JP3352123B2 - Lubricating oil composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition having excellent heat resistance and abrasion resistance. The present invention relates to a lubricating oil composition having excellent lubricity.

[0002]

2. Description of the Related Art In general, among various lubricating oil compositions, lubricating oils used in various industrial facilities other than engine lubricating oils include hydraulic oils, bearing oils for industrial machines, gear oils, and sliding surface oils. It has been known. Conventionally, for example, as a working oil or a bearing oil, a rust inhibitor (Rust inhibit)
ors) and antioxidants (Oxidation inhibitors), and the so-called Anti-wear type, which contains anti-wear agents such as zinc dithiophosphate and phosphate ester. Have been. However, in recent years, with the miniaturization and high output of hydraulic equipment, the former R & O type hydraulic oil has become insufficient in both abrasion resistance and heat resistance, while the latter anti-wear type hydraulic oil Although abrasion resistance is high, there is a problem that it cannot be used because of its poor heat resistance. Therefore, in consideration of heat resistance, it is conceivable to divert an engine lubricating oil containing a relatively large amount of a detergent / dispersant. Problem.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention is excellent in heat resistance and abrasion resistance, does not generate sludge even when used in a high-temperature atmosphere, and has an anti-emulsifying property. It is an object of the present invention to provide a lubricating oil composition having high rust prevention and suitable for use in various refrigerators, high-output hydraulic devices or bearings of industrial machines.

[0004]

The present inventors have conducted intensive studies to develop a lubricating oil composition having the above-mentioned preferable properties. As a result, the lubricating oil base oil contains an alkali metal salt of a carboxylic acid and a polyalkylene. A composition in which glycol monoalkyl ether and zinc dithiophosphate or (phosphite) phosphate compound are blended at a predetermined ratio, respectively,
It has been found that the purpose can be achieved. The present invention has been completed based on such findings. That is, the present invention relates to mineral oil, poly-α-olefin, alkylbenzene
And at least one member selected from the group of alkylnaphthalenes
(A) alkali metal salt of carboxylic acid in two lubricating base oils
0.01 to 2% by weight, (B) 0.01 to 5% by weight of a polyalkylene glycol monoalkyl ether and (C) at least one phosphorus selected from zinc dithiophosphate, a phosphate compound and a phosphite compound. An object of the present invention is to provide a lubricating oil composition comprising 0.01 to 2% by weight of a compound.

The lubricating base oil in the lubricating oil composition of the present invention is a mineral oil or a synthetic oil having a lubricating viscosity, and more specifically, a kinematic viscosity at a temperature of 40 ° C. of 10 to 500 cSt.
Mineral oils or synthetic oils in the above range are preferably used. As the mineral oil, those conventionally used as base oils for lubricating oils are applied, and typical examples thereof include hydrogenated refined mineral oil and solvent refined mineral oil. In addition, there are various synthetic oils.
α-olefins (including oligomers), alkylbenzenes, alkylnaphthalenes, various esters, ie, esters of polyhydric alcohols such as neopentyl glycol, trimethylolpropane, pentaerythritol and fatty acids, or polycarboxylic acids such as adipic acid and sebacic acid And an aliphatic alcohol. These mineral oils and synthetic oils can be used alone or in combination at any ratio.

In the lubricating oil composition of the present invention, there are various types of alkali metal salts of the carboxylic acid of the component (A) to be blended with the lubricating base oil.

[0007]

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(Wherein, R ¹ represents an alkyl group having 8 to 24 carbon atoms or an alkenyl group having 8 to 24 carbon atoms, and Me is an alkali metal). Alternatively, an alkali metal salt of an unsaturated fatty acid may be used. The saturated fatty acid or unsaturated fatty acid may have a hydroxyl group in its fatty chain. The alkali metal of the alkali metal salt is sodium, potassium or lithium. Here, as the saturated fatty acid, specifically, for example, nonanoic acid, lauric acid, palmitic acid, stearic acid, isostearic acid,
Behenic acid and the like. As the unsaturated fatty acids, specifically, for example, oleic acid, linolenic acid,
Erucic acid, linoleic acid, ricinolenic acid and the like can be mentioned.

The alkali metal salt of a carboxylic acid as the component (A) includes the general formula (II) MeOOC-R ² -COOMe (II) (wherein R ² is an alkylene having 4 to 36 carbon atoms) , An alkylalkylene group or an alkenylalkylene group, and Me is an alkali metal.) A saturated dicarboxylic acid or an alkali metal salt of an unsaturated dicarboxylic acid comprising a divalent carboxylic acid represented by the following formula: And
The alkali metal of the alkali metal salt is sodium, potassium or lithium. Here, this saturated dicarboxylic acid is specifically, as a saturated dicarboxylic acid having an alkylene group having 4 to 36 carbon atoms, for example, adipic acid,
Examples include azelaic acid, sebacic acid, dodecane diacid, isoeicosane diacid, and a dimer of oleic acid. Examples of the saturated dicarboxylic acid having an alkylalkylene group having 4 to 36 carbon atoms include octylsuccinic acid and octadecylsuccinic acid. The unsaturated dicarboxylic acid is, specifically, an unsaturated dicarboxylic acid having an alkenylalkylene group having 12 to 18 carbon atoms, for example, octenylsuccinic acid, pentadecenylsuccinic acid, octadecenylsuccinic acid and the like. No.

In the lubricating oil composition of the present invention, when the alkali metal salt of the carboxylic acid as the component (A) is mixed with the lubricating base oil, the amount of the carboxylic acid is 0.1% based on the total weight of the composition.
The content is 0.01 to 2% by weight, preferably 0.03 to 0.5% by weight. Here, if the compounding amount is less than 0.01% by weight, the effect is not recognized on heat resistance, abrasion resistance and demulsifying property. On the other hand, if it exceeds 2% by weight, it is not preferable because it is difficult to dissolve and the demulsifying property is lowered.

Next, in the lubricating oil composition of the present invention, there are various types of the polyalkylene glycol monoalkyl ether as the component (B) blended in the lubricating base oil.
For example, the general formula (III) R ³ —O (R ⁴ O) _m H (III) (wherein, R ³ represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms) , R ⁴ represents an alkylene group having 2 or 3 carbon atoms, and m is an integer of 1 to 6.)
Can be mentioned. Here, as the alkyl group having 1 to 20 carbon atoms, specifically, for example, butyl group, hexyl group, octyl group, 2-ethyl-hexyl group, nonyl group, dodecyl group, palmityl group, stearyl group, isostearyl And oleyl groups. Further, specific examples of the aryl group having 6 to 20 carbon atoms include a nonylphenyl group, an octylphenyl group, and a dodecylphenyl group. As the polyalkylene glycol monoalkyl ether,
Specifically, polyoxyethylene (2 mol addition) octyl ether in which 2 mol of ethylene glycol is added to octyl alcohol, polyoxypropylene (3 mol addition) lauryl ether in which 3 mol of propylene glycol is added to lauryl alcohol, oleyl Examples thereof include polyoxyethylene (4 mole addition) oleyl ether in which 4 moles of ethylene glycol are added to an alcohol, and polyoxypropylene (3 mole addition) isostearyl ether in which 3 moles of propylene glycol are added to isostearyl alcohol. In the lubricating oil composition of the present invention, when blending the polyalkylene glycol monoalkyl ether of the component (B) with the lubricating base oil, 0.01 to 5% by weight, preferably with respect to the total weight of the composition, is preferable. Is contained in an amount of 0.3 to 3% by weight. Here,
If the amount is less than 0.01% by weight, the effects on heat resistance and antioxidant properties are not recognized. On the other hand, if the content exceeds 5% by weight, the demulsifying properties are undesirably reduced.

And, in the lubricating oil composition of the present invention,
The component (C) blended in the lubricating base oil is at least one phosphorus-containing compound selected from zinc dithiophosphate, phosphate esters and phosphite esters. As the zinc dithiophosphate blended as one of the components (C), a compound represented by the general formula (IV)

[0013]

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Wherein R ⁵ , R ⁶ , R ⁷ and R ⁸ are each a primary or secondary alkyl group, an aryl group or an aralkyl group, which may be the same or different; The number is from 3 to 20.). Specific examples of such a substance include zinc dihexyldithiophosphate, zinc dioctyldithiophosphate, zinc dinonyldithiophosphate,
Zinc didecyldithiophosphate, zinc dododecyldithiophosphate, zinc dinonylphenyldithiophosphate, zinc didodecylphenyldithiophosphate, zinc ditolyldithiophosphate, and the like. These zinc dithiophosphates may be used alone or in a combination of two or more. And the content is 0.01 to 2 with respect to the total weight of the composition.
It is selected in the range of weight%. If the content is less than 0.01% by weight, the effect of improving the wear resistance and antioxidant properties is not sufficiently exhibited. On the other hand, if it exceeds 2% by weight, the demulsifying property tends to decrease.

Among the other components blended as the component (C), the phosphoric ester compound includes, for example, a compound represented by the general formula (V):

[0016]

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Wherein R ⁹ , R ¹⁰ and R ¹¹ are each hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms or an alkyl-substituted aryl group having 7 to 20 carbon atoms. However, R ^{9 to} R ¹¹ cannot be hydrogen at the same time.). And as the phosphite compound,
> For example, general formula (VI)

[0018]

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(Wherein R ⁹ , R ¹⁰ and R ¹¹ are the same as described above). Here, as the above-mentioned phosphate compound, specifically, for example, oleyl acid phosphate, lauryl acid phosphate, o-ethylhexyl acid phosphate, stearyl acid phosphate, butyl acid phosphate, dioleyl acid Phosphate, dilauryl acid phosphate, di-2-ethylhexyl acid phosphate, distearyl acid phosphate, dibutyl acid phosphate and the like can be mentioned. Specific examples of the phosphite compound include dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, dibutyl hydrogen phosphite, distearyl hydrogen phosphite, and diphenyl hydrogen phosphite. . Each of these phosphate compounds and phosphite compounds may be used alone or in combination of two or more. And its content is selected in the range of 0.01 to 2% by weight based on the total weight of the composition. If the content is less than 0.01% by weight, the effect of improving wear resistance is not sufficiently exhibited. If the content exceeds 2% by weight, the heat resistance and the demulsifying properties tend to decrease.

The lubricating oil composition of the present invention may contain, if necessary, other additives conventionally used as a component (D) in lubricating oils, for example, as long as the object of the present invention is not impaired.
Antioxidants, defoamers, rust inhibitors and the like can be added. Examples of the antioxidant include phenol-based and amine-based antioxidants. Examples of the antifoaming agent include silicone oil, esters, and silicate. Examples of the rust preventive include sulfonates such as alkali metal salts and alkaline earth metal salts of sulfonic acids such as petroleum sulfonic acid, dinonylnaphthalenesulfonic acid, and heavy alkylbenzenesulfonic acid; and alkyl or alkenyl succinic acids. Are preferably used.

[0021]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The appearance and performance of the lubricating oil composition were determined as follows. (1) Appearance By visual observation. (2) Demulsifying property The time (minute) until the emulsified phase became 3 ml or less was measured according to JIS K-2520. (3) Abrasion resistance 1200 rpm, 3 according to ASTM D-2783
A wear test was performed under the conditions of 0 kgf and 30 minutes, and the wear scar diameter (mm) was measured. (4) Rust-prevention property It was determined according to the method 2.5.1 of JIS K-2510.
In addition, evaluation followed the following. Judgment ×: rusting, ○: no rusting (5) Thermal degradation method (heat resistance) According to the lubricating oil heat stability test method of JIS K-2540
The performance after a thermal degradation test at 170 ° C. for 48 hours was determined.

Examples 1 to 3 and Comparative Examples 1 to 12 Lubricating oil compositions having the compositions shown in Table 1 were prepared and their performance was evaluated. Table 1 shows the results.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

From Table 1, it can be seen that the lubricating oils of the compositions of Examples 1 to 3 (products of the present invention) have abrasion resistance, anti-emulsifying properties, and rust-preventive properties, and maintain their properties even after a heat deterioration test. It turns out that it is excellent in heat resistance. On the other hand, in the comparative example, clouding occurs, the abrasion resistance is good, but there is a problem that the demulsifying property and the rust prevention property are inferior, and the performance is deteriorated after the heat deterioration test. It can be seen that the product has no commercial value due to poor heat resistance. The notes in the table are as follows. * 1: Hydrogenated refined mineral oil (kinematic viscosity at 40 ° C .: 46 cSt) * 2: Polyoxyethylene (addition of 2 mol) octyl ether * 3: Polyoxypropylene (addition of 3 mol) lauryl ether * 4: Base number: 20 mg KOH / g * 5: 4,4'-methylenebis (2,6-di-t-butylphenol)

[0028]

As described above, the lubricating oil composition of the present invention has excellent heat resistance and abrasion resistance, does not generate sludge even when used in a high-temperature atmosphere, and has anti-emulsifying properties and rust prevention properties. It is excellent. Accordingly, the lubricating oil composition of the present invention can be used as a hydraulic oil for a high-output hydraulic device, for example, a lubricating oil for a hydraulic drive machine such as a construction machine, an injection molding machine, a die-cast machine, and the like. It is suitably used as a lubricating oil for industrial machines having a bearing such as.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10M 137: 04 C10M 137: 10 A 137: 10) C10N 10:04 C10N 10:04 30:00 B 30:00 30:04 30 : 04 30:06 30:06 30:08 30:08 30:12 30:12 40:02 40:02 40:08 40:08 70:00 70:00 (58) Surveyed field (Int.Cl. ⁷ , DB name) C10M 141/10 C10M 129/28 C10M 129/16 C10M 137/02 C10M 137/04 C10M 137/10

Claims (7)

(57) [Claims] (1) Mineral oil, poly-α-olefin, alkylbenzene
Selected from the group of benzene and alkylnaphthalene
Both One of the lubricating base oil, (A) an alkali metal salt 0.01-2% by weight of a carboxylic acid, (B) a polyalkylene glycol monoalkyl ether 0.01 to 5 wt%, and (C)
A lubricating oil composition comprising 0.01 to 2% by weight of at least one phosphorus-containing compound selected from zinc dithiophosphate, a phosphate compound and a phosphite compound. 2. The (A) component is a fatty acid having 4 to 36 carbon atoms.
2. The alkali metal salt of claim 1.
Lubricating oil composition. 3. The lubricating oil composition according to claim 2 , wherein the component (A) is a potassium salt of succinic acid having an alkenyl group having 8 to 18 carbon atoms. 4. The component (B) is an ether of a saturated or unsaturated alcohol having 6 to 22 carbon atoms and a polyethylene glycol having 2 to 12 carbon atoms or a polypropylene glycol having 3 to 18 carbon atoms. The lubricating oil composition according to claim 1. 5. Component (C) is a zinc dialkyldithiophosphate having 3 to 12 carbon atoms, a phosphate compound of a saturated or unsaturated alcohol having 12 to 22 carbon atoms, or a saturated or unsaturated alcohol having 12 to 22 carbon atoms. The lubricating oil composition according to claim 1, which is a phosphite compound of the formula (1). 6. A hydraulic oil comprising the lubricating oil composition according to claim 1. 7. A bearing oil comprising the lubricating oil composition according to claim 1.