EP1419224A2

EP1419224A2 - Additives with a reduced tendency to emulsify, which improve the lubricating action of highly desulphurised fuel oils

Info

Publication number: EP1419224A2
Application number: EP02762334A
Authority: EP
Inventors: Matthias Krull; Markus Kupetz
Original assignee: Clariant Produkte Deutschland GmbH; Clariant GmbH
Current assignee: Clariant Produkte Deutschland GmbH
Priority date: 2001-07-27
Filing date: 2002-07-09
Publication date: 2004-05-19
Anticipated expiration: 2022-07-09
Also published as: JP4822665B2; JP2004536216A; EP1419224B1; ES2385646T3; WO2003012015A3; CA2455679C; US20060254128A1; DE10136828A1; CA2455679A1; US7431745B2; DE10136828B4; WO2003012015A2

Abstract

The invention relates to an additive for improving the lubrication capacity of fuel oils with a maximum sulphur content of 0.035 wt. %. Said additive contains at least one ester of a bivalent or polyvalent alcohol and a mixture of unsaturated and optionally saturated fatty acids, whose carbon chain lengths are between 8 and 30 carbon atoms, the aforementioned esters having an OH value less than 200 mg KOH/g ester and an iodine value greater than 100 g I/100 g ester. The invention also relates to fuel oils with a maximum sulphur content of 0.035 wt. %, which contain the inventive additives. The novel additives exhibit less tendency to emulsify than the additives in prior art.

Description

description

Lubricant-improving additives with reduced tendency to emulsify for highly desulfurized fuel oils

The present invention relates to additives from esters between polyols and fatty acid mixtures, and to their use for improving the lubricating effect of highly desulfurized fuel oils with a reduced tendency to emulsify.

Mineral oils and mineral oil distillates which are used as fuel oils generally contain 0.5% by weight or more of sulfur, which causes the formation of sulfur dioxide during combustion. In order to reduce the resulting environmental pollution, the sulfur content of fuel oils is continuously reduced. The diesel fuel standard EN 590 currently prescribes a maximum sulfur content of 350 ppm in Germany. Fuel oils with less than 50 ppm and in exceptional cases with less than 10 ppm sulfur are already used in Scandinavia. These fuel oils are usually produced by hydrogenation refining the fractions obtained from the petroleum by distillation. Desulphurization also removes other substances that give the fuel oils a natural lubricating effect. These substances include, among others, polyaromatic and polar compounds.

However, it has now been shown that the friction and wear-reducing properties of fuel oils deteriorate with increasing levels of desulfurization. Often these properties are so inadequate that the materials lubricated by the fuel, such as the distributor injection pumps of diesel engines, are likely to start seizing after a short time. The maximum value set according to EN 590 since 2000 for the 95% distillation point of maximum 360 ° C and the meanwhile in Scandinavia further reducing the 95% distillation point to below 350 ° C and sometimes below 330 ° C further aggravates this problem. Approaches are therefore described in the prior art which are intended to represent a solution to this problem (so-called lubricity additives).

EP-A-0 680 506 discloses that esters of fatty acids give highly desulfurized fuel oils an improved lubricating effect. Glycerol monooleate and diisodecyl adipate are mentioned in particular.

EP-A-0 739 970 discloses the suitability of fatty acid mixtures for improving the lubricity of low-sulfur fuel oils. Compositions of various degrees of esterification and various degrees of saturation of the fatty acids are disclosed.

EP-A-0 839 174 discloses in its lubricating effect improved fuel oils which are low in sulfur and comprise a mixture of polyol esters with unsaturated fatty acids.

However, the fatty acid esters of the prior art based on commercial fatty acid mixtures show a pronounced tendency to emulsify in the fuel oils added with them. This means that when such a fuel oil comes into contact with water, the water in the fuel oil emulsifies. These emulsions, particularly found at the oil / water phase boundary, cannot be separated or can only be separated with great effort. Since these emulsions cannot be used as fuel oils as such, they reduce the value of the products. This problem is particularly pronounced when esters based on natural fatty acid mixtures are used.

The object of the present invention was therefore to find lubricant-improving additives for desulfurized fuel oils which have a reduced tendency to emulsify compared to the prior art.

Surprisingly, it was found that esters from fatty acid mixtures, which show a certain combination of hydroxyl number and iodine number, do not have the emulsifiability of the prior art esters and have an excellent lubricating effect in desulfurized fuel oils. The reduced tendency to emulsify is presumably caused by two effects: firstly, the polarity range of the additives, determined by the OH number, results in a reduced affinity of the amphiphilic active substances for water. On the other hand, the formation of micellar, surface-active structures is disturbed by the number of double bonds in the alkyl radicals, which is determined by means of the iodine number.

The invention therefore relates to an additive for improving the

Lubricity of fuel oils with a maximum sulfur content of 0.035% by weight, containing at least one ester of a dihydric or polyhydric alcohol and a mixture of unsaturated and optionally saturated fatty acids, the carbon chain lengths of which are between 8 and 30 carbon atoms, the esters mentioned being OH - have a number of less than 200 mg KOH / g ester and an iodine number of more than 100 g 1/100 g ester.

The invention further relates to fuel oils with a maximum sulfur content of 0.035% by weight, which contain the additives according to the invention.

Another object of the invention is the use of the additives according to the invention to improve the lubricating effect of fuel oils with a sulfur content of at most 0.035% by weight.

Another object of the invention is a method for improving the lubricating effect of fuel oils with a sulfur content of at most 0.035% by weight by adding the additive according to the invention to the fuel oils.

Preferred fatty acids that are part of the fatty acid mixture are those with 10 to 26 carbon atoms, in particular 12 to 22 carbon atoms. The alkyl residues of the fatty acids consist essentially of carbon and hydrogen. However, you can add other substituents such as hydroxy, halogen, amino or Nitro groups, provided they do not affect the predominant hydrocarbon character. The fatty acids contained in the fatty acid mixture preferably contain at least one double bond. They can contain several double bonds, for example 2 or 3 double bonds, and can be of natural or synthetic origin. With polyunsaturated

Carboxylic acids can have their double bonds isolated or conjugated. In preferred fatty acid mixtures, at least 50% by weight, in particular at least 75% by weight, especially at least 90% by weight, of the fatty acids contain one or more double bonds. The iodine numbers of the fatty acids on which the esters according to the invention are based are preferably between 105 and 190, in particular 110 to 180 and especially 120 to 180 g 1/100 g of ester.

Suitable fatty acid mixtures contain at least two unsaturated fatty acids with 10 to 26 carbon atoms. Suitable unsaturated fatty acids are, for example, oleic acid, erucic acid, palmitoleic, myristoleic, linoleic, linolenic, elaeosteric, arachidonic, and / or ricinoleic acid. According to the invention, preference is given to fatty acid mixtures or fractions obtained from natural fats and oils, such as e.g. Peanut oil, fish, linseed, palm, rapeseed, ricin, castor, rape, soybean, sunflower and tall oil fatty acids are used, which have the corresponding iodine numbers.

In addition, the fatty acid mixtures can contain minor amounts, i.e. up to 10% by weight, preferably less than 5%, especially less than 2%, of saturated fatty acids such as, for example, lauric, tridecane, myristic, pentadecane, palmitin, margarine, stearin, isostearin, arachine and Contain beenic acid.

Also suitable as constituents of the fatty acid mixtures are dicarboxylic acids, such as dimer fatty acids and alkyl and alkenyl succinic acids with C ₈ -C ₅₀ alk (en) yl residues, preferably with C _δ -C o, especially with C ₁₂ -C ₂₂ alkyl residues. The alkyl radicals can be linear or branched (oligomerized alkenes, PIB). Portions of up to 10% by weight, in particular less than 5% by weight, are preferred. The fatty acids can further contain 1-40, especially 1-25 wt .-%, in particular 1-5 wt .-% resin acids.

Suitable alcohols preferably contain 2 to 6, in particular 3 to 4, carbon atoms, and 2 to 5, in particular 3 to 4, hydroxyl groups, but at most one hydroxyl group per carbon atom. Particularly suitable alcohols are ethylene glycol, diethylene glycol, propylene glycol, glycerin and pentaerythritol.

The esters can be prepared from alcohols and fatty acids in a known manner by esterification. Alternatively, partial saponification of naturally occurring fats and oils is also possible. Esters according to the invention are those which can be prepared from a dihydric or polyhydric alcohol and a mixture of fatty acids. This includes mixtures of, for example, monoesters of an alcohol with different fatty acids, of monoesters of different alcohols with different fatty acids, and also of mixtures of mono-, di- and / or triesters, or possibly higher esters, of one or more alcohols with different fatty acids , According to the invention, the esters are if they can be prepared from a fatty acid mixture.

The iodine numbers of the esters according to the invention are preferably between 100 and 180, in particular 110 to 150 g, 1/100 g of ester. The iodine numbers result from the iodine number of the underlying fatty acid mixture and the alcohol used for the esterification in a stoichiometric manner.

The OH number of the esters in the additive according to the invention is preferably between 110 and 195, in particular between 130 and 190 mg KOH / g ester. As a rule, these are mixtures of different esters, e.g. B. to mixtures of mono-, di- and triglycerides, mixtures such as those formed in the esterification of polyols.

The additives of the invention are oils in amounts from 0.001 to

0.5 wt .-%, preferably 0.005 to 0.3 wt .-% and especially 0.01 to 0.1 wt .-% added. They can be used as such or dissolved in solvents such as aliphatic and / or aromatic hydrocarbons or hydrocarbon mixtures such as toluene, xylene, ethylbenzene, decane, pentadecane, gasoline fractions, kerosene or commercial solvent mixtures such as solvent naphtha, ^® Shellsol AB, ^® Solvesso 150, ^® Solvesso 200, ^® Exxsol-, ^® Isopar and ^® Shellsol D types can be used. The additives according to the invention preferably contain 1-80%, especially 10-70%, in particular 25-60% solvents. The additives, which can also be used without problems at low temperatures of, for example, -30 ° C and lower, improve the lubricity of the additive oils while reducing the tendency to emulsify.

To produce additive packages for special problem solutions, the additives according to the invention can also be used together with one or more oil-soluble co-additives, which alone improve the cold flow properties and / or lubricating effect of crude oils, lubricating oils or fuel oils. Examples of such co-additives are vinyl acetate-containing copolymers or terpolymers of ethylene, paraffin dispersants, comb polymers, alkylphenol-aldehyde resins and oil-soluble amphiphiles.

Mixtures of the additives according to the invention with copolymers which contain 10 to 40% by weight of vinyl acetate and 60 to 90% by weight of ethylene have proven to be outstanding. According to a further embodiment of the invention, the additives according to the invention are mixed with ethylene / vinyl acetate / vinyl neononanoate terpolymers or ethylene-vinyl acetate /

Neodecanoic acid vinyl ester terpolymers for the simultaneous improvement of the flowability and lubricating effect of mineral oils or mineral oil distillates. The terpolymers of vinyl neononanoate or vinyl neodecanoate contain, in addition to ethylene, 10 to 35% by weight of vinyl acetate and 1 to 25% by weight of the respective neo compound. More preferred

In addition to ethylene and 10 to 35% by weight of vinyl esters, copolymers also contain 0.5 to 20% by weight of olefin such as diisobutylene, 4-methylpentene or norbornene. The mixing ratio of the additives according to the invention with the above described 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 reaction products according to the invention can also be used together with paraffin dispersants. Paraffin dispersants reduce the size of the paraffin crystals and ensure that the paraffin particles do not settle, but remain dispersed colloidally with a significantly reduced tendency to sedimentation. Furthermore, they increase the lubricating effect of the additives according to the invention. Oil-soluble polar compounds with ionic or polar groups, e.g. Amine salts and / or amides, which are obtained by reacting aliphatic or aromatic amines, preferably long-chain aliphatic amines, with aliphatic or aromatic mono-, di-, tri- or tetracarboxylic acids or their anhydrides (cf. US Pat. No. 4,211,534). Other paraffin dispersants are copolymers of maleic anhydride and σ, β-unsaturated compounds, which can optionally be reacted with primary monoalkylamines and / or aliphatic alcohols (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 σ, ß-unsaturated dicarboxylic acid anhydrides, σ, ß-unsaturated compounds and polyoxyalkylene ethers of lower unsaturated alcohols. Alkylphenol aldehyde resins are also suitable as paraffin dispersants.

For example, the additives 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

wherein R ^{A is} C ₄ -C ₅₀ alkyl or alkenyl, R ^{B 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. It is 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; N.A. Plate and V.P. Shibaev, J. Polym. Sci. Macromolecular Revs. 1974, 8, 117 ff). Examples of suitable ones

Comb polymers are, for example, fumarate / vinyl acetate copolymers (cf. EP 0 153 176 A1), copolymers of a C ₆ -C ₂₄ -o ^r -olefin and an NC ₆ -C ₂₂ -alkylmaleimide (cf. EP 0 320 766), furthermore esterified olefin / maleic anhydride copolymers, polymers and copolymers of σ-olefins and esterified copolymers of styrene and maleic anhydride.

Comb polymers can, for example, by the formula

A H G H

c - C c - C m

DMN to be discribed. In it AR \ 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 8-150 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 the additives according to the invention with resins or comb polymers is in each case 1:10 to 20: 1, preferably 1: 1 to 10: 1.

The additives according to the invention are particularly well suited for use in middle distillates. Middle distillates are mineral oils that are obtained by distilling crude oil and boil in the range of 120 to 450 ° C, such as kerosene, jet fuel, diesel and heating oil. The oils can also contain or consist of alcohols such as methanol and / or ethanol. The additives according to the invention are preferably used in middle distillates which contain less than 350 ppm sulfur, in particular less than 200 ppm sulfur and in special cases less than 50 ppm sulfur. These are generally middle distillates which have been subjected to hydrogenation refining and which therefore contain only small amounts of polyaromatic and polar compounds which give them a natural lubricating effect. The additives according to the invention are furthermore preferably used in middle distillates which have 95% distillation points below 370 ° C., in particular 350 ° C. and in special cases below 330 ° C. They can also be used as components in lubricating oils.

The mixtures can be used alone or together with other additives are used, for example with pour point depressants or dewaxing aids, with corrosion inhibitors, antioxidants, sludge inhibitors, dehazem, conductivity improvers, lubricity additives, and additives to lower the cloud point. Furthermore, they are successfully used together with additive packages, which contain well-known ash-free dispersing additives, detergents, defoamers and corrosion inhibitors. The synergisms described in the prior art with regard to cold flow properties according to WO 95/03377 and lubricity according to WO 96/18708 and WO 96/23855 are achieved between the additives according to the invention and the further additives mentioned.

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

Examples

Table 1: Characterization of the additives used (erf = according to the invention, V = comparison)

The OH numbers are defined in accordance with DIN 53240 by implementation with a Amount of excess acetic anhydride and subsequent titration of the acetic acid formed determined.

Iodine numbers are determined according to Kaufmann. For this purpose, a defined, excess amount of a methanolic bromine solution is added to a sample of known mass, an amount of bromine equivalent to the content of double bonds in the sample attaching to the double bonds. The excess bromine is back-titrated with sodium thiosulfate.

Table 2: Esters according to the prior art (comparative values)

Emulsification tendency in middle distillates

The tendency of additives to emulsify is tested in accordance with ASTM D 1094-85. 80 ml of a diesel fuel are mixed with 250 ppm of the additive to be tested in a 100 ml standing cylinder and tempered and shaken at 60 ° C. for 15 minutes. After cooling to room temperature, 2 ml of buffer solution are added and shaken for 2 minutes. After 5 minutes, the sample is assessed optically according to the following criteria:

Table 3: Emulsification tendency of the additives

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.

A Scandinavian winter diesel with the following characteristics was used as the test oil:

Boiling range: 185 - 320 ° C

Density: 0.820 g / cm ³

Cloud Point: - 29 ° C

Sulfur content: 3 ppm

The boiling data are determined in accordance with ASTM D-86 and the cloud point in accordance with ISO 3015.

Table 4: Wear Scar in test oil 2

Claims

claims

1. Additive to improve the lubricity of fuel oils with a sulfur content of at most 0.035% by weight, containing at least one ester of a dihydric or polyhydric alcohol and a mixture of unsaturated and optionally saturated fatty acids, the carbon chain lengths of which are between 8 and 30 carbon atoms, wherein the esters mentioned have an OH number of less than 200 mg KOH / g ester and an iodine number of more than 100 g 1/100 g ester.

2. Additive according to claim 1, wherein the iodine number is between 100 and 180 g 1/100 g ester.

3. Additive according to claim 1 and / or 2, wherein the OH number is between 110 and 195 mg KOH / g ester.

4. Additive according to one or more of claims 1 to 3, wherein the fatty acids that are part of the fatty acid mixture contain 10 to 26 carbon atoms.

5. Additive according to one or more of claims 1 to 4, wherein the fatty acid mixtures contain up to 10 wt .-% of saturated fatty acids.

6. Additive according to one or more of claims 1 to 5, wherein the fatty acid mixtures contain up to 10 wt .-% of one or more dicarboxylic acids.

7. Additive according to one or more of claims 1 to 6, wherein the alcohols contain 2 to 6 carbon atoms.

8. Additive according to one or more of claims 1 to 7, wherein the alcohols contain 2 to 5 hydroxyl groups, but at most one hydroxyl group per carbon atom.

9. Fuel oils with a maximum of 0.035 wt .-% sulfur content, containing an additive according to one or more of claims 1 to 8 in amounts of 0.001 to 0.5 wt .-% based on the fuel oil.

10. Use of an additive according to one or more of claims 1 to 8 in amounts of 0.001 to 0.5 wt .-% based on the fuel oil, to improve the lubricating effect of fuel oils with at most

0.035% by weight sulfur content.