Note: Descriptions are shown in the official language in which they were submitted.
CA 02573577 2007-01-10
Clariant International Ltd 2006DE402 KM/sch
Description
Additives for low-sulfur mineral oil distillates, comprising graft copolymers
based on
ethylene-vinyl ester copolymers
The invention relates to additives for low-sulfur mineral oil distillates
having improved
cold flowability and paraffin dispersancy, comprising a graft copolymer, to
fuel oils
additized with them and to the use of the additive.
In view of the decreasing mineral oil reserves coupled with steadily rising
energy
demand, ever more problematic crude oils are being extracted and processed. In
addition, the demands on the fuel oils produced therefrom, such as diesel and
heating oil, are becoming ever more stringent, not least as a result of
legislative
requirements. Examples thereof are the reduction in the sulfur content and the
limitation of the final boiling point and also of the aromatics content of
middle
distillates, which force the refineries into constant adaptation of the
processing
technology. In middle distillates, this leads in many cases to an increased
proportion
of paraffins, especially in the chain length range of from C18 to C24, which
in turn has
a negative influence on the cold flow properties of these fuel oils.
Crude oils and middle distillates, such as gas oil, diesel oil or heating oil,
obtained by
distillation of crude oils contain, depending on the origin of the crude oils,
different
amounts of n-paraffins which crystallize out as platelet-shaped crystals when
the
temperature is reduced and sometimes agglomerate with the inclusion of oil.
This
crystallization and agglomeration causes a deterioration in the flow
properties of
these oils or distillates, which may result in disruption in the course of
extraction,
transport, storage and/or use of the mineral oils and mineral oil distillates.
When
mineral oils are transported through pipelines, the crystallization phenomenon
can,
especially in winter, lead to deposits on the pipe walls, and in individual
cases, for
example in the event of stoppage of a pipeline, even to its complete blockage.
When
the mineral oils are stored and processed further, it may also be necessary in
winter
to store the mineral oils in heated tanks. In the case of mineral oil
distillates, the
CA 02573577 2007-01-10
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consequence of crystallization may be blockages of the filters in diesel
engines and
boilers, which prevents reliable metering of the fuels and under some
circumstances
results in complete interruption of the fuel or heating medium feed.
In addition to the classical methods of eliminating the crystallized paraffins
(thermally, mechanically or using solvents), which merely involve the removal
of the
precipitates which have already formed, chemical additives (known as flow
improvers) have been developed in recent years. By interacting physically with
the
precipitating paraffin crystals, they bring about modification of their shape,
size and
adhesion properties. The additives function as additional crystal seeds and
some of
them crystallize out with the paraffins, resulting in a larger number of
smaller paraffin
crystals having altered crystal shape. The modified paraffin crystais have a
lower
tendency to agglomerate, so that the oils admixed with these additives can
still be
pumped and processed at temperatures which are often more than 20 C lower than
in the case of nonadditized oils.
Typical flow improvers for crude oils and middle distillates are co- and
terpolymers of
ethylene with carboxylic esters of vinyl alcohol.
A further task of flow improver is the dispersion of the paraffin crystals,
i.e. the
retardation or prevention of the sedimentation of the paraffin crystals and
therefore
the formation of a paraffin-rich layer at the bottom of storage vessels.
The prior art also discloses certain graft copolymers which are added to
middle
distillates as cold additives.
DE-A-37 25 059 discloses flow improvers based on graft polymers of polyalkyl
methacrylates to ethylene-vinyl ester copolymers, containing
a) 20 - 80% by weight of alkyl methacrylate having 8- 15 carbon atoms in the
ester alkyl radical and
b) 80 - 20% by weight of ethylene-vinyl acetate copolymers, preferably having
28 - 40% by weight of vinyl acetate, where the original viscosity of the
CA 02573577 2007-01-10
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ethylene-vinyl acetate copolymers rj spec/c (at 25 C in xylene) is preferably
6 - 50 ml/g, in particular 6 - 30 ml/g, and where the degree of branching is
preferably from 3 to 15 CH3 groups per 100 CH2 groups and
c) a solvent S having a boiling point of at least 50 C, preferably >100 C, at
pressure (1013 hPa/760 mm).
US-4 608 411 discloses copolymers of ethylene and vinyl acetate, onto which
acrylates are grafted, and the use thereof as a cold additive for fuel oils.
The above-described flow-improving and/or paraffin-dispersing action of the
prior art
paraffin dispersants is not always sufficient, so that, on cooling of the
oils, large
paraffin crystals sometimes form and lead to filter blockages and, owing to
their
higher density, sediment in the course of time and thus lead to the formation
of a
paraffin-rich layer at the bottom of storage vessels. Problems occur in
particular in
the additization of paraffin-rich and narrow-cut distillation cuts having
boiling ranges
of 20 - 90% by volume of less than 120 C, in particular less than 100 C. The
situation is particularly problematic in the case of low-sulfur winter
qualities having
cloud points below -5 C; here, the addition of existing additives often cannot
achieve
sufficient paraffin dispersancy.
It is therefore an object of the invention to improve the flowability and in
particular the
paraffin dispersancy under cold conditions for mineral oils and mineral oil
distillates
by the addition of suitable cold additives.
It has now been found that, surprisingly, a cold additive which comprises
graft
copolymers which are obtainable by grafting alkyl acrylates to specific
ethylene-vinyl
ester copolymers has distinctly better suitability for paraffin dispersancy
than the
prior art graft copolymers.
The invention thus provides a graft copolymer obtainable by grafting an ester
(a) of a
C8- to C22-alcohol and acrylic acid onto a copolymer (b) containing, in
addition to
ethylene, from 0.5 to 16 mol% of at least one vinyl ester of the formula 1
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CH2=CH-OCOR' (1)
where R' is a branched C5_ to C15_ alkyl radical, with the proviso that the
copolymer b)
contains less than 3.5 mol% of vinyl acete.
The graft copolymers thus obtained preferably have a molecular weight (Mn)
between 1000 - 10 000 g/mol, in particular between 1500 - 8000 g/mol.
The invention further provides middle distillate fuel oils which comprise the
above-
described graft copolymer.
The invention further provides for the use of the above-described graft
copolymers
as paraffin dispersants in fuel oils, preferably in middle distillates.
The invention further provides a process for improving the cold flow
properties of fuel
oils, comprising the addition of the above-defined graft copolymers to the
fuel oil.
In a preferred embodiment, R' is a branched alkyl radical or a neoalkyl
radical having
from 7 to 11 carbon atoms, in particular having 8, 9 or 10 carbon atoms.
Particularly
preferred vinyl esters derive from secondary and especially tertiary
carboxylic acids
whose branch is in the alpha-position to the carbonyl group. Suitable vinyl
esters
include vinyl pivalate, vinyl 2-ethylhexanoate, and Versatic esters such as
vinyl
neononanoate, vinyl neodecanoate, vinyl neoundecanoate.
The copolymers preferably have melt viscosities at 140 C of from 20 to
10 000 mPas, in particular from 30 to 5000 mPas, especially from 50 to 2000
mPas.
The ethylene copolymers suitable as the copolymer (b) for the grafting
preferably
have a molecular weight distribution M,N/M,, of from 1 to 10, in particular
from 1.5 to 4.
The ethylene copolymers suitable as the copolymer (b) for the grafting may
contain,
in addition to at least one vinyl ester of the formula 1, up to 16 mol%,
preferably from
1 to 15 mol%, especially from 2 to 10 mol%, of further olefinically
unsaturated
monomers different therefrom, with the proviso that its vinyl acetate content
has to
CA 02573577 2007-01-10
be below 3.5 mol%. These olefinically unsaturated monomers are preferably
vinyl
esters, acrylic esters, methacrylic esters and/or alkyl vinyl ethers, and the
compounds mentioned may be substituted by hydroxyl groups. One or more of
these
comonomers may be present in the copolymer.
5
The vinyl esters are preferably those of the formula 5
CH2=CH-OCOR' (5)
where R' is CT- to C30-alkyl, preferably C4- to C1s-alkyl, especially C6- to
C12-alkyl. In
a further embodiment, the alkyl groups mentioned may be substituted by one or
more hydroxyl groups.
The acrylic esters are preferably those of the formula 2
CH2=CR2-COOR3 (2)
where R 2 is hydrogen or methyl and R3 is Cl- to C30-alkyl, preferably C4- to
C16-alkyl,
especially Cs- to C12-alkyl. Suitable acrylic esters include, for example,
methyl
(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n- and isobutyl
(meth)acrylate, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, tetradecyl,
hexadecyl,
octadecyl (meth)acrylate and mixtures of these comonomers. In a further
embodiment, the alkyl groups mentioned may be substituted by one or more
hydroxyl groups. An example of such an acrylic ester is hydroxyethyl
methacrylate.
The alkyl vinyl ethers are preferably compounds of the formula 3
CH2=CH-OR4 (3)
where R4 is Cl- to C30-alkyl, preferably C4- to C16-alkyl, especially C6- to
C12-alkyl.
Examples include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether.
In a further
embodiment, the alkyl groups mentioned may be substituted by one or more
hydroxyl groups.
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Apart from ethylene, particularly preferred copolymers (b) contain from 0.1 to
12 mol%, in particular from 0.2 to 10 mol%, of vinyl neononanoate or of vinyl
neodecanoate.
The graft component a) is alkyl esters of acrylic acid having 8- 22 carbon
atoms, in
particular having 10 - 15 carbon atoms, in the alkyl radical. It may be
isoalkyl or else
n-alkyl esters. Especially preferred are the iso-C,o-alkyl acrylates and the
C12-C,4-
alkyl acrylates. The alkyl esters of acrylic acid may also be grafted on in a
mixture.
The weight ratio of graft component a) to base polymer b) is preferably from
1:4 to
4:1, in particular from 1:1 to 3:1. The grafting reaction is preferably
carried out as
follows. The base polymer is initially charged in a suitable polymerization
vessel and
a solvent, for example dissolved in kerosene. The amount of the solvent S used
depends upon the nature thereof. The dissolution can be promoted by heating,
for
example to 90 10 C, with stirring. Thereafter, advantageously at elevated
temperature taking into account the decomposition temperatures of the
initiators
used, for instance up to 90 C and under a protective gas such as nitrogen or
argon,
the monomers and an initiator are metered in, for example in a mixture,
advantageously by means of a metering pump and within a certain period, for
example 2 1/2 hours. Useful initiators include the free-radical initiators
customary
per se, in particular per compounds such as peresters, e.g. tert-butyl
peroctoate. In
general, the addition of the initiators is in the range from 0.5 to 5% by
weight,
preferably 1- 4% by weight, based on the monomers. Advantageously, initiator
is
added once again at the end of the feeding, for instance approx. 15% by weight
of
the amount already used. The total polymerization time is about 8-16 hours.
Any homopolymer formed in the polymerization of a) can generally remain in the
batch which can thus be used further as it is, i.e. without specific
purification.
The inventive graft copolymers, which are also referred to hereinafter as
additives,
are added to middle distillates preferably in amounts of from 10 to 500 ppm.
The inventive graft copolymers may be used as such. They may also be present
and
used in the form of additive compositions which, in addition to the inventive
graft
copolymers, comprise one or more further constituents as coadditives. These
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additive compositions are referred to hereinbelow as inventive additives.
In a preferred embodiment, they comprise alkylphenol-aldehyde resins as a
further
constituent (constituent II). Alkylphenol-aldehyde resins are known in
principle and
are described, for example, in Rompp Chemie Lexikon, 9th edition, Thieme
Verlag
1988-92, volume 4, p. 3351 ff. Suitable in accordance with the invention are
in
particular those alkylphenol-aidehyde resins which derive from alkylphenois
having
one or two alkyl radicals in the ortho- and/or para-position to the OH group.
Particularly preferred starting materials are alkylphenois which bear, on the
aromatic
ring, at least two hydrogen atoms capable of condensation with aidehydes, and
especially monoalkylated phenols whose alkyl radical is in the para-position.
The
alkyl radicals (for constituent I, this refers generally to hydrocarbon
radicals as
defined below) may be the same or different in the alkylphenol-aidehyde resins
usable in the process according to the invention, they may be saturated or
unsaturated and have 1- 200, preferably 1- 20, in particular 4- 12 carbon
atoms;
they are preferably n-, iso- and tert-butyl, n- and isopentyl, n- and
isohexyl, n- and
isooctyl, n- and isononyl, n- and isodecyl, n- and isododecyl, tetradecyl,
hexadecyl,
octadecyl, tripropenyl, tetrapropenyl, poly(propenyl) and poly(isobutenyl)
radicals.
Suitable aldehydes for the alkylphenol-aidehyde resins are those having from 1
to 12
carbon atoms and preferably those having from 1 to 4 carbon atoms, for example
formaldehyde, acetaldehyde, propionaidehyde, butyraidehyde, 2-ethylhexanal,
benzaldehyde, glyoxalic acid and reactive equivalents thereof, such as
paraformaidehyde and trioxane. Particular preference is given to formaldehyde
in the
form of paraformaidehyde and especially formalin.
All molecular weights were measured by means of gel permeation chromatography
(GPC) against polystyrene standards in THF.
The molecular weight of the alkylphenol-aldehyde resins is preferably 400 -
20 000 g/mol, especially 400 - 5000 g/mol. A prerequisite in this context is
that the
alkylphenol-aidehyde resins are oil-soluble at least in concentrations
relevant to the
application of from 0.001 to 1% by weight.
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In a preferred embodiment of the invention, the a lkylp hen ol-formaidehyde
resins
contain oligo- or polymers having a repeat structural unit of the formula 4
OH
O
R5 (4)
where R5 is Cl -C200-alkyl or -alkenyl and n is from 2 to 100. R5 is
preferably C4-C20-
alkyl or -alkenyl and especially C6-C16-alkyl or -alkenyl. n is preferably
from 2 to 50
and especially from 3 to 25, for example from 5 to 15.
For use in middle distillates such as diesel and heating oil, particular
preference is
given to alkylphenol-aidehyde resins having C2-C40-alkyl radicals of the
alkylphenol,
preferably having C4-C20-alkyl radicals, for example C6-C12-alkyl radicals.
The alkyl
radicals may be linear or branched; they are preferably linear. Particularly
suitable
alkylphenol-aldehyde resins derive from linear alkyl radicals having 8 and 9
carbon
atoms. The average molecular weight, determined by means of GPC, is preferably
between 700 and 20 000, in particular between 800 and 10 000, for example
between 1000 and 2500 g/mol.
These alkylphenol-aldehyde resins are obtainable by known processes, for
example
by condensation of the appropriate alkylphenols with formaldehyde, i.e. with
from 0.5
to 1.5 mol, preferably from 0.8 to 1.2 mol, of formaldehyde per mole of
alkyiphenol.
The condensation may be effected without solvent, but is preferably effected
in the
presence of a water-immiscible or only partly water-miscible inert organic
solvent
such as mineral oils, alcohols, ethers and the like. Particular preference is
given to
solvents which can form azeotropes with water. Useful such solvents are in
particular
aromatics such as toluene, xylene, diethylbenzene and relatively high-boiling
commercial solvent mixtures such as Shel(sol AB and Solvent Naphtha. The
condensation is effected preferably between 70 and 200 C, for example between
90
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and 160 C. It is catalyzed typically by from 0.05 to 5% by weight of bases or
acids.
For example, the condensation catalyzed by amines, preferably tertiary amines,
for
example triethylamine, with subsequent neutralization by means of organic
sulfonic
acid leads to the inventive mixtures. Preference is given in accordance with
the
invention to catalysis by organic sulfonic acids which, on completion of the
condensation with amines, are converted to the inventive oil-soluble ammonium
sulfonates.
The mixing ratio of the alkylphenol-aidehyde resins as a coadditive to the
inventive
graft copolymers is generally between 20:1 and 1:20, preferably between 1:10
and
10:1.
In a preferred embodiment, the inventive additives for middle distillates
comprise, in
addition to the graft copolymer, one or more copolymers of ethylene and
olefinically
unsaturated compounds as constituent lii. Suitable ethylene copolymers are in
particular those which, in addition to ethylene, contain from 6 to 21 mol%, in
particular from 10 to 18 mol%, of comonomers. These copolymers preferably have
melt viscosities at 140 C of from 20 to 10 000 mPas, in particular from 30 to
5000 mPas, especially from 50 to 2000 mPas.
In a preferred embodiment, the=copolymers are of ethylene and from 6 to 21
mol% of
unsaturated esters. Preferred unsaturated esters are the vinyl esters of C2 to
C12
carboxylic acids. In a further preferred embodiment, the copolymer comprises,
in
addition to ethylene, from 3.5 to 20 mol% of a vinyl ester of a C2 to C4
carboxylic acid
and from 0.1 to 12 mol% of a C6 to C12 carboxylic acid, where the total
content of
vinyl ester is from 6 to 21 mol%, preferably from 10 to 18 mol%.
The olefinically unsaturated compounds are preferably vinyl esters, acrylic
esters,
methacrylic esters, alkyl vinyl ethers and/or alkenes, and the compounds
mentioned
may be substituted by hydroxyl groups. One or more comonomers may be present
in
the polymer.
The vinyl esters are preferably those of the formula 5
CA 02573577 2007-01-10
CH2=CH-OCOR' (5)
where R' is Cl- to C30-alkyl, preferably C4- to C16-alkyl, especially C6- to
C12-alkyl. In
a further embodiment, the alkyl groups mentioned may be substituted by one or
5 more hydroxyl groups.
In a further preferred embodiment, R' is a branched alkyl radical or a
neoalkyl
radical having from 7 to 11 carbon atoms, in particular having 8, 9 or 10
carbon
atoms. Particularly preferred vinyl esters derive from secondary and
especially
10 tertiary carboxylic acids whose branch is in the alpha-position to the
carbonyl group.
Suitable vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate,
vinyl
isobutyrate, vinyl hexanoate, vinyl heptanoate, vinyl octanoate, vinyl
pivalate, vinyl
2-ethylhexanoate, vinyl laurate, vinyl stearate and Versatic esters such as
vinyl
neononanoate, vinyl neodecanoate, vinyl neoundecanoate.
In a further preferred embodiment, these ethylene copolymers contain vinyl
acetate
and at least one further vinyl ester of the formula 5 where R' is C4- to C30-
alkyl,
preferably C4- to C16-alkyl, especially C6- to C12-alkyl.
The acrylic esters are preferably those of the formula 6
CH2=CR2-COOR3 (6)
where R 2 is hydrogen or methyl and R3 is Cl- to C30-alkyl, preferably C4- to
C16-alkyl,
especially C6- to C12-alkyl. Suitable acrylic esters include, for example,
methyl
(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n- and isobutyl
(meth)acrylate, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, tetradecyl,
hexadecyl,
octadecyl (meth)acrylate and mixtures of these comonomers. In a further
embodiment, the alkyl groups mentioned may be substituted by one or more
hydroxyl groups. An example of such an acrylic ester is hydroxyethyl
methacrylate.
The alkyl vinyl ethers are preferably compounds of the formula 7
CH2=CH-OR4 (7)
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where R4 is Cl- to C30-alkyl, preferably C4- to C16-alkyl, especially C6- to
C12-alkyl.
Examples include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether.
In a further
embodiment, the alkyl groups mentioned may be substituted by one or more
hydroxyl groups.
The alkenes are preferably monounsaturated hydrocarbons having from 3 to
30 carbon atoms, in particular from 4 to 16 carbon atoms and especially from 5
to 12
carbon atoms. Suitable alkenes include propene, butene, isobutylene, pentene,
hexene, 4-methylpentene, octene, diisobutylene and norbornene and derivatives
thereof such as methylnorbornene and vinylnorbornene. In a further embodiment,
the alkyl groups mentioned may be substituted by one or more hydroxyl groups.
Apart from ethylene, particularly preferred terpolymers contain from 0.1 to 12
mol%,
in particular from 0.2 to 5 mol%, of vinyl neononanoate or of vinyl
neodecanoate,
and/or from 3.5 to 20 mol%, in particular from 8 to 15 mol%, of vinyl acetate,
the total
comonomer content being between 6 and 21 mol%, preferably between 12 and
18 mol%. Further particularly preferred copolymers contain, in addition to
ethylene
and from 8 to 18 mol% of vinyl esters, also from 0.5 to 15 mol% of alkenes,
for
example propene, butene, isobutylene, hexene, 4-methylpentene, octene,
diisobutylene and/or norbornene.
Preference is given to using mixtures of two or more of the abovementioned
ethylene
copolymers. More preferably, the polymers on which the mixtures are based
differ in
at least one characteristic. For example, they may contain different
comonomers,
different comonomer contents, molecular weights and/or degrees of branching.
The mixing ratio between the inventive additives and ethylene copolymers as
constituent III may, depending on the application, vary within wide limits,
the ethylene
copolymers III often constituting the major proportion. Such additive mixtures
preferably contain from 2 to 70% by weight, preferably from 5 to 50% by
weight, of
the inventive additive, and also from 30 to 98% by weight, preferably from 50
to 95%
by weight, of ethylene copolymers.
The oil-soluble polar nitrogen compounds suitable in accordance with the
invention
as a constituent of the inventive additive (constituent IV) are preferably
reaction
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12
products of fatty amines with compounds which contain an acyl group. The
preferred
amines are compounds of the formula NRsR'R8 where Rs, R' and R8 may be the
same or different, and at least one of these groups is C8-C36-alkyl, Cs-C36-
cycloalkyl
or C8-C36-alkenyl, in particular C12-C24-alkyl, C12-C24-alkenyl or cyclohexyl,
and the
remaining groups are either hydrogen, CI-C36-alkyl, C2-C36-alkenyl,
cyclohexyl, or a
group of the formulae -(A-O)x-E or -(CH2),-NYZ, where A is an ethyl or propyl
group,
x is a number from 1 to 50, E = H, Cl-C30-alkyl, C5-C12-cycloalkyl or Cs-C30-
aryl, and
n = 2, 3 or 4, and Y and Z are each independently H, Cl-C30-alkyl or -(A-O)X.
The
alkyl and alkenyl radicals may each be linear or branched and contain up to
two
double bonds. They are preferably linear and substantially saturated, i.e.
they have
iodine numbers of less than 75 g of 12/g, preferably less than 60 g of 12/g
and in
particular between 1 and 10 g of IZ/g. Particular preference is given to
secondary
fatty amines in which two of the R6, R' and R8 groups are each Cg-C36-alkyl,
Cs-C3s-
cycloalkyl, C8-C36-alkenyl, in particular C12-C24-alkyl, C,2-C24-alkenyl or
cyclohexyl.
Suitable fatty amines are, for example, octylamine, decylamine, dodecylamine,
tetradecylamine, hexadecyiamine, octadecylamine, eicosyfamine, behenylamine,
didecylamine, didodecylamine, ditetradecylamine, dihexadecylamine,
dioctadecylamine, dieicosylamine, dibehenylamine and mixtures thereof. The
amines
especially contain chain cuts based on natural raw materials, for example
coconut
fatty amine, tallow fatty amine, hydrogenated tallow fatty amine, dicoconut
fatty
amine, ditallow fatty amine and di(hydrogenated tallow fatty amine).
Particularly
preferred amine derivatives are amine salts, imides and/or amides, for example
amide-ammonium salts of secondary fatty amines, in particular of dicoconut
fatty
amine, ditallow fatty amine and distearylamine.
Acyl group refers here to a functional group of the following formula:
> C = 0
Carbonyl compounds suitable for the reaction with amines are either low
molecular
weight or polymeric compounds having one or more carboxyl groups. Preference
is
given to those low molecular weight carbonyl compounds having 2, 3 or 4
carbonyl
groups. They may also contain heteroatoms such as oxygen, sulfur and nitrogen.
Suitable carboxylic acids are, for example, maleic acid, fumaric acid,
crotonic acid,
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itaconic acid, succinic acid, Cl-C40-alkenylsuccinic acid, adipic acid,
glutaric acid,
sebacic acid and malonic acid, and also benzoic acid, phthalic acid,
trimellitic acid
and pyromellitic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid
and their
reactive derivatives, for example esters, anhydrides and acid halides. Useful
polymeric carbonyl compounds have been found to be in particular copolymers of
ethylenically unsaturated acids, for example acrylic acid, methacrylic acid,
maleic
acid, fumaric acid and itaconic acid; particular preference is given to
copolymers of
maleic anhydride. Suitable comonomers are those which confer oil solubility on
the
copolymer. Oil-soluble means here that the copolymer, after reaction with the
fatty
amine, dissolves without residue in the middle distillate to be additized in
practically
relevant dosages. Suitable comonomers are, for example, olefins, alkyl esters
of
acrylic acid and methacrylic acid, alkyl vinyl esters, alkyl vinyl ethers
having from 2 to
75, preferably from 4 to 40 and in particular from 8 to 20, carbon atoms in
the alkyl
radical. In the case of olefins, the alkyl radical attached to the double bond
is
equivalent here. The molecular weights of the polymeric carbonyl compounds are
preferably between 400 and 20 000, more preferably between 500 and 10 000, for
example between 1000 and 5000.
It has been found that oil-soluble polar nitrogen compounds which are obtained
by
reaction of aliphatic or aromatic amines, preferably long-chain aliphatic
amines, with
aliphatic or aromatic mono-, di-, tri- or tetracarboxylic acids or their
anhydrides are
particularly useful (cf. US 4 211 534). Equally suitable as oil-soluble polar
nitrogen
compounds are amides and ammonium salts of aminoalkylenepolycarboxylic acids
such as nitrilotriacetic acid or ethylenediaminetetraacetic acid with
secondary amines
(cf. EP 0 398 101). Other oil-soluble polar nitrogen compounds are copolymers
of
maleic anhydride and a,R-unsaturated compounds which may optionally be reacted
with primary monoalkylamines and/or aliphatic alcohols (cf. EP-A-0 154 177,
EP-A-0 777 712), the reaction products of alkenyl-spiro-bislactones with
amines
(cf. EP-A-0 413 279 131) and, according to EP-A-0 606 055 A2, reaction
products of
terpolymers based on a,(3-unsaturated dicarboxylic anhydrides, a,p-unsaturated
compounds and polyoxyalkylene ethers of lower unsaturated alcohols.
The mixing ratio between the inventive additives and oil-soluble polar
nitrogen
CA 02573577 2007-01-10
14
compounds as constituent IV may vary depending upon the application. Such
additive mixtures preferably contain from 10 to 90% by weight, preferably from
20 to
80% by weight, of the inventive additive, and from 10 to 90% by weight,
preferably
from 20 to 80% by weight, of oil-soluble polar nitrogen compounds.
Suitable comb polymers as a coadditive for the inventive additive (constituent
V) may
be described, for example, by the formula
A H G H
I I I I
C-C - C-C -
m I I n
D E M N
In this formula
A is R', COOR', OCOR', R"-COOR', OR';
D is H, CH3, A or R";
E is H, A;
G is H, R", R"-COOR', an aryl radical or a heterocyclic radical;
M is H, COOR", OCOR", OR", COOH;
N is H, R", COOR", OCOR, an aryl radical;
R' is a hydrocarbon chain having from 8 to 50 carbon atoms;
R" is a hydrocarbon chain having from 1 to 10 carbon atoms;
m is between 0.4 and 1.0; and
n is between 0 and 0.6.
Suitable polyoxyalkylene compounds as a coadditive for the inventive additive
(constituent VI) are, for example, esters, ethers and ether/esters which bear
at least
one alkyl radical having from 12 to 30 carbon atoms. When the alkyl groups
stem
from an acid, the remainder stems from a polyhydric alcohol; when the alkyl
radicals
come from a fatty alcohol, the remainder of the compound stems from a
polyacid.
Suitable polyols are polyethylene glycols, polypropylene glycols, polybutylene
glycols
and copolymers thereof having a molecular weight of from approx. 100 to
approx.
CA 02573577 2007-01-10
5000, preferably from 200 to 2000. Also suitable are alkoxylates of polyols,
for
example of glycerol, trimethylolpropane, pentaerythritol, neopentyl glycol,
and the
oligomers which are obtainable therefrom by condensation and have from 2 to 10
monomer units, for example polyglycerol. Preferred alkoxylates are those
having
5 from 1 to 100 mol, in particular from 5 to 50 mol, of ethylene oxide,
propylene oxide
and/or butylene oxide per mole of polyol. Esters are particularly preferred.
Fatty acids having from 12 to 26 carbon atoms are preferred for the reaction
with the
polyols to form the ester additives, and particular preference is given to
using C18- to
10 C24-fatty acids, especially stearic and behenic acid. The esters may also
be prepared
by esterifying polyoxyalkylated alcohols. Preference is given to fully
esterified
polyoxyalkylated polyols having molecular weights of from 150 to 2000,
preferably
from 200 to 600. Particularly suitable are PEG-600 dibehenate and glycerol
ethylene
glycol tribehenate.
Suitable olefin copolymers as a coadditive for the inventive additive
(constituent VII)
may derive directly from monoethylenically unsaturated monomers, or may be
prepared indirectly by hydrogenation of polymers which derive from
polyunsaturated
monomers such as isoprene or butadiene. Preferred copolymers contain, in
addition
to ethylene, structural units which derive from a-olefins having from 3 to 24
carbon
atoms and have molecular weights of up to 120 000 g/mol. Preferred a-olefins
are
propylene, butene, isobutene, n-hexene, isohexene, n-octene, isooctene, n-
decene,
isodecene. The comonomer content of olefins is preferably between 15 and
50 mol%, more preferably between 20 and 35 mol% and especially between 30 and
45 mol%. These copolymers may also contain small amounts, for example up to
10 mol%, of further comonomers, for example nonterminal olefins or
nonconjugated
olefins. Preference is given to ethylene-propylene copolymers. The olefin
copolymers
may be prepared by known methods, for example by means of Ziegler or
metallocene catalysts.
Further suitable olefin copolymers are block copolymers which contain blocks
composed of olefinically unsaturated aromatic monomers A and blocks composed
of
hydrogenated polyolefins B. Particularly suitable block copolymers have the
structure
CA 02573577 2007-01-10
16
(AB)A and (AB)R,, where n is between 1 and 10 and m is between 2 and 10.
The mixing ratio between the inventive additive composed of the graft
copolymers
and the further constituents V, VI and VII is generally in each case between
1:10 and
10:1, preferably in each case between 1: 5 and 5:1, it being possible for one
or two
or all constituent(s) V, VI and VII to be present.
The additives may be used alone or else together with other additives, for
example
with other pour point depressants or dewaxing assistants, with antioxidants,
cetane
number improvers, dehazers, demulsifiers, detergents, lubricity additives,
dispersants, antifoams, dyes, corrosion inhibitors, sludge inhibitors,
odorants and/or
additives for lowering the cloud point.
The inventive additives are suitable for improving the cold flow properties of
fuel oils
of animal, vegetable or mineral origin.
In addition, they disperse the paraffins which precipitate out below the cloud
point in
middle distillates. In particular, they are superior to the prior art
additives in
problematic oils having a low aromatics content of less than 25% by weight, in
particular less than 22% by weight, for example less than 20% by weight, of
aromatics, and thus lower solubility for n-paraffins. Middle distillates refer
in particular
to those mineral oils which are obtained by distillation of crude oil and boil
in the
range from 120 to 450 C, for example kerosene, jet fuel, diesel and heating
oil.
Aromatic compounds refer to the totality of mono-, di- and polycyclic aromatic
compounds, as can be determined by means of HPLC to DIN EN 12916 (2001
edition). The inventive additives are particularly advantageous in those
middle
distillates which contain less than 350 ppm of sulfur, more preferably less
than
100 ppm of sulfur, in particular less than 50 ppm of sulfur and in special
cases less
than 10 ppm of sulfur. They are generally those middle distillates which have
been
subjected to refining under hydrogenating conditions and therefore contain
only small
fractions of polyaromatic and polar compounds. They are preferably those
middle
distillates which have 90% distillation points below 360 C, in particular 350
C and in
special cases below 340 C.
CA 02573577 2007-01-10
17
In view of decreasing world mineral oil reserves and the discussion about the
environmentally damaging consequences of the use of fossil and mineral fuels,
there
is increasing interest in alternative energy sources based on renewable raw
materials. These include in particular native oiis and fats of vegetable or
animal
origin. These are generally triglycerides of fatty acids having from 10 to 24
carbon
atoms and a calorific value comparable to conventional fuels, but are at the
same
time classified as biodegradable and environmentally compatible.
Oils obtained from animal or vegetable material are mainly metabolism products
which include triglycerides of monocarboxylic acids, for example acids having
from
10 to 25 carbon atoms, and corresponding to the formula
H H H
I I
H-C C C-H
I I I
O C R O C R O C R
Ol OI O
where R is an aliphatic radical which has from 10 to 25 carbon atoms and may
be
saturated or unsaturated.
In general, such oils contain glycerides from a series of acids whose number
and
type vary with the source of the oil, and they may additionally contain
phosphoglycerides. Such oils can be obtained by processes known from the prior
art.
As a consequence of the sometimes unsatisfactory physical properties of the
triglycerides, the industry has applied itself to converting the naturally
occurring
triglycerides to fatty acid esters of low alcohols such as methanol or
ethanol. The
prior art also includes mixtures of middle distillates with oils of vegetable
or animal
origin (also referred to hereinbelow as "biofuel oils").
In a preferred embodiment, the biofuel oil, which is frequently also referred
to as
biodiesel or biofuel, comprises fatty acid alkyl esters composed of fatty
acids having
from 12 to 24 carbon atoms and alcohols having from 1 to 4 carbon atoms.
Typically,
CA 02573577 2007-01-10
18
a relatively large portion of the fatty acids contains one, two or three
double bonds.
The biofuel is more preferably, for example, rapeseed oil methyl ester and
especially
mixtures which comprise rapeseed oil fatty acid methyl ester, sunflower oil
fatty acid
methyl ester, palm oil fatty acid methyl ester, used oil fatty acid methyl
ester and/or
soya oil fatty acid methyl ester.
Examples of oils which are derived from animal or vegetable material and which
can
be used in the inventive composition are rapeseed oil, coriander oil, soya
oil,
cottonseed oil, sunflower oil, castor oil, olive oil, peanut oil, maize oil,
almond oil,
palm kernel oil, coconut oil, mustardseed oil, bovine tallow, bone oil and
fish oils.
Further examples include oils which are derived from wheat, jute, sesame, shea
tree
nut, arachis oil and linseed oil, and can be derived therefrom by processes
known
from the prior art. It is also possible to use oils which have been obtained
from used
oils such as deep fat fryer oil. Preference is given to rapeseed oil, which is
a mixture
of fatty acids partially esterified with glycerol, since it is obtainable in
large amounts
and is obtainable in a simple manner by extractive pressing of rapeseeds. In
addition, preference is given to the likewise widely available oils of
sunflowers and
soya, and also to their mixtures with rapeseed oil.
Useful lower alkyl esters of fatty acids are the following, for example as
commercial
mixtures: the ethyl, propyl, butyl and in particular methyl esters of fatty
acids having
from 12 to 22 carbon atoms, for example of lauric acid, myristic acid,
palmitic acid,
paimitolic acid, stearic acid, oleic acid, elaidic acid, petroselic acid,
ricinolic acid,
elaeostearic acid, linoleic acid, linolenic acid, eicosanoic acid, gadoleic
acid,
docosanoic acid or erucic acid, each of which preferably has an iodine number
of
from 50 to 150, in particular from 90 to 125. Mixtures having particularly
advantageous properties are those which comprise mainly, i.e. comprise at
least
50% by weight of, methyl esters of fatty acids having from 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 type mentioned are obtained, for example, by
hydrolyzing and esterifying or by transesterifying animal and vegetable fats
and oils,
by transesterifying them with lower aliphatic alcohols. To prepare lower alkyl
esters
CA 02573577 2007-01-10
19
of fatty acids, it is advantageous to start from fats and oils having a high
iodine
number, for example sunflower oil, rapeseed oil, coriander oil, castor oil,
soya oil,
cottonseed oil, peanut oil or bovine tallow. Preference is given to lower
alkyl esters of
fatty acids based on a novel type of rapeseed oil, whose fatty acid component
is
derived to an extent of more than 80% by weight from unsaturated fatty acids
having
18 carbon atoms.
When mixtures of middle distillate of mineral origin (A) and biofuels (B) are
used, the
A:B mixing ratio of the constituents may vary as desired. It is preferably
between A:B
= 99.9:0.1 and 0.1:99.9, in particular from 99:1 to 1:99, especially from 95:5
to 5:95,
for example from 85:15 to 15:85 or from 80:20 to 20:80.
It is also possible to use mixtures of synthetic fuels, as are obtainable, for
example,
from the Fischer-Tropsch process, and a middle distillate of mineral origin A
and/or a
biofuel B as the fuel oil composition.
Examples
Table 1: Characterization of the test oils:
The test oils employed were current oils from European refineries. The CFPP
value
was determined to EN 116 and the cloud point to ISO 3015. The aromatic
hydrocarbon groups were determined to DIN EN 12916 (November 2001 edition).
CA 02573577 2007-01-10
Test oil 1 Test oil 2 Test oil 3
Distillation
IBP [ C] 166.3 C 173.8 C 240.7
90% - 20% cut [ C] 147 C 117 C 64.4
FBP [ C] 377.9 C 345.7 C 345.7
Cloud Point [ C] -8.0 -6.7 -8.2
CFPP [ C] -11.0 -8.0 -11
Sulfur [ppm] 308 210 1450
Density @15 C [g/cm3] 0.826 0.831 0.841
Aromatics content [% by wt.] 18.73 27.50 24.16
of which mono [% by wt.] 14.31 22.22 15.76
di [% by wt.] 3.93 4.83 7.93
poly [% by wt.] 0.49 0.46 0.47
The following additives were used:
5 Characterization of the ethylene copolymers used as flow improvers
(constituent III)
The ethylene copolymers used were commercial products having the properties
reported in Table 2. The products were used in the form of 65% and 50%
dilutions in
kerosene.
10 The viscosity was determined to ISO 3219/B with a rotational viscometer
(Haake
RV20) with plate-cone measuring system at 140 C.
Table 2: Characterization of the ethylene copolymers used (constituent III)
Example Comonomer(s) V140 CH3/100 CH2
Al 13.6 mol% of vinyl acetate 130 mPas 3.7
A2 14.5 mol% of vinyl acetate and 105 mPas 5.3
1.4 mol% of vinyl neodecanoate
A3 11.2 mol% of vinyl acetate 220 mPas 6.2
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Characterization of the alkylphenol-aidehyde resins used (constituent II):
B1) nonylphenol-formaidehyde resin, Mw 2000 g/mol
B2) dodecylphenol-formaldehyde resin, Mw 4000 g/mol
B3) C20124 alkylphenol-formaidehyde resin, Mw 3000 g/mol
Table 3: Characterization of the graft copolymers with acrylates.
The K values reported were measured according to Ubbelohde in 5% by weight
solution in toluene at 25 C.
Example Base polymer Acrylic ester K value
1(C) Ethylene-vinyl acetate with 13.3 mol% of vinyl Tetradodecyl 23.8
acetate acrylate
2 (C) Ethylene-vinyl acetate with 11.2 mol% of vinyl Tetradodecyl 23.8
cetate acrylate
3 Ethylene-vinyl neodecanoate with 7.1 mol% of Tetradodecyl 22.5
inyl neodecanoate acrylate
4 (C) Ethylene-vinyl acetate-propylene with 14 mol% Tetradodecyl 20.8
f vinyl acetate and 11 mol% of propylene acrylate
5 Ethylene-vinyl neodecanoate with 3.7 mol% of Tetradodecyl 21.8
inyl neodecanoate acrylate
6 Ethylene-vinyl neodecanoate with 7.1 mol% of Behenyldodecyl 21.8
inyl neodecanoate acrylate
7 Ethylene-vinyl neodecanoate with 3.7 mol% of Behenyldodecyl 22.9
inyl neodecanoate acrylate
"Tetradodecyl" represents a mixture of tetradecyl and dodecyl
"Behenyldodecyl" represents a mixture of behenyl and dodecyl
Table 4: Characterization of the graft copolymers with methacrylates
(comparison)
The K values reported were measured according to Ubbelohde in 5% by weight
solution in toluene at 25 C.
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Example Base polymer Methacrylic este K value
8 (C) Ethylene-vinyl neodecanoate with 7.1 mol% Tetradodecyl 21.8
of vinyl neodecanoate methacrylate
Effectiveness of the additives as cold flow improvers
To assess the effect of the inventive additives on the coid flow properties of
middle
distillates, the inventive additives were tested in middle distillates as
follows in the
short sediment test:
150 ml of the middle distillates admixed with the additive components
specified in the
table were cooled in 200 ml measuring cylinders in a cold cabinet at -2 C/hour
to -
13 C and stored at this temperature for 16 hours. Subsequently, volume and
appearance, both of the sedimented paraffin phase and of the oil phase above
it,
were determined and assessed visually. A small amount of sediment and an
opaque
oil phase show good paraffin dispersancy.
In addition, the lower 20% by volume is isolated and the cloud point is
determined to
ISO 3015. Only a slight deviation of the cloud point of the lower phase (CPcc)
from
the blank value of the oil shows good paraffin dispersancy.
The graft copolymers reported are used in an amount of 100-150 ppm. A
dispersant
is used generally in the presence of a cold flow improver. In addition to the
graft
polymer, appropriate cold flow improvers were therefore used.
Results in Test oil 1
The CFPP effectiveness and dispersing action of the inventive graft polymers
(constituent I) were determined in a composition of (by parts by weight)
3:0.5:1 of
constituents 111:11:1.
Alkylphenol-aidehyde resin: (constituent fl): B1
Flow improver (constituent III): Al
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Table 5
Graft CFPP CPcc
Example copolymer [OCI [OCI Visual assessment
of Example
9 (C) 1 -22 -7.0 Homogeneously opaque, 2 ml of sediment
(C) 2 -22 -7.4 Homogeneously opaque, no sediment
11 3 -27 -7.3 Homogeneously opaque, no sediment
12 (C) 4 -22 -7.1 Homogeneously opaque, 1 ml of sediment
13 5 -24 -7.2 Homogeneously opaque, no sediment
14 6 -23 -7.4 Homogeneously opaque, no sediment
7 -23 -6.9 Homogeneously opaque, 2 ml of sediment
16 (C) 8 -24 -4.9 17 ml of sediment, remainder clear
Results in Test oil 2
5
The CFPP effectiveness and dispersing action of the inventive graft polymers
(constituent I) were determined in a composition of (by parts by weight)
3:0.5:1 of
constituents III:II:I.
Alkylphenol-aidehyde resin: (constituent II): B2
10 Flow improver (constituent III): mixture of 10% Al and 25% A2
Table 6
Graft
CFPP CPcc
Visual assessment
Example copolymer [OCI [OCI
of Example
17 (C) 1 -22 -6.5 Homogeneously opaque, no sediment
18 (C) 2 -22 -6.4 Homogeneously opaque, no sediment
19 3 -26 -6.0 Homogeneously opaque, no sediment
20(C) 4 -22 -5.1 Homogeneously opaque, 2 ml of sediment
21 (C) 5 -23 -6.1 Homogeneously opaque, no sediment
22 (C) 6 -27 -5.5 Homogeneously opaque, 3 ml of sediment
CA 02573577 2007-01-10
24
Graft
CFPP CPcc
Example copolymer (oC, toC, Visual assessment
of Example
23 7 23 -6.1 Homogeneously opaque, no sediment
F 24(C) 8 -21 -3.5 20 ml of sediment, remainder clear
Results in Test oil 3
The CFPP effectiveness and dispersing action of the inventive graft polymers
(constituent I) were determined in a composition of (by parts by weight)
4:0.5:1 of
constituents 111:11:1.
Alkylphenol-aldehyde resin: (constituent II): B1
Flow improver (constituent III): mixture of 10% A2 and 15% A3
Table 7
Graft
CFPP CPcc
Example copolymer of ~oC~ ~oC, Visual assessment
Example
25 (C) 1 -23 -7.9 Homogeneously opaque, no sediment
26 (C) 2 -20 -7.9 Homogeneously opaque, no sediment
27 3 -25 -7.9 Homogeneously opaque, no sediment
28 (C) 4 -20 -8.1 Homogeneously opaque, no sediment
29 5 -22 -8.0 Homogeneously opaque, no sediment
30 6 -25 -7.5 Homogeneously opaque, no sediment
31 7 -26 -7.8 Homogeneously opaque, no sediment
32(C) 8 -20 -3.9 20 ml of sediment, remainder clear
