EP0964052A1 - Use of nitrogen-containing ethylene copolymers for producing fuel oils with improved lubricating activity - Google Patents

Abstract

The invention relates to processes for improving the lubricating effect of fuel oils, characterized by the use of an additive which improves the lubricating effect and contains at least one copolymer which, in addition to structural units which are derived from ethylene, also has structural units which are derived from an ethylenically unsaturated compound which have at least one aromatic or aliphatic nitrogen atom.

Description

The present invention relates to the use of nitrogenous Ethylene copolymers to improve the lubricating properties of fuel oils.

Mineral oils and mineral oil distillates used as fuel oils generally contain 0.5 wt .-% and more sulfur, when burning causes the formation of sulfur dioxide. To the resulting To reduce environmental pollution, the sulfur content of fuel oils lowered further and further. The diesel fuel standard EN 590 writes in Germany currently has a maximum sulfur content of 500 ppm. In Scandinavia already comes in with fuel oils with less than 200 ppm Exceptional cases with less than 50 ppm sulfur for use. This Fuel oils are usually made by making them from petroleum Fractions obtained by distillation hydrogenated refined. In the Desulphurization also removes other substances that Give fuel oils a natural lubricating effect. About these substances include polyaromatic and polar compounds.

However, it has now been shown that the friction and wear reducing Properties of fuel oils with increasing desulfurization become worse. Often these properties are so poor that the materials lubricated by fuel, e.g. the distributor injection pumps from Diesel engines can be expected to eat after a short time got to. The further lowering of the 95% distillation point below 370 ° C, partly below 350 ° C or below 330 ° C further exacerbates this problem.

Approaches are therefore described in the prior art which provide a solution to this Problems (so-called lubricity additives).

EP-A-0 680 506 discloses esters from carboxylic acids having 2 to 50 carbon atoms as additives to improve the lubricating effect of low sulfur Middle distillates with less than 0.5% by weight S.

DD-126 090 discloses lubricant-improving additives made from copolymers of Ethylene and unsaturated carboxylic acid esters, preferably vinyl acetate, which the Fuels in amounts of 0.01 to 0.5 wt .-% are added.

DE-A-15 94 417 discloses additives for improving the lubricating effect of oleophilic Liquids containing esters of glycols and dicarboxylic acids with at least Contain 11 carbon atoms.

EP-A-0 635 558 discloses diesel oils with sulfur contents of less than 0.2% by weight and aromatics contents of less than 30% by weight containing 100 to 10,000 ppm C ₁ -C ₅ alkyl esters of unsaturated straight-chain C ₁₂ -C ₂₂ Fatty acids derived from oilseeds are added, which improves their lubricating effect.

EP-A-0 764 198 discloses additives which improve the lubricating effect of fuel oils improve, and the polar nitrogen compounds based on alkylamines or Contain alkylammonium salts with alkyl radicals of 8 to 40 carbon atoms.

The object of the present invention was to find a method which Middle distillates largely freed from sulfur and aromatic compounds helps to improve the lubricating effect. At the same time, with this Process also affects the cold flow properties of these middle distillates favorably become.

Surprisingly, it was found that copolymers of ethylene and nitrogen-containing ethylenically unsaturated compounds that are additized with them Give fuel oils the required properties.

The invention relates to the use of 0.001 to 2 wt .-% (based on the fuel oil) of an additive which contains at least one copolymer which in addition to structural units derived from ethylene, there are also those Has structural units that differ from at least one ethylenically unsaturated Derive compound that has at least one aromatically or aliphatically bound Has nitrogen atom, with the exception of nitrogen atoms in imide bond, for Improvement of the lubricating effect of fuel oils.

The method according to the invention is preferably used for such fuel oils applied, which have a maximum of 0.2 wt .-% sulfur, and the group of Middle distillates belong. The method for additives is particularly well suited of oils containing less than 0.05, especially less than 0.035% by weight sulfur contain.

a) Alkylaminoacrylate bzw. -methacrylate, wie z.B. Aminoethylacrylat, Aminopropylacrylat, Amino-n-butylacrylat, N-Methylaminoethylacrylat, N,N-Dimethylaminoethylacrylat, N,N-Diethylaminoethylacrylat, N,N-Dimethylaminopropylacrylat, N,N-Diethylaminopropylacrylat sowie die entsprechenden Methacrylate,

b) Alkylacrylamide und -methacrylamide, wie z.B. Ethylacrylamid, Butylacrylamid, N-Octylacrylamid, N-Propyl-N-methoxyethylacrylamid, N-Acryloylphthalimid, N-Acryloylsuccinimid, N-Methylolacrylamid, sowie die entsprechenden Methacrylamide,

c) Vinylamide, wie z.B. N-Vinyl-N-methylacetamid, N-Vinylsuccinimid,

d) Aminoalkylvinylether, wie z.B. Aminopropylvinylether, Diethylaminoethylvinylether, Dimethylaminopropylvinylether,

e) Allylamin, N-Allyl-N-methylamin, N-Allyl-N-ethylamin,

f) eine Vinylgruppe tragende Heterozyklen, wie z.B. N-Vinylpyrrolidon, Methylvinylimidazol, 2-Vinylpyridin, 4-Vinylpyridin, 2-Methyl-5-vinylpyridin, Vinylcarbazol, Vinylimidazol, N-Vinyl-2-piperidon, N-Vinylcaprolactam.

The ethylenically unsaturated comonomers which, in addition to ethylene, are a component of the copolymer used in the process according to the invention, are preferably nitrogen-containing compounds which contain an ethylenic double bond which is capable of radical polymerization. Suitable comonomers are:

a) Alkylaminoacrylates or methacrylates, such as aminoethyl acrylate, aminopropyl acrylate, amino-n-butyl acrylate, N-methylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminopropyl acrylate and N, N-corresponding Methacrylates,

b) alkyl acrylamides and methacrylamides, such as, for example, ethyl acrylamide, butyl acrylamide, N-octylacrylamide, N-propyl-N-methoxyethylacrylamide, N-acryloylphthalimide, N-acryloylsuccinimide, N-methylolacrylamide, and the corresponding methacrylamides,

c) vinylamides, such as, for example, N-vinyl-N-methylacetamide, N-vinylsuccinimide,

d) aminoalkyl vinyl ethers, such as, for example, aminopropyl vinyl ether, diethylaminoethyl vinyl ether, dimethylaminopropyl vinyl ether,

e) allylamine, N-allyl-N-methylamine, N-allyl-N-ethylamine,

f) heterocycles bearing a vinyl group, such as, for example, N-vinylpyrrolidone, methylvinylimidazole, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, vinylcarbazole, vinylimidazole, N-vinyl-2-piperidone, N-vinylcaprolactam.

The monomers are commercially available or by known methods producible. The various aminoalkylene (meth) acrylates are e.g. according to EP-A-0188639 by transesterification of (meth) acrylic acid esters with amino alcohols accessible in the presence of a titanium catalyst. The production of Aminoalkyl vinyl ethers are e.g. in Liebigs Ann. Chem. 601 (1956), 81 described.

Those for use in the process according to the invention are preferably Suitable copolymers containing 0.1 to 15, in particular 1 to 10 mol% of one or contain several of the nitrogen-containing comonomers. Furthermore, in Processes according to the invention can also be used in mixtures of such copolymers. The melt viscosities of the copolymers that can be used are 140 ° C. preferably below 10,000 mPas, in particular between 10 and 1000 mPas and especially between 20 and 500 mPas.

The copolymers which can be used in the process according to the invention also contain Ethylene at least one comonomer with nitrogen atoms. You can still more, for example one, two or three more olefinically unsaturated Comonomers included. Such olefinically unsaturated comonomers are for example vinyl esters, acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, Vinyl ethers or olefins. Particularly preferred vinyl esters are vinyl acetate, Vinyl propionate and vinyl ester of neocarboxylic acids with 8, 9, 10, 11 or 12 Carbon atoms. Particularly preferred acrylic and methacrylic esters are those with Alcohols with 1 to 20 carbon atoms, especially of methanol, ethanol, Propanol, n-butanol, iso-butanol and tert-butanol. Particularly preferred olefins are those with 3 to 10 carbon atoms, especially propene, isobutylene, Diisobutylene, 4-methylpentene-1 and hexene. Do the copolymers contain another Comonomer, its molar fraction is preferably up to 15 mol%, in particular up to 12 mol%.

The comonomers are copolymerized by known processes (cf. for this e.g. Ullmann's Encyclopedia of Technical Chemistry, 4th Edition, Vol. 19, Pages 169 to 178). Polymerization in solution, in suspension, in the gas phase and high pressure bulk polymerization. Preferably one turns high-pressure bulk polymerization, which is carried out at pressures of 50 to 400 MPa, preferably 100 to 300 MPa and temperatures of 50 to 350 ° C, preferably 100 to 300 ° C, is carried out. The reaction of the comonomers is determined by Radical initiators (radical chain initiators) initiated. To this Substance classes belong e.g. Oxygen, hydroperoxides, peroxides and Azo compounds such as cumene hydroperoxide, t-butyl hydroperoxide, dilauroyl peroxide, Dibenzoyl peroxide, bis (2-ethylhexyl) peroxidicarbonate, t-butyl permaleinate, t-butyl perbenzoate, dicumyl peroxide, t-butylcumyl peroxide, di- (t-butyl) peroxide, 2,2'-azobis (2-methylpropanonitrile), 2,2'-azobis (2-methylbutyronitrile). The initiators are used individually or as a mixture of two or more substances in quantities of 0.01 to 20 wt .-%, preferably 0.05 to 10 wt .-%, based on the Comonomer mixture used.

The desired melt viscosity of the copolymers is given Composition of the comonomer mixture by varying the Reaction parameters pressure and temperature and optionally by adding Moderators hired. Hydrogen, saturated or unsaturated hydrocarbons, e.g. Propane, aldehydes, e.g. Propionaldehyde, n-butyraldehyde or isobutyraldehyde, ketones, e.g. Acetone, methyl methyl ketone, Methyl isobutyl ketone, cyclohexanone or alcohols, e.g. Butanol, proven. In The moderators become dependent on the desired viscosity in quantities up to 20 wt .-%, preferably 0.05 to 10 wt .-%, based on the Comonomer mixture used.

High pressure bulk polymerization is carried out in known high pressure reactors, e.g. Autoclaves or tube reactors are carried out batchwise or continuously, Tube reactors have proven particularly useful. Solvents such as aliphatic Hydrocarbons or hydrocarbon mixtures, benzene or toluene, can be contained in the reaction mixture, although the solvent-free Working method has proven particularly successful. According to a preferred embodiment of the Polymerization is the mixture of the comonomers, 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 comonomer streams be composed differently (EP-B-0 271 738).

Furthermore, the lubricating effect of oils can be improved in the manner according to the invention by adding ethylene copolymers which contain acid groups reacted with compounds bearing amino groups. Suitable ethylene copolymers and ethylene terpolymers are, for example, those which contain acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid or maleic anhydride. To produce an additive that improves the lubricating effect of oils, these copolymers containing acid groups are attached to the acid groups with primary or secondary amines such as methylamine, dimethylamine, ethylamine, propylamine, butylamine, or alkanolamines such as ethanolamine, propanolamine, which carry C ₁ -C ₁₀ -alkyl radicals. Diethanolamine, N-ethylethanolamine, diglycolamine, 2-amino-2-methylpropanolamine and mixtures thereof. 0.1 to 1.2 mol, preferably equimolar amounts, of amine per mol of acid are used. The reaction with hydroxyamines can take place either via the OH group to form esters or via an NH ₂ group to form amides.

To improve the lubricating effect according to the invention Copolymers mineral oils or mineral oil distillates in the form of solutions or Dispersions containing 10 to 90% by weight, preferably 20 to 80% by weight, of the polymers included, added. 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, ®Shellsol AB, ®Solvesso 150, ®Solvesso 200, ®Exxsol, ®ISOPAR and Shellsol D types. By the copolymers in their lubricating properties improved mineral oils or Mineral oil distillates contain 0.001 to 2, preferably 0.005 to 0.5% by weight Copolymer based on the distillate.

Mixtures can also be used in the process according to the invention, those of copolymers of the claimed type, but of different quality and / or quantitative composition and / or different (at 140 ° C measured) viscosity exist. The mixing ratio (in parts by weight) of the Copolymers can be varied over a wide range and e.g. 20: 1 to 1:20, preferably 10: 1 to 1:10. In this way, the additives specifically adapt to individual requirements.

For the production of additive packages for special solutions to problems in process according to the invention the copolymers together with one or several oil-soluble co-additives can be used, which alone Cold flow properties and / or lubricating effect of crude oils, lubricating oils or Improve fuel oils. Examples of such co-additives are those containing vinyl acetate Copolymers or terpolymers of ethylene, polar compounds, the one Paraffin dispersion effect (paraffin dispersants), comb polymers and oil-soluble amphiphiles.

So has the use of nitrogen-containing copolymers with copolymers excellent proven, the 10 to 40 wt .-% vinyl acetate and 60 to 90 wt .-% Contain ethylene.

To improve the lubricating effect in the process according to the invention mixtures with paraffin dispersants can also be used. These additives reduce the size of the paraffin crystals and cause the paraffin particles to separate do not settle, but colloidally with significantly reduced sedimentation efforts, stay dispersed. Furthermore, they increase the lubricating effect of the nitrogen-containing copolymers. Oil-soluble polar dispersants have been found as paraffin dispersants 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 are obtained (cf. US 4,211 534). Other paraffin dispersants are copolymers of maleic anhydride and α, β-unsaturated compounds, optionally with primary monoalkylamines and / or aliphatic alcohols can be implemented (cf. EP 0 154 177), the reaction products of alkenyl spirobis lactones with amines (cf. EP 0 413 279 B1) and according to EP 0 606 055 A2 reaction products of Terpolymers based on α, β-unsaturated dicarboxylic acid anhydrides, α, β-unsaturated compounds and polyoxyalkylene ethers of lower unsaturated ones Alcohols. Alkylphenol aldehyde resins are also suitable as paraffin dispersants.

Finally, in a further proven variant of the process, the nitrogen-containing copolymers are used together with comb polymers. This is understood to mean 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 0 153 176 A1), copolymers of a C ₆ to C ₂₄ α-olefin and an NC ₆ to C ₂₂ alkyl maleimide (cf. EP 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 oder OR ;

D

H, CH₃, A oder R ;

E

H oder A;

G

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

M

H, COOR , OCOR , OR oder COOH;

N

H, R , COOR , OCOR, COOH oder einen Arylrest;

R

eine Kohlenwasserstoffkette mit 8-50 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 or OR ;

D

H, CH ₃ , A or R ;

E

H or A;

G

MR , R -COOR , an aryl radical or a heterocyclic radical;

M

H, COOR , OCOR , OR or COOH;

N

MR , COOR , OCOR, COOH or an aryl radical;

R

a hydrocarbon chain of 8-50 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 nitrogen-containing copolymers with Paraffin dispersants or comb polymers are 1:10 to 20: 1, preferably 1: 1 to 10: 1.

To optimize the lubricating effect in the method according to the invention additional lubricity additives can be used. As lubricity additives have become preferably fatty alcohols, fatty acids and dimer fatty acids and their esters and Partial esters with glycols (according to DE-A-15 94 417), polyols such as glycerin (according to EP-A-0 680 506, EP-A-0 739 970) or hydroxyamines (according to EP-A-0 802 961) proven.

The method according to the invention is suitable for the lubricating properties of to improve animal, vegetable or mineral oils. It is for them Particularly suitable for use with middle distillates. As middle distillates One particularly refers to those mineral oils which are obtained by distilling crude oil be obtained and boiling in the range of 120 to 450 ° C, for example Kerosene, jet fuel, diesel and heating oil. Preferably, the invention Process applied to such middle distillates, the 0.5 wt .-% sulfur and less, especially less than 200 ppm sulfur and in special cases contain less than 50 ppm sulfur. It is generally about those middle distillates which have been subjected to hydrogenating refining, and which therefore only contains small amounts of polyaromatic and polar compounds contain, which give them a natural lubricating effect. The The method according to the invention is also preferably used in such Middle distillates applied, the 95% distillation points below 370 ° C, in particular 350 ° C and in special cases below 330 ° C.

Other additives can also be used in the process according to the invention, e.g. Pour point depressants or dewaxing agents, corrosion inhibitors, Antioxidants, sludge inhibitors, dehazers and additives to lower the Cloud points.

Another object of the invention is a means for improving Lubricating effect of fuel oils, the ones described above contains nitrogen-containing ethylene copolymers.

Another object of the invention is a fuel oil with improved Lubricating effect, characterized by a content of 0.001 to 2, preferably 0.005 to 0.5% by weight of the nitrogen-containing ones described above Ethylene copolymers.

Examples Additives

Additive 1:

Terpolymer made of ethylene, 15% by weight vinyl acetate and 8% by weight 1-vinyl-2-pyrrolidone. The melt viscosity measured at 140 ° C is 150 mPas.

Additive 2:

Terpolymer of 22% by weight vinyl acetate and 2.5% by weight 1-vinyl-2-pyrrolidone and a viscosity of 240 mPas at 140 ° C.

Additive 3:

Copolymer of ethylene and 15 wt .-% 1-vinyl-2-pyrrolidone and one Viscosity of 205 mPas at 140 ° C.

Additive 4:

Terpolymer made of ethylene, 27% by weight vinyl acetate and 20% by weight N-vinyl-N-methyl-acetamide and a melt viscosity of 143 mPas at 140 ° C.

Additive 5:

Copolymer of ethylene, 18 wt .-% N-vinyl-N-methyl-acetamide and a melt viscosity of 143 mPas at 140 ° C.

Additive 6:

Terpolymer of ethylene, 25% by weight vinyl propionate and 7% by weight Vinylimidazole and a melt viscosity of 260 mPas at 140 ° C.

Additive 7:

Terpolymer of ethylene, 13% by weight vinyl propionate and 10% by weight Dimethylaminoethyl methacrylate and a melt viscosity of 105 mPas at 140 ° C.

Additive 8:

Terpolymer of ethylene, 24% by weight vinyl acetate and 8% by weight Dimethylaminoethyl methacrylate and a viscosity of 93 mPas 140 ° C.

Characterization of the test oils: The boiling characteristics are determined in accordance with ASTM D-86 the CFPP value according to EN 116 and the determination of the cloud point according to ISO 3015. Test oil 1 Test oil 2 Initial boiling point [° C] 195 169 20% [° C] 226 240 30% [° C] 232 259 90% [° C] 281 359 95% [° C] 300 377 Cloud Point [° C] - 30.5 0 CFPP [° C] - 31 - 2nd S content [ppm] 14 171

Lubricating effect in middle distillates

The lubricating effect of the additives was carried out using an HFRR device from PCS Instruments on additive oils at 6 ° C. The High Frequency Reciprocating Rig Test (HFRR) is described in D. Wei, H. Spikes, Wear, Vol. 111, No. 2, p. 217, 1986. The results are reported as the coefficient of friction and wear scar. A low coefficient of friction and a low wear scar show a good lubricating effect. All additives were used as a 50% dispersion in solvent naphtha. As a comparison, a commercially available flow improver based on a copolymer of ethylene and 30% by weight of vinyl acetate and a melt viscosity V140 of 105 mPas is used. Wear Scar in Test Oil 1 example Additive friction Av. Movie [%] Wear Scar [µm] 1 - 0.62 19th 620 2nd 250 ppm additive 1 0.19 53 470 3rd 400 ppm additive 2 0.17 88 305 4th 500 ppm additive 2 0.19 57 430 5 300 ppm additive 3 0.17 92 265 6 500 ppm additive 4 0.20 68 441 7 500 ppm additive 5 0.16 85 293 8th 250 ppm additive 5 0.18 61 375 9 250 ppm additive 6 0.17 95 265 10th 125 ppm additive 6 0.19 58 443 11 300 ppm additive 7 0.21 55 441 12th 200 ppm additive 8 0.19 65 380 13 500 ppm ethylene-vinyl acetate copolymer (comparison) 0.31 9 619 CFPP effectiveness in test oil 1 100 ppm 200 ppm Additive 4 - 38 - 40 Additive 8 - 37 - 39 Wear in test oil 2 example Additive friction Av. Movie [%] Wear Scar [µm] 14 - 0.45 25th 590 15 300 ppm additive 1 0.14 88 302 16 300 ppm additive 2 0.13 92 275 17th 250 ppm additive 8 0.16 78 420 18th 300 ppm ethylene vinyl acetate copolymer (comparison) 0.42 23 585 CFPP effectiveness in test oil 2 50 ppm 100 ppm 200 ppm Additive 4 - 5th - 8th - 12th Additive 6 - 6th - 9 - 11 Additive 8 - 8th - 10th - 13th 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 to 287 ° C ®Exxsol Dearomatized solvents in various boiling ranges, for example ®Exxsol D60: 187 to 215 ° C ®ISOPAR (Exxon) isoparaffinic solvent mixtures in various boiling ranges, for example ®ISOPAR L: 190 to 210 ° C ®Shellsol D mainly aliphatic solvent mixtures in different boiling ranges

Claims (7)

Use of 0.001 to 2% by weight (based on the fuel oil) an additive which contains at least one copolymer which in addition to Structural units derived from ethylene also include such structural units has, which are derived from an ethylenically unsaturated compound, the at least one aromatic or aliphatic nitrogen atom Exception of nitrogen atoms in imide bond has to improve the Lubricating effect of fuel oils. Use according to claim 1, characterized in that the nitrogenous comonomer a derivative of acrylic acid or a nitrogenous one is an organic compound bearing a vinyl residue. Use according to claim 1 and / or 2, characterized in that it is the nitrogen-containing comonomer a) aminoethyl acrylate, aminopropyl acrylate, amino-n-butyl acrylate, N-methylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminopropyl acrylate, N, N-diethylaminopropyl acrylate, and the corresponding methacrylate b) ethyl acrylamide, butyl acrylamide, N-octylacrylamide, N-propyl-N-methoxyethylacrylamide, N-methylolacrylamide and the corresponding methacrylamides, c) N-vinyl-N-methylacetamide, d) aminopropyl vinyl ether, diethylaminoethyl vinyl ether, dimethylaminopropyl vinyl ether, e) allylamine, N-allyl-N-methylamine, N-allyl-N-ethylamine, f) N-vinylpyrrolidone, methylvinylimidazole, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, vinylcarbazole, vinylimidazole, N-vinyl-2-piperidone or N-vinylcaprolactam. Use according to one or more of claims 1 to 3, characterized characterized in that the molar proportion of the nitrogen-containing comonomer on Copolymers is 0.1 to 15%, in particular 1 to 10%. Use according to one or more of claims 1 to 4, characterized characterized in that the melt viscosities of the copolymers below 10,000 mPas and preferably 10 to 1,000 mPas. Use according to one or more of claims 1 to 5, characterized characterized in that the copolymers in addition to ethylene and nitrogenous Comonomers comprise one, two or three further comonomers which are derived from the Group consisting of vinyl esters, acrylic acid, acrylic esters, vinyl ethers and / or Alkenes are selected. Agents for improving the lubricating effect of fuel oils, characterized by a content of the in one or more of the claims 1 to 6 described nitrogen-containing ethylene copolymers.