EP1134273A2 - Blends of carboxylic acids, derivatives thereof and hydroxyl groups carrying polymers, and use thereof to improve the lubricating activity of oils - Google Patents

Abstract

Lubricity additive for fuel oil contains: (A) 10-95 wt.% oil-soluble amphiphilic aliphatic or aromatic amide, (thio)carboxylic, imine and/or (thio)ether compound(s); and (B) 5-90 wt.% copolymer (weight average molecular weight 500-100000 g/mole; hydroxyl (OH) number 10-300 mg KOH/g) of olefinically unsaturated compounds including 0.5-15 mole-% OH compound(s) and 85-99.5 mole-% ethylene. Lubricity additive for fuel oil contains: (A) 10-95 wt.% oil-soluble amphiphilic aliphatic or aromatic amide or (thio)carboxylic compound(s) of formula R<1)<C(O)XR<2>)y (I) and/or imine or (thio)ether compound(s) of formula R<1>XR<2> (II); and (B) 5-90 wt.% copolymer(s) with a weight average molecular weight Mw of 500-100000 g/mole and hydroxyl (OH) number of 10-300 mg KOH/g, comprising units of (B.1) 0.5-15 mole-% olefinically unsaturated compound(s) with free OH group(s), (B.2) 85-95.5 mole-% ethylene and (B.3) 0-20 mole-% comonomer(s) selected from (meth)acrylic acid and esters, vinyl esters and ethers and alkenes. R<1> = 1-50 carbon (C) (hydroxy)alkyl, alkenyl or aryl; X = NH, NR<3>, O or S; y = 1, 2, 3 or 4; R<2> = hydrogen (H) or 2-10 C hydroxyalkyl; R<3> = N, 2-10 C hydroxyalkyl and/or 1-20 C alkyl; or XR<2> = NR<41>R<42>; R<41> = -(R<43>-NR<44>)m-R<45>-; R<42> = -(R<43>-NR<44>)n-R<45>; R<43> = 2-10 C alkylene; R<44> = H, methyl, 2-20 C alkyl, R<1>-CO- or alkoxy; R<45> = H or R<1>-CO-; m, n = 0-20. Independent claims are also included for: (a) fuel oil, comprising a middle distillate containing ≤ 0.05 wt.% sulfur, and 0.001-2 wt.% of the additive; and (b) mixtures of the additive with flow enhancers, comb polymers and/or paraffin dispersants.

Description

The present invention relates to an additive which is a long-chain carboxylic acid and / or their derivatives, and one or more polymers containing hydroxyl groups includes, fuel oils containing such additives, and the use of such Additives to improve the lubricity of middle distillates.

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 introduction of the standard relating to diesel fuels EN 590 currently writes a maximum sulfur content of 350 ppm. In Scandinavia, fuel oils are already coming in at less than 50 ppm and in exceptional cases with less than 10 ppm sulfur. This Fuel oils are usually made by taking those 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 maximum value for the 95% distillation point of maximum 360 ° C and now in Scandinavia further reduction of the 95% distillation point to below 350 ° C and sometimes below 330 ° C this problem is further exacerbated.

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

EP-A-0 743 974 discloses the use of mixtures of lubricity additives (Esters of polyhydric alcohols and carboxylic acids with 10 to 25 carbon atoms or Dicarboxylic acids) and flow improvers based on copolymers of ethylene and unsaturated esters to synergistically improve the lubricating effect of highly desulfurized oils.

EP-A-0 802 961 discloses fuel oils which improve their lubricating effect contain at least one hydroxyamine.

WO-99/36 489 discloses the use of mixtures of monomeric and polymeric fatty acids to improve the lubricating effect of low sulfur Middle distillates.

DE-A-197 57 830 discloses that hydroxyl-containing polymers are mixed with Acid derivatives can be used. However, it will not be technical Advantages of such mixtures are disclosed and no examples are given.

EP-A-0 807 676 discloses an additive to fuel oil, the Lubricity increases and that in addition to a carboxylic acid amide Cold flow improver and an ashless dispersant.

EP-A-0 680 506 discloses the use of esters of mono- or polyvalent Carboxylic acids with mono- or polyhydric alcohols as Lubricity-improving additive to fuel oils.

The lubricity additives of the prior art, as far as polymers are concerned are the disadvantage that they improve their viscosity due to their high viscosity Handling used as a solution or dispersion in suitable solvents Need to become. However, the use of solvents requires increased Dosing rates and thus the transport of large quantities of substances. The non-polymeric Due to their amphiphilic character, additives often show a pronounced character Tendency to emulsify. As a result, the residual water in storage tanks becomes stable Emulsions brought with the middle distillates, which are then regarding corrosivity and Cold flow properties can cause problems.

The object underlying the present invention was therefore to Find additive compositions that also in low emulsification tendency small amounts of additive are effective.

Surprisingly, it has been found that additive combinations consist of oil-soluble Amphiphiles and copolymers containing hydroxyl groups are the state of the art show their own disadvantages in a significantly reduced manner.

A) 10 - 95 Gew.-% mindestens eines öllöslichen Amphiphils der Formeln 1

und/oder 2 R1 ― X ― R2 worin R¹ einen Alkyl-, Alkenyl-, Hydroxyalkyl- oder aromatischen Rest mit 1 bis 50 Kohlenstoffatomen, X NH, NR³, O oder S, y = 1, 2, 3 oder 4, R² Wasserstoff oder einen Hydroxylgruppen tragenden Alkylrest mit 2 bis 10 Kohlenstoffatomen und R³ einen Stickstoff und/oder Hydroxylgruppen tragenden Alkylrest mit 2 bis 10 Kohlenstoffatomen oder einen C₁-C₂₀-Alkylrest bedeutet, und

B) 5-90 Gew.-% mindestens eines Copolymers welches

B1) 0,5 bis 15 mol-% Struktureinheiten, die sich von olefinisch ungesättigten Verbindungen ableiten, welche mindestens eine freie Hydroxylgruppe aufweisen,

B2) 85 bis 99,5 mol-% Struktureinheiten, die sich von Ethylen ableiten, sowie gegebenenfalls

B3) 0 bis 20 mol-% weiterer Struktureinheiten ausgewählt aus der Gruppe bestehend aus (Meth)acrylsäure, (Meth)acrylaten, Vinylestern, Vinylethern und Alkenen enthält, mit der Maßgabe, dass die unter B3) genannten Struktureinheiten von den unter B1) und B2) genannten Struktureinheiten verschieden sind,

und das Copolymer eine mittlere Molekülmasse Mw von 500 bis 100.000 g/mol und eine OH-Zahl zwischen 5 und 300 mg KOH/g aufweist.The invention relates to additives for improving the lubricating properties of fuel oils

A) 10-95% by weight of at least one oil-soluble amphiphile of the formula 1

and / or 2 R 1 - X - R 2 wherein R ^{1 is} an alkyl, alkenyl, hydroxyalkyl or aromatic radical having 1 to 50 carbon atoms, X NH, NR ³ , O or S, y = 1, 2, 3 or 4, R ^{2 is} hydrogen or an alkyl radical carrying hydroxyl groups 2 to 10 carbon atoms and R ^{3 is} a nitrogen and / or hydroxyl-bearing alkyl radical having 2 to 10 carbon atoms or a C ₁ -C ₂₀ alkyl radical, and

B) 5-90% by weight of at least one copolymer

B1) 0.5 to 15 mol% of structural units which are derived from olefinically unsaturated compounds which have at least one free hydroxyl group,

B2) 85 to 99.5 mol% of structural units which are derived from ethylene, and if appropriate

B3) contains 0 to 20 mol% of further structural units selected from the group consisting of (meth) acrylic acid, (meth) acrylates, vinyl esters, vinyl ethers and alkenes, with the proviso that the structural units mentioned under B3) differ from those under B1) and B2) structural units mentioned are different,

and the copolymer has an average molecular weight Mw of 500 to 100,000 g / mol and an OH number between 5 and 300 mg KOH / g.

Another object of the invention are fuel oils, the said Contain additives.

Another object of the invention is the use of additives for Improve the lubricating properties of fuel oils.

Another object of the invention is a method for improving the Lubricity of fuel oils.

The oil-soluble amphiphile (component A) preferably comprises a radical R ¹ having 5 to 40, in particular 12 to 26, carbon atoms. R ¹ is particularly preferably linear or branched and contains 1 to 3 double bonds in the case of linear radicals. The radical R ² preferably has 2 to 8, in particular 2 to 6, carbon atoms and can be interrupted by nitrogen and / or oxygen atoms. In a further preferred embodiment, the sum of the carbon atoms of R ¹ and R ^{2 is} at least 10, in particular at least 15 and at most 35, in particular at most 28 C atoms. In a further preferred embodiment, component A carries 2 to 5 hydroxyl groups, each carbon atom not carrying more than one hydroxyl group.

In a preferred embodiment of the invention, X in formula 1 has the Meaning of oxygen. In particular, they are fatty acids and esters between carboxylic acids and dihydric or polyhydric alcohols. Preferred esters contain at least 10, especially at least 12 carbon atoms. Prefers is also that the esters contain free hydroxyl groups, the esterification of the Polyol is not complete with the carboxylic acid. Suitable polyols are for example ethylene glycol, diethylene glycol and higher alkoxylation products, Glycerin, trimethylolpropane, pentaerythritol and sugar derivatives. Others too Polyols containing heteroatoms, such as triethanolamine, are suitable.

In a further preferred embodiment of the invention, the compounds that form component A of the additive to form fatty acids 10 to 22 carbon atoms. These can be saturated or unsaturated.

Preferred components A are straight-chain saturated fatty acids with up to 18 carbon atoms such as caprylic acid (octanoic acid), capric acid (decanoic acid), Lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (Hexadecanoic acid), stearic acid (octadecanoic acid) and especially unsaturated Fatty acids such as oleic acid (octadecenoic acid), linoleic acid, linolenic acid and their Mixtures such as Rapeseed acid, soy fatty acid, sunflower fatty acid, Peanut fatty acid and tall oil fatty acid. Furthermore, dimer and Oligomeric fatty acids, such as those used in the oligomerization of unsaturated fatty acids arise, be present. Preferably have at least 50%, in particular more than 70%, especially more than 90% of the fatty acids at least one Double bond.

Also preferred are oil-soluble partial esters of these fatty acids with polyols such as ethylene glycol, diethylene glycol and higher oligomers of alkylene oxides and glycerol, pentaerythritol, sorbitol, diethanolamine, triethanolamine and alkoxylated polyamines. Glycerol monooleate is particularly preferred. Esters which have at least two free OH groups and an alkyl radical having at least 8 C atoms are particularly preferred. The esters preferably have OH numbers between 10 and 200 mg KOH / g, preferably 20 to 150 mg KOH / g. R ³ preferably represents methyl or ethyl.

If X is a nitrogen-containing residue, reaction products of ethanolamine are Diethanolamine, hydroxypropylamine, dihydroxypropylamine, n-methylethanolamine, Diglycolamine and 2-amino-2-methylpropanol are suitable. The implementation takes place preferably by amidation, the resulting amides also containing free OH groups wear. Examples include fatty acid monoethanolamides and diethanolamides and called -N-methylethanolamide.

worin R¹ die oben angegebene Bedeutung hat, R⁴¹ einen Rest der Formel 3a -(R43-NR44)m-R45 und R⁴² einen Rest der Formel 3b -(R43-NR44)n-R45 bedeutet, R⁴³ für eine C₂- bis C₁₀-Alkylengruppe steht, R⁴⁴ Wasserstoff, Methyl, C₂- bis C₂₀-Alkyl, einen Rest der Formel 3c

oder einen Alkoxyrest, und R⁴⁵ H oder einen Rest der Formel 3c bedeutet, und m und n jeweils unabhängig voneinander eine ganze Zahl von 0 bis 20 bedeuten, wobei vorzugsweise

a) m und n nicht gleichzeitig null bedeuten, und

b) die Summe aus m und n mindestens 1 und höchstens 20 ist.
R⁴³ steht vorzugsweise für einen C₂- bis C₈-, insbesondere für einen C₂- bis C₄-Rest. Das Polyamin, von dem sich die aus R⁴¹, R⁴² und dem sie verbindenden Stickstoffatom gebildete Struktureinheit ableitet, ist vorzugsweise Ethylendiamin, Diethylentriamin, Triethylentetramin, Tetraethylenpentamin oder ein höheres Homologes des Aziridins wie Polyethylenimin, sowie deren Mischungen. Teile der Aminogruppe können alkyliert sein. Ebenfalls geeignet sind Sternamine und Dendrimere. Darunter versteht man Polyamine mit im allgemeinen 2-10 Stickstoffatomen, die über -CH₂-CH₂-Gruppen miteinander verbunden sind und die in randständiger Position mit Acyl- oder Alkylresten abgesättigt sind.

In one embodiment, the multifunctional additive can contain, as component A, compounds of the formula 3.

wherein R ^{1 has} the meaning given above, R ^{41 is} a radical of the formula 3a - (R 43 -NO 44 ) m -R 45 and R ^{42 is} a radical of the formula 3b - (R 43 -NO 44 ) n -R 45 means, R ^{43 represents} a C ₂ - to C ₁₀ -alkylene group, R ^{44 is} hydrogen, methyl, C ₂ - to C ₂₀ -alkyl, a radical of formula 3c

or an alkoxy radical, and R ^{45 is} H or a radical of the formula 3c, and m and n each independently represent an integer from 0 to 20, preferably

a) m and n do not simultaneously mean zero, and

b) the sum of m and n is at least 1 and at most 20.
R ⁴³ preferably represents a C ₂ - to C ₈ -, in particular a C ₂ - to C ₄ -rest. The polyamine from which the structural unit formed from R ⁴¹ , R ⁴² and the nitrogen atom connecting them is derived is preferably ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine or a higher homologue of aziridine such as polyethyleneimine, and mixtures thereof. Parts of the amino group can be alkylated. Sternamines and dendrimers are also suitable. This is understood to mean polyamines with generally 2-10 nitrogen atoms which are connected to one another via —CH ₂ —CH ₂ groups and which are saturated in the marginal position with acyl or alkyl radicals.

R ⁴⁴ preferably represents hydrogen, an acyl radical or an alkoxy group of the formula - (OCH ₂ CH ₂ ) _n -, where n is an integer between 1 and 10, and mixtures thereof.

worin
R⁴⁶ die Bedeutung von R¹,
R⁴⁷ die Bedeutung von R¹ oder H oder -[CH₂-CH₂-O-]_p-H und

R⁴⁸ die Bedeutung von R² haben können und

p eine ganze Zahl von 1 bis 10 bedeuten,

mit der Maßgabe, dass mindestens einer der Reste R⁴⁶, R⁴⁷ und R⁴⁸ eine OH-Gruppe trägt . Als Beispiel sei y-Hydroxybuttersäuretalgfettamid genannt.Compounds of the formula 3d are also suitable as an amphiphile

wherein
R ^{46 has} the meaning of R ¹ ,
R ^{47 is} R ¹ or H or - [CH ₂ -CH ₂ -O-] _p -H and

R ^{48 can have} the meaning of R ² and

p is an integer from 1 to 10,

with the proviso that at least one of the radicals R ⁴⁶ , R ⁴⁷ and R ⁴⁸ carries an OH group. As an example, y- hydroxybutyric acid tallow amide may be mentioned.

The amides are generally by condensation of the polyamines with the Carboxylic acids or their derivatives such as esters or anhydrides. It are preferably 0.2 to 1.5 mol, in particular 0.3 to 1.2 mol, especially 1 mol Acid used per base equivalent. The condensation is preferably carried out at Temperatures between 20 and 300 ° C, especially between 50 and 200 ° C below Distilling off the water of reaction. Solvents may be preferred aromatic solvents such as benzene, toluene, xylene, trimethylbenzene and / or commercial solvent mixtures such as B. Solvent Naphtha, ® Shellsol AB, ® Solvesso 150, ® Solvesso 200 are added to the reaction mixture. The Products according to the invention generally have a titratable Base nitrogen of 0.01 - 5% and an acid number of less than 20 mg KOH / g, preferably less than 10 mg KOH / g.

y preferably takes the values 1 or 2. Examples of preferred connecting groups with y = 2 are derivatives of dimer fatty acids and alkenylsuccinic anhydrides. The latter can carry linear as well as branched alkyl radicals, ie they can be derived from linear α-olefins and / or from oligomers of lower C ₃ -C ₅ olefins such as poly (propylene) or poly (isobutylene).

Preferred polyols have 2 to 8 carbon atoms. They preferably wear 2, 3, 4 or 5 hydroxyl groups, but no more than they contain carbon atoms. The The carbon chain of the polyols can be straight-chain, branched, saturated or unsaturated be and optionally contain heteroatoms. It is preferably saturated.

Preferred carboxylic acids, from which the radical R ^{1 is} derived, have 5 to 40, in particular 12 to 30, carbon atoms. The carboxylic acid preferably has one or two carboxyl groups. The carbon chain of the carboxylic acids can be straight-chain, branched, saturated or unsaturated. Preferably more than 50% of the carboxylic acids (mixtures) used contain at least one double bond. Examples of preferred carboxylic acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid and behenic acid, and carboxylic acids with heteroatoms such as ricinoleic acid. Dimeric and trimer fatty acids, such as those obtainable, for example, by oligomerizing unsaturated fatty acids, and alkenyl succinic acids can also be used.

In a preferred embodiment, component A uses ethers and amines of the formula 2. These are partial ethers of polyols, such as, for example, glycerol monooctadecyl ether or hydroxyl-bearing amines, as are obtainable, for example, by alkoxylation of amines of the formula R ¹ NH ₂ or R ¹ R ³ NH with alkylene oxides, preferably ethylene oxide and / or propylene oxide. 1-10, in particular 1-5, mol of alkylene oxide are preferably used per H atom of nitrogen.

The copolymer which forms component B of the additive according to the invention contains free OH groups.

In a preferred embodiment of the invention, the proportion of Structural units (B1) between 1 and 15, in particular 3 to 12 mol%. In a In another preferred embodiment, the copolymer has an OH number of 10 up to 300, in particular 20 to 200 mg KOH / g. In another preferred In one embodiment, the copolymer has an average molecular weight Mw of 700 up to 10,000 g / mol.

In the case of the olefinically unsaturated compounds which the comonomers (B1) make up, it is preferably vinyl esters, acrylic esters, mono- and Diesters of ethylenically unsaturated carboxylic acids, methacrylic esters, alkyl vinyl ethers and / or alkenes which are hydroxyalkyl, hydroxyalkenyl, hydroxycycloalkyl or Wear hydroxyaryl residues. These residues contain at least one hydroxyl group, which can be anywhere on the rest, but preferably on Chain end (ω position) or in para position for ring systems.

The vinyl esters are preferably those of the formula 4 CH 2 = CH - OCOR 4th wherein R ^{4 is} C ₁ -C ₃₀ hydroxyalkyl, preferably C ₁ -C ₁₆ hydroxyalkyl, especially C ₂ -C ₁₂ hydroxyalkyl, and the corresponding hydroxyoxalkyl radicals. Suitable vinyl esters include 2-hydroxyethyl vinyl esters, α-hydroxypropyl vinyl esters, 3-hydroxypropyl vinyl esters and 4-hydroxybutyl vinyl esters.

The acrylic esters are preferably those of the formula 5 CH 2 = CR 5 - COOR 6 wherein R ^{5 is} hydrogen or methyl and R ^{6 is} C ₁ -C ₃₀ hydroxyalkyl, preferably C ₁ -C ₁₆ hydroxyalkyl, especially C ₂ -C ₁₂ hydroxyalkyl and the corresponding hydroxyoxalkyl radicals. Suitable acrylic esters include hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, hydroxyisopropyl acrylate, 4-hydroxybutyl acrylate and glycerol monoacrylate. The corresponding esters of methacrylic acid and also esters of ethylenically unsaturated dicarboxylic acids such as maleic acid, fumaric acid or itaconic acid with diols are equally suitable.

The alkyl vinyl ethers are preferably compounds of the formula 6 CH 2 = CH - OR 7 wherein R ^{7 is} C ₁ -C ₃₀ hydroxyalkyl, preferably C ₁ -C ₁₆ hydroxyalkyl, especially C ₂ -C ₁₂ hydroxyalkyl and the corresponding hydroxyoxalkyl radicals. Suitable alkyl vinyl ethers include 2-hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hexanediol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and cyclohexanedimethanol monovinyl ether.

The alkenes are preferably monounsaturated Hydroxy hydrocarbons with 3 to 30 carbon atoms, especially 4 to 16 carbon atoms and especially 5 to 12 carbon atoms. Suitable alkenes include dimethylvinylcarbinol (= 2-methyl-3-buten-2-ol), allyloxypropanediol, 2-butene-1,4-diol, 1-butene-3-ol, 3-butene-1-ol, 2-butene-1-ol, 1-penten-3-ol, 1-penten-4-ol, 2-methyl-3-buten-1-ol, 1-hexen-3-ol, 5-hexen-1-ol and 7-octene-1,2-diol.

Up to 20 mol% of one or more may optionally be used as further comonomers B3) several olefinically unsaturated comonomers may be included. Suitable Comonomers are, for example, acrylic acid or methacrylic acid, acrylic acid esters of alcohols with 1 to 20 carbon atoms, in particular methyl acrylate, ethyl acrylate, Propyl acrylate, butyl acrylate and ethylhexyl acrylate, as well as the corresponding Methacrylic acid esters, vinyl esters such as vinyl acetate, vinyl propionate, hexyl vinyl ester and Vinyl esters of neocarboxylic acids with 8, 9, 10, 11 or 12 carbon atoms, Vinyl ethers and olefins with 3 to 20 carbon atoms such as propene, butene, isobutene, Penten, hexene, 4-methylpentene, diisobutylene, norbornene are copolymerized.

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, Diallylamin

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-Vinylcaprolactem.

Similarly, nitrogen-containing monomers such as

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, diallylamine

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-vinylcaprolactem.

The melt viscosities of the copolymers at 140 ° C. are preferably below 10,000 mPas, especially between 10 and 2000 mPas and especially between 15 and 1000 mPas. Oil-soluble in the sense of the invention means that at least 10% by weight, preferably at least 1% by weight, in particular at least 0.1% by weight of the Additive is clearly soluble in the middle distillate to be added.

The copolymers which form component B of the additive according to the invention can be obtained by direct polymerization of compounds that are specified Structural units are obtained. It is also possible to use a to produce polymer-analogous implementation.

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 ethyl 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 copolymers which are obtained by copolymers containing acid groups by oxalkylation. Suitable ethylene copolymers are, for example, those of 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 oxalkylated on the acid groups with C ₁ -C ₁₀ -alkylene oxides. Preferred alkylene oxides are ethylene oxide, propylene oxide and butylene oxide. The oxyalkylation is preferably carried out using 0.5 to 10 mol, in particular 1 to 5 mol and especially 1 to 2 mol of alkylene oxide per mol of acid group.

To prepare the copolymers according to the invention by means of a polymer-analogous reaction, the polymeric acid groups can also be reacted with at least bifunctional reagents which carry at least one OH function. Binding to the polymer can take place via hydroxyl groups as esters and / or via primary or secondary amino groups in the form of amides, imides and / or ammonium salts. To avoid crosslinking reactions, for example, an excess of bifunctional reagent and / or a high dilution can be used. The esterification, amidation or imidation generally takes place with the removal of water of reaction (azeotropic distillation, stripping with a gas stream such as N ₂ ). The residual acid number is set to values <150, preferably <20, in particular <10 mg KOH / g. Suitable reagents are, for example: ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, mixed alkoxylates of ethylene oxide, propylene oxide and / or butylene oxide with up to 50, in particular up to 10 units derived from ethylene oxide, propylene oxide and / or butylene oxide, glycerol, pentaerythritol, sorbitol, Ethanolamine, diethanolamine, triethanolamine, butyldiethanolamine, methyldiisopropylamine, aminopropanediol and alkoxylated polyamines. The latter can be derived, for example, from ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and their higher homologues, which are alkoxylated with 0.5 to 50, in particular 10 mol, ethylene oxide, propylene oxide and / or butylene oxide per H atom bound to an N atom . The reaction with the polymer can take place either via an OH group to form the ester or via a primary or secondary amino group to form the amide or imide.

The conversion of the copolymers containing acid groups takes place between 30 and 250 ° C over the course of 0.5 to 20 hours. The hydroxy-functional reagent will with amounts of about 1 to about 2 moles per mole of polymerized Acid (derivative) implemented.

The additives of the invention are mineral oils or mineral oil distillates preferably added as a mixture, the oil-soluble amphiphile A as a solvent for the copolymer B. Preferred mixtures are at temperatures flowable below 40 ° C, i.e. at this temperature they have a viscosity of less than 10 Pas, especially <1Pas. If one is too high for processing The viscosity and / or intrinsic pour point of the mixture can be up to 50% by weight, in particular up to 20% by weight, based on the additive of a solvent be added. Solvents can be aliphatic and / or aromatic Be hydrocarbons. The advantages of the additive combination according to the invention can also be used with separate dosing of components A and B. become.

Improved by the additives in their lubrication and / or cold flow properties Mineral oils or mineral oil distillates contain 0.001 to 2, preferably 0.005 to 0.5% by weight additive, based on the distillate.

The additives according to the invention can also be in the form of mixtures are used, which consist of additives of the claimed type, however differ in qualitative and / or quantitative composition. The mixing ratio (in parts by weight) of the additive components can be via a wide range and e.g. 20: 1 to 1:20, preferably 10: 1 to 1:10 be. In this way, the additives can be individually tailored Adjust requirements.

For the production of additive packages for special problem solutions the additives according to the invention also together with one or more oil-soluble Co-additives are used, which alone have the cold flow properties and / or improve the lubricating effect of crude oils, lubricating oils or fuel oils. Examples of such co-additives are copolymers containing vinyl acetate or Terpolymers of ethylene, polar compounds that have a paraffin dispersion effect (paraffin dispersants), comb polymers, alkylphenol-aldehyde resins and oil-soluble amphiphiles.

Mixtures of additives with copolymers have proven to be excellent, which contain 10 to 40% by weight of vinyl acetate and 60 to 90% by weight of ethylene. To a further embodiment of the invention sets the invention Additives mixed with ethylene / vinyl acetate / neononanoic acid vinyl ester terpolymers or ethylene-vinyl acetate / neodecanoic acid vinyl ester terpolymers to improve the flowability of mineral oils or Mineral oil distillates. The terpolymers of vinyl neononanoate or In addition to ethylene, neodecanoic acid vinyl esters contain 10 to 35% by weight of vinyl acetate and 1 to 25% by weight of the respective new compound. Other preferred copolymers contain in addition to ethylene and 10 to 35% by weight vinyl esters also 0.5 to 20% by weight Olefin such as diisobutylene, 4-methylpentene or norbornene. The mixing ratio of the additives according to the invention with those described above Ethylene / vinyl acetate copolymers or the terpolymers of ethylene, Vinyl acetate and the vinyl esters of neononanoic or neodecanoic acid is (in Parts by weight) 20: 1 to 1:20, preferably 10: 1 to 1:10.

For use as a flow improver and / or lubricity additive, the additives according to the invention furthermore in a mixture with paraffin dispersants be used. Paraffin dispersants reduce the size of the paraffin crystals and cause the paraffin particles not to settle, but colloidally with them significantly reduced sedimentation efforts, remain dispersed. Farther they increase the lubricating effect of the additives according to the invention. As Paraffin dispersants have become oil-soluble polar compounds with ionic or polar groups, e.g. Amine salts and / or amides proven by reaction 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 Pat. No. 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) 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 α, β-unsaturated dicarboxylic acid anhydrides, α, β-unsaturated compounds and Polyoxyalkylene ethers of lower unsaturated alcohols. Also alkylphenol aldehyde resins are suitable as paraffin dispersants.

worin R⁶ für C₄-C₅₀-Alkyl oder -Alkenyl, R⁷ für Ethoxy- und/oder Propoxy, n für eine Zahl von 5 bis 100 und p für eine Zahl von 0 bis 50 steht.The copolymers according to the invention can be used in a mixture with alkylphenol-formaldehyde resins. In a preferred embodiment of the invention, these alkylphenol-formaldehyde resins are those of the formula 7

wherein R ^{6 is} C ₄ -C ₅₀ alkyl or alkenyl, R ^{7 is} ethoxy and / or propoxy, n is a number from 5 to 100 and p is a number from 0 to 50.

Finally, in a further embodiment of the invention, the additives according to the invention 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 the case of copolymers, at least 20%, preferably at least 30%, of the monomers have side chains (cf. Comb-like Polymers-Structure and Properties; NA Plate and VP Shibaev, J. Polym. Sci. Macromolecular Revs. 1974, 8, 117 ff). Examples of suitable comb polymers are, for example, fumara / 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.

Comb polymers can be represented, for example, by Formula 8

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

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

M

H, COOR ", OCOR", OR "or COOH;

N

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

R '

a hydrocarbon chain with 8-150 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 additives according to the invention Paraffin dispersants, resins or comb polymers are each 1:10 to 20: 1, preferably 1: 1 to 10: 1.

The additives according to the invention are suitable for the lubricating properties of animal, vegetable or mineral oils with only low dosage rates improve. In addition, they improve the cold properties of the additive oils. The emulsifying properties of the additive oils less impaired than with the lubricating additives of the prior art Case is. The additives of the invention are for use in middle distillates particularly well suited. Middle distillates are particularly those Mineral oils obtained from crude oil distillation and in the range of Boil 120 to 450 ° C, for example kerosene, jet fuel, diesel and heating oil. The additives according to the invention are preferably used in such middle distillates used, the 0.05 wt .-% sulfur and less, particularly preferably less than 350 ppm sulfur, especially less than 200 ppm sulfur and in in special cases contain less than 50 ppm sulfur. It is in the general to those middle distillates that are hydrogenated refining were subjected, and therefore only small proportions of polyaromatic and contain polar compounds that give them a natural lubricating effect to lend. The additives of the invention are also preferably in such middle distillates, the 95% distillation points below 370 ° C, in particular 350 ° C and in special cases below 330 ° C. You can also can be used as components in lubricating oils.

The additives can be used alone or together with other additives e.g. with other pour point depressants or dewaxing aids, with Corrosion inhibitors, antioxidants, sludge inhibitors, dehazers and additives to lower the cloud point.

The effectiveness of the additives according to the invention as lubricity additives is determined by the following examples are explained in more detail.

Examples

The polymers A1-A4 were obtained by high-pressure bulk polymerization from ethylene, Vinyl acetate and hydroxy-functional comonomers according to DE-A-197 57 830 manufactured.

The hydroxy-functional comonomers are determined by determination the OH number by reacting the polymer with excess acetic anhydride and subsequent titration of the acetic acid formed with KOH.

The viscosity is determined in accordance with ISO 3219 (B) using a rotary viscometer (Haake RV 20) with a plate and cone measuring system at 140 or 160 C. Characterization of the hydroxy-functional copolymers Example No. Comonomer (s) A1 Terpolymer of ethylene, 24% by weight vinyl acetate and 9% by weight hydroxyethyl methacrylate with a melt viscosity at 140 ° C of 200 mPas and an OH number of 43 mg KOH / g A2 Terpolymer of ethylene, 24% by weight of vinyl acetate and 12% by weight of hydroxyethyl vinyl ether with a melt viscosity at 140 ° C. of 120 mPas and an OH number of 78 mg KOH / g. A3 Copolymer of ethylene and hydroxypropyl acrylate with a melt viscosity at 140 ° C of 138 mPas and an OH number of 145 mg KOH / g. A4 Terpolymer of ethylene, dimethyl vinyl carbinol and 15% by weight vinyl neodecanoate with a melt viscosity at 140 ° C. of 100 mPas and an OH number of 48 mg KOH / g. Characterization of the oil-soluble amphiphiles template B1 Oleic acid B2 Tall oil fatty acid B3 Glycerol monooleate B4 Poly (isobutenyl) succinic anhydride, twice esterified with diethylene glycol according to Example 1 from WO 97/45507 B5 Oleic acid diethanolamide B6 Glycerol monooctadecyl ether

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. Characterization of the test oils Test oil 1 Test oil 2 Test oil 3 Initial boiling point [° C] 182 171 188 20% [° C] 202 227 220 30% [° C] 208 243 228 90% [° C] 286 322 270 95% [° C] 302 338 278 Cloud Point [° C] -29 -9.4 -29 CFPP [° C] -32 -11 -33 S content [ppm] 3rd 38 6 Density [g / cm ³ ] 0.819 0.830 0.810 WS 1.4 [µm] 679 555 626

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 60 ° 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 given as the coefficient of friction and wear scar (WS 1.4). A low coefficient of friction and a low wear scar show a good lubricating effect Wear Scar in Test Oil 1 example Additive Wear scar Friction Movie 1 150 ppm A1 50% in B1 437 0.21 49 2 200 ppm A1 50% in B1 375 0.16 69 3rd 400 ppm A1 50% in B1 310 0.13 67 4th 100 ppm A1 50% in B3 406 0.17 67 5 300 ppm A1 50% in B3 193 0.13 94 6 250 ppm A2 50% in B2 276 0.14 73 7 200 ppm A3 50% in B4 318 0.15 69 8th 200 ppm A2 50% in B5 290 0.14 75 9 200 ppm A3 50% in B6 370 0.16 71 10 (see) 600 ppm A1 (50% in SN) 484 0.29 14 11 (see) 600 ppm A2 (50% in SN) 473 0.26 19th 12 (See) 150 ppm B1 435 0.18 51 13 (see) 100 ppm B3 389 0.18 72 Wear Scar in Test Oil 2 example Additive Wear scar Friction Movie 14 100 ppm A1 50% in B1 380 0.18 69 15 200 ppm A1 50% in B1 355 0.16 71 16 300 ppm A1 50% in B1 344 0.16 73 17th 200 ppm A1 50% in B3 385 0.19 67 18th 300 ppm A1 50% in B3 183 0.12 93 19th 150 ppm A4 50% in B5 365 0.17 74 20th 150 ppm A4 50% in B6 420 0.19 65 21 (See) 100 ppm A1 (50% in SN) 572 0.30 29 22 (See) 200 ppm A1 (50% in SN) 552 0.27 40 23 (See) 300 ppm A1 (50% in SN) 348 0.17 87 24 (see) 300 ppm B1 334 0.14 66 25 (see) 100 ppm B3 430 0.21 50 26 100 ppm A3 50% in B1 380 0.18 69 27 200 ppm A3 50% in B1 355 0.16 71 28 300 ppm A3 50% in B1 344 0.16 73 29 200 ppm A3 50% in B3 385 0.19 67 30th 300 ppm A3 50% in B3 183 0.12 93 Wear scar in test oil 3 example Additive Wear scar Friction Movie 31 300 ppm A3 50% in B1 381 0.16 68 32 400 ppm A3 50% in B1 364 0.15 69 33 (See) 200 ppm A3 (50% in SN) 632 0.34 16 34 (See) 300 ppm A3 (50% in SN) 593 0.29 36 35 (See) 400 ppm A3 (50% in SN) 303 0.16 87 36 (See) 300 ppm B1 367 0.17 68

Tendency to emulsify in middle distillates

The tendency to emulsify is determined in accordance with ASTM D-1094-85. For this, 80 ml of the diesel fuel in a 100 ml cylinder with the additive to be tested offset and 15 min. tempered at 60 ° C and shaken. After cooling down Room temperature, 20 ml of buffer solution pH 7.0 are added and 2 minutes shaken. After 5 minutes the sample is assessed optically.

1

klar und sauber

1b

kleine, klare Blasen, die schätzungsweise nicht mehr als 50 % der Trennschicht bedecken. Keine Schlieren, keine Filmbildung oder sonstige Benetzung an der Trennschicht.

2

Schlieren, Filmbildung oder sonstige Benetzung an der Trennschicht.

3

Schmaler Saum oder leichte Schaumbildung, oder beides.

4

Dichter Saum oder starke Schaumbildung, oder beides.

Evaluation of the interface:

1

clear and clean

1b

small, clear bubbles that are estimated to cover no more than 50% of the interface. No streaks, no film formation or other wetting at the interface.

2

Streaks, film formation or other wetting on the interface.

3rd

Narrow hem or slight foaming, or both.

4th

Thick hem or heavy foaming, or both.

Assessment of phase separation

1

Complete absence of all emulsions and / or deposits in two phases or on top of the oil phase.

2nd

Streaks, film formation or other wetting on the interface.

3rd

Emulsions and / or precipitates in both phases or on top of the oil phase, and / or drops in the water phase or adhering to the wall (except the wall above the oil phase).
The amount of the water phase is given in brackets.

Emulsifying test in test oil 1 example Additive A Additive B Interface Phase separation 37 (comparison) 250 ppm A1 - 1b 3 (20 ml) 38 (comparison) 250 ppm A3 - 1b 2 (20 ml) 39 (comparison) - 250 ppm B1 3rd 2 (18 ml) 40 (comparison) - 250 ppm B3 3rd 3 (6 ml) 41 125 ppm A1 125 ppm B1 1b 3 (20 ml) 42 250 ppm A1 250 ppm B1 1b 3 (20 ml) 43 125 ppm A1 125 ppm B3 1b 2 (20 ml) 44 250 ppm A1 250 ppm B3 1b 3 (20 ml) 45 125 ppm A3 125 ppm B1 1b 2 (20 ml) Emulsifying test in test oil 2 example Additive A Additive B Interface Phase separation 46 (see) 250 ppm A3 - 1b 2 (20 ml) 47 (see) - 250 ppm B1 2nd 2-3 (18 ml) 48 (see) - 250 ppm B3 2nd 2-3 (17 ml) 49 125 ppm A3 125 ppm B1 1b 2 (20 ml) 50 125 ppm A3 125 ppm B3 1b 2 (20 ml) Emulsification test in test oil 3 example Additive A Additive B Interface Phase separation 51 (comparison) 250 ppm A3 - 1b 1-2 (20 ml) 52 (comparison) 53 (comparison) - 250 ppm B1 2-3 2-3 (18 ml) 54 55 125 ppm A3 125 ppm B1 1b 2 (20 ml)

Claims (8)

Containing additives to improve the lubricating properties of fuel oils A) 10-95% by weight of at least one oil-soluble amphiphile of the formula 1

and / or 2 R 1 - X ―R 2 wherein R ^{1 is} an alkyl, alkenyl, hydroxyalkyl or aromatic radical having 1 to 50 carbon atoms, X NH, NR ³ , O or S, y = 1, 2, 3 or 4, R ^{2 is} hydrogen or an alkyl radical carrying hydroxyl groups 2 to 10 carbon atoms and R ^{3 is} a nitrogen and / or hydroxyl-bearing alkyl radical having 2 to 10 carbon atoms or a C ₁ -C ₂₀ alkyl radical, or XR ² is NR ⁴¹ R ⁴² , in which R ^{41 is} a radical of the formula 3a - (R 43 -NO 44 ) m -R- 45 and R ^{42 is} a radical of the formula 3b - (R 43 -NO 44 ) n R 45 means, R ^{43 represents} a C ₂ - to C ₁₀ -alkylene group, R ^{44 is} hydrogen, methyl, C ₂ - to C ₂₀ -alkyl, a radical of formula 3c R 1 -CO- or an alkoxy radical, and R ^{45 is} hydrogen or a radical of the formula 3c, and m and n each independently represent an integer from 0 to 20, and B) 5-90% by weight of at least one copolymer B1) 0.5 to 15 mol% of structural units which are derived from olefinically unsaturated compounds which have at least one free hydroxyl group, and B2) 85 to 99.5 mol% of structural units which are derived from ethylene, and if appropriate B3) contains 0 to 20 mol% of further structural units selected from the group consisting of (meth) acrylic acid, (meth) acrylates, vinyl esters, vinyl ethers and alkenes, with the proviso that the structural units mentioned under B3) differ from those under B1) and B2) structural units mentioned are different, and the copolymer has an average molecular weight Mw of 500 to 100,000 g / mol and an OH number between 5 and 300 mg KOH / g. The additive according to claim 1, wherein the copolymer B has an OH number of 15 to 200 mg KOH / g. Additive according to claim 1 and / or 2, wherein the copolymer B is a medium Molecular weight Mw from 700 to 10,000 g / mol. Additive according to one or more of claims 1 to 3, wherein the proportion of structural units B1 is between 1 and 15 mol%. Additive according to one or more of claims 1 to 4, wherein the Oil-soluble amphiphile is a fatty acid with 10 to 18 carbon atoms, or one of such a fatty acid derived ester. Fuel oil comprising a middle distillate with a sulfur content of 0.05 wt% or less, and 0.001 to 2 wt% of an additive according to one or more of claims 1 to 5. Use of an additive according to one or more of claims 1 to 5 to improve the lubricating effect of middle distillates with 0.05% by weight Sulfur content or less. Mixtures of an additive according to one or more of claims 1 to 5 with flow improvers, comb polymers and / or paraffin dispersants.