U.S. patent application number 10/275139 was filed with the patent office on 2005-03-24 for nanosized particles of molybdenum sulfide and derivatives,method for its preparation and uses thereof as lubricant additive.
Invention is credited to Bakunin, Victor N, Kuz'mina, Galina N, Migdal, Cyril A, Parenago, Oleg P, Stott, Paul E, Suslov, Andrei Yu, Vedeneeva, Ludmila M.
Application Number | 20050065044 10/275139 |
Document ID | / |
Family ID | 34312009 |
Filed Date | 2005-03-24 |
United States Patent
Application |
20050065044 |
Kind Code |
A1 |
Migdal, Cyril A ; et
al. |
March 24, 2005 |
NANOSIZED PARTICLES OF MOLYBDENUM SULFIDE AND DERIVATIVES,METHOD
FOR ITS PREPARATION AND USES THEREOF AS LUBRICANT ADDITIVE
Abstract
A lubricant composition is disclosed that comprises: (a) a
lubricant and (b) at least one molybdenum-containing compound in
the form of surface-capped nanosized particles of the general
formula: (Z).sub.n(X--R).sub.m wherein Z is an inorganic moiety
comprising molybdenum and sulfur in the form of particles having
dimensions in the range of from about 1 to about 100 nm; (X--R) is
a surface-capping reagent wherein R is a C.sub.4 to C.sub.20
straight or branched-chain alkyl or alkylated cycloalkyl radical or
radicals and X is a functional group capable of specific sorption
and/or chemical interaction with molybdenum/sulfur moiety; n is the
number of molecules of Z in the particles; m is an integer
representing the amount of surface-capping reagents relative to a
single particle; and the ratio of m to n is in the range of from
about 1:1 to about 10:1.
Inventors: |
Migdal, Cyril A; (Pleasant
Valley, NY) ; Stott, Paul E; (Southbury, CT) ;
Bakunin, Victor N; (Moscow, RU) ; Parenago, Oleg
P; (Moscow, RU) ; Kuz'mina, Galina N; (Moscow,
RU) ; Vedeneeva, Ludmila M; (Moscow, RU) ;
Suslov, Andrei Yu; (Moscow, RU) |
Correspondence
Address: |
Michael P Dilworth
Crompton Corporation
199 Benson Road
Middlebury
CT
06749
US
|
Family ID: |
34312009 |
Appl. No.: |
10/275139 |
Filed: |
March 18, 2003 |
PCT Filed: |
May 8, 2001 |
PCT NO: |
PCT/US01/14982 |
Current U.S.
Class: |
508/230 ;
508/362; 508/363; 508/381 |
Current CPC
Class: |
C10M 171/06 20130101;
C10M 159/18 20130101 |
Class at
Publication: |
508/230 ;
508/362; 508/363; 508/381 |
International
Class: |
C10M 159/18; C10M
171/06 |
Claims
1. A lubricant composition comprising: A) a lubricant, and B) at
least one molybdenum-containing compound in the form of
surface-capped nanosized particles of the general formula
(Z).sub.n(X--R).sub.m wherein: Z is selected from the group
consisting of MoS.sub.3, MoS.sub.2O, Na.sub.2MoS.sub.4,
Na.sub.2MoS.sub.3O, (NH.sub.4).sub.2MoS.sub.4,
(NH.sub.4).sub.2MoS.sub.3O, and hydrates thereof in the form of
particles having dimensions in the range of from about 1 to about
100 nm; (X--R) is a surface-capping reagent selected from the group
consisting of alkyl amines, dialkyl amines, trialkyl amines,
carboxylic acids, dicarboxylic acids, carboxylic acid amides,
dicarboxylic acid diamides, alicyclic imides, ammonium or alkali
metal dialkyldithiocarbamates, divalent metal
bis-dialkyldithiocarbamates, trivalent metal
tris-dialkyldithiocarbamates- , tetraalkyl thiuram disulfides, and
derivatives thereof; n is the number of molecules of Z in the
particles; m is an integer representing the amount of
surface-capping, reagents relative to a single particle; and the
ratio of m to n is in the range of from about 1:1 to about
10:1.
2-3. (Canceled)
4. The lubricant composition of claim 1 wherein the alkyl amines,
dialkyl amines, and trialkyl amines are of the formula
R.sup.1R.sup.2R.sup.3N wherein: R.sup.1, R.sup.2, and R.sup.3 are
independently selected from the group consisting of hydrogen,
straight or branched-chain C.sub.1-C.sub.20 alkyl, C.sub.6-C.sub.16
alkylaryl, and aryl.
5. The lubricant composition of claim 1 wherein the carboxylic
acids and carboxylic acid amides are of the formula 17wherein X is
OH, NH.sub.2, NHR.sup.4, or NR.sup.4R.sup.4 and R.sup.4 is an
straight or branched-chain, saturated or partially unsaturated,
alkyl moiety of from 1 to 40 carbon atoms.
6. The lubricant composition of claim 1 wherein the alicyclic
imides are of the formula 18wherein R.sup.5 is hydrogen,
(C.dbd.O)NHR.sup.7, or an alkylene amine wherein pairs of nitrogens
are joined by alkylene groups, R.sup.6 is hydrogen, straight or
branched-chain (C.sub.2-C.sub.400)alkyl, and R.sup.7 is H or
(C.sub.1-C.sub.20)alkyl.
7. The lubricant composition of claim 1 wherein the ammonium or
alkali metal dialkyldithiocarbamates are of the formula 19wherein
R.sup.8 and R.sup.9 are independently selected from the group
consisting of (C.sub.1-C.sub.24)alkyl and M.sup.+ is Na.sup.+,
K.sup.+, or NH.sub.4.sup.+.
8. The lubricant composition of claim 1 wherein the divalent metal
bis-dialkyldithiocarbamate is a compound of the formula 20wherein
R.sup.8 and R.sup.9 are selected from the group consisting of
(C.sub.1-C.sub.24)alkyl and M.sup.+2 is Fe.sup.+2, Zn.sup.+2,
Pb.sup.+2, or Cu.sup.+2.
9. The lubricant composition of claim 1 wherein the trivalent metal
tris-dialkyldithiocarbamates are of the formula 21wherein R.sup.8
and R.sup.9 are selected from the group consisting of
(C.sub.1-C.sub.24)alkyl and M.sup.+3 is Sb.sup.+3 or Bi.sup.+3.
10. The lubricant composition of claim 1 wherein the tetraalkyl
thiuram disulfides are of the formula 22wherein R.sup.8 and R.sup.9
are independently selected from the group consisting, of
(C.sub.1-C.sub.24)alkyl.
11. The lubricant composition of claim 1 wherein the
molybdenum-containing compound in the form of surface-capped
nanosized particles is employed in an amount of about 0.2 to about
5% by weight.
12. The lubricant composition of claim 11 further comprising at
least one additional additive selected from the group consisting of
dispersants, detergents, rust inhibitors, antioxidants, metal
deactivators, anti-wear agents, antifoamants, friction modifiers,
seal swell agents, demulsifiers, VI improvers, and pour point
depressants.
13. A process for preparing a molybdenum-containing compound in the
form of surface-capped nanosized particles of the general formula
(Z).sub.n(X--R).sub.m wherein: Z is selected from the group
consisting of MoS.sub.3, MoS.sub.2O, Na.sub.2MoS.sub.4,
Na.sub.2MoS.sub.3O, (NH.sub.4).sub.2MoS.sub.4,
(NH.sub.4).sub.2MoS.sub.3O and hydrates thereof in the form of
particles having dimensions in the range of from about 1 to about
100 nm; (X--R) is a surface-capping reagent selected from the group
consisting of alkyl amines, dialkyl amines, trialkyl amines,
carboxylic acids, dicarboxylic acids, carboxylic acid amides,
dicarboxylic acid diamides, alicyclic imides, ammonium or alkali
metal dialkyldithiocarbamates, divalent metal
bis-dialkyldithiocarbamates, trivalent metal
tris-dialkyldithiocarbamates, tetraalkyl thiuram disulfides, and
derivatives thereof; n is the number of molecules of Z in the
particles; m is an integer representing the amount of
surface-capping reagents relative to a single particle; and the
ratio of m to n is in the range of from about 1:1 to about 10:1;
wherein the process comprises the steps of A) creating a reversed
microemulsion comprising a hydrocarbon-soluble surfactant solution
in an organic solvent or solvent mixture and an aqueous solution of
a water-soluble inorganic molybdenum (VI) compound; B) if necessary
to create a molybdenum/sulfur moiety, converting the water-soluble
inorganic molybdenum (VI) compound into a thio-derivative by
reaction with hydrogen sulfide; C) adding a surfactant that
chemically interacts with and/or adsorbs on the molybdenum/sulfur
moiety; D) removing water and the organic solvent(s) from the
microemulsion and extracting the molybdenum/sulfur
moiety-containing products thereof in the form of surface-capped
nanosized particles with a suitable organic solvent; and E)
removing said suitable organic solvent.
14. (Canceled)
15. The process of claim 13 wherein the hydrocarbon-soluble
surfactant is a cationic, anionic, or non-ionic surfactant.
16. The process of claim 15 wherein the hydrocarbon-soluble
surfactant is cationic.
17. The process of claim 16 wherein the surfactant is
tetraalkylammonium halide.
18. The process of claim 17 wherein the surfactant is
cetyltrimethylammonium halide.
19. The process of claim 18 wherein the cetyltrimethylammonium
halide is dissolved in chloroform:n-alkane (1:1 v/v) in a
concentration of 0.01 to 0.1 mol/L.
20. The process of claim 19 wherein the n-alkane is selected from
the group consisting of pentane, hexane, heptane, octane and
isomers and mixtures thereof.
21. The process of claim 13 wherein the aqueous solution of
water-soluble inorganic molybdenum (VI) compounds has pH less than
or equal to 8.
22. The process of claim 13 wherein the surfactant that chemically
interacts with and/or adsorbs on the molybdenum/sulfur moiety is
added to the microemulsion in step A) or step B).
23. The process of claim 13 wherein the surfactant that chemically
interacts with and/or adsorbs on the molybdenum/sulfur moiety is
selected from the group consisting of alkyl amines, dialkyl amines,
trialkyl amines, carboxylic acids, dicarboxylic acids, carboxylic
acid amides, dicarboxylic acid diamides, alicyclic imides, ammonium
or alkali metal dialkyldithiocarbamates, divalent metal
bis-dialkyldithiocarbamates, trivalent metal
tris-dialkyldithiocarbamates, tetraalkyl thiuram disulfides, and
derivatives thereof.
24. The process of claim 23 wherein the alkyl amines, dialkyl
amines, trialkyl amines are of the formula R.sup.1R.sup.2R.sup.3N
wherein R.sup.1, R.sup.2, and R.sup.3 are independently selected
from the group consisting of hydrogen, straight or branched-chain
C.sub.1-C.sub.28 alkyl, C.sub.6-C.sub.34 alkylaryl, and aryl.
25. The process of claim 23 wherein the carboxylic acids, and
carboxylic acid amides are of the formula 23wherein X is OH,
NH.sub.2, NHR.sup.4, or NR.sup.4R.sup.4 and R.sup.4 is an straight
or branched-chain, saturated or partially unsaturated, alkyl moiety
of from 1 to 40 carbon atoms.
26. The process of claim 23 wherein the alicyclic imides are of the
formula 24wherein R.sup.5 is selected from the group consisting, of
hydrogen, (C.dbd.O)NH--R.sup.7, and alkylene amines wherein pairs
of nitrogens are joined by alkylene groups; R.sup.6 is selected
from the group consisting of hydrogen and straight and
branched-chain (C.sub.2-C.sub.400)alkyl; and R.sup.7 is hydrogen or
(C.sub.1-C.sub.20)alkyl.
27. The process of claim 23 wherein the alkali metal
dialkyldithiocarbamates are of the formula 25wherein R.sup.8 and
R.sup.9 are independently selected from the group consisting of
(C.sub.1-C.sub.24)alkyl and M.sup.+ is Na.sup.+, K.sup.+, or
N.sub.4.sup.+.
28. The process of claim 23 wherein the divalent metal
bis-dialkyldithiocarbamates are of the formula 26wherein R.sup.8
and R.sup.9 are independently selected from the group consisting of
(C.sub.1-C.sub.4)alkyl and M.sup.+2 is Fe.sup.+2, Zn.sup.+2,
Pb.sup.+2, or Cu.sup.+2.
29. The process of claim 23 wherein the trivalent metal
tris-dialkyldithiocarbamates are of the formula 27wherein R.sup.8
and R.sup.9 are selected from the group consisting of
(C.sub.1-C.sub.24)alkyl and M.sup.+3 is Sb.sup.+3 or Bi.sup.+3.
30. The process of claim 23 wherein the thiuram disulfides are of
the formula 28wherein R' and R" are independently selected from the
group consisting of (C.sub.1-C.sub.24)alkyl.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to organo molybdenum derivatives and
their use as multifunctional friction modifier, antiwear, extreme
pressure, antioxidant additives for lubricants.
[0003] 2. Description of Related Art
[0004] Regulatory agencies today are seeking to improve the fuel
economy of cars on the road through legislation (CAFE requirements)
putting this responsibility on the car manufacturers who, in turn,
transfer some of this responsibility to the lubricant oil
manufacturers via engine oil specifications. It can be seen that as
these fuel economy requirements become more stringent, friction
modifier additives become more important to incorporate into
lubricant compositions. It is an object of this invention to
provide a friction modifier additive that imparts a reduction in
the coefficient of friction to a lubricant composition.
[0005] In addition, zinc dialkyldithiophosphates (ZDDP) have been
used in formulated oils as anti-wear and antioxidant additives for
more than 50 years. However, zinc dialkyldithiophosphates give rise
to ash, which contributes to particulate matter in automotive
exhaust emissions. Regulatory agencies are seeking to reduce
emissions of zinc into the environment. In addition, the phosphorus
is also suspected of limiting the service life of catalytic
converters, used on cars to reduce pollution. It is important to
limit the particulate matter and pollution formed during engine use
for toxicological and environmental reasons, but it is also
important to maintain, undiminished, the anti-wear and antioxidant
properties of the lubricating oil. In view of the aforementioned
shortcomings of the known zinc and phosphorus-containing additives,
it is a further object of this invention to provide anti-wear and
antioxidant additives that contain neither zinc nor phosphorus.
[0006] In developing lubricating oils, there have been many
attempts to provide additives that impart anti-frictional or
oiliness properties to lubricating oils and molybdenum compounds
are known to be useful as friction modifiers, anti-wear, extreme
pressure, and antioxidants in lubrication oil compositions.
[0007] Thiocarbamate additives for lubricating oils, particularly
molybdenum-containing thiocarbamates have been disclosed in the
patent literature. For example, U.S. Pat. Nos. 4,395,343;
4,402,840; 4,285,822; 4,265,773; 4,272,387; 4,369,119; 4,259,195;
4,259,194; and 4,283,295, all to DeVries and King, disclose a
variety of molybdenum, sulfur, and nitrogen containing compounds,
including dithiocarbamates, that are useful as antioxidants for
lubricants.
[0008] U.S. Pat. No. 3,509,051 discloses various molybdenum
dialkyldithiocarbamates, derived from secondary amines, which are
said to be useful as antioxidant and antiwear compounds for
lubricating oils.
[0009] Complexes of molybdenum oxides and nitrogen-containing
moieties, including dialkyldithiocarbamates, which are said to have
utility as additives for lubricants, are disclosed in U.S. Pat. No.
3,419,589 to Larson et al and U.S. Pat. No. 4,164,473 to Coupland
et al.
[0010] U.S. Pat. No. 3,541,014 to LeSuer discloses molybdenum
complexes of Group II metal-containing compounds, e.g., overbased
Group II metal sulfonates that are said to improve extreme pressure
properties and antiwear properties in lubricant compositions.
[0011] A molybdenum dihydrocarbyldithiocarbamate compound said to
be useful as an additive for lubricants is disclosed in U.S. Pat.
No. 4,098,705 to Sakurai et al.
[0012] U.S. Pat. No. 4,266,945 discloses the preparation of
molybdenum-containing compositions by the reaction of an acid of
molybdenum or salt thereof, phenol or aldehyde condensation product
therewith, and a primary or secondary amine. The preferred amines
are diamines such as tallow-substituted trimethylene diamine and
their formaldehyde condensation products. An optional but preferred
ingredient in the reaction mixture is at least one oil-soluble
dispersant. The molybdenum-containing compositions are said to be
useful as additives in lubricants and fuels, especially in
lubricants when combined with compounds containing active
sulfur.
[0013] Sulfur and phosphorus-containing molybdenum compositions
said to be useful for improving fuel economy for internal
combustion engines are disclosed in U.S. Pat. No. 4,289,635 to
Schroeck.
[0014] U.S. Pat. No. 4,315,826 discloses multipurpose lubricant
additives that are prepared by reaction of carbon disulfide with
thiomolybdenum derivatives of polyalkenylsuccinimides having basic
nitrogen functions. The subject additives function as dispersants
and are said to possess excellent anti-frictional properties and to
impart anti-wear and anti-oxidant properties to a lubricant.
[0015] U.S. Pat. No. 4,474,673 discloses the preparation of
anti-friction additives for lubricating oil by reacting a
sulfurized organic compound having an active hydrogen or
potentially active hydrogen with a molybdenum halide.
[0016] U.S. Pat. No. 4,479,883 discloses a lubricating oil
composition that contains a relatively low level of phosphorus and
is said to have particularly improved friction reducing properties
that comprises an ester of a polycarboxylic acid with a glycol or
glycerol and a selected metal dithiocarbamate.
[0017] U.S. Pat. No. 4,501,678 discloses a lubricant containing
molybdenum dialkyldithiocarbamates said to be useful for improving
fatigue life of gears.
[0018] U.S. Pat. No. 4,765,918 discloses the preparation of a
lubricating oil additive by reacting a triglyceride with a basic
nitrogen compound to form a reaction product, reacting said
reaction product with an acidic molybdenum compound to form an
intermediate reaction product, and reacting said intermediate
reaction product with a sulfur compound to produce a lubricating
oil additive.
[0019] U.S. Pat. No. 4,889,647 discloses molybdenum complexes
prepared by reacting (a) a fatty oil, (b) diethanolamine, and (c) a
molybdenum source. The molybdenum complexes are said to impart
antifriction and antiwear properties to lubricating compositions
and to decrease fuel consumption in internal combustion engines
using them.
[0020] U.S. Pat. No. 4,995,996 discloses a lubricating composition
comprising a major amount of an oil of lubricating viscosity and a
minor amount of an additive having the formula Mo.sub.2L.sub.4
wherein L is a ligand selected from xanthates and mixtures thereof
and, in particular, xanthates having a sufficient number of carbon
atoms to render the additive soluble in the oil. In general, the
xanthate ligand, L, will have from about 2 to 30 carbon atoms.
[0021] U.S. Pat. No. 5,498,809 discloses oil soluble copolymers
derived from ethylene and 1-butene that have a number average
molecular weight between about 1,500 and 7,500, at least about 30
percent of all polymer chains terminated with ethylvinylidene
groups, and ethylene-derived content of not greater than about 50
weight percent, and which form solutions in mineral oil free of
polymer aggregates, as determined by light scattering measurements.
Lubricating oil additives, particularly dispersants, produced by
the functionalization and derivatization of these copolymers are
said to have enhanced performance (e.g., improved dispersancy and
pour point) in lubricating oil compositions, attributable in part
to the combination of properties characterizing the copolymers.
[0022] The preparation of nanosized surface-capped inorganic
sulfides via intermediate reverse microemulsion formation is
described in the following references:
[0023] Boakye et al. J. Coll. Interface Sci. 163(1): 120-129 (1994)
describe the synthesis of molybdenum sulfide nanosized particles in
the range of 10-80 nm without surface-capping reagents.
[0024] Deng et al., Chem. Lett. (6):483-484 (1997) describe a novel
synthetic approach to CdS nanoparticles capped with an electric
neutral surface capping agent of 2,2-bipyridine in
sodium(bis-2-ethylhexyl) sulfosuccinate (AOT) reverse micelle.
[0025] Huang et al., Langmuir 13(2):172-175 (1997) describe copper
nanoparticles capped with poly-(N-vinylpyrrolidone) and prepared by
the reduction of Copper II acetate in water and 2-ethoxyethanol
using hydrazine under reflux.
[0026] Meldrum et al. J. Chem. Soc. Faraday Trans. 91 (4):673-680
(1995) describe the formation of thin particulate films from silver
nanoparticles, generated by the sodium borohydride reduction of
aqueous silver nitrate within sodium(bis-2-ethylhexyl)
sulfosuccinate reverse micelles in 2,2,4-trimethylpentane and
capped with octadecanethiol.
[0027] Motte et al., J. Phys III 7(3):517-527 (1997) describe
reverse micelles that have been used to synthesize 5.6 nm silver
sulfide particles. These nanoparticles are coated with
dodecanethiol, extracted from reverse micelles, and then dissolved
in heptane.
[0028] Motte et al., J. Phys. Chem., 99(44):16425-16429 (1995)
describe utilization of dodecanethiol for surface capping of
various metal sulfide nanosized particles.
[0029] Pileni et al. Surf. Rev. Letters 3(1):1215-1218 (1996)
describe synthesis of silver sulfide semiconductor clusters
encapped with dodecanethiol.
[0030] Steigerwald et al. J. Amer. Chem. Soc. 110(10):3046-3050
(1988) describe a synthesis of nanometer-sized clusters of CdSe
using organometallic reagents in inverse micellar solution and
chemical modification of the surface of these cluster compounds to
form a PhSe layer on the CdSe surface.
[0031] Yanagida et al. Bull. Chem. Soc. Jpn. 68(3):752-758 (1995)
describe size-controlling CdS nanocrystallites that were prepared
by using thiophenol or hexanethiol as a capping reagent by
controlling the ratio of Cd.sup.++ to bis(trimethylsilyl) sulfide
as a source of the sulfide ion in reversed micelles.
[0032] Unfortunately, a problem remains in that many molybdenum
compounds exhibit poor solubility in lubricant oils. No disclosures
are known to the present inventors that teach or even suggest
nanosize particles comprising a molybdenum/sulfur moiety whose
surface is modified with an appropriate ligand that prevents the
coagulation of the nanoparticles and provides their solubility and
stability in hydrocarbons or similar solvents, which further
improves anti-wear properties, antioxidant properties, extreme
pressure properties, and friction modifying properties in
lubricating oil compositions.
SUMMARY OF THE INVENTION
[0033] The additives of the present invention are complex reaction
products prepared in a series of reactions. The additives are
molybdenum sulfide nanosized particles [MoS.sub.x] whose surfaces
are modified with one or more appropriate ligands to prevent the
coagulation of the nanoparticles and provide solubility and
stability therefor in hydrocarbons or similar solvents.
[0034] More specifically, the present invention is directed to a
lubricant composition comprising:
[0035] A) a lubricant, and
[0036] B) at least one molybdenum-containing compound in the form
of surface-capped nanosized particles of the general formula
(Z).sub.n(X--R).sub.m
[0037] wherein:
[0038] Z is an inorganic moiety comprising molybdenum and sulfur in
the form of particles having dimensions in the range of from about
1 to about 100 nm;
[0039] (X--R) is a surface-capping reagent wherein R is a C.sub.4
to C.sub.20 straight or branched-chain alkyl or alkylated
cycloalkyl radical or radicals and X is a functional group capable
of specific sorption and/or chemical interaction with the
molybdenum/sulfur moiety;
[0040] n is the number of molecules of Z in the particles;
[0041] m is an integer representing the amount of surface-capping
reagents relative to a single particle; and
[0042] the ratio of m to n is in the range of from about 1:1 to
about 10:1.
[0043] In another aspect, the present invention is directed to a
process for preparing a molybdenum-containing compound in the form
of surface-capped nanosized particles of the general formula
(Z).sub.n(X--R).sub.m
[0044] wherein:
[0045] Z is an inorganic moiety comprising molybdenum and sulfur in
the form of particles having dimensions in the range of from about
1 to about 100 nm;
[0046] (X--R) is a surface-capping reagent wherein R is a C.sub.4
to C.sub.20 straight or branched-chain alkyl or alkylated
cycloalkyl radical or radicals and X is a functional group capable
of specific sorption and/or chemical interaction with the
molybdenum/sulfur moiety;
[0047] n is the number of molecules of Z in the particles;
[0048] m is an integer representing the amount of surface-capping
reagents relative to a single particle; and
[0049] the ratio of m to n is in the range of from about 1:1 to
about 10:1;
[0050] wherein the process comprises the steps of:
[0051] A) creating a reversed microemulsion comprising a
hydrocarbon-soluble surfactant solution in an organic solvent or
solvent mixture and an aqueous solution of a water-soluble
inorganic molybdenum (VI) compound;
[0052] B) if necessary to create a molybdenum/sulfur moiety,
converting the water-soluble inorganic molybdenum (VI) compound
into a thio-derivative by reaction with hydrogen sulfide;
[0053] C) adding a surfactant that chemically interacts with and/or
adsorbs on the molybdenum/sulfur moiety;
[0054] D) removing water and the organic solvent(s) from the
microemulsion and extracting the molybdenum/sulfur
moiety-containing products thereof in the form of surface-capped
nanosized particles with a suitable organic solvent; and
[0055] E) removing said suitable organic solvent.
[0056] The present invention is also directed to the use of the
surface-capped nanosize molybdenum sulfide derivative particles as
friction modifying, antiwear, extreme pressure, and antioxidant
additives for lubricating oils.
[0057] The present invention is also directed to lubricating oil
compositions comprising a lubricating oil and a
functional-property-impro- ving amount of the surface-capped
nanosize molybdenum/sulfur moiety-containing particles described
above.
[0058] Preferably, the present invention is directed to a
composition comprising:
[0059] A) a lubricant;
[0060] B) surface-capped nanosize molybdenum/sulfur
moiety-containing particles; and, optionally,
[0061] C) one or more auxiliary additives selected from the group
consisting of dispersants, detergents, rust inhibitors,
antioxidants, metal deactivators, anti-wear agents, antifoamants,
friction modifiers, seal swell agents, demulsifiers, VI improvers,
and pour point depressants.
BRIEF DESCRIPTION OF THE DRAWINGS
[0062] FIGS. 1 through 3 are UV spectra that are illustrative of
the formation of partially substituted thiomolybdate
derivatives.
[0063] FIG. 4 is a UV spectrum containing no absorption bands,
which is typical of the spectra of nanosized inorganic particles
formed in the interior of reverse micelles.
[0064] FIG. 5 is the UV spectrum of molybdenum sulfide
nanoparticles prepared in the presence of isopropyloctadecyl
amine.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0065] The present invention provides a lubricant composition,
e.g., a lubricating oil composition, comprising an organo
molybdenum additive that imparts friction modification, antiwear,
extreme pressure, antioxidant properties to the lubricant. The
additive is a reaction product of any water-soluble inorganic
molybdenum compound dissolved in the aqueous interior of a reversed
microemulsion with hydrogen sulfide at an appropriate pH value to
form a molybdenum sulfide derivative according to the following
chemical reactions: 1
[0066] The approach of the present invention includes the formation
of reverse microemulsions stabilized with one or more selected
surfactants (e.g., tetralkylammonium salts) in a convenient solvent
or solvent mixture wherein the mixture comprises the molybdenum
salt solution in the interior of the reverse microemulsion.
Subsequent interaction with H.sub.2S results in the formation of
MoS.sub.3 or MoS.sub.4.sup.-2 nanoparticles (depending on the pH
value of the aqueous solution) in the interior of microemulsions.
Further reaction with a long hydrocarbon chain-containing ligand
such as a dialkyl amine, a dialkyl dithiocarbamate derivative, or
the like provides modification of the nanoparticle surface, thereby
fixing their size and shape and providing reasonable solubility and
stability in hydrocarbon-type lubricating oils. In this approach
the size and shape of modified [MoS.sub.x] nanoparticles are
governed by the structure of the microemulsion and by the
concentration of the respective molybdenum salts in the aqueous
core of the microemulsion.
[0067] The following compounds are examples of water-soluble
inorganic molybdenum compounds that can be used in the synthesis of
the molybdenum sulfide derivatives:
[0068] Sodium tetrathiomolybdate Na.sub.2MoS.sub.4;
[0069] Ammonium tetrathiomolybdate (NH.sub.4).sub.2MoS.sub.4;
[0070] Sodium molybdate Na.sub.2MoO.sub.4;
[0071] Ammonium paramolybdate (H.sub.4).sub.6Mo.sub.7O.sub.24;
[0072] Molybdenum trioxide MoO.sub.3;
[0073] and hydrates thereof.
[0074] The molybdenum sulfide derivatives formed according to the
above reaction scheme in the interior of the reverse microemulsions
represent a dispersion stabilized by one or more surfactants in one
or more appropriate organic solvents. The surfactants that can be
utilized in the practice of the present invention are oil-soluble
cationic, anionic, and nonionic surfactants capable of formation of
reverse microemulsions in non-polar solvents, such as paraffin,
iso-paraffin, aromatic or alkylaromatic hydrocarbons, halogenated
hydrocarbons, or mixtures thereof.
[0075] The following compounds are examples of oil-soluble
surfactants that can be used in the preparation of the reverse
microemulsions:
[0076] Cationic Surfactants
[0077] Cetyltrimethylammonium bromide (CTAB, Fluka);
[0078] Tricaprylmethylammonium chloride (Aliquate.RTM. 336,
Aldrich);
[0079] Methyltrialkyl(C.sub.8-C.sub.10)ammonium chloride
(Adogene.RTM.464, Aldrich);
[0080] Anionic Surfactants
[0081] Sodium bis(2-ethylhexyl)sulfosuccinate (AOT) (Fluka);
[0082] Nonionic Surfactants
[0083] Triton.RTM. X-100 (Aldrich);
[0084] Triton.RTM. X-114 (Aldrich).
[0085] In order to provide further flocculation stability, the
molybdenum sulfide particles are capped with an appropriate
surface-capping reagent in accordance with the following scheme:
2
[0086] The surface-capping reagents represented by the general
formula R--X are selected from the compounds comprising a
C.sub.2-C.sub.400 straight or branched-chain alkyl or alkylated
cycloalkyl radical or radicals k and a functional group X that is
capable of specific sorption and/or chemical interaction with a
molybdenum sulfide moiety.
[0087] Examples of functional groups capable of specific sorption
and/or chemical interaction with the molybdenum/sulfur moiety
include amines, amides, imides, dithiocarbamates, thiuram
disulfides, carboxy groups, and the like.
[0088] Preferably, (X--R) is selected from the group consisting of
alkyl amines, dialkyl amines, trialkyl amines, carboxylic acids,
dicarboxylic acids, carboxylic acid amides, dicarboxylic acid
diamides, alicyclic imides, ammonium or alkali metal
dialkyldithiocarbamates, divalent metal
bis-dialkyldithiocarbamates, trivalent metal
tris-dialkyldithiocarbamates- , tetraalkyl thiuram disulfides, and
derivatives thereof.
[0089] Preferably, the alkyl amines, dialkyl amines, and trialkyl
amines are of the formula
R.sup.1R.sup.2R.sup.3N
[0090] wherein: R.sup.1, R.sup.2, and R.sup.3 are independently
selected from the group consisting of hydrogen, straight or
branched-chain C.sub.1-C.sub.28, alkyl, C.sub.6-C.sub.34 alkylaryl,
and aryl.
[0091] Preferably, the carboxylic acids, dicarboxylic acids,
carboxylic acid amides, and dicarboxylic acid diamides are of the
formula 3
[0092] wherein X is OH, NH.sub.2, NHR.sup.4, or N.sup.4R.sup.4 and
R.sup.4 is an straight or branched-chain, saturated or partially
unsaturated, alkyl moiety of from 1 to 40 carbon atoms, e.g.,
methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl,
octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,
pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl,
eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl,
triacontyl, pentatriacontyl, tetracontyl, and the like, and isomers
and mixtures thereof.
[0093] Preferably, the alicyclic imides are of the formula: 4
[0094] wherein R.sup.5 is hydrogen, (C.dbd.O)NHR.sup.7, or an
alkylene amine wherein pairs of nitrogens are joined by alkylene
groups, R.sup.6 is hydrogen, straight or branched-chain
(C.sub.2-C.sub.400)alkyl, and R.sup.7 is H or
(C.sub.1-C.sub.20)alkyl.
[0095] Preferably, the ammonium or alkali metal
dialkyldithiocarbamates are of the formula 5
[0096] wherein R.sup.8 and R.sup.9 are independently selected from
the group consisting of (C.sub.1-C.sub.24)alkyl and M.sup.+ is
Na.sup.+, K.sup.+, or NH.sub.4.sup.+.
[0097] Preferably, the divalent metal bis-dialkyldithiocarbamates
are of the formula 6
[0098] wherein R.sup.8 and R.sup.9 are selected from the group
consisting of (C.sub.1-C.sub.24)alkyl and M.sup.+2 is Fe.sup.+2,
Zn.sup.+2, Pb.sup.+2, or Cu.sup.+2.
[0099] Preferably, the trivalent metal tris-dialkyldithiocarbamates
are of the formula 7
[0100] wherein R.sup.8 and R.sup.9 are selected from the group
consisting of (C.sub.1-C.sub.24)alkyl and M.sup.+3 is Sb.sup.+3 or
Bi.sup.+3.
[0101] Preferably, the tetraalkyl thiuram disulfides are of the
formula wherein R.sup.8 and R.sup.9 are independently selected from
the group consisting of (C.sub.1-C.sub.24)alkyl.
[0102] The following compounds are examples of those that can be
used to adsorb on and/or react with the surface of the molybdenum
sulfide derivative nanosize particles of the present invention:
[0103] Sec-butyl amine;
[0104] Isopropyl(octadecyl)amine;
[0105] Docosanoic (behenic) acid (C.sub.22 carboxylic acid)
(Schuchardt, Munchen);
[0106] Alkenylsuccinimide (Polyisobutenylsuccinimide) (Uniroyal
Chemical Co.);
[0107] Sodium di(2-ethylhexyl)dithiocarbamate;
[0108] Sodium di(hexadecyl)dithiocarbamate (Uniroyal Chemical Co.);
8
[0109] Tetra(2-ethylhexyl)thiuram disulfide;
[0110] Tetra(hexadecyl)thiuram disulfide (Uniroyal Chemical
Co.).
[0111] The alkenylsuccinimides, as well as other ashless
dispersants, useful in the practice of this invention are described
below.
[0112] Various types of ashless dispersants (alkenylsuccinimides)
can be made by functionalizing and/or derivatizing hydrocarbon
polymers that are suitable for use in the lubricant compositions.
The term "polymer" is used herein to refer to any hydrocarbon
group, either branched or linear, containing 40-1500 carbon atoms.
One of the most common types of polymer is polyisobutylene (PIB)
based on a hydrocarbon chain of a number average molecular weight
(Mn) of from about 500 to about 3000. Another type is based upon
ethylene, alpha-olefin copolymer chains of a number average
molecular weight (Mn) of from about 500 to about 25,000.
[0113] The polymers can be functionalized, by which is meant that
they can be chemically modified to have at least one functional
group present within their structures, which functional groups are
capable of: (a) undergoing further chemical reaction (e.g.
derivatization) with other materials and/or (b) imparting desirable
properties, not otherwise possessed by the polymers alone, absent
such chemical modification.
[0114] More specifically, the functional group(s) can be
incorporated into the backbone of the polymer or as pendant groups
from the polymer backbone. The functional group(s) typically will
be polar and contain hetero atoms, such as P, O, S, N, halogen,
and/or boron. They can be attached to the saturated hydrocarbon
part of the polymers via substitution reactions or to an olefinic
portion via addition or cycloaddition reactions. Alternatively, the
functional group(s) can be incorporated into the polymer by
oxidation or cleavage of a small portion of the end of the polymer
(e.g., as in ozonolysis).
[0115] Functionalization of the polymer backbone with substituent
functional groups typically relies on an ethylenic unsaturation,
preferably a terminal ethylenic unsaturation, present in the
polymer for reaction with a compound containing or constituting the
functional group. Thus, reaction of these functional compounds and
the polymer can occur through a variety of mechanisms. Useful and
preferred functional groups include halogen, carboxyl materials
present as acids, esters, salts, or anhydrides, alcohols, amines,
ketones, aldehydes, and the like.
[0116] Useful functionalization reactions include, but are not
limited to: maleation, i.e., the reaction of the polymer at the
point of unsaturation with maleic acid or anhydride; halogenation
of the polymer at the olefinic bond and subsequent reaction of the
halogenated polymer with an ethylenically unsaturated functional
compound; reaction of the polymer with an unsaturated functional
compound by the "ene" reaction absent halogenation; reaction of the
polymer with at least one phenol group, which permits
derivatization in a Mannich Base-type condensation; reaction of the
polymer at its point of unsaturation with carbon monoxide using a
Koch-type reaction wherein an acid group, such as an iso acid or
neo acid is formed; reaction of the polymer with the functional
compound by free radical addition using a free radical catalyst;
and reaction of the polymer by air oxidation methods, epoxidation,
chloroamination, or ozonolysis.
[0117] The following are illustrative:
[0118] 1. Reaction products of functionalized polymer derivatized
with nucleophilic reagents, such as amine compounds, e.g.
nitrogen-containing compounds; organic hydroxy-group-containing
compounds, such as phenols and alcohols; and/or basic inorganic
materials.
[0119] More specifically, nitrogen- or ester-containing ashless
dispersants comprise oil-soluble salts, amides, imides, oxazolines,
and esters, or mixtures thereof, of the polymer employed in the
practice of the present invention, functionalized with mono- and
dicarboxylic acids or anhydride or ester derivatives thereof, said
polymer having dispersant range molecular weights as defined
hereinabove.
[0120] At least one functionalized polymer is mixed with at least
one of amine, alcohol, including polyol, aminoalcohol, and the
like, to form the dispersant additives. One class of particularly
preferred dispersants includes those derived from a polymer and
functionalized mono- or dicarboxylic acid material, e.g., succinic
anhydride, and reacted with (i) a hydroxy compound, e.g.,
pentaerythritol, (ii) a polyoxyalkylene polyamine, e.g.,
polyoxypropylene diamine, and/or (iii) a polyalkylene polyamine,
e.g., polyethylene diamine or tetraethylene pentamine, referred to
herein as TEPA. Another preferred dispersant class includes those
derived from functionalized polymer reacted with (i) a polyalkylene
polyamine, e.g., tetraethylene pentamine, and/or (ii) a polyhydric
alcohol or polyhydroxy-substituted aliphatic primary amine, e.g.,
pentaerythritol or trismethylolaminomethane.
[0121] 2. Reaction products of a hydrocarbon polymer functionalized
with an aromatic hydroxy group and derivatized with aldehydes
(especially formaldehyde) and amines (especially polyalkylene
polyamines) through the Mannich reaction, which may be
characterized as "Mannich dispersants".
[0122] 3. Reaction products of a hydrocarbon polymer that have been
functionalized by reaction with halogen and then derivatized by
reaction with amines (e.g., direct amination), preferably,
polyalkylene polyamines. These may be characterized as "amine
dispersants" and examples thereof are described, for example, in
U.S. Pat. Nos. 3,275,554; 3,438,757; 3,454,555; 3,565,804;
3,755,433; 3,822,209 and 5,084,197, the disclosures of which are
herein incorporated by reference in their entirety.
Derivatized Polymer from Amine Compounds
[0123] Useful amine compounds for derivatizing functionalized
hydrocarbon polymers comprise at least one amine and, optionally,
can comprise other reactive or polar groups. Where the functional
group is a carboxylic acid, ester, or derivative thereof, it reacts
with the amine to form an amide. Where the functional group is an
epoxy, it reacts with the amine to form an amino alcohol. Where the
functional group is a halide, the amine reacts to displace the
halide. Where the functional group is a carbonyl group, it reacts
with the amine to form an imine.
[0124] Amine compounds useful as nucleophilic reactants for
reaction with the functionalized hydrocarbon polymer include those
disclosed in U.S. Pat. Nos. 3,445,441; 5,017,299; and 5,102,566,
all hereby incorporated herein by reference in their entirety.
Preferred amine compounds include mono- and (preferably)
polyamines, of about 2 to about 60, preferably about 2 to about 40,
more preferably about 3 to about 20 total carbon atoms, and about 1
to about 12, preferably about 3 to about 12, and more preferably
about 3 to about 9 nitrogen atoms in the molecule. These amines can
be hydrocarbyl amines or can be hydrocarbyl amines that include
other groups, e.g., hydroxy groups, alkoxy groups, amide groups,
nitriles, imidazoline groups, and the like. Hydroxy amines having 1
to about 6 hydroxy groups, preferably 1 to about 3 hydroxy groups,
are particularly useful. Preferred amines are aliphatic saturated
amines, including those of the general formulae: 9
[0125] and 10
[0126] wherein R.sup.10, R.sup.11, R.sup.12, and R.sup.13 are
independently selected from the group consisting of hydrogen,
C.sub.1 to C.sub.25 straight or branched chain alkyl radicals,
C.sub.1 to C.sub.12 alkoxy, C.sub.2 to C.sub.6 alkylene radicals,
C.sub.2 to C.sub.12 hydroxy amino alkylene radicals, and C.sub.1 to
C.sub.12 alkylamino C.sub.2 to C.sub.6 alkylene radicals, and
wherein R.sup.13 can additionally comprise a moiety of the formula:
11
[0127] wherein R.sup.10 is as defined above, and wherein r, r', and
r" can be the same or a different integer of from 2 to 6,
preferably 2 to 4; and t and t' can be the same or different
integers of from 0 to 10, preferably 2 to 7, and more preferably
about 3 to 7. Preferably, the sum of t and t' is not greater than
15. To assure a facile reaction, it is preferred that R.sup.10,
R.sup.11, R.sup.12, R.sup.13, r, r', r", t, and t' be selected in a
manner sufficient to provide the compounds of Formulae (I) and (II)
with typically at least 1 primary or secondary amine group,
preferably at least 2 primary or secondary amine groups. The most
preferred amines of the above formulas are represented by Formula
(II) and contain at least 2 primary amine groups and at least 1,
and preferably at least 3, secondary amine groups.
[0128] Non-limiting examples of suitable amine compounds include:
1,2-diaminoethane; 1,3-diaminopropane; 1,4-diaminobutane;
1,6-diaminohexane; polyethylene amines, such as diethylene
triamine, triethylene tetramine, tetraethylene pentamine;
polypropylene amines, such as 1,2-propylene diamine,
di-(1,2-propylene)triamine, di-(1,3-propylene)triamine;
N,N-dimethyl-1,3-diaminopropane; N,N-di-(2-aminoethyl) ethylene
diamine; N,N-di-(2-hydroxyethyl)-1,3-propy- lene diamine;
3-dodecyloxypropylamine; N-dodecyl-1,3-propane diamine; tris
hydroxymethylaminomethane (THAM); diisopropanol amine; diethanol
amine; triethanol amine; mono-, di-, and tri-tallow amines; amino
morpholines, such as N-(3-aminopropyl)morpholine; and mixtures
thereof. Monoamines include methyl ethyl amine, methyl octadecyl
amines, anilines, diethylol amine, dipropyl amine, and the
like.
[0129] Other useful amine compounds include: alicyclic diamines
such as 1,4-di(aminomethyl) cyclohexane, and heterocyclic nitrogen
compounds, such as imidazolines, and N-aminoalkyl piperazines of
the general formula (III): 12
[0130] wherein p and q are the same or different and are each
integers of from 1 to 4, and x, y, and z are the same or different
and are each integers of from 1 to 3. Non-limiting examples of such
amines include 2-pentadecyl imidazoline; N-(2-aminoethyl)
piperazine; and the like.
[0131] Commercial mixtures of amine compounds can advantageously be
used. For example, one process for preparing alkylene amines
involves the reaction of an alkylene dihalide (such as ethylene
dichloride or propylene dichloride) with ammonia, which results in
a complex mixture of alkylene amines wherein pairs of nitrogens are
joined by alkylene groups, forming such compounds as diethylene
triamine, triethylenetetramine, tetraethylene pentamine, and
isomeric piperazines. Low cost poly(ethyleneamine) compounds
averaging about 5 to 7 nitrogen atoms per molecule are available
commercially under designations such as "Polyamine H", "Polyamine
400", "Dow Polyamine E-100", etc.
[0132] Useful amines also include polyoxyalkylene polyamines, such
as those of the formula:
NH.sub.2-alkylene-(--O-alkylene-).sub.m--NH.sub.2 (IV)
[0133] where m has a value of about 3 to 70, preferably 10 to 35;
and the formula:
R.sup.14-(-alkylene-(--O-alkylene-).sub.n--NH.sub.2).sub.a (V)
[0134] where n has a value of about 1 to 40 with the provision that
the sum of all the n values is from about 3 to about 70 and
preferably from about 6 to about 35, and R.sup.14 is a polyvalent
saturated hydrocarbon radical of up to 10 carbon atoms wherein the
number of substituents on the R.sup.14 group is represented by the
value of "a", which is an integer of from 3 to 6. The alkylene
groups in either formula (IV) or (V) can be straight or branched
chains containing about 2 to about 7, and preferably about about 2
to about 4 carbon atoms.
[0135] The polyoxyalkylene polyamines of formulas (IV) or (V)
above, preferably polyoxyalkylene diamines and polyoxyalkylene
triamines, can have number average molecular weights ranging from
about 200 to about 4,000 and preferably from about 400 to about
2,000. The preferred polyoxyalkylene polyamines include the
polyoxyethylene and polyoxypropylene diamines and the
polyoxypropylene triamines having average molecular weights ranging
from about 200 to 2,000. The polyoxyalkylene polyamines are
commercially available and can be obtained, for example, from the
Huntsman Chemical Company, Inc. under the trade designations
"Jeffamines D-230, D-400, D-1000, D-2000, T-403, etc. Other
suitable amines include bis(paraamino cyclohexyl) methane
oligomers.
Thiuram Disulfides and Thiocarbamate Salts
[0136] The thiocarbamate salts useful in the practice of the
present invention are characterized in that the alkali metal
dialkyldithiocarbamate represents a compound of the formula 13
[0137] wherein R.sup.8 and R.sup.9 are independently selected from
the group consisting of (C.sub.1-C.sub.24)alkyl and M is Na.sup.+,
K.sup.+, or NH.sub.4.sup.+.
[0138] Also useful are the divalent metal
bis-dialkyldithiocarbamates of the formula 14
[0139] wherein R.sup.8 and R.sup.9 are selected from the group
consisting of (C.sub.1-C.sub.24)alkyl and M.sup.+2 is Fe.sup.+2,
Zn.sup.+2, Pb.sup.+2, or Cu.sup.+2.
[0140] Also useful are the trivalent metal
tris-dialkyldithiocarbamates of the formula 15
[0141] wherein R.sup.8 and R.sup.9 are selected from the group
consisting of (C.sub.1-C.sub.24)alkyl and M.sup.3 is Sb.sup.+3 or
Bi.sup.+3.
[0142] Thiuram disulfides useful for this invention are of the
formula: 16
[0143] wherein R.sup.8 and R.sup.9 are as described above.
[0144] Examples of thiuram disulfides and their synthesis useful
for this invention are disclosed in U.S. Pat. No. 4,501,678, the
disclosure of which is herein incorporated by reference in its
entirety. Examples of thiocarbamate salts and their synthesis
useful for this invention are disclosed in U.S. Pat. Nos.
3,674,824; 3,678,135, the disclosures of which are herein
incorporated by reference in their entirety.
General Synthesis of Additives
[0145] The process for making the molybdenum based friction
modifiers of the present invention is unique in its simplicity and
appearance. This process includes the steps of:
[0146] i) creating a micelle solution of a suitable surfactant in
an organic solvent or solvent mixture,
[0147] ii) creating a reverse microemulsion by addition of an
aqueous solution of an appropriate water-soluble inorganic
molybdenum compound to the micelle solution,
[0148] iii) adding an appropriate surface-capping reagent capable
of adsorbing on or reacting with molybdenum sulfide,
[0149] iv) reacting the molybdenum compound in the aqueous
microemulsion core with hydrogen sulfide to form a thiomolybdenum
derivative,
[0150] v) removing water and organic solvents from the reaction
mixture,
[0151] vi) extracting molybdenum/sulfur moiety-containing nanosized
particles thus formed with an appropriate solvent, and
[0152] vii) evaporating the appropriate organic solvent to yield
the additive in the form of surface-capped nanosized particles.
Creating a Reverse Micelle Solution and Reverse Microemulsion
[0153] Generally, the reverse micellar solutions formed by any
surfactant type (cationic, anionic, or nonionic) can form a reverse
microemulsion on addition of an aqueous solution of any inorganic
salt. The reverse micellar solutions stabilized by various types of
surfactants as well as the reverse microemulsion made from said
micellar solutions within the scope of the present invention are
presented in Table 1. The surfactants useful in this invention
include:
[0154] i) cationic type: tetraalkylammonium halides, such as
cetyltrimethylammonium bromide (CTAB); tricaprylmethylammonium
chloride (Aliquate.RTM. 336, AL-336);
methyltriaklyl(C.sub.8-C.sub.10)ammonium chloride (Adogen.RTM. 464,
AD-464);
[0155] ii) anionic type: sodium bis(2-ethylhexyl)sulfosuccinate
(AOT);
[0156] iii) nonionic type: Triton.RTM. X-100 (TX-100); Triton.RTM.
X-100 reduced (TX-100R).
1TABLE 1 Surfactant Organic No. of (concentration, solvent/solvent
Amount of added solution mol/L) mixture, mL aqueous salt solution
Result 1 CTAB (0.01) Chloroform-hexane 15 .mu.l of 30 wt. % Clear
solution (1:1 v/v), 10 (NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 2
CTAB (0.001) Chloroform- 5 .mu.l of 40 wt. % Clear solution
isooctane (1:1 v/v), (NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 10
3 CTAB (0.1) Chloroform- 35 .mu.l of 40 wt. % Clear solution
isooctane (1:1 v/v), (NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 10
4 AL-336 (0.25) Benzene, 5 4 .mu.l of 5 wt. % Clear solution
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 5 AL-336 (0.25)
Chloroform, 5 2 .mu.l of 5 wt. % Clear solution
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 6 AL-336 (0.055)
Benzene, 5 5 .mu.l of 10 wt. % Clear solution
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 7 AD-464 (0.11) Benzene,
5 6 .mu.l of 10 wt. % Clear solution
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 8 AD-464 (0.11)
Chloroform, 5 4 .mu.l of 10 wt. % Clear solution
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 9 AOT (0.21) Chloroform,
5 20 .mu.l of 2 wt. % Clear solution
(NH.sub.4).sub.6Mo.sub.7O.sub.24.4H.sub.2O 10 AOT (0.19)
Chloroform-isooctane 10 .mu.l of 2 wt. % Clear solution (1:1 v/v),
5 Na.sub.2MoO.sub.4 11 AOT (0.15) Isooctane, 5 10 .mu.l of 2 wt. %
Clear solution Na.sub.2MoO.sub.4 12 TX-100 (0.10) Benzene, 5 2
.mu.l of 10 wt. % Clear solution Na.sub.2MoO.sub.4 13 TX-100 (0.10)
Benzene-hexane 2 .mu.l of 2 wt. % Clear solution (1:3 v/v), 5
Na.sub.2MoO.sub.4 14 TX-100R (0.10) Cyclohexane, 5 3 .mu.l of 5 wt.
% Clear solution Na.sub.2MoO.sub.4 15 TX-100R (0.10) Benzene-hexane
2 .mu.l of 1 wt. % Clear solution (1:3 v/v), 5
Na.sub.2MoO.sub.4
[0157] Preferably, CTAB is employed dissolved in
chloroform:n-alkane in a concentration of about 0.01 to about 0.1
mol/L. The n-alkanes that can be used include, but are not limited
to, pentane, hexane, heptane, octane, and isomers and mixtures
thereof.
Reacting a Molybdenum Compound in the Microemulsion Aqueous Core
with Hydrogen Sulfide
[0158] The reverse microemulsions containing molybdate salt
solutions that do not include a sulfur atom are reacted with
hydrogen sulfide (H.sub.2S) by bubbling gaseous hydrogen sulfide
directly into the microemulsion. The reaction proceeds similarly to
that in aqueous solution, i.e., by stepwise substitution for oxygen
atoms in molybdate anion. Depending on pH value, either
thiomolybdate anions at pH 7 or higher (step-by-step substitution)
that are soluble in water or MoS.sub.3 sediment at pH lower than 7
are formed. Interaction of the molybdate-containing microemulsions
was monitored by UV spectra in order to clarify the influence of
reaction conditions on its result. Typically, [MoS.sub.4].sup.2-
anions have absorption bands at 241 nm, 316 nm, and 467 nm;
[MoO.sub.2S.sub.3].sup.2-- --at 308 nm, 396 nm and 457 nm;
[MoO.sub.2S.sub.2].sup.2---at 320 nm and 393 nm, respectively, in
water.
[0159] UV spectra presented in FIGS. 1-3 are illustrative of
formation of a partially substituted thiomolybdate derivative. The
final spectrum in FIG. 4 contains no absorption bands and is
typical of UV spectra of nanosized inorganic particles formed in
the interior of the reverse micelles.
[0160] Depending on the pH value of the aqueous solution, the
reaction of the molybdenum (VI) compound with hydrogen sulfide may
proceed either to form thiomolybdate salt derivatives, as supported
by spectra presented at FIGS. 1-3 (pH.gtoreq.5), or to form
MoOS.sub.2 or MoS.sub.3 sediments directly within the microemulsion
aqueous core at pH<5. Adjustment of the pH value of the solution
is achieved by addition of a desired amount of hydrochloric acid
directly to the microemulsion containing molybdenum derivatives
solution and before reaction with hydrogen sulfide.
Adding an Appropriate Surface Capping Agent to Molybdenum Sulfide
Nanoparticles
[0161] Nanosize particles of inorganic material often possess
limited flocculation and/or sedimentation stability in an organic
medium. Utilization of a surface-capping agent to improve the
flocculation stability is known in the art; however, none of the
surface-capped nanosize inorganic particles may be dissolved in a
non-polar organic medium.
[0162] Molybdenum sulfides readily form complex compounds with a
number of compounds, such as organic amines, carboxylic acids,
dialkyldithiophosphoric acid derivatives, and dialkyldithiocarbamic
acid derivatives. The present invention is directed to the
utilization of these groups of compounds for the surface-capping of
molybdenum sulfide nanoparticles in order to enhance their
flocculation stability and to solubilize them in non-polar organic
solvents, such as hydrocarbons and petroleum-originated lubricating
oils.
[0163] Surface-capping of molybdenum/sulfur moiety-containing
nanoparticles, according to the present invention, can be performed
by the addition of a desired amount of the surface-capping agent
either before formation of a reverse microemulsion, after the
formation of a reverse microemulsion, or even after the reaction of
the molybdenum derivative in the aqueous core of the microemulsion
with hydrogen sulfide. Addition of the surface-capping agents does
not affect the course of the chemical reaction in the interior of
the reverse microemulsion, and the resulting spectra for nanosize
molybdenum sulfide particles are practically the same as those
obtained in the absence of any surface capping agents, e.g., see
the UV spectrum of molybdenum sulfide nanoparticles prepared in the
presence of isopropyloctadecyl amine, presented in FIG. 5.
Removing Water and Organic Solvents from the Reaction Mixture, and
Extracting the Molybdenum Sulfide Nanosized Particles
[0164] The solution obtained in the previous step, which is clear
brown, contains surface-capped molybdenum sulfide nanoparticles,
surfactant, water, and organic solvent and/or solvent mixture.
Water and organic solvents and/or solvent mixtures are readily
removed by evaporation and vacuum drying of the residue, while
isolation of the surface-capped molybdenum sulfide nanoparticles is
achieved by selective extraction with an appropriate solvent. For
example, in the case of cationic surfactants, the suitable solvent
is tetrahydrofuran (THF), which does not dissolve any significant
amount of tetraalkylammonium halide surfactant, but extracts the
final surface-capped molybdenum sulfide nanosize particles.
Evaporation of THF yields the desired compounds of this
invention.
[0165] Final additives of this invention are usually prepared by
dissolving the synthesized surface-capped molybdenum sulfide
nanosize particles in the corresponding surface-capping agent of
this invention so as to form an additive concentrate suitable for
blending with a lubricant oil of any type: petroleum-based or
synthetic comprising synthetic hydrocarbons, diesters, polyol
esters, alkylaromatic compounds, silicone-based oils, polyphenyl
ether, fluorinated hydrocarbons, and the like.
Use with Other Additives
[0166] The additive of this invention can be used in combination
with other additives typically found in lubricating compositions,
as well as with other friction modifier additives. The typical
additives found in lubricating oils are dispersants, detergents,
rust inhibitors, antioxidants, anti-wear agents, anti-foamants,
friction modifiers, seal swell agents, demulsifiers, VI improvers,
and pour point depressants. See, e.g. U.S. Pat. No. 5,498,809 for a
description of useful lubricating oil composition additives.
Examples of dispersants include polyisobutylene succinimides,
polyisobutylene succinate esters, Mannich Base ashless dispersants,
and the like. Examples of detergents include metallic phenates,
metallic sulfonates, metallic salicylates, and the like. Examples
of antioxidant additives that can be used in combination with the
additives of the present invention include alkylated
diphenylamines, N-alkylated phenylenediamines, hindered phenolics,
alkylated hydroquinones, hydroxylated thiodiphenyl ethers,
alkylidenebisphenols, oil soluble copper compounds, and the like.
Examples of anti-wear additives that can be used in combination
with the additives of the present invention include organo borates,
organo phosphites, organic sulfur-containing compounds, zinc
dialkyl dithiophosphates, zinc diaryl dithiophosphates,
phosphosulfurized hydrocarbon, and the like. Examples of friction
modifiers that can be used in combination with the friction
modifiers of the present invention include fatty acid esters and
amides, organo molybdenum compounds, molybdenum
dialkylthiocarbamates, molybdenum dialkyl dithiophosphates, and the
like. An example of an antifoamant is polysiloxane, and the like.
Exemplary of rust inhibitors are the polyoxyalkylene polyols, and
the like. Examples of VI improvers include olefin copolymers and
dispersant olefin copolymers, and the like. An example of a pour
point depressant is polymethacrylate, and the like.
Lubricant Compositions
[0167] Compositions, when containing these additives, typically are
blended into the base oil in amounts that are effective to provide
their normal attendant function.
2 Compositions Broad Weight % Preferred Weight % V.I. Improver 1-12
1-4 Corrosion Inhibitor 0.01-3 0.01-1.5 Oxidation Inhibitor 0.01-5
0.01-1.5 Dispersant 0.1-10 0.1-5 Lube Oil Flow Improver 0.01-2
0.01-1.5 Detergents/Rust Inhibitors 0.01-6 0.01-3 Pour Point
Depressant 0.01-1.5 0.01-0.5 Antifoaming Agents 0.001-0.1
0.001-0.01 Antiwear Agents 0.001-5 0.001-1.5 Seal Swellant 0.1-8
0.1-4 Friction Modifiers 0.01-3 0.01-1.5 Lubricating Base Oil
Balance Balance
[0168] The additives of the present invention would be substituted
for a portion of the friction modifier, and/or the oxidation
inhibitor, and/or the anti-wear agent.
[0169] When other additives are employed, it may be desirable,
although not necessary, to prepare additive concentrates comprising
concentrated solutions or dispersions of the subject additives of
this invention (in concentrate amounts hereinabove described),
together with one or more of said other additives (said concentrate
when constituting an additive mixture being referred to herein as
an additive-package) whereby several additives can be added
simultaneously to the base oil to form the lubricating oil
composition. Dissolution of the additive concentrate into the
lubricating oil may be facilitated by solvents and by mixing
accompanied by mild heating, but this is not essential. The
concentrate or additive-package will typically be formulated to
contain the additives in proper amounts to provide the desired
concentration in the final formulation when the additive-package is
combined with a predetermined amount of base lubricant. Thus, the
subject additives of the present invention can be added to small
amounts of base oil or other compatible solvents along with other
desirable additives to form additive-packages containing active
ingredients in collective amounts of typically from about 2.5 to
about 90%, and preferably from about 15 to about 75%, and more
preferably from about 25 to about 60% by weight additives in the
appropriate proportions with the remainder being base oil. The
final formulations may employ typically about 1-20 wt. % of the
additive-package with the remainder being base oil.
[0170] All of the weight percentages expressed herein (unless
otherwise indicated) are based on active ingredient (AI) content of
the additive, and/or upon the total weight of any additive-package
or formulation that will be the sum of the (AI) weight of each
additive plus the weight of total oil or diluent.
[0171] In general, the lubricant compositions of the present
invention contain the additives in a concentration ranging from
about 0.05 to about 30 weight percent. A concentration range for
the additives ranging from about 0.1 to about 10 weight percent
based on the total weight of the oil composition is preferred. A
more preferred concentration range is from about 0.2 to about 5
weight percent. Oil concentrates of the additives can contain from
about 1 to about 75 weight percent of the additive reaction product
in a carrier or diluent oil of lubricating oil viscosity.
[0172] In general, the additives of the present invention are
useful in a variety of lubricating oil basestocks. The lubricating
oil basestock is any natural or synthetic lubricating base oil
stock fraction having a kinematic viscosity at 100.degree. C. of
about 2 to about 200 cSt, more preferably about 3 to about 150 cSt,
most preferably about 3 to about 100 cSt. The lubricating oil
basestock can be derived from natural lubricating oils, synthetic
lubricating oils, or mixtures thereof. Suitable lubricating oil
basestocks include basestocks obtained by isomerization of
synthetic wax and wax, as well as hydrocrackate basestocks produced
by hydrocracking (rather than solvent extracting) the aromatic and
polar components of the crude. Natural lubricating oils include
animal oils, vegetable oils (e.g., rapeseed oils, castor oils and
lard oil), petroleum oils, mineral oils, and oils derived from coal
or shale.
[0173] Synthetic oils include hydrocarbon oils arid
halo-substituted hydrocarbon oils, such as polymerized and
interpolymerized olefins, alkylbenzenes, polyphenyls, alkylated
diphenyl ethers, alkylated diphenyl ethers, aklylated diphenyl
sulfides, as well as their derivatives, analogs and homologs
thereof, and the like. Synthetic lubricating oils also include
alkylene oxide polymers, interpolymers, copolymers, and derivatives
thereof, wherein the terminal hydroxyl groups have been modified by
esterification, etherification, etc. Another suitable class of
synthetic lubricating oils comprises the esters of dicarboxylic
acids with a variety of alcohols. Esters useful as synthetic oils
also include those made from C.sub.5 to C.sub.12 monocarboxylic
acids and polyols and polyol ethers.
[0174] Silicon-based oils (such as the polyalkyl-, polyaryl-,
polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils)
comprise another useful class of synthetic lubricating oils. Other
synthetic lubricating oils include liquid esters of
phosphorus-containing acids, polymeric tetrahydrofurans,
polyalphaolefins, and the like.
[0175] The lubricating oil may be derived from unrefined, refined,
re-refined oils, or mixtures thereof. Unrefined oils are obtained
directly from a natural source or synthetic source (e.g., coal,
shale, or tar and bitumen) without further purification or
treatment. Examples of unrefined oils include a shale oil obtained
directly from a retorting operation, a petroleum oil obtained
directly from distillation, or an ester oil obtained directly from
an esterification process, each of which is then used without
further treatment. Refined oils are similar to the unrefined oils
except that refined oils have been treated in one or more
purification steps to improve one or more properties. Suitable
purification techniques include distillation, hydrotreating,
dewaxing, solvent extraction, acid or base extraction, filtration,
and percolation, all of which are known to those skilled in the
art. Re-refined oils are obtained by treating refined oils in
processes similar to those used to obtain the refined oils. These
re-refined oils are also known as reclaimed or reprocessed oils and
often are additionally processed by techniques for removal of spent
additives and oil breakdown products.
[0176] Lubricating oil base stocks derived from the
hydroisomerization of wax can also be used, either alone or in
combination with the aforesaid natural and/or synthetic base
stocks. Such wax isomerate oil is produced by the
hydroisomerization of natural or synthetic waxes or mixtures
thereof over a hydroisomerization catalyst. Natural waxes are
typically the slack waxes recovered by the solvent dewaxing of
mineral oils; synthetic waxes are typically the wax produced by the
Fischer-Tropsch process. The resulting isomerate product is
typically subjected to solvent dewaxing and fractionation to
recover various fractions of specific viscosity range. Wax
isomerate is also characterized by possessing very high viscosity
indices, generally having a VI of at least 130, preferably at least
135 and higher and, following dewaxing, a pour point of about
-20.degree. C. and lower.
[0177] The additives of the present invention are especially useful
as components in many different lubricating oil compositions. The
additives can be included in a variety of oils with lubricating
viscosity including natural and synthetic lubricating oils and
mixtures thereof. The additives can be included in crankcase
lubricating oils for spark-ignited and compression-ignited internal
combustion engines. The compositions can also be used in gas engine
lubricants, turbine lubricants, automatic transmission fluids, gear
lubricants, compressor lubricants, metal-working lubricants,
hydraulic fluids, and other lubricating oil and grease
compositions. The additives can also be used in motor fuel (both
gasoline and diesel) compositions.
[0178] The advantages and the important features of the present
invention will be more apparent from the following examples.
EXAMPLES
Preparation of Surface-Capped Molybdenum Sulfide Nanoparticles
Using Various Surface-Capping Agents
Organic Amine Modification
Example 1
Isopropyloctadecylamine (IPODA)
[0179] Cetyltrimethylammonium bromide (0.652 g) was dissolved in 45
mL of chloroform and 100 .mu.L of a saturated aqueous solution of
(NH.sub.4).sub.6Mo.sub.7O.sub.24.2H.sub.2O was added with stirring.
The opaque solution was heated, then 20 mL of isooctane and 20 mL
of chloroform were added, and 10 drops of concentrated aqueous HCl
solution, resulting in a clear solution. Excess H.sub.2S was
bubbled in until a weak yellow color was obtained, then 11 mL of a
solution obtained by dissolving 0.577 g of isopropyloctadecylamine
in 50 mL of chloroform (Mo:N.about.1:5) was added. Three days
later, all solvents were evaporated from the resulting dark
solution containing small sediment, the residue was stirred with 30
mL tetrahydrofuran (THF), undissolved cetyltrimethylammonium
bromide (CTAB) containing some MoS.sub.3 was filtered off, and the
resulted dark clear solution was evaporated.
Example 2
sec.-Butylamine
[0180] CTAB (0.757 g) was dissolved in 100 mL of chloroform and
diluted with 100 mL of hexane. One hundred mL of saturated aqueous
solution of (N.sub.4).sub.6Mo.sub.7O.sub.24.2H.sub.2O was added
with stirring, followed by 12 .mu.L of concentrated aqueous HCl
solution, which resulted in a clear solution. H.sub.2S was bubbled
in over a one hour period until the color became gray-brown, then
30 .mu.L of sec.-butylamine was added, whereupon the solution
became a deep brown. Twenty-four hours later, all the solvents were
evaporated from the dark solution, the residue was stirred with 15
mL of tetrahydrofuran (THF), undissolved CTAB containing some
MoS.sub.3 was filtered off, and the resulting dark clear solution
was evaporated to yield 0.1279 g of a dark substance.
Example 3
Alkenyl Succinimide
[0181] Alkenyl succinimide (ASI, 1.7 mL) (the reaction product of
Indapol H-1500 (polyisobutylene) with maleic anhydride, which is
then reacted with triethylenetetraamine (TETA), (Uniroyal Chemical
Company) solution (0.2185 g ASI in 5 mL chloroform) was dissolved
in 100 mL of a 0.01M solution of CTAB in chloroform-hexane solution
(1:1 v/v) with stirring. After 10 minutes, 0.05 mL of a saturated
aqueous solution of (NH.sub.4).sub.6Mo.sub.7O.sub.24 was added to
produce an opaque microemulsion (ASI:Mo=1.6:1.1 by moles). Addition
of approximately 8.5 .mu.L of concentrated aqueous HCl resulted in
a clear solution, into which excess H.sub.2S was bubbled. The color
of the solution changed from green to brown and, after 24 hours, a
brown precipitate formed. Organic solvents were evaporated under
vacuum, the residue was stirred with 15 mL of freshly distilled
THF, the undissolved matter was filtered off, and the THF was
evaporated. The resulting residual brown substance (0.0523 g) was
nanosized molybdenum sulfide particles modified with ASI in a
modifier to Mo ratio of approximately 1:1.
Example 4
Alkenyl Succinimide
[0182] Alkenyl succinimide solution (0.85 mL of 0.2185 g ASI in 5
mL chloroform) was dissolved in 100 mL 0.01M solution of CTAB in a
chloroform-hexane solution (1:1 v/v) with stirring. After 10
minutes, 0.05 mL of a saturated aqueous solution of
(NH.sub.4).sub.6Mo.sub.7O.sub.- 24 was added to produce an opaque
microemulsion (ASI:Mo=0.56:1.1 by moles). Addition of approximately
7 .mu.L of concentrated aqueous HCl resulted in a clear solution,
into which excess H.sub.2S was bubbled. The solution turned opaque
and its color changed from greenish to brown. After 24 hours the
solution was still opaque and brown and no precipitate had formed.
The organic solvents were evaporated under vacuum, the residue was
stirred with 15 mL of freshly distilled THF, the undissolved matter
was filtered off, and the THF was evaporated. The residual brown
substance (0.04 g) was nanosized molybdenum sulfide particles
modified with ASI in a modifier to Mo ratio of approximately
1:2.
Example 5
Alkenyl Succinimide
[0183] A saturated aqueous solution of
(NH.sub.4).sub.6Mo.sub.7O.sub.24 (0.05 mL) was added to 100 mL
0.01M CTAB solution in a chloroform-hexane mixture (1:1 v/v). After
5 minutes, 1.7 mL of alkenyl succinimide solution (0.2185 g of ASI
in 5 mL chloroform) was added to produce a colorless opaque
microemulsion (ASI:Mo=1.6:1.1 by moles). The addition of
approximately 6 .mu.L of concentrated aqueous HCl resulted in a
clear solution, into which excess H.sub.2S was bubbled. The
solution slowly turned brown. After 24 hours, the organic solvents
were evaporated under vacuum, the residue was stirred with 15 mL of
freshly distilled THF, the undissolved matter was filtered off, and
the THF was evaporated. The residual brown substance (0.094 g) was
nanosized molybdenum sulfide particles modified with ASI in a
modifier to Mo ratio of approximately 1:1.
Example 6
Alkenyl Succinimide
[0184] Example 5 was repeated except that the ASI solution was
added to the CTAB solution first, and then the saturated aqueous
solution of (NH.sub.4).sub.6Mo.sub.7O.sub.24 was added. Hydrogen
sulfide was bubbled in over a period of approximately 2.5 hours.
Product isolation resulted in 0.1052 g of nanosized molybdenum
sulfide particles modified with ASI in a modifier to Mo ratio of
approximately 1:1.
Carboxylic Acid Modification
Example 7
Docosanoic (behenic) Acid; C.sub.22 Carboxylic Acid
[0185] Seven .mu.L of saturated aqueous ammonium molybdate solution
was added with stirring to 7 mL of 0.01 mol/L CTAB solution in a
1:1 v/v isooctane-chloroform mixture, then the mixture was
stabilized by addition of concentrated aqueous HCl (1 drop). After
30 minutes, H.sub.2S was bubbled into the slightly blue solution
turning it yellow, and 0.19 mL of a solution containing 0.0282 g
behenic acid in 5 mL of chloroform was added. Excess H.sub.2S was
further bubbled in. After 24 hours, a light brown sediment formed
The residue, after removing all solvents, dissolved in chloroform
and benzene (except for CTAB, in the latter case).
Example 8
Docosanoic (behenic) Acid
[0186] Two mL of behenic acid solution (0.2165 g of behenic acid in
10 mL of chloroform) was dissolved in 100 mL of 0.01M solution of
CTAB in chloroform-hexane solution (1:1 v/v) with stirring. After
10 minutes, 0.05 mL of a saturated aqueous solution of
(NH.sub.4).sub.6Mo.sub.7O.sub.- 24 was added, producing an opaque
microemulsion (C.sub.22 acid:Mo=1:1.3 by moles). Addition of
approximately 5.5 .mu.L of concentrated aqueous HCl resulted in a
clear solution, into which excess H.sub.2S was bubbled for 2.5
hours. The color of the solution changed from green to brown. After
24 hours, the organic solvents were evaporated in vacuum, the
residue was stirred with 15 mL of freshly distilled THF, the
undissolved matter was filtered off, and the THF was evaporated. A
residual brown substance (0.037 g) resulted, representing nanosized
molybdenum sulfide particles modified with behenic acid in a
modifier to Mo ratio of approximately 1:1.3.
Dialkyldithiophosphoric Acid Derivatives Modification
Example 9
Di-2-ethylhexyl-dithiophosphoric Acid
[0187] Fifty mL of aqueous saturated ammonium molybdate solution
was added to 10 mL of 0.01 mol/L CTAB solution in
isooctane-chloroform in a 1:1 v/v mixture under reflux, followed by
75 .mu.L of concentrated aqueous HCl. Then 0.07 .mu.L of a solution
containing 0.1 g di-2-ethylhexyl-dithiophos- phoric acid in 2 mL
chloroform was added (10 molar % relative to Mo) and excess
H.sub.2S bubbled in. Twenty-four hours later, a sediment was formed
that was isolated by filtration. The dark-brown solid thus obtained
dissolves in chloroform, THF, and slightly in benzene, CCl.sub.4
and sec.-C.sub.4H.sub.9NH.sub.2.
Dialkyldithiocarbamic Acid Derivatives Modification
Example 10
Tetra(hexadecyl)thiuram Disulfide
[0188] Tetra(hexadecyl)thiuram disulfide (THDTS) solution (1.5 mL
of 0.204 g THDTS in 5 mL of chloroform) was dissolved in 100 mL of
a 0.01M solution of CTAB in chloroform-hexane solution (1:1 v/v)
with stirring. After 10 minutes, 0.05 mL of a saturated aqueous
solution of (NH.sub.4).sub.6Mo.sub.7O.sub.24 was added to produce
an opaque microemulsion (THDTS:Mo=1:1 by moles). Addition of
approximately 5 .mu.L of concentrated aqueous HCl resulted in a
clear solution, and excess H.sub.2S (about 300 mL) was bubbled in.
The solution's color changed from light-brown to dark green-brown.
After 24 hours, no visible precipitate had formed in the solution.
The organic solvents were evaporated under vacuum, the residue was
stirred with 15 mL of freshly distilled THF, the undissolved matter
was filtered off, and the THF was evaporated. The residual brown
substance (0.0673 g) was nanosized molybdenum sulfide particles
modified with THDTS in a modifier to Mo ratio of approximately 1:1.
The whole sample completely dissolves in 3 mL benzene.
Example 11
Sodium di(hexadecyl)dithiocarbamate
[0189] Sodium di(hexadecyl)dithiocarbamate (NaHDTC) solution (1.5
mL of 0.204 g NaHDTC in 5 mL chloroform) was dissolved in 100 mL of
a 0.01M solution of CTAB in chloroform-hexane solution (1:1 v/v)
with stirring. After 10 minutes, 0.05 mL of a saturated aqueous
solution of (NH.sub.4).sub.6Mo.sub.7O.sub.24 was added to produce a
light-yellow solution (NaEDTC: Mo=1:1 by moles). Addition of
approximately 2.5 .mu.L of concentrated aqueous HCl resulted in a
clear solution, and excess H.sub.2S (about 300 mL) was bubbled in.
The solution's color changed to yellow-brown. After 24 hours, no
visible precipitate had formed in the solution. The organic
solvents were evaporated under vacuum, the residue was stirred with
15 mL of freshly distilled THF, the undissolved matter was filtered
off, and the THF was evaporated. The residual brown substance
(0.043 g) was nanosized molybdenum sulfide particles modified with
NaHDTC in a modifier to Mo ratio of approximately 1:1. The whole
sample completely dissolves in 5 mL benzene.
Preparation of Additives and of Lubricant Compositions
Example 12
Lubricant Composition A
[0190] The sample obtained in Example 1 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 13
Lubricant Composition B
[0191] The sample obtained in Example 2 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 14
Lubricant Composition C
[0192] The sample obtained in Example 3 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 15
Lubricant Composition D
[0193] The sample obtained in Example 4 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 16
Lubricant Composition E
[0194] The sample obtained in Example 5 was dissolved in 0.07 g AST
on heating to about 60.degree. C. An additional 0.06 g ASI was
added to improve solubility, although some solid particulate
material remained, which was later filtered off. Then 1.6 mL of T46
oil was added. The solution was filtered to produce a dark-brown
composition containing less than about 10 wt. % of the additive
package.
Example 17
Lubricant Composition F
[0195] The sample obtained in Example 6 was dissolved in 0.132 g
ASI on heating to about 60.degree. C. and 4.486 mL of T46 oil was
added. The solution was filtered to produce a dark-brown
composition containing about 5 wt. % of the additive package.
Example 18
Lubricant Composition G
[0196] The sample obtained in Example 7 was dissolved in 0.16 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 19
Lubricant Composition H
[0197] The sample obtained in Example 7 was dissolved in 0.149 g
ASI on heating to about 60.degree. C., and 4.7 mL T46 oil was added
on heating to about 60.degree. C. Some solid particulate material
was later filtered off. The warm solution was clear, but cooling to
ambient temperature resulted in sediment formation. This sample was
not tested.
Example 20
Lubricant Composition I
[0198] The sample obtained in Example 8 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL T46 oil was added. The
solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 21
Lubricant Composition J
[0199] The sample obtained in Example 9 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 22
Lubricant Composition K
[0200] The sample obtained in Example 10 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
Example 23
Lubricant Composition L
[0201] The sample obtained in Example 11 was dissolved in 0.2 g ASI
on heating to about 60.degree. C., and 5 mL of T46 oil was added.
The solution was filtered to produce a dark-brown composition
containing about 5 wt. % of the additive package.
SRV Tribometer Determination of Friction Coefficient and
Antiscuffing Properties
[0202] Friction coefficient measurements were performed using SRV
vibration tribometer (Optimol Instruments GmbH, Germany) for the
ball-area pair (friction point) at 50 MHz, stepwise loading from 20
to 1000 N. Friction coefficient versus load value was measured, as
well as load-carrying ability of the lubricant tested. Better
results are assumed to be those demonstrating a lower value of
friction coefficient and a higher value of scuffing load.
[0203] Lubricant compositions containing the surface-capped
nanosized molybdenum sulfide particles were prepared on the basis
of Turbine Oil T46 and included different amounts of the
molybdenum-containing additives. Tribological properties of the
lubricant compositions of this invention are compared with those of
a composition containing 1 wt. % of molybdenum
oxosulfo-(diisooctyldithiocarbamate) complex (Composition M, see
Zaimovskaya T. A. et al. Izv. AN SSSR. Ser. Khim., No.5:2151
(1991).
3TABLE 2 Lowest Friction Coefficient Composition Scuffing Load, N
Value A 800 0.098 B 800 0.098 C 900 0.097 D 1000 0.097 E 800 0.098
F 700 0.100 G 900 0.099 H 900 0.098 I 1000 0.097 J 1000 0.097 K 800
0.099 L 900 0.097 M 700 0.100 (comparative)
Example 24
Alkenyl Succinimide
[0204] Cetyltrimethylammonium bromide (CTAB) (0.757 g, 0.02 mol)
was dissolved in 100 mL in CHCl.sub.3, stirred for a period of 15
minutes, and then the mixture was diluted with 100 mL hexane
(solution A). Alkenyl succinimide (0.2188 g) was dissolved in 2 mL
of CHCl.sub.3 (solution B). Freshly re-crystallized salt
(NH.sub.4).sub.6Mo.sub.7O.sub.24 was dissolved in distilled water
to give a saturated solution (room temperature, approx. 40% by
weight) (solution C). A quantity of 1.327 mL of solution B (approx.
2.2.times.10.sup.-4 mol) was added with stirring to solution A. Ten
minutes later, 100 .mu.L of solution C (approx. 2.8.times.10.sup.-5
mol of salt, 1.93.times.10.sup.-4 mol Mo) was added using a
microsyringe. Finally, 0.2 mL of hydrochloric acid (36% by weight,
2.times.10.sup.-3 mol) was added. The solution thus obtained was
clear and colorless. An excess of H.sub.2S was bubbled through the
resultant solution over a period of 2.5 hours. Sixteen hours later
(the next day) all volatile matter was removed under reduced
pressure and the solid residue was dried under reduced pressure
(0.1 mm Hg). Ten mL of freshly distilled tetrahydrofuran (THF) was
added to the residue and the mixture was filtered through a porous
glass filter (precipitate left on filter (CTAB) was white). The
resultant dark-brown solution was evaporated to dryness under
reduced pressure (temperature less than 60.degree. C.) and dried to
give 0.1505 g of a dark-brown substance. Alkenyl succinimide (0.301
g) was added to the residue and the entire mixture was heated to
60.degree. C. and thoroughly mixed manually using a glass rod. This
product was tested in the Cameron-Plint machine after being
formulated into an engine oil.
Example 25
Alkenyl Succinimide
[0205] Cetyltrimethylammonium bromide (CTAB) (1.1355 g, 0.03 mol)
was dissolved in 150 mL CHCl.sub.3, stirred for a period of 15
minutes and the mixture was diluted with 150 mL of hexane (solution
AA). Alkenyl succinimide (0.4370 g) was dissolved in 4 mL of
CHCl.sub.3 (solution BB). Freshly re-crystallized salt,
(NH.sub.4).sub.6Mo.sub.7O.sub.24, was dissolved in distilled water
to give a saturated solution (room temperature, approx. 40% by
weight) (solution C). A quantity of 1.99 mL of solution BB (approx.
3.times.10.sup.-4 mol) was added with stirring to solution AA and
150 .mu.L of solution C (approx. 4.2.times.10.sup.-5 mol of salt,
2.94.times.10.sup.-4 mol Mo) was added using a microsyringe.
Finally, 0.3 mL of hydrochloric acid (36% by weight,
3.times.10.sup.-3 mol) was added. The solution thus obtained was
clear and colorless. An excess of H.sub.2S was bubbled through the
resultant solution over a period of 5 hours, at the end of which,
the solution had become opaque. Sixteen hours later (the next day)
all volatile matter was removed under reduced pressure and the
solid residue was dried under reduced pressure (0.1 mm Hg). Fifteen
mL of freshly distilled tetrahydrofuran (THF) was added to the
residue and the mixture was filtered through a porous glass filter
(the precipitate left on the filter (CTAB) was brown). The
resultant dark-brown solution was evaporated to dryness under
reduced pressure (temperature less than 60.degree. C.) and dried to
give 0.2526 g of a dark-brown substance. Alkenyl succinimide (0.505
g) was added to the residue and the entire mixture was heated to
60.degree. C. and thoroughly mixed manually using a glass rod. This
product was tested in the Cameron-Plint machine after being
formulated into an engine oil.
Cameron-Plint TE77 High Frequency Friction Machine Friction
Coefficient Testing
[0206] The anti-friction properties of the oil solubilized
molybdenum nano-particles in a filly formulated lubricating oil
were determined in the Cameron Plint TE77 Friction Test. The fully
formulated lubricating oils tested contained 1.5 wt. % of the
additive. The additives were tested for effectiveness in a motor
oil at increasing temperature points and compared to an identical
formulation without the friction modifier. In Table 3, the
numerical value of the test results (Coefficient of Friction)
decreases with an increase in effectiveness. In other words, the
lower the Friction Coefficient value the better the additive is at
reducing friction.
[0207] The test procedure for determining the friction coefficient
with the Cameron-Plint TE77 High Frequency Friction Machine is as
follows. Ten mL of an oil sample containing additive is placed in
the test chamber so as to cover a flat stationary hardened ground
NSOH B01 Gauge Plate (RC 60/0.4 micron). A reciprocating specimen,
a 16 mm long nitrided steel dowel pin (6 mm diameter, 60 Rc), is
placed on top of the steel plate under 50 Newton load, allowed to
heat up to 35.degree. C. from room temperature over 10 minutes and
maintained at 35.degree. C. for 5 minutes. Then, with the 50 Newton
load in place, the reciprocation frequency of 5 Hertz is begun with
a 15 millimeter amplitude stroke length. The temperature is then
ramped up to 50.degree. C. over 10 minutes and maintained at
50.degree. C. for 5 minutes. The load is then increased to 100
Newtons and the temperature is ramped up to 165.degree. C. over 1
hour. Friction Coefficient data are collected between
60-160.degree. C. The flat specimen is cleaned between runs with
hexanes and #500 emery cloth. A new dowel pin or surface of the
dowel pin is used each time. A reference oil is run alternately
between experimental oils. The same flat specimen is used until the
reference oil no longer provides reproducible results.
[0208] The motor oil formulation tested is a SAE 10W-30 grade
containing dispersant, detergent, antioxidant, rust inhibitor, pour
point depressant, OCP VI Improver, and anti-wear additive. Friction
modifier was added as a top treat to this formula.
4TABLE 3 Cameron-Plint High Frequency Friction Machine Friction
Results Mo C of F C of F C of F C of F C of F C of F Wt. % (ppm)
(.mu.) @ (.mu.) @ (.mu.) @ (.mu.) @ (.mu.) @ (.mu.) @ Additive (in
oil) (in oil) 60.degree. C. 80.degree. C. 100.degree. C.
120.degree. C. 140.degree. C. 160.degree. C. Ex. 24 1.5 311 0.115
0.114 0.111 0.090 0.055 0.048 Ex. 25 1.5 260 0.115 0.113 0.110
0.115 0.105 0.064 No 0.0 -- 0.125 0.127 0.130 0.133 0.130 0.125
FM.sup.1 CFM.sup.2 1.0 -- 0.115 0.118 0.115 0.115 0.121 0.121
MoDTC.sup.3 0.53 309 0.110 0.113 0.100 0.085 0.065 0.525 .sup.1The
reference oil is a fully formulated 10 W-30 gasoline crank case
motor oil containing no friction modifier. .sup.2CFM is an ashless
commercially available friction modifier based upon a mixture of
fatty acid amides, glycerol esters, and glycerol. .sup.3MoDTC is a
commercially available molybdenum dithiocarbamate.
[0209] Additive from Example 24 contained 2.07 wt. % Mo, therefore
the oil with the additive from Example 24 contained 311 ppm Mo.
[0210] Additive from Example 25 contained 1.73 wt. % Mo, therefore
the oil with the additive from Example 25 contained 260 ppm Mo.
[0211] Additive MoDTC contained 5.83 wt. % Mo, therefore the oil
with the additive MoDTC contained 309 ppm Mo.
[0212] In view of the many changes and modifications that can be
made without departing from principles underlying the invention,
reference should be made to the appended claims for an
understanding of the scope of the protection to be afforded the
invention.
* * * * *