JP2008115301A - Biodegradable lubricant composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable lubricant composition which excels in biodegradability, also excels in rust prevention/anticorrosion for iron and a non-ferrous metal such as white metal, hydrolysis stability and oxidation stability and which is applicable to a bearing oil for a hydraulic turbine for hydraulic power generation, a steam turbine oil, a gas turbine oil, a hydraulic oil, a compressor oil, a bearing oil for various industrial machines, a hydraulic oil/sliding surface oil for machine tools and the like. <P>SOLUTION: The biodegradable lubricant composition comprises (A) a synthetic ester type base oil containing ≥90 mass% of a hindered ester between an aliphatic hindered polyol, which has one or more quaternary carbons in the molecule and has 1-4 methylol groups bonded to at least one of the quaternary carbons, and an aliphatic monocarboxylic acid and (B) (a) 0.01-3 mass% of a fatty acid amide compound and (b) 0.01-2 mass% of a benzotriazole derivative. It has a biodegradability ratio of ≥60%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a biodegradable lubricating oil composition. More specifically, the present invention is excellent in biodegradability, and is excellent in rust / corrosion resistance, hydrolysis stability and oxidation stability for non-ferrous metals such as iron and white metal. Related to biodegradable lubricating oil compositions applicable to bearing oils, steam turbine oils, gas turbine oils, hydraulic fluids, compressor oils, bearing oils for various industrial machines, hydraulic fluids and sliding surface oils for machine tools, etc. It is.

In recent years, biodegradable lubricants have attracted attention in the field of lubricants from the viewpoint of environmental pollution countermeasures, and in industrial machinery, first, biodegradable hydraulic fluids for construction machinery used outdoors are developed. Has begun to be used in the department. Along with such an increase in environmental protection, biodegradable lubricating oil has been demanded from environmental pollution countermeasures in the case of leakage to hydroelectric turbine bearing oil. This type of bearing oil is required to have characteristics different from those of hydraulic fluid, and the development of a new biodegradable lubricating oil is required.
Known biodegradable base oils include natural vegetable oils such as rapeseed oil, synthetic esters, and polyalkylene glycols. However, although natural vegetable oils are inexpensive, they have problems such as poor thermal stability and oxidation stability and poor supply stability. Polyalkylene glycols are inexpensive and have good thermal stability. However, it has problems such as poor seal material compatibility. Therefore, the biodegradable lubricating oil in Japan is becoming a mainstream synthetic ester.
For example, as a biodegradable lubricating oil, a lubricating oil in which various additives are blended with a synthetic ester base oil is disclosed (see, for example, Patent Documents 1, 2, and 3). However, all of the lubricating oils disclosed in these publications place importance on biodegradability and characteristics as hydraulic fluids. For this reason, it can withstand rust and corrosion resistance against iron, copper, and white metal that must be provided as bearing oil for water turbines, hydrolytic stability of ester base oils when mixed with water, and long-term use for more than 10 years Oxidation stability is not taken into consideration, and none of them are insufficient in terms of performance. For example, they cannot be applied as bearing oil for biodegradable turbines.

JP-A-5-339591 JP-A-6-228579 JP 2005-213451 A

  Under such circumstances, the present invention is excellent in biodegradability, and has anti-corrosion and anti-corrosion properties against non-ferrous metals such as iron and white metal, hydrolytic stability, and oxidation stability that can withstand long-term use. It is also applicable to hydroelectric turbine bearing oil, steam turbine oil, gas turbine oil, hydraulic hydraulic oil, compressor oil, bearing oil for various industrial machines, hydraulic hydraulic oil and sliding surface oil for machine tools, etc. It is an object of the present invention to provide a biodegradable lubricating oil composition, preferably a bearing, particularly preferably a hydrodegradable lubricating oil composition for bearings of hydroelectric turbines (hydropower turbines).

As a result of earnest research to develop a biodegradable lubricating oil composition having the above-mentioned preferable properties, the present inventor has obtained a hindered ester of an aliphatic hindered polyol and an aliphatic monocarboxylic acid as a base oil. A compound containing 90% by mass or more is used, and each of the fatty acid amide compound and the benzotriazole derivative is included in a specific ratio, more preferably an antioxidant, and particularly preferably an amine antioxidant is included in a specific ratio. The present inventors have found that a lubricating oil composition having a biodegradation rate of a certain value or more can meet the purpose. The present invention has been completed based on such findings.
That is, the present invention
[1] (A) aliphatic hindered polyols having one or more quaternary carbons in the molecule and 1 to 4 methylol groups bonded to at least one of the quaternary carbons, and aliphatic Synthetic ester base oil containing 90% by mass or more of hindered esters with monocarboxylic acids, 0.01 to 3% by mass of (B) (a) fatty acid amide compound, and (b) benzotriazole derivative 0.01 to A biodegradable lubricating oil composition comprising 2% by mass and having a biodegradation rate of 60% or more,
[2] The biodegradable lubricating oil composition according to [1], further comprising (c) 0.1 to 5% by mass of an antioxidant as the component (B),
[3] The biodegradable lubricating oil composition according to the above [2], wherein the antioxidant is an amine-based antioxidant,
[4] The biodegradable lubricating oil composition according to any one of the above [1] to [3], wherein the 96-hour LC ₅₀ value is 100 mg / L or more in an acute toxicity test against medaka based on JIS K 0102,
[5] The aliphatic hindered polyols constituting the hindered ester in the component (A) are represented by the general formula (I)

(Wherein, R ¹ and R ² each independently represent a hydrocarbon group or a methylol group having 1 to 6 carbon atoms, n represents an integer of 0 to 4.)
The biodegradable lubricating oil composition according to any one of the above [1] to [4], which is a compound represented by:
[6] The biodegradable lubricating oil composition according to the above [5], wherein the aliphatic hindered polyol is trimethylolpropane, neopentyl glycol, pentaerythritol or a dehydration condensate thereof.
[7] The biodegradable lubricating oil composition according to any one of [1] to [6], wherein the aliphatic monocarboxylic acids constituting the hindered ester in the component (A) are saturated fatty acids having 5 or more carbon atoms. object,
[8] The biodegradable lubricating oil composition according to any one of [1] to [7], wherein the base number of the fatty acid amide compound of component (B) (a) is 10 mg KOH / g or more,
[9] The biodegradable lubricating oil composition according to any one of the above [1] to [8], wherein the base number of the benzotriazole derivative of the components (B) and (b) is 20 mg KOH / g or more,
[10] The biodegradable lubricating oil composition according to any one of [1] to [9], which is used as a bearing, and [11] the above [10], which is used as a bearing for a hydroelectric turbine. A biodegradable lubricating oil composition,
Is to provide.

  According to the present invention, it is excellent in biodegradability and is excellent in rust / corrosion resistance for non-ferrous metals such as iron and white metal, hydrolysis stability and oxidation stability that can withstand long-term use, Biodegradable lubrication applicable to bearing oil for hydroelectric turbines, steam turbine oil, gas turbine oil, hydraulic oil, compressor oil, bearing oil for various industrial machines, hydraulic oil for oil / slide surface of machine tools, etc. It is possible to provide an oil composition, preferably a biodegradable lubricating oil composition for bearings, particularly preferably for bearings of hydroelectric turbines (turbines for hydropower generation).

The biodegradable lubricating oil composition of the present invention (hereinafter sometimes simply referred to as a lubricating oil composition) includes a synthetic ester base oil as the base oil of the component (A), and the additive of the component (B). As a composition having a biodegradation rate of 60% or more, including a combination of (a) a fatty acid amide compound, (b) a benzotriazole derivative, and preferably (c) an antioxidant.
In the lubricating oil composition, the synthetic ester base oil used as component (A) has one or more quaternary carbons in the molecule, and at least one of the quaternary carbons has 1 to 4 methylol groups. It contains 90% by mass or more of hindered esters of aliphatic hindered polyols and aliphatic monocarboxylic acids formed by individual bonding.
Aliphatic hindered polyols 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. (Hereinafter, it may be simply referred to as hindered polyols) in the present invention, the general formula (I)

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

  The compounds represented by the general formula (I) (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, , 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) Is mentioned.

These hindered polyols may be used alone or in combination of two or more during esterification. In addition, n in the general formula (I) is preferably an integer of 0 to 2.
Among these hindered polyols, trimethylolpropane, neopentyl glycol, pentaerythritol, and their dehydration condensates are preferable from the viewpoint of the performance of the resulting hindered ester as a base oil. A bimolecular or trimolecular condensate is preferred.
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, the aliphatic monocarboxylic acids used when esterifying the hindered polyols may be either saturated or unsaturated, but from the viewpoint of oxidation stability that can withstand long-term use, the number of carbon atoms. A saturated monocarboxylic acid having 5 or more is preferable, and a saturated monocarboxylic acid having 5 to 24 carbon atoms is more preferable.
Examples of such saturated 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, Linear saturated monocarboxylic acids such as stearic acid, nonadecanoic acid, arachidic acid, behenic acid, isomyristinic acid, isopalmitic acid, isostearic acid, 2,2-dimethylbutanoic acid, 2,2-dimethylpentanoic acid, 2, 2-dimethyloctanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,5,5-trimethyl-2-t-butylhexanoic acid, 2 , 3,3-trimethyl-2-ethylbutanoic acid, 2,3-dimethyl-2-isopropylbutanoic acid, 2-ethylhexa Acid, branched saturated monocarboxylic acids, such as 3,5,5-trimethyl hexanoic acid and the like. These aliphatic monocarboxylic acids may be used alone or in combination of two or more during esterification.

The hindered ester obtained by esterifying the aliphatic hindered polyols with the aliphatic monocarboxylic acid may be a completely esterified product or a partially esterified product. Compounds are preferred.
In the biodegradable lubricating oil composition of the present invention, the hindered ester may be used alone or in a mixture containing two or more. In addition, the content of the hindered ester in the synthetic ester base oil needs to be 90% by mass or more in order for the lubricating oil composition to satisfy the predetermined properties described later.
As a synthetic ester base oil that can be used in combination with the hindered ester, from the viewpoint of biodegradability of the lubricating oil composition, an aliphatic polyhydric alcohol other than the hindered polyol and the aliphatic monocarboxylic acid are used. Mention may be made of esters.
In the lubricating oil composition, the kinematic viscosity of the synthetic ester base oil used as the component (A) varies depending on the use of the lubricating oil composition, but is usually about 10 to ²⁰⁰ mm ² / s at a temperature of 40 ° C., preferably Is selected in the range of 22 to 100 mm ² / s.
In addition, the acid value of the synthetic ester base oil is preferably 1 mgKOH / g or less, and more preferably 0.5 mgKOH / g or less, from the viewpoints of inhibiting corrosion against non-ferrous metals and inhibiting hydrolysis when mixed with water.

In the lubricating oil composition of the present invention, the fatty acid amide compound of the component (a) in the additive of the component (B) is an acid amide obtained by reacting a carboxylic acid with an amine, and the carboxylic acid is From the viewpoint of the solubility of the resulting fatty acid amide compound in a synthetic ester base oil, it is preferably a linear or branched saturated or unsaturated fatty acid having 6 to 24 carbon atoms, more preferably 12 to 18 carbon atoms. be able to. Examples of such carboxylic acids include heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, icosanoic acid Saturated fatty acids such as helicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid (these saturated fatty acids may be linear or branched); heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecene Unsaturated fatty acids such as acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid (including oleic acid), nonadecenoic acid, icosenic acid, heicosenoic acid, docosenoic acid, tricosenoic acid, tetracosenoic acid (these unsaturated fatty acids) Is straight or branched At best, also the position of the double bond is also arbitrary); and others as mentioned, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, and oleic acid are preferable.
These carboxylic acids may be used alone or in combination of two or more when used as a raw material in an acid amidation reaction with amines.

  On the other hand, alkylamines, alkanolamines, polyalkylenepolyamines and the like can be used as amines. Here, as the alkylamine, for example, monomethylamine, monoethylamine, monopropylamine, monobutylamine, monopentylamine, monohexylamine, monoheptylamine, monooctylamine, monononylamine, monodecylamine, monoundecylamine , Monododecylamine, monotridecylamine, monotetradecylamine, monopentadecylamine, monohexadecylamine, monoheptadecylamine, monooctadecylamine, monononadecylamine, monoicosylamine, monohenicosylamine, mono Primary aliphatic amines such as tricosylamine and monotetracosylamine (the alkyl group may be linear or branched); dimethylamine, methylethylamine, diethylamine, methylpropylamine, ethyl Propylamine, dipropylamine, methylbutylamine, ethylbutylamine, propylbutylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecyl Secondary aliphatic alkylamines such as amine, dipentadecylamine, dihexadecylamine, diheptadecylamine, dioctadecylamine, dinonadecylamine, diicosylamine, dihenicosylamine, ditricosylamine, ditetracosylamine (The alkyl group may be linear or branched).

Examples of the alkanolamine include monomethanolamine, monoethanolamine, monopropanolamine, monobutanolamine, monopentanolamine, monohexanolamine, monoheptanolamine, monooctanolamine, monononanolamine, dimethanolamine, methanolethanol Amine, diethanolamine, methanolpropanolamine, ethanolpropanolamine, dipropanolamine, methanolbutanolamine, ethanolbutanolamine, propanolbutanolamine, dibutanolamine, dipentanolamine, dihexanolamine, diheptanolamine, dioctanolamine, etc. (The alkanol group may be linear or branched).
Examples of the polyalkylene polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, tetrapropylenepentamine, and hexabutyleneheptamine.
These amines may be used alone or in combination of two or more when used as a raw material in the acid amidation reaction with the carboxylic acid.

In the present invention, a desired fatty acid amide compound is obtained by dehydrating the carboxylic acid and the amine at a temperature of about 100 to 220 ° C. for about 1 to 40 hours, preferably in a nitrogen stream. Can do.
The base number of the fatty acid amide compound of the component (a) thus obtained is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more from the viewpoint of the antirust effect of iron and the suppression of hydrolysis of the synthetic ester base oil. Is more preferable. Moreover, although there is no restriction | limiting in particular in the upper limit, Usually, it is about 80 mgKOH / g.
In addition, the acid value of the fatty acid amide compound is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, from the viewpoint of inhibiting corrosion of non-ferrous metals and inhibiting hydrolysis of synthetic ester base oil.
In the lubricating oil composition of the present invention, the fatty acid amide compound of component (a) in the additive of component (B) may be used alone or in combination of two or more. Moreover, the content is selected in the range of 0.01-3 mass%. When the content is less than 0.01% by mass, the antirust property is insufficient and the hydrolysis-inhibiting effect on the synthetic ester base oil is inferior. In addition, the hydrolysis-inhibiting effect on the synthetic ester base oil is not exhibited so much, and the oxidation stability may be adversely affected. For these reasons, the preferred content of the fatty acid amide compound is in the range of 0.05 to 1% by mass.

In the lubricating oil composition of the present invention, the benzotriazole derivative of component (b) in the additive of component (B) comprises benzotriazoles and monoalkylamines or benzotriazoles, formaldehyde, monoalkylamines or dialkylamines. It can be obtained by reacting.
Examples of the benzotriazoles include benzotriazole and compounds in which 1 to 4 lower alkyl groups having 1 to 4 carbon atoms are introduced into the benzene ring of benzotriazole.
The monoalkylamine preferably has 4 to 22 carbon atoms in the alkyl group, such as monobutylamine, monopentylamine, monohexylamine, monoheptylamine, monooctylamine, monononylamine, monodecylamine, Monoundecylamine, monododecylamine, monotridecylamine, monotetradecylamine, monopentadecylamine, monohexadecylamine, monoheptadecylamine, monooctadecylamine, monononadecylamine, monoicosylamine .
On the other hand, the dialkylamine preferably has an alkyl group having 4 to 22 carbon atoms, such as dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine. , Ditridecylamine, ditetradecylamine, dipentadecylamine, dioctadecylamine, dinonadecylamine, diicosylamine and the like.
The alkyl group in the monoalkylamine and dialkylamine may be linear or branched, and the two alkyl groups in the dialkylamine may be the same or different.

Examples of the benzotriazole derivatives obtained by reacting benzotriazoles with monoalkylamines include 2-alkylbenzotriazoles in which 1 to 4 lower alkyl groups may be introduced on the benzene ring. Benzotriazole derivatives obtained by reacting benzotriazoles with formaldehyde and monoalkylamines or dialkylamines are 2-alkylaminos in which 1 to 4 lower alkyl groups may be introduced on the benzene ring, respectively. Mention may be made of methylbenzotriazoles or 2-dialkylaminomethylbenzotriazoles.
Examples of these benzotriazole derivatives include 2-octylbenzotriazole, 2-octyltolazole, 2-octylaminomethylbenzotriazole, 2-octylaminomethyltoltriazole, 2-dioctylaminomethylbenzotriazole, and 2-dioctylamino. Examples include methyl toltriazole and compounds in which the octyl group in the compound is replaced with another alkyl group.
The base number of the benzotriazole derivative of the component (b) is preferably 20 mgKOH / g or more, and more preferably 50 mgKOH / g or more, from the viewpoint of the corrosion inhibition effect of copper and the hydrolysis inhibition of the synthetic ester base oil. Although there is no restriction | limiting in particular in the upper limit, Usually, it is about 150 mgKOH / g.
In addition, the acid value of the benzotriazole derivative is preferably 30 mgKOH / g or less, and more preferably 10 mgKOH / g or less, from the viewpoint of suppressing hydrolysis of the synthetic ester base oil. Benzotriazole has an acid value as high as about 400 mgKOH / g and can suppress the corrosion of copper, but promotes the hydrolysis of the synthetic ester base oil.

In the lubricating oil composition of the present invention, the benzotriazole derivative of the component (b) in the additive of the component (B) may be used alone or in combination of two or more. Moreover, the content is selected in the range of 0.01-2 mass%. If this content is less than 0.01% by mass, the anticorrosion property of copper is insufficient. If it exceeds 2% by mass, the effect of copper anticorrosion is not so much improved, but rather oxidation stability. May cause adverse effects. For these reasons, the preferred content of the benzotriazole derivative is in the range of 0.05 to 0.5% by mass.
In the lubricating oil composition of the present invention, an antioxidant can be contained as the component (c) in the additive of the component (B) in order to further improve the oxidation stability.
As the antioxidant of component (c), any of phenol-based antioxidants and amine-based antioxidants can be used.

  There is no restriction | limiting in particular as phenolic antioxidant among the said (c) component, Arbitrary things are suitably selected from the well-known phenolic antioxidant currently used as antioxidant of lubricating oil. Can be used. Examples of the phenolic antioxidant include 2,6-di-tert-butyl-4-methylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,4,6-tri-tert- 2,6-di-tert-butyl-4-hydroxymethylphenol; 2,6-di-tert-butylphenol; 2,4-dimethyl-6-tert-butylphenol; 2,6-di-tert-butyl- 4- (N, N-dimethylaminomethyl) phenol; 2,6-di-tert-amyl-4-methylphenol; n-octadecyl 3- (4-hydroxy-3,5-di-tert-butylphenyl) propionate Monocyclic phenols such as 4,4′-methylenebis (2,6-di-tert-butylphenol); Propylidenebis (2,6-di-tert-butylphenol); 2,2′-methylenebis (4-methyl-6-tert-butylphenol); 4,4′-bis (2,6-di-tert-butylphenol); 4 4,4′-bis (2-methyl-6-tert-butylphenol); 2,2′-methylenebis (4-ethyl-6-tert-butylphenol); 4,4′-butylidenebis (3-methyl-6-tert- Butylphenol); 2,2′-thiobis (4-methyl-6-tert-butylphenol); polycyclic phenols such as 4,4′-thiobis (3-methyl-6-tert-butylphenol).

  On the other hand, the amine-based antioxidant in the component (c) is not particularly limited, and any known amine-based antioxidant conventionally used as an antioxidant for lubricating oils may be appropriately selected. It can be selected and used. Examples of the amine-based antioxidant include diphenylamine-based compounds, specifically diphenylamine and monooctyldiphenylamine; monononyldiphenylamine; 4,4′-dibutyldiphenylamine; 4,4′-dihexyldiphenylamine; 4,4′- 4,4′-dinonyldiphenylamine; tetrabutyldiphenylamine; tetrahexyldiphenylamine; tetraoctyldiphenylamine: alkylated diphenylamine having a C3-C20 alkyl group such as tetranonyldiphenylamine, and naphthylamine-based compounds, Specifically, α-naphthylamine; phenyl-α-naphthylamine, further butylphenyl-α-naphthylamine; hexylphenyl-α-naphthylamine; Phenyl -α- naphthylamine; and alkyl-substituted phenyl -α- naphthylamine having 3 to 20 carbon atoms such as nonylphenyl -α- naphthylamine.

In the present invention, as the component (c), one kind of the above-mentioned phenolic antioxidant may be used, two or more kinds may be used in combination, and one kind of the above-mentioned amine-based antioxidant may be used. Two or more types may be used in combination, and one or more phenolic antioxidants and one or more amine type antioxidants may be used in combination. A system antioxidant is preferred from the viewpoint of effect. Among the amine-based antioxidants, phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and a mixture of these phenyl-α-naphthylamine compounds and dialkyldiphenylamine are particularly preferable.
In the lubricating oil composition of the present invention, the content of the antioxidant of the component (c) is preferably 0.1 to 5% by mass from the viewpoint of balance between effect and economy, and 0.5 to 3%. The mass% is more preferable.
As long as the object of the present invention is not impaired, the lubricating oil composition of the present invention may optionally contain various additives such as a lubricity improver, a detergent dispersant, a viscosity index improver, a pour point depressant and an antifoaming agent. It can contain at least one kind selected from.

Examples of the lubricity improver include oily agents, phosphate ester compounds, sulfur compounds, and organometallic compounds.
Examples of the oily agent include aliphatic saturated and unsaturated monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, Aliphatic saturated and unsaturated monoalcohols such as lauryl alcohol and oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine and oleylamine, aliphatic saturated and unsaturated monocarboxylic amides such as lauric acid amide and oleic acid amide Can be mentioned.
The preferable compounding quantity of these oiliness agents is the range of 0.01-10 mass% on the basis of the composition whole quantity, and the range of 0.1-5 mass% is especially preferable.
Examples of phosphoric acid ester compounds include phosphoric acid esters, acidic phosphoric acid esters, acidic phosphoric acid ester amine salts, phosphorous acid esters, acidic phosphorous acid esters, and acidic phosphorous acid ester amine salts.

  Examples of the phosphate ester include triaryl phosphate, trialkyl phosphate, trialkylaryl phosphate, triarylalkyl phosphate, trialkenyl phosphate, and the like, 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, di (ethylphenyl) phenyl phosphate, propylphenyl diphenyl phosphate, di (propylphenyl) phenyl phosphate, triethylphenyl phosphate, tripropyl Phenyl phosphate, butyl phenol Rudiphenyl phosphate, di (butylphenyl) phenyl phosphate, tributylphenyl phosphate, trihexyl phosphate, tri (2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate, trio Examples include rail phosphate.

  Examples of the acid phosphate ester include di-2-ethylhexyl acid phosphate, didecyl acid phosphate, didodecyl acid phosphate (dilauryl acid phosphate), tridecyl acid phosphate, dioctadecyl acid phosphate (distearyl acid phosphate), di- 9-octadecenyl acid phosphate (dioleoyl acid phosphate) and the like. Examples of the phosphite ester include triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri (nonyl). Phenyl) phosphite, tri (2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphe Louis-Soviet decyl phosphite, tristearyl phosphite, and the like can be given trio rail phosphite.

Examples of acidic phosphites include di-2-ethylhexyl hydrogen phosphite, didecyl hydrogen phosphite, didodecyl hydrogen phosphite (dilauryl hydrogen phosphite), and dioctadecyl hydrogen phosphite (distearyl). Hydrogen phosphite), di-9-octadecenyl hydrogen phosphite (dioleyl hydrogen phosphite), diphenyl hydrogen phosphite and the like.
Examples of the acid phosphate amine salt and the acid phosphite amine salt include salts of the aforementioned acid phosphate ester and acid phosphite ester with the following amines. As the amines, mono-substituted amines, di-substituted amines or tri-substituted amines are used.

  Examples of monosubstituted amines include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine, benzylamine, etc. Examples of disubstituted amines include dibutylamine, Dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, dibenzylamine, stearyl monoethanolamine, decyl monoethanolamine, hexylpropanolamine, benzyl monoethanolamine, Phenyl monoethanolamine, tolyl monopropanolamine and the like. Examples of the tri-substituted amine include tributylamine, tripentylamine. , Trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleyl monoethanolamine, dilauryl monopropanolamine, dioctyl monoethanolamine, dihexyl monopropanol Amine, dibutyl propanolamine, oleyl diethanolamine, stearyl dipropanolamine, lauryl diethanolamine, octyl dipropanolamine, butyl diethanolamine, benzyl diethanolamine, phenyl diethanolamine, tolyl dipropanolamine, xylyl diethanolamine, triyl Examples include ethanolamine and tripropanolamine.

Acid phosphate ester amine salts such as monomethyl hydrogen phosphate, monoethyl hydrogen phosphate, monopropyl hydrogen phosphate, monobutyl hydrogen phosphate, mono-2-ethylhexyl hydrogen phosphate, etc. Salts with amines can also be used.
In this invention, this phosphate ester type compound may be used individually by 1 type, and may be used in combination of 2 or more type. The compounding quantity is about 0.1-3.0 mass% normally based on the composition whole quantity.

Examples of sulfur compounds include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiadiazole compounds, thiophosphate esters (thiophosphites, thiophosphates), alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, A dialkyl thiodipropionate compound etc. can be mentioned. These are usually used in a proportion of 0.01 to 2% by mass, preferably 0.05 to 1% by mass, based on the total amount of the composition.
Examples of the organometallic compound include zinc dithiophosphate (ZnDTP), zinc dithiocarbamate (ZnDTC), sulfurized oxymolybdenum organophosphorodithioate (MoDTP), and sulfurized oxymolybdenum dithiocarbamate (MoDTC). These compounding quantities are 0.05-5 mass% normally on the basis of the composition whole quantity, Preferably it is 0.1-3 mass%.

  Examples of the detergent / dispersant include succinimides, boron-containing succinimides, benzylamines, boron-containing benzylamines, succinates, fatty acids, and monovalent or divalent carboxylic acid amides represented by succinic acid. Ashless dispersants, neutral metal sulfonates, neutral metal phenates, neutral metal salicylates, neutral metal phosphonates, basic sulfonates, basic phenates, basic salicylates, overbased sulfonates, overbased salicylates And metal detergents such as overbased phosphonates. These compounding quantities are 0.1-20 mass% normally on the basis of the composition whole quantity, Preferably it is 0.5-10 mass%.

As the viscosity index improver, for example, polymethacrylate, dispersed polymethacrylate, olefin copolymer (for example, ethylene-propylene copolymer), dispersed olefin copolymer, styrene copolymer (for example, Styrene-diene hydrogenated copolymer, etc.).
The blending amount of these viscosity index improvers is usually about 0.5 to 35% by mass, preferably 1 to 15% by mass, based on the total amount of the lubricating oil composition, from the viewpoint of the blending effect.
As the pour point depressant, polymethacrylate having a weight average molecular weight of about 50,000 to 150,000 can be used.

As the antifoaming agent, a high molecular silicone antifoaming agent is preferable, and by including this high molecular silicone antifoaming agent, antifoaming properties are effectively exhibited.
Examples of the polymer silicone antifoaming agent include organopolysiloxane, and fluorine-containing organopolysiloxane such as trifluoropropylmethyl silicone oil is particularly suitable. The high molecular silicone antifoaming agent is preferably contained in an amount of about 0.0001 to 0.1% by mass based on the total amount of the composition from the viewpoint of a balance between the defoaming effect and economy, and 0.0005 to 0%. More preferably, the content is 0.05% by mass.

Next, the properties of the lubricating oil composition of the present invention will be described.
The lubricating oil composition has excellent biodegradability with a biodegradation rate of 60% or more in a chemical degradation test by microorganisms according to the OECD test guideline 301C method. Further, in an acute toxicity test against medaka based on JIS K 0102, the 96-hour LC ₅₀ value is usually 100 mg / L or more, and there is little influence on the living body. Thus, the lubricating oil composition is a very environmentally friendly lubricating oil.
The viscosity index is usually 100 or more, preferably 120 or more, the pour point is usually −40 ° C. or less, preferably −45 ° C. or less, and the flash point is usually 250 ° C. or more, preferably 260 ° C. or more. It is. Since the synthetic ester base oil of component (A) has a viscosity index of 120 or more, the lubricating oil composition usually does not require a viscosity index improver.
Since the lubricating oil composition has a low pour point as described above, when used as a hydraulic oil, the startability of the machine at a low temperature is good, and since it has a high flash point, the flame retardancy is high. VG32 and above are classified as flammable liquids.

The biodegradable lubricating oil composition of the present invention is excellent in biodegradability, has little influence on the living body, has a high viscosity index, a low pour point, and a high flash point, and has good lubricating performance, iron, white metal It has excellent anti-corrosion, anti-corrosion, non-ferrous metal, hydrolytic stability and oxidation stability that can withstand long-term use, such as hydro turbine bearing oil, steam turbine oil, gas turbine oil, hydraulic fluid It can be applied to compressor oil, bearing oil for various industrial machines, hydraulic fluid and sliding surface oil for machine tools.
The lubricating oil composition of the present invention is suitable for bearings, and particularly suitable for bearings for hydroelectric power turbines (hydropower turbines).

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the property of the lubricating oil composition in each example was calculated | required in accordance with the method shown below.
(1) General properties (a) Kinematic viscosity at 40 ° C. Measured according to JIS K 2283.
(B) Viscosity index Measured according to JIS K 2283.
(C) Acid value Measured according to JIS K 2501.
(D) Base number Measured according to JIS K 2501.
(E) Flash point Measured according to JIS K 2265 using a Cleveland open-type (COC) tester.

(2) Biodegradability The biodegradability is measured according to the modified MITI test method “OECD301C”. In addition, according to the Eco Mark certification standard revised in July 1998, the biodegradation rate is required to be 60% or more.
(3) Acute toxicity to fish In accordance with JIS K 0102, Himedaka is used as a test fish, and the half-lethal concentration LC ₅₀ value after 96 hours is measured. The Eco Mark certification standard revised in July 1998 requires the LC ₅₀ value to be 100 mg / L or more.
(4) Rust prevention performance In accordance with JIS K 2510, the state of rust occurrence after 24 hours at 60 ° C. is observed using distilled water.
(5) Hydrolysis test A hydrolysis test is performed according to ASTM2619-95.
Put 75g of sample oil, 25g of distilled water and copper plate catalyst (15x55x2mm) into a glass bottle. After sealing, set it in a sample holder that rotates in the vertical direction in a thermostatic chamber and test at 100 ° C for 168 hours. After separation into an oil layer and a water tank, the acid value of the oil and the copper concentration of the water layer are measured.
(6) White metal soaking test White metal (WJ2; 10 x 50 x 5 mm) is soaked in 50 g of sample oil whose water content is adjusted to 1000 ppm, sealed, and then allowed to stand at 80 ° C for 3000 hours in a thermostatic bath. To do. Then, the acid value of oil, the amount of metal, and the presence or absence of corrosion of the white metal surface are measured.
(7) Oxidation stability Measured according to the JIS K 2514 turbine oil oxidation stability test (however, water is not added).
300 mL of sample oil; an iron-copper coiled catalyst is put in a cylinder and tested at a temperature of 130 ° C. and an oxygen blowing rate of 3 L / h. Take 10 mL of sample oil every 120 hours and measure the acid value. The time when the increase in acid value reaches 2 mgKOH / g is defined as the lifetime. However, for sample oils with poor oxidation stability, sample oils were sampled appropriately (every 24 hours or 48 hours) and the acid value was measured.

Examples 1-5 and Comparative Examples 1-5
While preparing lubricating oil compositions having the compositions shown in Table 1 and Table 1, commercial oils were prepared. The properties of the lubricating oil composition and commercial oil are shown in Table 1 and Table 1.

[note]
TMP-FE1; a reaction product of trimethylolpropane and a C10, C12 linear fatty acid, having a triester structure, acid value 0.04 mgKOH / g
TMP-FE2: a reaction product of trimethylolpropane and a branched fatty acid having 18 carbon atoms, having a triester structure, acid value of 0.1 mgKOH / g
TMP-DE; a reaction product of trimethylolpropane and a branched fatty acid having 18 carbon atoms, having a diester structure, acid value of 0.1 mgKOH / g
Fatty acid amide 1; reaction product of isostearic acid and tetraethylenepentamine, base number 74 mgKOH / g, acid value 5 mgKOH / g
Fatty acid amide 2; reaction product of oleic acid and diethanolamine, base number 27 mgKOH / g, acid value 0.4 mgKOH / g
BZT-D: benzotriazole derivative, 1- [N, N-bis (2-ethylhexyl) aminomethyl] -4-methyl-benzotriazole, base value 142 mgKOH / g, acid value 10 mgKOH / g
APNA: alkylphenyl-α-naphthylamine (alkyl group of alkylphenyl: carbon number 8)
Phenol type; Phenol type antioxidant, 2,6-di-tert-butyl-4-ethylphenol Antifoaming agent; Silicone type antifoaming agent (trade name “FL100” manufactured by Shin-Etsu Chemical Co., Ltd.)

As can be seen from Table 1, the lubricating oil compositions of the present invention (Examples 1 to 5) all have a high biodegradation rate and low toxicity to medaka, as well as good rust prevention and hydrolysis stability. It has anti-corrosion properties against white metal and has excellent oxidation stability that can withstand long-term use.
On the other hand, in the comparative example, at least one of the items of rust prevention, hydrolysis stability, anticorrosion against white metal, and oxidation stability is poor.

  The biodegradable lubricating oil composition of the present invention is excellent in biodegradability, and also has anti-corrosion and anti-corrosion properties against non-ferrous metals such as iron and white metal, hydrolytic stability, and oxidation stability that can withstand long-term use. It is also excellent for hydroelectric turbine bearing oil, steam turbine oil, gas turbine oil, hydraulic hydraulic oil, compressor oil, bearing oil for various industrial machines, hydraulic hydraulic oil / sliding surface oil for machine tools, etc. be able to.

Claims (11)

(A) Aliphatic hindered polyols having one or more quaternary carbons in the molecule and 1 to 4 methylol groups bonded to at least one of the quaternary carbons, and aliphatic monocarboxylic acids A synthetic ester base oil containing 90% by mass or more of a hindered ester, and 0.01 to 2% by mass of (B) (a) a fatty acid amide compound and 0.01 to 2% by mass of (b) a benzotriazole derivative. And a biodegradable lubricating oil composition characterized by having a biodegradation rate of 60% or more. The biodegradable lubricating oil composition according to claim 1, further comprising (c) 0.1 to 5% by mass of an antioxidant as the component (B).   The biodegradable lubricating oil composition according to claim 2, wherein the antioxidant is an amine-based antioxidant. The biodegradable lubricating oil composition according to any one of claims 1 to 3, which has a 96-hour LC ₅₀ value of 100 mg / L or more in an acute toxicity test against medaka based on JIS K 0102. The aliphatic hindered polyols constituting the hindered ester in the component (A) are represented by the general formula (I)

(Wherein, R ¹ and R ² each independently represent a hydrocarbon group or a methylol group having 1 to 6 carbon atoms, n represents an integer of 0 to 4.)
The biodegradable lubricating oil composition according to claim 1, which is a compound represented by the formula:   The biodegradable lubricating oil composition according to claim 5, wherein the aliphatic hindered polyol is trimethylolpropane, neopentyl glycol, pentaerythritol or a dehydrated condensate thereof. The biodegradable lubricating oil composition according to any one of claims 1 to 6, wherein the aliphatic monocarboxylic acids constituting the hindered ester in the component (A) are saturated fatty acids having 5 or more carbon atoms. The biodegradable lubricating oil composition according to any one of claims 1 to 7, wherein the base number of the fatty acid amide compound (B) (a) is 10 mgKOH / g or more. The biodegradable lubricating oil composition according to any one of claims 1 to 8, wherein the base number of the benzotriazole-based derivative as the component (B) or (b) is 20 mgKOH / g or more.   The biodegradable lubricating oil composition according to any one of claims 1 to 9, which is used for bearings.   The biodegradable lubricating oil composition according to claim 10, which is used as a bearing for a hydroelectric power generation turbine.