JPH09125080A - Heat-resistant lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in such heat resistance, oxidation resistance, abrasion resistance and the physical properties as a lubricating oil as to stand use under high-temperature conditions, thus useful in, e.g. turbo engines, comprising each specific ester and polyphenyl thioether at specified proportions. SOLUTION: This lubricating oil composition comprises (A) 10-90wt.% of an ester of a 5-30C hindered alcohol and a 4-20C fatty acid [e.g. neopentyl glycol di(n-butanoate)] and (B) 90-10wt.% of a polyphenyl thioether of formula I (R<1> to R<3> are each H or a 1-24C hydrocarbon; (x), (y) and (z) are each 1-4; (n) is 1-3) such as a compound of formula II [e.g. m-bis(phenylmercapto)benzene].

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-resistant lubricating oil composition, and more particularly to a heat-resistant lubricating oil composition comprising a mixture of a hindered alcohol and a fatty acid ester and polyphenyl thioether. It is a thing.

[0002]

2. Description of the Related Art In recent years, as the performance and efficiency of machinery and power equipment have improved, there has been a demand for a lubricating oil having a high quality capable of withstanding a severe environment of use. For example, jet engines, gas turbines, turbo engines, and the like are operated at high temperatures, so that lubricating oils used in these engines are required to have particularly excellent heat resistance and oxidation resistance.

Therefore, for example, an ester of pentaerythritol or trimethylolpropane and a monocarboxylic acid has been proposed as a base oil of a lubricating oil for jet engines to be used under high temperature conditions (for example, JP-A-50). No. 18860, U.S. Pat. No. 4,32,018, etc.). It has also been proposed to use a hindered ester of a fatty acid mixture having a specified fatty acid structure and a hindered alcohol as a lubricating base oil (see, for example, Japanese Patent Laid-Open No. Hei 6).
-158079 gazette).

However, although the above-mentioned ester of hindered alcohol and fatty acid has excellent heat resistance and oxidation resistance, it does not have sufficient wear resistance when used under high temperature conditions, so that sliding in the engine It becomes necessary to suppress an increase in wear loss of the surface. In particular, as described below, 230
There is a situation in which it is difficult to provide a lubricating oil which has corrosion resistance stability test for 72 hours at 0 ° C. and which is resistant to abrasion and which has abrasion resistance.

Therefore, conventionally, there has been earnestly desired to develop a heat-resistant lubricating oil which is excellent in heat resistance and oxidation resistance under severe high temperature conditions and also in abrasion resistance and can be used in various industrial fields.

[0006]

In view of the development status of heat-resistant lubricating oil as described above, the object of the present invention is to achieve the severe operating conditions, especially high temperature conditions, which are difficult to achieve with conventional lubricating base oils. An object of the present invention is to provide a heat-resistant lubricating oil composition having high heat resistance, oxidation resistance, and wear resistance that can withstand use and having a high practical value.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies to solve the above problems, a lubricating oil composition comprising a mixture of a hindered ester obtained from a hindered alcohol and a fatty acid and a polyphenylthioether having 3 to 5 aromatic rings Has excellent heat resistance that cannot be exhibited independently under high temperature conditions.
Focusing on the fact that they have oxidation resistance and wear resistance, they have found that they can solve the above problems and have reached the present invention.

Thus, according to the present invention, (a) an ester of a hindered alcohol having 5 to 30 carbon atoms and a fatty acid having 4 to 20 carbon atoms and (b) the following general formula [I]:

[0009]

Embedded image (In the above general formula [I], R ¹ , R ² and R ³
May be the same or different from each other, each is a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, and x, y and z may be the same or different from each other. They may be different, each is an integer of 1 to 4, and m is an integer of 1 to 3. And a polyphenyl thioether represented by the formula (1).

Further, according to the present invention, there is provided a heat resistant lubricating oil according to the following preferred embodiments. The heat resistant lubricating oil composition as described above, wherein the hindered alcohol is selected from pentaerythritol, dipentaerythritol or tripentaerythritol. Any of the above-mentioned heat-resistant lubricating oil compositions, wherein the fatty acid is a linear or branched fatty acid having 4 to 12 carbon atoms and is at least one selected from the group of saturated fatty acids. Any of the above-mentioned heat-resistant lubricating oil compositions, wherein the hydrocarbon group in the fatty acid portion of the hindered ester has an average carbon number of 3 to 8. The polyphenyl thioether represented by the general formula [I] is m-bis (phenylmercapto) benzene (m-
3P2T), bis (m-phenylmercaptophenyl)
Sulfide (m, m-4P3T) and m-bis (m
-Phenylmercaptophenylmercapto) benzene (m, m, m-5P4T), which is at least one selected from the group consisting of the above heat-resistant lubricating oil compositions. Ester 2 of the hindered alcohol and fatty acid
0% to 80% by weight and polyphenyl thioether 80
A heat resistant lubricating oil composition comprising a mixture of 20% by weight and 20% by weight.

One of the peculiarities of the present invention is as follows. That is, although both the ester of hindered alcohol and fatty acid and the polyphenyl thioether are inferior in abrasion resistance alone, they are mixed to improve heat resistance and oxidation resistance and abrasion resistance. It is a point that it can provide a lubricating oil composition.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Hindered Ester The hindered ester as one of the components of the heat resistant lubricating oil composition of the present invention is an ester of a hindered alcohol and a fatty acid. The hindered alcohol is a polyhydric alcohol having a neopentyl group containing a quaternary carbon atom in its molecule, and according to the present invention, one having 5 to 30 carbon atoms is used. Specific examples of the hindered alcohol include neopentyl glycol, 2,2-diethylpropane-1,3diol, 2,2-dibutylpropane-1,
3 diol, 2-methyl-2-propylpropane-1,
3 diol, 2-ethyl-2-butylpropane-1,3
Examples thereof include diol, trimethylolethane, trimethylolpropane, ditrimethylolpropane, tritrimethylolpropane, tetratrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, tetrapentaerythritol, pentapentaerythritol, and one or two of them. More than one seed is used. Preferred hindered alcohols have 5 to 20 carbon atoms, and particularly preferably 1 carbon atom.
A high-viscosity hindered alcohol such as dipentaerythritol or tripentaerythritol is used as it is 0 or more.

As the fatty acid, a linear or branched fatty acid having 4 to 20 carbon atoms is used. Examples of linear fatty acids include n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n. -Dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, n-pentadecanoic acid, n-hexadecanoic acid, n-heptadecanoic acid, n-octadecanoic acid, etc. may be used, and one or more of them may be used. Further, as the branched fatty acid,
For example, 2-methylpropanoic acid, 2-methylbutanoic acid,
3-methylbutanoic acid, 2,2-dimethylpropanoic acid, 2
-Ethylbutanoic acid, 2,2-dimethylbutanoic acid, 2,3
-Dimethylbutanoic acid, 2-ethylpentanoic acid, 2,2-
Dimethylpentanoic acid, 2-ethyl-2-methylbutanoic acid, 3-methylhexanoic acid, 2-methylheptanoic acid, 2
-Ethylhexanoic acid, 2-propylpentanoic acid, 2,2
-Dimethylhexanoic acid, 2-ethyl-2-methylpentanoic acid, 2-methyloctanoic acid, 2,2-dimethylheptanoic acid, 2-ethylheptanoic acid, 2-methylnonanoic acid,
2,2-dimethyloctanoic acid, 2-ethyloctanoic acid,
In addition to 2-methylnonanoic acid and 2,2-dimethylnonanoic acid, branched fatty acids having 11 or more carbon atoms can be mentioned, and one or more of them can be used. Preferred fatty acids have 4 to 12 carbon atoms, and particularly preferably 5 to 9 carbon atoms. The fatty acid as described above has an average number of carbon atoms of the hydrocarbon group of the fatty acid portion of the hindered ester of 3 to 8,
It is possible to use n-propanoic acid having less than 4 carbon atoms, for example, n-propanoic acid, or a mixture of fatty acids having 12 or more carbon atoms.

The above-mentioned hindered ester is produced by a conventional method, for example, (a) a method in which a hindered alcohol and a fatty acid are directly esterified by dehydration condensation in the presence of a catalyst or an acidic catalyst, ( b) a method of preparing a fatty acid chloride and reacting it with a hindered alcohol, and (c) a method of producing by a transesterification reaction of an ester of a lower alcohol with a fatty acid and a hindered alcohol, or the like. it can.

Specific examples of the hindered ester are as follows (hereinafter, neopentyl glycol is referred to as NP).
G, trimethylolpropane TMP, ditrimethylolpropane DTMP, pentaerythritol PE,
Dipentaerythritol is abbreviated as DPE and tripentaerythritol is abbreviated as TPE. ).

That is, NPG.di (n-butanoate), NPG.di (2-methylpropanoate), NP
G • di (n-pentanoate), NPG • di (2-methylbutanoate), NPG • di (n-hexanoate), NPG • di (2-ethylbutanoate), NPG
-Di (3-ethylbutanoate), NPG.di (n-heptanoate), NPG.di (2-ethylpentanoate), NPG.di (n-octanoate), NPG.di (n-nonanoate), NPG / di (isononate),
NPG.di (n-decanoate), NPG.di (isodecanoate) NPG.di [mixed (n-hexanoate,
n-butanoate)], NPG.di [mixed (n-hexanoate, n-pentanoate)], NPG.di [mixed (n-butanoate, n-heptanoate)], TMP
-Tri (n-butanoate), TMP-tri (2-methylpropanoate), TMP-tri (n-pentanoate), TMP-tri (n-hexanoate), TMP-
Tri (n-heptanoate), TMP.tri (2-ethylpentanoate), TMP.tri (n-octanoate), TMP.tri (2ethylhexanoate), TM
P.tri (n-nonanoate), TMP.tri (isononanate), TMP.tri (n-decanoate), TMP
-Tri (isodecanoate), TMP-Tri [mixed (n
-Butanoate, n-hexanoate)], DTMP
Tetra (n-butanoate), DTMP tetra (2-
Methyl propanoate), DTMP tetra (n-pentanoate), DTMP tetra (2-methylbutanoate), DTMP tetra (3-methylbutanoate), DTMP tetra (2,2-dimethylpropanoate) Ate), DTMP tetra (n-hexanoate), D
TMP ・ Tetra (2-ethylbutanoate), DTMP
・ Tetra (2,2-dimethylbutanoate), DTMP
-Tetra (n-heptanoate), DTMP-tetra (2-ethylpentanoate), DTMP-tetra (n
-Octanoate), DTMP tetra (2-ethylhexanoate), DTMP tetra (n-nonanate), DTMP tetra (isononate), DTMP
-Tetra (n-decanoate), DTMP-tetra (isodecanoate), DTMP-tetra [mixed (n-butanoate, n-hexanoate)], DTMP-tetra [mixed (n-pentanoate, isohexanoate)], PE- Tetra (n-butanoate), PE.Tetra (2-methylpropanoate), PE.Tetra (n
-Pentanoate), PE-tetra (2-methylbutanoate), PE-tetra (3-methylbutanoate),
PE / Tetra (2,2-dimethylpropanoate), P
E. tetra (n-hexanoate), PE. Tetra (2
-Ethylbutanoate), PE-tetra (2,2-dimethylbutanoate), PE-tetra (n-heptanoate), PE-tetra (2-ethylpentanoate), P
E. tetra (n-octanoate), PE. Tetra (2
-Ethyl hexanoate), PE-tetra (n-nonanoate), PE-tetra (isononanoate), PE-tetra (n-decanoate), PE-tetra (isodecanoate) PE-tetra [mixed (n-pentanoate, isopenta Noate, n-hexanoate, n-butanoate)], PE / tetra [mixed (n-pentanoate, isopentanoate, n-heptanoate, n-nonanoate)], DPE-hexa (n-butanoate), DPE
Hexa (2-methylpropanoate), DPE / hexa (n-pentanoate), DPE / hexa (2-methylbutanoate), DPE / hexa (3-methylbutanoate), DPE / hexa (2,2) 2-dimethylpropanoate), DPE / hexa (n-hexanoate), D
PE-hexa (2-ethylbutanoate), DPE-hexa (2,2-dimethylbutanoate), DPE-hexa (n-heptanoate), DPE-hexa (2-ethylpentanoate), DPE-hexa (N-octanoate), DPE.hexa (2-ethylhexanoate), DPE.hexa (n-nonanoate), DPE.hexa (isononate), DPE.hexa (n-decanoate), DPE.hexa [mixed (iso Pentanoate, n-hexanoate)], DPE / hexa [mixture (n-pentanoate, isopentanoate, n-hexanoate, n-butanoate)], DPE / hexa [mixture (n-pentanoate, isopentanoate, n
-Heptanoate, n-nonanoate], TPE octa (n-butanoate), TPE octa (2-methylpropanoate), TPE octa (n-pentanoate), TPE octa (2-methylbutanoate), T
PE octa (2,2-dimethylpropanoate), T
PE-octa (n-hexanoate), TPE-octa (2-ethylbutanoate), TPE-octa (n-octanoate), TPE-octa (2-ethylhexanoate), TPE-octa (n-nonanoate) , TPE
Octa (isononanoate), TPE octa (n-decanoate), TPE octa [mixed (n-pentanoate, isopentanoate, hexanoate, n-butanoate)], TPE octa [mixed (isopentanoate, n- Hexanoate)], TPE / octa [mixed (n-pentanoate, iso-pentanoate, n-heptanoate, n-nonanate)] and the like. According to the invention, in particular DPE-hexa [mixed (isopentanoate, n-hexanoate)], TPE-octa [mixed (isopentanoate, n-hexanoate)]
Etc. are preferred.

Further, as the hindered ester used in the heat-resistant lubricating oil composition of the present invention, those in which the chain length of the hydrocarbon group in the fatty acid moiety has an average carbon number of 3 to 8, particularly 4 to 7 is heat and acid resistant. It is particularly preferable because it is excellent in chemical conversion.

Polyphenyl thioether The polyphenyl thioether used as a component of the heat resistant lubricating oil composition of the present invention has a structure in which an aromatic ring is bound by a sulfur atom and has the following general formula [I]:

[0019]

Embedded image It is represented by

In the above general formula [I], R ¹ , R ² and R ³ may be the same or different from each other and each is a hydrogen atom or a carbon number of 1 to 24.
Is a hydrocarbon group. A compound in which all of R ¹ , R ² and R ³ are hydrogen atoms represents a hydrocarbon-unsubstituted polyphenyl thioether. The hydrocarbon group has, for example, 1 carbon atom.
-24 straight-chain or branched alkyl groups; C2-C2
A straight-chain or branched alkenyl group having 4 to 6 carbon atoms
A cycloalkyl group; and an aryl group having 6 to 24 carbon atoms. The aryl group has 1 to 1 carbon atoms as a substituent.
It may have 2 alkyl groups or 2 to 12 alkenyl groups. A preferred hydrocarbon group is an alkyl group having 6 to 20 carbon atoms, specifically, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group,
A dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group and the like, and those having a branch thereof are used. Particularly, those having 8 to 18 carbon atoms are preferable. The hydrocarbon group may be bonded to any position of the aromatic ring.

In the above general formula [I], x, y and z are the same or different from each other, and each is 1
-4.

In the above general formula [I], m is an integer of 1 to 3, and the polyphenylthioether of the present invention has 3
Compounds containing from 1 to 5 aromatic rings are included.

The thioether bond of the polyphenyl thioether may be bonded at any position of the aromatic ring, but from the viewpoint of maintaining fluidity, a bond at the meta position is preferable.

Therefore, as the polyphenyl thioether represented by the general formula [I], both hydrocarbon-unsubstituted polyphenyl thioether and hydrocarbon-substituted polyphenyl thioether are used.

Hydrocarbon-unsubstituted polyphenyl thioethers have the general formula [II]:

[0026]

Embedded image (In the above general formula [II], m is an integer of 1 to 3.) In the present invention, in addition to improving heat resistance, oxidation resistance and wear resistance, the viscosity of the lubricating oil composition and other From the viewpoint of adjusting physical properties, it is a particularly preferable compound.

Specific examples of the hydrocarbon-unsubstituted polyphenyl thioether are as follows. That is, m-bis (phenylmercapto) benzene (m-3
P2T), o-bis (phenylmercapto) benzene (o-3P2T), p-bis (phenylmercapto) benzene (p-3P2T), bis (phenylmercapto)
Benzene isomer mixture (mix-3P2T), bis (m
-Phenylmercaptophenyl) sulfide (m, m
-4P3T), bis (o-phenylmercaptophenyl) sulfide (o, o-4P3T), bis (p-phenylmercaptophenyl) sulfide (p, p-4)
P3T), m-phenylmercaptophenyl p-phenylmercaptophenyl sulfide (m, p-4P3
T), m-phenylmercaptophenyl o-phenylmercaptophenyl sulfide (m, o-4P3T),
p-phenylmercaptophenyl o-phenylmercaptophenyl sulfide (p, o-4P3T), bis (phenylmercaptophenyl) sulfide isomer mixture (mix-4P3T), m-bis (m-phenylmercaptophenylmercapto) benzene (m, m, m-
5P4T), 1- (m-phenylmercaptophenylmercapto) -3- (p-phenylmercaptophenylmercapto) benzene (m, m, p-5P4T), p-bis (m-phenylmercaptophenylmercapto) benzene (m, m). p, m-5P4T), 1- (m-phenylmercaptophenylmercapto) -4- (p-phenylmercaptophenylmercapto) benzene (m, p, p-
5P4T), m-bis (p-phenylmercaptophenylmercapto) benzene (p, m, p-5P4T), p
-Bis (p-phenylmercaptophenylmercapto)
Benzene (p, p, p-5P4T), o-bis (m-phenylmercaptophenylmercapto) benzene (m,
o, m-5P4T), m-bis (o-phenylmercaptophenylmercapto) benzene (o, m, o-5P4)
T), p-bis (o-phenylmercaptophenylmercapto) benzene (o, p, o-5P4T), o-bis (o-phenylmercaptophenylmercapto) benzene (o, o, o-5P4T), and bis ( Examples include phenylmercaptophenylmercapto) benzene isomer mixture (mix-5P4T).

As a specific example of the hydrocarbon-substituted polyphenyl thioether, a mono-obtained product obtained by bonding 1 to 3 alkyl groups having 6 to 20 carbon atoms in the molecule as described above,
Included are di- or tri-alkylated polyphenyl thioethers. For example, mono-alkylated m- bis (phenylmercapto) benzene (R-m-3P2T), dialkylated m- bis (phenylmercapto) benzene (R ₂ -
m-3P2T), trialkylated m-bis (phenylmercapto) benzene (R ₃ -m-3P2T), and bis (m-phenylmercaptophenyl) sulfide m.
-Bis (m-phenylmercaptophenylmercapto)
An example is an alkylated product of benzene.

The above-mentioned hydrocarbon-unsubstituted polyphenyl thioether and hydrocarbon-substituted polyphenyl thioether are
One type or two or more types are used.

Among the compounds exemplified above, m-bis (phenylmercapto) benzene (m-3P2T) and o-bis (phenylmercapto) benzene (which are hydrocarbon-unsubstituted polyphenylthioethers for the lubricating oil composition of the present invention ( o-3P2T), p-bis (phenylmercapto) benzene (p-3P2T), bis (m-phenylmercaptophenyl) sulfide (m, m-4P3T)
And m-bis (m-phenylmercaptophenylmercapto) benzene (m, m, m-5P4T) and the like, as described above, are particularly preferable from the viewpoints of heat resistance / oxidation resistance, improvement of wear resistance and physical properties of the lubricating oil composition. It is useful.

The above polyphenyl thioether may be produced by any method. Taking m-bis (phenylmercapto) benzene as an example, first, thiophenol metal salt and m-dihalogenobenzene are present in the presence of a copper catalyst. By reacting below, m-bis (phenylmercapto) benzene is produced (pre-reaction). m-Bis (phenylmercapto) benzene (m-
3P2T) can be obtained by collecting a desired fraction from the product of this first-stage reaction.

Next, to prepare hydrocarbon-substituted m-bis (phenylmercapto) benzene, m-bis (phenylmercapto) benzene is reacted with α-olefin in the presence of a Lewis acid catalyst to alkylate m-bis. It is possible to produce (phenylmercapto) benzene (second-stage reaction).

In the first-step reaction, N is used as the polar solvent.
-Methyl-2-pyrrolidone, N-propyl-2-pyrrolidone, dimethylacetamide, dimethylformamide and the like are used, and as the thiophenol metal salt, thiophenol sodium salt, thiophenol potassium salt and the like are used. Further, as the copper catalyst, copper chlorides such as cuprous chloride and cupric chloride, copper oxides such as cuprous oxide and cupric oxide, and the like are used. As m-dihalogenobenzene, m
-Dipromobenzene and m-dichlorobenzene. The thiophenol metal salt and m-dihalogenobenzene are mixed at a ratio of 3: 1 to 2: 1 and a temperature of 160 ° C to 210 ° C.
The reaction is carried out at a temperature of ° C. In the second reaction, 0.3 mol to 3 mol of α-olefin is mixed with 1 mol of m-bis (phenylmercapto) benzene obtained in the first reaction, and the mixture is subjected to the reaction at a temperature of 80 ° C to 100 ° C. As the Lewis acid catalyst used in the second-stage reaction, boron fluoride, aluminum chloride or the like is used.

From the reaction product obtained as described above,
A predetermined fraction was collected by a method such as vacuum distillation, and alkylated m-bis (phenylmercapto) benzene (R-m
-3P2T) can be isolated.

Lubricating Oil Composition The heat-resistant lubricating oil composition of the present invention comprises (a) an ester of a hindered alcohol and a fatty acid, and (b) a polyphenylthioether having 3 to 5 aromatic rings. is there.
The mixing ratio is (a) hindered ester 10 wt% to 90 wt% and (b) polyphenyl thioether 90 wt% to 10 wt% based on the total weight of the lubricating oil composition,
A preferable ratio is (a) 20% by weight to 80% by weight (b).
It is 80% to 20% by weight. A particularly preferred ratio is
(A) 40 wt% to 60 wt% (b) 60 wt% to 40
% By weight. By mixing the hindered ester and the polyphenyl thioether in the above proportions, the poor abrasion resistance can be improved, and the heat resistance and the oxidation resistance can be further improved by themselves. If the mixing ratio of the hindered ester is less than 10% by weight, the abrasion resistance is inferior. On the other hand, if it exceeds 90% by weight, the abrasion resistance and the heat resistance are similarly reduced.

As the heat-resistant lubricating oil composition of the present invention, by mixing the two, a kinematic viscosity at 100 ° C. of 2 cSt to 30 cSt, particularly 3 cSt to 10 cSt is usually obtained, and dipentaerythritol is used as a hindered alcohol. , A hydrocarbon-unsubstituted polyphenyl thioether, for example, m-bis (phenylmercapto) benzene, obtained by using a high-viscosity alcohol such as tripentaerythritol, or ditrimethylolpropane, to improve the physical properties such as viscosity. A controlled lubricating oil composition can be obtained.

Commercially available products of the above-mentioned hindered esters include LX-810 (dipentaerythritol ester) or LX-889 (tripentaerythritol ester) or LX-1342 manufactured by Asahi Denka Kogyo Co., Ltd.
(Ditrimethylolpropane ester) or the like can be used.

It is preferable to add an antiwear agent as an additive to the heat resistant lubricating oil composition of the present invention. Furthermore, if necessary, for example, an antioxidant, a metal deactivator, etc. can be added appropriately.

Examples of the antiwear agent include phosphoric acid esters such as trialkyl phosphate, tricresyl phosphate, triphenyl phosphate, benzyldiphenyl phosphate and ethyldiphenyl phosphate, zinc dialkyldithiophosphate, sulfur compounds and the like. However, tricresyl phosphate is particularly preferable. These are usually used in a proportion of 0.01% to 7% by weight, preferably 1% to 5% by weight. The abrasion resistance can be further improved by adding the antiwear agent to the mixed oil of the hindered ester and the polyphenyl thioether.

Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine and alkylated-α-naphthylamine, 2,6-di-t-butylphenol, 4,4'- Examples thereof include phenolic antioxidants such as methyl-bis- (2,6-di-t-butylphenol), sulfur-containing antioxidants such as zinc dialkyldithiophosphate, and sulfurized paraffin. 0.05 wt% ~
It is used in a proportion of 5% by weight, preferably 0.1% to 3% by weight.

Examples of the metal deactivator include benzotriazole, thiadiazole and the like, and these are usually used in a proportion of 0.01% by weight to 3% by weight.

The heat-resistant lubricating oil composition obtained as described above is used as jet engine oil, turbocharger engine oil, super heat-resistant heat-insulating engine oil, gas turbine oil, ceramic gas turbine oil, etc. used at high temperatures. It is possible.

[0043]

The present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

As a method for evaluating the effect of the present invention, the corrosion and oxidation stability test method and the four-ball test method were adopted to evaluate the heat resistance, oxidation resistance and wear resistance. Corrosion Oxidation Stability Test (COS Test) This test method is determined in accordance with the USAF MIL-L-23699 standard, 100 ml of sample oil is taken, Ag, Al, Fe, and Ti are used as an oxidation catalyst, and the temperature is 230 ° C. For 72 hours, air was blown at a rate of 5 liters per hour to carry out the oxidation treatment, and then the weight change of the metal piece before and after the oxidation treatment,
The change in viscosity, the change in total acid value, and the amount of sludge produced after the oxidation treatment were measured and used as the evaluation results of heat resistance and oxidation resistance.

In the above-mentioned test items, the change in weight of the metal piece is defined as the weight change / surface area of the metal piece of ± 0.2 mg / cm ² or less. The viscosity change is the kinematic viscosity change rate (%) at 40 ° C, and the change in total acid value is the difference in total acid value (mgKOH
The amount of sludge produced is the weight (mg / 10) of the residue after 100 ml of the sample oil after filtering the sample oil after the oxidation treatment with a filter having a pore size of 10 μm manufactured by Millipore.
0 ml).

Four- Ball Test In the wear test using a shell four-ball tester, the following test conditions were adopted, and test balls made of the following three kinds of materials were used as a rotating ball and a fixed ball as shown in each example. 30
The wear scar diameters (mm) of the three fixed balls after the operation for a minute were measured, and the average value thereof was obtained. Test conditions: Temperature (° C): 80 Load (kg): 30 Rotation speed (rpm): 1,200 Test sphere: SUJ-2 (high carbon chromium steel) M-50 (heat resistant steel) Si ₃ N ₄ (silicon nitride) Quality ceramics)

Example 1 Ester of dipentaerythritol with a mixture of iso-pentanoic acid and n-hexanoic acid (DPE.hexa [mixed (iso-pentanoate, n-hexanoate)])
And m-bis (phenylmercapto) benzene (m-3P
2T) and 50% by weight of DPE / hexa [mixture (iso-pentanoate, n-hexanoate)] and m
-3P2T 50 wt% mixture, to which tricresyl phosphate was added by 4 wt% based on the total weight of the composition, and kinematic viscosities at 40 ° C. and 100 ° C. were 25.
0 cSt and 4.8 cSt with a viscosity index of 113
A heat resistant lubricating oil composition was obtained.

Next, when the obtained lubricating oil composition was subjected to a corrosion oxidation stability test (COS test) and a four-ball test, the results shown in Table 1 were obtained. Example 2 Ester of tripentaerythritol with a mixture of isopentanoic acid and n-hexanoic acid (TPE-octa [mixed (iso-pentanoate, n-hexanoate)]]
And m-bis (phenylmercapto) benzene (m-3P
2T), and mixed with TPE.octa [mix (iso-pentanoate, n-hexanoate)] 50% by weight, m
-3P2T 50 wt% mixture, to which tricresyl phosphate was added by 4 wt% based on the total weight of the composition, and the kinematic viscosities at 40 ° C and 100 ° C were 36.
0 cSt and 6.2 cSt with a viscosity index of 121
A lubricating oil composition of was obtained.

Table 1 shows the results of the corrosion and oxidation stability test (COS test) and the four-ball test of this lubricating oil composition. Example 3 Ester of dipentaerythritol with a mixture of iso-pentanoic acid and n-hexanoic acid (DPE-hexa [mixed (iso-pentanoate, n-hexanoate)])
And m-bis (phenylmercapto) benzene (m-3P
2T) and DPE / hexa [mixture (iso-pentanoate, n-hexanoate)] 80% by weight, m
-3P2T 20 wt% mixture, to which tricresyl phosphate was added by 4 wt% based on the total weight of the composition, and the kinematic viscosities at 40 ° C. and 100 ° C. were 46.
Lubricating oil compositions of 1 cSt and 7.3 cSt were obtained. Next, the obtained lubricating oil composition was subjected to a corrosion oxidation stability test (CO
When subjected to the S test) and the four-ball test, the results shown in Table 1 were obtained. Example 4 An ester of a mixture of dipentaerythritol and iso-pentanoic acid, n-hexanoic acid (DPE.hexa [mixed (iso-pentanoate, n-hexanoate)) and m-bis (phenylmercapto) benzene (m-3P2).
T) with PE-hexa [mixture (iso-pentanoate, n-hexanoate) 20% by weight, m-3P
Tricresyl phosphate was added to the mixture having 2T of 80% by weight in an amount of 4% by weight based on the total weight of the composition to obtain a lubricating oil composition having kinematic viscosities of 15.0 cSt and 3.4 cSt at 40 ° C. and 100 ° C., respectively. . Next, the obtained lubricating oil composition was subjected to a corrosion oxidation stability test (COS test) and a four-ball test, and the results shown in Table 1 were obtained. Example 5 An ester of ditrimethylolpropane and n-heptanoic acid (DTMP.tetra (n-heptanoate)) and m-
Bis (phenylmercapto) benzene (m-3P2T)
And are mixed, and DTMP tetra (n-heptanoate) 5
4% by weight based on the total weight of the composition of tricresyl phosphate in a mixture of 0% by weight and m-3P2T 50% by weight.
Kinematic viscosity at 40 ° C and 100 ° C is 1 each
Lubricating oil compositions of 9.0 cSt and 4.1 cSt were obtained. Next, the obtained lubricating oil composition was subjected to a corrosion oxidation stability test test (COS test) and a four-ball test.
Were obtained.

Comparative Example 1 Ester of dipentaerythritol with a mixture of iso-pentanoic acid and n-hexanoic acid (DPE-hexa [mixed (iso-pentanoate, n-hexanoate)])
4% by weight, based on the total weight of the composition, of tricresyl phosphate was added thereto to obtain a lubricating oil composition.
The kinematic viscosities of this lubricating oil composition at 40 ° C. and 100 ° C. were 72.1 cSt and 10.0 cSt, respectively. Table 1 shows the results of the corrosion oxidation stability test and the four-ball test. Comparative Example 2 Tripentaerythritol and iso-pentanoic acid, n-
The tricresyl phosphate was added to an ester with a mixture of hexanoic acids (TPE octa [mix (iso-pentanoate, n-hexanoate)]) at 4% by weight based on the total weight of the composition. 40 ° C. of the obtained lubricating oil composition
And kinematic viscosities at 100 ° C. were 202.0 cSt and 20.2 cSt, respectively, and the viscosity index was 112. When this was subjected to a corrosion oxidation stability test (COS test) and a four-ball test, the results shown in Table 1 were obtained. Comparative Example 3 4% by weight of tricresyl phosphate was added to m-triphenylthioether (m-3P2T) based on the total weight of the composition, and kinematic viscosities at 40 ° C. and 100 ° C. were each 11.0.
A lubricating oil composition having a cSt and a 2.8 cSt and a viscosity index of 79 was obtained. Corrosion oxidation stability test (COS test)
Table 1 shows the results of the four-ball test. Comparative Example 4 To the ester of dimethylolpropane and n-heptanoic acid (DTMP.tetra (n-heptanoate)), 4% by weight of tricresyl phosphate was added based on the total weight of the composition, and the mixture was heated at 40 ° C and 100 ° C. The viscosities are 34.
7 cSt and 6.5 cSt, viscosity index 143
A lubricating oil composition of was obtained. Table 1 shows the results of the corrosion oxidation stability test (COS test) and the four-ball test.

[0051]

[Table 1] Note 1) Dipentaerythritol ester: Asahi Denka Kogyo Co., Ltd. ester oil LX (DPE ester) -810 (ester of dipentaerythritol and a mixture of iso-pentanoic acid and n-hexanoic acid) 2) Tripentaerythritol ester: Asahi Denka Kogyo Co., Ltd. ester oil L (TPE ester) X-889 (ester of tripentaerythritol with a mixture of iso-pentanoic acid and n-hexanoic acid) 3) Ditrimethylol propane ester: Asahi Denka Kogyo Ester oil L (DTMP ester) X-1342 (ester of ditrimethylolpropane and n-heptanoic acid) manufactured by Co., Ltd. From the above examples and comparative examples, hindered ester and polyphenyl thioether alone are abrasion resistant. Both are inferior in properties, but by mixing both耗性 is remarkably improved, also heat-a hindered ester alone
Although it is inferior in oxidation resistance, the peculiar result is obtained that when used in combination with polyphenyl thioether, a synergistic effect also appears in heat resistance and oxidation resistance.

Furthermore, by mixing the high-viscosity hindered ester with the low-viscosity polyphenyl thioether, 100 ° C.
It has been found that the so-called low temperature viscosity of 40 ° C. is remarkably reduced as compared with the viscosity and the application can be expanded.

[0053]

As described above, according to the present invention, a relatively high viscosity hindered ester and polyphenyl thioether having an aromatic ring of 3 to 5 rings are mixed so that heat resistance and acid resistance due to a synergistic effect can be obtained. It is possible to provide a heat-resistant lubricating oil composition that exhibits the unique effects of improved chemical conversion and expression of wear resistance and that has excellent lubricating oil physical properties.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location (C10M 169/04 105: 38 135: 28) C10N 30:06 30:08 30:10

Claims (2)

[Claims] 1. (a) 10% to 90% by weight of an ester of a hindered alcohol having 5 to 30 carbon atoms and a fatty acid having 4 to 20 carbon atoms, and (b) the following general formula [I]: (In the above general formula [I], R ¹ , R ² and R ³
May be the same or different from each other, each is a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, and x, y and z may be the same or different from each other. They may be different, each is an integer of 1 to 4, and m is an integer of 1 to 3. ) A heat-resistant lubricating oil composition containing 90% by weight to 10% by weight of a polyphenyl thioether represented by 2. The polyphenyl thioether is represented by the following general formula [II]: The heat resistant lubricating oil composition according to claim 1, which is a compound represented by the formula (II), wherein m is an integer of 1 to 3.