Note: Descriptions are shown in the official language in which they were submitted.
CA 02602770 2013-09-25
Lubricating Oil Compositions Including Sulphurized Overbased Me I
Phonate Detergents
The present invention is concerned with a lubricating oil composition suitable
for use as a marine diesel cylinder lubricant. In particular, the present
invention is concerned with a marine diesel cylinder lubricant that exhibits
an
increased rate of acid neutralization.
Fuels used in marine diesel engines generally include a high sulphur content,
such as, for example, 2-3%. The exhaust gases therefore include sulphur
oxides which react with moisture to form sulphuric acid which corrodes and
wears components in the diesel engine, such as cylinder liners and piston
rings. Therefore, any acid must be neutralized as quickly as possible.
EP 0 839 894A discloses a marine diesel cylinder lubricant that exhibits a
rapid neutralization rate. The lubricant includes (A) at least one compound
selected from the group consisting of overbased sulphonates, phenates or
salicylates of alkaline earth metals, and (B) a bis-type succinic imide
compound having an absorption ratio, a/p, of absorption peaks in an IR
spectrum of not more than 0.005, wherein a is the intensity of an absorption
peak at 1550+10 cm-I and P is the intensity of absorption peak at 1700+cm-1.
EP 1 051 467B also discloses a marine diesel cylinder lubricant that exhibits
a rapid neutralization rate. The lubricant includes 0.5 to 2.5 % by weight of
a
succinimide dispersant, 3.5 to 10 % by weight of an overbased sulphonate
detergent and 11 to 24.5 % by weight of an overbased phenate detergent.
The aim of the present invention is to provide a lubricant composition that
exhibits an increased rate of acid neutralization.
In accordance with the present invention there is provided a lubricating oil
composition including at least one sulphurized overbased metal phenate
detergent prepared from a C9-C15 alkyl phenol, at least one sulphurizing
agent, at least one metal and at least one overbasing agent; the detergent
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2
including less than 6.0% by combined mass of unsulphurized C9-C15 alkyl
phenol and its unsulphurized metal salt.
The lubricating oil composition preferably has a total base number ('TBN') of
more than 30, preferably more than 35, mgKOH/g, as determined by ASTM
02896. The lubricating oil composition preferably has a TBN of less than 100
mgKOH/g, as determined by ASTM D2896.
In accordance with the present invention there is also provided use to
increase the rate of acid neutralization of a lubricating oil composition of
at
least one sulphurized overbased metal phenate detergent prepared from a
C9-C15 alkyl phenol, at least one sulphurizing agent, at least one metal and
at
least one overbasing agent; the sulphurized overbased metal phenate
detergent including less than 6.0% by mass of unsulphurized C9-C-15 alkyl
phenol and its unsulphurized metal salt.
In accordance with the present invention there is also provided a method of
increasing the rate of acid neutralization of a lubricating oil composition,
the
method including the step of adding to the lubricating oil composition at
least
one sulphurized overbased metal phenate detergent prepared from a C9-C15
alkyl phenol, at least one sulphurizing agent, at least one metal and at least
one overbasing agent; the sulphurized overbased metal phenate detergent
including less than 6.0% by mass of unsulphurized C9-C15 alkyl phenol and its
unsulphurized metal salt.
By 'alkyl phenol' we mean phenol having a linear or branched alkyl group
attached thereto.
The metal is preferably calcium.
The overbased phenate detergent is prepared from mono-, di- and
polysulphides of C9-C15 alkyl phenols. The C9-C15 alkyl substituted phenols
may contain one or more C9-C15 alkyl groups per aromatic ring. Preferably,
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the overbased phenate detergent is prepared from mono-, di- and
polysulphides of C10-C13 alkyl phenols.
The sulphurized C9-C15 alkyl phenols may be represented by the general
formula I:
OH = H OH
111 Sx 111 sx
wherein R represents a C9-C15 alkyl radical, n is an integer of 0 to 20, y is
an
integer of 0 to 4 and may be different for each aromatic nucleus and x is an
integer of from 1 to 7, typically 1 to 4. The individual groups represented by
R
may be the same or different and may contain from 9 to 15, preferably 10 to
13, carbon atoms. Preferably n is 0 to 4, y is 1 or 2 and may be different for
each aromatic nucleus and x is 1 to 4.
The sulphurized C9-C15 alkyl substituted phenols may be mixtures of the
above general formula and may include un-sulphurized phenolic material. It
is preferred that the level of un-sulphurized phenolic material is kept to a
minimum. The sulphurized C9-C15 alkyl substituted phenols may contain up
to 15%, preferably up to 9%, by weight of un-sulphurized phenolic material.
One preferred group of sulphurized C9-C15 alkyl substituted phenols are those
with a sulphur content of between 4 and 16 mass /0, preferably 4 to 14%, and
most preferably 6 to 12 mass A.
The sulphurized phenols, which will normally comprise a mixture of different
compounds, typically contain at least some sulphur which is either free, or is
only loosely bonded; the sulphur thus being available to attack nitrile
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4
elastomeric seals and is referred to as active sulphur. This active sulphur
may be present in the form of polysulphides, for example when x is three or
greater in formula I; in this form the active sulphur may be present at levels
which are typically up to 2 wt % or more.
The sulphurized C9-C15 alkyl phenols are prepared by the reaction of C9-C15
alkyl phenols in the presence of a sulphurizing agent; the sulphurizing agent
being an agent which introduces Sx bridging groups between phenols where x
is 1 to 7. Thus the reaction may be conducted with elemental sulphur or a
halide thereof such as sulphur monochloride or sulphur dichloride.
Preferably, sulphur monochloride is used.
The C9-C15 alkyl substituted phenols may be any phenol of general formula II
OH
R
Y
II
wherein R and y are as defined above. Mixtures of phenols of general
formula II may be used.
It is preferred that the oil soluble sulphurized phenol is derived from
sulphur
monochloride and has low levels of chlorine such as less than 1000 ppm of
chlorine. Preferably the chlorine content is 900 ppm or less e.g. 800 or less
and most preferably 500 ppm or less.
It is preferred that the phenol is a mixture of phenols and as such has an
average molecular weight of between 210 and 310, preferably between 230
and 290, and most preferably between 250 and 270. Most preferred mixtures
are mixtures of para-substituted monoalkylphenols. It is preferred that the
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. õ
phenols of general formula II are not hindered phenols although they may be
mixtures of phenols which comprise a minor proportion, such as less than 25
wt %, e.g. less than 10 wt %, of hindered phenol. By 'hindered phenols' is
meant phenols in which all the ortho and para reactive sites are substituted,
or sterically hindered phenols in which, either both ortho positions are
substituted or only one ortho position and the para position are substituted
and, in either case, the substituent is a tertiary alkyl group, e.g. t-butyl.
It is
preferred that for a given mixture of mono and di-alkyl substituted phenols,
e.g. dodecyl substituted, that the mono-substituted phenol is present in at
least 80 wt `)/0 and preferably in the range 90 to 95 wt %. It is preferred
that
the mole ratio of phenol to sulphur monochloride is 2 or greater and most
preferably is 2.2 or greater.
The level of sulphur, the required conversion of phenolic material to keep the
un-sulphurized material to a minimum and the chlorine levels are linked. It is
difficult to keep chlorine levels low whilst increasing sulphur content and
achieving the desired conversion, because more chlorine containing starting
material, i.e. S2Cl2, is usually required to achieve these targets; the task
is to
be able to achieve low chlorine whilst at the same time not having a
detrimental effect on the other two factors. It is preferred that the reaction
is
carried out in the temperature range of -15 or -10 to 150 C, e.g. 20 to 150 C
and preferably 60 to 150 C. It is most preferred that the reaction is carried
out at less than 110 C; the use of reaction temperatures below 110 C with
certain phenols results in lower levels of chlorine. Typically the reaction
temperature is between 60 and 90 C. Preferably the sulphur monochloride is
added to the reaction mixture at a rate of 4 x 10-4 to 15-4 cm3min-1g-1
phenol.
If the reaction mixture is not adequately mixed during this addition the
chlorine content may increase. The resultant product preferably has a
sulphur content of at least 4%, e.g. between 4 and 16%, more preferably 4 to
14 % and most preferably at least 6%, e.g. 7 to 12%. The process has the
advantage of not requiring complicated post reaction purification steps in
order to reduce the levels of chlorine in the intermediate product.
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Olefins and acetylenic compounds may be used to remove active sulphur
from the sulphurized C9-C15 alkyl substituted phenols.
Suitable olefins include mono-olefins, di-olefins, tri-olefins or higher
homologues. By suitable is meant olefins which are capable of reacting with
active sulphur and whose properties are such that the excess of such olefins
used may be removed from the reaction mixture without resulting in significant
decomposition of the sulphurized phenol. Preferred olefins are those with a
boiling point of up to 200 C and most preferably have a boiling point in the
range of 150 C to 200 C.
The mono-olefins may be unsubstituted aliphatic mono-olefins meaning that
they contain only carbon and hydrogen atoms, or they may be substituted
with one or more heteroatoms and/or heteroatom containing groups e.g.
hydroxyl, amino, cyano. An example of a suitable cyano substituted mono-
olefin is fumaronitrile. The mono-olefins may also be substituted with
aromatic functionality as, for example, in styrene. The mono-olefins may
contain for example ester, amide, carboxylic acid, carboxylate, alkaryl,
amidine, sulphinyl, sulphonyl or other such groups. It is preferred that the
mono-olefins are aliphatic and are not substituted with heteroatoms and/or
heteroatom containing groups other than hydroxyl or carboxylate groups. The
mono-olefins may be branched or non-branched.
The mono-olefin preferably has from 4 to 36 carbon atoms and most
preferably 8 to 20 carbon atoms. The mono-olefin may, for example, be an a-
olefin. Examples of a-olefins which may be used include: 1-butene, 1-
pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene,
1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene,
1-octadecene, 1-nonadecene, 1-eicosene, 1-heneicosene, 1-docosene, 1
tetracosene, 1-pentacosene, 1-hexacosene, 1-octacosene, and 1-
nonacosene. The a-olefin may be a mixture of a-olefins such as the following
commercially available mixtures: C15-C15, C12-C16, Cia-Cis, C14-C18, C16-C20,
C22-C28, and C30+ (Gulftene available from the Gulf Oil Company).
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Another class of mono-olefins are those containing a saturated alicyclic ring
and one double bond, e.g. an exocyclic double bond. The alicyclic ring
preferably contains at least six carbon atoms, and, advantageously, the
alicyclic ring is substituted by a methylene bridging group that forms a four-
membered ring with three of the ring carbon atoms. The methylene carbon
atom in such a bridging group may be substituted, preferably by two methyl
groups, e.g. as in 0-pinene. Other examples of mono-olefins include a-
pinene, methylene cyclohexane, camphene, and methylene cyclopentane etc.
and unsaturated compounds such as the various derivatives of acrylic acid
such as acrylate, methacrylate and acrylamide derivatives.
An example of a suitable mono-olefin is the C12 tetramer of propylene. Other
suitable mono-olefins include oligomers of, for example, ethylene. Typically
oligomeric olefins are mixtures; therefore mixtures of oligomeric mono-olefins
may be used such as mixtures of propylene oligomers.
The di-olefins, tri-olefins and higher homologues may be any such olefins
which meet the above identified performance requirement for the olefin.
Preferred di-olefins, tri-olefins and higher homologues are those selected
from:
(a) an acyclic olefin having at least two double bonds, adjacent double bonds
being separated by two saturated carbon atoms; or
(b) an olefin comprising an alicyclic ring, which ring comprises at least
eight
carbon atoms and at least two double bonds, each double bond being
separated from the closest adjacent double bond(s) by two saturated carbon
atoms.
The preferred olefins of group (a) are unsubstituted or substituted linear
terpenes. Unsubstituted linear terpenes for use in accordance with the
invention may be represented by the formula (C5H8),, wherein n is at least 2,
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,
,
8
that is, a terpene containing carbon and hydrogen atoms only. An example of
an unsubstituted linear terpene is squalene (in which n in the above formula
is
6). Possible substituents for linear terpenes to be used are, for example,
hydroxyl groups. Suitable substituted terpenes include famasol and geraniol
with geraniol being preferred. Other examples of suitable di-olefins include
dicyclopentadiene, dipentene, 1,3-cyclohexadiene, 1 ,5,-cyclooctadiene,
methylcyclopentadiene, limonene and 1,4-cyclohexadiene and polybutadiene
etc.
If desired, the group (b) olefins may contain at least three double bonds,
each
end of each double bond being separated from each adjacent double bond by
two saturated carbon atoms. An example of a suitable group (b) olefin having
three double bonds is 1,5,9-cyclododecatriene. An example of another tri-
olefin is cycloheptatriene.
The acetylenic compounds are compounds which are capable of reacting with
active sulphur and whose properties are such that the excess of such
compounds may be removed from the reaction mixture without resulting in
significant decomposition of the sulphurized phenol. An example of a suitable
acetylene material is phenyl acetylene.
Olefins are preferred to acetylenic compounds.
More than one olefin may of course be used if desired. Where two or more
olefins are used, these need not be compounds from the same group. Thus,
for example, mixtures of mono and diolefins may be used although this is not
preferred.
The olefin or acetylenic compound and active sulphur-containing sulphurized
phenol may be added in any order. Thus, for example, the olefin or acetylenic
compound may be introduced into a vessel already containing the sulphurized
phenol, or vice versa, or the two materials may be introduced simultaneously
into the vessel. This process may be carried out in a suitable solvent for the
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9
reactants and/or products. This is a solvent which does not cause problems
in removal which effect stability of the product. An example of a suitable
solvent which may be used is SN150 basestock. In some instances the olefin
when used in a sufficient amount may act as a solvent for the reaction.
The mass ratio of sulphurized phenol to olefin or acetylenic compound is such
that the olefin or acetylenic compound is always in excess of that required to
react with the active sulphur present in the intermediate. The exact levels
will
depend on the nature of the olefin or acetylenic compound, i.e. whether or
not, for example, it is a mono, di or tri olefin, its molecular weight and the
molecular weight of the sulphurized phenol used, its level of sulphur and
level
of active sulphur. For example, when the olefin is C12 propylene tetramer the
ratio is preferably in the range 1.3:1 to 9:1.
It is preferred that the reaction between the sulphurized phenol and the
olefin
or acetylenic compound is carried out at an elevated temperature of greater
that 120 C and, most preferably between 120 C to 250 C, and for 0.5 to 60
hours.
Substantially all of the unreacted olefin or acetylenic compound should be
removed preferably by means of vacuum distillation, post reaction, or other
separation methods. The exact method used will depend on the nature of the
olefin or acetylenic compound used. In some circumstances the unreacted
olefin or acetylenic compound may be removed by simply applying a vacuum
to the reaction vessel or may require the use of applied heating to elevate
the
temperature of the reaction mixture. Preferably the unreacted material is
removed by means of vacuum distillation and where necessary with the use
of heating. Other material, such as volatile material when vacuum distillation
is used, may be removed at the same time as the unreacted olefin or
acetylenic compound. By 'substantially all the unreacted olefin or acetylenic
compound' is meant that proportion which may be removed by the use of
such techniques as, for example, vacuum distillation. Typically there will be
less than 3 wt % of unreacted olefin or acetylenic compound remaining in the
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product and preferably between 0 to 3 wt % and most preferably 0.5 wt % or
less. This residual material may comprise as a major proportion the higher
molecular weight fractions present in the original olefin composition or
mixture
used. For example, in the case of the olefin being a propylene tetramer,
which is typically a mixture of olefins, residual material after removal of
excess olefin may comprise a high proportion of, for example, pentamer and
higher homologues of propylene.
It has been found that removal of substantially all the unreacted olefin or
acetylenic compound is required so that lubricating oil compositions
comprising olefin or acetylenic compound reacted additives achieve
acceptable performance in the Panel Coker test. This is an industry standard
bench test which is used to screen additives in lubricating oil formulations
to
evaluate their efficacy as, for example, antioxidants and/or their ability to
prevent deposition of carbonaceous deposits by maintaining such deposits in
a dispersed form in the oil. If the excess olefin or acetylenic compound is
not
removed inferior Panel Coker performance of the oil is observed. This is a
particular problem with di-olefins.
On completion of the reaction between sulphur monochloride and the phenol,
the temperature of the reaction mixture is increased to the olefin or
acetylenic
compound reaction temperature and the reaction carried out. This increase in
temperature may be achieved by means of a ramped temperature increase to
the reaction temperature. The olefin or acetylenic compound may be added
to the intermediate reaction mixture before, during or after the temperature
increase.
A catalyst may be used for the reaction between the olefin or acetylenic
compound and the sulphurized phenol. Suitable catalysts include
sulphurisation catalysts and nitrogen bases. The preferred catalysts are
nitrogen bases. Suitable nitrogen bases include nitrogen-containing ashless
dispersants which are commercially available materials such as Mannich
bases and the reaction products of hydrocarbyl acylating agents with amines,
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in particular polyisobutenyl succinimides may be used; these may be
prepared by any of the conventional routes. It is preferred to use a
polyisobutenyl succinimide in which the polyisobutenyl succinic anhydride is
prepared using the so-called thermal process in which polyisobutene is
reacted directly with maleic anhydride, without the use of chlorine, before
reaction with the amine to produce the final dispersant. Other suitable
nitrogen bases include simple amines such as, for example, mono-, di-, and
tri-butylamines, polyamines such as, for example, diethylenetriamine (DETA),
triethylenetetramine (TETA) and tetraethylenepentamine (TEPA), cyclic
amines for example morpholines and aromatic amines such as commercial
diphenylamines. A particularly suitable amine is n-octylamine. It has also
surprisingly been found that nitrile seal compatibility improves with the use
of
increasing levels of catalyst to prepare the additives of the present
invention.
The reaction with olefin or acetylenic compound has the benefit of reducing
the level of chlorine in sulphurized compounds.
The sulphurized C9-C15 alkyl substituted phenols are used to prepare the
overbased metal phenates by reaction with alkali or alkaline earth metal salts
or compounds. The overbased metal phenates may also have low levels of
chlorine e.g. less than 1000 ppm. The overbased metal phenates comprise
neutralized detergent as the outer layer of a metal base (e.g. carbonate)
micelle. Such overbased metal phenates may have a TBN (total base number
as determined by ASTM D 2896) of 50 or greater, preferably 100 or greater,
more preferably 150 or greater, and typically of from 250 to 450 or more. The
metals are in particular the alkali or alkaline earth metals, e.g., sodium,
potassium, lithium, calcium, and magnesium. The most commonly used
metals are calcium and magnesium and mixtures of calcium and/or
magnesium with sodium.
The overbased phenates may include at least one further surfactant such as,
for example, a sulphonic acid or an aliphatic carboxylic acid such as, for
example, stearic acid.
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Sulphonic acids are typically obtained by sulphonation of hydrocarbyl-
substituted, especially alkyl-substituted, aromatic hydrocarbons, for example,
those obtained from the fractionation of petroleum by distillation and/or
extraction, or by the alkylation of aromatic hydrocarbons. Examples include
those obtained by alkylating benzene, toluene, xylene, naphthalene, biphenyl
or their halogen derivatives, for example, chlorobenzene, chlorotoluene or
chloronaphthalene. Alkylation of aromatic hydrocarbons may be carried out
in the presence of a catalyst with alkylating agents having from about 3 to
more than 100 carbon atoms, such as, for example, haloparaffins, olefins that
may be obtained by dehydrogenation of paraffins, and polyoiefins, for
example, polymers of ethylene, propylene, and/or butene. The alkylaryl
sulphonic acids usually contain from about 7 to about 100 or more carbon
atoms. They preferably contain from about 16 to about 80 carbon atoms, or
12 to 40 carbon atoms, per alkyl-substituted aromatic moiety, depending on
the source from which they are obtained.
Another type of sulphonic acid which may be used comprises alkyl phenol
sulphonic acids. Such sulphonic acids can be sulphurized. Whether
sulphurized or non-sulphurized these sulphonic acids are believed to have
surfactant properties comparable to those of sulphonic acids, rather than
surfactant properties comparable to those of phenols.
Su!phonic acids suitable for use also include alkyl sulphonic acids, In such
compounds the alkyl group suitably contains 9 to 100 carbon atoms,
advantageously 12 to 80 carbon atoms, especially 16 to 60 carbon atoms.
Carboxylic acids which may be used include mono- and dicarboxylic acids.
Preferred monocarboxylic acids are those containing 1 to 30 carbon atoms,
especially 8 to 24 carbon atoms. Examples of monacarboxylic acids are iso-
octanoic acid, stearic acid, oleic acid, palmitic acid and behenic acid. Iso-
octanoic acid may, if desired, be used in the form of the mixture of C8 acid
isomers sold by Exxon Chemical under the trade mark "Cekanoic". Other
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suitable acids are those with tertiary substitution at the a-carbon atom and
dicarboxylic acids with more than 2 carbon atoms separating the carboxylic
groups. Further, dicarboxylic acids with more than 35 carbon atoms, for
example, 36 to 100 carbon atoms, are also suitable. Unsaturated carboxylic
acids can be sulphurized.
In another aspect of the invention, the carboxylic acid/derivative, if used,
has
8 to 11 carbon atoms in the carboxylic-containing moiety.
In a further aspect of the invention, where a carboxylic acid/derivative is
used,
this is not a monocarboxylic acid/derivative with more than 11 carbon atoms
in the carboxylic-containing moiety. In another aspect, the carboxylic
acid/derivative is not a dicarboxylic acid/derivative with more than 11 carbon
atoms in the carboxylic-containing moiety. In a further aspect, the carboxylic
acid/derivative is not a polycarboxylic acid/derivative with more than 11
carbon atoms in the carboxylic-containing moiety. In another aspect, a
carboxylic acid surfactant is not a hydrocarbyl-substituted succinic acid or a
derivative thereof.
Examples of other surfactants which may be used include the following
compounds, and derivatives thereof: naphthenic acids, especially naphthenic
acids containing one or more alkyl groups, dialkylphosphonic acids,
dialkylthiophosphonic acids, and dialkyldithiophosphoric acids, high molecular
weight (preferably ethoxylated) alcohols, dithiocarbamic acids,
thiophosphines, and dispersants. Surfactants of these types are well known
to those skilled in the art.
Metal salts of sulphurized phenols are prepared by reaction with an
appropriate metal compound such as an oxide or hydroxide and neutral or
overbased products may be obtained by methods well known in the art.
Examples of suitable overbasing agents are carbon dioxide, a source of
boron, for example, boric acid, sulphur dioxide, hydrogen sulphide, and
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ammonia. Preferred overbasing agents are carbon dioxide or boric acid, or a
mixture of the two. The most preferred overbasing agent is carbon dioxide
and, for convenience, the treatment with an overbasing agent will in general
be referred to as "carbonation". Unless the context clearly requires
otherwise,
it will be understood that references herein to carbonation include references
to treatment with other overbasing agents.
Advantageously, on completion of the carbonation step, part of the basic
calcium compound remains uncarbonated. Advantageously, up to 15 mass
% of the basic calcium compound remains uncarbonated, especially up to 11
mass %.
Carbonation is effected at less than 100 C. Typically the carbonation is
effected at at least 15 C, preferably at least 25 C. Advantageously,
carbonation is carried out at less than 80 C, more advantageously less than
60 C, preferably at most 50 C, more preferably at most 40 C, and especially
at most 35 C. Advantageously, the temperature is maintained substantially
constant during the or each carbonation step, with only minor fluctuations.
Where there is more than one carbonation step, both or all carbonation steps
are preferably carried out at substantially the same temperature, although
different temperatures may be used, if desired, provided that each step is
carried out at less than 100 C.
Carbonation may be effected at atmospheric, super-atmospheric or sub-
atmospheric pressures. Preferably, carbonation is carried out at atmospheric
pressure.
Advantageously, there is a first carbonation step that is followed by a "heat-
soa king" step in which the mixture is maintained, without addition of any
further chemical reagents, in a selected temperature range (or at a selected
temperature), which is normally higher than the temperature at which
carbonation is effected, for a period before any further processing steps are
carried out. The mixture is normally stirred during heat-soaking. Typically,
CA 02602770 2007-09-18
heat-soaking may be carried out for a period of at least 30 minutes,
advantageously at least 45 minutes, preferably at least 60 minutes, especially
at least 90 minutes. Temperatures at which heat-soaking may be carried out
are typically in the range of from 15 C to just below the reflux temperature
of
the reaction mixture, preferably 25 C to 60 C: the temperature should be
such that substantially no materials (for example, solvents) are removed from
the system during the heat-soaking step. We have found that heat-soaking
has the effect of assisting product stabilization, dissolution of solids, and
filtrability.
Preferably, following the first carbonation step (and the heat-soaking step,
if
used), a further quantity of basic calcium compound is added to the mixture
and the mixture is again carbonated, the second carbonation step
advantageously being followed by a heat-soaking step.
Basic calcium compounds for use in manufacture of the overbased
detergents include calcium oxide, hydroxide, alkoxides, and carboxylates.
Calcium oxide and, more especially, hydroxide are preferably used. A
mixture of basic compounds may be used, if desired.
The mixture to be overbased by the overbasing agents should normally
contain water, and may also contain one or more solvents, promoters or other
substances commonly used in overbasing processes.
Examples of suitable solvents are aromatic solvents, for example, benzene,
alkyl-substituted benzenes, for example, toluene or xylene, halogen-
substituted benzenes, and lower alcohols (with up to 8 carbon atoms).
Preferred solvents are toluene and methanol. The amount of toluene used is
advantageously such that the percentage by mass of toluene, based on the
calcium overbased detergent (excluding oil) is at least 1.5, preferably at
least
15, more preferably at least 45, especially at least 60, more especially at
least
90. For practical/economic reasons, the said percentage of toluene is
typically at most 1200, advantageously at most 600, preferably at most 500,
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16
especially at most 150. The amount of methanol used is advantageously
such that the percentage by mass of methanol, based on the calcium
detergent (excluding oil) is at least 1.5, preferably at least 15, more
preferably
at least 30, especially at least 45, more especially at least 50. For
practical/economic reasons, the said percentage of methanol (as solvent) is
typically at most 800, advantageously at most 400, preferably at most 200,
especially at most 100. The above percentages apply whether the toluene
and methanol are used together or separately.
Examples of suitable promoters are lower alcohols (with up to 8 carbon
atoms) and water. Preferred promoters for use in accordance with the
invention are methanol and water. The amount of methanol used is
advantageously such that the percentage by mass of methanol, based on the
initial charge of basic calcium compound, for example, calcium hydroxide
(that is, excluding any basic calcium compound added in a second or
subsequent step) is at least 6, preferably at least 60, more preferably at
least
120, especially at least 180, more especially at least 210. For
practical/economic reasons, the said percentage of methanol (as promoter) is
typically at most 3200, advantageously at most 1600, preferably at most 800,
especially at most 400. The amount of water in the initial reaction mixture
(prior to treatment with the overbasing agent) is advantageously such that the
percentage by mass of water, based on the initial charge of basic calcium
compound(s), for example, calcium hydroxide, (that is, excluding any basic
calcium compound(s) added in a second or subsequent step) is at least 0.1,
preferably at least 1, more preferably at least 3, especially at least 6, more
especially at least 12, particularly at least 20. For practical/economic
reasons, the said percentage of water is typically at most 320,
advantageously at most 160, preferably at most 80, especially at most 40. If
reactants used are not anhydrous, the proportion of water in the reaction
mixture should take account of any water in the components and also water
formed by neutralization of the surfactants. In particular, allowance must be
made for any water present in the surfactants themselves.
CA 02602770 2007-09-18
17
Advantageously, the reaction medium comprises methanol, water (at least
part of which may be generated during salt formation), and toluene.
If desired, low molecular weight carboxylic acids (with 1 to about 7 carbon
atoms), for example, formic acid, inorganic halides, or ammonium compounds
may be used to facilitate carbonation, to improve filtrability, or as
viscosity
agents for overbased detergents. The process does not, however, require
the use of an inorganic halide or ammonium salt catalyst, for example,
ammonium salts of lower carboxylic acids or of alcohols, and the overbased
detergents produced are thus preferably free from groups derived from such a
halide or ammonium catalyst. (Where an inorganic halide or ammonium salt
is used in an overbasing process the catalyst will normally be present in the
final overbased detergent.)
Oil-soluble, dissolvable, or stably dispersible as that terminology is used
herein does not necessarily indicate that the additives or intermediates are
soluble, dissolvable, miscible, or capable of being suspended in oil in all
proportions. It does mean, however, that they are, for instance, soluble or
stably dispersible in oil to an extent sufficient to exert their intended
effect in
the environment in which the oil is employed. Moreover, the additional
incorporation of other additives may also permit incorporation of higher
levels
of a particular additive or intermediate, if desired.
The overbased phenates can be incorporated into base oil in any convenient
way. Thus, they can be added directly to the oil by dispersing or by
dissolving
them in the oil at the desired level of concentration, optionally with the aid
of a
suitable solvent such as, for example, toluene, cyclohexane, or
tetrahydrofuran. In some cases blending may be effected at room
temperature: in other cases elevated temperatures are advantageous such as
up to 100 C.
Base oils include those suitable for use in marine diesel engines.
CA 02602770 2007-09-18
18
Synthetic base oils include alkyl esters of dicarboxylic acids, polyglycols
and
alcohols: poly-a-olefins, polybutenes, alkyl benzenes, organic esters of
phosphoric acids and polysilicone oils.
Natural base oils include mineral lubricating oils which may vary widely as to
their crude source, for example, as to whether they are paraffinic,
naphthenic,
mixed, or paraffinic-naphthenic, as well as to the method used in their
production, for example, distillation range, straight run or cracked,
hydrorefined, solvent extracted and the like.
More specifically, natural lubricating oil base stocks which can be used may
be straight mineral lubricating oil or distillates derived from paraffinic,
naphthenic, asphaltic, or mixed base crude oils. Alternatively, if desired,
various blended oils may be employed as well as residual oils, particularly
those from which asphaltic constituents have been removed. The oils may be
refined by any suitable method, for example, using acid, alkali, and/or clay
or
other agents such, for example, as aluminium chloride, or they may be
extracted oils produced, for example, by solvent extraction with solvents, for
example, phenol, sulphur dioxide, furfural, dichlorodiethylether,
nitrobenzene,
or crotonaldehyde.
The lubricating oil base stock conveniently has a viscosity of about 2.5 to
about 12 cSt or mm2 /sec and preferably about 3.5 to about 9 cSt or mm2/sec
at 100 C.
Additional additives may be incorporated into the lubricating oil composition
to
enable it to meet particular requirements. Examples of additives which may
be included in lubricating oil compositions are further detergents,
dispersants,
anti-wear agents and pour point depressants.
The ashless dispersants comprise an oil soluble polymeric hydrocarbon
backbone having functional groups that are capable of associating with
particles to be dispersed. Typically, the dispersants comprise amine, alcohol,
CA 02602770 2007-09-18
19
amide, or ester polar moieties attached to the polymer backbone often via a
bridging group. The ashless dispersant may be, for example, selected from
oil soluble salts, esters, amino-esters, amides, imides, and oxazolines of
long
chain hydrocarbon substituted mono and dicarboxylic acids or their
anhydrides; thiocarboxylate derivatives of long chain hydrocarbons; long
chain aliphatic hydrocarbons having a polyamine attached directly thereto;
and Mannich condensation products formed by condensing a long chain
substituted phenol with formaldehyde and polyalkylene polyamine.
The oil soluble polymeric hydrocarbon backbone is typically an olefin polymer
or polyene, especially polymers comprising a major molar amount (i.e.,
greater than 50 mole ')/0) of a C2 to C18 olefin (e.g., ethylene, propylene,
butylene, isobutylene, pentene, octene-1, styrene), and typically a C2 to C5
olefin. The oil soluble polymeric hydrocarbon backbone may be a
homopolymer (e.g., polypropylene or polyisobutylene) or a copolymer of two
or more of such olefins (e.g., copolymers of ethylene and an alpha-olefin such
as propylene or butylene, or copolymers of two different alpha-olefins). Other
copolymers include those in which a minor molar amount of the copolymer
monomers, e.g. 1 to 10 mole `)/0, is an am-diene, such as a C3 to C22 non-
conjugated diolefin (e.g. a copolymer of isobutylene and butadiene, or a
copolymer of ethylene, propylene and 1,4-hexadiene or 5-ethylidene-2-
norbornene). Atactic propylene oligomer typically having M. of from 700 to
5000 may also be used, as described in EP-A-490454, as well as
heteropolymers such as polyepoxides.
One preferred class of olefin polymers is polybutenes and specifically
polyisobutenes (PIB) or poly-n-butenes, such as may be prepared by
polymerization of a C4 refinery stream. Other preferred classes of olefin
polymers are ethylene alpha-olefin (EAO) copolymers and alpha-olefin homo-
and copolymers having in each case a high degree (e.g. >30%) of terminal
vinylidene unsaturation. That is, the polymer has the following structure:
CA 02602770 2007-09-18
. .
7
P ¨HC -=---CH2
wherein P is the polymer chain and R is a C1¨ C18 alkyl group, typically
methyl or ethyl. Preferably the polymers will have at least 50% of the polymer
chains with terminal vinylidene unsaturation. EA0 copolymers of this type
preferably contain 1 to 50 wt% ethylene, and more preferably 5 to 48 wt%
ethylene. Such polymers may contain more than one alpha-olefin and may
contain one or more C3 to C22 diolefins. Also usable are mixtures of EAO's of
varying ethylene content. Different polymer types, e.g. EAO and PIB, may
also be mixed or blended, as well as polymers differing in M.; components
derived from these also may be mixed or blended.
Suitable olefin polymers and copolymers may be prepared by various catalytic
polymerization processes. In one method, hydrocarbon feed streams, typically
C3 ¨ C5 monomers, are cationically polymerized in the presence of a Lewis
acid catalyst and, optionally, a catalytic promoter, e.g., an organoaluminum
catalyst such as ethylaluminum dichloride and an optional promoter such as
FICI. Most commonly, polyisobutylene polymers are derived from Raffinate I
refinery feedstreams. Various reactor configurations can be utilized, e.g.
tubular or stirred tank reactors, as well as fixed bed catalyst systems in
addition to homogeneous catalysts. Such polymerization processes and
catalysts are described, e.g., in US-A 4,935,576; 4,952,739; 4,982,045; and
UK-A 2,001,662.
Conventional Ziegler-Natta polymerization processes may also be employed
to provide olefin polymers suitable for use in preparing dispersants and other
additives. However, preferred polymers may be prepared by polymerising the
appropriate monomers in the presence of a particular type of Ziegler-Natta
catalyst system comprising at least one metallocene (e.g., a cyclopentadienyl-
transition metal compound) and, preferably, a cocatalyst or an activator,
e.g.,
an alumoxane compound or an ionising ionic activator such as tri (n-butyl)
ammonium tetra (pentafluorophenyl) boron.
CA 02602770 2007-09-18
,
21
Metallocene catalysts are, for example, bulky ligand transition metal
compounds of the formula:
[L]mM[A]n
where L is a bulky ligand, A is a leaving group, M is a transition metal and m
and n are such that the total ligand valency corresponds to the transition
metal valency. Preferably the catalyst is four co-ordinate such that the
compound is ionizable to a If valency state. The ligands L and A may be
bridged to each other, and if two ligands A and/or L are present, they may be
bridged. The metallocene compound may be a full sandwich compound
having two or more ligands L which may be cyclopentadienyl ligands or
cyclopentadienyl derived ligands, or they may be half sandwich compounds
having one such ligand L. The ligand may be mono- or polynuclear or any
other ligand capable of ri-5 bonding to the transition metal.
One or more of the ligands may it-bond to the transition metal atom, which
may be a Group 4, 5 or 6 transition metal and/or a lanthanide or actinide
transition metal, with zirconium, titanium and hafnium being particularly
preferred.
The ligands may be substituted or unsubstituted, and mono-, di-, tri, tetra-
and
penta-substitution of the cyclopentadienyl ring is possible. Optionally the
substituent(s) may act as one or more bridge between the ligands and/or
leaving groups and/or transition metal. Such bridges typically comprise one or
more of a carbon, germanium, silicon, phosphorus or nitrogen atom-
containing radical, and preferably the bridge places a one atom link between
the entities being bridged, although that atom may and often does carry other
substituents.
CA 02602770 2007-09-18
22
The metallocene may also contain a further displaceable ligand, preferably
displaced by a cocatalyst - a leaving group - that is usually selected from a
wide variety of hydrocarbyl groups and halogens.
Such polymerizations, catalysts, and cocatalysts or activators are described,
for example, in US 4,530,914; 4,665,208; 4,808,561; 4,871,705; 4,897,455;
4,937,299; 4,952,716; 5,017,714; 5,055,438; 5,057,475; 5,064,802;
5,096,867; 5,120,867; 5,124,418; 5,153,157; 5,198,401; 5,227,440;
5,241,025; EP-A- 129,368; 277,003; 277,004; 420436; 520,732;
W091/04257; 92/00333; 93/08199 and 93/08221; and 94/07928.
The oil soluble polymeric hydrocarbon backbone will usually have a number
average molecular weight (M.) within the range of from 300 to 20,000. The
M. of the polymer backbone is preferably within the range of 500 to 10,000,
more preferably 700 to 5,000, where its use is to prepare a component having
the primary function of dispersancy. Polymers of both relatively low molecular
weight (e.g. M. = 500 to 1500) and relatively high molecular weight (e.g. M. =
1500 to 5,000 or greater) are useful to make dispersants. Particularly useful
olefin polymers for use in dispersants have M. within the range of from 1500
to 3000. Where the oil additive component is also intended to have a
viscosity modifying effect, it is desirable to use a polymer of higher
molecular
weight, typically with M. of from 2,000 to 20,000; and if the component is
intended to function primarily as a viscosity modifier then the molecular
weight
may be even higher, e.g., M. of from 20,000 up to 500,000 or greater.
Furthermore, the olefin polymers used to prepare dispersants preferably have
approximately one double bond per polymer chain, preferably as a terminal
double bond.
Polymer molecular weight, specifically M., can be determined by various
known techniques. One convenient method is gel permeation
chromatography (GPC), which additionally provides molecular weight
distribution information (see W. W. Yau, J. J. Kirkland and D. D. Bly, "Modern
Size Exclusion Liquid Chromatography", John Wiley and Sons, New York,
CA 02602770 2007-09-18
23
1979). Another useful method, particularly for lower molecular weight
polymers, is vapour pressure osmometry (see, e.g., ASTM D3592).
The oil soluble polymeric hydrocarbon backbone may be functionalized to
incorporate a functional group into the backbone of the polymer, or as one or
more groups pendant from the polymer backbone. The functional group
typically will be polar and contain one or more hetero atoms such as P, 0, S,
N, halogen, or boron. It can be attached to a saturated hydrocarbon part of
the oil soluble polymeric hydrocarbon backbone via substitution reactions or
to an olefinic portion via addition or cycloaddition reactions. Alternatively,
the
functional group can be incorporated into the polymer in conjunction with
oxidation or cleavage of the polymer chain end (e.g. as in ozonolysis).
Useful functionalization reactions include: halogenation of the polymer at an
olefinic bond and subsequent reaction of the halogenated polymer with an
ethylenically unsaturated functional compound (e.g. maleation where the
polymer is reacted with maleic acid or anhydride); reaction of the polymer
with
an unsaturated functional compound by the "ene" reaction absent
halogenation; reaction of the polymer with at least one phenol group (this
permits derivatization in a Mannich base-type condensation); reaction of the
polymer at a point of unsaturation with carbon monoxide using a Koch-type
reaction to introduce a carbonyl group in an iso or neo position; reaction of
the polymer with the functionalizing compound by free radical addition using a
free radical catalyst; reaction with a thiocarboxylic acid derivative; and
reaction of the polymer by air oxidation methods, epoxidation,
chloroamination, or ozonolysis. It is preferred that the polymer is not
halogenated.
The functionalized oil soluble polymeric hydrocarbon backbone is then further
derivatized with a nucleophilic reactant such as an amine, amino-alcohol,
alcohol, metal compound or mixture thereof to form a corresponding
derivative.
CA 02602770 2007-09-18
24
Useful amine compounds for derivatizing functionalized polymers comprise at
least one amine and can comprise one or more additional amine or other
reactive or polar groups. These amines may be hydrocarbyl amines or may
be predominantly hydrocarbyl amines in which the hydrocarbyl group includes
other groups, e.g. hydroxyl groups, alkoxy groups, amide groups, nitriles,
imidazoline groups, and the like. Particularly useful amine compounds
include mono- and polyamines, e.g. polyalkylene and polyoxyalklene
polyamines of about 2 to 60, conveniently 2 to 40 (e.g., 3 to 20), total
carbon
atoms and about 1 to 12, conveniently 3 to 12, and preferably 3 to 9 nitrogen
atoms in the molecule. Mixtures of amine compounds may advantageously
be used such as those prepared by reaction of alkylene dihalide with
ammonia. Preferred amines are aliphatic saturated amines, including, e.g.,
1,2-diaminoethane; 1,3-diaminopropane; 1,4-diaminobutane; 1,6-
diaminohexane; polyethylene amines such as diethylene triamine; triethylene
tetramine; tetraethylene pentamine; and polypropyleneamines such as 1,2-
propylene diamine; and di-(1,2-propylene)triamine.
Other useful amine compounds include: alicyclic diamines such as 1,4-
di(aminomethyl) cyclohexane, and heterocyclic nitrogen compounds such as
imidazolines. A particularly useful class of amines are the polyamido and
related amido-amines as disclosed in US 4,857,217; 4,956,107; 4,963,275;
and 5,229,022. Also usable is tris(hydroxymethyl)amino methane (THAM) as
described in US 4,102,798; 4,113,639; 4,116,876; and UK 989,409.
Dendrimers, star-like amines, and comb-structure amines may also be used.
Similarly, one may use the condensed amines disclosed in US 5,053,152.
The functionalized polymer is reacted with the amine compound according to
conventional techniques as described in EP-A 208,560; US 4,234,435 and
US 5,229,022.
The functionalized oil soluble polymeric hydrocarbon backbones also may be
derivatized with hydroxy compounds such as monohydric and polyhydric
alcohols or with aromatic compounds such as phenols and naphthols.
Polyhydric alcohols are preferred, e.g. alkylene glycols in which the alkylene
CA 02602770 2007-09-18
radical contains from 2 to 8 carbon atoms. Other useful polyhydric alcohols
include glycerol, mono-oleate of glycerol, monostearate of glycerol,
monomethyl ether of glycerol, pentaerythritol, dipentaerythritol, and mixtures
thereof. An ester dispersant may also be derived from unsaturated alcohols
such as allyl alcohol, cinnamyl alcohol, propargyl alcohol, 1-cyclohexane-3-
ol,
and ley! alcohol. Still other classes of the alcohols capable of yielding
ashless dispersants comprise the ether-alcohols and including, for example,
the oxy-alkylene, oxy-arylene. They are exemplified by ether-alcohols having
up to 150 oxy-alkylene radicals in which the alkylene radical contains from 1
to 8 carbon atoms. The ester dispersants may be di-esters of succinic acids
or acidic esters, i.e. partially esterified succinic acids; as well as
partially
esterified polyhydric alcohols or phenols, i.e. esters having free alcohols or
phenolic hydroxyl radicals. An ester dispersant may be prepared by one of
several known methods as illustrated, for example, in US 3,381,022.
A preferred group of ashless dispersants includes those derived from
polyisobutylene substituted with succinic anhydride groups and reacted with
polyethylene amines (e.g. tetraethylene pentamine, pentaethylene
(di)pentamine, polyoxypropylene diamine) aminoalcohols such as
trismethylolaminomethane and optionally additional reactants such as
alcohols and reactive metals, e.g. pentaerythritol, and combinations thereof).
Also useful are dispersants wherein a polyamine is attached directly to the
long chain aliphatic hydrocarbon as shown in US 3,275,554 and 3,565,804
where a halogen group on a halogenated hydrocarbon is displaced with
various alkylene polyamines.
Another class of ashless dispersants comprises Mannich base condensation
products. Generally, these are prepared by condensing about one mole of an
alkyl-substituted mono- or polyhydroxy benzene with about 1 to 2.5 moles of
carbonyl compounds (e.g. formaldehyde and paraformaldehyde) and about
0.5 to 2 moles polyalkylene polyamine as disclosed, for example, in US
3,442,808. Such Mannich condensation products may include a long chain,
high molecular weight hydrocarbon (e.g. M. of 1,500 or greater) on the
CA 02602770 2007-09-18
26
benzene group or may be reacted with a compound containing such a
hydrocarbon, for example, polyalkenyl succinic anhydride, as shown in US
3,442,808.
Examples of functionalized and/or derivatized olefin polymers based on
polymers synthesized using metallocene catalyst systems are described in
US 5,128,056; 5,151,204; 5,200,103; 5,225,092; 5,266,223; EP-A-440,506;
513,157; 513,211. The functionalization and/or derivatizations and/or post
treatments described in the following patents may also be adapted to
functionalize and/or derivatize the preferred polymers described above: US
3,087,936; 3,254,025; 3,275,554; 3,442,808, and 3,565,804.
The dispersant can be further post-treated by a variety of conventional post
treatments such as boration, as generally taught in US 3,087,936 and
3,254,025. This is readily accomplished by treating an acyl nitrogen-
containing dispersant with a boron compound selected from the group
consisting of boron oxide, boron halides, boron acids and esters of boron
acids, in an amount to provide from about 0.1 atomic proportion of boron for
each mole of the acylated nitrogen composition to about 20 atomic
proportions of boron for each atomic proportion of nitrogen of the acylated
nitrogen composition. Usefully the dispersants contain from about 0.05 to 2.0
wt. %, e.g. 0.05 to 0.7 wt. %, boron based on the total weight of the borated
acyl nitrogen compound. The boron, which appears be in the product as
dehydrated boric acid polymers (primarily (HB02)3), is believed to attach to
the dispersant imides and diimides as amine salts, e.g. the metaborate salt of
the diimide. Boration is readily carried out by adding from about 0.05 to 4,
e.g. 1 to 3, wt. % (based on the weight of acyl nitrogen compound) of a boron
compound, preferably boric acid, usually as a slurry, to the acyl nitrogen
compound and heating with stirring at from 135 to 190 C, e.g. 140 -170 C,
for from 1 to 5 hours followed by nitrogen stripping. Alternatively, the boron
treatment can be carried out by adding boric acid to a hot reaction mixture of
the dicarboxylic acid material and amine while removing water.
CA 02602770 2007-09-18
27
Metal-containing or ash-forming detergents function both as detergents to
reduce or remove deposits and as acid neutralisers or rust inhibitors, thereby
reducing wear and corrosion and extending engine life. Detergents generally
comprise a polar head with a long hydrophobic tail, with the polar head
comprising a metal salt of an acidic organic compound. The salts may contain
a substantially stoichiometric amount of the metal in which case they are
usually described as normal or neutral salts, and would typically have a total
base number or TBN (as may be measured by ASTM D2896) of from 0 to 80.
It is possible to include large amounts of a metal base by reacting an excess
of a metal compound such as an oxide or hydroxide with an acidic gas such
as carbon dioxide. The resulting overbased detergent comprises neutralized
detergent as the outer layer of a metal base (e.g. carbonate) micelle. Such
overbased detergents may have a TBN of 150 or greater, and typically of
from 250 to 450 or more.
Detergents that may be used include oil-soluble neutral and overbased
sulphonates, phenates, sulphurized phenates, thiophosphonates, salicylates,
and naphthenates and other oil-soluble carboxylates of a metal, particularly
the alkali or alkaline earth metals, e.g., sodium, potassium, lithium,
calcium,
and magnesium. The most commonly used metals are calcium and
magnesium, which may both be present in detergents used in a lubricant, and
mixtures of calcium and/or magnesium with sodium. Particularly convenient
metal detergents are neutral and overbased calcium sulphonates having TBN
of from 20 to 450 TBN, and neutral and overbased calcium phenates and
sulphurized phenates having TBN of from 50 to 450.
Dihydrocarbyl dithiophosphate metal salts are frequently used as anti-wear
and antioxidant agents. The metal may be an alkali or alkaline earth metal, or
aluminium, lead, tin, molybdenum, manganese, nickel or copper. The zinc
salts are most commonly used in lubricating oil in amounts of 0.1 to 10,
preferably 0.2 to 2 wt. %, based upon the total weight of the lubricating oil
composition. They may be prepared in accordance with known techniques by
first forming a dihydrocarbyl dithiophosphoric acid (DDPA), usually by
reaction
CA 02602770 2007-09-18
28
of one or more alcohol or a phenol with P2S5 and then neutralising the formed
DDPA with a zinc compound. The zinc dihydrocarbyl dithiophosphates can be
made from mixed DDPA which in turn may be made from mixed alcohols.
Alternatively, multiple zinc dihydrocarbyl dithiophosphates can be made and
subsequently mixed.
Thus the dithiophosphoric acid containing secondary hydrocarbyl groups used
in this invention may be made by reacting mixtures of primary and secondary
alcohols. Alternatively, multiple dithiophosphoric acids can be prepared
where the hydrocarbyl groups on one are entirely secondary in character and
the hydrocarbyl groups on the others are entirely-primary in character. To
make the zinc salt any basic or neutral zinc compound could be used but the
oxides, hydroxides and carbonates are most generally employed.
Commercial additives frequently contain an excess of zinc due to use of an
excess of the basic zinc compound in the neutralisation reaction.
The preferred zinc dihydrocarbyl dithiophosphates useful in the present
invention are oil soluble salts of dihydrocarbyl dithiophosphoric acids and
may
be represented by the following formula:
S -
R0\11
/PS Zn
-2
wherein R and R' may be the same or different hydrocarbyl radicals
containing from 1 to 18, preferably 2 to 12, carbon atoms and including
radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl and cycloaliphatic
radicals. Particularly preferred as R and R' groups are alkyl groups of 2 to 8
carbon atoms. Thus, the radicals may, for example, be ethyl, n-propyl,
propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl,
dodecyl,
octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl,
propenyl, butenyl. In order to obtain oil solubility, the total number of
carbon
atoms (i.e. R and R') in the dithiophosphoric acid will generally be about 5
or
greater. The zinc dihydrocarbyl dithiophosphate can therefore comprise zinc
CA 02602770 2007-09-18
29
dialkyl dithiophosphates. At least 50 (mole) % of the alcohols used to
introduce hydrocarbyl groups into the dithiophosphoric acids are secondary
alcohols.
Additional additives are typically incorporated into the compositions of the
present invention. Examples of such additives are antioxidants, anti-wear
agents, friction modifiers, rust inhibitors, anti-foaming agents,
demulsifiers,
and pour point depressants.
Pour point depressants, otherwise known as lube oil flow improvers, lower the
minimum temperature at which the fluid will or can be poured. Such
additives are well known. Typical of those additives which improve the low
temperature fluidity of the fluid are Cs to Cis dialkyl fumarate/vinyl
aceteate
copolymers and polyalkylmethacrylates.
Foam control can be provided by many compounds including antifoamant of
the polysiloxane type, for example, silicone oil or polydimethyl siloxane.
When lubricating compositions contain one or more of the above-mentioned
additives, each additive is typically blended into the base oil in an amount
which enables the additive to provide its desired function. Representative
effective amounts of such additives, when used in a marine diesel lubricant
are as follows:
Additive Mass % a.i.* Mass % a.i.*
(Broad) (Preferred)
Detergent(s) 1-18 3-12
Dispersant(s) 0.5-5 1-3
Anti-wear agent(s) 0.1-1.5 0.5-1.3
Pour point depressant 0.03-0.15 0.05-0.1
Mineral or synthetic base oil Balance Balance
CA 02602770 2007-09-18
* Mass % active ingredient based on the final oil.
The components may be incorporated into a base oil in any convenient way.
Thus, each of the components can be added directly to the oil by dispersing
or dissolving it in the oil at the desired level of concentration. Such
blending
may occur at ambient temperature or at an elevated temperature.
Preferably all the additives except for the pour point depressant are blended
into a concentrate or additive package, that is subsequently blended into
basestock to make finished lubricant. Use of such concentrates is
conventional. The concentrate will typically be formulated to contain the
additives in proper amounts to provide the desired concentration in the final
formulation when the concentrate is combined with a predetermined amount
of base lubricant.
Preferably the concentrate is made in accordance with the method described
in US 4,938,880. That patent describes making a premix of ashless
dispersant and metal detergents that is pre-blended at a temperature of at
least about 100 C. Thereafter the pre-mix is cooled to at least 85 C and the
additional components are added.
The final formulations may employ from 2 to 30 mass % and preferably 10 to
25 mass %, typically about 15 to 23 mass % of the concentrate or additive
package with the remainder being base oil.
The invention will now be described by way of illustration only with reference
to the following examples. In the examples, unless otherwise noted, all treat
rates of all additives are reported as mass percent active ingredient.
CA 02602770 2007-09-18
. =
31
Synthesis of Sulphurized Dodecylphenol
Charges:
Charge weights (g) to make approx. 1 kg of sulphurized dodecylphenol:
Reactor Charge (g)
Dodecylphenol 1102
Measuring cylinder
Sulphur monochloride 275
Caustic trap
Sodium hydroxide
(50% aqueous) 800
Water 800 -----
Reactor addition
Dec-1-one 202
Heating Profile
Day 1:
Start Target Ramp Time Dwell
Temp. Temp. Time
( C) ( C) (min.) (min.)
Ambient 60 10 2
60 80 120 90
80 85 30 2
85 110 30 180
Days 2 and 3:
Start Target Ramp Time Dwell
Temp. Temp. Time
( C) ( C) (min.) (min.)
Ambient 110 40 2
110 175 50 Hold
Method
Day 1
Sulphur monochloride (SMC) is corrosive and toxic, and therefore the
following method of charging was used to minimize the risk of exposure. A
CA 02602770 2007-09-18
32
charge of SMC, close to the proposed weight, was first poured into a 150 ml
beaker and from there to a 100 ml measuring cylinder which had been placed
on a balance. The exact weight was recorded from which the dodecylphenol
(DDP) charge was calculated. The caustic trap was set up at this stage by
charging a 3 litre beaker with sodium hydroxide solution.
The DDP was then weighed into a 1 litre baffled flask. The flask was set up
for reflux and heated to 60 C under a nitrogen blanket using the above
profile. At 60 C the sulphur monochloride addition was started via a
peristaltic pump over 4 hours using two 16 gauge flat ended stainless steel
needles joined by viton tubing. The-weight loss over time was noted varying
the addition rate as necessary. During this time, while the temperature was
allowed to follow the programmed ramp given above, the stirrer was adjusted
to keep the mixture stirring briskly. The mixture thickened during addition;
stirring was started at approx. 270 rpm and had been increased to 500 rpm by
the end of addition.
At the end of addition the stainless needle and septum were removed, a
nitrogen sparge was placed in the vessel and nitrogen bubbled through the
mixture at 200 ml min-1. The temperature was ramped to 110 C following the
profile and then the mixture was held at 110 C for 3 hours. The stirrer was
turned down to 240 rpm at 110 C because the mixture became much thinner.
Finally the heating was stopped, the funnel to the trap raised out of the
solution, the mixture air-cooled to below 60 C (raising the sparge out of the
solution at 85 C) and the nitrogen flow stopped. It was left standing
overnight.
pay 2:
Nitrogen sparge and stirring were restarted as before. The viscous mixture
was heated gently until mechanical stirring could be switched on. The prep
was then heated to 110 C in 40 minutes. At 110 C decene was added (17%
of estimated sulphurized DDP) and the mixture was heated to 175 C in a
further 50 minutes.
CA 02602770 2007-09-18
33
The prep was held at 175 C for up to 6 hours until the required UV ratio (see
below) was reached and then the heating was switched off but stirring and
nitrogen were continued until the prep had cooled below 60 C. The prep was
then switched off.
UV ratio: The UV ratio of absorbances at 291:325 nm was measured on
sulphurized DDP samples to determine the extent of polysulphide breakdown
from the initial reaction. The peak at 325 nm was expected to diminish during
a successful desulphurization to produce a final ratio exceeding 3Ø
_
Day 31
The caustic trap was removed and the flask set up for distillation. Nitrogen
blanket and stirring were started and the prep heated to 175 C using the
same profile as in Day 2. The mixture was much thinner that on day 2 due to
the decene addition and stirring could be started immediately. At 175 C high
vacuum was applied and held for 2 hours. At the end of 2 hours the heating
was switched off and the prep cooled to below 60 C under vacuum with
stirring and nitrogen still on. Once below 60 C the prep was switched off.
In the case of A (see Table below) the sulphurized DDP was then used as
such. In the case of B (see Table below) the product obtained was blended
with SN 150 oil (14%) at 60 C for 1 hr.
CA 02602770 2007-09-18
= =
34
Synthesis of Overbased Phenates
Examples A (Phenate / Stearate) and B (Phenate / Su!phonate / Stearate)
Charges:
Mass (g)
Reactor Example A Example B
Toluene 695 632
Methanol 397 361
Water 26 24
Oil, SN 150 30 30
Sulphurized dodecylphenol 622
Sulphurized dodecylphenol 457
Alkylbenzene sulphonic acid 0 39
(Mol. Wt. approx. 660, active matter
83%)
Reactor Additions
Calcium hydroxide 212 195
Carbon dioxide 65 _ 66
Oil, SN 150 (second oil charge) 144 178
Stearic Acid 93 84
Centrifuge addition
Toluene (further toluene charge) 1072 431
Heating Profile:
Start Temp Final Temp Ramp Time Dwell Time
( C) ( C) (min.) (min.)
Ambient 40 10 2
40 28 10 2
28 60 60 2
60 65 15
65 70 90
70 75 15
75 110 50
110 120 15 Hold
Method:
The toluene, methanol, water and initial oil were weighed into a 2 litre
reaction
vessel. The vessel was set up for reflux and heated to 40 C using the above
heating profile. The mixture was stirred at 200 rpm. Calcium hydroxide was
added at 33 C. At 40 C stirring was increased to 400 rpm and the
sulphurized dodecylphenol (and alkylbenzene sulphonic acid, if required)
CA 02602770 2007-09-18
were run in over a period of approx. 25 minutes. The prep was then cooled
back to 28 C.
At 28 C carbonation was started at a rate of approx. 150 ml min-1.
Carbonation time was 180 minutes.
Heat soak: after carbonation the mixture was ramped from 28 C to 60 C
using the above profile. The stearic acid was added at 60 C at the end of the
heat soak. After adding the stearic acid the reaction vessel was rearranged
for distillation and a blanket of nitrogen was applied. The mixture was
stripped according to the above profile. The second oil charge was added at
120 C.
Centrifugation: The product was decanted into a 3 litre beaker and weighed.
A further toluene charge was added to the beaker and stirred. The mixture
was transferred into centrifuge cans and spun in a centrifuge at 2500 rpm for
30 min. After spinning the mixtures were decanted to be stripped on a rotary
evaporator.
Rotary Evaporator Strip: The oil bath was pre-heated to 160 C and was
maintained at this temperature 10 C. An empty 2 litre pear shaped flask
was placed on the rotovap, spun briskly and a vacuum of approx. 400 mbar
was applied. The supernatant liquid was then bled in slowly over approx. 40
min. and the solvent allowed to flash off. After all the mixture had been
added the vacuum was increased to full vacuum and maintained for 1 hour.
After 1 hour the vacuum was released and the product was cooled.
CA 02602770 2013-09-25
36
The overbased detergent produced had the following characteristics:
Example A Example B Comparative
Example-
OLOA 219*
TBN 258 258..250
Unsulphurized 5.58 3.84 6.15
alkyl phenol and
its
unsulphurized
calcium salt,
mass%
* OLOA 219TM is a commercially available 250 BN calcium phenate.
The detergents in the table above were tested for their rates of
neutralization
using the following test method:
Acid Neutralisation Rig Method
A 100m1 two neck round bottom flask was fitted with a digital manometer
(Digitron TM model 2083) and an injection port consisting of a glass tap and
quick fit adapter. The flask was charged with 30 g of sample (to 0.1mg) and a
magnetic stirrer added. The flask was placed in an oil bath at 40 C 1 C and
the sample was allowed to reach equilibrium. 0.182 g of 18M sulphuric acid
was charged to a syringe and injected into the flask via the injection port
and
the pressure of the CO2 gas evolved was recorded as a function of time. The
results are shown in the table below and also in the attached graph.
The amount of dodecyl phenol (DDP) and its calcium salt was measured as
follows:
CA 02602770 2013-09-25
37
Method for Analysis of (Ca) DDP content
The determination of dodecyl phenol (DDP) and its calcium salt content was
done by reverse phase HPLC using a u.v. detector. Alkylphenol species were
differently eluted within ten minutes. The remaining sample impurities were
washed out from the column with pure methanol. A series of four calibration
standards were prepared by dissolving known amounts of reference DDP in
the mobile phase (84% methanol-16% water), concentrations were selected
according to the most appropriate range of detector response factor and
linearity. Analyses of test specimens were carried out within the calibration
range of response. About 0.3g of sample solution was dissolved in about 3g
of dichloromethane (AR grade). The solution was gently agitated. A 20m1
volumetric flask was half filled with the mobile phase and into this, about
2.6g
of the dichloromethane solution was directly weighed (to nearest 0,1mg). The
sample was homogenised by agitation or by sonication in a water bath for 2
minutes. The flask was diluted to volume with mobile phase and then, by
means of a 5 mL plastic syringe and a 0.45 pm disposable cellulose acetate
filter, the sample was filtered directly into the HPLC vial. The sample and
calibration solutions were chromotographed using the HPLC conditions
below. Integration of the peaks was carried out between 4 and 9 minutes, the
baseline being flat (the slope being less than 5%) with no drift of the u.v.
detector. The reference point for the baseline was taken at 9 minutes. A
linear calibration curve was generated by plotting the integrated areas of the
standards against the amount of DDP used to prepare the standards. This
calibration curve was used to determine the content of DDP and its calcium
salt by combined mass% in the sample.
The HPLC was run with the following conditions:
Column: C8(2) 150 mm X 4,6 mm, 5 pm particles size (Luna 100A
PhenomexTm column or equivalent);
Flow rate: 1.2 rnL/min;
Mobile phase: methanol 84% and water 16%;
Typical injection volume: 5 pl;
CA 02602770 2007-09-18
.
38
Total run time: 38 min;
0 - 10 min 84% methanol ¨ 16% water;
10.10 ¨ 20.00 min 100% methanol (column wash);
20.10 ¨ 38.00 min 84% methanol ¨ 16% water;
Temperature of the column compartment: 40 C;
UV detector settings: Wavelength: 230 nm (reference at 360 nm for DAD
systems).
Example 1 Example 2 Example 3
Comparative
Example 4
Example A 8.00 16.00
Example B 16.00
OLOA 219 16.00
425 BN 7.10 7.10 7.10 7.10
Calcium
Sulphonate,
Infineum
M7117
ExxonMobil 64.90 56.90 56.90 56.90
SN600
ExxonMobil 20.00 20.00 20.00 20.00
BS 2500
TBN 50 70 70 70
VK @ 40 C 180.2 196.6 211.8 209.7
CA 02602770 2013-09-25
39
Acid Neutralization Testing, CO2 pressure changes
Time, minutes Example 1 Example 2 Example 3 Comparative
Example 4
0 0 - 0 0 0
1 28.0 26.5
27.0 10.8
2 35.0 29.8 274 12.5
L-
3 38.7 32.0 29.2 13.3
4 41.7_
34.3 31.0 13.5
_________________________ õ._.
45,0 36.0 32.0 13.5
6 ' 47.0 37.0 33.0 13.8
7 49.0 ' 38.3 33.8 13.8
8 50.3 39.8 35.0 14.0
9 51.7 41.0 35.4 14.3
53.2 41.8 35.6 14.3 '
-
11 537 42.3 35.8 14.5
12 54.3 42.5 362 14.0
13 55.7 42,8 36.4 14.5
14 56.7 42.5 36.0 14.3-
57.0 43.5 36.0 14.5 '
______________________________________________________________ ---,
16 56.7 43.8 36.0 14.0
17 57.3 44.5 36.0 14.0
_ __
18 57.7 44.0 35.8 13.8
_ __
19 57.7 43.8 35.8 1:4-.0 '
_________________________________________________ _ __________
57.7 43.8 35.8 14.3 '
____ _ __ .,..
Figure 1 is a graphical view of the above results.
The results above show that the use of an overbased sulphurized metal
phenate including less than 6.0% by mass of unsulphurized C9-C15 alkyl
phenol and its unsulphurized metal salt unexpectedly produces a higher rate
of acid neutralization than the use of an overbased sulphurized metal phenate
including more than 6.0% by mass of unsulphurized C9-C15 alkyl phenol and
its unsulphurized metal salt.
