JP5759836B2 - Biodegradable lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition, and more particularly to a biodegradable lubricating oil composition used in particular for a step-up gear for wind power generation.

In recent years, wind power generation using natural energy has attracted attention from the viewpoint of environmental problems and the depletion of fossil fuels. In wind power generation, it is important to increase the power generation efficiency because the rotational speed of the rotor is slow, and a speed increaser is provided inside the power generation apparatus. A so-called gear oil is used for lubrication of a gear mechanism used in the gearbox, but extremely high lubricity is required.
Conventionally, lubricating oil based on PAO (polyalphaolefin) has been used as a speed increasing oil. On the other hand, since wind power generators are often used offshore or in natural environments, speed increaser oil requires high biodegradability. In contrast, conventional PAO-based lubricants have little biodegradability, and therefore search for alternatives has been continued.
As a speed increaser for a wind turbine generator that requires biodegradability, it is conceivable to apply a lubricant based on an ester (see, for example, Patent Documents 1 to 3). Patent Documents 1 and 2 propose biodegradable lubricating oils based on complex esters obtained from polyhydric alcohols and polycarboxylic acids. Patent Document 3 proposes a biodegradable lubricating oil obtained by blending two specific complex esters and a specific phosphate ester amine salt.

Special table 2003-522204 gazette JP 2005-520038 Gazette JP 2010-260972 A

However, the biodegradable lubricating oils described in Patent Documents 1 and 2 do not have sufficient oxidation stability, and maintain the performance as a lubricating oil for a long period of time when used for a gearbox of a wind power generator. It is difficult to do.
In addition, the biodegradable lubricating oil described in Patent Document 3 does not have sufficient low-temperature fluidity. For example, when used as a speed increaser for a wind power generator installed in a cold region, the increase in operating torque of the device due to oil is large. This will reduce the power generation efficiency of wind power generators.
Accordingly, an object of the present invention is to provide a biodegradable lubricating oil composition that is excellent in lubricity, low-temperature fluidity, oxidation stability, and biodegradability, and that is also suitable for use in a gearbox used in a wind power generator. It is in.

In order to solve the above problems, the present invention provides the following biodegradable lubricating oil composition.
The biodegradable lubricating oil composition of the present invention is obtained by reacting (A) a linear saturated aliphatic carboxylic acid, a linear aliphatic dicarboxylic acid and a polyhydric alcohol, and has a kinematic viscosity at 40 ° C. of 400 mm. ² / s or more and 1000 mm ² / s or less, an acid value of 0.5 mgKOH / g or less, (B) a linear saturated aliphatic carboxylic acid and a polyhydric alcohol are reacted to obtain an acid value. A linear saturated fat in the component (A), comprising an ester of 0.5 mg KOH / g or less and (C) a phosphate ester amine salt obtained by reacting an acidic phosphate with an alkylamine. The group carboxylic acid is composed of a linear saturated aliphatic carboxylic acid having 8 carbon atoms and a linear saturated aliphatic carboxylic acid having 10 carbon atoms, and the molar amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is the number of carbon atoms. 10 straight chain saturated fats More than the molar amount of the group carboxylic acid.

In the biodegradable lubricating oil composition of the present invention, the linear saturated aliphatic carboxylic acid in the component (A) is composed of 60 mol% or more and 90 mol% or less of a linear saturated aliphatic carboxylic acid having 8 carbon atoms, It is preferably composed of 10 mol% or more and 40 mol% or less of the linear saturated aliphatic carboxylic acid of several tens.
In the biodegradable lubricating oil composition of the present invention, as component (D), (D-1) the molecule does not contain a polysulfur condensation of -SSSS or more and the sulfur atom in the molecule ( S) It is preferable to further blend a sulfur compound having a content of 15% by mass or more.
In the biodegradable lubricating oil composition of the present invention, it is preferable to further blend (D-2) a thiophosphate trihydrocarbyl ester represented by the following formula (2) as the component (D).
(RO−) ₃ P = S (2)
In the biodegradable lubricating oil composition of the present invention, a group consisting of an ashless detergent / dispersant, an antioxidant, a rust inhibitor, a metal deactivator, a viscosity index improver, a pour point depressant and an antifoaming agent. It is preferable to further blend at least one selected from
In the biodegradable lubricating oil composition of the present invention, the biodegradable lubricating oil composition is preferably gear oil or bearing oil. Moreover, it is preferable that the gear oil is for a step-up gear of a wind power generator.

  The biodegradable lubricating oil composition of the present invention is excellent in lubricity, low-temperature fluidity, oxidation stability, and biodegradability, and is also suitable for a speed increaser used in a wind power generator.

  The biodegradable lubricating oil composition of the present invention (hereinafter also simply referred to as “the present composition”) comprises (A) a linear saturated aliphatic carboxylic acid, a linear aliphatic dicarboxylic acid, and a polyhydric alcohol. An ester obtained by reacting, (B) an ester obtained by reacting a linear saturated aliphatic carboxylic acid and a polyhydric alcohol, and (C) a phosphor obtained by reacting an acidic phosphate with an alkylamine. The linear saturated aliphatic carboxylic acid in the component (A) is a linear saturated aliphatic carboxylic acid having 8 carbon atoms and a linear saturated aliphatic carboxylic acid having 10 carbon atoms. And the molar amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is larger than the molar amount of the linear saturated aliphatic carboxylic acid having 10 carbon atoms. Hereinafter, the present invention will be described in detail.

[Component (A)]
The component (A) in the present invention is a so-called complex ester obtained by reacting a linear saturated aliphatic carboxylic acid, a linear aliphatic divalent carboxylic acid, and a polyhydric alcohol.
The linear saturated aliphatic carboxylic acid is composed of a linear saturated aliphatic carboxylic acid having 8 carbon atoms and a linear saturated aliphatic carboxylic acid having 10 carbon atoms, and is a monovalent carboxylic acid. Further, it is necessary that the molar amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is larger than the molar amount of the linear saturated aliphatic carboxylic acid having 10 carbon atoms. When the molar amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is less than or equal to the molar amount of the linear saturated aliphatic carboxylic acid having 10 carbon atoms, the oxidative stability of the resulting biodegradable lubricating oil composition is poor. It will be enough.
The blending amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms with respect to the total amount of the linear saturated aliphatic carboxylic acid is preferably 51 mol% or more and 99 mol% or less, and 60 mol% or more in terms of molar ratio. More preferably, it is 90 mol% or less. If the blending amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is within the above range, the oxidation stability of the resulting biodegradable lubricating oil composition can be ensured.
Examples of the linear saturated aliphatic carboxylic acid having 8 carbon atoms and the linear saturated aliphatic carboxylic acid having 10 carbon atoms include caprylic acid (8 carbon atoms) and capric acid (10 carbon atoms), respectively.

Examples of the linear aliphatic dicarboxylic acid include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, and octadecanedioic acid. Examples include acids, nonadecanedioic acid, and eicosanedioic acid. These linear aliphatic divalent carboxylic acids may be used alone or in combination of two or more during esterification.
Among these linear aliphatic divalent carboxylic acids, it is preferable to use those having 12 or less carbon atoms in order to maintain fluidity at low temperatures.

As the polyhydric alcohol for forming the component (A), a so-called hindered polyol is preferably used. Specifically, neopentyl glycol; 2-ethyl-2-methyl-1,3-propanediol; 2,2-diethyl-1,3-propanediol; trimethylolethane; trimethylolpropane; trimethylolbutane; 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; 6-dihydroxymethyl-2,6-dimethyl-4-oxa-1,7-heptanediol; 2,6,10-trihydroxy Methyl-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).
These hindered polyols may be used alone or in combination of two or more during esterification.

The complex ester as the component (A) is obtained by reacting the above-mentioned linear saturated aliphatic carboxylic acid, linear aliphatic dicarboxylic acid and polyhydric alcohol, and has a kinematic viscosity at 40 ° C. of 400 mm ² / s. Above, it is 1000 mm < ² > / s or less. When this kinematic viscosity is less than 400 mm ² / s, there is a possibility that a viscosity necessary for maintaining lubricity when a lubricating oil composition is obtained cannot be obtained. On the other hand, if the kinematic viscosity exceeds 1000 mm ² / s, biodegradability may be reduced.
Moreover, as (A) component, an acid value needs to be 0.5 mgKOH / g or less. When the acid value exceeds 0.5 mgKOH / g, the oxidation stability may be deteriorated.

  In order to obtain an ester as the component (A), it is common to react two kinds of carboxylic acid with a polyhydric alcohol as described above. It suffices to have an ester structure composed of a monohydric alcohol residue. The starting material (reaction raw material) itself need not be the carboxylic acid or polyhydric alcohol described above, and it is not always necessary to synthesize the component (A) by a dehydration reaction therefrom. You may synthesize | combine by another method from another raw material. For example, it may be produced by a transesterification method.

[(B) component]
The component (B) in the present invention is an ester obtained by reacting a linear saturated aliphatic carboxylic acid with a polyhydric alcohol.
Here, the linear saturated aliphatic carboxylic acid is preferably a carboxylic acid having 6 to 12 carbon atoms in order to maintain biodegradability and low-temperature fluidity. Specific examples include monocarboxylic acids such as caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, and lauric acid. In addition, since there exists a possibility that it may solidify when 1 type of carboxylic acid is used, it is preferable to use combining several types of carboxylic acid.
As a polyhydric alcohol, the same hindered polyalcohol as the polyhydric alcohol used in order to form (A) component is used suitably.

The kinematic viscosity at 40 ° C. of the component (B) is preferably 20 mm ² / s or more and 40 mm ² / s or less. If the kinematic viscosity is less than 20 mm ² / s, lubricity may be reduced when a lubricating oil composition is obtained. On the other hand, if the kinematic viscosity exceeds 40 mm ² / s, the low temperature fluidity may be deteriorated when a lubricating oil composition is obtained.
Moreover, as (B) component, an acid value needs to be 0.5 mgKOH / g or less. When the acid value exceeds 0.5 mgKOH / g, the oxidation stability may be deteriorated.

  The ester as the component (B) is generally obtained by reacting the above-mentioned predetermined carboxylic acid with a polyhydric alcohol. However, it is only necessary to have an ester structure composed of the carboxylic acid residue and the polyhydric alcohol residue as a result. The starting material (reaction raw material) itself does not need to be the carboxylic acid or polyhydric alcohol described above, and it is not always necessary to synthesize the component (B) by dehydration reaction therefrom. You may synthesize | combine by another method from another raw material. For example, it may be produced by a transesterification method.

  The blending ratio of the component (B) in the present invention is preferably 10% by mass or more based on the composition from the viewpoint of biodegradability.

[Component (C)]
The component (C) in the present invention is a phosphate ester amine salt obtained by reacting an acidic phosphate ester with an alkylamine.
(C) As acidic phosphate ester for forming a component, the thing of the structure shown by following formula (1) is mentioned, for example.

X ¹ in the formula (1) represents a hydrogen atom or an alkyl group having 6 to 20 carbon atoms, and X ² represents an alkyl group having 6 to 20 carbon atoms. The alkyl group having 6 to 20 carbon atoms may be linear, branched or cyclic, and examples thereof include various hexyl groups, octyl groups, decyl groups, dodecyl groups, tetradecyl groups. Group, hexadecyl group, octadecyl group, icon group and the like. Among these, an alkyl group having 8 to 18 carbon atoms is preferable, and an alkyl group having 8 to 13 carbon atoms is more preferable.

  Examples of the acidic phosphoric acid alkyl esters represented by the formula (1) include monooctyl acid phosphate, monodecyl acid phosphate, monoisodecyl acid phosphate, monolauryl acid phosphate, mono (tridecyl) acid phosphate, and monomyristyl acid phosphate. Acidic phosphoric acid monoesters such as monopalmityl acid phosphate and monostearyl acid phosphate, dioctyl acid phosphate, didecyl acid phosphate, diisodecyl acid phosphate, dilauryl acid phosphate, di (tridecyl) acid phosphate, dipalmityl acid phosphate, Mention may be made of acidic phosphoric acid diesters such as distearyl acid phosphate.

  (C) In order to form a component, the said acidic phosphate ester may be used individually by 1 type, and may be used in combination of 2 or more type. When the final composition is used, the phosphorus (P) content is preferably 150 ppm by mass or more and 500 ppm by mass or less based on the total amount of the composition. If the P content is less than 150 ppm by mass, seizure resistance may be insufficient when used as gear oil. On the other hand, if the P content exceeds 500 ppm by mass, fatigue resistance (FZG resistance) The micropitting property may be reduced. More preferable P content is 250 mass ppm or more and 450 mass ppm or less, and further preferably 350 mass ppm or more and 400 mass ppm or less.

(C) The alkylamine for forming the component may be any of primary amines, secondary amines and tertiary amines. However, in terms of improving seizure resistance, secondary amines or tertiary amines may be used. Are preferred, and dialkylamine or trialkylamine is more preferred. Further, it is preferable that the phosphoric ester amine salt is liquid at normal temperature (25 ° C.) in terms of solubility in base oil and prevention of precipitation at low temperature. For that purpose, the alkyl group has 6 or more carbon atoms, 20 The following are preferred.
Examples of dialkylamines include dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, and examples of trialkylamines include trihexylamine, tricyclohexylamine, Examples include octylamine, trilaurylamine, and tristearylamine.
These alkylamines may be used alone or in combination of two or more, but are preferably selected from trialkylamines in terms of seizure resistance.

The amount of component (C) is preferably 0.2% by mass or more and 1% by mass or less based on the total amount of the composition. When the blending amount is less than 0.2% by mass, the friction reducing effect is poor. On the other hand, if the blending amount exceeds 1% by mass, fatigue resistance (FZG micropitting resistance) may be reduced. Here, the component (C) may be mixed with other components in order to prepare the present composition after the acid phosphate amine salt is formed, or the acid phosphate ester and the alkylamine are individually added. The composition may be prepared by blending.
In addition, the compounding quantity of (C) component is a total value of both, when acidic phosphate ester and an alkylamine are mix | blended separately to make this composition.

In order to further improve the lubricity, the composition may further contain a predetermined sulfur compound as the component (D). For example, (D-1) a sulfur compound that does not contain a polysulfide condensation of -SSSS or more in the molecule and has a sulfur atom (S) content of 15% by mass or more in the molecule is suitable. . Furthermore, a thiophosphoric acid trihydrocarbyl ester represented by the following formula (2) is also suitable as a sulfur compound additionally blended with the component (D-1).
(RO−) ₃ P = S (2)

In said formula (2), R is a C6-C20 hydrocarbyl group. When the sulfur compound of the component (D-1) is a compound having a polysulfur condensation of -SSSS or more in the molecule, there is a possibility that the generation of sludge increases in the oxidation stability test described later. In addition, FZG micropitting resistance may be reduced. Moreover, if S content in a molecule | numerator is less than 15 mass%, the addition effect of a sulfur compound will not fully be exhibited, but seizure resistance may be insufficient.
Examples of the sulfur compound as the component (D-1) having such properties include the following compounds.
(1) Mono- or disulfide olefins (2) Dihydrocarbyl mono- or disulfides (3) Thiadiazole compounds (4) Dithiocarbamate compounds (5) Ester compounds having a disulfide structure (6) Other sulfur compounds

[Mono or disulfide olefin]
As a sulfurized olefin, the compound shown by following formula (3) can be mentioned, for example.
R ¹ -Sa-R ² (3)
In the above formula (3), R ¹ represents an alkenyl group having 2 to 15 carbon atoms, R ² represents an alkyl or alkenyl group having 2 to 15 carbon atoms, and a represents 1 or 2. 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. Examples of the olefin include propylene, isobutene and diisobutene. Preferably mentioned.

[Dihydrocarbyl mono or disulfide]
Examples of dihydrocarbyl mono or disulfide include compounds represented by the following formula (4).
R ³ —Sb—R ⁴ (4)
In the above formula (4), R ³ and R ⁴ 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, and an alkyl group having 7 to 20 carbon atoms. An aryl group or an arylalkyl group having 7 to 20 carbon atoms, which may be the same or different from each other, b represents 1 or 2. In addition, when R ³ and R ⁴ are alkyl groups, they are referred to as alkyl sulfides.

  Examples of the dihydrocarbyl mono or disulfide represented by the above formula (4) include dibenzyl mono or disulfide, various dinonyl mono or disulfide, various didodecyl mono or disulfide, various dibutyl mono or disulfide, various dioctyl mono or disulfide, diphenyl mono or disulfide, and dicyclohexanone. Preferable examples include xylmono or disulfide.

[Thiadiazole compounds]
Examples of 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, 3,6-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n-nonyldithio) -1,2,4 -Thiadiazole, 3,5-bis (1,1,3,3-tetramethylbutyldithio) -1,2,4-thiadiazole, 4,5-bis (n-octyldithio) -1,2,3-thiadiazole 4,5-bis n- nonyldithio) -1,2,3-thiadiazole, 4,5-bis (1,1,3,3-tetramethylbutyl dithio) -1,2,3-thiadiazoles such as can be a preferably exemplified.

[Dithiocarbamate compound]
Examples of the dithiocarbamate compound include alkylene bisdialkyldithiocarbamate, among which an alkylene group having 1 to 3 carbon atoms, a linear or branched saturated or unsaturated alkyl group having 3 to 20 carbon atoms, or The compound which is a C6-C20 cyclic alkyl group is mentioned preferably. Specific examples of such dithiocarbamate compounds include methylene bisdibutyl dithiocarbamate, methylene bisdioctyl dithiocarbamate, methylene bistridecyl dithiocarbamate, and the like.

[Ester compound having a disulfide structure]
Examples of the ester compound having a disulfide structure include a disulfide compound represented by the following formula (5) and a compound represented by the following formula (6).
^{R 5 OOC-A 1 -S-} S-A 2 -COOR 6 (5)
^{R 11 OOC-CR 13 R 14} -CR 15 (COOR 12) -S-S-CR 20 (COOR 17) -CR 18 R 19 -COOR 16 (6)

In the above formula (5), R ⁵ and R ⁶ are each independently a hydrocarbyl group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 18 carbon atoms, especially Is preferably a hydrocarbyl group having 3 to 18 carbon atoms. The hydrocarbyl group may be linear, branched or cyclic, and may contain an oxygen atom, a sulfur atom or a nitrogen atom. R ⁵ and R ⁶ may be the same or different from each other, but are preferably the same for manufacturing reasons.
Next, A ¹ and A ² are each independently a group represented by CR ⁷ R ⁸ or CR ⁷ R ⁸ -CR ⁹ R ¹⁰ , and R ⁷ to R ¹⁰ are each independently a hydrogen atom or a carbon number. 1 or more and 20 or less hydrocarbyl group. The hydrocarbyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. A ¹ and A ² may be the same or different from each other, but are preferably the same for manufacturing reasons.

On the other hand, in the above formula (6), R ¹¹ , R ¹² , R ¹⁶ and R ¹⁷ are each independently a hydrocarbyl group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, and more preferably carbon. A hydrocarbyl group having 2 or more and 18 or less, particularly 3 or more and 18 or less carbon atoms is preferable. The hydrocarbyl group may be linear, branched or cyclic, and may contain an oxygen atom, a sulfur atom or a nitrogen atom. R ¹¹ , R ¹² , R ¹⁶ and R ¹⁷ may be the same or different from each other, but are preferably the same for reasons of production.
Next, R ¹³ to R ¹⁵ and R ¹⁸ to R ²⁰ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 5 carbon atoms. A hydrogen atom is preferable because the raw material is easily available.

  Specific examples of the disulfide compound represented by the above formula (5) include bis (methoxycarbonyl-methyl) disulfide, bis (ethoxycarbonylmethyl) disulfide, bis (n-propoxycarbonylmethyl) disulfide, and bis (isopropoxycarbonylmethyl). ) Disulfide, bis (cyclopropoxycarbonylmethyl) disulfide, 1,1-bis (1-methoxycarbonylethyl) disulfide, 1,1-bis (1-methoxycarbonyl-n-propyl) disulfide, 1,1-bis (1 -Methoxycarbonyl-n-butyl) disulfide, 1,1-bis (1-methoxycarbonyl-n-hexyl) disulfide, 1,1-bis (1-methoxycarbonyl-n-octyl) disulfide, 2,2-bis ( 2-methoxycarbonyl n-propyl) disulfide, α, α-bis (α-methoxycarbonylbenzyl) disulfide, 1,1-bis (2-methoxycarbonylethyl) disulfide, 1,1-bis (2-ethoxycarbonylethyl) disulfide, 1, 1-bis (2-n-propoxycarbonylethyl) disulfide, 1,1-bis (2-isopropoxycarbonylethyl) disulfide, 1,1-bis (2-cyclopropoxycarbonylethyl) disulfide, 1,1-bis ( 2-methoxycarbonyl-n-propyl) disulfide, 1,1-bis (2-methoxycarbonyl-n-butyl) disulfide, 1,1-bis (2-methoxycarbonyl-n-hexyl) disulfide, 1,1-bis (2-methoxycarbonyl-n-propyl) disulfide, 2,2 Bis (3-methoxycarbonyl -n- pentyl) disulfide, 1,1-bis (2-methoxycarbonyl-1-phenylethyl) and the like disulfides.

  Specific examples of the disulfide compound represented by the above formula (6) include tetramethyl dithiomalate, tetraethyl dithiomalate, tetra-1-propyl dithiomalate, tetra-2-propyl dithiomalate, tetra-1-butyl dithiomalate, Tetra-2-butyl dithiomalate, tetraisobutyl dithiomalate, tetra-1-hexyl dithiomalate, tetra-1-octyl dithiomalate, tetra-1- (2-ethyl) hexyl dithiomalate, tetra-1-dithiomalate , 5,5-trimethyl) hexyl, tetra-1-decyl dithiomalate, tetra-1-dodecyl dithiomalate, tetra-1-hexadecyl dithiomalate, tetra-1-octadecyl dithiomalate, tetrabenzyl dithiomalate, dithiomalate te La-α- (methyl) benzyl, tetra-α, α-dimethylbenzyl dithiomalate, tetra-1- (2-methoxy) ethyl dithiomalate, tetra-1- (2-ethoxy) ethyl dithiomalate, tetra-1 dithiomalate -(2-butoxy) ethyl, tetra-1- (2-ethoxy) ethyl dithiomalate, tetra-1- (2-butoxyptoxy) ethyl dithiomalate, tetra-1- (2-phenoxy) ethyl dithiomalate, etc. Can be mentioned.

[Other sulfur compounds]
Examples of other sulfur compounds include sulfurized fats such as sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil and sulfurized rice bran oil, sulfurized fatty acids such as thioglycolic acid and sulfurized oleic acid, dilauryl thiodipropionate, and distearyl. Examples thereof include dialkylthiodipropionate compounds such as thiodipropionate and dimyristylthiodipropionate, and thioterpene compounds obtained by reacting phosphorus pentasulfide with pinene.

  As the above component (D-1), the above sulfur compounds may be used alone or in combination of two or more. Moreover, the compounding amount of the component (D-1) is preferably 0.2% by mass or more and 0.6% by mass or less in terms of the amount of sulfur based on the total amount of the composition. If the blending amount is less than 0.2% by mass, the seizure resistance may not be sufficiently exhibited. On the other hand, if the blending amount exceeds 0.6% by mass, the fatigue resistance such as FZG micropitting resistance is inferior. In the oxidation stability test (according to ASTM D 2893), the generation of sludge may increase. A preferable blending amount is 0.3% by mass or more and 0.5% by mass or less.

When blending the above component (D-1), it is preferable to blend the thiophosphate trihydrocarbyl ester represented by the above formula (2) as the component (D-2) as desired.
R in Formula (2) represents a hydrocarbyl group having 6 to 20 carbon atoms. Examples of the hydrocarbyl group include linear, branched, and cyclic alkyl groups or alkenyl groups having 6 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aryl groups having 7 to 20 carbon atoms. Indicates. In the aryl group and aralkyl group, one or more alkyl groups may be introduced on the aromatic ring. The three RO groups may be the same or different from each other.
Examples of the alkyl group and alkenyl group having 6 to 20 carbon atoms include various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, and cyclohexyl. Groups, various hexenyl groups, various octenyl groups, various decenyl groups, various dodecenyl groups, various tetradecenyl groups, various hexadecenyl groups, various octadecenyl groups, and cyclohexenyl groups.
Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, tolyl group, xylyl group, decylphenyl group, 2,4-didecylphenyl group, naphthyl group, and the like, and has 7 to 20 carbon atoms. Examples of the aralkyl group include a benzyl group, a phenethyl group, a naphthylmethyl group, a methylbenzyl group, a methylphenethyl group, and a methylnaphthylmethyl group.
Specific examples of the thiophosphoric acid trihydrocarbyl ester represented by the above formula (2) include trihexyl thiophosphate, tri-2-ethylhexyl thiophosphate, tris (decyl) thiophosphate, trilauryl thiophosphate, trimyristyl thiophosphate. , Tripalmityl thiophosphate, tristearyl thiophosphate, trioleyl thiophosphate, trixidyl thiophosphate, triquinyl thiophosphate, tris (decylphenyl) thiophosphate, tris [2,4-isoalkyl (C9, C10) phenyl] thio Examples include phosphate. One of these thiophosphate trihydrocarbyl phosphates may be used alone, or two or more thereof may be used in combination.
The (D-2) component thiophosphate trihydrocarbyl ester is blended as desired in order to further enhance the effect of adding the sulfur compound of the above component (D-1). Based on the total amount, it is preferably 0.1% by mass or more and less than 1% by mass, more preferably 0.2% by mass or more and 0.5% by mass in terms of sulfur.

In the present composition, various additives such as ashless detergents, antioxidants, rust preventives, metal deactivators, viscosity index improvers, as necessary, within a range where the object of the present invention is not impaired. In addition, at least one selected from pour point depressants and antifoaming agents can be blended.
Here, as the ashless detergent / dispersant, for example, succinimides, boron-containing succinimides, benzylamines, boron-containing benzylamines, succinic esters, fatty acids or succinic acids represented by succinic acid Or divalent carboxylic acid amides are mentioned. The blending amount of the ashless detergent / dispersant is about 0.01% by mass or more and 5% by mass or less on the basis of the total amount of the composition from the viewpoint of balance between effects and economy.

  As the antioxidant, amine-based antioxidants, phenol-based antioxidants and sulfur-based antioxidants conventionally used in lubricating oils can be used. These antioxidants can be used alone or in combination of two or more. Examples of amine antioxidants include monoalkyl diphenylamine compounds such as monooctyl diphenylamine and monononyl diphenylamine, 4,4′-dibutyldiphenylamine, 4,4′-dibenzyldiphenylamine, and 4,4′-dihexyl. Diphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, dialkyldiphenylamine compounds such as 4,4'-dinonyldiphenylamine, tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyl Polyalkyldiphenylamine compounds such as diphenylamine, α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, benzylphenyl α- naphthylamine, hexyl phenyl -α- naphthylamine, heptyl phenyl -α- naphthylamine, octylphenyl -α- naphthylamine, and naphthylamine-based compounds such as nonylphenyl -α- naphthylamine.

Examples of the phenolic antioxidant include 2,6-di -tert- butyl-4-methylphenol, 2,6-di -tert- butyl-4-ethylphenol, octadecyl 3- (3,5-di - monophenolic compounds such as tert-butyl-4-hydroxyphenyl) propionate, 4,4′-methylenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6- and diphenolic compounds such as tert-butylphenol).
Examples of the sulfur-based antioxidant include 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, phosphorus pentasulfide, and the like. Examples thereof include thioterpene compounds such as a reaction product with pinene, dialkylthiodipropionates such as dilauryl thiodipropionate, and distiaryl thiodipropionate.
The blending amount of the antioxidant is about 0.3% by mass or more and 2% by mass or less on the basis of the total amount of the composition from the viewpoint of balance between effects and economy.

Examples of the rust preventive include metal sulfonates and alkenyl succinic acid esters. The blending amount of these rust preventives is about 0.01% by mass or more and 0.5% by mass or less on the basis of the total amount of the composition from the viewpoint of blending effect.
Examples of the metal deactivator (copper corrosion inhibitor) include benzotriazole, tolyltriazole, thiadiazole, imidazole, and pyrimidine compounds. Of these, benzotriazole compounds are preferred. The compounding amount of these metal deactivators is about 0.01% by mass or more and 0.1% by mass or less on the basis of the total amount of the composition from the viewpoint of the blending effect.
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 copolymer, styrene-isoprene copolymer, etc.). The blending amount of these viscosity index improvers is about 0.5% by mass or more and 15% by mass or less based on the total amount of the composition from the viewpoint of the blending effect.

Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene, and the like. Polymethacrylate having a molecular weight of about 50,000 or more and about 150,000 or less is preferably used. The blending amount of the pour point depressant is about 0.1% by mass or more and 5% by mass or less based on the total amount of the composition.
As the antifoaming agent, a polymer silicone-based antifoaming agent and a polyacrylate-based antifoaming agent are preferable. By adding such a polymer silicone-based antifoaming agent, the defoaming property is effectively exhibited. Examples of such high molecular silicone antifoaming agents include organopolysiloxanes, and fluorine-containing organopolysiloxanes such as trifluoropropylmethyl silicone oil are particularly suitable. The blending amount of the antifoaming agent is about 0.005% by mass or more and 0.1% by mass or less based on the total amount of the composition from the viewpoint of balance between the defoaming effect and economy.

  Since the biodegradable lubricating oil composition of the present invention is excellent in lubricity, low-temperature fluidity, oxidation stability and biodegradability, it is suitable as various lubricating oils such as gear oil (gear oil) and bearing oil. Can be used. In particular, since the wind power generator is continuously used outdoors for a long period of time, the present composition is suitable as a lubricating oil used in a planetary gear type power transmission device (speed increaser) placed inside the wind power generator. . In addition, the present composition is particularly suitable as a lubricating oil used for a gearbox placed inside a wind power generator when installed on the ocean or in a mountainous area.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
[Examples 1-3, Comparative Examples 1-3]
Various additives were blended using various esters as a base oil, and various evaluations were performed on the resulting lubricating oil composition (sample oil).
The details of various components and various additives used as the base oil are shown below. Table 1 shows the properties of the carboxylic acid ester.

(1) Ester A (component A)
A complex ester composed of caprylic acid, capric acid, adipic acid and trimethylolpropane having a molar ratio (C8: C10) of caprylic acid (C8) to capric acid (C10) of 6: 4 150-28) was used.
(2) Ester B (component A)
A complex ester composed of caprylic acid, capric acid, adipic acid and trimethylolpropane having a molar ratio of caprylic acid (C8) to capric acid (C10) (C8: C10) of 8: 2 150-30) was used.
(3) Ester C (component A)
A complex ester composed of caprylic acid, capric acid, adipic acid and trimethylolpropane, wherein the molar ratio of caprylic acid (C8) to capric acid (C10) (C8: C10) is 9: 1 (Kao's Kao Lub 150-31) was used.
(4) Ester D
A complex ester composed of caprylic acid, capric acid, adipic acid and trimethylolpropane having a molar ratio (C8: C10) of caprylic acid (C8) to capric acid (C10) of 5: 5 150-29) was used.
(5) Ester E
A complex ester composed of pentaerythritol, sebacic acid and isostearic acid (Priorb 1851 manufactured by uniqema) was used.
(6) Ester F (component B)
An ester composed of pentaerythritol and a saturated fatty acid (Kao Kaoru 262) was used.
(7) Ester G
Trimethylolpropane diisostearate was used.
(8) PAO
Polyalphaolefin (INEOS USA LLC, PAO40) was used.

(9) Phosphate ester amine salt (component C)
Tridecyl acid phosphate and trioctylamine were used.
(10) Sulfur compounds (component D)
Methylenebisdibutyldithiocarbamate and tris (2,4-C9-C10 isoalkylphenol) thiophosphate were used.
(11) Antioxidant Irganox L107 manufactured by Ciba Specialty Chemicals was used as the phenolic type. Irganox L57 manufactured by Ciba Specialty Chemicals was used as the amine system. (12) Metal deactivator IRGAMET39 (benzotriazole derivative) manufactured by Ciba Japan was used.
(13) Antifoaming agent A silicone-based antifoaming agent (Shin-Etsu Chemical KF96H12500CS) was used.
(14) Demulsifier Lubrizol 5957 (PAG type) manufactured by Lubrizol was used.

The properties measurement method and various evaluation methods of the base oil and the test oil are as follows. Table 2 shows the evaluation results (biodegradability, oxidation stability, lubricity) of the test oil.
(1) Kinematic viscosity It measured based on the method of JISK2283.
(2) Acid value It measured based on the method of JISK2501.
(3) Saponification value It measured based on the method of JISK2503.
(4) Sulfur content It measured based on the method of JISK2541.
(5) Phosphorus content Measured according to the method described in ASTM D 5185.

(6) Biodegradability The biodegradability was measured according to the modified MITI test method (OECD301C). In addition, according to the Eco Mark certification standard revised in July 1998, this biodegradation rate is required to be 60% or more.
(7) Oxidation stability test In accordance with ASTM D 2893, the sample oil was air-oxidized (121 ° C, 312 hours) under predetermined conditions, and filtered through a 100 ° C kinematic viscosity increase rate, an acid value increase amount, and a Millipore filter. The amount of sludge was measured.
(8) Pour point Measured according to the method described in JIS K2269.
(9) Lubricity The friction coefficient (f15, f30, f90, f120) measured 15 minutes, 30 minutes, 90 minutes, and 120 minutes after the start of the test in the ball-on-disk tester and measurement conditions described in DIN51834 The average value (Wk, unit mm) of the wear scar diameter after 120 minutes was obtained.

〔Evaluation results〕
As shown in Table 2, the sample oils of Examples 1 to 3 that satisfy the conditions of the present invention are excellent in lubricity, low-temperature fluidity, oxidation stability, and biodegradability. For example, wind power generation It can be understood that it exhibits excellent performance for the gearbox used in the apparatus. On the other hand, in the test oil of Comparative Example 1, the ester D used as the base oil had a molar ratio (C8: C10) of caprylic acid (C8) to capric acid (C10) of 5: 5 when the ester was produced. Therefore, it is inferior in oxidation stability. The test oil of Comparative Example 2 has a structure in which the ester E used as the base oil uses a fatty acid different from the ester A, and the low temperature fluidity is inferior. The test oil of Comparative Example 3 is obtained by using PAO as the base oil and further blending 10% by mass of ester G (branched aliphatic carboxylic acid polyhydric alcohol ester), but is inferior in biodegradability. .

Claims (7)

(A) It is obtained by reacting a linear saturated aliphatic carboxylic acid, a linear aliphatic divalent carboxylic acid and a polyhydric alcohol, and has a kinematic viscosity at 40 ° C. of 400 mm ² / s or more and 1000 mm ² / s or less, an acid. An ester having a value of 0.5 mg KOH / g or less;
(B) an ester obtained by reacting a linear saturated aliphatic carboxylic acid and a polyhydric alcohol, and having an acid value of 0.5 mgKOH / g or less,
(C) a phosphoric acid ester amine salt obtained by reacting an acidic phosphoric acid ester with an alkylamine,
The linear saturated aliphatic carboxylic acid in the component (A) is composed of a linear saturated aliphatic carboxylic acid having 8 carbon atoms and a linear saturated aliphatic carboxylic acid having 10 carbon atoms. A biodegradable lubricating oil composition, wherein the molar amount of the aliphatic carboxylic acid is larger than the molar amount of the linear saturated aliphatic carboxylic acid having 10 carbon atoms. The biodegradable lubricating oil composition according to claim 1,
The linear saturated aliphatic carboxylic acid in the component (A) is composed of 60 mol% to 90 mol% of a linear saturated aliphatic carboxylic acid having 8 carbon atoms and 10 mol% of a linear saturated aliphatic carboxylic acid having 10 carbon atoms. A biodegradable lubricating oil composition characterized by comprising 40 mol% or less. In the biodegradable lubricating oil composition according to claim 1 or 2,
As component (D), (D-1) a sulfur compound not containing polysulfide condensation of -SSSS or more in the molecule and having a sulfur atom (S) content of 15% by mass or more in the molecule. Further blended
A biodegradable lubricating oil composition characterized by that. In the biodegradable lubricating oil composition according to any one of claims 1 to 3,
As component (D), (D-2) further blended with thiophosphate trihydrocarbyl ester represented by the following formula (2)
A biodegradable lubricating oil composition characterized by that.
(RO-) ₃ P = S (2) In the biodegradable lubricating oil composition according to any one of claims 1 to 4,
Further blending at least one selected from the group consisting of ashless detergents, antioxidants, rust inhibitors, metal deactivators, viscosity index improvers, pour point depressants and antifoaming agents Become
A biodegradable lubricating oil composition characterized by that. The biodegradable lubricating oil composition according to any one of claims 1 to 5, wherein the biodegradable lubricating oil composition is a gear oil or a bearing oil. The biodegradable lubricating oil composition according to claim 6 ,
The biodegradable lubricating oil composition, wherein the gear oil is used for a step-up gear of a wind power generator.