Note: Descriptions are shown in the official language in which they were submitted.
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LUBRICATING OIL COMPOSITIONS HAVING
IMPROVED LOW TEMPERATURE PROPERTIES
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
[001] The present invention relates to lubricating oils of improved low
temperature properties, especially viscometrics, and low pour points, and to a
method for improving the low temperature properties, especially viscometrics,
and reducing the pour points of gas-to-liquid (GTL) lubricating oils.
DESCRIPTION OF THE RELATED ART
[002] Lubricating oils and formulated lubricating oils (i.e., lubricating oils
comprising mixtures of lubricating oil base stocks/base oils with one or more
performance additives) used in most lubrication processes must be capable of
delivering lubrication performance at low temperatures, be they low startup
temperature or sustained low operating temperature.
[003] To this end, lubricating oils, having better low temperature properties,
especially reduced low temperature viscometrics, are desirable. It is
important
that these lubricant oils can flow at very low temperature to critical machine
or
engine parts to provide lubrication functions. This flowability of lube base
stock
or finished product, as measured by pour point measurement, is one of the
critical low temperature properties and can be measured easily by a standard
pour point method. Base stocks of low pour points are the desirable starting
base stocks/base oils for lubricating oils, be they lubricating oils used per
se (that
is without additives) or lubricating oil compositions (that is, lubricating
oils
formulated with at least one performance additive), also called formulated
lubricating oils.
[004] The pour point of a lubricating oil is traditionally defined as that
temperature at which a quantity of lubricating base stock/base oil, or of
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formulated lubricating oil does not move from a beaker when the beaker is
tilted
at angle. Pour point can be measured by standard method ASTM D-97 or
similar automated versions. Although pour point of a base stock measures the
lowest temperature at which the oil still flows, it is also a good indicator
for the
low temperature properties. Usually, lower pour point indicates better low
temperature properties or better low temperature viscometrics.
[005] Lubricating base stock/base oil pour point is usually a reflection of
the
wax content of said base stock/base oil. Wax is predominantly a linear
paraffin
which solidifies at low temperature. The pour point of lubricating base
stock/base oil can be reduced, therefore, by removing wax from the base
stock/base oil. For certain specially synthesized lube base stocks, such as
polyalphaolefins, which contain no crystallizable wax, the pour point of the
base
stock is usually determined by the viscosity of the fluid at low temperature.
At
very low temperature when the viscosity of the base stock increases to so high
a
level that it stops flowing within the D97 test time frame, this temperature
is
recorded as the pour point even though there is no wax formation in the base
stock.
[006] Historically and traditionally wax is removed from lubricating base
stock/base oil by dewaxing processes which are identified as being either
solvent
dewaxing process or catalytic dewaxing process.
[007] In solvent dewaxing processes the lubricating base stock/base oil
containing wax, hereinafter "waxy lube base stock" is contacted with a solvent
such as methyl ethyl ketone (MEK) and/or methyl isobutyl ketone (MIBK)
and/or toluene, etc., the temperature being reduced in the course of the
contact-
ing step to precipitate out the wax as a solid. The solid wax is then removed
from the cold oil/solvent mixture by decantation, centrifugation or filtration
through a filter, the oil/solvent passing through the filter and the wax being
deposited on the filter as a filter cake which is subsequently removed from
the
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filter element material such as by scraping. The recovered wax is known as
slack wax.
[008) Alternatively a solvent known as an autorefrigerative solvent can be
used. Such solvent(s) is/are liquefied propane and/or propylene and/or butane
and/or butylene which is/are mixed with the waxy lube oil under pressure, the
pressure subsequently being reduced which causes a reduction in temperature of
the entire mixture and a precipitation of solid wax which is then separated
from
the oil, again by, e.g., decantation, centrifugation or filtration.
[009] Solvent dewaxing constitutes the physical removal of wax from the waxy
oil with subsequent recovery of the wax as a separated stream or product.
[010] Catalytic dewaxing removes wax from waxy oil by the conversion of
wax into smaller hydrocarbon materials. The substantially linear long chain
paraffins (n-paraffins) which constitute the wax are cracked into shorter
chain
paraffins which have lower pour points or into paraffins which have so short a
chain length as to be.gases or non-lubricating oil range hydrocarbons.
[011] Catalytic dewaxing physically changes the wax into shorter chain length
molecules.
[012] Other dewaxing process, which also involves the use of a catalyst, are
hydrodewaxing or hydroisomerization. Either is a process whereby linear long
chain paraffins or long chain paraffins containing some branching (i.e.,
isoparaffins) are converted into more heavily branched isoparaffins by
rearrangement, i.e., by isomerization accompanied by some limited cracking. In
this way the wax is not actually removed from the oil but is converted into
another form of paraffins (i.e., into isoparaffins) which have pour points
lower
than the substantially linear long chain wax paraffins. This type of fluids is
sometimes called "chemically modified mineral oils".
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[013] In some instances, depending on the isomerization catalyst employed the
hydroisomerized lubricating oil may be subjected to a subsequent solvent or
catalytic dewaxing step to remove the residual long chain n-paraffins and the
only slightly branched iso-paraffins so as to further reduce the pour point.
[014] Another way to reduce the pour point of lubricating base stock/base oil
is
the use of one or more pour point depressing (PPD) performance additives.
[015] Pour point depressing additives are themselves large molecular which
function by interfering with the coagulation/solidification of the linear long
chain paraffins in the waxy lube oil as temperature is reduced.
[016] PPDs are used in low concentrations, usually 0.01 to about 3.0 wt% of
the lubricating base stock/base oil.
[017] PPDs are typically polymeric materials of high molecular weight and
include polymethacrylate, polyalkylmethacrylate, alkylated naphthalene, vinyl
acetate-fumarate copolymers, polyarylamides, condensation products of
haloparaffin waxes and aromatic compounds, vinyl carboxylate polymer, and
terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl
ethers.
[018] Limited amounts of such pour point depressants are used because the
addition of too much of the pour point depressant can have detrimental effects
on the oil being treated, e.g., the pour point can go up or the oil
solidifies.
[019] USP 3,396,114 teaches a dual purpose lubricant comprising a quantity of
tricresyl phosphate, a neutral calcium sulfonate, a poly (C4_20 alkyl)
methacrylate
viscosity index improver (about 10,000 to 30,000 molecular weight), a hindered
phenol antioxidant, about 0.5 to 2.0 volume percent of a paraffin wax
alkylated
naphthalene lubricating oil pour point depressant, an alkyl ester of a
chlorinated
fatty acid, an anti foamant and a petroleum lubricating base oil.
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[020] The pour point depressant is a wax alkylated naphthalene which is
identified as a well known PPD for lubricating oil, generally prepared by
chlorinating paraffin wax and condensing the chlorowax with naphthalene (see
also USP 1,815,022 and USP 2,015,748).
[021] USP 2,671,051 teaches low pour point lubricants made by adding to a
waxy hydrocarbon lubricating oil wherein the wax is predominantly normal
aliphatic hydrocarbon waxes, a pour point depressant in an amount in the range
of 75 to 150% based on the weight of said waxes of at least one extraneous
hydrocarbon wax bearing a cyclic end group on an aliphatic hydrocarbon chain,
the chain differing from the average normal aliphatic hydrocarbon wax chain
length by no more than about 4 carbon atoms. The pour point depressant can be
at least one extraneous naphthenic wax bearing a naphthenic end group having
an aliphatic hydrocarbon side chain or an extraneous aromatic wax bearing an
aromatic end group having an aliphatic hydrocarbon side chain, the aromatic
end
group being a dicyclic aromatic group, e.g., naphthalene.
[022] USP 4,753,745 teaches methylene linked aromatic pour point depressant
of the general formula
Ar (R) Ar' (R') In - Ar"
wherein Ar, Ar' and Ar" are independently an aromatic moiety containing 1 to 3
aromatic rings and each aromatic moiety is substituted with zero to 3
substituents, (R) and (R') are independently an alkylene group containing
about 1
to 100 carbon atoms with the proviso that at least one of (R) or (R') is CH2
and n
is zero to about 1000. The material has a molecular weight varying from about
271 to about 300,000.
[023] WO 2004/08 1 1 57 teaches a lubricant composition based on Fischer-
Tropsch (F-T) derived base oils having a pour point from -15 to -31 C obtained
by a catalytic dewaxing step and containing a pour point depressant additive,
and
15 wt% or greater of a Detergent Inhibitor (DI) additive package. Suitable
pour
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point depressants are alkylated naphthalene, and phenolic polymers,
polymethacrylates, maleate/fumarate copolymer esters, methacrylate vinyl
pyrrolidone copolymer or vinyl acetate-fumarate copolymer. Preferred amounts
used range from 0.1 wt% to preferably not more than 0.3 wt%.
[024] WO 02/04578 teaches compositions comprising blends of API Group II
and/or Group III base stocks and alkylated fused and/or polyfused aromatic
compositions, such as alkylated naphthalenes which exhibit excellent additive
solvency, thermo-oxidative stability, hydrolytic stability and seal swell
characteristics.
[025] USP 6,071,864 is directed to catalystic methods for the preparation of
arylated polyolefins for use as synthetic lubricants. The aryl moiety can be
benzene, naphthalene, furan, thiophene, anthracene, phenanthrene, etc.
[026] USP 5,132,478 is directed to alkylaromatic lubricant fluids. Aromatic
compounds are alkylated with C20-Ci300 olefinic oligomers using an acidic
alkylation catalyst to produce alkylated aromatic products exhibiting high
viscosity index and low pour point. They are described as also being useful as
additives such as dispersants, detergents, VI improvers, extreme
pressure/antiwear additives, antioxidants, pour point depressants,
emulsifiers,
demulsifiers, corrosion inhibitors, anti-rust inhibitors, anti-staining
additives,
friction modifiers and the like.
[027] USP 5,602,086 teaches lubricant compositions comprising mixtures of
polyalphaolefins and alkylated aromatic fluids. The alkyl aromatic can be
alkylated naphthalene having a kinematic viscosity at 100 C ranging from about
4 mm2/s to about 30 mm2/s. The mixture is characterized by improved oxidation
resistance.
[028] USP 4,714,794 teaches mixture of specific mono-alkylated naphthalenes
as synthetic oil having excellent oxidation stability and useful as a thermal
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medium oil or as the main component of a synthetic lubricating oil. The
mixture
of specific mono-alkylated naphthalenes can be incorporated with mineral oils
and/or known lubricating oils in amounts which do not impair their high oxida-
tion stability. The mineral oils and/or known lubricating oils may be added in
amounts up to 75% by weight, preferably up.to 50% by weight, more preferably
up to 25% by weight.
[029] USP 4,604,491 teaches mixtures of monoalkylated naphthalene and
polyalkylated naphthalenes having a viscosity at 210 F between 61 and 88 SUS,
a viscosity index between 105 and 136 and a flash point (COC = Cleveland
Open Cup) of between 508 F and 560 F, useful as a synthetic oil for functional
fluids and greases.
[030] Publication No. US 2005/0077209 is directed to a process for producing
lubricant base oils with optimized branching.
[031] The lubricants are characterized as having low pour points and extremely
high viscosity indexes. The lubricants are produced by hydroisomerization
dewaxing of waxy feed using a shape selective intermediate pore size molecular
sieve to produce an intermediate oil isomerate in which the extent of
branching
is less than 7 alkyl branches per 100 carbons and solvent dewaxing the inter-
mediate oil isomerate to produce a lube oil wherein the extent of branching is
less than 8 alkyl branches per 100 carbon atoms and less than 20 wt% of the
alkyl branches are at the 2 position, the lube base oil having a pour point of
less
than -8 C, a kinematic viscosity at 100 C of about 3.2 mm2/s or greater, a VI
greater than a Target VT as calculated as follows:
Target VI = 22 x ln (kinematic viscosity at 100 C)
[032] It is stated that this base oil can be blended with preferably less than
95
wt% of conventional Group I, Group II and Group III base stocks, isomerized
petroleum wax oils, polyalpha olefins, poly internal olefins, diesters, polyol
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esters, phosphate esters, alkylated aromatics and mixtures thereof. Alkylated
aromatics are identified as synthetic lubricants produced from the alkylation
of
aromatics with haloalkanes, alcohols or olefins in the presence of a Lewis or
Bionstead acid catalyst. Useful examples include alkylated benzene and
alkylated naphthalene which have good low temperature properties and may
provide improved additive solubility.
[033] USP 6,627,779 teaches an improved method for preparing a blended lube
base oil comprising at least one highly paraffinic Fischer-Tropsch (F-T) lube
base stock and at least one base stock composed of alkyl aromatic, alkylcyclo-
paraffins or mixtures thereof to improve the yield of lube base oils from F-T
facilities. The alkyl aromatics, alkylcycloparaffins or mixtures thereof are
present in an amount of from about I wt% to about 50 wt%. The alkylaromatic
are alkyl aromatics boiling in the lube oil boiling ranges and are alkyl
benzene,
alkylnaphthalene, alkyltetralines of alkyl polynuclear aromatics. Preferably
the
alkyl aromatic is alkyl benzene. Fischer-Tropsch synthesis process product is
fractionally distilled to produce a C20+ fraction, a light aromatics fraction
and a
light Fischer-Tropsch products fraction containing olefins, alcohols and
mixtures
thereof. The light aromatics fraction is alkylated with the light Fischer-
Tropsch
product fraction to yield the alkyl aromatics.
[034] The blended lube base oils are described as having excellent viscosity
and viscosity index properties. Only blends with alkyl benzene or alkyl
cyclohexane are exemplified. There is no mention about the pour points or low
temperature viscometrics for the blends containing alkylbenzene.
[035] Gas-to-liquids base stocks usually have pour points ranging from 0 C to
-25 C. If one tries to produce GTL derived base stocks with pour points much
below -25 C, the process lube yield will be decreased significantly, which is
undesirable. Therefore, it would be a significant technical advance if a way
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could be found to reduce the pour point of GTL base stock/base oil by ways
other than through conventional solvent dewaxing or catalytic dewaxing, or
through an increase in the intensity of the hydrodewaxing or
hydroisomerization
procedure.
DESCRIPTION OF THE FIGURE
[036] Figure 1 graphically presents pour points of blend fluids vs. wt%
alkylnaphthalene fluid (AN), ester, a low pour point alkylbenzene fluid (Ar
PAO) and a C20-C24 alkylbenzene (C2024AB) prepared according to prior art, all
in a 6 cSt GTL base stock (GTL 6). This graph demonstrates the effects
alkylated naphthalene fluid and the low pour point alkylbenzene (Ar PAO) have
on lowering the pour point of GTL base stock.
DESCRIPTION OF THE INVENTION
[037] A method is disclosed for reducing the pour point of gas-to-liquids
(GTL) lube base stocks/base oils or hydrodewaxed or hydroisomerized/catalytic
(or solvent) dewaxed wax derived base stocks/base oil(s) by adding to such
base
stocks/base oils from about 1 to 95 wt% preferably 5 to 80 wt%, more
preferably
to 60 wt% of an alkylated aromatic synthetic fluid. When the alkyl aromatic
synthetic fluid is alkyl naphthalene, said alkylated naphthalene synthetic
fluid,
has a kinematic viscosity at 100 C falling in the range from about 1.5 mm2/s
to
about 600 mm2/s, preferably from about 2 mm2/s to about 300 mm2/s, more
preferably from about 2 mm2/s to about 100 mm2/s, a pour point of 0 C or less,
preferably -15 C or less, more preferably -25 C or less, still more preferably
-35 C or less, a viscosity index in the range of from about 0 to 200,
preferably
about 50 to 150, more preferably about 50 to 145.
[038] When the synthetic alkyl aromatic fluid is alkyl benzene said alkyl
benzene synthetic fluid has a kinematic viscosity falling in the range from
about
1.5 mm2/s to 600 mm2/s, preferably from about 2 mm2/s to about 300 mm2/s,
more preferably about 2 mm2/s to 100 mm2/s, a pour point of 0 C or less,
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preferably -15 C or less, more preferably -25 C or less, still more preferably
-
35 C or less, most preferably -60 C or less, a viscosity index in the range of
from about 0 to 200, preferably about 70 to 200, more preferably about 80 to
180.
[039] Kinematic Viscosity (KV) is determined by ASTM D 445. Pour point is
determined by ASTM D 97. Viscosity Index (VI) is determined by ASTM D
2270.
[040] Base stock means a lubricating oil produced by a single manufacturer to
a particular specification regardless of feed stock source, manufacturer's
location
or process used, and identified by a specific identification formula or number
or
code. Base oil is one or a mixture of base stocks meeting the particular oil
component requirement of a specific lubricating oil product specification,
e.g.,
specific engine oil, turbine oil, etc., finished product performance
requirements.
[041] Gas-to-liquids (GTL) base stocks/base oils, and hydrodewaxed or
hydroisomerized/catalytic (and/or solvent) dewaxed wax derived base
stock(s)/base oil(s) defined in greater detail below, have many outstanding
lubricant properties. However, they are known to be highly paraffinic in
nature
and non-polar, resulting in their having poor solubility for polar additives
used in
many high quality, high performance lubricating oil formulations. They also
have poor solvency and dispersancy for degradation products or sludges formed
in the lubricant over long service times. Esters have been used to improve
solvency and dispersivity but esters are expensive and have performance
deficiencies.
[042] It has been discovered that the pour point and low temperature
properties
of such base stock/base oil especially GTL base stock/base oil can be
improved,
as can be the base stock/base oil solvency and dispersancy by combining into
said base stock/base oil a particular alkylated aromatic selected from
alkylated
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naphthalenes and/or low pour point alkylated benzene or their hydrogenated
analogues.
[043] The alkylated naphthalene used in the present method differs from the
alkylated naphthalene pour point depressants disclosed in the prior art. The
alkylated naphthalenes used in the present invention are alkyl naphthalene
fluids
having kinematic viscosity at 100 C falling in the range of from 1.5 to 600
mm2/s and having pour points of 0 C or less and VI in the range of 0 to 200.
They are flowable liquids at room temperature.
[044] The fluid alkylated naphthalenes used in the present invention have the
following general formula:
n
Rm
wherein n + m = 1 to 8, preferably 1 to 6, more preferably 1 to 5, and R is Ct-
C30, preferably CI-C20 linear alkyl group, C3-C300, preferably C3-CIoo, more
preferably C3-C30 branched alkyl group or mixtures of such groups with the
total
number of carbons in R. and Rn, preferably being at least 4.
[045] Examples of typical alkyl naphthalenes are mono-, di-, tri-, tetra-, or
penta-C3 alkyl naphthalene, C4 alkyl naphthalene, C5 alkylnaphthalene, C6
alkyl
naphthalene, C8 alkyl naphthalene, CIo alkyl naphthalene, C12 alkyl
naphthalene,
C14 alkyl naphthalene, C16 alkyl naphthalene, C18 alkyl naphthalene, etc., CIo-
C14
mixed alkyl naphthalene, C6-C18 mixed alkyl naphthalene, or the mono-, di-,
tri-
, tetra-, or penta C3, C4, C5, C6, C8, Clo, C12, C14, C16, C18 or mixture
thereof alkyl
monomethyl, dimethyl, ethyl, diethyl, or methylethyl naphthalene, or mixtures
thereof. The alkyl group can also be branched alkyl group with Clo to C3oo,
e.g.,
C24"C56 branched alkyl naphthalene, C24-C56 branched alkyl mono-, di-, tri-,
tetra- or penta- C1-C4 naphthalene. These branched alkyl group substituted
naphthalenes or branched alkyl group substituted mono-, di-, tri-, tetra- or
penta
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C1-C4 naphthalene can also be used as mixtures with the previously recited
materials. These branched alkyl group can be prepared from oligomerization of
small olefins, such as C5 to C24 alpha- or internal-olefins. When the branched
alkyl group is very large (that is 8 to 300 carbons), usually only one or two
of
such alkyl groups are attached to the naphthalene core. The alkyl groups on
the
naphthalene ring can also be mixtures of the above alkyl groups. Sometimes
mixed alkyl groups are advantageous because they provide more improvement
of pour points and low temperature fluid properties. The fully hydrogenated
fluid alkylnaphthalenes can also be used for blending with GTL base stock/base
oil, but the alkyl naphthalenes are preferred.
[046] Typically the alkyl naphthalenes are prepared by alkylation of
naphthalene or short chain alkyl naphthalene, such as methyl or di-methyl
naphthalene, with olefins, alcohols or alkylchlorides of 6 to 24 carbons over
acidic catalyst inducing typical Friedel Crafts catalysts. Typical Friedel-
Crafts
catalysts are A1C13, BF3, HT, zeolites, amorphous alumniosilicates, acid
clays,
acidic metal oxides or metal salts, USY, etc.
[047] Methods for the production of alkylnaphthalenes suitable for use in the
present invention are described in USP 5,034,563, USP 5,516,954, USP
6,436,882 as well as in references cited in those patents as well as taught
elsewhere in the literature. Because alkylated naphthalene synthesis
techniques
are well known to those skilled in the art as well as being well documented in
the
literature such techniques will not be further addressed herein.
[048] The naphthalene or mono- or di-substituted short chain alkyl
naphthalenes can be derived from any conventional naphthalene-producing
process from petroleum, petrochemical process or coal process or source
stream.
Naphthalene-containing feeds can be made from aromaticization of suitable
streams available from the F-T process. For example, aromatization of olefins
or
paraffins can produce naphthalene or naphthalene-containing component (DE84-
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3414705, US20060138024 Al). Many medium or light cycle oils from
petroleum refining processes contain significant amounts of naphthalene,
substituted naphthalenes or naphthalene derivatives. Indeed, substituted
naphthalenes recovered from whatever source, if possessing up to about three
alkyl carbons can be used as raw material to produce alkylnaphthalene for this
invention. Furthermore, alkylated naphtahlenes recovered from whatever source
or processing can be used in the present method, provided they possess
kinematic viscosities, VI, pour point, etc., as previously recited.
[049] Suitable alkylated naphthalenes are available commercially from
ExxonMobil Chemical Company under the tradename Synesstic AN or from
King Industries under the tradename NA-Lube naphthalene-containing fluids.
[050] As previously indicated, alkylated benzene of the following structure
with viscosity at 100 C of 1.5 to 600 cS, VI of 0 to 200 and pour point of 0 C
or
less, preferably -15 C or less, more preferably -25 C or less, still more
preferably -35 C or less, most preferably -60 C or less are useful for this
invention.
RX
I
In this structure, x = 1 to 6, preferably 1 to 5, more preferably 1 to 4. When
it is
monoalkylated benzene, the R can be linear Clo to C30 alkyl group or a CIo-
C300
branched alkyl group preferably CIo-Cloo branched alkyl group, more preferably
C15-C50 branched alkyl group. When n is 2 or greater than 2, one or two of the
alkyl group can be small alkyl radical of C, to C5 alkyl group, preferably CI-
C2
alkyl group. The other alkyl group or groups can be any combination of linear
CIo-C30 alkyl group, or branched CIo and higher up to C3oo alkyl group,
preferably C15-C50 branched alkyl group. These branched large alkyl radicals
can be prepared from the oligomerization or polymerization of C3 to C20
internal
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or alpha-olefins or mixture of these olefins. The total number of carbons in
the
alkyl subsitutents ranged from CIo to C300. Preferred alkyl benzene fluids can
be
prepared according to USP 6,071,864 or USP 6,491,809 or EP 0,168,534.
[051] In accordance with the present invention the alkylated benzene is
preferably prepared by the method comprising the steps of:
(a) oligomerizing one or more alpha olefins or internal olefins to form olefin
dimers and some higher oligomers; and
(b) arylating the olefin oligomers with benzene or a short alkyl chain (C1-C5
alkyl group) mono or poly substituted benzene to yield the alkylated benzene
product.
[052] An a-olefin or internal olefins is oligomerized in the presence of
promoted catalyst to give predominantly olefin dimer and higher oligomers.
Once the reaction has gone to completion, an aromatic composition containing
one or more aromatic compounds is reacted with the oligomers, in the presence
of the same catalyst, to give alkylated aromatic lube base stocks in high
yield.
[053] In preferred embodiments, the a-olefin has from 6 to about 20 carbon
atoms. In more preferred embodiments, the a-olefin has from about 8 to about
16
carbon atoms. In especially preferred embodiments the a-olefin has from about
8
to about 14 carbon atoms.
[054] In accordance with the present invention, one or more a-olefins are
oligomerized to form predominantly olefin dimer, with some trimer or higher
oligomers. In preferred embodiments the olefin dimer has from about 20 to
about 36 carbon atoms, more preferably from about 20 to about 28 carbon
atoms. In another embodiment, one or more internal olefins, by themselves or
mixed with a-olefins are oligomerized to form oligomers, which can further be
alkylated with an aromatic compound. The preferred internal olefins starting
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material are C8 to C30 internal olefins, preferably C 10 to C20, more
preferably
C12 to C18.
[055] . The aromatic moiety is benzene _or a short chain (CI -C5 alkyl group)
or
hydroxy, alkoxy, aroxy alkylthio, or arylthio mono or poly substituted
benzene,
preferably CI -C5 alkyl group mono or poly substituted benzene, more
preferably
toluene, o-, m- or p-xylene, ethylene benzene, di-ethyl benzene, n- or iso-
propyl
benzene, di-n- or di-isoparopyl benzene, n-iso or tert-butyl benzene, di- no-
or
di-iso or di-tert butyl benzene.
[056] The catalysts used include a Lewis acid catalyst such as BF3, A1C1,
triflic acid, BC13, AlBr3, SnC14, GaC13, an acid clay catalyst, or an acidic
zeolite,
for example zeolite Beta, USY, Mordenite, Montmorillonite, or other acidic
layered, open-structure zeolites, such as MCM-22, MCM-56 or solid superacids,
such as sulfated zirconia, and activated WoX/ZrOZ. In particularly preferred
embodiments, the catalyst is BF3 or A1C13 or their promoted versions.
[057] It is known that catalysts such as those described herein are
advantageously employed in conjunction with a promoter. Suitable promoters
for use with the catalysts in the present invention include those known in the
art,
for example water, alcohols, or esters, or acids.
[058] A preferred catalyst is MCM-56. MCM-56 is a member of the MCM-
22 group useful in the invention which includes MCM-22, MCM-36, MCM-49
and MCM-56. MCM-22 is described in U.S. Pat. No. 4, 954, 325. MCM-36 is
described in U.S. Pat. No. 5,250,277 and MCM-36 (bound) is described in U.S.
Pat. No. 5,292,698. MCM-49 is described in U.S. Pat. No. 5,236, 575 and
MCM-56 is described in U.S. Pat. No. 5,362,697.
[059] The catalysts as mixed metal oxide super acids comprise an oxide of a
Group IVB metal, preferably zirconia or titania. The Group IVB metal oxide is
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modified with an oxyanion of a Group VIB metal, such as an oxyanion of
tungsten, such as tungstate. The modification of the Group IVB metal oxide
with
the oxyanion of the Group VIB metal imparts acid functionality to the
material.
The combination of Group IVB metal oxide with an oxyanion of a Group VIB
metal is believed to enter into an actual chemical interaction which, in any
event,
provides a composition with more acidity than a simple mixture of separately
formed Group IVB metal oxide mixed with a separately formed Group VIB
metal oxide or oxyanion.
[060] The acidic solid materials useful as a catalyst are described in U.S.
Pat.
Nos. 5,510,539 and 5,563,310. These solid materials comprise an-oxide of a
Group IVB metal, preferably zirconia or titania. The Group IVB metal oxide is
modified with an oxyanion of a Group VIB metal, such as an oxyanion of
tungsten, such as tungstate. The modification of the Group IVB metal oxide
with
the oxyanion of the Group VIB metal imparts acid functionality to the
material.
The modification of a Group IVB metal oxide, particularly, zirconia, with a
Group VIB metal oxyanion, particularly tungstate, is described in U.S. Pat.
No.
5,113,034; in Japanese Kokai Patent Application No. Hei 1[1989]-288339; and
in an article by K. Arata and M. Hino in Proceeding 9th International Congress
on Catalysis, Volume 4, pages 1727-1735 (1988). According to these
publications, tungstate is impregnated onto a preformed solid zirconia
material.
This chemical interaction is discussed in the aforementioned article by K.
Arata
and M. Hino which also suggests that solid superacids are formed when sulfates
are reacted with hydroxides or oxides of certain metals, e.g., Zr. These
superacids are said to have the structure of a bidentate sulfate ion
coordinated to
the metal, e.g., Zr. The article suggests further that a superacid can also be
formed when tungstates are reacted with hydroxides or oxides of Zr. The
resulting tungstate modified zirconia materials are theorized to have an
analogous structure to the aforementioned superacids, comprising sulfate and
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zirconium, wherein tungsten atoms replace sulfur atoms in the bidentate
structure. It is further suggested that the tungsten oxide combines with
zirconium
oxide compounds to create superacid sites at the time the tetragonal phase is
formed.
[061] Although it is believed that the present catalysts may comprise the
bidentate structure suggested in the aforementioned article by Arata and Hino,
the particular structure of the catalytically active site in the present Group
IVB
metal oxide modified with an oxyanion of a Group VIB metal has not yet been
confirmed, and it is not intended that this catalyst component should be
limited
to any particular structure.
[062] Suitable sources of the Group IVB metal oxide, used for preparing the
catalyst, include compounds capable of generating such oxides, such as
oxychlorides, chlorides, nitrates, oxynitrates, etc., particularly of
zirconium or
titanium. Alkoxides of such metals may also be used as precursors or sources
of
the Group IVB metal oxides. Examples of such alkoxides include zirconium n-
propoxide and titanium i-propoxide. These sources of a Group IVB metal oxide,
particularly zirconia, may form zirconium hydroxide, i.e., Zr(OH)4, or
hydrated
zirconia as intermediate species upon precipitation from an aqueous medium in
the absence of a reactive source of tungstate. The expression, hydrated
zirconia,
is intended to connote materials comprising zirconium atoms covalently linked
to other zirconium atoms via bridging oxygen atoms, i. e., Zr-O-Zr, further
comprising available surface hydroxy groups. When hydrated zirconia is
impregnated with a suitable source of tungstate under sufficient conditions,
these
available surface hydroxyl groups are believed to react with the source of
tungstate to form an acidic catalyst. As suggested in the article by K. Arata
and
M. Hino, precalcination of Zr(OH)4 at a temperature of from about 100 C to
about 400 C results in a species which interacts more favorably with tungstate
upon impregnation therewith. This precalcination is believed to result in the
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condensation of ZrOH groups to form a polymeric zirconia species with surface
hydroxyl groups which may be referred to as a form of a hydrated zirconia.
[063] Suitable sources for the oxyanion of the Group VIB metal, preferably
molybdenum or tungsten, include, but are not limited to, ammonium
metatungstate or metamolybdate, tungsten or molybdenum chloride, tungsten or
molybdenum carbonyl, tungstic or molybdic acid and sodium tungstate or
molybdate.
[064] The ratio of aromatic compound to a-olefin oligomers preferably is
from about 0.05:1 to about 20:1. In more preferred embodiments the ratio of
aromatic compound to a-olefin oligomers is from about 0.1:1 to about 8:1.
[065] The methods provide arylated poly a-olefins in higher yield than the
conventional alkylbenzene fluid synthesis, where 2 moles of a-olefin and one
mole of aromatic compound are mixed together with a catalyst.
[066] Reaction temperatures typically range from about 20 to 100 C.
[067] The alkylbenzene fluids used in this invention have good low
temperature properties, including good pour points. Their pour points are
usually 0 C or less. A preferred alkyl methyl benzene fluid and the one used
in
all experiments was prepared according to procedures described in USP
6,071,864, starting from the oligomerization of a mixture of C8, CIo and C12
linear alpha olefins, over a promoted BF3 catalyst to produce a product which
is
reacted with toluene over the same catalyst at same reaction temperature. The
product was isolated to yield a lube base stock with viscometrics and pour
point
meeting the requirement for this invention (> 1.5 cS and less than 0 C pour
point). It has been discovered that this alkylbenzene unexpectedly reduces the
pour point of GTL fluids synergistically.
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[068] A dialkylbenzene (DAB) as described in US6491809 can also be used
with GTL lube to give similar benefit. These types of DAB can be prepared by
repeated alkylation of benzene e.g., alkylation of benzene to give mono-
alkylbenzene, followed by further alkylation of this mono-alkylbenzene in the
same reactor or in a separate reactor. Alkylbenzenes meeting the requirement
for this invention can also be obtained from many detergent alkylbenzene
processes. In these processes, linear alkylbenzene (LAB) is produced by
alkylation of benzene over alkylation catalyst. The mono-alkyl LAB is used as
raw material for detergent production. This detergent LAB process also
produces some heavier by-product streams, which contain mixtures of di-
alkylbenzene and high alkylbenzenes or oligomerized alkylated benzene. These
higher fractions often have properties meeting the description of this
invention
and are suitable to blend with GTL base stocks .
[069] In contrast, the conventional C20-C24 alkylbenzene fluids, prepared by
isomerizing C20-C24 linear alpha-olefins resulting in the rearrangement of the
double bond from the alpha to an internal position and then alkylating benzene
with such C20-C24 linear olefins (USP 6,627,779), have pour points above 0 C.
These types of fluids have no effect on GTL pour point or in fact raise the
pour
point.
[070] Further, it has been found that the hydrogenated analogues of the
alkylated naphthalene or alkylated benzene described above are also effective
pour point depressant fluids for GTL base stocks, and hydrodewaxed or
hydroisomerized/catalytic (and/or solvent) dewaxed wax derived base
stocks/base oils. Further, it has been found that the alkylated naphthalene or
alkylated benzene fluids can provide un-expected improvement of oxidation
stability of the blends with GTL fluids. This oxidative stability improvement
can be demonstrated by longer RBOT (ASTM D2272 method) or other
oxidation test methods. Further, it has been found that the alkylated
naphthalene
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or alkylated benzene fluids can improve the polarity of the blends with GTL
fluids. This higher polarity of the blend indicates a better solubility of
additives
and other polar components formed during oil service. Thus, the blend of GTL
with these alkylated aromatic fluids can provide higher level of finished
lubricant performance.
[071] The base stocks and/or base oils employed in the present invention
include one or more of a mixture of base stock(s) and/or base oil(s) derived
from
one or more Gas-to-Liquids (GTL) materials, as well as hydrodewaxed, or
hydroisomerized/conventional cat (and/or solvent) dewaxed base stock(s) and/or
base oils derived from natural wax or waxy feeds, mineral and or non-mineral
oil
waxy feed stocks such as slack waxes (derived from the solvent dewaxing of
natural oils, mineral oils or synthetic, e.g. Fischer-Tropsch feed stocks),
natural
waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms,
waxy raffinate, hydrocrackate, thermal crackates, foots oil or other mineral,
mineral oil, or even non-petroleum oil derived waxy materials such as waxy
materials received from coal liquefaction or shale oil, linear or branched
hydrocarbyl compounds with carbon numbers of about 20 or greater, preferably
about 30 or greater, and mixtures of such base stocks and/or base oils.
[072] Base stock(s) and/or base oil(s) derived from waxy feeds, which are also
suitable for use in this invention, are paraffinic fluids of lubricating
viscosity
derived from hydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed
waxy feedstocks of mineral oil, non-mineral oil, non-petroleum, or natural
source origin, e.g., feedstocks such as one or more of gas oils, slack wax,
waxy
fuels hydrocracker bottoms, hydrocarbon raffinates, natural waxes,
hyrocrackates, thermal crackates, foots oil, wax from coal liquefaction or
from
shale oil, or other suitable mineral oil, non-mineral oil, non-petroleum, or
natural
source derived waxy materials, linear or branched hydrocarbyl compounds with
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carbon number of about 20 or greater, preferably about 30 or greater, and
mixtures of such isomerate/isodewaxate base stock(s) and/or base oil(s).
[073] GTL materials are materials that are derived via one or more synthesis,
combination, transformation, rearrangement, and/or degradation/deconstructive
processes from gaseous carbon-containing compounds, hydrogen-containing
compounds and/or elements as feedstocks such as hydrogen, carbon dioxide,
carbon monoxide, water, methane, ethane, ethylene, acetylene, propane,
propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or
base oils are GTL materials of lubricating viscosity that are generally
derived
from hydrocarbons, for example waxy synthesized hydrocarbons, that are
themselves derived from simpler gaseous carbon-containing compounds,,
hydrogen-containing compounds and/or elements as feedstocks. GTL base
stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range
(1)
separated/fractionated from synthesized GTL materials such as for example, by
distillation and subsequently subjected to a final wax processing step which
involves either or both of a catalytic dewaxing process, or a solvent dewaxing
process, to produce lube oils of reduced/low pour point; (2) synthesized wax
isomerates, comprising, for example, hydrodewaxed, or
hydroisomerized/followed by cat and/or solvent dewaxed synthesized wax or
waxy hydrocarbons; (3) hydrodewaxed, or hydroisomerized/followed by cat
and/or solvent dewaxed Fischer-Tropsch (F-T) material (i.e., hydrocarbons,
waxy hydrocarbons, waxes and possible analogous oxygenates); preferably
hydrodewaxed, or hydroisomerized/followed by cat and/or solvent dewaxing
dewaxed F-T waxy hydrocarbons, or hydrodewaxed or
hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T waxes, or
mixtures thereof.
[074] GTL base stock(s) and/or base oil(s) derived from GTL materials,
especially, hydrodewaxed, or hydroisomerized/followed by cat and/or solvent
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dewaxed wax or waxy feed preferably F-T material derived base stock(s) and/or
base oil(s), are characterized typically as having kinematic viscosities at
100 C
of from about 2 mm2/s to about 50 mm2/s, preferably from about 3 mm2/s to
about 50mm2/s, more preferably from about 3.5 mm2/s to about 30 mm2/s
(ASTM D445). They are further characterized typically as having pour points of
about -5 C to about -40 C or lower. (ASTM D97) They are also characterized
typically as having viscosity indices of about 80 to 140 or greater (ASTM
D2270).
[075] In addition, the GTL base stock(s) and/or base oil(s) are typically
highly paraffinic (>90% saturates), and may contain mixtures of
monocycloparaffins and multicycloparaffins in combination with non-cyclic
isoparaffins. The ratio of the naphthenic (i.e., cycloparaffin) content in
such
combinations varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) and hydrodewaxed, or hydroisomerized/cat (and/or
solvent) dewaxed base stock(s) and/or base oil(s) typically have very low
sulfur
and nitrogen content, generally containing less than about 10 ppm, and more
typically less than about 5 ppm of each of these elements. The sulfur and
nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T
material, especially F-T wax, is essentially nil. In addition, the absence of
phosphorous and aromatics make this material especially suitable for the
formulation of low sulfur, sulfated ash, and phosphorus (low SAP) products.
[076] Base stock(s) and/or base oil(s) derived from waxy feeds, which are also
suitable for use in this invention, are paraffinic fluids of lubricating
viscosity
derived from hydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed
waxy feedstocks of mineral oil, non-mineral oil, non-petroleum, or natural
source origin, e.g., feedstocks such as one or more of gas oils, slack wax,
waxy
fuels hydrocracker bottoms, hydrocarbon raffinates, natural waxes,
hyrocrackates, thermal crackates, foots oil, wax from coal liquefaction or
from
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shale oil, or other suitable mineral oil, non-mineral oil, non-petroleum, or
natural
source derived waxy materials, linear or branched hydrocarbyl compounds with
carbon number of about 20 or greater, preferably about 30 or greater, and
mixtures of such isomerate/isodewaxate base stock(s) and/or base oil(s).
[077] Slack wax is the wax recovered from any waxy hydrocarbon oil
including synthetic oil such as F-T waxy oil or petroleum oils by solvent or
autorefrigerative dewaxing. Solvent dewaxing employs chilled solvent such as
methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), mixtures of
MEK/MIBK, mixtures of MEK and toluene, while autorefrigerative dewaxing
employs pressurized, liquefied low boiling hydrocarbons such as propane or
butane.
[078] Slack wax(es) secured from synthetic waxy oils such as F-T waxy oil
will usually have zero or nil sulfur and/or nitrogen containing compound
content. Slack wax(es) secured from petroleum oils, may contain sulfur and
nitrogen containing compounds. Such heteroatom compounds must be removed
by hydrotreating (and not hydrocracking), as for example by hydrodesulfuri-
zation (HDS) and hydrodenitrogenation (HDN) so as to avoid subsequent
poisoning/deactivation of the hydroisomerization catalyst.
[079] The term GTL base stock and/or base oil and/or wax isomerate base
stock and/or base oil is to be understood as embracing individual fractions of
such materials of wide viscosity range as recovered in the production process,
mixtures of two or more of such fractions, as well as mixtures of one or two
or
more low viscosity fractions with one, two or more higher viscosity fractions
to
produce a blend wherein the blend exhibits a target kinematic viscosity.
[080] In the present invention mixtures of hydrodewaxate, or
hydroisomerate/cat (or solvent) dewaxate base stock(s) and/or base oil(s),
mixtures of the GTL base stock(s) and/or base oil(s), or mixtures thereof,
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preferably mixtures of GTL base stock(s) and/or base oil(s), can constitute
all or
part of the base oil.
[081] In a preferred embodiment, the GTL material, from which the GTL
base stock(s) and/or base oil(s) is/are derived is an F-T material (i.e.,
hydrocarbons, waxy hydrocarbons, wax).
[082] The types and quantities of performance additives used in combination
with the instant invention in lubricant compositions are not limited by the
examples shown herein as illustrations.
Antiwear and EP Additives
[083] Internal combustion engine lubricating oils require the presence of
antiwear and/or extreme pressure (EP) additives in order to provide adequate
antiwear protection for the engine. Increasingly specifications for engine oil
performance have exhibited a trend for improved antiwear properties of the
oil.
Antiwear and extreme EP additives perform this role by reducing friction and
wear of metal parts.
[084] While there are many different types of antiwear additives, for several
decades the principal antiwear additive for internal combustion engine
crankcase
oils is a metal alkylthiophosphate and more particularly a metal dialkyldithio-
phosphate in which the primary metal constituent is zinc, or zinc
dialkyldithio-
phosphate (ZDDP). ZDDP compounds generally are of the formula
Zn[SP(S)(ORl)(OR2)]2 where R' and R2 are CI-C18 alkyl groups, preferably
C2-C12 alkyl groups. These alkyl groups may be straight chain or branched. The
ZDDP is typically used in amounts of from about 0.4 to 1.4 wt% of the total
lube
oil composition, although more or less can often be used advantageously.
[085] However, it is found that the phosphorus from these additives has a
deleterious effect on the catalyst in catalytic converters and also on oxygen
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sensors in automobiles. One way to minimize this effect is to replace some or
all
of the ZDDP with phosphorus-free antiwear additives.
[086] A variety of non-phosphorous additives are also used as antiwear
additives. Sulfurized olefins are useful as antiwear and EP additives. Sulfur-
containing olefins can be prepared by sulfurization or various organic
materials
including aliphatic, arylaliphatic or alicyclic olefinic hydrocarbons
containing
from about 3 to 30 carbon atoms, preferably 3-20 carbon atoms. The olefinic
compounds contain at least one non-aromatic double bond. Such compounds are
defined by the formula
R3R4C=CRSR6
where each of R3-R6 are independently hydrogen or a hydrocarbon radical.
Preferred hydrocarbon radicals are alkyl or alkenyl radicals. Any two of R3-R6
may be connected so as to form a cyclic ring. Additional information concern-
ing sulfurized olefins and their preparation can be found in USP 4,941,984.
[087] The use of polysulfides of thiophosphorus acids and thiophosphorus
acid esters as lubricant additives is disclosed in U.S. Patents 2,443,264;
2,471,115; 2,526,497; and 2,591,577. Addition of phosphorothionyl disulfides
as an antiwear, antioxidant, and EP additive is disclosed in USP 3,770,854.
Use
of alkylthiocarbamoyl compounds (bis(dibutyl)thiocarbamoyl, for example) in
combination with a molybdenum compound (oxymolybdenum diisopropyl-
phosphorodithioate sulfide, for example) and a phosphorous ester (dibutyl
hydrogen phosphite, for example) as antiwear additives in lubricants is
disclosed
in USP 4,501,678. USP 4,758,362 discloses use of a carbamate additive to
provide improved antiwear and extreme pressure properties. The use of
thiocarbamate as an antiwear additive is disclosed in USP 5,693,598.
Thiocarbamate/molybdenum complexes such as moly-sulfur alkyl dithio-
carbamate trimer complex (R=Cg-CIg alkyl) are also useful antiwear agents. The
use or addition of such materials should be kept to a minimum if the object is
to
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produce low SAP formulations. Each of the aforementioned patents is
incorporated by reference herein in its entirety.
[088] Esters of glycerol may be used as antiwear agents. For example, mono-,
di-, and tri-oleates, mono-palmitates and mono=myristates may be used.
[089] ZDDP is combined with other compositions that provide antiwear
properties. USP 5,034,141 discloses that a combination of a thiodixanthogen
compound (octylthiodixanthogen, for example) and a metal thiophosphate
(ZDDP, for example) can improve antiwear properties. USP 5,034,142 discloses
that use of a metal alkyoxyalkylxanthate (nickel ethoxyethylxanthate, for
example) and a dixanthogen (diethoxyethyl dixanthogen, for example) in
combination with ZDDP improves antiwear properties. Each of the afore-
mentioned patents is incorporated herein by reference in its entirety.
[090] Preferred antiwear additives include phosphorus and sulfur compounds
such as zinc dithiophosphates and/or sulfur, nitrogen, boron, molybdenum
phosphorodithioates, molybdenum dithiocarbamates and various organo-
molybdenum derivatives including heterocyclics, for example dimercaptothia-
diazoles,
mercaptobenzothiadiazoles, triazines, and the like, alicyclics, amines,
alcohols, esters, diols, triols, fatty amides and the like can also be used.
Such
additives may be used in an amount of about 0.01 to 6 wt%, preferably about
0.01 to 4 wt%. ZDDP-like compounds provide limited hydroperoxide
decomposition capability, significantly below that exhibited by compounds
disclosed and claimed in this patent and can therefore be eliminated from the
formulation or, if retained, kept at a minimal concentration to facilitate
production of low SAP formulations.
Antioxidants
[091] Antioxidants retard the oxidative degradation of base oils during
service. Such degradation may result in deposits on metal surfaces, the
presence
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of sludge, or a viscosity increase in the lubricant. One skilled in the art
knows a
wide variety of oxidation inhibitors that are useful in lubricating oil
composi-
tions. See, Klamann in Lubricants and Related Products, op cite, and U.S.
Patents 4,798,684 and 5,084,197, for example, each of which is incorporated by
reference herein in its entirety.
[092] Useful antioxidants include hindered phenols. These phenolic anti-
oxidants may be ashless (metal-free) phenolic compounds or neutral or basic
metal salts of certain phenolic compounds. Typical phenolic antioxidant
compounds are the hindered phenolics which are the ones which contain a
sterically hindered hydroxyl group, and these include those derivatives of
dihydroxy aryl compounds in which the hydroxyl groups are in the o- or
p-position to each other. Typical phenolic antioxidants include the hindered
phenols substituted with C6+ alkyl groups and the alkylene coupled derivatives
of these hindered phenols. Examples of phenolic materials of this type 2-t-
butyl-
4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-
t-
butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-
heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered
mono-phenolic antioxidants may include for example hindered 2,6-di-alkyl-
phenolic proprionic ester derivatives. Bis-phenolic antioxidants may also be
advantageously used in combination with the instant invention. Examples of
ortho-coupled phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol); 2,2'-bis(4-
octyl-6-t-butyl-phenol); and 2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-
coupled
bisphenols include for example 4,4'-bis(2,6-di-t-butyl phenol) and 4,4'-
methylene-bis(2,6-di-t-butyl phenol).
[093] Non-phenolic oxidation inhibitors which may be used include aromatic
amine antioxidants and these may be used either as such or in combination with
phenolics. Typical examples of non-phenolic antioxidants include: alkylated
and non-alkylated aromatic amines such as aromatic monoamines of the formula
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RgR9R10N where R 8 is an aliphatic, aromatic or substituted aromatic group, R9
is
an aromatic or a substituted aromatic group, and R10 is H, alkyl, aryl or
R"S(O)xR'Z where R" is an alkylene, alkenylene, or aralkylene group, R12 is a
higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2.
The
aliphatic group R8 may contain from 1 to about 20 carbon atoms, and preferably
contains from about 6 to 12 carbon atoms. The aliphatic group is a saturated
aliphatic group. Preferably, both R8 and R9 are aromatic or substituted
aromatic
groups, and the aromatic group may be a fused ring aromatic group such as
naphthyl. Aromatic groups R8 and R9 may be joined together with other groups
such as S.
[094] Typical aromatic amines antioxidants have alkyl substituent groups of at
least about 6 carbon atoms. Examples of aliphatic groups include hexyl,
heptyl,
octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more
than about 14 carbon atoms. The general types of amine antioxidants useful in
the present compositions include diphenylamines, phenyl naphthylamines,
phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of
two or more aromatic amines are also useful. Polymeric amine antioxidants can
also be used. Particular examples of aromatic amine antioxidants useful in the
present invention include: p,p'-dioctyldiphenylamine; t-octylphenyl-alpha-
naphthylamine; phenyl-alphanaphthylamine; and p-octylphenyl-alpha-
naphthylamine.
[095] Sulfurized alkyl phenols and alkali or alkaline earth metal salts
thereof
also are useful antioxidants.
[096] Another class of antioxidant used in lubricating oil compositions is oil-
soluble copper compounds. Any oil-soluble suitable copper compound may be
blended into the lubricating oil. Examples of suitable copper antioxidants
include copper dihydrocarbyl thio- or dithio-phosphates and copper salts of
carboxylic acid (naturally occurring or synthetic). Other suitable copper
salts
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include copper dithiacarbamates, sulphonates, phenates, and acetylacetonates.
Basic, neutral, or acidic copper Cu(I) and or Cu(II) salts derived from
alkenyl
succinic acids or anhydrides are know to be particularly useful.
[097] Preferred antioxidants include hindered phenols, arylamines. These
antioxidants may be used individually by type or in combination with one
another. Such additives may be used in an amount of about 0.01 to 5 wt%,
preferably about 0.01 to 1.5 wt%, more preferably zero to less than 1.5 wt%,
most preferably zero.
Detergents
[098] Detergents are commonly used in lubricating compositions. A typical
detergent is an anionic material that contains a long chain hydrophobic
portion -
of the molecule and a smaller anionic or oleophobic hydrophilic portion of the
molecule. The anionic portion of the detergent is typically derived from an
organic acid such as a sulfur acid, carboxylic acid, phosphorous acid, phenol,
or
mixtures thereof. The counterion is typically an alkaline earth or alkali
metal.
[099] Salts that contain a substantially stochiometric amount of the metal are
described as neutral salts and have a total base number (TBN, as measured by
ASTM D2896) of from 0 to 80. Many compositions are overbased, containing
large amounts of a metal base that is achieved by reacting an excess of a
metal
compound (a metal hydroxide or oxide, for example) with an acidic gas (such as
carbon dioxide). Useful detergents can be neutral, mildly overbased, or highly
overbased.
[0100] It is desirable for at least some detergent to be overbased. Overbased
detergents help neutralize acidic impurities produced by the combustion
process
and become entrapped in the oil. Typically, the overbased material has a ratio
of
metallic ion to anionic portion of the detergent of about 1.05:1 to 50:1 on an
equivalent basis. More preferably, the ratio is from about 4:1 to about 25:1.
The
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resulting detergent is an overbased detergent that will typically have a TBN
of
about 150 or higher, often about 250 to 450 or more. Preferably, the
overbasing
cation is sodium, calcium, or magnesium. A mixture of detergents of differing
TBN can be used in the present invention.
[0101] Preferred detergents include the alkali or alkaline earth metal salts
of
sulfonates, phenates, carboxylates, phosphates, and salicylates.
[0102] Sulfonates may be prepared from sulfonic acids that are typically
obtained by sulfonation of alkyl substituted aromatic hydrocarbons. Hydro-
carbon examples include those obtained by alkylating benzene, toluene, xylene,
naphthalene, biphenyl and their halogenated derivatives (chlorobenzene,
chlorotoluene, and chloronaphthalene, for example). The alkylating agents
typically have about 3 to 70 carbon atoms. The alkaryl sulfonates typically
contain about 9 to about 80 carbon or more carbon atoms, more typically from
about 16 to 60 carbon atoms.
[0103] Klamann in Lubricants and Related Products, op cit discloses a number
of overbased metal salts of various sulfonic acids which are useful as
detergents
and dispersants in lubricants. The book entitled "Lubricant Additives", C. V.
Smallheer and R. K. Smith, published by the Lezius-Hiles Co. of Cleveland,
Ohio (1967), similarly discloses a number of overbased sulfonates that are
useful
as dispersants/detergents.
[0104] Alkaline earth phenates are another useful class of detergent. These
detergents can be made by reacting alkaline earth metal hydroxide or oxide
(CaO, Ca(OH)2, BaO, Ba(OH)2, MgO, Mg(OH)2, for example) with an alkyl
phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain
or
branched C1-C30 alkyl groups, preferably, C4-C20. Examples of suitable phenols
include isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol, and
the like. It should be noted that starting alkylphenols may contain more than
one
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alkyl substituent that are each independently straight chain or branched. When
a
non-sulfurized alkylphenol is used, the sulfurized product may be obtained by
methods well known in the art. These methods include heating a mixture of
alkylphenol and sulfurizing agent (including elemental sulfur, sulfur halides
such
as sulfur dichloride, and the like) and then reacting the sulfurized phenol
with an
alkaline earth metal base.
[0105] Metal salts of carboxylic acids are also useful as detergents. These
carboxylic acid detergents may be prepared by reacting a basic metal compound
with at least one carboxylic acid and removing free water from the reaction
product. These compounds may be overbased to produce the desired TBN level.
Detergents made from salicylic acid are one preferred class of detergents
derived
from carboxylic acids. Useful salicylates include long chain alkyl
salicylates.
One useful family of compositions is of the formula
0
LO-M
n(R) I
Ll~"OH 2
where R is a hydrogen atom or an alkyl group having 1 to about 30 carbon
atoms, n is an integer from 1 to 4, and M is an alkaline earth metal.
Preferred R
groups are alkyl chains of at least C11, preferably C13 or greater. R may be
optionally substituted with substituents that do not interfere with the
detergent's
function. M is preferably, calcium, magnesium, or barium. More preferably, M
is calcium.
[0106] Hydrocarbyl-substituted salicylic acids may be prepared from phenols
by the Kolbe reaction. See USP 3,595,791 for additional information on
synthesis of these compounds. The metal salts of the hydrocarbyl-substituted
salicylic acids may be prepared by double decomposition of a metal salt in a
polar solvent such as water or alcohol.
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[0107] Alkaline earth metal phosphates are also used as detergents.
[0108] Detergents may be simple detergents or what is known as hybrid or
complex detergents. The latter detergents can provide the properties of two
detergents without the need to blend separate materials. See USP 6,034,039 for
example.
[0109] Preferred detergents include calcium phenates, calcium sulfonates,
calcium salicylates, magnesium phenates, magnesium sulfonates, magnesium
salicylates and other related components (including borated detergents).
Typically, the total detergent concentration is about 0.01 to about 6.0 wt%,
preferably, about 0.1 to 0.4 wt%.
Dispersant
[0110] During engine operation, oil-insoluble oxidation byproducts are
produced. Dispersants help keep these byproducts in solution, thus diminishing
their deposition on metal surfaces. Dispersants may be ashless or ash-forming
in
nature. Preferably, the dispersant is ashless. So called ashless dispersants
are
organic materials that form substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are considered ashless.
In contrast, metal-containing detergents discussed above form ash upon
combustion.
[0111] Suitable dispersants typically contain a polar group attached to a
relatively high molecular weight hydrocarbon chain. The polar group typically
contains at least one element of nitrogen, oxygen, or phosphorus. Typical
hydrocarbon chains contain 50 to 400 carbon atoms.
[0112] Chemically, many dispersants may be characterized as phenates,
sulfonates, sulfurized phenates, salicylates, naphthenates, stearates,
carbamates,
thiocarbamates, phosphorus derivatives. A particularly useful class of
dispersants are the alkenylsuccinic derivatives, typically produced by the
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reaction of a long chain substituted alkenyl succinic compound, usually a
substituted succinic anhydride, with a polyhydroxy or polyamino compound.
The long chain group constituting the oleophilic portion of the molecule which
confers solubility in the oil, is normally a polyisobutylene group. Many
examples of this type of dispersant are well known commercially and in the
literature. Exemplary U.S. patents describing such dispersants are 3,172,892;
3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012;
3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are
described in U.S. Patents 3,036,003; 3,200,107; 3,254,025; 3,275,554;
3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480;
3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730; 3,687,849;
3,702,300; 4,100,082; 5,705,458. A further description of dispersants may be
found, for example, in European Patent Application No. 471 071, to which
reference is made for this purpose.
[0113] Hydrocarbyl-substituted succinic acid compounds are popular
dispersants. In particular, succinimide, succinate esters, or succinate ester
amides prepared by the reaction of a hydrocarbon-substituted succinic acid
compound preferably having at least 50 carbon atoms in the hydrocarbon
substituent, with at least one equivalent of an alkylene amine are
particularly
useful.
101141 Succinimides are formed by the condensation reaction between alkenyl
succinic anhydrides and amines. Molar ratios can vary depending on the poly-
amine. For example, the molar ratio of alkenyl succinic anhydride to TEPA can
vary from about 1:1 to about 5:1. Representative examples are shown in U.S.
Patents 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616,
3,948,800; and Canada Pat. No. 1,094,044.
[0115] Succinate esters are formed by the condensation reaction between
alkenyl succinic anhydrides and alcohols or polyols. Molar ratios can vary
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depending on the alcohol or polyol used. For example, the condensation product
of an alkenyl succinic anhydride and pentaerythritol is a useful dispersant.
[0116] Succinate ester amides are formed by condensation reaction between
alkenyl succinic anhydrides and alkanol amines. For example, suitable alkanol
amines include ethoxylated polyalkylpolyamines, propoxylated polyalkylpoly-
amines and polyalkenylpolyamines such as polyethylene polyamines. One
example is propoxylated hexamethylenediamine. Representative examples are
shown in USP 4,426,305.
[0117] The molecular weight of the alkenyl succinic anhydrides used in the
preceding paragraphs will typically range between 800 and 2,500. The above
products can be post-reacted with various reagents such as sulfur, oxygen,
formaldehyde, carboxylic acids such as oleic acid, and boron compounds such as
borate esters or highly borated dispersants. The dispersants can be borated
with
from about 0.1 to about 5 moles of boron per mole of dispersant reaction
product.
[0118] Mannich base dispersants are made from the reaction of alkylphenols,.-
.r
formaldehyde, and amines. See USP 4,767,551, which is incorporated herein by
reference. Process aids and catalysts, such as oleic acid and sulfonic acids,
can
also be part of the reaction mixture. Molecular weights of the alkylphenols
range from 800 to 2,500. Representative examples are shown in U.S. Patents
3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and
3,803,039.
[0119] Typical high molecular weight aliphatic acid modified Mannich
condensation products useful in this invention can be prepared from high
molecular weight alkyl-substituted hydroxyaromatics or HN(R)2 group-
containing reactants.
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[0120] Examples of high molecular weight alkyl-substituted hydroxyaromatic
compounds are polypropylphenol, polybutylphenol, and other polyalkylphenols.
These polyalkylphenols can be obtained by the alkylation, in the presence of
an
alkylating catalyst, such as BF3, of phenol with high molecular weight poly-
propylene, polybutylene, and other polyalkylene compounds to give alkyl
substituents on the benzene ring of phenol having an average 600-100,000
molecular weight.
[0121] Examples of HN(R)2 group-containing reactants are alkylene poly-
amines, principally polyethylene polyamines. Other representative organic
compounds containing at least one HN(R)2 group suitable for use in the prepara-
tion of Mannich condensation products are well known and include the mono-
and di-amino alkanes and their substituted analogs, e.g., ethylamine and
diethanol amine; aromatic diamines, e.g., phenylene diamine, diamino
naphthalenes; heterocyclic amines, e.g., morpholine, pyrrole, pyrrolidine,
imidazole, imidazolidine, and piperidine; melamine and their substituted
analogs.
[0122] Examples of alkylene polyamide reactants include ethylenediamine,
diethylene triamine, triethylene tetraamine, tetraethylene pentaamine, penta-
ethylene hexamine, hexaethylene heptaamine, heptaethylene octaamine,
octaethylene nonaamine, nonaethylene decamine, and decaethylene undecamine
and mixture of such amines having nitrogen contents corresponding to the
alkylene polyamines, in the formula H2N-(Z-NH-)nH, mentioned before, Z is a
divalent ethylene and n is 1 to 10 of the foregoing formula. Corresponding
propylene polyamines such as propylene diamine and di-, tri-, tetra-, penta-
propylene tri-, tetra-, penta- and hexaamines are also suitable reactants. The
alkylene polyamines are usually obtained by the reaction of ammonia and dihalo
alkanes, such as dichloro alkanes. Thus the alkylene polyamines obtained from
the reaction of 2 to 11 moles of ammonia with 1 to 10 moles of dichloroalkanes
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having 2 to 6 carbon atoms and the chlorines on different carbons are suitable
alkylene polyamine reactants.
[0123] Aldehyde reactants useful in the preparation of the high molecular
products useful in this invention include the aliphatic aldehydes such as
formaldehyde (also as paraformaldehyde and formalin), acetaldehyde and aldol
((3-hydroxybutyraldehyde). Formaldehyde or a formaldehyde-yielding reactant
is preferred.
[0124] Hydrocarbyl substituted amine ashless dispersant additives are well
known to one skilled in the art; see, for example, USP Nos. 3,275,554;
3,438,757; 3,565,804; 3,755,433; 3,822,209 and 5,084,197.
[0125] Preferred dispersants include borated and non-borated succinimides,
including those derivatives from mono-succinimides, bis-succinimides, and/or
mixtures of mono- and bis-succinimides, wherein the hydrocarbyl succinimide is
derived from a hydrocarbylene group such as polyisobutylene having a Mn of
from about 500 to about 5000 or a mixture of such hydrocarbylene groups.
Other preferred dispersants include succinic acid-esters and amides,
alkylphenol-
polyamine-coupled Mannich adducts, their capped derivatives, and other related
components. Such additives may be used in an amount of about 0.1 to 20 wt%,
preferably about 0.1 to 8 wt%.
Supplemental Pour Point Depressants
[0126] Conventional pour point depressants (also known as lube oil flow
improvers) may be added to the compositions of the present invention if
desired.
These pour point depressant may be added to lubricating compositions of the
present invention to lower the minimum temperature at which the fluid will
flow
or can be poured. Examples of suitable pour point depressants include poly-
methacrylates, polyacrylates, polyarylamides, condensation products of
haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, and
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terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl
ethers.
USP Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746;
2,721,877; 2.721,878; and 3,250,715 describe useful pour point depressants
and/or the preparation thereof. Such additives may be used in an amount of
about 0.00 to 5 wt%, preferably about 0.01 to 1.5 wt%.
Corrosion Inhibitors
[0127] Corrosion inhibitors are used to reduce the degradation of metallic
parts that are in contact with the lubricating oil composition. Suitable
corrosion
inhibitors include thiadiazoles. See, for example, USP Nos. 2,719,125;
2,719,126; and 3,087,932. Such additives may be used in an amount of about
0.01 to 5 wt%, preferably about 0.01 to 1.5 wt%.
Seal Compatibility Additives
[0128] Seal compatibility agents help to swell elastomeric seals by causing a
chemical reaction in the fluid or physical change in the elastomer. Suitable
seal
compatibility agents for lubricating oils include organic phosphates, aromatic
esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example),
and
polybutenyl succinic anhydride. Such additives may be used in an amount of
about 0.01 to 3 wt%, preferably about 0.01 to 2 wt%.
Anti-Foam Agents
[0129] Anti-foam agents may advantageously be added to lubricant composi-
tions. These agents retard the formation of stable foams. Silicones and
organic
polymers are typical anti-foam agents. For example, polysiloxanes, such as
silicon oil or polydimethyl siloxane, provide antifoam properties. Anti-foam
agents are commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually the amount of
these additives combined is less than 1 percent and often less than 0.1
percent.
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Inhibitors and Antirust Additives
[0130] Antirust additives (or corrosion inhibitors) are additives that protect
lubricated metal surfaces against chemical attack by water or other
contaminants. A wide variety of these are commercially available; they are
referred to in Klamann in Lubricants and Related Products, op cit.
[0131] One type of antirust additive is a polar compound that wets the metal
surface preferentially, protecting it with a film of oil. Another type of
antirust
additive absorbs water by incorporating it in a water-in-oil emulsion so that
only
the oil touches the metal surface. Yet another type of antirust additive
chemically adheres to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates, basic
metal
sulfonates, fatty acids and amines. Such additives may be used in an amount of
about 0.01 to 5 wt%, preferably about 0.01 to 1.5 wt%.
Friction Modifiers
[0132] A friction modifier is any material or materials that can alter the
coefficient of friction of a surface lubricated by any lubricant or fluid
containing
such material(s). Friction modifiers, also known as friction reducers, or
lubricity
agents or oiliness agents, and other such agents that change the ability of
base
oils, formulated lubricant compositions, or functional fluids, to modify the
coefficient of friction of a lubricated surface may be effectively used in
combination with the base oils or lubricant compositions of the present
invention
if desired. Friction modifiers that lower the coefficient of friction are
particularly advantageous in combination with the base oils and lube composi-
tions of this invention. Friction modifiers may include metal-containing
compounds or materials as well as ashless compounds or materials, or mixtures
thereof. Metal-containing friction modifiers may include metal salts or metal-
ligand complexes where the metals may include alkali, alkaline earth, or
transition group metals. Such metal-containing friction modifiers may also
have
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low-ash characteristics. Transition metals may include Mo, Sb, Sn, Fe, Cu, Zn,
and others. Ligands may include hydrocarbyl derivative of alcohols, polyols,
glycerols, partial ester glycerols, thiols, carboxylates, carbamates,
thiocarba-
mates, dithiocarbamates, phosphates, thiophosphates, dithiophosphates, amides,
imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles, triazoles, and
other
polar molecular functional groups containing effective amounts of 0, N, S, or
P,
individually or in combination. In particular, Mo-containing compounds can be
particularly effective such as for example Mo-dithiocarbamates, Mo(DTC), Mo-
dithiophosphates, Mo(DTP), Mo-amines, Mo (Am), Mo-alcoholates, Mo-
alcohol-amides, etc. See USP 5,824,627; USP 6,232,276; USP 6,153,564;
USP 6,143,701; USP 6,110,878; USP 5,837,657; USP 6,010,987; USP
5,906,968; USP 6,734,150; USP 6,730,638; USP 6,689,725; USP 6,569,820;
WO 99/66013; WO 99/47629; WO 98/26030.
101331 Ashless friction modifiers may have also include lubricant materials
that contain effective amounts of polar groups, for example, hydroxyl-
containing
hydrocarbyl base oils, glycerides, partial glycerides, glyceride derivatives,
and
the like. Polar groups in friction modifiers may include hydrocarbyl groups
containing effective amounts of 0, N, S, or P, individually or in combination.
Other friction modifiers that may be particularly effective include, for
example,
salts (both ash-containing and ashless derivatives) of fatty acids, fatty
alcohols,
fatty amides, fatty esters, hydroxyl-containing carboxylates, and comparable
synthetic long-chain hydrocarbyl acids, alcohols, amides, esters, hydroxy
carboxylates, and the like. In some instances fatty organic acids, fatty
amines,
and sulfurized fatty acids may be used as suitable friction modifiers.
[0134] Useful concentrations of friction modifiers may range from about 0.01
wt% to 10-15 wt% or more, often with a preferred range of about 0.1 wt% to 5
wt%. Concentrations of molybdenum-containing materials are often described
in terms of Mo metal concentration. Advantageous concentrations of Mo may
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range from about 10 ppm to 3000 ppm or more, and often with a preferred range
of about 20-2000 ppm, and in some instances a more preferred range of about
30-1000 ppm. Friction modifiers of all types may be used alone or in mixtures
with the materials of this invention. Often mixtures of two or more friction
modifiers, or mixtures of friction modifier(s) with alternate surface active
material(s), are also desirable.
Cobasestocks
[0135] Cobasestocks include natural oil, synthetic oils, and other
unconventional oils and mixtures thereof and they can be used unrefined,
refined, or rerefined (the latter is also known as reclaimed or reprocessed
oil).
Unrefined oils are those obtained directly from a natural, synthetic or
unconventional source and used without further purification. These include.
for
example shale oil obtained directly from retorting operations, oils derived
from
coal, petroleum oil obtained directly from primary distillation, and ester oil
obtained directly from an esterification process. Refined oils are similar to
the
oils discussed for unrefined oils except refined oils are subjected to one or
more
purification or transformation steps to improve at least one lubricating oil
property. One skilled in the art is familiar with many purification or
transformation processes. These processes include, for example, solvent
extraction, secondary distillation, acid extraction, base extraction,
filtration,
percolation, hydrogenation, hydrorefining, and hydrofinishing. Rerefined oils
are obtained by processes analogous to refined oils, but use an oil that has
been
previously used.
[0136] Groups I, II, III, IV and V are broad categories of base oil stocks
developed and defined by the American Petroleum Institute (API Publication
1509; www.API.org) to create guidelines for lubricant base oils. Group I base
stocks generally have a viscosity index of between about 80 to 120 and contain
greater than about 0.03% sulfur and less than about 90% saturates. Group II
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base stocks generally have a viscosity index of between about 80 to 120, and
contain less than or equal to about 0.03% sulfur and greater than or equal to
about 90% saturates. Group III stock generally has a viscosity index greater
than
about 120 and contains less than or equal to about 0.03% sulfur and greater
than
about 90% saturates. Group IV includes polyalphaolefins (PAO). Group V base
stocks include base stocks not included in Groups I-IV. Table A summarizes
properties of each of these five groups.
TABLE A: Base Stock Properties
Saturates Sulfur Viscosity Index
Group I < 90% and/or > 0.03% and 80 and < 120
Group II _ 90% and 0.03% and 80 and < 120
Group III >_ 90% and 0.03% and 120
Group IV Pol al haolefins (PAO)
Group V All other base oil stocks not included in Groups I, II, III, or IV
[0137] Natural oils include animal oils, vegetable oils (castor oil and lard
oil,
for example), and mineral oils. Animal and vegetable oils possessing favorable
thermal oxidative stability can be used. Of the natural oils, mineral oils are
preferred. Mineral oils vary widely as to their crude source, for example, as
to
whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils
derived from coal or shale are also useful in the present invention. Natural
oils
vary also as to the method used for their production and purification, for
example, their distillation range and whether they are straight run or
cracked,
hydrorefined, or solvent extracted.
[0138] Synthetic oils include hydrocarbon oils as well as non hydrocarbon
oils.
Synthetic oils can be derived from processes such as chemical combination (for
example, polymerization, oligomerization, condensation, alkylation, acylation,
etc.), where materials consisting of smaller, simpler molecular species are
built
up (i.e., synthesized) into materials consisting of larger, more complex
molecular
species. Synthetic oils include hydrocarbon oils such as polymerized and
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interpolymerized olefins (polybutylenes, polypropylenes, polyisobutylene (see:
"Polybutenes" J. D. Fotheringham, Synthetic Lubricants and High-Performance
Functional Fluids" 2 d Edition, ed. L. R. Rudnick and R. L. Shubkin, published
by Marcel Dekker Inc., N.Y. 1999, p. 357-391), propylene isobutylene
copolymers, ethylene-olefin copolymers, ethylene-butene copolymer (see: WO
2003/076555A1) and ethylene-alphaolefin copolymers, for example).
Polyalphaolefin (PAO) oil base stock is a commonly used synthetic hydrocarbon
oil. By way of example, PAO's derived from C8, CIo, C12, C14 olefins or
mixtures thereof may be utilized. See U.S. Patents 4,956,122; 4,827,064; and
4,827,073.
[0139] The number average molecular weights of the PAO's, which are known
materials and generally available on a major commercial scale from suppliers -
such as ExxonMobil Chemical Company, Chevron, Ineos, and others, typically
vary from about 250 to about 3000, or higher, and PAO's may be made in
viscosities up to about 100 mm2/s (100 C), or higher. In addition, higher
viscosity PAO's are commercially available, and may be made in viscosities up
to about 3000 mm2/s (100 C), or higher. The PAO's are typically comprised of
relatively low molecular weight hydrogenated polymers or oligomers of alpha-
olefins which include, but are not limited to, about C2 to about C32
alphaolefins
with about C8 to about C16 alphaolefins, such as 1-octene, 1-decene, 1-
dodecene
and the like, being preferred. The preferred polyalphaolefins are poly-l-
octene,
poly-l-decene and poly-l-dodecene and mixtures thereof and mixed olefin-
derived polyolefins. However, the dimers of higher olefins in the range of
about
C14 to C18 may be used to provide low viscosity base stocks of acceptably low
volatility. Depending on the viscosity grade and the starting oligomer, the
PAO's may be predominantly trimers and tetramers of the starting olefins, with
minor amounts of the higher oligomers, having a viscosity range of about 1.5
to
12 mmZ/s.
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[0140] PAO fluids niay be conveniently made by the polymerization of an
alpha-olefin in the presence of a polymerization catalyst such as the Friedel-
Crafts catalysts including, for example, aluminum trichloride, boron
trifluoride
or complexes of boron trifluoride with water, alcohols such as ethanol,
propanol
or butanol, carboxylic acids or esters such as ethyl acetate or ethyl
propionate.
For example the methods disclosed by USP 4,149,178 or USP 3,3 82,291 may be
conveniently used herein. Other descriptions of PAO synthesis are found in the
following U.S. Patents 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352;
4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the
C14 to C18 olefins are described in USP 4,218,330.
[0141] Other useful synthetic lubricating base stock oils such as silicon-
based-
oil or esters of phosphorus containing acids may also be utilized. For
examples
of other synthetic lubricating base stocks are the seminal work "Synthetic
Lubricants", Gunderson and Hart, Reinhold Publ. Corp., NY 1962.
[0142] Alkylene oxide polymers and interpolymers and their derivatives
containing modified terminal hydroxyl groups obtained by, for example,
esterification or etherification are useful synthetic lubricating oils. By way
of
example, these oils may be obtained by polymerization of ethylene oxide or
propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers
(methyl-polypropylene glycol ether having an average molecular weight of
about 1000, diphenyl ether of polyethylene glycol having a molecular weight of
about 500-1000, and the diethyl ether of polypropylene glycol having a
molecular weight of about 1000 to 1500, for example) or mono- and poly-
carboxylic esters thereof (the acidic acid esters, mixed C3_8 fatty acid
esters, or
the C130xo acid diester of tetraethylene glycol, for example).
[0143] Esters comprise a useful base stock. Additive solvency and seal
compatibility characteristics may be secured by the use of esters such as the
esters of dibasic acids with monoalkanols and the polyol esters of mono-
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carboxylic acids. Esters of the former type include, for example, the esters
of
dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid,
alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic
acid,
alkenyl malonic acid, etc., with a variety of alcohols such as butyl alcohol,
hexyl
alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examples of
these
types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl
fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl
phthalate, didecyl phthalate, dieicosyl sebacate, etc.
[0144] Particularly useful synthetic esters are those full or partial esters
which
are obtained by reacting one or more polyhydric alcohols (preferably the I
hindered polyols such as the neopentyl polyols e.g. neopentyl glycol,
trimethylol
ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane,
pentaerythritol
and dipentaerythritol) with alkanoic acids containing at least about 4 carbon
atoms (preferably C5 to C30 acids such as saturated straight chain fatty acids
including caprylic acid, capric acid, lauric acid, myristic acid, palmitic
acid,
stearic acid, arachic acid, and behenic acid, or the corresponding branched
chain
fatty acids or unsaturated fatty acids such as oleic acid).
[0145] Suitable synthetic ester components include the esters of trimethylol
propane, trimethylol butane, trimethylol ethane, pentaerythritol and/or
dipenta-
erythritol with one or more monocarboxylic acids containing from about 5 to
about 10 carbon atoms.
[0146] Silicon-based oils are another class of useful synthetic lubricating
oils.
These oils include polyalkyl-, polyaryl-, polyalkoxy-, and polyaryloxy-
siloxane
oils and silicate oils. Examples of suitable silicon-based oils include
tetraethyl
silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate, tetra-(4-
methylhexyl)
silicate, tetra-(p-tert-butylphenyl) silicate, hexyl-(4-methyl-2-pentoxy)
disiloxane, poly(methyl) siloxanes, and poly-(methyl-2-methylphenyl)
siloxanes.
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[0147] Another class of synthetic lubricating oil is esters of phosphorous-
containing acids. These include, for example, tricresyl phosphate, trioctyl
phosphate, diethyl ester of decanephosphonic acid.
[0148] Another class of synthetic oils includes polymeric tetrahydrofurans,
their derivatives, and the like.
[0149] Other useful fluids of lubricating viscosity include non-conventional
or
unconventional base stocks that have been processed, preferably catalytically,
or
synthesized to provide high performance lubrication characteristics.
Typical Additive Amounts
[0150] When lubricating oil compositions contain one or more of the additives
discussed above, the additive(s) are blended into the composition in an amount
sufficient for it to perform its intended function. Typical amounts of such
additives useful in the present invention are shown in Table 1 below.
[0151] Note that many of the additives are shipped from the manufacturer and
used with a certain amount of base oil solvent in the formulation.
Accordingly,
the weight amounts in the table below, as well as other amounts mentioned in
this text, unless otherwise indicated are directed to the amount of active
ingredient (that is the non-solvent portion of the ingredient). The wt%
indicated
below are based on the total weight of the lubricating oil composition.
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TABLE 1
Typical Amounts of Various Lubricant Oil Components
Compound Approximate wt% (useful) Approximate wt% (preferred)
Detergent 0.01-6 0.01-4
Dispersant 0.1-20 0.1-8
Friction Reducer 0.01-5 0.01-1.5
Antioxidant 0.0-5 0.0-1.5
Corrosion Inhibitor 0.01-5 0.01-1.5
Anti-wear Additive 0.01-6 0.01-4
Supplemental Pour 0.0-5 0.01-1.5
Point Depressant
Anti-foam Agent 0.001-3 0.001-0.15
Co-basestock 0-90 0-50
Base Oil Balance Balance
EXAMPLES
[0152] In the Examples, the fluid properties were measured according to
standard ASTM methods:
(a) Kinematic viscosity at 40 C and 100 C in cSt (mm2/s) by ASTM 445
method. In this text, all fluid viscosities are the to their 100 C viscosities
unless specified differently.
(b) Pour point by ASTM D97 method or equivalent automated method.
(c) Aniline point by ASTM D611 method.
(d) Rotary Bomb Oxidation of Turbine Oil at 150 C by ASTM D2272 method.
(e) Oxidation test was conducted by purging oil sample with air at 325 C for
40 hours in the presence of copper, iron and lead metal. The oxidation
stability was measured by the percent of viscosity increase, change of total
acid number, sludge rating and amount of lead loss.
(f) Thermal stability test was conducted by heating a small amount of oil
sample sealed inside a metal vessel to 300 C or proper test temperature for
24 hours. The thermal stability was measured by the percent of viscosity
decrease and weight loss during to thermal cracking into volatile
component.
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[0153] The alkylated naphthalenes employed in the following examples are
described below. AN5 was prepared by reacting naphthalene with a 1-
hexadecene olefin over a USY catalyst according to method described in USP
5034563. AN12 was prepared by reacting naphthalene with 1-tetradecene using
a catalytic amount of trifluoromethane sulfonic acid. The Alkylmethylbenzene
was synthesized according to procedures described in USP 6,071,864, starting
with the oligomerization of a mixture of C8, Clo and C12 linear alpha olefins
over
a promoted BF3 catalyst to produce a product which is further reacted with
toluene (methylbenzene) over the same catalyst at the same reaction
temperature
as the olefin oligomerization. The product was isolated to yield a lube base
stock fluid with viscometrics and pour point listed in following table, along
with
the properties of a C12 alkylbenzene as produced according to Example 7.
TABLE 1
KV @ 100 C KV @ 40 C Pour
Fluid mm2/s mm2/s VI Point, C
AN5 4.76 28.16 70 -39
AN12 13.20 118.59 97 -39
Alkylmethyl 5.73 37.9 73 < -60
benzene
C12 Alkylbenzene 1.5 4.2 -- <-60
EXAMPLE 1
[0154] Various base stocks were used for blending with the alkyl naphthalene
fluids in the examples and these base stocks are presented below in
combination
with various amounts of the alkylated naphthalene fluid AN5 showing the effect
on pour point (reported in C).
TABLE 2
Wt% AN5 0 5 20 60 100
GroupI -21 -27 -29 -32 -39
Grouplll -25 -26 -28 -32 -39
GTL-6 -21 - 27 - 36 - 42 - 39
PAO-6 - 58 - 58 - 50 - 47 - 39
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[0155] As is shown, when the alkylated naphthalene (AN5) was blended with
API Group I or Group III base stock, there is no synergistic improvement of
the
pour point. While the pour point of such blends were decreased, the amount of
the decrease is never below the pour point of the AN base stock. When
combined with PAO, the AN actually degraded pour point performance. How-
ever, when AN was blended with GTL-6 (having a pour point of -21 C) the pour
point improvements associated with the blends were non-linear (see Figure 1
and
Table 3). Data in Table 3 further demonstrated that the oxidative stabilities
of
the blended oils were also synergistically improved over pure GTL-6. When 5%
AN5 was added, the RBOT was improved from 68 minutes to 102 minutes.
When 20% AN5 was added, the RBOT was improved to 132 minutes. This
further demonstrated the uniqueness of the blends.
Table 3. AN5 + GTL-6
Wt% of AN5 0 5 20 60 100
Wt% of GTL-6 100 95 80 40 0
Kv 100 C, cS 6.02 5.99 5.77 5.17 4.76
Kv 40 C, cS 29.76 29.34 28.86 27.77 28.16
VI 141 143 134 105 64
Pour Point, C -21 -27 -36 -42 -39
RBOT, minutes (D2272) 68 102 132 129 192
EXAMPLE 2
[0156] Various amounts of AN5 (described above) were combined with
GTL-14 (nominal kinematic viscosity at 100 C of 14 mm2/s). The results are
presented in Table 4 below:
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TABLE 4
Wt% of AN5 0 5 20 60 100
Wt% of GTL 14 100 95 80 40 0
Grams of AN5 0 2.5 7.125 30 0
Grams of GLT 14 0 47.5 28.5 20 0
Grams total 0 50 35.625 50 0
Kv 100 C, cS 14.3 13.64 11.72 7.73 4.76
Kv 40 C, cS 94.98 90.29 76.4 47.32 28.16
VI 155 143 137 119 64
Pour point, C - 24 - 27 - 36 - 42 - 39
[0157] As is seen the pour point of the GTL was still synergistically improved
by the addition of the alkylated naphthelene fluid.
EXAMPLE 3
[0158] Various amounts of AN12 (described above) were combined with
GTL-6. The results are presented in Table 5.
TABLE 5
Wt% of AN 12 0 20 60 100
Wt% of GTL-6 100 80 40 0
Kv 100 C, cS 6.02 6.78 8.90 13.20
Kv 40 C, cS 29.76 36.72 58.82 118.59
VI 141 133 117 97
Pour oint, C -21 - 30 - 39 - 39
RBOT, Minutes (D2272) 68 111 127 128
[0159] Again, it is seen that the addition of alkylated naphthalene, in this
instance a high viscosity AN, to a GTL (GTL-6) resulted in a blend which
exhibited a non-linear reduction in pour point. Furthermore, the oxidative
stabilities of the blends were improved synergistically. The RBOT increased
from 68 minutes to 111 minutes, when 20 wt% of AN12 was added.
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EXAMPLE 4
[0160] In this example an AN5 was fully hydrogenated in the presence of 800
psi H2 pressure with a 2 wt% nickel on Kieselguhr catalyst for 16 hours to
yield
a hydrogenated AN5 fluid (an alkyl cycloparaffin fluid). This fluid was
blended
in varying amounts with GTL-6 and the results are reported in Table 6.
TABLE 6
Wt% (fully hydrogenated 0 5 20 60 100
AN) (HAN)
Wt% of GTL 100 95 80 40 0
Kv 100 C, cS 6.02 6.03 5.91 5.56 5.25
Kv 40 C, cS 29.76 29.86 29.65 29.74 30.57
VI 141 141 136 115 89
Pour oint, C - 21 - 24 - 33 - 39 - 39
[0161] As is seen, the fully hydrogenated alkycycloparaffin fluid derived from
an alkyl naphthalene has the same influence on the pour point of the blend,
the
pour point of the blend being reduced non-linearly.
EXAMPLE 5
[0162] An alkylmethylbenzene fluid (ArPAO) was prepared and combined in
various amounts with GTL-6. The alkylmethylbenzene was prepared by first
oligomerizing a mixture of C8, CIo and C12 linear alpha olefins to give
oligomers
over promoted BF3 catalyst. The high boiling fraction, > 750 F (398.8 C), was
isolated as high quality PAO base stock after hydrogenation at 200 C, 600 psi
H2 pressure over a standard hydrogenation catalyst, a nickel on Kieselguhr
catalyst. The lighter oligomers with boiling points below 750 F were separated
by distillation. This light fraction usually contains olefins with less than
24
carbons. These light olefin oligomers were then further reacted with toluene
over a similar promoted BF3 catalyst as used in the oligomerization step. The
resulting alkylmethylbenzene fluid had excellent VI, pour point, thermal and
oxidative stability. This alkylmethylbenzene fluid was combined in various
amounts with GTL-6. The results are presented in Table 7 and Figure 1.
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TABLE 7
Wt% of 0 20 60 100
alkylmethylbenzene
Wt% of GTL 100 80 40 0
Kv 100 C, cS 6.02 5.87 5.53 5.22
Kv 40 C, cS 29.76 29.77 30.58 32.33
VI 141 132 107 73
Pour oint, C -21 - 27 - 36 <-60
[0163] As can be seen, the pour point of the GTL-6 was reduced by the
addition of the alkylmethylbenzene fluid.
EXAMPLE 6
[0164] The hydrogenated version of the alkylmethylbenzene fluid of Example
was prepared by hydrogenation of the fluid using 2 wt% nickel on Kieselguhr
catalyst (50 wt% nickel metal content) at 200 C, 800 psi H2 pressure for 8
hours.
The hydrogenated alkylmethylbenzene fluid was combined in various amounts
with GTL-6 and the results are presented in Table 8.
TABLE 8
Wt% of 0 20 60 100
hydrogenated
alkylmethylbenzene
fluid
Wt% of GTL 100 80 40 0
Kv 100 C, cS 6.02 5.99 5.82 5.73
Kv 40 C, cS 29.76 30.6 33.42 37.9
VI 141 133 105 73
Pour oint, C -21 -21 - 36 <-60
[0165] Again, a reduction in the pour point of the GTL is seen.
[0166] Example 7. An alkylbenzene fluid was prepared by alkylation of
benzene with 1-dodecene over a zeolite MCM22, according to the general
procedures as described in US 4962256. The property of this fluid was
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summarized in Table 1. This fluid was blended with GTL 6 and the blend
properties were summarized in following Table 9. Again, these data
demonstrated that low pour point alkylaromatic fluids recited in this
invention
improve the pour point of the blend stock when combined with GTL derived
base stocks.
TABLE 9
Wt% of 0 5 20 60 100
Alkylbenzene
in GTL6
Blend
Properties
Kv 100 C, cS 6.02 5.6 4.55 2.61 1.5
Kv 40 C, cS 29.76 25.7 19.45 8.8/2 4.22
VI 141 152 143 145
Pour Point, C -21 -35 -42 -65 -65
COMPARATIVE EXAMPLE 1
[0167] A C20-C24 alkyl benzene fluid was prepared according to the teaching
of USP 6,627,779. That C20-C24 alkyl benzene was blended with GTL-6 and the
pour points of the individual fluids and of various blends were reported in
Table
and Figure 1.
TABLE 10
C20-C24 alkyl benzene 0 5 20 60 100
Wt% of GTL-6 100 95 80 40 0
Kv 100 C, cS 6.02 6.03 5.85 5.44 5
Kv 40 C, cS 29.76 26.69 28.31 25.61 23.24
VI 141 142 143 142 135
Pour point, C - 21 - 21 - 6 6 9
[0168] As is seen the C20-C24 alkyl benzene of USP 6,627,779 exhibited a high
pour point and did not in any way reduce the pour point of the GTL fluid, the
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blends all exhibiting either no change or significantly increased pour points
as
compared to the data presented in Tables 6 and 7.
COMPARATIVE EXAMPLE 2
[0169] An ester of nominal kinematic viscosity at 100 C of 5 mm2/s (Ester 5)
was blended with GTL-6 in various amounts and the results are presented in
Table 11 and Figure 1.
TABLE 11
Wt% of ester 0 5 20 60 100
Wt% of GTL-6 100 95 80 40 0
Properties of Blends
Kv 100 C, cS 6.02 6.04 5.79 5.41 5.27
Kv 40 C, cS 29.76 29.02 27.92 26.25 26.29
VI 141 148 143 135 124
Pour oint, C -21 - 24 - 24 - 33 <-61
[0170] As can be seen Ester 5, despite having a pour point of < -61 had
substantially no effect on the pour point of the GTL-6 at treat levels of 5
and 20
wt% and only lowered the pour point of GTL from -21 down to -33 C at a treat
level of 60 wt% of Ester 5, clearly demonstrative of a lack of any significant
pour point reducing capacity and no synergistic impact as is the case when
alkylated naphthalene is employed. Merely because a second, added fluid has a
low pour point, therefore, does not automatically mean that the addition of
such
low pour point fluid to a higher pour point fluid will result in a mixture
having a
pour point significantly lower than that of the high pour point fluid. Thus,
the
present results secured using the alkylated naphthalene and alkylbenzene
synthetic fluids as disclosed herein are truly surprising and unexpected.
