Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Lubricant Compositions
This invention relates to an improved lubricating oil composition for marine
applications,
such as a marine diesel cylinder lubricant (MDCL) suitable for cross-head
diesel engines.
More particularly, this invention relates to a finished lubricant formulation
exhibiting
improved piston ring and liner wear performance.
The lubrication of cross-head diesel engines, in particular the cylinder
liners and piston
rings of such-engines, presents problems because the operating temperatures
and
pressures can lead to breakdown of the film of lubricant on the internal walls
of the
cylinder liners. When this occurs, the cylinder liners andlor piston rings may
wear
excessively.
EP-A-369,804 describes a method of lubricating a cross-head engine which
comprises
i5 lubricating the engine with a lubricant composition comprising a major
amount of base oil
and minor amounts of an anti-wear additive and of an extreme-pressure
additive. It states
that the amount of extreme pressure additive should be sufficient to provide
an extreme
pressure effect, usually up to 5.0 mass % based on the total weight of the
composition.
Thus, EP-A-369,804 teaches the need for a combination of an extreme-pressure
additive
2o and an anti-wear additive to achieve effectiveness.
The present invention solves the above problem by lubricating a marine diesel
engine with
at least one ashless anti-wear additive without need for minor amounts of an
extreme
pressure additive, whilst providing effective anti-wear performance under the
high
25 temperature and high pressure conditions of the cylinder liners and piston
rings of marine
diesel engines; furthermore, EP-A-369,804 describes the use, as co-additives,
of
overbased 250 TBN calcium phenate in combination with overbased 300 TBN
calcium
sulfonate. The present invention also provides the particularly effective use
of
combination with a minor amount of an ashless anti-wear additive.
Accordingly, a first aspect of the present invention is a marine diesel engine
lubricant
composition having a TBN of at least 10, such as at least 20, and preferably a
viscosity
index of at least 90, preferably at least 100, more preferably at least 110,
the composition
comprising, or being provided by admixing, a major amount of oil of
lubricating viscosity
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and a minor amount of
(A) an ashless antiwear additive; and
(B) a metal detergent in the form of
(i) an overbased metal detergent having a TBN at least 300, preferably
at least 330, more preferably at least 400, and comprising a
surfactant system derived from at least two surfactants, andlor
(ii) a metal detergent other than (i);
provided that, if detergent (ii) is present, the composition does not contain
a minor amount
of an extreme pressure additive, being up to 5.0 mass % based on the total
mass of the
to composition.
A second aspect of the present invention is a method of making a marine diesel
engine
lubricant composition having a TBN of at least 10, such as at least 20, and
preferably a
viscosity index of at least 90, preferably at least 100, more preferably at
least 110,
~5 comprising blending a major amount of oil of lubricating viscosity and
minor amounts of (A)
and (B) as defined in the first aspect of the invention, provided that, if
detergent {ii) is
blended, a minor amount of an extreme pressure agent, being up to 5.0 mass %
based on
the total mass of the composition, is not blended..
2o Preferably, in respect of use of metal detergent (B) (ii), the extreme
pressure additive, if
used, is not present in an amount up to 5.0, 4, 3, 2 or 1, mass % based on the
mass of the
lubricant composition. More, preferably, the extreme pressure additive is
absent, and is
absent also in respect of use of metal detergent (B) (i).
25 In contrast to antiwear additives, which protect against friction and wear
under moderate
boundary conditions, an extreme-pressure additive prevents the welding of
mating
surfaces that occurs at the exceedingly high local temperatures developed when
opposing
bodies are rubbed together under sufficient load. The latter form of
protection is effective
only under conditions of high local temperature. Thus,~an extreme-pressure
additive is
3o essentially an extreme-temperature additive. The aforementioned EP-A-
369,804
describes extreme pressure additives, as does J A Williams in
°Engineering Tribology"
{Oxford University Press, 1994), ps 354-357. The latter reference states that
the real
function of extreme-pressure additives is to lubricate at comparatively high
temperatures,
pefiaps up to as much as 300-400°C; in contrast, anti-wear additives
lubricate at lower
2
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temperatures and, according to the latter reference, act in a different way.
A third aspect of the present invention is a marine diesel engine lubricant
composition
comprising, or being provided by admixing, a major amount of oil of
lubricating viscosity
and a minor amount of (A) comprising a sulfur-containing boroester compound
having the
general formula (I):
(OB)mR2
R~S(R40)n (I)
-~ (OB)iRs
wherein R' represents a hydrocarbyl group having from 4 to 12 carbon atoms, R2
and R3
1o independently represent -(OR°)~SR' or -{OR')~SR'OH; R' represents a
hydrocarbyl group
having from 1 to 6 carbon atoms; n is an integer of from 1 to 4; and I and m
are
independently 0, 1 or 2;
a cyclic metaborate ester having the general formula (II):
R'
O
(II)
R~ S(R40)n-B
O
R'
wherein n, R' and R', are defined as in formula (I); or a mixture of a borate
ester of formula
{I) and a metaborate ester of formula (II), and (B) a metal detergent.
A fourth aspect of the present invention is a method of making a marine diesel
engine
lubricant composition comprising blending a major amount of oil of lubricating
viscosity
and a minor amount of an additive as defined in the third aspect of the
present invention.
A fifth aspect of the present invention is a method of reducing the piston
ring and cylinder
liner wear of a marine diesel engine, the method comprising lubricating the
engine with a
lubricant composition according to the first or third aspects of this
invention, or made by
3
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the method according to the second or fourth aspects of this invention.
A sixth aspect of the present invention is the use of a lubricant composition
to reduce the
piston ring and cylinder liner wear of a marine diesel engine which comprises
lubricating
5 the engine with a lubricant composition according to the first, or third
aspects of this
invention, or made by the method according to the second or fourth aspects of
this
invention.
A seventh aspect of the present invention is a method of lubricating a marine
diesel engine
~o which comprises supplying to the engine a marine diesel engine lubricant
composition
according to the first or third aspects of the invention, or made by the
method according to
the second or fourth aspects of the invention. In performing the seventh
aspect of the
invention, the engine may be supplied with a fuel having a sulfur-content,
expressed as
elemental sulfur, of not greater than 1.5, such as 0.5 to 1, mass %.
In another aspect of the present invention, there is provided a method of
lubricating a
cross-head marine diesel engine cylinder under boundary lubrication which
method
comprises supplying to a cylinder of the engine a lubricant composition having
a TBN
of at least 10, the composition comprising a major amount of oil of
lubricating
2o viscosity and a composite minor amount of: (A) an ashless antiwear additive
comprising a sulphur-containing boroester compound, being a borate ester
having the
general formula (I):
2s / (~g)mR2
R' S(R4~),~8~
wherein R' is a hydrocarbyl group having from 4 to 12 carbon atoms, R2 and R3
are
independently -(OR4)~SR' or -(OR4)~SR'OH; R4 represents a hydrocarbyl group
having from 1 to 6 carbon atoms; n is an integer of from 1 to 4; and I and m
are
independently 0, 1 or 2;
CA 02315707 2005-11-17
a cyclic metaborate ester having the general formula (II):
\ (u)
R1$(R40)n-S'
'O~8.
~~'~~~OR4)nS~,
wherein n, R' and R4, are defined as in formula (I); or a mixture of one or
more borate
esters of formula (I) and one or more metaborate esters of formual (II); (B) a
metal
detergent in the form of (i) an overbased metal detergent having a TBN at
(east 300,
and comprising a surfactant system derived from at least two surfactants,
and/or (ii) a
metal detergent other than (i); and (C) optionally, an extreme pressure
additive;
provided that, if detergent (ii) is blended, no more than 5.0 mass %, based on
the
total mass of the composition, of the optional extreme pressure additive is
blended.
In another aspect of the present invention, there is provided the use of a
lubricant
composition to reduce the piston ring and cylinder liner wear of a cross-head
diesel
engine which comprises lubricating a cylinder of the engine under boundary
lubrication with a composition as defined herein.
In another aspect of the present invention, there is provided a cross-head
marine
diesel engine cylinder lubricant composition, wherein the composition is as
defined
herein, wherein the ashless antiwear additive comprises a sulphur-, phosphorus-
, or
boron-containing additive, or a mixture thereof, and wherein the sulphur-
containing
additive is an additive other than a 1,3, 4-thiadiazole.
In another aspect of the present invention, there is provided a cross-head
marine
diesel engine cylinder lubricant composition, wherein the composition is as
defined
herein, provided that the TBN of the composition is less than 30.
4a
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In this specification, TBN (Total Base Number) is as measured by ASTM D2896,
and
viscosity index is as defined by ASTM D2270.
In this specification, unless otherwise stated, proportions of additives are
quoted in terms
of the proportion of active ingredient thereof, sometimes referred to as
'a.i.", e.g. such
proportions do not include diluent.
In this specification, by "hydrocarbyl" is meant a group that is connected to
the remainder
of the molecular via a carbon atom, that contains hydrogen and carbon atoms,
and that
may contain atoms other than hydrogen and carbon, such as hetero atoms,
provided they
do not interfere with the essentially hydrocarbon nature of the group.
The features of the invention will now be discussed in more detail.
MARINE DIESEL ENGINES
The lubricant composition of the present invention may be suitable for use in
a 4-stroke
trunk piston diesel engine such as having an engine speed of 200-2,000, e.g.
400-1,000.
4b
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rpm, and a brake horse-power (BHP) per cylinder of 50-3,000, preferably 100-
2,000. it
may also be suitable for use in a 2-stroke cross-head diesel engine such as
having a
speed of 40-200, preferably 60-120 rpm and a BHP per cylinder of 500-10,000.
The
above engine types may be referred to as medium - and slow-speed diesel
engines
respectively. Preferably, the engine is a cross-head diesel engine.
LUBRICANT COMPOSITION
to Preferably, the TBN of the lubricant composition is at least 40, for
example in the range of
from 60 to 100. Preferably, the viscosity index of the lubricant composition
is at least 115,
more preferably at least 120, and at most 180 such as 150, preferably 130. A
preferred
viscosity index range is from 120 to 130.
t5 The lubricant composition may, for example, have a kinematic viscosity at
100°C (as
measured by ASTM D445) of at least 14, preferably at least 15, more preferably
in the
range of from 17 to 30, for example from 17 to 25, mmZ/s.
The composition may be prepared by adding to the oil of lubricating viscosity
a mixture of,
20 or separately, minor amounts of the additives defined and described herein
and, if
necessary, one or more co-additives such as described hereinafter. Additives
may be
added directly or in the form of concentrates, including so-called "adpacks",
as known in
the art.
25 LUBRICATING OIL
The oil of lubricating viscosity (sometimes referred to as lubricating oil)
may be any oil
suitable for the lubrication of a cross-head engine or a trunk piston engine.
The lubricating
oil may suitably be an animal, a vegetable or a mineral oil. Suitably the
lubricating oil is a
3o petroleum-derived lubricating oil, such as a naphthenic base, paraffinic
base or mixed
base oil. Alternatively, the lubricating oil may be a synthetic lubricating
oil. Suitable
synthetic lubricating oils include synthetic ester lubricating oils, which
oils include diesters
such as di-octyl adipate, di-octyl sebacate and tri-decyl adipate, or
polymeric hydrocarbon
lubricating oils, for example liquid polyisobutene and poly-alpha olefins.
Commonly, a
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WO 99/35218 PCT/EP98/08576
mineral oil is employed. The lubricating oil may generally comprise greater
than 60,
typically greater than 70, % by mass of the composition, and typically have a
kinematic
viscosity at 100°C of from 2 to 40, for example from 3 to 15, mmzls,
and a viscosity index
of from 80 to 100, for example from 90 to 95.
Another class of lubricating oils comprises hydrocracked oils, formed where
the refining
process further breaks down the middle and heavy distillate fractions in the
presence of
hydrogen at high temperatures and moderate pressures. Hydrocracked oils
typically have
kinematic viscosity at 100°C of from 2 to 40, for example from 3 to 15,
mm2ls and a
lo viscosity index typically in the range of from 100 to 110, for example from
105 to 108.
Base oils which are solvent-extracted and de-asphalted products from vacuum
residuum
generally having a kinematic viscosity at 100°C of from 28 to 36 mmzls
are also suitable
for use in the prevent invention. They are typically used in a proportion of
less than 30,
~5 preferably less than 20, more preferably less than 15, most preferably less
than 10, such
as less than 5, mass %, based on the mass of the composition.
The terms 'oil-soluble' or 'oil-dispersible' as used herein do not necessarily
indicate that
the compounds or additives are soluble, dissolvable, miscible or capable of
being
2o suspended in the oil in all proportions. They do mean, however, that they
are, for
instance, soluble or stably dispersible in oil to an extent sufficient to
exert their intended
effect in the environment in which the oil is employed. Moreover, the
additional
incorporation of other additives may also permit incorporation of higher
levels of a
particular additive, if desired.
The lubricant compositions of this invention comprise defined components that
may or
may not remain the same chemically before and after mixing.
(A) ASHLESS ANTI-WEAR ADDITIVE
As used herein, the term 'ashless' refers to additives that are metal-free.
Ashless anti-wear additives protect against wear by reacting chemically with
the metal
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WO 99135218 PCT/EP98108576
surface to form a protective coating that allows the moving parts to slide
across each other
with minimum loss of wear.
Ashless anti-wear additives may be selected from sulfur-, phosphorus-, or
boron-
containing additives and mixtures thereof.
Examples of sulfur-containing ashless anti-wear additives are thiocarbamate-
containing
compounds, such as thiocarbamate esters, thiocarbamate amides, thiocarbamic
ethers,
alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl) disulfides.
io
The dithiocarbamate-containing compounds may be prepared by reacting a
dithiocarbamate acid or salt with an unsaturated compound. The dithiocarbamate-
containing compounds may also be prepared by simultaneously reacting an amine,
carbon
disulfide and an unsaturated compound. Generally, the reaction occurs at a
temperature
~5 from 25 to 125°C. US Patents 4,758,362 and 4,997,969 describe
dithiocarbamate
compounds and methods of making them.
The dithiocarbamate acid or salt which may be used to prepare the
dithiocarbamate-
containing compounds may be prepared by reacting an amine with carbon
disulfide. The
2o amines may be primary or secondary amines, secondary amines being
preferred. The
amines generally may contain hydrocarbyl groups. Each hydrocarbyl group may
independently contain from one up to 40, or from two up to 30, or from three
up to 24, or
even up to 12, carbon atoms.
25 Examples of primary amines useful in the present invention include
ethylamine,
propylamine, butylamine, 2-ethylhexylamine, octyfamine and dodecylamine.
Also suitable are primary fatty (C~) amines which include n-octylamine, n-
decyiamine,
n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine and
oleyamine.
so Other useful fatty amines include commercially available fatty amines such
as "Armeen"
(RTM) amines (products availabie from Akzo Chemicals, Chicago, Illinois), such
as Akzo's
Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S and Armeen SD,
wherein the letter designation relates to the fatty group, such as corn,
oleyl, tallow, or
stearyl groups.
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Other useful primary amines include primary ether amines, such as those
represented by
the formula, R"RO')xNH2, wherein R' represents a divalent alkylene group
having 2 to 6
carbon atoms; x is a number from one to 150, or from one to five, or one; and
R"
represents a hydrocarbyl group of 5 to 150 carbon atoms. An example of an
ether amine
is available under the name SURFAM~ amines produced and marketed by Macs
Chemical
Company, Atlanta, Georgia. Preferred etheramines are exemplified by those
identified as
SURFAM P14B (decyloxypropylamine), SURFAM P16A (linear C,g), SURFAM P178
(tridecyioxypropylamine). The carbon chain lengths (i.e., C,4) of the SURFAMS
described
to above are approximate and include the oxygen ether linkage.
The amine may also be a tertiary-aliphatic primary amine. Generally, the
aliphatic group,
preferably an alkyl group, contains from 4 to 30, or from 6 to 24, or from 8
to 22, carbon
atoms. Usually the tertiary alkyl primary amines are monoamines represented by
the
15 formula R,-C(R,')Z-NHZ, wherein R,' represents a hydrocarbyl group
containing from one
to 27 carbon atoms and each R,' independently represents a hydrocarbyl group
containing
from 1 to 12 carbon atoms. Such amines are illustrated by tert-butylamine,
tert-
hexylamine, 1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine,
tert-
dodecylamine, tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine,
tert-
2o tetracosanyfamine, and tent-octacosanylamine.
Mixtures of amines are also useful. Illustrative of amine mixtures of this
type are "Primene
81 R" which is a mixture of C"-C,4 tertiary alkyl primary amines and "Primene
JMT" which
is a similar mixture of C,a-C22 tertiary alkyl primary amines (both are
available from Rohm
25 and Haas Company). The tertiary alkyl primary amines and methods for their
preparation
are known in the art. The tertiary alkyl primary amine useful for the purposes
of this
invention and methods for their preparation are described in US Patent
2,945,749.
Speck secondary amines include dimethylamine, diethylamine, dipropylamine,
3o dibutylamine, diamyiamine, dihexylamine, diheptylamine, methylethylamine,
ethylbutylamine and ethylamylamine. The secondary amines may be cyclic amines
such
as piperidine, piperazine and morpholine.
Dithiocarbamate amide compounds may be prepared by reacting one or more
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dithiocarbamic acids or salts with an unsaturated amide. The reaction products
of
dithiocarbamic acids and salts with unsaturated amides are disclosed in US
Patents
4,758,362 {Butke) and 4,997,969 (Luciani).
Dithiocarbamate ether compounds include reaction products of a dithiocarbamic
acid or
salt with an unsaturated acid, anhydride or ester.
Dithiocarbamate ethers also include reaction products of a dithiocarbamic acid
or salt and
a vinyl ether:-
to
Alkylene coupled dithiocarbamates, useful in the present invention, may be
prepared by
the reaction of a salt of a dithiocarbamic acid with a suitable dihalogen
containing
hydrocarbon. The reaction is generally carried out at a temperature within the
range from
25 up to 150, or up to 100, °C. US Patent 3,876,550 describes alkylene
dithiocarbamate
is compounds, and US Patents 1,726,647 and 1,736,429, describe phenylmethylene
bis(dithiocarbamates) and methods of making them
Bis(S-alkyldithiocarbamoyl) disulfides, or sulfur-coupled dithiocarbamates,
may be
prepared by (A) reacting a sulfur halide with a stoichiometric equivalent of
(l) at least one
20 olefinic hydrocarbon, or (ii) an aldehyde or ketone, at a temperature and
for a period of
time sufficient to produce a di(halohydrocarbyl) sulfide intermediate or a
dialdehyde or
diketo sulfur intermediate, and (B) reacting the intermediate with a salt of a
dithiocarbamate in an amount sufficient generally to replace both halo groups
with the
dithiocarbamate groups or to react with both carbonyl groups of the dialdehyde
or
2s diketone. The sulfur halide utilised in the first step (A) may be sulfur
monochloride (i.e.,
S2CIz), sulfur dichloride, sulfur monobromide, sulfur dibromide, or mixtures
of any of the
above sulfur halides with elemental sulfur in varying amounts.
The bis(S-alkyldithiocarbamoyl) disulfides may also be prepared by a process
which
3o comprises the steps of (A) reacting an olefinic hydrocarbon with a halogen
to produce a
halogen-containing intermediate, and (B) reacting said intermediate with an
alkali metal
sull5de and a salt of a dithiocarbamate in an amount sufficient to replace the
halogen
groups present partially with dithiocarbamate groups andlor partially with
sulfide groups.
The bis(S-alkyldithiocarbamoyl) disulfides are described in US Patent
2,599,350.
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Examples of phosphorous-containing ashless anti-wear additives are phosphoric
acid
esters; phosphates; and phosphorus-containing carboxylic acids, esters,
ethers, or amides.
The phosphorus acids include the phosphoric, phosphoric, phosphinic and
thiophosphoric
acids including dithiophosphoric acids as welt as the monothiophosphoric
acids,
thiophosphinic and thiophosphonic acids.
The phosphorus acid esters may be prepared by reacting one or more phosphorus
acids
or anhydrides with an alcohol containing from one, such as from 3, carbon
atoms. The
to alcohol generally contains up to 30, such as up to 24, such as up to 12,
carbon atoms.
The phosphorus acid or anhydride may generally be an inorganic phosphorus
reagent,
such as phosphorus pentoxide, phosphorus trioxide, phosphorus tetroxide,
phosphoric
acid, phosphorous acid, phosphorus halide, lower phosphorus esters, or a
phosphorus
sulfide, including phosphorus pentasulfide.
Examples of useful phosphorus acid esters include the phosphoric acid esters
prepared
by reacting a phosphoric acid or anhydride with cresol alcohols. An example of
such
phosphorus acid esters is tricresyiphosphate.
2o Monothiophosphates may be prepared by the reaction of a sulfur source with
a
dihydrocarbyl phosphate. The sulfur source may for instance be elemental
sulfur. The
sulfur source may also be a monosulfide, such as a sulfur coupled olefin or a
sulfur
coupled dithiophosphate. Elemental sulfur is a preferred sulfur source. The
preparation of
monothiophosphates is described in US Patent 4,755,311 and PCT Publication
WO 87107638.
The amine salts of the phosphorus acid esters may be formed from ammonia, or
an
amine, including monoamines and polyamines. The amines may be primary amines,
secondary amines or tertiary amines. Useful amines include those amines
disclosed in
3o US Patent 4,234,435 at col. 21, line 4 to col. 27, line 50.
Phosphorus-containing amides may be prepared by the reaction of one of the
above-
described phosphorus acids, preferably a dithiophosphoric acid, with an one of
the above-
described unsaturated amides. The reaction product of the phosphorus acid and
the
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unsaturated amide may be further reacted with a linking or a coupling
compound, such as
formaldehyde or paraformaldehyde. Phosphorus containing amides are known in
the art
and are disclosed in US Patents 4,670,169, 4,770,807 and 4,876,374.
Phosphorus- containing carboxylic esters may be prepared by reaction of one of
the
above-described phosphorus acids, preferably a dithiophosphoric acid, and one
of the
above- described unsaturated carboxylic acids or esters. If a carboxylic acid
is used, the
ester may then be formed by subsequent reaction of the phosphoric acid-
unsaturated
carboxylic acid adduct with an alcohol, such as those described above for
phosphorus
1o acid esters.
Examples of boron-containing ashless anti-wear additives are borate esters,
borated fatty
amines, borated epoxides, and borated phospholipids.
~ s Borated amines may be prepared by reacting one or more of the above boron
compounds,
such as boric acid or borate ester, with a fatty amine, e.g., an amine having
from 4 to 18
carbon atoms.
Borated fatty epoxides are generally the reaction products of one or more of
the above
2o boron compounds with at least one epoxide. The borated fatty epoxides are
generally
known and are disclosed in US Patent 4,584,115.
Borated phospholipids may be prepared by reacting a combination of a
phospholipid and a
boron compound.
2s
Borate esters may be synthesised from the reaction of a boron source, such as
boric acid,
and an alcohol. The alcohol may be a polyol, such as a 1,3-diol and may have
up to 24
carbon atoms, and may contain other atoms, such as sulfur.
3o Further, EP-A-0216909 discloses antiwear agents that are esters of
metaboric acid, and
have the following formula:
11
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(OR')"OR
O~ g \O
RO(R O)~ g' / g (OR )FOR
O
wherein each R independently represents hydrogen or a hydrocarbyl group
containing
from 1 to 18'i;,arbon atoms and each R' independently represents an alkylene
group
containing from 2 to 4 carbon atoms.
Antiwear agents providing both boron and sulfur are disclosed, for example, in
US-A-
3303130 which describes an organo thioalkyl borate antiwear agent of the
general
formula:
O(CH2)~SR
RS(CH2)~O-B~ O(CH2)~SR
1o
wherein R is selected from the group consisting of hydrogen, alkyl, aryl,
alkaryl, aralkyl
and cycloalkyl radicals containing 1 to 16 carbon atoms and n is an integer of
2 to 16,
inclusive. These compounds are formed by reacting a thioalcohol with boric
acid in a
15 molar ratio of at least 3:1, and provide an antiwear additive having a
weight ratio of sulfur
to boron of 3.33:1. Similar compounds formed by reacting an alcohol, a
hydroxysulfide
and a boron compound, and the use thereof as a friction reducer in lubricating
oil
compositions are disclosed in US A-4492640.
2o Preferred examples of suitable borate esters comprising sulfur are those
defined in the
third aspect of the invention hereinbefore.
In formula (I) thereof, it is preferred that R' represents a hydrocarbyl group
having from 6
to 9 carbon atoms, R' represents a hydrocarbyl group having from 2 to 4 carbon
atoms,
25 and that each of !, m and n is 1. More preferably, R' has 6 carbon atoms
and R' has 2
carbon atoms.
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In formula (II) thereof, it is preferred that R' represents a hydrocarbyl
group having from 6
to 9 carbon atoms and R4 represents a hydrocarbyl group having from 2 to 4
carbon
atoms. More preferably, R' has 6 carbon atoms and R' has 2 carbon atoms.
The hydrocarbyl groups may be the same or different and are preferably alkyl
groups.
The above-mentioned borate esters of formulae (I) and (II) may be made as the
product of
a condensation reaction of an alkoxyalkyl sulfide and boric acid in a molar
ratio of at least
to about 1:1. Suitable alkoxyalkyl sulfides are compounds of formula (III):
R'(SR')OH (Ill)
wherein R' and R' are defined as above, and n is an integer from 1 to 4.
Preferable
compounds of formula (III} include hydroxyethyldodecyl sulfide, 1-hydroxy-2-
methyl-3-thio-
~5 decane and hydroxyethyloctyl sulfide (HEOS). The alkoxyalkyl sulfide can
compromise a
single compound or a mixture thereof.
When reacted with boric acid, the alkoxyalkyl sulfide will form a reaction
product that can
include both the compound of formula (I) and the compound of formula (II). The
reaction
2o strongly favours formation of the compound of formula (II) and the reaction
product may, in
fact, contain only insignificant amounts, or essentially no, compound of
formula (I). The
boric acid and hydroxalkyl sulfide are reacted in a molar ratio of about 1:1
or can be
reacted in the presence of a slight molar excess of alkoxyalkyl sulfide (no
greater than
about 2:1 ). The reaction is conducted at a temperature within a range of from
between 60
25 to 120°C, and at a pressure within a range from between -100 to 0,
preferably from
between -70 to -30, kPa.
The boric acid and hydroxalkyl sulfide may be reacted either neat or in an
inert or non-
participating polar solvent. Using hydroxyethyloctyl sulfide (HEOS) and boric
acid
3o reactants as examples, the reaction is believed to proceed as follows:
13
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WO 99/35218 PCT/EP98/08576
OCZH~SCBH~~
O~~i O
a
3CeH~7SC2H40H + 3H3B03 11o.3kPa C8H17SC2H4~B~ p..," jpC2H4SCgH~~ gH20
The borate ester may also be derived from glycerol, boric acid and a fatty
acid having 8-24
carbon atoms, and may, for example, have one or more of the following
formulae:
X - CH2
CH2-Y
HC - O~ ~ (II)
B-O-CH
H2C _ O ~
CH2 - Z
X - CH2 CH2 - Y
(III)
HC-O~ ~ H-Z
B-O-CHz
H2C-O~
X - CH2
HC - O ~ (IV)
B-OH
H2C - O ~
where X, Y and 2 are the same or different and each represents a group
selected from the
1o group consisting of a hydroxyl group and an alkylcarboxyl group of formula -
OCOR where
R represents a straight chain or branched chain alkyl group of 7-23 carbon
atoms which
may be saturated or unsaturated.
Dithiocarbamates salts of boron, such as boron trisdithiocarbamates, are also
ashless
anti-wear additives of the present invention.
The ashless anti-wear additive may be present in an amount of at least 0.01,
preferably at
14
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WO 99/35218 PCT/EP98108576
least 0.1, such as in the range of from 0.1 to 10, mass %, based on the mass
of the
lubricant composition.
(B) METAL DETERGENTS
The metal detergents, including detergents (B) (ii), may be overbased and may
include
alkali metal and alkaline earth metal additives such as overbased oil-soluble
or oil-
dispersible calcium, magnesium, sodium or barium salts of a surfactant
selected from
1o phenol, sulfonic acid, carboxylic acid, salicylic acid and naphthenic acid,
wherein the
overbasing is provided by an oil-insoluble salt of the metal, e.g. carbonate,
basic
carbonate, acetate, formats, hydroxide or oxalate, which is stabilised by the
oil-soluble salt
of the surfactant. The metal of the oil-soluble surfactant salt may be the
same as or
different from the metal of the oil-insoluble salt. Preferably the metal,
whether the metal of
is the oil-soluble or oil-insoluble salt, is calcium. Detergent B (ii) may be
neutral.
The metal detergent may have a TBN of at least 200, preferably at least 250,
especially at
least 300, such as up to 600, with reference to detergents (B) (i) and (B)
(ii) as
appropriate.
Most preferably detergents B (i) have a TBN of at least 350 such as in the
range of from
400 to 600, such as up to 500.
Surfactants for the surfactant system of the overbased metal compounds
preferably
contain at feast one hydrocarbyl group, for example, as a substituent on an
aromatic ring.
Advantageously, hydrocarbyf groups in surfactants for use in accordance with
the
invention are aliphatic groups, preferably alkyl or alkylene groups,
especially alkyl groups,
which may be linear or branched. The total number of carbon atoms in the
surfactants
3o should be at least sufficient to impart the desired oil-solubility.
Phenols for use in this invention may be non-sulfurised or, preferably
sulfurised. Further,
the term "phenol" as used herein includes phenols containing more than one
hydroxyl
group (for example, alkyl catechols) or fused aromatic rings (for example,
alkyl naphthols)
CA 02315707 2000-06-20
WO 99135218 PCTIEP98/08576
and phenols which have been modified by chemical reaction, for example,
alkylene-
bridged phenols and Mannich base-condensed phenols; and saligenin-type phenols
(produced by the reaction of a phenol and an aldehyde under basic conditions).
Preferred phenols may be ~ferived from the formula
OH
Ry
where R represents a hydrocarbyl group anc! y represents 1 to 4. Where y is
greater than
to 1, the hydrocarbyl groups may be the same or different.
In lubricating oil overbased metal compounds, the phenols are frequently used
in
sulfurised form. Sulfu~ised hydrocarbyl phenols may typically be represented
by the
formula:
OH OH
\ Sx \
Ry Ry
where x is generally from 1 to 4. In some cases, more than two phenol
molecules may be
linked by Sx bridges.
In the above formulae, hydrocarbyl groups represented by R are advantageously
alkyl
groups, which advantageously contain 5 to 100, preferably 5 to 40, especially
9 to 12,
carbon atoms, the average number of carbon atoms in all of the R groups being
at least 9
to ensure adequate solubility in oil. Preferred alkyl groups are nonyl
(trypropylene) groups.
In the following discussion, hydrocarbyl-substituted phenols will for
convenience be
referred to as alkyl phenols.
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WO 99I35Z18 PCT/EP98108576
A sulfurising agent for use in preparing a sulfurised phenol or phenate may be
any
compound or element which introduces -(S)x bridging groups between the alkyl
phenol
monomer groups, wherein x is generally from 1 to about 4. Thus, the reaction
may be
conducted with elemental sulfur or a halide thereof, for example, sulfur
dichloride or, more
preferably, suffur monochloride. If elemental sulfur is used, the
sulfurisation reaction may
be effected by heating the alkyl phenol compound at from 50 to 250, preferably
at least
100, °C. The use of elemental sulfur will typically yield a mixture of
bridging groups -(S)x-
as described' above. If a sulfur halide is used, the sulfurisation reaction
may be effected
~o by treating the alkyl phenol at from -10 to 120, preferably at least 60,
°C. The reaction
may be conducted in the presence of a suitable diluent. The diluent
advantageously
comprises a substantially inert organic diluent, for example mineral oil or an
alkane. In
any event, the reaction is conducted for a period of time sufficient to effect
substantial
reaction. It is generally preferred to employ from 0.1 to 5 moles of the alkyl
phenol
t 5 material per equivalent of suffurising agent.
Where elemental sulfur is used as the sulfurising agent, it may be desirable
to use a basic
catalyst, for example, sodium hydroxide or an organic amine, preferably a
heterocyclic
amine (e.g., morpholine).
Details of sulfurisation processes are well known to those skilled in the art.
Regardless of the manner in which they are prepared, sulfurised alkyl phenols
useful in
preparing overbased metal compounds generally comprise diluent and unreacted
alkyl
phenols and generally contain from 2 to 20, preferably 4 to 14, most
preferably 6 to 12,
mass % sulfur based on the mass of the sulfurised alkyl phenol.
Aldehydes with which phenols may be modified include, for example,
formaldehyde,
propionaldehyde and butyraldehyde. The preferred aldehyde is formaldehyde.
Aldehyde-
3o modified phenols suitable for use are described in, for example, US-A-5 259
967.
Mannich base-condensed phenols are prepared by the reaction of a phenol, an
aldehyde
and an amine. Examples of suitable Mannich base-condensed phenols are
described in
GB-A-2 121 432.
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WO 99!35218 PCT/EP98/08576
In general, the phenols may include substituents other than those mentioned
above
provided that such substituents do not detract significantly from the
surfactant properties of
the phenols. Examples of such substituents are methoxy groups and halogen
atoms.
Salicylic acids used in accordance with the invention may be non-sulfurised or
sulfurised,
and may be chemically modified and/or contain additional substituents, for
example, as
discussed above for phenols. Processes similar to those described above may
also be
used for sulfiuising a hydrocarbyl-substituted salicylic acid, and are well
known to those
to skilled in the art. Salicylic acids are typically prepared by the
carboxylation, by the Kolbe-
Schmitt process, of phenoxides, when they will generally be obtained (normally
in a
diluent) in admixture with uncarboxylated phenol.
Preferred substituents in oil-soluble salicylic acids from which overbased
detergents in
15 accordance with the invention may be derived are the substituents
represented by R in the
above discussion of phenols. In alkyl-substituted salicylic acids, the alkyl
groups
advantageously contain 5 to 100, preferably 9 to 30, especially 14 to 20,
carbon atoms.
Sulfonic acids used in accordance with the invention are typically obtained by
sulfonation
20 of hydrocarbyl-substituted, especially alkyl-substituted, aromatic
hydrocarbons, for
example, those obtained from the fractionation of petroleum by distillation
andlor
extraction, or by the alkylation of aromatic hydrocarbons. Examples include
those
obtained by alkylating benzene, toluene, xylene, naphthalene, biphenyl or
their halogen
derivatives, for example, chlorobenzene, chlorotoluene or chloronaphthalene.
Alkylation
25 of aromatic hydrocarbons may be carried out in the presence of a catalyst
with alkylating
agents having from 3 to more than 100 carbon atoms, such as, for example,
haloparaffins,
olefins that may be obtained by dehydrogenation of paraffins, and polyolefins,
for example,
polymers of ethylene, propylene, and/or butene. The alkylaryl sulphonic acids
usually
contain from 7 to 100 or more carbon atoms. They preferably contain from 16 to
80, or 12
3o to 40, carbon atoms per alkyl-substituted aromatic moiety, depending on the
source from
which they are obtained.
When neutralising these alkyiaryl sulfonic acids to provide sulfonates,
hydrocarbon
solvents andlor diluent oils may also be included in the reaction mixture, as
well as
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WO 99I3SZ18 PCT/EP98/08576
promoters and viscosity control agents.
Another type of sulfonic acid which may be used in accordance with the
invention
comprises alkyl phenol sulfonic acids. Such sulfonic acids can be sulfurised.
Whether
sulfurised or non-sulfurised, these sulfonic acids are believed to have
surfactant properties
comparable to those of suifonic acids, rather than surfactant properties
comparable to
those of phenols.
Sulfonic acids suitable for use in accordance with the invention also include
alkyl sulfonic
to acids, such as alkenyl sulfonic acids. In such compounds the alkyl group
suitably contains
9 to 100, advantageously 12 to 80, especially 16 to 60, carbon atoms.
Carboxylic acids which may be used in accordance with the invention include
mono- and
dicarboxylic acids. Preferred monocarboxylic acids are those containing 1 to
30, especially
t5 8 to 24, carbon atoms. (Where this specification indicates the number of
carbon atoms in
a carboxylic acid, the carbon atoms) in the carboxylic groups) is/are included
in that
number.) Examples of monocarboxylic acids are iso-octanoic acid, stearic acid,
oleic acid,
palmitic acid and behenic acid. Iso-octanoic acid may, if desired, be used in
the form of
the mixture of CB acid isomers sold by Exxon Chemical under the trade name
"Cekanoic"
2o (RTM). Other suitable acids are those with tertiary substitution at the
a-carbon atom, and dicarboxylic acids with more than 2 carbon atoms separating
the
carboxylic groups. Further, dicarboxylic acids with more than 35, for example,
36 to 100,
carbon atoms, are also suitable. Unsaturated carboxylic acids can be
sulphurised.
Although salicylic acids contain a carboxylic group, for the purposes of the
present
25 specification they are considered to be a separate group of surfactants,
and are not
considered to be carboxylic acid surfactants. (Nor, although they contain a
hydroxyl
group, are they considered to be phenol surfactants.)
Examples of other surfactants which may be used in accordance with the
invention include
3o the following compounds, and derivatives thereof: naphthenic acids,
especially
naphthenic acids containing one or more alkyl groups, dialkylphosphonic acids,
dialkylthiophosphonic acids, and dialkyldithiophosphoric acids, high molecular
weight
(preferably ethoxyiated) alcohols, dithiocarbamic acids, thiophosphines, and
dispersants.
Surfactants of these types are well known to those skilled in the art.
Surfactants of the
19
CA 02315707 2000-06-20
WO 99135218 PCTlEP98108576
type hydrocarbyl-substituted carboxylalkylene-linked phenols, or dihydrocarbyl
esters of
alkylene dicarboxylic acids, the alkylene group being substituted with a
hydroxy group and
an additional carboxylic acid group, or alkylene-linked polyaromatic
molecules, the
aromatic moieties whereof comprise at least one hydrocarbyl-substituted phenol
and at
least one carboxy phenol, may also be suitable for use in the present
invention; such
surfactants are described in EP-A-708171.
Also suitable for use in the present invention are overbased metal compounds,
preferably
overbased calcium detergents, that contain at least two surfactant groups,
such as phenol,
1o sulfonic acid, carboxylic acid, salicylic acid and naphthenic acid, that
may be obtained by
manufacture of a hybrid material in which two or more different surfactant
groups are
incorporated during the overbasing process.
Examples of hybrid materials are an overbased calcium salt of surfactants
phenol and
~s sulfonic acid; an overbased calcium salt of surfactants phenol and
carboxylic acid; an
overbased calcium salt of surfactants phenol, sulfonic acid and salicylic
acid; and an
overbased calcium salt of surfactants phenol and salicylic acid.
By an "overbased calcium salt of surfactants" is meant an overbased detergent
in which
2o the metal cations of the oil-insoluble metal salt are essentially calcium
cations. Small
amounts of other rations may be present in the oil-insoluble metal salt, but
typically at
least 80, more typically at least 90; for example at least 95, mole °r6
of the rations in the
oil-insoluble metal salt are calcium ions. Cations other than calcium may be
derived, for
example, from the use in the manufacture of the overbased detergent of a
surfactant salt
25 in which the ration is a metal other than calcium. Preferably, the metal
salt of the
surfactant is also calcium.
Where detergent (B) (ii) comprises at least two overbased metal detergents,
any suitable
proportions by mass may be used; preferably the mass to mass proportion of any
one
30 overbased metal detergent to any other overbased metal detergent is in the
range of from
5:95 to 95:5, such as from 90:10 to 10:90, more preferably from 20:80 to
80:20, especially
from 70:30 to 30:70, advantageously from 60:40 to 40:60.
Particular examples of hybrid materials include:
CA 02315707 2000-06-20
WO 99/35218 PCT/EP98/08576
l) an overbased calcium detergent comprising a surfactant system derivable,
and preferably derived, from at least two surfactants, at least one of which
is a phenol or a derivative thereof and the other, or at least one other, of
which is a surfactant other than a phenol surfactant, the proportion,
measured as described herein, of said phenol in the surfactant system
being at /east 10 mass % and the overbased detergent having a TBN:%
surfactant ratio (as hereinafter defined) of at least 10.
is Independently of the TBN:% surfactant ratio, the proportion of phenol in
the
surfactant system is at least 20, preferably at least 40, more preferably at
least 45, such as in the range of from 50 to 90, mass %. Independently of
the phenol proportion, the TBN:°~ surfactant ratio is at least 11,
preferably
at least 14, more preferably at least 16, advantageously at least 16,
~ s especially at least 19, more especially at least 21, for example at least
25,
such as up to 30 or more, or up to 40 or more.
ii) an overbased calcium detergent comprising a surfactant system derivable,
and preferably derived, from at least two surfactants, at least one of which
2o is a salicylic acid or a derivative thereof, and the other, or at least one
other,
of which is a surfactant other than a salicylic acid surfactant, the
proportion,
measured as described herein, of the said salicylic acid in the surfactant
system being at least 10 mass %, and the overbased detergent having a
TBN:% surfactant ratio (as hereinafter defined) of at least 10.
Independently of the TBN:°~ surfactant ratio, the proportion of
salicylic acid
in the surfactant system is at least 20, preferably at least 30, more
preferably at least 45, such as in the range of from 50 to 90, mass %.
Independently of the salicylic acid proportion, the TBN:% surfactant ratio is
3o at least 11, preferably at least 14, more preferably at least 16,
advantageously at least 18, especially at least 19, more especially at least
21, for example at least 25, such as up to 30 or more, or up to 40 or more.
iii) an overbased calcium detergent comprising a surfactant system derivable,
21
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WO 99!35218 PCT/EP98/08576
and preferably derived, from phenol and sulfonic acid, the proportions,
measured as described herein, of phenol to sulfonic acid in the surfactant
system being in the range of from 15:85 to 95:15, preferably 30:70 to 70:30,
especially 40:60 to 60:40, mass %; and the TBN:% surfactant ratio (as
hereinafter defined) of at least 15, preferably at least 17, especially 19 or
more.
iv) an overbased calcium detergent comprising a surfactant system derivable,
and preferably derived, from phenol, salicylic acid and sulfonic acid, the
proportions, measured as described herein, of phenol to salicylic acid to
sulfonic acid in the surfactant system being in the range of from 5 to 90:
to 90: 20 to 80; preferably 20 to 80: 20 to 80:10 to 50; more preferably 30
to 50: 25 to 50: 15 to 35, mass %: mass %: mass % and the TBN:%
surfactant ratio (as hereinafter defined) of at least 10, preferably at least
12,
~ 5 especially 14 or more.
Typically, the amount of overbased metal compound in a lubricant composition
is at least
0.5, particularly in the range of from 0.5 to 20, such as from 3 to 12 or 2 to
7, mass
active ingredient, based on the mass of the composition.
The overbased metal compounds of the present invention may be borated;
typically the
boron-contributing compound, e.g. the metal borate, is considered to form part
of the
overbasing.
The percentage of surfactant in the overbased calcium detergent, and the
percentages of
the individual surfactants, for example, phenol, in the surtactant system, are
the
percentages measured by the method set out below.
1. Dialysis of the overbased detergent
A known amount {A g, approximately 20 g) of the liquid overbased calcium
detergent
compound (substantially free from other lubricating oil additives) is dialysed
through a
membrane in a Soxhlet extractor (150 mm height x 75 mm internal diameter)
using n-
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CA 02315707 2000-06-20
WO 99135218 PCT1EP98/08576
hexane siphoning at a rate of 3 to 4 times per hour for 20 hours. The membrane
should
be one which retains substantially all the metal-containing material, and
passes
substantially all the remainder of the sample. An example of a suitable
membrane is a
gum rubber membrane supplied by Garters Products, Division of Carter Wallace
Inc., New
s York, NY 10105 under the trade name Trojans. The dialysate and residue
obtained on
completion of the dialysis step are evaporated to dryness, any remaining
volatile material
then being removed in a vacuum oven (100°C at less than 1 ton- or less
than about 130
Pa). The mass of the dried residue, in grams, is designated B. The percentage
(C) of
overbased detergent material in the liquid sample is given by the equation:
to
C=8 x100%
A
Background information for the dialysis technique is given by Amos, R. and
Albaugh, E.W.
in "Chromatography in Petroleum Analysis", Altgelt, K.H. and Gouw, T.H., Eds,
pages 417
is to 422, Marcel Dekker, Inc., New York and Basel, 1979.
2. Determination of TBN : % total surfactant ratio
2o A known amount (D g, approximately 10 g) of the dried residue is hydrolysed
as specified
in sections 8.1 to 8.1.2 of ASTM D3712, except that at least 200 ml of 25 % by
volume
hydrochloric acid (sp. gr. 1.18) is used in section 8.1.1. The amount of
hydrochloric acid
used should be sufficient to effect acidification/hydrolysis of the overbased
detergent
residue into organic materials (surfactants) and inorganic materials (calcium-
containing
25 materials, for example, calcium chloride). The combined ether extracts are
dried by
passing them through anhydrous sodium sulphate. The sodium sulphate is rinsed
with
clean ether, and the combined ether solutions are evaporated to dryness (at
approximately 110°C) to yield a hydrolysed residue. The mass of the
dried hydrolysed
residue, in grams, is designated E.
The percentage, Y, of total surfactants in the original liquid overbased
detergent is given
by the equation
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WO 99/35218 PCTIEP98108576
Y=~ xC
and the TBN : % total surfactant ratio, X, is given by the equation
X = TBN of the liquid overbased detergent
Y
It will be noted that, in determining X, the mass of the surfactants in their
free form (that is,
not in the form of a salt or other derivative) is used.
to
3. Determination of individual surfactants (in their free form) in the
surfactant system
The techniques described below isolate the individual surfactants, in
hydrolysed form, from
the hydrolysed surfactant mixture derived from the overbased detergent. As
indicated
15 below, the proportion of each individual surfactant is the proportion by
mass of the
individual surfactant, in hydrolysed form, in the hydrolysed surfactant
mixture. Thus,
where, for example, the overbased detergent contains a calcium
phenate/sulphonatelsalicylate surfactant system, the proportions of the
individual
surfactants in the surfactant system are expressed as the proportions of
phenol, sulphonic
2o acid and salicylic acid respectively
The proportions of individual surfactants may be determined by the following
method.
A known amount (F g, approximately 1 g) of the dried hydrolysed residue
obtained as
25 described above is placed at the top of a 450 x 25 mm (internal diameter)
fritted glass
column filled with 60-100 US mesh Florisil. Florisil is magnesium silicate
with a CAS
number of 8014-97-9. The column is eluted with a 250 ml portion of each of
seven
solvents of increasing polarity, namely, heptane, cyclohexane, toluene, ethyl
ether,
acetone, methanol, and, lastly, a mixture of 50 volume % chloroform, 44 volume
3o isopropanoi, and 6 volume % ammonia solution (sp. gr. 0.88). Each fraction
is collected,
evaporated to dryness, and the resulting residue is weighed and then analysed
to
determine the amount (G', G~, G' ... g) and nature of the surfactants)
contained in the
fraction.
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WO 99/35218 PCT/EP98I08576
Analysis of the fractions (or of the hydrolysed residue) can be carried out
by, for example,
chromatographic, spectroscopic, andlor titration (colour indicator or
potentiometric)
techniques known to those skilled in the art. Where the overbased detergent
contains a
sulphonate surfactant and a salicylate surfactant, the sulphonic acid and
salicylic acid
obtained by hydrolysis of these surfactants will usually be eluted from the
column together.
In this case, and in any other case where it is necessary to determine the
proportion of
sulphonic acid in a mixture containing it, the proportion of sulphonic acid in
the mixture can
be determinqd by the method described by Epton in Trans.Far.Soc. April 1948,
226.
m
In the above method, the mass (in grams, designated H') of a given surfactant,
in
hydrolysed form, is determined from the fractions) containing it, and thus the
proportion of
that surfactant in the surfactant system of the original overbased detergent
is
~ s F x 100%
The percentages (by mass) of the individual surfactants (in their free form,
that is, not in
the form of a salt or other derivative) based on the surfactant system can be
predicted
from the proportions of the surfactants used as starting materials, provided
that the
2o percentage of 'reactive ingredient' (r.i.) is known for each of the
surfactant starting
materials. The percentage of the total surfactants (in their free form) in the
liquid
overbased product can then be predicted, and the TBN : % surfactant ratio can
be
determined. As used herein, the term 'reactive ingredient' is the percentage
by mass of
surfactant that will be associated with the metal calcium.
2s
CO-ADDITIVES
The marine diesel engine lubricant compositions may also contain other
additives, for
example dispersants, antioxidants, antifoaming agents andlor rust inhibitors
as well as
ash-forming antiwear additives, such as known in the art.
Other co-additives may include pour point depressants, otherwise known as tube
oil flow
improvers, which lower the minimum temperature at which the fluid will flow or
can be
poured and antifoamants of the polysiloxane type, for example, silicone oil or
polydimethyl
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CA 02315707 2000-06-20
WO 99135218 PCTIEP98/08576
siloxane, to provide foam control.
Typical proportions for additives for a TPEO (a trunk piston engine oil) are
as follows:
26
CA 02315707 2000-06-20
WO 99135218 PCTIEP98/08576
Additive Mass % a.i Mas8 % a.i
*
(Broad) (Preferred)
Detergents) 0.5-12 2-8
Dispersant(s) 0.5-5 1-3
Ashless Anti-wear agents) 0.1-1.5 0.5-1.3
Oxidation inhibitor 0.2-2 0.5-1.5
Rust inhibitor 0.03-0.15 0.05-0.1
Pour point depressant 0.03-0.15 0.05-0.1
Mineral or synthetic base Balance Balance
oil
* Mass % active ingredient based on the final oil.
Typical proportions for additives for a MDCL (a marine diesel cylinder
lubricant) are as
follows:
Additive Mass % a.L Mass % a.i
*
(Broad) (Preferred)
Detergents) 1-20 3-15
Dispersant(s) 0.5-5 1-3
Ashless Anti-wear agents) 0.1-1.5 0.5-1.3
Pour point depressant 0.03-0.15 0.05-0.1
Mineral or synthetic base Balance Balance
oil
* Mass % active ingredient based on the final oil.
~o
EXAMPLES
The present invention is illustrated by, but in no way limited to, the
following examples.
t5
Test Method
The test method used was that described in 'Wear', 1996, 196, 207-213, and
closely
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WO 99/35218 PCT/EP98/08576
simulates wear mechanisms in the piston ring and cylinder liner areas of cross-
head diesel
engines.
Briefly described, the test is carried out using a pin-on-disc wear machine,
using pins of
s diameter of 8 mm, giving a total contact area of 50.2 mmz. A new pin
geometry is
employed to allow conformai surface contact between the pin and disc.
A camping (step) test technique on the pin-on-disc machine was employed to
identify
transition pressures from mild to severe wear under boundary lubrication.
Tests were
to carried out at sliding velocities of 0.5 and 2.0 mls at room temperatures
(20°C), and 2.0
mls at 250°C disc temperatures. Daros RM4 grey cast iron piston ring
materials were
used as pins, tested against GG25 B+P grey cast iron (Table 1 ). Tests begin
by applying
a load of 100 N on the pin and lubricant mist on the wear track. This
represents a
pressure of 2.0 Nlmm2 on the pin with contact area of 50.26 mmz. Load is then
increased
~s at regular intervals representing 600m of sliding until transition from
mild to severe wear
takes place at which point the test is terminated. For the given test
velocities the sliding
interval is adequate to achieve a steady state.
Transition can be noted by an increase in frictional energy (i.e. frictional
force, heat,
2o vibration and noise). Furthermore, at this point the oxidative feature of
the wear track
changes locally to metallic. Tests are conducted under boundary lubrication
(i.e.
0.1 s p. z 0.3). Using a pneumatic oil mister, the coefficient of friction is
controlled during
the starting stages of the test (during oxidative wear regime). Oil mist
application can be
regulated to achieve a steady state condition. The coefficient of friction
remains constant
25 under these conditions until transition from mild to severe wear occurs.
The oil mist
pressure, duration and intervals are adjustable and dependent on the lubricant
characteristics. Table 1 shows the camping test details.
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WO 99/35218 PCT/EP98/08576
Table 1 - Parameters for Ramping Tests
Wear Type Type: Pin-on-disc
Pin Material: Daros RM4 piston ring (Ra = 0.1 Vim)
Pin Surface Area = 50.2 mmz
(Standard NSD RTA piston ring material)
Disc Material: GG25 B+P (Standard NSD liner material)
Applied Load: Ramping, 100N up to transition ( a'L'~
100N intervals)
Ramp Interval: 600 m of sliding
Sliding Velocity: 0.5 and 2.0 mls
Starting Disc Temperature20C and 250C
Total Sliding Time: Depends on materials and lubricant
Lubricant Mist Dosage RT: 0.45 mglmin.
HT: 2 mg/min.
Daros RM4 piston ring is a standard W~rtsil~ NSD RTA piston ring material.
GG25 B+P is a standard W~rtsilfi NSD liner material.
Components
to
A 410 TBN calcium detergent (P) was prepared as follows.
Toluene (selected from the range of from 350-540 g), methanol (selected from
the range
of from 270-330 g), and water (selected from the range of from 15-26 g) were
introduced
t5 into a reactor and mixed while maintaining the temperature at approximately
20°C. Diluent
oil (11g) was also added and the mixture maintained at 20°C. Calcium
hydroxide
(Ca(OH)2) (71 g) was added, and the mixture was heated to 40°C, with
stirring. To the
slurry obtained in this way was added a mixture, maintained at 40°C, of
phenol, sulphonic
acid, and toluene (100 g), followed by a further quantity (50 g) of toluene.
After neutralisation of the surfactants by the calcium hydroxide, the
temperature of the
mixture was reduced to approximately 28°C and was maintained at
approximately 28°C
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WO 99/35218 PCT/EP98/08576
while carbon dioxide (31 g) was injected into the mixture at a rate such that
substantially
all the carbon dioxide was absorbed in the reaction mixture to form the basic
material.
The temperature was then raised to 60°C over 60 minutes, following
which the mixture
was cooled to a temperature of approximately 28°C over 30 minutes. At
28°C, a further
quantity of calcium hydroxide (63 g) was added and carbon dioxide (31 g) was
charged.
After this second carbonation step, the temperature was raised to 60°C
over 90 minutes.
Subsequently, the polar solvents were distilled off and the product was
filtered to remove
sediment. The remaining volatile material was then distilled off and difuent
oil (122 g) was
to added.
The phenol used in the preparation above is a sulphurised alkyl phenol,
synthesised from
sulphur monochloride and a 65!35 (by mass) blend of tertiary nonyl
(tripropylene) phenols
(predominantly para-substituted) and tertiary dinonyl phenols (predominantly
2,4-
15 substituted) (a.i. = 84; r.i. = 40); and the sulfonic acid used in the
preparation above is an
alkyl benzene sulfonic acid derived from S03 (in liquid S02) with a molecular
mass of fi83
(a.i. = 96; r.i. = 84).
The phenol and sulfonic acid were used in suitable quantities to obtain an
overbased
2o metal compound having a TBN of 410 and TBN:% surfactant ratio of 20.
The sulfur-containing borate ester (Q) was prepared as follows.
In a 5 liter, three neck flask, of hydroxyethyloctyl sulfide (22808; 12 mol)
and boric acid
25 powder (7448; 12 mol) were combined. The flask was equipped with a stirrer,
a
thermometer and a condenser connected to vacuum. The flask was heated to
110°C, and
pressure within the flask reduced to -70kPa. After a few minutes water began
to evolve.
The temperature in the flask was allowed to fall to 100°C at which
point heating was
terminated and the exothermic reaction proceeded unassisted until water (2
molar
3o equivalents) evolved and was collected. Heat was then applied until water
(one additional
molar equivalent) evolved and was collected.
The product was characterized by a combination of analytical techniques. HP~C
separation analysis showed that one primary species was formed. "C NMR
Spectroscopy
CA 02315707 2000-06-20
WO 99135218 PCT/EP98108576
indicated that the material had a characteristic sharp single resonance
associated with a
borated alkoxy methylene carbon at 62.8(1C) ppm relative to TMS. "B NMR
Spectroscopy showed only one boro-oxygen ester signal at -3 ppm relative to
H3BO3. The
simplicity of the carbon and boron NMR spectral result was indicative of a
highly
s symmetric meta-boroester structure. Characteristic carbon signals associated
with the
incorporation of hydroxyethyloctyi sulfide were found at 33(1C), 31.8(1C),
31.2(1C),
29.6(1 C), 28.8(1 C), 28.6(1C), 22.4(1C) and 13.6(1C).
A phosphorus-containing ashless anti-wear additive (R) in the form of PARABAR
(RTM)
l0 9450 additive, which is a commercially available ashless
diaryldithiophosphate derivative.
Description of Oils
I5 A - A lubricant composition containing base oil and of the order of 1.78
mass % of a
commercially available zinc dialkyldithiophosphate (ZDDP).
B - A lubricant composition containing base oil, borated dispersant, 250 TBN
calcium
phenate and 300 TBN calcium sulfonate, the TBN and viscosity index of the
20 lubricant composition being 72 and 95 respectively.
C - A set of lubricant compositions each containing base oil, borated
dispersant and
the 410 TBN calcium detergent (P) and having a TBN of 72. The viscosity index
of
the lubricant compositions varied between 110 and 116.
1 - A lubricant composition containing base oil, additives of Example B and
the sulfur-
containing borate ester (Q) in an amount of 2.0 mass %. The TBN and viscosity
index of the lubricant composition were 72 and of the order of 95
respectively.
2 - A lubricant composition containing base oil, additives of Example C and
the sulfur-
containing borate ester {Q) in an amount of 2.0 mass %. The TBN and viscosity
index of the lubricant composition were 72 and of the order of 113
respectively.
3 - A lubricant composition containing base oil, additive of Example C and the
additive
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CA 02315707 2000-06-20
WO 99135218 PCTIEP98/08576
R in an amount of 1.60 mass %.
Oils A-C and 1-3 were tested on the pin-on-disc wear machine and the results
are shown
in Table 2. Transition pressure is a measure of the pressure at which the
transition from a
low to a high wear regime takes place and its values are taken as an
indication of good
wear control, i.e. higher values indicate better wear control.
Table 2
io
Trans ition Pressure,
Nlmms
Disc COnditiOn8 20CI 20CI 250CI
0.5 ms'' 2.0 ms'' 2.0 ms''
Comparative Examples
A -~'~ 15.7
B 27.2~a~ 14.0~'~ 12.8~
C 32.5~ 17.24~ 11.34(~
Examples of the Present
I nvention
1 75 29 36m
2 62.5~n 32.5 25.2~a
3 60 43.5 23.5
(a) No measurement taken.
(b) Average of five measurements.
(c) Average of four measurements.
i 5 Average of thirteen measurements.
(d)
(e) Average of eleven measurements.
(f) Average of two measurements.
(g) Average of three measurements.
2o Comparative Example A shows the transition pressure of a composition
containing ZDDP,
a metal-containing antiwear additive.
Comparing Example 1 and Example B, transition pressure, hence wear control, is
better in
Example 1 in all three conditions of the test, including the high
temperaturelspeed stage
25 {250°C and 2.0 ms'). This suggests that the addition of the ashless
antiwear additive
alone has improved the wear control of the lubricating oil.
A similar trend is observed for Examples 2 and 3 in comparison with Example C:
the
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WO 99/35218 PCT/EP98/08576
transition pressure is better on addition of the ashless antiwear additive.
Further, Examples 2 and 3 show good wear control when high TBN overbased metal
compounds are used.
Also, Examples 1 and 3 reveal improved transition pressures over the
comparative
Example A which contained ZDDP.
33
