EP0931825A2 - Process to improve the cold flow properties of fuel oils - Google Patents

Abstract

An additive comprising a mixture of (A) 15-50 wt.% of a copolymer containing, apart from 87-92 mol.% structural units derived from ethylene, (a) 6.5-12 mol.% units derived from vinyl acetate and (b) 0.5-6 mol.% units derived from 4-methyl pentene-1, with the proviso that the sum of (a) and (b) is 8-14 mol.%, and (B) 85-50 wt.% of a further copolymer or terpolymer of ethylene and vinyl esters or acrylic acid esters. Process for improving the cold flow properties of oils containing less than 500 ppm sulfur and at least 8 wt.% n-paraffins of chain length of 18C or longer comprises adding an additive comprising a mixture of (A) 15-50 wt.% of a copolymer containing, apart from 87-92 mol.% structural units derived from ethylene, (a) 6.5-12 mol.% units derived from vinyl acetate and (b) 0.5-6 mol.% units derived from 4-methyl pentene-1, with the proviso that the sum of (a) and (b) is 8-14 mol.%, and (B) 85-50 wt.% of a further copolymer or terpolymer of ethylene and vinyl esters or acrylic acid esters.

Description

The present invention relates to a method for improving the Cold flow properties of mineral oils and mineral oil distillates, at the same time the filterability of the oils is retained, an additive mixture and the additive Oils.

Crude oils and middle distillates obtained by distilling crude oils such as gas oil, Diesel oil or heating oil contain different ones depending on the origin of the crude oils Amounts of n-paraffins which, when the temperature is lowered, are platelet-shaped Crystallize crystals and partially agglomerate with the inclusion of oil. This leads to a deterioration in the flow properties of these oils or distillates, which means, for example, during extraction, transport, storage and / or use of mineral oils and mineral oil distillates can occur. With mineral oils, this crystallization phenomenon can occur during transport Pipelines, especially in winter, to build up deposits on the pipe walls Individual cases, e.g. if a pipeline is at a standstill, even to completely block it to lead. The can also be used for the storage and processing of mineral oils Precipitation of paraffins cause difficulties. So it can be in winter It may be necessary to store the mineral oils in heated tanks. At Mineral oil distillates can clog the filter as a result of crystallization Diesel engines and firing systems occur, creating safe metering the fuel is prevented and, if necessary, a complete interruption of the Fuel or heating medium supply occurs.

In addition to the classic methods for removing the crystallized paraffins (thermal, mechanical or with solvents) that only affect the Removal of the already formed precipitates have been made in the last Years of chemical additives (so-called flow improvers or paraffin inhibitors) developed through physical interaction with the failing Paraffin crystals cause their shape, size and adhesive properties be modified. The additives act as additional crystal nuclei and partially crystallize with the paraffins, causing a larger number of results in smaller wax crystals with a changed crystal shape. A part of The effect of the additives is also explained by the dispersion of the wax crystals. The modified paraffin crystals are less prone to agglomeration, so that the pump oils mixed with these additives at temperatures or can be processed, which are often more than 20 ° lower than with non-additive oils.

The flow and cold behavior of mineral oils and mineral oil distillates is determined by Specification of the cloud point (determined according to ISO 3015), the pour point (determined according to ISO 3016) and the cold filter plugging point (CFPP; determined according to EN 116) described. Both parameters are measured in ° C.

Typical flow improvers for crude oils and middle distillates are copolymers of Ethylene with carboxylic acid esters of vinyl alcohol. So you bet after the DE-A-11 4 799 petroleum distillate fuels with a boiling point between about 120 and 400 ° C oil-soluble copolymers of ethylene and Vinyl acetate with a molecular weight between about 1,000 and 3,000. Copolymers which contain about 60 to 99% by weight of ethylene and about are preferred Contain 1 to 40 wt .-% vinyl acetate. They are particularly effective when passed through radical polymerization in an inert solvent at temperatures of about 70 to 130 ° C and pressures of 35 to 2,100 atü (DE-A-19 14 756). Mixtures of copolymers are also in the prior art described as a flow improver.

DE-A-22 06 719 discloses mixtures of ethylene / vinyl acetate copolymers with different comonomer contents to improve the cold flow behavior of middle distillates.

US 3,961,916 discloses mixtures of various vinyl esters or Acrylic esters with one another or with one another as cold flow improvers for Middle distillates.

DE-A-196 20 118 discloses terpolymers of ethylene, vinyl acetate and 4-methylpentene-1 as a cold flow improver for middle distillates.

EP-A-0 796 306 discloses additives for stabilizing the CFPP in middle distillates. These additives contain mixtures of copolymers and terpolymers of ethylene and Vinyl esters. The proportion of the mixtures proposed there is disadvantageous highly crystalline polymer fractions, in particular at low oil and / or Additive temperatures during the additive the filterability of the additive oils affect.

Conventional flow improvers are particularly problematic in middle distillates with a narrow distillation range and a high boiling end. It is observed that the CFPP set with such flow improvers in these oils is not stable, but rather goes back to the CFPP of the non-additized oil over the course of a few days to weeks (CFPP reversion). The reason for this is not known. It is suspected that it is to be found in an incomplete redissolution of the polymer components with a low comonomer content from the oil which has become cloudy. A particular problem is the prevention of CFPP reversion in the case of oils with a low sulfur content, since these contain particularly high proportions of long-chain n-paraffins with chain lengths greater than C ₁₈ due to the desulfurization steps.

It was therefore the task of additives for the mineral oils and To find mineral oil distillates that lead to a very good CFPP reduction, and in which there is no CFPP reversion and the filterability of the additive Do not interfere with oils above the cloud point.

Surprisingly, it was found that mixtures consisting of a copolymer Vinyl acetate, ethylene and 4-methylpentene-1 and a copolymer of ethylene and Containing vinyl esters or acrylic esters represent a solution to this problem.

A) 15 bis 50 Gew.-% eines Copolymers, enthaltend neben 87 bis 92 mol-% von Struktureinheiten, die sich von Ethylen ableiten;

a) 6,5 bis 11 mol-% Struktureinheiten, die sich von Vinylacetat ableiten,

b) 0,5 bis 5 mol-% Struktureinheiten, die sich von 4-Methylpenten-1 ableiten,
mit der Maßgabe, daß die Summe der molaren Anteile der Struktureinheiten a) und b) 8 bis 13 mol-% beträgt,

und

B) 85 bis 50 Gew-% mindestens eines weiteren Copolymers oder Terpolymers aus Ethylen und Vinylestern oder Acrylsäureestern, das für sich allein ein Kaltfließverbesserer ist.

The invention relates to a process for improving the cold flow properties of oils with a sulfur content of less than 500 ppm and a content of n-paraffins of chain length C ₁₈ and longer of at least 8% by weight, characterized by the addition of an additive containing one Mixture of

A) 15 to 50% by weight of a copolymer containing, in addition to 87 to 92 mol% of structural units which are derived from ethylene;

a) 6.5 to 11 mol% of structural units which are derived from vinyl acetate,

b) 0.5 to 5 mol% of structural units which are derived from 4-methylpentene-1,
with the proviso that the sum of the molar proportions of the structural units a) and b) is 8 to 13 mol%,

and

B) 85 to 50% by weight of at least one further copolymer or terpolymer composed of ethylene and vinyl esters or acrylic acid esters, which in itself is a cold flow improver.

The percentages by weight relate to the total weight of the mixture of A) and B).

Other objects of the invention are an additive to improve the Cold flow properties of mineral oils and mineral oil distillates as well Fuel oil compositions containing these additives.

The mixture of the copolymers preferably consists of 20 to 40% by weight of the Components A) and 60 to 80 wt .-% of component B).

Component A) is preferably a terpolymer which contains 7 to 11 mol% of structural units which are derived from vinyl acetate. Component A) furthermore preferably contains 1 to 4 mol% of structural units which are derived from 4-methylpentene-1. The total comonomer content, ie the content of structural units a) and b) is in a preferred embodiment between 10 and 13 mol%. In a further preferred embodiment, component A) contains 5 to 9 methyl groups per 100 methylene groups, with the exception of those methyl groups which originate from vinyl acetate. The number of methyl groups is determined by means of ¹ H NMR spectroscopy.

Copolymer B) is preferably an ethylene copolymer with a Comonomer content of 10 to 20 mol%, preferably 12 to 18 mol%. Suitable Comonomers are vinyl esters of aliphatic carboxylic acids with 2 to 15 carbon atoms. Preferred vinyl esters for copolymer B) are vinyl acetate, vinyl propionate, Vinyl hexanoate, vinyl laurate and vinyl esters of neocarboxylic acids, in particular here of neononanoic acid, neodecanoic acid and neoundecanoic acid. Are particularly preferred an ethylene-vinyl acetate copolymer, an ethylene-vinyl propionate copolymer Ethylene-vinyl acetate-neononanoic acid vinyl ester terpolymer or an ethylene-vinyl acetate-neodecanoic acid vinyl ester terpolymer. Preferred acrylic acid esters are Acrylic acid esters with alcohol residues from 1 to 20, in particular from 2 to 12 and especially from 4 to 8 carbon atoms, such as methyl acrylate, Ethyl acrylate and 2-ethylhexyl acrylate. Other suitable comonomers are olefins such as propene, hexene, butene, isobutene, diisobutylene, 4-methylpentene-1 and Norbornen. Ethylene-vinyl acetate-diisobutylene and ethylene-vinyl acetate-4-methylpentene-1 terpolymers are particularly preferred.

The copolymers used for the additive mixtures are the usual ones Copolymerization processes such as suspension polymerization, Solvent polymerization, gas phase polymerization or High-pressure bulk polymerization can be produced. The is preferred High pressure bulk polymerization at pressures of preferably 50 to 400, in particular 100 to 300 MPa and temperatures of preferably 50 to 350, especially 100 to 250 ° C. The reaction of the monomers is caused by radicals initiators (radical chain initiators) initiated. To this class of substance belong e.g. Oxygen, hydroperoxides, peroxides and azo compounds such as Cumene hydroperoxide, t-butyl hydroperoxide, dilauroyl peroxide, dibenzoyl peroxide, bis (2-ethylhexyl) peroxide carbonate, t-butyl perpivalate, t-butyl permaleinate, t-butyl perbenzoate, Dicumyl peroxide, t-butyl cumyl peroxide, di- (t-butyl) peroxide, 2,2'-azobis (2-methylpropanonitrile), 2,2'-azo-bis (2-methylbutyronitrile). The initiators are individual or as a mixture of two or more substances in amounts from 0.01 to 20 wt .-%, preferably 0.05 to 10 wt .-%, based on the Monomer mixture used.

The additive components preferably have melt viscosities of 140 ° C. 20 to 10,000 mPas, in particular from 30 to 5000 mPas, especially from 50 to 2000 mPas. The melt viscosities of A and B can be the same or different. A> B is preferred. The desired melt viscosity of the mixtures is determined by Selection of the individual components and variation of the mixing ratio of the Copolymers discontinued.

The copolymers mentioned under A) and B) can contain up to 5% by weight of further comonomers. Such comonomers can be, for example, vinyl esters, vinyl ethers, acrylic acid alkyl esters, methacrylic acid alkyl esters with C ₁ -C ₂₀ -alkyl radicals, isobutylene and higher olefins with at least 5 carbon atoms. Hexene, isobutylene, octene and / or diisobutylene are preferred as higher olefins.

High pressure bulk polymerization is carried out in known high pressure reactors, e.g. Autoclaves or tubular reactors, carried out batchwise or continuously, Tube reactors have proven particularly useful. Solvents such as aliphatic and / or aromatic hydrocarbons or hydrocarbon mixtures, Benzene or toluene can be contained in the reaction mixture. The is preferred solvent-free mode of operation. In a preferred embodiment of the Polymerization is the mixture of the monomers, the initiator and, if provided used, the moderator, a tubular reactor via the reactor inlet and via one or more side branches fed. Here the monomer streams be composed differently (EP-A-0 271 738).

The additive mixtures are mineral oils or mineral oil distillates in the form of Solutions or dispersions added. These solutions or dispersions preferably contain 1 to 90, in particular 5 to 80 wt .-% of the mixtures. Suitable solvents or dispersing agents are aliphatic and / or aromatic Hydrocarbons or hydrocarbon mixtures, e.g. Gasoline fractions, Kerosene, decane, pentadecane, toluene, xylene, ethylbenzene or commercial Solvent mixtures such as Solvent Naphtha, ®Shellsoll AB, ®Solvesso 150, ®Solvesso 200, ®Exxsol, ®ISOPAR and ®Shellsol D types. The specified Solvent mixtures contain different amounts of aliphatic and / or aromatic hydrocarbons. The aliphatics can be straight-chain (n-paraffins) or be branched (iso-paraffins). Aromatic hydrocarbons can be mono-, be di- or polycyclic and optionally one or more substituents carry. Through the additive mixtures in their rheological properties improved mineral oils or mineral oil distillates contain 0.001 to 2, preferably 0.005 to 0.5% by weight of the mixtures, based on the distillate.

For the production of additive packages for special problem solutions the Mixtures also together with one or more oil-soluble co-additives are used, which alone have the cold flow properties of crude oils, Improve lubricating oils or fuel oils. Examples of such co-additives are polar Compounds which effect a paraffin dispersion (paraffin dispersants), and Comb polymers.

Paraffin dispersants reduce the size of the wax crystals and cause the paraffin particles do not settle, but colloidally with significantly reduced Sedimentation efforts, remain dispersed. Have become paraffin dispersants oil-soluble polar compounds with ionic or polar groups, e.g. Amine salts and / or amides proven by the reaction of aliphatic or aromatic amines, preferably long-chain aliphatic amines, with aliphatic or aromatic Mono-, di-, tri- or tetracarboxylic acids or their anhydrides can be obtained (U.S. 4,211,534). Other paraffin dispersants are copolymers of Maleic anhydride and, ß-unsaturated compounds, optionally with primary monoalkylamines and / or aliphatic alcohols are implemented can (EP-A-0 154 177), the reaction products of alkenylspirobislactones with Amines (EP-A-0 413 279) and according to EP-A-0 606 055 reaction products of Terpolymers based on α, β-unsaturated dicarboxylic acid anhydrides, α, β-unsaturated compounds and polyoxyalkenyl ethers of lower unsaturated Alcohols. Alkylphenol-formaldehyde resins are also used as paraffin dispersants suitable.

Comb polymers are polymers in which hydrocarbon radicals having at least 8, in particular at least 10, carbon atoms are bonded to a polymer backbone. They are preferably homopolymers whose alkyl side chains contain at least 8 and in particular at least 10 carbon atoms. In copolymers, at least 20%, preferably at least 30%, of the monomers have side chains (cf. Comb-like Polymers - Structure and Properties; NA Platé and VP Shibaev, J. Polym. Sci. Macromolecular Revs. 1974, 8, 117 ff). Examples of suitable comb polymers are, for example, fumarate / vinyl acetate copolymers (cf. EP-A-0 153 176), copolymers of a C ₆ -C ₂₄ - olefin and an NC ₆ - to C ₂₂ -alkyl maleimide (cf. EP-A -0 320 766), also esterified olefin / maleic anhydride copolymers, polymers and copolymers of α-olefins and esterified copolymers of styrene and maleic anhydride.

beschrieben werden. Darin bedeuten

A

R', COOR', OCOR', R''-COOR', DR';

D

H, CH₃, A oder R'';

E

H, A;

G

H, R'', R''-COOR', einen Arylrest oder einen heterocyclischen Rest;

M

H, COOR'', OCOR'', OR'', COOH;

N

H, R'', COOR'', OCOR, einen Arylrest;

R'

eine Kohlenwasserstoffkette mit 8 bis 50 Kohlenstoffatomen;

R''

eine Kohlenwasserstoffkette mit 1 bis 10 Kohlenstoffatomen;

m

eine Zahl zwischen 0,4 und 1,0; und

n

eine Zahl zwischen 0 und 0,6.

For example, comb polymers can be represented by the formula

to be discribed. Mean in it

A

R ', COOR', OCOR ', R''-COOR', DR ';

D

H, CH ₃ , A or R '';

E

H, A;

G

H, R '', R '' - COOR ', an aryl radical or a heterocyclic radical;

M

H, COOR '', OCOR '', OR '', COOH;

N

H, R ", COOR", OCOR, an aryl radical;

R '

a hydrocarbon chain of 8 to 50 carbon atoms;

R ''

a hydrocarbon chain of 1 to 10 carbon atoms;

m

a number between 0.4 and 1.0; and

n

a number between 0 and 0.6.

The mixing ratio (in parts by weight) of the additive mixtures with Paraffin dispersants and / or comb polymers are each 1:10 to 20: 1, preferably 1: 1 to 10: 1.

Middle distillates are particularly well suited as fuel components. As Middle distillates are referred to as those mineral oils that pass through Distillation of crude oil and boiling in the range of 120 to 400 ° C, such as kerosene, jet fuel, diesel and heating oil. The invention Fuels preferably contain less than 350 ppm and especially less than 200 ppm sulfur. The content of n-paraffins determined by GC, the chain lengths of 18 carbon atoms or more is at least 8 area%, preferably with more than 10 area%. Compared to the closest version of Technology, in particular to EP-A-0 796 306, there is the advantage of inventive method in an improved solubility of the additives, so that the filterability of the oils additized with them also after additivation low temperatures of oil and / or additive is maintained. Also show the mixtures according to the invention have pronounced synergistic effects the individual components in the CFPP reduction.

The additive mixtures can be used alone or together with others Additives are used, for example with dewaxing aids, Corrosion inhibitors, antioxidants, lubricity additives, dehazers, Conductivity improvers, cetane number improvers or sludge inhibitors.

Examples

Characterization of additives The following copolymers and terpolymers of ethylene, each 50% in kerosene suspended, used: Vinyl acetate CH ₃ / 100CH ₂ Termonomer A1) 24.9% (10.0 mol%) 5.4 1.5 mol% 375 mPas A2) 22.5% (9.1 mol%) 6.5 2.6 mol% 287 mPas A3) 26.2% (10.8 mol%) 6.0 2.11 mol% 486 mPas A4) 22.0% (9.0 mol%) 8.0 3.8 mol% 335 mPas B1) 32.0% (13.3 mol%) 3.2 - 125 mPas B2) 32.0% (14.0 mol%) 6.5 1.6 mol% 110 mPas B3) 31.7% (14.9 mol%) 7.2 2.2 mol% 240 mPas Characterization of the test oils The boiling data are determined in accordance with ASTM D-86, the CFPP value in accordance with EN 116 and the cloud point in accordance with ISO 3015. The paraffin content is determined by gas chromatographic separation of the oil (detection using FiD) and calculation of the integral of the n-paraffins ≥ C ₁₈ in relation to the total integral. Test oil 1 (° C) Test oil 2 (° C) Test oil 3 (° C) Test oil 4 (° C) Test oil 5 (° C) Test oil 6 (° C) Start of boiling 180 169 183 183 184 182 20% 267 255 226 232 258 243 90% 350 350 330 358 329 351 95% 365 364 347 378 344 366 Cloud point -0.4 -1 -9 +4 -5 -3 CFPP -3 -3 -12 -4 -9 -6 (90-20)% 83 95 104 126 71 108 n-paraff. ≥C18 [area%] 11.8 10.9 9.6 10.5 8.5 11.3 S content [ppm] 270 540 175 375 295 430

Determination of the CFPP stability

The CFPP value of the oil additized with the specified amount of flow improver was measured directly after the additivation and the rest of the sample was stored at -3 ° C, i.e. below the cloud point. At weekly intervals, the samples were heated to 12 ° C, 50 ml were taken for another CFPP measurement and the rest was stored at -3 ° C. CFPP stability in test oil 1 The dosing rate in test oil 1 was 800 ppm additive, 50% in kerosene CFPP (immediately) 1 week 2 weeks 3 weeks 4 weeks A1 + B1 (1: 5) -14 -13 -11 -12 -11 A1 + B2 (1: 3) -12 -14 -12 -11 -12 A2 + B3 (1: 4) -14 -12 -11 -13 -11 A3 + B2 (1: 2) -12 -12 -11 -9 -11 A4 + B3 (1: 4) -13 -12 -13 -11 -11 A1 + B2 (1: 2) -14 -14 -10 -13 -14 A1 + B1 + B2 (1: 2: 2) -14 -12 -12 -15 -12 B1 (comparison) -10 -4 -5 -3 -4 B2 (comparison) -11 -7 -5 -4 -5 B3 (comparison) -10 -9 -7 -7 -5 CFPP stability in test oil 2 The dosing rate in test oil 2 was 800 ppm additive, 50% in kerosene CFPP (immediately) 1 week 2 weeks 3 weeks 4 weeks A1 + B2 (1: 3) -12 -10 -10 -12 -10 A2 + B3 (1: 4) -11 -12 -11 -12 -12 B2 (comparison) -10 -9 -7 -8th -5 B3 (comparison) -10 -9 -6 -6 -5

CFPP stability in test oil 6

CFPP values immediately after additives Additive CFPP (° C) 50 ppm 100 ppm 150 ppm B1 -10 -15 -16 B2 -9 -14 -15 A4 + B1 (1: 3) -11 -16 -17 A4 + B2 (1: 5) -10 -14 -15 CFPP values after 4 days of storage at 2 ° C Additive CFPP (° C) 50 ppm 100 ppm 150 ppm B1 -9 -10 -9 B2 -8th -10 -9 A4 + B1 (1: 3) -11 -15 -17 A4 + B2 (1: 5) -11 -15 -16 CFPP synergism in test oil 3 50 ppm 100 ppm 200 ppm A1 + B1 (1: 2) -20 -22 -24 A1 + B2 (1: 3) -19 -21 -26 A1 (comparison) -16 -18 -18 B1 (comparison) -17 -20 -23 B2 (comparison) -11 -15 -22 CFPP synergism in test oil 4 100 ppm 200 ppm 300 ppm A1 + B2 (1: 1) -12 -15 -16 A1 + B1 (1: 2) -11 -13 -17 A1 (comparison) -6 -8th -10 B1 (comparison) 1 -8th -12 B2 (comparison) -3 -2 -5

Solubility of the mixtures

The solubility behavior of the terpolymers is determined in the British Rail Test as follows: 400 ppm of a dispersion of the polymer in kerosene heated to 22 ° C. are metered into 200 ml of test oil 5 heated to 22 ° C. and shaken vigorously for 30 seconds. After storage for 24 hours at + 3 ° C., the mixture is shaken for 15 seconds and then filtered at 3 ° C. in three 50 ml portions through a 1.6 μm glass fiber microfilter (25 mm; Whatman GFA, Order No. 1820025). The ADT value is calculated from the three filtration times T ₁ , T ₂ and T ₃ , the total of which must not exceed 20 minutes: DT = (T3-T1) T2 · 50

An ADT value ≤ 15 is regarded as an indication that the gas oil can be used satisfactorily in "normal" cold weather. Products with ADT values ≤ 25 are said to be non-filterable. Solubility of the additives ADT Blank value (without additive) 3.0 A1 + B2 (1: 5) 5.8 A1 + B3 (1: 3) 6.0 A3 + B1 (1: 1) 12.5 A4 + B2 (1: 4) 8.2 B2 (comparison) 5.4 B2 + 4% EVA copolymer with 13.5% by weight vinyl acetate (according to WO 97/17905) 60 B2 + 10% EVA copolymer with 13.5% by weight vinyl acetate (according to WO 97/17905) not filterable (115 ml in 20 minutes)

List of trade names used

Solvent naphtha

aromatic solvent mixtures with boiling range 180 to 210 ° C

®Shellsol AB

®Solvesso 150

®Solvesso 200

aromatic solvent mixture with boiling range 230 up to 287 ° C

®Exxsol

Dearomatized solvents in various Boiling ranges, for example ®Exxsol D60: 187 bis 215 ° C

®ISOPAR (Exxon)

isoparaffinic solvent mixtures in different Boiling ranges, for example ®ISOPAR L: 190 to 210 ° C

®Shellsol D

mainly aliphatic solvent mixtures in different boiling ranges

Claims (10)

Process for improving the cold flow properties of oils with a sulfur content of less than 500 ppm and a content of n-paraffins of chain length C ₁₈ and longer of at least 8% by weight, characterized by the addition of an additive containing a mixture of A) 15 to 50% by weight of a copolymer containing, in addition to 87 to 92 mol% of structural units which are derived from ethylene; a) 6.5 to 12 mol% of structural units which are derived from vinyl acetate, b) 0.5 to 6 mol% of structural units which are derived from 4-methylpentene-1,
with the proviso that the sum of the molar proportions of the structural units a) and b) is 8 to 14 mol%, and B) 85 to 50% by weight of at least one further copolymer or terpolymer composed of ethylene and vinyl esters or acrylic acid esters, which is a cold flow improver in itself. A method according to claim 1, characterized in that copolymer A) 7 to Contains 11 mol% of the structural units mentioned under a). A method according to claim 1 and / or 2, characterized in that Copolymer A) contains 1 to 4 mol% of the structural units mentioned under b). Method according to one or more of claims 1 to 3, characterized characterized in that the additive mixture used has melt viscosities at 140 ° C from 20 to 10,000 mPas, in particular from 30 to 5000 mPas having. Method according to one or more of claims 1 to 4, characterized characterized in that the copolymers mentioned under A) or B) up to Contain 5 wt .-% of other comonomers. A method according to claim 5, characterized in that as further Comonomer vinyl esters, vinyl ethers, acrylic acid alkyl esters, Alkyl methacrylate, isobutylene or higher olefins with at least 5 Carbon atoms, preferably hexene, octene or diisobutylene, use Find. Method according to one or more of claims 1 to 6, characterized characterized in that paraffin dispersants and / or comb polymers as further components of the additive composition are added. Method according to one or more of claims 1 to 7, characterized characterized in that the additive mixtures 20 to 40 wt .-% of Components A) and 60 to 80% by weight of component B) contain. Additive mixture to improve the cold flow behavior of middle distillates, containing A) 15 to 50% by weight of a copolymer containing, in addition to 87 to 92 mol% of structural units which are derived from ethylene; a) 6.5 to 12 mol% of structural units which are derived from vinyl acetate, b) 0.5 to 6 mol% of structural units which are derived from 4-methylpentene-1,
with the proviso that the sum of the molar proportions of the structural units a) and b) is 8 to 14 mol%, and B) 85 to 50% by weight of at least one further copolymer or terpolymer composed of ethylene and vinyl esters or acrylic acid esters, which in itself is a cold flow improver. Fuel oil composition containing a fuel oil with a sulfur content of less than 500 ppm and a content of n-paraffins of chain length C ₁₈ and longer of at least 8% by weight and an additive containing a mixture of A) 15 to 50% by weight of a copolymer containing, in addition to 87 to 92 mol% of structural units which are derived from ethylene; a) 6.5 to 12 mol% of structural units which are derived from vinyl acetate, b) 0.5 to 6 mol% of structural units which are derived from 4-methylpentene-1,
with the proviso that the sum of the molar proportions of the structural units a) and b) is 8 to 14 mol%, and B) 85 to 50% by weight of at least one further copolymer or terpolymer composed of ethylene and vinyl esters or acrylic acid esters, which in itself is a cold flow improver.