Note: Descriptions are shown in the official language in which they were submitted.
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COMPOSITIONS COMPRISING ANIMAL OR VEGETABLE DERIVED
OIL AND AN ETHYLENE-VINYL ESTER COPOLYMER
This invention relates to the use of wax crystal modifying additives in oils
obtained from animal or vegetable material or both, or derivatives thereof, or
their
mixtures with petroleum-based oils.
Oils obtained from animal or vegetable material are mainly metabolites
comprising triglycerides of monocarboxylic acids, e.g. acids containing 10 to
25
carbon atoms which may be saturated or unsaturated.
Generally, such oils contain glycerides of a number of acids, the number and
kind varying with the source of the oil, and may additionally contain
phosphoglycerides. Such oils may be obtained by methods know in the art.
Examples of derivatives of such oils are alkyl esters, such as methyl esters,
of
fatty acids of the vegetable or animal oils. Such esters can be made by
transesterification.
Reference within this specification to oils that are derived from animal or
vegetable material therefore includes reference both to oils obtained from
said animal
or vegetable material or both, or to derivatives thereof.
FR-A-2,492,402 describes fuel compositions containing one or more fatty acid
esters of animal and vegetable origin described by the general formula:
Rt-COO-R2
where R1 contains 5 to 23 carbon atoms, being a substantially linear saturated
or
unsaturated aliphatic radical and R2 contains I to 12 carbon atoms, being a
linear or
branched, saturated or unsaturated, aliphatic radical. Such fuel compositions
are
described as particularly suitable for use in diesel engines, possessing a
cetane-index
range broadly equivalent to that of conventional diesel fuels derived from
mineral oils.
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However the usefulness of such fatty acid ester compositions as diesel fuels
is
limited by their low temperature properties. DE-A-4,040,317 discloses that at
temperatures below -5 C, such fuels may solidify in supply lines due to
inadequate
filterability, and describes a process for improving the low temperature
filterability
involving the addition of mixtures of short chain methyl esters of fatty acids
and
selected polymeric materials, namely polymeric esters or copolymers of esters
of
acrylic and/or methacrylic acids derived from alcohols possessing 1 to 22
carbon
atoms.
The low temperature properties of petroleum-based oils, i.e. mineral oils and
their derivatives such as crude oil, lubricating oil and fuel oil, for example
middle
distillate fuel oil, are well documented in the art. Similarly, it is known to
use
additives to modify the wax crystal structure of these mineral oils and
derivatives
thereof. Examples of such additives and their use are described in US-A-
3,048,479;
GB-A-1,263,152; US-A-3,961,916; US-A-4,211,534; EP-A-153,176 and
EP-A-153,177.
In contrast to said mineral oils and derivatives thereof, the low temperature
properties of oils according to the present invention being oils derived from
animal or
vegetable material, are controlled predominantly by the precipitation of
higher
molecular weight fatty acid esters present as major constituents. Such fatty
acid esters
are frequently derived from mixtures of saturated and unsaturated fatty acids.
By way
of example only, the main components of rapeseed oil methyl ester are the
methyl
esters of oleic, linoleic, linolenic and erucic acids.
In general such unsaturated fatty acid derivatives predominate over their
saturated analogues, although the exact proportions of individual components
within a
particular oil may vary as a result of seasonal fluctuations of the
constituent fatty
acids within the source material, or as a result of the particular method by
which they
are obtained.
This preponderance of ethylenically-unsaturated fatty acid esters provides
such oils with crystallization behavior different from that of the
aforementioned
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mineral oils, with the difference in crystal morphologies between these two
classes of oil
believed to result from the different structural configurations of the
hydrocarbon chains
of precipitating n-alkanes and unsaturated fatty acid esters respectively.
EP0629231 BI describes generally the use of cold flow additives typically used
in
petroleum fuels to improve the low temperature properties of oils derived from
animal or
vegetable oils. Among the additives described in EP0629231 BI are ethylene
unsaturated ester copolymer flow improvers. Polymer A of EP0629231 B 1 at page
1 1
has about 16 mole% vinyl acetate.
The present invention is based on the discovery that a certain limited
category of
ethylene-vinyl ester copolymers, i.e. those having a certain vinyl ester
content and degree
of branching, exhibit enhanced low temperature performance in fuel oils
derived from
animal or vegetable oils and mixtures of same with petroleum-based fuel oils.
There is provided herein a composition comprising an oil obtained from methyl
esters of animal or vegetable material or both or derivatives thereof, or
mixtures thereof
with petroleum-based oils, in admixture with an ethylene-vinyl ester copolymer
cold flow
additive having at least 17 mole% vinyl ester units and containing 5 or more
alkyl
branches per 100 backbone methylenes, and having a Mn molecular weight in the
range
of 3,000 to 5,000 as measured by gel permeation chromatography (GPC) using
polystyrene standards, with the proviso that the composition does not contain
a comb
polymer of at least one C8-C16 alkyl ester of an ethylenically unsaturated
dicarboxylic
acid and at least one C to-C20 olefin, wherein the sum Q
Qw1i=nti+w2j-n2j
i j
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of the molar averages of the carbon chain distributions in the alkyl side
chains of the
olefins on the one hand and the fatty alcohols in the ester groups on the
other hand is
from 23 to 27, where wI and w2 are the molar proportions of the individual
chain lengths
in the alkyl side chains of the olefins on the one hand and the fatty alcohols
in the ester
groups on the other hand, and n1 and n2 are the side chain lengths, in the
case of olefins
without the originally olefinically bonded carbon atoms, of the alkyl side
chains of the
olefins on the one hand and of the fatty alcohols in the ester groups on the
other hand,
and the serial variables i and j are the individual side chain lengths in the
alkyl side
chains of the olefins on the one hand and of the fatty alcohols in the ester
groups on the
other hand.
Further, there is provided a use of an ethylene-vinyl ester copolymer cold
flow
additive having at least 17 mole% vinyl ester units and containing 5 or more
alkyl
branches per 100 backbone methylenes, and having a Mn molecular weight in the
range
of 3,000 to 5,000 as measured by gel permeation chromatography (GPC) using
polystyrene standards, to improve low temperature properties of an oil
obtained from
methyl esters of animal or vegetable material or both or derivatives thereof,
or mixtures
thereof with petroleum-based oils, with the proviso that a comb polymer of at
least one
C8-C16 alkyl ester of an ethylenically unsaturated dicarboxylic acid and at
least one C10-
C20 olefin, wherein the sum Q
Qwij nIi+w2j n2j
i j
of the molar averages of the carbon chain distributions in the alkyl side
chains of the
olefins on the one hand and the fatty alcohols in the ester groups on the
other hand is
from 23 to 27, where w1 and w2 are the molar proportions of the individual
chain lengths
in the alkyl side chains of the olefins on the one hand and the fatty alcohols
in the ester
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groups on the other hand, and ni and n2 are the side chain lengths, in the
case of olefins
without the originally olefinically bonded carbon atoms, of the alkyl side
chains of the
olefins on the one hand and of the fatty alcohols in the ester groups on the
other hand,
and the serial variables i and j are the individual side chain lengths in the
alkyl side
chains of the olefins on the one hand and of the fatty alcohols in the ester
groups on the
other hand, is not also used.
Additionally, there is provided a method of improving low temperature
properties
of an oil obtained from methyl esters of animal or vegetable material or both
or
derivatives thereof, or mixtures thereof with petroleum-based oils, the method
comprising
the step of adding to the oil an ethylene-vinyl ester copolymer cold flow
additive having
at least 17 mole% vinyl ester units and containing 5 or more alkyl branches
per 100
backbone methylenes, and having a Mn molecular weight in the range of 3,000 to
5,000
as measured by gel permeation chromatography (GPC) using polystyrene
standards, with
the proviso that a comb polymer of at least one CR-Ci(, alkyl ester of an
ethylenically
unsaturated dicarboxylic acid and at least one C10-C2õ olefin, wherein the sum
Q
Qwti - nj i +w2j-n2j
i j
of the molar averages of the carbon chain distributions in the alkyl side
chains of the
olefins on the one hand and the fatty alcohols in the ester groups on the
other hand is
from 23 to 27, where wl and w2 are the molar proportions of the individual
chain lengths
in the alkyl side chains of the olefins on the one hand and the fatty alcohols
in the ester
groups on the other hand, and n1 and n2 are the side chain lengths, in the
case of olefins
without the originally olefinically bonded carbon atoms, of the alkyl side
chains of the
olefins on the one hand and of the fatty alcohols in the ester groups on the
other hand,
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and the serial variables i and j are the individual side chain lengths in the
alkyl side
chains of the olefins on the one hand and of the fatty alcohols in the ester
groups on the
other hand, is not also added to the oil.
The present invention comprises a major proportion of an oil obtained from
methyl esters of animal or vegetable oils, or both, or derivatives thereof, or
their mixtures
with petroleum-based oils in admixture with a minor proportion of an ethylene-
vinyl ester
copolymer flow improver having a polymethylene backbone divided into segments
by
oxyhydrocarbon chains, the polymer having a vinyl ester content of at least
17, preferably
17-25, more preferably 17-19, mole% and the number of short-chain alkyl
branches,
measured as the number of alkyls per 100 backbone methylenes should be greater
than 5,
preferably from 6 to 8. The esters are those of monocarboxylic acids having 2
to 30,
preferably 2 to 10 carbon atoms.
The following copolymers are preferred: ethylene-vinyl acetate, ethylene-vinyl
propionate, ethylene-vinyl hexanoate, ethylene-vinyl 2-ethylhexanoate, or
ethylene-vinyl
octanoate copolymer. The Mn molecular weight of the copolymers will be in the
range
of 1,000 to 10,000, preferably 2,000 to 6,000, more preferably 3,000 to 5,000,
as
measured by GPC using polystyrene standards.
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They may also be in the form of mixture of two copolymers such as those
described in US-A3,961,916. If desired, the copolymers may be derived from
additional comonomers, e.g., they may be terpolymers or tetrapolymers or
higher
polymers, for example where the additional comonomer is propylene or
isobutylene.
The copolymers may be made by direct polymerisation of comonomers. Such
copolymers may also be made by transesterification, or by hydrolysis and
reesterification, of an ethylene unsaturated ester copolymer to give a
different
unsaturated ester copolymer. For example, ethylene-vinyl hexanoate and
ethylene-
vinyl 2-ethylhexanoate copolymers may be made this way, e.g., from an ethylene-
vinyl acetate copolymer.
The polymers of this invention may be used in combination with conventional
cold flow additives which may comprise one or more of the following:
(a) another ethylene-unsaturated ester copolymer;
(b) a comb polymer;
(c) polar nitrogen compounds;
(d) a compound containing a cyclic ring system;
(e) a hydrocarbon polymer;
(f) a polyoxyalkylene compound;
(g) a hydrocarbylated-aromatic pour point depressant; or
(h) alkyl phenol formaldehyde condensates.
The features of this invention will now be discussed in further detail.
OILS
Examples of oils derived from animal or vegetable material are rapeseed oil,
coriander oil, soyabean oil, cottonseed oil, sunflower oil, caster oil, olive
oil, peanut
oil, maize oil, almond oil, palm kernel oil, coconut oil, mustard seed oil,
beef tallow
and fish oils. Further examples include oils derived from corn, jute, sesame,
shea nut,
ground nut and linseed and may be derived therefrom by methods know in the
art.
Rapeseed oil, which is a mixture of fatty acids partially esterified with
glycerol, is
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preferred as it is available in large quantities and can be obtained in a
simple way by
pressing from rapeseed.
As lower alkyl esters of fatty acids, consideration may be given to the
following, for example as commercial mixtures: the ethyl, propyl, butyl and
especially methyl esters of fatty acids with 12 to 22 carbon atoms, for
example of
lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid,
oleic acid,
elaidic acid, petroselic acid, ricinoleic acid, elaeostearic acid, linoleic
acid, linolenic
acid, eicosanoic acid, gadoleic acid, docosanoic acid or erucic acid, which
have an
iodine number from 50 to 150, especially 90 to 125. Mixtures with particularly
advantageous properties are those which contain mainly, i.e. to at least 20
wt.%
methyl esters of fatty acids with 16 to 22 carbon atoms and 1, 2 or 3 double
bonds.
The preferred lower alkyl esters of fatty acids are the methyl esters of oleic
acid,
linoleic acid, linolenic acid and erucic acid.
Commercial mixtures of the stated kind are obtained for example by cleavage
and esterification of animal and vegetable fats and oils by their
transesterification with
lower aliphatic alcohols. For production of lower alkyl esters of fatty acids
it is
advantageous to start from fats and oils with high iodine number, such as, for
example,
sunflower oil, rapeseed oil, coriander oil, castor oil, soyabean oil,
cottonseed oil,
peanut oil or beef tallow. Lower alkyl esters of fatty acids based on a new
variety of
rapeseed oil, the fatty acid component of which is derived to more than 80
wt.% from
unsaturated fatty acids with 18 carbon atoms, are preferred.
Particularly preferred are oils according to this invention capable of being
utilized as biofuels. Biofuels, i.e. fuels derived from animal or vegetable
material, are
believed to be less damaging to the environment on combustion, and are
obtained
from a renewable source. It has been reported that on combustion less carbon
dioxide
is formed than is formed by the equivalent quantity of petroleum distillate
fuel, e.g.
diesel fuel, and very little sulphur dioxide is formed. Certain derivatives of
vegetable
oil, e.g. those obtained by saponification and re-esterification with a
monohydric alkyl
alcohol, may be used as a substitute for diesel fuel. Rapeseed esters, for
example,
rapeseed oil methyl ester (RME), have been used neat on their own or in
mixtures
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with petroleum distillate fuels. Thus, a biofuel is an oil obtained from
vegetable or
animal material, or both, or a derivative thereof, capable of being utilized
as a fuel.
Whilst many of the above oils may be used as biofuels, preferred are vegetable
oils or derivatives thereof, of which particularly preferred biofuels are
rapeseed oil,
cottonseed oil, soyabean oil, sunflower oil, olive oil, palm oil, or alkyl
ester
derivatives thereof, rapeseed oil methyl ester being especially preferred.
The invention is also applicable to mixtures comprising 95-5 wt.% of the
to aforesaid biofuels with 5-95 wt.% by weight of a petroleum based fuel. The
petroleum based 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. Such
distillate fuel
oils generally boil in the range of 100-500 degrees Centigrade. 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 and coal or
biomass
conversion fuels. To make such fuels, syngas (CO + H2) is first generated and
then
converted to normal paraffins by a Fischer-Tropsch process. The normal
paraffins
may then be modified by processes such as catalytic cracking/reforming or
isomerization, 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 concentration of the additive in the oil may for example be in the range
of
1 to 10,000 ppm of additive (active ingredient) by weight per weight of fuel,
for
example 10 to 5,000 ppm such as 10 to 2000 ppm (active ingredient) by weight
per
weight of fuel.
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The additive may be incorporated into bulk oil by methods such as those
known in the art. Where more than one additive component or co-additive
component
is to be used, such components may be incorporated into the oil together or
separately
in any combination.
A concentrate comprising the additive dissolved or 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
additive 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; and paraffinic hydrocarbons such as hexane and pentane and
isoparaffins.
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 conventional cold flow additives for use in combination with the
polymers of the invention are defined in (A) - (H) below.
(A) Other ethylene-unsaturated ester copolymers, more especially one having,
in
addition to units derived from ethylene, units of the formula
-CR7R8 - CHR9 -
* Trade-mark
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where R8 represents hydrogen or a methyl group; R7 represents a - OOCR10 or
COOR10 group wherein R10 represents hydrogen or a C1 to C28, preferably C1 to
C9,
straight or branched chain alkyl group, provided that R10 does not represent
hydrogen
when R7 represents -COOR10, and R9 is hydrogen or -COOR10.
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 an unsaturated carboxylic acid. An ethylene-vinyl ester copolymer
is
advantageous; an ethylene-vinyl acetate, ethylene-vinyl propionate, ethylene-
vinyl
hexanoate, ethylene-vinyl 2-ethylhexanoate, or ethylene-vinyl octanoate
copolymer
is preferred.
Preferably, the copolymers contain from 0.3 up to 15mole%, preferably from
3.5 up to 15 mole% of the vinyl ester.
They may also be in the form of mixtures of two copolymers such as those
described in US-A3,961,916. If desired, the copolymers may be derived from
additional comonomers, e.g. they may be terpolymers or tetrapolymers or higher
polymers, for example where the additional comonomer is propylene or
isobutylene.
The copolymers may be made by direct polymerisation of comonomers. Such
copolymers may also be made by transesterification, or by hydrolysis and
reesterification, of an ethylene unsaturated ester copolymer to give a
different
unsaturated ester copolymer. For example, ethylene-vinyl hexanoate and
ethylene-
vinyl 2-ethylhexanoate copolymers may be made this way, e.g. from an ethylene-
vinyl acetate copolymer.
(B) Comb polymers.
Such polymers are polymers in which branches containing hydrocarbyl groups
are pendant from a polymer backbone, and are discussed in "Comb-Like Polymers.
Structure and Properties", N. A. Plate and V. P. Shibaev, J. Poly. Sci.
Macromolecular
Revs., 8, p 117 to 253 (1974).
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Generally, comb polymers have one or more long chain hydrocarbyl branches,
e.g., oxyhydrocarbyl branches, normally having from 10 to 30 carbon atoms,
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.
Advantageously, the comb polymer is a homopolymer or a copolymer wherein
at least 25 and preferably at least 40, more preferably at least 50, molar per
cent of the
units of which have, side chains containing at least 6, and preferably at
least 10, atoms.
As examples of preferred comb polymers there may be mentioned those of the
general formula
D J
I i
-[C-CH]m-[C-CH]n
it I I
EG KL
wherein D = R", COOR", OCOR", R12COOR", or OR",
E = H, CH3, D, or R12,
G =HorD
J = H, R12, R12COOR", or an aryl or heterocyclic group,
K = H, COOR12, OCOR12, OR12 or COOH,
12 12 12L = H, R, COOR, OCOR, COOH, or aryl,
R" > Clo hydrocarbyl,
R12 >_ C, hydrocarbyl or hydrocarbylene,
and in and n represent mole fractions, m being finite and preferably within
the range
of from 1.0 to 0.4, n being less than 1 and preferably in the range of from 0
to 0.6.
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R1 1 advantageously represents a hydrocarbyl group with from 10 to 30 carbon
atoms, while R12 advantageously represents a hydrocarbyl or hydrocarbylene
group
with from 1 to 30 carbon atoms.
The comb polymer may contain units derived from other monomers if desired
or required.
These comb polymers may be copolymers of maleic anhydride or fumaric or
itaconic acids and another ethylenically unsaturated monomer, e.g., an (X-
olefin,
1o including styrene, or an unsaturated ester, for example, vinyl acetate or
homopolymer
of fumaric or itaconic acids. 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, and 1-
octadecene.
The acid or anhydride group of the comb polymer 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 which may be
used
include n-decan- l -ol, ndodecan- l -ol, n-tetradecan- l -ol, n-hexadecan- l -
ol, and
noctadecan-l-ol. The alcohols may also include up to one methyl branch per
chain,
for example, 1-methylpentadecan I-ol or 2-methyltridecan-l-ol. The alcohol may
be a
mixture of normal and single methyl branched alcohols.
It is preferred to use pure alcohols rather than the commercially available
alcohol mixtures but if mixtures are used the R12 refers to the average number
of
carbon atoms in the alkyl group; if alcohols that contain a branch at the 1 or
2
positions are used R12 refers to the straight chain backbone segment of the
alcohol.
These comb polymers may especially be fumarate or itaconate polymers and
copolymers such for example as those described in EP-A-153176, EP-A-153177 and
-
EP-A-225688, and WO 91/16407.
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Particularly preferred fumarate comb polymers are copolymers of alkyl
fumarates and vinyl acetate, in which the alkyl groups have from 12 to 20
carbon
atoms, more especially polymers in which the alkyl groups have 14 carbon atoms
or
in which the alkyl groups are a mixture of C14/C16 alkyl groups, made, for
example,
by solution copolymerizing an equimolar mixture of fumaric acid and vinyl
acetate
and reacting the resulting copolymer with the alcohol or mixture of alcohols,
which
are preferably straight chain alcohols. When the mixture is used it is
advantageously
a 1:1 by weight mixture of normal C14 and C16 alcohols. Furthermore, mixtures
of the
C14 ester with the mixed C14/C16 ester may advantageously be used. In such
mixtures,
io the ratio of C14 to C14/C16 is advantageously in the range of from 1:1 to
4:1, preferably
2:1 to 7:2, and most preferably about 3:1, by weight. The particularly
preferred comb
polymers are those having a number average molecular weight, as measured by
vapour phase osmometry, of 1,000 to 100,000, more especially 1,000 to 30,000.
Other suitable comb polymers are the polymers and copolymers of a-olefins
and esterified copolymers of styrene and maleic anhydride, and esterified
copolymers
of styrene and fumaric acid; 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, e.g., copolymers of
ethylene and at least one a-olefin, the a-olefin preferably having at most 20
carbon
atoms, examples being n-decene-1 and n-dodecene- 1. Preferably, the number
average
molecular weight of such a copolymer is at least 30,000 measured by GPC. The
hydrocarbon copolymers may be prepared by methods known in the art, for
example
using a Ziegler type 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
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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 -NR13R'4 where R13 is defined as above and
R'4
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 dioctacedyl 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
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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.
(D) Compounds containing a cyclic ring system carrying at least two
substituents
of the general formula below on the ring system
-A-NR 15R16
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 WO 94/07842.
(E) Hydrocarbon polymers.
Examples of suitable hydrocarbon polymers are those of the general formula
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TH UH
II II
-[C-C]I-[C-Cll-
II I I
TT HU
wherein T = H or R17 wherein
R17= C1 to C40 hydrocarbyl, and
U =H,T,oraryl
and v and w represent mole fractions, v being within the range of from 1.0 to
0.0, w
being in the range of from 0.0 to 1Ø
Examples of hydrocarbon polymers are disclosed in WO 91/11488.
Preferred copolymers are ethylene a -olefin copolymers, having a number
average molecular weight of at least 30,000. Preferably the a-olefin has at
most 28
carbon atoms. Examples of such olefins are propylene, 1-butene, isobutene, n-
octene-
1, isooctene-1, n-decene-1, and n-dodecene-1. The copolymer may also comprise
small amounts, e.g., up to 10% by weight, of other copolymerizable monomers,
for
example, olefins other than a-olefins, and non-conjugated dienes. The
preferred
copolymer is an ethylene-propylene copolymer.
The number average molecular weight of the ethylene a-olefin copolymer is,
as indicated above, preferably at least 30,000, as measured by gel permeation
chromatography (GPC) relative to polystyrene standards, advantageously at
least
60,000 and preferably at least 80,000. Functionally no upper limit arises but
difficulties of mixing result from increased viscosity at molecular weights
above
about 150,000, and preferred molecular weight ranges are from 60,000 and
80,000 to
120,000.
Advantageously, the copolymer has a molar ethylene content between 50 and
85 per cent. More advantageously, the ethylene content is within the range of
from 57
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to 80%, and preferably it is in the range from 58 to 73%; more preferably from
62 to
71 %, and most preferably 65 to 70%.
Preferred ethylene- a-olefin copolymers are ethylenepropylene copolymers
with a molar ethylene content of from 62 to 71% and a number average molecular
weight in the range 60,000 to 120,000; especially preferred copolymers are
ethylene-
propylene copolymers with an ethylene content of from 62 to 71% and a
molecular
weight from 80,000 to 100,000.
The copolymers may be prepared by any of the methods known in the art, for
example using a Ziegler type catalyst. The polymers should be substantially
amorphous, since highly crystalline polymers are relatively insoluble in fuel
oil at low
temperatures.
Other suitable hydrocarbon polymers include a low molecular weight
ethylene- a -olefin copolymer, advantageously with a number average molecular
weight of at most 7500, advantageously from 1,000 to 6,000, and preferably
from
2,000 to 5,000, as measured by vapour phase osmometry. Appropriate a-olefins
are
as given above, or styrene, with propylene again being preferred.
Advantageously the
ethylene content is from 60 to 77 molar per cent, although for ethylene-
propylene
copolymers up to 86 molar per cent by weight ethylene may be employed with
advantage.
(F) Polyoxyalkylene compounds.
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
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R"-O(D) -O-R'9
where R18 and R19 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.
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.
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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.
(G) Hydrocarbylated aromatics.
These materials are condensates comprising aromatic and hydrocarbyl parts.
The aromatic part is conveniently an aromatic hydrocarbon which may be
unsubstituted or substituted with, for example, non-hydrocarbon substituents.
Such aromatic hydrocarbon preferably contains a maximum of these
substituent groups and/or three condensed rings, and is preferably
naphthalene. The
hydrocarbyl part is a hydrogen and carbon containing part connected to the
rest of the
molecule by a carbon atom. It my be saturated or unsaturated, and straight or
branched, and may contain one or more hetero-atoms provided they do not
substantially affect the hydrocarbyl nature of the part. Preferably, the
hydrocarbyl
part is an alkyl part, conveniently having more than 8 carbon atoms. The
molecular
weight of such condensates may, for example, be in the range of 2,000 to
200,000
such as 2,000 to 20,000, preferably 2,000 to 8,000.
Examples are known in the art, primarily as lube oil pour depressants and as
dewaxing aids as mentioned hereinbefore, they may, for example, be made by
condensing a halogenated wax with an aromatic hydrocarbon. More specifically,
the
condensation may be a Friedel-Crafts condensation where the halogenated wax
contains 15 to 60, e.g., 16 to 50, carbon atoms, has a melting point of about
200 to
400 C and has been chlorinated to 5 to 25 wt.% chlorine, e.g., 10 to 18 wt.
Another
way of making similar condensates may be from olefins and the aromatic
hydrocarbons.
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(H) Alkyl Phenol Formaldehyde Condensates
Suitable alkyl phenol formaldehyde condensates are disclosed in EP 0 311 452
and EP 0 851 776.
The alkyl phenol formaldehyde condensate may be obtainable by the
condensation reaction between:
(i) at least one aldehyde or ketone or reactive equivalent thereof, and
(ii) at least one compound comprising one or more aromatic moieties
bearing at least one substituent of the formula -XR' and at least one
further substituent -R2, wherein:
X represents oxygen or sulphur,
R' represents hydrogen or a moiety bearing at least one hydrocarbyl
group, and
R2 represents a hydrocarbyl group, linear or branched, preferably
containing from 4 to 40 carbon atoms, more preferably containing
from 8 to 30 carbon atoms and most preferably containing from 8 to 18
carbon atoms.
The alkyl phenol formaldehyde condensate may be present in the fuel oil in an
amount ranging from 5 to 5,000 ppm, preferably 10 to 1,000 ppm and most
preferably
from 20 to 500 ppm.
EXAMPLES
The invention will now be particularly described, by way of example only, as
follows.
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EXAMPLE 1
Additives
The following additives were used:
Polymer 1: an ethylene/vinyl acetate copolymer having a vinyl acetate
concentration of about 38.1 wt.% (16.7% mole), a number average
molecular weight of about 2,470 and containing about 7.6 alkyl
branches per 100 methylene units
Polymer 2: an ethylene/vinyl acetate copolymer having a vinyl acetate
concentration of about 15 wt.% (5mole%), a number average
molecular weight of about 6,500 and containing about 8 alkyl branches
per 100 methylene units
Polymer 3: a polymer of this invention having about 40 wt.% (17.5 mole%) vinyl
acetate, a number average molecular weight of about 3,700 and
containing about 6 alkyl branches per 100 methylene units
Co-additive: a comb polymer, di-n-dodecyl fumarate/vinyl-acetate.
Test
Polymers 1, 2, 3 and the co-additive were dissolved in samples of the same
rapeseed methyl ester fuel and the Cold Filter Plugging Point (CFPP) test
measured
by the procedure described in detail in "Journal of the Institute of
Petroleum",
Volume 52, Number 510, June 1966, pp 173-285. The CFPP is a measure of
filterability. The results are in the table below.
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TABLE
Additive components
Additive Polymer 1 Polymer 2 Polymer 3 Co-additive Total CFPP, C
treat rate
mAi mAt mAi mAi mAi
Base fuel 0 0 0 0 0 -16
A 1920 0 0 80 2000 -20
B 1440 480 0 80 2000 -18
C 1782 137 0 80 2000 -19
Example A 0 0 1920 80 2000 -24
Example B 0 480 1440 80 2000 -24
Example C 0 137 1782 80 2000 -26
Note: "ppm Ai" refers to the active ingredient of the cold flow additive in
ppm by
weight, i.e., without regard to any amount of carrier solvent.
The examples of the invention are Example A, Example B and Example C,
each of which include the polymer of this invention, Polymer 3, which exhibits
superior performance in the CFPP test.
