U.S. patent application number 12/816224 was filed with the patent office on 2010-12-16 for lubricating oil composition.
This patent application is currently assigned to Chevron Japan Ltd.. Invention is credited to Masami Fuchi, Takahiro Nakagawa, Michio Shiga.
Application Number | 20100317554 12/816224 |
Document ID | / |
Family ID | 43306937 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100317554 |
Kind Code |
A1 |
Fuchi; Masami ; et
al. |
December 16, 2010 |
LUBRICATING OIL COMPOSITION
Abstract
There is provided a lubricating oil composition that has good
friction performance and friction performance durability, and which
is unlikely to cause degradation of oil seals made from
fluororubbers, and which is particularly useful as an automatic
transmission fluid. This lubricating oil composition is produced by
adding a phosphorus/nitrogen-containing ashless dispersant of 0.2
to 8 wt % with a nitrogen/phosphorus ratio of 1.5 to 2.8, a
friction modifier of 0.01 to 5 wt %, a metal-containing detergent
of 0.005 to 2 wt %, and an antioxidant of 0.1 to 5 wt % as
additives to a base oil with a lubricating viscosity.
Inventors: |
Fuchi; Masami;
(Makinohara-City, JP) ; Nakagawa; Takahiro;
(Haibara-Gun, JP) ; Shiga; Michio;
(Hiratsuka-City, JP) |
Correspondence
Address: |
CHEVRON CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Assignee: |
Chevron Japan Ltd.
|
Family ID: |
43306937 |
Appl. No.: |
12/816224 |
Filed: |
June 15, 2010 |
Current U.S.
Class: |
508/428 |
Current CPC
Class: |
C10M 2219/106 20130101;
C10M 2215/08 20130101; C10M 141/10 20130101; C10M 2223/08 20130101;
C10M 2215/28 20130101; C10M 2207/026 20130101; C10M 2203/1025
20130101; C10N 2040/042 20200501; C10N 2030/36 20200501; C10N
2030/06 20130101; C10M 2229/02 20130101; C10M 2219/046 20130101;
C10M 163/00 20130101; C10M 2215/064 20130101; C10M 2209/084
20130101; C10M 2203/1025 20130101; C10N 2020/02 20130101; C10M
2215/28 20130101; C10M 2201/085 20130101; C10M 2219/046 20130101;
C10N 2010/04 20130101; C10M 2203/1025 20130101; C10N 2020/02
20130101; C10M 2219/046 20130101; C10N 2010/04 20130101 |
Class at
Publication: |
508/428 |
International
Class: |
C10M 137/00 20060101
C10M137/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2009 |
JP |
2009-143651 |
Claims
1. A lubricating oil composition, produced by adding a
phosphorus/nitrogen-containing ashless dispersant of 0.2 to 8 wt %
with a nitrogen/phosphorus ratio of 1.5 to 2.8, a friction modifier
of 0.01 to 5 wt %, a metal-containing detergent of 0.005 to 2 wt %,
and an antioxidant of 0.1 to 5 wt % as additives to a base oil with
a lubricating viscosity, wherein the amounts in which the additives
are added are in percentages with respect to the total weight of
the lubricating oil composition.
2. The lubricating oil composition according to claim 1, wherein
the phosphorus/nitrogen-containing ashless dispersant is the
product of a reaction between a nitrogen-containing ashless
dispersant and phosphoric acid or phosphorous acid and wherein the
ashless dispersant is non-borated.
3. The lubricating oil composition according to claim 1, wherein
the phosphorus/nitrogen-containing ashless dispersant is the
product of a reaction between polyisobutenylsuccinimide and
phosphoric acid or phosphorous acid.
4. The lubricating oil composition according to claim 3, wherein
the polyisobutenylsuccinimide is a polyisobutenylsuccinimide with a
bis structure.
5. The lubricating oil composition according to claim 1, wherein
the friction modifier is a C.sub.6 to C.sub.30 hydrocarbon
substituted succinimide
6. The lubricating oil composition according to claim 5, wherein
the succinimide is the product of a reaction between ammonia and an
alkenylsuccinic anhydride in which the alkenyl group is an internal
olefin obtained by the isomerization of an olefinic double bond of
a linear alpha olefin with 10 to 30 carbon atoms.
7. The lubricating oil composition according to claim 1, wherein
the friction modifier is a fatty acid amide.
8. The lubricating oil composition according to claim 7, wherein
the fatty acid amide is a reaction product obtained by a
condensation reaction of an amine and a monovalent fatty acid with
6 to 30 carbon atoms.
9. The lubricating oil composition according to claim 5, wherein
the friction modifier includes succinimide and a fatty acid amide
compound.
10. The lubricating oil composition according to claim 1, wherein
the metal-containing detergent is an alkali metal sulfonate.
11. The lubricating oil composition according to claim 1, wherein
the antioxidant is one or more ashless antioxidants selected from
the group consisting of amine compounds having an antioxidant
property, and phenol compounds having an antioxidant property.
12. An automatic transmission lubricating oil composition
comprising 0.2 to 8 wt % of a phosphorolyated polyisobutenyl
succinimide having a nitrogen/phosphorus mass ratio of 1.5 to 2.8
wherein the polyisobutenyl group has an average molecular weight of
900 to 2300; 0.01 to 5 wt % a friction modifier succinimide derived
from the reaction product of an isomerized C.sub.6 to C.sub.30
alkenyl succinic anhydride with an amine selected from the group of
ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine,
and tetraethylenepentamine; a metal-containing detergent of 0.005
to 2 wt %; and an antioxidant of 0.1 to 5 wt % as additives to a
base oil with a lubricating viscosity, wherein the amounts in which
the additives are added are in percentages with respect to the
total weight of the lubricating oil composition.
13. The automatic transmission lubricating oil composition
according to claim 12, wherein the phosphorolyated polyisobutenyl
succinimide is non-borated.
14. The automatic transmission lubricating oil composition
according to claim 12 wherein the total phosphorous content in the
lubricating oil composition is less than 700 parts per million
phosphorous.
15. A method for improving fluororubber seal compatibility while
maintaining stability of the coefficient of friction as measured
according to the JASCO M315:2004 in an automatic transmission
comprising using an automatic transmission lubricating oil
composition comprising 0.2 to 8 wt % of a phosphorolyated
polyisobutenyl succinimide having a nitrogen/phosphorus mass ratio
of 1.5 to 2.8 wherein the polyisobutenyl group has an average
molecular weight of 900 to 2300; 0.01 to 5 wt % a friction modifier
succinimide derived from the reaction product of an isomerized
C.sub.6 to C.sub.30 alkenyl succinic anhydride with an amine
selected from the group of ammonia, ethylenediamine,
diethylenetriamine, triethylenetetramine, and
tetraethylenepentamine; a metal-containing detergent of 0.005 to 2
wt %; and an antioxidant of 0.1 to 5 wt % as additives to a base
oil with a lubricating viscosity, wherein the amounts in which the
additives are added are in percentages with respect to the total
weight of the lubricating oil composition.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a lubricating oil
composition, and more particularly relates to a lubricating oil
composition that is very useful as an automatic transmission
fluid.
DESCRIPTION OF THE RELATED ART
[0002] Lubricating oils, called automatic transmission fluids, have
been used conventionally to assist smooth operation of automatic
transmissions that are installed in automobiles and include a
torque converter, a gear mechanism, a wet clutch, and a hydraulic
mechanism. In modern automobiles, fuel economy has been increased,
and reductions in size and weight have been attained in automatic
transmissions as well. Accordingly, there is a need for automatic
transmission fluids with even better friction characteristics and
even better stability of these friction characteristics, that is, a
reduction in variation in friction characteristics attributable to
long-term use.
[0003] Japanese Laid-Open Patent Application 2003-321695 discloses
an automobile transmission fluid that has a high coefficient of
static friction and that is effective at buffering impacts that
occur during shifting, wherein perbasic calcium sulfonate, a
hydrocarbon-substituted succinimide, and a phosphorous acid ester
compound are added to a lubricating base oil. It can be seen from
the working examples in that an antioxidant is also added to the
automobile transmission fluid that is prepared.
[0004] U.S. Pat. No 5,972,851 discloses a composition containing a
dispersant and a friction modifier and having a total
nitrogen-to-phosphorus weight ratio of approximately 3:1 to
approximately 10:1 as an automobile transmission fluid that has
good resistance to oscillation, high static torque, and superior
resistance to friction.
[0005] With a device that needs lubrication, such as an automatic
transmission or an automobile engine, oil seals or O-rings are used
as sealing members to prevent the lubricating oil from leaking out.
Many different materials have been used for these oil seals and
O-rings, but as automatic transmissions, automobile engines, and
the like have become smaller in recent years as mentioned above,
there is a corresponding tendency for the temperature of the
lubricating oil to rise in these devices, so fluororubbers, which
have excellent heat resistance and also have high resistance to oil
and chemicals, have come to be widely used as the material for oil
seals and O-rings. However, these fluororubbers degrade in a
relatively short time through contact with the nitrogen-containing
dispersants that are generally contained in lubricating oils, and
this is a problem in that the properties of the oil seals and
O-rings end up being diminished within a relatively short time.
[0006] U.S. Pat. No. 4,615,826 and U.S. Pat. No. 4,747,971 disclose
that a reaction product of fluorophosphoric acid and a perbasic
nitrogen-containing dispersant is effective as a
nitrogen-containing dispersant that is less likely to cause
degradation of a fluororubber. Nevertheless, these patents are
primarily aimed at developing an additive to be added to an engine
oil, and therefore do not touch upon the friction characteristics
of a lubricating oil composition to which this additive has been
added.
[0007] U.S. Pat. No. 4,889,646 discloses that a lubricating oil
composition containing a reaction product of a mineral acid such as
sulfuric acid, nitric acid, or hydrochloric acid and a dispersant
such as a viscosity index improver containing an amine dispersant,
a Mannich dispersant, a succinimide dispersant, or a succinate
ester amide dispersant, is effective as an engine lubricating oil
that is unlikely to cause degradation of a fluororubber.
Nevertheless, the invention described in this patent is aimed at
developing an additive to be added to an engine oil, and therefore
does not touch upon the friction characteristics of a lubricating
oil composition to which this additive has been added.
[0008] U.S. Pat. No. 4,940,552 discloses that a reaction product of
a dicarboxylic acid or an anhydride thereof and a dispersant having
perbasic nitrogen is effective as a dispersant that is unlikely to
cause degradation of a fluororubber. Nevertheless, the invention
described in this patent is primarily aimed at developing an
additive to be added to an engine oil, and therefore does not touch
upon the friction characteristics of a lubricating oil composition
to which this additive has been added.
DETAILED DESCRIPTION
[0009] An aspect of the present invention to provide a lubricating
oil composition that can impart satisfactory friction
characteristics, particularly to an automatic transmission, and
which is less likely to cause modification of fluororubber sealing
members. Thus, in part, it is directed to a lubricating oil
composition, produced by adding a phosphorus/nitrogen-containing
ashless dispersant of 0.2 to 8 wt % with a nitrogen to phosphorous
mass ratio of 1.5 to 2.8, a friction modifier of 0.01 to 5 wt %, a
metal-containing detergent of 0.005 to 2 wt %, and an antioxidant
of 0.1 to 5 wt % as additives to a base oil with a lubricating
viscosity (wherein the amounts in which the additives are added are
in percentages with respect to the total weight of the lubricating
oil composition).
[0010] The lubricating oil composition is a lubricating oil
composition that can impart satisfactory friction characteristics
and that is less likely to cause modification of fluororubber
sealing members, so it is particularly useful as an automatic
transmission fluid composition, demonstrating significant
improvement of Viton Seal compatibility. Also, these superior
characteristics are useful as a lubricating oil composition used to
lubricate automobile engines and the like that are equipped with
fluororubber sealing members, and therefore the lubricating oil
composition of the present invention is useful as a lubricating oil
composition in various different applications. Preferred
embodiments of the lubricating oil composition of the present
invention are listed below. [0011] (1) The
phosphorus/nitrogen-containing ashless dispersant is the product of
a reaction between a nitrogen-containing ashless dispersant and
phosphoric acid and/or phosphorous acid. The
phosphorus/nitrogen-containing ashless dispersant is non-borated or
essentially boron free meaning it has been post treated with a
boron component. [0012] (2) The phosphorus/nitrogen-containing
ashless dispersant is the product of a reaction between
polyisobutenylsuccinimide and phosphoric acid and/or phosphorous
acid. [0013] (3) The polyisobutenylsuccinimide is a
polyisobutenylsuccinimide with a bis structure. [0014] (4) The
friction modifier is succinimide [0015] (5) The succinimide is the
product of a reaction between ammonia and an alkenylsuccinic
anhydride in which the alkenyl group is an internal olefin obtained
by the isomerization of an olefinic double bond of a linear alpha
olefin with 10 to 30 carbon atoms. [0016] (6) The friction modifier
is a fatty acid amide. [0017] (7) The fatty acid amide is a
reaction product obtained by a condensation reaction of an amine
and a monovalent fatty acid with 6 to 30 carbon atoms. [0018] (8)
The friction modifier includes succinimide and a fatty acid amide
compound. [0019] (9) The metal-containing detergent is an alkali
metal sulfonate. [0020] (10) The antioxidant is one or more ashless
antioxidants selected from the group consisting of amine compounds
having an antioxidant property, and phenol compounds having an
antioxidant property. [0021] (11) The lubricating oil composition
is used in an automatic transmission.
[0022] Another aspect, is directed to an automatic transmission
lubricating oil composition comprising 0.2 to 8 wt % of a
phosphorolyated polyisobutenyl succinimide having a
nitrogen/phosphorus mass ratio of 1.5 to 2.8 wherein the
polyisobutenyl group has an average molecular weight of 900 to
2300; 0.01 to 5 wt % a friction modifier succinimide derived from
the reaction product of an isomerized C.sub.6 to C.sub.30 alkenyl
succinic anhydride with an amine selected from the group of
ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine,
and tetraethylenepentamine; a metal-containing detergent of 0.005
to 2 wt %; and an antioxidant of 0.1 to 5 wt % as additives to a
base oil with a lubricating viscosity, wherein the amounts in which
the additives are added are in percentages with respect to the
total weight of the lubricating oil composition. The automatic
transmission lubricating oil demonstrates antiwear performance when
the polyisobutenyl succinimide is employed in an amount to provide
greater than about 200 parts per million phosphorous up to about
700 parts per million in the total lubricant. In one aspect, the
automatic transmission lubricant can be essentially free of
supplementary phosphorous containing additives. Many phosphorous
compounds and anti-wear agents such as phosphate and phosphite,
have harmful side effects on frictional properties, such as poor
friction durability and poor anti-shudder durability. In this
regard, another aspect is directed to a method for improving
fluororubber seal compatibility while maintaining stability of the
coefficient of friction as measured according to the JASCO
M315:2004 in an automatic transmission comprising using an
automatic transmission lubricating oil composition described herein
above. Preferably the change in .mu.d (%) is less than 10. [0023]
The base oil and additive components that constitute the
lubricating oil composition of the present invention will now be
described in detail.
Base Oil
[0024] There are no particular restrictions on the base oil in the
lubricating oil composition of the present invention, and any of
the lubricating base oils with various characteristics that have
been used up to now as base oils for automobile engine (and
especially gasoline engine) lubricating oil compositions or in
automatic transmission fluids can be used. For example, Groups 1 to
3 mineral oils, Group 4 synthetic oils, and Group 5 base oils (base
oils not encompassed by Groups 1 to 4) as set forth by ASTM can be
used. It is preferable to use a mineral oil and/or synthetic oil
containing at least 85 wt % (and preferably at least 90 wt %)
saturated components, having a viscosity index of at least 110 (and
preferably at least 120, and even more preferably at least 130),
and having a sulfur content of no more than 0.01 wt % (and
particularly no more than 0.001 wt %).
[0025] A mineral oil-based base oil preferably undergoes a suitable
combination of treatments such as hydrogenation or solvent refining
of a mineral oil-based lubricating oil fraction, and is
particularly favorable to use a highly hydrogenated refined oil
(also called a hydrocracked oil, which is typically an oil with a
viscosity index of at least 120, an evaporation loss (ASTM D8500)
of no more than 15 wt %, a sulfur content of no more than 0.001 wt
%, and an aromatic content of no more than 10 wt %). Alternatively,
a mixed oil containing at least 10 wt % of a hydrocracked oil such
as this can also be used. These hydrocracked oils also encompass
gas-to-liquid (GTL) base oils and oils with a high viscosity index
(such as those with a viscosity index of at least 140, and
particularly 140 to 150) and produced by an isomerization and
hydrocracking process using as a raw material a synthetic wax made
from natural gas or a mineral oil-based slack wax. Hydrocracked
oils are preferable for the object of the present invention from
the standpoints of low sulfur content, low volatility, low residual
carbon content, and so forth.
[0026] Examples of synthetic oils (synthetic lubricating base oils)
include poly-.alpha.-olefins that are C.sub.3 to C.sub.12
.alpha.-olefin polymer; dialkyl diesters that are esters of a
C.sub.4 to C.sub.18 alcohol and a dibasic acid such as sebacic
acid, azelaic acid, and adipic acid, which are typified by dioctyl
sebacate; polyol esters that are esters of a C.sub.3 to C.sub.18
monobasic acid and 1-trimethylolpropane or pentaerythritol; and
alkylbenzenes having a C.sub.9 to C.sub.40 alkyl group. In general,
synthetic oils contain virtually no sulfur, have excellent
oxidation stability and heat resistance, and when combusted produce
little residual carbon or soot, which makes them preferable for the
lubricating oil composition of the present invention.
Poly-.alpha.-olefins are particularly favorable for the purposes of
the present invention. Mineral oil-based base oils and synthetic
base oils can each be used singly, but if desired, a combination of
two more kinds of mineral oil-based base oil or two or more kinds
of synthetic base oil can be used. Also, if desired, a mineral
oil-based base oil and a synthetic base oil can be combined in any
proportions.
[0027] Phosphorus/Nitrogen-Containing Ashless Dispersant with
Nitrogen/Phosphorus Ratio of 1.5 to 2.8
[0028] The phosphorus/nitrogen-containing ashless dispersant with a
nitrogen/phosphorus ratio of 1.5 to 2.8 contained in the
lubricating oil composition of the present invention can be
obtained as a uniform solution by mixing a nitrogen-containing
ashless dispersant (usually containing approximately 60 wt %
nitrogen-containing ashless dispersant (active components or
solids) and approximately 40 wt % diluting mineral oil) and
phosphoric acid or phosphorous acid in a proportion such that the
nitrogen/phosphorus ratio will be from 1.5 to 2.8, and then
stirring this mixture, usually for 0.1 to 5 hours, and usually
between 40 and 200.degree. C. (preferably between 50 and
150.degree. C., and more preferably between 70 and 120.degree.
C.).
[0029] The preferable nitrogen/phosphorus ratio for use in the
lubricating oil composition of the present invention is a range of
1.5 to 2.8, but more preferably the nitrogen/phosphorus ratio is no
more than 2 5, and even more preferably this ratio is no more than
2.3, with a ratio of no more than 2.0 being particularly favorable.
A phosphorus/nitrogen-containing ashless dispersant having a
nitrogen/phosphorus ratio of 3 or higher will not exhibit a
satisfactory effect in terms of suppressing the degradation of
fluororubber.
[0030] Furthermore, the amount in which the
phosphorus/nitrogen-containing ashless dispersant with a
nitrogen/phosphorus ratio of 1.5 to 2.8 is contained in the
lubricating oil composition of the present invention is preferably
between 0.2 and 8 wt %, with a range of 0.5 to 5 wt % being even
better. The amount in which this phosphorus/nitrogen-containing
ashless dispersant is contained in the lubricating oil composition
is preferably between 100 and 700 ppm calculated as total
phosphorus content, with a range of 150 to 400 ppm being even
better, and a range of 250 to 350 ppm being particularly favorable.
In one aspect, the entire phosphorus content in the lubricating oil
composition is derived from the phosphorus/nitrogen-containing
ashless dispersant, thus the lubricating oil composition is
essentially free of other phosphorous containing additives.
[0031] Typical examples of the nitrogen-containing ashless
dispersant include alkenyl or alkyl succinimides derived from
polyolefins, and derivatives thereof A succinimide can be obtained
by a reaction between a succinic anhydride substituted with a high
molecular weight alkenyl or alkyl group, and a
polyalkylenepolyamine containing an average of 3 to 10 (and
preferably 4 to 7) nitrogen atoms per molecule. The high molecular
weight alkenyl or alkyl group is preferably a polyolefin with a
number average molecular weight of approximately 900 to 5000, with
polybutene being particularly favorable.
[0032] In some cases a chlorination method in which chlorine is
used is utilized in the step of obtaining a polybutenyl succinic
anhydride by a reaction between polybutene and maleic anhydride.
With this method, however, although reactivity is good, a large
amount of chlorine (such as about 2000 ppm) ends up remaining in
the final succinimide product. On the other hand, if a thermal
reaction is used in which no chlorine is involved, the amount of
chlorine remaining in the final product can be kept to a very low
level (such as 40 ppm or less). Also, compared to conventional
polybutene (primarily one having a .beta.-olefin structure), using
highly reactive polybutene (one in which at least about 50% has a
methyl vinylidene structure) is advantageous in that reactivity is
increased even with a thermal reaction method. If reactivity is
high, there will be less unreacted polybutene in the dispersant, so
a dispersant with a high concentration of active component
(succinimide) can be obtained. Therefore, it is preferable to
manufacture a succinimide by first obtaining a polybutenyl succinic
anhydride by thermal reaction using highly reactive polybutene, and
then reacting this polybutenyl succinic anhydride with a polyamine.
The succinimide can be used in the form of what is called a
modified succinimide, by further reacting with boric acid, an
alcohol, an aldehyde, a ketone, an alkylphenol, a cyclic carbonate,
an organic acid, or the like. A boron-containing alkenyl (or alkyl)
succinimide obtained by a reaction with boric acid or a boron
compound is particularly advantageous in terms of thermal and
oxidation stability. Succinimides come in mono, bis, and poly
types, according to the number of imide structures per molecule,
but bis types are preferable as the succinimide used for the
purpose of the present invention.
[0033] Other examples of nitrogen-containing ashless dispersants
include polymeric succinimide dispersants derived from an
ethylene-.alpha.-olefin copolymer (such as one with a molecular
weight of 1000 to 15,000), and alkenylbenzylamine-based ashless
dispersants.
[0034] Particularly preferred nitrogen-containing ashless
dispersants are mono and bis alkenyl succinimides derived from the
reaction of alkenyl succinic acid or anhydride and alkylene
polyamines. These compounds are generally considered to have the
formula
##STR00001##
wherein R.sup.1 is a substantially hydrocarbon radical having a
molecular weight from about 450 to 3000, that is, R.sup.1 is a
hydrocarbyl radical, preferably an alkenyl radical, containing
about 30 to about 200 carbon atoms; Alk is an alkylene radical of 2
to 10, preferably 2 to 6, carbon atoms, R.sup.2, R.sup.3, and
R.sup.4 are selected from a C.sub.1-C.sub.4 alkyl or alkoxy or
hydrogen, preferably hydrogen, and x is an integer from 0 to 10,
preferably 0 to 3. The actual reaction product of alkylene or
alkenylene succinic acid or anhydride and alkylene polyamine will
comprise the mixture of compounds including succinamic acids and
succinimides. However, it is customary to designate this reaction
product as a succinimide of the described formula, since this will
be a principal component of the mixture. The mono alkenyl
succinimide and bis alkenyl succinimide produced may depend on the
charge mole ratio of polyamine to succinic groups and the
particular polyamine used. Charge mole ratios of polyamine to
succinic groups of about 1:1 may produce predominately mono alkenyl
succinimide Charge mole ratios of polyamine to succinic group of
about 1:2 may produce predominately bis alkenyl succinimide
[0035] These N-substituted alkenyl succinimides can be prepared by
reacting maleic anhydride with an olefinic hydrocarbon followed by
reacting the resulting alkenyl succinic anhydride with the alkylene
polyamine. The R.sup.1 radical of the above formula, that is, the
alkenyl radical, is preferably derived from a polymer prepared from
an olefin monomer containing from 2 to 5 carbon atoms. Thus, the
alkenyl radical is obtained by polymerizing an olefin containing
from 2 to 5 carbon atoms to form a hydrocarbon having a molecular
weight ranging from about 450 to 3000. Such olefin monomers are
exemplified by ethylene, propylene, 1-butene, 2-butene, isobutene,
and mixtures thereof.
[0036] In a preferred aspect, the alkenyl succinimide may be
prepared by reacting a polyalkylene succinic anhydride with an
alkylene polyamine. The polyalkylene succinic anhydride is the
reaction product of a polyalkylene (preferably polyisobutene) with
maleic anhydride. One can use conventional polyisobutene, or high
methylvinylidene polyisobutene in the preparation of such
polyalkylene succinic anhydrides. One can use thermal,
chlorination, free radical, acid catalyzed, or any other process in
this preparation. Examples of suitable polyalkylene succinic
anhydrides are thermal PIBSA (polyisobutenyl succinic anhydride)
described in U.S. Pat. No. 3,361,673; chlorination PIBSA described
in U.S. Pat. No. 3,172,892; a mixture of thermal and chlorination
PIBSA described in U.S. Pat. No. 3,912,764; high succinic ratio
PIBSA described in U.S. Pat. No. 4,234,435; PolyPIBSA described in
U.S. Pat. Nos. 5,112,507 and 5,175,225; high succinic ratio
PolyPIBSA described in U.S. Pat. Nos. 5,565,528 and 5,616,668; free
radical PIBSA described in U.S. Pat. Nos. 5,286,799, 5,319,030, and
5,625,004; PIBSA made from high methylvinylidene polybutene
described in U.S. Pat. Nos. 4,152,499, 5,137,978, and 5,137,980;
high succinic ratio PIBSA made from high methylvinylidene
polybutene described in European Patent Application Publication No.
EP 355 895; terpolymer PIBSA described in U.S. Pat. No. 5,792,729;
sulfonic acid PIBSA described in U.S. Pat. No. 5,777,025 and
European Patent Application Publication No. EP 542 380; and
purified PIBSA described in U.S. Pat. No. 5,523,417 and European
Patent Application Publication No. EP 602 863. The disclosures of
each of these documents are incorporated herein by reference in
their entirety. The polyalkylene succinic anhydride is preferably a
polyisobutenyl succinic anhydride. In one preferred embodiment, the
polyalkylene succinic anhydride is a polyisobutenyl succinic
anhydride having a number average molecular weight of at least 450,
more preferably at least 900 to about 3000 and still more
preferably from at least about 900 to about 2300.
[0037] In another preferred embodiment, a mixture of polyalkylene
succinic anhydrides are employed. In this embodiment, the mixture
preferably comprises a low molecular weight polyalkylene succinic
anhydride component and a high molecular weight polyalkylene
succinic anhydride component. More preferably, the low molecular
weight component has a number average molecular weight of from
about 450 to below 1000 and the high molecular weight component has
a number average molecular weight of from 1000 to about 3000. Still
more preferably, both the low and high molecular weight components
are polyisobutenyl succinic anhydrides. Alternatively, various
molecular weights polyalkylene succinic anhydride components can be
combined as a dispersant as well as a mixture of the other above
referenced dispersants as identified above.
[0038] The polyalkylene succinic anhydride can also be incorporated
with the detergent which is anticipated to improve stability and
compatibility of the detergent mixture. When employed with the
detergent it can comprise from 0.5 to 5 percent by weight of the
detergent mixture and preferably from about 1.5 to 4 weight
percent.
[0039] The preferred polyalkylene amines used to prepare the
succinimides are of the formula:
##STR00002##
wherein z is an integer of from 0 to 10 and Alk, R.sup.2, R.sup.3,
and R.sup.4 are as defined above. The alkylene amines include
principally methylene amines, ethylene amines, butylene amines,
propylene amines, pentylene amines, hexylene amines, heptylene
amines, octylene amines, other polymethylene amines and also the
cyclic and the higher homologs of such amines as piperazine and
amino alkyl-substituted piperazines They are exemplified
specifically by ethylene diamine, triethylene tetraamine, propylene
diamine, decamethyl diamine, octamethylene diamine,
diheptamethylene triamine, tripropylene tetraamine, tetraethylene
pentamine, trimethylene diamine, pentaethylene hexamine,
ditrimethylene triamine,
2-heptyl-3-(2-aminopropyl)-imidazoline,4-methyl imidazoline,
N,N-dimethyl-1,3-propane diamine, 1,3-bis(2-aminoethyl)imidazoline,
1-(2-aminopropyl)-piperazine, 1,4-bis(2-aminoethyl)piperazine and
2-methyl-1-(2-aminobutyl)piperazine. Higher homologs such as are
obtained by condensing two or more of the above-illustrated
alkylene amines likewise are useful.
[0040] The ethylene amines are especially useful. They are
described in some detail under the heading "Ethylene Amines" in
Encyclopedia of Chemical Technology, Kirk-Othmer, Vol. 5, pp.
898-905 (Interscience Publishers, New York, 1950). The term
"ethylene amine" is used in a generic sense to denote a class of
polyamines conforming for the most part to the structure
H.sub.2N(CH.sub.2CH.sub.2NH).sub.aH
[0041] wherein a is an integer from 1 to 10.
[0042] Thus, it includes, for example, ethylene diamine, diethylene
triamine, triethylene tetraamine, tetraethylene pentamine,
pentaethylene hexamine, and the like. The individual alkenyl
succinimides used in the alkenyl succinimide composition of the
present invention can be prepared by conventional processes, such
as disclosed in U.S. Pat. Nos. 2,992,708; 3,018,250; 3,018,291;
3,024,237; 3,100,673; 3,172,892; 3,202,678; 3,219,666; 3,272,746;
3,361,673; 3,381,022; 3,912,764; 4,234,435; 4,612,132; 4,747,965;
5,112,507; 5,241,003; 5,266,186; 5,286,799; 5,319,030; 5,334,321;
5,356,552; 5,716,912, the disclosures of which are all hereby
incorporated by reference in their entirety for all purposes.
[0043] Thereafter, the succinimide is reacted with a phosphorous
source under suitable reaction conditions to provide a nitrogen to
phosphorus mass ration of 1.5 to 2.8. Examples of inorganic
phosphorous acids include phosphorous acid, hydrophosphoric acid,
phosphorous trioxide, phosphorous tetraoxide and phosphoric
anhydride. Partial or total sulfur analogs, such as
phosphorotetrathioic acid, phosphoromonothioic acid,
phosphorodithioic acid and phosphorotrithioic acid and
P.sub.2S.sub.5 can be used. Particularly preferred is phosphorous
acid. Specific examples of phosphoric acids are othophosphoric acid
and metaphosphoric acid. Suitable procedures are for reacting a
succinimide with a phosphorous source are set forth in U.S. Pat.
Nos. 3,502,677 and 4,857,214, hereby incorporated by reference in
their entirety for all purposes. In one aspect, the ashless
dispersant is prepared by phosphorylating a succinimide, more
particularly a polyisobutenyl succinimide, to such a degree that
the nitrogen to phosphorous mass ratio in the reaction product is
between about 1.5 to about 2.8; more preferably between about 1.5
to about 2.5; even more preferably between about 1.5 to about 2. In
one aspect, the phosphorous/nitrogen containing ashless dispersant
is substantially free of boron and thus, particularly preferred are
phosphorylated polyisobutenyl succinimides substantially free of
boron or non-borated phosphorylated polyisobutenyl
succinimides.
Friction Modifier
[0044] A variety of known friction modifiers can be used as the
friction modifier contained in the lubricating oil composition of
the present invention, but a low molecular weight C.sub.6 to
C.sub.30 hydrocarbon-substituted succinimide or a fatty acid amide
is preferable. The friction modifier can be used singly or as a
combination. The friction modifier is preferably contained in an
amount of 0.01 to 5 wt % in the lubricating oil composition, and a
range of 0.5 to 3 wt % is particularly favorable.
[0045] C.sub.6 to C.sub.30 Hydrocarbon-Substituted Succinimide
[0046] The friction modifying succinimide can be obtained by a
reaction between ammonia or urea and a C.sub.6 to C.sub.30
hydrocarbon-substituted succinic acid or anhydride thereof The
hydrocarbon-substituted succinic acid or anhydride thereof
preferably has a C.sub.6 to C.sub.30 straight chain or branched
chain alkyl or alkenyl group as a substituent. This
hydrocarbon-substituted succinic acid can be obtained by a reaction
between maleic anhydride and an olefin corresponding to the
hydrocarbon substituent. A preferable olefin is a linear olefin
with 10 to 30 carbon atoms, or an internal olefin obtained by
isomerization of the double bonds of this olefin.
[0047] Particularly preferred succinimides are derived from
isomerized alkenyl succinic anhydrides or their fully saturated
alkyl analogs, suitable preparation methods are described in, for
example U.S. Pat. No. 3,382,172. Commonly these materials are
prepared by heating alpha-olefins with acidic catalysts to migrate
the double bond to an internal position. This mixture of olefins
(2-enes, 3-enes, etc.) is then thermally reacted with maleic
anhydride. Typically olefins from C.sub.6 (1-hexene) to C.sub.30
(1-triacontene) are used. Suitable isomerized alkenyl succinic
anhydrides include iso-decylsuccinic anhydride, iso-dodecylsuccinic
anhydride, iso-tetradecylsuccnic anhydride, iso-hexadecylsuccinic
anhydride, iso-octadecylsuccinic anhydride and iso-eicosylsuccinic
anhydride. Preferred materials are iso-hexadecylsuccinic anhydride
and iso-octadecylsuccinic anhydride. In another aspect, a C.sub.6
to C.sub.18 isomerized olefin is particularly favorable. The
materials produced by this process contain one double bond (alkenyl
group) in the alkyl chain. The alkenyl substituted succinic
anhydrides may be easily converted to their saturated alkyl analogs
by hydrogenation. The isomerized C.sub.6 to C.sub.30 alkenyl
succinic anhydrides (or The isomerized C.sub.6 to C.sub.30
saturated-alkyl succinic anhydrides) can be reacted with amines to
form the succinimide(s). Particularly preferred amines are ammonia,
in another aspect the amine is a polyamine such as an ethylene
amine Non-limiting examples include ethylenediamine,
diethylenetriamine, triethylenetetramine, and
tetraethylenepentamine and pentaethylene hexamine.
[0048] Other examples of favorable succinimides include a C.sub.6
to C.sub.12 straight chain hydrocarbon-substituted succinic acid or
an anhydride thereof and a hydrocarbon-substituted succinic acid
polyalkylenepolyaminoimide obtained by reacting a
polyalkylenepolyamine in a molar ratio of (1.0 to 1.75):(0.25 to
1.0):1.0. Examples of polyalkylenepolyamines include
ethylenediamine, diethylenetriamine, triethylenetetramine, and
tetraethylenepentamine.
[0049] (2) Fatty Acid Amides
[0050] A fatty acid amide can be obtained by condensation between a
C.sub.6 to C.sub.30 monovalent fatty acid and an amine The
monovalent fatty acid is preferably a straight chain or branched
chain, saturated or unsaturated monovalent fatty acid with 8 to 22
carbon atoms. Specific examples include octylic acid, lauric acid,
myristic acid, palmitic acid, stearic acid, isostearic acid, oleic
acid, and behenic acid. The amine can be a primary amine, secondary
amine, ammonia, or polyalkylenepolyamine. The primary amine is
preferably a C.sub.8 to C.sub.22 primary amine, specific examples
of which include octylamine, decylamine, dodecylamine,
tetradecylamine, hexadecylamine, octadecylamine, and oleylamine
Specific examples of secondary amines include dioctylamine,
didodecylamine, dioctadecylamine, and dioleylamine. Specific
examples of polyalkylenepolyamines include ethylenediamine,
diethylenetriamine, triethylenetetramine, and
tetraethylenepentamine. Examples of particularly favorable fatty
acid amides include an oleylamide obtained by a reaction between
oleic acid and ammonia, and an amide compound obtained by
condensation between 2 to 4 mol of isostearic acid and 1 mol of
tetraethylenepentamine. This amide compound can also be used in
combination with imidazoline.
Metal-Containing Detergent
[0051] There are no particular restrictions on the metal-containing
detergent used in the lubricating oil composition of the present
invention, but it is preferable to use a salt of an
alkyltoluenesulfonic acid, alkylbenzenesulfonic acid, or petroleum
sulfonic acid with a total base number of 10 to 500 mgKOH/g and an
alkali metal (such as lithium) or alkaline earth metal (such as
magnesium or calcium), or a perbasic compound thereof The
metal-containing detergent can be used singly or in
combination.
[0052] Also, an alkyl salicylate, alkyl carboxylate, and/or phenate
of an alkali metal or alkaline earth metal can be used either
singly or in combination with one of the above-mentioned
sulfonates.
Antioxidant
[0053] It is preferable for the antioxidant to be at least one kind
selected from the group consisting of phenol-based antioxidants and
amine-based antioxidants known in the past. The antioxidant is
preferably contained in the lubricating oil composition in an
amount of 0.1 to 5 wt % (and particularly 0.5 to 3 wt %).
[0054] A hindered phenol compound is generally used as the
phenol-based antioxidant, and a diarylamine compound is generally
used as the amine-based antioxidant. Specific examples of hindered
phenol antioxidants include 2,6-di-t-butyl-p-cresol,
4,4'-methylenebis(2,6-di-t-butylphenol),
4,4'-methylenebis(6-t-butyl-o-cresol),
4,4'-isopropylidenebis(2,6-di-t-butylphenol),
4,4'-bis(2,6-di-t-butylphenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol),
4,4'-thiobis(2-methyl-6-t-butylphenol),
2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],
octyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, octadecyl
3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and octyl
3-(5-t-butyl-4-hydroxy-3-methylphenyl)propionate. Specific examples
of diarylamine antioxidants include C.sub.4 to C.sub.9 mixed
alkyldiphenylamines, p,p'-dioctyidiphenylamine,
phenyl-.alpha.-naphthylamine, phenyl-.beta.-naphthylamine,
alkylated .alpha.-naphthylamines, and alkylated
phenyl-.alpha.-naphthylamines. The hindered phenol antioxidants and
diarylamine antioxidants can each be employed singly, or can be
combined as desired. Other oil-soluble antioxidants may also be
used together with these.
[0055] The lubricating oil composition of the present invention can
further contain any of various known lubricating oil additives.
Examples of these known lubricating oil additives include viscosity
index improvers (such as dispersive and non-dispersive viscosity
index improvers), corrosion inhibitors (such as thiazole compounds,
triazole compounds, thiadiazole compounds, and other such copper
corrosion inhibitors), antiwear agents (such as phosphoric esters,
amine salts of phosphoric esters, phosphorous esters, amine salts
of phosphorous esters, and thiophosphoric esters), seal expanders
(such as oil-soluble dialkyl esters of adipic acid, azelaic acid,
sebacic acid, phthalic acid, and other such dibasic acids), dyes
(such as red dyes), antifoaming agents, and pour point depressants
(such as polymethacrylic esters, polyacrylic esters, and
polyacrylamides).
Working Examples
Synthesis Example 1
Synthesis of Phosphorus/Nitrogen-Containing Ashless Dispersant
(Dispersant A)
[0056] 200 g of bis-type polyisobutenyl (PIB) succinimide (a
solution containing approximately 40 wt % mineral oil; nitrogen
content of solution: 2.0 wt %; number average molecular weight of
PIB: approximately 1000, amine being a heavy polyamine comprising a
mixture of largely tetraethylenepentamine and triethylenetetramine)
was mixed with 5.3 g of phosphorous acid (phosphorus: 37.8 wt %).
The mixture was stirred while the temperature was raised to
100.degree. C., then held for 1 hour at this temperature, which
gave a Dispersant A as the reaction product. This Dispersant A had
a nitrogen content of 1.96 wt %, a phosphorus content of 0.97 wt %,
and a nitrogen/phosphorus mass ratio of 2.0.
Synthesis Examples 2 to 7
Synthesis of Phosphorus/Nitrogen-Containing Ashless Dispersants
(Dispersants B to G)
[0057] Using 200 g of the same bis-type polyisobutenyl (PIB)
succinimide (a solution containing approximately 40 wt % mineral
oil) as that used in Synthesis Example 1, Dispersants 2 to 7 were
obtained by the same procedure as in Synthesis Example 1, except
for using phosphorous acid in the amounts listed in Table 1. Table
1 also lists the nitrogen and phosphorus contents, and their
content ratios, for Dispersants B to G thus obtained.
TABLE-US-00001 TABLE 1 Succinimide Phosphorous acid Reaction
product amount used amount used Dispersant N (%) P (%) N/P
Synthesis Example 1 200 g 5.3 g A 1.96 0.97 2.0 Synthesis Example 2
200 g 4.6 g B 1.96 0.85 2.3 Synthesis Example 3 200 g 4.3 g C 1.97
0.79 2.5 Synthesis Example 4 200 g 3.55 g D 1.98 0.66 3.0 Synthesis
Example 5 200 g 2.95 g E 1.98 0.55 3.6 Synthesis Example 6 200 g
2.7 g F 1.98 0.5 4.0 Synthesis Example 7 200 g 1.1 g G 2.0 0.2
10.0
Synthesis Example 8
Synthesis of Friction Modifier (FM-1)
[0058] 1000 g (2.84 mol) of isomerized octadecenyl succinic
anhydride was put into a four-neck flask equipped with a stirrer, a
thermometer, and a dehydrator, the inside of the flask was replaced
with nitrogen while the contents were stirred, and the temperature
was raised to 130.degree. C. Ammonia was then poured in, the
temperature was raised to 180.degree. C., and ammonia was added for
6.5 hours until no more heat was generated. After this, the
pressure was reduced to 50 Torr, and dehydration was performed for
1 hour. 995 g of a light brown, viscous liquid (nitrogen content of
3.85 wt %) was finally obtained as the reaction product (FM-1).
Synthesis Example 9
Synthesis of Friction Modifier (FM-2)
[0059] 68.3 g (0.323 mol) of isomerized n-octenyl succinic
anhydride and 130 g (0.107 mol) of polyisobutenyl-substituted
succinic anhydride with a molecular weight of 1000 were put into a
four-neck flask equipped with a stirrer, a thermometer, and a
dehydrator, and the atmosphere was replaced with nitrogen while the
temperature was raised to 90.degree. C. 22.05 g (0.215 mol) of
diethylenetriamine was then added dropwise. Upon completion of the
dropping, the mixture was heated to 160.degree. C., and the water
that was produced was removed while the mixture was heated and
stirred for 2 hours. After this, the reaction product was
dehydrated for 1 hour at a temperature of 160.degree. C. and a
reduced pressure of 50 Torr. A light brown, viscous liquid
(nitrogen content of 4.3 wt %) was finally obtained as the reaction
product (FM-2).
Synthesis Example 10
Synthesis of Friction Modifier (FM-3)
[0060] 180 g (0.61 mol) of isostearic acid was put into a four-neck
flask equipped with a stirrer, a thermometer, and a dehydrator, and
the atmosphere was replaced with nitrogen while the temperature was
raised to 90.degree. C. 36.7 g (0.194 mol) of
tetraethylenepentamine was then added dropwise. Upon completion of
the dropping, the mixture was heated to 213.degree. C. over a
period of 3 hours, and the reaction product was dehydrated for 5
hours at the same temperature and a reduced pressure of 50 Torr. A
brown, viscous liquid (nitrogen content of 6.4 wt %) was finally
obtained as the reaction product (FM-3).
Working Examples 1 to 4 and Comparative Examples 1 to 4
Manufacture of Lubricating Oil Composition
[0061] A phosphorus/nitrogen-containing ashless dispersant, a
friction modifier, a metal-containing detergent, an antioxidant, a
corrosion inhibitor, a viscosity index improver, and an antifoaming
agent were added in the following amounts to a specific base oil to
prepare lubricating oil compositions.
[0062] (1) Base Oil
[0063] A mixture of 42.69 weight parts of a base oil with a
100.degree. C. kinematic viscosity of 3.5 mm.sup.2/s (belonging to
Group 3) and 42.69 weight parts of a base oil with a 100.degree. C.
kinematic viscosity of 4.0 mm.sup.2/s (also belonging to Group
3).
[0064] (2) Phosphorus/Nitrogen-Containing Ashless Dispersant
[0065] 3.0 weight parts (added amount of solution containing
approximately 40% mineral oil) of the
phosphorus/nitrogen-containing ashless dispersant listed in Table 2
(one of the Dispersants A to G synthesized in the synthesis
examples given above).
[0066] (3) Friction Modifier
[0067] A mixture of 2.0 weight parts of the FM-1 or FM-2 listed in
Table 2, and 0.25 weight part of FM-3.
[0068] (4) Metal-Containing Detergent 0.1 weight part (added amount
of solution containing approximately 40% mineral oil) of perbasic
calcium sulfonate with a total base number (TBN) of 315
mgKOH/g.
[0069] (5) Antioxidant
[0070] A mixture of 0.5 weight part of an amine-based antioxidant
(an alkyldiphenylamine) and 0.5 weight part of a phenol-based
antioxidant (a hindered phenol mixture).
[0071] (6) Corrosion Inhibitor
[0072] 0.07 weight part of a thiazole corrosion inhibitor (an
alkylthiadiazole).
[0073] (7) Viscosity Index Improver
[0074] 8.20 weight part of non-dispersive polymethacrylate-based
viscosity index improver.
[0075] (8) Antifoaming Agent
[0076] Silicone oil.
Evaluation of Lubricating Oil Composition
[0077] (1) Fluororubber Compatibility Test
[0078] F585, which is a standard material for a rotary oil seal
made by NOK, was used as the fluororubber material. The test was
conducted according to the method in JASO M344-92, in which a
fluororubber piece was soaked for 72 hours at 150.degree. C. in a
lubricating oil composition, after which the change in elongation
and the change in tensile strength were measured.
[0079] (2) Shell Four-Ball Wear Test
[0080] Using a Shell four-ball tester, the wear resistance was
evaluated under test conditions comprising a load of 392 N, a
rotational speed of 1200 rpm, a test oil temperature of 70.degree.
C., and a test duration of 1 hour. Wear resistance was evaluated by
measuring the diameter of wear marks in the balls at the end of the
test.
[0081] Evaluation Results for Lubricating Oil Composition
[0082] The results are given in Table 2 below.
TABLE-US-00002 TABLE 2 Working Example Comparative Example 1 2 3 4
1 2 3 4 Phosphorus/nitrogen-containing ashless dispersant A A B C D
E F G N/P ratio 2.0 2.0 2.3 2.5 3.0 3.6 4.0 10.0 Friction modifier
(FM-) 1 + 3 2 + 3 1 + 3 1 + 3 1 + 3 1 + 3 1 + 3 1 + 3 Fluororubber
immersion test results Change in elongation (%) -9.5 -9.5 -11.6
-12.5 -16.1 -19.7 -20.1 -19.6 Change in tensile strength (%) -5.0
-5.0 -7.6 -9.2 -11.6 -14.8 -15.7 -18.3 Shell four-ball wear test
results: wear mark diameter (mm) 0.48 0.46 0.49 0.53 0.58 0.70 --
--
[0083] As reference examples, the fluororubber immersion test and
the Shell four-ball wear test were also conducted on two kinds of
commercially available automatic transmission fluid. As a result,
with one of the commercially available automatic transmission
fluids, the change in elongation was -12.4%, the change in tensile
strength was -7.7%, and the wear mark diameter was 0.53 mm, and
with the other commercially available automatic transmission fluid,
the change in elongation was -4.5%, the change in tensile strength
was -13.8%, and the wear mark diameter was 0.56 mm.
[0084] This confirms that the lubricating oil composition of the
present invention makes it less likely that a fluororubber seal
will deteriorate than with a lubricating oil composition containing
a phosphorus/nitrogen-containing ashless dispersant with a
nitrogen/phosphorus ratio of 3.0 or higher, and also contributes to
improvement of the wear resistance of the machinery.
Working Example 5 and Comparative Examples 5 and 6
[0085] Manufacture of Lubricating Oil Composition
[0086] A combination of a phosphorus/nitrogen-containing ashless
dispersant (3.0 weight parts of Dispersant A (an amount including
approximately 40 wt % mineral oil)) or a nitrogen-containing
ashless dispersant containing no phosphorus (3 weight parts (an
amount including approximately 40 wt % mineral oil)) and a
phosphorus-based friction modifier (0.18 weight part of butyl acid
phosphate or dibutyl hydrogenphosphate), an organic friction
modifier (FM-3: 2.0 weight parts), a metal-containing detergent
(0.1 weight part of the calcium sulfonate used in Working Example 1
(an amount including approximately 40 wt % mineral oil)), an
antioxidant (a combination of 0.5 weight part of the amine-based
antioxidant and 0.5 weight part of the phenol-based antioxidant
used in Working Example 1), a corrosion inhibitor 0.07 weight part
of the thiadiazole-based inhibitor used in Working Example 1, a
viscosity index improver (8.20 weight parts of the
polymethacrylate-based non-dispersive viscosity index improver used
in Working Example 1), and an antifoaming agent (0.002 weight part
of the silicone oil used in Working Example 1) were added to the
same base oil as that used in Working Example 1 (total: 85.38
weight parts) to prepare a lubricating oil composition.
[0087] Evaluation of Friction Stability of Lubricating Oil
Composition
[0088] The stability of the coefficient of friction was measured
according to the JASO M315:2004 automatic transmission fluid
standards, in which the change (50 to 5000 cycles) in type 1 and
type 2 dynamic friction coefficient (.mu.d) is specified as 10% or
less.
[0089] The measurement of pd by the following test was conducted by
a dynamic friction test method using an SAE No. 2 tester, as set
forth in the JASO M348:2002 automatic transmission fluid friction
test method. The change in pd was calculated from the following
equation, and was rounded off to the nearest integer.
Change in .mu.d (%)=(maximum value-minimum value)-(maximum
value).times.100
[0090] Note: The maximum and minimum values are the maximum and
minimum values between 50 and 5000 cycles.
[0091] The JASO M348:2002 automatic transmission fluid friction
test method is summarized below:
[0092] (1) Friction Materials
[0093] Friction material: FZ127-24-Y12, steel plate: FZ132-8Y2
[0094] (2) Dynamic Friction Test Conditions
[0095] Inertial moment of inertial disk: 0.343 kgm.sup.2, oil
temperature: 100.degree. C.
[0096] (3) Recording of Dynamic Friction Coefficient
[0097] Test cycles: The dynamic friction coefficient (0) was
recorded after 1, 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 3000,
4000, and 5000 cycles.
[0098] Table 3 shows the results of evaluating friction
stability.
TABLE-US-00003 TABLE 3 Working Comparative Comparative Example 5
Example 5 Example 6 Dispersant Dispersant A phosphorus-free
dispersant Phosphorus-based -- phosphate phosphate friction
modifier N/P ratio 2.0 2.0 2.0 Friction stability Maximum value of
.mu.d 0.148 0.158 0.168 Minimum value of .mu.d 0.137 0.138 0.142
Change in .mu.d 7% 13% 26%
[0099] The lubricating oil composition pertaining to Working
Example 5 of the present invention exhibited high stability of its
dynamic friction coefficient (.mu.d).
* * * * *