ES2776987T3 - Composition of lubricating oil for diesel engines - Google Patents

Abstract

Composition of lubricating oil for use in diesel engines comprising, in the base oil, not more than 0.3% by mass of sulfated ash, from 0.01 to 0.2% by mass of nitrogen in succinimides, from 0, 05 to 0.12% by mass of zinc in zinc dithiophosphates, 0.02 to 0.3% by mass of nitrogen in amine-based antioxidants, and 0.01 to 0.08% by mass of boron, which It also has a total value of the amount of zinc in zinc dithiophosphate x (amount of nitrogen in succinimide + amount of nitrogen in amine-based antioxidant) as defined above from 0.015 to 0.06, and that it does not contain metallic detergents of salicylate, phenate, or sulfonate, and wherein the boron is derived from boron-modified forms of alkenyl or alkyl succinimides.

Description

DESCRIPTION

Composition of lubricating oil for diesel engines

Technical field of the invention

The present invention relates to a diesel engine lubricating oil composition and, in particular, relates to a diesel engine lubricating oil composition having excellent engine (piston) detergency and low ash content despite the fact that it does not incorporate metallic detergents.

Background of the invention

A diesel particulate filter (hereinafter DPF), which is considered an effective way to clean particulate matter (hereinafter PM) in diesel engine exhaust gases, can be exposed to clogging filter due to metal components in used motor oil. For example, it is known that the ashes from diesel engine oils accumulate in the DPF, and that this leads to a reduction in the cleaning efficiency of the PM and a reduction in the useful life of the DPF, so that it is considered necessary to reduce the sulfated ash in the diesel engine oil, in other words, to reduce the ash content.

This has meant that motor oils, and diesel motor oils in particular, have had a history of change due to changes in fuel. For example, emissions of particulate matter, carbon monoxide and NOx from air pollution due to exhaust gases are now a problem and, in particular, the sulfur content in diesel oils has decreased dramatically in the last ten years or more, from no more than 500 ppm to no more than 10 ppm. Due to these countermeasures in the exhaust gases, an aftertreatment device known as a DPF has been installed in diesel engines. But in order to prevent clogging of DPFs, a need has arisen for low-ash motor oils.

Also, in the case of sulfur content, because sulfuric acid is formed by combustion, because sulfuric acid formed in this way has a deleterious effect on detergency and piston wear, and because it is known that the phosphorus in engine oils poisons exhaust gas purification catalysts, an increasingly strong trend in favor of low ash / low phosphorous / low sulfur engine oils is now conceivable, known as "low SAPS" motor oils.

In this move towards lower ash contents, which has a major effect on the required performance of diesel engine oils noted above, it is necessary to reduce the mixed amounts of metal-containing additives, such as metallic detergents that impart engine detergency and zinc dialkylthiophosphates (ZnDTP), which impart antiwear performance.

In order to prevent clogging of the DPF noted above, a low ash engine oil composition that does not contain metallic additives can be considered, but if the metallic component is simply reduced compared to engine oil compositions of the prior art, the result will be a reduction in important functions, namely, engine detergency, antiwear performance, and oxidative stability of the engine oil composition.

For example, Japanese Patent Laid-Open 2007-254559 (Patent Reference 1) targets a low-ash diesel engine oil composition, but sulfated ash is still considerable, down to 0.6% in mass, and also contains a metallic detergent, so that as long as you use a small amount of metallic detergent, the situation is that the prior art continues even with the goal of a low ash engine oil.

In addition, Japanese Patent Laid-Open 2006-176672 (Patent Reference 2) targets a lubricating oil for internal combustion engines with superior oxidative stability due to a low ash component. It tries to offer higher viscosity and acid number in this low ash oil, but does not particularly focus on piston detergency. Furthermore, the sulfated ash in the examples is extremely large, 0.99 to 1.01% by mass.

The present invention seeks to obtain a lubricating oil composition for use in diesel engines such that excellent engine (piston) detergency is maintained while preventing DPF clogging and reducing valve train wear, even without the inclusion of a metallic detergent.

The present invention, without the inclusion of a metallic detergent, maintains excellent engine piston detergency while preventing DPF plugging and valve train wear by creating a balance between zinc dithiophosphates, succinimides and amine-based antioxidants added to the base oil.

Summary of the invention

According to the present invention, there is provided a lubricating oil composition for use in diesel engines comprising, in the base oil, not more than 0.3% by mass of sulfated ash, from 0.01 to 0.2% by mass of nitrogen in succinimides, from 0.05 to 0.12% by mass of zinc in zinc dithiophosphates, from 0.02 to 0.3% by mass of nitrogen in amine-based antioxidants and from 0.01 to 0.08 Boron mass%, which also has a total value of the amount of zinc in zinc dithiophosphate x (amount of nitrogen in succinimide amount of nitrogen in amine-based antioxidant) as defined above from 0.015 to 0.06, preferably 0.015 to 0.04 and more preferably 0.015 to 0.04, and containing no salicylate, phenate or sulfonate metal detergents, and wherein the boron is derived from boron modified forms of alkenyl or alkyl succinimides.

Detailed description of the invention

What is meant by "containing no metal detergents" herein is a lubricating oil composition in which the metal component derived from metal detergents is not more than 0.01% by mass.

The base oil indicated above is preferably one that is a base oil or a mixture of base oils selected from Group II, Group III, Group IV and Group V and in which the sulfur component of the base oil is not more than 50 ppm.

Furthermore, this lubricating oil composition for use in diesel engines is such that the TGF in the JASO M336: 1998 Detergency Test Procedure is not greater than 30%, and the cam protrusion wear in the Test Procedure JASO M354: 1998 valve train wear is not greater than 95 | jm.

With the present invention, it is possible to obtain a lubricating oil composition for use in diesel engines so that it does not include metallic detergents and has a low amount of ash, while at the same time maintaining excellent engine piston detergency, prevent DPF clogging and reduce valve train wear, thus reducing environmental problems.

For the base oil used in the diesel engine lubricating oil composition of the present invention, it is possible in particular to use as appropriate mineral oils, synthetic oils and mixtures thereof as normally used for lubricating oils. In particular, it is possible to use, individually or as mixtures, oils belonging to the base oil categories of Group II, Group III, Group IV and Group V of the API (American Petroleum Institute).

The Group II base oils listed above include, for example, paraffinic mineral oils obtained by the appropriate use of a suitable combination of refining procedures such as hydrocracking and dewaxing relative to the lubricating oil fractions obtained by atmospheric distillation of crude oil. Group II base oils refined by hydrorefining processes, such as the Gulf Company process, have a total sulfur content of less than 10 ppm and an aromatic content of not more than 5%, and therefore can be used herein. invention.

The viscosity of these base oils is not particularly limited, but the viscosity index should be from 80 to 120 and preferably from 100 to 120. The kinematic viscosity at 40 ° C should preferably be from 2 to 680 mm2 / s and more preferably 8 at 220 mm2 / s. Furthermore, the total sulfur content should be less than 300 ppm, preferably less than 100 ppm, and more preferably less than 10 ppm. The total nitrogen content should also be less than 10 ppm and preferably less than 1 ppm. In addition, oils with an aniline point of 80 to 150 ° C and preferably 100 to 135 ° C should be used.

Group 2 Plus base oils, which have a viscosity index greater than 115, can be specified as a preferred Group 2 base oil.

Group III base oils include, for example, paraffinic mineral oils manufactured by a high degree of hydrorefining relative to lubricating oil fractions obtained by atmospheric distillation of crude oil, isodewaxing refined base oils that dewax and isoparaffin substitutes for the waxes produced by dewaxing procedures, and base oils refined by the Mobil wax isomerization process. These are also suitable for use in the present invention.

The viscosity of these base oils is not particularly limited, but the viscosity index should be 120 to 160 and preferably 120 to 150. The kinematic viscosity at 40 ° C should preferably be 2 to 680 mm2 / s and more preferably 8 at 220 mm2 / s. Furthermore, the total sulfur content should be less than 300 ppm, preferably less than 100 ppm, and more preferably less than 10 ppm. The total nitrogen content should also be less than 10 ppm and preferably less than 1 ppm. In addition, oils with an aniline point of 80 to 150 ° C and preferably 110 to 135 ° C should be used.

Group 3 Plus base oils, which have a viscosity index greater than 130, can be specified as a preferred Group 3 base oil.

As examples of synthetic oils, there may be mentioned polyolefins, alkylbenzenes, alkylnaphthalenes, esters, polyoxyalkylene glycols, polyphenyl ethers, dialkyldiphenyl ethers, fluorine-containing compounds (perfluoropolyethers, fluorinated polyolefins, etc.) and silicones.

The polyolefins listed above include polymers of various olefins or hydrides thereof. Any olefin can be used, and as examples ethylene, propylene, butene and α-olefins with five or more carbons can be mentioned. In the manufacture of polyolefins, one type of the olefins indicated above can be used individually or two or more types can be used in combination. Particularly suitable are polyolefins called poly-aolefins (PAO). These are Group IV base oils.

The viscosity of these synthetic oils is not especially limited, but the kinetic viscosity at 40 ° C should preferably be 2 to 680 mm2 / s and more preferably 8 to 220 mm2 / s.

GTLs (gas to liquid) synthesized by the Fischer-Tropsch process for converting natural gas into liquid fuel have very low sulfur content and aromatic content compared to mineral oil-based oils refined from crude oil and have a very high paraffin constituent ratio, and thus have excellent oxidative stability, and because they also have extremely small evaporation losses, they are suitable as base oils for the present invention.

The viscosity characteristics of GTL base oils are not especially limited, but normally the viscosity index should be 120 to 180, preferably 130 to 175 and more preferably 140 to 175. In addition, the kinematic viscosity at 40 ° C should be from 2 to 680 mm2 / s and preferably from 5 to 120 mm2 / s. Typically, the total sulfur content is also less than 10 ppm and the total nitrogen content is less than 1 ppm. A commercial example of such a GTL base oil is Shell XHVI (registered trademark).

The base oils specified above can be used alone or as mixtures, and their sulfur content should be less than 50 ppm, preferably less than 10 ppm, and more preferably less than 1 ppm.

As examples of the zinc dithiophosphates mentioned above, zinc dialkyl dithiophosphates, zinc diaryl dithiophosphates and zinc arylalkyl dithiophosphates may be mentioned in general. For example, zinc dialkyl dithiophosphates can be used in which the alkyl groups of zinc dialkyl dithiophosphates have primary or secondary alkyl groups of 3 to 22 carbons or alkylaryl groups substituted with alkyl groups of 3 to 18 carbons. For example, zinc dialkyl dithiophosphates in which the alkyl groups of zinc dialkyl dithiophosphates have primary or secondary alkyl groups of 3 to 12 carbons or zinc diaryl dithiophosphates in which the aryl groups are phenyl or alkylaryl groups substituted with groups alkyl of 1 to 18 carbons.

Zinc dithiophosphates with secondary alkyl groups having 3 to 12 carbon atoms, preferably 3 to 8 carbon atoms, and more preferably 3 to 6 atoms are preferred.

As specific examples of zinc dialkyl dithiophosphates, zinc dipropyl dithiophosphate, zinc dibutyl dithiophosphate, zinc dipentyl dithiophosphate, zinc dihexyl dithiophosphate, zinc diisopentyl dithiophosphate, zinc diethylhexyl dithiophosphity , zinc didecyl dithiophosphate, zinc didodecyl dithiophosphate, zinc dipropylphenyl dithiophosphate, zinc dipentylphenyl dithiophosphate, zinc dipropylphenyl dithiophosphate, zinc dinonylphenyl dithiophosphate and zinc didodecylphenyl dithiophosphate.

These zinc dithiophosphates are incorporated such that the amount of zinc is 0.05 to 0.12% by mass, but preferably 0.06 to 0.12% by mass, of the lubricating oil composition. Zinc dithiophosphates are, as noted above, effective antiwear additives, but contain phosphorus (P). Phosphorous compounds are said to poison exhaust gas catalysts and if the phosphorus content in the composition increases, there is a greater possibility of a deleterious effect on the exhaust gas cleaning catalyst. For this reason, if the zinc dithiophosphate is incorporated such that the amount of zinc exceeds 0.12% by mass, there will be a concomitant increase in the amount of phosphorus in the composition, which is undesirable. Furthermore, if the upper limit indicated above is exceeded, the antiwear additive effect will be saturated, so that an effect corresponding to the expense will not be obtained and this will not be efficient. On the other hand, if the amount is less than 0.05% by mass, the result in terms of anti-wear additive may not be effective.

In the lubricating oil composition of the present invention, an alkenyl succinimide or an alkyl succinimide and / or a boron modified derivative thereof is used for the succinimide listed above. It has the function of being an ashless dispersant.

As suitable examples of an alkenyl or an alkyl succinimide may be mentioned the alkenyl monoimides or succinic alkyl represented by the general Formula (1) and the alkenyl or succinic alkyl bisimides represented by the general Formula (2).

In the General Formula (1) and General Formula (2) indicated above, each of R1, R3 and R4 indicates an alkenyl group or an alkyl group with a weight average molecular weight of 500 to 3,000, and R3 and R4 They can be the same or different. Each of R2, R5 and R6 indicates an alkylene group having 2 to 5 carbons, and R5 and R6 may be the same or different. m is an integer from 1 to 10 and n is 0 or an integer from 1 to 10.

The weight average molecular weight of each of R1, R3 and R4 in General Formulas (1) and (2) is, as indicated above, 500 to 3,000, but preferably 1,000 to 3,000. If the weight average molecular weight is less than 500, the solubility in the base oil will be reduced, and if it exceeds 3,000, the detergency will be reduced, so there will be a risk that the target functions are not achieved.

Furthermore, m indicated above is an integer from 1 to 10, but preferably 2 to 5, and more preferably 3 to 4. If m exceeds 2, there will be good detergency. If m is less than 5, the solubility in the base oil will be good.

In the general Formula (2), n is 0 or an integer from 1 to 10, but preferably 1 to 4 and more preferably 2 to 3. If n exceeds 1, there will be good detergency, and if n is less the solubility in the base oil it will be good.

As examples of the alkenyl groups in the general Formulas (1) and (2), mention may be made of polybutenyl groups, polyisobutenyl groups and ethylene-propylene copolymers. Alkyl groups include hydrogenated forms thereof. As typical examples of suitable alkenyl groups, polybutenyl groups and polyisobutenyl groups can be mentioned. These polybutenyl groups are obtained by polymerizing mixtures of 1-butene and highly refined isobutene or isobutene.

Furthermore, hydrogenated forms of polybutenyl groups or polyisobutenyl groups are typical examples of suitable alkyl groups.

The alkenyl or alkyl succinimides listed above can usually be prepared by reacting with a polyamine an anhydrous alkenyl succinimide obtained by a reaction between a polyolefin and maleic anhydride, or an anhydrous alkyl succinimide obtained by hydrogenation thereof.

The succinic monoimides and bisimides listed above can be prepared by varying the reaction rates of the anhydrous alkenyl succinic acids or anhydrous alkyl succinic acids and polyamines.

For the olefin monomer that forms the above-noted polyolefin, it is possible to use mixtures of one or two or more types of α-olefins having 2 to 8 carbons, and it is possible to use satisfactorily mixtures of isobutene and butene-1.

As examples of the polyamines listed above, unit diamines such as ethylene diamine, propylene diamine, butylene diamine, and pentylene diamine, and polyalkylene polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, di (methylethylene) triamine, dibutylene triamine, tributylene tetramine, and pentapentylene hexamine.

Furthermore, for boron modified derivatives of alkenyl or alkyl succinimides, it is possible to use the preparations by the usual procedures. For example, they can be obtained after converting the indicated polyolefins into anhydrous alkenyl succinimides by reacting them with maleic acid, by further imidification by reacting them with an intermediate product obtained by reacting the polyamines indicated above and a boron compound such as boron oxide, a halide boron, a boric acid, a boric anhydride, a boric ester or an ammonium salt of a boric acid.

The lubricating oil composition of the present invention contains, in composition terms, from 0.01 to 0.2% by mass, calculated in terms of nitrogen content, of an alkenyl or alkyl succinic monoimide or bisimide and / or a boron modified derivative thereof as an ashless dispersant, but preferably contains 0.05 to 0.15% by mass.

If the content of the alkenyl or alkyl succinic monoimide or bisimide and / or boron modified derivative thereof is less than 0.01% by mass, the effect as an ashless dispersant will not be satisfactorily displayed, and if it exceeds 0.2 % by mass, a detrimental influence on rubber parts, such as elastomers, used in engines can be observed.

Furthermore, the content of a boron modified derivative of an alkenyl or alkyl succinic monoimide in said ashless dispersant will be, calculated in terms of boron, from 0.01 to 0.08% by mass and preferably from 0.04 to 0, 07% by mass.

Even if the boron-converted content of the alkenyl or alkyl succinic monoimide and / or the boron-modified derivative thereof in the ashless dispersant is less than 0.01% by mass, the effect of antiwear and detergency performance to High temperature is not enough and if it exceeds 0.08% by mass, the effective performance will saturate and the economic efficiency will decrease.

Furthermore, boron is derived from boron-modified forms of succinimides, and for the amount of succinimide added to be within the range indicated above, it is often undesirable for the boron component to be added in excess, since excess Boron component can cause DPF clogging by increasing the sulfated ash derived from the greater amount of boron in the formulation.

For the amine-based antioxidants used in the present invention, those generally used for lubricating oils are preferred for practical use, and it is possible to use the same alone or in multiple combinations in the lubricating oil composition within the range of 0.02 to 0.3% by mass in terms of nitrogen content.

Amine-based antioxidants are structurally prone to surface adsorption, and because zinc dithiophosphate, the antiwear agent, breaks down and acid intermediates adsorb on the surface, again an excess amount added is not desirable. , so it is better to control the upper limit.

As examples of the amine-based antioxidants listed above, mention may be made of dialkyldiphenylamines such as p, p'-dioctyldiphenylamine (Nonflex OD-3, manufactured by Seiko Chemical Ltd), p, p'-di-methylbenzyldiphenylamine and Np-butylphenyl-N -p'-octylphenylamine, monoalkyldiphenylamines such as mono-t-butyldiphenylamine and monooctyldiphenylamine, bis (dialkylphenyl) amines such as di (2,4-diethylphenyl) amine and di (2-ethyl-4-nonylphenyl) amine, alkylphenyl-1- naphthylamines such as octylphenyl-1-naphthylamine and Nt-dodecylphenyl-1-naphthylamine, 1-naphthylamine, arylnaphthylamines such as phenyl-1-naphthylamine, phenyl-2-naphthylamine, N-hexylphenyl-2-naphthylamine and N-octylphenyl-2- naphthylamine, phenylenediamines such as N, N'-diisopropyl-p-phenylenediamine and N, N'-diphenyl-p-phenylenediamine, and phenothiazines such as Phenothiazine (manufactured by Hodogaya Chemical Ltd.) and 3,7-dioctylphenothiazine.

In addition to the amine-based antioxidants used in the present invention, it is possible to use phenolic antioxidants. In the examples below, phenolic antioxidants and amine-based antioxidants are used in combination. These antioxidants can be used individually or in multiple combinations within the range of 0.01 to 5% by mass in the lubricating oil composition.

The combination of the amine-based antioxidants and the phenolic antioxidants used in the Examples is shown in Table 1.

As examples of sulfur-based antioxidants, mention may be made of dialkyl sulfides such as didodecyl sulfide, thiodipropionate esters such as dioctadecyl thiodipropionate, dimyristyl thiodipropionate, and dodecyloctadecyl thiodipropionate, and 2-mercaptobenzoimidazoimidazole.

Phenolic antioxidants include 2-t-butylphenol, 2-t-butyl-4-methylphenol, 2-t-butyl-5-methylphenol, 2,4-di-t-butylphenol, 2,4-dimethyl6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,5-di-t-butylhydroquinone (Antage DBH, manufactured by Kawaguchi Chemical Industry Co. Ltd), 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-alkylphenols such as 2,6-di-t-butyl-4-methylphenol and 2,6-di-t- butyl-4-ethylphenol and 2,6-di-t-butyl-4-alkoxyphenols such as 2,6-di-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-ethoxyphenol.

In addition, there are 3,5-di-t-butyl-4-hydroxybenzylmercapto-octylacetate, alkyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionates such as n-octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate (Yoshinox SS, manufactured by Yoshitomi Fine Chemicals Ltd), ndodecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and 2'- ester ethylhexyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3,5-bis (1,1-dimethyl-ethyl) -4-hydroxy-C ⁷ -C ⁹ side chain alkyl Benzenepropanoic acid (Irganox L135, manufactured by Ciba Specialty Chemicals Ltd), 2,6-di-t-butyl-α-dimethylamino-p-cresol and 2,2'-methylenebis (4-alkyl-6-t-butylphenols) such such as 2,2'-methylenebis (4-methyl-6-t-butylphenol) (Antage W-400, manufactured by Kawaguchi Chemical Industry Ltd.) and 2,2'-methylenebis (4-ethyl-6-t-butylphenol) (Antage W-500, manufactured by Kawaguchi Chemical Industry Ltd).

In addition, there are bisphenols such as 4,4'-butylidenebis (3-methyl-6-t-butylphenol) (Antage W-300, manufactured by Kawaguchi Chemical Industry Ltd.), 4,4'-methylenebis (2,6- di-t-butylphenol) (lonox 220AH, manufactured by Shell Japan Ltd.), 4,4'-bis (2,6-di-t-butylphenol), 2,2- (di-p-hydroxyphenyl) propane (bisphenol A, manufactured by Shell Japan Ltd.), 2,2-bis (3,5-di-t-butyl-4-hydroxyphenyl) propane, 4,4'-cyclohexylidenebis (2,6-t-butylphenol), hexamethylene glycol bis [ 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (Irganox L109, manufactured by Ciba Specialty Chemicals Ltd.), triethylene glycol bis [3- (3-t-butyl-4-hydroxy -5 -methylphenyl) propionate] (Tominox 917, manufactured by Yoshitomi Fine Chemicals Ltd.), 2,2'-thio- [diethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (Irganox L115, manufactured by Ciba Specialty Chemicals Ltd.), 3,9-bis {1,1-dimethyl-2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl} 2,4,8 , 10-tetraoxaspiro [5.5] undecane (Sumilizer GA80, manufactured by Sumitomo Chemicals), 4,4'-thiobis (3-methyl-6-t-bu Tylphenol) (Antage RC, manufactured by Kawaguchi Chemical Industry Ltd.) and 2,2'-thiobis (4,6-di-t-butyl-resorcinol).

Polyphenols such as tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (Irganox L101, manufactured by Ciba Specialty Chemicals Ltd.), 1,1,3- tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane (Yoshinox 930, manufactured by Yoshitomi Fine Chemicals Ltd.), 1,3,5-trimethyl-2,4,6-tris (3,5- di-t-butyl-4-hydroxybenzyl) benzene (Ionox 330, manufactured by Shell Japan Ltd.), bis- [3,3'-bis- (4'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester , 2- (3 ', 5'-di-t-butyl-4-hydroxyphenyl) methyl-4- (2 ", 4" -di-t-butyl-3 "-hydroxyphenyl) methyl-6-t-butylphenol and 2,6, -bis (2'-hydroxy-3'-t-butyl-5'-methyl-benzyl) -4-methylphenol, and phenol-aldehyde condensates such as pt-butylphenol and formaldehyde condensates and pt condensates -butylphenol and acetaldehyde.

In addition to the constituents indicated above, when applications or performance require it, it is also possible to use as metal deactivators, corrosion inhibitors, viscosity index improvers, pour point depressants, antifoaming agents and other additives in the composition of diesel engine lubricating oil of the present invention.

Metal deactivators that can be used in conjunction with the diesel engine lubricating oil composition of the present invention include benzotriazole and benzotriazole derivatives which are 4-alkyl-benzotriazoles such as 4-methyl-benzotriazole and 4-ethyl-benzotriazole, 5- alkyl-benzotriazoles such as 5-methyl-benzotriazole and 5-ethyl-benzotriazole, 1-alkyl-benzotriazoles such as 1-dioctylaminomethyl-2,3-benzotriazole and 1-alkyl-tolutriazoles such as 1-dioctylaminomethyl-2,3-tolutriazole and benzoimidazole and benzoimidazole derivatives which are 2- (alkyldithio) -benzoimidazoles such as 2- (octyldithio) -benzoimidazole, 2- (decyldithio) -benzoimidazole and 2- (dodecyldithio) -benzoimidazole and 2- (alkyldithio) toluimidazoles such as 2 - (octyldithio) -toluimidazole, 2- (decyldithio) -toluimidazole and 2- (dodecyldithio) toluimidazole.

Mention may also be made of indazole, indazole derivatives that are toluindazoles, such as 4-alkyl-indazoles and 5-alkyl-indazoles, benzothiazole, and benzothiazole derivatives that are 2-mercaptobenzothiazole derivatives (Thiolite B-3100, manufactured by Chiyoda Chemical Industries Ltd.), 2- (alkyldithio) benzothiazoles such as 2- (hexyldithio) benzothiazole and 2- (octyldithio) benzothiazole, 2- (alkyldithio) tolutiazoles such as 2- (hexyldithio) tolutiazole and 2- (octyldithio) tolutiazole, 2 - (N, N-dialkyldithiocarbamyl) -benzothiazoles such as 2- (N, N-diethyldithiocarbamyl) -benzothiazole, 2- (N, N-dibutyldithiocarbamyl) -benzothiazole and 2- (N, N-dihexyldithiocarbamyl) -benzothiazole, and 2 - (N, N-dialkyldithiocarbamyl) -tolutiazoles such as 2- (N, N-diethyldithiocarbamil) -tolutiazole, 2- (N, N-dibutyldithiocarbamil) -tolutiazole and 2- (N, N-dihexyldithiocarbamil) -tolutiazole.

Furthermore, benzooxazole derivatives which are 2- (alkyldithio) benzooxazoles such as 2- (octyldithio) benzooxazole, 2- (decyldithio) benzooxazole and 2- (dodecyldithio) benzooxazole or which are 2- (alkyldithio) toluoxazoles such as 2 - (octyldithio) toluoxazole, 2- (decyldithio) toluoxazole and 2- (dodecyldithio) toluoxazole, thiadiazole derivatives that are 2,5-bis (alkyldithio) -1,3,4-thiadiazoles such as 2,5-bis (heptyldithio ) -1,3,4-thiadiazole, 2,5-bis (nonyldithio) -1,3,4-thiadiazole, 2,5-bis (dodecyldithium) -1,3,4-thiadiazole and 2,5-bis ( octadecyldithio) -1,3,4-thiadiazole, 2,5-bis (N, N-dialkyldithiocarbamil) -1,3,4-thiadiazoles such as 2,5-bis (N, N-diethyldithiocarbamil) -1,3, 4-thiadiazole, 2,5-bis (N, N-dibutyldithiocarbamyl) -1,3,4-thiadiazole and 2,5-bis (N, N-dioctyldithiocarbamyl) -1,3,4-thiadiazole and 2-N, N-dialkyldithiocarbamil-5-mercapto-1,3,4-thiadiazoles such as 2-N, N-dibutyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole and 2-N, N-dioctyldithiocarbamyl-5-mercapto-1 , 3,4-thiadiazole, and triazole derivatives which are, for example, 1-alkyl-2,4-triazoles such as 1-di-octylaminomethyl-2,4-triazole.

These metal deactivators can be used alone or in multiple combinations within the range of 0.01 to 0.5%. by mass in the lubricating oil composition.

As examples of the corrosion inhibitors listed above, mention may be made of fatty acids, alkenylsuccinic half esters, soaps of fatty acids, salts of alkylsulfonic acid, sulfonates and naphthenates of alkaline earth metals (calcium (Ca), magnesium (Mg), barium (Ba), etc.), fatty acid esters of polyhydric alcohol, amines of fatty acids, paraffin oxide and alkylpolyoxyethylene ethers, and normally the amount thereof in the mixture will be within the range of 0.01 to 5% by mass based to the total amount of the composition.

In order to improve flow characteristics and low temperature viscosity characteristics, pour point depressants and viscosity index improvers may also be added to the lubricating oil composition of the present invention.

As examples of viscosity index improvers, non-dispersant type viscosity index improvers, such as polymethacrylates, as well as ethylene-propylene copolymers, styrene-butadiene copolymers, such as styrene-butadiene or olefin polymers such as polyisobutylene can be mentioned. and polystyrene, and dispersant-type viscosity index improvers in which the nitrogen-containing monomers have been copolymerized therewith. As for the amount to be added, they can be used within the range of 0.05 to 20% by mass of the lubricating oil composition.

As examples of pour point depressants, polymethacrylate-based polymers can be mentioned. As for the amount to be added, they can be used within the range of 0.01 to 5% by mass of the lubricating oil composition. A polymethacrylate based pour point depressant was incorporated into the examples of the present invention.

Antifoam agents may also be added in order to impart antifoam characteristics to the lubricating oil composition of the present invention. As examples of preferred antifoaming agents, organosilicates such as polydimethylsiloxane, diethylsilicate and fluorosilicone, and non-silicone antifoaming agents such as polyalkylacrylates can be mentioned. As for the amount to be added, they can be used individually or in multiple combinations within the range of 0.0001 to 0.1% by mass in the lubricating oil composition.

In the following, additional explanations are provided by the provision of examples and comparative examples, but the invention is not limited thereto.

In preparing the examples and comparative examples, the following compositions and materials were used.

1. Base oils

(1-1) Base oil A: Base oil derived from Fischer-Tropsch (XHVI 5.2) [Characteristics: kinematic viscosity at 100 ° C, 5.2 mm2 / s; viscosity index, 140; sulfur content, not greater than 10 ppm by mass]

(1-2) Base oil B: Base oil derived from Fischer-Tropsch (XHVI 8.2) [Characteristics: kinematic viscosity at 100 ° C, 8.2 mm2 / s; viscosity index, 144; sulfur content, not greater than 10 ppm by mass]

(1-3) Base oil C: Ethylene α-olefin co-oligomer (Lucant HC40) [Characteristics: kinematic viscosity at 100 ° C, 40 mm2 / s; viscosity index, 155; sulfur content, not greater than 10 ppm by mass]

2. Zinc dithiophosphates

(2-1) ZnDTP-1: Zinc dialkyldithiophosphate having secondary alkyl groups with 3-6 carbons [Constituents (values for elemental analysis): Zn 11.1% by mass, P 10.0% by mass, S 21 % by mass] (2-2) ZnDTP-2: Zinc dialkyldithiophosphate having secondary alkyl groups with 4-6 carbons [Constituents (values for elemental analysis): Zn 7.7% by mass, P 7.2% by mass, S 15% by mass] 3. Ashless dispersants

(3-1) Succinimide-1: Borated polybutenyl succinimide (mono) [Constituents (values for elemental analysis): N 2.2% by mass, B 1.96% by mass]

(3-2) Succinimide-2: Polybutenyl succinimide (bis) [Constituents (values for elemental analysis): N 1.2% by mass]

(3-3) Succinimide-3: Borated polybutenyl succinimide (bis) [Constituents (values for elemental analysis): N 1.5% by mass, B 0.47% by mass]

4. Antioxidants

(4-1) Antioxidant-1: Amine-based antioxidant (Irganox L57) [Components: nitrogen content 4.5% by mass]

(4-2) Antioxidant-2: hindered phenol-based antioxidant (Irganox L135)

5. Metal deactivator: Benzotriazole derivative (Irgamet 39)

6. Viscosity index improver: styrene-butadiene based viscosity index improver

7. Pour point depressant: Pour point depressant based on polymethacrylate

8. Defoaming agent: Defoaming agent based on polydimethylsiloxane

Examples and comparative examples

The component materials were mixed in the proportions shown in Tables 1 and 2, and lubricating oil compositions were obtained for use in diesel engine oils. The proportions shown in Tables 1 and 2 are% by mass unless otherwise specified.

essays

The following tests were carried out on Examples 1 to 4 and Comparative Examples 1 to 6 in order to compare their characteristics.

(1) Calculation of parameters

Total value of [(amount of zinc in zinc dialkyldithiophosphate) x (amount of nitrogen in polybutenyl succinimide)] and [(amount of zinc in zinc dialkyldithiophosphate) x (amount of nitrogen in amine-based antioxidant)]

The amount of zinc and nitrogen described herein is expressed by mass%.

Evaluation criteria:

0.015 or more Acceptable

Below 0.015 Unacceptable

If this value is less than 0.015, the TGF will exceed 30% or the amount of cam boss wear will exceed 95 µm, which is undesirable. If it is between 0.015 and 0.06, both the TGF and the amount of cam boss wear will be small, which means that desirable results can be achieved. If the value is greater than 0.06, it is not favorable in terms of economic efficiency.

(2) Detergency test based on TGF value (TGF value measured after Nissan TD25 engine test) A test was performed to evaluate piston detergency based on the engine test procedure according to JASO M336: 1998, which is a diesel engine piston detergency test also adopted for JASO M355 (Automotive Diesel Engine Oil Standard).

Evaluation criteria:

30% or less Acceptable

More than 30% Unacceptable

(3) Valve train wear tests

The valve train wear tests were carried out according to JASO M354: 1999 (using a Mitsubishi 4D34T4 heat engine).

Evaluation criteria:

Cam boss wear 95 jm or less Acceptable

More than 9530% Unacceptable

The cam boss wear value limit is based on the JASO DH-2 approval criteria. In the case of cam boss wear values used herein, they were carried out investigations using actual measured values themselves and no conversions of any kind were performed.

Test results

The test results for Examples 1 to 4 and Comparative Examples 1 to 6 are provided in Tables 1 and 2.

Discussion

Example 1 did not contain any metallic detergent. The succinimide-3 ashless dispersant provided 0.15 mass% nitrogen, the amine-based antioxidant provided 0.08 mass% nitrogen, and the succinimide-based dispersant provided boron. of 0.047% by mass, while ZnDTP provided an amount of Zn of 0.10% by mass, so that the parameter for the amount of zinc x (amount of nitrogen in succinimide amount of nitrogen in amine-based antioxidant) had a value of 0.023, and the TGF was 12% and the cam boss wear was 7 pm. Furthermore, the sulphated ash was 0.23% by mass, meeting the criteria, so that a satisfactory yield was obtained.

Example 2 did not use a metallic detergent. The main points were that the total amount of nitrogen in the mixture of succinimide-1, succinimide-2 and succinmimide-3 provided a total amount of nitrogen of 0.12% by mass, and the value of the parameter was therefore 0.020 . The TGF was 12%, and the cam boss wear was 18 pm, which meant that satisfactory performance had been achieved.

In the case of Example 3, the amount of nitrogen of the succinimides was 0.15% by mass, and it was a mixture of succinimide-1 and succinimide-2. The amount of Zn was 0.1% by mass, and the amine-based antioxidant provided an amount of nitrogen of 0.0396% by mass, which meant that the parameter value was 0.019. The TGF value was 9% and the wear of the cam boss was 24.7 pm.

When the amount of amine-based antioxidant nitrogen was 0.022% by mass, such as in Example 4, the parameter value was 0.015, the TGF was 7%, and the cam boss wear was 84.9 pm, but this was within the satisfactory performance range.

On the other hand, in the case of Comparative Example 1, the succinimide-based dispersant provided a nitrogen amount of 0.075% by mass. Furthermore, the amount of Zn was 0.077% by mass, and no amine-based antioxidant was added, so that the parameter value was greatly reduced by 0.006, the TGF value was 47%, and there was a substantial increase in the wear of cam boss. In Comparative Example 2, the amount of nitrogen from the succinimide-based dispersant was 0.12% by mass, and the amount of nitrogen from the amine-based antioxidant was 0.08% by mass, while the amount of Zn was 0.05% by mass. This meant that the parameter value was outside the range of 0.010, and the TGF was 39%, but the cam boss wear exceeded 95 pm to 217 pm.

Comparative Example 3 provided an amount of Zn of 0.05% by mass, an amount of nitrogen in succinimide of 0.10% by mass, an amount of nitrogen in amine-based antioxidant of 0.0792% by mass, and a value parameter of 0.009, which was out of range. The TGF value was 55 and the valve train wear deteriorated further at 300 pm. In the case of Comparative Example 4, when the amount of Zn was 0.06% by mass, the amount of nitrogen in succinimide was 0.15% by mass, and the amount of amine-based antioxidant nitrogen was 0, 0396% by mass, the parameter value was 0.011, the TGF was 14%, and the cam boss wear exceeded 95 pm to 130.7 pm.

In Comparative Example 5, when the amount of Zn was 0.07% by mass and the amount of nitrogen in succinimide was 0.12% by mass, the parameter value was 0.011, and the TGF was satisfactory at 24 %, but wear on the cam boss increased substantially to provide 235.6 pm. In Comparative Example 6, the amount of succinimide-3 was made the same as in Example 1, and the amount of Zn was 0.07% by mass, while the amount of nitrogen in amine-based antioxidant was 0, 0396% by mass, which meant the parameter value was 0.013, the TGF was 11% and the cam boss wear was 99 pm, slightly exceeding the camshaft wear limit of 95 pm.

Table 1

Table 2

Claims (4)

1. Composition of lubricating oil for use in diesel engines comprising, in the base oil, not more than 0.3% by mass of sulfated ash, from 0.01 to 0.2% by mass of nitrogen in succinimides, from 0.05 to 0.12% by mass of zinc in zinc dithiophosphates, 0.02 to 0.3% by mass of nitrogen in amine-based antioxidants, and 0.01 to 0.08% by mass of boron , which also has a total value of the amount of zinc in zinc dithiophosphate x (amount of nitrogen in succinimide amount of nitrogen in amine-based antioxidant) as defined above from 0.015 to 0.06, and that does not contain metallic detergents of salicylate, phenate or sulfonate, and wherein the boron is derived from boron modified forms of alkenyl or alkyl succinimides. 2. Lubricating oil composition for use in diesel engines according to claim 1, wherein the oil indicated above is a single base oil or a mixture selected from Group II, Group III, Group IV and Group V, and in where the sulfur component of the base oil is not greater than 50 ppm. 3. Lubricating oil composition for use in diesel engines according to claim 1 or claim 2, so that the TGF in the JASO M336: 1998 detergency test procedure is not greater than 30% and the wear test procedure of the JASO M354: 1999 valve train is not greater than 95 pm. Lubricating oil composition for use in diesel engines according to claim 1, claim 2 or claim 3, in which the above oil contains secondary zinc alkyl dithiophosphates, in which the alkyl groups have from 3 to 12 carbon atoms.