JPH07331269A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil composition useful for a lubricating oil for an internal combustion such as an engine of an automobile, showing oily effects by strongly adsorbing on frictional surface and having reducing action on a coefficient of friction even at a middle or low oil temperature and under a driving condition of a low-speed revolution. CONSTITUTION:This lubricating oil composition comprises (A) an oxymolybdenum dithiocarbamate sulfide containing a 8-18C hydrocarbon group, (B) a zinc dialkyldithiophosphate and (C) a boron-containing succinimide. The amount of molybdenum derived from the oxymolybdenum dithlocarbamate sulfide is 200-1,000ppm (weight ratio) based on the whole weight of the composition, the amount of phosphorus owing to the zinc dialkyldithiophosphate is 0.04-0.15wt.% and the amount of born owing to the baron-containing succinimide is 0.005-0.06wt.% to give the objective lubricating oil composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel lubricating oil composition. More specifically, the present invention provides a low coefficient of friction under a wide range of use conditions, particularly operating conditions of medium and low oil temperature and low speed rotation, and lubricating oil for internal combustion engines such as automobile engines, gear oil, automatic transmission fluid, The present invention relates to a lubricating oil composition suitable as a lubricating oil for automobiles such as shock absorber oil.

[0002]

2. Description of the Related Art Lubricating oil is used in internal combustion engines, automatic transmissions, shock absorbers, drive system devices such as power steering, gears, etc. in order to ensure smooth operation. In particular, lubricating oil for internal combustion engines is mainly used for piston rings and cylinder liners, bearings for crankshafts and connecting rods,
In addition to lubrication of various sliding parts such as valve mechanism including cam and valve lifter, it also functions to cool the engine, cleanly disperse combustion products, and prevent rust and corrosion.
As described above, lubricating oils for internal combustion engines are required to have various performances, and in recent years, high performances have been required as the performances, output power, and operating conditions of internal combustion engines have become more severe. . Therefore, various additives such as an antiwear agent, a metal detergent, an ashless dispersant, and an antioxidant are blended with the lubricating oil for an internal combustion engine in order to satisfy such required performance. As the basic function of lubricating oil for internal combustion engines,
In particular, it is important to operate the engine smoothly under all conditions to prevent wear and seizure. The engine lubrication section
Most of them are in fluid lubrication, but boundary lubrication is likely to occur at valve operating systems and top and bottom dead centers of pistons.The wear resistance under such boundary lubrication is generally determined by adding zinc dithiophosphate or zinc dithiocarbamate. Has been granted by. By the way, in an internal combustion engine, since a large amount of energy is lost in a friction portion where the lubricating oil is involved, a lubricating oil in which various additives such as a friction modifier are combined is used as a measure for reducing the friction loss and the fuel consumption. (For example, Japanese Examined Patent Publication No. 3-23595). The internal combustion engine of a car
It is operated in a wide range of oil temperature, rotation speed, and load, and therefore, in order to further improve fuel economy, the internal combustion engine lubricating oil needs to have excellent friction characteristics under a wide range of use conditions. Conventionally, in order to lower the coefficient of friction, a combination of zinc dithiophosphate, succinimide, calcium sulfonate, sulfurized oxymolybdenum dithiocarbamate, etc. has been used. However, such a lubricating oil has a problem that a sufficiently low friction coefficient cannot be obtained under operating conditions of low and medium oil temperatures and low speed rotation.

[0003]

DISCLOSURE OF THE INVENTION The present invention is a lubricant which is suitable as a lubricating oil for an internal combustion engine of an automobile and which provides a low friction coefficient under a wide range of use conditions, particularly under operating conditions of medium and low oil temperature and low speed rotation. The purpose of the invention is to provide an oil composition.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies to develop a lubricating oil composition having the above-mentioned preferable properties, the present inventors have found that the lubricating base oil has a specific alkyl group. Sulfurized oxymolybdenum dithiocarbamate, zinc dialkyldithiophosphate having a specific alkyl group,
The inventors have found that a lubricating oil composition containing boron and succinimide containing boron in specific proportions can meet the purpose, and based on this finding, the present invention has been completed. That is, the present invention, for lubricating base oil,
(A) a sulfurized oxymolybdenum dithiocarbamate having a hydrocarbon group having 8 to 18 carbon atoms, (B) a zinc dialkyldithiophosphate having a primary alkyl group having 1 to 18 carbon atoms,
And (C) a lubricating oil composition containing boron-containing succinimide, wherein the amount of molybdenum derived from sulfurized oxymolybdenum dithiocarbamate is 200 to 1000 ppm (weight ratio) based on the total weight of the composition, and the dialkyl The amount of phosphorus derived from zinc dithiophosphate is 0.04 to 0.1
It is 5% by weight, and the amount of boron derived from the boron-containing succinimide is 0.005 to 0.06% by weight, which provides a lubricating oil composition.

The present invention will be described in detail below. The lubricating base oil used in the lubricating oil composition of the present invention is not particularly limited, and those conventionally used as a base oil for lubricating oil, such as mineral oil and synthetic oil, are used. As mineral oil, raffinate obtained by solvent refining a lubricating oil raw material with an aromatic extraction solvent such as phenol or furfural, hydrotreating with a hydrotreating catalyst such as cobalt or molybdenum using silica-alumina as a carrier Or a mineral oil such as a lubricating oil fraction obtained by isomerizing a wax, for example, 60 neutral oil, 100 neutral oil, 150 neutral oil, 3
Examples include 00 neutral oil, 500 neutral oil, and bright stock. On the other hand, examples of the synthetic oil include poly α-olefin oligomer, polybutene, alkylbenzene, polyol ester, polyglycol ester, dibasic acid ester, phosphoric acid ester and silicone oil. These base oils may be used alone, or may be used in combination of two or more kinds, and mineral oil and synthetic oil may be mixed and used. This base oil usually has a kinematic viscosity at a temperature of 100 ° C. of 3 to 20 c.
Those in the range of St are preferable. The sulfurized oxymolybdenum dithiocarbamate used in the lubricating oil composition of the present invention has the general formula [1]

[Chemical 1] (However, in the formula, R ¹ and R ² each have 8 to 18 carbon atoms.
, Which may be the same or different, and m and n are positive integers such that their sum is 4. The compound represented by these can be used. Examples of the hydrocarbon group having 8 to 18 carbon atoms represented by R ¹ and R ² in the general formula [1] include, for example, an alkyl group having 8 to 18 carbon atoms, an alkenyl group having 8 to 18 carbon atoms, and a carbon number. Hydrocarbon groups such as cycloalkyl groups having 8 to 18 carbon atoms, aryl groups having 8 to 18 carbon atoms, alkylaryl groups, and arylalkyl groups can be mentioned. The alkyl group or alkenyl group may be linear or branched. In the lubricating oil composition of the present invention, it is particularly preferable that the hydrocarbon group represented by R ¹ and R ² has 8 carbon atoms. Specific examples of the hydrocarbon group represented by R ¹ and R ² include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, hexadecenyl,
Octadecenyl, dimethylcyclohexyl, ethylcyclohexyl, methylcyclohexylmethyl, cyclohexylethyl, propylcyclohexyl, butylcyclohexyl, heptylcyclohexyl, dimethylphenyl,
Examples thereof include methylbenzyl, phenethyl, naphthyl and dimethylnaphthyl groups. In the lubricating oil composition of the present invention, one type of sulfurized oxymolybdenum dithiocarbamate may be used, or two or more types may be used in combination. The sulfurized oxymolybdenum dithiocarbamate has an amount of molybdenum derived from the sulfurized oxymolybdenum dithiocarbamate of 200 to 200 based on the total weight of the composition.
1000 ppm (weight ratio), preferably 300
It is blended so that it becomes ~ 800ppm (weight ratio). When the amount of sulfurized oxymolybdenum dithiocarbamate is less than 200 ppm (weight ratio) of molybdenum derived from sulfurized oxymolybdenum dithiocarbamate based on the total weight of the composition, the effect of improving the friction characteristics is sufficiently exhibited. The amount of molybdenum derived from sulfurized oxymolybdenum dithiocarbamate is 100 based on the total weight of the composition.
When the amount is more than 0 ppm (weight ratio), the effect is not improved for the amount, and sludge is likely to be a cause.

The zinc dialkyldithiophosphate used in the lubricating oil composition of the present invention has the general formula [2]

[Chemical 2] (However, in the formula, R ³ and R ⁴ are primary alkyl groups having 1 to 18 carbon atoms, and they may be the same or different from each other.). The primary alkyl groups represented by R ³ and R ⁴ in the general formula [2] are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl. , Pentadecyl, hexadecyl, heptadecyl and octadecyl groups, it is preferable to use zinc dialkyldithiophosphate having a primary alkyl group having 3 to 12 carbon atoms in the lubricating oil composition of the present invention. In the lubricating oil composition of the present invention, it is essential that the alkyl group of zinc dialkyldithiophosphate is a primary alkyl group, and when the alkyl group is secondary or tertiary, sufficient friction is obtained. No improvement in characteristics can be obtained. In the lubricating oil composition of the present invention, one type of zinc dialkyldithiophosphate having a primary alkyl group may be used, or two or more types may be used in combination. The zinc dialkyldithiophosphate is preferably 0.06 to 0.12% by weight so that the amount of phosphorus derived from the zinc dialkyldithiophosphate is 0.04 to 0.15% by weight based on the total weight of the composition. Blend so that When the amount of zinc dialkyldithiophosphate mixed is such that the amount of phosphorus derived from zinc dialkyldithiophosphate is less than 0.04% by weight based on the total weight of the composition, abrasion resistance becomes insufficient. However, a satisfactory low coefficient of friction cannot be obtained under the operating conditions of low and medium oil temperature and low speed, and the amount of zinc dialkyldithiophosphate added is based on the total weight of the composition. If the amount exceeds 0.15% by weight, no improvement in the effect is observed for the amount. The boron / nitrogen atom ratio in the boron-containing succinimide used in the lubricating oil composition of the present invention is 0.05 to 1.5, preferably 0.1 to 0.8. When the ratio of the number of atoms of boron / nitrogen is less than 0.05, sufficient improvement of the friction characteristics cannot be obtained, and when the ratio of the number of atoms of boron / nitrogen exceeds 1.5, the friction characteristics deteriorate. In the lubricating oil composition of the present invention, the boron-containing succinimide is preferably such that the amount of boron derived from the boron-containing succinimide is 0.005 to 0.06% by weight, based on the total weight of the composition. It is blended so as to be 0.01 to 0.04% by weight. When the amount of the boron-containing succinimide compounded is such that the amount of boron derived from the boron-containing succinimide is less than 0.005% by weight based on the total weight of the composition, sufficient improvement in friction characteristics can be obtained. Or, the amount of boron-containing succinimide blended is such that the amount of boron derived from boron-containing succinimide is 0, based on the total weight of the composition.
When the amount is more than 06% by weight, the improvement of the effect is not recognized for the amount. In the lubricating oil composition of the present invention,
One type of boron-containing succinimide may be used, or two or more types may be used in combination.

The lubricating oil composition of the present invention contains various additives conventionally used in lubricating oils, such as metal detergents, other friction modifiers, and antioxidants, as long as the object of the present invention is not impaired. Agents, viscosity index improvers, pour point depressants, defoamers, other antiwear agents, rust preventives, corrosion inhibitors and the like can be appropriately added. Examples of the metal-based detergent include calcium sulfonate, magnesium sulfonate, barium sulfonate, calcium phenate, barium phenate, calcium salicylate, magnesium salicylate, etc. These are usually used in a proportion of 0.1 to 5% by weight. To be done. Examples of the friction modifier include polyhydric alcohol partial ester, amine, amide, sulfurized ester and the like. Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine and alkylated-α-naphthylamine, 2,6-di-t-butyl-4-methylphenol, 4,4 Examples include phenolic antioxidants such as'-methylenebis (2,6-di-t-butylphenol), which are usually used in a proportion of 0.05 to 2% by weight. Examples of the viscosity index improver include polymethacrylate-based, polyisobutylene-based, ethylene-propylene copolymer system, styrene-butadiene hydrogenated copolymer system and the like, and these are usually in a proportion of 0.5 to 35% by weight. Used in. Examples of the pour point depressant include polyalkylmethacrylate, chlorinated paraffin-naphthalene condensate, alkylated polystyrene and the like. Examples of the defoaming agent include dimethyl polysiloxane and polyacrylic acid. Examples of the antiwear agent include metal salts of thiophosphoric acid, metal salts of thiocarbamic acid, sulfur compounds, phosphoric acid esters, phosphorous acid esters, etc., and these are usually 0.05 to 5.0% by weight. Used in proportion. Examples of the rust preventive include fatty acid, alkenyl succinic acid half ester, fatty acid soap, alkyl sulfonate, fatty acid polyhydric alcohol ester, fatty acid amine, oxidized paraffin, alkyl polyoxyethylene ether and the like. Examples of the corrosion inhibitor include benzotriazole and benzimidazole.

[0008]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The friction coefficient of the lubricating oil composition was measured using a reciprocating sliding friction tester [SRV friction tester] at a frequency of 50 Hz, an amplitude of 3 mm, a load of 25 N, a temperature of 80 ° C., and a test time of 25 minutes. Examples 1 to 8 and Comparative Examples 1 to 3 Base oil (100 neutral oil, viscosity at 100 ° C. 4.4 mm / s ² ), and each type and amount of each compounding component shown in Table 1, and as a metal-based detergent. A lubricating oil composition containing 2.0% by weight of calcium sulfonate was prepared and the coefficient of friction was measured. The results are shown in Table 1.

[0009]

[Table 1]

When the lubricating oil compositions of the present invention of Examples 1 to 8 were used, they all had a low friction coefficient and exhibited good friction characteristics. On the other hand, Comparative Example 1 in which zinc dialkyldithiophosphate having a secondary alkyl group is blended, Comparative Example 2 in which succinimide is blended instead of boron-containing succinimide, and a primary alkyl group is included. The content of phosphorus derived from zinc dialkyldithiophosphate was 0.03.
It can be seen that the lubricating oil compositions of Comparative Example 3 in which the weight percentage is set have a high friction coefficient and insufficient friction characteristics.

[0011]

INDUSTRIAL APPLICABILITY The lubricating oil composition of the present invention exerts an oily effect by strongly adsorbing to the friction surface even under the operating conditions of medium and low oil temperature and low speed rotation, and has a function of reducing the friction coefficient. is doing. The lubricating oil composition of the present invention can be suitably used as a lubricating oil for internal combustion engines such as automobile engines, and for automobiles such as gear oil, automatic transmission fluid and shock absorber oil.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C10N 10:04 10:12 40:04 40:08 40:25 (72) Inventor Katsuya Arai Iruma Gundai, Saitama Prefecture Icho Nishi Tsurugaoka 1-3-1 Tonen Corporation Research Institute (72) Inventor Hirotaka Tomizawa Nishii Tsurugaoka 1-3-1 Toinzawa Research Institute Tonen Research Institute

Claims (1)

[Claims] 1. A lubricating base oil comprising: (A) a sulfurized oxymolybdenum dithiocarbamate having a hydrocarbon group having 8 to 18 carbon atoms, and (B) a dialkyl having a primary alkyl group having 1 to 18 carbon atoms. A lubricating oil composition containing zinc dithiophosphate and (C) boron-containing succinimide, wherein the amount of molybdenum derived from sulfurized oxymolybdenum dithiocarbamate is 200 to 1000, based on the total weight of the composition.
ppm (weight ratio), the amount of phosphorus derived from zinc dialkyldithiophosphate is 0.04 to 0.15% by weight, and the amount of boron derived from boron-containing succinimide is 0.0
A lubricating oil composition, characterized in that it is from 05 to 0.06% by weight.