Note: Descriptions are shown in the official language in which they were submitted.
CA 02736308 2011-04-05
A LUBRICATING OIL COMPOSITION
FIELD OF THE INVENTION
The present invention relates to lubricating oil compositions, more especially
to
automotive lubricating oil compositions for use in piston engines, especially
gasoline
(spark-ignited) and diesel (compression-ignited) crankcase lubrication, such
compositions
being referred to as crankcase lubricants. In particular, although not
exclusively, the
present invention relates to use of ashless detergent additives with good
copper corrosion
properties in lubricating oil compositions where corrosion is a concern.
BACKGROUND OF THE INVENTION
A crankcase lubricant is an oil used for general lubrication in an internal
combustion engine where an oil sump is situated generally below the crankshaft
of the
engine and to which circulated oil returns. It is well known to include
additives in
crankcase lubricants for several purposes.
Among the additives that are and have been commonly included are metal-
containing detergents. These are additives that reduce formation of piston
deposits, for
example high-temperature varnish and lacquer deposits, in engines; they have
acid-
neutralising properties and are capable of keeping finely-divided solids in
suspension.
They are based on metal salts of acidic organic compounds, sometimes referred
to as
soaps. Generally, a metal detergent comprises a polar head with a long
hydrophobic tail,
the polar head comprising the metal salt.
Lubricant specifications are becoming, or have become, more exacting such as
in
limiting the amount of metal, expressed as sulfated ash. There is therefore
considerable
incentive to provide detergents that are free of metal, so-called "ashless"
detergents.
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RD 417045 describes ethoxylated methylene-bridged alkyl phenols as detergents
that are metal free, which may for example be represented by the structural
formula:
[CH2CH2O]õ H [CH2CH2O]õH
I I
O O
H2
C H
X
R, R,
wherein the "n" of the ethoxylated groups is an integer such as in the range
of 1 to
20. The compounds are described as being made by the acid-catalysed reaction
of an
alkylated phenol with paraformaldehyde to give a methylene-bridged phenol,
with
subsequent ethoxylation using ethylene oxide. Products made according to this
disclosure
comprise undesirably high levels of non-oxyalkylated (i.e. n = 0) content,
undesirably high
levels of di- and poly-oxyalkylated (i.e. n > 2) content and consequently low
levels of
mono-oxyalkylated (i.e. n = 1) content. Products with high levels of n > 2
have inferior oil
solubility, resulting in increased levels of haze and sediment. When included
within fully-
formulated oils, products with high levels of n > 2 also confer inferior
deposit control
properties. Products with high levels of n = 0 confer inferior copper
corrosion in fully-
formulated oils.
In this specification, the abbreviation `n=0' is used to denote non-
oxyalkylation;
the abbreviation `n=1' is used to denote mono-oxyalkylation; and the
abbreviation `n>2' is
used to denote poly-oxyalkylation which includes di-oxyalkylation, tri-
oxyalkylation,
tetra-oxyalkylation etc.
EP-B-0 032 617 describes lubricants that contain similar additives to those
described in RD 417045 (including an additive marketed under the trade name
"Prochinor
GR77") for controlling or eliminating emulsion-sludge formation. Preferably, n
is from 2
to 10, which is most preferably obtained by ethoxylation using ethylene oxide,
and also
prefers a molecular weight of 4,000 to 6,000.
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Neither of the above prior art references describes the benefits of maximising
n = 1
content, minimising n = 0 content and/or minimising n > 2 content. Neither of
the above
prior art references describes the effect of the additives on copper corrosion
or on deposit
control.
SUMMARY OF THE INVENTION
The present invention provides a lubricating oil composition that exhibits
superior
deposit control properties whilst minimising copper corrosion. In the
lubricating oil
composition, the value of n in the oil-soluble oxyalkylated detergent is
controlled.
In accordance with a first aspect, the present invention provides a
lubricating oil
composition comprising or made by admixing
(A) an oil of lubricating viscosity; and
(B) as an additive component, an oil-soluble mixture of oxyalkylated
hydrocarbyl
phenol condensates, wherein oxyalkyl groups prepared from phenolic functional
groups have the formula -(R'O),, where R' is an ethylene, propylene or
butylene
group, and n is independently from 0 to 10;
wherein less than 45, preferably less than 30, mole % of the phenolic
functional
groups of the condensates are non-oxyalkylated (i.e. n = 0); and
more than 55 mole % of the phenolic functional groups of the condensates are
mono-oxyalkylated (i.e. n = 1).
According to a second aspect, the present invention provides a method of
making
additive component (B) as defined in the first aspect, the method comprising
forming an
oxyalkylated hydrocarbyl phenol aldehyde condensate via the steps of (1)
condensation of
a hydrocarbyl phenol with an aldehyde, in the presence of an acid or base
catalyst, to form
a hydrocarbyl phenol-aldehyde condensate, and (2) oxyalkylating said
condensate in the
presence of a base catalyst, preferably a sodium salt, with 0.5 to less than
3, preferably less
than 2.5, preferably less than 2.0, equivalents of ethylene carbonate,
propylene carbonate
or butylene carbonate for each equivalent of phenolic functional groups within
the
condensate.
According to a third aspect, the present invention provides a method of making
an
additive component (B) as defined in the first aspect, the method including
the steps of
forming an oxyalkylated hydrocarbyl phenol-aldehyde condensate via the steps
of (1)
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oxyalkylating a hydrocarbyl phenol in the presence of a base catalyst,
preferably a sodium
salt, with 0.5 to 3, preferably to less than 2.5, preferably less than 2.0,
equivalents of
ethylene carbonate, propylene carbonate or butylene carbonate and (2)
condensation in the
presence of an acid or base catalyst of said oxyalkylated hydrocarbyl phenol
with an
aldehyde.
According to a fourth aspect, the present invention provides an additive
component
(B) as defined in the first aspect made by or obtainable by the method of the
second or
third aspects.
According to a fifth aspect, the present invention provides the use of
additive
component (B) as defined in the first or fourth aspects to improve the deposit
control
properties whilst not adversely affecting the copper corrosion properties of
the lubricant.
According to a sixth aspect, the present invention provides a method of
lubricating
surfaces of an internal combustion chamber during its operation by:
(i) providing, in a minor amount, one or more additives (B) as defined in
the first aspect in a major amount of an oil of lubricating viscosity to
make a lubricant;
(ii) providing the lubricant to the crankcase of the internal combustion
engine;
(iii) providing a hydrocarbon fuel in the combustion chamber of the engine,
and
(iv) combusting the fuel in the combustion chamber.
In this specification, the following words and expressions, if and when used,
have
the meanings ascribed below:
"active ingredient" 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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"hydrocarbyl" means a chemical group of a compound that contains only hydrogen
and carbon atoms and that is bonded to the remainder of the compound directly
via
a carbon atom;
"oil-soluble" or "oil-dispersible", or cognate terms, used herein do not
necessarily
indicate that the compounds or additives are soluble, dissolvable, miscible,
or are
capable of being suspended in the oil in all proportions. These do mean,
however,
that they are, for example, 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;
"major amount" means in excess of 50 mass % of a composition;
"minor amount" means less than 50 mass % of a composition;
"TBN" means total base number as measured by ASTM D2896;
"phosphorus content" is measured by ASTM D5185;
"sulfur content" is measured by ASTM D2622; and
"sulfated ash content" is measured by ASTM D874.
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.
Furthermore, the constituents of this invention may be isolated or be present
within
a mixture and remain within the scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The features of the invention relating, where appropriate, to each and all
aspects of
the invention, will now be described in more detail as follows:
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OIL OF LUBRICATING VISCOSITY (A)
The oil of lubricating viscosity (sometimes referred to as "base stock" or
"base
oil") is the primary liquid constituent of a lubricant, into which additives
and possibly
other oils are blended, for example to produce a final lubricant (or lubricant
composition).
Also, a base oil is useful for making concentrates as well as for making
lubricants
therefrom.
A base oil may be selected from natural (vegetable, animal or mineral) and
synthetic lubricating oils and mixtures thereof. It may range in viscosity
from light
distillate mineral oils to heavy lubricating oils such as gas engine oil,
mineral lubricating
oil, motor vehicle oil and heavy duty diesel oil. Generally the viscosity of
the oil ranges
from 2 to 30, especially 5 to 20, mm2s-1 at 100 C.
Natural oils include animal and vegetable oils (e.g. castor and lard oil),
liquid
petroleum oils and hydrorefined, solvent-treated mineral lubricating oils of
the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of lubricating
viscosity derived
from coal or shale are also useful base oils.
Synthetic lubricating oils include hydrocarbon oils such as polymerized and
interpolymerized olefins (e.g. polybutylenes, polypropylenes, propylene-
isobutylene
copolymers, chlorinated polybutylenes, poly(1-hexenes), poly(l-octenes),
poly(1-
decenes)); alkylbenzenes (e.g. dodecylbenzenes, tetradecylbenzenes,
dinonylbenzenes,
di(2-ethylhexyl)benzenes); polyphenols (e.g. biphenyls, terphenyls, alkylated
polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides
and the
derivatives, analogues and homologues thereof
Another suitable class of synthetic lubricating oils 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, 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 these esters include 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
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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 ethers such as neopentyl glycol,
trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.
Unrefined, refined and re-refined oils can be used in the compositions 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, a petroleum oil obtained directly from distillation
or ester oil
obtained directly from an esterification process and used without further
treatment would
be unrefined oil. Refined oils are similar to the unrefined oils except they
have been
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 obtain refined oils applied
to refined oils
which have been already used in service. Such re-refined oils are also known
as reclaimed
or reprocessed oils and often are additionally processed by techniques for
approval of
spent additive and oil breakdown products.
Other examples of base oil are gas-to-liquid ("GTL") base oils, i.e. the base
oil
may be an oil derived from Fischer-Tropsch synthesised hydrocarbons made from
synthesis gas containing H2 and CO 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.
Base oil may be categorised in Groups I to V according to the API EOLCS 1509
definition.
When the oil of lubricating viscosity is used to make a concentrate, it is
present in
a concentrate-forming amount (e.g., from 30 to 70, such as 40 to 60, mass %)
to give a
concentrate containing for example 1 to 90, such as 10 to 80, preferably 20 to
80, more
preferably 20 to 70, mass % active ingredient of an additive or additives,
being component
(B) above, optionally with one or more co-additives. The oil of lubricating
viscosity used
in a concentrate is a suitable oleaginous, typically hydrocarbon, carrier
fluid, e.g. mineral
lubricating oil, or other suitable solvent. Oils of lubricating viscosity such
as described
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herein, as well as aliphatic, naphthenic, and aromatic hydrocarbons, are
examples of
suitable carrier fluids for concentrates.
Concentrates constitute a convenient means of handling additives before their
use,
as well as facilitating solution or dispersion of additives in lubricants.
When preparing a
lubricant that contains more than one type of additive (sometime referred to
as "additive
components"), each additive may be incorporated separately, each in the form
of a
concentrate. In many instances, however, it is convenient to provide a so-
called additive
"package" (also referred to as an "adpack") comprising one or more co-
additives, such as
described hereinafter, in a single concentrate.
The oil of lubricating viscosity may be provided in a major amount, in
combination
with a minor amount of additive component (B) as defined herein and, if
necessary, one or
more co-additives, such as described hereinafter, constituting a lubricant.
This preparation
may be accomplished by adding the additive directly to the oil or by adding it
in the form
of a concentrate thereof to disperse or dissolve the additive. Additives may
be added to
the oil by any method known to those skilled in the art, either before, at the
same time as,
or after addition of other additives.
Preferably, the oil of lubricating viscosity is present in the lubricant in an
amount
of greater than 55 mass %, more preferably greater than 60 mass %, even more
preferably
greater than 65 mass %, based on the total mass of the lubricant. Preferably,
the oil of
lubricating viscosity is present in an amount of less than 98 mass %, more
preferably less
than 95 mass %, even more preferably less than 90 mass %, based on the total
mass of the
lubricant.
The lubricants of the invention may be used to lubricate mechanical engine
components, particularly in internal combustion engines, e.g. spark-ignited or
compression-ignited two- or four-stroke reciprocating engines, by adding the
lubricant
thereto. Preferably, they are crankcase lubricants.
The lubricating oil compositions of the invention comprise defined components
that may or may not remain the same chemically before and after mixing with an
oleaginous carrier. This invention encompasses compositions which comprise the
defined
components before mixing, or after mixing, or both before and after mixing.
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When concentrates are used to make the lubricants, they may for example be
diluted with 3 to 100, e.g. 5 to 40, parts by mass of oil of lubricating
viscosity per part by
mass of the concentrate.
The lubricants of the present invention may contain low levels of phosphorus,
namely not greater than 0.12 mass %, preferably up to 0.08 mass %, more
preferably up to
0.06 mass % of phosphorus, expressed as atoms of phosphorus, based on the
total mass of
the lubricant.
Typically, the lubricants may contain low levels of sulfur. Preferably, the
lubricant
contains up to 0.4, more preferably up to 0.3, most preferably up to 0.2, mass
% sulfur,
expressed as atoms of sulfur, based on the total mass of the lubricant.
Typically, the lubricant may contain low levels of sulfated ash. Preferably,
the
lubricant contains less than 1.0, preferably less than 0.8, more preferably
less than 0.5,
mass % sulfated ash, based on the total mass of the lubricant.
Suitably, the lubricant may have a total base number (TBN) of 5 or more,
preferably 7 or more, such as up to 16, preferably 8 to 16. This basicity may
originate
from metal bases such as overbased detergents or non-metal bases such as
nitrogen bases,
examples of which are dispersants, anti-oxidants (e.g. alkylated diphenylamine
and
phenylene diamine) and quaternary ammonium salts, or combinations thereof.
Suitably,
up to 30%, preferably up to 40%, more preferably up to 50%, even more
preferably up to
60% of the TBN in the lubricant originates from non-metal bases.
ADDITIVE COMPONENT (B)
It has been found that the use of additive component (B) comprising less than
45
mole % of n = 0 in a lubricant reduces copper corrosion more than the use of
additive
component (B) comprising 45 mole% or more of n = 0. It has also been found
that when
additive component (B) having a low mole % of n > 2 content is used in a
lubricant, the
lubricant has significantly advantageous deposit control properties.
The oxyalkylated condensates in (B) are preferably represented by the
following
general structural formula:
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[CH2CH2O]nH [CH2CH2O]nH
I I
R1
b
H
~
R
x
wherein
x is 1 to 50, preferably 1 to 40, more preferably 1 to 30;
R1 and R2 are H, hydrocarbyl groups having 1 to 12 carbon atoms, or
hydrocarbyl
groups having 1 to 12 carbon atoms and at least one heteroatom; and
R is a hydrocarbyl group having 9 to 100, preferably 9 to 70, preferably 9 to
50,
preferably 9 to 30, preferably 9 to 20 and most preferably 9 to 15 carbon
atoms.
In the above formula, R is preferably in the para position in relation to the
-O-[CH2CH2O]nH group.
In the oxyalkylated condensates in (B), less than 45, preferably less than 35,
and
more preferably less than 30, mole % of the phenolic functional groups of the
condensates
are non-oxyalkylated (i.e. n = 0).
In the oxyalkylated condensates in (B), more than 55, preferably more than 60,
preferably more than 70, more preferably more than 80, even more preferably
more than
90, and most preferably more that 95, mole % of the phenolic functional groups
of the
condensates are mono-oxyalkylated (i.e. n = 1).
Advantageously, in the oxyalkylated condensates in (B), less than 5 mole % of
the
phenolic functional groups of the condensates are poly-oxyalkylated (i.e. n
>2), which
includes di-oxyalkylation, tri-oxyalkylation, tetra-oxyalkylation etc.
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Preferably, the mixture has a number average molecular weight (MO), as
measured
by GPC, in the range of 1000 to less than 4000, such as to 3000.
Advantageously, the
mixture has a weight average molecular weight (Mw,), as measured by GPC, in
the range of
1100 to less than 6000, preferably less than 4000, such as 3500;
advantageously, M,,,/Mr, is
in the range of 1.10-1.60.
Preferably, the mixture has a number average degree of polymerization of 4-20,
such as 5-15, and more preferred 6-10.
In the above general formula, R is preferably, independently, a branched chain
alkyl group having 9 to 30 carbon atoms, preferably 9 to 15 carbon atoms, more
preferably
12 to 15 carbon atoms.
The oxyalkylated condensate mixtures of the invention are preferably made by
oxyalkylating a hydrocarbyl phenol condensate with ethylene carbonate (which
is
preferred), propylene carbonate or butylene carbonate.
Without wishing to be bound by any theory, it is believed that oxyalkylation
begins
at the terminal units of the condensate polymer and progressively moves
towards the
centre of the polymer, generating more mono-oxyalkyl (n = 1) content. However,
steric
factors inhibit reaction with central units and then further reaction can
occur with terminal
units to confer the di- and poly-oxyalkyl (i.e. n > 2) content.
Use of a carbonate for the oxyalkylation reaction is found to give rise to
much
better control of the "n" value and quantity, as required in this invention,
in comparison
with use of ethylene oxide or propylene oxide as described in the prior art.
Furthermore,
an appropriate choice of catalyst can provide a product consisting essentially
entirely of
mono-oxyalkyl (i.e. n = 1) content. Sodium salts are preferred, especially the
hydroxide
and carboxylates, such as stearate.
Suitably, additive component (B) is present in the amount of 0.1 to 10, such
as 0.1
to 5, such as 0.1 to 2, mass % based on the total lubricant mass.
CO-ADDITIVES
Co-additives, with representative effective amounts in lubricants that may
also be
present, different from additive component (B), are listed below. All the
values listed are
stated as mass percent active ingredient.
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Additive Mass % Mass %
(Broad) (Preferred)
Ashless Dispersant 0.1 - 20 1 -8
Metal Detergents 0.1 - 15 0.2 - 9
Friction modifier 0-5 0 - 1.5
Corrosion Inhibitor 0-5 0 - 1.5
Metal Dihydrocarbyl Dithiophosphate 0-10 0-4
Anti-Oxidants 0-5 0.01 - 3
Pour Point Depressant 0.01 - 5 0,01-1.5
Anti-Foaming Agent 0-5 0.001-0.15
Supplement Anti-Wear Agents 0-5 0-2
Viscosity Modifier (1) 0-6 0.01 - 4
Mineral or Synthetic Base Oil Balance Balance
(1) Viscosity modifiers are used only in multi-graded oils.
The final lubricant, typically made by blending the or each additive into the
base
oil, may contain from 5 to 25, preferably 5 to 18, typically 7 to 15, mass %
of the co-
additives, the remainder being oil of lubricating viscosity.
The above mentioned co-additives are discussed in further detail as follows;
as is
known in the art, some additives can provide a multiplicity of effects, for
example, a
single additive may act as a dispersant and as an oxidation inhibitor.
A dispersant is an additive whose primary function is to hold solid and liquid
contaminations in suspension, thereby passivating them and reducing engine
deposits at
the same time as reducing sludge depositions. 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.
Dispersants are usually "ashless", as mentioned above, being non-metallic
organic
materials that form substantially no ash on combustion, in contrast to metal-
containing,
and hence ash-forming materials. They comprise a long hydrocarbon chain with a
polar
head, the polarity being derived from inclusion of e.g. an 0, P, or N atom.
The
hydrocarbon is an oleophilic group that confers oil-solubility, having, for
example 40 to
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500 carbon atoms. Thus, ashless dispersants may comprise an oil-soluble
polymeric
backbone.
A preferred class of olefin polymers is constituted by polybutenes,
specifically
polyisobutenes (PIB) or poly-n-butenes, such as may be prepared by
polymerization of a
C4 refinery stream.
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 is
constituted by
hydrocarbon-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. Particularly 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, 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.
Preferably, the dispersant, if present, is a succinimide dispersant derived
from a
polyisobutene of number average molecular weight in the range of 1000 to 3000,
preferably 1500 to 2500, and of moderate functionality. The suceinimide is
preferably
derived from highly reactive polyisobutene.
Metal detergents are metal salts as mentioned above. The salts may contain a
substantially stoichiometric amount of the metal when they are usually
described as
normal or neutral salts and would typically have a total base number or TBN
(as may be
measured by ASTM D2896) of from 0 to 80. Large amounts of a metal base can be
included by reaction of an excess of a metal compound, such as an oxide or
hydroxide,
with an acidic gas such as carbon dioxide. The resulting overbased detergent
comprises
neutralised detergent as an outer layer of a metal base (e.g. carbonate)
micelle. Such
overbased detergents may have a TBN of 150 or greater, and typically of from
250 to 500
or more.
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Detergents that may be used include oil-soluble neutral and overbased
sulfonates,
phenates, sulfurized phenates, thiophosphonates, salicylates, and naphthenates
and other
oil-soluble carboxylates of a metal, particularly the alkali or alkaline earth
metals, e.g.
sodium, potassium, lithium, calcium and magnesium. The most commonly-used
metals
are calcium and magnesium, which may both be present in detergents used in a
lubricant,
and mixtures of calcium and/or magnesium with sodium.
Particularly preferred metal detergents are neutral and overbased alkali or
alkaline
earth metal detergents having a TBN of from 50 to 450, preferably a TBN of 50
to 250.
Highly preferred detergents include alkaline earth metal salicylates,
particularly
magnesium and calcium, especially, calcium salicylates.
The weight ratio of the additive component (B) in the lubricating oil
composition
to any metal detergents is preferably in the range of 0.1 to 4, preferably 0.1
to 3, preferably
0.1 to 2, or most preferably 0.2 to 1.6. Preferred examples of metal
detergents are calcium
salicylate, magnesium salicylate, calcium sulfonate, magnesium sulfonate,
calcium
phenate and mixtures thereof.
Friction modifiers include glyceryl monoesters of higher fatty acids, for
example,
glyceryl mono-oleate; esters of long chain polycarboxylic acids with diols,
for example,
the butane diol ester of a dimerized unsaturated fatty acid; oxazoline
compounds; and
alkoxylated alkyl-substituted mono-amines, diamines and alkyl ether amines,
for example,
ethoxylated tallow amine and ethoxylated tallow ether amine.
Other known friction modifiers comprise oil-soluble organo-molybdenum
compounds. Such organo-molybdenum friction modifiers also provide antioxidant
and
antiwear credits to a lubricating oil composition. Suitable oil-soluble organo-
molybdenum
compounds have a molybdenum-sulfur core. As examples there may be mentioned
dithiocarbamates, dithiophosphates, dithiophosphinates, xanthates,
thioxanthates, sulfides,
and mixtures thereof. Particularly preferred are molybdenum dithiocarbamates,
dialkyldithiophosphates, alkyl xanthates and alkylthioxanthates. The
molybdenum compound
is dinuclear or trinuclear.
One class of preferred organo-molybdenum compounds useful in all aspects of
the
present invention is tri-nuclear molybdenum compounds of the formula Mo3SkLõQZ
and
mixtures thereof wherein L are independently selected ligands having organo
groups with a
sufficient number of carbon atoms to render the compounds soluble or
dispersible in the oil, n
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CA 02736308 2011-04-05
is from I to 4, k varies from 4 through to 7, Q is selected from the group of
neutral electron
donating compounds such as water, amines, alcohols, phosphines, and ethers,
and z ranges
from 0 to 5 and includes non-stoichiometric values. At least 21 total carbon
atoms should be
present among all the ligands' organo groups, such as at least 25, at least
30, or at least 35
carbon atoms.
The molybdenum compounds may be present in a lubricating oil composition at a
concentration in the range 0.1 to 2 mass %, or providing at least 10 such as
50 to 2,000 ppm
by mass of molybdenum atoms.
Preferably, the molybdenum from the molybdenum compound is present in an
amount of from 10 to 1500, such as 20 to 1000, more preferably 30 to 750, ppm
based on the
total weight of the lubricant. For some applications, the molybdenum is
present in an amount
of greater than 500 ppm.
Anti-oxidants are sometimes referred to as oxidation inhibitors; they increase
the
resistance of the lubricant to oxidation and may work by combining with and
modifying
peroxides to render them harmless, by decomposing peroxides, or by rendering
an
oxidation catalyst inert. Oxidative deterioration can be evidenced by sludge
in the
lubricant, varnish-like deposits on the metal surfaces, and by viscosity
growth.
They may be classified as radical scavengers (e.g. sterically-hindered
phenols,
secondary aromatic amines, and organo-copper salts); hydroperoxide decomposers
(e.g.,
organosulfur and organophosphorus additives); and multifunctionals (e.g. zinc
dihydrocarbyl dithiophosphates, which may also function as anti-wear
additives, and
organo-molybdenum compounds, which may also function as friction modifiers and
anti-
wear additives).
Examples of suitable antioxidants are selected from copper-containing
antioxidants, sulfur-containing antioxidants, aromatic amine-containing
antioxidants,
hindered phenolic antioxidants, dithiophosphates derivatives, metal
thiocarbamates, and
molybdenum-containing compounds.
Dihydrocarbyl dithioph osphate metals salts are frequently used as antiwear
and
antioxidant agents. The metal may be an alkali or alkaline earth metal, or
aluminium,
lead, tin, zinc molybdenum, manganese, nickel or copper. Zinc salts are most
commonly
used in lubricants such as in amounts of 0.1 to 10, preferably 0.2 to 2, mass
%, based upon
the total mass of the lubricant. They may be prepared in accordance with known
techniques by first forming a dihydrocarbyl dithiophosphoric acid (DDPA),
usually by
CA 02736308 2011-04-05
reaction of one or more alcohols or a phenol with P2S5, and then neutralising
the formed
DDPA with a zinc compound. For example, a dithiophosphoric acid may be made by
reaction with mixtures of primary and secondary alcohols. Alternatively,
multiple
dithiophosphoric acids can be prepared where the hydrocarbyl groups on one
acid are
entirely secondary in character and the hydrocarbyl groups on the other acids
are entirely
primary in character. To make the zinc salt, any basic or neutral zinc
compound could be
used but the oxides, hydroxides and carbonates are most generally employed.
Commercial
additives frequently contain an excess of zinc due to use of an excess of the
basic zinc
compound in the neutralisation reaction.
Anti-wear agents reduce friction and excessive wear and are usually based on
compounds containing sulfur or phosphorous or both, for example that are
capable of
depositing polysulfide films on the surfaces involved. Noteworthy are the
dihydrocarbyl
dithiophosphates, such as the zinc dialkyl dithiophosphates (ZDDPs) discussed
herein.
Examples of ashless anti-wear agents include 1,2,3-triazoles, benzotriazoles,
thiadiazoles, sulfurised fatty acid esters, and dithiocarbamate derivatives.
Rust and corrosion inhibitors serve to protect surfaces against rust and/or
corrosion. As rust inhibitors there may be mentioned non-ionic polyoxyalkylene
polyols
and esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonic acids.
Pour point depressants, otherwise known as lube oil flow improvers, lower the
minimum temperature at which the oil will flow or can be poured. Such
additives are well
known. Typical of these additive are C8 to C18 dialkyl fumarate/vinyl acetate
copolymers
and polyalkylmethacrylates.
Additives of the polysiloxane type, for example silicone oil or polydimethyl
siloxane, can provide foam control.
A small amount of a demulsifyin component may be used. A preferred
demulsifying component is described in EP-A-330,522. It is obtained by
reacting an
alkylene oxide with an adduct obtained by reaction of a bis-epoxide with a
polyhydric
alcohol. The demulsifier should be used at a level not exceeding 0.1 mass %
active
ingredient. A treat rate of 0.001 to 0.05 mass % active ingredient is
convenient.
Viscosity modifiers (or viscosity index improvers) impart high and low
temperature operability to a lubricant. Viscosity modifiers that also function
as
dispersants are also known and may be prepared as described above for ashless
dispersants. In general, these dispersant viscosity modifiers are
functionalised polymers
16
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(e.g. interpolymers of ethylene-propylene post grafted with an active monomer
such as
maleic anhydride) which are then derivatised with, for example, an alcohol or
amine.
The lubricant may be formulated with or without a conventional viscosity
modifier
and with or without a dispersant viscosity modifier. Suitable compounds for
use as
viscosity modifiers are generally high molecular weight hydrocarbon polymers,
including
polyesters. Oil-soluble viscosity modifying polymers generally have weight
average
molecular weights of from 10,000 to 1,000,000, preferably 20,000 to 500,000,
which may
be determined by gel permeation chromatography or by light scattering.
EXAMPLES
The invention will now be particularly described in the following examples
which
are not intended to limit the scope of the claims hereof.
Example 1 - Preparation of methylene-bridged alkyl phenol
A mixture of 95% para-substituted, branched dodecylphenol (1910g), alkyl
benzene
sulfonic acid catalyst (19.1g) and toluene (574g) was heated to 110 C over 60
minutes in a
5L reactor under a blanket of nitrogen gas which remained throughout the
reaction
process. An aqueous formaldehyde solution (37%, 497g) was added stepwise over
2 hours
and 30 minutes. The temperature was increased to 120 C and the contents of the
reactor
maintained at this temperature for 1 hour and 30 minutes. The contents were
cooled to
90 C and an aqueous NaOH solution (50%, 42g) added over 35 minutes. The
contents of
the reactor were heated to 130 C over 25 minutes, kept at this temperature for
2 hours and
toluene stripped therefrom by vacuum distillation. The product was an
alkylphenol-
formaldehyde condensate in the form of a methylene-bridged alkylphenol in
which x was
from 0 to 22 or more, Mn (by GPC) = 1600, Mw = 2100, and residual monomer of
dodecylphenol < 1%.
Example 2 - Preparation of ethoxylated methylene-bridled alkyl phenol
Xylene (573g) was added to Example 1 (2004g), and then ethylene carbonate
(1.02
equivalents per hydroxyl group, 645g) at 90 C over 35 minutes. The contents of
the
reactor were heated to reflux (150-160 C). The ethylene carbonate was consumed
over 4
17
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hours, then xylene was stripped by vacuum distillation. The mixture had a
molecular
weight, as measured by GPC, of Mn = 1700, Mw = 2300, and residual monomer of
dodecylphenol < 0.1%. 13C NMR analysis of the mixture showed that it had the
following
properties with regard to the parameter n:
n mole %
0 1
1 96
>2 3
The temperature was lowered to 110 C and group I 150 neutral oil added (2278g)
and
mixed for 1 hour to make an ethoxylated methylene-bridged alkylphenol mixture
at 50%
active ingredient (4556g).
Example 3
Heavy duty diesel lube oil formulation A was prepared containing ashless
dispersant,
metal containing detergent, zinc dialkyl dithiophosphate anti-wear agent,
supplementary
antioxidant, viscosity modifier and flow improver in a base oil. Heavy duty
diesel lube oil
formulation B (sulfated ash content = 1.0%, TBN = 12.3) was prepared with the
same
amount of all the additives except that 1.5 wt% active ingredient of the
ethoxylated
methylene bridged alkyl phenol mixture of Example 2 was added in place of 1.5
wt% of
base oil. The weight ratio of the ashless detergent of Example 2 relative to
the metal
containing detergents in Heavy duty diesel lube oil formulation B was 1.2 on
an active
ingredient basis.
Both products were tested in an OM501 LA heavy duty diesel deposit test and
the merits
produced are compared in Table I.
Table I
Piston Merits
Heavy duty diesel formulation A 21.7
Heavy duty diesel formulation B 31.4
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Clearly, Heavy duty diesel formulation B containing the ashless detergent of
Example 2
exhibited significantly enhanced deposit control capability relative to Heavy
duty diesel
formulation A which contained only ash-containing detergents.
Example 4
Passenger car diesel lube oil formulation C was prepared containing ashless
dispersant,
metal containing detergent, zinc dialkyl dithiophosphate anti-wear agent,
supplementary
antioxidant, viscosity modifier and flow improver in a base oil. Passenger car
diesel lube
oil formulation D (sulfated ash content = 0.5%, TBN = 7.7) was prepared with
the same
amount of all the additives except that 0.5 wt% active ingredient of the
ethoxylated
methylene bridged alkyl phenol mixture of Example 2 was added in place of 0.5
wt% of
base oil (and the viscosity modifier level was reduced slightly). The weight
ratio of the
ashless detergent of Example 2 relative to the metal containing detergents in
Passenger car
diesel lube oil formulation D was 0.6 on an active ingredient basis.
Both products were tested in a VW TDI passenger car diesel deposit test and
the merits
produced are compared in Table II.
Table II
Piston Merits
Passenger car diesel formulation C 59
Passenger car diesel formulation D 65
Clearly, both Heavy duty diesel formulation B and Passenger car diesel
formulation D
containing the ashless detergent of Example 2 exhibited significantly enhanced
deposit
control capability relative to Heavy duty diesel formulation A and passenger
car diesel
formulation C which contained only ash-containing detergents.
Examples 5-6 and Comparative Example 1
The procedure of Example 2 was repeated with different amounts of the ethylene
carbonate reagent to produce ethoxylated methylene-bridged alkylphenol
mixtures of
formula (I) with varying amounts of oxyalkyl moieties as shown in Table III.
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Example 7
Heavy duty diesel lube oil formulation E was prepared containing ashless
dispersant,
metal containing detergent, zinc dialkyl dithiophosphate anti-wear agent,
supplementary
antioxidant, viscosity modifier and flow improver in a base oil. Heavy duty
diesel lube oil
formulation F (sulfated ash content = 1.0, TBN = 11.1) was prepared with the
same
amount of all the additives except that 1.8 wt% active ingredient of the
ethoxylated
methylene bridged alkyl phenol mixture of Examples 2, 5, 6 and Comparative
Example 1
was added in place of 1.8 wt% of base oil. The weight ratio of the ashless
detergent in
relation to the metal containing detergents in Heavy duty diesel lube oil
formulation D was
1.3 on an active ingredient basis.
All the above formulated products were tested for copper corrosion using the
High
Temperature Corrosion Bench Test ('HTCBT', ASTM D6594). The copper corrosion
results are expressed in parts per million Cu, where a lower result is
superior (<20 ppm is
considered a pass).
The results of the High Temperature Corrosion Bench Test ('HTCBT') are as
follows:
Table III
Example Equivalents of Mole % Mole % Mole % Cu
EC n=1 n=0 n>2 (ppm)
Comparative 0.58 55 45 0 91.6
Example 1
Example 6 0.75 75 25 0 43.4
Example 5 0.90 87 12 2 44.7
Example 2 1.02 96 1 3 18.2
EC = ethylene carbonate used in preparation
CA 02736308 2011-04-05
The results clearly show that a low level of non-oxyalkylated group (i.e. n=0)
is required
to maintain passing copper corrosion performance.
Example 8 - Preparation of highly capped hydroxyethyl methylene bridged alkyl
phenol
The procedure of Example 1 was repeated, on a smaller scale (branched dodecyl
phenol -
400g; alkylbenzene sulfonic acid catalyst - 4g; aqueous formaldehyde solution
(37%) -
104g), except that the 50% aqueous NaOH was replaced by an equal mass
percentage of
50% aqueous KOH (IOg). Xylene (120g) was added to the intermediate that was
produced
(418g), and then ethylene carbonate (2 equivalents per hydroxyl group, 270g)
at 90 C over
30 minutes. The contents of the reactor were heated to reflux (150-160 C).
Reaction
continued for 4 hours, when it was determined that the reaction was not
completed and
temperature was decreased. The next day, heating was resumed (165 C) for a
further 8
hours, at which point the reaction was determined to be completed. Xylene was
stripped
by vacuum distillation, leaving a viscous orange-red liquid. The temperature
was reduced
to 120 C and it was determined that, after analytical samples removal, the
weight of
product was 475g. The mixture had a molecular weight, as measured by GPC, of
Mn =
2250, Mw = 3900. 13C NMR analysis of the mixture showed that it had the
following
properties with regard to parameter n:
n mole %
0 0
1 45
Group I 150 neutral oil was added (475g) and mixed for 1 hour to make an
ethoxylated
methylene-bridged alkylphenol mixture at 50% active ingredient (950g).
Example 9 (Performance impact of higher capping)
Heavy duty diesel lube oil formulation G was prepared containing ashless
dispersant,
metal containing detergent, zinc dialkyl dithiophosphate anti-wear agent,
supplementary
antioxidant, viscosity modifier and flow improver in a base oil. Heavy duty
diesel
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formulation H was prepared with the same amount of all additives except that
1.6 wt%
active ingredient of Example 2 was added in place of 1.6 wt% base oil. Heavy
duty diesel
lube oil formulation I was prepared with the same amount of all the additives
except that
1.6 wt% active ingredient of Example 8 was substituted for the 1.6 wt% active
ingredient
of Example 2. The weight ratio of the ashless detergent relative to the metal
containing
detergents in all Heavy duty diesel lube oil formulations was 1.3.
All three formulations were tested in the Thermo-oxidation Engine Oil
Simulation Test
("TEOST" 33C ; (ASTM 6335) and the results are compared in Table IV.
Table IV
Equivalents of Mole % Mole % Mole % Deposits
Example EC n=1 n=0 n>2 (mg)
Formulation - - - - 38
G
Formulation 1.02 96 1 3 22.5
H
Formulation I 2.0 45 0 55 43
13C NMR Methodology
Quantitative 13C NMR was used to determine the n = 0, n = 1 and n > 2 contents
reported
herein. For comparing the contents of n = 0 and n = 1 in partially ethoxylated
oligomers,
the following diagram can be used:
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[CH2CH2O]õ H [CH2CH2O]õ H [CH2CH2O]õ H
I I I
O O O
C C
H*X. H2
Y
R R R
For the progression from n = 0 to n = 1, carbons A, B and C experience
chemical
shifts from 150, 147 and 116 ppm to 154, 152 and 110 ppm, respectively.
The region between 60 - 76 ppm is the chemical shift range for all of the
carbons
of the (poly-)ethoxylated groups. The internal (mono-)hydroxyethyl carbons (n
= 1) are
found at 75 and 61.4 ppm, whereas the external (mono-)hydroxyethyl carbons
(also n = 1)
are found at 69 and 60.7 ppm. On addition of one or more ethoxy units (i.e. n
> 2), these
same carbon signals shift to broad peaks at 72, 70 and 61.1 ppm. In order to
determine the
n > 2 content, it is possible to subtract the sum of the integrated values of
the two peaks at
75 and 69 ppm from the sum of the integrated values of the three peaks at
61.4, 61.1 and
60.7 ppm. Additionally, the proportion of n = 1 to n > 2 can be directly
compared (i.e., the
sum of the integrated values of the two peaks at 61.4 and 60.7 ppm versus the
integral of
the peak at 61.1 ppm) provided the resolution of the NMR makes these peaks
discernible.
23
