-
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.
-
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 maleic acid, itaconic acid or citraconic
acid with one or more branched monohydric alcohols having 1 to 18 carbon atoms and
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.
-
Suitable dicarboxylic acid anhydrides for use in preparing the copolymer include
maleic anhydride, itaconic anhydride and citraconic anhydride, and the like, with maleic
anhydride being preferred. Suitable dicarboxylic acids for use in preparing the copolymer
include maleic acid, fumaric acid, itaconic acid, and the like, with maleic 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.
-
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% 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
and/or 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
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 carrier 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 carrier
solvents. The carrier 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.
-
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:
-CR1R2-CHR3-
wherein R1 represents hydrogen or methyl, R2 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 OOCR5, wherein R5 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. Platé 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
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
where
- D represents R11, COOR10, OCOR10, R11COOR10 or OR10;
- E represents H or D;
- G represents H or D;
- J represents H, R11, R11COOR10, or a substituted or unsubstituted aryl or
heterocyclic group;
- K represents H, COOR11, OCOR11, OR11 or COOH;
- L represents H, R11, COOR11, OCOR11 or substituted or unsubstituted aryl;
- R10 representing a hydrocarbyl group having 10 or more carbon atoms, and
- R11 representing a hydrocarbylene (divalent) group in the R11COOR10 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. R10 advantageously represents a hydrocarbyl group with from 10 to 30 carbon atoms,
preferably 10 to 24, more preferably 10 to 18. Preferably, R10 is a linear or slightly branched
alkyl group and R11 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, R11, when
monovalent, is a linear or slightly branched alkyl group. When R11 is divalent, it is preferably
a methylene or ethylene group. By "slightly branched" is meant having a single methyl
branch.
-
-
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 maleic anhydride acid and
another ethylenically unsaturated monomer, e.g. an α-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. maleic
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 maleic 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-methyltridecan-1-ol 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 C12
dialkylfumarate-vinyl acetate copolymers.
-
Other suitable comb polymers are the polymers and copolymers of α-olefins and
esterified copolymers of styrene and maleic 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-C8 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 C10-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% 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
formula -NR13R14 where R13 is defined as above and R14 represents hydrogen or R13, provided
that R13, and R14 may be the same or different, said substituents 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 C40 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 C40, preferably C14 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% C18.
-
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.
-
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-NR15R16
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 WO9407842.
-
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% C16, and 59% C18.
(D) A Polyoxyalkylene Compound.
-
Examples are polyoxyalkylene esters, ethers, ester/ethers and mixtures thereof,
particularly those containing at least one, preferably at least two, C10 to C30 linear alkyl groups
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
R31-O(D)-O-R32
where R
31 and R
32 may be the same or different and represent
- (a) n-alkyl-
- (b) n-alkyl-CO-
- (c) n-alkyl-O-CO(CH2)x- or
- (d) n-alkyl-O-CO(CH2)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-C24 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).
-
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 diene polymer comprising
at least one crystallizable block, obtainable by ene-to-end polymerization of a linear diene,
and at least one non-crystallizable block being obtainable by 1,2-configuration polymerization
of a linear diene, by polymerization of a branched diene, 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=CR1-CR2=CH2
wherein R1 represents a C1 to C8 alkyl group and R2 represents hydrogen or a C1 to C8 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,
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.
| Fuel | A | B |
| Country | Germany | Germany |
| Sulphur, wt.% | 10 ppm | 10 ppm |
| Density at 15°C (g/l) | 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
-
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 maleic half esters copolymerized with vinyl 2-ethylhexanoate, e.g. "Isodecyl
MEVE", as indicated in the Table. The copolymers of the invention consistently improved
the CFPP value of the fuel containing only EVX and WASA.
| Treat Rate (ppm al) | CFPP (°C) |
| EVX | WASA | Isodecyl MEVE Mn 5694 | Isodecyl MEVE Mn 4279 | 2-Ethylhexyl MEVE Mn 4162 | 2-Ethylhexyl MEVE Mn 4871 | 2-Ethylhexyl MEVEMn 5553 | average |
| 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 |
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% 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
12 and n-C
14
alkyl fumarate and vinyl acetate and "EVA" is an ethylene-vinyl acetate copolymer having 29
wt.% vinyl acetate and "A2HT" is di-hydrogenated tallow amine. Additionally, iC10 PI is a
homopolymer of the isodecyl half ester of itaconic acid having a Mn of 2000.
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
maleic acid ("2EHMEA") where the comonomers were vinyl esters of branched C
9,
C
10 and C
11 carboxylic acids ("VeoVa9", "VeoVa10" and "VeoVa11") as well as
three copolymers each of the isodecyl half ester of maleic acid ("iC10 MEA").
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
8 amine.
-
Table 6 reports data for the test reported in Table 3 for copolymers of the invention have been
post-reacted with amines.
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 C8 amine.
