CA2235182C

CA2235182C - Synergistic organomolybdenum compositions and lubricating compositions containing same

Info

Publication number: CA2235182C
Application number: CA002235182A
Authority: CA
Inventors: Thomas J. Karol; Steven G. Donnelly
Original assignee: RT Vanderbilt Co Inc
Current assignee: Vanderbilt Chemicals LLC
Priority date: 1997-04-22
Filing date: 1998-04-20
Publication date: 2004-08-10
Anticipated expiration: 2018-04-20
Also published as: JP3090904B2; CN1098348C; EP0874040A1; JPH1143686A; CN1201066A; DE69714213T2; EP0874040B1; CA2235182A1; DE69714213D1

Abstract

This invention relates to synergistic antiwear compositions comprising an organomolybdenum complex and an organic sulfur compound selected from 2,5-dimercapto-1,3,4-thiadiazole derivatives, bisdithiocarbamate esters, metal dithiocarbamates, metal phosphorodithioates and phosphorodithioate esters. The organomolybdenum complex is a reaction product prepared by reacting 1 mole fatty oil, 1.0 to 2.5 moles diethanolamine and a molybdenum source.
Lubricating compositions containing the synergistic compositions possess good antiwear properties and improved oxidation stability.

Description

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 O
II
I-1zC - C - O - R2 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 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 \ 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 (v) phosphoroditiioate esters of the formula 4a R -O S O
\ ~~ ~~ 4a P-S-CH-C-0-R (V) sa / ~ sa 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 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 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 ~ 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 _ q _ 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 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.

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.

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.

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 _ g _ 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.
- g _

Claims

1. A synergistic antiwear composition, consisting of:
(a) an organomolybdenum 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 weight of the complex; and (b) a 1,3,4-thiadiazole compound of the general formula:

wherein R and R1 are, independently, selected from the group consisting of an alkyl group having 1 to 22 carbon atoms, a terpene residue and a malefic acid residue of the general formula:

wherein R2 and R3, independently, represent C1-C22-alkyl and C5-C7-cycloalkyl groups, and either R2 or R3 may be hydrogen, and either R or R1 may be hydrogen when R2 and R3 are C9-22-alkyl groups, wherein the ratio of (a) to (b) is about 1:5 to about 5:1.

2. A composition according to claim 1, wherein the 1,3,4-thiadiazole compound is 2,5-bispinanyl-1,3,4-thiadiazole.

3. A synergistic antiwear composition, consisting of:
(a) as defined in claim 1; and (b) a bisdithiocarbamate compound of the general formula:

wherein R4, R5, R6 and R7 are aliphatic hydrocarbon groups having 1 to 13 carbon atoms and R8 is an alkylene group having 1 to 8 carbon atoms, wherein the ratio of (a) to (b) is about 1:5 to about 5:1.

4. A composition according to claim 3, wherein the bisdithiocarbamate compound is methylenebis(dibutyldithiocarbamate).

5. A synergistic antiwear composition, consisting of:
(a) as defined in claim 1; and (b) a dithiocarbamate of the general formula:

wherein R4a and R5a are alkyl groups having 1 to 8 carbon atoms, M represents a metal of the periodic groups IIA, IIIA, VA, VIA, IB or VIII, or a salt moiety formed from an amine of the general formula:

wherein R11, R12 and R13 are, independently, a hydrogen atom or an aliphatic group having 1 to 18 carbon atoms and n is the valence of M, wherein the ratio of (a) to (b) is about 1:5 to about 5:1.

6. A synergistic composition according to claim 5, wherein the dithiocarbamate is an antimony salt.

7. A synergistic antiwear composition, consisting of:
(a) as defined in claim 1; and (b) a phosphorodithioate of the general formula:

wherein X and X1 are, independently, S or O, R9 and R10 are, independently, a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and M and n are as defined in claim 5, wherein the ratio of (a) to (b) is about 1:5 to about 5:1.

8. A synergistic antiwear composition, consisting of:

(a) as defined in claim 1; and (b) a phosphorodithioate ester of the general formula:
wherein R4a and R5a are as defined in claim 5, wherein the ratio of (a) to (b) is about 1:5 to about 5:1.

9. A composition according to claim 8, wherein the ester is S-dicarbobutoxyethyl O,O-dipropylphosphorodithioate.

10. A composition according to any one of claims 1 to 9, wherein the ratio of (a) to (b) is about 1:2 to 5:1.

11. A lubricating composition comprising an oil of lubricating viscosity and about 0.1 to 10.0 percent by weight of a synergistic antiwear composition as defined in any one of claims 1 to 10.

12. A lubricating composition comprising an oil of lubricating viscosity and about 0.1 to 10.0 percent by weight of a synergistic antiwear composition as defined in one of claims 1 to 4, 8 and 9.

13. A lubricating composition according to claim 11 or 12, comprising about 0.5 to about 5.0 percent by weight of the synergistic antiwear composition.