Note: Descriptions are shown in the official language in which they were submitted.
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SYNERGISTIC ORGANOMOLY13DENUM COMI'OSI'fIONS
AND LUBRICATING COMPOSITIONS CONTAINING SAMC
BACKGROUND OP TI-IE INVENTION
'hire invention concerns lubricating compositions having improved properties.
Another aspect of the invention relates tv additive cotnposilions which impart
atltiwear acrd
atrtiscufGng properties to lubricating compositions used for internal
combustion engines
such as gasoline engine and diesel engine.
to Additives known as antiwear agents are employed to increase the load
carrying
capacity of lubricants. 'hire atrtiwear agents promote the formation of a
surface film and
thereby prevent wear of the contacting surfaces. The mechanical efficiency
etthatlced by
decreased friction loss further results in decreased fuel consurnption and
energy savings.
1l is known that certain organic molybdenum complexes possess atltiwear
properties as well as ollrer dcsirablc lubricating clraracterislics as
disclosed in U.S. I'at. No.
4,889,647. Surprisingly, it has beers now discovered that the tnolybdenutn
complexes
described llterein produce a synergistic atltiwear effect in combination with
certain organic
sulfur compounds.
SUMMARY OF TI-IE INVEPdTION
20 According to the invention, there are provided synergistic antiwear
compositions
comprising:
( 1 ) as orgatlomolybdenutn complex prepared by reacting about I mole fatty
oil,
about 1.0 to 2.5 moles dielhanolarnine and a molybdenum source sufficient to
yield about
U. I to 12.0 percent of molybdenum based on the weight of the complex, and
(2) atl organic sulfur compoutld selected From the group consisting of
(i) 1,3,4-lhiadiazole compounds of the formula:
N-N
II II
R-S-C C-S-R' (I)
S
30 wherein R and R' ate independently selected from Cr.22-alkyl groups,
tetpene residue and
tnaleic acid residue of the formula
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O
II
I-1zC - C - O - R2
-HC-C-O-R3
I~
O
and RZ and R~ represent C,.ZZ-alkyl and Cs.~-cycioalkyl groups, either Ri or
R3 may be
hydrogen and either R or R' may be hydrogen when R~ or R~ are C9.z1-alkyl
groups;
(ii) bisdithiocarbamate compounds of the formula
R4 S S R6
II. . II
N-C-S-Re-S-C-N (II)
l0 . Rs '~ ~ R~
wherein R4, Rs, R6, and R' are aliphatic hydrocarbyl groups having 1 to 13
carbon atoms
and Ra is an alkylene group having 1 to 8 carbon atoms;
(iii) dithiocarbarnates of the formula
4a
R S
\ I~
N-C-S- M+" (111)
Sa /
R n
4a Sa
wherein R and R represent alkyl groups having 1 to 8 carbon atoms, M
represents metals
of the periodic groups IIA, IIIA, VA, VIA, IB, VIB, VIII and a salt moiety
formed from an
Rt3
amine of the formula R~ ~ - N - R~Z, Rt ~, Rti and R'3 being independently
selected from
Itydro~en arid aliphatic groups having 1 l0 18 carbon alotns and n is the
valence of M;
(iv) phosphorodilhioales of the fornwla
R9-O X
\ it
P - X' - M+" (IV)
R~° -0 ~ n
wherein X and X' are independently selected from S and O, R9 and Rt°
represent hydrogen
and alkyl groups having 1 to 22 carbon atoms, M represents metals of the
periodic groups
IIA, IIIA, VA, VIA, IB, VIB, VIII and a salt moiety formed from an amine of
the formula
t
' R~ ~-N-R~2, Rt ~; Rt2 and R~3 being independently selected from hydrogen and
aliphatic
groups having 1 l0 18 carbon atoms and n is the valence of M; and
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(v) phosphoroditiioate esters of the formula
4a
R -O S O
\ ~~ ~~ 4a
P-S-CH-C-0-R (V)
sa / ~ sa
R -O CH2 C-0-R
y
O
4a Sa
wherein R and R may be the same or different and are selected from alkyl
groups having
1 to 8 carbon atoms; and the ratio of the molybdenum complex to the sulfur
compound is
about 1:5 to about 5:1.
Another aspect of the invention concerns lubricating compositions having
improved
l0 lubricating properties and comprising a major portion of an oil of
lubricating viscosity and
about 0.1 to 10.0 percent by weight of a composition comprising (1) an
organomoly-
bdenum complex prepared by reacting about 1 mole fatty oil, about 1.0 to 2.5
moles
diethanolamine and a molybdenum source sufficient to yield about 0.1 to 12.0
percent of
molybdenum based on the weiglri of the complex and (2) a sulfur compound of
the
formula I, lI, III, IV or V.
DETAILED DESCRIPTION OF THE INVENTION
The organomolybdenum component of the invention is prepared by sequentially
reacting fatty oil, diethanolamine and a molybdenum source by the condensation
method
described in U.S. Pat. No. 4,889,647. The reaction yields
Z~ a reaction product mixture. The major components are believed to have the
structural
formulae
HZC-O O O CHZ-CH=-O 0
ii ~ \ //
Mo and R-C-N Mo
H C-O ~O ~ CHZ-CH=-O ~O
HIC - O-C-R
~i
0
wherein R represents a fatty oil residue. The preferred fatty oils. are
glyceryl esters of
higher fatty acids containing at least I2 carbon atoms and may contain 22
carbon atoms
and higher. Such esters are commonly known as vegetable and animal oils.
Vegetable oils
30 particularly useful are oils derived from coconut, corn, cottonseed,
linseed, peanut, soybean
and sunflower seed. Similarly, animal fatty oils such as tallow may be used.
The source of molybdenum is an oxygen-containing molybdenum compound
capable of reacting with the intenmediate reaction product of fatty oil and
dielhanolamine
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to fc8m. an ester-type molybdenum complex. The source of molybdenum includes,
ampng
others, ammonium molybdates, molybdenum oxides and mixtures thereof.
The 1,3,4-thiadiazoles of formula I may be prepared by the method disclosed in
U.S. Pat. No. 4,761,842 and U.S. Pat. No. 4,880,437. Terpene residues are
preferably
derived from pinene and limonene having the structural formulae given
hereinbelow.
CH; CH3
and
CH3
- CH3 CH3 ~ CH2
The alkyl groups represented by R and R' contain preferably 1 to 22 carbon
atoms
and may be branched or straight chain. Particularly preferred are compounds
wherein both
alkyl groups together contain a total of at least 22 carbon atoms: Groups RZ
and R3 in the
formula 1 represent branched or sUaight chain alkyl groups containing 1 to 22
carbon atoms
and cyclic aliphatic groups such as cyclohexyl, cyclopentyl and cycloheptyl:
The bisdithiocarbamates of formula II are known compounds described in U.S.
Pat.
No. 4,648,985. The compounds are characterized by
groups R, to R' which are the same or different and are hydrocarbyl groups
having 1 to 13
carbon atoms. The group R8 is an aliphatic group such as straight and branched
alkylene
groups containing 1 to 8 carbons. Particularly preferred is methylenebis
(dibutyldithiocar-
bamate) available commercially under the tradename VANLUBE~ 7723 from R.T.
Vanderbilt Company, Inc.
The dithiocarbamates of the formula III are known compounds. One of the
4a Sa
processes of preparation is disclosed in U.S. Pat. No. 2,492,314. Groups R and
R in the
formula III represent branched and straight chain alkyl groups having 1 to $
carbon atoms.
Particularly preferred are antimony dithiocarbamates.
The phosphorodithioaies of the formula IV are known, commercially available
materials. One of the processes of preparation is taught by U.S. Pat. No.
4,215,067.
Groups R9 and R~° represent branched and straight chain alkyl groups
having I-22 groups
3 0 and may be derived from fatty acids. The metal ion in formula III and IV
may be selected
from the following groups of the Periodic Table: IIA, IIIA, VA, VIA,1B, VIB
and VIII.
Amine salts of the compounds are also useful synergists of the invention.
Exemplary, salts
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include among others, those prepared from alkyl amines and mixed alkyl amines.
Particularly useful are fatty acid amines.
The phosphorodithioate esters of the formula V are known compounds. One of the
processes of manufacture is disclosed in U.S. Pat. No. 3,567,638. Groups
R° and RS in the
formula V may be the same or different and may be selected from branched and
straight
chaili alkyl groups. Preferred are groups containing 1 to 8 carbon atoms.
The sulfur compounds are known to possess certain lubricating properties such
as
oxidation, wear and corrosion inhibition in various lubricating media.
Sometimes,
however, the sulfur compounds alone do not provide adequate antiwear
protection for the
varied hea4y duty applications of many industrial and automotive lubricants.
Moreover, under certain conditions, the high concentrations of sulfw compounds
may produce an adverse effect on the overall performance of the lubricant.
Unexpectedly, the above sulfur compounds produce synergistic antiwear effect
when combined with organomolybdenum compounds in certain ratios. Synergism is
displayed by compositions containing about 1 to 5 parts by weight of the
sulfur compotu~d
to about 5 to 1 part by weight of the molybdenum compound.
Another advantage of the synergistic combination is that the compositions
possess
good antioxidant properties. Even in instances where the sulfur compounds do
not possess
an antioxidant activity, the combination with the molybdenum complexes
provides a
composition with good overall antioxidant properties.
The synergistic compositions may be incorporated in any lubricating media by
knOWil IllethOdS. The compositions impart antiwear as well as oxidation
inhibiting and
extreme pressure properties to natural and synthetic lubricants formulated as
oils or
greases.
The base oils employed as lubricant vehicles are typical natural and synthetic
oils
used in automotive and industrial applications such as, among others, twbine
oils,
hydraulic oils, gear oils, crankcase oils and diesel oils. Natwal base oils
include mineral
oils, petroleum oil, paraffinic oils and the ecologically desirable vegetable
oils. Typical
synthetic oils include pentaerythritol esters, poly-alpha-olefins,
hydrogenated mineral oils,
silicones and silanes.
The compositions of the invention may be incorporated in the lubricant in an a-
mount effective to produce the desired aniiwear characteristics. An amount
from about 0.1 to
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10.0 percent will be sufficient for most applications. A preferred range is
from about 0.5
tc about 3. 0 percent by weight of the total lubricant composition.
The lubricating compositions may contain other conventional additives
depending
on the intended use of the lubricant. For example, formulations may contain
rust inhibitors
such as metal salts of alkylnaphthalenesulfonic ac~~is, demulsifiers,
dispersants, detergents
and supplemental antioxidants, particularly alkylated diphenylamines.
The grease formulations may contain various thickening agents such as, among
others, silicate minerals, metal soaps and organic polymers.
The following examples are given for the purpose of illustrating the invention
and
are not intended in any way to limit the invention. All percentages and parts
are based on
weight unless otherwise indicated.
EXAMPLE 1
A laboratory test was conducted by using the original Falex machine tv
simulate the
valve train wear of an automobile engine. The V-blocks and pin were washed in
mineral
spirits with an ultrasonic cleaner, rinsed with acetone, air dried and
weighed. The test
sample (60 g) was placed into the oil cup. The motor was switched on and the
loading arm
was placed on the ratchet wheel. Upon reaching the reference load of 227 kg,
the ratchet
wheel was disenggged and the load was maintained constant for 3.5 hours.
Thereafter, the
motor was switched off. The V-blocks and pin were washed, dried and weighed.
The
weight loss, a measure of wear, was recorded and compiled in Table I.
The test was performed with a molybdenum complex in conjunction with the
following ashless sulfur compound synergists of the invention: S-
dicarbobutoxyethyl 0,0-
dipropylphosphorodithioate (hereinafter phosphorodithioate ester) and
methylenebis-
(dibutyldithiocarbamate). The molybdenum complex was a reaction product of
coconut
oil, 2,2'-iminobisethanol and hexammonium salt of molybdic acid. The base oil
was a
hydrofinished naphthenic oil (ISO VG 22 manufactured by Sun Refining and
Marketing
Co.).
The results compiled in Table I indicate that the molybdenum complex and the
above sulfur compounds act as synergists towards inhibition of wear.
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Table I
ModiFed Fale,Y Wear Test
Component, Mass Percent
Salilnle 1 2 3 4 S 6
Molybdenum complex 1.0 1.5 -- 0.5 -- 0.5
Phosphorodithioate ester -- -- 1.0 0.5 -- --
Methylenebis(dibutyldithiocarbamate) -- -- -- -- 1.5 1.0
'Lest parameters
Test Time, min. 40* 75* 20* 210 210 210
1 o Total Weight Loss, mg. 433 542.8 -- 14.6 86.4 3.4
*Test terminated due to excessive wear
IJliHLV, Yl LL; G
The modified Falex Wear Test described in Example 1 was performed with the
same molybdenum complex in conjunction with the following metal salts of the
sulfur
compound synergists: nickel dilauryldithiocarbamale, calcium di-2-
ethylhexyldithio-
phosphate, aluminum di-2-ethylhexyldithiophosphate, tellurium di-2-
ethylhexyldithio-
phosphate, gild Cii-~4-alkylamine salt of tert-octyl phosphates (hereinafter
dithiophosphate
amine salt). The base oil was a hydroFnished naphthenic oil (ISO VG 22).
The results compiled in Table II herein indicate that the molybdenum complex
and
20 the above salts of the sulfur compounds act as synergists towards
inhibition of wear.
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Table II
dif
d F
M
l
'
o
S ie
l a
ex Wear
rest
Component, Mass Percent
ayD Z 8 9 10 1l 12 13 15 1G 17
e 14
Molybdenum complex 1.5 -- 0.5 -- 0.5 -- 0.5 0.5 0.5
-- --
Nickel dithiocarbamate -- I.5 l.0 -- -- -- -- -- -- --
--
Calcium ditlriophosphate -- -- -- I.5 1.0 -- -- -- -- --
--
Aluminum dithiophosphate -- -- -- -- -- 1.5 1.0 -- -- --
--
Tellurium dithiophosphate -- -- -- -- -- -- -- 1.0 --
1.5 --
Dithiophosphate amine -- -- -- -- -- -- -- -- 1.5 I.0
salts --
Test Parameters
Test Time, ruin. 75* 5* 210 5* 210 210 210 210 210
120* 2*
Total Weight Loss, mg. 542.8 3GG.8 14.9 3GG.G18.4 17.7 41.9
90.1 33.5 84.8 S.G**
* Test terminated due to excessive wear
**High galling fail
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EXAMPLE 3
A thin film oxygen uptake test was conducted essentially according to the
method
described by Chia-Soon Ju et al, J. Atn. Sod . ~bric~li 1L ~n~., 40, 2, 75-83,
1984. 'fhe
oxidation induction time of the lubricant was measured under conditions which
simulate
the high temperature oxidation processes in automotive engines by modified
rotary bomb
oxidation test method ASTM D-2272. The test was conducted with 1.5 gram
samples of
hydrofinished naphthenic oil, ISO VG 22. The composition of the invention
described in
Example 1 and, for comparison, the individual components, were added to the
oil in the
amount indicated in 'fable III. 'I~lie test was conducted at 1GU°C and
initial oxygen
pressure of G20.G kPa (90 psi). A "pass" oil has a high induction time, while
a "fail" oil
has a low induction time. The compositions of the invention display good
antioxidative
effect as demonstrated by the data compiled in Table III.
Table III
Component, Mass Percent
Molybdenum complex 1.0 1.5 -- 0.5
Methylenebis (dibutyldithiocarbamate) -- I.5 1.0
Test Parameter
Average Induction Time, min. 10 10 75 93
The above embodiments have shown various aspects of the present invention.
Other variations will be evident to those skilled in the art and such
modifications are
intended to be within the scope of the invention as defined by the appended
claims.
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