WO2008050717A1

WO2008050717A1 - Lubricating oil composition for internal combustion engine

Info

Publication number: WO2008050717A1
Application number: PCT/JP2007/070547
Authority: WO
Inventors: Koki Ito
Original assignee: Idemitsu Kosan Co., Ltd.
Priority date: 2006-10-23
Filing date: 2007-10-22
Publication date: 2008-05-02
Also published as: JP5175739B2; US20100009882A1; EP2077319A1; EP2077319A4; JPWO2008050717A1

Abstract

Disclosed is a lubricating oil composition for an internal combustion engine, which comprises: a base oil; (A) at least one member selected from a disulfide compound represented by the general formula (I): R1OOC-A1-S-S-A2-COOR2 (I) and a disulfide compound represented by the general formula (II): R7OOC-CR9R10-CR11(COOR8)-S-S-CR16(COOR13)-CR14R15-COOR12 (II) ; and (B) at least one member selected from an alkali metal-containing detergent and an alkali earth metal-containing detergent in an amount of 10 to 2000 ppm by mass in terms of metal content. The lubricating oil composition can maintain abrasion resistance, has excellent heat resistance, can prolong the time interval for the lubricating oil renewal and has a long service life, in spite of its low ash content, low phosphorous content and low sulfur content.

Description

Specification

Lubricating oil composition for internal combustion engines

Technical field

[0001] The present invention relates to a lubricating oil composition for an internal combustion engine, in particular, a lubricating oil composition suitable for an internal combustion engine such as a gasoline engine, a diesel engine, or a gas engine. The present invention relates to a long-life lubricating oil composition that maintains wear resistance while having low phosphorus content and low sulfur content, is excellent in heat resistance, and can extend the renewal interval of the lubricating oil.

Background art

[0002] Lubricating oil for internal combustion engines is mainly used for lubrication of various sliding parts such as piston rings, cylinder liners, crankshafts, connecting rod shafts, cams, and valve mechanisms including valve lifters. It has functions such as cooling, dispersion of sludge and unburned fuel.

As described above, the lubricating oil for internal combustion engines is required to have various performances, and in addition, in recent years, advanced performance has been demanded as internal combustion engines have become higher performance, higher output, and severer operating conditions. It is coming. Therefore, in order to satisfy such required performance, various additives such as an antiwear agent, a metal detergent, an ashless dispersant, and an antioxidant are blended in the lubricating oil for internal combustion engines.

In addition, as part of extending the life of lubricating oils, development of more effective antioxidants and combination techniques have been studied, and among them, dialkyldithiophosphoric acid has been conventionally used as an extreme pressure additive. Zinc (ZnDTP) has been heavily used. This ZnDTP not only has an antioxidant action, but also has a great effect on wear prevention, and also has a corrosion prevention action, and has been widely used especially in engine oils.

However, in recent years, regulations on automobile exhaust gas have been tightened, and exhaust gas purification devices have been installed in gasoline engines. In order to prevent poisoning of this three-way catalyst, gasoline is lead-free and engine oil is low in phosphorus. As a result, the use of ZnDTP began to be restricted. Therefore, the development of extreme pressure antiwear agents that do not contain phosphorus has become essential. [0004] In diesel engines, particulate matter (particulate matter) contained in the combustion gas discharged from diesel vehicles is also a problem, and diesel particulate removal devices (diesel 'particulate' filters) are used in diesel vehicles. , Hereinafter abbreviated as “DPF”). When ZnDTP is used as an extreme pressure additive as described above, there is a risk of clogging of the filter due to the deposition of zinc components contained in ZnDTP on DPF, and the development of alternatives to ZnDTP is desired.

It is also desirable to reduce the phosphorus component contained in ZnDTP from the viewpoint of catalyst poisoning.

[0005] Patent Document 1 discloses a lubricating oil composition containing a thiophosphate, a metal salt of phosphate, or an amine salt, having a reduced sulfur content and excellent base number retention. Sulfur content can be reduced as a substitute for ZnDTP S, phosphorus component, zinc component (ash content) cannot be reduced, and catalyst poisoning and DPF clogging problems remain and are still insufficient as a lubricating oil composition .

As described above, it is difficult to reduce the zinc component, phosphorus component and sulfur component without reducing wear resistance and antioxidant performance as an extreme pressure additive, but it is difficult to reduce the amount of exhaust gas treatment equipment, DPF and other automobiles. These reductions are desired in order to minimize the impact on the post-processing process.

[0006] Conventionally, it is well known that a synergistic effect can be obtained by combining a sulfur-based antioxidant and a phenol-based antioxidant. However, as the sulfur-based antioxidant, those having a monosulfide structure are mainly used, and an increase in acid value due to hydrolysis has been a problem. In addition, sulfur compounds having a polysulfide structure higher than trisulfide have a problem of high corrosiveness to non-ferrous metals.

[0007] Patent Document 1: 2002-924721

Disclosure of the invention

Problems to be solved by the invention

[0008] Under such circumstances, the present invention maintains wear resistance and has excellent heat resistance while having a low ash content, a low phosphorus content, and a low sulfur content. It is an object of the present invention to provide a lubricating oil composition for an internal combustion engine that can extend the interval. Means for solving the problem

As a result of earnest research to develop a lubricating oil composition for an internal combustion engine having the above-mentioned preferable properties, the present inventor has used the above-mentioned by combining a disulfide compound having a specific structure and a specific amount of detergent. We have found that the objective can be achieved. The present invention has been completed based on such knowledge.

That is, the present invention

(1) Base oil and (A) —general formula (I)

R'OOC-A ¹ -S-S-A ² -COOR ² … (I)

(Wherein R ¹ and R ² are each independently an oxygen atom, a sulfur atom, or a nitrogen atom and a hydrocarbyl group having 1 to 30 carbon atoms, A ¹ and A ² are each independently CR ³ R ⁴ or CR ³ R ⁴ —CR ⁵ R ⁶ , wherein R ^{3 to} R ⁶ each independently represents a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. Disulfide compounds and general formula (Π)

R ⁷ OOC CR ⁹ R ¹⁰ — CR ^U (COOR ⁸ ) S— S— CR ¹⁶ (COOR ¹³ ) CR ¹⁴ R ¹⁵ CO OR ¹² (II)

(Wherein R ⁷ , R ⁸ , R ¹² and R ¹³ are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain an oxygen atom, a sulfur atom or a nitrogen atom, R ^{9 to} R ^U and R ^{14 to} R ¹⁶ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 5 carbon atoms.) And at least one selected from disulfide compounds represented by (B ) A lubricating oil composition for internal combustion engines, comprising 10 to 2000 mass ppm as a metal amount of at least one selected from alkali metal or alkaline earth metal detergents,

(2) The lubricating oil composition for internal combustion engines according to (1) above, which contains 0.01 to 0.50 mass% as a sulfur amount of at least one selected from the disulfide compounds of component (A),

(3) The lubricating oil composition for internal combustion engines according to (1) or (2) above, wherein the alkali metal or alkaline earth metal detergent of component (B) comprises salicylate or sulfonate, and

(4) (1) to (3) V above, wherein the metal of component (B) is Ca or Mg, any one of the lubricating oil compositions for internal combustion engines,

Is to provide. The invention's effect

[0010] According to the present invention, a long-life internal combustion engine that has a low ash content, a low phosphorus content, and a low sulfur content, is excellent in wear resistance and heat resistance, and can extend the interval between lubricating oils. A lubricating oil composition for an engine can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

[0011] Mineral oil and synthetic oil can be used as the base oil in the lubricating oil composition for internal combustion engines of the present invention (hereinafter sometimes abbreviated as "lubricating oil composition"). There are various mineral oils and synthetic oils, and they may be appropriately selected according to the application. Examples of mineral oils include paraffinic mineral oils, naphthenic mineral oils, intermediate-based mineral oils, and specific examples include light neutral oils, medium neutral oils, heavy neutral oils, bright oils by solvent refining or hydrorefining. Stocks can be listed.

On the other hand, synthetic oils include, for example, poly α-olefin, α-olefin copolymer, polybutene, alkylbenzene, polyol ester, dibasic acid ester, polyhydric alcohol esterol, polyoxyalkylene glycolol, polyoxyanol. Cylene glycol ester, polyoxyalkylene glycol ether, cycloalkane compounds, etc.

These lubricating base oils can be used alone or in combination of two or more kinds, and mineral oil and synthetic oil may be used in combination.

[0012] The compound represented by the general formula (I), which is the component (ii) used in the lubricating oil of the present invention, has the following structure:

R ^ OOC— Α ¹ — S— S— Α ² — COOR ² … (I)

It is a disulfide compound having

In the general formula (I), R ¹ and R ² are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain an oxygen atom, a sulfur atom, or a nitrogen atom, preferably a carbon number;! A hydrocarbyl group of 20, or even 2 to 18 carbon atoms, especially 3 to 3 carbon atoms; 18 is preferred. The hydrocarbyl group may be linear, branched or cyclic. R ¹ and R ² may be the same or different, but are preferably the same for manufacturing reasons. Next, and are each independently a group represented by or, and are independently a hydrogen atom or a hydrocarbyl group having a carbon number of. As the hydrocarbyl group, those having a carbon number of ~; and further those having a carbon number of ~ are preferred. And may be the same or different from each other, but are preferably the same for reasons of production.

In the lubricating oil composition of the present invention, the content of the polysulfide above the trisulfide when the bond is represented by the above-mentioned general formula, ie, —— is based on the total amount with the disulfide compound. It is preferable that it is less than mass%. When this content is less than or equal to mass%, the corrosiveness to non-ferrous metals can be sufficiently suppressed. The content of the polysulfide compound more than trisulfide is more preferably not more than mass%, particularly preferably not more than mass%. Therefore, in the production of the disulfide compound represented by the above general formula, it is important to adopt a method in which the amount of by-product of the polysulfide compound higher than trisulfide falls within the above range. In the present invention, for example, it is preferably produced according to the following method.

That is, as a raw material, general formula and / or general formula

… (M)

… (

(Wherein, and, and are the same as above.)

The oxidative coupling is performed using a mercaptoalkanecarboxylic acid ester represented by: According to such a production method, a by-product of a polysulfide compound higher than trisulfide hardly occurs.

For example,

Is manufactured.

As an oxidizing agent used in the production of a corresponding disulfide by oxidizing an α-mercaptocarboxylic acid ester, an oxidizing agent used for producing a disulfide from mercaptan can be used. Oxidants include oxygen, hydrogen peroxide, halogen (iodine, bromine), and And manganese oxide (IV). Among these oxidizing agents, oxygen, hydrogen peroxide, and dimethyl sulfoxide are preferable because they are inexpensive and easy to produce disulfide. Specific examples of the disulfide compound represented by the general formula (I) include bis (methoxycarbonyl).

Bis (n dodecyloxycarbonyl,

Screw (1.

Norre- π-1 Bis (1-methoxycarbo Ninore π-Bis (1-Methoxycarboro n Dodecyl

2, 2-bis (2-methoxycarbonyl n-propinole) disulfide, α, α-bis (α-methoxycarbonylbenzyl) disulfide, 1,1 bis (2-methoxycarbonylbenzoyl) disulfide, 1,1 bis (2 —Ethoxycarbonylethyl) disulfide, 1,1 bis (2-η-propoxycarbonylruetinole) disulfide, 1,1 bis (2 isopropoxycarbonylethyl) disulfide, 1,1 bis (2-cyclopropoxycarbodi) Ruetinore) disulfide, 1, 1 bis (2-methoxycarbolulu η-propyl) Disunoreuid, 1, 1-bis (2-methoxycarbolulu η butinole) disulfide, 1, 1-bis (2-methoxycarbolulu) η-hexyl) disulfide, 1,1 bis (2-methoxycanolebonyl ηpropinole) disulfide, 2, 2 Bis (3 methoxycarbonoluene η pen chinole) disulfide, 1,1 bis (2-methoxycarbodiluene 1 phenethylenole) disulfide, and the like.

Furthermore, the compound represented by the general formula (II), which is the component (ii) used in the lubricating oil composition of the present invention, has the following structure:

R ⁷ OOC CR ⁹ R ¹⁰ — CR ^U (COOR ⁸ ) S— S CR ¹⁶ (COOR ¹³ ) CR ¹⁴ R ¹⁵ COO

R ¹² (II)

It is a disulfide compound having In the general formula (Π), in the formula, R ⁷ , R ⁸ , R ¹² and R ¹³ each independently have 1 to 30 carbon atoms which may contain an oxygen atom, a sulfur atom, or a nitrogen atom. It is a hydrocarbyl group, preferably a hydrocarbyl group having 1 to 20 carbon atoms, more preferably 2 to 18 carbon atoms, particularly 3 to carbon atoms; The hydrocarbyl group may be linear, branched or cyclic.

R ⁷ , R ⁸ , R ¹² and R ¹³ may be the same or different from each other, but are preferably the same for manufacturing reasons.

Next, R ^{9 to} R ^U and R ^{14 to} R ¹⁶ are each independently a hydrogen atom or a hydrocarbyl group having carbon number; A hydrogen atom is preferable because the raw material is easily available.

In the present invention, the disulfide compound is preferably produced, for example, according to the following two methods. That is, as the first production method, as a raw material, the general formula (V) and / or the general formula (VI)

R ^? OOC-CR ⁹ R ¹⁰ -CR ^U (COOR ⁸ ) —SH (V)

R ¹² OOC-CR ¹⁵ R ¹⁴ -CR ^lD (COOR ¹³ ) SH '-(VI)

(Wherein R ^{7 to} R ¹⁶ are the same as above.)

This is a method of oxidative coupling using a mercaptoalkanedicarboxylic acid diester represented by the formula:

[0018] Specifically,

R ⁷ OOC-CR ⁹ R ¹⁰ -CR ^U (COOR ⁸ ) — S— S— CR ¹⁶ (COOR ¹³ )-CR ^ CR ¹⁵ — COO R ¹² ,

R ⁷ OOC CR ⁹ R ¹⁰ CR ¹¹ (COOR ⁸ ) S— S— CR ^U (COOR ⁸ ) CR ¹⁰ CR ⁹ COOR ⁷ , and

R ¹² OOC—CR ¹⁵ R ¹⁴ —CR ¹⁶ (COOR ¹³ ) —S—S—CR ¹⁶ (COOR ¹³ ) CR ¹⁴ CR ¹⁵ —CO OR ¹² is produced.

In this case, the oxidizing agent includes oxygen, hydrogen peroxide, halogen (iodine, bromine), hypohalomanganese (IV), and the like. Among these oxidizing agents, oxygen, hydrogen peroxide, and dimethyl sulfoxide are preferable because they are inexpensive and easy to produce disulfide. [0019] Further, in the second production method of the disulfide compound, as a raw material, the general formula (VII) and

/ Or general formula (vm)

HOOC- CR ⁹ R ¹⁰ CR ^U (COOH) SH… (VII)

HOOC-CR ¹⁴ R ¹⁵ -CR ¹⁶ (COOH) — SH (VIII)

(In the formula, R ^{9 to} R ^U and R ^{14 to} R ¹⁶ are the same as described above.)

Oxidative coupling of the mercaptoalkanedicarboxylic acid represented by

This is a method in which a hydrocarbyl group having 1 to 30 carbon atoms which may contain an oxygen atom, a sulfur atom or a nitrogen atom is esterified with a monohydric alcohol. Specifically, in oxidative coupling,

HOOC-CR ⁹ R ¹⁰ -CR ¹¹ (COOH) S— S— CR ¹⁶ (COOH) — CR ¹⁵ R ¹⁴ — COOH, HOOC CR ⁹ R ¹⁰ CR ¹¹ (COOH) S— S— CR ^U (COOH) CR ¹⁰ R ⁹ COOH, and

HOOC-CR ¹⁴ R ¹⁵ -CR ¹⁶ (COOH) —S— S—CR ¹⁶ (COOH) —CR ¹⁵ R ¹⁴ — COOH In this case, the above oxidizing agents can be used.

[0020] Following oxidative coupling, general formula (IX)

R ¹⁷ — OH… (K)

(Wherein R ¹⁷ is the same as R ⁷ described above.)

Esterify with alcohol. For the esterification, the usual method of dehydration condensation using an acid catalyst can be used. By this method, specifically,

R ¹⁷ OOC-CR ⁹ R ¹⁰ -CR ^U (COOR ¹⁷ ) S— S— CR ¹⁶ (COOR ¹⁷ ) — CR ¹⁵ R ¹⁴ — COO R ¹⁷ ,

R ¹⁷ OOC CR ⁹ R ¹⁰ CR ¹¹ (COOR ¹⁷ ) S— S— CR ^U (COOR ¹⁷ ) CR ¹⁰ R ⁹ — COO R ¹⁷ , and

R ¹⁷ OOC-CR ¹⁴ R ¹⁵ -CR ¹⁶ (COOR ¹⁷ ) S—S—CR ¹⁶ (COOR ¹⁷ ) —CR ¹⁵ R ¹⁴ —COO R ¹⁷

[0021] Specific examples of the disulfide compound represented by the general formula (Π) include tetramethyl dithiomalate, tetraethyl dithiomalate, tetra-1-propyl dithiomalate, tetra-2-propyl dithiomalate, tetra-1-butyl dithiomalate, Dithiomalate Tet 2-butyl, tetraisobutyl dithiomalate, tetrahexyl dithiomalate, 1-octyl dithiomalate, tetra-1-dithiomalate (2-ethyl) hexyl, tetramonodithiomalate 1- (3, 5, 5 —Trimethyl) hexyl, tetrathiodithiolate, 1-decyl, tetrathiododecyl dithiomalate, tetrahexadithiomalate, 1-octadecyl dithiomalate, tetrabenzyl dithiomalate, tetra-dithiomalate α (methyl) benzyl, dithiomalate Tetra α, a dimethylbenzyl, tetrathiodithiolate (2-methoxy) ethyl, tetrathiodithiolate (2-ethoxy) ethyl, dithiomalate tetra (1-butoxy) ethyl, dithiomalate tetra (2—E Carboxymethyl) Echiru, Jichioringo acid tetra 1 i (2-butoxy Shibutokishi) Echiru, leaving at Jichioringo acid tetra 1 i (2-phenoxy) thereof and Echiru Rukoto force S.

[0022] The disulfide compound represented by the general formula (I) or the general formula (Π) is excellent in load carrying ability and wear resistance as a sulfur-based extreme pressure additive, and is an additive for a lubricating oil composition. Used as

In the lubricating oil composition of the present invention, the component (A) may contain one or two or more disulfide compounds represented by the above general formula (I). ), Or one or two or more of the disulfide compounds represented by Furthermore, a mixture of at least one disulfide compound represented by the general formula (I) and at least one disulfide compound represented by the general formula (II) may be included.

[0023] The content of the disulfide compound as the component (A) in the lubricating oil composition of the present invention is a force that is appropriately selected according to the purpose and conditions of use of the composition. It is preferable to include -0.50% by mass, more preferably in the range of 0.01-0.30% by mass.

[0024] Further, in the lubricating oil composition of the present invention, the component (B) contains 10 to 2000 ppm by mass of at least one selected from alkali metal or alkaline earth metal detergents as a metal. It takes a thing. Preferably it is 100-2000 mass ppm, More preferably, it is 200-2000 mass ppm.

Maintaining acid neutralization performance by keeping the content of component (B) within the above range as the amount of metal In addition, by suppressing the increase in ash content, it is possible to prevent clogging of DPF, suppress the formation of deposits, and extend the oil renewal interval.

[0025] The component (B) Al-strength metal or al-strength earth metal-based detergent (hereinafter sometimes abbreviated as "metal-based detergent") has acid neutralization performance, high-temperature cleanability, and wear resistance. It is preferable to use for enhancing the above. As the metal-based detergent, any metal-based detergent used for lubricating oils without particular limitation can be used. Specifically, for example, one or more metal-based cleaners selected from alkali metal sulfonate or alkaline earth metal sulfonate, alkali metal phenate or alkaline earth metal phenate, alkali metal salicylate, alkaline earth metal salicylate, etc. Agents. Examples of the alkali metal include sodium, potassium, and examples of the alkaline earth metal include magnesium, calcium, and barium. In particular, the alkaline earth metal magnesium and calcium are preferably used.

Yes

In the present invention, an alkaline earth metal sulfonate and / or an alkaline earth metal salicylate is used in order to obtain a composition having excellent base number maintenance, high temperature cleanability, and wear resistance. I prefer to do it. Preferably, the total base number is 20 to 600 mg KO H / g QlS K-2501: perchloric acid method). By making the total base number within the above range, the ability to neutralize acidic components generated by oxidation is ensured, the increase in ash content in the lubricating oil can be suppressed, and the formation of a large amount of deposits can be prevented by prolonged use. .

[0026] Alkaline earth metal sulfonates are alkaline earth metal salts of various sulfonic acids, and are usually obtained by a method of carbonating alkaline earth metal salts of various sulfonic acids. Examples of sulfonic acids include aromatic petroleum sulfonic acids, alkyl sulfonic acids, aryl sulfonic acids, and alkyl aryl sulfonic acids. Specifically, dodecyl benzene sulfonic acid, dilauryl cetyl benzene sulfonic acid, paraffin wax substitution Examples thereof include benzene sulfonic acid, polyolefin-substituted benzene sulfonic acid, polyisobutylene-substituted benzene sulfonic acid, and naphthalene sulfonic acid.

[0027] The alkaline earth metal salicylate is an alkali metal salt of an alkyl salicylic acid, usually alkylating phenol with α-olefin having 8 to 18 carbon atoms, and then introducing a carboxyl group by a Kolbeschmitt reaction. Obtained by the method of metathesis and carbonation. It is done. Specific examples of the alkyl salicylic acid include dodecyl salicylic acid, dodecyl methylolesalicylic acid, tetradecyl salicylic acid, hexadecyl salicylic acid, octadecyl salicylic acid, dioctyl salicylic acid and the like.

[0028] In the lubricating oil composition of the present invention, depending on the purpose of use, various additives such as other friction modifiers, antiwear agents, ashless dispersants, viscosity index improvers, A pour point depressant, an antifungal agent, a metal corrosion inhibitor, an antifoaming agent, a surfactant, an antioxidant and the like can be appropriately contained.

Examples of friction modifiers and antiwear agents include sulfur compounds such as olefin sulfide, dialkyl polysulfides, dialyl alkyl polysulfides, and dialyl polysulfides, phosphate esters, thiophosphate esters, and phosphorus oxides. Phosphorus compounds such as acid esters, alkyl hydrogen phosphates, phosphate ester amine salts, phosphite amine salts, chlorinated oils, chlorinated paraffins, chlorinated fatty acid esters, chlorinated fatty acid esters and other chlorinated compounds, Ester compounds such as alkyl or alkenyl maleic acid esters, alkyl or alkenyl succinic acid esters, organic acid compounds such as alkyl or alkenyl maleic acid, alkyl or alkenyl succinic acid, naphthenates, zinc dithiophosphate (ZnDTP), Dithio rubamate (ZnDTC), sulfurized O carboxymethyl molybdenum organo phosphorodithioate di Chio er HMoDTP), and an organic metal-based compounds such as sulfurized O carboxymethyl molybdenum Chio force Rubameto (MoDTC).

[0029] Examples of the ashless dispersant include succinimides, boron-containing succinimides, benzilamines, boron-containing benzylamines, succinic esters, fatty acids or succinic acids. Examples include amides of divalent carboxylic acids.

Examples of the viscosity index improver include polymetatalylate, dispersed polymetatalylate, olefinic copolymer (for example, ethylene propylene copolymer), dispersed olefinic copolymer, and styrene copolymer. Examples of the pour point depressant include polymetatalylate (for example, styrene-hydrogenated copolymer).

Examples of antifungal agents include, for example, alkenyl succinic acid and partial esters thereof, and examples of anticorrosive agents include benzotriazole, benzimidazole, benzothiazole, and thiadiazole, and antifoaming agents. For example, dimethylpolysiloxane For example, polyoxyethylene alkylphenyl ether or the like is used as the surfactant.

[0030] Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, alkylated mononaphthylamine, 2, 6-di-butyltalesol, 4, 4 ' Mention may be made of phenolic antioxidants such as -methylenebis (2,6-diΤ-butylphenol).

The lubricating oil composition for internal combustion engines of the present invention is excellent in wear resistance and heat resistance while having a low ash content, low phosphorus content and low sulfur content, and has a length that can extend the renewal interval of the lubricating oil. It is characterized by a long life, and is mainly used for internal combustion engines. Besides, drive system equipment such as automatic transmissions, shock absorbers, and power steering, lubricating oil for automobiles used in gears, cutting, grinding Metal oil used for metal processing such as processing and plastic processing, hydraulic oil that is used as power transmission fluid for hydraulic power systems such as hydraulic equipment and devices, power transmission, force control, buffering, etc. it can.

Example

[0031] Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

The analysis and evaluation of the lubricating oil composition prepared with the formulation shown in Table 1 followed the methods shown below.

(1) Phosphorus concentration measurement

Luminescence spectroscopic analysis was performed by ICP (Inductively Coupled Plasma) analysis (apparatus: IRIS Advantage manufactured by JARRELL ASH) to determine the mass% of phosphorus element in the sample. Table 1 shows the measurement results.

(2) Sulfur concentration measurement

Conforms to ASTM D-1552.

(3) Sulfated ash

Compliant with JIS K2272 "Crude oil and petroleum products-Test methods for ash and sulfate ash"

(4) Base number (hydrochloric acid method) Conforms to potentiometric titration method (base number / hydrochloric acid method) of JIS K2501 “Petroleum products and lubricating oil neutralization number test method”.

(5) Hot tube test

The test oil 0.3 milliliter / hr and air 10 milliliter / min were kept flowing in the glass tube with an inner diameter of 2 mm for 16 hours while maintaining the temperature of the glass tube at the specified evaluation temperature (280 ° C to 310 ° C). . The lacquer adhering to the glass tube was compared with the color sample, and the score was given as 10 points for transparent and 0 points for black. Higher grades indicate higher performance.

(6) 1 ^ \ ¥ —1 Friction test

Test apparatus: A friction test was conducted under the following conditions using an LFW-1 friction tester, and the wear scar width of the block after the test was measured.

Block material H-60, ring material S-10, rotation speed 1400rpm, oil temperature 80. C, load 30Lbs, time 30 minutes

(7) ISOT test (oxidation stability test)

The ISOT test was conducted in accordance with JIS K-2514 “Lubricating oil monoxide stability test”. In other words, an iron-copper plate was put into oil and stirred at 165.5 ° C., and the total base number after 96 hours was measured by JIS K-2501 (hydrochloric acid method).

Production Example 1 Production of bis (n otatoxycarbonylmethyl) disulfide

Mercaptomethanecarboxylic acid octyl ester was oxidatively coupled according to the method for producing the compound represented by the above general formula (I) to produce bis (n-otatoxycarbonylmethyl) disulfide. In this compound, the presence of polysulfide higher than trisulfide was not observed. Sulfur content 15. 8% by mass.

Mercaptomethanecarboxylic acid octyl ester in a 100 ml eggplant flask

40.8 g and dimethinolesnoreoxide 30.8 g were added and heated in an oil bath at 120 ° C. for 8 hours. After cooling, it was dissolved in 100 ml of toluene and washed 10 times to remove unreacted dimethyl sulfoxide. Toluene was distilled off under reduced pressure to obtain 30.5 g of bis (n oxycarbonylcarbonyl) disulfide.

[0033] Production Example 2 Oil-soluble molybdenum-containing composition

Polybuture (molecular weight 1000) succinic anhydride (PIBSA) and Huntsman Chemical From a mixture of polyethylene polyamine oligomers commercially available as E-100 polyethyleneamine, 250 g of bissuccinimide synthesized at a molar ratio of amine to PIBSA of 0.5: 1, and 162.5 g of neutral oil, It was placed in a glass reactor equipped with a mechanical stirrer and a water-cooled cooler. The mixture was heated to a molybdation reaction temperature of 70 ° C. While maintaining the reaction temperature, 26.6 g of molybdenum oxide and 45.8 g of water were added to the reactor. The reactor was then maintained at a reaction temperature of 70 ° C. for 28 hours. After the molybdation reaction, water was removed by distillation at a temperature of 99 ° C and a pressure of 25 mmHg (absolute value) or less for about 30 minutes. The product contained 4.01% by weight molybdenum and 1.98% by weight nitrogen. Examples;! -3, Comparative Example 1

A lubricating oil composition was prepared based on the formulation shown in Table 1.

Each of the obtained lubricating oil compositions was measured for phosphorus concentration, sulfur concentration and sulfated ash, and subjected to a hot tube test, LFW-1 friction test and ISOT test. Table 1 shows the measurement results and evaluation results.

[table 1]

Table 1

note"

* 1. 100N mineral oil: hydrorefined mineral oil, 100 ° C kinematic viscosity 4.5mm ² , sulfur content 0.01% by mass or less

* 2. 500N mineral oil: hydrorefined mineral oil, 100 ° C kinematic viscosity 10.9mm ² / s, sulfur content 0.01% by mass or less

* 3. Viscosity index improver: polymetatalylate (weight average molecular weight; 90, 000)

* 4. Pour point depressant: polyalkylmetatalylate (weight average molecular weight; 69, 000)

* 5. Disulfide: Bis (n-otatoxycarbonylmethyl) disulfide, sulfur content 1

Replacement paper (M26) 5. 8% by mass (prepared in Production Example 1)

* 6. Metal detergent: calcium sulfonate (base number 300mgKOH / g, calcium content; 12% by mass)

* 7. Hindered phenolic antioxidants: 4, 4'-methylenebis (2, 6-dibutylphenol)

* 8. Amine-based antioxidants: dialkyldiphenylamine (the alkyl group is a mixture of butyl and octyl groups)

* 9. Molybdenum-based antioxidant: Oil-soluble molybdenum-containing composition prepared in Production Example 2 * 10. Ashless dispersant: Polybutyruccinimide (nitrogen content; 0.7 mass%) * 11. Ashless Powder: Boron-modified polybutyrsuccinimide (boron content; 0.2% by mass, nitrogen content; 2.1% by mass)

* 12. Copper deactivator: Benzotriazole

* 13. Antifoaming agent: silicone oil

[0035] Table 1 shows the following.

Example 1 is one in which the sulfur content of ZnDTP is replaced with the disulfide compound according to the present invention in the prescription of the comparative example, and the wear resistance of Example 1 is equivalent to that of the comparative example. The property (hot tube test) is better than the comparative example.

In Example 2, the amount of sulfur relative to ZnDTP was reduced and replaced with the disulfide compound according to the present invention in the formulation of the comparative example, and the wear resistance and base number maintenance characteristics of Example 2 were compared with those of the comparative example. They are equivalent and have good heat resistance.

In Example 3, the amount of sulfur relative to ZnDTP in the formulation of the comparative example was reduced and replaced with the disulfide compound according to the present invention, and the sulfated ash content was adjusted to 0.6% by mass or less (Ca-based cleaning agent increased amount). ). The abrasion resistance of Example 3 is equivalent to that of the comparative example, and the heat resistance and the base value maintenance property are good.

[0036] The formulations of Examples;! To 3 do not contain phosphorus, which is the cause of catalyst poisoning. Further, as shown in Examples 2 and 3, the formulations of catalyst poisoning were not impaired without impairing wear resistance. It is possible to reduce the amount of sulfur that can be a cause. In general, there is an upper limit for sulfated ash that represents the total amount of metal that becomes clogged with DPF (API standards, JASO standards, etc.). Therefore, consider the impact on DPF. In other words, as shown in Example 3, the lubricating oil composition using the disulfide compound according to the present invention as a substitute for ZnDTP has a heat resistance that does not impair the wear resistance (hot tube test) and after the ISOT test. It is possible to improve the base number maintenance property.

Industrial applicability

The lubricating oil composition for an internal combustion engine of the present invention maintains wear resistance, has excellent heat resistance, and has an extended oil renewal interval while having a low ash content, low phosphorus content and low sulfur content. In addition to lubricating oils for internal combustion engines, automotive lubricating oils used in automatic transmissions, shock absorbers, power steering and other gear systems, gears, etc., cutting, grinding, plastic working It is suitably used as metal working oil used for metal processing such as, hydraulic fluid that is a power transmission fluid used for power transmission, force control, buffering, etc. in hydraulic systems such as hydraulic equipment and devices.

Claims

The scope of the claims

[1] Base oil and (A) —general formula (I)

R'OOC-A ¹ -S-S-A ² -COOR ² … (I)

(Wherein R ¹ and R ² are each independently an oxygen atom, a sulfur atom, or a nitrogen atom and a hydrocarbyl group having 1 to 30 carbon atoms, A ¹ and A ² are each independently CR ³ R 4 or CR ³ R ⁴ —CR ⁵ R ⁶ , wherein R ^{3 to} R ⁶ each independently represents a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. Disulfide compounds and general formula (Π)

(Wherein R ⁷ , R ⁸ , R ¹² and R ¹³ are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain an oxygen atom, a sulfur atom or a nitrogen atom, R ^{9 to} R ^U and R ^{14 to} R ¹⁶ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 5 carbon atoms.) And at least one selected from disulfide compounds represented by (B ) A lubricating oil composition for an internal combustion engine, comprising 10 to 2000 mass ppm as a metal amount of at least one selected from alkali metal or alkaline earth metal detergents.

[2] The lubricating oil composition for an internal combustion engine according to claim 1, comprising at least one selected from the disulfide compounds as component (A) in an amount of 0.01-0.50% by mass.

[3] The lubricating oil composition for an internal combustion engine according to claim 1, wherein the alkali metal or alkaline earth metal detergent as the component (B) comprises salicylate and / or sulfonate.

[4] The lubricating oil composition for an internal combustion engine according to claim 1, wherein the metal of the component (B) is Ca or Mg.