New compositions for reducing crystallization of paraffin crystals in fuels

Description

The present invention relates to new compositions and the use of certain of their components for reducing crystallization of paraffin crystals in fuels.

Middle distillate fuels of fossil origin, especially gas oils, diesel oils or light heating oils, which are obtained from mineral oil, have different contents of paraffins according to the origin of the crude oil. At low temperatures, there is precipitation of solid paraffins at the cloud point ("CP"). It is thought that, in the course of further cooling, the platelet-shaped n-paraffin crystals form a kind of "house of cards structure" and the middle distillate fuel ceases to flow even though its predominant portion is still liquid. The precipitated n-paraffins in the temperature range between cloud point and pour point ("PP") considerably impair the flowability of the middle distillate fuels; the paraffins block filters and cause irregular or completely interrupted fuel supply to the combustion units. Similar disruptions occur in the case of light heating oils.

It has long been known that suitable additives can modify the crystal growth of the n-paraffins in middle distillate fuels. Additives of good efficacy prevent middle distillate fuels from already solidifying at temperatures a few degrees Celsius below the temperature at which the first paraffin crystals crystallize out. Instead, fine, readily crystallizing, separate paraffin crystals are formed, which, even when the temperature is lowered further, pass through the filters in motor vehicles and heating systems, or at least form a filtercake which is permeable to the liquid portion of the middle distillates, so that disruption-free operation is assured. The efficacy of the flow improvers is typically expressed, in accordance with European standard EN 116, indirectly by measuring the cold filter plugging point ("CFPP"). Cold flow improvers or middle distillate flow improvers ("MDFIs") of this kind which are used have long included, for example, ethylene-vinyl carboxylate copolymers such as ethylene-vinyl acetate copolymers ("EVA").

One disadvantage of these additives when used in middle distillate fuels is that the paraffin crystals modified in this way, because of their higher density compared to the liquid portion, have a tendency to settle out more and more at the base of the fuel container, for example the reservoir tank, in the course of storage of the middle distillate fuel. This results in formation of a homogeneous low-paraffin phase in the upper part of the vessel and a biphasic paraffin-rich layer at the base. Since the fuel is usually drawn off not very far above the base of the container both in motor vehicle tanks and in storage or supply tanks belonging to mineral oil dealers, there is the risk that the high concentration of solid paraffins will lead to blockages of filters and meter- ing units. The further the storage temperature drops below the precipitation temperature of the paraffins, the greater this risk becomes, since the amount of paraffin precipitated increases with falling temperature. The additional use of paraffin dispersants or wax anti-settling additives ("WASAs") can reduce the problems outlined.

WO 07/147753 discloses the use of mixtures comprising polar oil-soluble nitrogen compounds as paraffin dispersant for fuels. It is a disadvantage of the mixtures according to WO 07/147753 that two-component mixtures of components (a) and (b) according to WO 07/147753 are not stable but require the presence of a third component (c) according to WO 07/147753 to yield stable mixtures. Component (c) according to WO 07/147753 needs to be prepared by reaction of tridecylamine with maleic anhydride.

It is one object of the present invention to find commercially available alternatives to that component (c) of WO 07/147753 in order to avoid costly synthesis of such a component.

WO 16/083130 and WO 17/202642 describe copolymers of unsaturated dicarboxylic acid or derivatives thereof, a-olefins and optionally alkyl esters of acrylic acid or methacrylic acid as cold flow improvers and for reducing paraffin crystals in fuels.

Despite the efficiency of such copolymers in fuels there is still a demand for further improvement of the activity of such copolymers in fuels.

Antistatic agents are often admixed to fuels or hydrocarbon distillation liquids in refineries in order to increase the electric conductivity, e.g. against electrostatic charge or for detecting the level in distillation towers or tanks with sensor using electric conductivity.

Usually, the electric conductivity of fuels is in the range of 3 to 5 pS/m respectively in the case of distillation liquids is adjusted to a range of 30 pS/m or higher using such antistatic agents.

Examples for antistatic agents are disclosed in WO 08/107371. A use as cold flow improvers and wax anti settling improver is not disclosed.

The International Application WO 2022/218737 (application number PCT/EP2022/058863, filing date April 4, 2022) discloses mixtures of copolymers of unsaturated dicarboxylic acid or derivatives thereof, a-olefins and optionally alkyl esters of acrylic acid or methacrylic acid and antistatic agents for reducing paraffin crystals in fuels. It is a common observation that wax anti-settling additives ("WASAs") tend to lose performance activity on storage.

The problem underlying the present invention was to provide mixtures of wax anti-settling additives with easy to synthesise components which exhibit a comparable activity in reducing paraffin crystals in fuels and which are more stable on storage.

The problem was solved by a composition for reducing the crystallization of paraffin crystals in fuels comprising

(I) at least one oil-soluble reaction product based on poly(C2- to C2o-carboxylic acids) which has at least one tertiary amino group and are of the general formula (1) or (2)

(2) in which the variable A is a straight-chain or branched C2- to Ce-alkylene group or is the moiety of the formula (3) and the variable B is a Ci- to Cig-alkylene group, and

(II) as antistatic agent

(F) at least one copolymer of sulfur dioxide with one or more linear or branched 1 -olefins having from 2 to 24 carbon atoms, and (III) at least one carboxylic acid comprising 8 to 40 carbon atoms per carboxylic acid group, with the proviso that no copolymer (IV) obtainable by copolymerization of

(A) at least one unsaturated dicarboxylic acid or derivatives thereof,

(B) at least one a-olefin having from at least 6 up to and including 20 carbon atoms,

(C) optionally at least one C3- to C2o-alkyl ester of acrylic acid or methacrylic acid or a mixture of such alkyl esters and

(D) optionally one or more further copolymerizable monomers other than monomers (A), (B) and (C), followed by the reaction with at least one dialkylamine (E), where the two alkyl radicals in the at least one dialkylamine (E) are independently alkyl radicals having at least 17 up to 30 carbon atoms wherein derivatives of monomer (A) are

- anhydrides,

- mono- or dialkyl esters,

- mixed esters or

- mono- or diamides or imides, is present.

For the sake of clarity absence of copolymer (IV) according to the present invention shall mean less than 10 ppm, preferably not more than 8, more preferably not more than 5, and even more preferably not more than 3 ppm down to 0 ppm.

Another object of the present invention is the use of such compositions for reducing the crystallization of paraffin crystals in fuels and/or for improving the cold flow properties of fuels and/or for improving the filterability of fuel oils, optionally and preferably together with at least one wax anti-settling additive.

Another object of the present invention is a fuel comprising the above-mentioned compositions.

Optionally the compositions according to the invention may comprise solvents and/or further additives typical for fuel additives. Preferably the compositions according to the present invention comprise at least one solvent and at least one flow improver (see below).

Component (I)

Component (I) is at least one oil-soluble reaction product based on poly(C2- to C2o-carboxylic acids) which has at least one tertiary amino group and are of the general formula (1) or (2)

B B HOOC' "N' 'COOH i B"COOH (2) in which the variable A is a straight-chain or branched C2- to Ce-alkylene group or is the moiety of the formula (3) and the variable B is a Ci- to Cig-alkylene group.

Moreover, the preferred oil-soluble reaction product of component (I), especially that of the general formula (1) or (2), is an amide, an amide ammonium salt or an ammonium salt, in which no, one or more carboxylic acid groups have been converted to amide groups. Preferably, at least one of the carboxylic acid groups has been converted to an amide group.

Straight-chain or branched C2- to Ce-alkylene groups of the variables A are, for example, 1 ,2- ethylene, 1 ,2-propylene, 1 ,3-propylene, 1 ,2-butylene, 1 ,3-butylene, 1 ,4-butylene, 2-methyl-1 ,3- propylene, 1 ,5-pentylene, 2-methyl-1 ,4-butylene, 2,2-dimethyl-1 ,3-propylene, 1 ,6-hexylene (hexamethylene) and, in particular, 1 ,2-ethylene or 1 ,3-propylene and especially 1 ,2-ethylene. Variable A preferably comprises from 2 to 4, in particular 2 or 3 carbon atoms.

Ci- to Cig-alkylene groups of the variables B are, for example, methylene, 1 ,2-ethylene, 1 ,3- propylene, 1 ,4-butylene, 1 ,5-pentylene, 1 ,6-hexamethylene, octamethylene, decamethylene, dodecamethylene, tetradecamethylene, hexadecamethylene, octadecamethylene, nonadeca- methylene and in particular methylene or 1 ,2-ethylene and especially methylene. Variable B comprises preferably from 1 to 10, in particular, from 1 to 4 carbon atoms.

The primary and secondary amines as a reactant for the polycarboxylic acids to form component (I) are typically monoamines, especially aliphatic monoamines. These primary and secondary amines may be selected from a multitude of amines which bear hydrocarbon radicals optionally joined to one another.

In a preferred embodiment, these amines underlying the oil-soluble reaction products of component (I) are secondary amines and have the general formula HNR2 in which the two variables R are each independently straight-chain or branched C10- to Cso-alkyl radicals, in particular straight-chain C14- to C24-alkyl radicals. These relatively long-chain alkyl radicals are preferably straight-chain or branched only to a slight degree, more preferably straight-chain. In general, the secondary amines mentioned, with regard to their relatively long-chain alkyl radicals, derive from naturally occurring fatty acid or from derivatives thereof. The two R radicals are preferably identical.

Examples for the radicals R are n-decyl, 2-propylheptyl, n-undecyl, iso-undecyl, n-dodecyl, n- tridecyl, isotridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, iso-heptadecyl, n- octadecyl, n-nonadecyl, n-eicosyl, n-heneicosyl, n-docosyl, n-tricosyl, n-tetracosyl, oleyl, linolyl or linolenyl. Preferably the radicals R are selected from the group consisting of n-dodecyl, n- tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, and mixtures thereof.

Preferably the secondary amines are selected from the group consisting of dioleylamine, dipal- mitamine, dicoconut fatty amine, distearylamine, dibehenylamine or in particular ditallow fatty amine.

The secondary amines mentioned may be bonded to the polycarboxylic acids by means of amide structures or in the form of the ammonium salts; it is also possible for only a portion to be present in the form of amide structures and another portion in the form of ammonium salts. Preferably only a few, if any, acid groups are present. In a preferred embodiment, the oil-soluble reaction products of component (I) are present fully in the form of the amide structures.

Typical examples for component (I) are reaction products of nitrilotriacetic acid, of ethylenediaminetetraacetic acid or of propylene-1 ,2-diaminetetraacetic acid with, in each case, from 0.5 to 1.5 mol per carboxyl group, in particular from 0.8 to 1.2 mol per carboxyl group, of dioleylamine, dipalmitamine, dicoconut fatty amine, distearylamine, dibehenylamine or in particular ditallow fatty amine. A particularly preferred component (I) is the reaction product formed from 1 mol of ethylenediaminetetraacetic acid and 4 mol of hydrogenated ditallow fatty amine.

Further typical examples of component (I) include the N,N-dialkylammonium salts of 2-N’,N’- dialkylamidobenzoates, for example the reaction product formed from 1 mol of phthalic anhydride and 2 mol of ditallow fatty amine, the latter being hydrogenated or unhydrogenated, and the reaction product of 1 mol of an alkenyl-spiro-bislactone with 2 mol of a dialkylamine, for example ditallow fatty amine and/or tallow fatty amine, the latter two compounds being hydrogenated or unhydrogenated.

Cold flow improvers of this kind are described, for example, in WO 2007/147753, particularly at page 13 line 1 to page 16 - 32 therein, which is hereby incorporated into the present disclosure by reference.

Compound (I) is added to the fuels so that the middle distillate fuels comprise the compound in an amount of typically 10 to 5000 ppm by weight, preferably of 20 to 3000 ppm by weight, especially of 30 to 2000 ppm by weight and in particular of 50 to 1000 ppm by weight.

Antistatic agent (II)

The antistatic agent is (F) a copolymer of sulfur dioxide with one or more linear or branched 1- olefins having from 2 to 24 carbon atoms.

Component (F)

The structure and the known preparation processes for the olefin-sulfur dioxide copolymer of component (F) are described in documents IIS-A 3 917 466, IIS-A 4 416 668, and WO 08/107371. Component (F) is preferably a copolymer of sulfur dioxide with one or more linear or branched 1 -olefins having from 2 to 24 carbon atoms. Typically, the copolymers (polysulfones) of component (F) are alternating 1 :1 copolymers in which one sulfone unit generally follows one olefin unit; it is also possible for sequences of two or more olefin units to occur in small amounts. Some of the olefin monomers may be replaced by ethylenically unsaturated carboxylic acids (e.g. acrylic acid, methacrylic acid or vinylacetic acid) or ethylenically unsaturated dicarboxylic acids (e.g. maleic acid or fumaric acid) or derivatives thereof (e.g. maleic anhydride), so that the copolymer of component (F) is formed especially from 50 mol% of sulfur dioxide or sulfone units, from 40 to 50 mol% of olefin units and from 0 to 10 mol% of units from said ethylenically unsaturated carboxylic acids, ethylenically unsaturated dicarboxylic acids or derivatives thereof.

Useful branched and especially linear 1-olefins having from 2 to 24 carbon atoms for preparing component (F) include, for example, ethene, propene, 1 -butene, 2-butene, isobutene, 1- pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1- tridecene, 1 -tetradecene, 1 -pentadecene, 1 -hexadecene, 1 -heptadecene, 1 -octadecene, 1- nonadecene, 1-eicosene, 1-heneicosene, 1-docosene, 1-tricosene, 1-tetracosene or mixtures thereof.

Particular preference is given to linear 1-olefins having from 6 to 16 carbon atoms, especially having from 8 to 14 carbon atoms, or linear 1-olefins having from 12 to 22 carbon atoms, especially from 14 to 20 carbon atoms, and also mixtures thereof, for example a mixture of 1- dodecene and 1 -tetradecene. It may also be advantageous to use mixtures of low molecular weight and high molecular weight 1-olefins, i.e. 1-olefin mixtures with a bimodal distribution, to prepare component (F), for example mixtures of 1-olefins having from 6 to 13 carbon atoms and 1-olefins having from 14 to 20 carbon atoms, or mixtures of 1-olefins having from 6 to 10 carbon atoms and 1-olefins having from 11 to 15 carbon atoms, or mixtures of 1-olefins having from 2 to 24 carbon atoms and a single 1-olefin having from 4 to 10 carbon atoms. When technical or other 1-olefin mixtures are used, the specification of the carbon atoms within the ranges specified above is based on the mean carbon atom number of these mixtures, where the mean carbon atom number is the sum over the mathematical products of fraction by weight and corresponding carbon atom number of all 1-olefins present in the mixture.

The olefin-sulfur dioxide copolymer of component (F) typically has a number-average molecular weight M _n of from 2000 to 1 000 000, especially from 4000 to 100 000, in particular from 6000 to 25 000. The polydispersity (PDI = M _w /M _n ) is generally in the range from 1.1 to 30, especially from 1.5 to 20, in particular from 2 to 10, most preferably from 2.3 to 5.

US-A 3 917 466 recommends the preparation of the olefin-sulfur dioxide copolymers by a suitable free-radical polymerization process in the temperature range from 0 to 50°C; the solvents to be used are benzene, toluene or xylene; only a low molar excess of sulfur dioxide (a maximum of 1 .5 times the molar amount) is employed; free-radical initiators such as peroxides or azo compounds and the additional irradiation with actinic light are recommended. According to document US-A 4 416 668, the olefin-sulfur dioxide copolymers can be prepared by emulsion polymerization processes in aqueous medium. Both preparation methods are, however, in need of improvement, and the use of the olefin-sulfur dioxide copolymers thus obtained in the inventive additive formulation leads to disadvantages in their handling and efficacy. In particular, the content of volatile and combustible starting olefins is still too high, such that the flashpoint of the resulting antistat additive formulation is too low. There was thus the need for an improved preparation process for the olefin-sulfur dioxide copolymers in order to make their use in the inventive additive formulation problem-free.

Dosage of component (F) in fuels is often accompanied by a further component (F1) comprising one or more basic nitrogen atoms and having at least one relatively long-chain linear or branched hydrocarbon radical having at least four carbon atoms or an equivalent structural element which ensures the solubility of component (F) in the fuel.

The at least one antistatic agent is added to the fuel in an amount so that the electrical conductivity according to ASTM 2624 of the fuel (absent any other additives) is raised to 30 to 1000 pS/m, preferably from 40 to 900 pS/m, more preferably from 50 to 800 pS/m and especially from 60 to 700 pS/m.

Such electrical conductivity is much higher than usually necessary for antistatic activity, however, in these amounts the at least one antistatic agent takes full effect as cold flow improver.

In order to achieve the above-mentioned electrical conductivity the at least one antistatic agent is typically added to the fuels so that the middle distillate fuels comprise the antistatic agent in an amount of typically 0.5 to 150 ppm by weight, preferably of 1 to 125 ppm by weight, especially of 3 to 100 ppm by weight and in particular of 3 to 75 ppm by weight.

Component (III) is at least one carboxylic acid comprising 8 to 40 carbon atoms per carboxylic acid group, preferably comprising 8 to 30, even more preferably 9 to 26, and especially 9 to 20 carbon atoms.

Component (III) does not comprise heteroatoms other than carbon and hydrogen and the oxygen atoms in the carboxylic acid group (-COOH), preferably component (III) is an aromatic or aliphatic carboxylic acid, more preferably an alkane-, alkene- Oder alkadiene- mono-, di- or polycarboxylic acid.

The carboxylic acid (III) may bear one or more carboxylic acid groups, preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. In one embodiment carboxylic acid (III) may be a dicarboxylic acid. In this case the number of carbon atoms including the carboxylic acid groups is 16 to 80, preferably 16 to 60, even more preferably 18 to 52, and especially 18 to 40.

Examples of dicarboxylic acids are succinic acids bearing a polypropenyl, polybutenyl or poly- isobutenyl radical with a number-average molecular weight M _n of preferably in each case 168 to 1050 g/mol and more preferably 196 to 1050. Such polypropenyl-, polybutenyl- or polyisobu- tenyl-substituted succinic acids are obtainable by reaction of polypropene, polybutene or polyisobutene with the respective molecular weight with maleic acid anhydride and subsequent hydrolysis of the anhydride functional group. Preferred examples of such substituted succinic acids are dodecenyl succinic acid, hexadecenyl succinic acid, eicosenyl succinic acid, and poly- isobutenyl succinic acid based on polyisobutene with an average molecular weight of approximately 550, 750 or 1000 g/mol.

More preferred examples of dicarboxylic acids are thapsic acid (hexadecanedioic acid), japanic acid (heneicosanedioic acid), phellogenic acid (docosanedioic acid), and very preferably dimer fatty acids namely dimers of unsaturated monocarboxylic acids, especially compositions of dimer fatty acid predominantly containing a dimer of stearic acid (CAS 61788-89-4) and even the trimer (CAS 68937-90-6). Dimerisation respectively oligomerisation usually takes place via Diels-Alder reaction so that the dimers typically comprise at least one substituted cyclohexene substructure. It is also possible that oligomerisation takes place via Alder ene-reaction or radical oligomerisation.

In another embodiment the carboxylic acid (III) may be a tall oil resin acid composition which naturally originates from tree resins, especially conifer resins from pines or spruces, is formed from one or preferably more than one so-called resin acid. Resin acids are carboxyl-containing polycyclic hydrocarbon compounds. They include, as the most important representatives, abietic acid, dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid and levopimaric acid. These resin acids may partly also be present in oxidized form as so-called oxy acids.

The carboxylic acid (III) is preferably a monocarboxylic acid.

The carboxylic acid may be branched or linear and may be saturated or one- or multifold unsaturated, preferably saturated. It is also possible to use a mixture of aliphatic monocarboxylic acids, especially from natural and renewable sources, e.g. animal or preferably vegetable oil. Such mixtures of aliphatic monocarboxylic acids are usually obtained by saponification of natural oils and yield mixtures of aliphatic monocarboxylic acids with different number of carbon atoms depending on the source and origin of the natural oil. Preferred are linseed oil, coconut fat, palm kernel oil, palm oil, soy bean oil, peanut oil, cocoa butter, shea butter, cotton seed oil, corn oil, sunflower oil, rapeseed oil or castor oil.

Examples for aliphatic monocarboxylic acids are dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), isostearic acid, oleic acid, linoleic acid, linolaidic acid, erucic acid, arachidic acid, behenic acid, lignoceric acid and cerotic acid, preferred are tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), isostearic acid, oleic acid, linoleic acid, linolaidic acid, erucic acid, arachidic acid, and behenic acid, very preferred are hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), isostearic acid, oleic acid, linoleic acid, linolaidic acid, and mixtures thereof, and especially oleic acid, linoleic acid, and linolaidic acid. Oleic acid is especially preferred.

Possible is also a composition of tall oil fatty acids which usually comprises palmitic acid, oleic acid, and linoleic acid.

Examples of branched non-fatty acids as monocarboxylic acids (III) are 2-ethyl hexanoic acid, 2,2-dimethylhexanoic acid (neooctanoic acid, Versatic Acid 8), 2,2-dimethylheptanoic acid (ne- ononanoic acid, Versatic Acid 9), isononanoic acid, 2-propyl heptanoic acid, 2,2- dimethyloctanoic acid (neodecanoic acid, Versatic Acid 10), neoundecanoic acid (Versatic Acid 11), neododecanoic acid, and neotridecanoic acid (Versatic Acid 13). The neoalkanoic acids comprising 8 to 13 carbon atoms may be mixtures of isomers and not necessarily pure isomers. For example, neodecanoic acid may be a mixture of carboxylic acids (CAS 26896-20-8) comprising 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2-isopropylpentanoic acid, 2,5-dimethyl- 2-ethylhexanoic acid, 2,2-dimethyloctanoic acid, and/or 2,2-diethylhexanoic acid. It is a feature of such neoalkanoic acids that the carboxylic acid group is bound to a carbon atom (quaternary carbon atom) which further bears three alkyl groups, preferably one methyl group and two alkyl groups.

In a preferred embodiment the carboxylic acid (III) is isononanoic acid. As used herein, isononanoic acid refers to one or more branched-chain aliphatic carboxylic acids with 9 carbon atoms. Embodiments of isononanoic acid may include 7-methyloctanoic acid (e.g., CAS Nos. 693-19-6 and 26896-18-4), 6,6-dimethylheptanoic acid (e.g., CAS No. 15898-92-7), 3,5,5- trimethylhexanoic acid (e.g., CAS No. 3302-10-1), 3,4,5-trimethylhexanoic acid, 2,5,5- trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid (e.g., CAS No. 3302-12-3) and combinations thereof. In a preferred embodiment, isononanoic acid has as its main component greater than 90% of one of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5- trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, and 2,2,4,4- tetramethylpentanoic acid. The balance of the isononanoic acid may include other nine carbon carboxylic acid isomers and minor amounts of one or more contaminants. In a preferred embodiment, the isononanoic acid has as its main component greater than 90% of 3,5,5- trimethylhexanoic acid and even more preferably, the main component is greater than 95% 3,5,5-trimethylhexanoic acid.

Examples for aromatic carboxylic acids are alkyl- or alkenyl-substituted benzoic acids, phthalic acid isomers, and naphthalene carboxylic acids comprising 8 to 40 carbon atoms per carboxylic acid group.

Preferred examples are wherein

R ¹ is a Ce- to C2o-alkyl group.

More preferred are 4-alkyl benzoic acids, alkyl-substituted phthalic acid, alkyl-substituted isophthalic acid, alkyl-substituted terephthalic acid, and alkyl-substituted 1- or 2- naphthalene carboxylic acids.

Compound (III) is added to the fuels so that the middle distillate fuels comprise the compound in an amount of typically 10 to 5000 ppm by weight, preferably of 20 to 3000 ppm by weight, especially of 30 to 2000 ppm by weight and in particular of 50 to 1000 ppm by weight.

Copolymer (IV) The compositions according to the invention do not comprise any copolymer (IV) which is described in more detail:

Monomer (A) comprises at least one, preferably one to three, more preferably one or two and most preferably exactly one unsaturated dicarboxylic acid(s) or derivatives thereof.

Derivatives are understood to mean

- the anhydrides in question, in monomeric or else polymeric form,

- mono- or dialkyl esters, preferably mono- or di-Ci-C4-alkyl esters, more preferably mono- or dimethyl esters or the corresponding mono- or diethyl esters,

- mixed esters, preferably mixed esters having different Ci-C4-alkyl components, more preferably mixed methyl ethyl esters, and

- mono- and diamides, and also imides, obtainable by reaction of the unsaturated dicarboxylic acid with primary amines or secondary amines, preferably Ci-Cso-alkylamines or di-Ci-Cso- alkylamines.

The derivatives are preferably anhydrides in monomeric form or di-Ci-C4-alkyl esters, more preferably anhydrides in monomeric form.

In a further preferred embodiment, the derivatives are di- or monoamides, preferably monoamides, obtainable by reaction of the unsaturated dicarboxylic acid with dialkylamines (E) wherein the alkyl radicals independently have at least 17 up to 30 carbon atoms.

In the context of this document, Ci-C4-alkyl is understood to mean methyl, ethyl, /so-propyl, n- propyl, n-butyl, /so-butyl, sec-butyl and terf-butyl, preferably methyl and ethyl, more preferably methyl.

The unsaturated dicarboxylic acid comprises those dicarboxylic acids or derivatives thereof in which the two carboxyl groups are conjugated to the ethylenically unsaturated double bond.

Examples thereof are maleic acid, fumaric acid, 2-methylmaleic acid, 2,3-dimethylmaleic acid, 2-methylfumaric acid, 2,3-dimethylfumaric acid, methylenemalonic acid and tetrahydrophthalic acid, preferably maleic acid and fumaric acid and more preferably maleic acid, and derivatives thereof.

Monomer (A) is especially maleic anhydride. Monomer (B) comprises at least one, preferably one to four, more preferably one to three, even more preferably one or two and especially exactly one a-olefin(s) having from at least 6 up to and including 20 carbon atoms. The a-olefins (B) preferably have at least 8, more preferably at least 10, carbon atoms. The a-olefins (B) preferably have up to and including 18, more preferably up to and including 16 and most preferably up to and including 14 carbon atoms.

If monomer (B) is a mixture of different olefins, the determination of the number of carbon atoms should be based on the statistical average of the numbers of carbon atoms in the olefins present in the mixture. Accordingly, a mixture of 50 mol% of C22 olefin and 50 mol% of C olefin has a statistical average of 19 carbon atoms.

In a preferred embodiment, however, essentially all the a-olefins present in the mixture have the above-specified number of carbon atoms, preferably at least 90 mol%, more preferably at least 95 mol% and most preferably at least 98 mol%.

The a-olefins may preferably be linear or branched, preferably linear, 1-alkenes.

Examples thereof are 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1- dodecene, 1-tridecene, 1 -tetradecene, 1 -pentadecene, 1-hexadecene, 1 -heptadecene, 1- octadecene, 1-nonadecene and 1-eicosene, of which preference is given to 1-decene, 1-dodecene, 1 -tetradecene and 1-hexadecene and particular preference to 1-dodecene.

Optional monomer (C) is at least one, preferably one to four, more preferably one to three, even more preferably one or two and especially exactly one C4- to C2o-alkyl ester(s) of acrylic acid or methacrylic acid, preferably of acrylic acid, or a mixture of such alkyl esters. The alkyl radical in each case may be straight-chain or branched.

Suitable C3- to C2o-alkyl esters of acrylic acid or methacrylic acid, preferably of acrylic acid, for component (C) are preferably the esters of acrylic acid and methacrylic acid with C3- to C18- alkanols, preferably with C4- to Cis-alkanols, more preferably with Cs- to Cie-alkanols, even more preferably C10- to Ci4-alkanols and especially Ci2-alkanols, for example with n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, n-pentanol, tert-pentanol, n- hexanol, n-heptanol, n-octanol, 2-ethylhexanol, n-nonanol, isononanol, n-decanol, 2- propylheptanol, n-undecanol, isoundecanol, n-dodecanol, n-tridecanol, isotridecanol, 3, 3, 5,5,7- pentamethyloctanol, n-tetradecanol, n-pentadecanol, n-hexadecanol, n-heptadecanol, iso- heptadecanol, 3,3,5,5,7,7,9-heptamethyldecanol, n-octadecanol and n-eicosanol. Also conceivable are mixtures of Cv-alkanols, as described in WO 2009/124979.

In one embodiment, the alkanols are branched C13- or Cn-alkanols or mixtures thereof having a mean degree of branching according to the iso index of 1.2 to 3.0, especially of 1.7 to 2.5.

Alkanols of this kind or mixtures thereof are obtainable by oligomerization of C4 hydrocarbon streams, especially homogeneously or heterogeneously catalyzed oligomerization of technical grade C4 streams composed of 10% to 90% by weight of butane, 10% to 90% by weight of linear butenes (butene-1 , cis- and trans-butene-2) and 1 % to 5% by weight of isobutene, for example of raffinate II. A heterogeneous catalyst typical for this purpose comprises nickel. The oligomerization is usually conducted at temperatures of 30 to 280°C and pressures of 10 to 300 bar. Oligomerization reactions of this kind are described, for example, in WO 99/25668. The oligomerization products are subsequently hydroformylated and hydrogenated and thus give rise to the alkanols or alkanol mixtures mentioned.

Component (C) is preferably n-decyl (meth) aery I ate, 2-propylheptyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, isotridecyl (meth)acrylate or n-tetradecyl (meth)acrylate, more preferably n-dodecyl (meth)acrylate or n-tetradecyl (meth)acrylate or mixtures thereof and most preferably the respective acrylates.

The optional further monomers (D), which are different than monomers (A), (B) and (C), are preferably selected from the group consisting of cycloaliphatic (meth)acrylates (D1), (meth)acrylates of polyalkylene glycol monoalkyl ethers (D2), vinyl alkanoates (D3), allyl compounds (D4), vinyl ethers (D5), N-vinyllactams (D6), N-vinylimidazoles (D7), ethylenically unsaturated aromatics (D8), sulfur dioxide (D9) and ethylenically unsaturated nitriles (D10).

It is possible here for at least one monomer (D), preferably one to four, more preferably one to three, even more preferably one or two and especially exactly one monomer(s) (D) to be used optionally.

Examples of cycloaliphatic (meth)acrylates (D1) are (meth)acrylates of alcohols having at least one, preferably one or two and more preferably one cycloaliphatic ring system(s) and having 5 to 20 carbon atoms. Preferred monomers are cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate and norbornyl (meth)acrylate, particular preference being given to the respective acrylates. (Meth)acrylates of polyalkylene glycol monoalkyl ethers (D2) are preferably (meth)acrylic esters of mono-Ci-C4-alkyl ethers of poly-1 ,2-propylene glycol having a molar mass between 134 and 1178 or polyethylene glycol having a molar mass between 106 and 898, and also ethylene glycol mono-Ci-C4-alkyl ethers or propylene glycol mono-Ci-C4-alkyl ethers. Particular preference is given to ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, 1 ,2-propanediol monomethyl ether, 1 ,2-propanediol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol mono- n-butyl ether.

Among the vinyl alkanoates (D3), preference is given to vinyl acetate, vinyl propionate, vinyl butanoate, vinyl pentanoate, vinyl hexanoate, vinyl 2-ethylhexanoate, vinyl octanoate, vinyl ester of neodecanoic acid ("Veova"), vinyl decanoate, vinyl dodecanoate, vinyl tridecanoate, vinyl isotridecanoate, vinyl tetradecanoate, vinyl pentadecanoate, vinyl hexadecanoate and vinyl octadecanoate, particular preference to vinyl acetate, vinyl propionate, vinyl hexanoate, vinyl 2- ethylhexanoate, and vinyl ester of neodecanoic acid ("Veova"), very particular preference to vinyl acetate.

Among the allyl compounds (D4), preference is given to allyl alcohol, allyl alcohol Ci-C4-alkyl ethers and allyl alkanoates of those carboxylic acids as listed under (D3).

Among the vinyl ethers (D5), preference is given to cyclohexyl vinyl ether, isopropyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-butyl vinyl ether, octyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, tetradecyl vinyl ether, hexadecyl vinyl ether and octadecyl vinyl ether.

N-Vinyllactams (D6) are preferably N-vinylcaprolactam and N-vinylpyrrolidone.

Among the N-vinylimidazoles (D7), preference is given to N-vinylimidazole.

Among the ethylenically unsaturated aromatics (D8), preference is given to styrene and 1- methylstyrene, particular preference to styrene.

Among the ethylenically unsaturated nitriles (D10), preference is given to acrylonitrile and methacrylonitrile, particular preference to acrylonitrile.

Among the optionally usable monomers (D), preference is given to (D1), (D3), (D5) and/or (D8), particular preference to (D1), (D3) and/or (D5), very particular preference to (D1) and/or (D3). The stoichiometry of the monomers (A), (B), (C) and optionally (D) is preferably chosen such that the monomers in copolymerized form have a molar incorporation ratio of (A):(B):(C):(D) of 1:0.5 to 2.0:0 to 2.0:0 to 0.1.

Preferably, the molar incorporation ratio (A):(B):(C):(D) is 1 :0.6 to 1.5:0.1 to 1.5:0 to 0.05.

More preferably, the molar incorporation ratio (A):(B):(C):(D) is 1:0.7 to 1.0:0.2 to 1.0:0.

In a preferred embodiment no monomer (C) is present in the copolymer.

In another preferred embodiment no monomer (D) is present in the copolymer.

In another preferred embodiment neither monomer (C) nor monomer (D) is present in the copolymer. Hence, the copolymer is preferably made of monomers (A) and (B), more preferably of maleic anhydride and (B), even more preferably in a molar incorporation ratio of (A) : (B) 1 : 0.95 to 1.05.

The copolymer (IV) is obtainable in a first step by polymerizing a mixture of the monomers (A), (B), optionally (C) and optionally (D).

The copolymers are obtainable by the customary copolymerization processes, for example solvent polymerization, emulsion polymerization, precipitation polymerization or bulk polymerization, preferably solvent polymerization or bulk polymerization; they are preferably obtained via said copolymerization processes.

In a first preparation stage, the monomer components can be polymerized neat, in emulsion or preferably in solution. It is possible here to use a single monomer species or a mixture of several such monomer species for each monomer component. The polymerization reaction is generally conducted at standard pressure and under a protective gas, such as nitrogen, but it is also possible to work at elevated pressures of up to 25 bar, for example in an autoclave. The polymerization temperatures are generally 50 to 250°C, especially 90 to 210°C, in particular 120 to 180°C, typically 140 to 160°C. Suitable polymerization reactors are in principle all customary continuous or batchwise apparatuses, for example a stirred tank, stirred tank cascade, tubular reactor or loop reactor.

Typically, the polymerization is initiated by initiators that break down by a free-radical mechanism; suitable initiators for this purpose are air or oxygen of organic peroxides and/or hydroper- oxides, and also organic azo compounds. Examples of useful organic peroxides or hydroperoxides include diisopropylbenzene hydroperoxide, cumene hydroperoxide, methyl isobutyl ketone peroxide, di-tert-butyl peroxide and tert-butyl perisononanoate. An example of a suitable organic azo compound is azobisisobutyronitrile ("AIBN"). In addition, it is possible to use suitable chain transfer agents in the polymerization as well, such as thio alcohols, aldehydes or ketones.

If solvents or emulsion media are used in the polymerization as well, the customary high-boiling inert liquids are useful for this purpose, such as aliphatic hydrocarbons, e.g. heptane, Shellsol® D70, white oil, lamp oil), aromatic hydrocarbons, e.g. ethylbenzene, diethylbenzenes, toluene, xylenes or corresponding technical hydrocarbon mixtures such as Shellsol®, Solvesso® or Solvent Naphtha, and also dialkyl 1,2-cyclohexanedicarboxylates, preferably diisononyl 1,2- cyclohexanedicarboxylate.

In a second reaction stage, the copolymer thus obtainable, preferably the copolymer thus obtained, is reacted with the dialkylamine (E). The reaction generally does not require any catalysts; instead, the reaction can be effected at temperatures of 50 to 160°C, preferably 60 to 140 and more preferably 70 to 120°C. The reaction can preferably be effected in an inert solvent, preference being given to the solvents listed above for the polymerization.

The dialkylamine (E) is at least one, preferably one or two and more preferably exactly one dial- kylamine(s) (E), wherein the alkyl radicals are each independently alkyl radicals having at least 17 up to 30, preferably 17 to 26, more preferably 17 to 24 and most preferably 17 to 22 carbon atoms.

The two alkyl radicals may be the same or different, preferably the same.

The alkyl radicals having 17 up to 30 carbon atoms may be linear or branched, preferably linear, particular preference being given to n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, n- heneicosyl, n-docosyl, lignoceryl, ceryl and myricyl, and particular preference to n-octadecyl, n- nonadecyl and n-eicosyl.

Preferred dialkylamines (E) are di-n-octadecylamine, di-n-nonadecylamine and di-n- eicosylamine.

The molar ratio of dialkylamine (E) based on incorporated units of the dicarboxylic acid (A) in the copolymer is preferably at least 1.2:1, more preferably 1.3 to 2.0:1 , even more preferably 1.5 to 2.0:1 and especially 2.0:1. In a preferred embodiment, the dialkylamine is used in such a way that, ideally, one equivalent of dialkylamine (E) reacts with the incorporated units of the dicarboxylic acid (A) in the copolymer to form amide groups and one further equivalent of dialkylamine (E) neutralizes the free carboxyl groups formed.

In a further embodiment, it is possible to dispense with the second reaction stage if the monomer (A) is already used in the form of the di- or monoamide, preferably of the monoamide, of the unsaturated dicarboxylic acid with dialkylamines (E).

In this case, amidation of the copolymer formed from (A), (B) and optionally (C), and optionally (D), is no longer required since the monomer (A) has already been used in the polymerization as the corresponding amide. In this case, the free carboxyl groups present in the copolymer thus obtained may still be neutralized to an extent of 20 to 100 mol% with the dialkylamine (E).

The copolymer (IV), after reaction with component (E), preferably has a weight-average molecular weight (M _w ) in the range from 2000 to 20 000, more preferably from 2200 to 8000 and most preferably from 2500 to 6000 g/mol (determined in each case by gel permeation chromatography). The polydispersity is preferably up to 3, more preferably 2 to 3.

In a preferred embodiment the fuels may comprise at least one further cold flow improver (V) different from those mentioned above, more preferably at least one ethylene-vinyl alkanoate copolymer, even more preferably at least one ethylene-vinyl acetate copolymer.

In the context of present invention, flow improvers shall be understood to mean all additives which improve the cold properties of middle distillate fuels. As well as the actual cold flow improvers ("MDFI"), these are also nucleators (cf. also Ullmann’s Encyclopedia of Industrial Chemistry, 5th edition, volume A16, p. 719 ff.).

When cold flow improvers are present, the middle distillate fuels comprise these, in addition to the copolymer, in an amount of typically 1 to 2000 ppm by weight, preferably of 5 to 1000 ppm by weight, especially of 10 to 750 ppm by weight and in particular of 50 to 500 ppm by weight, for example of 150 to 400 ppm by weight.

Preferred flow improvers are ethylene-vinyl acetate copolymers as described in WO 99/29748, or comb polymers as described in WO 2004/035715, and form, together with the inventive co- polymer in its function as a paraffin dispersant, an efficient and versatile cold stabilization system for middle distillate fuels, especially for those having a proportion of biodiesel.

More preferably, the flow improvers are copolymers of ethylene with at least one further eth- ylenically unsaturated monomer, preferably selected from alkenyl carboxylates, (meth)acrylic esters, dialkyl maleates, dialkyl fumarates and olefins.

Most preferably, the flow improvers are ter- or quaterpolymers of ethylene and at least one alkenyl carboxylate and with at least one further ethylenically unsaturated monomer, preferably selected from (meth)acrylic esters, dialkyl maleates, dialkyl fumarates and olefins.

Suitable olefins are, for example, those having 3 to 10 carbon atoms and having 1 to 3, preferably having 1 or 2, especially having one carbon-carbon double bond(s). In the latter case, the carbon-carbon double bond may either be terminal (a-olefins) or internal. Preference is given, however, to a-olefins, particular preference to a-olefins having 3 to 6 carbon atoms, for example propene, 1-butene, 1-pentene and 1-hexene.

Suitable (meth)acrylic esters are, for example, esters of (meth)acrylic acid with Ci- to C - alkanols, especially with methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, nonanol and decanol.

Suitable alkenyl carboxylates are, for example, the vinyl and propenyl esters of carboxylic acids having 2 to 20 carbon atoms, wherein the hydrocarbyl radical may be linear or branched. Among these, preference is given to the vinyl esters. Among the carboxylic acids having a branched hydrocarbyl radical, preference is given to those wherein the branch is in the a position to the carboxyl group, the a carbon atom more preferably being tertiary, meaning that the carboxylic acid is what is called a neocarboxylic acid. However, the hydrocarbyl radical of the carboxylic acid is preferably linear.

Examples of suitable alkenyl carboxylates are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl neopentanoate, vinyl hexanoate, vinyl neononanoate, vinyl neodecanoate and the corresponding propenyl esters, preference being given to the vinyl esters. A particularly preferred alkenyl carboxylate is vinyl acetate; typical copolymers that result therefrom are ethylene-vinyl acetate copolymers ("EVA"), which are used on a large scale and diesel fuels. More preferably, the ethylenically unsaturated monomer is selected from alkenyl carboxylates.

Examples of dialkyl maleates and dialkyl fumarates are the methyl, ethyl, n-propyl, isopropyl, n- butyl, sec-butyl, isobutyl, n-pentyl, n-hexyl, 2-ethylhexyl and 2-propylheptyl esters of maleic acid or fumaric acid, these being mixed or preferably identical esters, i.e. in the case of alkyl radicals are the same.

Also suitable are copolymers comprising two or more different alkenyl carboxylates in copolymerized form, these differing in terms of the alkenyl function and/or in terms of the carboxylic acid group. Likewise suitable are copolymers which, as well as the alkenyl carboxylate(s), comprise at least one olefin and/or at least one (meth)acrylic ester in copolymerized form.

Such copolymers preferably have a number-average molecular weight M _n of 1000 to 20 000, more preferably of 1000 to 10 000 and especially of 1000 to 6000.

Fuels

In the context of the present invention, fuel oils shall be understood to mean middle distillate fuels of fossil, vegetable or animal origin, biofuel oils ("biodiesel") and mixtures of such middle distillate fuels and biofuel oils.

Middle distillate fuels (also called "middle distillates" for short hereinafter) are especially understood to mean fuels which are obtained by distilling crude oil as the first process step and boil within the range from 120 to 450°C. Such middle distillate fuels are used especially as diesel fuel, heating oil or kerosene, particular preference being given to diesel fuel and heating oil. Preference is given to using low-sulfur middle distillates, i.e. those which comprise less than 350 ppm of sulfur, especially less than 200 ppm of sulfur, in particular less than 50 ppm of sulfur. In special cases they comprise less than 10 ppm of sulfur; these middle distillates are also referred to as "sulfur-free". They are generally crude oil distillates which have been subjected to refining under hydrogenating conditions and therefore comprise only small proportions of polyaromatic and polar compounds. They are preferably those middle distillates which have 90% distillation points below 370°C, especially below 360°C and in special cases below 330°C.

Low-sulfur and sulfur-free middle distillates may also be obtained from relatively heavy mineral oil fractions which cannot be distilled under atmospheric pressure. Typical conversion processes for preparing middle distillates from heavy crude oil fractions include: hydrocracking, thermal cracking, catalytic cracking, coking processes and/or visbreaking. Depending on the process, these middle distillates are obtained in low-sulfur or sulfur-free form, or are subjected to refining under hydrogenating conditions.

The middle distillates preferably have aromatics contents of below 28% by weight, especially below 20% by weight. The content of normal paraffins is between 5% by weight and 50% by weight, preferably between 10 and 35% by weight.

In the context of the present invention, middle distillate fuels shall also be understood here to mean those fuels which can either be derived indirectly from fossil sources such as mineral oil or natural gas, or else are produced from biomass via gasification and subsequent hydrogenation. A typical example of a middle distillate fuel which is derived indirectly from fossil sources is the GTL ("gas-to-liquid") diesel fuel obtained by means of Fischer-Tropsch synthesis. A middle distillate is prepared from biomass, for example, via the BTL ("biomass-to-liquid") process, and can be used as fuel either alone or in a mixture with other middle distillates. The middle distillates also include hydrocarbons which are obtained by the hydrogenation of fats and fatty oils. They comprise predominantly n-paraffins.

The qualities of the heating oils and diesel fuels are laid down in more detail, for example, in DIN 51603 and EN 590 (cf. also Ullmann’s Encyclopedia of Industrial Chemistry, 5th edition, volume A12, p. 617 ff.).

In a preferred embodiment the fuel is a diesel fuel (absent any additives) with a CP value according to ASTM D2500/ASTM D97 of 0 to -15 °C, preferably 0 to -10 °C, and more preferably -5 to -10 °C and/or, preferably and with a content of n-paraffines of from 10 to 27 % by weight, more preferably of from 15 to 25 % by weight, and most preferably from 17 to 23 % by weight.

In addition to its use in the middle distillate fuels of fossil, vegetable or animal origin mentioned, which are essentially hydrocarbon mixtures, the inventive copolymer can also be used in biofuel oils and in mixtures of the middle distillates mentioned with biofuel oils, in order to improve cold flow characteristics. Mixtures of this kind are commercially available and usually comprise the biofuel oils in minor amounts, typically in amounts of 1% to 30% by weight, especially of 3% to 10% by weight, based on the total amount of middle distillate of fossil, vegetable or animal origin and biofuel oil.

Biofuel oils are generally based on fatty acid esters, preferably essentially on alkyl esters of fatty acids which derive from vegetable and/or animal oils and/or fats. Alkyl esters are preferably understood to mean lower alkyl esters, especially Ci- to C4-alkyl esters, which are obtainable by transesterifying the glycerides which occur in vegetable and/or animal oils and/or fats, especially triglycerides, by means of lower alcohols, for example ethanol or in particular methanol ("FAME"). Typical lower alkyl esters which are based on vegetable and/or animal oils and/or fats and find use as a biofuel oil or components thereof are, for example, HVO (hydrogenated vegetable oil), sunflower methyl ester, palm oil methyl ester ("PME"), soya oil methyl ester ("SME") and especially rapeseed oil methyl ester ("RME").

The compositions according to the present invention comprise compound (I) and antistatic agent (II) and compound (III) in a weight ratio of from 1 : 0.01 to 10 : 1 to 20, preferably from 1 : 0.02 to 5 : 2 to 10, more preferably from 1 : 0.05 to 3 : 2 to 5.

Preferably the composition may further comprise at least one cold flow improver (V) in a weight ratio referring to compound (I) : cold flow improver (V) of from 1 : 0.01 to 10, preferably from 1 : 0.02 to 5, more preferably from 1 : 0.05 to 3.

The composition is usually added to the middle distillate fuels in amounts of 10 to 5000 ppm by weight.

It is possible, through the use of the inventive compositions, to improve a number of fuel properties. Mention shall be made here by way of example merely of the additional effect as a cloud point depressant (CPD) or as a booster together with a flow improver for further improvement of the CFPP.

The inventive compositions can be added either to middle distillate fuels entirely of fossil origin, i.e. those that have been obtained from mineral oil, or to fuels which, as well as the proportion based on mineral oil, comprise a proportion of biodiesel, in order to improve the properties thereof. In both cases, a distinct improvement in the cold flow characteristics of the middle distillate fuel is observed, i.e. a lowering of the CP values and/or CFPP values, irrespective of the origin or the composition of the fuel. The paraffin crystals which precipitate out are effectively kept suspended, and so there are no blockages of filters and lines by sedimented paraffin. The inventive copolymers have a good activity spectrum and thus achieve very good dispersion of the paraffin crystals which precipitate out in a wide variety of different middle distillate fuels.

The present invention also provides fuels, especially those with a biodiesel content, comprising the inventive compositions. In general, the fuels or fuel additive concentrates also comprise, as further additives in amounts customary therefor, flow improvers (as described above), further paraffin dispersants, conductivity improvers, anticorrosion additives, lubricity additives, antioxidants, metal deactivators, antifoams, demulsifiers, detergents, cetane number improvers, solvents or diluents, dyes or fra- grances or mixtures thereof. The aforementioned further additives are familiar to those skilled in the art and therefore need not be explained any further here.

The other further additives mentioned above are, incidentally, familiar to those skilled in the art and therefore need not be elucidated here any further.

The examples which follow are intended to elucidate the present invention without restricting it.

Examples

Components

MDFI1 : Copolymer of ethylene and vinyl acetate, molecular weight 3400 g/mol, 60 wt% in aromatic hydrocarbon solvent as middle distillate flow improver (MDFI).

MDFI2: Copolymer of ethylene and vinyl acetate, molecular weight 2500 g/mol, 70 wt% in aliphatic hydrocarbon solvent as middle distillate flow improver (MDFI).

Component 1 : Ethylenediaminetetraacetic acid reacted with 4 mol of di tallow oil fatty acid amine, predominantly distearyl amine, prepared in Solvent Naphtha as described in example 1 of WO 00/23541.

Component 2: reaction product of maleic anhydride and tridecylamine according to Example 2 of WO 00/23541.

Component 3: reaction product of 2 mol oleic acid with 1 mol of diethylene triamine (40 wt% solution in Solvent Naphtha). Entries in the table refer to the solution.

Component 4: 1-decene-sulfur dioxide copolymer obtainable as described in Example 2 of WO 2008/107371 A2. Number average molecular weight Mn 18000 g/mol, weight average molecular weight Mn 110000 g/mol, polydispersity approx. 6.0.

Tests

The cloud point (CP) to ISO 3015 and the CFPP to EN 116 of the additized fuel samples were determined. For this purpose, the additized fuel samples in 500 ml glass cylinders, in order to determine the delta CP, were cooled to -13 °C in a cold bath and stored at this temperature for 16 hours. For each sample, the CP was again determined to ISO 3015 on the 20% by volume base phase separated off at -13 °C.

The smaller the deviation of the CP of the 20% by volume base phase from the original CP (delta CP) for the respective fuel sample, the better the dispersion of the paraffins. The smaller the delta CP and the lower the CFPP, the better the cold flow characteristics of a diesel fuel.

Fuels

Fuel 1 was a Diesel fuel from middle Europe, admixed with 7 % fatty acid methyl ester to a B7 Diesel fuel.

Cloud Point (CP): -8.1 °C

CFPP: -10 °C

Pour Point (PP): -12 °C

Density at 15 °C: 835.1 kg/m ³

Content of C8-C19 paraffines: 17.94%

Content of C>19 paraffines: 2.02%

Fuel 2 was a BO Diesel fuel from middle Europe.

Cloud Point (CP): -5.3 °C

CFPP: -8 °C

Pour Point (PP): -15 °C

Density at 15 °C: 843.0 kg/m ³

Content of C8-C19 paraffines: 13.45%

Content of C>19 paraffines: 3.93%

Fuel 3 was a BO Diesel fuel from middle Europe.

Cloud Point (CP): -9.8 °C

CFPP: -12 °C

Pour Point (PP): -18 °C

Density at 15 °C: 825.33 kg/m ³

Content of C8-C19 paraffines: 17.70%

Content of C>19 paraffines: 3.11%

Fuel 4 was a Diesel fuel from middle Europe, admixed with 7 % fatty acid methyl ester to a B7 Diesel fuel.

Cloud Point (CP): -6.2 °C

CFPP: -10 °C Pour Point (PP): -18 °C

Density at 15 °C: 832.37 kg/m ³

Content of C8-C19 paraffines: 17.65%

Content of C>19 paraffines: 2.56%

Fuel 5 was a Diesel fuel from middle Europe, admixed with 7 % fatty acid methyl ester to a B7 Diesel fuel.

Cloud Point (CP): -8.0 °C

CFPP: -10 °C

Pour Point (PP): -18 °C

Density at 15 °C: 827.65 kg/m ³

Content of C8-C19 paraffines: 17.59%

Content of C>19 paraffines: 2.17%

Fuel 6 was a BO Diesel fuel from middle Europe.

Cloud Point (CP): -9.0 °C

CFPP: -9 °C

Pour Point (PP): -15 °C

Density at 15 °C: 830.24 kg/m ³

Content of C8-C19 paraffines: 16.12%

Content of C>19 paraffines: 2.05%

Examples

Example 1

Fuel 1 was additized with 200 ppm MDFI1 and additionally with 150 wt.ppm of the wax antisettling additive package as stated in Table 1. The composition of the additive package in the table is given in weight per cent, the balance to 100 wt% is Solvent Naphtha 150 used as solvent. Table 1

(1) Amide of coconut fatty acid and N,N-dimethyl-1 ,3-propylene-diamine Entry 5 is according to the invention, entries 1 to 4 and 6 are comparative

The three-component mixture of Components 1 , 2 and 3 as in Entry 1 reflects the teaching of WO 2007/147753. The presence of Component 2 is necessary to ensure the stability of the mixture of Components 1 and 3 (see Example 4).

It can easily be seen that Component 2 can be substituted by a commercially available carbox- ylic acid (III) without deteriorating but even improving the results for CFPP and DeltaCP.

The total amount of additive added to the fuel can significantly reduced by using the mixture according to the invention in Entry 5 yielding excellent values for CFPP and DeltaCP.

Example 2

Fuel 1 was additized with 150 ppm MDFI1 and additionally with 150 ppm of the composition as stated in Table 2. The composition of the additive package in the table is given in weight per cent, the balance to 100 wt% is Solvent Naphtha 150 used as solvent.

Table 2 n.a. not available Example 3

Fuel 2 was additized with 150 ppm MDFI2 and additionally with 150 ppm of the composition as stated in Table 3: Table 3

The balance of the composition to 100 % is Solvent Naphtha 150 used as solvent. Example 4

The stability of the additive packages was determined after storage at room temperature for 1 week.

Table 4 The balance of the composition to 100 % is Solvent Naphtha 150 used as solvent.

It can easily be seen that the mixture of Components 1 and 3 leads to a visual turbidity and requires the presence of Component 2 or of a carboxylic acid for stabilisation (Entries 17 to 19 vs. 1 or 2).

Example 5

Fuel 3 was additized with 150 ppm MDFI2 and additionally with 150 ppm of the composition as stated in Table 5. The development of the CFPP- and DeltaCP-values was monitored after the period of time as given in Table 5:

Table 5

It can easily be seen that the CFPP-values remain constant within the measurement of accuracy of the method (repeatability r approx. 1.7 °C), but the Delta CP-value decreases in the course of the storage period.

Example 6

The following additive packages were tested in different fuels and the Delta CP-value was determined. Table 6a

Table 6b (Delta CP [°C])

It can easily be seen from Entries 4 to 6 that a combination of Components 1 and 3 does not yield a reduction of DeltaCP.