Note: Descriptions are shown in the official language in which they were submitted.
LA/1-23562/P1/CGC 2259 CA 02567235 2006-11-07
METHACRYLATE COPOLYMER POUR POINT DEPRESSANTS
TECHNICAL FIELD
This invention relates to polyalkyl methacrylate copolymers having excellent
low
temperature properties. The present invention also relates to the use of these
copolymers as pour point depressants or viscosity improvers at low
temperatures for
lubricating oils.
BACKGROUND OF THE INVENTION
Polymethacrylate pour point depressants are well known in the lubricating
industry.
Many attempts have been made to produce polymethacrylate pour point
depressants
that improve the low temperature viscometrics of various lubricating
compositions.
Pour point depressants (PPD) additives improve the low-temperature performance
of an
oil by modifying the wax crystallization process. A wide variety of chemical
types are
currently available, and include polyalkylmethacrylates, styrenated
polyesters, alkylated
polystyrenes, ethylene-vinyl acetate, vinyl acetate-fumarate, esterified
olefinic, styrene
maleic anhydride, and alkylated naphthalenes. The present invention is
directed to alkyl
methacrylate polymers which exhibit desired low temperature properties. More
specifically, the invention is directed to PPDs that exhibit outstanding low
temperature
properties in lubricating oils for applications such as automatic transmission
fluids,
manual transmission fluids, hydraulic fluids, greases, gear fluids, metal-
working fluids,
engine oil applications, crankcase motor oil and shock absorber fluids. The
oil chemist is
constantly searching for PPDs that achieve optimum low-temperature performance
at
low concentrations. The present invention addresses the need for an improved
PPD.
In particular, the invention addresses the need for a pour point depressant
which can be
used in a variety of oils at lower treat rates, displays less interactions
with other
components of the oil such as dispersants and inhibitors, shows stability in
shear fields
and lower gelation indices in some instances depending on the base oil than
for previous
pour point polyalkylmethacrylates. It is important that the PPD be soluble and
compatible
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CA 02567235 2006-11-07
with the base oil and maintain an appropriate scanning BROOKFIELD viscosity at
low
temperatures.
U.S. Patent No. 2,655,479 to Munday et al. claims a pour point depressant
composition
consisting of a blend of two copolymers, the first copolymer having an average
side
chain length of about 12.7 while the second copolymer has an average side
chain length
of about 11.2.
U.K. Patent No. 1,559,952 discloses a mixture of two classes of oil soluble
polyalkyl
(meth)acrylates as pour point depressants.
U.S. Patent No. 4,146,492 discloses lubricating oil compositions comprising
between
about 0.5 and 30 wt. % of a specifically defined ethylene-propylene copolymer
and
between about 0.005 to 10 wt. % of a neat interpolymeric polyalkylacrylate of
(A) Cl -
C15 alkylacrylate and (B) C 16 -C22 alkylacrylate having a weight ratio of A:
B of between
about 90:10 and 50:50, a molecular weight of from 1000 to 25,000 and an
average alkyl
side chain length of between about 11 and 16 carbons.
U.S. Patent No. 4,867,894 discloses pour point improving additives for mineral
oils
comprising from 10 to 30 mole percent methyl methacrylate, 10 to 70 mole
percent of a
linear C16 to C30 alkyl methacrylate, from 10 to 80 mole percent of a C4-C15
linear alkyl
methacrylate and/or a C4 to C40 branched methacrylate, and from 0 to 30 mole
percent
of a free-radically polymerizable nitrogen-containing monomer having
dispersing action.
U.S. Patent Nos. 5,312,884 and 5,368,761 disclose copolymers useful as pour
point
depressants for lubricating oils comprising 15-67 mole percent C8-C15 alkyl
(meth)
acrylates, 3-40 mole percent C16-C24 (meth) acrylates, and from greater than
30-65
mole percent C1-C4 methacrylates. These patents do not teach copolymers
containing
the specific monomers in the specific proportions required by the present
claims.
U.S. Patent No. 5,281,329 discloses copolymers useful as pour point
depressants for
oils containing at least two species of poly alkyl (meth)acrylate, one species
having an
onset of crystallization temperature above 15 C and one species having an
onset of
crystallization temperature below 15 C.
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CA 02567235 2006-11-07
U.S. Patent No. 5,534,175 discloses copolymers of unsaturated fatty esters
derived from
12-20 mass % of a C1-C3 (meth) acrylate, 45-72 mass % of a C11-C15 (meth)
acrylate
and 14-30 mass % of a C16-C25 (meth) acrylate.
EP 0 236 844 B1 teaches pour point improving agents derived from methyl
methacrylate.
U.S. Patent No. 6,255,261 discloses copolymers formed from 5 to 60 weight
percent
C11-C15 (meth) acrylates and 95 to 40 weight % C16-C30 (meth) acrylates for
use as
pour point depressants.
SUMMARY OF THE INVENTION
The present invention is directed to polyalkyl methacrylates and their use as
pour point
depressants for lubricating oils.
The polyalkyi methacrylate copolymers of the present invention comprise units
derived
from:
(A) about 60 to about 96, weight percent of a C12-C16 alkyl methacrylate; and
(B) about 40 to about 4, weight percent of a C18-C30 alkyl methacrylate.
The poly alkyl methacrylate copolymer may be crosslinked or structured.
Addition of the poly alkyl methacrylate copolymer derived as above is added to
an oil of
lubricating viscosity to form a lubricating oil composition.
Furthermore the composition above is used to improve the low temperature
properties of
a lubricating oil.
DESCRIPTION OF THE DRAWINGS
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Figure 1 illustrates pour point temperature as a function of concentration for
the poly
alkyl methacrylate of example 1 in an hydraulic oil compared to a commercial
pour point
depressant.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to polyalkyl methacrylate copolymers
comprising units
derived from:
(A) about 60 to about 96, weight percent of a C12-C16 alkyl meth acrylate; and
(B) about 40 to about 4, weight percent of a C18-C30 alkyl meth acrylate.
Molecular Weight
The copolymers of the present invention have a relative weight average
molecular
weight ranging from about 5,000 to about 250,000. Typically, the weight
average may
range from about 10,000 to about 200,000, from about 15,000 to about 150,000
and
most typically from about 20,000 to about 130,000. The molecular weight
distribution is
usually less than 2.5 and generally ranges from about 1.5 to about 2.5.
Crosslinked or Structured Copolymer
The poly alkyl methacrylate copolymer may be crosslinked, structured or
branched.
Cross linking agents are usually polyethylenically unsaturated crosslinking
agents.
Examples are methylene bis(meth)acrylamide, polyethyleneglycol diacrylate;
polyethyleneglycol dimethacrylate; N-vinyl acrylamide; divinylbenzene; tetra
(ethyleneglycol) diacrylate; diallyloctylamide; trimethyllpropane ethoxylate
triacryalte; N-
allylacrylamide N-methylallylacrylamide, pentaerythritol triacrylate and
combinations
thereof. Other systems for crosslinking can be used instead of or in addition
to this. For
instance covalent crosslinking through pendant groups can be achieved, for
instance by
the use of ethylenically unsaturated epoxy monomers, or by the use of
polyfunctional
crosslinking agents other known crosslinking systems.
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Variation in components (A) and (B)
The component (A) may for example, vary from about 65 to about 95 weight
percent or
about 70 to about 95, about 80 to about 95, about 85 to about 95, about 88 to
about 95
weight percent of the formed poly alkyl methacrylate copolymer.
The component (B) may for example, vary from about 35 to about 5 weight
percent, or
about 30 to about 5, about 20 to about 5, about 15 to about 5, about 12 to
about 5
weight percent of the formed poly alkyl methacrylate copolymer.
For purposes of the invention, weight percent of components (A) and (B) of the
formed
alkyl methacrylate is calculated by taking total weight of component (A) or
(B) over the
total weight of the formed polyalkyl methacrylate copolymer multiplied by 100.
For
example, if component (A) weighs 80 g and the formed copolymer weighs 100g,
then
component (A) makes up 80 percent by weight of the formed copolymer. The basis
weight of the formed copolymer is the copolymer per se and does not include
the diluent.
Component (A)
As used herein, C12-C16 alkyl methacrylate means an alkyl ester of methacrylic
acid
having a straight or branched ester alkyl group of 12 to 16 carbon atoms per
group such
as, lauryl methacrylate, myristyl methacrylate, cetyl methacrylate, dodecyl
methacrylate,
tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate,
hexadecyl
methacrylate and mixtures thereof. The preferred source for the C12-C16 alkyl
methacrylate esters is lauryl methacrylate which contains a mixture of
methacrylate
esters formed from a mixture of C12 to C16 alcohols. For example, about 60 to
about
96 weight percent lauryl methacrylate esters, about 65 to about 95 weight
percent lauryl
methacrylate esters make up the formed poly methacrylate copolymer.
Alternatively, the
weight percent lauryl methacrylate esters may vary as described above for
component
(A).
CA 02567235 2006-11-07
In the instance where lauryl methacrylate esters are used to make up component
(A) of
the polyalkyl methacrylate copolymers, the lauryl ester is derived from a
straight or
branched distribution of C12-C16 long chain alcohols. The weight percent
compositions
of the lauryl methacrylate esters may range as below:
Lauryl methacrylate Distribution
Chain length Wt. %
C12 68 -74
C14 20 -26
C16 2-6
The weight percent of the various homologues in the lauryl methacrylate means
weight
percent on the basis of the total weight of the lauryl methacrylate fraction.
Thus if the
total lauryl methacrylate fraction is 100g and the C12 contribution is 68 g
then the weight
percent of the C12 is 68 weight % of the total lauryl methacrylate fraction.
It is preferable that component (A) is substantially linear.
Furthermore, it is preferred that the C12-C16 esters contain only even ester
chain
lengths (C12, C14 and C16) but even and odd ester chain lengths (C12, C13,
C14, C15
and C16) are also possible. In the case where only even chain lengths are
used, the
component (A) contains only C12, C14 and C16 esters.
Thus (A) may consist essentially of about 60 to about 96 weight percent C12,
C14 and
C16 alkyl methacrylates.
"Consists essentially of' for the purposes of the invention means that minor
levels of
other monomers, polymerizable with the alkyl methacrylates may be present as
long as
they do not adversely affect the low temperature properties of the fully
formulated fluids.
Component (B)
As used herein, C18-C30 alkyl methacrylate means an alkyl ester of methacrylic
acid
having a straight or branched alkyl group of 18 to 30 carbon atoms per group
such as,
stearyl methacrylate, octadecyl methacrylate, heptadecyl methacrylate,
nonadecyl meth
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acrylate, eicosyl methacrylate, henicosyl methacrylate, docosyl methacrylate,
tricosyl
methacrylate, tetracosylmethacrylate, pentacosyl methacrylate, hexacosyl
methacrylate,
hexacosyl methacryalte, octacosyl methacrylate, nonacosyl methacrylate,
triacontyl
methacrylate, behenyl methacrylate and mixture thereof.
A typical source for the C18-C30 alkyl methacrylate esters is behenyl
methacrylate
esters. Behenyl methacrylate contains a range of long chain methacrylate
esters
wherein the length of the ester chain ranges from C18 to C22. For example,
about 40 to
about 4 weight percent of the behenyl methacrylate esters make up the formed
poly
alkylmethacrylate copolymer. For example, 35 to about 5 weight percent, about
30 to
about 5, about 20 to about 5, about 15 to about 5 or about 12 to about 5 of
the formed
poly alkyl methacrylate copolymer is formed from behenyl methacrylate esters .
In the instance where behenyl methacrylate esters are used to make up
component (B)
of the poly alkyl methacrylate copolymers, the behenyl esters may be derived
from a
C18-C22 distribution of long chain alcohols. The weight percent compositions
of the
behenyl methacrylate esters may range as below:
Behenyl Methacrylate Distribution
Chain length Wt. %
C18 40-50
C20 5 - 15
C22 40 -50
When referring to distribution by weight percent of the particular ester in
the behenyl
methacrylate, the weight percent is based on the total weight of behenyl
methacrylate.
Thus behenyl methacrylate may consist essentially of about 40 to about 50,
preferably
42 to about 48 weight percent C18 alkylmethacrylate, about 5 to about 15,
preferably 6.5
to about 12 weight percent C20 alkyl methacrylate and about 40 to about 50,
preferably
42 to about 48 weight percent C22 alkyl methacrylate based on the total weight
of
behenyl methacrylate.
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The behenyl methacrylate is substantially linear and contains substantially
only C18 to
C22 alkyl methacrylates.
The C16 and C18 fractions of alkyl methacrylates cummulative weight percent in
the
formed copolymer generally will not exceed about 22 to 23 % weight percent.
For
example, the combined weight percent of the C16 and C18 fractions may be about
15,
16, 17, 18, 19 or 21 weight percent of the formed alkyl methacrylate from
components
(A) and (B) with a minimum of at least 7, 8 or 9 weight percent for the
cumulative weight
percent of C16 and C18 fractions. For example, the (A) and (B) components are
further
defined as comprising a combined weight percent of C16 and C18 fractions which
combined fractions range from about a minimum of 7 weight percent to about a
maximum of 23 weight percent based on the total weight of the poly
methacrylate
copolymer.
Furthermore, the alkyl methacrylates esters in component (B) which are equal
to or
greater than C20 makes up at least about 2 to about 22 weight percent of the
formed
poly alkyl meth acrylate copolymer. For example, about 2.5, 3, 3.5, 4, 4.5, 5,
6, 7 or 8
weight percent of the formed poly alkyl methacrylate copolymer is derived from
C20 to
C30 alkyl methacrylates esters. The formed poly alkyl methacrylate copolymer
contains
a maximum of about 15, 16, 17, 18, 19, 20 or 22 weight percent of C20 to C30
alkyl
methacrylate esters.
Thus, the (B) components are further defined as comprising a combined weight
percent
of C20 to C30 fractions which fractions range from about a minimum of 2 weight
percent
to about a maximum of about 22 weight percent based on the total weight of the
poly
alkyl methacrylate copolymer.
The C20-C24 homologues are preferred and the C20- C22 homologues are the most
preferred homolog fractions of component (B). Thus for example, the C20-C22
homologues may make up about 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or 8
weight
percent of the formed poly alkyl methacrylate copolymer or as much as about 22
weight
percent.
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In a preferred embodiment the sum of (A) and (B) equals 100 weight percent of
the
formed poly alkyl methacrylate copolymer.
The poly methacrylate PPD copolymers according to the invention may or may not
contain C1-C10 alkyl methacrylates esters, or other polymerizable non-alkyl
methacrylate monomers.
Preparation of Poly Alkyl Methacrylate PPD Copolymers
The alkyl methacrylate comonomers containing 12 or more carbon atoms in the
alkyl
ester group are generally prepared by standard esterification procedures using
technical
grades of long chain aliphatic alcohols. These commercially available alcohols
are
mixtures of alcohols of varying chain lengths containing between 12 and 30
carbon
atoms in the alkyl groups. Consequently, for the purposes of this invention,
alkyl meth
acrylate comonomers are intended to include not only the individual alkyl
methacrylate
esters named, but also to include mixtures of the alkyl methacrylate esters.
Conventional methods of free-radical polymerization can be used to prepare the
copolymers of the present invention. Polymerization of the acrylic
methacrylate
monomers can take place under a variety of conditions, including bulk
polymerization,
solution polymerization, usually in an organic solvent, preferably mineral
oil.
In the solution polymerization, the reaction mixture comprises a diluent, the
alkyl meth
acrylate monomers, a polymerization initiator and usually a chain transfer
agent and
optionally a crosslinker.
The diluent may be any inert hydrocarbon. The ratio of diluent to total
monomer charge
may range from about 2:1 to about 0.6:2.0 For example a ratio of about 0.8:2.0
or 1:1.4
is normal. As used herein, "total monomer charge" means the combined amount of
all
monomers in the initial, i.e., unreacted, reaction mixture.
In preparing the copolymers of the present invention by free-radical
polymerization the
meth acrylic monomers may be polymerized simultaneously or sequentially or the
monomers may be fed over time to the reaction vessel. For example, the blend
of C12 to
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CA 02567235 2006-11-07
C30 alkyl methacrylate monomers may be fed over time to a reaction vessel
along with
an initiator feed.
Suitable polymerization initiators include initiators which disassociate upon
heating to
yield a free radical, e.g., peroxide compounds such as benzoyl peroxide, t-
butyl
perbenzoate, t-butyl peroctoate and cumene hydroperoxide; and azo compounds
such
as azoisobutyronitrile and 2,2'-azobis (2-methylbutanenitrile). The mixture
includes from
about 0.01 wt % to about 5.0 wt % initiator relative to the total monomer
mixture. For
example, 0.02 wt. % to about 4.0 wt. %, 0.02 wt. % to about 3.5 wt. % are
envisioned.
Typically about 0.02 wt. % to about 2.0 wt. % are used.
Suitable chain transfer agents include those conventional in the art such as
mercaptanes
and alcohols. For example, dodecyl mercaptan and ethyl mercaptan may be used
as
chain transfer agents. The selection of the amount of chain transfer agent to
be used is
based on the desired molecular weight of the polymer being synthesized as well
as the
desired level of shear stability for the polymer, i.e., if a more shear stable
polymer is
desired, more chain transfer agent can be added to the reaction mixture. The
chain
transfer agent is added to the reaction mixture or monomer feed in an amount
of 0.01 to
3 weight percent relative to the monomer mixture.
By way of example and without limitation, the reaction mixture is charged to a
reaction
vessel that is equipped with a stirrer, a thermometer and a reflux condenser
and heated
with stirring under a nitrogen blanket to a temperature from about 50 C to
about
125 C for a period of about 0.5 hours to about 15 hours to carry out the
polymerization
reaction.
A viscous solution of the copolymer of the present invention in the diluent is
obtained as
the product of the above-described process.
To form the lubricating oils of the present invention, a base oil is treated
with the
copolymer of the invention in a conventional manner, i.e., by adding the
copolymer to the
base oil to provide a lubricating oil composition having the desired low
temperature
properties. The lubricating oil contains from about 0.01 to about 5.0 parts by
weight, for
example about 0.01 to about 2.0, more typically about 0.02 to about 0.5, of
the neat
CA 02567235 2006-11-07
copolymer (i.e., excluding diluent oil) per 100 weight of base oil. The
preferred dosage
will of course depend upon the base oil.
In a particularly preferred embodiment, the copolymer is added to the base oil
in the
form of a relatively concentrated solution of the copolymer in a diluent, The
diluent oil
may be any of the oils referred to below that are suitable for use as base
oils.
Base Oils
Preferred base oils contemplated for use in this invention include mineral
oils, poly-
alpha-olefin synthetic oils and mixtures thereof. Suitable base oils also
include
basestocks obtained by isomerization of synthetic wax and slack wax, as well
as
basestocks produced by hydrocracking (rather than solvent extracting) the
aromatic and
polar components of the crude. In general, both the mineral and synthetic base
oils will
each have a kinematic viscosity ranging from about 1 to about 40 cSt at 100
C.,
although typical applications will require each oil to have a viscosity
ranging from about 2
to about 20 cSt at 100 C.
The mineral oils useful in this invention include all common mineral oil base
stocks. This
would include oils that are naphthenic, paraffinic or aromatic in chemical
structure.
Naphthenic oils are made up of methylene groups arranged in ring formation
with
paraffinic side chains attached to the rings. The pour point is generally
lower than the
pour point for paraffinic oils. Paraffinic oils comprise saturated, straight
chain or
branched hydrocarbons. The straight chain paraffins of high molecular weight
raise the
pour point of oils and are often removed by dewaxing. Aromatic oils are
hydrocarbons of
closed carbon rings of a semi-unsaturated character and may have attached side
chains. This oil is more easily degraded than paraffinic and naphthalenic oils
leading to
corrosive by-products.
In reality a base stock will normally contain a chemical composition which
contains some
proportion of all three (paraffinic, naphthenic and aromatic). For a
discussion of types of
base stocks, see Motor Oils and Engine Lubrication by A. Schilling, Scientific
Publications, 1968, section 2.2 thru 2.5.
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The poly methacrylate copolymer may be used in paraffinic, naphthenic and
aromatic
type oils. For example, the poly methacrylate copolymer may be used in Groups
I-V
base oils. These Groups are well known by the art skilled. Additionally, the
poly
methacrylate copolymer may be used in gas to liquid oils
Oils may be refined by conventional methodology using acid, alkali, and clay
or other
agents such as aluminum chloride, or they may be extracted oils produced, for
example,
by solvent extraction with solvents such as phenol, sulfur dioxide, furfural,
dichlordiethyl
ether, etc. They may be hydrotreated or hydrorefined, dewaxed by chilling or
catalytic
dewaxing processes, or hydrocracked. The mineral oil may be produced from
natural
crude sources or be composed of isomerized wax materials or residues of other
refining
processes. The preferred synthetic oils are oligomers of a-olefins,
particularly oligomers
of 1-decene, also known as poly-alphaolefins or PAO's.
The base oils may be derived from refined, re-refined oils, or mixtures
thereof. Unrefined
oils are obtained directly from a natural source or synthetic source (e.g.,
coal, shale, or
tar sands bitumen) without further purification or treatment. Examples of
unrefined oils
include a shale oil obtained directly from a retorting operation, a petroleum
oil obtained
directly from distillation, or an ester oil obtained directly from an
esterification process,
each of which is then used without further treatment. Refined oils are similar
to the
unrefined oils except that refined oils have been treated in one or more
purification steps
to improve one or more properties. Suitable purification techniques include
distillation,
hydrotreating, dewaxing, solvent extraction, acid or base extraction,
filtration, and
percolation, all of which are known to those skilled in the art. Re-refined
oils are obtained
by treating used oils in processes similar to those used to obtain the refined
oils. These
re-refined oils are also known as reclaimed or reprocessed oils and are often
additionally
processed by techniques for removal of spent additives and oils breakdown
products.
Optional Customary Oil Additives
The addition of at least one additional customary oil additive to the
composition is
possible. The mentioned lubricant compositions, e.g. greases, gear fluids,
metal-working
fluids and hydraulic fluids, may additionally comprise further additives that
are added in
order to improve their basic properties still further. Such additives include:
further
antioxidants, metal passivators, rust inhibitors, viscosity index enhancers,
additional
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pour-point depressants, dispersants, detergents, further extreme-pressure
additives and
anti-wear additives. Such additives are added in the amounts customary for
each of
them, which range in each case approximately from 0.01 to 10.0%, preferably
0.1 to
1.0%, by weight. Examples of further additives are given below:
1. Examples of Phenolic Antioxidants:
1.1. Alkylated monophenols: 2,6-di-tert-butyl-4-methylphenol, 2-butyl-4,6-
dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-
butylphenol, 2,6-di-
tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(.alpha.-
methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-
tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, linear
nonylphenols or
nonylphenols branched in the side chain, such as, for example, 2,6-dinonyl-4-
methylphenol, 2,4-dimethyl-6-(1'-methyl-undec-1'-yl)-phenol, 2,4-dimethyl-6-
(1'-
methylheptadec-1'-yl)-phenol, 2,4-dimethyl-6-(1'-methyltridec-1'-yl)-phenol
and mixtures
thereof;
1.2. Alkylthiomethylphenols: 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-
dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-
didodecylthiomethyl-4-nonylphenol;
1.3. Hydroquinones and alkylated hydroquinones: 2,6-di-tert-butyl-4-
methoxyphenol, 2,5-
di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-
octadecyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-
hydroxyanisole,
3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl
stearate, bis (3,5-di-
tert-butyl-4-hydroxyphenyl) adipate;
1.4. Tocopherols: alpha.-, .beta.-, gamma. or .delta.-tocopherol and mixtures
thereof
(vitamin E);
1.5. Hydroxylated thiodiphenyl ethers: 2,2'-thio-bis(6-tert-butyl-4-
methylphenol), 2,2'-thio-
bis (4-octylphenol), 4,4'-thio-bis(6-tert-butyl-3-methylphenol), 4,4'-thio-
bis(6-tert-butyl-2-
methylphenol), 4,4'-thio-bis(3,6-di-sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-
hydroxy-
phenyl)disulfide;
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1.6. Alkylidene bisphenols: 2,2'-methylene-bis (6-tert-butyl4-methylphenol),
2,2'-
methylene-bis (6-tert-butyl-4-ethylphenol), 2,2'-methylene-bis [4-methyl-6-(.
alpha.-
methylcyclohexyl) phenol], 2,2'-methylene-bis (4-methyl-6-cyclohexylphenol),
2,2'-
methylene-bis (6-nonyl-4-methylphenol), 2,2'-methylene-bis (4,6-di-tert-
butylphenol),
2,2'-ethylidene-bis(4,6-di-tert-butylphenol), 2,2'-ethylidene-bis(6-tert-butyl-
4-
isobutylphenol), 2,2'-methylene-bis[6-(.alpha.-methylbenzyl)-4-nonylphenol],
2,2'-
methylene-bis[6-(.alpha.,.alpha.-dimethyl-benzyl)-4-nonylphenol], 4,4'-
methylene-bis(2,6-
di-tert-butylphenol), 4,4'-methylene-bis(6-tert-butyl-2-methylphenol), 1,1-
bis(5-tert-butyl-
4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-
hydroxybenzyl)-4-
methylphenol, 1, 1, 3-tris(5-tert-butyl-4-hyd roxy-2-methyl phenyl) butane,
1,1-bis(5-tert-
butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol
bis[3,3-
bis(3'-tert-butyl-4'-hydroxyphenyl)-butyrate], bis(3-tert-butyl-4-hydroxy-5-
methylphenyl)dicyclopentadiene, bis[2-(3'-tert-butyl-2'-hydroxy-5'-
methylbenzyl)-6-tert-
butyl-4-methylphen yl]terephthalate, 1,1-bis(3,5-dimethyl-2-
hydroxyphenyl)butane, 2,2-
bis(3,5-di-tert-butyl-4-hydroxyphenyl)-propane, 2,2-bis(5-tert-butyl-4-hydroxy-
2-
methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra(5-tert-butyl-4-hydroxy-
2-
methylphenyl)pentane;
1.7. 0-. N- and S-benzyl compounds: 3,5,3',5'-tetra-tert-butyl-4,4'-
dihydroxydibenzyl
ether, octadecyl-4-hydroxy-3,5-dimethylbenzyl-mercaptoacetate, tridecyl-4-
hydroxy-3,5-
di-tert-butylbenzyl-mercaptoacetate, tris (3,5-di-tert-butyl-4-
hydroxybenzyl)amine, bis(4-
tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3,5-di-tert-
butyl-4-
hydroxybenzyl)sulfide, isooctyl-3,5-di-tert-butyl-4-hydroxybenzyl-
mercaptoacetate;
1.8. Hydroxybenzylated malonates: dioctadecyl-2,2-bis(3,5-di-tert-butyl-2-
hydroxybenzyl)malonate, dioctadecyl-2-(3-tert-butyl-4-hydroxy-5-
methylbenzyl)malonate,
didodecyl-mercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl) malonate,
di[4-
(1,1,3,3-tetramethylbutyl)-phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydrox
ybenzyl)malonate;
1.9. Hydroxybenzyl aromatic compounds: 1,3,5-tris(3,5-di-tert-butyl-4-
hydroxybenzyl)-
2,4,6-tri m ethyl benzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-
tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) phenol;
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1.10. Triazine compounds: 2,4-bis-octylmercapto-6-(3,5-di-tert-butyl-4-
hydroxyanilino)-
1,3,5-triazin e, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-
1,3,5-triazine ,
2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine ,
2,4,6-tris(3,5-
di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris (3,5-di-tert-butyl-
4-
hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-
dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4-
hydroxyphenylethyl)-1,3,5-
triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexahydro-
1,3,5-tria zine,
1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate;
1.11. Acylaminophenols: 4-hydroxylauric acid anilide, 4-hydroxystearic acid
anilide, N-
(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamic acid octyl ester;
1.12. Esters of.beta.-(5-tert-butyl-4-hydroxy-3-methylphenyl) propionic acid:
with
polyhydric alcohols, e.g. with 1,6-hexanediol, 1,9-nonanediol, ethylene
glycol, 1,2-
propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol,
triethylene glycol,
pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'-bis (hydroxyethyl)
oxalic acid
diamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,
trimethylolpropane,
4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane;
1.1 3. Esters of.beta.-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid,
.gamma.-(3,5-
dicyclohexyl-4-hydroxyphenyl) propionic acid, 3,5-di-tert-butyl-4-
hydroxyphenylacetic
acid: with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-
octanol,
isooctanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-
propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol,
triethylene glycol,
pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'-bis-hydroxyethyl oxalic
acid diamide,
3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethyfolpropane,
4-
hydroxymethyl-1 -phospha-2,6,7-trioxabicyclo[2.2.2]octane;
1.14. Amides of.beta.-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid: N,N'-
bis (3,5-di-
tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamine, N,N'-bis(3,5-di-tert-
butyl-4-
hydroxyphenylpropionyl)trimethylenediamine, N,N'-bis(3,5-di-tert-butyl-4-
hydroxyphenylpropionyl)hydrazine;
CA 02567235 2006-11-07
1.15. Ascorbic acid (vitamin C);
1.1 6. Aminic antioxidants: N,N'-diisopropyl-p-phenylenediamine, N,N'-di-sec-
butyl-p-
phenylenediamine, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N'-bis(1-
ethyl-3-
methylpentyl)-p-phenylenediamine, N,N'-bis(1-methylheptyl)-p-phenylenediamine,
N, N'dicyclohexyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N'-
di(naphth-2-yl)-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine,
N-(1,3-
dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-
phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, 4-(p-
toluenesulfonamido)-diphenylamine, N,N'-dimethyl-N,N'-di-sec-butyl-p-
phenylenediamine, diphenylamine, N-allyldiphenylamine, 4-
isopropoxydiphenylamine, 4-
n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-
dodecanoylaminophenol, 4-octadecanoylaminophenol, di(4-methoxyphenyl)amine,
2,6-
di-tert-butyl-4-dimethylaminomethyl phenol, 2,4'-diaminodiphenylmethane, 4,4'-
diaminodiphenylmethane, N, N, N', N'-tetramethyl-4,4'-diami nod
iphenylmethane, 1,2-di[(2-
methylphenyl)amino]-ethane, 1,2-di(phenylamino)propane, (o-tolyl)biguanide,
di[4-(1',3'-
dimethylbutyl)phenyl]amine, tert-octylated N-phenyl-l-naphthylamine, mixture
of mono-
and di-alkylated tert-butyl/tert-octyl-diphenylamines, mixture of mono- and di-
alkylated
nonyldiphenylamines, mixture of mono- and di-alkylated dodecyldiphenylamines,
mixture
of mono- and di-alkylated isopropyl/isohexyl-diphenylamines, mixtures of mono-
and di-
alkylated tert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-
benzothiazine,
phenothiazine, mixture of mono- and di-alkylated tert-butyl/tert-octyl-
phenothiazines,
mixtures of mono- and di-alkylated tert-octylphenothiazines, N-
allylphenothiazine,
N, N, N', N'-tetraphenyl-l,4-diaminobut-2-ene, N, N-bis(2,2,6,6-
tetramethylpiperidin-4-
yl)hexamethylenediamine, bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate,
2,2,6,6-
tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol.
2. Examples of further antioxidants: aliphatic or aromatic phosphites, esters
of
thiodipropionic acid or thiodiacetic acid or salts of dithiocarbamic acid,
2,2,12,12-
tetramethyl-5,9-dihydroxy-3,7,11-trithiatridecane and 2,2,15,15-tetramethyl-
5,12-
dihydroxy-3,7,10,14-tetrathiahexadecane.
3. Examples of Metal Deactivators. e.g. for Copper:
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3.1. Benzotriazoles and derivatives thereof: 2-mercaptobenzotriazole, 2,5-
dimercaptobenzotriazole, 4- or 5-alkylbenzotriazoles (e.g. tolutriazole) and
derivatives
thereof, 4,5,6,7-tetrahydrobenzotriazole, 5,5'-methylene-bis-benzotriazole;
Mannich
bases of benzotriazole ortolutriazole, such as 1-[di(2-ethylhexyl)
aminomethyl]tolutriazole and 1-[di(2-ethylhexyl)aminomethyl]benzotriazole;
alkoxyalkylbenzotriazoles, such as 1-(nonyloxy-methyl)benzotriazole, 1-(1-
butoxyethyl)-
benzotriazole and 1-(1-cyclohexyloxybutyl)-tolutriazole;
3.2. 1,2,4-Triazoles and derivatives thereof: 3-alkyl-(or -aryl-) 1,2,4-
triazoles, Mannich
bases of 1,2,4-triazoles, such as 1-[di(2-ethylhexyl)aminomethyl]-1,2,4-
triazole;
alkoxyalkyl-1,2,4-triazoles, such as 1-(1-butoxyethyl)-1,2,4-triazole;
acylated 3-amino-
1,2,4-triazoles;
3.3. Imidazole derivatives: 4,4'-methylene-bis(2-undecyl-5-methyl) imidazole
and bis [(N-
methyl)imidazol-2-yl]carbinol-octyl ether;
3.4. Sulfur-containing heterocyclic compounds: 2-mercaptobenzothiazole, 2,5-
dimercapto-1,3,4-thiadiazole, 2,5-dimercaptobenzothiadiazole and derivatives
thereof;
3,5-bis [di(2-ethylhexyl)aminomethyl]-1,3,4-thiadiazolin-2-one;
3.5. Amino compounds: salicylidene-propylenediamine, salicylaminoguanidine and
salts
thereof.
4. Examples of Rust Inhibitors:
4.1. Organic acids, their esters, metal salts, amine salts and anhydrides:
alkyl- and
alkenyisuccinic acids and their partial esters with alcohols, diols or
hydroxycarboxylic
acids, partial amides of alkyl- and alkenyl-succinic acids, 4-
nonylphenoxyacetic acid,
alkoxy- and alkoxyethoxy-carboxylic acids, such as dodecyloxyacetic acid,
dodecyloxy
(ethoxy) acetic acid and amine salts thereof, and also N-oleoyl-sarcosine,
sorbitan
monooleate, lead naphthenate, alkenylsuccinic acid anhydrides, e.g.
dodecenylsuccinic
acid anhydride, 2-(2-carboxyethyl)-1-dodecyl-3-methylglycerol and salts
thereof,
especially sodium and triethanolamine salts thereof.
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4.2. Nitrogen-containing Compounds:
4.2.1. Tertiary aliphatic or cycloaliphatic amines and amine salts of organic
and inorganic
acids, e.g. oil-soluble alkylammonium carboxylates, and 1-[N,N-bis(2-
hydroxyethyi)amino]-3-(4-nonylphenoxy)propan-2-ol;
4.2.2. Heterocyclic compounds: substituted imidazolines and oxazolines, e.g. 2-
heptadecenyl-1-(2-hydroxyethyl)-imidazoline;
4.2.3. Sulfur-containing compounds: barium dinonyinaphthalene sulfonates,
calcium
petroleum sulfonates, alkylthio-substituted aliphatic carboxylic acids, esters
of aliphatic
2-sulfocarboxylic acids and salts thereof.
5. Examples of viscosity index enhancers: polyacrylates, polymethacrylates,
nitrogen
containing polymethylmethacrylates, vinylpyrrolidone/methacrylate copolymers,
polyvinylpyrrolidones, polybutenes, polyisobutylenes, olefin copolymers such
as
ethylene-propylene copolymers, styrene-isoprene copolymers, hydrated styrene-
isoprene copolymers, styrene/acrylate copolymers and polyethers.
Multifunctional
viscosity improvers, which also have dispersant and/or antioxidancy properties
are
known and may optionally be used in addition to the products of this
invention.
6. Examples of pour-point depressants: polymethacrylates, ethylene/vinyl
acetate
copolymers, alkyl polystyrenes, fumarate copolymers, alkylated naphthalene
derivatives.
7. Examples of dispersants/surfactants: polybutenylsuccinic acid amides or
imides,
polybutenylphosphonic acid derivatives, basic magnesium, calcium and barium
sulfonates and phenolates.
8. Examples of extreme-pressure and anti-wear additives: sulfur- and halogen-
containing compounds, e.g. chlorinated paraffins, sulfurized olefins or
vegetable oils
(soybean oil, rape oil), alkyl- or aryl-di- or -tri-sulfides, benzotriazoles
or derivatives
thereof, such as bis (2-ethylhexyl) aminomethyl tolutriazoles,
dithiocarbamates, such as
methylene-bis-dibutyidithiocarbamate, derivatives of 2-mercaptobenzothiazole,
such as
1-[N,N-bis(2-ethylhexyl)aminomethyl]-2-mercapto-1 H-1,3-benzothiazole,
derivatives of
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2,5-dimercapto-1,3,4-thiadiazole, such as 2,5-bis(tert-nonyidithio)-1,3,4-
thiadiazole.
9 Examples of coefficient of friction reducers: lard oil, oleic acid, tallow,
rape oil,
sulfurized fats, amides, amines. Further examples are given in EP-A-0 565 487.
10. Examples of special additives for use in water/oil metal-working fluids
and hydraulic
fluids: Emulsifiers: petroleum sulfonates, amines, such as polyoxyethylated
fatty amines,
non-ionic surface-active substances; buffers: such as alkanolamines; biocides:
triazines,
thiazolinones, tris-nitromethane, morpholine, sodium pyridenethiol; processing
speed
improvers: calcium and barium sulfonates.
The inventive pour point depressant may be admixed with the above-mentioned
directly
in a lubricant. It is also possible to prepare a concentrate or a so-called
"additive pack",
which can be diluted to give the working concentrations for the intended
lubricant.
Lubricating oils containing the copolymers of the present invention may be
used in a
number of different applications including automatic transmission fluids,
manual
transmission fluids, hydraulic fluids, greases, gear fluids, metal-working
fluids, engine oil
applications and shock absorber fluids.
EXAMPLES
Example 1
Synthesis of Lauryl-Behenyl Methacrylate Copolymer- 90/10 Monomer Weight Ratio
140 g of high temperature oil (neutral hydrotreated oil) is charged to a
reactor and
heated to 95 C under nitrogen. T-butyl peroctoate, 0.406 g in 7.7 g of oil is
added to the
heated oil in the reactor. Two separate parallel feeds are setup for metering
into the
reactor. The first feed is made up of a mixture of 252.00 g of lauryl
methacrylates, 28
grams of behenyl methacrylate, 1.12 grams of dodecyl mercaptan (DDM) and
235.20
grams of high temperature oil and is metered over a 2 hour period. The second
feed
consists of 1.22 g t-butyl peroctoate in 23.14 g of oil and is fed over a 3
hour period. At
the end of 2 hours the feed rate, the second feed rate is doubled. The
reaction is held for
19
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an additional hour at 95 C after which an additional charge of initiator,
0.560 g in 10.64
g oil is added to the reaction and held for one more hour at 95 C.
Table I
The resulting composition of the poly alkyl methacrylate copolymer formed is:
Polymer Components Weight % Based on Total Weight of
Copolymer
Dodecylmethacrylate 61
Tetradecyl m ethacry late 23
Hexadecylmethacrylate 7
Octadecylmethacrylate 4
Eicosylmethacrylate 1
Docosylmethacrylate 4
Application Data for Pour Point Depressant
Table 2
Properties of 0.2 weight percent PPD in 5W30 Engine oil
PPD Pour Point Scanning Kinematic Gelation Temp.
( C) BROOKFIELD Viscosity 0.2 wt. %,
Viscosity 40 C 5W30
-35 C (cSt) ( C)
(cP)
Comparison -42 (-39) 244,000 35.82 -22
example
Example 1 -45 80,600 35.5 -25.5
1. The pour point depressant (PPD) is in the solvent used to synthesis the PPD
in
example 1. The solvent is a neutral hydrotreated oil.
2. The comparison example is a commercially available poly alkyl methacrylate
copolymer. The polymer is formed from long chain esters of methacrylate (=>C12
). The
pour point in parenthesis represents a second run of the same test.
a I i
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The above tests are well known to one skilled in the art. The scanning
BROOKFIELD
viscosity is determined by ASTM D2983. Kinematic Viscosity is determined by
ASTM
D445. Pour point is determined by ASTM D5950 and Gelation Temperature is
determined by ASTM5153.
Pour Point as a Function of Concentration
Figure 1 illustrates the pour point as a function of concentration for a
commercial pour
point depressant and example 1 in an hydraulic type oil. The commercial pour
point
depressant is also a long chain poly alkyl methacryalte copolymer. The graph
illustrates
the surprising improved efficiency of example 1 as compared to the
commercially
available pour point depressant. Lower concentrations of example 1 are
required to
achieve the same or lower pour point values.
Viscosity as a Function of Temperature
The copolymer of example 1 and a commercial pour point depressant are each
added
separately to a fully formulated 5W30 engine oil. The viscosity for both
samples is
observed across a range of temperatures (-35.0 C to -5.0 C). The copolymer
of
example 1 at a concentration of 0.05 weight percent in the engine oil achieves
the same
viscosity profile as a 0.1 weight percent concentration for the commercially
available
pour point depressant. The commercial pour point depressant is also a long
chain poly
alkyl methacrylate. Thus the copolymer of example 1 is found to be twice as
efficient as
the commercial pour point depressant in achieving the same
temperature/viscosity
profile.
Table 3
Pour Point and Scanning BROOKFIELD Viscosity in Type II oil with 0.2 wt. % of
the Poly
alkylmethacrylate formed in example 1.
Sample Pour Point ( C) Scanning BROOKFIELD
Viscosity at -40 C (Cps)
Type II Oil -58 14,777
Type II Oil with 0.2 wt. % -56 8,648
example 1
21
