Note: Descriptions are shown in the official language in which they were submitted.
BAC~CGROUMD OF THE INVE~ITIO~I
2 This invention relates to a storage stable lu-
3 bricating oil composition having particularly improved
4 anti-friction properties.
There has been considerable effort in recent
6 years to develop lubricating oil compositions which will
7 reduce friction in engines and particularly automotive
8 engines. This effort is based on the need to improve the
9 fuel economy of such engines which operate on petroleum
fuel, a product having a declining source of supply and
11 an escalating price. It is known that high engine fric-
12 tion causes significant energy loss and thus one way to
13 improve fuel economy is to reduce such friction.
14 Xnown ways to solve the problem of energy losses
due to high friction e.g., in crackcase motor oils in-
16 clude the use of synthetic ester base oils which are ex- -
17 pensive and ~the use of insoluble molybdenum sulfides
18 which have the disadvantage of giving the oil composition
19 a black or hazy appearance.
Another approach to reduce energy losses by the
21 use of a lubricating oil composition involves a composi-
22 ticn containing an additive combination of an oil soluble
23 friction reducing ester component derived from esterifi-
24 cation of a polycarboxylic acid wi'h a glycol and a zinc
dihydrocarbyl dithiophosphate. This type of composition
26 is disclosed in U.S. Patent 4,105,571 which notes that
27 while a lubricating composition containing the additive
28 package of such ester and zinc thiophosphate components
29 provides excellent anti-friction and anti-wear properties,
it presents compatability and stability problems. The
31 problem is solved by adding a selected ashless dispersant
32 containing a high molecular weight aliphatic hydrocarbon
33 oil solubilizing group attached thereto to the composi-
34 tion, and preferably predispersing either the ester and/
or zinc thiophosphate components prior to their addition
~._.
- 2 _
1 to the remainder of the composition. Such ashless dis-
2 persants may contain hydroxyl groups as noted in tne
3 patent.
4 r~rnile the above approaches all provide reduced
engine friction and consequently improved fuel economy,
6 there is always the need and desire for further reductions
7 in energy losses due to friction or otherwise since even
8 small reductions per engine can result in a rather large
9- savings in fuel, particularly when considering the total
number of engines in use.
11 SU~ RY OF THE INV~NTIOM
_ .
12 It has now surprisingly been discovered that
13 lubricating oil compositions containing an additive combi-
14 nation of an ester of a polycarboxylic acid and a glycol
or glycerol plus zinc dihydrocarbyl dithiophosphate can
be made storage stable and have particularly improved
17 friction reducing properties when an ashless dispersant
18 containing a selected amount of free hydroxyl is used.
19 ~ore particularly a storage stable lubricating oil compo-
sition with improved friction reducing properties is
21 provided by the composition of this invention which in-
22 cludes an additive combination of (1) an ester of a
3 polycarboxylic acid with a glycol or glycerol, (2) a
24 zinc dihvdrocarbyl dithiophosphate and (3) an ashless
dispersant containing a high molecular weight aliphatic
26 hydrocarbon oil solubilizing group attached thereto and
27. a selected amount of free hydroxyl groups.
28 In accordance with the present invention a
29 storage stable lubricating oil composition with improved
friction reducing properties is provided by a composition
31 comprising a major portion of lubricating oil, from about
32 0.01 to 1.0 parts by weight of an es.er of a polycarboxylic
33 acid with a glycol or glycerol, from about 0.01 to about
34 5.0 parts by weight of zinc dihydrocarbyl dithiophosphate
and from about 0.1 to about 20 parts by weight of an
36 hydroxyl containing ashless dispersant having a high
molecular weight aliphatic hydrocarbon oil solubilizing group
attached thereto, said dispersant containing from about 0.35 to
about 1.8 millimoles (mM) of free hydroxyl per gram of dispersant,
all weights based on 100 parts by weight of said lubricating oil
composition.
In another aspect, the invention provides a method of re-
ducing friction in an internal combustion engine comprising lubri-
cating the engine using a lubricating oil composition as just
described.
DETAILED DESCRIPTION OF THE INVENTION
As previously indicated the present invention relates to a
storage stable lubricating oil composition having particularly im-
proved friction reducing properties comprising an additive combina-
tion of an ester of a polycarboxylic acid and a glycol or glycerol,
zinc dihydrocarbyl dithiophosphate and an ashless dispersant con-
taining a selected amount of free hydroxyl groups.
The oil soluble friction reducing ester component used in
the composition of this invention generally, can be any hdyroxy
substituted oil soluble ester of a polycarboxylic acid.
Best results are, however, obtained when such compounds are
derived from the esterification of a polycarboxylic acid with a
glycol or glycerol, preferably glycol. Such an ester may be a par-
tial, di- or polyester with typical formulas of the ester repre-
sented by the following general formulas when using a glycol:
(1) HO-R-OOC-R"-COOH
(2) HO-R-OOC-R"-COOR'-OH
(3) HO-R-OOC-R"-COOR-OOC-R"-COOR'-OH
wherein R" is the hydrocarbon radical of said acid and each R and
R' may be the same or different hydrocarbon radicals associated
with a glycol or diol as hereinafter defined. It will, of course,
be appreciated that esters of the type illustrated by the fore-
going formulas can be obtained by esterifying a polycarboxyli.c
acid, or a mix-ture of such acids, with a diol or mixture of such
diols.
The polycarboxylic acid used in preparing the ester may
be an aliphatic saturated or unsaturated acid
- 3a -
1 and will generally have a total of about 24 to about 90,
2 pref2rably about 24 to about 60 carbon atoms and about 2
3 to about 4, re~erably about 2 to about 3 and more pref-
4 erably about 2 carboxyiic acid groups witn at least about
9 up to about 42 carbon atoms, preferably about 12 to
6 about 42 and more preferably about 16 to about 22 carbon
7 atoms between the carboxylic acid groups.
8 The oil insoluble glycol which is reacted with
9 the polycarboxylic acid may be an alkane diol, i.e.
alkylene glycol or an oxa-alkane diol, i.e. polyalkylene
11 glycol, straight chain or branched. The alkane diol may
12 have from about 2 to about 12 carbon atoms and preferably
13 about 2 to about 5 car~on atoms in the molecule and the
14- oxa-alkane diol will, generally, have from about 4 to
about 200, preferably about 4 to about 100 carbon atoms.
16 The oxa-alkane diol (polyal]sylene glycol) will, of course,
17 contain periodically repeating groups of the formula:
18 _ _
19 HO- -C - C- -O H
H H
21 x
22 wherein R may be H, CH3, C2H5 or C3H7, and x is 2 to 100,
23 preferably 2 to 25. The preferr2d alkane diol or alkylene
24 glycol is ethylene glycol and the preferred oxa-alkane
diol or polyalkylene glycol is diethylene glycol. As
26 indicated previously, glycerol may also be used in pre-
27 paring the ester of polycarboxylic acid and it is con-
28 templated that such component will also include its higher29 molecular weight analogues.
~rnile any of the esters as set forth above can
31 be effectively used, best results are, however, obtained
32 wit'n such compounds wherein the carboxyl groups of tne
33 polycarboxylic acid are separated from each other by from
34 about 16 to aoout 22 carbon atoms and wllerein the hydroxy
groups are separated from the closest carboxyl group by
36 from about 2 to about 12 carbon atoms. Particularly
1 desirable results have been obtained with additives pre-
2 ~ared by esterifying a dimer of a fatty acid particularly
3 those containing conjugated unsaturation with a poly-
4 hydroxy compound. Such dimers are, of course, clearly
taught in U.S. Patent 3,180,832 which was granted on
6 April 27, 1965 and U.S. Patent 3,429,817 which was granted
7 on February 25, 1969, and as there indicated, the hydro-
8 carbon portion of the dimer or dicarboxylic acid thus
9 obtained may contain a six member ring. ~he formation of
the dimer from linoleic acid, oleic acid and mixtures of
11 these acids is illustrated by the following:
12 A. CH3(cH2)4cH=cHcH2cH=cH(cH2)7coo~ ~ 30005
13 9, 12 Linoleic ~cid
14 2 molecules
CH3(CH2)5CH=CHCH=CH(CH2)7COOH 9-11 acid
16 3iels-Alder
17 9,11 Linoleic Acid A
18( 2~7 ~ (CH2)5CH3
19;~OOC(CH2) ~ ~CH2)5CH3
20Linoleic Acid Dimer (dilinoleic acid)
212 mole~ules
23 3 2 72 7 Diels Alder
24 Oleic Acid ~
CH3(CH2)7CH 5~(Cil2)7
26 CH3(CH~)7CH2CH(CH2)7COOH
27 Oleic Acid Dimer (Dioleic Acid)
28 C. 9,11 Linoleic Acid + Olei~ Acid
29 CH3(CH2)6CHCH=CH(cH2)7cooH
CH3(cH2)4cHcH=cHcH=cH(cH2)7cooH
31 ~i~ed Dimer
32 It will, of course, be appreciated that while the reac-
33 tions illustrated produce the dimers, commercial applica-
34 tion of the reactions will, generally, lead to trimer
1 formation and in some cases the pxoduct thus obtained will
2 contain minor amounts of unreacted monomer or monomers.
3 As a result, commercially available dimer acids may con-
4 tain as much as 25% trimer and the use of such mixtures
is within the scope of the present invention.
6 The preferred hydroxy-substituted ester lubri-
7 city additives useful in the present invention will be
3 the reaction product of a dimerized fatty acid, such as
9 those illustrated, and an oil insoluble glycol and may
be produced by various techniques. As praviously pointed
11 out, the preferred acid dimers are the dimers of linoleic
12 acid, oleic acid or the mixed dimer of linoleic and oleic
13 acids, which may also contain some monomer as well as
14 trimer. Other specifically satisfactory glycols in addi-
lS tion to ethylene glycol and polyethylene glycol are, for
16 example, propylene glycol, polypropylene glycol, butylene
17 glycol, polybutylene glycol and the like.
18 The zinc dihydrocarbyl dithiophosphates useful
19 in the present invention are salts of dihydrocarbyl esters
of dithiophosphoric acids and may be represented by the
21 following formula: _ _
22 S
23
24 RO - P - S Zn
26 OR' 2
27 wherein R and R' may be the same or different hydrocarbyl
28 radicals containing from 1 to 18 and preferably 2 to 12
29 carbon atoms and including radicals such as alkyl, alkenyl,
aryl, aralkyl, alkaryl and cycloaliphatic radicals. Par-
31 ticularly preferred as R and R' groups are alkyl groups of
32 2 to 8 carbon atoms. Thus, the radicals may, for example,
33 be ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl,
34 tert-butyl, amyl, n-hexyl, i-hexyl, n-heptyl, n-octyl,
decyl, dodecyl, octadecyl, 2-ethylhexyl, phenyl, butyl-
36 phenyl, cyclohexyl, methylcyclopentyl, propenyl, butenyl,
c~
1 etc. In order to obtain oil solubility, the total number
2 of carbon atoms in the dithiophosphoric acid will average
3 about S or greater.
4 The zinc dihydrocarbyl dlthiophosphates which
are useful in the compositions of the present invention
6 may be prepared in accordance ~ith known techniques by
7 first esterifying a dithiophosphoric acid usually by
8 reaction of an alcohol or phenol with P2S5 and then neu-
9 tralizing the dithiophosphoric acid ester with a suitable
zinc compound such as zinc oxide. In general, the alcohol
11 or mixtures of alcohols containing from 1 to 13 carbon
12 atoms may be used to effect the esterification. The
13 hydrocarbon portion of the alcohol may, for example, be
14 a straight or branched chain alkyl or al~enyl group, or
a cycloaliphatic or aromatic group. ~mong the alcohols
which are generally preferred for use as starting mate-
17 rials in the preparation of the esters may be mentioned
18 ethyl, isopropyl, amyl, 2-ethylhexyl, lauryl, stearyl and
19 methyl cyclohexyl alcohols as well as commercial mixtures
o~ alcohols, such as the mixture of alcohols derived from
21 coconut oil and known as "Lorol B" alcohol, which mixture
22 consists essentially of alcohols in the C10 to C18 range.
23 Other natural products containing alcohols such as the
24 alcohols derived from wool fat, natural waxes and the li~e
may be used. ;qoreover, alcohols produced by the oxidation
26 of petroleum hydrocarbon products as well as the Oxo-
27 alcohols produced from olefins, carbon monoxide and
28 hydrogen may be employed. Further aromatic compounds such
29 as alkylated phenols of the type n-butyl phenol, tertiary-
amyl phenol, diamyl phenol, tertiary octyl phenol, cetyl
31 phenol, petroleum phenol and the like as well as the
32 corresponding naphthols may be employed in like manner.
33 Following the esterification, the diester is
34 then neutralized with a suitable basic zinc compound or
a mixture of such compounds. In general, any compound
36 could be used but the oxides, hydroxides and carbonates
- 8
1 are most generally employed.
2 Generally, any lubricating oil ashless disper-
3 sant containing a high ~olecular weight aliphatic hydro-
4 carbon oil solubilizing group attached thereto and the
selected amount of free hydroxyl groups can be used in
6 the composition of this invention. More particularly,
7 said dispersant will contain from a~out 0.35 to about 1.8
8 millimoles of free hydroxyl per gram of dispersant, pref-
9 erably from about 0.5 to about 1.5 and more preferably
about 0.7 to about 1.3 millimoles of free hydroxyl per
11 gram of dispersant. In referring to dispersant in the
12 context of free hydroxyl groups, the gram weight is of
13 active dispersant, i.e. it does not include the carrier
14 or lubricating oil in which the dispersant is diluted or
otherwise dispersed.
16 The significance of the hydroxyl content in the
17 dispersant is the essential feature of this invention
18 since it has surprisingly been found that controlling
19 hydroxyl content per gram of active dispersant results in
significantly lower engine friction. Additionally, there
21 is a minimum amount of hydroxyl content which must be
22 maintained in the dispersant in order to retain composi-
23 tion stability. Accordingly, it is essential that the
24 dispersant contain a selected amount of free hydroxyl
content as described herein to provide a lubricating
26 composition with improved friction reducing properties
27 while retaining its stability.
28 A variety of compounds may be used as the ash-
29 less dispersant in the composition of this invention
provided they have a suitable high molecular weight ali-
31 phatic hydrocarbon oil solubilizing group attached thereto
32 and most important a selected amount of free hydroxyl
33 groups. 3ispersant compounds of this type include esters
34 of mono and polycarboxylic acids witll polyhydric alcohols,
p~enols and naphthols as well as nitrogen containing
36 compounds containing the necessary hydroxyl content as
- 9 -
l previously noted. It is contemplated that mixtures and
2 a wlde variety of compounds may be utilized as the ash-
3 less dispersant or ashless dispersant system in this in-
4 vention provided the necessary functionality is available,
S particularly the selected amount of free hydroxyl content.
6 Thus, the ashless dispersant of this invention may comprise
7 a mixture of a hydroxylated and non-hydroxylated compound
8 provided the necessary functionality as defined herein is
9 satisfied. Accordingly, the term ashless dispersant as
used throughout this application is intended to include
ll such mixtures and combination of compounds thereof.
12 The different dispersants which can be used in
13 this invention are characterized by a long chain hydro-
14 carbon group or groups, which may be attached, e.g. to
the acid, so the acid contains a total of about 50 to
16 about 400 carbon atoms, said acid being attached, e.g.
17 to an amine and/or ester group or both.
18 Ester containing ashless dispersants of this19 invention can be derived from polyhydric aliphatic
alcohols or polyhydric aromatic hydroxyl containing com-
21 pounds such as phenols and naphthols. The polyhydric
22 alcohols and aromatic compounds used will preferably
23 contain from 2 to about 10 nydroxy radicals and are
24 illustrated by ethylene glycol, diethylene glycol, tri-
25 ethylene glycol, tetraethylene glycol, dipropylene glycol,
2~ tripropylene glycol, dibutylene glycol, tributylene
27 glycol, and other alkylene glycols in which the alkylene
28 radicals contain from about 2 to about 8 carbon atoms.
29 Also, resorcinol, catechol, p,p'-dihydroxybiphenyl,
4,4'-methylene bis-phenol, di (nydroxyphenyl) oxide,
31 and di (hydroxyphenyl) sulfide. Other useful polyhy-7ric
32 compounds include glycerol, mono-oleate of glycerol,
33 pentaerythritol, trimethylol propane, 9,10-dihydroxy-
34 stearic acid, 1,2-butanediol, 2,3-hexanediol, 2,4 hexane-
35 diol, ?inacol, erythritol, arabitol, sorbitol, mannitol,
36 and 1,2-cyclohexanediol. Carbohydrates such as sugars,
37 starches, cellulose, etc., likewise may yield appropriate
3'~
-- 10 --
1 esters as exempllfied by flucose, fructose, sucrose,
2 rhamnose, mannose, glyceraldehyde, and galactose.
3 An especially preferred class of polyhydric
4 alcohols are those having at least three hydroxy radicals,
5 some o~ which have been esterified with a monocarboxylic
6 acid having from about 8 to about 30 carbon atoms such as
7 octanoic acid, oleic acid, stearic acid, linoleic acid,
~ dodecanoic acid or tall oil acid. Examples of such
g partially esterified polyhydric alcohols are the mono-
10 oleate of glycerol, monosterate of glycerol, di-dodecanote
11 of erythritol.
12 T~e ester dispersant of this invention may also
13 be derived from unsaturated alcohols, ether-alcohols, and
14 amino alcohols including for example: oxy-alkylene,
lS oxy-arylene, amino-alkylene, and amino-arylene substituted
16 alcohols. Such compounds include di (hydroxyethyl~ amine,
17 tri (hydroxypropyl) amine, N,~,~FN-tetrahydroxytrimethyl-
18 enediamine, 2-amino-2-methyl-1,3 propanediol, 2-amino-2-
19 ethyl-1,3-oropanediol, tris (hydroxymethyl) amino-methane,
20 etc.
21 As indicated earlier, the particular dispersants
22 used in this invention contain a long chain hydrocarbon
23 group which will generally have about 50 to about 400
24 carbon atoms and oreferably will be derived from an alkenyl
succinic acid/anhydride where the alkenyl radical will
26 have a molecular weight of at least about 900 and pref-
27 erably at least about 1200 and more preferably at least
28 about 1300.
29 A large number of dispersants having the above
identified characteristics can be used in this invention
31 some of which are disclosed in U.S. Patents 4,105,571;
32 3,542,678; 3,522,179; 3,542,680i 3,632,511; and 3,804,763.
33 Methods for preparing such dispersants are generally well
34 known and are also disclosed in the noted patents. Some
particularly preferred dispersant combinations include
36 1) a combination of a polyisobutenyl succinic anhydride,
37 a hydroxy compound e.g. pentaerythritol and a polyoxy-
1 alkylene ~olyamine e.g. ~olyoxypropylenediamine and a
2 2olyalkylene ~ol~amine e.g. polyet!lylenediamine and
3 .etraet'lylene pentamine and ~) a combination of polyiso-
4 butenyl succinic anhydride, polyal~ylene polyamine e.g.,
tetraethylene 2entamine and a polyhydric alcohol or poly-
6 hydroxy-substituted aliphatic pri~ary amine e.g. ~enta-
7 erythritol or trismethylolaminomethane.
8 In general, the zinc dihydrocarbyl dithiophos-
9 phate will be used in the lubricating composition at a
10 concentration within the range of about 0.01 to about 5
11 parts by weight per 100 parts of lubricating oil composi-
12 tion and preferably from about 0.5 to about 1.5. The
13 polycarboxylic acid/glycol or glycerol ester will be used
14 at a concentration of about 0.01 to about 2.0, preferably
15 about 0.05 to about 1.0 and more preferably 0.05 to 0.5
16 parts by weight per 100 parts of lubricating oil composi-
17 tion and the ashless dispersant will be employed at a
18 concentration of about 0.1 to about 20 and preferably
19 about 0.5 to about 10 parts by weight per 100 parts of
20 lubricating oil composition.
21 The lubricating oil liquid hydrocarbons which
22 may be used include the mineral lubricating oils and the
23 synthetic lubricating oils and mixtures thereof. The
24 synthetic oils will include diester oils such as di
(2-ethylhexyl) sebacate, azelate and adipate; complex
26 ester oils such as those formed from dicarboxylic acids,
27 glycols and either monobasic acids or monohydric alcohols;
23 silicone oils; sulfide esters; organic carbonates; and
29 other synthetic oils known to the art.
Other additives, of course, may be added to t,he
31 oil compositions of the ~resent invention to form a
32 finisned oil. Such additives may be the conventionally
33 used additives including oxidation inhibitors such as
34 phenothiazine or phenyl C7~naphthylamine; rust inhibitors
35 such as lecithin or sorbitan monoleate; detergents such
36 as barium phenates; pour point depressants such as co-
~olymers of vinyl ace~ate with fumaric acid esters of
- 12 -
1 ~oconut oil alcoholsi viscosity index improvers such as
2 ole~in co?olymers, pol~methacrylates; etc. I~ particularly
3 useful additive i5 the basic alkaline earth metal salts
~ of an organic sulfonic acid, generally a ~etroleum
sulfonic acid or a synthetically prepared alkaryl sulfonic
6 acid. Among the ~etroleum sulfonates, the most useful
7 products are those prepared by the sulfonation of suitable
8 petroleum fractions with subsequent removal of acid sludge
g and purification. Synthetic alkaryl sulfonic acids are
usually prepared from alkylated benzenes such as the
11 Friedel-Crafts reaction product of benzene and a polymer
12 such as tetrapropylene. Suitable acids may also be
13 obtained by sulfonation of alkylated derivatives of such
14 compounds as diphenylene oxide thianthrene, phenolthioxine,
diphenylene sulfide, phenothiazine, diphenyl oxide, di-
16 phenyl sulfide, diphenylamine, cyclohexane, decahydro
17 naphthalene and tlle like.
18 Basic alkaline earth metal sulfonates are gener-
19 ally prepared by reacting an alkaline earth metal base,
e.g. lime, magnesium oxide, magnesium alcoholate with CO2
21 in the presence of sulfonic acid or neutral metal sulfo-
22 nates, ordinarily the calcium, Magnesium or barium salts.
23 These neutral salts in turn may be prepared from the free
24 acids by reaction with the suitable alkaline earth metal
base, or by double decomposition of an alkali metal
26 sulfonate, which methods are well known in the art.
27 Further details are described in U.S. Patent No. 3,562,159.
28 The composition of this invention is particularly
29 useful when metal containing additives such as the normal
and basic metal phenates, sulfonates or sulfurized
31 phenates are used since such components have been known
32 to cause compatability problems in more conventional type
33 lubricant compositions.
34 The above described additive package may be used
in conventional base oils with other conventional addi-
36 tives. While tlle components can generallv be added in
37 their normal and conventional manner, it is a preferred
-- 13 --
1 2~L,odimer.t of t:nis invention to .~eep ~he zinc dihydrocarbyl
2 ~ aiophosphate and polycarboxylic acid/glycol or glycerol
3 ester components apart from one another until at least
4 one of SUCL1 components has been predis?ersed as described
5 in U.S. 4,105,571. This will help to maintain a storage
6 stable and compatible composition. By predispersed it
7 is meant that the ester component or the zinc component
8 or both separately are mixed with the ashless dispersant,
9 which may be in oil solution, until the solution is
lO generally clear.
ll The following examples are further illustrative
12 of this invention and are not intended to be construed as
13 limitations thereof.
14 E~A~lPLE 1
Formulations were prepared using a lOW-40SE
16 quality automotive engine oil containing 1.5% by weight,
17 based on the total lubric~ting oil weight, of zinc dialkyl
18 dithiophosphate (80% active ingredient in diluent mineral
19 oil) in which the al]~yl groups were a mixture of such
20 groups having ~etween 4 and 5 carbon atoms and made by
21 reacting P2S5 with a mixture of about 65% isobutyl alco-
22 l~ol and 35% of amyl alcohol; 0.1% by weight, based on the
23 total lubricating oil weight of an ester formed by esteri-
24 fication of a dimer acid of linoleic acid and diethylene
25 glycol and having the formula:
2276 HocH2cE~2ociH2cH2oc (CH2)7CH=CH (CH2)5CH3
29 H0CH2CH20cH2cH20~l(cH2)7 ~ (CH2)5CH3
This additive is actually a mixture of the
31 structure shown plus ~igher molecular weight repeating
32 units (polymers) of this material.
33 Dispersants containing different amounts of free
34 hydroxyl contents were used in the different lubricating
formulations as described ~elow:
3~
- 14 -
1 A) 5.25% by wt. of dispersant (mixture of 46.5%
2 by weignt active ingredient in mineral lubricating oil)
3 was used, said dispersant prepared by reacting polyiso-
4 butenyl succinic anhydride (pIssA)~ the polyisobutenyl
radical (PIB) having an average molecular weight (.`~n) of
6 about 900 with an equal molar amount of pentaerythritol
7 and a minor amount of a polyamine mixture comprising
8 polyoxypropylene amine and polyethylene amines to form a
9 a product having a nitrogen content of about 0.35% by
weight and having a millimole (m.~) hydroxyl per gram of
11 active ingredient of 2.00. ~aterials of this type are
12 described in U.S. Patent 3,804,763 and sold by Lubrizol
13 Corporation under the tradename ~ubrizol 6431;
14 B) A dispersant similar to A described above
but having about 75~ of the pentaerythritol added was
16 prepared and llad a nitrogen content of 0.27% and 1.55 m~
17 of hydroxyl per gram of active ingredient;
18 C) ~nother dispersant similar to A described
19 above but using about 50% of the pentaerythritol was pre-
pared and had a nitrogen content of 0.44~ and 1.25 m,~ of
21 hydroxyl per gram of active ingredient;
22 3) Another dispersant similar to A described
23 above was prepared using 10% of pentaerythritol and had
24 a nitrogen content of 1.05% and 0.75 ~`~ of hydroxyl per
gram of active ingredient.
26 The dispersants noted above were added to the
27 lOW-40SE crankcase oil along with the other additives and
28 a rust inhibitor, i.e. overbased magnesium sulfonate, a
29 detergent and a VI improver, i.e. an ethylene-propylene
copolymer.
31 The above noted compositions all exhibited
32 storage stability and compatibility over an extended period
33 and were further tested for relative friction using a ball
34 on cylinder test.
The apparatus used in the ball on cylinder test
36 is described in the Journal of the American Society of
-- 15 --
1 Lubrication Engineers, entitled i'ASLE Transactions",
2 Vol. 4 pages 1-11, 1961. In essence, the apparatus con-
3 sists basically of a fixed metal ball loaded against a
4 rotating cylinder. The weight on the ball and the rota-
tion of the cylinder can be varied during any given test
6 or from test to test. Also, the time of any given test
7 can be varied. Generally, however, steel on steel is
8 used at a constant load, a constant rpm and a fi~ed time
9 and in each of the tests of this example, a 4Xg load,
0.26 rpm and 70 minutes was used. The actual friction was
11 determined from the power actually required to effect
12 rotation and the relative friction determined by ratioing
13 the actual load to that of a standard. The apparatus and
14 method used is more fully described in U.S. Patent No.
3,129,580 which was issued ~ay 21, 1964 to Furey et al
16 and which is entitled "Apparatus for ~leasuring Friction
17 and Contacts Between Sliding Lubricating Surfaces".
1~ The results of ball on cylinder test are given
19 below:
~ OH per gram Coeff of Frict.
21Composition of Active Dispersant @70 ~lin.
22 A 2.0 .135
23 B 1.55 .095
24 C 1.25 .~75
D 0.75 .055
26 ~hile noting in the above composition that the
27 amount of friction was significantly reduced by decreasing
28 the hydroxyl content, it was ascertained that a level of
29 about 0.35 mM OE/gram of active dispersant was needed to
have a compatible system. Thus, the surprising friction
31 effects of using the composition of this invention where-
32 in a dispersant having selected hydroxyl content is used
33 is readily shown by the results.
