U.S. patent application number 10/752805 was filed with the patent office on 2005-07-07 for power transmission fluids with enhanced anti-shudder characteristics.
Invention is credited to Ozbalik, Nubar, Tersigni, Samuel H..
Application Number | 20050148478 10/752805 |
Document ID | / |
Family ID | 34592565 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050148478 |
Kind Code |
A1 |
Ozbalik, Nubar ; et
al. |
July 7, 2005 |
Power transmission fluids with enhanced anti-shudder
characteristics
Abstract
A power transmission fluid composition having improved
characteristics. The fluid may comprise a base oil and an additive
composition including a viscosity index improving amount of a
polyisoalkylene component having a molecular weight ranging from
about 300 to about 3000 weight average molecular weight as
determined by gel permeation chromatography. The power transmission
fluid exhibits a kinematic viscosity (KV at 100.degree. C.) of less
than about 9 centistokes and a Brookfield viscosity (BV at
-40.degree. C.) of less than about 30,000 centipoise. Also the
friction versus velocity curve for the fluid has a more positive
slope at high speeds compared to similar fluids in the absence of
the polyisoalkylene component.
Inventors: |
Ozbalik, Nubar; (Midlothian,
VA) ; Tersigni, Samuel H.; (Glen Allen, VA) |
Correspondence
Address: |
DENNIS H. RAINEAR
CHIEF PATENT COUNSEL, ETHYL CORPORATION
330 SOUTH FOURTH STREET
RICHMOND
VA
23219
US
|
Family ID: |
34592565 |
Appl. No.: |
10/752805 |
Filed: |
January 7, 2004 |
Current U.S.
Class: |
508/591 |
Current CPC
Class: |
C10M 171/02 20130101;
C10N 2040/045 20200501; C10N 2040/042 20200501; C10M 2205/026
20130101; F16H 57/041 20130101; C10N 2040/044 20200501; C10M 143/06
20130101 |
Class at
Publication: |
508/591 |
International
Class: |
C10M 143/06; C10M
161/00 |
Claims
1. A power transmission fluid composition, comprising: (a) a base
oil, and (b) an additive composition comprising a viscosity index
improving amount of a polyisoalkylene component having a molecular
weight ranging from about 300 to about 10,000 weight average
molecular weight as determined by gel permeation chromatography,
wherein the power transmission fluid exhibits a kinematic viscosity
(KV at 100.degree. C.) of less than about 9 centistokes and a
Brookfield viscosity (BV at -40.degree. C.) of less than about
30,000 centipoise, and wherein a friction versus velocity curve for
the fluid has a more positive slope at high speeds compared to
similar fluids in the absence of the polyisoalkylene component.
2. The fluid of claim 1, wherein the base oil comprises one or more
of a natural oil, a mixture of natural oils, a synthetic oil, a
mixture of synthetic oils, and a mixture of natural and synthetic
oils.
3. The fluid of claim 2, wherein the natural oil comprises one or
more of a mineral oil, a vegetable oil, and a mixture of mineral
oil and vegetable oil.
4. The fluid of claim 2, wherein the synthetic oil is comprises one
or more of an oligomer of an alphaolefin, an ester, an oil derived
from a Fischer-Tropsch process, a gas-to-liquid stock, and a
mixture thereof.
5. The fluid of claim 1, wherein the base oil comprises a kinematic
viscosity of from about 2 centistokes to about 10 centistokes at
100.degree. C.
6. The fluid of claim 1, wherein the polyisoalkylene comprises
polyisobutylene having a weight average molecular weight ranging
from about 500 to about 3000.
7. The fluid of claim 6, wherein the polyisobutylene is
hydrogenated.
8. The fluid of claim 1, wherein the additive composition comprises
from about 10 wt % to about 90 wt % polyisoalkylene component.
9. The fluid of claim 1, wherein the additive composition further
comprises one or more viscosity index improver components selected
from the group consisting of polymethacrylates, olefin copolymers,
and styrene-maleic esters.
10. The fluid of claim 1, wherein the additive composition further
comprises one or more of an ashless dispersant, an antioxidant, an
antiwear agent, a friction modifier, an antifoam agent, and a
corrosion inhibitor.
11. The fluid of claim 10, wherein the ashless dispersant is
comprises one or more of hydrocarbyl succinimides, hydrocarbyl
succinamides, polyol esters, mixed ester/amides of hydrocarbyl
substituted succinic acid, and Mannich condensation products of
hydrocarbyl-substituted phenols, formaldehyde and polyamines.
12. The fluid of claim 10, wherein the friction modifier comprises
one or more of aliphatic fatty amines, ether amines, alkyoxylated
aliphatic fatty am ines, alkoxylated ether amines, oil-soluble
aliphatic carboxylic acids, polyol esters, fatty acid amides,
acylated amines, imidazolines, tertiary amines, and hydrocarbyl
succinimides reacted with ammonia or a primary am ine.
13. The fluid of claim 10, wherein the antioxidant comprises one or
more of bis-alkylated diphenyl amines, phenyl alpha or beta napthyl
amines, sterically hindered phenols, bisphenols, and cinnamic acid
derivatives.
14. The fluid of claim 10, wherein the antiwear agent comprises one
or more of phosphate esters and salts thereof, phosphite esters and
salts thereof, dialkyldithiophosphoric acid esters and salts
thereof, phosphoric acids, and phosphorus acids.
15. The fluid of claim 10, wherein the antifoam agent comprises one
or more of silicones and polyacrylates.
16. The fluid of claim 1, wherein the fluid is suitable for use in
comprises one or more of a transmission employing one or more of a
slipping torque converter, a lock-up torque converter, a starting
clutch, and one or more shifting clutches.
17. The fluid of claim 1, wherein the fluid is suitable for use in
comprises one or more of a belt, chain, and disk-type continuously
variable transmission.
18. An automatic transmission containing the fluid of claim 1.
19. The automatic transmission of claim 18, wherein the automatic
transmission comprises a constantly variable transmission.
20. The automatic transmission of claim 18, wherein the
transmission comprises a carbon fiber friction plate.
21. A method of improving shear stability for a transmission fluid
comprising: providing a base oil; and adding to the base oil an
additive composition comprising from about 10 to about 90 wt % of a
polyisoalkylene component having a molecular weight ranging from
about 300 to about 10,000 weight average molecular weight as
determined by gel permeation chromatography, wherein the base oil
containing the additive composition exhibits a kinematic viscosity
(KV at 100.degree. C.) of less than about 9 centistokes and a
Brookfield viscosity (BV at -40.degree. C.) of less than about
30,000 centipoise, and wherein a friction versus velocity curve for
the oil and additive composition has a more positive slope at high
speeds compared to similar fluids in the absence of the
polyisoalkylene component.
22. The method of claim 21, wherein the base oil comprises one or
more of a natural oil, a mixture of natural oils, a synthetic oil,
a mixture of synthetic oils, and a mixture of natural and synthetic
oils.
23. The method of claim 22, wherein the natural oil comprises one
or more of a mineral oil, a vegetable oil, and a mixture of mineral
oil and vegetable oil.
24. The method of claim 22, wherein the synthetic oil comprises one
or more of an oligomer of an alphaolefin, an ester, an oil derived
from a Fischer-Tropsch process, a gas-to-liquid stock, and a
mixture thereof.
25. The method of claim 21, wherein the base oil comprises a
kinematic viscosity of from about 2 centistokes to about 10
centistokes at 100.degree. C.
26. The method of claim 21, wherein the polyisoalkylene comprises
polyisobutylene having a weight average molecular weight ranging
from about 500 to about 3000.
27. The method of claim 26, wherein the polyisobutylene is
hydrogenated.
28. The method of claim 21, wherein the additive composition
comprises from about 20 wt % to about 90 wt % polyisoalkylene
component.
29. The method of claim 21, wherein the additive further comprises
one or more viscosity index improver components selected from the
group consisting of polymethacrylates, olefin copolymers, and
styrene-maleic esters.
30. The method of claim 21, wherein the additive composition
further comprises one or more of an ashless dispersant, an
antioxidant, an antiwear agent a friction modifier, an antifoam
agent, and a corrosion inhibitor.
31. The method of claim 30, wherein the ashless dispersant
comprises one or more of hydrocarbyl succinimides, hydrocarbyl
succinamides, polyol esters, mixed ester/amides of hydrocarbyl
substituted succinic acid, and Mannich condensation products of
hydrocarbyl-substituted phenols, formaldehyde, and polyamines.
32. The method of claim 30, wherein the friction modifier comprises
one or more of aliphatic fatty amines, ether amines, alkyoxylated
aliphatic fatty amines, alkoxylated ether amines, oil-soluble
aliphatic carboxylic acids, polyol esters, fatty acid amides,
acylated amines, imidazolines, tertiary amines, and hydrocarbyl
succinimides reacted with ammonia or a primary amine.
33. The method of claim 30, wherein the antioxidant comprises one
or more of bis-alkylated diphenyl amines, phenyl alpha or beta
napthyl amines, sterically hindered phenols, bisphenols, and
cinnamic acid derivatives.
34. The method of claim 30, wherein the antiwear agent comprises
one or more of phosphate esters and salts thereof, phosphite esters
and salts thereof, dialkyldithiophosphoric acid esters and salts
thereof, phosphoric acids, and phosphorus acids.
35. The method of claim 30, wherein the antifoam agent comprises
one or more of silicones and polyacrylates.
36. The method of claim 21, wherein the fluid is suitable for use
in a transmission employing one or more of a slipping torque
converter, a lock-up torque converter, a starting clutch, and one
or more shifting clutches.
37. The method of claim 31, wherein the fluid is suitable for use
in a belt, chain, or disk-type continuously variable
transmission.
38. An additive concentrate for a transmission fluid, the additive
concentrate comprising: at least a first thickening agent
comprising a polyisoalkylene having a molecular weight ranging from
about 500 to about 10,000 weight average molecular weight as
determined by gel permeation chromatography, a second thickening
agent comprising one or more of polymethacrylates, olefin
copolymers, and styrene-maleic esters, wherein a total amount of
the first and second viscosity index improvers present in the
additive concentrate ranges from about 10 wt % to about 90 wt % and
the additive concentrate further comprises from about 5 wt % to
about 25 wt % base oil, and wherein a power transmission fluid
containing from about 1 to about 30 wt % of the additive
concentrate exhibits a kinematic viscosity (KV at 100.degree. C.)
of less than about 9 centistokes and a Brookfield viscosity (BV at
-40.degree. C.) of less than about 30,000 centipoise, and wherein a
friction versus velocity curve for the fluid has a more positive
slope at high speeds compared to similar fluids in the absence of
the polyisoalkylene component.
39. The additive concentrate of claim 38, wherein the
polyisoalkylene comprises polyisobutylene having a weight average
molecular weight ranging from about 500 to about 3000.
40. The additive concentrate of claim 39, wherein the
polyisobutylene is hydrogenated.
41. The additive concentrate of claim 38, wherein the additive
concentrate comprises from about 20 wt % to about 90 wt %
polyisoalkylene component.
42. The additive concentrate of claim 38, further comprising one or
more of an ashless dispersant, an antioxidant, an antiwear agent, a
friction modifier, an antifoam agent, and a corrosion
inhibitor.
43. The additive concentrate of claim 42, wherein the ashless
dispersant comprises one or more of hydrocarbyl succinimides,
hydrocarbyl succinamides, polyol esters, mixed ester/amides of
hydrocarbyl substituted succinic acid, and Mannich condensation
products of hydrocarbyl-substituted phenols, formaldehyde, and
polyamines.
44. The additive concentrate of claim 42, wherein the friction
modifier comprises one or more of aliphatic fatty amines, ether
amines, alkyoxylated aliphatic fatty amines, alkoxylated ether
amines, oil-soluble aliphatic carboxylic acids, polyol esters,
fatty acid amides, imidazolines, tertiary amines, and hydrocarbyl
succinimides reacted with ammonia or a primary amine.
45. The additive concentrate of claim 42, wherein the antioxidant
comprises one or more of bis-alkylated diphenyl amines, phenyl
alpha or beta napthyl amines, sterically hindered phenols,
bisphenols, and cinnamic acid derivatives.
46. The additive concentrate of claim 42, wherein the antiwear
agent comprises one or more of phosphate esters and salts thereof,
phosphite esters and salts thereof, and dialkyldithiophosphoric
acid esters and salts thereof.
47. The additive concentrate of claim 42, wherein the antifoam
agent comprises one or more of silicones and polyacrylates.
48. An automatic transmission fluid comprising a base oil and the
additive concentrate of claim 38, wherein the additive concentrate
is present in an amount of about 5 wt % to about 50 wt % in the
fluid.
50. A vehicle comprising an engine and a transmission, the
transmission including the automatic transmission fluid of claim
48.
51. The vehicle of claim 50 wherein the automatic transmission
comprises a carbon fiber containing friction plate.
Description
FIELD
[0001] The present disclosure relates to a power transmission fluid
having improved characteristics for high and low speed transmission
applications. The power transmission fluid disclosed here may
include a fluid suitable for an automatic transmission (ATF), a
manual transmission, a dual clutch transmission, and/or a
continuously variable transmission.
BACKGROUND
[0002] New and advanced transmission systems are being developed by
the automotive industry. These new systems often involve high
energy requirements. Therefore, friction materials technology must
be developed to meet the increasing energy requirements of these
advanced systems.
[0003] The high speeds generated during engagement and
disengagement of some of the newer transmission and braking systems
mean that a friction material must be able to maintain a relatively
constant friction throughout the engagement. It is important that
the frictional engagement be relatively constant over a wide range
of speeds and temperatures in order to minimize "shuddering" of
materials during braking or during transmission power shift from
one gear to another.
[0004] In particular, new high energy type friction materials are
being developed and used. The new high energy friction materials
are able to withstand high speeds wherein internal transmission
plate surface speeds are up to about 65 m/second. It is also
important that the friction material be useful under limited
lubrication conditions. One such material being developed for
automatic transmission applications is a carbon fiber containing
material.
[0005] In view of new materials and greater demands on
transmissions, automotive power transmission fluids are called upon
to provide specific frictional properties under very demanding
conditions of speed, temperature, and pressure. Changes in a
fluid's frictional properties as a function of relative sliding
speed, temperature, or pressure may cause performance degradation
immediately noticeable to the vehicle operator. Such effects may
include unacceptably long or short gear shifts, vehicle shudder or
vibration, noise, and/or harsh shifts ("gear change shock"). Thus,
there is a need for transmission fluids that exhibit improved
characteristics such as shear stability at high temperatures and
pressures. Such fluids would reduce equipment and performance
problems while improving the interval between fluid changes. By
enabling smooth engagement of torque converter and shifting
clutches, these fluids may reduce shudder, vibration, and/or noise,
and in some cases improve fuel economy, over a longer fluid
lifetime.
[0006] Friction modifiers are used in automatic transmission fluids
to decrease friction between surfaces (e.g., the members of a
torque converter clutch or a shifting clutch) at low sliding
speeds. The result is a friction vs. velocity (u-v) curve that has
a positive slope, which in turn leads to smooth clutch engagements
and minimizes "stick-slip" behavior (e.g., shudder, noise, and
harsh shifts). Many conventional friction modifiers, however, are
thermally unstable. Upon prolonged exposure to heat, these
additives decompose, and the benefits they confer on clutch
performance may be lost.
SUMMARY OF THE EMBODIMENTS
[0007] Power transmission fluids formulated according to the
present disclosure provide improved shear stability, thereby
providing improved performance for smooth engagement of torque
converter and shifting clutches and minimized shudder, vibration
and/or noise, and/or improved fuel economy.
[0008] In an embodiment, a power transmission fluid composition
having improved characteristics is provided. The fluid includes a
base oil and an additive composition including a viscosity index
improving amount of a polyisoalkylene component having a molecular
weight ranging from about 300 to about 10,000 weight average
molecular weight as determined by gel permeation chromatography.
The power transmission fluid exhibits a kinematic viscosity (KV at
160.degree. C.) of less than about 9 centistokes and a Brookfield
viscosity (BV at -40.degree. C.) of less than about 30,000
centipoise. Also, a friction versus velocity curve for the fluid
has a more positive slope at high speeds compared to similar fluids
in the absence of the polyisoalkylene component.
[0009] Another embodiment provides a method of improving shear
stability for a transmission fluid. The method includes providing a
base oil and adding to the base oil an additive composition to
provide a transmission fluid. The transmission fluid may contain
from about 1 to about 9 weight percent (wt %) of a polyisoalkylene
component having a molecular weight ranging from about 300 to about
10,000 weight average molecular weight as determined by gel
permeation chromatography. Or, stated alternatively, the additive
composition may contain about 10 to about 90 wt % of the
polyisoalkylene component. The base oil containing the additive
composition may exhibit a kinematic viscosity (KV at 100.degree.
C.) of less than about 9 centistokes and a Brookfield viscosity (BV
at -40.degree. C.) of less than about 30,000 centipoise. Also, a
friction versus velocity curve for the oil and additive composition
has a more positive slope at high speeds compared to similar fluids
in the absence of the polyisoalkylene component.
[0010] Yet another embodiment provides an additive concentrate for
a transmission fluid. The additive concentrate includes at least a
first viscosity index improving thickening agent and a second
viscosity index improving thickening agent. The first thickening
agent is a polyisoalkylene having a molecular weight ranging from
about 500 to about 10,000 weight average molecular weight as
determined by gel permeation chromatography. The second thickening
agent is selected from polymethacrylates, olefin copolymers, and
styrene-maleic esters. A total amount of the first and second
viscosity index improvers present in the additive concentrate may
range from about 10 to about 90 wt % and the balance of the
additive concentrate may comprise from about 5 wt % to about 25 wt
% base oil and from about 0.5 to about 10 wt % other performance
additives. A power transmission fluid containing from about 1 wt %
to about 30 wt % of the additive concentrate may exhibit a
kinematic viscosity (KV at 100.degree. C.) of less than about 9
centistokes and a Brookfield viscosity (BV at -40.degree. C.) of
less than about 30,000 centipoise. Also, a friction versus velocity
curve for the fluid has a more positive slope at high speeds
compared to similar fluids in the absence of the polyisoalkylene
component.
[0011] Power transmission fluids of the foregoing embodiments are
formulated to deliver improved shear stability, allowing the fluid
to change very little when the fluid is subjected to mechanical,
thermal, and/or oxidative stresses. Such power transmission fluids
are suitable for use in transmissions where high stressing of the
lubricant is routine, such as transmissions with a slipping torque
converter, a lock-up torque converter, a starting clutch, and/or
one or more shifting clutches. Such transmissions may include
four-, five-, six-, or seven-speed transmissions, or may include
continuously variable transmissions (chain, belt, and disk type).
They may also be used in manual transmissions, including automated
manual and dual-clutch transmissions. A particular advantage of the
fluids described herein is their improved characteristics with
respect to transmissions containing advanced friction materials
such as carbon fiber friction plates.
[0012] Both the foregoing general description and the following
detailed description are exemplary and explanatory only and are
intended to provide further explanation of the present invention,
as claimed.
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIG. 1 illustrates the u-v friction profile of transmission
fluids containing various viscosity index improvers.
DETAILED DESCRIPTION OF EMBODIMENTS
[0014] As used herein, the term "hydrocarbyl substituent" or
"hydrocarbyl group" is used in its ordinary sense, which is
well-known to those skilled in the art. Specifically, it refers to
a group having a carbon atom directly attached to the remainder of
a molecule and having a predominantly hydrocarbon character.
Examples of hydrocarbyl groups include:
[0015] (1) hydrocarbon substituents, that is, aliphatic (e.g.,
alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl)
substituents, and aromatic-, aliphatic-, and alicyclic-substituted
aromatic substituents, as well as cyclic substituents wherein the
ring is completed through another portion of the molecule (e.g.,
two substituents together form an alicyclic radical);
[0016] (2) substituted hydrocarbon substituents, that is,
substituents containing non-hydrocarbon groups which, in the
context of the description herein, do not alter the predominantly
hydrocarbon substituent (e.g., halo (especially chloro and fluoro),
hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and
sulfoxy);
[0017] (3) hetero-substituents, that is, substituents which, while
having a predominantly hydrocarbon character, in the context of
this description, contain other than carbon in a ring or chain
otherwise composed of carbon atoms. Hetero-atoms include sulfur,
oxygen, nitrogen, and encompass substituents such as pyridyl,
furyl, thienyl, and imidazolyl. In general, no more than two, or as
a further example, no more than one, non-hydrocarbon substituent
will be present for every ten carbon atoms in the hydrocarbyl
group; typically, there will be one non-hydrocarbon substituent in
the hydrocarbyl group.
[0018] As power transmission fluids operate under increasingly
severe conditions, the oils used to lubricate those transmissions
should be formulated to endure higher temperatures and pressures.
To reduce equipment problems and increase the interval between
transmission oil changes, the oil additive packages should be
formulated so that important oil properties change as little as
possible in the face of these stresses. In particular, the shear
stability properties of the oil, which depend in great measure on
the additive package, should stay relatively constant over a wide
range of temperatures and operating speeds. This ensures smooth
engagement of torque converter and shifting clutches and minimized
shudder, vibration and noise, and improved fuel economy. It has
been found that the components herein disclosed, when blended into
a base oil, impart to that oil greatly improved shear
stability.
[0019] In an embodiment, a power transmission fluid may include a
base oil and an additive composition. The additive composition
includes a viscosity index improving amount of a polyisoalkylene
component. The polyisoalkylene component may have a molecular
weight ranging from about 300 to about 10,000 weight average
molecular weight as determined by gel permeation chromatography. As
a further example, the polyisoalkylene component may have a
molecular weight ranging from about 500 to about 3000 weight
average molecular weight. And as an even further example, the
polyisoalkylene component may have a molecular weight ranging from
about 700 to about 2500 weight average molecular weight. When used
in a viscosity index improving amount the polyisoalkylene component
provides a power transmission fluid with a kinematic viscosity (KV
at 100.degree. C.) of less than about 9 centistokes (cSt) and a
Brookfield viscosity (BV at -40.degree. C.) of less than about
30,000 centipoise (cp). A friction versus velocity curve for the
fluid exhibits a positive slope at high speeds compared to a
similar fluid in the absence of the polyisoalkylene component. Of
the polyisoalkylene components, examples include
poly(C.sub.3-C.sub.6)isoalkylene components such as
polyisobutylene.
[0020] The polyisoalkylene component may be derived from olefinic
hydrocarbon monomers such as isobutene made by cracking a
hydrocarbon stream to produce a hydrocarbon mixture of essentially
C.sub.4-hydrocarbons. For example, thermocracking processes
(streamcracker) produce C.sub.4 cuts having C.sub.4 paraffins and
C.sub.4 olefins, with a major component being isobutene. Butadiene
and acetylene are substantially removed from the stream by
additional selective hydrogenation or extractive distillation
techniques.
[0021] A polymerization reaction used to form a polyisoalkylene
component from its monomers is generally carried out in the
presence of a conventional Ziegler-Natta or metallocene catalyst
system. The polymerization medium can include solution, slurry, or
gas phase processes, as known to those skilled in the art. When
solution polymerization is employed, the solvent may be any
suitable inert hydrocarbon solvent that is liquid under reaction
conditions for polymerization of alpha-olefins; examples of
satisfactory hydrocarbon solvents include straight chain paraffins
having from 5 to 8 carbon atoms, such as hexane. Aromatic
hydrocarbons, aromatic hydrocarbons having a single benzene
nucleus, such as benzene and toluene; and saturated cyclic
hydrocarbons having boiling point ranges approximating those of the
straight chain paraffinic hydrocarbons and aromatic hydrocarbons
described above, are suitable. The solvent selected may be a
mixture of one or more of the foregoing hydrocarbons. When slurry
polymerization is employed, the liquid phase for polymerization may
be liquid propylene. It is desirable that the polymerization medium
be free of substances that will interfere with the catalyst
components. The polymerization process may be terminated when a
polyisoalkylene compound having a weight average molecular weight
ranging, for example, from about 300 to about 10,000, from about
700 to about 5,000, or from about 700 to about 2,500 is
obtained.
[0022] A linear version of the polyalkylene component may be used
in addition to or in the alternative to the isomerized component
discussed herein.
[0023] A viscosity index improving amount of polyisoalkylene
component may be present in a power transmission fluid in an amount
from about 1 to about 30 wt % of the total weight of the
transmission fluid. As a further example, the polyisoalkylene
component may be present in an amount of about 2 wt % to about 9 wt
% in the transmission fluid.
[0024] While a suitable transmission fluid may be provided with the
polyisoalkylene component as the sole viscosity index improver,
embodiments may also include a combination of viscosity index
improvers. For example, non-dispersant viscosity index improvers
may be used in combination with the foregoing polyisoalkylene
viscosity index improver. Such non-dispersant viscosity index
improvers include, but are not limited to, olefin copolymers,
polyalkylmethacrylates, and styrene-maleic esters. The viscosity
index improver may be supplied in the form of a solution in an
inert solvent, typically a mineral oil solvent, which usually is a
severely refined mineral oil.
[0025] Suitable commercially available materials for use as
viscosity index improvers in combination with the polyisoalkylene
component include styrene-maleic esters such as are available under
the trade designation LUBRIZOL.RTM. 3702, LUBRIZOL.RTM. 3706 and
LUBRIZOL.RTM. 3715 available from The Lubrizol Corporation;
polyalkylmethacrylates such as those available from ROHM GmbH
(Darmstadt, Germany) under the trade designations: VISCOPLEX.RTM.
5543, VISCOPLEX.RTM. 5548, VISCOPLEX.RTM. 5549, VISCOPLEX.RTM.
5550, VISCOPLEX.RTM. 5551 and VISCOPLEX.RTM. 5151, from Rohm &
Haas Company (Philadelphia, Pa.) under the trade designations
ACRYLOID.RTM. 1277, ACRYLOID.RTM. 1265 and ACRYLOID.RTM. 1269, and
from Ethyl Corporation (Richmond, Va.) under the trade designation
HiTEC.RTM. 5710, HiTEC.RTM. 5738, HiTEC.RTM. 5739, and HiTEC.RTM.
5742; and olefin copolymer viscosity index improvers such as
HiTEC.RTM. 5747, HiTEC.RTM. 5751, HiTEC.RTM. 5770, and HiTEC.RTM.
5772, available from Ethyl Corporation and SHELLVIS.RTM. 200
available from Shell Chemical Company. Mixtures of the foregoing
products can also be used as well as dispersant and
dispersant-antioxidant viscosity index improvers.
[0026] Base Oil
[0027] Base oils suitable for use in formulating transmission fluid
compositions may be selected from any of the synthetic or natural
oils or mixtures thereof. Natural oils include animal oils and
vegetable oils (e.g., castor oil, lard oil) as well as mineral
lubricating oils such as liquid petroleum oils and solvent treated
or acid-treated mineral lubricating oils of the paraffinic,
naphthenic or mixed paraffinic-naphthenic types. Oils derived from
coal or shale are also suitable. The base oil typically has a
viscosity of about 2 to about 15 cSt or, as a further example,
about 2 to about 10 cSt at 100.degree. C. Further, gas-to-liquid
stocks are also suitable.
[0028] The synthetic base oils include alkyl esters of dicarboxylic
acids, polyglycols and alcohols, poly-alpha-olefins, including
polybutenes, alkyl benzenes, organic esters of phosphoric acids,
and polysilicone oils. Synthetic oils include hydrocarbon oils such
as polymerized and interpolymerized olefins (e.g., polybutylenes,
polypropylenes, propylene isobutylene copolymers, etc.);
poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and
mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes,
tetradecylbenzenes, di-nonylbenzenes, di-(2-ethylhexyl)benzenes,
etc.); polyphenyls (e.g., biphenyls, terphenyl, alkylated
polyphenyls, etc.); alkylated diphenyl ethers and alkylated
diphenyl sulfides and the derivatives, analogs and homologs thereof
and the like.
[0029] Alkylene oxide polymers and interpolymers and derivatives
thereof where the terminal hydroxyl groups have been modified by
esterification, etherification, etc., constitute another class of
known synthetic oils that may be used. Such oils are exemplified by
the oils prepared through polymerization of ethylene oxide or
propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene
polymers (e.g., methyl-polyisopropylene glycol ether having an
average molecular weight of about 1000, diphenyl ether of
polyethylene glycol having a molecular weight of about 500-1000,
diethyl ether of polypropylene glycol having a molecular weight of
about 1000-1500, etc.) or mono- and polycarboxylic esters thereof,
for example, the acetic acid esters, mixed C.sub.3-8 fatty acid
esters, or the C.sub.13 Oxo acid diester of tetraethylene
glycol.
[0030] Another class of synthetic oils that may be used includes
the esters of dicarboxylic acids (e.g., phthalic acid, succinic
acid, alkyl succinic acids, alkenyl succinic acids, maleic acid,
azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic
acid, linoleic acid dimer, malonic acid, alkyl malonic acids,
alkenyl malonic acids, etc.) with a variety of alcohols (e.g.,
butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl
alcohol, ethylene glycol, diethylene glycol monoether, propylene
glycol, etc.) Specific examples of these esters include dibutyl
adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl
sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl
phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl
diester of linoleic acid dimer, the complex ester formed by
reacting one mole of sebacic acid with two moles of tetraethylene
glycol and two moles of 2-ethylhexanoic acid and the like.
[0031] Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol
ethers such as neopentyl glycol, trimethylol propane,
pentaerythritol, dipentaerythritol, tripentaerythritol, etc.
[0032] Hence, the base oil used which may be used to make the
transmission fluid compositions as described herein may be selected
from any of the base oils in Groups I-V as specified in the
American Petroleum Institute (API) Base Oil Interchangeability
Guidelines. Such base oil groups are as follows:
1 Saturates Base Oil Group.sup.1 Sulfur (wt %) (wt %) Viscosity
Index Group I >0.03 and/or <90 80 to 120 Group II
.ltoreq.0.03 And .gtoreq.90 80 to 120 Group III .ltoreq.0.03 And
.gtoreq.90 .gtoreq.120 Group IV all polyalphaolefins (PAOs) Group V
all others not included in Groups I-IV .sup.1Groups I-III are
mineral oil base stocks.
[0033] As set forth above, the base oil may be a poly-alpha-olefin
(PAO). Typically, the poly-alpha-olefins are derived from monomers
having from about 4 to about 30, or from about 4 to about 20, or
from about 6 to about 16 carbon atoms. Examples of useful PAOs
include those derived from octene, decene, mixtures thereof, and
the like. PAOs may have a viscosity of from about 2 to about 15, or
from about 3 to about 12, or from about 4 to about 8 cSt at
100.degree. C. Examples of PAOs include 4 cSt at 100.degree. C.
poly-alpha-olefins, 6 cSt at 100.degree. C. poly-alpha-olefins, and
mixtures thereof. Mixtures of mineral oil with the foregoing
poly-alpha-olefins may be used.
[0034] The base oil may be an oil derived from Fischer-Tropsch
synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons
are made from synthesis gas containing H.sub.2 and CO using a
Fischer-Tropsch catalyst. Such hydrocarbons typically require
further processing in order to be useful as the base oil. For
example, the hydrocarbons may be hydroisomerized using processes
disclosed in U.S. Pat. No. 6,103,099 or 6,180,575; hydrocracked and
hydroisomerized using processes disclosed in U.S. Pat. No.
4,943,672 or 6,096,940; dewaxed using processes disclosed in U.S.
Pat. No. 5,882,505; or hydroisomerized and dewaxed using processes
disclosed in U.S. Pat. Nos. 6,013,171; 6,080,301; or 6,165,949.
[0035] Unrefined, refined and rerefined oils, either natural or
synthetic (as well as mixtures of two or more of any of these) of
the type disclosed hereinabove can be used in the base oils.
Unrefined oils are those obtained directly from a natural or
synthetic source without further purification treatment. For
example, a shale oil obtained directly from retorting operations, a
petroleum oil obtained directly from primary distillation or ester
oil obtained directly from an esterification process and used
without further treatment would be an unrefined oil. Refined oils
are similar to the unrefined oils except they have been further
treated in one or more purification steps to improve one or more
properties. Many such purification techniques are known to those
skilled in the art such as solvent extraction, secondary
distillation, acid or base extraction, filtration, percolation,
etc. Rerefined oils are obtained by processes similar to those used
to obtain refined oils applied to refined oils which have been
already used in service. Such rerefined oils are also known as
reclaimed or reprocessed oils and often are additionally processed
by techniques directed to removal of spent additives, contaminants,
and oil breakdown products.
[0036] The base oil may be combined with an additive composition as
disclosed in embodiments herein to provide a power transmission
fluid. The base oil may be present in the power transmission fluid
in an amount from about 50 wt % to about 95 wt %.
[0037] Other Optional Components
[0038] The power transmission fluid may also include conventional
additives of the type used in automatic transmission fluid
formulations in addition to the components described above. Such
additives include, but are not limited to, ashless dispersants,
friction modifiers, antioxidants, extreme pressure additives,
corrosion inhibitors, antiwear additives, antirust additives, metal
deactivators, antifoamants, pour point depressants, air entrainment
additives, metallic detergents, and/or seal swell agents.
[0039] Ashless Dispersants
[0040] The ashless dispersant which may be used in the transmission
fluids as described herein may be selected from any of the ashless
dispersants known to those skilled in the art. Suitable ashless
dispersants may include ashless dispersants such as succinimide
dispersants, Mannich base dispersants, and polymeric polyamine
dispersants. Hydrocarbyl-substituted succinic acylating agents are
used to make hydrocarbyl-substituted succinimides. The
hydrocarbyl-substituted succinic acylating agents include, but are
not limited to, hydrocarbyl-substituted succinic acids,
hydrocarbyl-substituted succinic anhydrides, the
hydrocarbyl-substituted succinic acid halides (especially the acid
fluorides and acid chlorides), and the esters of the
hydrocarbyl-substituted succinic acids and lower alcohols (e.g.,
those containing up to 7 carbon atoms), that is,
hydrocarbyl-substituted compounds which can function as carboxylic
acylating agents.
[0041] Hydrocarbyl substituted acylating agents are made by
reacting a polyolefin or chlorinated polyolefin of appropriate
molecular weight with maleic anhydride. Similar carboxylic
reactants can be used to make the acylating agents. Such reactants
may include, but are not limited to, maleic acid, fumaric acid,
malic acid, tartaric acid, itaconic acid, itaconic anhydride,
citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic
anhydride, dimethylmaleic anhydride, ethylmaleic acid,
dimethylmaleic acid, hexylmaleic acid, and the like, including the
corresponding acid halides and lower aliphatic esters.
[0042] The molecular weight of the olefin can vary depending upon
the intended use of the substituted succinic anhydrides. Typically,
the substituted succinic anhydrides will have a hydrocarbyl group
of from 8-500 carbon atoms. However, substituted succinic
anhydrides used to make lubricating oil dispersants will typically
have a hydrocarbyl group of about 40-500 carbon atoms. Dispersants
having a hydrocarbyl group containing from about 8 to about 150
carbon atoms are referred to herein as "relatively low molecular
weight dispersants." Whereas dispersants having a hydrocarbyl group
containing more than about 150 carbon atoms up to about 500 carbon
atoms are referred to herein as "relatively high molecular weight
dispersants." With the very high molecular weight substituted
succinic anhydrides, it is more accurate to refer to number average
molecular weight (Mn) since the olefins used to make these
substituted succinic anhydrides may include a mixture of different
molecular weight components resulting from the polymerization of
low molecular weight olefin monomers such as ethylene, propylene
and isobutylene.
[0043] The mole ratio of maleic anhydride to olefin can vary
widely. It may vary, for example, from about 5:1 to about 1:5, or
for example, from about 1:1 to about 3:1. With olefins such as
polyisobutylene having a number average molecular weight of about
500 to about 7000, or as a further example, about 800 to about 3000
or higher and the ethylene-alpha-olefin copolymers, the maleic
anhydride may be used in stoichiometric excess, e.g. 1.1 to 3 moles
maleic anhydride per mole of olefin. The unreacted maleic anhydride
can be vaporized from the resultant reaction mixture.
[0044] Polyalkenyl succinic anhydrides may be converted to
polyalkyl succinic anhydrides by using conventional reducing
conditions such as catalytic hydrogenation. For catalytic
hydrogenation, a suitable catalyst is palladium on carbon.
Likewise, polyalkenyl succinimides may be converted to polyalkyl
succinimides using similar reducing conditions.
[0045] The polyalkyl or polyalkenyl substituent on the succinic
anhydrides employed herein is generally derived from polyolefins
which are polymers or copolymers of mono-olefins, particularly
1-mono-olefins, such as ethylene, propylene and butylene. The
mono-olefin employed may have about 2 to about 24 carbon atoms, or
as a further example, about 3 to about 12 carbon atoms. Other
suitable mono-olefins include propylene, butylene, particularly
isobutylene, 1-octene and 1-decene. Polyolefins prepared from such
mono-olefins include polypropylene, polybutene, polyisobutene, and
the polyalphaolefins produced from 1-octene and 1-decene.
[0046] In some embodiments, the ashless dispersant may include one
or more alkenyl succinimides of an amine having at least one
primary amino group capable of forming an imide group. The alkenyl
succinimides may be formed by conventional methods such as by
heating an alkenyl succinic anhydride, acid, acid-ester, acid
halide, or lower alkyl ester with an amine containing at least one
primary amino group. The alkenyl succinic anhydride may be made
readily by heating a mixture of polyolefin and maleic anhydride to
about 180.degree.-220.degree. C. The polyolefin may be a polymer or
copolymer of a lower monoolefin such as ethylene, propylene,
isobutene and the like, having a number average molecular weight in
the range of about 300 to about 3000 as determined by gel
permeation chromatography (GPC).
[0047] Amines which may be employed in forming the ashless
dispersant include any that have at least one primary amino group
which can react to form an imide group and at least one additional
primary or secondary amino group and/or at least one hydroxyl
group. A few representative examples are: N-methyl-propanediamine,
N-dodecylpropanediamine, N-aminopropyl-piperazine, ethanolamine,
N-ethanol-ethylenediamine, and the like.
[0048] Suitable amines may include alkylene polyamines, such as
propylene diamine, dipropylene triamine, di-(1,2-butylene)triamine,
and tetra-(1,2-propylene)pentamine. A further example includes the
ethylene polyamines which can be depicted by the formula
H.sub.2N(CH.sub.2CH.sub.2- NH).sub.nH, wherein n may be an integer
from about one to about ten. These include: ethylene diamine,
diethylene triamine (DETA), triethylene tetramine (TETA),
tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA), and
the like, including mixtures thereof in which case n is the average
value of the mixture. Such ethylene polyamines have a primary amine
group at each end so they may form mono-alkenylsuccinimides and
bis-alkenylsuccinimides. Commercially available ethylene polyamine
mixtures may contain minor amounts of branched species and cyclic
species such as N-aminoethyl piperazine,
N,N'-bis(aminoethyl)piperazine, N,N'-bis(piperazinyl)ethane, and
like compounds. The commercial mixtures may have approximate
overall compositions falling in the range corresponding to
diethylene triamine to tetraethylene pentamine. The molar ratio of
polyalkenyl succinic anhydride to polyalkylene polyamines may be
from about 1:1 to about 3.0:1.
[0049] In some embodiments, the ashless dispersant may include the
products of the reaction of a polyethylene polyamine, e.g.
triethylene tetramine or tetraethylene pentamine, with a
hydrocarbon substituted carboxylic acid or anhydride made by
reaction of a polyolefin, such as polyisobutene, of suitable
molecular weight, with an unsaturated polycarboxylic acid or
anhydride, e.g., maleic anhydride, maleic acid, fumaric acid, or
the like, including mixtures of two or more such substances.
[0050] Polyamines that are also suitable in preparing the
dispersants described herein include N-arylphenylenediamines, such
as N-phenylphenylenediamines, for example,
N-phenyl-1,4-phenylenediamine, N-phenyl-1,3-phenylendiamine, and
N-phenyl-1,2-phenylenediamine; aminothiazoles such as
aminothiazole, aminobenzothiazole, aminobenzothiadiazole and
aminoalkylthiazole; aminocarbazoles; aminoindoles; aminopyrroles;
amino-indazolinones; aminomercaptotriazoles; aminoperimidines;
aminoalkyl imidazoles, such as 1-(2-aminoethyl) imidazole,
1-(3-aminopropyl) imidazole; and aminoalkyl morpholines, such as
4-(3-aminopropyl) morpholine. These polyamines are described in
more detail in U.S. Pat. Nos. 4,863,623 and 5,075,383. Such
polyamines can provide additional benefits, such as anti-wear and
antioxidancy, to the final products.
[0051] Additional polyamines useful in forming the
hydrocarbyl-substituted succinimides include polyamines having at
least one primary or secondary amino group and at least one
tertiary amino group in the molecule as taught in U.S. Pat. Nos.
5,634,951 and 5,725,612. Examples of suitable polyamines include
N,N,N",N"-tetraalkyldialkylenetriamines (two terminal tertiary
amino groups and one central secondary amino group),
N,N,N',N"-tetraalkyltrialkylenetetramines (one terminal tertiary
amino group, two internal tertiary amino groups and one terminal
primary amino group), N,N,N',N",N'"-pentaalkyltrialkylenetetramines
(one terminal tertiary amino group, two internal tertiary amino
groups and one terminal secondary amino group),
tris(dialkylaminoalkyl)aminoalkylmethanes (three terminal tertiary
amino groups and one terminal primary amino group), and like
compounds, wherein the alkyl groups are the same or different and
typically contain no more than about 12 carbon atoms each, and
which preferably contain from 1 to 4 carbon atoms each. Most
preferably these alkyl groups are methyl and/or ethyl groups.
Polyamine reactants of this type may include
dimethylaminopropylamine (DMAPA) and N-methyl piperazine.
[0052] Hydroxyamines suitable for herein include compounds,
oligomers or polymers containing at least one primary or secondary
amine capable of reacting with the hydrocarbyl-substituted succinic
acid or anhydride. Examples of hydroxyamines suitable for use
herein include aminoethylethanolamine (AEEA),
aminopropyldiethanolamine (APDEA), ethanolamine, diethanolamine
(DEA), partially propoxylated hexamethylene diamine (for example
HMDA-2PO or HMDA-3PO), 3-amino-1,2-propanediol,
tris(hydroxymethyl)aminomethane, and 2-amino-1,3-propanediol.
[0053] The mole ratio of amine to hydrocarbyl-substituted succinic
acid or anhydride may range from 1:1 to about 3.0:1. Another
example of a mole ratio of amine to hydrocarbyl-substituted
succinic acid or anhydride may range from about 1.5:1 to about
2.0:1.
[0054] The foregoing dispersant may also be a post-treated
dispersant made, for example, by treating the dispersant with
maleic anhydride and boric acid as described, for example, in U.S.
Pat. No. 5,789,353 to Scattergood, or by treating the dispersant
with nonylphenol, formaldehyde and glycolic acid as described, for
example, in U.S. Pat. No. 5,137,980 to DeGonia, et al.
[0055] The Mannich base dispersants may be a reaction product of an
alkyl phenol, typically having a long chain alkyl substituent on
the ring, with one or more aliphatic aldehydes containing from 1 to
about 7 carbon atoms (especially formaldehyde and derivatives
thereof), and polyamines (especially polyalkylene polyamines). For
example, a Mannich base ashless dispersants may be formed by
condensing about one molar proportion of long chain
hydrocarbon-substituted phenol with from about 1 to about 2.5 moles
of formaldehyde and from about 0.5 to about 2 moles of polyalkylene
polyamine.
[0056] Hydrocarbon sources for preparation of the Mannich polyamine
dispersants may be those derived from substantially saturated
petroleum fractions and olefin polymers, such as polymers of
mono-olefins having from 2 to about 6 carbon atoms. The hydrocarbon
source generally contains, for example, at least about 40 carbon
atoms, and as a further example, at least about 50 carbon atoms to
provide substantial oil solubility to the dispersant. The olefin
polymers having a GPC number average molecular weight between about
600 and 5,000 are suitable for reasons of easy reactivity and low
cost. However, polymers of higher molecular weight can also be
used. Especially suitable hydrocarbon sources are isobutylene
polymers and polymers made from a mixture of isobutene and a
raffinate I stream.
[0057] Suitable Mannich base dispersants may be Mannich base
ashless dispersants formed by condensing about one molar proportion
of long chain hydrocarbon-substituted phenol with from about 1 to
2.5 moles of formaldehyde and from about 0.5 to 2 moles of
polyalkylene polyamine.
[0058] Polymeric polyamine dispersants suitable as the ashless
dispersants are polymers containing basic amine groups and oil
solubilizing groups (for example, pendant alkyl groups having at
least about 8 carbon atoms). Such materials are illustrated by
interpolymers formed from various monomers such as decyl
methacrylate, vinyl decyl ether or relatively high molecular weight
olefins, with aminoalkyl acrylates and aminoalkyl acrylamides.
Examples of polymeric polyamine dispersants are set forth in U.S.
Pat. Nos. 3,329,658; 3,449,250; 3,493,520; 3,519,565; 3,666,730;
3,687,849; and 3,702,300. Polymeric polyamines may include
hydrocarbyl polyamines wherein the hydrocarbyl group is composed of
the polymerization product of isobutene and a raffinate I stream as
described above. PIB-amine and PIB-polyamines may also be used.
[0059] Methods for the production of ashless dispersants as
described above are known to those skilled in the art and are
reported in the patent literature. For example, the synthesis of
various ashless dispersants of the foregoing types is described in
such patents as U.S. Pat. Nos. 2,459,112; 2,962,442, 2,984,550;
3,036,003; 3,163,603; 3,166,516; 3,172,892; 3,184,474; 3,202,678;
3,215,707; 3,216,936; 3,219,666; 3,236,770; 3,254,025; 3,271,310;
3,272,746; 3,275,554; 3,281,357; 3,306,908; 3,311,558; 3,316,177;
3,331,776; 3,340,281; 3,341,542; 3,346,493; 3,351,552; 3,355,270;
3,368,972; 3,381,022; 3,399,141; 3,413,347; 3,415,750; 3,433,744;
3,438,757; 3,442,808; 3,444,170; 3,448,047; 3,448,048; 3,448,049;
3,451,933; 3,454,497; 3,454,555; 3,454,607; 3,459,661; 3,461,172;
3,467,668; 3,493,520; 3,501,405; 3,522,179; 3,539,633; 3,541,012;
3,542,680; 3,543,678; 3,558,743; 3,565,804; 3,567,637; 3,574,101;
3,576,743; 3,586,629; 3,591,598; 3,600,372; 3,630,904; 3,632,510;
3,632,511; 3,634,515; 3,649,229; 3,697,428; 3,697,574; 3,703,536;
3,704,308; 3,725,277; 3,725,441; 3,725,480; 3,726,882; 3,736,357;
3,751,365; 3,756,953; 3,793,202; 3,798,165; 3,798,247; 3,803,039;
3,804,763; 3,836,471; 3,862,981; 3,872,019; 3,904,595; 3,936,480;
3,948,800; 3,950,341; 3,957,746; 3,957,854; 3,957,855; 3,980,569;
3,985,802; 3,991,098; 4,006,089; 4,011,380; 4,025,451; 4,058,468;
4,071,548; 4,083,699; 4,090,854; 4,173,540; 4,234,435; 4,354,950;
4,485,023; 5,137,980, and Re 26,433, herein incorporated by
reference.
[0060] An example of a suitable ashless dispersant is a borated
dispersant. Borated dispersants may be formed by boronating
(borating) an ashless dispersant having basic nitrogen and/or at
least one hydroxyl group in the molecule, such as a succinimide
dispersant, succinamide dispersant, succinic ester dispersant,
succinic ester-amide dispersant, Mannich base dispersant, or
hydrocarbyl amine or polyamine dispersant.
[0061] The borated dispersant may contain at least one polyalkylene
moiety. As a further example, the borated dispersant, may include
at least two polyalkylene moieties. The polyalkylene moiety may
have a molecular weight of from about 300 weight average molecular
weight to about 3000 weight average molecular weight. The
polyalkylene moiety, for example, may have a molecular weight of
from about 1300 weight average molecular weight to about 2100
weight average molecular weight. As a further example, the
polyalkylene moiety may have a molecular weight of about 2100
weight average molecular weight. The polyalkylene moiety may
include a polybutenyl group. Methods that can be used for
boronating the various types of ashless dispersants described above
are described in U.S. Pat. Nos. 3,087,936; 3,254,025; 3,281,428;
3,282,955; 2,284,409; 2,284,410; 3,338,832; 3,344,069; 3,533,945;
3,658,836; 3,703,536; 3,718,663; 4,455,243; and 4,652,387.
[0062] The borated dispersant may include a high molecular weight
dispersant treated with boron such that the borated dispersant
includes up to 2 wt % of boron. As another example the borated
dispersant may include from about 0.8 wt % or less of boron. As a
further example, the borated dispersant may include from about 0.1
to about 0.7 wt % of boron. As an even further example, the borated
dispersant may include from about 0.25 to about 0.7 wt % of boron.
As a further example, the borated dispersant may include from about
0.35 to about 0.7 wt % of boron. The dispersant may be dissolved in
oil of suitable viscosity for ease of handling. It should be
understood that the weight percentages given here are for neat
dispersant, without any diluent oil added.
[0063] A dispersant may be further reacted with an organic acid, an
anhydride, and/or an aldehyde/phenol mixture. Such a process may
enhance compatibility with elastomer seals, for example. The
borated dispersant may further include a mixture of borated
dispersants. As a further example, the borated dispersant may
include a nitrogen-containing dispersant and/or may be free of
phosphorus.
[0064] A suitable dispersant may be a phosphorylated dispersant.
For example, a Mannich or a succinimide dispersant may be reacted
with a phosphorous compound, such as a phosphorous-containing acid.
Suitable phosphorous-containing acids include, for example,
phosphorous acid (H.sub.3PO.sub.3), dibutyl hydrogen phosphite
(DBHP), dialkyldithiophosphoric acids, and the like. Further, a
succinimide dispersant, such as a polyisobutylene succinic
anhydride, may be phosphorylated and/or boronated to provide a
suitable dispersant.
[0065] A dispersant may be present in the power transmission fluid
in an amount of about 0.1 wt % to about 10 wt %. Further, the power
transmission fluid may include from about 2 wt % to about 7 wt % of
the dispersant. Further, the power transmission fluid may include
from about 3 wt % to about 5 wt % of the dispersant. Further, the
power transmission fluid may include an amount of a borated
dispersant sufficient to provide up to 1900 parts per million (ppm)
by weight of boron in the finished fluid, such as for example, from
about 50 to about 500 ppm by weight of boron in the finished
fluid.
[0066] Antiwear Agents
[0067] The antiwear agents may include phosphorus-containing
antiwear agents which may include an organic ester of phosphoric
acid, phosphorous acid, or an amine salt thereof. For example, the
phosphorus-containing antiwear agent may include one or more of a
dihydrocarbyl phosphite, a trihydrocarbyl phosphite, a
dihydrocarbyl phosphate, a trihydrocarbyl phosphate, any sulfur
analogs thereof, and any amine salts thereof. As a further example,
the phosphorus-containing antiwear agent may include at least one
of dibutyl hydrogen phosphite (such as HiTEC.RTM. 528 antiwear
agent available from Ethyl Corporation) and an amine salt of
sulfurized dibutyl hydrogen phosphite (such as HiTEC.RTM. 833
antiwear agent available from Ethyl Corporation).
[0068] The phosphorus-containing antiwear agent may be present in
an amount sufficient to provide about 50 to about 500 parts per
million by weight of phosphorus in the power transmission fluid. As
a further example, the phosphorus-containing antiwear agent may be
present in an amount sufficient to provide about 150 to about 300
parts per million by weight of phosphorus in the power transmission
fluid.
[0069] The power transmission fluid may include from about 0.01 wt
% to about 1.0 wt % of the phosphorus-containing antiwear agent. As
a further example, the power transmission fluid may include from
about 0.2 wt % to about 0.3 wt % of the phosphorus-containing
antiwear agent. As an example, the power transmission fluid may
include from about 0.1 wt % to about 0.2 wt % of a dibutyl hydrogen
phosphite or 0.3 wt % to about 0.4 wt % an amine salt of a
sulfurized dibutyl hydrogen phosphate.
[0070] Friction Modifiers
[0071] Friction modifiers are used in automatic transmission fluids
to decrease friction between surfaces (e.g., the members of a
torque converter clutch or a shifting clutch) at low sliding
speeds. The result is a function-vs.-velocity (u-v) curve that has
a positive slope, which in turn leads to smooth clutch engagements
and minimizes "stick-slip" behavior (e.g., shudder, noise, and
harsh shifts). Many conventional organic friction modifiers,
however, are thermally unstable. Upon prolonged exposure to heat,
these additives decompose, and the benefits they confer on clutch
performance are lost. The friction-modifying succinimides of the
present disclosure show unusual thermal stability. Compositions
containing this friction modifier show little change in friction
behavior upon thermal stressing.
[0072] Friction modifiers include such compounds as aliphatic
amines or ethoxylated aliphatic amines, ether amines, alkoxylated
ether amines, aliphatic fatty acid amides, acylated amines,
aliphatic carboxylic acids, aliphatic carboxylic esters, polyol
esters, aliphatic carboxylic ester-amides, imidazolines, tertiary
amines, aliphatic phosphonates, aliphatic phosphates, aliphatic
thiophosphonates, aliphatic thiophosphates, etc., wherein the
aliphatic group usually contains one or more carbon atoms so as to
render the compound suitably oil soluble. As a further example, the
aliphatic group may contain about 8 or more carbon atoms. Also
suitable are aliphatic substituted succinimides formed by reacting
one or more aliphatic succinic acids or anhydrides with ammonia
primary amines.
[0073] The succinimide may include the reaction product of a
succinic anhydride and ammonia or primary amine. The alkenyl group
of the alkenyl succinic acid may be a short chain alkenyl group,
for example, the alkenyl group may include from about 12 to about
36 carbon atoms. Further, the succinimide may include a C.sub.12 to
about C.sub.36 aliphatic hydrocarbyl succinimide. As a further
example, the succinimide may include a C.sub.16 to about C.sub.28
aliphatic hydrocarbyl succinimide. As an even further example, the
succinimide may include a C.sub.18 to about C.sub.24 aliphatic
hydrocarbyl succinimide.
[0074] The succinimide may be prepared from a succinic anhydride
and ammonia as described in European Patent Application No. 0 020
037, herein incorporated by reference. Further, the succinimide may
include HiTEC.RTM. 3191 friction modifier, available from Ethyl
Corporation. In some embodiments, no non-metallic friction modifier
other than the succinimide disclosed herein is included.
[0075] The succinimide may include one or more of a compound having
the following structure: 1
[0076] wherein Z may have the structure: 2
[0077] wherein either R.sup.1 or R.sup.2 may be hydrogen, but not
both, and wherein R.sup.1 and R.sup.2 may be independently straight
or branched chain hydrocarbon groups containing from about 1 to
about 34 carbon atoms such that the total number of carbon atoms in
R.sup.1 and R.sup.2 is from about 11 to about 35; X is an amino
group derived from ammonia or a primary amine; and
[0078] wherein, in addition to or in the alternative, the parent
succinic anhydride may be formed by reacting maleic acid,
anhydride, or ester with an internal olefin containing about 12 to
about 36 carbon atoms, said internal olefin being formed by
isomerizing the olefinic double bond of a linear a-olefin or
mixture thereof to obtain a mixture of internal olefins. The
reaction may involve an equimolar amount of ammonia and may be
carried out at elevated temperatures with the removal of water.
[0079] One group of friction modifiers includes the N-aliphatic
hydrocarbyl-substituted diethanol amines in which the N-aliphatic
hydrocarbyl-substituent is at least one straight chain aliphatic
hydrocarbyl group free of acetylenic unsaturation and having in the
range of about 14 to about 20 carbon atoms.
[0080] An example of a suitable friction modifier system is
composed of a combination of at least one N-aliphatic
hydrocarbyl-substituted diethanol amine and at least one
N-aliphatic hydrocarbyl-substituted trimethylene diamine in which
the N-aliphatic hydrocarbyl-substituent is at least one straight
chain aliphatic hydrocarbyl group free of acetylenic unsaturation
and having in the range of about 14 to about 20 carbon atoms.
Further details concerning this friction modifier system are set
forth in U.S. Pat. Nos. 5,372,735 and 5,441,656.
[0081] Another friction modifier system is based on the combination
of (i) at least one di(hydroxyalkyl) aliphatic tertiary amine in
which the hydroxyalkyl groups, being the same or different, each
contain from 2 to about 4 carbon atoms, and in which the aliphatic
group is an acyclic hydrocarbyl group containing from about 10 to
about 25 carbon atoms, and (ii) at least one hydroxyalkyl aliphatic
imidazoline in which the hydroxyalkyl group contains from 2 to
about 4 carbon atoms, and in which the aliphatic group is an
acyclic hydrocarbyl group containing from about 10 to about 25
carbon atoms. For further details concerning this friction modifier
system, reference should be had to U.S. Pat. No. 5,344,579.
[0082] Another suitable group of friction modifiers include
polyolesters, for example, glycerol monooleate (GMO), glycerol
monolaurate (GML), and the like.
[0083] Generally speaking, the compositions may contain up to about
1.25 wt %, or, as a further example, from about 0.05 to about 1 wt
% of one or more friction modifiers.
[0084] Antioxidants
[0085] In some embodiments, antioxidant compounds may be included
in the compositions. Antioxidants include phenolic antioxidants,
aromatic amine antioxidants, sulfurized phenolic antioxidants, and
organic phosphites, among others. Examples of phenolic antioxidants
include 2,6-di-tert-butylphenol, liquid mixtures of tertiary
butylated phenols, 2,6-di-tert-butyl-4-methylphenol,
4,4'-methylenebis(2,6-di-tert-butylphen-
ol),2,2'-methylenebis(4-methyl6-ter t-butylphenol), mixed
methylene-bridged polyalkyl phenols, and
4,4'-thiobis(2-methyl-6-tert-but- ylphenol).
N,N'-di-sec-butyl-phenylenediamine, 4-isopropylaminodiphenylami-
ne, phenyl-.alpha.-naphthyl amine, phenyl-.alpha.-naphthyl amine,
and ring-alkylated diphenylamines. Examples include the sterically
hindered tertiary butylated phenols, bisphenols and cinnamic acid
derivatives and combinations thereof. The amount of antioxidant in
the transmission fluid compositions described herein may range from
about 0.01 to about 3.0 wt % based on the total weight of the fluid
formulation. As a further example, antioxidant may be present in an
amount from about 0.1 wt % to about 1.0 wt %.
[0086] Corrosion Inhibitors
[0087] In some embodiments, copper corrosion inhibitors may
constitute another class of additives suitable for inclusion in the
compositions. Such compounds include thiazoles, triazoles and
thiadiazoles. Examples of such compounds include benzotriazole,
tolyltriazole, octyltriazole, decyltriazole, dodecyltriazole,
2-mercapto benzothiazole, 2,5-dimercapto-1,3,4-thiadiazole,
2-mercapto-5-hydrocarbylthio-1,3,4-thia- diazoles,
2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles,
2,5-bis(hydrocarbylthio)-1,3,4-thiadiazoles, and
2,5-bis(hydrocarbyldithi- o)-1,3,4-thiadiazoles. Suitable compounds
include the 1,3,4-thiadiazoles, a number of which are available as
articles of commerce, and also combinations of triazoles such as
tolyltriazole with a 1,3,5-thiadiazole such as a
2,5-bis(alkyldithio)-1,3,4-thiadiazole. Materials of these types
that are available on the open market include COBRATEC TT-100 and
HiTEC.RTM. 4313 additive (Ethyl Corporation). The
1,3,4-thiadiazoles are generally synthesized from hydrazine and
carbon disulfide by known procedures. See, for example, U.S. Pat.
Nos. 2,765,289; 2,749,311; 2,760,933; 2,850,453; 2,910,439;
3,663,561; 3,862,798; and 3,840,549.
[0088] Rust or corrosion inhibitors are another type of inhibitor
additive for use in embodiments of the present disclosure. Such
materials include monocarboxylic acids and polycarboxylic acids.
Examples of suitable monocarboxylic acids are octanoic acid,
decanoic acid and dodecanoic acid. Suitable polycarboxylic acids
include dimer and trimer acids such as are produced from such acids
as tall oil fatty acids, oleic acid, linoleic acid, or the like.
Products of this type are currently available from various
commercial sources, such as, for example, the dimer and trimer
acids sold under the HYSTRENE trademark by the Humko Chemical
Division of Witco Chemical Corporation and under the EMPOL
trademark by Henkel Corporation. Another useful type of rust
inhibitor may comprise alkenyl succinic acid and alkenyl succinic
anhydride corrosion inhibitors such as, for example,
tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride,
tetradecenylsuccinic acid, tetradecenylsuccinic anhydride,
hexadecenylsuccinic acid, hexadecenylsuccinic anhydride, and the
like. Also useful are the half esters of alkenyl succinic acids
having 8 to 24 carbon atoms in the alkenyl group with alcohols such
as the polyglycols. Other suitable rust or corrosion inhibitors
include ether amines; acid phosphates; amines; polyethoxylated
compounds such as ethoxylated amines, ethoxylated phenols, and
ethoxylated alcohols; imidazolines; aminosuccinic acids or
derivatives thereof, and the like. Materials of these types are
available as articles of commerce. Mixtures of such rust or
corrosion inhibitors can be used. The amount of corrosion inhibitor
in the transmission fluid formulations described herein may range
from about 0.01 to about 2.0 wt % based on the total weight of the
formulation.
[0089] Antifoam Agents
[0090] In some embodiments, a foam inhibitor may form another
component suitable for use in the compositions. Foam inhibitors may
be selected from silicones, polyacrylates, surfactants, and the
like. One suitable acrylic defoamer material is PC-1244 available
from Monsanto Company. The amount of antifoam agent in the
transmission fluid formulations described herein may range from
about 0.01 wt % to about 0.5 wt % based on the total weight of the
formulation. As a further example, antifoam agent may be present in
an amount from about 0.01 wt % to about 0.1 wt %.
[0091] Seal Swell Agents
[0092] The seal swell agent used in the transmission fluid
compositions described herein is selected from oil-soluble
diesters, oil-soluble sulfones, and mixtures thereof. Generally
speaking the most suitable diesters include the adipates, azelates,
and sebacates of C.sub.8-C.sub.13 alkanols (or mixtures thereof),
and the phthalates of C.sub.4-C.sub.13 alkanols (or mixtures
thereof). Mixtures of two or more different types of diesters
(e.g., dialkyl adipates and dialkyl azelates, etc.) can also be
used. Examples of such materials include the n-octyl, 2-ethylhexyl,
isodecyl, and tridecyl diesters of adipic acid, azelaic acid, and
sebacic acid, and the n-butyl, isobutyl, pentyl, hexyl, heptyl,
octyl, nonyl, decyl, undecyl, dodecyl, and tridecyl diesters of
phthalic acid.
[0093] Other esters which may give generally equivalent performance
are polyol esters such as EMERY 2935, 2936, and 2939 esters from
the Emery Group of Henkel Corporation and HATCOL 2352, 2962, 2925,
2938, 2939, 2970, 3178, and 4322 polyol esters from Hatco
Corporation.
[0094] Suitable sulfone seal swell agents are described in U.S.
Pat. Nos. 3,974,081 and 4,029,587. Lubrizol 730 additive (The
Lubrizol Corporation) is understood to be a commercially-available
sulfone type seal swell agent. Typically these products are
employed at levels in the range of about 0.25 wt % to about 5 wt %
in the finished transmission fluid. As a further example, they may
be provided in an amount of about 0.25 wt % to about 1 wt %.
[0095] Suitable seal swell agents are the oil-soluble dialkyl
esters of (i) adipic acid, (ii) sebacic acid, or (iii) phthalic
acid. The adipates and sebacates should be used in amounts in the
range of from about 1 to about 15 wt % in the finished fluid. In
the case of the phthalates, the levels in the transmission fluid
should fall in the range of from about 1.5 to about 10 wt %.
Generally speaking, the higher the molecular weight of the adipate,
sebacate or phthalate, the higher should be the treat rate within
the foregoing ranges.
[0096] Additives used in formulating the compositions described
herein can be blended into the base oil individually or in various
sub-combinations. However, it is suitable to blend all of the
components concurrently using an additive concentrate (i.e.,
additives plus a diluent, such as a hydrocarbon solvent). The use
of an additive concentrate takes advantage of the mutual
compatibility afforded by the combination of ingredients when in
the form of an additive concentrate. Also, the use of a concentrate
reduces blending time and lessens the possibility of blending
errors.
[0097] The power transmission fluids disclosed herein may include
fluids suitable for any power transmitting application, such as a
step automatic transmission or a manual transmission. Further, the
power transmission fluids of the present disclosure are suitable
for use in transmissions with a slipping torque converter, a
lock-up torque converter, a starting clutch, and/or one or more
shifting clutches. Such transmissions include four-, five-, six-,
and seven-speed transmissions, and continuously variable
transmissions (chain, belt, or disk type). They may also be used in
manual transmissions, including automated manual and dual-clutch
transmissions.
[0098] FIG. 1 and the following table illustrates the coefficient
of friction characteristics of transmission fluids on a carbon
fiber friction plate at speeds ranging from 1 to 300 rpm. This
behavior is relevant to the performance of a fluid in a torque
converter clutch. The u-v profiles shown in these figures were
obtained with an SAE No. 2 machine as described in SAE 940821,
herein incorporated by reference. The coefficients of friction were
determined at an applied pressure of 890 kPa, a temperature of
120.degree. C., and a slip time of 2.9 seconds. FIG. 1 and the
following table show the u-v characteristics of baseline fluids
with and without viscosity index improvers (VII's). The fluid
tested include a baseline fluid (ran in duplicate; Baseline 1 and
Baseline 1A) which is an example of the typical ATF, without
viscosity modifier, a description of which, by component type,
follows:
2 Component type wt % in finished fluid friction modifier(s) 0.01
to 0.5 sulfur agent(s) 0.01 to 1.5 anti-oxidant(s) 0.01 to 2.0
anti-rust agent(s) 0.01 to 0.3 anti-wear agent(s) 0.05 to 5.0
detergent(s) 0.01 to 1.0 dispersant(s) 0.5 to 10.0 anti-foam
agent(s) 0.0001 to 0.5 base oil (mineral and/or synthetic)
remaining
[0099] The other fluids in the table and chart contained the
baseline fluid and one of the following thickening agents:
[0100] VII A is polyisobutylene having a number average molecular
weight of 1200.
[0101] VII B is a 2100 MW.sub.N Mannich dispersant.
[0102] VII C is a 2100 MW.sub.N PIBSA plus a polyamine post treated
with nonylphenol, formaldehyde, and glycolic acid and having a
SA/PIB mol ratio of greater than about 1.1.
[0103] VII D is a 1300 MW.sub.N PIBSA plus a polyamine.
[0104] VII E is a 2100 MW.sub.N PIB-phenol Mannich reaction
product.
[0105] VII F is a 2100 MW.sub.N PIBSA plus a polyamine having a
SA/PIB ratio of greater than about 1.1.
3 Baseline VII A VII B VII C VII D VII E VII F RPM Baseline 1 1A @
7.5 wt % @ 6.5 wt % @ 6.5 wt % @ 6.5 wt % @ 6.5 wt % @ 8.0 wt % 1
0.117 0.118 0.12 0.123 0.13 0.138 0.119 0.137 2 0.118 0.119 0.121
0.125 0.131 0.139 0.121 0.14 5 0.12 0.121 0.124 0.129 0.135 0.141
0.125 0.141 10 0.122 0.121 0.124 0.13 0.137 0.141 0.126 0.142 20
0.122 0.122 0.125 0.131 0.137 0.14 0.127 0.141 30 0.122 0.121 0.124
0.13 0.137 0.138 0.126 0.14 40 0.122 0.121 0.124 0.13 0.135 0.137
0.126 0.138 50 0.122 0.121 0.123 0.129 0.135 0.136 0.126 0.138 100
0.122 0.12 0.122 0.127 0.132 0.133 0.124 0.135 200 0.122 0.119
0.122 0.125 0.129 0.13 0.121 0.132 300 0.121 0.117 0.12 0.123 0.126
0.126 0.118 0.129 max - min 0.005 0.005 0.005 0.008 0.011 0.015
0.009 0.013 max - 300 0.001 0.005 0.005 0.008 0.011 0.015 0.009
0.013 100.degree. KV 4.01 4.01 6.32 5.4 5.17 5.2 5.35 5.69 (cSt)
-40.degree. C. B (cP) 17,000 17,000 24,200 22,000 21,000 21,000
14,800 18,900
[0106] As shown by the foregoing table and FIG. 1, a baseline fluid
absent a functionalized dispersant has acceptable coefficient of
friction (u) characteristics over an rpm range of 1 to 300 wherein
the difference between the maximum u and the minimum u is 0.005.
However the kinematic viscosity and the Brookfield viscosity of the
baseline fluid are low. A baseline fluid containing 7.5 w % of the
thickening agent according to the embodiments described herein (VII
A) had a higher kinematic viscosity (KV) and a substantially higher
Brookfield viscosity (BV) than the baseline fluid, however the
difference between the maximum u and the minimum u were the same as
the baseline fluid. This result is compared with the other
thickening agents listed in the table. As can be seen all of the
other thickening agents VII B to VII F had greater differences
between the maximum u and minimum u and lower viscosities than VII
A.
[0107] At numerous places throughout this specification, reference
has been made to a number of U.S. Patents. All such cited documents
are expressly incorporated in full into this disclosure as if fully
set forth herein.
[0108] Other embodiments will be apparent to those skilled in the
art from consideration of the specification and practice of the
invention disclosed herein. As used throughout the specification
and claims, "a" and/or "an" may refer to one or more than one.
Unless otherwise indicated, all numbers expressing quantities of
ingredients, properties such as molecular weight, percent, ratio,
reaction conditions, and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the specification and claims
are approximations that may vary depending upon the desired
properties sought to be obtained by the present invention. At the
very least, and not as an attempt to limit the application of the
doctrine of equivalents to the scope of the claims, each numerical
parameter should at least be construed in light of the number of
reported significant digits and by applying ordinary rounding
techniques. Notwithstanding that the numerical ranges and
parameters setting forth the broad scope of the invention are
approximations, the numerical values set forth in the specific
examples are reported as precisely as possible. Any numerical
value, however, inherently contains certain errors necessarily
resulting from the standard deviation found in their respective
testing measurements. It is intended that the specification and
examples be considered as exemplary only, with a true scope and
spirit of the invention being indicated by the following
claims.
* * * * *