U.S. patent application number 13/291652 was filed with the patent office on 2012-03-01 for hexagonal boron nitride as an enhanced anti-sticking transmission oil additive.
This patent application is currently assigned to Total France. Invention is credited to Bernard Constans, Sylvain Iovine, Raphaele Ladaviere, Pierre Tequi.
Application Number | 20120053095 13/291652 |
Document ID | / |
Family ID | 34443100 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120053095 |
Kind Code |
A1 |
Tequi; Pierre ; et
al. |
March 1, 2012 |
Hexagonal Boron Nitride as an Enhanced Anti-Sticking Transmission
Oil Additive
Abstract
Disclosed are additive compositions for transmission oils
comprising an oil dispersion of a hexagonal boron nitride and a
polymethacrylate, a dispersant polymethacrylate or a dispersant
olefin copolymer viscosity index improver, as well as lubricating
oil compositions containing the same.
Inventors: |
Tequi; Pierre; (Breaute,
FR) ; Constans; Bernard; (Serezin, FR) ;
Ladaviere; Raphaele; (Sainte Foy Les Lyon, FR) ;
Iovine; Sylvain; (Mornant, FR) |
Assignee: |
Total France
Puteaux
CA
Chevron Oronite S.A.
San Ramon
|
Family ID: |
34443100 |
Appl. No.: |
13/291652 |
Filed: |
November 8, 2011 |
Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
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12216699 |
Jul 9, 2008 |
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13291652 |
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10738388 |
Dec 16, 2003 |
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12216699 |
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Current U.S.
Class: |
508/160 ;
508/155 |
Current CPC
Class: |
C10M 2205/022 20130101;
C10N 2060/06 20130101; C10M 2201/061 20130101; C10M 2205/024
20130101; C10M 161/00 20130101; C10M 2217/023 20130101; C10N
2010/02 20130101; C10M 2217/028 20130101; C10N 2030/06 20130101;
C10N 2020/06 20130101; C10N 2020/04 20130101; C10N 2040/04
20130101; C10N 2040/044 20200501; C10N 2020/02 20130101; C10N
2060/09 20200501; C10N 2040/042 20200501; C10M 2209/084 20130101;
C10M 2201/087 20130101; C10M 2217/022 20130101 |
Class at
Publication: |
508/160 ;
508/155 |
International
Class: |
C10M 125/26 20060101
C10M125/26 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2003 |
EP |
03292968.9 |
Claims
1. A composition, comprising: a transmission oil additive
containing a) an oil dispersion of hexagonal boron nitride having a
particle size distribution wherein 90% or greater of the particles
are less than about 0.5 microns; and b) a viscosity index improver
selected from the group consisting of i) a non-dispersant
polymethacrylate, ii) a dispersant polymethacrylate, and iii) a
dispersant olefin copolymer. wherein the weight ratio of the oil
dispersion of hexagonal boron nitride to the viscosity index
improver is in the range of about 99:1 to about 1:99.
2. The composition of claim 1, wherein the weight ratio of the oil
dispersion of hexagonal boron nitride to the viscosity index
improver is in the range of about 5:95 to about 95:5.
3. The composition of claim 1, wherein the oil dispersion of
hexagonal boron nitride contains an oil of lubricating viscosity
and about 1 to about 50 wt % of hexagonal boron nitride solids,
based on the total weight of the oil dispersion.
4. The composition of claim 3, wherein the oil dispersion of
hexagonal boron nitride further contains a surfactant as a
stabilizer.
5. The composition of claim 1, wherein the oil dispersion of
hexagonal boron nitride is present in the transmission oil additive
in the range of about 10 to about 90 wt %, based on the total
weight of the transmission oil additive.
6. The composition of claim 1 wherein the non-dispersant
polymethacrylate contains short chain, intermediate chain or long
chain hydrocarbon side chains.
7. The composition of claim 1, wherein the dispersant
polymethacrylate contains short chain, intermediate chain or long
chain dispersant hydrocarbon side chains.
8. The composition of claim 1, wherein the dispersant olefin
copolymer is a dispersant ethylene-propylene olefin copolymer.
9. The composition of claim 1, wherein the transmission oil
additive further comprises an oil dispersion of hydrated alkali
metal borate.
10. The composition of claim 9, wherein the alkali metal in the
hydrated alkali metal borate is sodium or potassium.
11. The composition of claim 10, wherein the alkali metal is
potassium.
12. The composition of claim 9, wherein the hydrated alkali metal
borate is hydrated potassium triborate.
13. The composition of claim 9, wherein the oil dispersion of
hydrated alkali metal borate contains a hydrated alkali metal
borate, a dispersant, and an oil of lubricating viscosity.
14. The composition of claim 13, wherein the oil dispersion of
hydrated alkali metal borate contains about 10 to about 75 wt % of
the hydrated alkali metal borate, based on the total weight of the
oil dispersion.
15. The composition of claim 14, wherein the oil dispersion of
hydrated alkali metal borate contains about 2 to about 40 wt % of
the dispersant, based on the total weight of the oil
dispersion.
16. The composition of claim 15, wherein the oil dispersion of
hydrated alkali metal borate further contains a detergent.
17. The composition of claim 16, wherein the oil dispersion of
hydrated alkali metal borate contains about 0.2 to about 10 wt % of
the detergent, based on the total weight of the oil dispersion.
18. The composition of claim 9, wherein the oil dispersion of
hydrated alkali metal borate is present in the transmission oil
additive in the range of about 10 to about 90 wt %, based on the
total weight of the transmission oil additive.
19. A lubricating oil composition comprising a major amount of a
transmission oil of lubricating viscosity and an effective
synchronizer sticking reducing amount of a transmission oil
additive containing; a) an oil dispersion of hexagonal boron
nitride having a particle size distribution wherein 90% or greater
of the particles are less than about 0.5 microns; and b) a
viscosity index improver selected from the group consisting of (i)
a non-dispersant polymethacrylate, (ii) a dispersant
polymethacrylate, and iii) a dispersant olefin copolymer, wherein
the weight ratio of the oil dispersion of hexagonal boron nitride
to the viscosity index improver is in the range of 99:1 to about
1:99.
20. The composition of claim 19, wherein the weight ratio of the
oil dispersion of hexagonal boron nitride to the viscosity index
improver is in the range of about 5:95 to about 95:5.
21. The composition of claim 19, wherein the lubricating oil
composition contains about 1 to about 20 wt % of the transmission
oil additive, based on the total weight of the lubricating oil
composition.
22. The composition of claim 19, wherein the transmission oil of
lubricating viscosity is a manual transmission gear oil.
Description
[0001] The present invention is directed to an additive composition
for a transmission oil. More particularly, the present invention is
directed to an additive composition comprising an oil dispersion of
hexagonal boron nitride and a viscosity index improver, in
particular, an additive composition containing a viscosity index
improver selected from a polymethacrylate, a dispersant
polymethacrylate or a dispersant olefin copolymer.
REFERENCES
[0002] The following references are cited in this application as
superscript numbers: [0003] .sup.1 Peeler, U.S. Pat. No. 3,313,727,
Alkali Metal Borate E.P. Lubricants, issued Apr. 11, 1967 [0004]
.sup.2 Adams, U.S. Pat. No. 3,912,643, Lubricant Containing
Neutralized Alkali Metal Borates, issued Oct. 14, 1975 [0005]
.sup.3 Sims, U.S. Pat. No. 3,819,521, Lubricant Containing
Dispersed Borate and a Polyol, issued Jun. 25, 1974 [0006] .sup.4
Adams, U.S. Pat. No. 3,853,772, Lubricant Containing Alkali Metal
Borate Dispersed with a Mixture of Dispersants, issued Dec. 10,
1974 [0007] .sup.5 Adams, U.S. Pat. No. 3,997,454, Lubricant
Containing Potassium Borate, issued Dec. 14, 1976 [0008] .sup.6
Adams, U.S. Pat. No. 4,089,790, Synergistic Combinations of
Hydrated Potassium Borate, Antiwear Agents, and Organic Sulfide
Antioxidants, issued May 16, 1978 [0009] .sup.7 Adams, U.S. Pat.
No. 4,163,729, Synergistic Combinations of Hydrated Potassium
Borate, Antiwear Agents, and Organic Sulfide Antioxidants, issued
Aug. 7, 1979 [0010] .sup.8 Frost, U.S. Pat. No. 4,263,155,
Lubricant Composition Containing an Alkali Metal Borate and
Stabilizing Oil-Soluble Acid, issued Apr. 21, 1981 [0011] .sup.9
Frost, U.S. Pat. No. 4,401,580, Lubricant Composition Containing an
Alkali Metal Borate and an Ester-Polyol Compound, issued Aug. 30,
1983 [0012] .sup.10 Frost, U.S. Pat. No. 4,472,288, Lubricant
Composition Containing an Alkali Metal Borate and an Oil-Soluble
Amine Salt of a Phosphorus Compound, issued Sep. 18, 1984 [0013]
.sup.11 Clark, U.S. Pat. No. 4,534,873, Automotive Friction
Reducing Composition, issued Aug. 13, 1985 [0014] .sup.12 Brewster,
U.S. Pat. No. 3,489,619, Heat Transfer and Quench Oil, issued Jan.
13, 1970. [0015] .sup.13 Salentine, U.S. Pat. No. 4,717,490,
Synergistic Combination of Alkali Metal Borates, Sulfur Compounds,
Phosphites and Neutralized Phosphate, issued Jan. 5, 1988
[0016] All of the above patents are herein incorporated by
reference in their entirety to the same extent as if each
individual patent was specifically and individually indicated to be
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0017] High load conditions often occur in gear sets such as those
used in automobile transmissions and differentials, pneumatic
tools, gas compressors, centrifuges, high-pressure hydraulic
systems, metal working and similar devices, as well as in many
types of bearings. When employed in such environments, it is
conventional to add an extreme-pressure (E.P.) agent to the
lubricant composition and, in this regard, alkali metal borates are
well known extreme-pressure agents for such compositions..sup.1-11,
13 E.P. agents are added to lubricants to prevent destructive
metal-to-metal contact in the lubrication of moving surfaces. While
under normal conditions termed "hydrodynamic", a film of lubricant
is maintained between the relatively moving surfaces governed by
lubricant parameters, and principally viscosity. However, when load
is increased, clearance between the surface's is reduced, or when
speeds of moving surfaces are such that the film of oil cannot be
maintained, the condition of "boundary lubrication" is reached;
governed largely by the parameters of the contacting surfaces. At
still more severe conditions, significant destructive contact
manifests itself in various forms such as wear and metal fatigue as
measured by ridging and pitting. It is the role of E.P. additives
to prevent this from happening. For the most part, E.P. agents have
been oil soluble or easily dispersed as a stable dispersion in the
oil, and largely have been organic compounds chemically reacted to
contain sulfur, halogen (principally chlorine), phosphorous,
carboxyl, or carboxylate salt groups which react with the metal
surface under boundary lubrication conditions. Stable dispersions
of hydrated alkali metal borates have also been found to be
effective as E.P. agents.
[0018] Moreover, because hydrated alkali metal borates are
insoluble in lubricant oil media, it is necessary to incorporate
the borate as a dispersion in the oil and homogenous dispersions
are particularly desirable. The degree of formation of a homogenous
dispersion can be correlated to the turbidity of the oil after
addition of the hydrated alkali metal borate with higher turbidity
correlating to less homogenous dispersions. In order to facilitate
formation of such a homogenous dispersion, it is conventional to
include a dispersant in such compositions. Examples of dispersants
include lipophilic surface-active agents such as alkenyl
succinimides or other nitrogen containing dispersants as well as
alkenyl succinates..sup.1-4, 12 It is also conventional to employ
the alkali metal borate at particle sizes of less than 1 micron in
order to facilitate the formation of the homogenous
dispersion..sup.11
[0019] In addition, anti-sticking agents are often employed in
automotive gear boxes to provide smooth synchronization and good
shift ability. Examples of such anti-sticking agents include
phosphates, phosphites, phosphonates, thiophosphates, carbamates,
molybdenum dithiocarbamates and dithiophosphates.
[0020] It is also known that boron nitride exhibits friction
modifying properties in lubricants. For example, U.S. Pat. No.
4,787,993, issued Nov. 29, 1988 to Nagahiro, discloses a lubricant
effective for the reduction of friction which comprises dispersing
a finely powdered aromatic or polyamide resin into a fluid fat or
oil, which may additionally contain molybdenum disulfide, organic
molybdenum or boron nitride. Furthermore, U.S. Pat. No. 4,715,972,
issued Dec. 29, 1987 to Pacholke, discloses a solid lubricant
additive for gear oils comprising solid lubricant particles
combined with a stabilizing agent and a fluid carrier, wherein the
solid lubricant particles are selected from the group consisting of
molybdenum disulfide, graphite, cerium fluoride, zinc oxide,
tungsten disulfide, mica, boron nitrate, boron nitride, borax,
silver sulfate, cadmium iodide, lead iodide, barium fluoride, tin
sulfide, fluorinated carbon, PTFE, intercalated graphite, zinc
phosphide, zinc phosphate, and mixtures thereof. This patent
further discloses that such lubricant additive provides the gear
oil with improved demulsibility, stability and compatibility
characteristics of the gear oil when contaminated with water.
[0021] Polymethacrylic acid esters or polymethacrylates are long
chain esters commonly used in the lubricating oil industry as
viscosity index improvers (VII). Their molecular masses lie
predominantly between 20,000 and 500,000. The properties of the
homo- or co-polymers of the various alkylmethacrylates differ with
the chain length of the alcohol used to make the ester and the
degree of polymerization. Olefin co-polymers (OCP) are manufactured
from ethylene and propylene by means of Ziegler catalysts and are
commonly used in the lubricating oil industry as VIIs. Dispersant
Olefin Co-polymers (DOCP) are multifunctional VIIs; the viscosity
improving effect is combined with dispersant properties by the
inclusion of cyclic imides such as N-vinylimidazole and similar
fragments in the polymers.
[0022] Accordingly, it is an object of the present invention to
provide a lubricant additive composition having good anti-sticking
properties when used in transmission oils.
SUMMARY OF THE INVENTION
[0023] The present invention provides a novel additive composition
for a transmission oil comprising: [0024] a) an oil dispersion of
hexagonal boron nitride and; [0025] b) a viscosity index improver
selected from the group consisting of: [0026] i) a
polymethacrylate, [0027] ii) a dispersant polymethacrylate, and
[0028] iii) a dispersant olefin copolymer; [0029] wherein the
weight ratio of the oil dispersion of hexagonal boron nitride to
the viscosity index improver is in the range of from about 99:1 to
about 1:99.
[0030] Typically, the concentration of the oil dispersion of
hexagonal boron nitride is from about 1 to about 99 wt %,
preferably from about 5 to about 95 wt % and the concentration of
the viscosity index improver is from about 1 to about 99 wt %,
preferably from about 5 to about 95 wt %, based on the total weight
of the additive composition.
[0031] The additive composition of the present invention may
optionally further contain an oil dispersion of hydrated alkali
metal borate containing a hydrated alkali metal borate, a
dispersant, optionally a detergent, and an oil of lubricating
viscosity.
[0032] The additive composition of the present invention may be
suitably employed in both manual transmission gear oils and
automatic transmission oils. Preferably, the additive composition
will be employed in a manual transmission gear oil.
[0033] The present invention further provides a lubricating oil
composition comprising a major amount of a transmission oil of
lubricating viscosity and an effective synchronizer sticking
reducing amount of the additive composition described above.
Preferably, the transmission oil is a manual transmission gear
oil.
[0034] Among other factors, the present invention is based in part
upon the surprising discovery that the unique combination of an oil
dispersion of hexagonal boron nitride and a certain viscosity index
improver selected from a polymethacrylate, dispersant
polymethacrylate and a dispersant olefin copolymer, provides a
significant and unexpected reduction in synchronizer sticking when
used as an additive composition in a manual transmission gear
oil.
DETAILED DESCRIPTION OF THE INVENTION
[0035] As noted above, the present invention is directed to a novel
additive composition for a transmission oil comprising an oil
dispersion of hexagonal boron nitride and a viscosity index
improver selected the group consisting of: [0036] a. a
polymethacrylate, [0037] b. a dispersant polymethacrylate, and
[0038] c. a dispersant olefin copolymer; wherein the weight ratio
of the oil dispersion of hexagonal boron nitride to the viscosity
index improver is in the range of from about 99:1 to about
1:99.
[0039] Each of the components in the additive composition of the
present invention will be described in further detail below. Unless
otherwise stated, all percentages are in weight percent (wt %).
[0040] The Oil Dispersion of Hexagonal Boron Nitride
[0041] The additive composition of the present invention contains
an oil dispersion of hexagonal boron nitride.
[0042] Hexagonal boron nitride, or h-BN, is a hexagonal,
graphite-like form of boron nitride, having a layered structure and
planar 6-membered rings of alternating boron and nitrogen atoms. On
alternate sheets, boron atoms are directly over nitrogen atoms.
Hexagonal boron nitride can be prepared by heating boric oxide,
boric acid or boric acid salts with ammonium chloride, alkali
cyanides or calcium cyanamide at atmospheric pressure. Hexagonal
boron nitride may also be prepared by the reaction of boron
trichloride or boron trifluoride with ammonia. A discussion of
hexagonal boron nitride can be found, for example, in Kirk-Othmer,
Encyclopedia of Chemical Technology, Fourth Edition, Vol. 4, pp.
427-429, John Wiley and Sons, New York, 1992.
[0043] Generally, the oil dispersion of hexagonal boron nitride
will have a mean particle size of less than 1 micron. Preferably,
the oil dispersion of hexagonal boron nitride will have a particle
size distribution wherein 90% or greater of the particles are less
than about 0.5 microns (500 nanometers, nm), with a preferred mean
particle size of less than about 0.3 microns (300 nm).
[0044] Typically, the oil dispersion of hexagonal boron nitride
will contain from, about 1 to about 50 wt % of the hexagonal boron
nitride solids, preferably from about 1 to about 20 wt %, and more
preferably from about 5 to about 15 wt %, based on the total weight
of the oil dispersion.
[0045] Preferably, the oil dispersion of hexagonal boron nitride
will contain a surfactant as a stabilizer for the oil dispersion.
Typical surfactants for use as a stabilizer include
ethylene-propylene copolymers, or terpolymers of ethylene,
propylene and an unconjugated dienes commonly known as
ethylene-propylene-diene terpolymer, ethylene-propylene copolymers
grafted with a nitrogen-containing vinyl functionality selected
from the group consisting of N-vinyl pyrrollidone and N-vinyl
pyridine, and the like. The ethylene-propylene copolymer generally
has an average molecular weight in the range of from about 22,000
to about 200,000. A preferred surfactant is ethylene-propylene
copolymer which has substantially equal proportions of ethylene and
propylene monomers and an average molecular weight of from about
22,000 to about 40,000. When present, the surfactant concentration
in the oil dispersion of hexagonal boron nitride will typically
range from about 0.1 to about 25 wt %, preferably from about 2 to
about 7 wt %, and more preferably from about 3.0 to about 5.0 wt %,
based on the total weight of the oil dispersion of hexagonal boron
nitride.
[0046] The lubricant oil used to prepare the oil dispersion of
hexagonal boron nitride may be selected from the same group of
natural or synthetic lubricating oils described above for use in
preparing the oil dispersion of hydrated alkali metal borate, but
other carrier fluids have been found to be satisfactory, including
vegetable oils such as rapeseed oil; liquid hydrocarbons such as
aliphatic and aromatic naphthas and mixtures thereof; synthetic
lubricant fluids such as polyalphaolefins, polyglycols, diester
fluids, and mixtures of these liquids. Moreover, the oil used in
forming the oil dispersion of hexagonal boron nitride may be the
same as, or different from, the lubricant oil employed in preparing
the oil dispersion of hydrated alkali metal borate. Typical oils
for preparing the oil dispersion of hexagonal boron nitride include
the Group I and Group II base oils, such as 150 solvent neutral
petroleum oil.
[0047] In general, the oil dispersion of hexagonal boron nitride is
present in the additive composition of the present invention in the
range of from about 1 to about 99 wt %, preferably from about 5 to
about 95 wt %, and more preferably from about 10 to about 90 wt %,
based on the total amount of the additive composition.
[0048] Viscosity Index Improver (VI Improver)
[0049] The additive composition of the present invention contains a
polymethacrylate, dispersant polymethacrylate or a dispersant
olefin copolymer VI improver.
[0050] A. The Polymethacrylate (PMA) or Dispersant
Polymethacrylate
[0051] Typically, the polymethacrylate VI improvers employed in the
present invention are polymeric methacrylates containing short,
intermediate, and long-chain hydrocarbon side chains. Short-chain
hydrocarbon side chains typically have from about 1 to about 7
carbon atoms. For example, both methyl and butyl (either n-butyl,
isobutyl, or mixtures of the two) methacrylates have been used.
Methyl methacrylate is the most common. Intermediate-chain
hydrocarbon side chains typically contain from about 8 to about 15
carbon atoms and may be derived from alcohols including
2-ethylhexyl alcohol, isodecyl alcohol and alcohol mixtures which
may be, for example, C.sub.8 to C.sub.10, C.sub.12 to C.sub.14 or
C.sub.12 to C.sub.15 alcohol mixtures. Long-chain hydrocarbon side
chains generally will contain about 14 or more carbon atoms and may
be based, for example, on C.sub.16 to C.sub.18 or C.sub.16 to
C.sub.20 alcohol mixtures.
[0052] The polymethacrylate VI improvers which may be employed in
the present invention are any type of non-dispersant type or
dispersant type polymethacrylate compounds which are used as VI
improvers for a lubricating oil.
[0053] The non-dispersant type polymethacrylate VI improvers may be
a polymer of a compound represented by the formula:
CH.sub.2.dbd.C(CH.sub.3)--CO.sub.2--R.sup.1
[0054] In formula (1) R.sup.1 is a straight chain or branched alkyl
group such as methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,
hexadecyl, heptadecyl, and octadecyl groups.
[0055] Dispersancy may be incorporated into the PMA with an
appropriate polar monomer by any number a methods known by the
skilled artisan such as copolymerization, graft polymerization or
post reaction of a reactive species into or onto the polymer.
Typically, such methods involve the incorporation of a polar group
derived from nitrogen or oxygen. Nitrogen-based groups are derived
from amines, for example, polyalkyleneamines such as
diethylenetriamine and triethylenetetramine. Oxygen-based groups
are alcohol-derived such as hydroxyethyl methacrylates or
ether-containing methacrylates. Although nitrogen-based PMAs are
exemplified in the present invention, oxygen-based PMAs are also
contemplated within the scope of the present invention. Examples of
oxygen-based PMAs are those derived from polyhydric alcohols such
as glycols, trivalent alcohols such as glyercol and higher
alcohols, such as erythrytol, pentaerythrytol, mannitol and the
like. Moreover, ether-containing PMAs are also well known in the
art. Further details of oxygen-based PMAs may be found, for
example, in U.S. Pat. Nos. 3,249,545 and 3,052,648, the disclosures
which is hereby incorporated for all purposes.
[0056] Specific examples of the dispersant polymethacrylate VI
improvers are copolymers obtained by copolymerizing one or more
monomers selected from compounds represented by formula (1) with
one or more nitrogen-containing monomers selected from compounds
represented by formulas (2) and (3)
CH.sub.2.dbd.C(R.sup.2)CO.sub.2--R.sup.3--X.sup.1 Formula 2
CH.sub.2.dbd.C(R.sup.4)--X.sup.2 Formula 3
[0057] In formulas (2) and (3) R.sup.2 and R.sup.4 are each
independently hydrogen or methyl, R.sup.3 is a straight chain or
branched alkylene group having from about 1 to about 18 carbon
atoms, such as ethylene, propylene, butylene, pentylene, hexylene,
heptylene, octylene, nonylene, decylene, undecylene, dodecylene,
tridecylene, tetradecylene, pentadecylene, hexadecylene,
heptadecylene, and octadecylene groups, X.sup.1 and X.sup.2 each
independently an amino- or heterocyclic-residue having about 1 or
about 2 nitrogen atoms and 0 to about 2 oxygen atoms. Specific
examples of X.sup.1 and X.sup.2 are dimethylamino, diethylamino,
dipropylamino, dibutylamino, anilino, toluidino, xylidino,
acetylamino, benzoilamino, morpholino, pyrolyl, pyridyl,
methylpyridyl, pyrrolidinyl, piperidinyl, quinonyl, pyrrolidonyl,
pyrrolidono, imidazolino, and pyrazino groups.
[0058] Specific examples of the nitrogen-containing monomers
represented by formula (2) or (3) are
dimethylaminomethylmethacrylate, diethylaminomethylmethacrylate,
dimethylaminoethylmethacrylate, diethylaminoethylmethacrylate,
2-methyl-5-vinylpyridine, morpholinomethylmethacrylate,
morpholinoethylmethacrylate, N-vinylpyrrolidone, and mixtures
thereof.
[0059] A particularly beneficial PMA employed in the present
invention is an ester polymer, having principally from about 1 to
about 20, preferably from about 8 to about 14, carbon atoms. It can
be prepared by a polymerization reaction with a basic monomer and a
peroxide or azoic initiator in a hydrocarbon solvent such as
toluene or a mineral or synthetic base oil. The basic monomers used
to prepare the PMA are principally monocarboxylic acid esters such
as methacrylate, acrylate, crotonate, tiglicate, and angelicate.
The PMA may also be prepared by reaction with olefinic copolymers
(i.e., ethylene-propylene copolymer) in oil.
[0060] The average molecular weight of the PMA will be in the range
of from about 20,000 to about 500,000. Preferably, the molecular
weight will range from about 50,000 to about 300,000 and more
preferably, from about 80,000 to about 150,000.
[0061] A further discussion of PMA VI improvers and dispersant PMA
VI improvers can be found, for example, in "Lubricant Additives
Chemistry and Applications", Leslie R. Rudnick, Editor, Chapters 5
and 11, Marcel Dekker, Inc, New York 2003 and U.S. Pat. No.
6,642,189.
[0062] B. Dispersant Olefin Copolymer (OCP)
[0063] The dispersant OCPs employable in the present invention
include copolymers of two or more olefins such as ethylene,
propylene, butylene, iso-butylene, isoprene, butadiene and the
like, as well as copolymers of these olefins with other monomers
such as styrene, cyclopentadiene, dicyclopentadiene,
ethylidene-norbornene and so on.
[0064] Exemplary dispersant OCPs for the purpose of the present
invention relate to ethylene copolymers. Oil soluble ethylene
copolymers used in the invention generally will have a
number-average molecular weight (M.sub.n) of from above about 5,000
to about 500,000; preferably from about 10,000 to about 200,000 and
optimally from about 20,000 to about 100,000. They will generally
have a narrow range of molecular weight, as determined by the ratio
of weight-average molecular weight (M.sub.w) to number average
molecular weight (M.sub.n). Polymers having a M.sub.w/M.sub.n of
less than 10, preferably less than 7, and more preferably 4 or less
are most desirable. As used herein and (M.sub.n) and (M.sub.w) are
measured by the well known techniques of vapor phase osmometry
(VPO), membrane osmometry and gel permeation chromatography. In
general, polymers having a narrow range of molecular weight may be
obtained by a choice of synthesis conditions such as choice of
principal catalyst and cocatalyst combination, addition of hydrogen
during the synthesis, etc. Post synthesis treatment such as
extrusion at elevated temperature and under high shear through
small orifices, mastication under elevated temperatures, thermal
degradation, fractional precipitation from solution, etc. may also
be used to obtain narrow ranges of desired molecular weights and to
break down higher molecular weight polymer to different molecular
weight grades for VI use.
[0065] These polymers are prepared from ethylene and ethylenically
unsaturated hydrocarbons including cyclic, alicyclic and acyclic,
containing from about 3 to about 28 carbons, e.g. about 2 to about
18 carbons. These ethylene copolymers may contain from about 15 to
about 90 wt. % ethylene, preferably from about 30 to about 80 wt. %
of ethylene and from about 10 to about 85 wt. %, preferably from
about 20 to about 70 wt. % of one or more C.sub.3 to C.sub.28,
preferably C.sub.3 to C.sub.18, more preferably C.sub.3 to C.sub.8,
alpha olefins. While not essential, such copolymers preferably have
a degree of crystallinity of less than 25 wt. %, as determined by
X-ray and differential scanning calorimetry. Copolymers of ethylene
and propylene are most preferred. Other alpha-olefins suitable in
place of propylene to form the copolymer, or to be used in
combination with ethylene and propylene to form a terpolymer,
tetrapolymer, etc., include 1-butene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, 1-decene, etc.; also branched chain
alpha-olefins, such as 4-methyl-1-pentene, 4-methyl-1-hexene,
4,4-dimethyl-1-pentene, and 6-methylheptene-1, etc., and mixtures
thereof.
[0066] The term copolymer as used herein, unless otherwise
indicated, includes terpolymers, tetrapolymers, etc., of ethylene,
said C.sub.3 to C.sub.28 alpha-olefin and/or a non-conjugated
diolefin or mixtures of such diolefins which may also be used. The
amount of the non-conjugated diolefin will generally range from
about 0.5 to about 20 mole percent, preferably from about 1 to
about 7 mole percent, based on the total amount of ethylene and
alpha-olefin present.
[0067] Representative examples of non-conjugated dienes that may be
used as the third monomer in the terpolymer include:
a. Straight chain acyclic dienes such as: 1,4-hexadiene;
1,5-heptadiene; 1,6-octadiene. b. Branched chain acyclic dienes
such as: 5-methyl-1,4-hexadiene; 3,7-dimethyl 1,6-octadiene;
3,7-dimethyl 1,7-octadiene; and the mixed isomers of
dihydro-myrcene and dihydro-cymene. c. Single ring alicyclic dimes
such as: 1,4-cyclohexadiene; 1,5-cyclooctadiene;
1,5-cyclo-dodecadiene; 4-vinylcyclohexene; 1-allyl,
4-isopropylidene cyclohexane; 3-allyl-cyclopentene; 4-allyl
cyclohexene and 1-isopropenyl-4-(4-butenyl)cyclohexane. d.
Multi-single ring alicyclic dienes such as: 4,4'-dicyclopentenyl
and 4,4'-dicyclohexenyl dienes. e. Multi-ring alicyclic fused and
bridged ring dienes such as: tetrahydroindene; methyl
tetrahydroindene; dicyclopentadiene; bicyclo (2.2.1)-hepta
2,5-diene; alkyl, alkenyl, alkylidene, cycloalkenyl and
cycloalkylidene norbornenes such as: ethyl norbornene;
5-methylene-6-methyl-2-norbornene;
5-methylene-6,6-dimethyl-2-norbornene; 5-propenyl-2-norbornene;
5-(3-cyclopentenyl)-2-norbornene and
5-cyclohexylidene-2-norbornene; norbornadiene; etc.
[0068] A compound containing at least one ethylenic bond and at
least one, preferably two, carboxylic acid groups, or an anhydride
group, or a polar group which is convertible into said carboxyl
groups by oxidation or hydrolysis may be grafted on the ethylene
coploymer. Preferred acid materials are (i) monounsaturated C.sub.4
to C.sub.10 dicarboxylic acid wherein (a) the carboxyl groups are
vicinyl, i.e., located on adjacent carbon atoms, and (b) at least
one, preferably both, of said adjacent carbon atoms are part of
said mono unsaturation; or (ii) derivatives of (i) such as
anhydrides or C.sub.1 to C.sub.5 alcohol derived mono- or diesters
of (i). Upon reaction with the ethylene-alpha-olefin copolymer, the
monounsaturation of the dicarboxylic acid, anhydride, or ester
becomes saturated. Thus, for example, maleic anhydride becomes a
hydrocarbyl substituted succinic anhydride.
[0069] Maleic anhydride or a derivative thereof is preferred as it
does not appear to homopolymerize appreciably but grafts onto the
ethylene copolymer to give two carboxylic acid functionalities.
Such preferred materials have the generic formula
##STR00001##
wherein R.sup.5 and R.sup.6 are the same or different and are
hydrogen or a halogen. Suitable examples additionally include
chloro-maleic anhydride, itaconic anhydride, or the corresponding
dicarboxylic acids, such as maleic acid or fumaric acid or their
monoesters, etc.
[0070] As taught by U.S. Pat. No. 4,160,739 and U.S. Pat. No.
4,161,452, both of which are incorporated herein by reference,
various unsaturated comonomers may be grafted on the ethylene
copolymer together with the unsaturated acid component, e.g. maleic
anhydride. Such graft monomer systems may comprise one or a mixture
of comonomers different from the unsaturated acid component and
which contain only one copolymerizable double bond and are
copolymerizable with said unsaturated acid component. Typically,
such comonomers do not contain free carboxylic acid groups and are
esters containing alpha, beta-ethylenic unsaturation in the acid or
alcohol portion; hydrocarbons, both aliphatic and aromatic,
containing alpha, beta-ethylenic unsaturation, such as the C.sub.4
to C.sub.12 alpha olefins, for example isobutylene, hexene, nonene,
dodecene, etc.; styrenes, for example styrene, alpha-methyl
styrene, p-methyl styrene, p-sec. butyl styrene, etc.; and vinyl
monomers, for example vinyl acetate, vinyl chloride, vinyl ketones
such as methyl and ethyl vinyl ketone, etc. Comonomers containing
functional groups which may cause crosslinking, gelation or other
interfering reactions should be avoided, although minor amounts of
such comonomers (up to about 10% by weight of the comonomer system)
often can be tolerated.
[0071] Specific useful copolymerizable comonomers include the
following:
(A) Esters of saturated acids and unsaturated alcohols wherein the
saturated acids may be monobasic or polybasic acids containing up
to about 40 carbon atoms such as the following: acetic, propionic,
butyric, valeric, caproic, stearic, oxalic, malonic, succinic,
glutaric, adipic, pimelic, suberic, azelaic, sebacic, phthalic,
isophthalic, terephthalic, hemimellitic, trimellitic, trimesic and
the like, including mixtures. The unsaturated alcohols may be
monohydroxy or polyhydroxy alcohols and may contain up to about 40
carbon atoms, such as the following: allyl, methallyl, crotyl,
1-chloroallyl, 2-chloroallyl, cinnamyl, vinyl, methyl vinyl,
1-phenallyl, butenyl, propargyl, 1-cyclohexene-3-ol, oleyl, and the
like, including mixtures. (B) Esters of unsaturated monocarboxylic
acids containing up to about 12 carbon atoms such as acrylic,
methacrylic and crotonic acid, and an esterifying agent containing
up to about 50 carbon atoms, selected from saturated alcohols and
alcohol epoxides. The saturated alcohols may preferably contain up
to about 40 carbon atoms and include monohydroxy compounds such as:
methanol, ethanol, propanol, butanol, 2-ethylhexanol, octanol,
dodecanol, cyclohexanol, cyclopentanol, neopentyl alcohol, and
benzyl alcohol; and alcohol ethers such as the monomethyl or
monobutyl ethers of ethylene or propylene glycol, and the like,
including mixtures. The alcohol epoxides include fatty alcohol
epoxides, glycidol, and various derivatives of alkylene oxides,
epichlorohydrin, and the like, including mixtures.
[0072] The components of the graft copolymerizable system are used
in a ratio of unsaturated acid monomer component to comonomer
component of about 1:4 to about 4:1, preferably about 1.2 to about
2:1 by weight.
[0073] Further dispersant functionality may be incorporated into
the OCP by reacting with polyamine or polyol, high functionality
long chain hydrocarbyl dicarboxylic acid materials having a
functionality of from about 1.2 to about 2 and short chain
hydrocarbyl substituted dicarboxylic acids, as described, for
example, in U.S. Pat. No. 5,035,821, which is hereby incorporated
for all purposes.
[0074] Among the copolymers preferred are ethylene-propylene
copolymers (the ratio of ethylene:propylene is preferably about 3:1
to about 1:3), and styrene-isoprene copolymers. Olefin copolymers
are manufactured from ethylene and propylene by means of Ziegler
catalysts. The molecular weight of olefinic copolymers may vary
widely, but preferred copolymer are those having a molecular weight
of from about 30,000 to about 200,000, more preferably from about
40,000 to about 150,000.
[0075] Such preferred copolymers include nitrogen atom-containing
polymers, for example, those obtained by copolymerizing or
grafting, with an acidic component such as maleic acid or anhydride
thereof, onto an olefinic copolymer, followed by forming amide or
imide linkages by reaction with polyamines.
[0076] Another such preferred copolymer is that obtained by
oxidizing an olefinic copolymer, followed by reacting the oxidized
polymer with polyamines. Still another copolymer is that obtained
by oxidizing an olefinic copolymer followed by Mannich condensation
with formaldehyde and polyamines.
[0077] Another preferred copolymer is that obtained by
copolymerizing olefins with a nitrogen atom-containing monomer, or
grafting a nitrogen atom-containing monomer onto an olefinic
copolymer such as N-vinylpyrrolidone, N-vinylthiopyrrolidone, a
dialkylaminoethyl methacrylate or the like (the content of nitrogen
atom-containing monomer preferably being from about 0.1 to about 10
wt %).
[0078] In general, the VI Improver is present in the additive
composition of the present invention in the range of from about 1
to about 99 wt %, preferably from about 5 to about 95 wt %, and
more preferably from about 10 to about 90 wt %, based on the total
weight of the additive composition.
[0079] A further discussion of dispersant OCP VI improvers can be
found, for example, in "Lubricant Additives; Chemistry and
Applications", Leslie R. Rudnick, Editor, Chapters 5 and 10, Marcel
Dekker, Inc, New York 2003.
[0080] The Hydrated Alkali Metal Borate
[0081] The additive composition of the present invention may
optionally further contain an oil dispersion of hydrated alkali
metal borate as described below.
[0082] Hydrated alkali metal borates are well known in the art.
Representative patents disclosing suitable borates and methods of
manufacture include: U.S. Pat. Nos. 3,313,727; 3,819,521;
3,853,772; 3,912,643; 3,997,454; and 4,089,790..sup.1-6
[0083] The hydrated alkali metal borates suitable for use in the
present invention can be represented by the following general
formula:
M.sub.2O.xB.sub.2O.sub.3.yH.sub.2O
wherein M is an alkali metal, preferably sodium or potassium; x is
a number from about 2.5 to about 4.5 (both whole and fractional);
and y is a number from about 1.0 to about 4.8. More preferred are
the hydrated potassium borates, particularly the hydrated potassium
triborates. The hydrated borate particles will generally have a
mean particle size of less than 1 micron.
[0084] In the alkali metal borates employed in this invention, the
ratio of boron to alkali metal will preferably range from about
2.5:1 to about 4.5:1.
[0085] Oil dispersions of hydrated alkali metal borates are
generally prepared by forming, in deionized water, a solution of
alkali metal hydroxide and boric acid, optionally in the presence
of a small amount of the corresponding alkali metal carbonate. The
solution is then added to a lubricant composition comprising an oil
of lubricating viscosity, a dispersant and any optional additives
to be included therein (e.g., a detergent, or other optional
additives) to form an emulsion that is then dehydrated.
[0086] Because of their retention of hydroxyl groups on the borate
complex, these complexes are referred to as "hydrated alkali metal
borates" and compositions containing oil/water emulsions of these
hydrated alkali metal borates are referred to as "oil dispersions
of hydrated alkali metal borates".
[0087] Preferred oil dispersions of alkali metal borates will have
a boron to alkali metal ratio of from about 2.5:1 to about 4.5:1.
In another preferred embodiment, the hydrated alkali metal borate
particles generally will have a mean particle size of less than 1
micron. In this regard, it has been found that the hydrated alkali
metal borates employed in this invention preferably will have a
particle size where 90% or greater of the particles are less than
0.6 microns.
[0088] In the oil dispersion of hydrated alkali metal borate, the
hydrated alkali metal borate will generally comprise from about 10
to about 75 wt %, preferably from about 25 to about 50 wt %, more
preferably from about 30 to about 40 wt % of the total weight of
the oil dispersion of hydrated borate.
[0089] In general, when employed, the oil dispersion of hydrated
alkali metal borate is present in the additive composition of the
invention in the range of from about 10 to about 90 wt %, based on
the total weight of the additive composition.
[0090] The additive compositions and lubricant compositions of the
present invention can further employ surfactants, detergents, other
dispersants and other conditions as described below and known to
those skilled in the art. Optionally, the additive compositions may
contain an alkylaromatic or polyisobutenyl sulfonate.
[0091] The oil dispersions of hydrated alkali metal borates
employed in this invention generally comprise a dispersant, an oil
of lubricating viscosity, and optionally a detergent, that are
further detailed below.
[0092] The dispersant employed in the oil dispersion of hydrated
alkali metal borate optionally employable in the present invention
can be ashless dispersants such as an alkenyl succinimide, an
alkenyl succinic anhydride, an alkenyl succinate ester, and the
like, or mixtures of such dispersants.
[0093] Ashless dispersants are broadly divided into several groups.
One such group is directed to copolymers which contain a
carboxylate ester with one or more additional polar function,
including amine, amide, imine, imide, hydroxyl carboxyl, and the
like. These products can be prepared by copolymerization of long
chain alkyl acrylates or methacrylates with monomers of the above
function. Such groups include alkyl methacrylate-vinyl
pyrrolidinone copolymers, alkyl methacrylate-dialkylaminoethyl
methacrylate copolymers and the like. Additionally, high molecular
weight amides and polyamides or esters and polyesters such as
tetraethylene pentamine, polyvinyl polysterarates and other
polystearamides may be employed. Preferred dispersants are
N-substituted long chain alkenyl succinimides.
[0094] Alkenyl succinimides are usually derived from the reaction
of alkenyl succinic acid or anhydride and alkylene polyamines.
These compounds are generally considered to have the formula
##STR00002##
wherein R.sup.7 is a substantially hydrocarbon radical having a
molecular weight from about 400 to about 3,000, that is, R.sup.7 is
a hydrocarbyl radical, preferably an alkenyl radical, containing
from about 30 to about 200 carbon atoms; Alk is an alkylene radical
of from about 2 to about 10, preferably from about 2 to about 6,
carbon atoms, R.sup.8, R.sup.9, and R.sup.10 are selected from a
C.sub.1 to C.sub.4 alkyl or alkoxy or hydrogen, preferably
hydrogen, and z is an integer from about 0 to about 10, preferably
from about 0 to about 3. The actual reaction product of alkylene
succinic acid or anhydride and alkylene polyamine will comprise the
mixture of compounds including succinamic acids and succinimides.
However, it is customary to designate this reaction product as a
succinimide of the described formula, since this will be a
principal component of the mixture. See, for example, U.S. Pat.
Nos. 3,202,678; 3,024,237; and 3,172,892.
[0095] These N-substituted alkenyl succinimides can be prepared by
reacting maleic anhydride with an olefinic hydrocarbon followed by
reacting the resulting alkenyl succinic anhydride with the alkylene
polyamine. The R.sup.1 radical of the above formula, that is, the
alkenyl radical, is preferably derived from a polymer prepared from
an olefin monomer containing from about 2 to about 5 carbon atoms.
Thus, the alkenyl radical is obtained by polymerizing an olefin
containing from about 2 to about 5 carbon atoms to form a
hydrocarbon having a molecular weight ranging from about 400 to
about 3,000. Such olefin monomers are exemplified by ethylene,
propylene, 1-butene, 2-butene, isobutene, and mixtures thereof.
[0096] The preferred polyalkylene amines used to prepare the
succinimides are of the formula:
##STR00003##
wherein z is an integer of from about 0 to about 10 and Alk,
R.sup.8, R.sup.9, and R.sup.10 are as defined above.
[0097] The alkylene amines include principally methylene amines,
ethylene amines, butylene amines, propylene amines, pentylene
amines, hexylene amines, heptylene amines, octylene amines, other
polymethylene amines and also the cyclic and the higher homologs of
such amines as piperazine and amino alkyl-substituted piperazines.
They are exemplified specifically by ethylene diamine, triethylene
tetraamine, propylene diamine, decamethyl diamine, octamethylene
diamine, diheptamethylene triamine, tripropylene tetraamine,
tetraethylene pentamine, trimethylene diamine, pentaethylene
hexamine, ditrimethylene triamine,
2-heptyl-3-(2-aminopropyl)-imidazoline, 4-methyl imidazoline,
N,N-dimethyl-1,3-propane diamine, 1,3-bis(2-aminoethyl)imidazoline,
1-(2-aminopropyl)-piperazine, 1,4-bis(2-aminoethyl)piperazine and
2-methyl-1-(2-aminobutyl)piperazine, Higher homologs such as are
obtained by condensing two or more of the above-illustrated
alkylene amines likewise are useful.
[0098] The ethylene amines are especially useful. They are
described in some detail under the heading "Ethylene Amines" in
Encyclopedia of Chemical Technology, Kirk-Othmer, Vol. 5, pp.
898-905 (Interscience Publishers, New York, 1950).
[0099] The term "ethylene amine" is used in a generic sense to
denote a class of polyamines conforming for the most part to the
structure
H.sub.2N(CH.sub.2CH.sub.2NH).sub.aH
wherein a is an integer from about 1 to about 10.
[0100] Thus, it includes, for example, ethylene diamine, diethylene
triamine, triethylene tetraamine, tetraethylene pentamine,
pentaethylene hexamine, and the like.
[0101] Also included within the term "alkenyl succinimides" are
post-treated succinimides such as post-treatment processes
involving ethylene carbonate disclosed by Wollenberg, et U.S. Pat.
No. 4,612,132; Wollenberg, et al., U.S. Pat. No. 4,746,446; and the
like as well as other post-treatment processes each of which are
incorporated herein by reference in its entirety.
[0102] Preferably, the dispersant component, such as a polyalkylene
succinimide, comprises from about 2 to about 40 wt %, more
preferably from about 5 to about 20 wt %, and even more preferably
from about 5 to about 15 wt %, of the weight of the oil dispersion
of hydrated alkali metal borate.
[0103] Polyalkylene succinic anhydrides or a non-nitrogen
containing derivative of the polyalkylene succinic anhydride (such
as succinic acids, Group I and/or Group II mono- or di-metal salts
of succinic acids, succininate esters formed by the reaction of a
polyalkylene succinic anhydride, acid chloride or other derivative
with an alcohol, and the like) are also suitable dispersants for
use in the compositions of this invention.
[0104] The polyalkylene succinic anhydride is preferably a
polyisobutenyl succinic anhydride. In one preferred embodiment, the
polyalkylene succinic anhydride is a polyisobutenyl succinic
anhydride having a number average molecular weight of at least 500,
more preferably at least about 900 to about 3,000 and still more
preferably from at least about 900 to about 2,300.
[0105] In another preferred embodiment, a mixture of polyalkylene
succinic anhydrides is employed. In this embodiment, the mixture
preferably comprises a low molecular weight polyalkylene succinic
anhydride component and a high molecular weight polyalkylene
succinic anhydride component. More preferably, the low molecular
weight component has a number average molecular weight of from
about 500 to below 1,000 and the high molecular weight component
has a number average molecular weight of from about 1000 to about
3,000. Still more preferably, both the low and high molecular
weight components are polyisobutenyl succinic anhydrides.
Alternatively, various molecular weights polyalkylene succinic
anhydride components can be combined as a dispersant as well as a
mixture of the other above referenced dispersants as identified
above.
[0106] As noted above, the polyalkylene succinic anhydride is the
reaction product of a polyalkylene (preferably polyisobutene) with
maleic anhydride. One can use conventional polyisobutene, or high
methylvinylidene polyisobutene in the preparation of such
polyalkylene succinic anhydrides. One can use thermal,
chlorination, free radical, acid catalyzed, or any other process in
this preparation. Examples of suitable polyalkylene succinic
anhydrides are thermal PIBSA (polyisobutenyl succinic anhydride)
described in U.S. Pat. No. 3,361,673; chlorination PIBSA described
in U.S. Pat. No. 3,172,892; a mixture of thermal and chlorination
PIBSA described in U.S. Pat. No. 3,912,764; high succinic ratio
PIBSA described in U.S. Pat. No. 4,234,435; PolyPIBSA described in
U.S. Pat. Nos. 5,112,507 and 5,175,225; high succinic ratio
PolyPIBSA described in U.S. Pat. Nos. 5,565,528 and 5,616,668; free
radical PIBSA described in U.S. Pat. Nos. 5,286,799, 5,319,030, and
5,625,004; PIBSA made from high methylvinylidene polybutene
described in U.S. Pat. Nos. 4,152,499, 5,137,978, and 5,137,980;
high succinic ratio PIBSA made from high methylvinylidene
polybutene described European Patent Application Publication No. EP
355 895; terpolymer PIBSA described in U.S. Pat. No. 5,792,729;
sulfonic acid PIBSA described in U.S. Pat. No. 5,777,025 and
European Patent Application Publication No. EP 542 380; and
purified PIBSA described in U.S. Pat. No. 5,523,417 and European
Patent Application Publication No. EP 602 863. The disclosures of
each of these documents are incorporated herein by reference in
their entirety.
[0107] Preferably, the polyalkylene succinic anhydride or other
dispersant component comprises from about 2 to about 40 wt %, more
preferably from about 5 to about 20 wt %, and even more preferably
from about 5 to about 15 wt %, of the weight of the oil dispersion
of hydrated alkali metal borate.
[0108] Typically, in the oil dispersion of hydrated alkali metal
borate, the hydrated alkali metal borate is in a ratio of at least
2:1 relative to the polyalkylene succinic anhydride or other
dispersant, while preferably being in the range of 2:1 to about
10:1. In a more preferred embodiment the ratio is at least 5:1. In
another preferred embodiment, mixtures as defined above of the
polyalkylene succinic anhydrides are employed.
[0109] The oil dispersion of hydrated alkali metal borate which is
optionally employed in the additive compositions of the present
invention may optionally contain a detergent. There are a number of
materials that are suitable as detergents for the purpose of this
invention. These materials include phenates (high overbased or low
overbased), high overbased phenate stearates, phenolates,
salicylates, phosphonates, thiophosphonates and sulfonates and
mixtures thereof. Preferably, sulfonates are used, such as high
overbased sulfonates, low overbased sulfonates, or phenoxy
sulfonates. In addition the sulfonic acids themselves can also be
used.
[0110] The sulfonate detergent is preferably an alkali or alkaline
earth metal salt of a hydrocarbyl sulfonic acid having from about
15 to about 200 carbons. Preferably the term "sulfonate"
encompasses the salts of sulfonic acid derived from petroleum
products. Such acids are well known in the art. They can be
obtained by treating petroleum products with sulfuric acid or
sulfur trioxide. The acids thus obtained are known as petroleum
sulfonic acids and the salts as petroleum sulfonates. Most of the
petroleum products which become sulfonated contain an
oil-solubilizing hydrocarbon group. Also included within the
meaning of "sulfonate" are the salts of sulfonic acids of synthetic
alkyl aryl compounds. These acids also are prepared by treating an
alkyl aryl compound with sulfuric acid or sulfur trioxide. At least
one alkyl substituent of the aryl ring is an oil-solubilizing
group, as discussed above. The acids thus obtained are known as
alkyl aryl sulfonic acids and the salts as alkyl aryl sulfonates.
The sulfonates where the alkyl is straight-chain are the well-known
linear alkylaryl sulfonates.
[0111] The acids obtained by sulfonation are converted to the metal
salts by neutralizing with a basic reacting alkali or alkaline
earth metal compound to yield the Group I or Group II metal
sulfonates. Generally, the acids are neutralized with an alkali
metal base. Alkaline earth metal salts are obtained from the alkali
metal salt by metathesis. Alternatively, the sulfonic acids can be
neutralized directly with an alkaline earth metal base. The
sulfonates can then be overbased, although, for purposes of this
invention, overbasing is not necessary. Overbased materials and
methods of preparing such materials are well known to those skilled
in the art. See, for example, LeSuer U.S. Pat. No. 3,496,105,
issued Feb. 17, 1970, particularly columns 3 and 4.
[0112] The sulfonates are present in the oil dispersion in the form
of alkali and/or alkaline earth metal salts, or mixtures thereof.
The alkali metals include lithium, sodium and potassium. The
alkaline earth metals include magnesium, calcium and barium, of
which the latter two are preferred.
[0113] Particularly preferred, however, because of their wide
availability, are salts of the petroleum sulfonic acids,
particularly the petroleum sulfonic acids which are obtained by
sulfonating various hydrocarbon fractions such as lubricating oil
fractions and extracts rich in aromatics which are obtained by
extracting a hydrocarbon oil with a selective solvent, which
extracts may, if desired, be alkylated before sulfonation by
reacting them with olefins or alkyl chlorides by means of an
alkylation catalyst; organic polysulfonic acids such as benzene
disulfonic acid which may or may not be alkylated; and the
like.
[0114] The preferred salts for use in the present invention are
those of alkylated aromatic sulfonic acids in which the alkyl
radical or radicals contain at least about 8 carbon atoms, for
example from about 8 to about 22 carbon atoms. Another preferred
group of sulfonate starting materials are the aliphatic-substituted
cyclic sulfonic acids in which the aliphatic substituents or
substituents contain a total of at least 12 carbon atoms, such as
the alkyl aryl sulfonic acids, alkyl cycloaliphatic sulfonic acids,
the alkyl heterocyclic sulfonic acids and aliphatic sulfonic acids
in which the aliphatic radical or radicals contain a total of at
least 12 carbon atoms. Specific examples of these oil-soluble
sulfonic acids include petroleum sulfonic acids, mono- and
poly-wax-substituted naphthalene sulfonic acids, substituted
sulfonic acids, such as cetyl benzene sulfonic acids, cetyl phenyl
sulfonic acids, and the like, aliphatic sulfonic acid, such as
paraffin wax sulfonic acids, hydroxy-substituted paraffin wax
sulfonic acids, etc., cycloaliphatic sulfonic acids, petroleum
naphthalene sulfonic acids, cetyl cyclopentyl sulfonic acid, mono-
and poly-wax-substituted cyclohexyl sulfonic acids, and the like.
The term "petroleum sulfonic acids" is intended to cover all
sulfonic acids that are derived directly from petroleum
products.
[0115] Typical Group II metal sulfonates suitable for use in the
present invention include the metal sulfonates exemplified as
follows: calcium white oil benzene sulfonate, barium white oil
benzene sulfonate, magnesium white oil benzene sulfonate, calcium
dipolypropene benzene sulfonate, barium dipolypropene benzene
sulfonate, magnesium dipolypropene benzene sulfonate, calcium
mahogany petroleum sulfonate, barium mahogany petroleum sulfonate,
magnesium mahogany petroleum sulfonate, calcium triacontyl
sulfonate, magnesium triacontyl sulfonate, calcium lauryl
sulfonate, barium lauryl sulfonate, magnesium lauryl sulfonate,
etc. The concentration of metal sulfonate that may be employed may
vary over a wide range, depending upon the concentration of alkali
metal borate particles. When present, however, the detergent
concentration will generally range from about 0.2 to about 10 wt %
and preferably from about 3 to about 7 wt %, based on the total
weight of the oil dispersion of hydrated borate. In addition, the
compositions of this invention may contain a mixture of both a
metal sulfonate and an ashless dispersant, as described above,
where the ratio is a factor of achieving the proper stability of
the oil dispersion of hydrated alkali metal borate.
[0116] The oil of lubricating viscosity used to form the oil
dispersions of hydrated alkali metal borate may be any
hydrocarbon-based lubricating oil or a synthetic base oil stock.
Likewise, these lubricating oils can be added to the oil
dispersions and additive compositions containing them, as described
herein, in additional amounts, to form finished lubricating oil
compositions. The hydrocarbon-based lubricating oils may be derived
from synthetic or natural sources and may be paraffinic, naphthenic
or aromatic base, or mixtures thereof. The diluent oil can be
natural or synthetic, and can be different viscosity grades.
[0117] In the oil dispersion of hydrated alkali metal borate, the
lubricating oil typically comprises from about 30 to about 70 wt %,
more preferably from about 45 to about 55 wt %, based on the total
weight of the oil dispersion of hydrated alkali metal borate.
[0118] When employed the oil dispersion of hydrated alkali metal
borate is present in the additive composition of the present
invention in the range of from about 1 to about 99 wt %, preferably
from about 5 to about 95 wt %, based on the total weight of the
additive composition.
[0119] Formulations
[0120] The additive composition of the present invention containing
the oil dispersion of hexagonal boron nitride and VI improver, and
optionally, the oil dispersion of hydrated alkali metal borate, may
be blended further with additional additives to form additive
packages containing the present additive compositions. These
additive packages typically comprise from about 10 to about 80 wt %
of the additive composition of the present invention described
above and from about 90 to about 20 wt % of one or more of
conventional additives selected from the group consisting of
ashless dispersants (0-10 wt %), detergents (0-5 wt %), sulfurized
hydrocarbons (0-40 wt %), dialkyl hydrogen phosphates (0-15 wt %),
zinc dithiophosphates (0-20 wt %), alkyl ammonium phosphates and/or
thio-dithiophosphates (0-20 wt %), phosphites (0 to 10 wt %) fatty
acid esters of polyalcohols (0-10 wt %), 2,5-dimercaptothiadiazole
(0-5 wt %), benzotriazole (0-5 wt %), dispersed molybdenum
disulfide (0-5 wt %), foam inhibitors (0-2 wt %), and imidazolines
(0-10 wt %) and the like wherein each wt % is based on the total
weight of the additive composition.
[0121] Fully formulated finished lubricating oil compositions of
this invention can be formulated from these additive packages upon
further blending with an oil of lubricating viscosity. Preferably,
the additive package described above is added to a base oil of
lubricating viscosity in an amount of from about 1 to about 40 wt
%, preferably from about 2 to about 20 wt %, to provide for the
finished lubricating oil composition wherein the wt % of the
additive package is based on the total weight of the lubricating
oil composition.
[0122] A variety of other additives can be present in lubricating
oils of the present invention. These additives include
antioxidants, rust inhibitors, corrosion inhibitors, extreme
pressure agents, antifoam agents, other anti-wear agents, and a
variety of other well-known additives in the art.
EXAMPLES
[0123] The invention will be further illustrated by the following
examples, which set forth particularly advantageous embodiments.
While the examples are provided to illustrate the present
invention, they are not intended to limit it.
Example 1
[0124] The additive composition of the present invention was
evaluated in a lubricating oil for its anti-sticking properties
following a test using an SAE No. 2 bench, which evaluates
transmission fluids during synchronization. The friction pairs used
in this bench comprised a brass synchronizer ring and a steel gear
cone.
[0125] During each cycle of the test, the cone is rotating, at a
given speed, then the ring moves along the axis of the cone for its
braking until it is blocked. At the end of each cycle, the ring is
disengaged.
[0126] If sticking occurs, a sticking torque is measured when
rotation of the cone is resumed. During the test, the lubricating
oil and the metal parts are heated to a temperature between about
60.degree. C. and about 90.degree. C. The contact pressure is about
20 MPa and the initial sliding speed is 1.6 m/s.
[0127] The anti-sticking coefficient for this test was calculated
as follows:
Anti - sticking coefficient = 1 - ( No . of cycles with sticking )
( Total No . of cycles in test ) ##EQU00001##
[0128] Accordingly, an anti-sticking coefficient of 0 indicates the
presence of cone on ring sticking during every cycle of the test.
Conversely, an anti-sticking coefficient of 1 indicates no sticking
at all was observed over the entire duration of the test. Thus, the
higher the anti-sticking coefficient, up to a maximum of 1, the
better the anti-sticking performance of the lubricating oil.
[0129] The test lubricating oil compositions were formulated as
follows, all the oils formulated have the same viscosity (about of
9 cSt):
Lubricant Composition 1
[0130] Lubricant composition 1 was prepared containing the
following: [0131] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, [0132] b) 12 wt % of a long
chain polymethacrylate VI Improver sold under the name
Viscoplex.RTM. 0-113 (available from RohMax Additives GmbH,
Darmstadt, Germany), and [0133] c) 78 wt % of a 50/50 mixture of
neutral oil (150N plus 600N) and synthetic polyalphaolefin oil.
Lubricant Composition 2
[0134] Lubricant composition 2 was prepared containing the
following: [0135] a) 10 wt of an oil dispersion of hexagonal boron
nitride, wherein the oil dispersion contained about 10 wt % of the
hexagonal boron nitride solids, dispersed in a 150 N neutral oil
containing a stabilizing agent, [0136] b) 12 wt % of a dispersant
long chain polymethacrylate VI Improver sold under the name
Viscoplex.RTM. 0-110 (available from RohMax Additives GmbH,
Darmstadt, Germany), and [0137] c) 78 wt % of a 50/50 mixture of
neutral oil (150N plus 600N) and synthetic polyalphaolefin oil.
Lubricant Composition 3
[0138] Lubricant composition 3 was prepared containing the
following: [0139] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, [0140] b) 12 wt % of a short
chain polymethacrylate VI Improver sold under the name
Viscoplex.RTM. 0-030 (available from RohMax Additives GmbH,
Darmstadt, Germany), and [0141] c) 78 wt % of a 50/50 mixture of
neutral oil (150N plus 600N) and synthetic polyalphaolefin oil.
Lubricant Composition 4
[0142] Lubricant composition 4 was prepared containing the
following: [0143] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, [0144] b) 12 wt % of a
dispersant ethylene-propylene olefin copolymer VI Improver with a
weight average molecular weight of about 39,000 (Paratone.RTM. 8500
available from Chevron Oronite Company, LLC, San Ramon, Calif.),
and [0145] c) 78 wt % of a 50/50 mixture of neutral oil (150N plus
600N) and synthetic polyalphaolefin oil.
Lubricant Composition 5
[0146] Lubricant composition 5 was prepared containing the
following: [0147] a) 7 wt % of an oil dispersion of hydrated
potassium triborate, wherein the oil dispersion contained about 30
wt % of the hydrated potassium triborate, dispersed in a 150N
neutral oil, [0148] b) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, [0149] c) 12 wt % of a long
chain polymethacrylate VI Improver sold under the name
Viscoplex.RTM. 0-113 (available from RohMax Additives GmbH,
Darmstadt, Germany), and [0150] d) 71 wt of a 50/50 mixture of
neutral oil (150N plus 600N) and synthetic polyalphaolefin oil.
Lubricant Composition A (Comparative)
[0151] Comparative lubricant composition A was prepared containing
the following: [0152] a) 7 wt % of an oil dispersion of hydrated
potassium triborate, wherein the oil dispersion contained about 30
wt % of the hydrated potassium triborate, dispersed in a 150 N
neutral oil, and [0153] b) 93 wt % of a 50/50 mixture of neutral
oil (150N plus 600N) and synthetic polyalphaolefin oil.
Lubricant Composition B (Comparative)
[0154] Comparative lubricant composition B was prepared containing
the following: [0155] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contains about 10 wt % of
the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, and [0156] b) 90 wt % of a
50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition C (Comparative):
[0157] Comparative lubricant composition C was prepared containing
the following: [0158] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, [0159] b) 12 wt % of a
non-dispersant type ethylene-propylene olefin copolymer VI Improver
with a weight average molecular weight of about 90,000
(Paratone.RTM.8002 available from Chevron Oronite Company, LLC, San
Ramon, Calif.), and [0160] c) 78 wt % of a 50/50 mixture of neutral
oil (150N plus 600N) and synthetic polyalphaolefin oil.
Lubricant Composition D (Comparative):
[0161] Comparative lubricant composition D was prepared containing
the following: [0162] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent, [0163] b) 0.5 wt % of a
polyisobutenyl mono-succinimide, and [0164] c) 89.5 wt % of a 50/50
mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition E (Comparative):
[0165] Comparative lubricant composition E was prepared containing
the following: [0166] a) 10 wt % of an oil dispersion of hexagonal
boron nitride, wherein the oil dispersion contained about 10 wt %
of the hexagonal boron nitride solids, dispersed in a 150 N neutral
oil containing a stabilizing agent [0167] b) 0.5 wt % of a
polyisobutenyl bis-succinimide, and [0168] c) 89.5 wt % of a 50/50
mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
TABLE-US-00001 [0168] TABLE 1 No. of Cycles with Cone on Total No.
of Anti-sticking Sample Ring Sticking Cycles coefficient Base oil
5000 5000 0 Comparative Composition A 8100 8100 0 Comparative
Composition B 6600 6600 0 Comparative Composition C 5700 5700 0
Comparative Composition D 6400 6400 0 Comparative Composition E
8100 8100 0 Composition 1 500 7100 0.93 1050 5600 0.81 Composition
2 100 6800 0.99 Composition 3 1200 6850 0.82 Composition 4 200
20000 0.99 Composition 5 650 20000 0.97
[0169] The above data demonstrates that the additive composition of
the present invention provides significant anti-sticking
performance and shows a marked improvement over the comparative
compositions.
[0170] From the foregoing description, various modifications and
changes in the above-described invention will occur to those
skilled in the art. All such modifications coming within the scope
of the appended claims are intended to be included therein.
* * * * *