DE19816797C2 - Use of nitrogen-containing ethylene copolymers for the production of fuel oils with improved lubrication - Google Patents

Description

The present invention relates to a method for producing fuel oils with an improved lubricating effect due to the addition of nitrogenous ones Ethylene copolymers.

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 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 such as B. 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 exacerbates this problem. There are approaches in the prior art  described, which should represent a solution to this problem (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 below 0.2% by weight and aromatics contents below 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.

EP-A-0 405 270 discloses a method for improving the cold flowability of Mineral oils and mineral oil distillates. It consists of adding a mixture of an ethylene-vinyl acetate copolymer and an ethylene-vinyl acetate-N- Vinyl pyrrolidone terpolymer.

EP-A-0 061 696 discloses a method for improving the flowability of Mineral oils by adding a copolymer of 66 to 99.9% by weight of ethylene and 0.1 to 40% by weight vinyl acid amide.  

WO-96/18706 discloses the use of mixtures of lubricating additives and nitrogen compounds to improve the Lubricity of low-sulfur fuel oils. As nitrogen compounds come into question those which have a structural unit <NR, in which R is a Hydrocarbon residue with 8 to 40 carbon atoms means.

JP-A-62 045 692 discloses a cold flow improver for fuel oils, which Copolymers of ethylene, ring-closed nitrogen compounds with 5-7 Ring members and (meth) acrylic acid amide derivatives.

JP-A-09 208 973 discloses a lubricant improving additive for low sulfur Fuel oils, comprising polymers containing imide groups and structural units of Include α-olefins.

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 The process also has a favorable influence on the cold flow properties of these middle distillates 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% by weight (based on the fuel oil) of an additive in fuel oils with a maximum of 0.2% by weight of sulfur, which contains at least one copolymer which, in addition to structural units which are derived from ethylene also has 0.1-15 mol% of such structural units which are derived from a nitrogen-containing ethylenically unsaturated compound, selected from the group

• 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 methacrylates,
• 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-vinyl caprolactam,

and wherein the melt viscosities of the copolymers are 10 to 1,000 mPa.s amount to improve the lubricating effect of fuel oils.

The method according to the invention is preferably used for such fuel oils applied that less than 0.05, in particular less than 0.035 wt .-% sulfur contain.

The monomers used in addition to ethylene are commercially available or after known methods can be produced. So are the different ones Aminoalkylene (meth) acrylates e.g. B. according to EP-A-0188639 by transesterification of (Meth) acrylic acid esters with amino alcohols in the presence of a titanium catalyst accessible. The production of aminoalkyl vinyl ethers is e.g. B. in Liebigs Ann. Chem. 601 (1956), 81.

Such are for use in the method of the invention  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 between 140 ° C. 10 and 1000 mPa.s and especially between 20 and 500 mPa.s.

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. this z. B. 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 class include e.g. As 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. B. propane, aldehydes, e.g. B. propionaldehyde, n-butyraldehyde or isobutyraldehyde, ketones, e.g. B. acetone, methyl ethyl ketone, Methyl isobutyl ketone, cyclohexanone or alcohols, e.g. B. 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.

The high pressure bulk polymerization is in known high pressure reactors, e.g. B. 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 20-80% by weight, of the polymers included, added. Suitable solvents or dispersing agents are aliphatic and / or aromatic hydrocarbons or hydrocarbon mixtures, e.g. B. 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 z. B. 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 do not settle, but colloidally with significantly reduced Sedimentation efforts, remain dispersed. Furthermore, they reinforce the Lubricating effect of the copolymers containing nitrogen. Have as paraffin dispersants oil-soluble polar compounds with ionic or polar groups, e.g. B. 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) 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.

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 e.g. B. fumarate / vinyl acetate copolymers (cf. EP 0 153 176 A1), copolymers of a C ₆ -C ₂₄ -α-olefin and an NC ₆ -C ₂₂ - alkylmaleimide (cf. EP 0 320 766), furthermore esterified olefin / Maleic anhydride copolymers, polymers and copolymers of α-olefins and esterified copolymers of styrene and maleic anhydride.

For example, comb polymers can be represented by the formula

to be discribed. Mean in it
A R ', COOR', OCOR ', R "-COOR' or OR ';
DH, CH ₃ , A or R ";
EH or A;
GH, R ", R" -COOR ', an aryl radical or a heterocyclic radical;
MH, COOR ", OCOR", OR "or COOH;
NH, R ", COOR", OCOR, COOH or an aryl radical;
R 'is a hydrocarbon chain of 8-50 carbon atoms;
R "is a hydrocarbon chain of 1 to 10 carbon atoms;
m is a number between 0.4 and 1.0; and
n is 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. B. 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 of ethylene, 15% by weight of vinyl acetate and 8% by weight 1-vinyl-2-pyrrolidone. The melt viscosity measured at 140 ° C is 150 mPa.s.

Additive 2: terpolymer of 22% by weight vinyl acetate and 2.5% by weight 1-vinyl-2- pyrrolidone and a viscosity of 240 mPa.s at 140 ° C.

Additive 3: copolymer of ethylene and 15% by weight of 1-vinyl-2-pyrrolidone and one Viscosity of 205 mPa.s at 140 ° C.

Additive 4: terpolymer of ethylene, 27% by weight of vinyl acetate and 20% by weight N-vinyl-N-methyl-acetamide and a melt viscosity of 143 mPa.s at 140 ° C.

Additive 5: copolymer of ethylene, 18% by weight of N-vinyl-N-methyl-acetamide and a melt viscosity of 143 mPa.s at 140 ° C.

Additive 6: terpolymer of ethylene, 25% by weight of vinyl propionate and 7% by weight Vinylimidazole and a melt viscosity of 260 mPa.s at 140 ° C.

Additive 7: terpolymer of ethylene, 13% by weight of vinyl propionate and 10% by weight Dimethylaminoethyl methacrylate and a melt viscosity of  105 mPa.s at 140 ° C.

Additive 8: terpolymer of ethylene, 24% by weight of vinyl acetate and 8% by weight Dimethylaminoethyl methacrylate and a viscosity of 93 mPa.s 140 ° C.

Table 1 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

Lubricating effect in middle distillates

The lubricating effect of the additives was determined using an HFRR device from PCS Instruments performed 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 as a coefficient of friction and wear Scar stated. A low coefficient of friction and a low wear scar show a good lubricating effect. All additives were in 50% dispersion in Solvent naphtha used. As a comparison, a commercially available flow improver  based on a copolymer of ethylene and 30 wt .-% vinyl acetate and one Melt viscosity V140 of 105 mPa.s used.

Table 2

Wear Scar in Test Oil 1

Table 3

CFPP effectiveness in test oil 1

Table 4

Wear scar in test oil 2

Table 5

CFPP effectiveness in test oil 2

List of trade names used

Solvent Naphtha aromatic solvent mixtures with boiling range 180
®Shellsol AB up to 210 ° C
®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 (4)

1. Use of 0.001 to 2% by weight (based on the fuel oil) of an additive in fuel oils with a maximum of 0.2% by weight of sulfur which contains at least one copolymer which, in addition to structural units which are derived from ethylene, also Has 1-15 mol% of such structural units which are derived from a nitrogen-containing ethylenically unsaturated compound, selected from the group

• 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,

and wherein the melt viscosities of the copolymers are 10 to 1,000 mPa.s to improve the lubricating effect of fuel oils. 2. Use according to claim 1, characterized in that the molar  The proportion of the nitrogen-containing comonomer in the copolymer is 1 to 10%. 3. Use according to claim 1 or 2, characterized in that the Copolymers in addition to ethylene and nitrogen-containing comonomers one, two or three include further comonomers selected from the group consisting of vinyl esters, Acrylic acid, acrylic ester, vinyl ether and / or alkenes are selected. 4. agents for improving the lubricating effect of fuel oils, characterized by a content of the in one or more of the claims 1 to 3 described nitrogen-containing ethylene copolymers.