JP2007126519A - Lubricant oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant oil composition which is suppressed in evaporating amount at a high temperature, of which the fluidity is maintained for a long time, and which is suitable for use at a high temperature. <P>SOLUTION: A base oil containing 50 mass% or higher of a mixture containing a hindered ester compound and an aromatic ester compound expressed by general formula (I) in the mass ratio of 5:95-95:5, is used in the lubricant oil composition. In the formula, R<SP>1</SP>shows a 6-18C alkyl group and n shows an integer of 1-6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition suitable for high temperatures used in chains, roller chains, chain conveyors, bearings and the like such as high temperature furnaces, drying furnaces, heat setters and the like.

  Lubricating oils used in chains, roller chains, chain conveyors, bearings, etc. such as high temperature furnaces, drying furnaces, heat setters, etc. are exposed to high temperatures, and the amount of evaporation of the lubricating oil greatly affects the life of the apparatus. Thus, under high temperature conditions, the lubricating oil loses its conventional viscosity and becomes a thin film, and the amount of evaporation must be suppressed under more severe conditions. As a conventional high-temperature lubricating oil, a high-viscosity and high-viscosity oil agent has been used in order to suppress evaporation (for example, see Patent Document 1). However, such an oil agent has a small amount of evaporation but a large power loss, which is not preferable when viewed as the total performance of the lubricating oil. In addition, when exposed to high temperatures, such an oil generally solidifies although there is a large amount of residue, and not only loses its properties as a liquid, but also becomes solidified sludge and prevents the flow of the oil. This results in poor lubrication of the lubrication part. Accordingly, it has been desired that a high-temperature lubricating oil can suppress the amount of evaporation at a high temperature and maintain fluidity for a long time.

JP 2000-192071 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a lubricating oil composition suitable for high temperatures, in which the amount of evaporation at high temperatures is suppressed and the fluidity is maintained for a long time. Is.

As a result of extensive research, the present inventors have achieved the above-described object of the present invention by using, as a main component, a mixture containing a hindered ester compound and a specific aromatic ester compound in a specific ratio as a base oil. Has been found to be achieved. The present invention has been completed based on such findings.
That is, the present invention provides the following lubricating oil composition.
1. A hindered ester compound and the following general formula (I)

(In the formula, R ¹ represents an alkyl group having 6 to 18 carbon atoms, and n represents an integer of 1 to 6).
A lubricating oil composition comprising a base oil containing 50% by mass or more of a mixture containing the aromatic ester compound represented by formula (1) at a mass ratio of 5:95 to 95: 5.
2. 2. The lubricating oil composition according to 1 above, which comprises one or more antioxidants selected from phenol-based antioxidants, amine-based antioxidants, and antioxidants containing sulfur and / or phosphorus in the molecule.
3. An hindered ester compound having one or more quaternary carbons in the molecule, and aliphatic hindered polyols having 1 to 4 methylol groups bonded to at least one of the quaternary carbons; 3. The lubricating oil composition according to 1 or 2 above, which is an ester with monocarboxylic acids and / or dimer acids.
4). 4. Lubricating oil composition in any one of said 1-3 whose aromatic ester compound is 1 or more types chosen from a phthalate, trimellitate, and pyromellitate.

  According to the present invention, it is possible to provide a lubricating oil composition suitable for high temperatures, in which the amount of evaporation at high temperatures is suppressed and the fluidity is maintained for a long time.

  As the base oil constituting the lubricating oil composition of the present invention, a hindered ester compound and the following general formula (I)

(In the formula, R ¹ represents an alkyl group having 6 to 18 carbon atoms, and n represents an integer of 1 to 6).
A base oil containing 50% by mass or more of a mixture containing the aromatic ester compound represented by the formula (1) at a mass ratio of 5:95 to 95: 5 is used.
Examples of the hindered ester compound include aliphatic hindered polyols having at least one quaternary carbon in the molecule and 1 to 4 methylol groups bonded to at least one of the quaternary carbons and fats. Group monocarboxylic acids and / or esters with dimer acids can be used.
Aliphatic hindered polyol having one or more quaternary carbons in the molecule and having 1 to 4 methylol groups bonded to at least one of the quaternary carbons, which is an alcohol component of the hindered ester compound. In the present invention, the following general formula (II)

(In the formula, R ² and R ³ each independently represent a hydrocarbon group or methylol group having 1 to 6 carbon atoms, and m represents an integer of 0 to 4)
Is preferably used.
In the above general formula (II), the hydrocarbon group having 1 to 6 carbon atoms of R ² and R ³ is preferably a linear or branched alkyl group or alkenyl group, and particularly preferably an alkyl group.

  The compounds represented by the general formula (II) (hindered polyols) are hindered polyols such as neopentyl glycol, trimethylol alkane (alkane has 2 to 7 carbon atoms), pentaerythritol, and dehydration thereof. A condensate, specifically neopentyl glycol; 2-ethyl-2-methyl-1,3-propanediol; 2,2-diethyl-1,3-propanediol; trimethylolethane; trimethylolpropane; Trimethylolpentane; trimethylolhexane; trimethylolheptane; pentaerythritol; 2,2,6,6-tetramethyl-4-oxa-1,7-heptanediol; 2,2,6,6,10, 10-hexamethyl-4,8-dioxa-1,11-undecadiol; 2 2,6,6,10,10,14,14-octamethyl-4,8,12-trioxa-1,15-pentadecadiol; 2,6-dihydroxymethyl-2,6-dimethyl-4-oxa-1 , 7-heptanediol; 2,6,10-trihydroxymethyl-2,6,10-trimethyl-4,8-dioxa-1,11-undecadiol; 2,6,10,14-tetrahydroxymethyl- 2,6,10,14-tetramethyl-4,8,12-trioxa-1,15-pentadecadiol; di (pentaerythritol); tri (pentaerythritol); tetra (pentaerythritol); penta (pentaerythritol) Etc.

These hindered polyols may be used alone or in combination of two or more during esterification. Note that m in the general formula (II) is preferably an integer of 0 to 2.
Among these hindered polyols, trimethylolpropane, neopentyl glycol, pentaerythritol, and their dehydration condensates are preferable, and the bimolecular or trimolecular condensates are preferable.
The production method of the hindered polyols may be a conventionally known method. The dehydration condensate of hindered polyols can be usually obtained by dehydration condensation at about 180 ° C. in the presence of a catalyst by heating the hindered polyols to a melting point or higher and dispersing them in a solvent.

  On the other hand, as the aliphatic monocarboxylic acids used when esterifying the aliphatic hindered polyols, saturated or unsaturated monocarboxylic acids having 6 to 22 carbon atoms are preferably used. The acyl group of this monocarboxylic acid may be either linear or branched. Examples of such aliphatic monocarboxylic acids include caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid Linear unsaturated monocarboxylic acids such as acid, nonadecanoic acid, arachidic acid, behenic acid, etc., linear unsaturation such as undecenoic acid, oleic acid, elaidic acid, celetic acid, erucic acid, brassic acid, linoleic acid, linolenic acid Monocarboxylic acid, isomyristic acid, isopalmitic acid, isostearic acid, 2,2-dimethylbutanoic acid, 2,2-dimethylpentanoic acid, 2,2-dimethyloctanoic acid, 2-ethyl-2,3,3-trimethyl Butanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,5,5-trimethyl- Branching of -t-butylhexanoic acid, 2,3,3-trimethyl-2-ethylbutanoic acid, 2,3-dimethyl-2-isopropylbutanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, etc. And saturated monocarboxylic acid. These aliphatic monocarboxylic acids may be used alone or in combination of two or more during esterification.

  Moreover, as a dimer acid used when esterifying, a C2-C22 saturated or unsaturated carboxylic acid is used preferably. Examples of the dimer acid include those represented by the following formula (III) or (IV) obtained from tall oil fatty acid and / or soybean oil fatty acid.

The hindered ester obtained by esterifying the aliphatic hindered polyols with the aliphatic monocarboxylic acid and / or dimer acid may be a completely esterified product or a partially esterified product. Although completely esterified, it is preferable.
In the lubricating oil composition of the present invention, the hindered ester compounds may be used alone or in a mixture containing two or more.

  On the other hand, as for the aromatic carboxylic acid which comprises the aromatic ester compound represented by the said general formula (I), the number of the carboxylic acid couple | bonded with benzene is preferable 2-4, and a phthalic acid, trimellitic acid, pyromellitic is especially preferable. Acid is preferred. That is, as the aromatic ester compound, phthalate, trimellitate and pyromellitate are preferable. As the aliphatic alcohol used for the aromatic ester compound, a linear or branched alcohol having 6 to 18 carbon atoms is preferable, and a linear alcohol is more preferable. Specific examples of the aromatic ester compound include di-n-hexyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, di-3,5,5-trimethylhexyl phthalate, diundecyl phthalate, diisostearyl phthalate, tri n-hexyl trimellitate, tri-2-ethylhexyl trimellitate, triundecyl trimellitate, triisostearyl trimellitate, tri n-octyl trimellitate, tri 3,5,5-trimethylhexyl trimellitate, Tetra n-hexyl pyromellitate, tetra 2-ethylhexyl pyromellitate, tetra n-octyl pyromellitate, tetra 3,5,5-trimethylhexyl pyromellitate, tetraundecyl pyromellitate and tetraisostearyl pyromellitate Etc. can be mentioned. In addition, the aromatic ester compound may be used alone or in combination of two or more kinds, and the full ester may contain a partial ester.

In the lubricating oil composition of the present invention, in order to obtain a base oil suitable for high temperature, the mixing ratio of the hindered ester compound and the aromatic ester compound is 5:95 to 95: 5, preferably by mass ratio. Is 20: 80-80: 20, more preferably 40: 60-60: 40.
Moreover, content in the base oil of the mixture which consists of this hindered ester compound and an aromatic ester compound is 50 mass% or more, Preferably it is 70 mass% or more, More preferably, it is 80 mass% or more.
In the lubricating oil composition of the present invention, in addition to the above-mentioned hindered ester compound and aromatic ester compound, the base oil is 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass. It can mix in the following ratios.
As said other base oil, synthetic oils other than a conventionally well-known mineral oil and / or a hindered ester compound, for example, poly alpha olefin, etc. can be mentioned.

The lubricating oil composition of the present invention may contain one or more antioxidants selected from phenol-based antioxidants, amine-based antioxidants, and antioxidants containing sulfur and / or phosphorus in the molecule. preferable. Among these antioxidants, an antioxidant containing sulfur and / or phosphorus in the molecule is preferable from the viewpoint of effects.
Examples of phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol; monophenols such as 2,6-di-tert-butyl-4-ethylphenol, and 4,4′-methylenebis. (2,6-di-tert-butylphenol); diphenols such as 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), and octadecyl 3- (3,5-di-tert-butyl) There may be mentioned polymer systems having an ester bond such as -4-hydroxyphenyl) propionate.

  Examples of amine antioxidants include monooctyl diphenylamine; monoalkyldiphenylamines such as monononyldiphenylamine; 4,4′-dibutyldiphenylamine; 4,4′-dipentyldiphenylamine; 4,4′-dihexyldiphenylamine; 4,4′-dioctyldiphenylamine; dialkyldiphenylamines such as 4,4′-dinonyldiphenylamine; tetrabutyldiphenylamine; tetrahexyldiphenylamine; tetraoctyldiphenylamine; polyalkyldiphenylamines such as tetranonyldiphenylamine; α-naphthylamine; phenyl-α-naphthylamine; butylphenyl-α-naphthylamine; pentylphenyl-α-naphthylamine; It can be mentioned naphthylamine such as nonylphenyl -α- naphthylamine; phenyl -α- naphthylamine; heptylphenyl -α- naphthylamine; octylphenyl -α- naphthylamine.

  The antioxidant containing sulfur and / or phosphorus in the molecule may be any compound that contains sulfur and / or phosphorus in the molecule and has an antioxidant ability, and may be added for other purposes. There is no problem. First, antioxidants containing sulfur in the molecule are described. For example, sulfurized fats and oils, sulfurized mineral oil, sulfurized fatty acids, sulfurized esters, sulfurized olefins, monosulfides, disulfides, dihydrocarbyl polysulfides, thiadiazole compounds, alkylthiocarbamoyl compounds, triazine compounds. Thioterpene compounds, dialkylthiodipropionate compounds, and the like.

  Here, sulfurized fats and oils are obtained by reacting sulfur and sulfur-containing compounds with fats and oils (lard oil, whale oil, vegetable oil, fish oil, etc.), and the sulfur content is not particularly limited, but generally 5 to 30 mass. % Is preferred. Specific examples thereof include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil, and sulfurized rice bran oil. Examples of the sulfurized fatty acid include sulfurized oleic acid, and examples of the sulfurized ester include sulfurized methyl oleate and sulfurized rice bran fatty acid octyl.

As the sulfurized olefin, for example, the following general formula (V)
R ⁴ -S _a -R ⁵ (V)
(In the formula, R ⁴ represents an alkenyl group having 2 to 15 carbon atoms, R ⁵ represents an alkyl group or alkenyl group having 2 to 15 carbon atoms, and a represents an integer of 1 to 8)
The compound etc. which are represented by these can be mentioned. This compound is obtained by reacting an olefin having 2 to 15 carbon atoms or a dimer or tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride, and as the olefin, propylene, isobutene, diisobutene and the like are preferable.
As monosulfide, dihexyl monosulfide, diheptyl monosulfide, dioctyl monosulfide, dinonyl monosulfide, didecyl monosulfide, diundecyl monosulfide, didodecyl monosulfide (dilauryl monosulfide), ditetradecyl monosulfide, Examples include dihexadecyl monosulfide. Specific examples of disulfide include disulfide corresponding to the monosulfide.

In addition, dihydrocarbyl polysulfide is represented by the following general formula (VI)
R ⁶ S _b -R ⁷ (VI)
(In the formula, R ⁶ and R ⁷ are each an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or 7 to 20 carbon atoms. An arylalkyl group, which may be the same or different from each other, and b represents an integer of 2 to 8)
It is a compound represented by these. Here, when R ⁶ and R ⁷ are alkyl groups, they are referred to as alkyl sulfides.

Specific examples of R ⁶ and R ⁷ in the general formula (VI) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, Various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl groups, cyclooctyl groups, phenyl groups, naphthyl groups, tolyl groups, xylyl groups, benzyl groups, Examples thereof include a phenethyl group.

  Preferred examples of the dihydrocarbyl polysulfide include dibenzyl polysulfide, various dinonyl polysulfides, various didodecyl polysulfides, various dibutyl polysulfides, various dioctyl polysulfides, diphenyl polysulfide, dicyclohexyl polysulfide, and the like. As the thiadiazole compound, for example, the following general formula (VII) or (VIII)

(Wherein, R ⁸ to R ¹¹ are each a hydrogen atom, C1-20, preferably a hydrocarbon group having 4 to 13 carbon atoms, c to f, respectively 0-8, preferably 1-4 Indicates an integer.)
1,3,4-thiadiazole and 1,2,4-thiadiazole compounds represented by the formula are preferably used. Specific examples of such thiadiazole compounds include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole, 2,5-bis (n-octyldithio) -1,3,4-thiadiazole. 2,5-bis (n-nonyldithio) -1,3,4-thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole, 3, , 5-bis (n-hexyldithio) -1,2,4-thiadiazole, 3,5-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n-nonyldithio)- Preferred examples include 1,2,4-thiadiazole and 3,5-bis (1,1,3,3-tetramethylbutyldithio) -1,2,4-thiadiazole. Examples of the alkylthiocarbamoyl compound include the following general formula (IX)

(Wherein R ^{12 to} R ¹⁵ each represent an alkyl group having 1 to 20 carbon atoms, preferably 4 to 8 carbon atoms, and g represents an integer of 1 to 8, preferably 1 to 3).
What is represented by these is used preferably. Specific examples of such alkylthiocarbamoyl compounds include bis (dimethylthiocarbamoyl) monosulfide, bis (dibutylthiocarbamoyl) monosulfide, bis (dimethylthiocarbamoyl) disulfide, bis (dibutylthiocarbamoyl) disulfide, and bis (diamil). Preferable examples include thiocarbamoyl) disulfide and bis (dioctylthiocarbamoyl) disulfide.

Preferred examples of the triazine compound include 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol. Furthermore, examples of the thioterpene compound include a reaction product of phosphorus pentasulfide and pinene, and examples of the dialkylthiodipropionate compound include dilauryl thiodipropionate and distearyl thiodipropionate.
Also, as containing sulfur and metal, zinc dialkyldithiocarbamate (Zn-DTC), molybdenum dialkyldithiocarbamate (Mo-DTC), lead dialkyldithiocarbamate, tin dialkyldithiocarbamate, sodium sulfonate, calcium sulfonate, etc. You can also

  Next, an antioxidant containing phosphorus in the molecule will be described. Typical examples are phosphate esters and amine salts thereof. The phosphoric acid esters include phosphoric acid esters, acidic phosphoric acid esters, phosphorous acid esters, and acidic phosphorous acid esters represented by the following general formulas (X) to (XIV).

In the general formulas (X) to (XIV), R ^{16 to} R ²⁶ are groups selected from alkyl groups, alkenyl groups, alkylaryl groups and arylalkyl groups having 4 to 30 carbon atoms, preferably 4 to 18 carbon atoms. R ^{16 to} R ²⁶ may be the same or different.
In the general formulas (X) to (XIV), R ^{16 to} R ²⁶ represent an alkyl group, alkenyl group, alkylaryl group, and arylalkyl group having 4 to 30 carbon atoms, and R ^{16 to} R ²⁶ are the same or different. May be. Examples of phosphate esters include triaryl phosphates, trialkyl phosphates, trialkylaryl phosphates, triarylalkyl phosphates, and trialkenyl phosphates. Specifically, for example, triphenyl phosphate, tricresyl phosphate, benzyldiphenyl phosphate, Ethyl diphenyl phosphate, tributyl phosphate, ethyl dibutyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, ethyl phenyl diphenyl phosphate, diethyl phenyl phenyl phosphate, propyl phenyl diphenyl phosphate, dipropyl phenyl phenyl phosphate, triethyl phenyl phosphate, tripropyl phenyl phosphate , Butylphenyl Such as phenyl phosphate, dibutylphenyl phenyl phosphate, tributylphenyl phosphate, trihexyl phosphate, tri (2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate, trioleyl phosphate Can be mentioned.

Specific examples of the acidic phosphate ester include 2-ethylhexyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate. , Stearyl acid phosphate, isostearyl acid phosphate, and the like.
Specific examples of phosphites include triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri (nonylphenyl) phosphite, tri (2-ethylhexyl) phosphite, tri Examples thereof include decyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenylisodecyl phosphite, tristearyl phosphite, and trioleyl phosphite.

Specific examples of the acidic phosphite include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydrogen phosphite, and diphenyl hydrogen phosphite. Furthermore, as amines that form amine salts with these, for example, general formula (XV)
R ²⁷ _m NH _3-m (XV)
(Wherein R ²⁷ represents an alkyl group or alkenyl group having 3 to 30 carbon atoms, an aryl group or arylalkyl group having 6 to 30 carbon atoms, or a hydroxyalkyl group having 2 to 30 carbon atoms, and m is 1, 2 or 3 shows a. in addition, when R ²⁷ is plural, R ²⁷ may be the same or different.)
And mono-substituted amines, di-substituted amines, and tri-substituted amines. The alkyl group or alkenyl group having 3 to 30 carbon atoms of R ²⁷ in the general formula (XV) may be linear, branched or cyclic.

  Here, examples of the mono-substituted amine include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine, benzylamine, etc. Examples of the disubstituted amine include Dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, dibenzylamine, stearyl monoethanolamine, decyl monoethanolamine, hexyl monopropanolamine, benzyl Examples include monoethanolamine, phenyl monoethanolamine, and tolyl monopropanol. Examples of tri-substituted amines are tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleyl monoethanolamine, dilauryl. Monopropanolamine, dioctyl monoethanolamine, dihexyl monopropanolamine, dibutyl monopropanolamine, oleyl diethanolamine, stearyl dipropanolamine, lauryl diethanolamine, octyl dipropanolamine, butyl diethanolamine, benzyl diethanolamine , Phenyl diethanolamine, tolyl dipropanolamine, xylyl diethanolamine It may be mentioned triethanolamine, tripropanolamine and the like.

  Examples of those containing phosphorus and halogen atoms include chlorinated phosphates. Examples of the antioxidant containing sulfur and phosphorus in the molecule include phosphosulfurized fats and oils, phosphosulfurized olefins, thiophosphates (thiophosphites, thiophosphates), among them thiophosphites (alkyl type), Thiophosphate (alkylaryl type) is preferred.

  Dithiophosphates such as zinc dithiophosphate (Zn-DTP), molybdenum dithiophosphate (Mo-DTP), lead dithiophosphate, tin dithiophosphate, etc. can be mentioned as those containing sulfur, phosphorus and metals, among which alkyl Those having an aryl group are preferred. Among the above-mentioned antioxidants, 2,6-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine-2 is effective in suppressing the amount of evaporation. -Ilamino) phenol, Zn-DTP (alkylaryl type), thiophosphite (alkyl type), thiophosphate (alkylaryl type) are preferred.

  The said antioxidant can be used individually or in combination of 2 or more types. The blending amount of the antioxidant is usually about 0.1 to 10% by mass, preferably 1 to 7% by mass, based on the total amount of the composition. When the blending amount is 0.1% by mass or more, the object of the present invention is sufficiently exerted, and when the blending amount is 10% by mass or less, the balance between the blending effect and the economy is good, and the dissolution in the base oil Good properties.

In the lubricating oil composition of the present invention, various known additives such as a rust preventive agent, a cleaning dispersant, a metal deactivator, and an antifoaming agent are appropriately blended as necessary within a range not impairing the object of the present invention. can do. Examples of the rust inhibitor include metal sulfonates and succinates.
Examples of the cleaning dispersant include metal sulfonate, metal salicylate, metal finate, and succinimide. Examples of the metal deactivator include benzotriazole and thiadiazole. Examples of antifoaming agents include methyl silicone oil, fluorosilicone oil, and polyacrylate.

In the lubricating oil composition of the present invention, it is preferable to adjust the kinematic viscosity at 40 ° C. to 10 to 500 mm ² / s in order to achieve the object. More preferably, it is the range of 50-320 mm < ² > / s. In addition, the lubricating oil composition of the present invention is suitably used when the temperature exceeds 150 ° C. during 50% or more of the period of use.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
76.4 parts by mass of (neopentylglycol-2-ethylhexanol) dimer acid ester as a hindered ester compound, 20 parts by mass of tri-n-octyl trimellitate as an aromatic ester compound, octylphenyl- as an amine-based antioxidant 1 part by mass of α-naphthylamine, 1 part by mass of 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol as a sulfur-based antioxidant Parts, 2 parts by mass of trinonylphenylthiophosphate as a phosphorus-based antioxidant, 0.05 parts by mass of benzotriazole, 0.5 parts by mass of Ca salicylate of TBN (total base number) 300, and 0.05 parts by mass of alkenyl succinate Were mixed to prepare a lubricating oil composition. When this thin film residue test was conducted on this lubricating oil composition by the following method, the residual oil ratio was 84.1%. Moreover, when the container was tilted and the presence or absence of fluidity at that time was visually determined, it was confirmed that the container had fluidity.

<Thin film residue test>
Using a container and a constant temperature air bath shown in the lubricating oil thermal stability test of JIS K 2540, the amount of residue was measured at 200 ° C. for 48 hours with a sample amount of 1 g. It was expressed as a percentage and used as the residue rate. During the measurement, air was constantly introduced at 10 liter / hr.

Example 2
In Example 1, a lubricating oil composition was prepared and evaluated in the same manner as in Example 1 except that 76.4 parts by mass of dipentaerythritol isostearyl acid was used as the hindered ester compound. As a result, the residual oil ratio was 81.7%, and it was confirmed that the residual oil ratio was fluid.

Comparative Example 1
In Example 1, a lubricating oil composition was prepared in the same manner as in Example 1 except that 76.4 parts by mass of poly α-olefin (Amoco, DURASYN174) was used instead of the hindered ester compound. Evaluation was performed. As a result, the residual oil ratio was 73.5%, and it was confirmed that there was no fluidity.

  The lubricating oil composition of the present invention is suitably used in chains, roller chains, chain conveyors, bearings and the like such as high temperature furnaces, drying furnaces, heat setters and the like.

Claims (4)

A hindered ester compound and the following general formula (I)

(In the formula, R ¹ represents an alkyl group having 6 to 18 carbon atoms, and n represents an integer of 1 to 6).
A lubricating oil composition comprising a base oil containing 50% by mass or more of a mixture containing the aromatic ester compound represented by formula (1) at a mass ratio of 5:95 to 95: 5.   The lubricating oil composition according to claim 1, comprising one or more antioxidants selected from phenolic antioxidants, amine-based antioxidants, and antioxidants containing sulfur and / or phosphorus in the molecule.   An hindered ester compound having one or more quaternary carbons in the molecule, and aliphatic hindered polyols having 1 to 4 methylol groups bonded to at least one of the quaternary carbons; The lubricating oil composition according to claim 1 or 2, which is an ester with monocarboxylic acids and / or dimer acids.   The lubricating oil composition according to any one of claims 1 to 3, wherein the aromatic ester compound is at least one selected from phthalate, trimellitate, and pyromellitate.