JP7107741B2 - Turbine oil composition - Google Patents

Description

The present invention relates to turbine oil compositions.

In recent years, the importance of environmental conservation has increased, and lubricating oils used in equipment and facilities that are used outdoors or in the natural environment may be discharged into the natural environment during or after use. The number of cases where is required is increasing.
In recent years, turbine oil for generators used in facilities in the natural environment such as hydroelectric power plants, geothermal power plants, wind power plants, etc. near rivers or lakes, is being protected against possible leakage, etc. There is a growing demand for degradability.

In such cases, the Eco Mark Certification Standards established by the Japan Environment Association are used as an indicator of the biodegradability of lubricating oils. In the case of lubricating oil, Eco Mark Product Category No. 110, and products that have acquired the Eco Mark according to the certification standard "Biodegradable Lubricant Version 2.6" are generally recognized as biodegradable lubricants and are in widespread use. According to this "Biodegradable Lubricating Oil Version 2.6", in order to acquire the Eco Mark, biodegradability must be 60% or more within 28 days by any of the following test methods. is one of the requirements.
That is, the biodegradability within 28 days is required to be 60% or more in any one test method among OECD301B, 301C, 301F, ASTM D5864, and D6731.

In general, as a method for improving the biodegradability of lubricating oils, there are many cases in which highly biodegradable base oils are used as the base oil, which is the main component, and polyol ester base oil is used as turbine oil for hydroelectric power generation. There is known a technique in which biodegradability is improved by using a method (see, for example, Patent Document 1).

In many cases , turbine oil is replaced during regular maintenance of power generation equipment that has been in continuous operation for a long period of time. Basic performance such as thermal oxidative stability, anti-sludging and hydrolytic stability to withstand, corrosion resistance to metallic materials used in turbine bearings are of course also emphasized.

Therefore, when improving the biodegradability of turbine oil, it is necessary to ensure these basic performances.

As a turbine oil composition having excellent biodegradability, a low pour point, and excellent thermal oxidation stability, for example, (A) a polyhydric alcohol residue, a linear saturated fatty acid residue and a linear saturated polycarboxylic acid and a complex ester having a kinematic viscosity at 40° C. of 20 to 100 mm ² /s and a pour point of −40° C. or lower; and (B) an antioxidant. , a turbine oil composition characterized by containing 60% by mass or more of (A) in the base oil (see, for example, Patent Document 2).
In addition, the base oil contains (A) a trimethylolpropane residue, a C8 straight-chain saturated fatty acid, a C10 straight-chain saturated fatty acid, a C12 straight-chain saturated fatty acid, a C14 straight-chain saturated fatty acid, and a C16 straight-chain saturated fatty acid. A complex consisting of a linear saturated fatty acid residue and an adipic acid residue of a mixture of two or more of the above, and having a kinematic viscosity at 40°C of 32 to 68 mm ² /s and a pour point of -40°C or less A turbine oil composition for hydroelectric power generation equipment of a hydroelectric power plant is disclosed, which is characterized by being an ester and containing (B) an antioxidant (see, for example, Patent Document 3).

Japanese Patent Application Laid-Open No. 2008-115301 JP 2014-055284 A Japanese Patent No. 6114961

When an ester base oil is used in turbine oil to improve biodegradability, it has sometimes been difficult to ensure these basic performances.
As in the above Patent Documents 1 to 3, in order to improve biodegradability, it is mainstream to use fatty acid ester as the base oil of lubricating oil, but when water is mixed in turbine oil, hydrolysis There is concern that the acid value of the oil will increase and the life of the turbine oil will be shortened, and further improvements are required.
Accordingly, an object of the present invention is to provide a turbine oil composition that is excellent in biodegradability, thermooxidative stability, and hydrolytic stability in order to solve the above problems.

As a result of extensive research, the present inventors have found that the above problems can be solved by including a specific polyol ester as the base oil component, and have completed the present invention.

That is, the means for solving the above problems includes the following embodiments.
<1> It consists of an alcohol residue having a neopentyl structure and a saturated fatty acid residue of a mixture of a linear saturated fatty acid having 7 to 11 carbon atoms and a branched saturated fatty acid having 16 to 20 carbon atoms, and at 40 ° C. A turbine oil containing a base oil component containing a polyol ester having a kinematic viscosity of 32 mm ² /s to 68 mm ² /s, and 0.05% by mass to 0.15% by mass of a carbodiimide compound as a hydrolysis inhibitor. Composition.
<2> The turbine oil composition according to <1>, further containing at least one selected from the group consisting of antioxidants, demulsifiers, rust inhibitors and corrosion inhibitors.
<3> The turbine oil composition according to <1> or <2>, which has a biodegradability of 60% or more according to the OECD301B method or the OECD301C method <4> It is for hydroelectric power generation facilities, <1> to <3> The turbine oil composition according to any one of

According to the present invention, it is possible to provide a turbine oil composition that is excellent in biodegradability, thermooxidative stability, and hydrolytic stability.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below.
In this specification, "-" representing a numerical range represents a range including the numerical values described as the upper limit and the lower limit. In addition, when only the upper limit value in the numerical range represented by "-" is described in units, it means that the lower limit value is also in the same unit.
In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described stepwise.
In the present specification, the content rate or content of each component in the composition refers to, when there are multiple types of substances corresponding to each component in the composition, the multiple types of substances present in the composition unless otherwise specified. means the total content or content of a substance.
Combinations of preferred aspects are more preferred aspects herein.

<<turbine oil composition>>
The turbine oil composition of the present invention consists of an alcohol residue having a neopentyl structure and a saturated fatty acid residue of a mixture of linear saturated fatty acids with 7 to 11 carbon atoms and branched saturated fatty acids with 16 to 20 carbon atoms. and a base oil containing a polyol ester having a kinematic viscosity at 40° C. of 32 mm ² /s to 68 mm ² /s, and 0.05% to 0.15% by mass of a carbodiimide compound as a hydrolysis inhibitor, contains
The turbine oil composition of the present invention is excellent in biodegradability, thermo-oxidative stability and hydrolytic stability due to the above constitution. The reason for this is not clear, but is presumed as follows.

A typical viscosity grade of turbine oil is VG46 (41.4 mm ² /s to 50.6 mm ² /s in kinematic viscosity at 40°C). When trying to prepare a turbine oil with a high kinematic viscosity grade of about VG46 using a polyol ester base oil, it is necessary to increase the molecular weight of the ester. In this case, in order to secure a low pour point while securing a high kinematic viscosity (that is, a large molecular weight), it is necessary to use a linear unsaturated fatty acid with a large molecular weight or use a branched saturated fatty acid with a large molecular weight. . However, when a straight-chain unsaturated fatty acid is used, the biodegradability is good, but the thermo-oxidative stability is low. Although it is good, there is a problem that biodegradability is low, and there is a trade-off relationship between biodegradability and thermo-oxidative stability.
The turbine oil composition of the present invention uses a polyol ester obtained by combining an alcohol having a neopentyl structure, a linear saturated fatty acid having 7 to 11 carbon atoms and a branched saturated fatty acid having 16 to 20 carbon atoms, while hydrolyzing By adding a specific amount of a carbodiimide compound as an inhibitor, biodegradability, thermal oxidation stability and hydrolysis stability are all excellent. Moreover, the turbine oil composition of the present invention can ensure a high kinematic viscosity of about VG46 in spite of containing a polyol ester as a base oil component.
Each component constituting the turbine oil composition of the present invention will be described below.

<Base oil content>
The turbine oil composition of the present invention comprises, as a base oil, an alcohol residue having a neopentyl structure, and a saturated fatty acid residue of a mixture of a linear saturated fatty acid having 7 to 11 carbon atoms and a branched saturated fatty acid having 16 to 20 carbon atoms. And contains a polyol ester (hereinafter also referred to as "specific polyol ester") consisting of.
In the present specification, the number of carbon atoms in straight-chain saturated fatty acids and branched-chain saturated fatty acids means the total number of carbon atoms including carbon atoms forming ester bonds.

The specific polyol ester, which is the base oil component of the turbine oil composition of the present invention, is an ester produced by reacting an alcohol with a carboxylic acid or a carboxylic acid derivative. That is, the specific polyol ester consists of an alcohol residue derived from an alcohol and an acid residue derived from a carboxylic acid, and the alcohol residue is an alcohol residue having a neopentyl structure in which the alcohol residue is a polyhydric alcohol residue, and the acid residue is straight-chain saturated fatty acid residues and branched-chain saturated fatty acid residues.
That is, the specific polyol ester is an ester having an alcohol residue having a neopentyl structure as an alcohol residue and having both a linear saturated fatty acid residue and a branched saturated fatty acid residue as an acid residue. .

The specific polyol ester contains an alcohol residue having a neopentyl structure as an alcohol residue, so that it is easy to obtain an appropriate viscosity and a low pour point as a base oil, and also has biodegradability and thermal oxidation stability. easily compatible.
Moreover, since the alcohol residue having a neopentyl structure is a hindered alcohol residue having a structure in which there is no hydrogen at the β-position of the ester group, thermal decomposition of the specific polyol ester hardly occurs.

In the specific polyol ester, the linear saturated fatty acid residue has 7 to 11 carbon atoms.
When the linear saturated fatty acid residue has 7 to 11 carbon atoms, the molecular weight of the specific polyol ester is not too small, the desired pour point and viscosity for turbine oil can be obtained, and biodegradability can also be obtained. Moreover, since the straight-chain fatty acid residue is a saturated fatty acid residue, it is excellent in thermooxidative stability.

In the specific polyol ester, the linear saturated fatty acid residue preferably has a valence of one.
Further, as used herein, the valence of linear saturated fatty acid residues and branched saturated fatty acid residues refers to the number of ester bonds formed by linear saturated fatty acid residues or branched saturated fatty acid residues. .

In the synthesis of the specific polyol ester, the carboxylic acid or carboxylic acid derivative that becomes a linear saturated fatty acid residue having 7 to 11 carbon atoms by reaction with an alcohol having a neopentyl structure is an acid residue by reaction with an alcohol having a neopentyl structure. Carboxylic acids or carboxylic acid derivatives such as straight-chain saturated fatty acids, straight-chain saturated fatty acid chlorides, straight-chain saturated fatty acid esters, etc., having 7 to 11 carbon atoms in the base portion may be mentioned.
The carboxylic acid or carboxylic acid derivative that becomes the linear saturated fatty acid residue may be used singly or in combination of two or more.

In the specific polyol ester, the branched saturated fatty acid residue has 16 to 20 carbon atoms. When the number of carbon atoms in the branched saturated fatty acid residue is 16 to 20, the molecular weight of the specific polyol ester is increased, so that the desired pour point and viscosity for turbine oil can be easily obtained. Excellent prevention. Moreover, since the branched-chain fatty acid residue is a saturated fatty acid residue, it is excellent in thermooxidative stability.
In the specific polyol ester, the branched saturated fatty acid residue preferably has a valence of one.

If the specific polyol ester has a kinematic viscosity at 40° C. of 32 mm ² /s to 68 mm ² /s, the alcohol residue having a neopentyl structure, a linear fatty acid residue having 7 to 11 carbon atoms, and 16 to 16 carbon atoms The ratio of 20 branched chain fatty acid residues and the molecular weight of the specific polyol ester are not particularly limited.
In addition, if the kinematic viscosity of the specific polyol ester at 40° C. is 32 mm ² /s to 68 mm ² /s, the reaction conditions and the type of process for producing the specific polyol ester are not particularly limited.

In the specific polyol ester, the ratio of linear saturated fatty acid and branched saturated fatty acid (straight chain saturated fatty acid: branched saturated fatty acid) is appropriate from the viewpoint of kinematic viscosity, biodegradability, thermooxidative stability and hydrolytic stability , 85-35: 15-65 , more preferably 75-45:25-55, even more preferably 65-55:35-45.

<Kinematic viscosity at 40°C>
The kinematic viscosity at 40° C. of the specific polyol ester is 32 mm ² /s to 68 mm ² /s. When the kinematic viscosity at 40°C is within the above range, a sufficient oil film can be maintained, and by suppressing an increase in viscosity when the turbine oil is prepared by blending additives, flow resistance and agitation are improved. Since the resistance is reduced, the power loss and the temperature rise of the turbine bearing metal can be suppressed.
From the above viewpoint, the kinematic viscosity at 40° C. of the specific polyol ester is preferably 32 mm ² /s to 68 mm ² /s, more preferably 39 mm ² /s to 57 mm ² /s.
The kinematic viscosity at 40°C can be determined according to JIS K 2283 (2000) "Kinematic Viscosity Test Method".

<Kinematic viscosity at 100°C>
The kinematic viscosity at 100° C. of the specific polyol ester is preferably 5 mm ² /s to 10 mm ² /s.
From the viewpoint of lubricity, the kinematic viscosity at 100° C. of the specific polyol ester is preferably 6 mm ² /s to 9 mm ² /s, more preferably 6.5 mm ² /s to 8.5 mm ² /s. .

The pour point of the specific polyol ester is preferably −40° C. or lower, more preferably −45° C. or lower.
When the pour point of the specific polyol ester is −40° C. or less, it is possible to maintain a sufficient oil film, and by suppressing the increase in viscosity when preparing turbine oil by blending additives, Since the resistance and stirring resistance are reduced, power loss and temperature rise of the turbine bearing metal can also be suppressed.

The iodine value of the specific polyol ester is preferably 2 gI ₂ /100 g or less, more preferably 1 gI ₂ /100 g or less.
When the iodine value of the specific polyol ester is 2 gI ₂ /100 g or less, it is more excellent in thermal oxidation stability.

The acid value of the specific polyol ester is preferably 5 mgKOH/g or less, more preferably 3 mgKOH/g or less, still more preferably 1 mgKOH/g or less. When the acid value of the specific polyol ester is within the above range, the anti-emulsibility is enhanced, and corrosion of metal materials such as bearings can be suppressed.

The turbine oil composition of the present invention may contain a base oil other than the specific polyol ester (hereinafter also referred to as "other base oil") as a base oil component.
Other base oils are not particularly limited as long as they do not impair the biodegradability and thermo-oxidative stability of the turbine oil composition.
Other base oils include, for example, monoesters, diesters, polyol esters, polyglycols, etc. that do not have straight-chain saturated fatty acid residues of 7 to 11 carbon atoms and branched-chain saturated fatty acid residues of 16 to 20 carbon atoms. mentioned.
Polyglycols include, for example, polyethylene oxide.

In the turbine oil of the present invention, the content of the specific polyol ester in the base oil ((specific polyol ester content/total base oil content) x 100) is 60% by mass or more, preferably 70% by mass or more, and more It is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more.
In terms of improving biodegradability and improving various performances as a turbine oil, it is preferable that the content of other base oils is small. It is more preferable to have

<Hydrolysis inhibitor>
The turbine oil composition of the present invention contains a carbodiimide compound as a hydrolysis inhibitor.
The carbodiimide compound is not particularly limited as long as it is a compound containing a carbodiimide group in one molecule, and examples thereof include monocarbodiimide compounds, polycarbodiimide compounds, cyclic carbodiimide compounds, and the like.
Among these, a monocarbodiimide compound is preferable as the carbodiimide compound.
Examples of monocarbodiimide compounds include dicyclohexylcarbodiimide and bis-2,6-diisopropylphenylcarbodiimide.
Bis-2,6-diisopropylphenyl carbodiimide is preferred as the carbodiimide compound from the viewpoint of superior hydrolysis resistance.

The content of the carbodiimide compound is 0.05% by mass to 0.15% by mass with respect to the total mass of the turbine oil composition. When the content of the carbodiimide compound is within the above range, the hydrolysis-preventing effect can be exhibited without greatly reducing the biodegradability.
From the above viewpoint, the content of the carbodiimide compound should be 0.08% by mass to 0.08% by mass with respect to the total mass of the turbine oil composition. 12% by mass is preferred.

<Additive>
The turbine oil composition of the present invention preferably further contains at least one selected from the group consisting of antioxidants, demulsifiers, rust inhibitors and corrosion inhibitors.

(Antioxidant)
As the antioxidant, an ashless antioxidant is preferable because the antioxidant itself is less prone to sludging.
Ashless antioxidants are chain terminators that absorb radicals, and include, for example, alkylated aromatic antioxidants such as alkylbenzenes and alkylnaphthalenes, phenolic antioxidants, and amine antioxidants.
Among these, from the viewpoint of thermal oxidation stability, the antioxidant is preferably a phenol-based antioxidant and an amine-based antioxidant.
When the antioxidant is a phenolic antioxidant or an amine antioxidant, either one of the phenolic antioxidant and the amine antioxidant may be used, or they may be used in combination.

Phenolic antioxidants include, for example, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, monocyclic phenols such as 2,4,6-tri-methylphenol, 2,6-di-methyl-4-ethylphenol and 2,4-di-methyl-6-t-butyl-phenol; 4,4' -bis(2,6-di-t-butylphenol), 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-ethylenebis(2,6-di-t-butylphenol) , 4,4'-butylenebis(2,6-di-t-butylphenol), 6,6'-methylenebis(2-di-t-butyl-4-methylphenol) and other bisphenols; 4,4'thiobis- Sulfur-containing phenols such as (2,6-di-t-butyl-phenol), 4,4'thiobis-(2-methyl-6-t-butyl-phenol); represented by the following general formula (1) Ester group-containing phenols; sulfur- and ester group-containing phenols represented by the following general formula (2) or the following general formula (3).

In general formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ³ is a It is an alkylene group, R ⁴ is an alkyl group having 1 to 20 carbon atoms, and n is an integer of 1 to 4.

In general formula (2), R ⁵ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ⁶ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁷ is a is an alkylene group, A ¹ is a sulfur atom or a sulfide group having 1 to 20 carbon atoms, and n is an integer of 1 to 4;

In general formula (3), R ⁸ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ⁹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ¹⁰ is a is an alkyl group, A ² is a sulfur atom or a sulfide group having 1 to 20 carbon atoms, and n is an integer of 1 to 4;

Among these, monocyclic phenolic antioxidants, bisphenolic antioxidants, and ester group-containing phenolic antioxidants are preferred as phenolic antioxidants.
In the case of an ester group-containing phenolic antioxidant, in general formula (1), R ¹ and R ² are preferably C 1-4 alkyl groups, more preferably isoalkyl groups, and still more preferably t-butyl groups. In general formula (1), those in which both R ¹ and R ² are other than hydrogen atoms are likely to be stabilized when a radical is captured. Further, R ³ is preferably an alkylene group having 1 to 18 carbon atoms. When the carbon number of R ³ is 18 or less, the solubility is excellent. Also, R ⁴ is preferably an alkyl group having 1 to 18 carbon atoms. When the oxygen number of R ⁴ is 18 or less, the solubility is excellent. Also, n is preferably 1 or 2. When n is 4 or less, the oil solubility increases.
Phenolic antioxidants may be used singly or in combination of two or more.

The content of the phenolic antioxidant in the turbine oil composition of the present invention is preferably 0.01% by mass to 3% by mass, more preferably 0.1% by mass to It is 2% by mass. When the content of the phenolic antioxidant in the turbine oil composition is within the above range, it is possible to suppress the generation of sludge and exhibit an antioxidant effect while maintaining biodegradability.

Specific examples of amine antioxidants include naphthylamine compounds such as phenyl-α-naphthylamine; diphenylamine compounds such as alkylated diphenylamine represented by the following general formula (4); N,N-di-t phenylenediamine compounds such as -butyl-p-phenylenediamine; heteroatom-containing aromatic amine compounds such as phenothiazine; these are hindered amine compounds in which the amino group is shielded with an aromatic ring, a t-butyl group, or the like; be.

In general formula (4), R ¹¹ is a hydrogen atom or an alkyl group having 1 to 24 carbon atoms, and R ¹² is a hydrogen atom or an alkyl group having 1 to 24 carbon atoms.

Among these, the amine-based antioxidant is preferably a naphthylamine compound, a diphenylamine compound or a phenylenediamine compound, more preferably a diphenylamine compound.
When the amine antioxidant is a diphenylamine compound, both R ¹¹ and R ¹² in general formula (4) are preferably alkyl groups having 1 to 18 carbon atoms, and both are preferably alkyl groups having 1 to 12 carbon atoms. is more preferably an alkyl group of If the number of carbon atoms in R ¹¹ or R ¹² is 24 or less, fluidity will be high. Moreover, it is more preferable that R ¹¹ and R ¹² contain an alkyl group having a branched chain.
Amine-based antioxidants may be used singly or in combination of two or more.

The content of the amine antioxidant is preferably 0.01% by mass to 3% by mass, more preferably 0.1% by mass to 2% by mass, relative to the total mass of the turbine oil composition.
When the content of the amine-based antioxidant in the turbine oil composition of the present invention is within the above range, the generation of sludge can be suppressed, and the antioxidant effect can be exhibited while maintaining biodegradability. .

When a phenolic antioxidant and an amine antioxidant are used in combination, the content ratio of the phenolic antioxidant and the amine antioxidant is preferably 10:1 to 1:10, preferably 5:1. ~1:5 is more preferred, and 3:1 to 1:3 is even more preferred.

When the turbine oil composition of the present invention contains antioxidants, the total content of antioxidants in the turbine oil composition is preferably 0.01% by mass to 3% by mass relative to the total mass of the turbine oil composition. % by mass, more preferably 0.1 to 2% by mass.

(Anti-emulsifier)
The main component of the demulsifier is a surfactant, and the demulsifier is preferably a nonionic surfactant, more preferably a polyalkylene glycol.
Examples of polyalkylene glycol include homopolymers obtained by polymerizing ethylene glycol, propylene glycol, or butylene glycol as monomers, and copolymers obtained by polymerizing these in combination. The homopolymer and copolymer may be used singly or in combination of two or more.
The nonionic surfactant is preferably a copolymer polymerized by combining ethylene glycol, propylene glycol or butylene glycol as monomers, and ethylene oxide-propylene oxide polymerized by combining ethylene glycol and propylene glycol. A copolymer is more preferred.

The weight average molecular weight of the demulsifier is preferably from 100 to 20,000, more preferably from 1,000 to 15,000. When the main component is an ethylene oxide-propylene oxide copolymer, the molar ratio of ethylene oxide:propylene oxide is preferably 20:1 to 1:10, more preferably 10:1 to 1:5.

The content of the demulsifier is preferably 0.001% by mass to 0.2% by mass, more preferably 0.005% by mass to 0.1% by mass, based on the total mass of the turbine oil composition.
When the content of the demulsifying agent is within the above range, the demulsifying effect is likely to be obtained.

(rust inhibitor)
The rust inhibitor is preferably an oil-soluble rust inhibitor that is contained for the purpose of preventing rusting at locations where iron-based materials are used.
Examples of oil-soluble rust inhibitors having a structure having an alkyl group responsible for oil solubility and a functional group that adsorbs to a metal surface include metallic soaps such as sulfonate metal salts and naphthenic acid metal salts, alkyl succinic acid derivatives, alkenyl succinic acid derivatives, lanolin compounds, surfactants such as sorbitan monooleate and pentaerythritol monooleate, waxes, oxidized waxes, petrolatum, N-oleyl sarcosine, rosinamine, alkylated amines such as dodecylamine and octadecylamine compounds, fatty acids such as oleic acid and stearic acid, and phosphorus compounds such as phosphite.

Among these, alkylsuccinic acid derivatives, alkenylsuccinic acid derivatives, surfactants other than demulsifiers, or alkylated amine compounds are preferred as rust inhibitors, and alkylsuccinic acid derivatives or alkenylsuccinic acid derivatives are more preferred. Preferred are alkenyl succinic acid half esters.
When the rust inhibitor is an alkenyl succinic acid half ester, it preferably has an acid value of 100 mgKOH/g or more.
These rust inhibitors may be used singly or in combination of two or more.

When the turbine oil composition of the present invention contains a rust inhibitor, the content of the rust inhibitor is preferably 0.001% by mass to 1% by mass, more preferably 0.001% by mass to 1% by mass, more preferably It is 0.01% by mass to 0.5% by mass.
When the content of the rust inhibitor is within the above range, it is possible to suppress the generation of sludge and maintain the biodegradability while exhibiting the rust inhibitor effect.

(corrosion inhibitor)
Corrosion inhibitors are mainly non-ferrous metal materials and are added for the purpose of preventing corrosion at locations where copper-based or lead-based materials are used, and are also called metal deactivators. Corrosion inhibitors also function indirectly as antioxidants by suppressing the catalytic action of metals.

The corrosion inhibitor is not particularly limited as long as it is a compound that exhibits a corrosion inhibitory effect by forming a film on the metal surface. Examples include benzotriazole and its derivatives, indazole and its derivatives, benzimidazole and its derivatives. , indole and its derivatives, thiadiazole and its derivatives, and the like.
Among these, benzotriazole and its derivatives, and thiadiazole and its derivatives are preferable as corrosion inhibitors. Among corrosion inhibitors, those having low oil solubility such as benzotriazole may be used as a mixture dissolved in a fatty acid, an amine compound, mineral oil, or the like.
Corrosion inhibitors may be used singly or in combination of two or more.

When the turbine oil composition of the present invention contains a corrosion inhibitor, the content of the corrosion inhibitor is preferably 0.001% by mass to 0.5% by mass, more than It is preferably 0.01% by mass to 0.2% by mass.
When the content of the corrosion inhibitor is within the above range, it is possible to suppress the generation of sludge and exhibit the corrosion prevention effect while maintaining biodegradability.

When the turbine oil composition of the present invention contains antioxidants, demulsifiers, rust inhibitors and corrosion inhibitors, the sum of the antioxidants, demulsifiers, rust inhibitors and corrosion inhibitors in the turbine oil composition The content is preferably 0.1% by mass to 5% by mass, more preferably 0.5% by mass to 3% by mass, relative to the total mass of the turbine oil composition.
When the total content of the antioxidant, demulsifier, rust inhibitor and corrosion inhibitor in the turbine oil composition is within the above range, thermal oxidation is suppressed while sludge generation is suppressed and biodegradability is maintained. Performance as a turbine oil, such as stability and corrosion resistance, can be easily obtained.

In addition to the antioxidant, demulsifier, rust inhibitor, and corrosion inhibitor components, the turbine oil composition of the present invention contains other components in appropriate amounts as necessary within a range that does not impair the effects of the present invention. be able to.
Other components include, for example, kerosene fractions, mineral base oils such as solvent-refined mineral oils, hydrorefined mineral oils, and hydrocracked mineral oils; olefinic base oils such as poly-α-olefins and olefin-copolymers and polybutene; Glycol-based base oils such as polyalkylene glycol, and other base oils such as phenyl ether-based base oils are included.

Other components include, for example, components used in ordinary lubricating oil compositions, such as detergents, dispersants, pour point depressants, viscosity index improvers, antifoaming agents, antiwear agents, friction modifiers, Other additives such as extreme pressure agents, oiliness agents, and surfactants other than the above demulsifiers are included.

Detergents include, for example, sulfonates, phenates, salicylates, and the like.
Examples of the dispersant include alkenylsuccinimide and boron compound derivatives of alkenylsuccinimide.
Pour point depressants include, for example, polymethacrylates.
Viscosity index improvers include, for example, polymethacrylates, olefin copolymers, and the like.

(Antifoaming agent)
The antifoaming agent is not particularly limited, and examples thereof include silicone antifoaming agents such as dimethylsilicone and fluorine-modified silicone, and ester antifoaming agents such as polyacrylate.
From the viewpoint of antifoaming properties, among these, the antifoaming agent is preferably a silicone-based antifoaming agent, and more preferably dimethyl silicone.
The antifoaming agent preferably has a kinematic viscosity at 25° C. of 500 mm ² /s to 100,000 mm ² /s, more preferably 1,000 mm ² /s to 50,000 mm ² /s.
When the turbine oil composition contains an antifoaming agent, the content of the antifoaming agent is preferably 1 ppm to 50 ppm, more preferably 2 ppm to 30 ppm, based on the total mass of the turbine oil composition. When the content of the antifoaming agent is within the above range, aggregation and sedimentation do not occur, and an antifoaming effect is obtained.

Antiwear and extreme pressure agents include zinc dithiophosphate compounds (ZnDTP), phosphate esters, and the like.
Examples of friction modifiers include fatty acids, acidic phosphoric acid esters and amine salts thereof, organic molybdenum compounds, polyhydric alcohol half esters, amide compounds, and the like.
Examples of surfactants include anionic surfactants such as Na alkylbenzenesulfonate, nonionic surfactants such as polyoxyethylene alkyl ethers and sorbitan fatty acid esters, cationic surfactants, and amphoteric surfactants.

When the turbine oil composition of the present invention contains other additives, from the viewpoint of ensuring biodegradability, the total content of antioxidants, demulsifiers, rust inhibitors and corrosion inhibitors is It is preferably less than 10% by mass.

<Properties of turbine oil composition>
The kinematic viscosity at 40° C. of the turbine oil composition of the present invention is preferably 20 mm ² /s to 100 mm ² /s, more preferably 32 mm ² /s to 68 mm ² /s, still more preferably 41.4 mm ² /s to 50.6 mm ² /s.
As a fatty acid ester turbine oil composition, a 40° C. kinematic viscosity of 41.4 mm ² /s to 50.6 mm ² /s is a general kinematic viscosity. When trying to prepare an oil composition, as described above, it was difficult to achieve excellent biodegradability, thermooxidative stability, and hydrolytic stability with conventional polyol ester turbine oils. , according to the present invention, this can be easily achieved.

(Biodegradable)
The turbine oil composition of the present invention preferably has a biodegradability of 60% or more according to the OECD301B method or the OECD301C method.
When the biodegradability of the turbine oil composition is 60% or more, it can be said that the biodegradability is higher.

Since the turbine oil composition of the present invention is excellent in thermal oxidation stability, hydrolyzability and biodegradability, it may be used, for example, as a turbine oil composition for hydroelectric power generation equipment in hydroelectric power plants.
The turbine oil composition of the present invention may also be applied to water gate equipment.

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples below, but the present invention is not limited to the following examples.

Table 1 shows the raw materials and physical properties of each ester base oil used in the turbine oils of Examples and Comparative Examples.
In addition, each property test was implemented based on the following test methods.
・ Kinematic viscosity: JIS K 2283 (2000) "Kinematic viscosity test method"
・Viscosity index: JIS K 2283 (2000) "Viscosity index calculation method"
・ Flash point: JIS K 2265-4 (2007) "Flash point test method (Cleveland open method)"
・ Pour point: JIS K 2269 (1987) "Pour point test method"
・ Acid value: JIS K 2501 (2003) "Neutralization value test method"
・ Iodine value: JIS K 0070 (1992) “Testing methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products”

The ester base oils shown in Table 1 and the additives shown below were blended in the proportions shown in Table 2 or Table 3 to prepare turbine oil compositions.
<Additive>
Amine-based antioxidant: an alkylated diphenylamine, which is a mixture of R ¹¹ and R ¹² having 4 carbon atoms and 8 carbon atoms in general formula (4).
· Phenolic antioxidant: isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, in general formula (1), both R ¹ and R ² are t-butyl groups, and R ³ is an ethylene group, R ⁴ is an isooctyl group, and n is 1;
• Anti-emulsifier: A copolymer of ethylene oxide-propylene oxide as the main component. The weight average molecular weight is 5000-8000.
· Rust inhibitor: alkenyl succinic acid half ester, acid value: 175 mgKOH/g
・Corrosion inhibitor: Benzotriazole derivative ・Antifoaming agent: Polydimethylsiloxane (other additives)

Tables 2 and 3 show the general properties of the prepared turbine oil composition and the results of the biodegradability test of the composition.
-evaluation-
<Biodegradability>
The test period was set to 28 days by the OECD301B method or the OECD301C method specified in the Eco Mark certification standard "biodegradable lubricating oil Version 2.6". Based on this standard, a 28-day test was performed. If the degree of biodegradation was 60% or more, it was judged to pass, and if it was less than 60%, it was judged to be unsatisfactory.

<Thermal stability>
As a sample, 40 ml of a turbine oil composition blended in the proportions shown in Table 2 or Table 3 is placed in a sample bottle, left to stand for a predetermined time (1000 hours) in a constant temperature bath with a rotating disk at 120 ° C., and after the test The acid value (mgKOH/g) of the sample was measured, and the acid value change was obtained from the following formula.
Change in acid value=acid value after test−acid value before test When the change in acid value is 0.1 mgKOH/g or less, it can be judged that the thermal stability is excellent.

<Hydrolytic stability>
A turbine oil composition blended in the ratio shown in Table 2 or Table 3 was used as a sample, and a hydrolysis stability test was conducted by a modified method of ASTM D 2619-95 "Standard Test Method for Hydraulic Stability of Hydraulic Fluids (Beverage Bottle Method)". did. The test equipment, temperature, etc. conformed to the test method.
Regarding the sample amount, moisture ratio, and test time, in order to simulate the effect of moisture contamination in long-term use, the moisture ratio was set to 2000 ppm with respect to 100 g of the sample, and the sample was stored under the conditions of 93 ° C. and 480 hours. The acid value (mgKOH/g) was measured, and the change in acid value was determined from the following formula.

Acid value change = Acid value of sample after storage - Acid value of sample before storage

If the change in acid value is 0.5 mgKOH/g or less, it can be judged that the hydrolysis stability is excellent.

As shown in Table 2, the turbine oil composition of Example 1 was excellent in all of thermooxidative stability, hydrolyzability and biodegradability. Further, the biodegradability of the turbine oil composition of Example 1 was 60% or more according to the OECD301C method.
On the other hand, the base oil consists of an alcohol residue having a neopentyl structure and a saturated fatty acid residue of a mixture of linear saturated fatty acids with 7 to 11 carbon atoms and branched saturated fatty acids with 16 to 20 carbon atoms. The turbine oil compositions of Comparative Examples 1 to 3, which did not contain polyol ester, did not satisfy all of the thermal oxidative stability, hydrolyzability and biodegradability.

The turbine oil composition according to the present invention is excellent in thermal oxidation stability, hydrolyzability and biodegradability, and can be suitably used as turbine oil for hydroelectric power generation equipment.

Claims (2)

It consists of an alcohol residue having a neopentyl structure and a saturated fatty acid residue of a mixture of a linear saturated fatty acid having 7 to 11 carbon atoms and a branched saturated fatty acid having 16 to 20 carbon atoms, and has a kinematic viscosity at 40 ° C. a base oil containing a polyol ester with a viscosity of 32 mm ² /s to 68 mm ² /s;
0.05% by mass to 0.15% by mass of a carbodiimide compound as a hydrolysis inhibitor,
contains
Kinematic viscosity at 40° C. is 41.4 mm ² /s to 50.6 mm ² /s,
The biodegradability according to the OECD301B method or the OECD301C method is 60% or more ,
for hydroelectric power plants ,
Turbine oil composition. 2. The turbine oil composition according to claim 1, further comprising at least one selected from the group consisting of antioxidants, demulsifiers, rust inhibitors and corrosion inhibitors.