JPH09235579A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in oxidation stability, etc., by adding a specific organic dithiophosphoric acid zinc salt, a salicylic acid alkaline earth metal salt and a boron-containing alkenyl succinic acid imide having a specific atom composition as essential components to a lubricating oil component. SOLUTION: This lubricating oil composition is obtained by adding (A) an organic dithiophosphoric acid zinc salt having a 5-20C secondary hydrocarbon group, (B) a salicylic acid alkaline earth metal salt and (C) a boron-containing alkenylsuccinic acid imide having a boron/nitrogen atom number ratio of 0.2-0.4 as essential components to a lubricating base oil. The components A, B and C are preferably added in amounts of 0.04-0.2wt.% (as a phosphorus content), 0.05-2wt.% (as a metal content) and 0.005-0.4wt.% (as a nitrogen content), respectively, based on the whole amount of the lubricating oil composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel lubricating oil composition. More specifically, the present invention relates to a lubricating oil composition having excellent oxidative stability and achieving long drainage that can be used without replacement for a long period of time, and has an internal combustion engine, an automatic transmission, a shock absorber, A lubricating oil composition suitable for power steering and the like is provided.

[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 systems, gear devices, etc. in order to ensure smooth operation. In particular, lubricating oils for internal combustion engines mainly lubricate various sliding parts such as piston rings and cylinder liners, bearings of crankshafts and connecting rods, valve trains including cams and valve lifters, as well as cooling and combustion products inside the engine. It has the functions of clean dispersion and prevention of rust and corrosion.

As described above, the lubricating oil for an internal combustion engine is required to have various performances, and in addition to the high performance of the internal combustion engine such as low fuel consumption, high output and severe operating conditions in recent years, Lubrication performance is required.

As a basic function of the lubricating oil for an internal combustion engine, the internal combustion engine operates smoothly under all conditions,
It is required to prevent wear and seizure, suppress deterioration even under high-temperature, high-speed and high-load conditions and withstand long-term continuous use. Therefore, in order to satisfy such a required performance, for example, various additives such as an antioxidant, an antiwear agent, a metal-based detergent, an ashless dispersant, and a friction modifier are mixed with a lubricating base oil. There is.

However, for the lubricating oil for an internal combustion engine, the additive formulation proposed hitherto is still insufficient for extending the oil-refreshing period by suppressing its deterioration and achieving long-term use without replacement. At present, the renewal period of the commercially available internal combustion engine lubricating oil is one year at the longest, or 15,000.
Since it is necessary to change oil every time the vehicle travels km, complicated change work has been forced. Under these circumstances, there is a demand for maintenance-free lubricating oils for a longer period of time, and there is a strong demand for the development of lubricating oils with excellent long-drainability.

[0006]

Therefore, in view of the above-mentioned development situation, the present invention has an excellent oxidation stability under the conditions of high temperature, high speed and high load, which are difficult to achieve with the conventional lubricating oils for internal combustion engines. It is an object of the present invention to provide a lubricating oil composition having properties and suppressing deterioration of the lubricating oil component and achieving long drainage.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
In order to solve the above problems, as a result of intensive studies, as a disposal of additives having resistance to deterioration of lubricating oil components, a specific organic zinc dithiophosphate, an alkaline earth metal salt of salicylic acid and a boron-containing alkenyl of a specific composition It has been found that by using succinimide as an essential component, it has excellent oxidative stability and can extend the oil-refreshing period. The present invention has been completed based on such findings.

That is, the present invention relates to a lubricating base oil
(A) an organic zinc dithiophosphate having a secondary hydrocarbon group having 5 to 20 carbon atoms, (b) an alkaline earth metal salt of salicylic acid, and (c) a boron / nitrogen atom ratio of 0.2.
The present invention provides a lubricating oil composition, characterized in that a boron-containing alkenyl succinimide of 0.4 to 0.4 is contained as an essential component.

Further, as a preferred embodiment of the present invention, (a) based on the total weight of the lubricating oil composition with respect to the lubricating base oil.
Zinc dialkyldithiophosphate having a secondary alkyl group having 5 to 20 carbon atoms as a phosphorus amount is 0.04% by weight to 0.
2% by weight, (b) 0.05% by weight to 2% by weight of an alkaline earth metal salt of salicylic acid as a metal amount, and (c) a boron / nitrogen atom ratio of 0.2 to 0.4 in boron. 0.005% by weight to 0.4% by weight of alkenylsuccinimide as a nitrogen content, a lubricating oil composition containing as an essential component, based on the total weight of the lubricating oil composition (a) with respect to the lubricating base oil.
The zinc dialkyldithiophosphate having a secondary alkyl group having 5 to 20 carbon atoms is contained in an amount of 0.05% by weight to 0.
15% by weight, (b) calcium salicylate as a calcium amount of 0.1% by weight to 1% by weight, and (c) boron /
A boron-containing alkenyl succinimide having a nitrogen atom ratio of 0.2 to 0.4 is used in an amount of 0.005% by weight as a nitrogen amount.
A lubricating oil composition containing 0.4% by weight as an essential component can be provided.

The lubricating base oil that constitutes the lubricating oil composition of the present invention is not particularly limited, and those conventionally used as a lubricating base oil, such as various mineral oils or synthetic oils, are conventionally used. Can be used. As mineral oil,
Paraffin-based mineral oil, intermediate group-based mineral oil, naphthene-based mineral oil and the like can be mentioned. Specifically, raffinate, alumina or silinate obtained by solvent refining using an aromatic extraction solvent such as phenol or furfural as a lubricating oil raw material. Mineral oil such as hydrotreated oil obtained by hydrotreatment using a hydrotreating catalyst such as cobalt, molybdenum, nickel, etc. using caralumina as a carrier, or lubricating oil fraction obtained by isomerization of wax, for example, 60 Neutral oil,
100 neutral oil, 150 neutral oil, 300
Neutral oil, 500 neutral oil, bright stock, etc. can be used. Also, as synthetic oil,
For example, poly-α-olefin oligomer, polybutene, alkylbenzene, alkylnaphthalene, polybutene, polyol ester, that is, fatty acid ester such as neopentyl glycol, trimethylolpropane, pentaerythritol, dibasic acid ester, phosphoric acid ester, silicone oil, etc. Can be used. These mineral oils and synthetic oils may be used alone or may be mixed in any proportion and used. These mineral oils and synthetic oils used in the lubricating oil composition of the present invention generally have a kinematic viscosity of 1 cSt to 100 cSt, particularly 3 cSt to 20 cSt at 100 ° C.

On the other hand, as the additive (a) component organic zinc dithiophosphate constituting the lubricating oil composition of the present invention, the following general formula [I] is used.

[0012]

Embedded image Can be used.

In the above general formula [I], R ¹ , R ² ,
R ³ and R ⁴ are secondary hydrocarbon groups and may be the same or different from each other. Examples of the hydrocarbon group include an alkyl group having 5 to 20 carbon atoms; an alkenyl group having 5 to 20 carbon atoms; and an aryl group having 6 to 20 carbon atoms having a secondary alkyl group. A particularly preferred hydrocarbon group is a secondary alkyl group having 5 to 20 carbon atoms. Specifically, it is an alkyl group having a secondary carbon atom and having 5 to 20 carbon atoms, and is bonded to the oxygen atom in the above general formula [1] at the secondary carbon atom. Examples of such an alkyl group having a secondary carbon atom include 1
-Methylpentyl, 1-ethylbutyl, 1,3-dimethylbutyl, 1-methylheptyl, 1-ethylhexyl,
1-methyloctyl, 1-ethylheptyl, 1-methylnonyl, 1-ethyloctyl, 1-methylundecyl,
Examples thereof include 1-ethyldecyl, 1-methylheptadecyl, 1-ethylhexadecyl and the like. The alkyl group preferably has 6 to 13 carbon atoms. If the alkyl group has less than 5 carbon atoms, the decomposition temperature of the organic zinc zinc dithiophosphate may decrease, which may cause a problem in heat resistance. Therefore, it is preferable that the alkyl group has a long chain length, but even if the alkyl group has more than 20 carbon atoms. The heat resistance tends not to improve so much as the carbon number increases.

The content of zinc organic dithiophosphate is 0.04% by weight to 0.04% by weight based on the total weight of the lubricating oil composition.
2% by weight, preferably 0.05% to 0.15% by weight
It is. If the organic zinc zinc thiophosphate is less than 0.04% by weight, the resistance to deterioration is not sufficient, while if it exceeds 0.2% by weight, the effect corresponding to the increase in amount cannot be obtained.

The alkaline earth metal salt of salicylic acid as the additive (b), which is an essential component of the lubricating oil composition of the present invention, is not particularly limited, but the following general formula [ II]

[0016]

Embedded image Can be used.

In the above general formula [II], R ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and n is 1
Is an integer of 4 and M is an alkaline earth metal. As the above-mentioned hydrocarbon group, those having a relatively long chain having 6 to 20 carbon atoms are preferable, and examples thereof include an alkyl group having 6 to 20 carbon atoms; an alkenyl group having 6 to 20 carbon atoms; and a cycloalkyl group having 6 to 20 carbon atoms. An aryl group having 6 to 20 carbon atoms and the like can be mentioned, and the aryl group may have an alkyl group as a substituent. Particularly, a linear or branched alkyl group is preferable. Alkaline earth metals are calcium, barium and magnesium, with calcium being particularly preferred. Since the alkaline earth metal salt of salicylic acid has a hydroxyl group in its structure, it is presumed that it has an action as an antioxidant. The content of these alkaline earth metal salts of salicylic acid is 0.05% by weight to 2% by weight, and preferably 0.1% by weight, based on the total weight of the lubricating oil composition.
It is 1% by weight to 1% by weight. If the content of the metal is less than 0.05% by weight, the desired effect of the present invention cannot be obtained, while if it exceeds 2% by weight, the effect corresponding to the increase of the content cannot be obtained.

The boron-containing alkenyl succinimide as the additive (C) component as an essential component constituting the lubricating oil composition of the present invention is a boron compound derivative of alkenyl succinimide obtained from polyalkenyl succinic acid and polyamine. And, for example, the following general formula [III]

[0019]

Embedded image It is a boron compound derivative obtained by introducing a boron component into the alkenyl succinimide represented by. In addition, the following general formula [IV]

[0020]

Embedded image A boron compound derivative obtained by introducing a boron component into the bis-type alkenyl succinimide represented by can be similarly used.

In the above general formulas [III] and [IV], R ⁶ is an olefin oligomer group having 1 to 100 carbon atoms, R ⁷ is an alkylene group having 2 to 5 carbon atoms, and m and n are 1 It is an integer of -10. The general formula [I
In the compound [V], two R ^{6 s} may be the same or different. Examples of the olefin monomer of the olefin oligomer include ethylene, propylene, 1-butene, isobutylene, 1-hexene, and 2
-Methyl pentene-1, 1-octene and the like having 2 to 8 carbon atoms
.Alpha.-olefin can be used, and propylene and isobutylene having 3 to 4 carbon atoms are particularly preferable.

As a typical example of the alkenyl succinimide containing boron, a succinimide having an alkenyl group having a molecular weight of about 400 to 3,000, preferably polybutenyl succinimide, is subjected to a boration treatment to give boron a molecular structure. It is obtained by introducing into the inside.

One of the peculiarities of the present invention is that the boron-containing alkenyl succinimide has a boron / nitrogen atom ratio of 0.
This is the point specified in 2 to 0.4. When the boron / nitrogen atom ratio is less than 0.2, the heat resistance of the boron-containing alkenylsuccinimide cannot be sufficiently obtained, and when the boron / nitrogen atom ratio becomes large, the dispersibility decreases. The problem arises. Also, the ratio of the number of boron / nitrogen atoms is 0.4.
It also contains a problem that excessive boron is liberated and the total acid value is increased when it exceeds. Therefore, heat resistance and dispersibility can be balanced by setting the ratio of the number of atoms of boron / nitrogen to 0.2 to 0.4. Therefore, the method for producing the boron-containing alkenyl succinimide is not particularly limited and any method can be adopted, but the production conditions are set so that the ratio of the number of boron / nitrogen atoms is within the above range. This is very important. For example, a reaction product obtained by reacting a reaction product of an alkylene amine and a boron compound with a polyalkenyl succinic anhydride (see Japanese Patent Publication No. 42-8013), amino alcohol, boric acid, and oxyethane carvone. A condensation product with an acid (see JP-A-54-87705) or a reaction product obtained by sequentially reacting a polyalkenyl succinic anhydride with a polyalkylene glycol, a secondary alkanolamine and a boron compound is used. It can be used after adjusting the ratio of the number of atoms of boron / nitrogen to the above range.

The content of these boron-containing alkenyl succinimides is 0.005% by weight to 0.4% by weight, and preferably, the amount of nitrogen based on the total weight of the lubricating oil composition.
It is 0.1% by weight to 0.2% by weight. Content is 0.00
When it is less than 5% by weight, the resistance to deterioration is hardly improved. On the other hand, if it exceeds 0.4% by weight, the effect corresponding to the increase in the content cannot be obtained, and it is meaningless to increase the amount and mix it in the production.

The lubricating oil composition of the present invention contains various additives conventionally used in lubricating oils, such as antioxidants, viscosity index improvers, and pour point depressing agents, to the extent that the object of the present invention is not impaired. Agents, other friction modifiers, other abrasion agents, other ashless dispersants, antifoaming agents, rust preventives, corrosion inhibitors and the like can be appropriately added.

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,
Examples thereof include phenolic antioxidants such as 4,4′-methylenebis (2,6-di-t-butylphenol), and these are usually used in a proportion of 0.05% by weight to 5% by weight.

Examples of the viscosity index improver include polymethacrylate type, polyisobutylene type, ethylene-propylene copolymer system, styrene-butadiene hydrogenation copolymer system, etc., and these are usually 0.5% by weight. ~ 35
Used in percentages by weight. Examples of the pour point depressant include polyalkyl methacrylate, chlorinated paraffin-naphthalene condensate, alkylated polystyrene and the like.

Examples of other friction modifiers include partial esters of polyhydric alcohols, amines, amides, sulfurized esters and the like.

Other antiwear agents include, for example, sulfur compounds, phosphoric acid esters, phosphorous acid esters and the like, and these are usually used in a proportion of 0.05 to 5% by weight.

Examples of other ashless dispersants include succinamide-based, benzylamine-based, and ester-based dispersants, which are usually used in a proportion of 0.5% by weight to 7% by weight. It

Examples of the defoaming agent include dimethylpolysiloxane and polyacrylic acid.

Examples of the rust preventive include fatty acid, alkenyl succinic acid partial 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.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION

[0034]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

The oxidation test of the lubricating oil composition for judging the effect of the present invention was carried out in accordance with the method described in SAE952533. Oxidation stability increases total acid number, total residual base number,
It was evaluated by 40 ° C. viscosity ratio, aggregate pentane insoluble matter, blotter test and DSC oxidation start time.

Example 1 Trimethylolpropane ester 20 as a lubricating base oil
A mixture of 50% by weight and 80% by weight of poly-α-olefin (kinematic viscosity; 4.0 cSt @ 100 ° C.) was used, to which
Zinc dialkyldithiophosphate having a secondary alkyl group having a carbon number of 6 (1,3-dimethylbutyl group), calcium salicylate, and the ratio of the number of atoms of boron / nitrogen (B / N
ratio. same as below. ) Is 0.20 and a boron-containing alkenyl succinimide is added, and further a phenol-based, amine-based and molybdenum-based antioxidant, a viscosity index improver, and a pour point depressant shown in Table 2 are added. The thing was prepared. Table 1 shows the oxidation test results of the lubricating oil composition thus obtained.

Example 2 All were the same as Example 1 except that a boron-containing alkenyl succinimide having a B / N ratio of 0.26 was used in place of the boron-containing alkenyl succinimide having a B / N ratio of 0.20. Then, a lubricating oil composition was prepared. Table 1 shows the results of the oxidation test.

Example 3 All were the same as Example 1 except that a boron-containing alkenylsuccinimide having a B / N ratio of 0.40 was used in place of the boron-containing alkenylsuccinimide having a B / N ratio of 0.20. Then, a lubricating oil composition was prepared. Table 1 shows the results of the oxidation test.

Example 4 Zinc dialkyldithiophosphate was changed from one having a secondary alkyl group having 6 carbon atoms to one having a secondary alkyl group having 10 carbon atoms, and the boron-containing alkenyl succinimide was changed to B / N. A lubricating oil composition was prepared in the same manner as in Example 1 except that the ratio was changed from 0.20 to 0.26. Table 1 shows the results of the oxidation test.

Example 5 Mineral oil (kinematic viscosity; 4.0 cSt @ 100) as a lubricating base oil
A lubricating oil composition was prepared in the same manner as in Example 2 except that (° C.) Was used. Table 1 shows the results of the oxidation test.

Comparative Examples 1 to 5 Trimethylolpropane ester 20 as a lubricating base oil
By using a mixture of 50% by weight and 80% by weight of poly-α-olefin (kinematic viscosity; 4.0 cSt @ 100 ° C.), and mixing each of the additive components shown in Table 1 in the ratio shown in the same table, lubrication An oil composition was prepared. Table 1 shows the oxidation test results of these lubricating oil compositions. Comparative Examples 1 and 2 show cases where the B / N ratios of the alkenyl succinimide containing boron were 0.15 and 0.42, respectively, and Comparative Example 3 shows the case where calcium sulfonate was used. In Comparative Example 4, the alkyl group of zinc dialkyldithiophosphate has 3 carbon atoms, and Comparative Example 5 uses zinc dialkyldithiophosphate having a primary alkyl group (n-hexyl group) of 6 carbon atoms. Is. The above-mentioned comparative examples all show cases outside the scope of the present invention. The results of each oxidation test are shown in Table 1.

[0042]

[Table 1]

[0043]

[Table 2] From the above Examples and Comparative Examples, the lubricating oil composition having strong resistance to deterioration and achieving long drainage is (a) an organic zinc dithiophosphate having a secondary alkyl group having 5 to 20 carbon atoms, ( It was revealed that it was obtained by adding b) an alkaline earth metal salt of salicylic acid and (c) a boron-containing alkenyl succinimide having a B / N ratio of 0.2 to 0.4 as essential components, which is extremely specific. It is understood that it provides an additive formulation.

[0044]

The lubricating oil composition of the present invention is (a) an organic zinc dithiophosphate having a secondary alkyl group having 5 to 20 carbon atoms and (b) an alkaline earth metal salicylic acid with respect to a lubricating base oil. It was obtained by adding a salt and (c) a boron-containing alkenyl succinimide having a B / N ratio of 0.2 to 0.4 as an essential component, and as a result, the resistance to deterioration of the lubricating oil component was enhanced. Was done. Therefore, it is possible to realize a lubricating oil composition that achieves long drainage,
It can be suitably used as a lubricating oil for an internal combustion engine, an automatic transmission, a shock absorber, a power steering, etc., especially as an internal combustion engine lubricating oil.

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Claims (1)

[Claims] 1. A lubricating base oil (1) having 5 to 5 carbon atoms
Organic zinc dithiophosphates having 20 secondary hydrocarbon groups, (2) alkaline earth metal salts of salicylic acid, and (3) boron-containing alkenyl having a boron / nitrogen atom ratio of 0.2 to 0.4. A lubricating oil composition comprising succinimide as an essential component.