(19)
(11)EP 2 179 011 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
27.06.2018 Bulletin 2018/26

(21)Application number: 08786285.0

(22)Date of filing:  21.07.2008
(51)International Patent Classification (IPC): 
C10M 129/10(2006.01)
C10M 169/04(2006.01)
C10N 40/25(2006.01)
C10M 133/12(2006.01)
C10N 30/10(2006.01)
(86)International application number:
PCT/EP2008/059543
(87)International publication number:
WO 2009/013275 (29.01.2009 Gazette  2009/05)

(54)

LUBRICATING COMPOSITION FOR USE IN DIESEL ENGINES COMPATIBLE WITH BIOFUEL

SCHMIERMITTELZUSAMMENSETZUNG ZUR VERWENDUNG IN BIOKRAFTSTOFFKOMPATIBLEN DIESELMOTOREN

COMPOSITION LUBRIFIANTE DESTINEE A ETRE UTILISEE DANS DES MOTEURS DIESEL COMPATIBLES AVEC UN BIOCARBURANT


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

(30)Priority: 23.07.2007 JP 2007190658

(43)Date of publication of application:
28.04.2010 Bulletin 2010/17

(73)Proprietor: Shell Internationale Research Maatschappij B.V.
2596 HR The Hague (NL)

(72)Inventors:
  • SHINODA, Noriaki
    Tokyo 135-8074 (JP)
  • NAGATOMI, Eiji
    Tokyo 135-8074 (JP)

(74)Representative: Shell Legal Services IP 
p/a Carel van Bylandtlaan 16
2596 HR Den Haag
2596 HR Den Haag (NL)


(56)References cited: : 
EP-A- 0 432 089
EP-A- 0 586 194
WO-A-2004/081150
JP-A- 4 202 398
US-A- 3 652 411
EP-A- 0 456 925
EP-A- 0 799 883
WO-A-2006/105267
JP-A- 8 157 853
US-B1- 6 410 490
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] This invention relates to lubricating compositions for use in diesel engines that use biofuels.

    [0002] In recent years, as a contribution to reducing CO2 in the global environment, there has been increasing momentum towards making positive use of fuels derived from plants and produced through biomass technologies. However, in composition they are not necessarily similar to existing fossil fuels and so various problems that can be generated by biofuels may be expected. Various investigations are being made of techniques to cope with these in the lubricating oils used in internal combustion engines.

    [0003] In the case of the alcohol fuels which are principally used in the field of gasoline engines, admixture with water cannot be avoided, and engine parts undergo a larger amount of wear than in the case of gasoline. Solutions for these problems have therefore been proposed. See Japanese Laid-open Patent 5-70786 (1993).

    [0004] Biofuels for use in the diesel engines used in automotive vehicles have in some cases been produced by methyl esterification of plant oils, taking mainly rapeseed oil or sunflower oil as their raw material in France, German, and Italy within the EU, and mainly soybean oil as their raw material in the United States. In many cases, these fuels are used by mixing about 20% in a light oil.

    [0005] There are several points about these biodiesel fuels which must be borne in mind when using them. They have aspects which demand improvement simply in fuel terms in that their viscosities and pour points are rather high, and they are prone to oxidise because, being derived from plant oils, they contain many unsaturated fatty acids. Furthermore, these biodiesel fuels may compete directly with edible vegetable oils, and so they have not been studied as much as the above-mentioned alcohol fuels as alternatives to gasoline, and there have hardly been any attempts to improve lubricating oils in association with biodiesel fuels.

    [0006] In the above-mentioned diesel engines, because a mixture of biodiesel fuel with light oil is used, a phenomenon is seen whereby an unburnt portion of the biodiesel fuel becomes mixed with the lubricating oil, promoting ageing thereof. This creates difficulties for using the lubricating oil stably over long periods.

    [0007] EP0432089 describes a formulation containing A) a lubricant and a mixture of B) for example, at least one of the compounds O,O-bis-2-ethylhexylsodium dithiophosphate, O,O-bis-2-ethylhexylsodium thionophosphate, O,O-bis-2-methylpropylsodium dithiophosphate, O,O-bis-nonylphenylsodium dithiophosphate or S-[O,O-bis-2-ethyl-hexylthiophosphoryl]-potassium thioglycolate, C) at least one compound from the series of the aromatic amines, for example the diphenylamines or phenothiazines, and D) at least one compound from the series of the cyclic sterically hindered amines, the acyclic sterically hindered amines and the phenols substituted with alkyl radicals. Such lubricant formulations are said to have a high degree of stability towards oxidative degradation.
    WO2006/105267 discloses lubricating oil compositions with reduced phosphorus levels, for an internal combustion engine such as a diesel engine, providing superior oxidation control, and comprising a 4,4' methylenebis(2,6-di-tert-butylphenol), an alkylated diphenylamine, and in some alternatives an ester derived from 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid.

    [0008] The inventors have discovered that it is possible to inhibit ageing, and in particular degradation of the detergent performance of the lubricating oil, even after admixture with biodiesel fuel, by combining different types of anti-oxidant, a phenolic anti-oxidant and an amine-based anti-oxidant, in the lubricating oil composition.

    [0009] To this end, the present invention provides a lubricating composition for use in diesel engines compatible with biofuel, wherein the lubricating composition comprises a base oil belonging to Group III and/or Group II of the API base oil categories, from 0.5 to 5% by mass of a 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid and from 0.5 to 5% by mass of a diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene, the total content of the anti-oxidants being at least 2.5% by mass.

    [0010] According to this invention, it is possible to inhibit rapid degradation of the detergent performance and accelerated ageing of the lubricating oil, even after admixture of biodiesel fuel in the lubricating oil, by using different types of anti-oxidant, a 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid and a diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene, together, and thus it is possible to use the lubricating oil stably over a long period.

    [0011] The light fuel oils and the biodiesel oils used in diesel engines of automotive vehicles, as already mentioned, have various obvious differences, and according to the literature ("New biomass liquid fuels for the 21st century", published by the Kagaku Kogyo Nippo [The Chemical Daily] on 2002-04-25) they can be summarised as being the differences shown in Table 1.
    Table 1
     Biodiesel oilLight oil
    Pour point (°C) -5.5 -11.5
    Kinetic viscosity (mm2/s) 5.6 3.0
    Flash point (°C) 135 ∼ 145 88
    Sulphur content (%) 0.0001 0.2
    Carbon (%) 77.1 ∼ 77.9 87.2
    Hydrogen (%) 11.7 ∼ 11.8 12.8
    Oxygen (%) 11.1 ∼ 11.2 0


    [0012] As is evident from Table 1, among the aspects where biodiesel oils differ substantially from light oils is the content of constituent oxygen atoms. Also, it is believed that, since they contain double bonds derived from unsaturated fatty acids, the combustion reaction itself differs.

    [0013] Further, it may be mentioned that, in terms of physical properties, the flash point is higher than in light oils and they are more prone to evaporate. When supplied as fuel to engines, the reaction may cease in the elementary process on the way to complete combustion, and the unreacted portion will often mix with the lubricating oil or the unburnt constituents themselves will be mixed with the lubricating oil, causing the formation of sludge in the lubricating oil and accelerating ageing of the lubricating oil through oxidation.

    [0014] Given these facts, the lubricating oils will be characterised by being used under more rigorous conditions even than when exposed to high temperatures when using only light oils as the fuel.

    [0015] For the base oils of this invention it is possible to use any suitable mineral oil or synthetic oil, and normally it is possible to use base oils, singly or in mixtures, that belong to Group III and Group II of the base oil categories of the API (American Petroleum Institute).

    [0016] These Group III and Group II base oils include, for example, paraffinic mineral oils obtained by a high degree of hydrorefining in respect of lubricating oil fractions obtained by atmospheric distillation of crude oil, base oils refined by the Isodewax process which dewaxes and substitutes the wax produced by the dewaxing process with isoparaffins, base oils refined by the Mobil wax isomerisation process, and the so-called GTL (gas-to-liquid) base oils solvent dewaxed or catalyst dewaxed after synthesis by the Fischer-Tropsch method. They include also those that may be designated as "synthetic oils" according to the rulings of the NAD (National Advertising Division) which is responsible for advertising adjudications in America.

    [0017] A 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid and a diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene are blended together in these base oils.

    [0018] The amount of the above-mentioned 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid is from 0.5 to 5.0% by mass based on the total amount of the lubricating oil composition, and preferably from 0.5 to 2% by mass.

    [0019] The amount of the above-mentioned diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene is from 0.5 to 5.0% by mass based on the total amount of the lubricating oil composition, and preferably from 0.5 to 2% by mass.

    [0020] For both the above-mentioned 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid and diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene, if the amount is less than 0.5% by mass the oxidative stability decreases, which is undesirable, and if it exceeds 5% by mass the piston detergency decreases, which is often undesirable.

    [0021] The 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid and the diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene are used respectively in the above-mentioned amounts, but it is
    further required that the total amount of the two anti-oxidants at the same time is not less than 2.5% by mass. If the total amount of both is less than that, the expected effect will not be obtained.

    [0022] It is also possible to add to this lubricating oil composition, as required, suitable dispersants, extreme-pressure agents, detergents, viscosity index improvers and other additives.

    [0023] In another aspect the present invention provides a method of operating a diesel engine comprising lubricating the diesel engine with a lubricating composition according to the present invention and using a biofuel, preferably derived from rapeseed oil, as fuel.

    Examples



    [0024] The biodiesel fuel (BDF) was a methyl ester derived from rapeseed oil and was prepared so as to have the properties shown in Table 2.
    Table 2
    ItemTest methodUnitsCharacteristic (numeric value)
    Density: vibration method (15°C) JIS K-2249 g/cm3 0.883
    Flash point: PMCC method JIS K-2265 O C 155
    Kinetic viscosity: 30°C JIS K-2283 mm2/s 5.51
    Cetane value JIS K-2280   53.0


    [0025] The following constituent materials were used in preparation of the examples of embodiment and comparative examples.
    1. (1) Base oil: a mineral oil belonging to API Group III
    2. (2) Phenolic anti-oxidant: 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid
    3. (3) Amine-based anti-oxidant: diphenylamine being a reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene
    4. (4) Additives package: additives containing dispersant, ZnDTP and detergent.

    Examples 1-4, Comparative Examples 1-6



    [0026] Using the above-mentioned constituent materials, the lubricating oil compositions of Examples 1-4 and Comparative Examples 1-6 were prepared in accordance with Tables 3 and 4.

    [0027] The above-mentioned Comparative Example 6 was a composition with a JASO (Engine Oil Standards Implementation Panel) DH-2 level diesel combustion engine oil for use in automotive vehicles.

    [0028] The amounts of each constituent blended in are shown in each case as % by mass.

    Tests



    [0029] In order to view the performance of the lubricating oil compositions of Examples 1-4 and Comparative Examples 1-6, hot tube tests (according to JPI-5S-55-99; a standard test from the Japanese Petroleum Institute for determining high temperature deposits) were carried out at 280°C under load conditions whereby 5% by mass of biodiesel fuel was added in respect of 100% by mass of each lubricating oil composition.

    [0030] Evaluation of the hot tube tests was from 0 to 10 in fractions of 0.5, and 7 and above was set as the pass mark.

    Test results



    [0031] The results are shown in Tables 3 and 4. Example 1 is not according to the invention.
    Table 3
     Example 1Example 2Example 3Example 4
    Base oil 86 85 85.5 82
    Phenolic anti-oxidant 1.0 1.5 1.5 2.0
    Amine-based antioxidant 1.0 1.5 1.0 4.0
    Additives package 12 12 12 12
    Total 100 100 100 100
    Admixed BDF 5 5 5 5
             
    Hot tube score 7.0 7.0 7.0 7.5
    Table 4
     Comp. Ex. 1Comp. Ex. 2Comp. Ex. 3Comp. Ex. 4Comp. Ex. 5Comp. Ex. 6
    Base oil 88 85.5 84.5 85.5 86.5 88
    Phenolic anti-oxidant       2.5 0.5  
    Amine-based antioxidant   2.5 3.5   1.0  
    Additives package 12 12 12 12 12 12
    Total 100 100 100 100 100 100
    Admixed BDF 5 5 5 5 5  
                 
    Hot tube score 1.0 2.0 5.0 3.0 2.5 7.0

    Evaluation



    [0032] When using a 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid and a diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene together, as shown in Examples 1-4, the amount of each being not less than 1% by mass and the total amount being not less than 2% by mass, an evaluation of 7 or higher was obtained in the hot tube test in all cases, and it was evident that these were lubricating oil compositions not prone to ageing after admixture of biofuel.

    [0033] Anti-oxidants were not added in the case of Comparative Example 1, and the hot tube score was poor, 1.0. Comparative Example 2 used 2.5% by mass of only the diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene, and although the total amount exceeded 2% by mass the hot tube score was poor at 2.0. More diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene was added to Comparative Example 3 than in Comparative Example 2, but the hot tube score rose only to 5.0. Comparative Example 4 used 2.5% by mass of only the 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid, and although the total amount exceeded 2% by mass the hot tube score was poor at 3.0. Comparative Example 5 used both anti-oxidants together, but the total amount was less than 2% by mass and so the hot-tube score was poor at 2.5. A satisfactory effect was thus not obtained for any of Comparative Examples 1-5

    [0034] Comparative Example 6 had no admixture of biofuel, and even though no 6 methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl)propionic acid or diphenylamine which is the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene was used, the hot tube score was 7.0 and it can be seen that a satisfactory effect was obtained.


    Claims

    1. A lubricating composition for use in diesel engines compatible with biofuel, wherein the lubricating composition comprises a base oil belonging to Group III and/or Group II of the API base oil categories, from 0.5 to 5% by mass of a 6-methylheptyl alcohol ester of 3-(4-hydroxy-3,5-di-t-butyl-phenyl) propionic acid and from 0.5 to 5% by mass of a diphenylamine which is a reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene, the total content of the anti-oxidants being at least 2.5% by mass.
     
    2. A lubricating composition according to Claim 1 wherein the biofuel used in the diesel engine is derived from rapeseed oil.
     
    3. Use of the lubricating composition according to claim 1 or claim 2 in a diesel engine, and wherein a biofuel is used in the diesel engine, preferably a biofuel derived from rapeseed oil.
     
    4. A method of operating a diesel engine comprising lubricating the diesel engine with a lubricating composition according to any of claims 1 to 2 and using a biofuel, preferably derived from rapeseed oil, as fuel.
     


    Ansprüche

    1. Schmiermittelzusammensetzung zur Verwendung in biokraftstoffkompatiblen Dieselmotoren, wobei die Schmiermittelzusammensetzung ein Basisöl, das zu Gruppe III und/oder Gruppe II der API-Basisölkategorien gehört, 0,5 bis 5 Masse-% eines 6-Methylheptylalkoholesters von 3-(4-Hydroxy-3,5-di-t-butyl-phenyl)propionsäure und 0,5 bis 5 Masse-% eines Diphenylamins umfasst, bei dem es sich um ein Reaktionsprodukt von N-Phenylbenzolamin und 2,4,4-Trimethylpenten handelt, wobei der Gesamtgehalt der Antioxidationsmittel mindestens 2,5 Masse-% beträgt.
     
    2. Schmiermittelzusammensetzung nach Anspruch 1, wobei der in dem Dieselmotor verwendete Biokraftstoff von Rapsöl abgeleitet ist.
     
    3. Verwendung der Schmiermittelzusammensetzung nach Anspruch 1 oder Anspruch 2 in einem Dieselmotor, und wobei in dem Dieselmotor ein Biokraftstoff verwendet wird, vorzugsweise ein Biokraftstoff, der von Rapsöl abgeleitet ist.
     
    4. Verfahren zum Betreiben eines Dieselmotors, umfassend das Schmieren des Dieselmotors mit einer Schmiermittelzusammensetzung nach einem der Ansprüche 1 bis 2 und Verwenden eines Biokraftstoffs, vorzugsweise von Rapsöl abgeleitet, als Kraftstoff.
     


    Revendications

    1. Composition lubrifiante destinée à être utilisée dans des moteurs diesel compatibles avec un biocarburant, dans laquelle la composition lubrifiante comprend une huile de base appartenant au groupe III et/ou au groupe II des catégories d'huiles de base API, comprenant de 0,5 à 5 % en masse d'un ester d'alcool 6-méthylheptylique de l'acide 3-(4-hydroxy-3,5-di-t-butyl-phényl) propionique et de 0,5 à 5 % en masse d'une diphénylamine qui est un produit de réaction de la N-phénylbenzène-amine et du 2,4,4-triméthylpentène, la teneur totale en antioxydants étant d'au moins 2,5 % en masse.
     
    2. Composition lubrifiante selon la revendication 1, dans laquelle le biocarburant utilisé dans le moteur diesel est dérivé de l'huile de colza.
     
    3. Utilisation de la composition lubrifiante selon la revendication 1 ou la revendication 2 dans un moteur diesel, et dans laquelle un biocarburant est utilisé dans le moteur diesel, de préférence un biocarburant dérivé d'huile de colza.
     
    4. Procédé de fonctionnement d'un moteur diesel comprenant la lubrification du moteur diesel avec une composition lubrifiante selon l'une quelconque des revendications 1 à 2 et l'utilisation d'un biocarburant, de préférence dérivé de l'huile de colza, en tant que carburant.
     






    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description




    Non-patent literature cited in the description