U.S. patent application number 16/607835 was filed with the patent office on 2020-06-18 for lubricating oil composition for internal combustion engine.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Akimitsu FUJIWARA, Kiyoshi HANYUDA, Izumi KOBAYASHI, Taku SAITO.
Application Number | 20200190422 16/607835 |
Document ID | / |
Family ID | 62200408 |
Filed Date | 2020-06-18 |
United States Patent
Application |
20200190422 |
Kind Code |
A1 |
HANYUDA; Kiyoshi ; et
al. |
June 18, 2020 |
LUBRICATING OIL COMPOSITION FOR INTERNAL COMBUSTION ENGINE
Abstract
A lubricating oil composition comprising a GTL (Gas to-Liquid)
base oil synthesized by the Fischer-Tropsch process and a viscosity
index improver, wherein the content of the viscosity index improver
is 0.1 to 20 mass %, and at least HTHSV 50.degree. C./HTHSV
150.degree. C. is 6.50 or less and KV 50.degree. C./HTHSV
150.degree. C. is 8.00 or less.
Inventors: |
HANYUDA; Kiyoshi; (Aikou,
JP) ; FUJIWARA; Akimitsu; (Minato-ku, JP) ;
KOBAYASHI; Izumi; (Tokyo, JP) ; SAITO; Taku;
(Tokyo, US) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
HOUSTON |
TX |
US |
|
|
Family ID: |
62200408 |
Appl. No.: |
16/607835 |
Filed: |
April 18, 2018 |
PCT Filed: |
April 18, 2018 |
PCT NO: |
PCT/EP2018/059952 |
371 Date: |
October 24, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2229/041 20130101;
C10N 2030/10 20130101; C10M 169/00 20130101; C10M 2203/10 20130101;
C10M 2215/30 20130101; C10N 2030/68 20200501; C10N 2030/02
20130101; C10M 2207/026 20130101; C10M 171/02 20130101; C10N
2040/25 20130101; C10N 2030/54 20200501; C10M 145/14 20130101; C10M
2215/064 20130101; C10M 143/00 20130101; C10M 2205/173 20130101;
C10M 2223/045 20130101; C10M 169/041 20130101; C10M 139/06
20130101; C10N 2030/12 20130101; C10M 2215/28 20130101; C10M
2290/02 20130101; C10N 2010/04 20130101; C10M 2219/068 20130101;
C10M 2203/1025 20130101; C10M 169/04 20130101; C10M 2205/02
20130101; C10M 101/02 20130101; C10M 2209/084 20130101; C10M
2227/08 20130101; C10M 141/12 20130101; C10M 2205/00 20130101; C10N
2030/74 20200501; C10N 2020/02 20130101; C10N 2030/04 20130101;
C10M 2219/068 20130101; C10N 2010/12 20130101; C10M 2229/041
20130101; C10N 2020/04 20130101; C10M 2223/045 20130101; C10N
2010/04 20130101; C10M 2215/28 20130101; C10N 2060/14 20130101 |
International
Class: |
C10M 141/12 20060101
C10M141/12; C10M 169/04 20060101 C10M169/04; C10M 101/02 20060101
C10M101/02; C10M 143/00 20060101 C10M143/00; C10M 145/14 20060101
C10M145/14; C10M 139/06 20060101 C10M139/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2017 |
JP |
2017-086314 |
Claims
1. A lubricating oil composition for an internal combustion engine,
comprising a GTL (Gas To Liquid) base oil synthesized by the
Fischer-Tropsch method and a viscosity index improver, wherein the
content of the viscosity index improver relative to the total
amount of lubricating oil composition is 0.1 to 20 mass % by resin
amount, and the lubricating oil composition satisfies the following
(a) to (e): (a) high temperature high shear viscosity (HTHSV (ASTM
D4683 or ASTM D5481)) at 150.degree. C., 106 s-1 is 1.0 mPas or
more; (b) kinematic viscosity (KV (JIS K2283)) at 100.degree. C. is
3.0 mm2/s or more; (c) HTHSV50.degree. C./HTHSV 150.degree. C. is
6.50 or less; (d) KV50.degree. C./HTHSV150.degree. C. is 8.00 or
less; and (e) NOACK evaporation amount (JPI-5S-41) is 15 mass % or
less.
2. The lubricating oil composition of claim 1, comprising one or
more base oils having KV100.degree. C. of 1 to 8 mm2/s, a viscosity
index of 110 or more, % CA by ASTM D3238 of 5 or less, and % CP by
ASTM D3238 of 60 or more, wherein: the content of the base oils
relative to the total amount of the lubricating oil composition is
50 mass % or less, and a fraction of an entire base oil at
380.degree. C. or less in gas chromatography distillation by ASTM
D2887 is 10 mass % or less.
3. The lubricating oil composition of claim 1, wherein at least one
of (f) through (i), below, is satisfied: (f) the lubricating oil
composition includes a metal-including detergent having at least
one selection from Ca and Mg, and [Ca]+[Mg]=0.10 to 0.25, where
[Ca], [Mg] are respectively concentrations (mass %) of calcium and
magnesium in the lubricating oil composition; (g) the lubricating
oil composition contains a succinimide ashless dispersant and/or a
boron modified succinimide ashless dispersant, and the dispersants
are 0.01 to 0.20 mass % (based on a total amount of the lubricating
oil composition) in terms of nitrogen concentration; (h) the
lubricating oil composition includes ZnDTP of 0.03 to 0.09 mass %
(based on the total amount of the lubricating oil composition) in
terms of phosphorus concentration; and/or (i) the lubricating oil
composition includes an organic molybdenum compound of 0.01 to 0.12
mass % (based on the total amount of the lubricating oil
composition) in terms of Mo concentration.
4. The lubricating oil composition of claim 1, including at least
one selection from a corrosion inhibitor, a phenol-based
antioxidant, an amine-based antioxidant, and a sulfur-containing
additive.
5. The lubricating oil composition of claim 1, wherein the
viscosity index improver is a comb polymer, preferably wherein the
comb polymer comprises (1) repeating units derived from
polyolefin-based macro monomers, and (2) repeating units derived
from low-molecular-weight monomers selected from a group comprising
styrene monomers having between 8 and 17 carbon atoms,
alkyl(meth)acrylates having between 1 and 10 carbon atoms in an
alcohol base, vinyl esters having between 1 and 11 carbon atoms in
an acyl, vinyl ethers having between 1 and 10 carbon atoms in an
alcohol base, (di)alkyl fumarate having between 1 and 10 carbon
atoms in an alcohol base, (di)alkyl maleates having between 1 and
10 carbon atoms in an alcohol base, and mixtures of these monomers,
included in the main chain.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a lubricating oil
composition for an internal combustion engine (hereinafter also
referred to as an engine) that is excellent in fuel economy in a
temperature range of practical use.
BACKGROUND OF THE INVENTION
[0002] Regulations regarding environmental conservation are being
strengthened on a global scale. Limitations on fuel consumption and
limitations on exhaust gases, particularly when it comes to
automobiles, are becoming increasingly severe, based on concerns
regarding environmental problems, such as global warming, depletion
of petroleum resources, as a strategy for preserving resources. In
particular when it comes to the need to reduce fuel consumption of
automobiles, improvements are being made to engines in order to
reduce the weight of automobiles and to improve energy efficiency,
and improvements are being made to various types of structural
elements in automobiles, such as improving the efficiency of
transmission of the driving forces.
[0003] In engine oils there is the need to reduce frictional loss
in the engine in order to contribute to reduced fuel consumption.
This friction loss is primarily due to viscous drag under the
conditions of fluid lubrication, caused by the lubricating oil that
is used, and friction between metals in the sliding portions under
mixed lubrication or boundary lubrication conditions, and thus, in
order to achieve a superior effect in fuel economy, it is necessary
to reduce the viscosity below that which is conventional for the
viscosity of lubricating oil, to reduce the viscous drag.
Preventing variability in viscosity due to changes in temperature,
using a base oil with a lower viscosity, or a viscosity index
improving agent, such as a comb polymer, or the like, is effective
in reducing the viscosity of a lubricating oil (as described in,
for example, Japanese Patent Application No. 2015-520285 and
Japanese Patent No. 5502730).
[0004] In relation to this, in recent years, in particular, as a
typical example of a strategy to reduce fuel consumption of
passenger vehicles, there is a function to stop idling that works
when a passenger vehicle comes to a halt, such as at a signal, and
thus engines are stopped frequently when traveling on city streets.
Because of this, when operating over short distances, such as when
on a shopping trip, engine operation is stopped without the
temperature of the internal combustion engine lubricating oil
warming up adequately. The same is true for a plug-in hybrid
vehicle (PHV), where the engine is turned ON/OFF as necessary,
producing a state wherein there is a tendency for the engine to not
warm up adequately with short-distance commutes or shopping
trips.
[0005] On the other hand, it is known that reducing the viscosity
of the engine oil leads to an increased risk of wear and
metal-on-metal friction due to failure of the oil film when at high
temperatures, and thus, to prevent this, the SAE J300 viscosity
standard defines lower limits for the 150.degree. C. shear
viscosity (hereinafter termed "HTHSV150") and the 100.degree. C.
kinematic viscosity (hereinafter termed "KV100") for each viscosity
grade. Because of this, when attempting to reduce the viscosity of
engine oils, the lower limit values for HTHSV150 and KV100 become
barriers, and no specific methods have been proposed for achieving
further fuel economy at given viscosity grades, even for PHVs and
for vehicles with functions for stopping idling.
[0006] In light of the above, the present invention is to achieve a
lubricating oil composition for an internal combustion engine that
is able to further improve fuel economy under general driving
conditions, including a state wherein the engine itself is not
running, while still maintaining HTHSV150 and KV100, stipulated in
SAE J300, at no less than the lower limit value.
SUMMARY OF THE INVENTION
[0007] The present inventors, based on the issues set forth above,
used a new approach to be the first to discover that it is possible
to improve fuel economy substantially through having both the shear
viscosity and kinematic viscosity at 50.degree. C. be within a
specific range (a specific range that corresponds to temperature
characteristics in a higher temperature domain), particularly in an
idling stopping vehicle and a PHV wherein the engine is stopped and
started repeatedly, through extensive research regarding
characteristics in a variety of temperature ranges that are not
normally examined. The result was achievement of the present
invention, which is able to improve the fuel economy of an internal
combustion engine lubricating oil composition while maintaining the
HTHSV 150.degree. C. and KV 100.degree. C. at no less than the
lower limit values stipulated in SAE J300.
[0008] The present invention, specifically, provides (1) to (5) as
follows:
(1): A lubricating oil composition for an internal combustion
engine, comprising a GTL (Gas To Liquid) base oil synthesized by
the Fischer-Tropsch method and a viscosity index improver, wherein
the content of the viscosity index improver relative to the total
amount of lubricating oil composition is 0.1 to 20 mass % by resin
amount, and the lubricating oil composition satisfies the following
(A) to (E): (A) high temperature high shear viscosity (HTHSV (ASTM
D4683 or ASTM D5481)) at 150.degree. C., 106 s-1 is 1.0 mPas or
more; (B) kinematic viscosity (KV (JIS K2283)) at 100.degree. C. is
3.0 mm2/s or more; (C) HTHSV50.degree. C./HTHSV 150.degree. C. is
6.50 or less; (D) KV50.degree. C./HTHSV150.degree. C. is 8.00 or
less; and (E) NOACK evaporation amount (JPI-5S-41) is 15 mass % or
less. (2): The lubricating oil composition of (1), including: one
or more base oils having KV100.degree. C. of 1 to 8 mm2/s, a
viscosity index of 110 or more, % CA by ASTM D3238 of 5 or less,
and % CP by ASTM D3238 of 60 or more, wherein: the content of the
base oils relative to the total amount of the lubricating oil
composition is 50 mass % or less, and a fraction of an entire base
oil at 380.degree. C. or less in gas chromatography distillation by
ASTM D2887 is 10 mass % or less. (3): The lubricating oil
composition of (1) or (2), wherein: at least one of (F) through
(I), below, is satisfied: (F) the lubricating oil composition
includes a metal-including detergent having at least one selection
from Ca and Mg, and [Ca]+[Mg]=0.10 to 0.25, where [Ca], [Mg] are
respectively concentrations (mass %) of calcium and magnesium in
the lubricating oil composition; (G) the lubricating oil
composition contains a succinimide ashless dispersant and/or a
boron modified succinimide ashless dispersant, and the dispersants
are 0.01 to 0.20 mass % (based on a total amount of the lubricating
oil composition) in terms of nitrogen concentration; (H) the
lubricating oil composition includes ZnDTP of 0.03 to 0.09 mass %
(based on the total amount of the lubricating oil composition) in
terms of phosphorus concentration; and (I) the lubricating oil
composition includes an organic molybdenum compound of 0.01 to 0.12
mass % (based on the total amount of the lubricating oil
composition) in terms of Mo concentration. (4): The lubricating oil
composition of any of (1) to (3), including at least one selection
from a corrosion inhibitor, a phenol-based antioxidant, an
amine-based antioxidant, and a sulfur-containing additive. (5): The
lubricating oil composition of any of (1) to (4), wherein the
viscosity index improver is a comb polymer, preferably wherein the
comb polymer comprises (1) repeating units derived from
polyolefin-based macro monomers, and (2) repeating units derived
from low-molecular-weight monomers selected from a group comprising
styrene monomers having between 8 and 17 carbon atoms,
alkyl(meth)acrylates having between 1 and 10 carbon atoms in an
alcohol base, vinyl esters having between 1 and 11 carbon atoms in
an acyl, vinyl ethers having between 1 and 10 carbon atoms in an
alcohol base, (di)alkyl fumarate having between 1 and 10 carbon
atoms in an alcohol base, (di)alkyl maleates having between 1 and
10 carbon atoms in an alcohol base, and mixtures of these monomers,
included in the main chain.
[0009] The compositions of the present invention are particularly
well-suited for PHVs and/or stop-idle vehicles.
[0010] The present invention provides an internal combustion engine
lubricating oil composition able to improve fuel economy while
maintaining the HTHSV 150 and KV 100 at no less than the lower
limit values stipulated in SAE J300.
[0011] In the present invention, an internal combustion engine
lubricating oil composition satisfies the 150.degree. C. 106 s-1
high-temperature/high-shear viscosity {(ASTM D4683 or ASTM D5481),
hereinafter termed "HTHSV"} is no less than 1.0 MPA-s, and the
100.degree. C. kinematic velocity {(JIS K2283), hereinafter termed
"KV") is no less that 3.0 mm2/s, and the NOACK evaporation
(JPI-5S-41) is no less that 15 mass %, and HDHSV 50.degree.
C./HTHSV 150.degree. C..ltoreq.6.50 and KV 50.degree. C./HTHSV
150.degree. C..ltoreq.8.00.
[0012] The composition, methods for manufacturing, characteristics,
and applications of the internal combustion engine lubricating oil
composition according to the present invention will be explained in
detail below, but the present invention is in no way limited
thereto.
DETAILED DESCRIPTION
[0013] The internal combustion engine lubricating oil composition
according to the present invention includes a base oil and a
viscosity index improving agent, and, if necessary, includes other
additives as well. The composition according to the present
invention will be explained below.
[0014] The base oil in the lubricating oil composition according to
the present invention includes, as an essential component, a GTL
(gas-to-liquid) base oil, synthesized using the Fischer-Tropsch
method. The GTL (gas-to-liquid) base oil that is synthesized using
the Fischer-Tropsch method, which is a technology for turning
natural gas into a liquid fuel, when compared to a mineral oil base
oil that is refined from crude oil, is extremely low in sulfur
content and aromatic components, and extremely high in its
proportion of paraffin structures, and thus the evaporative loss
will also be extremely low and the oxidation stability will be
superior, making this suitable as a base oil for the present
invention. While there is no particular limitation on the viscosity
characteristic of the GTL base oil, normally the kinematic
viscosity at 100.degree. C. may be between 1.0 and 50.0 mm.sup.2/s,
more preferably between 1.0 and 12.0 mm.sup.2/s, and, more
preferably, between 3.0 and 10.0 mm.sup.2/s. Moreover, normally the
viscosity index may be between 100 and 180, and preferably between
105 and 160, and more preferably be between 110 and 150.
[0015] Moreover, normally the total sulfur content may be less than
10 ppm, and the total nitrogen content may be less than 1 ppm. The
GTL base oil product may be Shell XHVI (registered trademark).
[0016] Note that the lubricating oil composition according to the
present invention may include other base oils if necessary. Mineral
oils and hydrocarbon-based synthetic oils, known as highly refined
base oils, may be used as the other base oils, and, in particular,
a base oil selected from a group comprising base oils classified in
group 2, group 3, and group 4 of the API (American Petroleum
Institute) Base Oil Classifications may be used. The base oil used
here has a 100.degree. C. kinematic viscosity of between 3.0 and
12.0 mm.sup.2/s, but preferably may be between 3.0 and 10.0
mm.sup.2/s, and more preferably between 3.0 and 8.0 mm.sup.2/s. The
viscosity index of the base oil may be between 100 and 180, and
preferably between 100 and 160, and more preferably between 100 and
150. The sulfur element content of the base oil may be no greater
than 300 ppm, and preferably no greater than 200 ppm, more
preferably no greater than 100 ppm, and even more preferably no
greater that 50 ppm. Moreover, the density of the base oil at
15.degree. C. may be between 0.80 and 0.95 g/cm.sup.3, preferably
between 0.80 and 0.90 g/cm.sup.3, and more preferably between 0.80
and 0.85 g/cm.sup.3.
[0017] The group 2 base oil may be a paraffin-based mineral oil
obtained through, for example, the use of an appropriate
combination of refining means, such as hydrocracking, dewaxing, and
the like, to a lubricating oil fraction obtained through
low-pressure distillation of crude oil. Moreover, a group 2 base
oil refined through the hydrorefining of Gulf Corporation, or the
like, has a total sulfur content of less than 10 ppm, and an
aromatic content % CA of no greater than 5 ppm, and is suitable for
use as a base oil that is mixed into the lubricating oil
composition according to the present invention. In the group 2 base
oil, preferably the viscosity index (where the viscosity index in
the present invention is measured using ASTM D2270 or JIS K2283) is
no less than 100 and is less than 120, and more preferably is no
less that 105 and less than 120. The 100.degree. C. kinematic
viscosity of the group 2 base oil (where the kinematic viscosity in
the present invention is measured using ASTM D445 or JIS K 2283)
preferably is between 3.0 and 12.0 mm.sup.2/s, and more preferably
between 3.0 and 9.0 mm.sup.2/s. Moreover, in the group 2 base oil,
preferably the total sulfur content is less than 300 ppm, more
preferably less than 200 ppm, even more preferably less than 100
ppm, and particularly preferably less that 10 ppm. The total sulfur
content is a value that is measured using a radioexcitation method
(based on ASTM D4294 and JIS K2541-4). The total nitrogen content
of the group 2 base oil may be less than 10 ppm, and preferably
less than 1 ppm. Moreover, the aniline point of the group 2 base
oil (where the aniline point in the present invention is measured
through ASTM D611 and JIS K2256) preferably is between 80 and
150.degree. C., and more preferably between 100 and 135.degree.
C.
[0018] The group 3 base oil may be, for example, a "paraffin-based
mineral oil obtained through the application of high-level
hydrorefining means to a lubricating oil fraction obtained through
low-pressure distillation of crude oil," "a base oil refined
through the Mobil wax (WAX) isomerizing process," or the like.
[0019] The group 3 base oil viscosity index preferably is between
120 and 150, and more preferably is between 120 and 140. The group
3 base oil 100.degree. C. kinematic viscosity preferably is between
3.0 and 12.0 mm.sup.2/s, and more preferably between 3.0 and 9.0
mm/s. Moreover, the group 3 base oil total sulfur content
preferably is less than 100 ppm, and more preferably is less than
10 ppm. The group 3 base oil total nitrogen content preferably is
less than 10 ppm, and more preferably less than 1 ppm.
[0020] Moreover, the group 3 base oil aniline point is preferably
between 80 and 150.degree. C., and more preferably between 110 and
140.degree. C.
[0021] The group 4 base oil may be, for example, a polyalphaolyfin,
an alphaolefin oligomer, a mixture thereof (a polyalphaolyfin and
an alphaolefin oligomer), or the like. The polyalphaolyfin (PAO) is
any of a variety of polymers of alphaolefins (monomers). Moreover,
the polyalphaolyfin may be a mixture wherein a plurality of types
of copolymers of "alphaolefins (monomers)" are mixed, rather than a
single type of "polymer of alphaolefins (monomers)." Moreover, the
alphaolefin oligomer is any of a variety of types of oligomers of
alphaolefins (monomers), and includes hydrogenated oligomers of
alphaolefins (monomers). There is no particular limitation on the
alphaolefins (monomers), and they may be, for example, ethylene,
propylene, butene, an alphaolefin with a carbon number of five or
more, or the like.
[0022] The hydrocarbon-based synthetic oil may be, for example, a
polyolefin, including a PAO, or the like, described above, alkyl
benzene, alkyl naphthalene, or the like, or a mixture, or the like,
thereof.
[0023] There are no particular limitations on the viscosities of
these synthetic base oils, but the 100.degree. C. kinematic
viscosity is preferably between 3.0 and 12.0 mm.sup.2/s, more
preferably between 3.0 and 10.0 mm.sup.2/s, and even more
preferably between 3.0 and 8.0 mm.sup.2/s. The viscosity index of
the synthetic base oil, for the case of alkyl benzene or alkyl
naphthalene, preferably is between 10 and 120, more preferably
between 20 and 120, and even more preferably between 20 and 110,
and, in the case of a polyalphaolefin, preferably is between 100
and 170, more preferably between 110 and 170, and even more
preferably between 110 and 155. The 15.degree. C. density of the
synthetic base oil is preferably between 0.8000 and 0.9500
g/cm.sup.3, more preferably between 0.8100 and 0.9500 g/cm.sup.3,
and even more preferably between 0.8100 and 0.9200 g/cm.sup.3.
[0024] Moreover, the base oil of the present lubricating oil
composition may have a base oil belonging to group 1 of the Base
Oil Categories of the API (American Petroleum Institute), mixed
into the base oil described above. The group 1 base oil may be a
paraffin-based mineral oil obtained through, for example, the use
of an appropriate combination of refining means, such as solvent
refining, hydrorefining, dewaxing, and the like, to a lubricating
oil fraction that is obtained through atmospheric-pressure
distillation of crude oil. In the group 1 base oil used here, the
100.degree. C. kinematic viscosity may be between 3.0 and 35.0
mm.sup.2/s, but preferably may be between 3.0 and 10.0 mm.sup.2/s,
and more preferably between 3.0 and 8.0 mm.sup.2/s. Moreover, the
viscosity index may be between 90 and 120, and preferably between
95 and 115, and more preferably be between 95 and 110. Moreover,
the sulfur content may be between 0.03 and 0.7 mass %, and
preferably between 0.1 and 0.7 mass %, and more preferably between
0.4 and 0.7 mass %. Moreover, the % CA, in ASTM D3238, may be 5 or
less, or preferably no greater than 4, or more preferably no
greater than 3.4. Moreover, the % CP, in ASTM D3238, may be 60 or
more, or preferably no less than 63, or more preferably no less
than 66.
[0025] Moreover, in the lubricating oil composition according to
the present invention, one or more base oils wherein the KV
100.degree. C. is between 1 and 8 mm.sup.2/s, the viscosity index
is no less than 110, and the % CA is no greater than 5 and the % CP
is no less than 60, according to ASTM D3238, may be included, so as
to be no more than 50 mass % of the lubricating oil composition as
a whole, so that the fracture at 380.degree. C. or less in gas
chromatographic distillation through ASTM D2887, in the base oil as
a whole, is no more than 10 mass %. The use of such a base oil
makes it possible to provide a lubricating oil composition wherein
a portion of the GTL oil is replaced with another base oil without
a significant loss in the reduction of evaporative loss, which is a
distinctive feature of the GTL oil.
[0026] Viscosity index improving agents generally are polymer
substrates that have the effect of improving the viscosity index. A
variety of viscosity index improving agents may be used in the
present invention. Examples of viscosity index improving agents
include poly(meth)acrylate and olefin copolymers such as
ethylene/propylene copolymers and styrene/diene copolymers, and the
like, as non-dispersive viscosity index improving agents, along
with dispersive viscosity index improving agents such as those that
can be obtained through copolymerization of these with monomers
that include nitrogen. A comb polymer, which has a high viscosity
index improving effect and is useful in reduction of (design of)
the low-temperature viscosity, is preferred as a viscosity index
improving agent. Note that the comb polymer is a polymer that forms
a comb shape through combining, with polymer main chains,
relatively long side chains that are known polymers. A known comb
polymer may be used as such a comb polymer. More specifically, a
comb polymer may be used wherein (1) repeating units derived from
polyolefin-based macro monomers and (2) repeating units derived
from low-molecular-weight monomers selected from a group comprising
styrene monomers having between 8 and 17 carbon atoms,
alkyl(meth)acrylates having between 1 and 10 carbon atoms in an
alcohol base, vinyl esters having between 1 and 11 carbon atoms in
an acyl, vinyl ethers having between 1 and 10 carbon atoms in an
alcohol base, (di)alkyl fumarate having between 1 and 10 carbon
atoms in an alcohol base, (di)alkyl maleates having between 1 and
10 carbon atoms in an alcohol base, and mixtures of these monomers,
are included in the main chain. In particular, that which is
suitable has a molar branching level of between 0.3 and 1.1 mol %,
wherein, in relation to the mass of the repeating units, described
above, the total of the (1) repeating units derived from
polyolefin-based macro monomers and (2) repeating units derived
from low-molecular-weight monomers selected from a group comprising
styrene monomers having between 8 and 17 carbon atoms,
alkyl(meth)acrylates having between 1 and 10 carbon atoms in an
alcohol base, vinyl esters having between 1 and 11 carbon atoms in
an acyl, vinyl ethers having between 1 and 10 carbon atoms in an
alcohol base, (di)alkyl fumarate having between 1 and 10 carbon
atoms in an alcohol base, (di)alkyl maleates having between 1 and
10 carbon atoms in an alcohol base, and mixtures of these monomers,
is no less than 80 mass %, with the repeating units derived from
the polyolefin-based macro molecule being between 8 and 30 mass %,
and wherein the iodine number is no greater than 0.2 g per 1 g of
the comb polymer.
[0027] Here the inclusion proportion of the viscosity index
improving agent is between 0.1 and 15 mass %, in terms of the
amount of resin, relative to the lubricating oil composition as a
whole, and, more preferably, is between 0.1 and 10 mass %, in terms
of the amount of resin.
[0028] In the lubricating oil composition according to the present
invention, additives other than the viscosity index improving agent
(other additives) may include Ca/Mg-based cleaning agents
(metal-including cleaning agents that include at least one
selection from Ca and Mg), succinimide-based/boron-modified
succinimide-based ashless dispersing agents, ZnDTP, and/or friction
adjusting agents (which may be organic molybdenum compounds).
Moreover, corrosion inhibitors, phenol-based oxidation inhibitors,
amine-based oxidation inhibitors, and/or sulfur-including additives
may be used suitably as other additives. Other additives such as
these will be explained below.
[0029] In the lubricating oil composition according to the present
invention, a Ca-based cleaning agent (a cleaning agent that
includes at least Ca) and/or a Mg-based cleaning agent (a cleaning
agent that includes at least Mg) may be included, where the
inclusion proportion thereof is suitably in a range that satisfies
[Ca]+[Mg]=0.10 to 0.25 (wherein [Ca] and [Mg] are the respective
concentrations (mass %) of calcium and magnesium in the lubricating
oil composition). Note that if [Ca]+[Mg] is between 0.10 and 0.25,
[Mg] may be 0 (that is, no Mg is included) or [Mg] may be greater
than zero (that is, some or all of the Ca-based cleaning agent is
replaced with a Mg-based cleaning agent). When [Ca]+[Mg] does not
exceed 0.25, there is the benefit of achieving an improvement in
the torque improvement ratio, and when not less than 0.10,
cleanliness will be improved.
[0030] The Ca/Mg cleaning agent may be a known metal-including
cleaning agent, including calcium and/or magnesium as an alkaline
earth metal. Note that such a metal-including cleaning agent may
include a phenate, a salicylate, a carboxylate, or a sulfonate as
the main component thereof.
[0031] The lubricating oil composition according to the present
invention may include a succinimide-based ashless dispersing agent
and/or a boron-modified succinimide-based ashless dispersing agent,
and the inclusion proportion thereof may satisfy a condition
between 0.01 and 0.20 mass % (in reference to the total amount of
the lubricating oil composition), in terms of the nitrogen
concentration. Note that being no greater than 0.20 mass %, in
terms of the nitrogen concentration, is useful in wear
resistance.
[0032] That which is known may be used for a bis-type
succinimide-based ashless dispersing agent that does not include
boron, and a bis-type succinimide wherein, at the time of
imidization, anhydrous succinic acid is added to both ends of a
polyamine may be used. Moreover, that which is known to be used for
the boron-modified succinimide-based ashless dispersing agent may
be used, and may be a succinimide wherein a mono-type succinimide,
to which, at the time of imidization, anhydrous succinic acid has
been added to one end of a polyamine, and/or a bis-type succinimide
wherein anhydrous succinic acid has been added to both ends of a
polyamine, has been boron-modified.
[0033] The lubricating oil composition according to the present
invention may include ZnDTP, and the inclusion portion thereof may
be between 0.03 and 0.09 mass %, as a phosphorous inclusion
proportion (in reference to the total amount of the lubricating oil
composition). Note that ZnDTP has a function as an anti-wear agent,
and if the phosphorus inclusion proportion is no less than 0.03
mass %, the wear resistance will be more superior. Moreover, if the
phosphorus inclusion proportion is no greater than 0.09 mass %, it
is unlikely to interfere with the effect of the friction adjusting
agent.
[0034] ZnDTP is an abbreviation for Zinc Dialkyldithiophosphate,
and is expressed by structural formula (1), below. In the equation,
R indicates mutually independent hydrocarbon groups. Preferably
they are primary or secondary alkyl groups of between C3 and C20.
More preferably, they are primary or secondary alkyl groups of
between C3 and C10.
##STR00001##
[0035] An arbitrary compound that is normally used as a lubricating
oil friction adjusting agent may be used in the lubricating oil
composition according to the present invention, and may be, for
example, an organic molybdenum compound or ashless friction
adjusting agent. An organic molybdenum compound and an ashless
friction adjusting agent may be used either singly or in
combination.
[0036] That which is known may be used for the organic molybdenum
compound and may be, for example, molybdenum dithiocarbamate (which
may be abbreviated simply MoDTC, or the like), a trinuclear
molybdenum compound as described in WO-98/26030, a sulfide of
molybdenum, a molybdenum dihiophosphate salt, a molybdenum-amine
complex, a molybdenum-succinimide complex, a molybdenum salt of an
organic acid, a molybdenum salt of an alcohol, or the like. The
inclusion proportion thereof, in an arbitrary combination of the
organic molybdenum compounds, may satisfy between 0.01 and 0.12
mass % in terms of the Mo concentration (in reference to the total
amount of the lubricating oil composition). Note that the storage
stability is better at no more than 0.12 mass %, in terms of the Mo
concentration.
[0037] That which is known conventionally may be used as the
ashless friction adjusting agent, and may be, for example, an alkyl
group or alkynyl group with a carbon number between 3 and 30, and,
in particular, may be an ashless friction adjusting agent, such as
an amine compound, a fatty acid ester, a fatty acid amide, a fatty
acid, an aliphatic alcohol, an aliphatic ether, or the like, which
has, in the molecule, at least one straight-chain alkyl group or
straight-chain alkynyl group with a carbon number between 3 and 30.
Note that some or all of these alkyl groups or alkynyl groups may
be replaced with alkoxy groups, or carbon atoms of the alkyl groups
or alkynyl groups may be replaced by hetero atoms. Note that while
there is no particular limitation on the inclusion proportion for
the ashless friction adjusting agent, it may, for example, satisfy
0.01 to 1.0 mass % (in reference to the total amount of the
lubricating oil composition). Note that the storage stability and
seal compatibility will be improved if this is no greater than 1.0
mass %.
[0038] In the present invention, molybdenum dithiocarbamate is the
most suitable from the perspective of optimally reducing
friction.
[0039] The lubricating oil composition according to the present
invention may include a corrosion inhibitor.
[0040] That which is known may be used for the corrosion inhibitor,
which may be, for example, a benzotriazole-based,
tolyltriazole-based, thiadiazole-based, or imidazole-based
compound, or the like.
[0041] Note that while there is no particular limitation on the
inclusion proportion, it may be, for example, between 0.01 and 0.1
mass % (in reference to the total amount of the lubricating oil
composition).
[0042] A phenol-based oxidation inhibitor and/or an amine-based
oxidation inhibitor may be included as an ashless oxidation
inhibitor in the lubricating oil composition according to the
present invention.
[0043] That which is known may be used as the phenol-based
oxidation inhibitor, which may be, for example, 4, 4'-methylene bis
(2, 6-di-tert-butyl phenol), 4, 4'-bis (2, 6-di-tert-butyl phenol),
or the like. That which is known may be used for the amine-based
oxidation inhibitor, which may be, for example, alkyl diphenyl
amine, alkyl naphthyl amine, phenyl-alpha-naphthyl amine, alkyl
phenyl-alpha-naphthyl amine, or the like, which are aromatic amine
compounds.
[0044] While there is no particular limitation on the inclusion
proportion for the amine-based oxidation inhibitor, it should be,
for example, between 0.1 and 2.0 mass % (in reference to the total
amount of the lubricating oil composition). Moreover, while there
is no particular limitation on the inclusion proportion for the
phenol-based oxidation inhibitor, it should be, for example,
between 0.1 and 2.0 mass % (in reference to the total amount of the
lubricating oil composition).
[0045] The lubricating oil composition according to the present
invention may include a sulfur-including additive. Note that the
sulfur-including additive indicated here indicates a sulfur
compound other than the ZnDTP and MoDTC described above, and may be
selected as a component that is further added after adding the
MoDTC.
[0046] That which is known may be used for this sulfur-including
additive, which may be, for example, hydrogen sulfide, a sulfur
cross-linked metal phenate, dihydrocarbyl polysulfide, a
dithiocarbamate other than MoDTC, or the like.
[0047] Note that while there is no particular limitation on the
inclusion proportion for the sulfur-including additive, it should
be between 0.1 mass % and 2.0 mass %, in relation to the
lubricating oil composition as a whole.
[0048] As required, additives other than the above, such as
oxidation inhibitors, ashless dispersing agents, metal cleaning
agents, friction adjusting agents, rust inhibiting agents,
anti-forming agents, or the like, may also be added to the
lubricating oil composition according to the present invention.
Moreover, an additive package, wherein some or all of the additives
to be mixed in are packaged, may be used (or may be used as
well).
[0049] Note that while there is no particular limitation on the
inclusion proportion of the other components such as this, it
should be between 10 mass % and 30 mass %, relative to the
lubricating oil composition as a whole, as additives other than the
base oil, taking into consideration also dilution of the oil in
which the various additives, including the viscosity index
improving agent, are included.
[0050] While there is no particular limitation on the method for
manufacturing the lubricating oil composition according to the
present invention, the manufacturing may be through, for example,
adding and mixing the various components described above through an
arbitrary process.
[0051] The lubricating oil composition according to the present
invention is provided with all of the following characteristics (A)
through (E):
(A) high temperature high shear viscosity (HTHSV (ASTM D4683 or
ASTM D5481)) at 150.degree. C., 106 s-1 is 1.0 mPas or more; (B)
kinetic viscosity (KV (JIS K2283)) at 100.degree. C. is 3.0 mm2/s
or more; (C) HTHSV50.degree. C./HTHSV150.degree. C. is 6.50 or
less; (D) KV50.degree. C./HTHSV150.degree. C. is 8.00 or less; and
(E) NOACK evaporation amount (JPI-5S-41) is 15 mass % or less.
[0052] In the lubricating oil composition according to the present
invention, having the HTHSV 50.degree. C./HTHSV 150.degree. C. be
no greater that 6.50 and the KV 50.degree. C./HTHSV 150.degree. C.
be no greater than 8.00 enables an improvement in fuel economy and
satisfaction of a NOACK evaporation (JPI-5S-41) of no greater than
15 mass %, even given conditions of (A) 150.degree. C., 106 s-1
high-temperature/high-shear viscosity (HTHSV (ASTM D4683 or ASTM
D5481)) no less than 1.0 mPas and a 100.degree. C. kinematic
viscosity (KV) no less than 3.0 mm.sup.2/s.
[0053] Note that specifically, in order to achieve (C) and (D),
above, it is effective to reduce the solubility, relative to the
base oil, below that of existing viscosity index improving agents,
and to increase the temperature of complete dissolution of the
polymer. For example, if the viscosity index improving agent is
PMA, it is possible to make adjustments through increasing the
polarity of the PMA by increasing the chain length of the R (long
alkyl chain) of the --COOR group that is a structural element of
the PMA.
[0054] The lubricating oil composition according to the present
invention can be used as a lubricating oil composition for an
ordinary internal combustion engine, but is particularly
well-suited as a lubricating oil composition for a PHV internal
combustion engine and/or for an internal combustion engine for an
idling-stopping vehicle.
Examples
[0055] Lubricating oil compositions according to the invention and
Reference Examples 1 through 5 were prepared through mixing the raw
materials listed below so as to have the blending quantities (mass
%) shown in Table 1. Note that in the present invention, a
composition wherein the 150.degree. C. HTHSV is no greater that 2.5
is classified corresponding to 0W-20, and if less than this, is
classified corresponding to 0W-16.
Base Oils
[0056] Shell XHVI (registered trademark) 4 (GTL base oil); [0057]
Shell XHVI (registered trademark) 3 (GTL base oil).
DI Package
[0058] The primary ingredients in the package used are shown below.
[0059] Package A.
[0060] A mixture of a highly refined mineral oil, a
succinimide-based ashless dispersing agent, a calcium-based metal
cleaning agent, ZnDTP, and an amine-based oxidation inhibitor.
[0061] Package B.
[0062] A mixture of a highly refined mineral oil, a
succinimide-based ashless dispersing agent, a calcium-based metal
cleaning agent, a magnesium-based metal cleaning agent, ZnDTP, and
an amine-based oxidation inhibitor. [0063] Package C.
[0064] A mixture of a highly refined mineral oil, a
succinimide-based ashless dispersing agent, a magnesium-based metal
cleaning agent, a calcium-based metal cleaning agent, ZnDTP, an
amine-based friction adjusting agent, an amine-based oxidation
inhibitor, and a phenol-based anti-oxidizing agent.
Viscosity Index Improving Agent
[0065] Viscosity index improving agent E: Non-comb PMA; [0066]
Viscosity index improving agent F: OCP; [0067] Viscosity index
improving agent D, G, and H: Comb PMAs.
[0068] Here the viscosity index improving agents D, G, and H are
comb PMAs manufactured under different conditions, to have
differences in numbers of repetitions, chain lengths of the long
alkyl chains, and the like, to exhibit mutually differing
polarities.
Friction Adjusting Agent
[0069] Sakuralube 525 (MoDTC (molybdenum dithiocarbamate),
manufactured by ADEKA Co.).
Anti-Foaming Agent
[0069] [0070] A 3 mass % solution wherein polymethyl siloxane
(silicone oil) with a weight average molecular weight of
approximately 30,000 is dissolved, at DCF 3 mass %, into JIS No. 1
kerosene.
[0071] Here the concentrations of Ca, Mg, Mo, P, Zn, N, and S (mass
%, in reference to the total amount of the lubricating oil
composition) in Reference Examples 1 through 5 and Examples 1
through 4 are shown in Table 2. The measurement methods are based
on JPI-5S-38 for B, Ca, Mg, Mo, P, and Zn, based on JIS K2609 for
N, and based on JIS K2541-4 (the radiostimulation method) for
S.
Evaluation
[0072] Next, for each of the individual lubricating oil
compositions, the high-temperature/high-shear viscosities
(50.degree. C. and 150.degree. C.) were measured based on ASTM
D5481, the kinematic viscosities (40.degree. C., 50.degree. C., and
100.degree. C.) were measured based on JIS K2283, and the NOACK
evaporation was measured based on JPI-5S-41, and the reduction in
fuel consumption was also evaluated. The evaluation results are
shown in Table 3. The method for evaluating the fuel economy (the
reduction in fuel consumption) was as follows.
[0073] An engine was driven by an electric motor, and the force
required to do so (the friction torque) was measured by a torque
meter. A four-cylinder in-line 2.0-L direct injection engine was
used for the engine, with a test oil temperature of 50.degree. C.,
and a rotational speed of 2,000 RPM (where the lubricating oil
composition of Reference Example 1 was used as a reference
oil).
[0074] Note that 50.degree. C. was selected as the test oil
temperature, envisioning the state wherein a typical passenger
vehicle has just been started, or traveling conditions wherein the
engine oil temperature does not increase substantially, in an idle
stopping vehicle or a PHV.
[0075] In Table 3 it can be appreciated that, when compared to the
corresponding lubricants of the same viscosity grades, that is,
when for Reference Example 1, Example 1, and Example 3, which
correspond to 0W-20, are compared, and Reference Example 2,
Reference Example 3, Example 2, and Example 4, which correspond to
0W-16, are compared, the fuel economy can be improved through
having the HTHSV 50.degree. C./HTHSV 150.degree. C. be no greater
than 6.50, and the KV 50.degree. C./HTHSV 150.degree. C. be no
greater than 8.00.
TABLE-US-00001 TABLE 1 Reference Example 1 (Reference Reference
Reference Reference Reference Oil) Example 2 Example 3 Example 4
Example 5 Corresponding Corresponding Corresponding Corresponding
Corresponding to 0 W-20 to 0 W-16 to 0 W-16 to 0 W-16 to 0 W-16
SHELL XHVI 82.82 74.67 74.07 77.07 75.57 4 SHELL XHVI 8.50 8.50
8.50 8.50 3 Package A 9.05 Package B 9.30 9.30 9.30 9.30 Package C
Sakuralube 1.00 1.00 1.00 1.00 1.00 525 (MoDTC) Viscosity 4.70 6.50
Index Improving Agent D Viscosity 2.40 4.10 Index Improving Agent E
Viscosity 5.60 Index Improving Agent F Viscosity 7.10 Index
Improving Agent G Viscosity Index Improving Agent H DCF 003 0.03
0.03 0.03 0.03 solution Total 100.00 100.00 100.00 100.00 100.00
Example 1 Example 2 Example 3 Example 4 Corresponding Corresponding
Corresponding Corresponding to 0 W-20 to 0 W-16 to 0 W-20 to 0 W-16
SHELL XHVI 73.37 73.87 72.65 76.27 4 SHELL XHVI 6.50 8.50 6.50 6.00
3 Package A Package B 9.30 9.30 Package C 10.2 10.2 Sakuralube 100
1.00 1.00 1.00 525 (MoDTC) Viscosity Index Improving Agent D
Viscosity Index Improving Agent E Viscosity Index Improving Agent F
Viscosity Index Improving Agent G Viscosity 9.80 7.30 9.62 6.50
Index Improving Agent H DCF 0.03 0.03 0.03 0.03 solution Total
100.00 100.00 100.00 100.00
TABLE-US-00002 TABLE 2 Reference Example 1 (Reference Reference
Reference Reference Reference Oil) Example 2 Example 3 Example 4
Example 5 Corresponding Corresponding Corresponding Corresponding
Corresponding to 0 W-20 to 0 W-16 to 0 W-16 to 0 W-16 to 0 W-16 B
0.01 <0.01 <001 <0.01 <0.01 Ca 0.22 0.15 0.15 0.15 0.15
Mg -- 0.06 0.06 0.06 0.06 Mo 0.10 0.10 0.10 0.10 0.10 P 007 0.07
0.07 0.07 0.07 Zn 0.09 0.08 0.08 0.08 008 N 0.10 0.09 0.09 0.09
0.09 S 0.34 0.36 0.36 0.36 0 36 Example 1 Example 2 Example 3
Example 4 Corresponding Corresponding Corresponding Corresponding
to 0 W-20 to 0 W-16 to 0 W-20 to 0 W-16 B <0.01 <0.01 0.01
0.01 Ca 0.15 0.15 0.14 0.14 Mg 0.06 0.06 0.05 0.05 Mo 0.10 0.10
0.10 0.10 P 0.07 0.07 0.07 0.07 Zn 008 0.08 0.08 0.08 N 0.09 0.09
0.09 0.09 S 0.36 0.36 0.38 0.38
TABLE-US-00003 TABLE 3 Reference Example 1 Reference Reference
Reference Reference Reference Oil) Example 2 Example 3 Example 4
Example 5 Corresponding Corresponding Corresponding Corresponding
Corresponding to 0 W-20 to 0 W-16 to 0 W-16 to 0 W-16 to 0 W-16 KV
50.degree. C. (mm2/s) 23.1 18.2 17.9 23 4 24.8 HTHSV 50.degree. C.
(TBS) 16.1 14.4 14.2 15.2 16.6 (mPa - s) HTHSV 150.degree. C. (TBS)
2.55 2.24 2.19 2.29 2.29 (mPa s) KV 40aC (mm2/s) 23.1 25.2 24.8
32.4 35.1 KV 100.degree. C. (mm2/s) 7.75 6.40 6.13 7.33 7.08 NOACK
250.degree. C. (%) 15 15 15 15 15 HTHSV 50.degree. C./HTHSV 6.33
6.41 6 49 6.65 7 23 150.degree. C. (--) KV 50.degree. C./HTHSV 9.05
8.13 8.18 10.21 10.82 150.degree. C. (--) 2,000 RPM Torque 0.0 1.6
2.2 -- -- Improvement Ratio (%) Example 1 Example 2 Example 3
Example 4 Corresponding Corresponding Corresponding Corresponding
to 0 W-20 to 0 W-16 to 0 W-20 to 0 W-16 KV 50.degree. C. (mm2/s)
19.0 17.9 19.0 17.9 HTHSV 50.degree. C.(TBS) 14.8 14.2 15.1 14.5
(mPa - s) HTHSV 2.52 2.26 2.55 2.25 150.degree. C. (TBS) mPa s) KV
40aC (mm2/s) 26.1 24.7 26.2 24.8 KV 100.degree. C. 6.90 6.17 6.86
6.07 (mm2/s) NOACK 250.degree. C. (%) 15 15 15 15 HTHSV 5.85 6.28
5.91 6.44 50.degree. C./HTHSV 150.degree. C. (--) KV 50.degree.
C./HTHSV 7.54 7.93 7.44 7.95 150.degree. C. (--) 2,000 RPM 2.8 3.5
1.8 2.8 Torque Improvement Ratio (%)
* * * * *