Note: Descriptions are shown in the official language in which they were submitted.
=
MARINE ENGINE LUBRICATING OIL COMPOSITION COMPRISING AN
OIL-SOLUBLE ESTER BASESTOCK AND AN OIL-SOLUBLE
POLYALKENYL-SUBSTITUTED CARBOXYLIC ACID ANHYDRIDE
FIELD OF THE INVENTION
This invention relates to a trunk piston marine engine lubricating composition
for a medium-speed four-stroke compression-ignited (diesel) marine engine and
lubrication of
such an engine.
BACKGROUND OF THE INVENTION
Marine trunk piston engines generally use Heavy Fuel Oil ('HF0') for offshore
running. Heavy Fuel Oil is the heaviest fraction of petroleum distillate and
comprises a
complex mixture of molecules including up to 15% of asphaltenes, defined as
the fraction of
petroleum distillate that is insoluble in an excess of aliphatic hydrocarbon
(e.g. heptane) but
that is soluble in aromatic solvents (e.g. toluene). Asphaltenes can enter the
engine lubricant
as contaminants either via the cylinder or the fuel pumps and injectors, and
asphaltene
precipitation can then occur, manifested in 'black paint' or 'black sludge' in
the engine. The
presence of such carbonaceous deposits on a piston surface can act as an
insulating layer that
can result in the formation of cracks that then propagate through the piston.
If a crack travels
through the piston, hot combustion gases can enter the crankcase, possibly
resulting in a
crankcase explosion.
It is therefore highly desirable that trunk piston engine oils (`TPEO's)
prevent or inhibit
asphaltene precipitation. TPEO' s using Group 1 basestocks may have the
ability to solubilise
asphaltenes. However, TPEO's using high saturate basestocks (e.g. Group II or
III) require a
booster to achieve similar performance levels in this respect.
WO 2010/115594 ("594") and WO 2010/115595 ("595") describe the use, in trunk
piston marine engine lubricating oil compositions that contain 50 mass % or
more of a Group
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II basestock, of respective minor amounts of a calcium salicylate detergent
and of a
polyalkenyl-substituted carboxylic and anhydride. The data in "594" and "595"
show that the
combination gives rise to improved asphaltene dispersancy.
US 2011/0319304 Al ('304) describes the use of ester basestock in a high
saturates
basestock TPEO to improve asphaltene dispersancy.
A problem in the art is to improve still further the asphaltene dispersancy
performance
of TPEO's that employ high saturate basestocks.
SUMMARY OF THE INVENTION
The invention meets the above problem by employing an anhydride and an ester
in a
TPEO: a synergistic effect is observed as demonstrated in the data herein.
A first aspect of the invention is a trunk piston marine engine lubricating
oil composition
for improving asphaltene handling in use thereof in operation of the engine
when fuelled by a
heavy fuel oil, which composition comprises or is made by admixing
(A) an oil of lubricating viscosity, in a major amount, which is either an oil-
soluble
ester basestock (Al); or comprises greater than 0.1 to less than 90 mass %,
preferably greater than 1 to less than 80 mass%, of an oil-soluble ester
basestock
(Al) and, as 50 mass % or more of the remainder of the oil of lubricating
viscosity,
a basestock containing greater than or equal to 90% saturates and less than or
equal
to 0.03 % sulphur or a mixture thereof (A2);
(B) an oil-soluble metal detergent, in a minor amount; and
(C) an oil-soluble polyalkenyl-substituted carboxylic acid anhydride, in a
minor amount
of from greater than 0.1 to less than 10 mass %, preferably greater than 1 to
less than
2
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8 mass%, the, or at least one, polyalkenyl group being derived from polyalkene
having a number average molecular weight of from 200 to 3000.
The ester basestock (Al) is present in an amount of 10 to 90, such as 20 to
90, such as
30 to 90, mass %.
A second aspect of the invention is a method of operating a trunk piston
medium-
speed compression-ignited marine engine comprising
(i) fuelling the engine with a heavy fuel oil; and
(ii) lubricating the crankcase of the engine with a composition according
to the
first aspect of the invention.
A third aspect of the invention is a method of dispersing asphaltenes in a
trunk piston
marine lubricating oil composition during its lubrication of surfaces of the
combustion chamber
of a medium-speed compression-ignited marine engine and operation of the
engine, which
method comprises:
(i) providing a composition according to the first aspect of the invention;
(ii) providing the composition in the combustion chamber;
(iii) providing heavy fuel oil in the combustion chamber; and
(iv) combusting the heavy fuel oil in the combustion chamber.
A fourth aspect of the invention is the use of detergent (B) in combination
with
component (C) as defined in and in the amounts stated in the first aspect of
the invention in a
trunk piston marine lubricating oil composition for a medium-speed compression-
ignited
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marine engine, which composition comprises an oil of lubricating viscosity (A)
in a major
amount as defined in the first aspect of the invention, to provide comparable
or improved
asphaltene handling during operation of the engine, fuelled by a heavy fuel
oil, and its
lubrication by the composition, in comparison with that of a comparable oil
where the basestock
is a Group I basestock.
The metal detergent (B) is C20 or higher alkyl-substituted.
The polyalkenyl substituent in the anhydride (C) has a number average
molecular
weight of from 350 to 1000, such as from 500 to 1000.
In this specification, the following words and expressions, if and when used,
have the
meanings ascribed below:
"active ingredients" or "(a.i.)" refers to additive material that is not
diluent or solvent;
"comprising" or any cognate word specifies the presence of stated features,
steps, or
integers or components, but does not preclude the presence or addition of one
or more
other features, steps, integers, components or groups thereof; the expressions
"consists
of' or "consists essentially of' or cognates may be embraced within
"comprises" or
cognates, wherein "consists essentially of' permits inclusion of substances
not
materially affecting the characteristics of the composition to which it
applies;
"major amount" means 50 mass % or more, preferably 60 mass % or more, more
preferably 70 mass /0 or more, even more preferably 80 mass % or more, of a
composition;
"minor amount" means less than 50 mass %, preferably less than 40 mass %, more
preferably less than 30 mass %, and even more preferably less than 20 mass %,
of a
composition;
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"TBN" means total base number as measured by ASTM D2896.
Furthermore in this specification, if and when used:
"calcium content" is as measured by ASTM 4951;
"phosphorus content" is as measured by ASTM D5185;
"sulphated ash content" is as measured by ASTM D874;
"sulphur content" is as measured by ASTM D2622;
"KV100" means kinematic viscosity at 100 C as measured by ASTM D445.
Also, it will be understood that various components used, essential as well as
optimal
and customary, may react under conditions of formulation, storage or use and
that the invention
also provides the product obtainable or obtained as a result of any such
reaction.
Further, it is understood that any upper and lower quantity, range and ratio
limits set
forth herein may be independently combined.
DETAILED DESCRIPTION OF THE INVENTION
The features of the invention will now be discussed in more detail below.
OIL OF LUBRICATING VISCOSITY (A)
ESTER BASESTOCKS (Al)
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These are organic ester basestocks that include but are not limited to
monoestcrs,
diesters and polyolesters, and also polymer esters. They are generally
considered to be Group
V basestocks and are typically derived from animal or vegetable sources.
Naturally-occurring
organic esters can be found in animal fats or in vegetable oils. Organic
esters can be synthesised
by reacting organic acids with alcohols.
Monesters may be prepared by reacting monohydric alcohols with monobasic fatty
acids
to create a molecule with a single ester linkage and linear or branched alkyl
groups.
Diesters may be prepared by reacting monohydric alcohols (e.g., butyl alcohol,
hexyl
alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene
glycol monoether,
propylene glycol) with dibasic acids (e.g., phthalic acid, succinic acid,
alkyl succinic acids and
alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic
acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic
acids) to create a
molecule which may be linear, branched or aromatic with two ester groups.
Specific examples
of such esters includes dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl
fumarate, dioctyl
sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl
phthalate, dieicosyl
sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex
ester formed by
reacting one mole of sebacic acid with two moles of tetraethylene glycol and
two moles of 2-
ethylhexanoic acid.
Polyol esters may be prepared by esterifying one or more polyols such as
neopentyl
glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and
tripentaerythritol with one or
more organic acids such as C5 to C12 monocarboxylic acids. See, for example,
US-A-6,462,001.
Examples of polyol esters include trimethylolpropane (IMP) esters .
Tricarboxylic acid esters are also preferred. The tricarboxylic acid ester is
preferably a
benzene tricarboxylic acid. A
preferred benzene tricarboxylic acid ester is I ,2,4-
benzenetricarboxylic acid having alkyl chain lengths ranging from 5 to 10,
preferably from 7
to 9. A preferred 1,2,4-benzenetricarboxylic acid is trioctyl trimellitate.
6
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Examples of ester basestocks for use in the present invention are those having
a
kinematic viscosity of 2 to 10 mm2s-I at 100 C or those having a kinematic
viscosity of greater
than 10 to 100 mm2s-I at 100 C. A specific example of suitable polyol ester is
Priolube
(Registered Trade Mark) 3970, which is an ester of a neopentyl polyol,
suitably TMP, with at
least one aliphatic, saturated monocarboxylic acid and having 6 to 12 carbon
atoms and a
kinematic viscosity of 4.4 mm2s-I at 100 C.
The ester basestock may be present in an amount in the range of 2 to 85,
preferably 5 to
50, more preferably 8 to 40 mass %.
BASESTOCKS (A2)
These may range in viscosity from light distillate mineral oil to heavy
lubricating oil.
Generally, the viscosity of the oil ranges from 2 to 40 mm2s1, as measured at
100 C.
Natural oils include animal oils and vegetable oils (e.g., castor oil, lard
oil); liquid
petroleum oils and hydrorefined, solvent-treated or acid-treated mineral oils
of the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of lubricating
viscosity derived from
coal or shale also serve as useful base oils.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted
hydrocarbon
oils such as polymerized and interpolymerized olefins (e.g., polybutylenes,
polypropylenes,
propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexenes),
poly(1-
octenes), poly(1-decenes)); alkybenzenes (e.g., dodecylbenzenes,
tetradecylbenzenes,
dinonylbenzenes, di(2-ethylhexyl)benzencs); polyphenyls (e.g., biphenyls,
terphenyls,
alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl
sulphides and
derivative, analogues and homologues thereof.
7
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Unrefined, refined and re-refined oils can be used in lubricants of the
present invention.
Unrefined oils are those obtained directly from a natural or synthetic source
without further
purification treatment. For example, a shale oil obtained directly from
retorting operations; and
petroleum oil obtained directly from distillation are unrefined oils. Refined
oils are similar to
unrefined oils except that the oil is further treated in one or more
purification steps to improve
one or more properties. Many such purification techniques, such as
distillation, solvent
extraction, acid or base extraction, filtration and percolation, are known to
those skilled in the
art. Re-refined oils are obtained by processes similar to those used to
provide refined oils but
begin with oil that has already been used in service. Such re-refined oils are
also known as
reclaimed or reprocessed oils and are often subjected to additional processing
using techniques
for removing spent additives and oil breakdown products.
The American Petroleum Institute (API) publication "Engine Oil Licensing and
Certification System", Industry Services Department, Fourteenth Edition,
December 1996,
Addendum 1, December 1998 categorizes base stocks as follows:
Group I base stocks contain less than 90 percent saturates and/or greater than
0.03 percent
sulphur and have a viscosity index greater than or equal to 80 and less than
120 using the test
methods specified in Table E-1.
Group II base stocks contain greater than or equal to 90 percent saturates and
less than or
equal to 0.03 percent sulphur and have a viscosity index greater than or equal
to 80 and less
than 120 using the test methods specified in Table E-1.
Group III base stocks contain greater than or equal to 90 percent saturates
and less than
or equal to 0.03 percent sulphur and have a viscosity index greater than or
equal to 120 using
the test methods specified in Table E-1.
Group IV base stocks are polyalphaolefins (PAO).
8
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Group V base stocks include all other base stocks not included in Group I, IT,
III, or IV.
Analytical Methods for Base Stock are tabulated below:
(TABLE E-1)
PROPERTY TEST METHOD
Saturates ASTM D 2007
Viscosity Index ASTM D 2270
Sulphur ASTM D 2622
ASTM D 4294
ASTM D 4927
ASTM D 3120
By way of example, the basestocks (A2) embraces Group II, Group III and Group
IV
basestocks and also basestocks derived from hydrocarbons synthesised by the
Fischer-Tropsch
process. In the Fischer-Tropsch process, synthesis gas containing carbon
monoxide and
hydrogen (or `syngas') is first generated and then converted to hydrocarbons
using a Fischer-
Tropsch catalyst. These hydrocarbons typically require further processing in
order to be useful
as a base oil. For example, they may, by methods known in the art, be
hydroisomerized;
hydrocracked and hydroisomerized; dewaxed; or hydroisomerized and dewaxed. The
syngas
may, for example, be made from gas such as natural gas or other gaseous
hydrocarbons by
steam reforming, when the basestock may be referred to as gas-to-liquid
("GTL") base oil; or
from gasification of biomass, when the basestock may be referred to as biomass-
to-liquid
("BTL" or "BMTL") base oil; or from gasification of coal, when the basestock
may be referred
to as coal-to-liquid ("CTL") base oil.
As stated, the basestock (A2), when used in this invention, contains 50 mass %
or more
of the defined basestock or a mixture thereof. Preferably, it contains 60,
such as 70, 80 or 90,
mass % or more of the defined basestock or a mixture thereof. (A2) may
comprise substantially
all the defined basestock or a mixture thereof.
9
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OVERBASED METAL DETERGENT (B)
A metal detergent is an additive based on so-called metal "soaps", that is
metal salts of
acidic organic compounds, sometimes referred to as surfactants. They generally
comprise a
polar head with a long hydrophobic tail. Overbased metal detergents, which
comprise
neutralized metal detergents as the outer layer of a metal base (e.g.
carbonate) micelle, may be
provided by including large amounts of metal base by reacting an excess of a
metal base, such
as an oxide or hydroxide, with an acidic gas such as carbon dioxide. Examples
of detergents
include metal salicylates, phenates and salicylates and combinations thereof.
In the present invention, overbased metal detergents (B) are preferably
overbased metal hydro carbyl-substituted hydroxybenzo ate,
more preferably
hydrocarbyl-substituted salicylate, detergents. The metal may be an alkali
metal (e.g. Li, Na,
K) or an alkaline earth metal (e.g. Mg, Ca).
"Hydrocarbyl" means a group or radical that contains carbon and hydrogen atoms
and
that is bonded to the remainder of the molecule via a carbon atom. It may
contain hetero atoms,
i.e. atoms other than carbon and hydrogen, provided they do not alter the
essentially
hydrocarbon nature and characteristics of the group. As examples of
hydrocarbyl, there may
be mentioned alkyl and alkenyl. A preferred overbased metal hydrocarbyl-
substituted
hydroxybenzoate is a calcium alkyl-substituted salicylate and has the
structure shown:
/OH
R Ca 2
R
\ 0
2
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wherein R is a linear alkyl group. There may be more than one R group attached
to the benzene
ring. The COO- group can be in the ortho, meta or para position with respect
to the hydroxyl
group; the ortho position is preferred. The R group can be in the ortho, meta
or para position
with respect to the hydroxyl group.
Salicylic acids are typically prepared by the carboxylation, by the Kolbe-
Schmitt
process, of phenoxides, and in that case will generally be obtained (normally
in a diluent) in
admixture with uncarboxylated phenol. Salicylic acids may be non-sulphurized
or sulphurized,
and may be chemically modified and/or contain additional substituents.
Processes for
sulphurizing an alkyl salicylic acid are well known to those skilled in the
art, and are described
in, for example, US 2007/0027057.
The alkyl groups advantageously contain 5 to 100, preferably 9 to 30,
especially 14 to
24, carbon atoms.
The term "overbased" is generally used to describe metal detergents in which
the ratio
of the number of equivalents of the metal moiety to the number of equivalents
of the acid moiety
is greater than one. The term low-based' is used to describe metal detergents
in which the
equivalent ratio of metal moiety to acid moiety is greater than 1, and up to
about 2.
By an "overbased calcium salt of surfactants" is meant an overbased detergent
in which
the metal cations of the oil-insoluble metal salt are essentially calcium
cations. Small amounts
of other cations 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 % of the cations 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 in which
the cation is a metal
other than calcium. Preferably, the metal salt of the surfactant is also
calcium.
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Carbonated overbased metal detergents typically comprise amorphous
nanopartieles.
Additionally, the art discloses nanoparticulate materials comprising carbonate
in the crystalline
calcite and vaterite forms.
The basicity of the detergents may be expressed as a total base number (TBN),
sometimes referred to as base number (BN). A total base number is the amount
of acid needed
to neutralize all of the basicity of the overbased material. The TBN may be
measured using
ASTM standard D2896 or an equivalent procedure. The detergent may have a low
TBN (i.e. a
TBN of less than 50), a medium TBN (i.e. a TBN of 50 to 150) or a high TBN
(i.e. a TBN of
greater than 150, such as 150-500). The bascicity may also be expressed as
basicity index (BI),
which is the molar ratio of total base to total soap in the overbased
detergent.
POLYALKENYL-SUBSTITUTED CARBOXYLIC ACID ANHYDRIDE (C)
The anhydride may constitute at least 1 to 7, preferably 2 to 6 mass % of the
lubricating
oil composition. Preferably it constitutes 3 to 5, even more preferably 4 to
5, mass %.
The anhydride may be mono or polycarboxylic, preferably dicarboxylic. The
polyalkenyl group preferably has from 8 to 400, such as 8 to 100, carbon
atoms.
General formulae of exemplary anhydrides may be depicted as
R1
HC¨CO
H2C¨CO
where R.' represents a C8 to Cim branched or linear polyalkenyl group.
The polyalkenyl moiety may have a number average molecular weight of from 200
to
3000, preferably from 350 to 950.
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Suitable hydrocarbons or polymers employed in the formation of the anhydrides
used
in the present invention to generate the polyalkenyl moieties include
homopolymers,
interpolymers or lower molecular weight hydrocarbons. One family of such
polymers comprise
polymers of ethylene and/or at least one C3 to C28 alpha-olefin having the
formula H2C=CHR1
wherein RI is straight or branched-chain alkyl radical comprising 1 to 26
carbon atoms and
wherein the polymer contains carbon-to-carbon unsaturation, preferably a high
degree of
terminal ethenylidene unsaturation. Preferably, such polymers comprise
interpolymers of
ethylene and at least one alpha-olefin of the above formula, wherein R1 is
alkyl of from 1 to 18
carbon atoms, and more preferably is alkyl of from 1 to 8 carbon atoms, and
more preferably
still of from 1 to 2 carbon atoms. Therefore, useful alpha-olefin monomers and
comonomers
include, for example, propylene, butene-1, hexene-1, octene-1, 4-methylpentene-
1, decene-1,
dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1,
heptadecene-1,
octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures of propylene
and butene-1,
and the like). Exemplary of such polymers are propylene homopolymers, butene-1
homopolymers, ethylene-propylene copolymers, ethylene-butene-1 copolymers,
propylene-butene copolymers and the like, wherein the polymer contains at
least some terminal
and/or internal unsaturation. Preferred polymers are unsaturated copolymers of
ethylene and
propylene and ethylene and butene-1. The interpolymers may contain a minor
amount, e.g. 0.5
to 5 mole %, of a C4 to C18 non-conjugated diolefin comonomer. However, it is
preferred that
the polymers comprise only alpha-olefin homopolymers, interpolymers of alpha-
olefin
comonomers and interpolymers of ethylene and alpha-olefin comonomers. The
molar ethylene
content of the polymers employed is preferably in the range of 0 to 80 %, and
more preferably
0 to 60 %. When propylene and/or butene-1 are employed as comonomer(s) with
ethylene, the
ethylene content of such copolymers is most preferably between 15 and 50 %,
although higher
or lower ethylene contents may be present.
These polymers may be prepared by polymerizing an alpha-olefin monomer, or
mixtures of alpha-olefin monomers, or mixtures comprising ethylene and at
least one C3 to C28
alpha-olefin monomer, in the presence of a catalyst system comprising at least
one metallocene
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=
(e.g., a cyclopentadienyl-transition metal compound) and an alumoxane
compound. Using this
process, a polymer in which 95 % or more of the polymer chains possess
terminal
ethenylidene-type unsaturation can be provided. The percentage of polymer
chains exhibiting
terminal ethenylidene unsaturation may be determined by FTIR spectroscopic
analysis, titration,
or C13 NMR. Interpolymers of this latter type may be characterized by the
formula
POLY-C(R1)=CH2 wherein R1 is CI to C26 alkyl, preferably Ci to Cis alkyl, more
preferably
CI to C8 alkyl, and most preferably CI to C2 alkyl, (e.g., methyl or ethyl)
and wherein POLY
represents the polymer chain. The chain length of the R1 alkyl group will vary
depending on
the comonomer(s) selected for use in the polymerization. A minor amount of the
polymer
chains can contain terminal ethenyl, i.e., vinyl, unsaturation, i.e. POLY-
CH=CH2, and a portion
of the polymers can contain internal monounsaturation, e.g. POLY-CH=CH(R1),
wherein R1 is
as defined above. These terminally unsaturated interpolymers may be prepared
by known
metallocene chemistry and may also be prepared as described in U.S. Patent
Nos. 5,498,809;
5,663,130; 5,705,577; 5,814,715; 6,022,929 and 6,030,930.
Another useful class of polymers is that of polymers prepared by cationic
polymerization of isobutene, styrene, and the like. Common polymers from this
class include
polyisobutenes obtained by polymerization of a C4 refinery stream having a
butene content of
35 to 75 mass %, and an isobutene content of 30 to 60 mass %, in the presence
of a Lewis acid
catalyst, such as aluminum trichloride or boron trifluoride. A preferred
source of monomer for
making poly-n-butenes is petroleum feedstreams such as Raffinate II. These
feedstocks are
disclosed in the art such as in U.S. Patent No. 4,952,739. Polyisobutylene is
a most preferred
backbone because it is readily available by cationic polymerization from
butene streams (e.g.,
using AlC13 or BF3 catalysts). Such polyisobutylenes generally contain
residual unsaturation
in amounts of one ethylenic double bond per polymer chain, positioned along
the chain. A
preferred embodiment utilizes polyisobutylene prepared from a pure isobutylene
stream or a
Raffinate I stream to prepare reactive isobutylene polymers with terminal
vinylidene olefins.
Preferably, these polymers, referred to as highly reactive polyisobutylene (HR-
PIB), have a
terminal vinylidene content of at least 65%, e.g., 70%, more preferably at
least 80%, most
preferably, at least 85%. The preparation of such polymers is described, for
example, in U.S.
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CA 2833977 2019-10-07
Patent No. 4,152,499. HR-PIB is known and HR-PIB is commercially available
under the
tradenames GlissopalTm (from BASF) and UltravisTm (from BP-Amoco).
Polyisobutylene polymers that may be employed are generally based on a
hydrocarbon
chain of from 400 to 3000. Methods for making polyisobutylene are known.
Polyisobutylene
can be functionalized by halogenation (e.g. chlorination), the thermal "ene"
reaction, or by free
radical grafting using a catalyst (e.g. peroxide), as described below.
To produce (C) the hydrocarbon or polymer backbone may be functionalized with
carboxylic anhydride-producing moieties selectively at sites of carbon-to-
carbon unsaturation
on the polymer or hydrocarbon chains, or randomly along chains using any of
the three
processes mentioned above or combinations thereof, in any sequence.
Processes for reacting polymeric hydrocarbons with unsaturated carboxylic,
anhydrides
and the preparation of derivatives from such compounds are disclosed in U.S.
Patent Nos.
3,087,936; 3,172,892; 3,215,707; 3,231,587; 3,272,746; 3,275,554; 3,381,022;
3,442,808;
3,565,804; 3,912,764; 4,110,349; 4,234,435; 5,777,025; 5,891,953; as well as
EP 0 382 450
Bl; CA-1,335,895 and GB-A-1,440,219. The polymer or hydrocarbon may be
functionalized,
with carboxylic acid anhydride moieties by reacting the polymer or hydrocarbon
under
conditions that result in the addition of functional moieties or agents, i.e.,
acid anhydride, onto
the polymer or hydrocarbon chains primarily at sites of carbon-to-carbon
unsaturation (also
referred to as ethylenic or olefinic unsaturation) using the halogen assisted
functionalization
(e.g. chlorination) process or the thermal "ene" reaction.
Selective functionalization can be accomplished by halogenating, e.g.,
chlorinating or
brominating, the unsaturated a-olefin polymer to 1 to 8, preferably 3 to 7,
mass % chlorine, or
bromine, based on the weight of polymer or hydrocarbon, by passing the
chlorine or bromine
through the polymer at a temperature of 60 to 250 C, preferably 110 to 160 C,
e.g., 120 to
140 C, for 0.5 to 10, preferably 1 to 7 hours. The halogenated polymer or
hydrocarbon
(hereinafter backbone) is then reacted with sufficient monounsaturated
reactant capable of
CA 2833977 2019-10-07
adding the required number of functional moieties to the backbone, e.g.,
monounsaturated
carboxylic reactant, at 100 to 250 C, usually 180 C to 235 C, for 0.5 to 10,
e.g., 3 to 8 hours,
such that the product obtained will contain the desired number of moles of the
monounsaturated
carboxylic reactant per mole of the halogenated backbones. Alternatively, the
backbone and
the monounsaturated carboxylic reactant are mixed and heated while adding
chlorine to the hot
material.
While chlorination normally helps increase the reactivity of starting olefin
polymers
with monounsaturated functionalizing reactant, it is not necessary with some
of the polymers
or hydrocarbons contemplated for use in the present invention, particularly
those preferred
polymers or hydrocarbons which possess a high terminal bond content and
reactivity.
Preferably, therefore, the backbone and the monounsaturated functionality
reactant, (carboxylic
reactant), are contacted at elevated temperature to cause an initial thermal
"ene" reaction to take
place. Ene reactions are known.
The hydrocarbon or polymer backbone can be functionalized by random attachment
of
functional moieties along the polymer chains by a variety of methods. For
example, the
polymer, in solution or in solid form, may be grafted with the monounsaturated
carboxylic
reactant, as described above, in the presence of a free-radical initiator.
When performed in
solution, the grafting takes place at an elevated temperature in the range of
100 to 260 C,
preferably 120 to 240 C. Preferably, free-radical initiated grafting would be
accomplished in
a mineral lubricating oil solution containing, e.g., 1 to 50, preferably 5 to
30, mass % polymer
based on the initial total oil solution.
The free-radical initiators that may be used are peroxides, hydroperoxides,
and azo
compounds, preferably those that have a boiling point greater than 100 C and
decompose
thermally within the grafting temperature range to provide free-radicals.
Representative of
these free-radical initiators are azobutyronitrile, 2,5-dimethylhex-3-ene-2, 5-
bi s-tertiary-butyl
peroxide and dicumene peroxide. The initiator, when used, is typically in an
amount of between
0.005% and 1% by weight based on the weight of the reaction mixture solution.
Typically, the
16
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=
aforesaid monounsaturated carboxylic reactant material and free-radical
initiator are used in a
weight ratio range of from 1.0:1 to 30:1, preferably 3:1 to 6:1. The grafting
is preferably carried
out in an inert atmosphere, such as under nitrogen blanketing. The resulting
grafted polymer is
characterized by having carboxylic acid (or derivative) moieties randomly
attached along the
polymer chains, it being understood, of course, that some of the polymer
chains remain
ungrafted. The free radical grafting described above can be used for the other
polymers and
hydrocarbons used in the present invention.
The preferred monounsaturated reactants that are used to functionalize the
backbone
comprise mono- and dicarboxylic acid material, i.e., acid, or acid derivative
material, including
(i) monounsaturated C4 to Clo dicarboxylic acid wherein (a) the carboxyl
groups are vicinyl,
(i.e., located on adjacent carbon atoms) and (b) at least one, preferably
both, of the adjacent
carbon atoms are part of the mono unsaturation; (ii) derivatives of (i) such
as anhydrides or CI
to C5 alcohol derived mono- or diesters of (i); (iii) monounsaturated C3 to
CIO monocarboxylic
acid wherein the carbon-carbon double bond is conjugated with the carboxy
group, i.e., of the
structure -C¨C-00-; and (iv) derivatives of (iii) such as CI to C5 alcohol
derived mono- or
diesters of (iii). Mixtures of monounsaturated carboxylic materials (i) - (iv)
also may be used.
Upon reaction with the backbone, the monounsaturation of the monounsaturated
carboxylic
reactant becomes saturated. Thus, for example, maleic anhydride becomes
backbone-
substituted succinic anhydride, and acrylic acid becomes backbone-substituted
propionic acid.
Exemplary of such monounsaturated carboxylic reactants are fumaric acid,
itaconic acid, maleic
acid, maleic anhydride, chloromaleic acid, chloromaleic anhydride, acrylic
acid, methacrylic
acid, crotonic acid, cinnamic acid, and lower alkyl (e.g., CI to C4 alkyl)
acid esters of the
foregoing, e.g., methyl maleate, ethyl fumarate, and methyl fumarate.
To provide the required functionality, the monounsaturated carboxylic
reactant,
preferably maleic anhydride, typically will be used in an amount ranging from
equimolar
amount to 100 mass % excess, preferably 5 to 50 mass % excess, based on the
moles of polymer
or hydrocarbon. Unreacted excess monounsaturated carboxylic reactant can be
removed from
the final dispersant product by, for example, stripping, usually under vacuum,
if required.
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CO-ADDITIVES
The lubricating oil composition of the invention may comprise further
additives,
different from and additional to (B) and (C). Such additional additives may,
for example
include ashless dispersants, other metal detergents, anti-wear agents such as
zinc dihydrocarbyl
dithiophosphates, anti-oxidants and demulsifiers. In some cases, an ashless
dispersant need not
be provided.
It may be desirable, although not essential, to prepare one or more additive
packages or
concentrates comprising the additives, whereby additives (B) and (C) can be
added
simultaneously to the base oil to form the lubricating oil composition.
Dissolution of the
additive package(s) into the lubricating oil may be facilitated by solvents
and by mixing
accompanied with mild heating, but this is not essential. The additive
package(s) will typically
be formulated to contain the additive(s) in proper amounts to provide the
desired concentration,
and/or to carry out the intended function in the final formulation when the
additive package(s)
is/are combined with a predetermined amount of base oil. Thus, additives (B)
and (C), in
accordance with the present invention, may be admixed with small amounts of
base oil or other
compatible solvents together with other desirable additives to form additive
packages
containing active ingredients in an amount, based on the additive package, of,
for example,
from 2.5 to 90, preferably from 5 to 75, most preferably from 8 to 60, mass A
of additives in
the appropriate proportions, the remainder being base oil.
The final formulation as a trunk piston engine oil may typically contain 30,
preferably
to 28, more preferably 12 to 24, mass % of the additive package(s), the
remainder being base
oil. The trunk piston engine oil may have a compositional TBN (using ASTM
D2896) of 20 to
60, such as, 30 to 55. For example, it may be 40 to 55 or 35 to 50.
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EXAMPLES
The present invention is illustrated by but in no way limited to the following
examples.
COMPONENTS
The following components were used:
Ester Basestocks (Al)
= a polyol ester (PRIOLUBE (Registered Trade Mark) 3970), a
trimethylolpropane ester
with C8-10 fatty acids, having a viscosity of 4.4 mm2s-I at 100 C, ex Croda
Lubricants;
= a polymer ester (KETJENLUBE (Registered Trade Mark) 115), in the form of
a
copolymer of alpha-olefins and a dicarboxylic acid dibutylester with an
average
molecular weight of approximately 1400.
Basestocks (A2)
= a Group I oil (XOMAPE 600) (for comparison)
= a Group II oil (RLOP 600)
= a Group III oil (YUBASETM 8)
Commercial identifications are in parentheses.
Detergents (B)
= calcium alkyl salicylate (BI 8.0)
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= calcium alkyl salicylate (BI 3.0)
Basicity indices are in parentheses.
PIBSA (C)
a polyisobutene succinic anhydride derived from a polyisobutene having a
number average
molecular weight of 950
HFO
a heavy fuel oil (ISO-F-RMK 380)
TRUNK PISTON MARINE ENGINE LUBRICATING OILS (TPEO'S)
Selections of the above components were blended to give a range of TPEO' s.
Some are
examples of the invention; others are reference examples for comparison
purposes. The
compositions of the TPEO' s tested when each contained an HFO are given (in
mass %) in the
tables below under the RESULTS heading.
TESTING
Light Scattering
Test trunk piston marine engine lubricating oils (TPEO's) were evaluated for
asphaltene
dispersancy using light scattering according to the Focused Beam Reflectance
Method
("FBRM"), which predicts asphaltene agglomeration and hence 'black sludge'
formation.
CA 2833977 2019-10-07
The FBRM test method was disclosed at the 7th International Symposium on
Marine
Engineering, Tokyo, 24th - 28th October 2005, and was published in "The
Benefits of Salicylate
Detergents in TPEO Applications with a Variety of Base Stocks" in the
Conference Proceedings.
Further details were disclosed at the CIMAC Congress, Vienna, 21st -24th May
2007 and
published in "Meeting the Challenge of New Base Fluids for the Lubrication of
Medium Speed
Marine Engines ¨ An Additive Approach" in the Congress Proceedings. In the
latter paper it
is disclosed that, by using the FBRM method, it is possible to obtain
quantitative results for
asphaltene dispersancy that predict performance for lubricant systems based on
base stocks
containing greater than or less than 90% saturates, and greater than or less
than 0.03% sulphur.
The predictions of relative performance obtained from FBRM were confirmed by
engine tests
in marine diesel engines.
The FBRM probe contains fibre optic cables through which laser light travels
to reach
the probe tip. At the tip, an optic focuses the laser light to a small spot.
The optic is rotated so
that the focussed beam scans a circular path between the window of the probe
and the sample.
As particles flow past the window, they intersect the scanning path giving
backscattered light
from the individual particles.
The scanning laser beam travels much faster than the particles; this means
that the
particles are effectively stationary. As the focussed beam reaches one edge of
the particle, the
amount of backscattered light increases; the amount will decrease when the
focussed beam
reaches the other edge of the particle.
The instrument measures the time of the increased backscatter. The time period
of
backscatter from one particle is multiplied by the scan speed and the result
is a distance or chord
length. A chord length is a straight line between any two points on the edge
of a particle. This
is represented as a chord length distribution, a graph of numbers of chord
lengths (particles)
measured as a function of the chord length dimensions in microns. As the
measurements are
performed in real time, the statistics of a distribution can be calculated and
tracked. FBRM
typically measures tens of thousands of chords per second, resulting in a
robust number-by-
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chord length distribution. The method gives an absolute measure of the
particle size distribution
of the asphaltene particles.
The Focused beam Reflectance Probe (FBRM), model LasentecTM D600L, was
supplied
by Mettler Toledo, Leicester, UK. The instrument was used in a configuration
to give a particle
size resolution of 1 Inn to lmm. Data from FBRM can be presented in several
ways. Studies
have suggested that the average counts per second can be used as a
quantitative determination
of asphaltene dispersancy. This value is a function of both the average size
and level of
agglomerate. In this application, the average count rate (over the entire size
range) was
monitored using a measurement time of 1 second per sample.
The test TPEO's were heated to 60 C and stirred at 400rpm; when the
temperature
reached 60 C the FBRM probe was inserted into the sample and measurements made
for 15
minutes. An aliquot of heavy fuel oil (10% w/w) was introduced into the TPEO
under stirring
using a four-blade stirrer (at 400 rpm). A value for the average counts per
second was taken
when the count rate had reached an equilibrium value (typically overnight).
RESULTS
Light Scattering
The results of the FBRM tests are summarized in the tables below, where lower
particle
count indicates better performance.
Reference examples are designated "Ref".
TABLE 1
Each TPEO tested had a BN of 40, contained 1.23 mass% (in terms of calcium) of
calcium salicylate of BI 8.0 and 0.24 mass % (in terms of calcium) of calcium
salicylate of BI
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3.0, and contained the same amount of Zn and of silicone antifoam. The
remainder of the
finished oil components are given in the table below:
Example PIBSA Priolube Group Group I Lasentec Counts
(C) 3970 II Oil
(% (Al) Oil (A2)
active (wt %)
matter)
Ref 1 - Balance 2,032.43
Ref 2 Balance - 5,988.84
Ref 3 10.00 Balance - 9,613.23
Ref 4 30.00 Balance - 732.81
Ref 5 4.80 Balance - 2,205.86
1 4.80 10.00 Balance - 786.41
2 4.80 30.00 Balance - 12.82
3 4.80 80.83 13.89
Ref 3 and Ref 4 are illustrative of US Patent Application Publication No.
2011/0319304 Al ('304).
Ref 4 (use of ester alone) confirms the teaching of '304.
Ref 5 (use of PIBSA alone) confirms the teaching of '594.
Examples 1-3 confirm the synergy of PIBSA and ester.
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. .
TABLE 2
Each TPEO tested had a BN of 40, contained 0.75 mass % (in terms of calcium)
of calcium
salicylate of BI 8.0 and 0.68 mass % (in terms of calcium) of calcium
salicylate of BI 3.0, and
contained the same amount of Zn. The remainder of the finished oil components
are given in
the table below:
Example PIBSA Priolube Ketjenlube Group Group Group Lasentec
(C) 3970 (Al) 115 II (A2) I
III (A2) Counts
(% active (wt "A) (Al)
matter) (wt %)
- -
Ref 6 - - Balance - 933.83
4 4.80 1.00 - Balance - - 391.79
5 4.80 3.00 - Balance - - 223.56
6 4.80 5.00 - Balance - - 251.08
7 4.80 7.00 - Balance - - 161.13
8 4.80 10.00 - Balance - - 48.38
9 0.80 10.00 - Balance - - 3,499.45
10 1.60 10.00 - Balance - - 1,333.98
11 2.40 10.00 - Balance - - 421.74
12 3.20 10.00 - Balance - - 268.40
13 4.00 10.00 - ' Balance - - 47.87
14 4.80 10.00 - - - Balance 737.14
15 4.80 - 10 Balance - - 110.03
The results show that varying the treat rate of PIBSA and ester affects
performance: in
Examples 4-8, the PIBSA treat rate is kept constant and the ester treat rate
progressively
increased; in Examples 9-13, the ester treat rate is kept constant and the
PIBSA treat rate is
progressively increased. Example 14 shows the applicability of the invention
to a Group III
/4
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. .
base oil eyond that of Ref 6 (a Group I oil) and Example 15 shows the
applicability of the
invention to esters other than Priolube 3970.
TABLE 3
Each TPEO treated had a BN of 30, contained 0.56 mass % (in terms of calcium)
of
calcium salicylate of BI 8.0 and 0.51 mass % (in terms of calcium) of calcium
salicylate of BI
3.0, and contained the same amount of Zn. The remainder of the finished oil
components are
given in the table below:
Example PIBSA Priolube Group II Group I Lasentec
(C) 3970 (A2) Counts
(% active (Al)
,
matter) (wt /0)
Ref 7 - - - Balance 1,755.35
Ref 8 2.40 Balance - 3,638.42
17 2.40 1.00 Balance - 1,622.23
18 2.40 3.00 Balance - 1,805.06
19 2.40 5.00 Balance - 1,626.40
20 2.40 7.00 Balance - 1,135.09
21 2.40 10.00 Balance - 899.70
The results show that the effect of the invention is exhibited in lower BN
TPEO' s.
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