JP3229652B2 - 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 having excellent oxidation resistance and abrasion resistance. More specifically, the present invention relates to a lubricating oil composition which exhibits oxidation stability and anti-wear properties over a long period of time, which is useful as a hydraulic fluid for various devices used under high temperature and high pressure conditions.

[0002]

Various proposals have been made to improve the properties of lubricating oil compositions. (i) For example, a lubricating base oil composed of a mineral oil or a synthetic oil having a low aromatic content is used to prevent oxidation of an alkylated phenyl-α-naphthylamine having 12 to 15 carbon atoms derived from an oligomer of propylene as an alkyl group. It is known that it is incorporated as an agent to improve oxidation stability and suppress sludge generation (Japanese Patent Application Laid-Open No. 62-181396). (ii) a lubricating base oil, for example, a solvent refined mineral oil (sulfur content 100 ppm or more, nitrogen content 10 ppm or more, viscosity specific gravity 0.80 or more), as an amine or phenolic antioxidant and an antiwear agent 2. Description of the Related Art Oxidation-resistant and wear-resistant hydraulic fluids, which are compounded with zinc thiophosphate, are known. 1

[0003] However, the conventional lubricating oil composition is unsuitable especially as a hydraulic oil used under high temperature and high pressure conditions. That is, in recent years, the size and speed of hydraulic devices have been reduced, and accordingly, the oil temperature has been increased from the conventional range of 60 to 70 ° C. to around 100 ° C., and the number of cases has increased. I have. For this reason, conventional lubricating oils do not have sufficient thermal oxidation stability, and the oil is oxidized to generate sludge in the oil, which causes problems in hydraulic valves and the like.

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, sludge generated by oxidation of the lubricating oil causes blockage of the hydraulic valve, clogging of the oil tank, reduction in efficiency of the cooler, and the like. On the other hand, as the oxidation reaction proceeds, the characteristics of the lubricating oil rapidly decrease.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to exhibit characteristics which were difficult to achieve with conventional lubricating oils, in particular, excellent thermal oxidation resistance and wear resistance under high temperature and high pressure conditions. It is intended to provide a lubricating oil composition that can be used. The above-mentioned improvement in the properties can be achieved by the present inventors by using a specific amine-based antioxidant (alkylated phenyl-α-naphthylamine) or a phosphite in combination with the same, and It has been found that this can be achieved by the combined use of an agent (a phosphate triester, i.e., a triphosphate and / or a phosphate ester amine salt).

[0006]

SUMMARY OF THE INVENTION In summary of the present invention,
The present invention relates to a lubricating oil composition comprising a mineral oil-based hydrogenated oil , an antioxidant and an antiwear agent, wherein (1) the mineral oil-based hydrogenated oil is analyzed by a ring analysis method (ndM).
C _p , C _N , C _A are C _p 60 or more, C _N 40 or less, C
_A 0 and a total sulfur content of 10 ppm or less,
Consists of mineral water hydrogenated oils are oxygen partial content 1.0ppm or less, (2). The antioxidant, alkylated phenyl -α- naphthylamine or alkylated phenyl -α- naphthylamine and phosphites, in, (3) The lubricating oil composition according to the present invention, wherein the wear inhibitor comprises a phosphate triester and / or a phosphate ester amine salt.

Hereinafter, the technical structure 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, in the presence of a reduced nickel-containing catalyst at a hydrogenation temperature of 200 to 200.
400 ° C., pressure 120-250 kg / cm ² , liquid space velocity (S
V) It is prepared by reacting with hydrogen under the conditions of 0.1 to 2.0 V / V hour. Wherein the mineral water hydrogenated oil is Ru characterized der show the following physical properties. 1. 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, (as measured by ring analysis (n-d-M)) those of C _A 0 Note In the ring analysis method ( ndM ), C _p is the percentage of the number of paraffin carbons to the total number of carbon atoms, C _N is the percentage of the number of carbon atoms of the naphthene ring to the total number of carbon atoms , and C _A is the carbon number of the aromatic ring. It means the percentage of the number to the total carbon number. 2. Total sulfur content (ppm by weight) 100 or less, preferably 10 or less, particularly preferably 1.0 or less. 3. Total nitrogen content (weight ppm) 10 or less, preferably 1.0 or less, particularly preferably 0.2 or less. 4. 4. Residual carbon (% by weight) 0.02 or less, preferably 0.01 or less The aniline point is 100 to 130, preferably 110 to 120. 6. Kinematic viscosity (mm ² / S, 40 ° C.) 2.2 to 1500, preferably 3 to 500.

The synthetic lubricating oil used in the present invention is:
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, polyalkylene glycols, silicone oils and alkylbenzenes.

(Olefin Oligomer) The olefin oligomer used in the present invention usually has 2 to 1 carbon atoms.
4, preferably one obtained by homopolymerization or copolymerization of two or more selected from linear or branched olefinic hydrocarbons in the range of 4 to 12. Olefin oligomers are usually prepared at 100 ° C.
1~130mm ² / S, it is preferably one having a kinematic viscosity of 1.5~25mm ² / S. Its average molecular weight usually ranges from about 100 to 2000, preferably from about 200 to 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 Octene-1 and 25-40% by weight of decene
And a mixture obtained by copolymerizing a mixture consisting of the two. Oligomers obtained from a single monomer such as decene-1 and hydrogenated products thereof are also suitable. ethylene/
As the α-olefin oligomer, for example, 40 to 9
Examples thereof include those obtained by copolymerizing 0% by weight of ethylene and 10 to 60% by weight of propylene.

These olefin oligomers can be produced by using a Friedel-craft type catalyst such as aluminum chloride or boron fluoride, an oxide catalyst such as Ziegler catalyst or chromium oxide, or the like as a catalyst. 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 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 obtained by dehydrating an aliphatic dibasic acid having 4 to 14 carbon atoms and / or an aromatic dibasic acid having 8 carbon atoms with an alcohol having 4 to 14 carbon atoms. It is a diester obtained by condensation.
This diester usually has a kinematic viscosity of ² to 7 mm ² / S at 100 ° C. 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.
Further, phthalic acid and isophthalic acid can be exemplified as the aromatic dibasic acid having 8 carbon atoms.

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

Examples of diesters obtained from these aliphatic dibasic acids or aromatic dibasic acids and alcohols having 4 to 14 carbon atoms include di- (1-ethylpropyl) adipate and 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- [mixture (2
-Ethylhexyl, 2-propylhexyl)] 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, 2-ethylhexyl phthalate, diisononyl phthalate, diisodecyl phthalate, and the like.

These diesters are usually at 100 ° C.
And has a kinematic viscosity of ^{2 to} 7 mm ² / S, preferably 2.2 to ⁶ mm 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- [mixture (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 to 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 to 1,000.

(Silicone Oil) Examples of the silicone oil used in the present invention include organopolysiloxanes represented by the following general formula (1). Si (R) ₃ —O— [Si (R) ₂ —O] _n —Si (R) ₃ (1) wherein R has 1 to 18 carbon atoms and is the same or different, It represents a hydrocarbon group optionally halogenated, and n is an integer of 1 to 3000.) As R, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i -Butyl group, t-butyl group, n
-Alkyl groups such as pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, decyl group, and octadecyl group; aryl groups such as phenyl group and naphthyl group; benzyl group; 1-phenylethyl group; Aralkyl groups such as phenylethyl group, araryl groups such as o-, m- and p-diphenyl groups, o-, m- and p-
Chlorophenyl group, o-, m-, p-bromophenyl group, 3,3,3-trifluoropropyl group, 1,1,
1,3,3,3-hexafluoro-2-propyl group, heptafluoroisopropyl group and heptafluoro-n-
It is a halogenated hydrocarbon group such as a propyl group. In particular, R is preferably a fluorinated hydrocarbon group having 1 to 8 carbon atoms excluding an aliphatic unsaturated group, and a methyl group and a phenyl group are also advantageous. May be used.

(Alkylbenzene) The alkylbenzene used in the present invention has a side chain alkyl group having 10 carbon atoms.
To 25-branched alkylbenzenes, and linear alkylbenzenes having 10 to 25 carbon atoms.

In the present invention, the above-mentioned lubricating base oil components, that is, mineral oil-based hydrogenated oil and 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. (i) -1. Alkylated phenyl-α-naphthylamine component: The alkylated phenyl-α-naphthylamine used in the present invention is represented by the following chemical formula 1. In the present invention
Wherein the alkylated phenyl-α-naphthylamine is
As shown in the following Chemical Formula 1 , hydrogen on a naphthyl ring is an alkyl group.
And may be substituted with a phenyl group .

[0024]

Embedded image (However, R ₁ represents hydrogen or a C _{1 to} C ₁₀ linear or branched alkyl group. R _{2 to} R ₈ may or may not be present, and if they are present, they may be C _{1 to} C _10. A typical compound of this type is octylphenyl-α-naphthylamine, and the like.

(I) -2. Phosphite component In the present invention, the phosphite which may be used in combination with the alkylated phenyl-α-naphthylamine is a tri-alkylated phenyl phosphite represented by the following formula (2). .

[0026]

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

In the present invention, phosphites represented by Chemical Formulas 3 and 4 may be used as the phosphite component.

[0028]

Embedded image (Where R is an alkyl group having 12 to 18 carbon atoms, di-t-
A butylphenyl group and a nonylphenyl group are shown. It preferably represents a di-t-butylphenyl group. )

[0029]

Embedded image (However, R ₁ is an alkyl group having 4 to 30 carbon atoms, R ₂ , R
₃ , R ₄ represents an alkyl group having 1 to ₄ carbon atoms. It preferably represents an alkyl group having 4 carbon atoms. A typical compound of the phosphite component described above is tris-di-t-butylphenyl phosphite.

Next, a description will be given of an antiwear agent system which is a major feature of the present invention. The anti-wear agent used in the present invention is one in which a phosphate triester (triphosphate) and / or a phosphate ester amine salt is essential in connection with the above-described antioxidant system. (ii) -1. Phosphoric acid triester (triphosphate) component: The phosphoric acid triester (triphosphate) used in the present invention is represented by the following chemical formula (5).

[0031]

Embedded image (However, R represents hydrogen, a C _{4 to} C ₁₂ linear or branched alkyl group, or a phenyl group substituted with a C _{1 to} C ₄ alkyl group. X represents an oxygen atom or a sulfur atom.) Some typical compounds are tricresyl phosphate, tributyl phosphate, and the like.

(Ii) -2. Phosphate amine salt component: The phosphate amine salt component used in the present invention is represented by the following general formulas (2) and (3). [HOP (O) (OR) ₂ ] [NH ₂ -R '] (2) [(HO) ₂ P (O) OR] [NH ₂ -R'] ₂ (3) ( Wherein R is a C _{4 to} C ₁₈ linear or branched alkyl group;
Or an alkylene group containing one double bond. R'represents a straight-chain or branched alkyl group or a double bond one alkylene group containing, for C ₄ -C _18. )

In the present invention, the proportions of the antioxidants and antiwear agents used are as follows. (i) The use ratio of the alkylated phenyl-α-naphthylamine constituting the antioxidant in the lubricating oil composition is 0.1%.
0.01 to 10.0% by weight, and preferably 0.01 to 10.0% by weight.
3.0% by weight. When the content is 0.01% by weight or less, the action as a radical scavenger is small, and when the content is 10.0% by weight or more, an antagonistic action is exerted and the antioxidant effect is reduced. The phosphite used in combination is 0.01 to 3.0% by weight,
Preferably, it is 0.1 to 1.0% by weight. When the content is less than 0.01% by weight, the peroxide decomposition action is small, and when the content is more than 3.0, the solubility of the oxidatively degraded product itself is reduced and sludge is formed. (ii) The use ratio of phosphoric acid triester (triphosphate) constituting the antiwear agent in the lubricating oil composition is 0.1%.
1 to 10.0% by weight, preferably 0.1 to 3.
0% by weight. At 0.1% by weight or less, for example, V-1
No effect on wear prevention against 04C vane pump
If the content is 10.0% by weight or more, compatibility with an oil seal such as NBR deteriorates.

In the present invention, the above-mentioned specific antioxidant system and antiwear agent system are essential additives, but other known additives shown below can be blended if desired. (A) Pour point depressant: PMA (polymethacrylate), PIB (polyisobutylene), EPC (ethylene-propylene copolymer), SBC (styrene-butadiene water-added copolymer) and the like. In addition, these are also used from a viewpoint of a viscosity index improver. (B) Rust inhibitor: alkenyl succinic acid or a partial ester thereof, or sarcosine, sorbitan ester and derivatives thereof. (C) Antifoaming agent: dimethylpolysiloxane, polyacrylate, etc. (D) Metal insolubilizing agent: a triazole-based or thiadiazole-based metal insolubilizing agent. (E) Demulsifier: ethylene oxide is 10 to 80% by weight based on propylene oxide, and has an average molecular weight of 1,000.
Alkylene glycols and derivatives thereof, such as up to 15,000 polyoxypropylene copolymers. And the like may be used in appropriate combination.

The lubricating oil composition of the present invention comprising the above-mentioned components exhibits excellent oxidation stability and anti-wear properties especially under high temperature and high pressure conditions. That is, since mineral oil-based hydrogenated oil has few impurities such as aromatic sulfur compounds and aromatic nitrogen compounds, it has a good response with the antioxidant used, and among the antioxidants, especially alkylated naphthylamine is used. It has good compatibility (matching) with these mineral hydrogenated hydrogenated oils and shows an extremely long induction period in an RBOT oxidation test (described later). In addition, in the antiwear agent, the conventional zinc thiophosphate itself tends to be oxidized and decomposed into sludge, whereas the phosphate triester of the present invention has good oxidation stability and is hard to be sludge. .

As described above, the lubricating oil composition of the present invention is used as a lubricating oil for hydraulic equipment in general. It is useful as a hydraulic oil for compression molding machines, punching machines, continuous machinery, and the like.

[0037]

EXAMPLES Hereinafter, 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.

<Preparation of Test Oil> As shown in Tables 1 to 3, test oils were prepared using mineral oil-based lubricating oils, antioxidants, and antiwear agents. In addition,
Each component in Tables 1 to 3 means the following: High-pressure hydrogenated oil: viscosity-specific gravity constant 0.79, sulfur content 1 ppm, nitrogen content 0 ppm, viscosity 46 mm ² / s (40 ° C.) , C _a 0% in n-d-M ring analysis _{method, C n 30%, C P} 70% of paraffinic base oil. Solvent refined oil: Viscosity - gravity constant number 0.81, sulfur content 1100 ppm, the nitrogen content 10 ppm, viscosity ^{46mm 2 / s (40 ℃)} , C A 10% by n-d-M ring analysis method, C _N 20 %, _CP 70% paraffinic base oil. . Alkylated PAN: octylphenyl-α-naphthylamine. Alkylated DPA: dioctylphenylamine. Phenol: 4.4 'methylene-bis-2.6-di-t-butylphenol. Phosphite: Tris-di-t-butylphenyl phosphite. Zinc thiophosphate: Pri-isooctyl zinc thiophosphate.

Evaluation of Test Oils of (Examples 1 to 3 / Comparative Examples 1 to 6) (i) Test of Oxidation Stability (Modified ISOT Method) The oxidation stability of each test oil at a high temperature was examined. Table 1 shows the results
Shown in The oxidation stability was measured by the modified ISOT method.
This is based on the following method. That is, 250 ml of oil
Into a glass beaker, and immersed in oil using an iron plate and a copper plate as a catalyst. Air is blown through the air blower at a rate of 10 l / hr to promote oxidation. Then, the oil is heated to 165.5 ° C., stirred while blowing air in the presence of an iron and copper catalyst, and heated for 96 hours to accelerate the oil and oxidize it at a high temperature. Next, the change in the viscosity and total oxidation of the oil before and after the test, and the amount of sludge (the amount captured by a 0.8 μm filter mg / 100 ml) are measured. In addition,
Ludgee causes filter clogging in service and
Because of the danger of catastrophic failure,
This is an evaluation item that should be considered particularly important as compared with changes in total oxidation.

(Ii) Performance evaluation by the modified ISOT method From Table 1, the following is clear. (1) When an antioxidant (alkylated PAN) and an antiwear agent (tricresyl phosphate) are used in combination with the base oil, the oxidation stability is improved. Further, when phosphite is used in combination, the oxidation stability is significantly improved (Examples 1 to 3 ). (2) Only phosphite as an antioxidant (Comparative Example 1),
The use of alkylated DPA and phosphite (Comparative Example 2) and phenol and phosphite (Comparative Example 3) do not improve the oxidative stability of high pressure hydrogenated oil. (3) In the additive system of Example 2, the antiwear agent was changed from tricresyl phosphate to the same phosphorus antiwear agent dilauryl hydrogen diene phosphite (Comparative Example 4), and to zinc thiophosphate. In each case (Comparative Example 5), the oxidation stability, particularly the sludge generation amount, deteriorated. (4) When the base oil of Example 2 is changed from a high-pressure hydrogenated oil to a conventional solvent refined oil, the oxidation stability is extremely deteriorated (Comparative Example 6). From the above, it can be seen that excellent oxidation stability is exhibited only in the lubricating oil composition comprising the specific base oil component, the specific antioxidant, and the antiwear agent of the present invention.

[0041]

[Table 1]

Evaluation of Test Oils of (Example 2 / Comparative Examples 5 to 7) (i) Preparation of Test Oil Test oils having the compositions shown in Table 2 below were prepared. Examples 2 and Comparative Examples 5 to 6 have the same composition as that described above (Table 1).

(Ii) Test of Oxidation Stability (RBOT Method) The antioxidant ability of each test oil was examined by the RBOT method. Table 2 shows the results. The RBOT method is one of the methods for evaluating the antioxidant ability of a lubricating oil, and has been established by JIS K2514. The evaluation is based on the rotating cylinder type oxidation stability. This RBOT method uses 50 g of lubricating oil and 5 ml of water.
6.3 kg / cm ^{2 in} a closed system containing a copper catalyst.
And oxidize at 150 ° C. Then, a pressure drop occurs due to oxygen absorption, and this is evaluated by measuring a time (induction time: minute) until the pressure drop of a specified amount.

(Iii) Performance evaluation by RBOT method From Table 2, the following is clear. (1) The product of Example 2 exhibits oxidation stability higher than that of Comparative Example 7 (lubricating oil for screw compressors) in which oxidation stability is most important. (2) Those using zinc thiophosphate which is generally used in the prior art as a wear inhibitor (Comparative Example 5)
It is 1/3 or less of the second embodiment. (3) Also, when the base oil is replaced with a conventional solvent refined oil (Comparative Example 6), the life is reduced to ２ or less of the life of Example 2.

[0045]

[Table 2]

Evaluation of Test Oils of Examples 2-3 / Comparative Examples 4, 5, and 8 (i) Preparation of Test Oil Test oils having the compositions shown in Table 3 below were prepared. The composition of Example 2 has the same composition as that described above (Table 1).

(Ii) Abrasion resistance test The abrasion resistance of each test oil was examined by a shell type four-ball abrasion test method. Table 3 shows the results. Shell type four-ball wear test method is a 1/2 inch steel ball, 1200 rpm, 30 kgf, 30
The wear marks of three steel balls after a minute wear test are measured. The smaller the wear mark, the better the wear resistance.

(Iii) Evaluation of abrasion resistance Table 3 shows the following. Specific phosphate triesters (triphosphates) used in the present invention are phosphites or zinc thiophosphates (Comparative Examples 4, 5, and 5) conventionally used as antiwear agents for antiwear lubricants.
It exhibits very good abrasion resistance as compared to 8).

[0049]

[Table 3]

[0050]

The lubricating oil composition comprising the specific lubricating base oil of the present invention and the specific antioxidant and antiwear agent has excellent properties (oxidation resistance, abrasion resistance, especially under high temperature and high pressure conditions). Sex) can be exhibited. Accordingly, the lubricating oil composition of the present invention can be used for hydraulic equipment in which the oil temperature range is shifted to a high temperature side with miniaturization and high speed operation, or for hydraulic equipment used under high temperature and high pressure conditions. It is very useful as an oil.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10M 137: 08 C10M 137: 08 137: 02) 137: 02) C10N 30:06 C10N 30:06 30:10 30:10 40: 08 40:08 (56) References JP-A-3-62894 (JP, A) JP-A 1-275698 (JP, A) JP-A-63-254196 (JP, A) JP-A-59-149995 (JP, A) JP-A-58-109597 (JP, A) JP-A-50-46580 (JP, A) JP-B-49-43542 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB Name) C10M 101/00-101/04 C10M 133/00-133/58 C10M 137/00-137/16 C10N 40:08

Claims (1)

(57) [Claims] 1. A lubricating oil composition comprising a mineral oil-based hydrogenated oil , an antioxidant, and an antiwear agent, wherein (1) the mineral oil-based hydrogenated oil is subjected to a ring analysis method (ndM). Yo
C _p , C _N , C _A are C _p 60 or more, C _N 40 or less, C
_A 0 and a total sulfur content of 10 ppm or less,
Consists of mineral water hydrogenated oils are oxygen partial content 1.0ppm or less, (2). The antioxidant, alkylated phenyl -α- naphthylamine or alkylated phenyl -α- naphthylamine and phosphites, in, (3) The lubricating oil composition, wherein the antiwear agent is composed of a phosphate triester and / or a phosphate ester amine salt.