was measured in a combination of an oil temperature (60
degrees C., 80 degrees C., 100 degrees C.) and a rotation speed
(1500 rpm, 2000 rpm, 2500 rpm). An average of all nine data was
defined as a driving torque value of the sample oil. Using
commercially available ACEA C2 5W-30 (a kinematic viscosity at 100
degrees C.: 10.29 mm.sup.2/s, NOACK: 14.3 mass %, CCS viscosity
(-35 degrees C.): 7700 mPas, a viscosity index: 172) as a reference
oil, the driving torque value of the sample oil relative to a
driving torque value of the reference oil was defined as a torque
improvement rate. A motoring performance of the sample oil was
evaluated based on the following scale.
[0136] A: more excellent than the reference oil (the torque
improvement rate relative to the reference oil: 1.5% or more)
[0137] B: more excellent than the reference oil (the torque
improvement rate relative to the reference oil: less than 1.5%)
[0138] C: inferior to the reference oil
[0139] A later-described mPAO among the base oil was manufactured
by the following method.
Manufacturing Example: Manufacturing of Hydrogenated 1-Decene
Oligomer (Trimer)
(a) Oligomerization of Decene
[0140] Under a flow of inert gas, 4 liter (21.4 mol) of a decene
monomer (manufactured by Idemitsu Kosan Co., Ltd: LINEALENE 10) was
put into a three-necked flask having an inner volume of 5 liter and
biscyclopentadienyl zirconium dichloride (a complex mass: 1168 mg
(4 mmol)) that was dissolved in toluene and methyl alumoxane (40
mmol in terms of Al) that was also dissolved in toluene were
further added thereto. The obtained mixture was stirred for 20
hours while being kept at 40 degrees C. Subsequently, 20 ml of
methanol was added to the mixture to stop the oligomerization
reaction. Next, the reaction mixture was taken out of an autoclave
and 4 liter of an aqueous sodium hydroxide solution (5 mol/liter)
was added to the reaction mixture. The obtained mixture was
forcibly stirred for 4 hours at the room temperature and was
separated. An organic phase (an upper phase) was taken out.
Unreacted decene and a decene isomer of a side reaction product
were removed from the organic phase by stripping.
(b) Hydrogenation of Decene Oligomer
[0141] Under a flow of nitrogen gas, 3 liter of the decene oligomer
manufactured in the step (a) was put into an autoclave having an
inner volume of 5 liter and cobalt trisacetylacetonato (a catalyst
weight: 3.0 g) that was dissolved in toluene and triisobutyl
aluminium (30 mmol) that was diluted in toluene were added thereto.
After addition, the obtained mixture was substituted twice by
hydrogen and heated to be kept at a reaction temperature of 80
degrees C. and at 0.9 MPa of a hydrogen pressure. Hydrogenation
immediately proceeds along with heat generation. When 4 hours
elapsed since the reaction was started, the temperature of the
mixture was decreased to stop the reaction.
[0142] Subsequently, after the autoclave was depressurized and
contents in the autoclave were taken out, a simple distillation was
performed on the obtained reaction product, so that a fraction
(hydrogenated trimer of 1-decene) under pressure of 530 Pa was
separated at a distillation temperature in a range of 240 degrees
C. to 270 degrees C.
Examples 1 to 4 and Comparatives 1 to 4
[0143] Lubricating oil compositions (the sample oils) having
compositions as shown in Table 1 were prepared using the following
PAOs, mineral oils and additives. Properties and various
performances of the sample oils are shown in Table 1. [0144] PAO-1:
Durasyn 125 manufactured by INEOS Group Limited (a kinematic
viscosity at 100 degrees C.: 5.196 mm.sup.2/s, NOACK: 5.5 mass %, a
CCS viscosity (-35 degrees C.): 2490 mPas, a viscosity index: 143)
[0145] PAO-2: Durasyn 145 manufactured by INEOS Group Limited (a
kinematic viscosity at 100 degrees C.: 5.194 mm.sup.2/s, NOACK: 5.1
mass %, a CCS viscosity (-35 degrees C.): 2570 mPas, a viscosity
index: 145) [0146] PAO-3: the mPAO obtained in the above
Manufacturing Example (a kinematic viscosity at 100 degrees C.:
3.458 mm.sup.2/s, NOACK: 11.1 mass %, a CCS viscosity (-35 degrees
C.): 800 mPas, a viscosity index: 127) [0147] PAO-4: Durasyn 164
manufactured by INEOS Group Limited (a kinematic viscosity at 100
degrees C.: 3.893 mm.sup.2/s, NOACK: 14.0 mass %, a CCS viscosity
(-35 degrees C.): 1330 mPas, a viscosity index: 120) [0148] PAO-5:
Durasyn 166 manufactured by 1NEOS Group Limited (a kinematic
viscosity at 100 degrees C.: 5.824 mm.sup.2/s, NOACK: 6.0 mass %, a
CCS viscosity (-35 degrees C.): 3950 mPas, a viscosity index: 178)
[0149] Mineral Oil-1: hydrorefined mineral oil (a kinematic
viscosity at 100 degrees C.: 4.121 mm.sup.2/s, NOACK: 14.1 mass %,
a CCS viscosity (-35 degrees C.): 1870 mPas, a viscosity index:
122) [0150] Mineral Oil-2: hydrorefined mineral oil (a kinematic
viscosity at 100 degrees C.: 6.483 mm.sup.2/s, NOACK: 7.5 mass %, a
CCS viscosity (-35 degrees C.): 10100 mPas, a viscosity index: 121)
[0151] Additive Package: infineum P6000 manufactured by Infineum
[0152] Viscosity Index Improver: polymethacrylate (a mass average
molecular weight of 230,000, a resin portion of 45 mass % (The
blended content shown in Table 1 is a total amount of the viscosity
index improver including the resin portion.)) [0153] Pour Point
Depressant: polyalkylmethacrylate (a mass average molecular weight
of 6,000)
TABLE-US-00001 [0153] TABLE 1 Exam- Exam- Exam- Exam- Compar-
Compar- Compar- Compar- ple 1 ple 2 ple 3 ple 4 ative 1 ative 2
ative 3 ative 4 Blend Base PAO-1: Component (A) 30.0 -- -- -- -- --
-- -- Compo- Oil PAO-2: Component (A) -- 30.0 -- 20.0 -- -- -- --
sition PAO-3: Component (A) -- -- 30.0 10.0 -- -- -- -- (mass PAO-4
-- -- -- -- -- -- -- 27.7 %) PAO-5 -- -- -- -- 30.0 -- -- 8.0
Mineral Oil-1: Component (B) 50.7 50.7 20.7 50.7 50.7 80.7 54.7
45.0 Mineral Oil-2: Component (B) -- -- 30.0 -- -- -- 26.0 -- Addi-
Additive Package 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 tive
Visocity Index Improver 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 Pour Point
Depressant 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Kinematic Vicosity at
100.degree. C. of 4.482 4.481 4.502 4.256 4.661 4.121 4.719 4.171
Mixed Base Oil (mm.sup.2/s) Properties NOACK (mass %) 9.3 9.2 9.1
9.8 9.5 11.9 10.2 11.3 of Sample Oil CCS Viscosity (-35.degree. C.,
mPa s) 5300 5300 5850 4650 6100 5100 8000 4550 Evalua- Evaporation
rate (mass %) in 0.25 0.25 0.25 0.27 0.26 0.46 0.30 0.40 tion
thin-film vaporizability test Results Motoring test results B B B A
C A C A
Evaluation Results
[0154] Since the sample oils of Examples 1 to 4, which are
configured to match the composition of the invention, contain the
PAO having specific properties and the mineral oil having specific
properties as shown in Table 1, it can be understood that the
sample oils exhibit a low vaporizability and an excellent caulking
resistance. Moreover, due to a low viscosity, the sample oils
exhibit an excellent fuel-saving performance. The excellent
fuel-saving performance is also apparent from the results of the
motoring test. Accordingly, the composition of the invention is
suitable not only to a typical internal combustion engine but also
a gasoline engine and a diesel engine which are provided with a
turbo mechanism.
[0155] In contrast, since none of the sample oils of Comparatives
contain a predetermined PAO, a low vaporizability (caulking
resistance) and fuel-saving performance cannot be simultaneously
satisfied.
* * * * *