Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
USE OF A NITROGEN-CONTAINING ASHLESS DISPERSANT ADDITIVE IN A
TRUNK PISTON MARINE LUBRICATING OIL COMPOSITION
FIELD OF THE INVENTION
This invention relates to the lubrication of 4-stroke marine diesel internal
combustion
engines, usually referred to as trunk piston engines. Lubricants therefor are
usually known as
trunk piston engine oils ("TPEO' s").
BACKGROUND OF THE INVENTION
Trunk piston engines may be used in marine, power-generation and rail traction
applications and have a higher speed than cross-head engines. A single
lubricant (TPEO) is
used for crankcase and cylinder lubrication. All major moving parts of the
engine, i.e. the main
and big end bearings, camshaft and valve gear, are lubricated by means of a
pumped circulation
system. The cylinder liners are lubricated partially by splash lubrication and
partially by oil
from the circulation systems that finds its way to the cylinder wall through
holes in the piston
skirt via the connecting rod and gudgeon pin. Trunk piston engines normally
include a
centrifuge to clean the TPEO.
Nitrogen-containing ashless dispersants are known in the art as additives for
TPEO's.
See for example EP-A-2133740; US-A-2009/0203559; US-A-2009/0011966; EP-A-
1528099;
and EP-A-1209218.
The art does not, however, mention the effect of a nitrogen-containing ashless
dispersant
on the dimunition of base number (BN) during use of the TPEO; nor its effect
on viscosity
increase.
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Date Recue/Date Received 2022-03-18
CA 02915701 2015-12-18
SUMMARY OF THE INVENTION
It is now found that the use of nitrogen-containing ashless dispersants in
defined
amounts in a TPEO has a beneficial effect on the BN and viscosity, without
adversely
affecting deposits performance.
Thus, the present invention provides the use of a nitrogen-containing ashless
dispersant additive in an amount providing in the range of 50 to 150,
preferably 75 to 125,
ppm N by mass in a trunk piston marine lubricating oil composition for a
medium-speed
compression-ignited marine engine, fueled by a heavy fuel oil, and its
lubrication by the
composition, the composition having a BN in the range of 20 to 60, preferably
30 to 55, the
use being to diminish the loss of BN and to diminish the increase in viscosity
without
adversely affecting deposits performance, preferably in comparison with
analogous use when
the amount of nitrogen-containing ashless dispersant falls outside of the
above range.
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;
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"major amount" means 50 mass % or more, preferably 60 mass A or more, even
more
preferably 60 mass % or more, and most preferably 70 mass % or more, of a
composition;
"minor amount" means less than 50 mass %, preferably less than 40 mass %, even
more preferably less than 30 mass %, and most preferably less than 20 mass %,
of a
composition;
"TBN" means total base number as measured by ASTM D2896. "BN" has the same
meaning.
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.
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DETAILED DESCRIPTION OF THE INVENTION
The features of the invention will now be discussed in more detail below.
TRUNK PISTON MARINE ENGINE LUBRICATING OIL COMPOSITION
("TPEO")
A TPEO may employ 7-35, preferably 10-28, more preferably 12-24, mass % of a
concentrate or additives package, the remainder being base stock (oil of
lubricating viscosity).
Preferably, the TPEO has a compositional TBN (using D2896) of 20-60,
preferably 25 or 30-
55.
The following may be mentioned as typical proportions of additives in a TPEO.
Additive Mass% a.i. Mass % a.i.
(Broad) (Preferred)
detergent(s) 0.5-12 2-8
dispersant(s) 0.5-5 1-3
anti-wear agent(s) 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 dispersant 0.03-1.15 0.05-0.1
base stock balance balance
When a plurality of additives is employed it may be desirable, although not
essential,
to prepare one or more additive packages or concentrates comprising the
additives, whereby
several additives can be added simultaneously to the oil of lubricating
viscosity 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,
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in the final formulation when the additive package(s) is/are combined with a
predetermined
amount of base lubricant. Thus, additives 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 % of additives in the appropriate proportions,
the remainder
being base oil.
NITROGEN-CONTAINING ASHLESS DISPERSANT
A dispersant is an additive for a lubricating composition whose primary
function is to
hold solid and liquid contaminants in suspension, thereby passivating them and
reducing
engine deposits at the same time as
reducing
sludge depositions. Thus, for example, a dispersant maintains in suspension
oil-insoluble
substances that result from oxidation during use of the lubricant, thus
preventing sludge
flocculation and precipitation or deposition on metal parts of the engine.
"Ashless" means that the dispersant is a non-metallic organic material that
forms
substantially no ash on combustion, in contrast to metal-containing, hence ash-
forming,
materials. Ashless dispersants comprise a long chain hydrocarbon with a polar
head, the polarity
being derived from inclusion of, e.g. an 0, P or N atom, in this invention, a
N atom. The
hydrocarbon is an oleophilic group that confers oil-solubility, having, for
example 40 to 500
carbon atoms. Thus, ashless dispersants may comprise an oil-soluble polymeric
hydrocarbon
backbone having functional groups that are capable of associating with
particles to be dispersed.
Typically, the dispersants comprise amine, alcohol, amide, or ester polar
moieties attached to the
polymer backbone often via a bridging group. The ashless dispersant may be,
for example,
selected from oil-soluble salts, esters, amino-esters, amides, imides, and
oxazolines of long chain
hydrocarbon-substituted mono-and dicarboxylic acids or their anhydrides;
thiocarboxylate
derivatives of long chain hydrocarbons; long chain aliphatic hydrocarbons
having a polyamine
attached directly thereto, and Mannich condensation products formed by
condensing a long chain
CA 02915701 2015-12-18
substituted phenol with formaldehyde and polyalkylene polyamine, such as
described in US-A-
3,442,808.
The oil-soluble polymeric hydrocarbon backbone is typically an olefin polymer
or polyene,
especially polymers comprising a major molar amount (i.e., greater than 50
mole %) of a C2 to
C18 olefin (e.g., ethylene, propylene, butylene, isobutylene, pentene, octene-
1, styrene), and
typically a C2 to C5 olefin. The oil-soluble polymeric hydrocarbon backbone
may be a
homopolymer (e.g., polypropylene or polyisobutylene) or a copolymer of two or
more of such
olefin (e.g., copolymers of ethylene and an alpha-olefin such as propylene or
butylene, or
copolymers of two different alpha-olefins). Other copolymers include those in
which a minor
molar amount of the copolymer monomers, e.g., 1 to 10 mole %, is an mo-diene,
such as a C3
to 022 non-conjugated diolefin (e.g., a copolymer of isobutylene and
butadiene, or a
copolymer of ethylene, propylene and 1,4-hexadiene or 5-ethylidene-2-
norbornene). Atactic
propylene oligomers typically having an Mn of from 700 to 5000 may also be
used, as
described in EP-A-490454, as well as heteropolymers such as polyepoxides.
A preferred class of olefin polymers is polybutenes, specifically
polyisobutenes (PIB)
or poly-n-butenes, such as may be prepared by polymerization of a C4 refinery
stream. Other
preferred classes of olefin polymers are ethylene alpha-olefin (EAO)
copolymers and alpha-
olefin homo- and copolymers having in each case a high degree (e.g., >30%) of
terminal
vinylidene unsaturation, such as described in WO-94/13709, which may be
functionalised and
aminated to give dispersants.
Dispersants include, for example, derivatives of long chain hydrocarbon-
substituted
carboxylic acids, examples being derivatives of high molecular weight
hydrocarbyl-
substituted succinic acid. A noteworthy group of dispersants are hydrocarbyl-
substituted
succinimides, made, for example, by reacting the above acids (or derivatives)
with a nitrogen-
containing compound, advantageously a polyalkylene polyamine, such as a
polyethylene
polyamine. Preferably, the hydrocarbyl group is a polyalkenyl group. Such
polyalkenyl (e.g.
polybutenyl) moriety may have a number average molecular weight of from 200 to
3000,
preferably from 350 to 1000, more preferably from 400 to 960, or 400 to 950.
Particularly
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CA 02915701 2015-12-18
preferred are the reaction products of polyalkylene polyamines with alkenyl
succinic
anhydrides, such as described in US-A-3,202,678; -3,154,560; -3,172,892; -
3,024,195, -
3,024,237; -3,219,666; and -3,216,936; and BE-A66,875 that may be post-treated
to improve
their properties, such as borated (as described in US-A-3,087,936 and -
3,254,025); fluorinated
and oxylated. For example, boration may be accomplished by treating an acyl
nitrogen-
containing dispersant with a boron compound selected from boron oxide, boron
halides, boron
acids and esters of boron acids.
As stated, the dispersants provides the TPEO with 50-150 ppm by mass of N
atoms.
The co-additives will now be discussed in further detail.
METAL DETERGENT
A detergent is an additive that reduces formation of deposits, for example,
high-temperature varnish and lacquer deposits, in engines; it has acid-
neutralising properties
and is capable of keeping finely-divided solids in suspension. It is based on
metal "soaps",
that is metal salts of acidic organic compounds, sometimes referred to as
surfactants.
A detergent comprises a polar head with a long hydrophobic tail. Large amounts
of a
metal base are included by reacting an excess of a metal compound, such as an
oxide or
hydroxide, with an acidic gas such as carbon dioxide to give an overbased
detergent which
comprises neutralised detergent as the outer layer of a metal base (e.g.
carbonate) micelle.
The detergent is preferably an alkali metal or alkaline earth metal additive
such as an
overbased oil-soluble or oil-dispersible calcium, magnesium, sodium or barium
salt of a
surfactant selected from phenol, sulphonic 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, formate, 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
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different from that of the metal of the oil-insoluble salt. Preferably the
metal, whether the
metal of the oil-soluble or oil-insoluble salt, is calcium.
The TBN of the detergent may be low, i.e. less than 50 mg KOH/g; medium, i.e.
50-
150 mg KOH/g; or high, i.e. over 150 mg KOH/g, as determined by ASTM D2896.
Preferably the TBN is medium or high, i.e. 50 TBN or more. More preferably,
the TBN is at
least 60, more preferably at least 100, more preferably at least 150, and up
to 500, such as up
to 350 mg KOH/g, as determined by ASTM D2896.
Preferably, the detergent comprises an alkaline earth hydrocarbyl-substituted
hydroxyl-benzoate salt such as a calcium alkylsalicylate salt.
The terms 'oil-soluble' or 'oil-dispersable' as used herein do not necessarily
indicate
that the compounds or additives are soluble, dissolvable, miscible or capable
of being
suspended in the oil in all proportions. These 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 individual (i.e.
separate) components that may or may not remain the same chemically before and
after
mixing.
OTHER CO-ADDITIVES
The lubricating oil composition of the invention may comprise further
additives. Such
additional additives may, for example, include other metal detergents, anti-
wear agents such
as ZDDP's, anti-oxidants such as aminic or phenolic anti-oxidants, and
demulsifiers.
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OIL OF LUBRICATING VISCOSITY
The lubricating oils present as a major proportion of the TPEO may range in
viscosity
from light distillate mineral oils to heavy lubricating oils. Generally, the
viscosity of the oil
ranges from 2 to 40 mm2/sec, as measured at 100 C.
Natural oils include animal oils and vegetable oils (e.g., caster 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)benzenes); polyphenyls (e.g., biphenyls,
terphenyls,
alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl
sulphides and
derivative, analogues and homologues thereof.
Alkylene oxide polymers and interpolymers and derivatives thereof where the
terminal
hydroxyl groups have been modified such as by esterification or
etherification, constitute
another class of known synthetic lubricating oil. These are exemplified by
polyoxyalkylene
polymers prepared by polymerization of ethylene oxide or propylene oxide, and
the alkyl and
aryl ethers of polyoxyalkylene polymers (e.g., methyl-polyiso-propylene glycol
ether having a
molecular weight of 1000 or diphenyl ether of poly-ethylene glycol having a
molecular
weight of 1000 to 1500); and mono- and polycarboxylic esters thereof, for
example, the acetic
acid esters, mixed C3-C8 fatty acid esters and Ci3 Oxo acid diester of
tetraethylene glycol.
Another suitable class of synthetic lubricating oil comprises the esters of
dicarboxylic
acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl
succinic acids, maleic
acid, azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic acid,
linoleic acid dimer,
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malonic acid, alkylmalonic acids, alkenyl malonic acids) with a variety of
alcohols (e.g., butyl
alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene
glycol, diethylene
glycol monoether, propylene glycol). 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.
Esters useful as synthetic oils also include those made from C5 to C12
monocarboxylic
acids and polyols and polyol esters such as neopentyl glycol,
trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- or
polyaryloxysilicone oils and silicate oils comprise another useful class of
synthetic lubricants;
such oils include tetraethyl silicate, tetraisopropyl silicate, tetra-(2-
ethylhexyl)silicate, tetra-
(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-
methyl-2-
ethylhexyl)disiloxane, poly(methyl)siloxanes and poly(methylphenyl)siloxanes.
Other
synthetic lubricating oils include liquid esters of phosphorus-containing
acids (e.g., tricresyl
phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and
polymeric
tetrahydrofurans.
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; petroleum oil obtained directly from distillation; or
ester oil obtained
directly from an esterification and used without further treatment would be an
unrefined oil.
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
CA 02915701 2015-12-18
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:
a) 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 the table below.
b) 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 the table below.
c) 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 the table below.
d) Group IV base stocks are polyalphaolefins (PAO).
e) Group V base stocks include all other base stocks not included in Group I,
II, III, or
IV.
Analytical test methods for base stock, referred to above, are tabulated
below:
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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
As examples of the above oils, there may be mentioned the Group I and Group II
oils.
Also, there may be mentioned those of the above oils containing greater than
or equal to 90%
saturates and less than or equal to 0.03% sulphur as the oil of lubricating
viscosity, eg Group
II, III, IV or V. They also include base stocks 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 base stock may be referred
to as gas-to-
liquid ("GTL") base oil; or from gasification of biomass, when the base stock
may be referred
to as biomass-to-liquid ("BTL" or "BMTL") base oil; or from gasification of
coal, when the
base stock may be referred to as coal-to-liquid ("CTL") base oil.
Preferably, the oil of lubricating viscosity in this invention contains 50
mass % or
more said base stocks. It may contain 60, such as 70, 80 or 90, mass % or more
of said base
stock or a mixture thereof The oil of lubricating viscosity may be
substantially all of said
base stock or a mixture thereof
It may be desirable, although not essential, to prepare one or more additive
packages
or concentrates comprising additives, whereby additives can be added
simultaneously to the
oil of lubricating viscosity to form the TPEO.
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The final formulations as a trunk piston engine oil may typically contain 30,
preferably 10 to 28, more preferably 12 to 24, mass % of the additive
package(s), the
remainder being the oil of lubricating viscosity. 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.
The treat rate of additives contained in the lubricating oil composition may
for
example be in the range of 1 to 2.5, preferably 2 to 20, more preferably 5 to
18, mass %.
EXAMPLES
The present invention is illustrated by but not limited to the following
examples.
TRUNK PISTON ENGINE OILS (TPEO'S)
A set of TPEO's was formulated comprising two TPEO's which differed only in
that
one contained a nitrogen-containing ashless dispersant and the other did not.
Each TPEO
contained a mixture of overbased calcium salicylate detergents, a mixture of
aminic and
phenolic anti-oxidants, and other co-additives. They contained the same base
oil to balance.
The dispersant was the product of reacting a polyisobutenyl succinic anhydride
with a
tetraethylene pentamine, and provided the TPEO with 91 ppm by mass of N. The
polyisobutenyl moiety had a number average molecular weight of 950.
Each TPEO was tested in a bulk oil oxidation test where the oil was
contaminated with
0.5 % HFO (Heavy Fuel Oil) and subjected to oxidising conditions for 120
hours. The test
was the DKA oxidation test (CEC L-48-00) in which BN and viscosity change were
assessed.
Each TPEO was also tested in the Panel Coker Test which is described as
follows:
Panel Coker Test
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Lubricating oils may degrade on hot engine surfaces and leave deposits which
will
affect engine performance; the panel coker test simulates typical conditions
and measures the
tendency of oils to form such deposits. The oil under test is splashed onto a
heated metal
plate by spinning a metal comb-like splasher device within a sump containing
the oil. At the
end of the test period, deposits are measured.
An overview of the test method is as follows:
= 225 ml of the oil is heated in an oil bath to 100 C.
= A heated aluminium panel is located above the oil bath at an incline,
maintained at a
temperature of 320 C.
= The oil is splashed for 15 seconds against this panel, followed by no
splashing for 45
seconds.
= This cycle of intermittent splashing is continued for 1 hour.
= The panel is weighed and the deposits are calculated in grams (g).
Tests were carried out on fresh oil (containing no 1-1170) and doped oil
(containing
2.5 % HFO). Results are expressed on a rating scale of 1-10, where lower
values indicate
poorer deposits performance.
The results are tabulated below where the example with no dispersant is called
"Ref"
and the example with the dispersant is called "Inv".
Example Panel Coker DKA
Fresh Oil Doped Oil BN % Loss KV100 % Increase
Ref 4.95 3.64 11 17
Inv 6.92 4.29 7 2
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The results show that the example of the invention (Inv), which contained
dispersant,
exhibited both a lower reduction in BN and a lower increase in KV100 than the
comparison
example (Ref). Also, they show that, where a small amount of dispersant in
present, deposit
cleanliness in the Panel Coker Test is improved markedly even when the TPEO is
contaminated with 2.5% of HFO.
