U.S. patent application number 11/743377 was filed with the patent office on 2008-01-31 for lubricating oil composition.
Invention is credited to David Charles Nelson, Mark Clift Southby.
Application Number | 20080026973 11/743377 |
Document ID | / |
Family ID | 37026986 |
Filed Date | 2008-01-31 |
United States Patent
Application |
20080026973 |
Kind Code |
A1 |
Nelson; David Charles ; et
al. |
January 31, 2008 |
LUBRICATING OIL COMPOSITION
Abstract
A method of reducing deposits in an internal combustion engine,
comprising lubricating the internal combustion engine with a
lubricating oil composition comprising lubricating oil base oil,
one or more anti-wear additives and one or more
poly(hydroxycarboxylic acid) amide salt derivatives preparable by
reaction of an amine and a poly(hydroxycarboxylic acid) of formula
(I) Y--CO[O-A-CO].sub.n--OH (I) where Y is hydrogen or optionally
substituted hydrocarbyl group, A is a divalent optionally
substituted hydrocarbyl group and n is from 1 to 100, with an acid
or a quaternizing agent.
Inventors: |
Nelson; David Charles;
(Chester, GB) ; Southby; Mark Clift; (Chester,
GB) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
37026986 |
Appl. No.: |
11/743377 |
Filed: |
May 2, 2007 |
Current U.S.
Class: |
508/547 ;
508/551 |
Current CPC
Class: |
C10M 163/00 20130101;
C10N 2030/04 20130101; C10M 161/00 20130101; C10N 2040/25 20130101;
C10M 2217/041 20130101; C10M 141/10 20130101; C10M 2215/08
20130101; C10M 141/06 20130101; C10M 2223/045 20130101 |
Class at
Publication: |
508/547 ;
508/551 |
International
Class: |
C10L 1/22 20060101
C10L001/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 3, 2006 |
EM |
06252350.1 |
Claims
1. A method of reducing deposits in an internal combustion engine,
comprising: lubricating the internal combustion engine with a
lubricating oil composition comprising lubricating oil base oil, at
least one anti-wear additive, and at least one
poly(hydroxycarboxylic acid) amide salt derivative preparable by
reaction of an amine and a poly(hydroxycarboxylic acid) of formula
(I) Y--CO[O-A-CO].sub.n--OH (I) where Y is hydrogen or optionally
substituted hydrocarbyl group, A is a divalent optionally
substituted hydrocarbyl group and n is from 1 to 100, with an acid
or a quaternizing agent.
2. The method according to claim 1 wherein the
poly(hydroxycarboxylic acid) amide salt derivatives comprises a
compound of formula (III) [Y--CO[O-A-CO].sub.n-Z-R.sup.+].sub.m
pX.sup.q- (III) wherein Y is hydrogen or optionally substituted
hydrocarbyl group, A is a divalent optionally substituted
hydrocarbyl group, n is from 1 to 100, m is from 1 to 4, q is from
1 to 4 and p is an integer such that pq=m, Z is an optionally
substituted divalent bridging group which is attached to the
carbonyl group through a nitrogen atom, R.sup.+ is an ammonium
group and X.sup.q- is an anion.
3. The method according to claim 2 wherein R.sup.+ is a quaternary
ammonium group.
4. The method according to claim 2 wherein A is selected from the
group consisting of arylene, alkylene, and alkenylene groups.
5. The method according to claim 2 wherein there are between 4 and
14 carbon atoms connected between the carbonyl group and the oxygen
atom derived from the hydroxyl group.
6. The method according to claim 2 wherein A includes at least one
substituent selected from the group consisting of hydroxy, halo,
and alkoxy groups.
7. The method according to claim 2 wherein X.sup.q- is selected
from the group consisting of sulfate and sulfonate anions.
8. The method according to claim 1 wherein Y contains up to 50
carbon atoms and is selected from the group consisting of aryl,
alkyl, and alkenyl groups and combinations thereof.
9. The method according to claim 1 wherein Y is selected from the
group consisting of heptyl, octyl, undecyl, lauryl, heptadecyl,
heptadenyl, heptadecadienyl, stearyl, oleyl, and linoleyl groups,
and combinations thereof.
10. The method according to claim 1 wherein Y comprises a moiety
selected from the group consisting of C.sub.4-8 cycloalkyls,
polycycloalkyls, aryls, aralkyls, polyaryls, and combinations
thereof.
11. The method according to claim 1 wherein the
poly(hydroxycarboxylic acid) is selected from the group consisting
of poly(hydroxystearic acid) and poly(hydroxyoleic acid).
12. The method according to claim 1 wherein the amine is a diamine
selected from the group consisting of ethylenediamine and
N,N-dimethyl-1,3-propanediamine.
13. The method according to claim 1 wherein the
poly(hydroxycarboxylic acid) amide salt derivative contains
sulfur.
14. The method according to claim 1, further including providing
said at least one poly(hydroxycarboxylic acid) amide salt
derivative in an amount in the range of from 0.1 to 10.0 wt. %,
based on the total weight of the lubricating oil composition.
15. The method according to claim 1 wherein said lubricating oil
composition further comprises at least one detergent selected from
the group consisting of alkali metal or alkaline earth metal
salicylate, phenate, and sulfonate detergents, and combinations
thereof.
Description
RELATED CASES
[0001] The present application claims priority from EPC application
06252350.1, filed May 3, 2006, which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a lubricating oil
composition for particular use in internal combustion engines.
BACKGROUND OF THE INVENTION
[0003] It will be appreciated that the same lubricating oils are
not always used by consumers as internal combustion engine oils in
their vehicles. As different lubricating oil compositions have
differing abilities to suppress internal combustion engine fouling,
this changing of oils may lead to the build-up of deposits such as
sludge, varnish and soot-related deposits in an internal combustion
engine.
[0004] Sludge and varnish deposits form through complex
interactions of lubricating oil composition components with
contaminants under differing engine conditions. Under low
temperature operating conditions, such as short automotive trips, a
lubricating oil composition may not get hot enough for contaminants
such as water and fuel components to evaporate. At high
temperatures a lubricating oil composition can oxidise, producing
reactive groups and thickening. These conditions promote reactions
with unburnt and partially burnt fuel, water, soot, acids, blow-by
gases and other contaminants to form sludges and varnish. Also, if
high levels of soot are not efficiently dispersed, then the soot
particles can aggregate, forming extended structures and gels which
increase the low shear viscosity of a lubricating oil composition.
Such materials can build up to coat engine components and block
vital oilways, potentially causing oil starvation and wear.
[0005] WO-A-2005/073551 discloses a non-metal containing
lubricating oil additive which is said to have good cleaning
performance and a lubricating oil composition comprising the
same.
[0006] Said additive is characterised by containing a quaternary
ammonium salt having a base number of at least 10 mg KOH/g.
Examples of said additive are said to include quaternary ammonium
salts obtained through salt-exchange of counter-anions contained in
cationic surfactants such as tetra alkyl ammonium chloride and
tetra alkyl ammonium sulfate.
[0007] EP-A-0194718 discloses lubricating oil compositions that
contain one or more lubricating oils, one or more basic salts of
polyvalent metals, and one or more polyesters or salts thereof
which are either derived from one or more hydroxycarboxylic acids
of the general formula HO--X--COOH, wherein X represents a bivalent
saturated or unsaturated aliphatic radical which contains at least
8 carbon atoms and in which at least 4 carbon atoms are situated
between the hydroxyl group and the carboxyl group, or derived from
a mixture of one or more such hydroxycarboxylic acids and one or
more carboxylic acids containing no hydroxyl groups.
[0008] The polyesters present in said lubricating oil composition
are said to lead to a marked improvement in stability of the one or
more basic salts in the lubricating oil composition. In addition,
said polyesters are also said to have a cleansing effect which
renders them capable of suppressing fouling of an internal
combustion engine.
[0009] Despite such assertions, it remains highly desirable to
develop lubricating oil compositions that not only exhibit
outstanding abilities to suppress internal combustion engine
fouling during continual use, but which also exhibit excellent
cleaning performance in reducing deposits in the oil circuit of an
internal combustion engines.
SUMMARY OF THE INVENTION
[0010] In some embodiments, the present invention relates to a
lubricating oil composition comprising lubricating oil base oil,
one or more anti-wear additives and one or more
poly(hydroxycarboxylic acid) amide salt derivatives preparable by
reaction of an amine and a poly(hydroxycarboxylic acid) of formula
(I) Y--CO[O-A-CO].sub.n--OH (I) wherein Y is hydrogen or optionally
substituted hydrocarbyl group, A is a divalent optionally
substituted hydrocarbyl group and n is from 1 to 100, with an acid
or a quaternizing agent.
[0011] In other embodiments, the invention relates to a method for
reducing deposits in an internal combustion engine using a
lubricating oil in accordance with embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a more detailed understanding of the invention,
reference is made to the accompanying Figures, in which:
[0013] FIG. 1 represents graphically the % increase in cleanliness
ratings over the cleanliness ratings at 0 days for the results of
Table 3;
[0014] FIG. 2 represents graphically the % increase in cleanliness
ratings over the cleanliness ratings at 0 days for the results of
Table 4; and
[0015] FIG. 3 represents graphically the % increase in cleanliness
ratings over the cleanliness ratings at 0 hours for the results of
Table 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] Typical industry recognised methods to assess the
cleanliness of an engine are based on deposit rating systems. Such
systems typically use a numeric scale from 1 to 10 to define the
level of cleanliness, wherein a rating of 10 is defined as
completely clean.
[0017] The ability of a lubricating oil composition to suppress
internal combustion engine fouling during continual use (i.e. "keep
clean") can be observed as the rating being maintained at the same
level. Similarly, the ability of a lubricating oil composition to
exhibit "cleaning" (i.e. "clean-up") performance in reducing
deposits is observed as an increase in the rating. "Continual
cleansing" by a lubricating oil composition is observed by
increasing ratings during the test. "End of test clean-up" is
defined as the increase in rating between the start and end of
test.
[0018] There has been surprisingly found in the present invention a
lubricating oil composition for particular use in internal
combustion engines, which lubricating oil composition not only
suppresses internal combustion engine fouling and which also
exhibits advantageous cleaning performance in the reduction of
deposits such as sludge and varnish.
[0019] Accordingly, the present invention provides a lubricating
oil composition comprising lubricating oil base oil, one or more
anti-wear additives and one or more poly(hydroxycarboxylic acid)
amide salt derivatives preparable by reaction of an amine and a
poly(hydroxycarboxylic acid) of formula (I) Y--CO[O-A-CO].sub.n--OH
(I) wherein Y is hydrogen or optionally substituted hydrocarbyl
group, A is a divalent optionally substituted hydrocarbyl group and
n is from 1 to 100, preferably from 1 to 10, with an acid or a
quaternizing agent.
[0020] As used herein, the term "hydrocarbyl" represents a radical
formed by removal of one or more hydrogen atoms from a carbon atom
of a hydrocarbon (not necessarily the-same carbon atoms in case
more hydrogen atoms are removed). Hydrocarbyl groups may be
aromatic, aliphatic, acyclic or cyclic groups. Preferably,
hydrocarbyl groups are aryl, cycloalkyl, alkyl or alkenyl, in which
case they may be straight-chain or branched-chain groups.
[0021] Representative hydrocarbyl groups include phenyl, naphthyl,
methyl, ethyl, butyl, pentyl, methylpentyl, hexenyl, dimethylhexyl,
octenyl, cyclooctenyl, methylcyclooctenyl, dimethylcyclooctyl,
ethylhexyl, octyl, isooctyl, dodecyl, hexadecenyl, eicosyl,
hexacosyl, triacontyl and phenylethyl.
[0022] In the present invention, the phrase "optionally substituted
hydrocarbyl" is used to describe hydrocarbyl groups optionally
containing one or more "inert" heteroatom-containing functional
groups. By "inert" is meant that the functional groups do not
interfere to any substantial degree with the function of the
compound.
[0023] The optionally substituted hydrocarbyl group Y in formula
(I) herein is preferably aryl, alkyl or alkenyl containing up to 50
carbon atoms, more preferably in the range of from 7 to 25 carbon
atoms. For example, the optionally substituted hydrocarbyl group Y
may be conveniently selected from heptyl, octyl, undecyl, lauryl,
heptadecyl, heptadenyl, heptadecadienyl, stearyl, oleyl and
linoleyl. Other examples of said optionally substituted hydrocarbyl
group Y in formula (I) herein include C.sub.4-8 cycloalkyls such as
cyclohexyl; polycycloalkyls such as polycyclic terpenyl groups
which are derived from naturally occurring acids such as abietic
acid; aryls such as phenyl; aralkyls such as benzyl; and polyaryls
such as naphthyl, biphenyl, stibenyl and phenylmethylphenyl.
[0024] In the present invention, the optionally substituted
hydrocarbyl group Y may contain one or more functional groups such
as carbonyl, carboxyl, nitro, hydroxy, halo, alkoxy, tertiary amino
(no N--H linkages), oxy, cyano, sulfonyl and sulfoxyl. The majority
of the atoms, other than hydrogen, in substituted hydrocarbyl
groups are generally carbon, with the heteroatoms (e.g., oxygen,
nitrogen and sulfur) generally representing only a minority, about
33% or less, of the total non-hydrogen atoms present.
[0025] Those skilled in the art will appreciate that functional
groups such as hydroxy, halo, alkoxy, nitro and cyano in a
substituted hydrocarbyl group Y will displace one of the hydrogen
atoms of the hydrocarbyl, whilst functional groups such as
carbonyl, carboxyl, tertiary amino (--N--), oxy, sulfonyl and
sulfoxyl in a substituted hydrocarbyl group will displace a --CH--
or --CH.sub.2-- moiety of the hydrocarbyl.
[0026] The hydrocarbyl group Y in formula (I) is more preferably
unsubstituted or substituted by a group selected from hydroxy, halo
or alkoxy group, even more preferably C.sub.1-4 alkoxy. Most
preferably, the optionally substituted hydrocarbyl group Y in
formula (I) is a stearyl group, 12-hydroxystearyl group, an oleyl
group, a 12-hydroxyoleyl group or a group derived from naturally
occurring oil such as tall oil fatty acid.
[0027] In a preferred embodiment of the present invention, the one
or more poly(hydroxy-carboxylic acid) amide salt derivatives are
sulfur-containing poly(hydroxycarboxylic acid) amide salt
derivatives. More preferably, said one or more
poly(hydroxycarboxylic acid) amide salt derivatives have a sulfur
content in the range of from 0.1 to 2.0 wt. %, even more preferably
in the range of from 0.6 to 1.2 wt. % sulfur, as measured by
ICP-AES, based on the total weight of said poly(hydroxycarboxylic
acid) amide salt derivatives. The preparation of
poly(hydroxycarboxylic acid) and its amide or other derivatives is
known and is described, for instance, in EP-A-0164817,
WO-A-95/17473, WO-A-96/07689, U.S. Pat. No. 5,536,445,
GB-A-2001083, GB-A-1342746, GB-A-1373660, US-A-5000792 and U.S.
Pat. No. 4,349,389.
[0028] The poly(hydroxycarboxylic acid)s of formula (I) may be made
by the interesterification of one or more hydroxycarboxylic acids
of formula (II) HO-A-COOH (II) wherein A is a divalent optionally
substituted hydrocarbyl group, optionally in the presence of a
catalyst according to well known methods. Such methods are
described, for example, in U.S. Pat. No. 3,996,059, GB-A-1373660
and GB-A-1342746.
[0029] The chain terminator in said interesterification may be a
non-hydroxycarboxylic acid. The hydroxyl group in the
hydroxycarboxylic acid and the carboxylic acid group in the
hydroxycarboxylic acid or the non-hydroxycarboxylic acid may be
primary, secondary or tertiary in character.
[0030] The interesterification of the hydroxycarboxylic acid and
the non-hydroxycarboxylic acid chain terminator may be effected by
heating the starting materials, optionally in a suitable
hydrocarbon solvent such as toluene or xylene, and azeotroping off
the formed water. The reaction may be carried out at a temperature
up to -250.degree. C, conveniently at the reflux temperature of the
solvent.
[0031] Where the hydroxyl group in the hydroxycarboxylic acid is
secondary or tertiary, the temperature employed should not be so
high as to lead to dehydration of the acid molecule.
[0032] Catalysts for the interesterification, such as
p-toluenesulfonic acid, zinc acetate, zirconium naphthenate or
tetrabutyl titanate, may be included, with the objective of either
increasing the rate of reaction at a given temperature or of
reducing the temperature required for a given rate of reaction.
[0033] In the compounds of formulae (I) and (II), A is preferably
an optionally substituted aromatic, aliphatic or cycloaliphatic
straight chain or branched divalent hydrocarbyl group. Preferably,
A is an arylene, alkylene or alkenylene group, in particular an
arylene, alkylene or alkenylene group containing in the range of
from 4 to 25 carbon atoms, more preferably in the range of from 12
to 20 carbon atoms. Preferably, in said compounds of formulae (I)
and (II), there are at least 4 carbon atoms, more preferably in the
range of from 8 to 14 carbon atoms connected directly between the
carbonyl group and the oxygen atom derived from the hydroxyl
group.
[0034] In the compounds of formulae (I) and (II), the optional
substituents in the group A are preferably selected from hydroxy,
halo or alkoxy groups, more preferably C.sub.1-4 alkoxy groups. The
hydroxyl group in the hydroxycarboxylic acids of formula (II) is
preferably a secondary hydroxyl group. Examples of suitable
hydroxycarboxylic acids are 9-hydroxystearic acid,
10-hydroxystearic acid, 12-hydroxystearic acid, 12-hydroxy-9-oleic
acid (ricinoleic acid), 6-hydroxycaproic acid, preferably
12-hydroxystearic acid. Commercial 12-hydroxystearic acid
(hydrogenated castor oil fatty acid) normally contains up to 15% wt
of stearic acid and other non-hydroxycarboxylic acids as impurities
and can conveniently be used without further admixture to produce a
polymer of molecular weight about 1000-2000.
[0035] Where the non-hydroxycarboxylic acid is introduced
separately to the reaction, the proportion which is required in
order to produce a polymer or oligomer of a given molecular weight
can be determined either by simple experiment or by calculation by
the person skilled in the art.
[0036] The group (--O-A-CO--) in the compounds of formulae (I) and
(II) is preferably a 12-oxystearyl group, 12-oxyoleyl group or a
6-oxycaproyl group. Preferred poly(hydroxycarboxylic acid)s of
formula (I) for reaction with amine include poly(hydroxystearic
acid) and poly(hydroxyoleic acid). The amines which react with
poly(hydroxycarboxylic acid)s of formula (I) to form
poly(hydroxycarboxylic acid) amide intermediates may include those
defined in WO-A-97/41092. For example, various amines and their
preparations are described in U.S. Pat. No. 3,275,554, U.S. Pat.
No. 3,438,757, U.S. Pat. No. 3,454,555, U.S. Pat. No. 3,565,804,
U.S. Pat. No. 3,755,433 and U.S. Pat. No. 3,822,209.
[0037] The amine reactant is preferably a diamine, a triamine or a
polyamine. Preferred amine reactants are diamines selected from
ethylenediamine, N,N-dimethyl-1,3-propanediamine, triamines and
polyamines selected from dietheylenetriamine, triethylenetetramine,
tetraethylenepentamine, pentaethylenehexamine and
tris(2-aminoethyl)amine. The amidation between the amine reactant
and the (poly(hydroxycarboxylic acid) of formula (I) may be carried
out according to methods known to those skilled in the art, by
heating the poly(hydroxycarboxylic acid) with the amine reactant,
optionally in a suitable hydrocarbon solvent such as toluene or
xylene, and azeotroping off the formed water. Said reaction may be
carried out in the presence of a catalyst such as p-toluenesulfonic
acid, zinc acetate, zirconium naphthenate or tetrabutyl
titanate.
[0038] Various patent documents disclose poly(hydroxycarboxylic
acid) amide derivatives. For instance, GB-A-1373660 discloses
poly(hydroxycarboxylic acid) amide derivatives with amines such as
3-dimethylaminopropylamine and ethylenediamine for use as
dispersing agents in dispersions of pigments in organic liquids.
GB-A-2001083 discloses poly(hydroxycarboxylic acid) amide
derivatives with poly(ethyleneimine) (PEI) having a molecular
weight (MW) greater than 500 for a similar use. In U.S. Pat. No.
5000792, poly(hydroxycarboxylic acid) amide derivatives with amines
of the formula of NH.sub.2--R'--N(R'')--R'''--NH.sub.2 are
disclosed for use as pigment dispersing agent. WO-A-95/17473
discloses poly(hydroxycarboxylic acid) amide derivatives with
amines such as 3-dimethylaminopropylamine, ethylenediamine,
poly(ethyleneimine) (PEI) having a molecular weight (MW) greater
than 500 and amines of the formula of
NH.sub.2--R'--N(R'')--R'''--NH.sub.2 for use in a method of
preparing a non-aqueous dispersion of copper phthalocyanine.
[0039] U.S. Pat. No. 4,349,389 discloses poly(hydroxycarboxylic
acid) amide derivatives with amines such as
3-dimethyl-aminopropylamine, poly(ethyleneimine) (PEI) having a
molecular weight (MW) greater than 500 as dispersing agent in the
preparation of a dispersible inorganic pigment composition.
EP-A-0164817 discloses poly(hydroxycarboxylic acid) amide
derivatives with polyamines (ethylenediamine, diethylenetriamine,
etc.), aminoalcohols (diethanolamine, etc.) and ester derivatives
with polyols (glycerol, etc.) for use as surfactant suitable for
stabilising dispersions of solids in organic liquids and oil/water
emulsions.
[0040] However, none of the afore-mentioned patent documents
disclose the use of one or more poly(hydroxycarboxylic acid) amide
salt derivatives as disclosed herein in lubricating oil
compositions. The poly(hydroxycarboxylic acid) amide intermediate
formed from reaction of the amine and the poly(hydroxycarboxylic
acid) of formula (I) is reacted with an acid or a quaternizing
agent to form a salt derivative, according to well-known
methods.
[0041] Acids that may be used to form the salt derivative may be
selected from organic or inorganic acids. Said acids are preferably
sulfur-containing organic or inorganic acids. Preferably, said
acids are selected from sulfuric acid, methanesulfonic acid and
benzenesulfonic acid.
[0042] Quaternizing agents that may be used to form the salt
derivative may be selected from dimethylsulfuric acid, a dialkyl
sulfate having from 1 to 4 carbon atoms, an alkyl halide such as
methyl chloride, methyl bromide, aryl halide such as benzyl
chloride. In a preferred embodiment of the present invention, the
quaternizing agent is a sulfur-containing quaternizing agent, in
particular dimethylsulfuric acid or an dialkyl sulfate having from
1 to 4 carbon atoms. The quaternizing agent is preferably dimethyl
sulfate. Quaternization is a well-known method in the art. For
example, quaternization using dimethyl sulfate is described in U.S.
Pat. No. 3,996,059, U.S. Pat. No. 4,349,389 and GB-A-1373660.
[0043] In a preferred embodiment of the present invention, the one
or more poly(hydroxycarboxylic acid) amide salt derivatives
comprise a compound of formula (III):
[Y--CO[O-A-CO].sub.n-Z-R.sup.+].sub.m pX.sup.q- (III) wherein Y is
hydrogen or optionally substituted hydrocarbyl group, A is a
divalent optionally substituted hydrocarbyl group, n is from 1 to
100, preferably from 1 to 10, m is from 1 to 4, q is from 1 to 4
and p is an integer such that pq=m, Z is an optionally substituted
divalent bridging group which is attached to the carbonyl group
through a nitrogen atom, R+is an ammonium group and X.sup.q- is an
anion. R.sup.+ may be a primary, secondary, tertiary or quaternary
ammonium group and is preferably a quaternary ammonium group.
[0044] In formula (III), A is preferably a divalent straight chain
or branched hydrocarbyl group as hereinbefore described for
formulae (I) and (II). That is to say, in formula (III), A is
preferably an optionally substituted aromatic, aliphatic or
cycloaliphatic straight chain or branched divalent hydrocarbyl
group. More preferably, A is an arylene, alkylene or alkenylene
group, in particular an arylene, alkylene or alkenylene group
containing in the range of from 4 to 25 carbon atoms, more
preferably in the range of from 12 to 20 carbon atoms.
[0045] Preferably, in said compound of formula (III), there are at
least 4 carbon atoms, more preferably in the range of from 8 to 14
carbon atoms connected directly between the carbonyl group and the
oxygen atom derived from the hydroxyl group.
[0046] In the compound of formula (III), the optional substituents
in the group A are preferably selected from hydroxy, halo or alkoxy
groups, especially C.sub.1-4 alkoxy groups.
[0047] In formula (III), Y is preferably an optionally substituted
hydrocarbyl group as hereinbefore described for formula (I). That
is to say, the optionally substituted hydrocarbyl group Y in
formula (III) is preferably aryl, alkyl or alkenyl containing up to
50 carbon atoms, more preferably in the range of from 7 to 25
carbon atoms. For example, the optionally substituted hydrocarbyl
group Y may be conveniently selected from heptyl, octyl, undecyl,
lauryl, heptadecyl, heptadenyl, heptadecadienyl, stearyl, oleyl and
linoleyl.
[0048] Other examples of said optionally substituted hydrocarbyl
group Y in formula (III) herein include C.sub.4-.sub.8 cycloalkyls
such as cyclohexyl; polycycloalkyls such as polycyclic terpenyl
groups which are derived from naturally occurring acids such as
abietic acid; aryls such as phenyl; aralkyls such as benzyl; and
polyaryls such as naphthyl, biphenyl, stibenyl and
phenylmethylphenyl.
[0049] In the present invention, the optionally substituted
hydrocarbyl group Y in formula (III) may contain one or more
functional groups such as carbonyl, carboxyl, nitro, hydroxy, halo,
alkoxy, amino, preferably tertiary amino (no N-H linkages), oxy,
cyano, sulfonyl and sulfoxyl. The majority of the atoms, other than
hydrogen, in substituted hydrocarbyl groups are generally carbon,
with the heteroatoms (e.g., oxygen, nitrogen and sulfur) generally
representing only a minority, about 33% or less, of the total
non-hydrogen atoms present.
[0050] Those skilled in the art will appreciate that functional
groups such as hydroxy, halo, alkoxy, nitro and cyano in a
substituted hydrocarbyl group Y will displace one of the hydrogen
atoms of the hydrocarbyl, whilst functional groups such as
carbonyl, carboxyl, tertiary amino (--N--), oxy, sulfonyl and
sulfoxyl in a substituted hydrocarbyl group will displace a --CH--
or --CH.sub.2-- moiety of the hydrocarbyl. More preferably, the
hydrocarbyl group Y in formula (III) is unsubstituted or
substituted by a group selected from hydroxy, halo or alkoxy group,
even more preferably C.sub.1-4 alkoxy. Most preferably, the
optionally substituted hydrocarbyl group Y in formula (III) is a
stearyl group, 12-hydroxystearyl group, an oleyl group or a
12-hydroxyoleyl group, and that derived from naturally occurring
oil such as tall oil fatty acid.
[0051] In formula (III), Z is preferably an optionally substituted
divalent bridging group represented by formula (IV) ##STR1##
wherein R.sup.1 is hydrogen or a hydrocarbyl group and B is an
optionally substituted alkylene group.
[0052] Examples of hydrocarbyl groups that may represent R.sup.1
include methyl, ethyl, n-propyl, n-butyl and octadecyl. Examples of
optionally substituted alkylene groups that may represent B include
ethylene, trimethylene, tetramethylene and hexamethylene.
[0053] Examples of preferred Z moieties in formula (III) include
--NHCH.sub.2CH.sub.2-- and --NHCH.sub.2C(CH.sub.3).sub.2CH.sub.2--
and --NH(CH.sub.2).sub.3--.
[0054] Preferably, R.sup.+ may be represented by formula (V)
##STR2## wherein R.sup.2, R.sup.3 and R.sup.4 may be selected from
hydrogen and alkyl groups such as methyl.
[0055] Preferably, the anion X.sup.q- of the compound of formula
(III) is a sulfur-containing anion. More preferably said anion is
selected from sulfate and sulfonate anions.
[0056] The one or more poly(hydroxycarboxylic acid) amide salt
derivatives are present in the lubricating oil composition of the
present invention in a preferred amount in the range of from 0.1 to
10.0 wt. %, more preferably in an amount in the range of from 0.1
to 5.0 wt. % and most preferably in an amount in the range of from
0.2 to 4.0 wt. %, based on the total weight of the lubricating oil
composition.
[0057] Poly(hydroxycarboxylic acid) amide salt derivatives that are
preferred in the present invention are those which each have a TBN
(total base number) value of less than 10 mg.KOH/g, as measured by
ASTM D 4739. More preferably, the poly(hydroxycarboxylic acid)
amide salt derivatives each have a TBN value of less than 5
mg.KOH/g, most preferably 2 mg.KOH/g or less, as measured by ASTM D
4739.
[0058] Examples of poly(hydroxycarboxylic acid) amide salt
derivatives that are available commercially include that available
from Lubrizol under the trade designation "SOLSPERSE 17000" (a
reaction product of poly(12-hydroxystearic acid) with
N,N-dimethyl-1,3-propanediamine and dimethyl sulfate) and those
available under the trade designations "CH-5" and "CH-7" from
Shanghai Sanzheng Polymer Company.
[0059] The one or more anti-wear additives in the lubricating oil
composition of the present invention are preferably present in an
amount in the range of from 0.01 to 10.0 wt. %, based on the total
weight of the lubricating oil composition. Preferably, the one or
more anti-wear additives present in the lubricating oil composition
may comprise zinc dithiophosphates. The or each zinc
dithiophosphate may be selected from zinc dialkyl-, diaryl- or
alkylaryl-dithiophosphates. Preferred zinc dithiophosphates are
those that may be conveniently represented by formula (VI):
##STR3## wherein R.sup.5 to R.sup.8 may be the same or different
and are each a primary alkyl group containing from 1 to 20 carbon
atoms preferably from 3 to 12 carbon atoms, a secondary alkyl group
containing from 3 to 20 carbon atoms, preferably from 3 to 12
carbon atoms, an aryl group or an aryl group substituted with an
alkyl group, said alkyl substituent containing from 1 to 20 carbon
atoms preferably 3 to 18 carbon atoms.
[0060] Zinc dithiophosphate compounds in which R.sup.5 to R.sup.8
are all different from each other can be used alone or in admixture
with zinc dithiophosphate compounds in which R.sup.5 to R.sup.8 are
all the same. Preferably, the or each zinc dithiophosphate used in
the present invention is a zinc dialkyl dithiophosphate.
[0061] Examples of zinc dithiophosphates which are commercially
available include those available ex. Lubrizol Corporation under
the trade designations "Lz 677A", "Lz 1095", "Lz 1097", "Lz 1370",
"Lz 1371", "Lz 1373" and "Lz 1395", those available ex. Chevron
Oronite under the trade designations "OLOA 260", "OLOA 262", "OLOA
267" and "OLOA 269R", and those available ex. Afton Chemical under
the trade designation "HITEC 7169" and "HITEC 7197".
[0062] The lubricating oil composition according to the present
invention preferably comprises in the range of from 0.01 to 10.0
wt. % of zinc dithiophosphates, based on total weight of the
lubricating oil composition. Additional or alternative anti-wear
additives may be conveniently used in the lubricating oil
composition of the present invention.
[0063] In a preferred embodiment of the present invention, the
lubricating oil composition further comprises one or more
detergents, in particular one or more salicylate, phenate or
sulfonate detergents. Said detergents are preferably selected from
alkali metal or alkaline earth metal salicylate, phenate or
sulfonate detergents. Calcium and magnesium salicylates, phenates
and sulfonates are particularly preferred. Said detergents are
preferably used in amounts in the range of 0.05 to 12.5 wt. %, more
preferably from 1.0 to 9.0 wt. % and most preferably in the range
of from 2.0 to 5.0 wt. %, based on the total weight of the
lubricating oil composition.
[0064] There are no particular limitations regarding the base oil
used in the present invention, and various conventional known
mineral oils and synthetic oils may be conveniently used. The
lubricating oil base oil used in the present invention may
conveniently comprise mixtures of one or more mineral oils and/or
one or more synthetic oils. Mineral oils include liquid petroleum
oils and solvent-treated or acid-treated mineral lubricating oil of
the paraffinic, naphthenic, or mixed paraffinic/naphthenic type
which may be further refined by hydrofinishing processes and/or
dewaxing.
[0065] Naphthenic base oils have low viscosity index (VI)
(generally 40-80) and a low pour point. Such base oils are produced
from feedstocks rich in naphthenes and low in wax content and are
used mainly for lubricants in which colour and colour stability are
important, and VI and oxidation stability are of secondary
importance.
[0066] Paraffinic base oils have higher VI (generally >95) and a
high pour point. Said base oils are produced from feedstocks rich
in paraffins, and are used for lubricants in which VI and oxidation
stability are important.
[0067] Fischer-Tropsch derived base oils may be conveniently used
as the base oil in the lubricating oil composition of the present
invention, for example, the Fischer-Tropsch derived base oils
disclosed in EP-A-0776959, EP-A-0668342, WO-A-97/21788,
WO-A-00/15736, WO-A-00/14188, WO-A-00/14187, WO-A-00/14183,
WO-A-00/14179, WO-A-00/08115, WO-A-99/41332, EP-A-1029029,
WO-A-01/18156 and WO-A-01/57166.
[0068] Synthetic processes enable molecules to be built from
simpler substances or to have their structures modified to give the
precise properties required. Synthetic oils include hydrocarbon
oils such as olefin oligomers (PAOs), dibasic acid esters, polyol
esters, and dewaxed waxy raffinate. Synthetic hydrocarbon base oils
sold by the Shell Group under the designation "XHVI" (trade mark)
may be conveniently used.
[0069] Preferably, the lubricating oil base oil is constituted from
mineral oils and/or synthetic oils which contain more than 80% wt
of saturates, preferably more than 90 % wt., as measured according
to ASTM D2007.
[0070] It is further preferred that the lubricating oil base oil
contains less than 1.0 wt. %, preferably less than 0.1 wt. % of
sulfur, calculated as elemental sulfur and measured according to
ASTM D2622, ASTM D4294, ASTM D4927 or ASTM D3120. Preferably, the
viscosity index of the lubricating oil base oil is more than 80,
more preferably more than 120, as measured according to ASTM
D2270.
[0071] The total amount of lubricating oil base oil incorporated in
the lubricating oil composition of the present invention is
preferably present in an amount in the range of from 60 to 92 wt.
%, more preferably in an amount in the range of from 75 to 90 wt. %
and most preferably in an amount in the range of from 75 to 88 wt.
%, with respect to the total weight of the lubricating oil
composition.
[0072] Preferably, the lubricating oil composition has a kinematic
viscosity in the range of from 2 to 80 mm.sup.2/s at 100 .degree.
C., more preferably in the range of from 3 to 70 mm.sup.2/s, most
preferably in the range of from 4 to 50 mm.sup.2/s.
[0073] The lubricating oil composition of the present invention may
further comprise additional additives such as anti-oxidants,
dispersants, friction modifiers, viscosity index improvers, pour
point depressants, corrosion inhibitors, defoaming agents and seal
fix or seal compatibility agents.
[0074] Antioxidants that may be conveniently used include those
selected from the group of aminic antioxidants and/or phenolic
antioxidants. In a preferred embodiment, said antioxidants are
present in an amount in the range of from 0.1 to 5.0 wt. %, more
preferably in an amount in the range of from 0.3 to 3.0 wt. %, and
most preferably in an amount of in the range of from 0.5 to 1.5 wt.
%, based on the total weight of the lubricating oil
composition.
[0075] Examples of aminic antioxidants which may be conveniently
used include alkylated diphenylamines,
phenyl-.alpha.-naphthylamines, phenyl-.beta.-naphthylamines and
alkylated-naphthylamines. Preferred aminic antioxidants include
dialkyldiphenylamines such as p,p'-dioctyl-diphenylamine,
p,p'-di-.alpha.-methylbenzyl-diphenylamine and
N-p-butylphenyl-N-p'-octylphenylamine, monoalkyldiphenylamines such
as mono-t-butyldiphenylamine and mono-octyldiphenylamine,
bis(dialkylphenyl)amines such as di-(2,4-diethylphenyl)amine and
di(2-ethyl-4-nonylphenyl)amine, alkylphenyl-l-naphthylamines such
as octylphenyl-1-naphthylamine and n-t-dodecylphenyl-1
-naphthylamine, 1-naphthylamine, arylnaphthylamines such as
phenyl-1-naphthylamine, phenyl-2-naphthylamine,
N-hexylphenyl-2-naphthylamine and N-octylphenyl-2-naphthylamine,
phenylenediamines such as N,N'-diisopropyl-p-phenylenediamine and
N,N'-diphenyl-p-phenylenediamine, and phenothiazines such as
phenothiazine and 3,7-dioctylphenothiazine. Preferred aminic
antioxidants include those available under the following trade
designations: "Sonoflex OD-3" (ex. Seiko Kagaku Co.), "Irganox
L-57" (ex. Ciba Specialty Chemicals Co.) and phenothiazine (ex.
Hodogaya Kagaku Co.).
[0076] Examples of phenolic antioxidants which may be conveniently
used include C.sub.7-C.sub.9 branched alkyl esters of
3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-benzenepropanoic acid,
2-t-butylphenol, 2-t-butyl-4-methylphenol,
2-t-butyl-5-methylphenol, 2,4-di-t-butylphenol,
2,4-dimethyl-6-t-butylphenol, 2-t-butyl-4-methoxyphenol,
3-t-butyl-4-methoxyphenol, 2,5-di-t-butylhydroquinone,
2,6-di-t-butyl-4-alkylphenols such as 2,6-di-t-butylphenol,
2,6-di-t-butyl-4-methylphenol and 2,6-di-t-butyl-4-ethylphenol,
2,6-di-t-butyl-4-alkoxyphenols such as
2,6-di-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-ethoxyphenol,
3,5-di-t-butyl-4-hydroxybenzylmercaptooctylacetate,
alkyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionates such as
n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,
n-butyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and
2'-ethylhexyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,
2,6-d-t-butyl-.alpha.-dimethylamino-p-cresol,
2,2'-methylenebis(4-alkyl-6-t-butylphenol) such as
2,2'-methylenebis(4-methyl-6-t-butylphenol, and
2,2-methylenebis(4-ethyl-6-t-butylphenol), bisphenols such as
4,4'-butylidenebis(3-methyl-6-t-butylphenol,
4,4'-methylenebis(2,6-di-t-butylphenol),
4,4'-bis(2,6-di-t-butylphenol), 2,2-(di-p-hydroxyphenyl)propane,
2,2-bis(3,5-di-t-butyl-4-hydroxyphenyl)propane,
4,4'-cyclohexylidenebis(2,6-t-butylphenol), hexamethyleneglycol-bis
[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionatel,
triethyleneglycolbis
[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionatel,
2,2'-thio-[diethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],
3,9-bis{1,1
-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)-propionyloxylethyl}2,-
4,8,10-tetraoxaspiro[5,5]undecane,
4,4'-thiobis(3-methyl-6-t-butylphenol) and
2,2'-thiobis(4,6-di-t-butylresorcinol), polyphenols such as
tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionatelmethane,
1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)-butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,
bis-[3,3'-bis(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol
ester,
2-(3',5'-di-t-butyl-4-hydroxyphenyl)methyl-4-(2'',4''-di-t-butyl-3''-hydr-
oxyphenyl)methyl-6-t-butylphenol and
2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl)-4-methylphenol, and
p-t-butylphenol--formaldehyde condensates and
p-t-butylphenol--acetaldehyde condensates.
[0077] Preferred phenolic antioxidants include those available
under the following trade designations: "Irganox L-135" (ex. Ciba
Specialty Chemicals Co.), "Yoshinox SS" (ex. Yoshitomi Seiyaku
Co.), "Antage W-400" (ex. Kawaguchi Kagaku Co.), "Antage W-500"
(ex. Kawaguchi Kagaku Co.), "Antage W-300" (ex. Kawaguchi Kagaku
Co.), "Irganox L-109" (ex. Ciba Speciality Chemicals Co.), "Tominox
917" (ex. Yoshitomi Seiyaku Co.), "Irganox L-115" (ex. Ciba
Speciality Chemicals Co.), "Sumilizer GA80" (ex. Sumitomo Kagaku),
"Antage RC" (ex. Kawaguchi Kagaku Co.), "Irganox L-101" (ex. Ciba
Speciality Chemicals Co.), "Yoshinox 930" (ex. Yoshitomi Seiyaku
Co.).
[0078] The lubricating oil composition of the present invention may
comprise mixtures of one or more phenolic antioxidants with one or
more aminic antioxidants.
[0079] The lubricating oil compositions of the present invention
may additionally contain an ash-free dispersant which is preferably
admixed in an amount in the range of from 5 to 15 wt. %, based on
the total weight of the lubricating oil composition. Examples of
ash-free dispersants which may be used include the polyalkenyl
succinimides and polyalkenyl succininic acid esters disclosed in
Japanese Laid-Open Patent Application Nos. JP 53-050291 A, JP
56-120679 A, JP 53-056610 A and JP 58-171488 A. Preferred
dispersants include borated succinimides.
[0080] Examples of viscosity index improver improvers which may
conveniently be used in the lubricating oil composition of the
present invention include the styrene-butadiene copolymers,
styrene-isoprene stellate copolymers and the polymethacrylate
copolymer and ethylene-propylene copolymers. Dispersant-viscosity
index improvers may be used in the lubricating oil composition of
the present invention. Such viscosity index improver improvers may
be conveniently employed in an amount in the range of from 1 to 20
wt. %, based on the total weight of the lubricating oil
composition.
[0081] Polymethacrylates may be conveniently employed in the
lubricating oil compositions of the present invention as effective
pour point depressants. Furthermore, compounds such as alkenyl
succinic acid or ester moieties thereof, benzotriazole-based
compounds and thiodiazole-based compounds may be conveniently used
in the lubricating oil composition of the present invention as
corrosion inhibitors. Compounds such as polysiloxanes, dimethyl
polycyclohexane and polyacrylates may be conveniently used in the
lubricating oil composition of the present invention as defoaming
agents. Compounds which may be conveniently used in the lubricating
oil composition of the present invention as seal fix or seal
compatibility agents include, for example, commercially available
aromatic esters.
[0082] The lubricating oil compositions of the present invention
may be conveniently prepared by admixing the one or more anti-wear
additives, one or more poly(hydroxycarboxylic acid) amide salt
derivatives and, optionally, one or more detergents and further
additives that are usually present in lubricating oil compositions,
for example as herein before described, with mineral and/or
synthetic base oil.
[0083] The present invention further provides a method of reducing
deposits in an internal combustion engine, which method comprises
lubricating said internal combustion engine with a lubricating oil
composition as hereinbefore described. Furthermore, the present
invention also provides for the use of a lubricating oil
composition as hereinbefore described in order to reduce deposits
in an internal combustion engine. In particular, the present
invention provides a method of suppressing internal combustion
engine fouling and/or improving cleaning performance in the
reduction of deposits such as sludge and varnish.
[0084] Thus, the present invention further provides for the use of
a lubricating oil composition as hereinbefore described in order to
suppress internal combustion engine fouling and/or improve cleaning
performance in the reduction of internal combustion engine deposits
such as sludge and varnish.
[0085] There is further provided a method of lubricating an
internal combustion engine comprising applying a lubricating oil
composition as hereinbefore described thereto.
[0086] The present invention is described below with reference to
the following Examples, which are not intended to limit the scope
of the present invention in any way.
EXAMPLES
Lubricating Oil Compositions
[0087] Tables 1 and 2 indicate the lubricating oil compositions
that were tested.
[0088] Poly(hydroxycarboxylic acid) amide salt derivatives
according to the present invention that were used in testing were
products available commercially from Lubrizol under the trade
designation "SOLSPERSE 17000" (a reaction product of
poly(12-hydroxystearic acid) with N,N-dimethyl-1,3-propanediamine
and dimethyl sulfate) and under the trade designation "CH-7" from
Shanghai Sanzheng Polymer Company. "SOLSPERSE 17000" product and
"CH-7" product have TBN values of approximately 2.0 mg.KOH/g and
1.9 mg.KOH, respectively, as measured by ASTM D 4739. Furthermore,
"SOLSPERSE 17000" product and "CH-7" product have sulfur contents
of approximately 0.89 wt. % and 0.86 wt. %, respectively, as
measured by ICP-AES.
[0089] A comparative product was tested which was a
poly(hydroxycarboxylic acid) derivative that is not according to
the teaching of the present invention. Said comparative product is
available from commercially from Lubrizol under the trade
designation "SOLSPERSE 11200". "SOLSPERSE 11200" product has a TBN
value of approximately 35 mg.KOH/g, as measured by ASTM D 4739 and
a sulfur content of <0.01 wt. %, as measured by ICP-AES.
[0090] The formulation of Comparative Example 1 in Table 1 was a
commercial engine oil which comprised API Group I base oil, pour
point depressant, viscosity modifier, antifoam, a conventional
additive package containing sulfonate and phenate detergents having
TBNs in the range of from 30 to 350 mg.KOH/g, PIB succinimide
dispersant and zinc dithiophosphate and diluent oil. Said
formulation was also used as the basis for the formulations of
Examples 2 and 3.
[0091] The formulation of Comparative Example 3 in Table 2 was a
commercial engine oil which comprised base oil and zinc
dithiophosphate anti-wear additive and conventional lubricant
additives and is available from the Shell group under the trade
designation "HELIX" engine oil. Said formulation was also used as
the basis for the formulation of Example 4. TABLE-US-00001 TABLE 1
Comp. Comp. Additive (wt. %) Ex. 1 Ex. 2.sup.1 Ex. 3.sup.1 Ex.
1.sup.2 Ex. 2 Anti-foam -- 10 ppm 10 ppm 10 ppm -- Additive package
-- 11.3 11.3 11.3 -- Pour point depressant -- 0.15 0.15 0.15 --
Viscosity modifier -- 6.2 6.2 6.2 -- "SOLSPERSE 17000" 3.0 3.0 --
-- -- product "SOLSPERSE 11200" -- -- -- -- 3.0 product "CH-7"
product -- -- 3.0 -- -- API Group I Base Oil 97.0 79.35 79.35 82.35
97.0 TOTAL 100 100 100 100 100 .sup.1Lubricating oil composition of
Comp. Ex. 1 with further "SOLSPERSE 17000" or "CH-7" products
added. .sup.2Commercial engine oil comprising a conventional
additive package containing sulfonate and phenate detergents having
TBNs in the range of from 30 to 350 mg KOH/g, PIB succinimide
dispersant and zinc dithiophosphate and diluent oil.
[0092] TABLE-US-00002 TABLE 2 Comp. Formulation/additive (wt. %)
Ex. 4 Ex. 3 Commercial engine oil available from the Shell group
97.0 100.0 under the trade designation "HELIX" engine oil "CH-7"
additive 3.0 -- TOTAL 100 100
Modified Sequence VG Test
[0093] The modified Sequence VG test was performed as follows:
[0094] 1. The "dirty-up" phase was conducted as per ASTM D6593,
using a new VG engine and a "dirty-up" standard oil which was an
API SF specification oil with the following modifications: [0095]
Intermediate sludge ratings of the right side of the engine were
carried out every 24 hours on the valve deck, cam cover and
cam-baffle. [0096] Photographs were taken of each of these
components every 24 hours. [0097] The test was run until one of the
components had accumulated enough sludge and varnish to achieve a
rating of approximately 7. The time taken to reach this rating
(.about.7) was approximately 216 to 288 hours.
[0098] 2. At the end of the "dirty-up" phase, the "dirty-up"
standard oil was drained. The "dirty-up" standard oil was then
replaced with the lubricating oil composition to be tested and the
engine was ready to continue with the second part of the test.
[0099] 3. The second part of the test, the "clean-up" phase, was
conducted in exactly the same manner as the "dirty-up" phase for
the standard 216 hours. 24 hourly ratings and photographs were
taken throughout the test.
[0100] 4. Passing lubricating oil compositions tended to show an
initial "cleaning" effect, followed by "continual cleansing". For
passing lubricating oil compositions, the average rating increased
significantly during the first 24 hours of the "clean-up" phase and
the final (216 hour) rating was higher than this "post-cleaning"
rating.
Bench Screener Test
[0101] A bench screener test was developed in order to demonstrate
deposit control specifically in relation to the ability of a
lubricant to "clean-up" real engine sludge rather than just "keep
clean."
[0102] 1. A cam-baffle was obtained from a VG engine after running
the dirty-up phase of the modified Sequence VG test as described
above.
[0103] 2. 1 cm.times.1 cm samples were cut from the cam-baffle,
using a lever-press to avoid contamination with cutting fluid.
[0104] 3. Cam-baffle samples were dipped in lubricating oil
compositions to be tested and allowed to drain before initial
cleanliness ratings for sludge and varnish were made and
photographs were taken for each sample.
[0105] 4. Cam-baffle samples were then suspended in the lubricating
oil compositions to be tested (100 g). The lubricating oil
compositions were then stirred and maintained at 80.degree. C. for
a period of up to 14 days.
[0106] 5. Cleanliness ratings and photographs were taken at
intermediate time-intervals to assess the performance of the
lubricating oil compositions tested.
[0107] A rating of 10.0 means that the sample was completely clean
with no sludge or varnish thereon.
Results and Discussion
[0108] The formulations described in Tables 1 and 2 were tested
using the afore-mentioned tests and the results obtained thereon
are detailed below:
[0109] Testing using bench screener test
Example 1 and Comparative Examples 1 and 2
[0110] The lubricating oil compositions of Example 1 and
Comparative Examples 1 and 2 were screened using the bench test
screener test. Cleanliness ratings for the lubricating oil
compositions of Example 1 and Comparative Example 2 were taken and
compared against those of the fully formulated lubricating oil
composition of Comparative Example 1 at 0, 3, 7 and 15 days. The
cleanliness ratings are given in Table 3. TABLE-US-00003 TABLE 3
Cleanliness ratings taken after: Example 0 days 3 days 7 days 15
days Ex. 1 8.24 10.00 10.00 10.00 Comp. Ex. 1 9.23 9.65 9.70 9.75
Comp. Ex. 2 9.18 9.37 9.48 9.48
[0111] FIG. 1 represents graphically the percent increase in
cleanliness ratings over the cleanliness ratings at 0 days for the
results of Table 3. It is apparent from Table 3 and FIG. 1 that the
cleaning performance of the lubricating oil composition of Example
1 was outstanding. In particular, the blend had the ability to
clean both sludge and varnish from the cam-baffle sample. Indeed,
it is apparent from the cleanliness ratings that while the initial
cleanliness rating was lower for the cam-baffle sample tested with
the formulation of Example 1, said lubricating oil composition
quickly allowed the cam-baffle to achieve a rating of 10, i.e.
representing a completely clean cam-baffle.
Examples 2 and 3 and Comparative Example 1
[0112] The lubricating oil compositions of Examples 2 and 3 and
Comparative Example 1 were screened using the bench test screener
test. Cleanliness ratings for the lubricating oil compositions of
Examples and 2 were taken and compared against those of the fully
formulated lubricating oil composition of Comparative Example 1 at
0, 2, 4 and 11 days. The cleanliness ratings are given in Table 4.
TABLE-US-00004 TABLE 4 Cleanliness ratings taken after: Example 0
days 2 days 4 days 11 days Ex. 2 8.24 8.27 9.05 9.40 Ex. 3 8.24
8.82 9.02 9.55 Comp. Ex. 1 8.24 8.24 8.24 8.30
[0113] FIG. 2 represents graphically the percent increase in
cleanliness ratings over the cleanliness ratings at 0 days for the
results of Table 4. It is apparent from Table 4 and FIG. 2 that the
cleaning performance of the lubricating oil compositions of
Examples 2 and 3 exceeded that of the commercial engine oil of
Comparative Example 1 upon which they were based.
Testing Using Modified Sequence VG Test
[0114] The lubricating oil compositions of Example 4 and
Comparative Example 3 were screened using the modified Sequence VG
engine test as hereinbefore described. The cleanliness ratings are
given in Table 5. TABLE-US-00005 TABLE 5 Cleanliness Rating Comp.
Hours Ex. 3 Example 4 0.00 8.08 6.76 24.00 8.64 6.94 48.00 8.65
7.40 72.00 8.65 7.48 96.00 8.60 7.32 120.00 8.72 7.51 144.00 8.74
7.80 168.00 8.74 7.82 192.00 8.72 7.84 216.00 8.65 7.83
[0115] The lubricating oil composition of Comparative Example 3 was
a commercial engine oil available from the Shell group under the
trade designation "HELDI" engine oil, whilst the lubricating oil
composition of Example 4 was the same formulation boosted with 3.0
wt. % of "CH-7" product. FIG. 3 represents graphically the percent
increase in cleanliness ratings over the cleanliness ratings at 0
hours for the results of Table 5. It is apparent from the results
of the modified Sequence VG test on the boosted formulation of
Example 4 that said formulation displays better cleaning
performance vis-a-vis the standard formulation of Comparative
Example 3 in terms of the change in average merit rating of engine
parts.
[0116] The average end-of-test clean-up for the lubricating oil
composition of Comparative Example 3 was 0.57 merit, whereas the
average end-of-test clean-up for the boosted lubricating oil
composition of Example 4 was 1.07 merit.
[0117] While preferred embodiments of the invention have been
described herein, it will be understood that various modifications
could be made to the components thereof without departing from the
scope of the invention. The Examples and other specific
descriptions are intended to merely illustrate the invention and
are not intended to limit the scope of the claims that follow.
* * * * *