Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COLD FLOW IMPROVER COMPOSITIONS FOR FUELS
This invention relates to novel compositions useful as fuel additive
compositions, use
of the additive compositions to improve cold flow characteristics of fuel
oils, fuel oil
compositions comprising the additive compositions and additive concentrates of
the additive
compositions.
Fuel oils, whether derived from petroleum or from vegetable sources, contain
components, e.g., n-alkanes, that at low temperatures tend to precipitate as
large crystals or
spherulites of wax in such a way as to form a gel structure which causes the
fuel to lose its
ability to flow. The lowest temperature at which the fuel will still flow is
known as the pour
point.
As the temperature of the fuel falls and approaches the pour point,
difficulties arise in
transporting the fuel through lines and pumps. Further, the wax crystals tend
to plug fuel
lines, screens, and filters at temperatures above the pour point. These
problems are well
recognized in the art, and various additives have been proposed, many of which
are in
commercial use, for depressing the pour point of fuel oils. Similarly, other
additives have
been proposed and are in commercial use for reducing the size and changing the
shape of the
wax crystals that do form. Smaller size crystals are desirable since they are
less likely to clog
a filter. The wax from a diesel fuel, which is primarily an alkane wax,
crystallizes as
platelets; certain additives inhibit this and cause the wax to adopt an
acicular habit, the
resulting needles being more likely to pass through a filter than are
platelets. The additives
may also have the effect of retaining in suspension in the fuel the crystals
that have formed,
the resulting reduced settling also assisting in prevention of blockages.
US 5,487,763 describes additives for distillate fuels which are copolymers of
an alpha
olefin or an aromatic substituted olefin with an ester of a dicarboxylic acid.
EP 0356256 describes the use of an additive to improve the low temperature
properties
of distillate fuels, wherein the additive may include a comb polymer which is
a copolymer of
a fumarate ester and vinyl acetate.
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US 3,982,909 describes the use, in combination, of nitrogen compounds,
hydrocarbons,
such as waxes, and pour point depressants as cold flow improvers for middle
distillate fuel
oils. The pour point depressant is preferably an ethylene backbone polymer
derived from the
copolymerization of ethylene with e.g. an ester of a dicarboxylic acid.
US 5,094,666 describes a three or more component additive comprising an
ethylene
backbone polymer, and two nitrogen compounds.
EP 0308176 describes an additive for adding to a fuel oil which is a fused
mixture of a
paraffin wax and a flow improver. The flow improver may be a copolymer of an
ester of
fumaric acid and a vinyl ester. The additive may be in the form of solid slabs
or blocks to aid
effective distribution and handling.
The present invention is concerned with the problem of providing an improved
additive composition for improving cold flow characteristics of fuel oils.
More particularly, the present invention is concerned with the problem of
improving
cold flow characteristics of fuel oils having a 90% - 20% boiling temperature
range, as
measured in accordance with ASTM D-86, of preferably from 80 to 150°C,
and a final
boiling point of from 320 to 390°C.
The present invention is based on the discovery of a three additive system for
improving the cold flow properties of distillate fuels oils using certain
copolymers or
homopolymers not heretofore used as fuels additives in combination with at
least two
conventional cold flow additives.
In accordance with this invention, there is provided a fuel oil composition
having
improved low temperature properties comprising a fuel oil and an effective
amount of a
polymeric substance selected from the group consisting of:
(a)
(i) copolymers of one or more monoesters of malefic acid, itaconic acid or
citraconic
acid with one or more branched monohydric alcohols having 1 to 18 carbon atoms
and
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more than a single methyl branch, or one or more straight-chain monohydric
alcohols
having less than 10 carbon atoms; and one or more vinyl esters of carboxylic
acids
having 2 to 18 carbon atoms; or
(ii) copolymers of a C4 to C6 dicarboxylic acid anhydride and one or more
vinyl esters
of carboxylic acids having 2 to 18 carbon atoms, esterified with one or more
monohydric alcohols having 1 to 18 carbon atoms;
(b) copolymers of one or more alkylacrylates or alkylmethacrylates, where the
alkyl
groups have 1 to 18 carbon atoms, and acrylic or methacrylic acid;
(c) copolymers of one or more acrylic acids or methacrylic acids and one or
more vinyl
esters of carboxylic acids having 2 to 18 carbon atoms; and,
(d)
(i) homopolymers of one or more monoesters of an unsaturated C4 to C6
dicarboxylic
acid with a branched monohydric alcohol having 1 to 18 carbon atoms and more
than
a single methyl branch, or a straight-chain monohydric alcohol having less
than 10
carbon atoms, or
(ii) homopolymers of an C4 to C6 dicarboxylic acid anhydride, followed by
esterification with one or more monohydric alcohols having 1 to 18 carbon
atoms,
said polymeric substance being present in the fuel oil in combination with two
or more other
cold flow additives selected from the group consisting of: ethylene-
unsaturated monomer
copolymers; comb polymers; polar nitrogen compounds; polyoxyalkylene compounds
and di-
block hydrocarbon polymers.
The preferred two additional cold flow additives are (1) ethylene-unsaturated
ester
copolymers, particularly a copolymer of ethylene and vinyl acetate or a
terpolymer of
ethylene, vinyl acetate and vinyl 2-ethylhexanoate, and (2) polar nitrogen
compounds,
particularly the reaction product of di-hydrogenated tallow amine and phthalic
anhydride, or
the free amine.
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Suitable dicarboxylic acid anhydrides for use in preparing the copolymer
include
malefic anhydride, itaconic anhydride and citraconic anhydride, and the like,
with malefic
anhydride being preferred. Suitable dicarboxylic acids for use in preparing
the copolymer
include malefic acid, fumaric acid, itaconic acid, and the like, with malefic
acid being preferred.
Preferred alcohols include those alcohols having 6 to 14 carbon atoms,
especially the
branched alkanols, with 2-ethylhexanol and isodecyl alcohol being particularly
preferred.
Mixed esters can also be used.
The preferred vinyl ester for use in preparing the copolymeric additive is
vinyl 2-
ethylhexanoate, also preferred are vinyl acetate and the vinyl esters of
branched chain
carboxylic acids having 9 to 11 carbon atoms. Mixed vinyl esters can also be
used.
Methacrylic and acrylic acids can also be copolymerized with
alkylmethacrylates and
alkylacrylates, where the alkyl groups are branched or straight chained and
include of 1-18
carbon atoms. Again, mixed esters can also be used.
The copolymers or homopolymers of this invention will have a number average
molecular weight (Mn) ranging from about Mn 1,000 to about Mn 20,000,
preferably about
Mn 2,000 to Mn 8,000. The copolymers will contain about 25 to 75, preferably
40 to 60,
most preferably about 50 mole % of dicarboxylic acid half ester or
alkylacrylate ester or
alkylmethacrylate ester.
The copolymers or homopolymers of this invention are prepared using
conventional
synthesis techniques well known in the art. For example, the monoesters of the
dicarboxylic
acids are polymerized by use of a suitable polymerization initiator, such as
an organic perester
initiator, at temperatures of about 50 to 120°C in a suitable solvent
such as toluene. They can
also be prepared by copolymerization or homopolymerization of the dicarboxylic
acid
anhydrides followed by esterification with a monohydric alcohol.
In an embodiment, the copolymers or homopolymers of the invention may be post-
reacted with one or more amines. Primary, secondary, tertiary and branched
amines, including
mixtures thereof, are suitable.
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The invention still further provides an additive concentrate comprising a
solvent or
carrier liquid miscible with fuel oil and the three additive system comprising
the copolymer or
homopolymer and at least two additional cold flow additives as described
above.
The fuel oil may be, e.g., a petroleum-based fuel oil, especially a middle
distillate fuel
oil. Such distillate fuel oils generally boil within the range of from
110°C to 500°C, e.g.
150°C to 400°C.
The invention is applicable to middle distillate fuel oils of all types,
including the
broad-boiling distillates, i.e., those having a 90%-20%o boiling temperature
difference, as
measured in accordance with ASTM D-86, of 80°C or more.
The fuel oil may comprise atmospheric distillate or vacuum distillate, cracked
gas oil,
or a blend in any proportion of straight run and thermally and/or
catalytically cracked
distillates. The most common petroleum distillate fuels are kerosene, jet
fuels, diesel fuels,
heating oils and heavy fuel oils. The heating oil may be a straight
atmospheric distillate, or
may also contain vacuum gas oil or cracked gas oil or both. The fuels may also
contain major
or minor amounts of components derived from the Fischer-Tropsch process.
Fischer-Tropsch
fuels, also known as FT fuels, include those that are described as gas-to-
liquid fuels, coal
andlor biomass conversion fuels. To make such fuels, syngas (CO + H2) is first
generated and
then converted to normal paraffins and olefins by a Fischer-Tropsch process.
The normal
paraffins may then be modified by processes such as catalytic
cracking/reforming or
isomerisation, hydrocracking and hydroisomerisation to yield a variety of
hydrocarbons such
as iso-paraffins, cyclo-paraffins and aromatic compounds. The resulting FT
fuel can be used
as such or in combination with other fuel components and fuel types such as
those mentioned
in this specification. The above mentioned low temperature flow problem is
most usually
encountered with diesel fuels and with heating oils. The invention is also
applicable to fuel
oils containing fatty acid methyl esters derived from vegetable oils, for
example, rapeseed oil,
either used alone or in admixture with a petroleum distillate oil.
The concentration of the copolymer or homopolymer additives of the invention
and
each of the additional cold flow additives in the oil may each be in the range
of 0.1 to 1,000
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ppm of additive (active ingredient) by weight per weight of fuel, preferably 1
to 500 ppm,
more preferably 1 to 100 ppm.
A concentrate comprising the additive dispersed in Garner liquid (e.g. in
solution) is
convenient as a means of incorporating the additive. The concentrates of the
present
invention are convenient as a means for incorporating the additives into bulk
oil such as
distillate fuel, which incorporation may be done by methods known in the art.
The
concentrates may also contain other additives as required and preferably
contain from 3 to 75
wt.%, more preferably 3 to 60 wt.%, most preferably 10 to 50 wt.% of the
additives preferably
in solution in oil. Examples of carrier liquid are organic solvents including
hydrocarbon
solvents, for example petroleum fractions such as naphtha, kerosene, diesel
and heater oil;
aromatic hydrocarbons such as aromatic fractions, e.g. those sold under the
'SOLVESSO'
tradename; alcohols and/or esters; and paraffinic hydrocarbons such as hexane
and pentane
and isoparaffins. Alkylphenols, such as nonylphenol and 2,4-di-t-butylphenol,
either alone or
in combination with any of the above, have also been found to be particularly
useful as Garner
solvents. The Garner liquid must, of course, be selected having regard to its
compatibility with
the additive and with the fuel.
The additives of the invention may be incorporated into bulk oil by other
methods
such as those known in the art. If co-additives are required, they may be
incorporated into the
bulk oil at the same time as the additives of the invention or at a different
time.
The copolymers or homopolymers of this invention are used in fuel oils in
combination with two or more conventional cold flow additives as defined in
categories (A)
(E) below to achieve enhanced low temperature properties.
(A) Ethylene Polymers
Each polymer may be a homopolymer or a copolymer of ethylene with another
unsaturated
monomer. Suitable co-monomers include hydrocarbon monomers such as propylene,
n- and
iso- butylenes, 1-hexene, 1-octene, methyl-1-pentene vinyl-cyclohexane and the
various
alpha-olefins known in the art, such as 1-decene, 1-dodecene, 1-tetradecene, 1-
hexadecane
and 1-octadecene and mixtures thereof.
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Preferred co-monomers are unsaturated ester or ether monomers, with ester
monomers
being more preferred. Preferred ethylene unsaturated ester copolymers have, in
addition to
units derived from ethylene, units of the formula:
_CR'R2_C~3_
wherein R1 represents hydrogen or methyl, RZ represents COOR4, wherein R4
represents an
alkyl group having from 1-12, preferably 1-9 carbon atoms, which is straight
chain, or, if it
contains 3 or more carbon atoms, branched, or R2 represents OOCRS, wherein RS
represents
R4 or H, and R3 represents H or COOR4.
These may comprise a copolymer of ethylene with an ethylenically unsaturated
ester,
or derivatives thereof. An example is a copolymer of ethylene with an ester of
a saturated
alcohol and an unsaturated carboxylic acid, but preferably the ester is one of
an unsaturated
alcohol with a saturated carboxylic acid. An ethylene-vinyl ester copolymer is
advantageous;
an ethylene-vinyl acetate, ethylene-vinyl propionate, ethylene-vinyl
hexanoate, ethylene-vinyl
2-ethylhexanoate, ethylene-vinyl octanoate or ethylene-vinyl versatate
copolymer is preferred.
Preferably, the copolymer contains from 5 to 40 wt% of the vinyl ester, more
preferably from
10 to 35 wt% vinyl ester. A mixture of two copolymers, for example, as
described in US
Patent No. 3,961,916, may be used. The Mn of the copolymer is advantageously
1,000 to
10,000. If desired, the copolymer may contain units derived from additional
comonomers, e.g.
a terpolymer, tetrapolymer or a higher polymer, e.g. where the additional
comonomer is
isobutylene or diisobutylene or a further unsaturated ester.
(B) A Comb Polymer.
Comb polymers are discussed in "Comb-Like Polymers. Structure and Properties",
N. A. Platy and V. P. Shibaev, J. Poly. Sci. Macromolecular Revs., 8, p 117 to
253 (1974).
Generally, comb polymers consist of molecules in which long chain branches
such as
hydrocarbyl branches, optionally interrupted with one or more oxygen atoms
and/or carbonyl
groups, having from 6 to 30 such as 10 to 20, carbon atoms, are pendant from a
polymer
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backbone, said branches being bonded directly or indirectly to the backbone.
Examples of
indirect bonding include bonding via interposed atoms or groups, which bonding
can include
covalent and/or electrovalent bonding such as in a salt. Generally, comb
polymers are
distinguished by having a minimum molar proportion of units containing such
long chain
branches.
As examples of preferred comb polymers there may be mentioned those containing
units of the general formula
CDE - CHG CJK - CHL
m n
where D represents R", COOR'°, OCOR'°, R''COOR'° or
OR'°;
E represents H or D;
G represents H or D;
J represents H, R", R"COOR'°, or a substituted or unsubstituted
aryl or
heterocyclic group;
K represents H, COOR' 1, OCOR", OR" or COOH;
L represents H, R", COOR", OCOR" or substituted or unsubstituted aryl;
R'° representing a hydrocarbyl group having 10 or more carbon atoms,
and
R" representing a hydrocarbylene (divalent) group in the R"COOR'°
moiety
and otherwise a hydrocarbyl (monovalent) group, and m and n represent mole
ratios, their
sum being 1 and m being finite and being up to and including 1 and n being
from zero to less
than 1, preferably m being within the range of from 1.0 to 0.4 and n being in
the range of from
0 to 0.6. R'° advantageously represents a hydrocarbyl group with from
10 to 30 carbon atoms,
preferably 10 to 24, more preferably 10 to 18. Preferably, R'° is a
linear or slightly branched
alkyl group and R" advantageously represents a hydrocarbyl group with from 1
to 30 carbon
atoms when monovalent, preferably with 6 or greater, more preferably 10 or
greater,
preferably up to 24, more preferably up to 18 carbon atoms. Preferably, R",
when
monovalent, is a linear or slightly branched alkyl group. When R'' is
divalent, it is preferably
a methylene or ethylene group. By "slightly branched" is meant having a single
methyl
branch.
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The comb polymer may contain units derived from other monomers if desired or
required, examples being CO, vinyl acetate and ethylene. It is within the
scope of the
invention to include two or more different comb copolymers.
The comb polymers may, for example, be copolymers of malefic anhydride acid
and
another ethylenically unsaturated monomer, e.g. an a-olefin or an unsaturated
ester, for
example, vinyl acetate as described in EP-A-214,786. It is preferred but not
essential that
equimolar amounts of the comonomers be used although molar proportions in the
range of 2
to 1 and 1 to 2 are suitable. Examples of olefins that may be copolymerized
with e.g, malefic
anhydride, include 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-
octadecene, and
styrene. Other examples of comb polymers include polyalkyl(meth)acrylates.
Copolymer may be esterified by any suitable technique and although preferred
it is not
essential that the malefic anhydride or fumaric acid be at least 50%
esterified. Examples of
alcohols that may be used include n-decan-1-ol, n-dodecan-1-ol, n-tetradecan-1-
ol, n-
hexadecan-1-ol, and n-octadecan-1-ol. The alcohols may also include up to one
methyl
branch per chain, for example, 2-methylpentadecan-1-ol, 2-rnethyltridecan-1-of
as described
in EP-A-213,879. The alcohol may be a mixture of normal and single methyl
branched
alcohols. It is preferred to use pure alcohols rather than alcohol mixtures
such as may be
commercially available; if mixtures are used, the number of carbon atoms in
the alkyl group is
taken to be the average number of carbon atoms in the alkyl groups of the
alcohol mixture; if
alcohols that contain a branch at the 1 or 2 positions are used, the number of
carbon atoms in
the alkyl group is taken to be the number in the straight chain backbone
segment of the alkyl
group of the alcohol.
The copolymer may also be reacted with a primary and/or secondary amine, for
example, a mono- or di-hydrogenated tallow amine.
The comb polymers may especially be fumarate or itaconate polymers and
copolymers
such as for example those described in European Patent Applications 153 176,
153 177, 156
577 and 225 688, and WO 91/16407. The comb polymers are preferably C8 to C,a
dialkylfumarate-vinyl acetate copolymers.
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Other suitable comb polymers are the polymers and copolymers of a-olefins and
esterified copolymers of styrene and malefic anhydride, and esterified
copolymers of styrene
and fumaric acid as described in EP-A-282,342; mixtures of two or more comb
polymers may
be used in accordance with the invention and, as indicated above, such use may
be
advantageous.
Other examples of comb polymers are hydrocarbon polymers such as copolymers of
at
least one short chain 1-alkene and at least one long chain 1-alkene. The short
chain 1-alkene
is preferably a C3-Cg 1-alkene, more preferably a C4-C6 1-alkene. The long
chain 1-alkene
preferably includes greater than 8 carbon atoms and at most 20 carbon atoms.
The long chain
1-alkene is preferably a Clo-C14 1-alkene, including 1-decene, 1-dodecene and
1-tetradecene
(see, for example, WO 93/19106). The comb polymer is preferably a copolymer of
at least
one 1-dodecene and at least one 1-butene in the ratio of 60-90 mole % 1-
dodecene to 40-10
mole % 1-butene, preferably in the ratio of 75-85 mole % 1-dodecene to 25-15
mole°lo 1-
butene. Preferably, the comb polymer is a mixture of two or more comb polymers
made
from a mixture of two or more 1-alkenes. Preferably, the number average
molecular weight
measured by Gel Permeation Chromatography against polystyrene standards of
such a
copolymer is, for example, up to 20,000 or up to 40,000, preferably from 4,000
to 10,000,
preferably 4,000 to 6,000. The hydrocarbon copolymers may be prepared by
methods known
in the art, for example using a Ziegler-Natta type, Lewis acid or metallocene
catalyst.
(C) Polar Nitrogen Compounds.
Such compounds are oil-soluble polar nitrogen compounds carrying one or more,
preferably two or more, substituents of the formula >NR13, where R13
represents a
hydrocarbyl group containing 8 to 40 atoms, which substituent or one or more
of which
substituents may be in the form of a cation derived therefrom. The oil soluble
polar nitrogen
compound is generally one capable of acting as a wax crystal growth inhibitor
in fuels. It
comprises for example one or more of the following compounds:
An amine salt and/or amide formed by reacting at least one molar proportion of
a
hydrocarbyl-substituted amine with a molar proportion of a hydrocarbyl acid
having from 1 to
4 carboxylic acid groups or its anhydride, the substituent(s) of formula >NR13
being of the
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formula -NR'3R'4 where R'3 is defined as above and R'4 represents hydrogen or
R'3, provided
that R'3, and R'4 may be the same or different, said suhstituents constituting
part of the amine
salt and/or amide groups of the compound.
Ester/amides may be used, containing 30 to 300, preferably 50 to 150, total
carbon
atoms. These nitrogen compounds are described in US Patent No. 4,211,534.
Suitable
amines are predominantly C12 to C4o primary, secondary, tertiary or quaternary
amines or
mixtures thereof but shorter chain amines may be used provided the resulting
nitrogen
compound is oil soluble, normally containing about 30 to 300 total carbon
atoms. The
nitrogen compound preferably contains at least one straight chain C8 to Cue,
preferably C~4 to
C24, alkyl segment.
Suitable amines include primary, secondary, tertiary or quaternary, but are
preferably
secondary. Tertiary and quaternary amines only form amine salts. Examples of
amines
include tetradecylamine, cocoamine, and hydrogenated tallow amine. Examples of
secondary
amines include di-octadecylamine, di-cocoamine, di-hydrogenated tallow amine
and
methylbehenyl amine. Amine mixtures are also suitable such as those derived
from natural
materials. A preferred amine is a secondary hydrogenated tallow amine, the
alkyl groups of
which are derived from hydrogenated tallow fat composed of approximately 4%
C14, 31% C16,
and 59% C~g.
Examples of suitable carboxylic acids and their anhydrides for preparing the
nitrogen
compounds include ethylenediamine tetraacetic acid, and carboxylic acids based
on cyclic
skeletons, e.g., cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-
dicarboxylic acid,
cyclopentane-1,2-dicarboxylic acid and naphthalene dicarboxylic acid, and 1,4-
dicarboxylic
acids including dialkyl spirobislactones. Generally, these acids have about 5
to 13 carbon
atoms in the cyclic moiety. Preferred acids useful in the present invention
are benzene
dicarboxylic acids e.g., phthalic acid, isophthalic acid, and terephthalic
acid. Phthalic acid
and its anhydride are particularly preferred. The particularly preferred
compound is the
amide-amine salt formed by reacting 1 molar portion of phthalic anhydride with
2 molar
portions of dihydrogenated tallow amine. Another preferred compound is the
diamide formed
by dehydrating this amide-amine salt.
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Other examples are long chain alkyl or alkylene substituted dicarboxylic acid
derivatives such as amine salts of monoamides of substituted succinic acids,
examples of
which are known in the art and described in US Patent No. 4,147,520, for
example. Suitable
amines may be those described above.
Other examples are condensates, for example, those described in EP-A-327427.
Other examples of polar nitrogen compounds are compounds containing a ring
system
carrying at least two substituents of the general formula below on the ring
system
-A-ysRi6
where A is a linear or branched chain aliphatic hydrocarbylene group
optionally interrupted
by one or more hetero atoms, and R15 and R16 are the same or different and
each is
independently a hydrocarbyl group containing 9 to 40 atoms optionally
interrupted by one or
more hetero atoms, the substituents being the same or different and the
compound optionally
being in the form of a salt thereof. Advantageously, A has from 1 to 20 carbon
atoms and is
preferably a methylene or polymethylene group. Such compounds are described in
WO
93/04148 and W09407842.
Other examples are the free amines themselves as these are also capable of
acting as wax
crystal growth inhibitors in fuels. Suitable amines include primary,
secondary, tertiary or
quaternary, but are preferably secondary. Examples of amines include
tetradecylamine,
cocoamine, and hydrogenated tallow amine. Examples of secondary amines include
di-
octadecylamine, di-cocoamine, di-hydrogenated tallow amine and methylbehenyl
amine.
Amine mixtures are also suitable such as those derived from natural materials.
A preferred
amine is a secondary hydrogenated tallow amine, the alkyl groups of which are
derived from
hydrogenated tallow fat composed of approximately 4% C14, 31% C,6, and 59%
C,8.
(D) A Polyoxyalkylene Compound.
Examples are polyoxyalkylene esters, ethers, esterlethers and mixtures
thereof,
particularly those containing at least one, preferably at least two, Coo to
C3o linear alkyl groups
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and a polyoxyalkylene glycol group of molecular weight up to 5,000, preferably
200 to 5,000,
the alkyl group in said polyoxyalkylene glycol containing from 1 to 4 carbon
atoms. These
materials form the subject of EP-A-0061895. Other such additives are described
in United
States Patent No. 4,491,455.
The preferred esters, ethers or ester/ethers are those of the general formula
R3i-O(D) -O-R3z
where R3' and R3z may be the same or different and represent
(a) n-alkyl-
(b) n-alkyl-CO-
(c) n-alkyl-O-CO(CHz)X or
(d) n-alkyl-O-CO(CHz)x-CO-
x being, for example, 1 to 30, the alkyl group being linear and containing
from 10 to 30
carbon atoms, and D representing the polyalkylene segment of the glycol in
which the
alkylene group has 1 to 4 carbon atoms, such as a polyoxymethylene,
polyoxyethylene or
polyoxytrimethylene moiety which is substantially linear; some degree of
branching with
lower alkyl side chains (such as in polyoxypropylene glycol) may be present
but it is preferred
that the glycol is substantially linear. D may also contain nitrogen.
Examples of suitable glycols are substantially linear polyethylene glycols
(PEG) and
polypropylene glycols (PPG) having a molecular weight of from 100 to 5,000,
preferably
from 200 to 2,000. Esters are preferred and fatty acids containing from 10-30
carbon atoms
are useful for reacting with the glycols to form the ester additives, it being
preferred to use a
C18-Cz4 fatty acid, especially behenic acid. The esters may also be prepared
by esterifying
polyethoxylated fatty acids or polyethoxylated alcohols.
These materials may also be prepared by alkoxylation of a fatty acid ester of
a polyol
(e.g. ethoxylated sorbitan tristearate having the trade name TWEEN 65, which
is available
from Uniqema).
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Polyoxyalkylene diesters, diethers, ether/esters and mixtures thereof are
suitable as
additives, diesters being preferred for use in narrow boiling distillates,
when minor amounts
of monoethers and monoesters (which are often formed in the manufacturing
process) may
also be present. It is preferred that a major amount of the dialkyl compound
be present. In
particular, stearic or behenic diesters of polyethylene glycol, polypropylene
glycol or
polyethylene/ polypropylene glycol mixtures are preferred.
Other examples of polyoxyalkylene compounds are those described in Japanese
Patent
Publication Nos. 2-51477 and 3-34790, and the esterified alkoxylated amines
described in EP
A-117108 and EP-A-326356.
(E) Di-block Hydrocarbon Polymers.
These polymers may be an oil-soluble hydrogenated block dime polymer
comprising
at least one crystallizable block, obtainable by ene-to-end polymerization of
a linear dime,
and at least one non-crystallizable block being obtainable by 1,2-
configuration polymerization
of a linear dime, by polymerization of a branched dime, or by a mixture of
such
polymerizations.
Advantageously, the block copolymer before hydrogenation comprises units
derived
from butadiene only, or from butadiene and at least one comonomer of the
formula
CH2=CR 1-CR2=CHZ
wherein R1 represents a C1 to Cg alkyl group and RZ represents hydrogen or a
C~ to Cg alkyl
group. Advantageously, the total number of carbon atoms in the comonomer is 5
to 8, and the
comonomer is advantageously isoprene. Advantageously, the copolymer contains
at least 10%
by weight of units derived from butadiene.
In addition, the additive composition may comprise one or more other
conventional
co-additives known in the art, such as detergents, antioxidants, corrosion
inhibitors, dehazers,
CA 02490424 2004-12-16
2003M017 - 15 -
demulsifiers, metal deactivators, antifoaming agents, cetane improvers, co-
solvents, package
compatibilizers, lubricity additives and anti-static additives.
EXAMPLES
The invention will now be particularly described, by way of example only, as
follows.
The cold flow improvement properties of the additives of this invention were
evaluated in the two petroleum distillate fuels which are disclosed in Table 1
below.
Table 1
Fuel A B
Country Germany Germany
Sulphur, wt.% 10 ppm 10 ppm
Density at 15C (g/1)0.8294 0.8439
Cloud Point (C) -6.3 -4.4
CFPP (C) -13 -7.5
ASTM D86 (C) .
IBP 200.3 203
5% 216.5 222
10% 222.9 233
20% 232.1 250
30% 242.6 261
40% 253.1 270
50% 264.2 280
60% 275.8 291
70% 287.9 303
80% 301.8 317
90% 320.3 334
95% 337.7 347
FBP 352.6 357
Table 2 below reports the results using Fuel A in the Cold Filter Plugging
Point
(CFPP) test, the details of which are specified in the European Standard
method EN116. The
CFPP test is acknowledged as a standard bench test for determining fuel
performance at low
temperatures and, as such, has been adopted in many national fuel
specifications. "ai" means
active ingredient, i.e., without regard to solvent or carrier oil and "ppm" is
parts per million
by weight
CA 02490424 2004-12-16
2003M017 - 16 -
In Table 2 below, "EVX" is a terpolymer of ethylene, vinyl acetate and vinyl 2-
ethylhexanoate of Mn 4300; "WASA" is the reaction product of dihydrogenated
tallow amine
and phthalic anhydride, and the copolymers of varying Mn's in the invention
are the isodecyl
or 2-ethylhexyl malefic half esters copolymerized with vinyl 2-ethylhexanoate,
e.g. "Isodecyl
S MEVE", as indicated in the Table. The copolymers of the invention
consistently improved
the CFPP value of the fuel containing only EVX and WASA.
Table 2
Treat CFPP (C)
Rate
(ppm
si)
EVX WASA IsodecylIsodecyl2-Ethylhexyl2-Ethylhexyl2-Ethylhexylaverage
MEVE MEVE MEVE MEVE MEVE
Mn 5694Mn Mn 4162 Mn 4871 Mn 5553
4279
240 40 -19.0
270 45 -18.5
300 50 -20.0
330 55 -20.0
360 60 -19.0
240 40 40 -20.7
270 45 45 -20.5
300 50 50 -26.5
330 55 55 -23.8
360 60 60 -25.0
270 45 45 -23.1
300 50 50 -23.5
330 55 55 -26.5
360 60 60 -27.0
240 40 40 -23.3
270 45 45 -23.0
300 50 50 -.27.2
330 55 55 -24.0
360 60 60 -20.5
240 40 40 -21.5
270 45 45 -24.0
300 50 50 -26.4
330 55 55 -24.0
360 60 60 -26.5
240 40 40 -24.4
270 45 45 -20.4
300 50 50 -24.1
330 55 55 -26.5
360 60 60 -25.0
CA 02490424 2004-12-16
2003M017 - 17 -
Table 3, which used Fuel B, reports the results of the Aral Short Sediment
Test run at -13°C.
This test was developed by the German oil company, Aral, and measures the
degree of wax
settling. The fuel is stored at -13°C for 16 hours and the amount of
wax that is judged by eye
to have settled out is noted. The bottom 20°Io of the fuel is then
taken and the Cloud Point
(CP) of this sample is measured and compared to that of the base fuel. The
greater the
difference ("delta CP"), the greater the degree of wax settling.
The additives used in Table 3 were as described in Table 2 except that "PEPEB"
is a
di-block hydrocarbon polymer of Mn 8000; "FVA" is a copolymer of mixed n-C,2
and n-C,4
alkyl fumarate and vinyl acetate and "EVA" is an ethylene-vinyl acetate
copolymer having 29
wt.°Io vinyl acetate and "A2HT" is di-hydrogenated tallow amine.
Additionally, iClO PI is a
homopolymer of the isodecyl half ester of itaconic acid having a Mn of 2000.
CA 02490424 2004-12-16
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N 0.. ~.O~ O~M ~. M ~~ ~ N N
3 ' v O~ fVN N I~ N
N (V
N
T
~1
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W
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CA 02490424 2004-12-16
2003M017 - 19 -
Table 4 below reports additional CFPP data for Fuel A. Six copolymers of the
invention were tested. Tested were three copolymers of the 2-ethylhexyl half
ester of
malefic acid ("2EF~MEA") where the comonomers were vinyl esters of branched
C9,
Coo and C1~ carboxylic acids ("VeoVa9", "VeoValO" and "VeoVal l") as well as
three copolymers each of the isodecyl half ester of malefic acid ("iClO MEA").
CA 02490424 2004-12-16
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U Ov ~ N v~ N N v'1 ~ N
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CA 02490424 2004-12-16
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CA 02490424 2004-12-16
2003M017 - 22 -
Table 5 reports CFPP data for Fuel B wherein the copolymers of the invention
have been
post-reacted with amines. In the table, "CX " represents a primary amine with
X carbon
atoms, e.g. C8 = primary C$ amine.
Table 6 reports data for the test reported in Table 3 for copolymers of the
invention have been
post-reacted with amines.
CA 02490424 2004-12-16
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CA 02490424 2004-12-16
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