Note: Descriptions are shown in the official language in which they were submitted.
5~;~35
1 BACKGROUND OF THE DNVENTION
2 The present invention concerns oil-soluble molyb-
3 denum complexes of ashless nitrogen dispersants, their
4 method of preparation, and the utility of said molybdenum
containing dispersants as lubricating oil additives, which
6 markedly improve the sludge dispersancy, friction-reducing
7 properties of lubricating oils employed for crankcase lubri-
8 cation of i~ternal combustion engines.
9 There are two principle environ~ents which are en-
countered by automotive crankcase lubricants, i.e. cyclical
11 high and low temperatures from stop-and-go driving and con-
12 tinuous high temperatures from extended operation of the
13 automobile over long distances. Each of these environments
14 provokes the presence in the lubricant of varying proportions
of foreign particles such as dirt, soot, water and decomposi-
16 tion products resulting from breakdown of the oil. ~his for-
17 eign matter appears responsible for the deposition of a mayon-
18 naise-like sludge which circulates with the oil.
19 During the past decade, ashless sludge dispersants
have become increasingly ~mportant, primarily in improving
21 the performance of lubricants in keeping the engine clean of
22 deposits and permitting extended crankcase oil drain periods
23 while avoiding the undesirable environmental Lmpact of the
24 earlier used metal-containing additives. One co~mercial
type of ashless dispersant contains nitrogen resulting from
26 the attachment of an amine or polyamine to a long-chain hy-
27 drocarbon polymer (the oil solubilizing portion of the mole-
28 cule), usually polyisobutylene through an aci~ group, e.g.
29 polyisobutenyl succinic anhydride, by forming amide or imide
linkages.
31 In the operation of an internal combustion engine,
32 there are many "Boundary Lubrication" conditions where two
33 rubbing surfaces must be lubricated, or otherwise protected,
34 so as to prevent wear and to lns~lre continued movement.
Moreover, where, as in most cases, friction between the two
36 surfaces will increase the power required to effect mo~ement
37 and where the movement is an integral ~art of an energy con-
~ 57 3 5
-- 2 --
1 version system, it is most desirable to effect the lubrica-
2 tion in a manner which will mlni~ize this friction and/or
3 reduce wear. As is also well known~ both wear and friction
4 can be reduced, with various degrees of success, through the
addition of a suitable additive or combination thereof, to a
6 natural or synthetic lubricant. Similarly, continued ve-
7 ment can be insured, again with varying degrees of success,
8 through the addition of one or more appropriate additives.
9 ~hile there are many known lubricant additives which
lG may be classified as antiwear, antifriction and extreme pres-
11 sure agents and some may in fact satisfy more than one of
12 these functions as well as provide other useful functions,
13 it is also known that many of ~hese additives act Ln a dif-
14 ferent physical or chemical manner and often c~mpete with one
another, e.g. they ~ay compete for the surface of the moving
16 metal parts which are subjected to lubrication. Accordingly,
17 e~treme care must be exercised in the selection of these ad-
18 ditives to ~nsure compatibility and effectiveness.
19 me metal dihydrocarbyl dithiophosphates, e.g. the
zinc dialkyl dithiophosphates, are one of the additives which
21 are known to exhlbit antioxid2nt and antiwear properties.
22 While they afford excellent oxidation resistanc~s and exhibit
23 superior an~iwear properties, it has heretofore been believed
24 that the same increases or significantly limits their ability
to decrease friction between mo~ing surfaces. As a result,
26 compositions containlng zinc dialkyl dithiophosphates were
27 not believed to provide the most desirable lubricity and, in
28 turn~ it was believed that use of compositions containing the
29 same would lead to significant energy losses in overcoming
3C friction e~en when antifriction agents are included in the
31 composition.
32 Known ways to solve the problem of energy losses due
33 to high friction Ln crankcase lubrication include the use of
34 synthetic ester base oils ~hich are expensive and the use of
insoluble lybdenum sulfide ar.d graphite dispersions which
~ S7 ~ 5
1 have the disadvantage of giving the oil composition a black
2 or hazy appearance. It would be desirable then to provide
3 oil-soluble molybdenum compounds and thus overcome the dis-
4 advantage. Oil-soluble molybdenum additives taught as use-
ful in lubricating oils include the molybdates of organic
6 nitrogen bases obtained from heating an aqueous solution of
7 molybdic acid and an aliphatic amine or heterocyclic nitro-
8 gen base (see U.S. 3,144,712).
9 The practical exploitation of Yarious types of
molybdenum compounds and complexes as lubricant additives
ll has been hindered not only by their insolubility and/or cor-
12 rosiveness but also by low thermal stability.
13 SUMMARY OF THE DNVENTION
-
14 It has now been discovered that ashless nitrogen-
containing dispersants can be reacte~ with a source of lyb-
16 denum to provide a molybdenum-containing ashless dispersant
17 of improved thermal stability in lubricating oils and ha~ing
18 the property of importing enhanced lubricity to said lubri-
19 cating oil. This has been accomplished by us~ of an aqueous-
non-aqueous reaction medium. The operational embodiment of
21 the invention thus is a lubricating oil composition compris-
22 ing a major proportion of mineral oil and a minor but a
23 friction reducing amount of an oil-soluble lybdenum-contain-
24 ing ashless nitrogen lubricating oil dispersant, said disper-
sant having from 0.5 to 20 wt.% molybdenum based on the
26 weight of said dispersant.
27 These materials are preparet from conventional ash-
28 less nitrogen dispersants by reaction of said dispersant with
29 an inorganic lybdenum compound in a binary solvent system
3C comprising an aqueous component of the class cansisting of
31 water and ammonium hydroxide and a non-aqueous component
32 consisting of the class consisting of tetrahydrofuran (THF)
33 and a hydrocarbon boil~ng between 70 and 250C. The volume
34 ratio of aqueous to non-aqueous componen~ ranges from 1:1000
to 1:1, preferably 1:100 to 1:4, optimally 1:10. ~n the con-
36 text of this in~ention, the aqueous component can be con-
ll;~S~735
- 4 -
1 sidered a promoter for the molybdation of the nitrogen dis-
2 persant. Thus, for the purposes of this discussion, both
3 the water and the ammonium hydroxide could be defined as an
4 essential promoter of molybdation in a non-aqueous reaction
medium.
6 It has now been further discovered that a stable
7 lybdenum complex can be obtained with little if any de-
8 struction of the ashless dispersant when complexing is ef-
9 fected at a temperature of 40C. to 250C., preferably from
50 to 200C., in said binary solvent system.
11 In accordance with the present invention, it is
12 preferred that the lubricity enhancing, i.e. friction reduc-
13 i~g, additive is present in the mineral oil in an amount to
14 provide from about 0.01 to 2.0, preferably 0.02-1.0 and
optimally 0. 05-0. 5 weight percent molybdenum in said oil)
16 all weight perc~nt being based on the total weight of the
17 lubricating composition.
18 rn preferred fonm, the lybdenum complex is that
19 of a nitrogen compound derived from the reaction of one to
2G three moles of a hydrocarbyl substituted dicarboxylic acid
21 materia~ such as poly(isobutenyl) succinic anhydride wherein
22 said hydrocarbyl substituent e.g. the poly(isobutenyl) group
23 has a (~) ranging from about 700 to 5,000, optimally from
24 abou~ 900 to 1600 and preferably 1.3 moles of said dicarboxy-
lic acid material, with about 1 mole of tetraethylene pent-
26 amine (includes commercial equivalent~, said compound being
27 complexed with from 1 to 2 molar equivalents of molybdic
28 oxide, i.e. MoO3 and containing from 0.5 to 20, preferably
29 .2 to 10, optimally 5, wt.% molybdenum.
DETAILED DESC~IPTION OF THE rNVENTION
31 Lubricatin~ OiI Dispersant
32 Generally, any nitrogen-containing dispersant addi-
33 tives including m~neral oil-soluble salts, amides, imides,
34 and esters of no- and dicar~oxylic acids (and wher2 they
exist the corresponding acid anhydrides) and various amines
36 Of nitrogen-containing materials having amino nitrogen or
11~5735
heterocyclic nitrogen and at least one amido capable of salt, a~ide
or imide formation can be complexed wlth molybdenum according to
this invention. Other nitrogen-containing dispersants which may be
used in this invention lnclude those wherein a nitrogen-containing
polyamine is attached directly to the long chain aliphatic hydro-
carbon as shown in U.S. Patents 3,275,554 and 3,565,804 where the
halogen group on the halogenated hydrocarbon is displaced with
various alkylene polyamines.
The nitrogen-containing dispersants described hereinafter
are characterized by a long chain hydrocarbon group, or groups,
which may be attached, e.g. to the acld, so the acid contains a
total of about 50 to about 400 carbon atoms, said acid being attach-
ed to the amine either through salt,imlde,amide~or ester groups.
Usually, these dispersants are made by condensing a dicarboxylic
acid, preferably a succinic acid-producing material, such as alkenyl
succinic anhydride, with an amine or polyamine.
The hydrocarbyl substituent may also be a copolymer of 30
to 80 wt.% ethylene and 20 to 70 wt.~ of one or more C3 to C18
alpha-olefin, preferably propylene having a number average molecu-
lar weight of 700 to 250,000, preferably 10,000 to 200,000 as
determined by vapor pressure osmometry (VPO).
Terpolymers of ethylene, said alpha-olefin and 0.5 to 20
mol ~, based on said total polymer, of a non-conjugated diolefin,
such as a hexadiene, may also be used. The hydrocarbyl substituent
may also be a hydrogenated copolymer of butad~ene and styrene or a
terpolymer of a butadiene, styr~ne and isoprene. If the hydro-
carbyl group has a molecular weight above?l0,000 then the molyb-
denum containing dispersant also has viscosity-index improving
properties. The molybdenum-containing dispersant contains between
0.001 and 25 wt.~, preferably 0.01 to 10 wt.% and more preferably
between 0.05 and 5 wt.~ oxygen and nitrogen.
The most commonly used dicarboxylic acid is alkenyl
5 7~ ~
1 succinic anhydride wherein the alkenyl group contains about
2 50 to about 400 carbon atoms.
3 PrLmarily because of its ready a~ailability and low
4 cost, the hydrocarbon portion of the mono- or dicarboxylic
acid or other substituted group is preferably derived from a
6 polymer of a C2 to C5 monoolefin, said polymer ge~erally
7 having a molecular weight of about 700 to about 5000. Parti-
8 cularly preferred is polyisobutylene.
9 Polyalkyleneamines are usually the amines used to
lC make the dispersant. These polyalkyleneæmines include those
11 represented by the general formula:
12 H2N(CH2)n [NH(CH2)n]m --NH(CH2)nNH2
13 wherein n is 2 or 3, and m is O to 10. Examples of such poly-
14 alkyleneamines include diethylene triamine, tetraethylene
pentamine, octaethylene nonamine, tetrapropylene pentEmine,
16 as well as various cyclic polyalkyleneamines.
17 Dispersants formed by reacting about equal molar
18 amounts of polyisobutenyl succinic anhydride and a tetra-
19 ethylene pentamine are described in U.S. Patent 3,202,678.
Similar dispersants, but made by reacting a molar amount of
21 alkenyl succinic anhydride with about two molar amounts of
22 polyalkyleneamines, are described in U.S. Patent 3,154,560.
23 Other dispersants, using still other molar ratios of alkenyl
24 succinic anhydride and polyalkyleneamines are described in
U.S. Patent No. 3,172,892. Still other dispersants of ~1-
26 kenyl succinic anhydride with other a~ines are described in
27 U.S. Patents 3,024,195 and 3,024,237 (piperazine amines)
28 ~nd 3,219,666. An ester deri~ative is taught in Belgian
29 Patent 662J875 w~here N-alkyl morpholinone esters, e.g. N-(2-
3G hydroxyethyl)-2-morpholinone, are forme~ by reaction with
31 polyiQobutenyl succinic anhydride~ The prior art also
32 teaches that the alkenyl succinic polyamine type dispersants
33 can be further modified by reacting a fatty acid having up
34 to 22 carbon atoms, e.g. a~etic acid, with the reaction pro-
3~ duct of the alkenyl succinic anhydride and polyamine (see
36 U.S. Patent 3,216,936).
-- 7 --
1 While any of the above type ashless nitrogen dis-
2 persants may be complexed according to this invention, parti
3 cularly preferred are those prepared with alkenyl succinic
4 acid/anhydrides where the alkenyl radicals have a molecular
weight of at least about 700 to 5,000 and preferably at
6 least about 1200 and more preferably at least about 1300.
7 Particularly preferred nitrogen containing disper-
8 sants are those d~rived from amine compounds having the fol-
9 lowing formulas:
lC (A) alkylene polyamines
l H - N ~ alkylene N ~ H
13 x
4 wherein x is an integer of about 1 to 10, preferablY about 2
to 4, ~ is hydrogen, a hydrocarbon or substantially a hydro-
16 carbon group co~tain~ng about 1 to 7, preferably about 1 to 4
17 carbon atoms and the alkylene radical is a straight or
18 branched chain alkyler.e radical having up to about 7 prefer-
19 ably about 2 to 4 carbon atoms;
(B~ polyoxyalkylene polyamines
21 (i) NH2--alkylene ~ 0-alkylene ~ NH2
23 where m has a value of about 3 to 70 and preferably 10 to 35
24 and
26 (ii) R ~ alkylene ~ 0-al~ylene 3n NX2 ]3 6
27 ~here n has a value of about 1 to 40 with the proviso that
28 the sum of all the n's is from about 3 to about 70 and pre-
29 ferably from about 6 to about 35 and R is a polyvalent satu-
3G rated hydrocarbon radical of up to ten carbon atoms having a
31 valence of 3 to 6. The alkylene groups i~ either formula (i)
32 or (ii) may be straight or bra~ched chains containing about 1
33 to 7 and preferably about 1 to 4 car~on atoms; and
34 (C) primary amines and hydroxy substitutes thereof
R - NH2
36 where R is a ncvalent organic group having up to 20, pre-
37 ferably 10 carbon atoms and may cQntain one or re alcoholic
~1~57~5
-- 8 --
1 hydroxyl groups and preferably 1 to 6 alcoholic hydroxyl
2 groups. The R group in this formula may be an aliphatic,
3 aromatic, heterocyclic or carbocyclic radical. An alcoholic
4 hydroxyl group being one not attached to a carbon atom fonm-
ing part of an aromatic nucleus.
6 The alkylene polyamines of formula (A) above in-
7 clude, for example, methylene amines, ethylene amines,
8 butylene amines, propylene amines, pentylene amines, hexylene
9 amines, heptylene amines, octylene amines, other polymethyl-
ene amines, and the cyclic and higher homologs of these
11 amines such as the piperazines, and the amino-alkyl-substi-
12 tuted piperazines. These amines include, for example,
13 ethylene diamine, triethylene tetramine, propylene diamine,
14 di(heptamethylene) triamine, tripropylene tetramine, tetra-
ethylene pentamine, trimethylene diamine, pentaethylene hex-
16 amine, di(trimethylene) triamine, 2Gheptyl-3-~2-aminopropyl3
17 imidazoline, 4-methylimidazoline, 1,3-bis-(2-aminoethyl) imi-
18 dazoline, pyrimidine, 1-(2-aminopropyl) piperazine, 1,4-bis-
19 (2-aminoethyl) piperazine, N,N-dimethylaminopropyl amine,
Q N,N-dioctylethyl amine, N-octyl-N'-methylethylene diamine,
21 and 2-methyl-1-(2-aminobutyl) piperazine. Other higher
22 homologs which may be used can be obtained by condensing two
23 or more of the above-mentioned alkylene amines in a known
24 ~anner.
The ethylene amines which are particularly useful
26 are described, for e~ample5 in the Encyclopedia of Chemical
27 Tec~nology under the heading of "Ethylene Amines" (Kirk and
28 Othmer), Volume 5, pgs. 898-905; Interscience Publishers,
29 New York (1950). These compounds are prepared by the reac-
C tion of an alkylene chloride with ammonia. This results in
31 the production of a complex mixture of alkylene amines, in-
32 cluding cyclic condensation products such as piperazi~es.
33 While mixtures of these amines may be used or purposes of
34 this invention, it is obvious that pure alkylene amines may
be used with complete satisfaction. A particularly useful
36 al~ylene a~i~e comprises a mixture of ethylene amines pre-
1~h,573S
g
1 pared by the reaction of ethylene chloride and ammonia which
2 may be characterized as having a composition that corresponds
3 to that of t~traethylene pentamine. In addition, the alkyl-
4 ene amines having one or re hydroxyalkyl substituents on
5 the nitrogen atoms may be used. These hydroxy^alkyl-sub-
6 stituted alkylene amines are preferably compounds wherein
7 the alkyl group is a lower alkyl group, i.e. having less
8 than about 6 carbon atoms and includeJ for example, N-(2-
9 hydroxyethyl) ethylene diamine, N,N'-bis(2-hydroxyethyl)
10 ethylene diamine, 1-(2-hydroxyethyl) piperazine, monohydroxy-
11 propylsubstituted diethylene triamine, 1,4-bis(2-hydroxy-
12 propyl)-piperazine, dihydroxy-propyl-substituted tetra-
13 ethylene pent2mine, N-~3-hydroxy-propyl) tetramethylene di-
14 amine, 2-heptadecayl-1-(2-hydroxyethyl) imidazole, etc.
15 The polyoxyalkylene polyamines of formula (B) above,
16 which may be complexed according to this invention, e.g. poly-
17 oxyalkylene diamines and polyoxyalkylene triamines, may have
18 average molecular weights ranging from about 200 to about
l9 4000 and preferably from about 400 to about 2000. The pre-
20 ferred polyoxyalkylene polyamines for purposes of this in-
21 ~ention include the polyoxyethylene and polyoxypropylene di-
22 amines and the polyoxypropylene triamines having average
23 molecular weights ranging from about 200 to 2Q00. The poly-
24 oxyalkylene polyamines are commercially available and may be
25 obtained, for example, from the Jefferson Ch~mical Company,
B 26 Inc. under the trade ~ "Jeffamines D-230, D-400J D-1000,
~7 D-2000, T-403", etc.
28 The primary and hydroxy substitutes thereof, as de-
2~ fined by formula (C) include aliphatic amines, aromatic
3C ami~esJ heterocyclic or carbocyclic amines as well as the
31 hydroxy substitutes thereof. Specific amines of this type
32 include methylamine, cyclohexylamine, aniline, dodecylamine,
33 2-amino-1-butanol, 2-amino-2-methyl-1-propanol, p-(~ -hy-
34 droxyethyl~-aniline, 2-amino~l-propanoL, 3-amino-1-propanol~
35 N-( ~ -hydroxy-propyl~ aminoethyl~-piperazine, 2-
36 amino-l-butanol, ethanolamine, ~ - ~ -hydroxy-ethoxy)-
1~257;~5
ethylamine, glucamine, glucosamine, 4-amino-3-hydroxy-3-methyl-l-
butene (which can be prepared according to procedures known in the
art by reacting isopreneoxide with ammonia), N-(3-amino-propyl)-4-
(2-hydroxyethyl)-piperidine, 2-amino-6-methyl-6-heptanol, 5-amino-
l-pentanol, N-(~-hydroxyethyl)-1,3-diamino propane, 1,3-diamino-2-
hydroxypropane, N~ hydroxyethyl)-ethylene diamine, and the like.
Mixtures of these or similar amines can also be employed.
Particularly preferred amine derived dispersants of the
above-described types are those derived from about 0.3:1 to about
20:1, preferably about 1:1 to about 10:1 and more preferably from
about 2:l to about lO:l moles of alkenyl succinic acid/anhydride
to amine. It is also particularly preferred that the nitrogen con-
tent of the prepared amine derived dispersant be less than about
2 percent by weight and preferably less than 1.5 percent. The
preferred dispersants are those derived from polyisobutenyl succinic
anhydride and polyethylene amines, e.g. tetraethylene pentamine
and polyoxyethylene amines, e.gO polyoxypropylene diamine and com-
binations thereof.
To further enhance the dispersancy, the acyl nitrogen
dispersant, e.g. the alkenyl succinic polyamine, is readily borated
as generally taught in U.S. Patent 3,254,025. This is readily
accomplished by treating said acyl nitrogen dispersant with a boron
compound se ected from the class consisting of boron oxide, boron
halides, boron acids and esters of boron acids ln an amount to pro-
vide from about 0.1 atomic proportion of boron for each mole of said
acylated nitrogen composition to about 10 atomic proportions of
boron for each atomic proportion of nitrogen of said acylated nitro-
gen composition. The borated dispersants for complexing with the
molybdenum source according to this invention contain frGm about 0.1
to 2.0, preferably 0.2 to 0.8, wt.% boron based on the total weight
of said borated acyl nitrogen compound. The boron, which appears to
be in the reactant dispersant as dehydrated boric acid polymers
(primarily HBO2)3, attaches
-- 10 --
~lZ5735
chemically to the dispersant imides and diimides as amine salts
e.g. the metaborate salt of said dilmide and appears not displaced
in the molybdenumization step.
Borating is readily carried out by adding from about 1 to
3 wt.% (based on the weight of said acyl nitrogen compound) of
said boron compound, preferably boric acid which is most usually
added as a slurry to said acyl nitrogen compound and heating with
stirring and at from about 135C. to 165C. for from 1 to 5 hours
followed by nitrogen stripping at said temperature ranges and
filtration if desired.
~ mination and/or imidation of the carboxylic acid material
is usefully carried as a solution reaction with the carboxylic acid
material, e.g. polyisobutenylsuccinic anhydride dissolved in a
solvent such as mineral oil to which the other reactant is added.
The formation of the imlde dispersants in high yield can be effect-
ed by adding from about 0.3 to 1, preferably about 0.4 to 0.7, molar
proportions of alkylene polyamine per molar proportion of dicarboxy-
lic acid material of the nitrogen compound to said solution and
heating the mixture at 140C. to 165C. until the appropriate amount
of water of reaction is evolved. Typically the solvent mineral oil
is adjusted so that it constitutes 50% weight o~ the final acyl
nitrogen compound solutlon.
MOLYBDENUM SOURCE
The source of molybdenum is a molybdenum oxygen-or sulfur-
containing compound capable of complexing with the ashless dispers-
ant to provide a thermally stable molybdenum complex containing
from about 0.5 to 20, preferably 2 to 10, optimally about 5r wt.%
molybdenum based on the total weight of said complex. The sources
of molybdenum include molybdic acid, molybdic trioxide (preferred)
which is also known as molybdic anhydride and as molybdic oxide,
ammonium thiomolybdate, ammonium bismolybdate, molybdenum halides,
and ammonium heptamolybdate tetrahydrateO
METHOD OF PREPARING THE CO~PLEX
The organo molybdenum complex is substantially the
1125735
2 -
1 product of a binary solution reaction of lto 2 moles ashless
2 dispersant (either the borated or non-borated) and 1 mole of
3 lybdenum metal derived from the molybdenum source. The
4 reaction ic readily carried out by reaction at an elevated -
temperature of ~rom 40C. to 250C., preferably 50C. to
6 200C.>optimally 60C. to 180C. to react and stabilize
7 the product complex. The reaction is carried out in a binary
8 solution system wherein water is present (either as water or
9 ammonium hydroxide) along with a non-aqueous component such
as tetrahydrofuran (~HF) or a hydrocarbon boiling between
11 70C. and 250C. and as preferred a second non-aqueous compo-
12 nent which is a higher boiling point hydrocarbon as mineral
13 oil. A highly usef~l reaction system is 1 to 20% water cram-
14 monium hydroxide and mixtures thereof, 20 to 60% mineral oil
a~d the balsce xylene, toluene or tetrahydrofuran.
16 The reaction is carried out over a period of from
17 about 4 to 20, preferably 6 to 12, hours in order to suit-
18 abLy stabilize the complex after which the binary solvents
19 are generally removed and the complex dissolved in mineral
oil for ease of handling.
21 Carrying out the organo molybdenum complexing reac-
22 tion in a binary solvent system wherein one part by weight
23 water or ammonium hydroxide per 1 to 1000 parts by weight of
24 THF or said lower boiling hydrocarbon provides a number of
benefits over a reaction without solvent or in a light aro-
26 matic solvent such as toluene or a light hydrocarbon oil, e.g.
27 mineral oil including: faster reaction time; completion of
28 reaction to a stabilized molybdenum complex at a lower temp-
29 erature; and, an additive product solution which when added
to lubricating oil provides both ~nhanced friction reduction
31 and sludge dispersancy.
32 SULFUR DONORS
33 The hydrocarbon-soluble molybdenum complexes of ash-
34 less dispersants provide not only dispersancy for lubricating
oils but enhanced 3ubricity as well when used in combina-
36 tion with an active sulfur donor which c~n be defined as a
1~57~S
- 13 -
1 compound which when used in admixture with the dispersant-
2 molybdenum complex reduces the coefficient of friction at
3 least about 10% relative to that provided by the complex
4 alone. The active sulfur donor is present in an amount of
from about 0.1 to 10, preferably 0.2 to 2, parts by weight
6 per part by weight of molybdenum complex.
7 Illu~trative of active sulfur donors are metal di-
8 hydrocarbyl dithiophosphates and the corresponding precursor
9 esters, phosphosulfurized pinenes~ sulfurized olefins and hy-
drocarbons, sulfurized fatty esters and sulfurized alkyl
11 phenols.
12 Preferred are the zinc dihydrocarbyl dithiophos-
13 phates which are salts of dihydrocarbyl esters of dithio-
14 phosphoric acids and may be represented by the following
formula:
16 _ _
17RO - P - S Zn
18 OR'
19 _ _ 2
wherein R and R' may be the same or different hydrocarbyl
21 radicals containing from 1 to 18 and preferably 2 to 12 car-
22 bon atoms and including radicals such as alkyl, alkenyl,
23 aryl, aralkyl, alkaryl and cycloaliphatic radicals. Parti-
24 cularly preferred as R and R' groups are alkyl groups of 2 to
8 carbon atoms. Thus, the radicals may, for example, be
26 ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-
27 butyl, amyl n-hexyl9 i-hexyl, n-heptyl, n-octyl, decyl, do-
28 decyl, octadecyl, 2-ethyLhexyl, phenyl, butylphenyl, cyclo-
29 hexyl, methylcyclopentyl, propenyl, butenyl, etc. In order
3G to obtain oil solubility, the total number of carbon atoms in
31 the dithiophosphoric acid will average about 5 or greater.
32 The zinc dihydrocarbyl dithiophosphates which are
33 useful as the coadditive~ i.e. sulfur donorJ of the present
34 in~ention may be prepared in accordance with known techniques
by first esterifying a dithiophosphoric acid usually by reac-
57
- 14 -
1 tion of an alcohol or phenol with P2S5 and then neutralizing
2 the dithiophosphoric acid ester with a suitable zinc compound
3 such as zinc oxide.
4 In general, the zinc dIhydrocarbyl dithiophosphate
will be used in the lubricating composition at a concentra-
6 tion within the range of about 0.01 to about 5 parts by
7 weight per 100 parts of lubricating oil and preferably from
8 about 0.5 to about 1.5. This is adequate for sulfur donation
9 wherPby the lubricity enhancement of the lubricating oil com-
position by the coadditive combination is realized.
11 As noted earlier, an equally suitable active sulfur
12 donor is the dihydrocarbyl esters of dithiophosphoric acid
13 Which may be represented by the formula:
14 l!
RO - ~ - SH
16 OR'
17 where R and R' are as previously defined. Par~icularly use-
18 ful is the dibutylphenyl dithiophosphate.
19 The phosphorosulfurized terpenes as represen.ed by
pinene, dipentene, allo-ocime~e, etc., are another group of
21 dithiophosphate diesters which are active sulfur donors. Of
22 the terpenes, the bicyrlic pinene is preferred. The phospho-
23 sulfurized terpene is readily obtained by reaction of about
2~ one mole of diester of thiophosphoric acid and one mole of
pinene at a temperature of at least 100C., e.g. 10CC. to
26 200C. The preferred a~tive sulfur donor can be character-
27 ized as the bornyl ester of dihydrocarbyl (C2-C20) dithio-
28 phosphoric acids ~as shown in U.S. 2,689,258).
29 m e sulfurized olefins and hydrocarbons are fur-
3G ther esters of thiophosphoric acids which are useful sul~ur
31 donors. These esters are achieved by reaction with olefins
32 such as ethylene, propylene, isobutylene, decene, dodecene,
33 octadecene, etc., olefin polymers of molecular weight ranging
34 from 100 to 50,000 such as ethylene, propylene, isobutylene,
etc., aromatics such as benzene, naphthalene, toluene, xyl~ne,
57~3S
- 15 -
1 etc., petroleum fractions and condensation product of kalo-
2 genated aliphaeic hydrocarbons with aromatic compounds, e.gO
3 wax-naphthalene (see U.S. 2,804,431).
4 The sulfurized fatty esters are another subclass of
esters which are active sulfur donors. These products are
6 readily obtained from the reaction of P2S5 and aliphatic
7 alcohols usefully having from about 8 to 22 carbons obtained
8 from natural sources including linoleic, behenic, stearic,
9 palmitic~ lauric, capric, etc.~ as well as mixtures obtained
from vegetable and animal oils, such as tall oil.
11 The sulfurized alkyl phenols are generally C4 to C20
12 alkyl phenol sulfides. These sulfurized alkyl ph~nols are
13 readily produced by sulfurizing an alkyl phenol with a sul-
14 fur halide or elemental sulfur.
15 OTHER ADD ITIVES FOR LUBRICAT~G COMPOS ITIONS
16 In addition to the molybdenum complex of the ash-
17 less dispersant and active sul~ur donor, the lubricating oil
18 composition may contain other well-known lubricating oil ad-
19 ditives to provide trouble-free operation of the lubricated
2G equipment, such as ashless dispersants, metallic detergents,
21 supplemental oxidation and corrosion inhibitors, extrem~
22 pressure agents, rust inhibitors, pour poin~ depressants,
23 viscosity index improvers, etc.
24 1. ASHLESS DISPERSANTS
As used herein, the terminology "ashless disper-
26 sant" in des~ribing both the reactant and the additive is in-
27 tended to describe ~he now well-known class of non-metal-
28 containing oil-soluble polymeric additives or the acyl
29 derivatives of relatively high molecular weight carboxylic
3G acids which are capable of dispersing contaminants and the
31 like in hydrocarbons such as lubricating oils. The carboxy-
32 lic acids may be mono- or polycarboxylic acids and they are
33 generally characterized by substantially hydrocarbon consti-
34 tuents containing an average of 50 to 250 aliphatic carbon
35 atoms-
36 A preferred class of ashless dispersants are the
11~5~35
- 16 -
1 nitrogen-containing dispersant additives which are generally
2 known in the art as sludge dispersants for crankcase motor
3 oils. These dispersants include mineral oil-soluble salts,
4 amides, imides and esters made from high lecular weight
no- and dicarboxylic acids (and where they exist the cor-
6 responding acid anhydrides) and various amines of nitrogen-
7 containing materials having amino nitrogen or heterocyclic
8 nitrogen and at least one amido or hydroxy group capable of
9 salt, amide, imide or ester formation. Usually, these dis-
persants are made by condensing a monocarboxylic acid or a
11 dicarboxylic acid or anhydride, preferably a succinic acid
12 producing material such as alkenyl succinic anhydride, with
13 an amine or alkylene polyamine. Usually, the molar ratio
14 of acid or anhydride to amine is between 1:1 to 5:1, e.g. 1
mole of C50-C10O polylsobutenyl succinic anhydride to 2
16 moles of tetraethylene pentamine.
17 Prim~rily because of its ready availability and low
18 cost, the hydrocarbon portion of the mono-, or dicarboxylic
19 acid or anhydride is preferably derived from a polymer of a
2C C2 to C5 monoolefin, said polymer generally ha~ing between
21 50 and 25G carbon atoms. A particularly preferred polymer
22 is polyisobutylene.
23 Polyalkyleneamines are usually used to make the
24 non-metal-containing dispersant. These polyalkyleneamines
include those represented by the general formula:
26 NH2(CH2)n [NH(CH2)n]m NH2
27 wherein n is 2 to 3 and m is a number from O to 10. Specific
28 compounds coming within the formula include diethylenetri-
29 amine, tetraethylenepentamine, dipropylenetriamine, octa-
ethylenenonamine, and tetrapropylenepentamine; N,N-di-(2-
31 aminoethyl) ethylenediamine may also be used. Other ali-
32 phatic polyamino compounds that may be used are N-amino-
33 alkylpiperazines, e.g. N-(2-aminoethyl) piperazine. Mix-
34 tures of alkylene polyamines approximating tetraethylene
pentamine are commercially available, e.g. Dow E-100 sold by
36 Dow Chemical Company of Midland, Michigan.
~ Je f1~rk
1~57~3
- 17 -
l Representati~e dispersants are formed by reacting
2 about one molar amount of polyisobutenyl succinic anhydride
3 with from about one to about two molar amounts of tetra-
4 ethyle~e pentamine or with from about 0.5 to l moles of a
polyol, e.g. pentaerythritol.
6 It is possible to modify the ashless dispersants
7 generally by the addition of metals such as boron in order
8 to enhance the dispersancy of the additive. This is readily
9 accomplished by adding boric acid to the reaction mixture
after the imidation or esterification is substantially com-
ll plete and heating the mixture at temperatures of 100 to 150C.
12 for a few hours.
13 2. OIHER ADDITIVES
14 Detergents useful in conjunction with dispersants,
preferably the ashless type, include normal, basic or over-
16 based metal~ e.g. calcium, magnesium, etc., salts of petro-
~ leum naphthenic acids, petroleum sulfonic ?cids, alkyl ben-
18 zene sulronic acids, oil-soluble fatty acids, alkyl sali-
l9 cyclic acids, alkylene-bis-phenols, and hydrolyzed phosphoro-
sulfurized polyolefins.
21 Oxidation inhibitors include hi~dered phenols, e.g.
22 2,6-ditert. butyl para-cresol, amines, sulfurized phenols and
23 alkyl phenothiazines.
24 Pour point depressants include wax alkylated aro-
matic hydrocarb~ns, olefin polymers and copolymers, acr~l-
26 ate and methacrylate polymers and copolymers.
27 Viscosity Index Impro~ers include olefin polymers
28 such as polybutene, ethylene-propylene copolymers, hydro-
2g genated polymers and copolymers and terpolymer of styrene
3G with isoprene and/or butadiene, polymers of alkyl acrylates
31 or alkyl methacrylates, copolymers of alkyi ~ethacrylates
32 with N-vinyl pyrollidone or dimethylaminoalkyl methacrylate~
33 post-grafted polymers of ethylene-propylene with an active
34 monomer such as maleic anhydride which may be further reacted
'5 with an alcohol or an alkylene polyamine, styrene/maleic an-
36 hydride polymers post-reacted with alcohols and amines, etc.
~57~5
- 18 -
1 The hydrocarbons in which the additive combination
2 ~f the invention is most effective are mineral oils having a
3 viscosity as measured by ASTM D-445 of from about 2 to 40,
4 preferably 5 to 20 centistokes at 99C.
If the molybdenum-containing acylated nitrogen
6 dispersant is used as an additive concentrate, the concen-
7 trate may consist essentially of from about 5 to 80 weight
& percent of molybdenum containing dispersant, based on the
9 total weight of said concentrate, the remainder being a
suitable solvent such as kerosene, miner~l oil, synthetic
11 oil and a naphtha or the like. Ihe preferred concentrate
12 contains about 10-60 weight percent of the additive combina-
13 tion in the solvent.
14 Whether the mwlybdenized acylated nitrogen disper-
sant is used alone or in combination with other additives,
16 its concentration may vary appreciably with the partlcular
17 application. For exa~ple, wh~n the said molybdenum contain-
18 ing dispersants are used alone in a fueL such as gasoline,
19 the co~centration of the additive ranges from 1 to 1000,
preferably 5-50 parts per million3 based on the total weight
21 of the gasoline. In a lubricant, however, it is used from
22 about 0.1 to 20 preferably 0.5-5% based on the total weight
23 of the oil.
24 The invention will be further understood by refer-
e~ce to the follswing Examplçs which illustrate a preferred
26 form of the invention and com~ares the same with different,
27 though similar compositions.
28 The following Examples illustrate more clearly the
29 compositions of the present invention. However, these il-
lustrations are not to be interpreted 25 specific l~mita-
31 tions on this inve~tion.
32 AMPLE 1
33 90.4 g of polyisobutenylsuccinic polyamine ashless
34 dispersant in 50% S150~ mineral oil (the polyisobutenyl sub-
stituent has a number average molecular weight (Mn) of 90C
36 and the dispersant contains 2.1% nitrogen) and 5.5 g of
~5735
- 19 -
1 molybdic acid, MoO3 H20, were refluxed 8 hours in 5CG ml of
2 tetrahydrofuran and 10 ml of H20. The temperature was 6C-
3 7GC. The tetrahydrofu an and excess water were then removed
4 using a rotoevaporator. It was Lhen redissolved in hexane
and filtered through celite. This was then evaporaced on the
6 rotary evaporator to remove the hexane. The resulcing green-
7 ish viscous material contained 3.49 wt./o molybdenum.
8 EXAMPLE 2
9 90.4 g of the polyisobutenyl succinic polyamine
ashless dispersant in 50% mineral oil (same additive as in
11 Ex. 1) and 13.0 g of molybdic acid, MoO3 H20, were refluxed
12 in 500 ml of ~XE and 10 ml of NH40H for 3 hours. The TXF was
13 re ved by a nitrogen sparge and the product diluted with
14 hexane and filtered. This was rotoevaporated to give a
clear, dark green viscous material containing 5.2 ~t.%
16 m~lybdenum.
17 EXAMp T E 3
18 A mixture of 80 g of a 50% mineral oil solution of
19 the dispersant product prepared from polyisobutenyl succinlc
anhydride (~ ~ 1000) and a polyethylene amine appro~imating
21 to tetraethylene pentamine in a charge molar ratio of 1.5:1
22 and 3.52 g ammonium heptamolybdate tetrahydrate in xylene
23 (50 cm3) and water (5 cm3) was refluxed with stirring for 5
24 hours. During this time, water and xylene were removed by
distillation. The reactants were freed from solid material
26 by filtration and the filtrate stripped of volatile material
27 by rotoevaporation. The product was a dark viscous oil con-
28 taining 2.1% molybdenum. This represents a conversion~ based
29 on lybdenum, of 91% on theory.
EXAMPLE 4
31 A mixture of the dispersant product solution of Ex.
32 3 (80 g), molybdic oxide (3.39 g), xylene (50 cm3) and water
33 (5 cm3) was refluxed with stirring for 3 hours. The product
34 was isolated by filtration and stripping to yield a dar~
brown oil with a molybdenum content of 2 6%. This repre-
36 sents a conversion of 95Z based on molybdenum.
~1~57~35
- 20 -
2 (a~ A mixture of the dispersant product solution of
3 Ex. 3 (80 g), molybdic oxide (4.24 g), xylene (50 cm3) and
4 water (5 cm3) was refluxed with stirring for 3 hours. The
product, isolated by filtration and stripping the filtrate
6 free from volatiles, was a dark brown oil with a molybdenum
7 content of 3.3970. This represents a quantitative conversion
8 based on molybdenum charged.
9 (b) Carrying out the same reaction, i.e. 5(a), for
2 hours rather than 3 yielded a dark brown oil containing
11 4.98% molybdenum.
12 ExA~T F 6
13 A mixture of a 50 wt.% mineral oil solution of a
14 dispersant obtained from the reaction of polyisobutenyl suc-
cinic anhydride with tetrae~hylene pentamine (40 g),molybdic
1~ oxide (2.44 g), xylene (50 cm3) and water (5 cm3) were re-
17 fluxed with stirring for 6.5 hours. The product was isolated
18 in the same manner as previous Examples 3-5 to yield a dark
19 brown o~l containing 3.72% molybdenum.
FXAMpLE 7
.
21 40 g of the dispersant solution used and described
22 1~ Ex. 6, ammonium heptamolybdate tetrahydrate (2.96 g),
23 xylene (50 cm3) and water (5 cm3) was refluxed with stirring
24 for 7.25 hours. The product, isolated in the usual manner,
was a dark brown oil containing 3.72% molybdenum (97% con-
26 version based on lybdenum).
27 AMPLE 8
28 A mixture of a 50 wt.% mineral solution of a
29 borated dispers~nt derived from the condensation of 1.5
3G les of polyisobutenyl succinic anhydride to 1 mole of tetra-
31 ethylene pentamine and containing 0.35% boron (80 g), molyb-
32 dic oxlde ~4.18 g), xyler~e (50 cm3~ and water ~5 cm3) was
33 stirred at reflux for 6.75 hours. The product, isolated in
34 the nonmal manner, was a dark green oil con~aining 3.0%
molybdenum (90% conversion based on molybdenum).
~573S
- 21 -
LE 9
2 80 g of a borated condensation product of polyiso-
3 butenyl succinic anhydride and an alkylene polyamine dis-
4 solved in 50 wt.% mineral oil,
6 molybdic oxide (3 g), xylene (50 cm3) and water (5 cm3) were
7 stirred at reflux for 6 hours. m e product, a dark green
8 oil, isolated in the normal manner, contained 3~62% molyb-
9 denum (8270 conversion based on molybdenum).
10 EXA~IE 10
11 Some of these molybdated dispersants were evalua-
12 ted, in a formulated oil, for their effect on friction in a
13 Ro~ana Four-Ball Tester. As a comparative example, in each
14 case, an oil containing the dispersant but without molyb-
denum was run. The concentration of the molybdenum-contaln-
16 ing dispersant was adjusted to provide 0.1% molybdenum in the
17 oil. A total dispersant concentration of 2.570 was maintained
13 in all tests.
19 The lubricant composition was:
~ Wt% Active Ingredient
21 Dispersant 2.5
22 Magnesium Sulfonate 0.4
23 (overbased)
24 Zinc dialkyl 1. 0
dithiophosphate
26 M~neral oil 96.1
27 The Roxana Four-ball wear tester with the Brown/GE
28 modification from Roxana Machine Works, St. Louis, MO was
29 used to measure friction properties by the following pro-
cedure. The tester was assembled in the normal wear pro-
31 cedure as described in ASTM D2266-67 using four ~" bearing
32 steel ba~ls. The tester was brought to 110C. and run at
33 1200 rpm and 15 kg for a minimum of 45 minutes. If the
34 frictional force as seen on the strip chart recorder is con-
stant for the last 10 minutes, the speed is reduced to 25
36 rpm. Otherwise, the test is carried on until frictional
11i~57;~S
- 22 -
1 force has stabilized. The test at 25 rpm is carried out at
2 110C. and lS kg for 15 minutes or until frictional force
3 has stabilized.
4 The compounds of the invention were then evaluated
by subjecting the products to a study of their utility as a
6 lubricity enhancing ant/or antiwear additive for lubricating
7 oils by using said Testing Procedure; the results are shown
8 in the following Table. It will be seen ~hat the molyb-
9 denum-containing dispersants of the inven~ion provide
lubricity enhancement to lubricating oils superior to their
11 non-molybdized counterparts when an active sulfur donor is
12 present.
- 23 ~ 5735
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