U.S. patent application number 09/813379 was filed with the patent office on 2001-11-22 for lubricant compositions for transmissions.
This patent application is currently assigned to Nippon Mitsubishi Oil Corporation. Invention is credited to Komiya, Kenichi, Kurosawa, Osamu, Yaguchi, Akira.
Application Number | 20010044389 09/813379 |
Document ID | / |
Family ID | 18595046 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010044389 |
Kind Code |
A1 |
Komiya, Kenichi ; et
al. |
November 22, 2001 |
Lubricant compositions for transmissions
Abstract
Transmission lubricant compositions comprise a mineral oil as a
base oil of which % CP and % CA defined in ASTM D 3238 are 70 or
more and 3 or less, respectively, a viscosity index improver, and a
friction modifier. The transmission lubricant compositions have
excellent low temperature fluidity, shear stability, and durability
of anti-shudder properties and thus can be used for extended
periods of time.
Inventors: |
Komiya, Kenichi;
(Yokohama-shi, JP) ; Yaguchi, Akira;
(Yokohama-shi, JP) ; Kurosawa, Osamu;
(Yokohama-shi, JP) |
Correspondence
Address: |
AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103
US
|
Assignee: |
Nippon Mitsubishi Oil
Corporation
|
Family ID: |
18595046 |
Appl. No.: |
09/813379 |
Filed: |
March 21, 2001 |
Current U.S.
Class: |
508/284 ; 208/18;
508/466; 508/469; 508/558; 508/562 |
Current CPC
Class: |
C10M 2223/049 20130101;
C10M 2209/084 20130101; C10M 2215/04 20130101; C10M 2207/026
20130101; C10M 169/044 20130101; C10M 2219/046 20130101; C10M
2215/042 20130101; C10N 2030/06 20130101; C10M 2215/223 20130101;
C10N 2010/04 20130101; C10M 2215/064 20130101; C10N 2030/02
20130101; C10N 2030/68 20200501; C10N 2040/042 20200501; C10N
2060/14 20130101; C10M 2215/28 20130101 |
Class at
Publication: |
508/284 ;
508/558; 508/562; 508/466; 508/469; 208/18 |
International
Class: |
C10M 11/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2000 |
JP |
2000-077487 |
Claims
What is claimed is:
1. A transmission lubricant composition which comprises a mineral
oil as a base oil of which % CP and % C.sub.A defined in ASTM D
3238 are 70 or more and 3 or less, respectively, a viscosity index
improver, and a friction modifier.
2. The transmission lubricant composition according to claim 1
wherein said viscosity index improver is selected from the group
consisting of various polymethacrylates.
3. The transmission lubricant composition according to claim 2
wherein said polymethacrylates have a weight-average molecular
weight of 10,000 to 200,000.
4. The transmission lubricant composition according to claim 1
wherein said mineral oil has a kinematic viscosity at 100.degree.
C. of 1 to 10 mm.sup.2/s.
5. The transmission lubricant composition according to claim 1
wherein said viscosity index improver is selected from the group
consisting of dispersion type viscosity index improvers.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to lubricant compositions for
transmissions, and more particularly to lubricant compositions
which are free from a reduction in anti-shudder properties even
after prolonged use. The lubricant compositions are particularly
useful for automatic transmissions and continuously variable
transmissions.
[0003] 2. Description of the Prior Art
[0004] In recent years, with the objective of the cost reduction of
oil changes and the reduction of the amount of waste oil, a demand
has arisen for transmission lubricant compositions which have long
duration of life and can maintain their properties even after the
long-time use.
[0005] In addition to automatic transmissions, most of continuously
variable transmissions are equipped with a torque converter.
Recently, lock-up clutches have been built in torque converters as
effective means to improve mileage such that in addition to power
transmission via lubricant, the engine torque is directly
transmitted to the transmission. However, a torque converter clutch
works only in a high-speed range where the engine torque
fluctuations are less when the torque converter works in a
low-speed range, the engine torque fluctuations bring about
abnormal vibration of the car body, leading to unpleasant driving
conditions. As a result, in the low-speed range, e.g., during the
starting period, power transmission loss occurs, caused by a
difference between the input and output revolutions, i.e., engine
output and transmission input, leading to a decrease in gas
mileage.
[0006] In order to decrease such power transmission loss, a slip
control mechanism is used in some automobiles in which the torque
converter works at a low speed range and the engine torque
fluctuation is absorbed by the relative slip of the clutch.
However, in such a case, there is a possibility that abnormal
vibration of the car body, so-called shudder occurs at the torque
converter clutch's surface, resulting in uncomfortable riding
conditions. In order to prevent the occurrence of shudder, the
lubricant is required to have improved .mu. (friction
coefficient)-V(sliding velocity) properties such that the friction
coefficient is increases as sliding velocity increases. The use of
friction modifiers is effective to improve the .mu.-V properties
and thus many friction modifiers have been proposed. However, there
has not been obtained a satisfactory result with regard to
long-lasting anti-shudder properties.
[0007] The transmission lubricants must maintain proper viscosity
to lubricate a gear shaft bearing mechanism and particularly those
used in a transmission having a hydraulic controlling mechanism are
required to maintain proper viscosity so as to prevent it from
leaking from the control valve. Furthermore, the transmission
lubricant are required to be less in viscosity reduction even after
the use for extended periods of time. In addition to this, the
transmission lubricants are also required to have an excellent low
temperature fluidity because the increase of its resistance to
stirring under cold conditions invite the decrease of gas mileage
and therefore, viscosity at low temperatures are importantly needed
to be suppress low.
[0008] In view of the foregoing circumstances, there has been a
great deal of need to develop a lubricant for transmissions which
has in addition to long-lasting anti-shudder properties excellent
low temperature fluidity and shear stability.
[0009] It is an object of the present invention to provide
transmission lubricant compositions which have and maintains
excellent shear stability and anti-shudder properties for extended
periods of time without being degraded.
SUMMARY OF THE INVENTION
[0010] According to the present invention, there is provided a
transmission lubricant composition comprising a mineral oil as a
base oil hereinafter referred to as Component (A) of which %
C.sub.p and % C.sub.A defined by ASTM D3238 are 70 or more and 3 or
less, respectively, as a main component, a viscosity-index improver
hereinafter referred to as Component (B), and a friction modifier
hereinafter referred to as Component (C).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] The present invention is described below in more
details.
[0012] A mineral oil having a % C.sub.p of 70 or more and a %
C.sub.A of 3 or less both of which are defined by ASTM D 3238, are
used as Component (A) in the present invention.
[0013] Since Component (A) fulfills the conditions of %
C.sub.P.gtoreq.70 and % C.sub.A.ltoreq.3, the composition of the
present invention exhibits excellent low temperature fluidity and
long lasting anti-shudder properties synergistically with
Components (B) and (C).
[0014] No particular limitation is imposed on the kinematic
viscosity of Component (A). However, Component (A) has a kinematic
viscosity of from 1 to 10 mm.sup.2/s, particularly preferably from
1 to 4 mm.sup.2/s. The use of a mineral base oil having a kinematic
viscosity at 100.degree. C. of 1.0 mm.sup.2/S or more can form oil
film and provide lubricity for the lubricant composition and
moreover can reduce the evaporation loss of the base oil at
elevated temperatures. The use of a mineral base oil having a
kinematic viscosity at 100.degree. C. of 10 mm.sup.2/S or less can
reduce the flow resistance of itself, resulting in a lubricant
composition having a lower friction resistance at friction parts.
The use of a mineral base oil having a kinematic viscosity at
100.degree. C. of 4 mm.sup.2/S or less can further enhance the low
temperature fluidity of the resulting lubricant composition.
[0015] No particular limitation is imposed on the viscosity index
of Component (A) as well. However, the viscosity index of Component
(A) is preferably 50 or more and particularly preferably 80 or
more. The use of a base oil having a viscosity index of 50 or more
is contributive to the production of a lubricant composition which
are further superior in the capabilities of both oil film formation
and flow resistance reduction.
[0016] Mineral oils used as Component (A) may be produced any
suitable method. For example, mineral oils which may be used
include paraffinic- and naphthenic- mineral oils which are produced
by subjecting lubricant fractions resulting from the atmospheric
distillation and vacuum distillation of crude oil to refining
processes such as solvent deasphalting, solvent extraction,
hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining,
sulfuric acid washing, and clay treatment in suitable combination;
and n-paraffinic mineral oils.
[0017] More specifically, mineral base oils can be obtained by
refining the starting oil as it is or the lubricant fractions
recovered therefrom through the usual refining processes and then
recovering the lubricant fractions. The starting oil may be (i)
distillate oils resulting from the atmospheric distillation of a
paraffin based crude oil and/or of a mixed base crude oil; (ii)
distillate oils resulting from the vacuum distillation of the
topped crude of a paraffin based crude oil and/or of a mixed base
crude oil; (iii) oils resulting from mild hydrocracking of oils (i)
and/or (ii); (iv) mixed oils of two or more selected from oils (i),
(ii), and (iii); (v) deasphalted oils of oils (i) to (iv), (vi)
oils resulting from mild hydrocracking of oils (v); and (vii) mixed
oils of two or more selected from oils (i) to (vi).
[0018] There is no restriction to the usual refining processes
mentioned above which may be any of the refining methods used upon
production of lubricant base oils. Specific examples of such
refining methods are (a) hydro-refining such as hydrocracking and
hydro-finishing; (b) solvent refining such as furfral extraction;
(c) dewaxing such as solvent dewaxing and catalytic dewaxing; (d)
clay treatment with acid clay or active clay; and (e) acid or
alkali chemical refining such as sulfuric acid washing and caustic
soda washing. In the production of the lubricant composition of the
present invention, the above-described methods may be used
individually or in combination in any order. Needless to mention,
the refining condition of each of the refining methods, i.e., the
temperature and pressure in the hydro-refining is suitably selected
such that a mineral oil having the desired properties can be
obtained.
[0019] The mineral oils which may be used as Component (A) of the
present invention can be easily obtained by utilizing preferably 50
percent by mass or more, more preferably 70 percent by mass or
more, particularly preferably 80 percent by mass or, based on the
total mass of the base oil, of a component produced by
hydrocracking the starting oil selected from the oils (i) to (vii)
as it is or the lubricant fraction recovered therefrom; solvent- or
catalytic dewaxing the resulting product as it is or the lubricant
fraction recovered therefrom; and solvent-refining the resulting
product or such as solvent- or solvent- or catalytic dewaxing the
resulting product after the solvent-refining.
[0020] Component (A) may be a mixture of two or more kinds of
refined mineral oils obtained by any of the above-described
refining processes or a single refined mineral oil by the same.
However, in any case, the mineral oils used as Component (A) of the
present invention must fulfils the conditions of %
C.sub.P.gtoreq.70 and % C.sub.A.ltoreq.3. In other words, as long
as they fulfils such conditions, any kind of mineral oils can be
used as Component (A). Therefore, the mineral oils which may be
used as Component (A) may contain small amounts of synthetic oils
such as poly-.alpha.-olefins and ester-based synthetic oils.
[0021] Eligible viscosity index improvers, i.e., Component (B) of
the present invention are non-dispersion type and dispersion type
viscosity index improvers.
[0022] Specific examples of the non-dispersion type- viscosity
index improvers are polymers or copolymers obtained by polymerizing
one or more monomers represented by formulae (1), (2) and (3)
below, and hydrides of these polymers: 1
[0023] Specific examples of the dispersion type-viscosity index
improvers are copolymers of two or more monomers selected from the
group consisting of compounds represented by formulae (4) and (5)
below and hydrides thereof and copolymers of one or more monomers
selected from the group consisting of compounds represented by
formulae (1), (2) and (3) above with one or more monomers selected
from the group consisting of compounds represented by formulae (4)
and (5) below and hydrides thereof 2
[0024] In formula (1), R.sup.1 is hydrogen or methyl, and R.sup.2
is an alkyl group having 1 to 18 carbon atoms.
[0025] Specific examples of the alkyl group having 1 to 18 carbon
atoms for R.sup.2 are alkyl groups, which may be straight-chain or
branched, such as methyl, ethyl, propyl, butyl, pentyl, hexyl,
heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,
tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl
groups.
[0026] In formula (2), R.sup.3 is hydrogen or methyl, and R.sup.4
is a hydrocarbon group having 1 to 12 carbon atoms.
[0027] Specific examples of the hydrocarbon group having 1 to 12
carbon atoms are alkyl groups, which may be straight-chain or
branched, such as methyl, ethyl, propyl, butyl, pentyl, hexyl,
heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; alkenyl
groups, which may be straight-chain or branched and the position of
which the double bond may vary, such as butenyl, pentenyl, hexenyl,
heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl
groups; cycloalkyl groups having 5 to 7 carbon atoms, such as
cyclopentyl, cyclohexyl, and cycloheptyl groups; alkylcycloalkyl
groups, of which the alkyl group may bonded to any position of the
cycloalkyl group, having 6 to 11 carbon atoms, such as
methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl,
diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl,
methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl,
dimethylcycloheptyl, methylethylcycloheptyl, and diethylcycloheptyl
groups; aryl groups such as phenyl and naphtyl groups; alkylaryl
groups, of which the alkyl group may be straight-chain or branched
and bond to any position of the aryl group, having 7 to 12 carbon
groups, such as tolyl, xylyl, ethylphenyl, propylphenyl,
butylphenyl, pentylphenyl, and hexylphenyl groups; and phenylalkyl
groups, of which the alkyl group may be straight-chain or branched,
having 7 to 12 carbon atoms, such as benzyl, phenylethyl,
phenylpropyl, phneylbutyl, phenylpentyl, and phenylhexyl
groups.
[0028] In formula (3), D.sup.1 and D.sup.2 are each independently
hydrogen, a residue of an alkylalcohol having 1 to 18 carbon atoms
represented by the formula --OR.sup.5 wherein R.sup.5is an alkyl
group having 1 to 18 carbon atoms, or a residue of a monoalkylamine
having 1 to 18 carbon atoms represented by the formula--NHR.sup.6
wherein R.sup.6 is an alkyl group having 1 to 18 carbon atoms.
[0029] Specific examples of the alkyl group for R.sup.5 and R.sup.6
are the same as those exemplified with regard to R.sup.2 in formula
(1).
[0030] Among the monomers of formulae (1), (2), and (3), preferred
are alkylacrylates and alkylmethacrylates of formula (1); olefins
of formula (2) wherein R.sup.3is hydrogen or methyl, and R.sup.4is
an alkyl group having 1 to 12 carbon atoms; styrene of formula (2)
wherein R.sup.3 is hydrogen, and R.sup.4 is phenyl;
.alpha.-methylstyrene of formula (2) wherein R.sup.3 is methyl, and
R.sup.4 is phenyl; p-methylstyrene of formula (2) wherein R.sup.3is
hydrogen, and R.sup.4is tolyl; maleates of formula (3) wherein
D.sup.1 and D.sup.2 are --OR.sup.5 wherein R.sup.5is alkyl; and
maleic amides of formula (3) wherein D.sup.1 and D.sup.2 are
--NHR.sup.6 wherein R.sup.6 is alkyl.
[0031] In formula (4), R.sup.7 is hydrogen or methyl, R.sup.8 is an
alkylene group having 1 to 18 carbon atoms, E.sup.1 is an amine
residue or heterocyclic residue having 1 or 2 nitrogen and 0 to 2
oxygen, and a is an integer of 0 or 1.
[0032] Specific examples of the alkylene group having 1 to 18
carbon atoms for R.sup.8 are ethylene, propylene, butylene,
pentylene, hexylene, heptylene, octylene, nonylene, decylene,
undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene,
hexadecylene, heptadecylene, and octadecylene groups, all of which
may be straight-chain or branched.
[0033] Specific examples of the amine residue for E.sup.1 are
dimethylamino, diethylamino, dipropylamino, dibutylamino, anilino,
toluidino, xylidino, acetylamino, and benzoilamino. Specific
examples of the heterocyclic residue are morpholino, pyrolyl,
pyridyl, methylpydidyl, pyrolidinyl, piperidinyl, quinonyl,
pyrrolidonyl, pyrrolidono, imidazolino, and pyrazino groups.
[0034] In formula (5), R.sup.9 is hydrogen or methyl, and E.sup.2
is an amine residue or heterocyclic residue having 1 or 2 nitrogen
and 0 to 2 oxygen.
[0035] Specific examples of the amine residue for E.sup.2 are
dimethylamino, diethylamino, dipropylamino, dibutylamino, anilino,
toluidino, xylidino, acetylamino, and benzoilamino. Specific
examples of the heterocyclic residue are morpholino, pyrolyl,
pyridyl, methylpydidyl, pyrolidinyl, piperidinyl, quinonyl,
pyrrolidonyl, pyrrolidono, imidazolino, and pyrazino groups.
[0036] Among the monomers of formulae (4), (5), and (6), preferred
are dimethylaminomethacrylate of formula (4) wherein R.sup.7 is
methyl, R.sup.8 is methylene, and E.sup.1 is dimethylamino;
diethylaminomethylmethacrylate of formula (4) wherein R.sup.7 is
methyl, R.sup.8 is methylene, and E.sup.1 is diethylamino;
dimethylaminoethylmethacrylate of formula (4) wherein R.sup.7 is
methyl, R.sup.8 is ethylene, and E.sup.1 is dimethylamino;
diethylaminoethylmethacrylate of formula (4) wherein R.sup.7 is
methyl, R.sup.8 is ethylene, and E.sup.1 is diethylamino;
morpholinomethylmethacr- ylate of formula (4) wherein R.sup.7 is
methyl, R.sup.8 is methylene, and E.sup.1 is morpholino;
morpholinoethylmethacrylate of formula (4) wherein R.sup.7 is
methyl, R.sup.8 is ethylene, and E.sup.1 is morpholino;
2-vinyl-5-methylpyridine of formula (5) wherein R.sup.9 is
hydrogen, and E.sup.2 is 5-methylpyridyl; and N-vinylpyrrolidone of
formula (5) wherein R.sup.9 is hydrogen and E.sup.2 is
pyrrolidono.
[0037] When one or more monomers represented by formula (1), (2) or
(3) is copolymerized with one or more monomers represented by
formula (4) or (5), the molar ratio of the former monomers to the
latter monomers is arbitrary selected but is within the range of
80:20 to 95:5. The copolymerization is conducted using any suitable
conventional method by radical-solution polymerization of the
monomers in the presence of a polymerization initiator such as
benzoyl peroxide.
[0038] Specific examples of Component (B), i.e., viscosity index
improvers are polymethacrylates, ethylene-.alpha.-olefin copolymers
and hydrides thereof, polyisobutylene and hydrides thereof,
styrene-diene hydrogenated copolymers, styrene-maleic anhydrides
copolymers, and polyalkylstyrene. These viscosity index improvers
may be of either dispersion type or non-dispersion type. However,
preferred are dispersion type viscosity index improvers because of
their capability to maintain anti-shudder properties.
[0039] Preferred for Component (B) are polymethacrylates because
they are superior in an enhancement in low temperature fluidity.
The molecular weight of polymethacrylates is preferably selected in
view of shear stability. In general, preferred polymethacrylates
are those having a weight-average molecular weight of 10,000 to
200,000, preferably 10,000 to 60,000 in view of the prolonged
use.
[0040] No particular limitation is imposed on the content of
Component (B). In general, it is contained in an amount of
preferably 0.1 to 25 percent by mass, more preferably 0.5 to 20
percent by mass, based on the total mass of the transmission
lubricant composition. A content of Component (B) which is less
than 0.1 percent by mass would be poor in effect to improve low
temperature fluidity, while that in excess of 25 percent by mass
would fail to exhibit an effect corresponding to the amounts.
[0041] Component (C) of the present invention is a friction
modifier. Eligible friction modifiers are those having in its
molecules at least one alkyl or alkenyl group having 6 to 30,
preferably 9 to 24 carbon atoms and no hydrocarbon group having 31
or more carbon atoms. The alkyl or alkenyl group may be
straight-chain or branched. However, those having less than 6 or
more than 30 carbon atoms are not preferred because they possibly
deteriorate the function properties in a wet clutch.
[0042] Specific examples of the alkyl and alkenyl groups are alkyl
groups, which may be straight-chain or branched, such as hexyl,
heptyl, octyl, nonyl, decyl, undecyl, dodecyl (lauryl), tridecyl,
tetradecyl (myristyl), pentadecyl, hexadecyl (palmityl),
heptadecyl, octadecyl (stearyl), nonadecyl, eicosyl, heneicosyl,
docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl,
octacosyl, nonacosyl and triacontyl groups; and alkenyl groups,
which may be straight-chain or branched and the position of which
the double bond may vary, such as hexenyl, heptenyl, octenyl,
nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl,
pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl (oleyl),
nonadecenyl, eicosenyl, heneicosenyl, docosenyl, tricosenyl,
tetracosenyl, pentacosenyl, hexacosenyl, heptacosenyl, octacosenyl,
nonacosenyl and triacontenyl groups.
[0043] Preferred friction modifiers for the present invention are
as follows:
[0044] (C-1) an amine compound having in its molecules at least one
alkyl or alkenyl group having 6 to 30 carbon atoms and no
hydrocarbon group having 31 or more carbon atoms, and derivatives
thereof;
[0045] (C-2) a phosphorus compound having in its molecules at least
one alkyl or alkenyl group having 6 to 30 carbon atoms and no
hydrocarbon group having 31 or more carbon atoms, and derivatives
thereof; and
[0046] (C-3) an amide or metallic salt of a fatty acid having in
its molecules at least one alkyl or alkenyl group having 6 to 30
carbon atoms and no hydrocarbon group having 31 or more carbon
atoms.
[0047] Specific examples of (C-1) the amine compound are aliphatic
monoamines represented by the formula or alkyleneoxide adducts
thereof 3
[0048] aliphatic polyamines represented by the formula 4
[0049] and imidazoline compounds represented by the formula 5
[0050] In formula (6), R.sup.10 is an alkyl or alkenyl group having
6 to 30, preferably 9 to 24 carbon atoms, R.sup.11 and R.sup.12 are
each independently ethylene or propylene, R.sup.13 and R.sup.14 are
each independently hydrogen or a hydrocarbon group having 1 to 30
carbon atoms, f and g are each independently an integer of 0 to 10,
preferably 0 to 6, and f+g=0 to 10, preferably 0 to 6.
[0051] In formula (7), R.sup.15 is an alkyl or alkenyl group having
6 to 30, preferably 9 to 24 carbon atoms, R.sup.16 is ethylene or
propylene, R.sup.17 and R.sup.18 are each independently hydrogen or
a hydrocarbon group having 1 to 30 carbon atoms, h is an integer of
1 to 5, preferably 1 to 4.
[0052] In formula (8), R.sup.19 is an alkyl or alkenyl group having
6 to 30, preferably 9 to 24 carbon atoms, R.sup.20 is ethylene or
propylene, R.sup.21 is hydrogen or a hydrocarbon group having 1 to
30 carbon atoms, and i is an integer of 0 to 10, preferably 0 to
6.
[0053] The alkyl or alkenyl group for R.sup.10, R.sup.15, and
R.sup.19 may be straight-chain or branched but have 6 to 30 carbon
atoms, preferably 9 to 24 carbon atoms.
[0054] Specific examples of the alkyl or alkenyl groups for
R.sup.10, R.sup.15, and R.sup.19 are alkyl groups, which may be
straight-chain or branched, such as hexyl, heptyl, octyl, nonyl,
decyl, undecyl, dodecyl (lauryl), tridecyl, tetradecyl (myristyl),
pentadecyl, hexadecyl (palmityl), heptadecyl, octadecyl (stearyl),
nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl,
pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl and
triacontyl groups; and alkenyl groups, which may be straight-chain
or branched and the position of which the double bond may vary,
such as hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl,
dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl,
heptadecenyl, octadecenyl (oleyl), nonadecenyl, eicosenyl,
heneicosenyl, docosenyl, tricosenyl, tetracosenyl, pentacosenyl,
hexacosenyl, heptacosenyl, octacosenyl, nonacosenyl and
triacontenyl groups. Among these, particularly preferred are alkyl
or alkenyl groups having 12 to 18 carbon atoms, such as lauryl,
myristyl, palmityl, stearyl, isostearyl (16-methylheptadecyl), and
oleyl groups because they can provide superior friction properties
in a wet clutch.
[0055] Specific examples of the group for each R.sup.13, R.sup.14,
R.sup.17, R.sup.18, and R.sup.21 are hydrogen; alkyl groups, which
may be straight-chain or branched, such as methyl, ethyl, propyl,
butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl,
dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl,
octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl,
tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl
and triacontyl groups; alkenyl groups, which may be straight-chain
or branched and wherein the position of the double bond may vary,
such as butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl,
decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl,
pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl,
eicosenyl, heneicosenyl, docosenyl, tricosenyl, tetracosenyl,
pentacosenyl, hexacosenyl, heptacosenyl, octacosenyl, nonacosenyl
and triacontenyl groups; cycloalkyl groups having 5 to 7 carbon
atoms, such as cyclopentyl, cyclohexyl and cycloheptyl groups;
alkylcycloalkyl groups, of which the alkyl group may bond to any
position of the cycloalkyl group, having 6 to 11 carbon atoms, such
as methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl,
diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl,
methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl,
dimethylcycloheptyl, methylethylcycloheptyl and diethylcycloheptyl
groups; aryl groups such as phenyl and naphtyl groups; alkylaryl
groups, of which the alkyl group may be straight-chain or branched
and may bond to any position of the aryl group, having 7 to 18
carbon atoms, such as tolyl, xylyl, ethylphenyl, propylphenyl,
butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl,
nonylphenyl, decylphenyl, undecylphenyl and dodecylphenyl groups;
and arylalkyl groups, of which the alkyl group may be
straight-chain or branched, having 7 to 12 carbon atoms, such as
benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl and
phenylhexyl groups.
[0056] Among the aliphatic monoamines of formula (6) and
alkyleneoxide adducts thereof, more preferred are those of formula
(6) wherein R.sup.13 and R.sup.14 are each independently hydrogen
or an alkyl group having 1 to 6 carbon atoms, and f=g=0, and
alkyleneoxide adducts of aliphatic monoamines of formula (6)
wherein both R.sup.13 and R.sup.14 are hydrogen, and f and g are
each independently an integer of 0 to 6 and f+g=1 to 6 because of
their good friction properties in a wet clutch.
[0057] Among the aliphatic polyamines of formula (7), preferred are
those of formula (7) wherein R.sup.17 and R.sup.18 are each
independently hydrogen or an alkyl group having 1 to 6 carbon atoms
because of their good friction properties in a wet clutch.
[0058] Among the imidazoline compounds of formula (8), preferred
are those of formula (8) wherein R.sup.21 is hydrogen or an alkyl
group having 1 to 6 carbon atoms because of their good friction
properties in a wet clutch.
[0059] First examples of derivatives of the amine compounds also
referred to as (C-1) are acid-modified compounds obtained by
allowing the above-described amine compound of formula (6), (7) or
(8) to react with monocarboxylic acid (aliphatic acid) having 2 to
30 carbon atoms or polycarboxylic acid having 2 to 30 carbon atoms,
such as oxalic acid, phthalic acid, trimellitic acid, and
pyromellitic acid so as to neutralize the whole or part of the
remaining amino and/or imino groups or to convert the whole or part
of the same into amide. Second examples are boron-modified
compounds obtained by allowing the above-described amine compound
of formula (6), (7) or (8) to react with boric acid so as to
neutralize the whole or part of the remaining amino and/or imino
groups. Third examples are salts of phosphates obtained by allowing
the above-described amine compound of formula (6), (7) or (8) to
react with acid phosphate or acid phosphite each having in its
molecules one or two hydrocarbon groups having 1 to 30 carbon atoms
but no hydrocarbon group having 31 or more carbon atoms and having
at least one hydroxyl group so as to neutralize the whole or part
of the remaining amino or imino groups. Forth examples are
alkyleneoxide adducts of amine compounds obtained by allowing the
amine compound of formula (7) or (8) to react with an alkylene
oxide such as ethylene oxide and propylene oxide. Other than these
compounds, there may be used modified products obtained by
subjecting the amine compound of formula (6), (7), or (8) to two or
more of the aforesaid modifications.
[0060] Therefore, in view of the capability to provide excellent
friction properties in a wet clutch, preferred amine compound and
derivatives thereof referred to as Component (C-1) are as
follows:
[0061] (i) amine compounds such as lauryl amine, lauryl
diethylamine, lauryl diethanolamine, dodecyldipropanolamine,
palmitylamine, stearylamine, stearyltetraethylenepentamine,
oleylamine, oleylpropylenediamine, oleyldiethanolamine, and
[0062] N-hydroxyethyloleylimidazolyne;
[0063] (ii) alkyleneoxide adducts of the above amine compounds
(i);
[0064] (iii) salts of the above amine compounds (i) and acid
phosphate such as di-2-ethylhexylphosphate or acid phosphite such
as 2-ethylhexylphosphite;
[0065] (iv) boric acid-modified product of the above amine
compounds (i), the above alkyleneoxide adducts (ii) or the salts
(iii); and
[0066] (v) mixtures of any two or more of (i), (ii), (iii), and
(iv).
[0067] Phosphorus compounds referred to as Component (C-2) are
phosphates represented by the formula 6
[0068] and
[0069] phosphites represented by the formula 7
[0070] In formula (9), R.sup.22 is an alkyl or alkenyl group having
6 to 30, 9 to 24 carbon atoms, R.sup.23 and R.sup.24 are each
independently hydrogen or a hydrocarbon group having 1 to 30 carbon
atoms, F.sup.1, F.sup.2, F.sup.3, and F.sup.4 are each
independently oxygen or sulfur, provided that at least one of
F.sup.1, F.sup.2, F.sup.3, and F.sup.4 is oxygen.
[0071] In formula (10), R.sup.25 is an alkyl or alkenyl group
having 6 to 30, preferably 9 to 24 carbon atoms, R.sup.26 and
R.sup.27 are each independently hydrogen or a hydrocarbon group
having 1 to 30 carbon atoms, F.sup.5, F.sup.6, and F.sup.7 are each
independently oxygen or sulfur provided that at least one of
F.sup.5, F.sup.6, and F.sup.7 is oxygen.
[0072] The alkyl and alkenyl group for R.sup.22 and R.sup.25 may be
straight-chain or branched ones but have 6 to 30, preferably 9 to
24 carbon atoms. Departures from the above-specified range of
carbon number would cause a deterioration in friction properties in
a wet clutch.
[0073] Specific examples of the alkyl or alkenyl groups for
R.sup.22 and R.sup.25 are alkyl groups, which may be straight-chain
or branched, such as hexyl, heptyl, octyl, nonyl, decyl, undecyl,
dodecyl (lauryl), tridecyl, tetradecyl (myristyl), pentadecyl,
hexadecyl (palmityl), heptadecyl, octadecyl (stearyl), nonadecyl,
eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl,
hexacosyl, heptacosyl, octacosyl, nonacosyl and triacontyl groups;
and alkenyl groups, which may be straight-chain or branched and the
position of which the double bond may vary, such as hexenyl,
heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl,
tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl,
octadecenyl (oleyl), nonadecenyl, eicosenyl, heneicosenyl,
docosenyl, tricosenyl, tetracosenyl, pentacosenyl, hexacosenyl,
heptacosenyl, octacosenyl, nonacosenyl and triacontenyl groups.
Among these, particularly preferred are straight-chain alkyl or
alkenyl groups having 12 to 18 carbon atoms, such as lauryl,
myristyl, palmityl, stearyl, and oleyl groups with because they can
provide superior friction properties in a wet clutch.
[0074] Specific examples of the hydrocarbon group for R.sup.23,
R.sup.24, R.sup.26, and R.sup.27 are alkyl groups, which may be
straight-chain or branched, such as methyl, ethyl, propyl, butyl,
pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl,
tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,
nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl,
pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl and
triacontyl groups; alkenyl groups, which may be straight-chain or
branched and wherein the position of the double bond may vary, such
as butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl,
undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl,
hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, eicosenyl,
heneicosenyl, docosenyl, tricosenyl, tetracosenyl, pentacosenyl,
hexacosenyl, heptacosenyl, octacosenyl, nonacosenyl and
triacontenyl groups; cycloalkyl groups having 5 to 7 carbon atoms,
such as cyclopentyl, cyclohexyl and cycloheptyl groups;
alkylcycloalkyl groups, of which the alkyl group may bond to any
position of the cycloalkyl group, having 6 to 11 carbon atoms, such
as methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl,
diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl,
methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl,
dimethylcycloheptyl, methylethylcycloheptyl and diethylcycloheptyl
groups; aryl groups such as phenyl and naphtyl groups; alkylaryl
groups, of which the alkyl group may be straight-chain or branched
and may bond to any position of the aryl group, having 7 to 18
carbon atoms, such as tolyl, xylyl, ethylphenyl, propylphenyl,
butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl,
nonylphenyl, decylphenyl, undecylphenyl and dodecylphenyl groups;
and arylalkyl groups, of which the alkyl group may be
straight-chain or branched, having 7 to 12 carbon atoms, such as
benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl and
phenylhexyl groups.
[0075] Because their excellent friction properties in a wet clutch,
preferred phosphorus compounds as Component (C-2) are acid
phosphates represented by formula (9) wherein at least one of
R.sup.23 and R.sup.24 is hydrogen and acid phosphites represented
formula (10) wherein at least one of R.sup.26 and R.sup.27 is
hydrogen.
[0076] Specific examples of the derivatives of the phosphoric
compounds also referred to as Component (C-2) are salts obtained by
allowing an acid phosphite of formula (9) wherein at least one of
R.sup.23 and R.sup.24 is hydrogen or an acid phosphite of formula
(10) wherein at least one of R.sup.26 and R.sup.27 is hydrogen to
react with a nitrogen-containing compound such as ammonia or an
amine compound having in its molecules only hydrocarbon or
hydroxyl-containing groups having 1 to 8 carbon atoms so as to
neutralize the whole or part of the remaining acid hydrogen.
[0077] Specific examples of such a nitrogen-containing compound are
ammonia; alkylamines, of which the alkyl group may be
straight-chain or branched, such as monomethylamine,
monoethylamine, monopropylamine, monobutylamine, monopentylamine,
monohexylamine, monoheptylamine, monooctylamine, dimethylamine,
methylethylamine, diethylamine, methylpropylamine,
ethylpropylamine, dipropylamine, methylbutylamine, ethylbutylamine,
propylbutylamine, dibutylamine, dipentylamine, dihexylamine,
diheptylamine and dioctylamine; alkanolamines, of which the alkanol
group may be straight-chain or branched, such as monomethanolamine,
monoethanolamine, monopropanolamine, monobutanolamine,
monopentanolamine, monohexanolamine, monoheptanolamine,
monooctanolamine, monononanolamine, dimethanolamine,
methanolethanolamine, diethanolamine, methanolpropanolamine,
ethanolpropanolamine, dipropanolamine, methanolbutanolamine,
ethanolbutanolamine, propanolbutanolamine, dibutanolamine,
dipentanolamine, dihexanolamine, diheptanolamine and
dioctanolamine; and mixtures thereof.
[0078] Because of their excellent friction properties in a wet
clutch, particularly preferred phosphorus compounds as Component
(C-2) are monolauryl phosphate, dilauryl phosphate, monostearyl
phosphate, distearyl phosphate, monooleyl phosphate, dioleyl
phosphate, monolauryl phosphate, dilauryl phosphite, monostearyl
phosphite, distearyl phosphite, monooleyl phosphite,
dioleylphosphite, monolauryl thiophosphate, dilauryl thiophosphate,
monostearyl thiophosphate, distearyl thiophosphate, monooleyl
thiophosphate, dioleyl thiophosphate, monolauryl thiophosphate,
dilauryl thiophosphite, monostearyl thiophosphite, distearyl
thiophosphite, monooleyl thiophosphite, dioleyl thiophosphite;
amine salts of these phosphates such as mono2-ethylhexylamine
salts, phosphite, thiophosphate and thiophosphite; and mixtures
thereof.
[0079] The fatty acid amide or fatty metal salt referred to as
Component (C-3) may be straight-chain or branched and saturated or
unsaturated fatty acids but the alkyl group or alkenyl group
thereof has 6 to 30, preferably 9 to 24 carbon atoms. Fatty acids
having an alkyl or alkenyl group having fewer than 6 or 31 or
greater carbon atoms are not preferred because they would cause the
deterioration of friction properties in a wet clutch.
[0080] Specific examples of the fatty acid are straight-chain or
branched saturated fatty acids, such as heptanoic acid, octanonic
acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic
acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid,
hexadecanoic acid, heptadecanoic acid, octadecanoic acid;
nonadecanoic acid, icosanoic acid, henicosanoic acid, docosanoic
acid, tricosanoic acid, tetracosanoic acid, pentacosanoic acid,
hexacosanoic acid, heptacosanoic acid, octacosanoic acid,
nonacosanoic acid, and triacontanoic acid; and straight-chain or
branched unsaturated fatty acids, wherein the position the double
bond may vary, such as heptanoic acid, octenoic acid, nonenoic
aicd, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic
acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid,
heptadecenoic acid, octadecenoic acid, nonadecenoic acid,
eicosenoic acid, heneicosenoic acid, docosenoic acid, tricosenoic
acid, tetracosenoic acid, pentasenoic acid, hexacosenoic acid,
heptacosenoic acid, octacosenoic acid, nonacosenoic acid and
triacontenoic acid. Because of their excellent friction properties
in a wet clutch, particularly preferred fatty acids are
straight-chain fatty acids derived from various types of fats and
oils such as lauric acid, myristic acid, palmitic acid, stearic
acid and oleic acid and mixtures of straight-chain fatty acid and
branched fatty acid obtained by the oxo synthesis.
[0081] The fatty acid amide referred to as Component (C-3) may be
amides obtained by reacting a nitrogen-containing compound such as
ammonia and amine compound having per molecule only hydrocarbon or
hydroxyl-containing hydrocarbon groups having 1 to 8 carbon
atoms.
[0082] Specific examples of such a nitrogen-containing compound are
ammonia; alkylamine, of which the alkyl group may be straight-chain
or branched, such as monomethylamine, monoethylamine,
monopropylamine, monobutylamine, monopentylamine, monohexylamine,
monoheptylamine, monooctylamine, dimethylamine, methylethylamine,
diethylamine, methylpropylamine, ethylpropylamine, dipropylamine,
methylbutylamine, ethylbutylamine, propylbutylamine, dibutylamine,
dipentylamine, dihexylamine, diheptylamine and dioctylamine; and
alkanolamines, of which the alkanol group may be straight-chain or
branched, such as monomethanolamine, monoethanolamine,
monopropanolamine, monobutanolamine, monopentanolamine,
monohexanolamine, monoheptanolamine, monooctanolamine,
monononanolamine, dimethanolamine, methanolethanolamine,
diethanolamine, methanolpropanolamine, ethanolpropanolamine,
dipropanolamine, methanolbutanolamine, ethanolbutanolamine,
propanolbutanolamine, dibutanolamine, dipentanolamine,
dihexanolamine, diheptanolamine, and dioctanolamine.
[0083] Because of their excellent friction properties in a wet
clutch, specific examples of the fatty acid amides as Component
(C-3) are lauric acid amide, lauric acid diethanolamide, lauric
monopropanolamide, myristic acid amide, myristic acid
diethanolamide, myristic acid monopropanolamide, palmitic acid
amide, palmitic acid ethanolamide, palmitic acid monopropanolamide,
stearic acid amide, stearic acid diethanolamide, stearic acid
monopropanolamide, oleic acid amide, oleic acid diethanolamide,
oleic acid monopropanol amide, coconut oil fatty amide, coconut oil
fatty acid diethanolamide, coconut oil fatty monopropanolamide,
synthetic mixed fatty amides having 12 to 13 carbon atoms,
synthetic mixed fatty diethanolamides having 12 to 13 carbon atoms,
synthetic mixed fatty monopropanolamides having 12 to 13 carbon
atoms, and mixtures thereof.
[0084] Specific examples of the fatty metallic acid also referred
to as Component (C-3) are alkaline earth metal salts such as a
magnesium salt and a calcium salt, and a zinc salt of any of the
above-exemplified fatty acids. Because of their excellent friction
properties in a wet clutch, particularly preferred fatty acid
metallic salts are calcium laurate, calcium myristate, calcium
palmitate, calcium stearate, calcium oleate, coconut oil fatty acid
calcium, synthetic mixed fatty acid calcium having 12 or 13 carbon
atoms, zinc laurate, zinc myristate, zinc palmitate, zinc stearate,
zinc oleate, coconut oil fatty zinc, synthetic mixed fatty zinc
having 12 to 13 carbon atoms, and mixtures thereof.
[0085] Any one or more members arbitrary selected from the
above-described Components (C-1) through (C-3) may be added to the
transmission lubricant composition of the present invention in any
suitable amount as long as they do not adversely affect the other
properties of the resulting composition such as oxidation
stability. In order to obtain long-lasting friction properties of
the composition, it is necessary to avoid a deterioration in
friction properties caused by the deterioration of the friction
modifier. Addition of large amounts of Component (C) is effective
in obtaining long-lasting friction properties. However, too large
amounts of Component (C) would lead to reduced static friction
coefficient which is required to be high so as to maintain the
coupling or engagement of a wet clutch. The amount of Component (C)
is thus limited to some extent.
[0086] Therefore, the content of Component (C) is within the range
of preferably 0.005 to 3.0 mass percent, preferably 0.01 to 2.0
mass percent, based on the total mass of the transmission lubricant
composition of the present invention.
[0087] The transmission lubricant composition of the present
invention is obtained by blending a particular mineral base oil
with suitable amounts of the viscosity index improver and friction
modifier. Although the composition as such is superior in the
durability of anti-shudder properties and in low temperature
fluidity, in order to further enhance such properties there may be
blended various additives such as anti-wear agents, extreme
pressure agents, ashless dispersants, metallic detergents,
oxidation inhibitors, corrosion inhibitors, anti-foaming agents and
dyes. These additives may be used individually or in
combination.
[0088] Anti-wear agents may be any of conventional ones for
lubricants. Eligible abrasion inhibitors are one or more phosphorus
compounds such as salts of monophosphates, diphosphates,
triphosphates, monophosphites, diphosphites, triphosphites, or
these esters with amines or alkanolamines. The content of such
abrasion inhibitors is selected from the range of 0.005 to 2
percent by mass, based on the total mass of the transmission
lubricant composition.
[0089] Extreme pressure agents may be any of conventional ones for
lubricants. Eligible extreme pressure agents are sulfuric compounds
such as disulfides, olefin sulfides, and sulfurized fats and oils.
One or more of these compounds is preferably added in an amount of
0.1 to 5.0 percent by mass based on the total mass of the
transmission lubricant composition.
[0090] Ashless dispersants may be any of conventional ones for
lubricants, such as amino- or imino-compounds having their
molecules at least one alkyl or alkenyl group having 40 to 400
carbon atoms, and modified products thereof.
[0091] The alkyl and alkenyl groups may be straight-chain or
branched. Preferred are branched alkyl and alkenyl groups derived
from oligomers of olefins such as propylene, 1-butne, and
isobutylene or cooligomers of ethylene and propylene. The alkyl and
alkenyl groups have preferably 60 to 350 carbon atoms. Alkyl and
alkenyl groups having fewer than 40 carbon atoms would result in a
compound having poor solubility to the lubricating base oil, those
having over 400 carbon atoms would deteriorate the low temperature
fluidity of the transmission lubricant composition.
[0092] Examples of derivatives of the amino and/or imino compounds
are (i) acid-modified compounds obtained by allowing the
above-described amino or imino compound to react with
monocarboxylic acid having 2 to 30 carbon atoms, such as fatty acid
or polycarboxylic acid having 2 to 30 carbon atoms, such as oxalic
acid, phthalic acid, trimellitic acid, and pyromellitic acid to
neutralize the whole or part of the remaining amino and/or imino
groups or to convert the whole or part of the same into amide; (ii)
boron-modified compounds obtained by allowing the above-described
amino or imino compound to react with boric acid to neutralize the
whole or part of the remaining amino and/or imino groups or to
convert the whole or part of the same into amide; and (iii)
sulfur-modified compounds obtained by allowing the above-described
amino or imino compound to react with a sulfuric compound.
[0093] There may be blended the above-described amino and imino
compounds and one or more modified products thereof as the ashless
dispersant. The content thereof is selected from the range of 0.1
to 10 percent by mass, based on the total mass of the transmission
lubricant composition.
[0094] Metallic detergents may be any of conventional ones for
lubricants. Eligible metallic detergents are sulfonates, phenates,
and salicylates of alkaline metals or alkaline earth metals. These
compounds may be used individually or in combination. Examples of
the alkaline metals are sodium and potassium, while examples of the
alkaline earth metals are calcium and magnesium. Specific examples
of the metallic detergent are sulfonates, phenates and salicylates
of calcium or magnesium.
[0095] The content of the metallic detergent is arbitrary selected,
depending on the properties required for the transmission lubricant
composition. In general, the metallic detergent is blended in an
amount of 0.1 to 5.0 percent by mass, based on the total mass of
the transmission lubricant composition.
[0096] Oxidation inhibitors are any of conventional ones for
lubricants. Eligible oxidation inhibitors are phenol- or
amine-based compounds. These may be used individually or in
combination. Specific examples of the oxidation inhibitor are
alkylphenols such as 2-6-di-tert-butyl-4-methylph- enol, bisphenols
such as methylene-4,4-bisphenol(2,6-di-tert-butyl-4-methy-
lphenol), naphtylamines such as phenyl-.alpha.-naphtylamine,
dialkyldiphenylamines, zinc dialkyldithiophosphates such as zinc
di-2-ethylhexyldithiophosphate, esters of
3,5-di-tert-butyl-4-hydroxyphen- yl fatty acid (propionic acid)
with a mono- or poly-hydric alcohol such as methanol, octadecanol,
1,6 hexanediol, neopentyl glycol, thiodiethylene glycol,
triethylene glycol or pentaerythritol.
[0097] The oxidation inhibitor is blended in an amount of 0.01 to
5.0 percent by mass based on the total mass of the transmission
lubricant composition.
[0098] Corrosion inhibitors may be conventional ones for
lubricants. Eligible corrosion inhibitors are benzotriazole-,
tolyltriazole-, thiodiazole- and imidazole-based compounds. These
may be used individually or in combination. The corrosion inhibitor
is usually blended in an amount of 0.01 to 3.0 percent by mass,
based on the total mass of the transmission lubricant
composition.
[0099] Anti-foaming agents may conventional ones for lubricants.
Eligible anti-foaming agents are silicones such as dimethylsilicon
and fluorosilicon. These may be used individually or in
combination. The anti-foaming agents is usually blended in an
amount of 0.001 to 0.05 percent by mass, based on the total mass of
the transmission lubricant composition.
[0100] When a dye is blended in the lubricant composition of the
present invention, they may be conventional ones. The dye is
usually blended in an amount of 0.001 to 1.0 percent by mass, based
on the total mass of the transmission lubricant composition.
[0101] The invention will be further described by way of the
following examples and comparative examples which are provided for
illustrative purposes only.
[0102] EXAMPLES
[0103] Transmission lubricant compositions of the present invention
and of comparative examples were prepared such that the kinematic
viscosity at 100 .degree. C. of each composition is made to 7.3
mm.sup.2/s, in accordance with the formulations indicated in Table
1.
[0104] Each of the compositions was subjected to an anti-shudder
durability test, a low temperature viscosity measurement, and a
shear stability test. Table 1 shows the results of the durability
of anti-shudder properties, low temperature fluidity, and shear
stability.
1 TABLE 1 Compara- Inventive Examples tive 1 2 3 4 Example 1 Base
Oil Mineral Oil A.sup.1) mass % 79 55.3 12.3 79 -- Mineral Oil
B.sup.2) mass % -- 11.9 75.7 -- -- Mineral Oil C.sup.3) mass % --
11.8 -- -- 44.9 Mineral Oil D.sup.4) mass % -- -- -- -- 35.3
Kinematic Viscosity mm.sup.2/s 2.8 2.8 3.8 2.8 2.8 of Base Oil
(100.degree. C.) % C.sub.P of Base Oil 76 75 81 76 62 % C.sub.A of
Base Oil 2 2 0.6 2 5.6 Viscosity Index mass % -- -- -- 15 --
Improver A.sup.5) Viscosity Index mass % 15 15 -- -- 13.8 Improver
B.sup.6) Viscosity Index mass % -- -- 6.4 -- -- Improver C.sup.7)
Ashless Dispersant mass % 3 3 3 3 3 A.sup.8) Ashless Dispersant
mass % 1 1 0.5 1 1 B.sup.9) Anti-wear agent.sup.10) mass % 0.2 0.2
0.2 0.2 0.2 Ca-based mass % 0.4 0.4 0.5 0.4 0.4 Detergent.sup.11)
Oxidation Inhibitor mass % 0.5 0.5 0.5 0.5 0.5 A.sup.12) Oxidation
Inhibitor mass % 0.5 0.5 0.5 0.5 0.5 B.sup.13) Friction Modifier
mass % 0.1 0.1 0.1 0.1 0.1 A.sup.14) Friction Modifier mass % 0.2
0.2 0.2 0.2 0.2 B.sup.15) Corrosion mass % 0.1 0.1 0.1 0.1 0.1
Inhibitor.sup.16) Low temperature mPa .multidot. s 8300 8300 16200
8100 20400 Viscosity (-40.degree. C.) The time taken until h 144
144 168 120 48 d.mu./dV reached less than 0 Viscosity reduction %
4.8 4.8 14.2 4.8 4.3 after shear .sup.1)hydro-refined mineral oil
(viscosity index: 110, % C.sub.P: 76, % CA: 2.0)
.sup.2)hydxo-refined mineral oil (viscosity index: 125, % C.sub.P:
81, % CA: 0.5) .sup.3)solvent-refined mineral oil (viscosity index:
95, % C.sub.P: 60, % CA: 5.2) .sup.4)solvent-refined mineral oil
(viscosity index: 100, % C.sub.P: 67, % CA: 6.5)
.sup.5)non-dispersion type polymethacrylate (weight-average
molecular-weight: 40,000) .sup.6)dispersion type polymethacrylate
(weight-average molecular-weight: 40,000) .sup.7)dispersion type
polymethacrylate (weight-average molecular-weight: 120,000)
.sup.8)polybutenylsuccinimide (bis-type) .sup.9)boric acid-modified
polybutenylsuccinimide (mono-type) .sup.10)arylphosphite
.sup.11)petroleum-based Ca sulfonate (total base number: 300
mgKOH/g) .sup.12)dialkyldiphenylamine-based .sup.13)bisphenol-based
.sup.14)oleylamine .sup.15)ethoxylated oleylamine
.sup.16)tolyltriazole
Anti-Shudder Durability Test
[0105] The results of .mu.-V characteristics evaluation test using
a wet clutch was used as a measure of the anti-shudder properties
of a transmission lubricant composition. The .alpha.-V
characteristics was evaluated in accordance with "Test method for
anti-shudder performance of automatic transmission fluids"
prescribed in JASO M349-98. A transmission lubricant composition is
considered to have no anti-shudder properties in the case where
d.mu./dV(50) or d .mu./dV(1 50) defined by the formulae below is
less than 0.
d.mu./dV(50)=(.mu..sub.50-.mu..sub.1)/(V.sub.50-V.sub.1)
d.mu./dV(150)=(.mu..sub.150-.mu..sub.50)/(V.sub.150-V.sub.50)
[0106] wherein .mu..sub.1 is friction coefficient at 1 rpm,
[0107] .mu..sub.50 is friction coefficient at 50 rpm,
[0108] .mu..sub.150 is friction coefficient at 150 rpm,
[0109] V.sub.1 is a sliding velocity of 0.006 m/s at 1 rpm,
[0110] V.sub.50 is a sliding velocity of 0.3 m/s at 50 rpm,
[0111] V.sub.150 is a sliding velocity of 0.9 m/s at 150 rpm.
[0112] Each of the above lubricant compositions was subjected to
"Test method for Oxidation Stability of Lubricating Oils for
Internal Combustion Engines" of "Testing Methods for Oxiation
Stability of Lubricating Oils" prescribed in JIS K2514-1993, at a
test temperature of 150.degree. C., for varied test periods of
time, thereby preparing various deteriorated oils. The .mu.-V
characteristics of each deteriorated oil was evaluated.
Anti-shudder durability was determined by the time taken until
d.mu./dV(50) or d.mu./dV(150) reached less than 0.
Low Temperature Viscosity Evaluation
[0113] The low temperature viscosity at -40.degree. C. of each
transmission lubricant composition was measured in a low
temperature liquid bath in accordance with "Gear oil low
temperature viscosity determination method" prescribed in
JPI-5S-26-85.
Shear Stability Test
[0114] Each of the above transmission lubricant composition was
irradiated with ultrasonic wave for one hour in accordance with
"Test method for shear stability of automatic transmission fluids"
prescribed in JASO M347-95. The viscosity reduction rate of each
composition was derived from the kinematic viscosity of before and
after irradiation using the following equation:
.DELTA.V=(V.sub.0-V.sub.r)/V.sub.0.times.100
[0115] wherein .DELTA.V is viscosity reduction rate (% )
[0116] V.sub.0 is kinematic viscosity (mm.sup.2/s) before
irradiation
[0117] V.sub.r is kinematic viscosity (mm.sup.2/s) after
irradiation
[0118] As apparent from the results shown in Table 1, the
transmission lubricant compositions of Examples 1 to 4 take longer
time until d.mu./t/dV values reached 0 and have excellent
properties, i.e., low viscosity at low temperatures.
[0119] Whereas, the transmission lubricant composition of
Comparative Example 1 contains a base oil of which % C.sub.P and/or
% C.sub.A deviates the ranges defined by the present invention and
thus take shorter time until d.mu./dV values reached 0 with less
durable in anti-shudder properties and high viscosity at low
temperatures.
* * * * *