Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Case No. 3257
TITLE
Lubricating Composition Substantially Free of ZDDP
FIELD OF INVENTION
[0001] The present invention relates to a lubricating oil composition
containing a metal salixarate and other performance additives. The lubricating
oil composition has antiwear and detergency performance in the absence of a
metal hydrocarbyl dithiophosphate.
BACKGROUND OF THE INVENTION
[0002] It is well known for lubricating oils to contain a number of additives
used to protect the engine from wear, the accumulation of sludge and filter
plugging. Common additives for engine lubricating oils are zinc
dialkyldithiophosphate (ZDDP) as an antiwear additive, and overbased calcium
sulphonate detergents. It is believed that ZDDP antiwear additives protect the
engine by forming a protective film on metal surfaces. Typical treatment
quantities of ZDDP range from 1 to 2 weight percent based on the total weight
of
the lubricant. Detergents such as overbased calcium sulphonate help keep the
engine parts clean of soot and other deposits, and offer an alkalinity
reserve.
Typical treatment quantities of detergents range from 0.05 to 10 weight
percent
based on the total weight of the lubricant.
[0003] In recent years phosphates and sulphonates derived from engine
lubricants have been shown to contribute in part to particulate emissions.
Further, sulphur and phosphorus tend to poison the NOX catalysts used in
catalytic converters, resulting in a reduction in performance of said
catalysts.
Any reduction in the performance of catalytic converters tends to result in
increased amounts of greenhouse gases such as nitric oxide and/or sulphur
oxides. However, reducing the amount of ZDDP will increase the amount of
wear in an engine. Also reducing the amount of detergent will decrease engine
cleanliness and result in increased soot deposits.
[0004] International Publication W003/18728 (Cressey et al.) discloses
additives for lubricants containing linear compounds containing phenolic and
salicylic units in the form of oligomers or polymers. The linear compounds can
be salted with calcium and optionally cosalted with boric acid. The additives
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have detergency and/or antiwear properties. Lubricant examples contain an
ashless dispersant and a zinc dithiophosphate.
[0005] US Patent Number 6,200,936 (Moreton) discloses compounds
containing phenolic units and salicylic units in a lubricating composition.
The
compounds can be salted with calcium. The . examples of lubricating
compositions contain phenolic units with a dodecyl alkyl group. The compounds
of the invention can be used as a detergent in gasoline or diesel fuel. They
also
stabilise gasoline or diesel compositions against thermal decomposition.
[0006] International Publication W099/25793 (Taylor) discloses a fuel
composition containing kerosene and compounds containing phenolic units and
salicylic units. The compounds can be salted with calcium. The examples of
lubricating compositions contain phenolic units with a dodecyl alkyl group.
[0007] International Publication WO01/56968 (Taylor et al.) discloses a
cyclic compound containing phenolic units and salicylic units. The salicylic
units can be salted with a metal or an ammonium cation.
[0008] European Patent Application 1 262 538 A2 (Locke et al.) discloses a
metal detergent derived from an aromatic carboxylic acid, a metal detergent
derived from phenol capable of imparting oxidation resistance in a lubricating
oil
composition. In a preferred embodiment the aromatic carboxylic acid is a
salicylic acid substituted with an alkyl group.
[0009] It has now been found that the composition of the present invention
provides detergency and antiwear performance to an oil of lubricating
viscosity
often used in an engine oil and said composition is substantially free of a
metal
hydrocarbyl dithiophosphate.
SUMMARY OF THE INVENTION
[0010] The present invention provides a composition comprising:
(a) a metal salixarate;
(b) at least one additive selected from the group consisting of (1) an
antioxidant; (2) a friction modifier; (3) a dispersant; (4) a viscosity
modifier; (5)
a dispersant viscosity modifier; and (6) an antiwear agent other than a metal
hydrocarbyl dithiophosphate; and
(c) an oil of lubricating viscosity, wherein the composition contains
about 400 ppm or less of phosphorus derived from a metal hydrocarbyl
dithiophosphate.
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[0011] The invention further provides a process for the preparation of a
composition comprising mixing:
(a) a metal salixarate;
(b) at least one additive selected from the group consisting of (1) an
antioxidant; (2) a friction modifier; (3) a dispersant; (4) a viscosity
modifier; (5)
a dispersant viscosity modifier; and (6) an antiwear agent other than a metal
hydrocarbyl dithiophosphate; and
(c) an oil of lubricating viscosity, wherein the composition contains
about 400 ppm or less of phosphorus derived from a metal hydrocarbyl
dithiophosphate. '
[0012] The use of the composition of the invention imparts one or more of
improved engine cleanliness, decreased wear, decreased NOX emissions and
'decreased particulate emissions.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention provides a composition as described above.
Often the composition has a total sulphur content below 0.5 wt %, preferably
below 0.3 wt %, more preferably 0.1 wt % and most preferably near 0 wt %.
Often the major source of sulphur in the composition of the invention is
derived
from diluent oil. Usually the diluent oil is used in the manufacturing
processes
used for preparing many of the component (b) additives. Excluding the diluent
oil, the composition of the invention often have a sulphur content of 700 ppm
or
less, preferably 600 ppm or less, more preferably 300 ppm or less, even more
preferably 100 ppm or less and most preferably 50 ppm or less such as less
than
30 ppm, 25 ppm or less, 20 ppm or less and 15 ppm or less. When sulphur from
the diluent oil is included, the sulphur content of the composition is often
increased by up to 800 ppm, preferably up to 600 ppm and most preferably up to
400 ppm, for instance about 200 ppm or about 300 ppm.
[0014] Often the composition has a total phosphorus content below 0.1 wt %,
preferably equal to or less than 0.085 wt %, more preferably equal to or less
than
0.07 wt %, even more preferably equal to or less than 0.055 wt % and most
preferably equal to or less than 0.05 wt % of the composition, such as 200 ppm
or less, preferably 100 ppm or less, more preferably 50 ppm or less and most
preferably 10 ppm or less. In one embodiment the phosphorus is present from 1
ppm or 10 ppm to 50 ppm or 200 ppm.
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[0015] Often the composition has a total ash content as determined by ASTM
D-874 is below 1.5 wt %, preferably equal to or less than 1.1 wt %, more
preferably equal to or less than 1.0 wt %, even more preferably equal to or
less
than 0.8 wt % and most preferably equal to or less than 0.5 wt % of the
composition. In one embodiment the total ash content is present from 0.1 wt %
or0.2wt%to0.6wt%or0.7wt%.
Salixarate Salt Detergent
[0016] The substrate of the metal salixarate of the invention is often
represented by one or a mixture of substantially linear compounds comprising
at
least one unit of the formulae (I) or (II):
(~>
or
(B>
each end of the compound having a terminal group of formulae (III) or (IV):
(OH)f
1
~~ ~R4)9
COORS
(III) (IV)
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such groups being linked by divalent bridging groups, which may be the same or
different for each linkage; wherein in formulas (I)-(IV) f is 1, 2 or 3,
preferably 1
or 2; U is -OH, -NH2 -NHR1, -N(Rl)z or mixtures thereof, R1 is a hydrocarbyl
group containing 1 to 5 carbon atoms; R2 is hydroxyl or a hydrocarbyl group
and
j is 0, 1, or 2; R3 is hydrogen or a hydrocarbyl group; R4 is a hydrocarbyl
group
or a substituted hydrocarbyl group; g is 1, 2 or 3, provided at least one R4
group
contains 8 or more carbon atoms; and wherein the molecules on average contain
at least one of unit (I) or (III) and at least one of unit (II) or (IV) and
the ratio of
the total number of units (I) and (III) to the total number of units of (II)
and (IV)
in the composition overall is about 0.1:1 to about 2:1, although individual
molecules within the composition may fall outside this range.
[0017] The U group in formulae (i) and (iii) may be located in one or more
positions ortho, meta, or para to the -COORS group. Preferably the U group is
located ortho to the -COORS group. When the U group is a -OH group,
formulae (i) arid (iii) are derived from 2-hydroxybenzoic acid (often called
salicylic acid), 3-hydroxybenzoic acid, 4-hydroxybenzoic acid or mixtures
thereof. When U is a -NH2 group, formulae (i) and (iii) are derived from 2-
aminobenzoic acid (often called anthranilic acid), 3-aminobenzoic acid,
4-aminobenzoic acid or mixtures thereof.
[0018] The divalent bridging group, which may be the same or different in
each occurrence, includes -CHa- (methylene bridge) and -CH~OCH2- (ether
bridge), either of which may be derived from an aldehyde such as formaldehyde
or a formaldehyde equivalent (e.g., paraform, formalin), ethanal or propanal.
[0019] The metal of the metal salixarate is often mono-valent, di-valent or
mixtures thereof. Preferably the metal is selected from an alkali metal or
alkaline earth metal such as magnesium, calcium, potassium or sodium, although
magnesium, calcium, potassium or mixtures thereof are most preferred.
[0020] It is believed that a significant fraction of salixarate molecules
(prior
to neutralisation) may be represented on average by the following formula:
s
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H
group, provided at least one RS is alkyl. In a preferred embodiment, RS is a
polyisobutene group (especially of molecular weight 200 to 1,000, or about
550).
Significant amounts of di-or trinuclear species may also be present containing
one salicylic end group of formula (III). The salixarate detergent may be used
alone or with other detergents.
[0021] Salixarate derivatives and methods of their preparation are described
in greater detail in U.S. patent number 6,200,936 and PCT Publications WO
01/56968 and WO 03/18728. It is believed that the salixarate derivatives have
a
predominantly linear, rather than macrocyclic, structure, although both
structures
are intended to be encompassed by the term "salixarate." Additionally "Linear"
does not exclude branching or other structures in the substituent R groups.
[0022] The metal salixarate is often present on an oil free basis at 0.01 to
20,
preferably 0.1 to 10, more preferably 0.2 to 8 and most preferably 0.5 to 5
weight percent of the composition.
Component (b) Additives
The present invention contains at least one additive selected from the group
consisting of (1) an antioxidant; (2) a friction modifier; (3) a dispersant;
(4) a
viscosity modifier; (5) a dispersant viscosity modifier; and (6) an antiwear
agent
other than a metal hydrocarbyl dithiophosphate; and
[0023] The present invention contains at least one additive selected from the
group consisting of (1) an antioxidant; (2) a friction modifier; (3) a
dispersant;
(4) a viscosity modifier; (5) a dispersant viscosity modifier; and (6) an
antiwear
agent other than a metal hydrocarbyl dithiophosphate. Often 2 or more and most
preferably 3 or more of additives (1)-(6) are present in the invention.
[0024] Often the amount of each of the additives (1)-(6) are present on an oil
free basis at 0 to 25, preferably 0.1 to 20, more preferably 0.3 to 15 and
most
preferably 1 to 10 weight percent of the composition, with the proviso that at
least one additive is present at 0.1 or more weight percent of the
composition.
6
w>
wherein each RS can be the same or different, and are hydrogen or an alkyl
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Antioxidant
[0025] When present in the invention the antioxidant often includes a
diphenylamine antioxidant, a hindered phenol antioxidant, or mixtures thereof.
° [0026] Other antioxidant additives such as a molybdenum
dithiocarboamate
or a sulphurised olefin may also be added to the composition of the invention,
although preferably the composition is substantially free of a molybdenum
dithiocarboamate or a sulphurised olefin. As used herein the term
"substantially
free of a molybdenum dithiocarboamate or a sulphurised olefin" means the
composition will contain a molybdenum dithiocarboamate or a sulphurised olefin
present at less than 100 ppm, preferably less than 20ppm and most preferably 1
ppm or less.
[0027] When present, the diphenylamine suitable for the invention is often
represented by the formula:
(VI)
(R6)Z ~7)z
wherein are independently a hydrocarbyl group; and z is zero or higher,
provided
that on at least one ring, z is non-zero. Often the hydrocarbyl group contains
1
to 24, preferably 2 to 1~ and most preferably 4 to 12 carbon atoms.
[0028] Examples of suitable diphenylamine antioxidants include octyl
diphenylamine, nonyl diphenylamine, bis-octyl diphenylamine, bis-nonyl
diphenylamine or mixtures thereof.
[0029] When present, the diphenylamine is often present on an oil free basis
at 0.01 to 20, preferably 0.05 to 10, more preferably 0.1 to 5 and most
preferably
0.2 to 3 weight percent of the composition.
[0030] When present, the hindered phenol suitable for the invention is often
represented by the formula:
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R8
HO (~)
E
Ry
[0031] wherein R$ and R9 are independently branched or linear alkyl groups
containing 1 to 24, preferably 4 to 18, and most preferably 4 to 12 carbon
atoms;
and E is hydrogen, a hydrocarbyl group, a bridging group linking to a second
aromatic group, an ester-containing group, or mixtures thereof.
[0032] R$ and R9 may be either straight or branched chain; branched is
preferred. Suitable examples of R8. and R9 include secondary butyl and
tertiary
butyl.
[0033] In one embodiment, the hindered phenol of formula (VII) suitable for
the invention are esters or acids represented by the formula:
Ra
CH2CH2C(O)ORlo (VIIa)
R9
[0034] wherein R$ and R~ are as defined above and R1° is hydrogen, a
hydrocarbyl group or mixtures thereof.
[0035] When R1° is a hydrocarbyl group, Rl° is preferably
selected from the
group consisting of butyl, sec-butyl, isobutyl, tert-butyl, pentyl, n-hexyl,
sec-
hexyl, n-octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl and mixtures
thereof.
[0036] In one embodiment, the hindered phenol of formula (VII) suitable for
the invention contains a bridging group. Examples of suitable bridging groups
include an alkylene bridge or an ether bridge, often containing 1 to 8,
preferably
1 to 6, more preferably 1 to 4 and most preferably 1 to 2 carbon atoms.
Examples of a suitable bridge group include -CH2-, -CH2CH2-, -CH20CH2- and
-CH2CH20CH2CH2-.
[0037] When present, the hindered phenol with a bridging group is often
represented by the formula:
s
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R$
Y OH (VIIb)
R9
R~
wherein R11 and R12 are defined above and Y is a bridging group. Examples of a
methylene-bridged hindered phenol include 4,4 -methylene-bis-(6-tert-butyl-o-
a
cresol), 4,4 -methylene-bis-(2-tert-amyl-o-cresol) and 4,4 -methylene-bis-(2,6-
di-
tertbutylphenol).
[0038] The hindered phenol of the invention also includes compounds
represented by the formula:
OH
RF R9
Y
(VIII)
wherein R8, E and Y are defined above. Examples of a suitable methylene-
bridged hindered phenol of formula (VIII) include 2,2~-methylene-bis-(4-methyl-
6-tert-butylphenol), and 2,2~-methylene-bis-(4-ethyl-6-tert-butylphenol), 2,2~-
methylene-bis-(4-propyl-6-tert-butylphenol).
[0039] When present, the hindered phenol is often present on an oil free basis
at 0.01 to 25, preferably 0.1 to 20, more preferably 0.5 to 15 and most
preferably
1 to 10 weight percent of the composition.
Dispersant
[0040] When present, the invention further includes a dispersant often derived
from N-substituted long chain alkenyl succinimide or mixtures thereof. The
dispersants can be used alone or in combination with other dispersants.
[0041] The N-substituted long chain alkenyl succinimides have a variety of
chemical structures and include a mono-succinimide and/or a di-succinimide.
Often the long chain alkenyl group will have number average molecular weight
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of 35'0 to 10,000, preferably 400 to 7000, more preferably 500 to 5000 and
most
preferably 500 to 4000. In one embodiment the long chain alkenyl group is a
polyisobutylene group, which has a number average molecular weight from 800
to 1600 and in another embodiment from 1600 to 3000. The succinimide is often
prepared by the condensation of a hydrocarbyl-substituted acylating agent
(e.g.,
hydrocarbyl-substituted succinic anhydride) with a polyamine or an amino
alcohol, often a polyalkylene polyamine or poly(ethyleneamine) such as
triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine or, in
one embodiment, polyamine still bottoms.
[0042] N-substituted long chain alkenyl succinimides dispersant additives and
their preparation are disclosed, for instance, in US Patent Numbers 3,361,673,
3,401,118 and 4,234,435.
[0043] Another class of suitable dispersants include Mannich bases, which
are the reaction products of alkyl phenols in which the alkyl group typically
contains at least 30 carbon atoms with aldehydes (especially formaldehyde) and
amines (especially polyalkylene polyamines) and are described in more detail
in
U.S. Patent 3,634,515.
[0044] Another class of ashless dispersant is high molecular weight esters.
These materials are similar to the above-described succinimides except that
they
may be seen as having been prepared by reaction of a hydrocarbyl acylating
agent and a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or
sorbitol. Such materials are described in more detail in U.S. Patent
3,381,022.
[0045] Other dispersants include polymeric dispersant additives, which are
generally hydrocarbon-based polymers which contain polar functionality to
impart dispersancy characteristics to the polymer.
[0046] Dispersants may also be post-treated by reaction with any of a variety
of agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon
disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted
succinic
anhydrides, nitrites, epoxides, boron compounds, and phosphorus compounds.
References detailing such treatment are listed in U.S. Patent 4,654,403.
[0047] When present, the dispersant is often present on an oil free basis at
0.01 to 20, preferably 0.1 to 15, more preferably 0.2 to 10 and most
preferably
0.5 to 6 weight percent of the composition.
Friction Modifiers
to
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[0048] When present in the invention, the friction modifier can be a
monoester of a polyol and an aliphatic carboxylic acid, often an acid
containing
12 to 24 carbon atoms. Often the monoester of a polyol and an aliphatic
carboxylic acid is in the form of a mixture with a sunflower oil or the like,
which
may be present in the friction modifier mixture from 5 to 95, preferably 10 to
90,
more preferably 20 to 85 and most preferably 20 to 8,0 weight percent of said
mixture.
[0049] Polyols include diols, triols, and alcohols with higher numbers of
alcoholic OH groups. Polyhydric alcohols include ethylene glycols, including
di-, tri- and tetraethylene glycols; propylene glycols, including di-, tri-
and
tetrapropylene glycols; glycerol; butane diol; hexane diol; sorbitol;
arabitol;
mannitol; sucrose; fructose; glucose; cyclohexane diol; erythritol; and
pentaerythritols, including di- and tripentaerythritol; preferably, diethylene
glycol, triethylene glycol, glycerol, sorbitol, pentaerythritol and
dipentaerythritol.
[0050] The aliphatic carboxylic acids which form the esters are those acids
containing 12 to 24 carbon atoms. Acids containing straight chain hydrocarbyl
groups containing 12 to 24 carbon atoms are preferred, for instance, 14 to 20
or
16 to 18 carbon atoms. Such acids can be used in combinatiomwith acids with
more or fewer carbon atoms as well.
[0051] Generally the acid is a monocarboxylic acid. Examples of carboxylic
acids include dodecanoic acid, stearic acid, lauric acid, behenic acid, and
oleic
acid.
[0052] The esters used in the present invention are in particular the
monoesters of such polyols and such carboxylic acids. A preferred ester is
glycerol monooleate. It is to be understood that glycerol monooleate, as is
the
case with other such materials, in its commercially available grade, is a
mixture
which includes such materials as glycerol, oleic acid, other long chain acids,
glycerol dioleate, and glycerol trioleate. The commercial material is believed
to
include about 60 ~ 5 percent by weight of the chemical species "glycerol
monooleate," along with 35 ~ 5 percent glycerol dioleate, and less than about
5
percent trioleate and oleic acid. The amounts of the monoesters, described
below, are calculated based on the actual, corrected, amount of polyol
monoester
present in any such mixture.
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[0053] Other friction modifiers that are suitable for the invention include
fatty amines, fatty phosphites, fatty acid amides, fatty epoxides, alkoxylated
fatty
amines, metal salts of fatty acids, sulfurised olefins, fatty imidazolines,
condensation products of carboxylic acids and polyalkylene-polyamines, amine
salts of alkylphosphoric acids. Preferably the friction modifier is free of
sulphur
and/or phosphorus.
[0054] When present, the friction modifier is often present on an oil free
basis at 0.01 to 20, preferably 0.05 to 10, more preferably 0.1 to 5 and most
preferably 0.2 to 3 such as 0.5 to 2 weight percent of the composition.
Viscosity Modifiers
[0055] When present in the invention the viscosity modifier is often an olefin
copolymer. The olefin copolymer backbone often contains two to four,
preferably two to three and most preferably two different olefin monomers. The
olefin monomers often contain 2 to 20, preferably 2 to 10, more preferably 2
to 6
and most preferably 2 to 4 carbon atoms.
[0056] When present, the viscosity modifiers are often present on an oil free
basis at of 0.01 to 15, preferably 0.05 to 10, more preferably 0.1 to 5 and
most
preferably 0.2 to 3 weight percent of the composition.
[0057] The olefin copolymer preferably contains an ethylene monomer and at
least one other comonomer derived from an alpha-olefin having the formula
HZC=CHR1°, wherein R1° is a hydrocarbyl group, preferably an
alkyl radical
containing 1 to 18, preferably 1 to 10, more preferably 1 to 6 and most
preferably 1 to 3 carbon atoms. The hydrocarbyl group includes an alkyl
radical
that has a straight chain, a branched chain or mixtures thereof.
[0058] Examples of suitable comonomers include propylene, 1-butene,
1-hexene, 1-octene, 4-methylpentene-1, 1-decene, 1-dodecene, 1-tridecene,
1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene,
1-nonadecene or mixtures thereof. Preferably the comonomer is 1-butene,
propylene or mixtures thereof. Example of olefin copolymers include ethylene-
propylene copolymers or ethylene-butene-1 copolymers.
[0059] Other viscosity modifiers suitable for the invention include polymeric
materials including hydrogenated styrene-butadiene rubbers, hydrogenated
styrene-isoprene polymers, hydrogenated radical isoprene polymers,
polymethacrylate acid esters, polyacrylate acid esters, polyalkyl styrenes,
alkenyl
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aryl conjugated dime copolymers, polyalkylmethacrylates, esters of malefic
anhydride-styrene copolymers or mixtures thereof.
[0060] Optionally the olefin copolymer of the invention is further grafted
with an unsaturated dicarboxylic acid anhydride or derivatives thereof and an
amine to form a dispersant viscosity modifier (often referred to as DVM), thus
named because they also exhibit dispersant properties. DVM additives and their
preparation are disclosed, for instance, in US Patent Numbers 6,107,258 and
6,107,257.
[0061] Examples of olefin copolymer DVM's include those commercially
available from DSM as PA1250TM, PA1260TM and PA1274TM as well as Hitec
5777TM (commercially available from Ethyl Corporation).
[0062] Often the dispersant viscosity modifier is selected from the group
consisting of (a) an olefin copolymer grafted with an unsaturated dicarboxylic
acid anhydride or derivatives thereof and an amine; (b) a polymethacrylate
functionalised with an amine; (c) an esterified copolymer comprising (i)
styrene,
(ii) an unsaturated dicarboxylic acid anhydride or derivatives thereof,
optionally
functionalised with an amine; and mixtures thereof. Often DVM's derived from
a polymethacrylate and/or a styrene copolymer are prepared by reacting with an
amine as described in US Patent Numbers 6,107,258 and 6,107,257. The DVM
can be used alone or in combination with other DVM's.
[0063] When present, the dispersant viscosity modifier is often present on an
oil free basis at 0.01 to 10, preferably 0.05 to 6, more preferably 0.08 to 4
and
most preferably 0.1 to 2 weight percent of the composition.
Antiwear Agents
[0064] The composition of the invention may additionally contain an
antiwear agent other than a metal hydrocarbyl dithiophosphate. Suitable
antiwear agents include phosphoric acid esters or salt thereof; phosphites;
and
phosphorus-containing carboxylic esters, ethers, and amides or mixtures
thereof.
Preferably the composition of the invention is substantially free of
phosphorus-
and/or sulphur-containing antiwear agents. In one embodiment of the invention
the composition is free of antiwear agents.
[0065] As used herein the term "substantially free of antiwear agents
containing sulphur and/or phosphorus" means the composition will contain
antiwear agents present at less than 50 ppm, preferably less than 10 ppm and
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most preferably 1 ppm or less. In one embodiment of the invention no antiwear
agents containing sulphur andlor phosphorus are present. In one embodiment of
the invention 1 ppm to 15 ppm of antiwear agents containing sulphur and/or
phosphorus are present.
Oils of Lubricating Viscosity
[0066] The lubricating oil composition of the present invention may be added
to an oil of lubricating viscosity. The oil includes natural and synthetic
oils, oil
derived from hydrocracking, hydrogenation, hydrofinishing, unrefined, refined
and re-refined oils, or mixtures thereof.
[0067] Unrefined oils are those obtained directly from a natural or synthetic
source generally without (or with little) further purification treatment.
[0068] 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. Purification techniques are known in the art and include solvent
extraction, secondary distillation, acid or base extraction, filtration,
percolation
and the like.
[0069] Re-refined oils are also known as reclaimed or reprocessed oils, and
are obtained by processes similar to those used to obtain refined oils and
often
are additionally processed by techniques directed to removal of spent
additives
and oil breakdown products.
[0070] Natural oils useful in making the inventive lubricants include animal
oils, vegetable oils (e.g., castor oil, lard oil), mineral lubricating oils
such as
liquid petroleum oils and solvent-treated or acid-treated mineral lubricating
oils
of the paraffinic, naphthenic or mixed paraffinic-naphthenic types and oils
derived from coal or shale or mixtures thereof.
[0071] Synthetic lubricating oils are useful and include hydrocarbon oils such
as polymerised and interpolymerised olefins (e.g., polybutylenes,
polypropylenes, propyleneisobutylene copolymers); poly(1-hexenes), poly(1-
octenes), poly(1-decenes), and mixtures thereof; alkyl-benzenes (e.g.
dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)-
benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls);
alkylated diphenyl ethers and alkylated diphenyl sulphides and the
derivatives,
analogs and homologs thereof or mixtures thereof. Preferably the synthetic
lubricating oils are free of alkylated diphenyl sulphides.
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[0072] Other synthetic lubricating oils include but are not limited to polyol
esters, liquid esters of phosphorus-containing acids (e.g., tricresyl
phosphate,
trioctyl phosphate, and the diethyl ester of decane phosphonic acid), and
polymeric tetrahydrofurans. Synthetic oils may be produced by Fischer-Tropsch
reactions and typically may be hydroisomerised Fischer-Tropsch hydrocarbons
or waxes. Preferably the synthetic lubricating oils are free of phosphorus-
containing esters.
[0073] Oils of lubricating viscosity may also be defined as specified in the
American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The
five base oil groups are as follows: Group I (sulphur content >0.03 wt %,
and/or
<90 wt % saturates, viscosity index 80-120); Group II (sulphur content <0.03
wt
%, and >90 wt % saturates, viscosity index 80-120); Group III (sulphur content
<0.03 wt %, and >90 wt % saturates, viscosity index >120); Group IV (all
polyalphaolefins (PAO's)); and Group V (all others not included in Groups I,
II,
III, or IV). The oil of lubricating viscosity is selected from the group
consisting
of an API Group I, II, III, IV, V oil and mixtures thereof; preferably an API
Group II, III, IV or V oil and mixtures thereof; and most preferably an API
Group III, IV or V oil and mixtures thereof. If the oil of lubricating
viscosity is
an API Group II, III, IV or V oil there may be up to a maximum of 20 wt %,
preferably up to a maximum of 10 wt %, more preferably up to a maximum of 5
wt % and most preferably up to a maximum of 1.5 wt % of the lubricating oil an
API Group I oil.
[0074] Examples of suitable API Group III oils include NexbaseTM 3050,
NexbaseTM 3043, YubaseTM 4, YubaseTM 6, and ShellTM XHVI 5.2.
[0075] The oil of lubricating viscosity is often present at up to 99.98,
preferably up to 99.8, more preferably up to 99.65 and most preferably up to
99.3 weight percent of the composition.
[0076] If the present invention is in the form of a concentrate (which can be
combined with additional oil to form, in whole or in part, a finished
lubricant),
the ratio of each of the above-mentioned dispersant, as well as other
components,
to diluent oil is often 80:20 to 10:90 by weight.
Metal Hydrocarbyl Dithiophosphate
[0077] The invention is substantially free of to free of a metal hydrocarbyl
dithiophosphate often represented by the formula:
is
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R11~O
-O/ P\\ M' (XIV)
n
wherein R11 and R12 are independently hydrogen, hydrocarbyl groups or mixtures
thereof, provided that at least one of R11 and R12 is a hydrocarbyl group,
preferably alkyl or cycloalkyl with 1 to 30, preferably 2 to 20 and most
preferably 2 to 15 carbon atoms.
[0078] The term "substantially free of" means that the composition contains
400 ppm or less of phosphorus, preferably 300 ppm or less of phosphorus, more
preferably 200 ppm or less of phosphorus, even more preferably 100 ppm or less
of phosphorus and most preferably 100 ppm or less of phosphorus such as 50
ppm, 20 ppm or 1 ppm or less, derived from a metal hydrocarbyl
dithiophosphate. In one embodiment of the invention the composition contains
0.5 ppm or lOppm to 50 ppm of phosphorus derived from a metal hydrocarbyl
dithiophosphate. In one embodiment of the invention the composition is free of
a metal hydrocarbyl dithiophosphate.
[0079] M' is a metal, and n is an integer equal to the available valence of
M'.
M' is mono- or di- or tri- valent, preferably divalent, more preferably a
divalent
transition metal. In one embodiment M' is zinc. In one embodiment M' is
calcium. In one embodiment M' is barium. Examples of a metal hydrocarbyl
dithiophosphate include zinc dihydrocarbyl dithiophosphates (often referred to
as
ZDDP, ZDP or ZDTP).
Other Performance Additives
[0080] The composition of the invention optionally further includes other
performance additives. The other performance additives selected from the group
consisting of detergents other than those of component (a) of the invention,
corrosion inhibitors, antiscuffing agents, foam inhibitors, demulsifiers, pour
point depressants seal swelling agents and mixtures thereof.
[0081] The total combined amount of the other performance additives present
on an oil free basis is often from 0 to 20, preferably 0.01 to 15, more
preferably
0.05 to 10 and most preferably 0.1 to 5 weight percent of the composition.
Although one or more of the other performance additives may be present, it is
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common for the other performance additives to be present in different amounts
relative to each other.
[0082] Detergents other than those of component (a) of the invention are
known and include neutral or overbased, Newtonian or non-Newtonian, basic
salts of alkali, alkaline earth and transition metals with one or more of a
phenate,
a sulphonate, a carboxylic acid, a phosphorus acid, a mono- and/or a di-
thiophosphoric acid, a saligenins, an alkylsalicylate or mixtures thereof.
Commonly used metals include sodium, potassium, calcium, magnesium lithium
or mixtures thereof. Most commonly used metals include sodium, magnesium
and calcium. Preferably the composition of the invention is free of detergents
containing sulphur and/or phosphorus.
(0083] Other performance additives such as corrosion inhibitors including
octylamine octanoate, condensation products of dodecenyl succinic acid or
anhydride and a fatty acid such as oleic acid with a polyamine; metal
deactivators including derivatives of benzotriazoles, 1,2,4-triazoles,
benzimidazoles, 2-alkyldithiobenzimidazoles or 2-alkyldithiobenzothiazoles;
foam inhibitors including copolymers of ethyl acrylate and 2-
ethylhexylacrylate
and optionally vinyl acetate; demulsifiers including trialkyl phosphates,
polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene
oxide-propylene oxide) polymers; pour point depressants including esters of
malefic anhydride-styrene, polymethacrylates, polyacrylates or
polyacrylamides;
and seal swell agents including Exxon Necton-37TM (FN 1380) and Exxon
Mineral Seal Oil (FN 3200); may also be used in the composition of the
invention.
Process
[0084] The invention further provides a process for the preparation of a
composition as described above.
[0085] Components (a)-(c) are often mixed sequentially, separately for the
composition of the invention. The mixing conditions are often 15°C to
130°C,
preferably 20°C to 120°C and most preferably 25°C to
110°C; and for a period of
time in the range 30 seconds to 48 hours, preferably 2 minutes to 24 hours,
more
preferably 5 minutes to 16 hours and most preferably 10 minutes to 5 hours;
and
at pressures in the range 86 kPa to 266 kPa (650 mm Hg to 2000 rnm Hg),
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preferably 91 kPa to 200 kPa (690 mm Hg to 1500 mm Hg), and most preferably
95 kPa to 133 kPa (715 mm Hg to 1000 mm Hg).
[0086] The process optionally includes mixing other optional performance
additives as described above. The optional performance additives are often
added sequentially, separately or as a concentrate.
Industrial Application
[0087] The composition of the present invention is useful in an internal
combustion engines, for example diesel fuelled engines, gasoline fuelled
engines, natural gas fuelled engines or a mixed gasoline/alcohol fuelled
engines.
[0088] In one embodiment of the invention provides a method for lubricating
an internal combustion engine, comprising supplying thereto a lubricant
comprising the composition as described herein. The use of the composition of
the invention is capable of imparting one or more of the group selected from
improved engine cleanliness, decreased wear, decreased NOX emissions and
decreased particulate emissions.
[0089] The following examples provide an illustration of the invention.
These examples are non exhaustive and are not intended to limit the scope of
the
invention.
EXAMPLES
Preparative Example l: Preparation of Salixarate Substrate - Salixarene
[0090] A sample of a salixarene substrate is prepared using a flange flask
approximately 2 litres in volume, a flange and clip, overhead stirrer with
paddle
and polytetrafluoroethylene (PTFE) stirrer gland, Dean Stark trap and double
surface condenser, an electric mantle/thermocouple/EurothermTM temperature
controller system, the glassware from just above the mantle to just below the
condenser being covered with glass wool. The flask is filled with 4758
polyisobutenyl phenol derived from high vinylidene polyisobutylene with a
number average molecular weight of 550 (GLISSOPAL~550 commercially
available from BASF) and 330g of mineral oil (SN 150) and heated to
30°C via a
pressure equalizing dropping funnel 3.4g of 50% aqueous KOH is added. The
contents of the flask are heated to 75°C and the temperature is kept
constant for
30 minutes while 81.6g of 37% aqueous formaldehyde (formalin) is added. The
reaction is charged with 51.6g of salicylic acid and heated to 140°C
while
controlling reflux. Water is removed using Dean Stark trap. The product is
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vacuum stripped at 140°C/l3kPa (equivalent to 100mm Hg) for 30 minutes.
A
more detailed description of the reaction process is given in Examples 1 and 5
of
International Publication W003/018728, pages 22 and 23.
Preparative Example 2: Calcium Salixarate
[0091] A vessel is charged with 12008 of the salixarene from Preparative
Example 1, 258 of ethylene glycol, 1308 of calcium hydroxide and 4108 of 2-
ethylhexanol. The vessel and contents are heated to 95°C and stirred
under
vacuum (64 kPa, which is equivalent to 480mm Hg). The vessel and contents
are then subject to vacuum at 6.7 kPa (equivalent to 50mm Hg) for 15 minutes
and heated to 130°C. The vessel is then charged with an additional 1208
of
ethylene glycol added dropwise over 10 minutes before carbon dioxide is added
via a dip tube under a slight negative pressure at 1.0 g/minute or less until
488
are added. Upon completion of carbon dioxide addition, the dip tube is removed
and the temperature is increased to 200°C under a vacuum of 6.7 kPa
(equivalent
to 50mm Hg) to remove solvents. The residue is vacuum filtered through a
l2mm diatomaceous earth pad in a sintered funnel yielding a viscous brown
liquid.
Preparative Example 3: Magnesium Salixarate
I
[0092] A vessel is charged with 560.58 of the salixarene from Preparative
Example 1 with 4338 of xylene. The vessel and contents are heated to
35°C
under a nitrogen atmosphere where 538 of magnesium oxide is added. The
vessel is then charged with 20.28 of glacial acetic acid and then a mixture of
methanol (428) and water (308) is added. The vessel and contents are heated to
61°C and carbonated. The vessel and contents are held at 61°C
for a further 2
hours and a further mixture of methanol (368) and water (26.28) is added. The
vessel heated to 150°C and held for 1 hour. The product is vacuum
stripped.
Preparative Example 4: Potassium Salixarate
[0093] A vessel is charged with 3138 of the salixarene from Preparative
Example 1, and heated under a nitrogen atmosphere to 80°C where
12.18 of
potassium hydroxide in 7g of water is added dropwise followed by the addition
of 858 of a diluent oil. The vessel and contents are heated to 110°C
for 10
minutes, then heated to 120°C for 90 minutes and heated to 140°C
for 3 hours. A
dark brown product is formed.
Reference Example 1
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[0094] A composition is prepared by mixing (a) 42.5g of Nexbase TM3050 oil,
(b) 34.4g of NexbaseTM 3043 oil, (c) on a an oil free basis 0.4g of an amine
dispersant viscosity modifier, (d) on a an oil free basis 2.8g of
polyisobutylene
succinimide dispersants, (e) 5g of antioxidants including a diphenylamine and
a
hindered phenol, (f) 0.7g of an olefin copolymer viscosity modifier and (g) a
glycerol monooleate friction modifier. The composition contains 0 wt % of
calcium, 0 wt % of phosphorus, 190 ppm of sulphur and 0 wt % of zinc. The
composition has a KV 100 of 13.11 mm2/s (cSt) and a sulphated ash content of 0
wt %.
Reference Example 2: Top Tier European Passenger Car Oil Formulation
[0095] Reference Example 2 is a successful European top tier passenger car
oil formulation containing zinc dithiophosphate. The elemental analysis of the
oil formulation indicates a calcium content of 3307ppm, a phosphorus content
of
889ppm, a sulphur content of 2645ppm and a zinc content of 889ppm. The oil
formulation has a KV 100 of 11.3 mm2ls (cSt) and sulphated ash content of 1.26
wt %.
Example 1
[0096] Example 1 has the same composition as Reference Example 1 except
2.5g (on an oil free basis) of the product of Preparative Example 2 is also
added.
The phosphorus content is 0 wt % and the sulphur content is 190 ppm (all
derived from diluent oil).
Example 2
[0097] Example 2 has the same composition as Reference Example 1 except
2.5g (on an oil free basis) of the product of Preparative Example 3 is also
added.
The phosphorus content is 0 wt % and the sulphur content is 190 ppm (all
derived from diluent oil).
Example 3
[0098] Example 3 has the same composition as Reference Example 1 except
2.5g (on an oil free basis) of the product of Preparative Example 4 is also
added.
The phosphorus content is 0 wt % and the sulphur content is 190 ppm (all
derived from diluent oil).
[0099] A number of lubricating oil compositions are formed using Reference
Example 1 and adding examples 1-3 at 2.5g on a oil free basis to the oil thus
forming "Lubricating Oil Composition with Example 1", Example 2 is titled
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"Lubricating Oil Composition with Example 2" and "Lubricating Oil
Composition with Example 3." Reference example 1 and the corresponding
Lubricating Oil Composition with examples 1-3 have a KV100 of 13.11 mm2/s
(or cSt).
Test 1: HFRR of Examples 1-3 and Reference Examples 1-2
[0100] Lubricating Oil Composition with Example 1-3 are and Reference
Example 1-2 are evaluated for wear performance in a programmed temperature
high frequency reciprocating rig (HFRR) available from PCS Instruments. HFRR
conditions for the evaluations are 200g load, 75 minute duration, 1000
micrometer stroke, 20 hertz frequency, and temperature profile of 15 minutes
at
40°C followed by an increase in temperature to 160°C at a rate
of 2°C per
minute. Wear scar in micrometers and film formation as percent film thickness
are measured with lower wear scar values and higher film formation values
indicating improved wear performance.
[0101] The percent film thickness is based on the measurement of electrical
potential between an upper and a lower metal test plate in the HFRR. When the
film thickness is 100%, there is a high electrical potential for the full
length of
the 1000 micrometre stroke, suggesting no metal to metal contact. Conversely
for a film thickness of 0% there is no electrical potential suggesting
continual
metal to metal contact between the plates. For intermediate film thicknesses,
there is an electrical potential suggesting the upper and lower metal test
plate
have a degree of metal to metal contact as well as other areas with no metal
to
metal contact. The wear scar and film formation results obtained are presented
in Table 1:
Table 1: HFRR Wear Scar and Film Formation Data
Example Wear Scar Film Formation
Lubricating Oil Composition Example128 70
1
Lubricating Oil Composition Example174 19
2
Lubricating Oil Composition Example169 30
3
Reference Example 1 189 12
Reference Example 2 126 88
Test 2: Cameron Plint of Example 1 and Reference Examples 1-2
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[0102] The Cameron Plint TE-77TM is a reciprocating wear tester. In this test
a steel ball upper specimen is reciprocated against a steel flat lower
specimen.
The Cameron Plint is charged with 10m1 of sample and heated to 50°C
and held
for 1 minute. The sample is then subject to a load of 100N over two minutes
while at the same time the reciprocation is started at 10 Hz over l5mm stroke
length. The sample is then heated to 250°C at 3°C per minute. At
the end of the
test the average diameter of the wear scar (in micrometers) on the ball
(measured
in the X and Y directions) is measured using a calibrated microscope. The
results obtained are:
Table 2: Cameron Plint Wear Scar Data
Example Wear Scar
Lubricating Oil Composition Example 1 396
Reference Example 1 ~ 753
Reference Example 2 517
Test 3: 4 Ball Wear Test Using ASTM D4172
[0103] The "Lubricating Oil Composition Example 4" and "Lubricating Oil
Composition Example 5" used in this test are the same as the "Lubricating Oil
Composition Example 1" except "Example 4" contains 2g on a oil free basis of
the product of Preparative Example 2 and delivering about 1900 ppm of calcium
and a TBN of about 146; and "Example 5" contains 1.2g on a oil free basis of
the
product of preparative Example 2 and delivering about 1300 ppm of calcium and
a TBN of about 146. Reference Example 3 has the same oil composition as
Reference Example 1, except a calcium alkylsalicylate (commercially available
from AC60CTM range of products from Infineum) is added in sufficient quantity
to deliver about 1300 ppm of calcium and a TBN of about 146. Reference
Example 4 has the same oil composition as Reference Example 1, except a
magnesium saligenin (commercially available from The Lubrizol Corporation) is
added in sufficient quantity to deliver about 1300 ppm of magnesium and a TBN
of about 146.
[0104] The ASTM D4172 test is run on a number of examples using the
modified B conditions indicated on page Section 8 of ASTM D 4172 - 94
(reapproved 1999). The wear scar is measured in micrometers. The results
obtained are:
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Table 2: ASTM D4172 Wear Scar Data
Example Wear Scar
Lubricating Oil Composition Example 4 416
Lubricating Oil Composition Example 5 433
Reference Example 1 583
Reference Example 4 483
Reference Example 5 482
[0105] Overall the analysis of the data from Test 1 and Test 2 shows the
compositions of the invention produce good antiwear and film formation results
compared with reference example 1. The analysis also indicates that the
lubricating oil composition example 1 has antiwear and film formation results
comparable with a successful European top tier passenger car oil formulation
containing zinc dithiophosphate.
[0106] In this specification the terms "hydrocarbyl substituent" or
"hydrocarbyl group," as used herein are used in its ordinary sense, which is
well-
known to those skilled in the art. Specifically, it refers to a group
primarily
composed of carbon and hydrogen atoms and is attached to the remainder of the
molecule through a carbon atom and does not exclude the presence of other
atoms or groups in a proportion insufficient to detract from the molecule
having
a predominantly hydrocarbon character. In general, no more than two,
preferably no more than one, non-hydrocarbon substituent will be present for
every ten carbon atoms in the hydrocarbyl group; typically, there will be no
non-
hydrocarbon substituents in the hydrocarbyl group. A more detailed definition
of the terms "hydrocarbyl substituent" or "hydrocarbyl group," is described in
US Patent Number 6, 583,092.
[0107] Each of the documents referred to above is incorporated herein by
reference. Except in the Examples, or where otherwise explicitly indicated,
all
numerical quantities in this description specifying amounts of materials,
reaction
conditions, molecular weights, number of carbon atoms, and the like, are to be
understood as modified by the word "about." Unless otherwise indicated, each
chemical or composition referred to herein should be interpreted as being a
commercial grade material which may contain the isomers, by-products,
derivatives, and other such materials which are normally understood to be
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present in the commercial grade. However, the amount of each chemical
component is presented exclusive of any solvent or diluent oil, which may be
customarily present in the commercial material, unless otherwise indicated. It
is
to be understood that the upper and lower amount, range, and ratio limits set
forth herein may be independently combined. Similarly, the ranges and amounts
for each element of the invention can be used together with ranges or amounts
for any of the other elements. As used herein, the expression "consisting
essentially of" permits the inclusion of substances that do not materially
affect
the basic and novel characteristics of the composition under consideration.
24
