JP2954744B2 - Lubricating oil composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition having excellent oxidation resistance. More specifically, the present invention relates to a long-term lubricant comprising blending a specific antioxidant (radical scavenger and peroxide decomposer) with a lubricating base oil containing a mineral oil-based hydrogenated oil and / or a synthetic lubricating oil. The present invention relates to a lubricating oil composition having an excellent balance of lubricating oil properties, such as exhibiting oxidative stability and extremely low generation of insoluble sludge.

[0002]

2. Description of the Related Art As is well known, when a mineral or synthetic lubricating base oil is oxidized, a radical reaction proceeds by autoxidation, and alcohols and ketones are generated by a reaction with oxygen. These oxides such as alcohols and ketones are polycondensed to form insoluble sludge in the base oil, which causes a serious obstacle to the lubrication system. That is, the sludge generated by the oxidation of the lubricating oil causes clogging of the oil tank and reduction in the efficiency of the cooler. On the other hand, as the oxidation reaction proceeds, the characteristics of the lubricating oil rapidly decrease. To explain this point more specifically, for example, in a screw type compressor, the lubricating oil cools the rotor and the casing, which have become hot in the compression process, and receives heat, becomes hot, and releases this heat out of the system. However, at this time, since the oxidation reaction is accelerated by the oxidation catalyst reaction of the copper oil cooler, the demand for oxidation stability is extremely high.

Conventionally, an antioxidant is generally added to improve the oxidation stability of a lubricating oil. As this kind of antioxidant, a radical scavenger, a peroxide decomposer and the like are known by their action, and these are used alone or in combination. In addition to these antioxidants, other additives such as a metal deactivator are used to inactivate metal compounds eluted in lubricating oil.
However, at present, no stabilizer has been developed to enhance the oxidation resistance of lubricating oil and to exhibit stable lubricating properties over a long period of time.

[0004]

The present invention uses a mineral oil-based hydrogenated oil and / or a synthetic lubricating oil as a lubricating base oil, and uses a specific amine-based antioxidant as a radical scavenger, and The combination of a specific phosphite as a peroxide decomposer and a specific phenolic antioxidant further improves long-term oxidation resistance and minimizes the amount of sludge generated. An object of the present invention is to provide a lubricating oil composition having an excellent balance of oil properties.

[0005]

SUMMARY OF THE INVENTION In summary of the present invention,
The present invention includes a mineral oil-based hydrogenated oil and / or a synthetic lubricating oil as a lubricating base oil component, and the following antioxidants,
That is, (1) (i) alkylated phenylamine-α-alkylated naphthylamine, (ii) alkylated diphenylamine, (ii)
(i) phosphite, an antioxidant consisting of three types, or (2) (i) alkylated phenylamine-α-alkylated naphthylamine, (ii) alkylated diphenylamine, (ii)
i) a hindered phenol having an average molecular weight of 400 to 700,
v) A lubricating oil composition comprising four types of antioxidants, phosphites.

Hereinafter, the configuration of the present invention will be described in detail. The base oil component constituting the lubricating oil composition of the present invention is not particularly limited as long as it contains a mineral oil-based hydrogenated oil and / or a synthetic lubricating oil.

The mineral oil-based hydrogenated oil used in the present invention is, for example, a hydrogenated oil having a hydrogenation temperature of 20 in the presence of a reduced nickel-containing catalyst.
0 to 400 ° C, pressure 120 to 250 kg / cm ² , liquid hourly space velocity (SV)
It is prepared by reacting with hydrogen under the condition of 1 to 2.0 V / V. The aforementioned mineral oil-based hydrogenated oil is characterized by exhibiting the following physical property values; Type C _P 60 or more hydrocarbons, C _N 40 or less, C _A 0, preferably C _P 70 or more, C _N 30 or less, that of C _A 0 (ring analysis (n-d-
M)) 2. 2. Total sulfur content (weight ppm) 10 or less, preferably 1.0 or less 3. Total nitrogen content (weight ppm) 1.0 or less, preferably 0.2 or less 4. Residual carbon (% by weight) 0.02 or less, preferably 0.01 or less 5. Aniline point of 100 to 130, preferably 110 to 120 Kinematic viscosity (mm ² / S, 40 ° C) 2.2 to 1500, preferably 3 to 500

The synthetic lubricating oil used in the present invention comprises:
Among the physical properties of the mineral oil-based hydrogenated oil, other physical properties are satisfied except for the aniline point. Such synthetic lubricating oils include olefin oligomers, polybutenes,
There are synthetic oils such as diesters, polyol esters, and polyalkylene glycols.

(Olefin oligomer) The olefin oligomer used in the present invention usually has 2 to 1 carbon atoms.
4. Preferably obtained by homopolymerization or copolymerization of two or more arbitrary ones selected from linear or branched olefinic hydrocarbons in the range of 4 to 12. Olefin oligomers are usually prepared at 100 ° C for 1 to 1
130 mm ² / S, is preferably one having a kinematic viscosity of 1.5~25mm ² / S. Its average molecular weight is usually about 100-200
0, preferably in the range of about 200-1000. The olefin oligomer used in the present invention is particularly preferably an olefin oligomer in which unsaturated bonds are saturated by hydrogenation.

As the olefin oligomer, for example,
α-olefin oligomers, ethylene / α-olefin oligomers and the like. As the α-olefin oligomer, a mixture of α-olefins having 6 to 12 carbon atoms obtained by trimerization of hydrocarbons or lower olefins, for example, 25 to 50% by weight of hexene-1, 30 to 40% by weight Of octene-1 and 25-40% by weight of decene-1. Decene-1
Oligomers obtained from a single monomer and hydrogenated products thereof are also suitable. Examples of the ethylene / α-olefin oligomer include those obtained by copolymerizing 40 to 90% by weight of ethylene and 10 to 60% by weight of propylene.

These olefin oligomers can be produced using a catalyst such as a Friedel-Crafts catalyst such as aluminum chloride or boron fluoride, an oxide catalyst such as a Ziegler catalyst or chromium oxide, or the like. The hydrogenation of the olefin oligomer is carried out by removing the catalyst from the polymerization reaction product, and then contacting the olefin oligomer with hydrogen under heating and pressure, for example, in the presence of a hydrogenation catalyst such as nickel-molybdenum / alumina. be able to.

(Polybutene) The polybutene (polyisobutylene) used in the present invention is one kind of an α-olefin oligomer and is usually prepared by polymerizing a starting material mainly composed of isobutylene with aluminum chloride as a catalyst, It may be used as it is or may be used after hydrogenation.

(Diester) The diester used in the present invention is an aliphatic dibasic acid having 4 to 14 carbon atoms and 4 to 14 carbon atoms.
A diester obtained by dehydration condensation with an alcohol of No. This diester is usually 2 to 7 at 100 ° C.
It has a kinematic viscosity of mm ² / S. Examples of the aliphatic dibasic acid having 4 to 14 carbon atoms include succinic acid, glutaric acid, adipic acid, piperic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, bradylic acid, and Tetradecandioic acid and the like can be mentioned. Among these, adipic acid, azelaic acid and sebacic acid are preferred, and adipic acid and sebacic acid are particularly preferred.

Examples of the alcohol having 4 to 14 carbon atoms include n-butanol, isobutanol, n-aluminum alcohol, isoaluminoalcohol, n-hexanol,
-Ethylbutanol, cyclohexanol, n-heptanol, isohebutanol, methylcyclohexanol, n-octanol, dimethylhexanol, 2-ethylhexanol, 2,4,4-trimethylpentanol, isooctanol, 3,5,5-trimethyl Hexanol, isononanol, isodecanol, isoundecanol, 2-butyloctanol, tridecanol, isotetradecanol and the like can be mentioned.
Among these, 2-ethylhexanol and isodecanol are particularly preferred.

The diesters obtained from these aliphatic dibasic acids and alcohols having 4 to 14 carbon atoms include, for example,
Di- (1-ethylpropyl) adipate, di- (3-methylbutyl) adipate, di- (1,3-methylbutyl) adipate, di- (2-ethylhexyl) adipate, di- (isononyl) adipate, di- (isodecyl) ) Adipate, di- (undecyl) adipate, di-
(Tridecyl) adipate, di- (isotetradecyl)
Adipate, di- (2,2,4-trimethylbentyl)
Adipate, di- [mixed (2-ethylhexyl, isononyl)] adipate, di- (1-ethylpropyl) azelate, di- (3-methylbutyl) azelate, di-
(2-ethylbutyl) azelate, di- (2-ethylhexyl) azelate, di- (isooctyl) azelate, di- (isononyl) azelate, di- (isodecyl) azelate, di- (tridecyl) azelate, di-
[Mixed (2-ethylhexyl, isononyl)] azelate, di- [mixed (2-ethylhexyl, decyl)] azelate, di- [mixed (2-ethylhexyl, isodecyl)] azelate, di- [mixed (2-ethylhexyl,
2-propylhebutyl)] azelate, di- (n-butyl) sebacate, di- (isobutyl) sebacate, di-
(1-ethylpropyl) sebacate, di- (1,3-methylbutyl) sebacate, di- (2-methylbutyl) sebacate, di- (2-ethylhexyl) sebacate, di- [2- (2-ethylbutoxy) ethyl] Sebacate,
Di- (2,2,4-trimethylbenzyl) sebacate,
Di- (isononyl) sebacate, di- (isodecyl) sebacate, di- (isoundecyl) sebacate, di-
(Tridecyl) sebacate, di- (isotetradecyl)
Sebacate, di- [mixed (2-ethylhexyl, isononyl)] sebacate, di- (2-ethylhexyl) glutarate, di- (isoundecyl) glutarate, di- (isotetradecyl) glutarate and the like can be mentioned.

These diesters are usually prepared at 100 ° C.
2 to 7 mm ² / S, preferably having a kinematic viscosity of 2.2 ~6mm ² / S. If the kinematic viscosity is too low, there are problems in flammability, volatilization resistance, and load resistance. If it is too high, the viscosity at low temperatures increases, and the low-temperature fluidity is impaired.

(Polyol Ester) The polyol ester used in the present invention is prepared by synthesizing a neopentyl polyol having 5 to 9 carbon atoms and an organic acid having 4 to 18 carbon atoms. In the present invention, neopentyl polyol is a polyhydric alcohol having a neopentyl group, for example, 2,2-dimethylpropane-1,3-diol (that is, neopentyl glycol), 2-ethyl-2. -Butyl-propane-1,3-diol, 2,2-diethylpropane-1,3-diol, 2,2-dibutylpropane-1,3-diol, 2-methyl-2-propylpropane-1,3-diol Diol, 2-ethyl-2-butylpropane-1,3-diol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, preferably neopentyl glycol,
Methyl-2-propylpropane-1,3-diol, trimethylolpropane, pentaerythritol,
Particularly preferred are neopentyl glycol, trimethylolpropane, and pentaerythritol. Organic acids include, for example, n-butanoic acid, isoptanic acid, n-pentanoic acid, isopentanoic acid, n-hexanoic acid, 2-ethylbutanoic acid, cyclohexanoic acid, n-heptanoic acid, isoheptanoic acid, methylcyclohexanoic acid, n-octane Acid, dimethylhexanoic acid, 2-ethylhexanoic acid, 2,4,4
-Trimethylpentanoic acid, isooctanoic acid, 3,5,5
-Trimethylhexanoic acid, n-nonanoic acid, isononanoic acid, isodecanoic acid, isoundecanoic acid, 2-butyloctanoic acid, tridecanoic acid, tetradecanoic acid, hexadecanoic acid and octadecanoic acid, preferably heptanoic acid,
n-octanoic acid and 2-ethylhexanoic acid. The synthesis of neopentyl polyol ester from neopentyl polyol and an organic acid can be performed by a conventional method, for example, a method of dehydration-condensation under an acidic catalyst. For example, as neopentyl polyol ester (hereinafter, neopentyl is NPG, trimethylolpropane is TMP,
Pentaerythritol is abbreviated as PE. ), NPG
Di- (heptanoate), NPG di- (2-ethylbutyrate), NPG di- (cyclohexanoate),
NPG di- (heptanoate), NPG di- (isoheptanoate), NPG di- (octylate), N
PG di- (2-ethylhexanoate), NPG di- (isooctanoate), NPG di- (isononylate), NPG di- (isodecanoate), NPG
Di- [mixed (hexanoate, heptanoate)], N
PG di- [mixed (hexanoate, octanoate)], NPG di- [mixed (hexanoate, nonylate)], NPG di- [mixed (heptanoate, octanoate)], NPG di- [mixed (heptanoate, nonylate) ], NPG di- [mixed (heptanoate, isooctanoate)], NPG di- [mixed (heptanoate, isononylate)], NPG di-
[Mixed (isooctanoate, isononylate)], N
PG di- [mixed (ptanoate, tridecanoate)], NPG di- [mixed (ptanoate, tetradecanoate)], NPG di- [mixed (ptanoate,
Octadecanoate)], NPG di- [mixture (hexanoate, isooctanoate, isononylate)],
NPG di- [mixed (hexanoate, isooctanoate, isodecanoate)], NPG di- [mixed (heptanoate, isooctanoate, isononylate)], NPG di- [mixed (heptanoate, isooctanoate, Isonodecanoate)], NPG di-
[Mixed (octanoate, isononylate, isonodecanoate)], TMP tri- (pentanoate), TMP
MP tri- (hexanoate), TMP tri- (heptanoate), TMP tri- (octanoate),
TMP tri (nonylate), TMP tri (isopentanoate), TMP tri (2-ethylbutyrate), TMP tri (isooctanoate), TM
P-tri- (2-ethylhexanoate), TMP-tri- (isononylate), TMP-tri- (isodecanoate), TMP-tri- [mixed (butyrate, octadecanoate)], TMP-tri- [ Mixing (hexanoate, hexadecanoate)], TMP tri- [mixing (heptanoate, tridecanoate)], TMP tri- [mixing (octanoate, decanoate)], TM
P. tri- [mixed (octanoate, nonylate)],
TMP tri- [mixture (butyrate, heptanoate,
Octadecanoate)], TMP tri- [mixture (pentanoate, heptanoate, tridecanoate)],
TMP tri- [mixed (hexanoate, heptanoate, octanoate)], PE tetra (pentanoate), PE tetra (hexanoate), PE tetra (isopentanoate), PE tetra (2-ethyl butyrate) ), PE • tetra (isoheptanoate), PE • tetra (isooctanoate), PE • tetra (2-ethylhexanoate), PE • tetra (isononylate), and PE and tetracarbon having 4-8 carbon atoms Esters with a mixture of chain or branched carboxylic acids. Also, N
Neopentyl polyol other than PG, TMP and PE,
That is, examples thereof include polyol esters of 2-methyl-2-propylpropane-1,3-diol, 2,2-diethylpropanediol, trimethylolethane, and trimethylolhexane with the above-described organic acids alone or as a mixture.

(Polyalkylene Glycol) The polyalkylene glycol used in the present invention is a ring-opened polymer of a linear or branched alkylene oxide having an alkylene group having 2 to 5, preferably 2 to 3, carbon atoms. It is a ring-opening copolymer. As the alkylene oxide, ethylene oxide, propylene oxide, butylene oxide, or a mixture thereof is preferable. Preferable examples include polyethylene glycol and polypropylene glycol, and those having a molecular weight range of 100 to 2,000, preferably
200-1000.

In the present invention, the aforementioned lubricating base oil components, that is, the mineral oil-based hydrogenated oil and the synthetic lubricating oil, can be used alone or in combination. For example, one or more mineral oil-based hydrogenated oils may be used, one or more synthetic lubricating oils may be used, or one or more mineral oil-based hydrogenated oils and one or more synthetic lubricating oils may be used. Species or more may be used in combination.

Next, the antioxidant system which is a major feature of the present invention will be described. The antioxidant used in the present invention is specified in relation to required characteristics or target characteristics for a lubricating oil as follows.

(1) RBOT (minute) characteristics One of the methods for evaluating the antioxidant performance of a lubricating oil, JI
The evaluation is made based on the oxidation stability of a rotary cylinder type established by SK2514. This is 50g of lubricating oil and 5ml of water
And oxygen is injected into the closed system containing the copper catalyst to 6.3 kg / cm ² and oxidized at 150 ° C. Then, a pressure drop is caused by oxygen absorption. This is measured and evaluated by measuring a time (induction time; minute) until the pressure drop of a specified amount. In general,
Lubricating oils having a high RBOT value are used as compressor oils under severe environmental conditions, but commercially available compressor oils include mineral oil-based or synthetic oil-based oils.
The value is about 2000 minutes, and something better than this must be developed.

(2) Thermal stability This is carried out according to the test method specified in JIS K2520.
This is to evaluate the tendency of sludge generation due to oxidation.
A lubricating oil with a long sludge generation time must be developed.

(3) Residual carbon content (POT, CCR%) characteristics This is a characteristic determined by an experiment that correlates with the amount of carbon generated particularly at the piston portion of the reciprocating compressor. As an experimental method, the PNEUROP Oxidation Test (POT) specified in DIN 51352 is known.
This is a method of evaluating the tendency of carbon formation in a laboratory. The experimental method of the below-described example of the present invention uses a test oil of 40 ml.
Oil temperature is increased by blowing 15 l / h air in the presence of 0.4 g of iron oxide.
Oxidized oil at 200 ° C for 24 hours, carbon residue (CCR) of oxidized oil
Was measured and defined as POT (CCR%). This POT (C
(CR%) value must be developed as low as possible. It should be noted that a large POT (CCR%) value is likely to cause a fire or explosion accident of the lubricating equipment.

(4) RBOT maintenance rate A catalyst of a copper plate and an iron plate is immersed in 250 ml of lubricating oil, and air is blown for 10 minutes.
l / hr and stirred at 165.5 ° C for 96 hours (MI
SOT). After the M-ISOT (after the oxidation test), the RBOT retention rate (%) is determined by the following equation. [M
-RBOT of used oil after ISOT (minutes) / [RBOT of new oil
(Min)] · 100 (%) This is a scale for evaluating the oxidation life performance of the lubricating oil, and the higher the RBOT retention ratio, the better the lubricating oil.

In connection with the above-mentioned properties, the antioxidant system of the present invention comprises the above-mentioned composite system, that is, (1) (i)-(iii) or
(2) It is composed of those specified in (i) to (iV). Hereinafter, the composite oxidation stabilizer of the present invention will be described more specifically.

(1) (i) Alkylated phenyl-α-alkylated naphthylamine component: The alkylated phenyl-α-alkylated naphthylamine used in the present invention is represented by the following formula 1.

[0027]

Embedded image (However, R ₁ represents an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 4 to 8 carbon atoms. R _{2 to} R ₈ may or may not be present. A typical compound of this type is octylphenyl-α-naphthylamine.

(1) (ii) Alkylated diphenylamine component: The alkylated diphenylamine used in the present invention is represented by the following chemical formula 2.

[0029]

Embedded image (However, R ₁ and R ₂ are each H or carbon number 1 to
Indicate 18 alkyl groups. It preferably represents an alkyl group having 4 to 8 carbon atoms. A typical compound of this type is octyldiphenylamine.

(1) (iii) Phosphite component: The phosphite used in the present invention is represented by the following chemical formula (3), (4) or (5).

[0031]

Embedded image (However, R ₁ and R ₂ are H or an alkyl group of C _{4 to} C ₁₂ , preferably a t-butyl group.)

[0032]

Embedded image (However, R represents an alkyl group having 12 to 18 carbon atoms, a di-t-butylphenyl group, or a nonylphenyl group, preferably a di-t-butylphenyl group.)

[0033]

Embedded image (However, R ₁ is an alkyl group having 4 to 30 carbon atoms, R ₂ ,
R ₃ and R ₄ each represent an alkyl group having 1 to ₄ carbon atoms. It preferably represents an alkyl group having 4 carbon atoms. ) A typical compound of this type is tris-di-t-butylphenyl phosphite.

(2) (iii) Hindered phenol component having an average molecular weight of 400 to 700: In the present invention, among various hindered phenol compounds, the average (weight) molecular weight is 400 as shown in Examples described later. ~ 700 are preferred. Particularly preferably, it has a molecular weight of 550 to 700. This kind of hindered phenol is a single compound represented by the following chemical formula (6).

[0035]

Embedded image (However, R ₁ and R ₂ represent H or a t-Bu group, and R ₃ represents a methylene group having 1 to 5 carbon atoms.)

In the present invention, the average amount is 400
If it is ~ 700, for example, a combination of a plurality of hindered phenols represented by the following chemical formulas 7, 8 and 9 may be used.

[0037]

Embedded image

[0038]

Embedded image

[0039]

Embedded image (However, in Chemical Formula 7, Chemical Formula 8, and Chemical Formula 9, n is an integer of 1 to 4, and R ₁ and R _{2 each} represent H or a t-Bu group.)

In the present invention, the above-mentioned alkylated phenyl-α-alkylated naphthylamine and alkylated diphenylamine as the amine-based antioxidant, the hindered phenol having an average molecular weight of 400 to 700 as the phenolic antioxidant, and the peroxide The compounding ratio of the phosphite as a substance decomposing agent to the base oil is 0.1 to 2.0% by weight, 0.1 to 2.0% by weight, 0.1 to 0.5% by weight, and 0.1 to 0.2% by weight, respectively.
5% by weight, and a sufficient effect can be obtained under this use ratio. That is, under the use ratio described above,
Balanced RBOT (minute) characteristics, thermal stability, PO
The T (CCR%) characteristic and the RBOT maintenance rate are secured.

In the present invention, the above (1) (i) to (iii)
The oxidation stabilizer consisting of the components (2), (i) to (iv) is essential, but if necessary, a known oxidation stabilizer or other additives can be blended. Examples of the above-mentioned additives include (a) pour point depressants: PMA (polymethacrylate), PIB (polyisobutylene), EPC (ethylene-propylene copolymer), SBC (styrene-butadiene water-added copolymer), etc. . (B) Antifoaming agent: dimethylpolysiloxane, polyacrylate, etc. (C) Metal insolubilizing agent: a triazole-based or thiadiazole-based metal insolubilizing agent. (D) Demulsifier: ethylene oxide is 10 to 80% by weight based on propylene oxide, and the average molecular weight is 1,000 to 1
5,000 polyoxypropylene copolymers, etc. (E) Rust inhibitor: alkenyl succinic acid or a partial ester thereof. And the like may be used in appropriate combination.

As described above, since the lubricating oil composition of the present invention has excellent antioxidant properties at high temperatures, it can be used to lubricate a lubricating system having a large operating load, such as compressor oil, turbine oil and hydraulic oil. Suitable for oil.

(Examples) Next, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples.

(Examples 1 and 2 / Comparative Examples 1 to 4) Example 1
Uses a mineral oil-based hydrogenated base oil having a viscosity of 32 mm ² / S at 40 ° C, a sulfur content of 1.0 ppm, and a nitrogen content of 0.2 ppm, and the antioxidant shown in Table 1 below And additives are blended into a lubricating oil composition. Example 2
Uses a poly-α-olefin having a viscosity of 32 mm ² / S at 40 ° C., a sulfur content of 1 ppm or less and a nitrogen content of 1 ppm or less,
The lubricating oil composition was prepared by blending the same additives as in Example 1. Next, various performance evaluations were performed. The results are shown in Table 1. As a comparative example, performance of a commercially available compressor oil was also evaluated. The results are shown in Table 1. In Table 1 below, the alkylated PAN is represented by the formula: R = C ₈ H ₁₇ ,
That is, it represents octylphenyl-α-naphthylamine. The alkylated DPA is obtained by converting R ₁ , R ₂ ＣC
₈ H ₁₇ , that is, octyldiphenylamine. Additive pour point depressant (a) is polymethacrylate, metal deactivator (b) is methylbenzotriazole derivative,
Rust inhibitor (c) is alkenyl succinate, demulsifier
(d) shows a polyoxyethylene polyoxypropylene copolymer. Table 1 shows that the mineral oil-based hydrogenated oil and synthetic oil (poly-
Examples 1 and 2 consisting of an α-olefin oligomer) and a complex antioxidant were obtained from commercially available compressor oils (mineral oil,
(Synthetic oil).

[0045]

[Table 1]

(Examples 3 to 4 / Comparative Examples 5 to 9) The effect of using a phenolic compound as a component of a composite antioxidant was examined. In this example, a predetermined target characteristic value was set based on the required needs of the lubricating oil characteristics, and the optimum composite antioxidant was examined. Table 2 below shows the prepared lubricating oil compositions and the results of the performance evaluations. In Table 2, phenol (M
W 420) is represented by the following formula: R ₁ = R ₂ = t-Bu
The group, R _3, is that of CH ₂ . Phenol (MW 56
The compound of the formula (5) is represented by the formulas (7), (8) and (9), where n = 4 and R ₁
= R ₂ = t-Bu group, 36% of the compound of formula 7, and 8
Are 31% and those of formula 9 are 33%.
In addition, those having MW = 220 are represented by the following chemical formula 10, and those having MW = 1178 are represented by the following chemical formula 11;

[0047]

Embedded image

[0048]

Embedded image

From Table 2, it can be seen that the lubricating oil composition of the present invention is a well-balanced lubricating oil satisfying all the required characteristics (target values).

[0050]

[Table 2]

[0051]

The lubricating oil composition of the present invention is based on a mineral oil-based hydrogenated oil and / or a synthetic lubricating oil as a base oil component, to which a specific amine-based antioxidant and a phosphite, or a more specific It is prepared by blending a hindered phenol having an average molecular weight, and can maintain a wide range of lubricating properties over a long period of time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 137: 04 129: 10) C10N 30:10 40:08 40:12 (72) Inventor Hirotaka Tomizawa Niizuru, Oimachi, Iruma-gun, Saitama 1-3-1 Kaoka Inside Tonen Research Laboratory (56) References JP-A-62-89796 (JP, A) JP-A-54-91502 (JP, A) (58) Fields investigated (Int. . ^6, DB name) C10M 169/04 C10M 101/02 C10M 105/04 C10M 133/12 C10M 137/04 C10M 129/10 C10N 30:10 C10N 40:08 C10N 40:12 WPI / L (QUESTEL)

Claims (4)

(57) [Claims] 1. A lubricating oil composition comprising a lubricating base oil containing a mineral oil-based hydrogenated oil and / or a synthetic lubricating oil and an antioxidant, wherein the antioxidant comprises: (i) an alkylated phenyl-α- A lubricating oil composition comprising an alkylated naphthylamine, (ii) an alkylated diphenylamine, and (iii) a phosphite. 2. An antioxidant comprising: (i) an alkylated phenyl-α-alkylated naphthylamine, (ii) an alkylated diphenylamine, (iii) a hindered phenol having an average molecular weight of 400 to 700, and (iv) a phosphite. A lubricating oil composition comprising four types. 3. The compounding amount of the antioxidant to the lubricating base oil is as follows: (i) alkylated phenyl-α-alkylated naphthylamine: 0.1 to 2.0% by weight (ii) alkylated diphenylamine: 0.1 to 2.0% by weight (iii) The lubricating oil composition according to claim 1, wherein the content is 0.1 to 0.5% by weight. 4. The compounding amount of the antioxidant to the lubricating base oil is as follows: (i) 0.1 to 2.0% by weight of alkylated phenyl-α-alkylated naphthylamine (ii) 0.1 to 2.0% by weight of alkylated diphenylamine The lubricating oil composition according to claim 2, wherein (iii) hindered phenol is 0.1 to 0.5% by weight (iv) phosphite is 0.1 to 0.5% by weight.