JP2005213451A - Biodegradable lubricant composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable lubricant composition which is excellent in biodegradability, has a high viscosity index, a low pour point and a high flash point and shows a good lubricating performance, oxidation stability, anticorrosive property against iron or a non-ferrous metal and applicability to a sealant. <P>SOLUTION: The biodegradable lubricant composition contains (A) a synthetic ester-base oil containing ≥50 mass% hindered ester of aliphatic hindered polyols and aliphatic monocarboxylic acids, wherein the aliphatic hindered polyols each has at least one quaternary carbon within the molecule and 1-4 methylol groups bound to at least one of the quaternary carbons and (B) (a) 0.1-5.0 mass% phenolic antioxidant, (b) 0.01-2.0 mass% calcium sulfonate with a low basic value and (c) 0.01-1.0 mass% triazole-based compound. The composition shows biodegradability of ≥60% in a microbial degradation test of chemical substances according to the OECD test guideline 301C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a biodegradable lubricating oil composition. More specifically, the present invention is excellent in biodegradability and has a high viscosity index, a low pour point, a high flash point, and good lubricating performance, oxidation stability, iron and The present invention relates to a synthetic ester biodegradable lubricating oil composition having anticorrosive properties against non-ferrous metals and compatibility with a sealing material.

In recent years, biodegradable lubricants have attracted attention in the field of lubricants from the standpoint of environmental pollution countermeasures, and development research has been conducted by various companies. In Japan, it has been launched from the early 1990s. became. However, biodegradable lubricants are more expensive than conventional mineral oils, so despite their attention, they are rarely used in Japan and are required by law. The actual situation is behind.
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 compatibility with the sealing material. Therefore, biodegradable lubricants in Japan are becoming predominantly synthetic ester-based lubricants. However, synthetic ester-based lubricants so far are much more expensive than mineral oil-based lubricants in terms of price and oxidation stability. It was inferior to.

In Japan, there is an “Eco Mark” certified by the Japan Environmental Association as a standard for biodegradable hydraulic oil. This "Eco Mark" certification standard was revised significantly in July 1998, and the certification standard is stricter than before. The major changes are as follows.
(1) The biodegradability standard was changed from the partial biodegradation test “CEC method” (standard: 67% or more) to the essential biodegradation test “OECD301C method” (standard: biodegradation rate 60% or more).
(2) Addition of acute toxicity test JIS K 0102 (standard: LC ₅₀ value ≧ 100 mg / L) with Himedaka.
As a lubricating oil having biodegradability, for example, a polyol ester base oil having a weight ratio of a carboxylic acid having 5 to 14 carbon atoms and a carboxylic acid having 15 to 38 carbon atoms of 0.1: 99.9 to 50:50, Lubricating oil composition containing 0.1 to 15% by weight of at least one selected from sulfonates, condensates of alkanolamines and carboxylic acids having 5 to 14 carbon atoms, and polybutenyl succinimide (for example, Patent Document 1) Reference), an ester of a polyol having 3 to 12 carbon atoms and 3 to 6 total hydroxyl groups and a chain monocarboxylic acid having 6 to 22 carbon atoms, having a hydroxyl value of 35 mg KOH / g or more, a flash point of 290 ° C. or more, and a number Flame retardant hydraulic fluid containing a hydraulic fluid base oil mainly composed of a polyol partial ester having an average molecular weight of 600 to 1500 (see, for example, Patent Document 2), dimethylol C _{5 to} C ₇ Lubricating oil containing an ester of an alkane and a linear fatty acid of C _{10 to} C ₂₀ and containing a synthetic ester having a kinematic viscosity (40 ° C.) of 20 to 40 mm ² / s, a viscosity index of 120 or more, and a pour point of −30 ° C. or less (for example, a patent Reference 3), non-aqueous hydraulic oils containing a base oil composed of trimethylolpropane trioleate or neopentylglycoldiolate and a surfactant such as polyoxyethylene alkyl ether (for example, see Patent Document 4) are disclosed. ing.

  However, these biodegradable lubricating oils have relatively good lubricity and oxidation stability in terms of practical performance. However, it was not always satisfactory because metal elution was remarkable and the seal material expanded rapidly.

JP-A-5-339591 JP-A-6-228579 Japanese Patent Laid-Open No. 9-249889 JP 11-323373 A

  The present invention has been made under such circumstances, and is excellent in biodegradability, has a high viscosity index, a low pour point, and a high flash point, and has a good lubricating performance, oxidation stability, iron and non-ferrous metals. An object of the present invention is to provide a biodegradable lubricating oil composition having corrosion resistance to metals and compatibility with a sealing material.

As a result of intensive studies to develop a biodegradable lubricating oil composition having the above-mentioned preferable properties, the present inventors have obtained aliphatic hindered polyols and aliphatic monocarboxylic acids having a specific structure as a base oil. A synthetic ester base oil mainly composed of an ester and a specific additive added thereto at a predetermined ratio, and the biodegradation rate measured by the OECD test guideline 301C method is a certain value or more. It has been found that the oil composition can be adapted to its 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 A synthetic ester base oil containing 50% by mass or more of a hindered ester with a monocarboxylic acid, (B) (a) 0.1 to 5.0% by mass of a phenolic antioxidant, and (b) a low base number calcium. In the degradation test of a chemical substance by a microorganism according to the OECD test guideline 301C method, the biodegradation includes 0.01 to 2.0% by mass of a sulfonate and (c) 0.01 to 1.0% by mass of a triazole compound. A biodegradable lubricating oil composition characterized in that the rate is 60% or more,
(2) The biodegradable lubricating oil composition according to (1) above, 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,
(3) The biodegradable lubricating oil composition according to (1) or (2), wherein the viscosity index is 130 or more, the pour point is −40 ° C. or less, and the flash point is 250 ° C. or more.
(4) Fatty acid hindered polyols 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 (3), which is a compound represented by:
(5) The biodegradable lubricating oil composition according to the above (4), wherein the aliphatic hindered polyol is trimethylolpropane, neopentyl glycol, pentaerythritol or a dehydrated condensate thereof,
(6) The biodegradable lubricating oil composition according to any one of (1) to (5), wherein the aliphatic monocarboxylic acid is a saturated or unsaturated monocarboxylic acid having 6 to 22 carbon atoms,
(7) The biodegradable lubricating oil according to any one of (1) to (6) above, wherein the low base number calcium sulfonate as the component (B) (b) has a total base number of 0 to 100 mgKOH / g. Composition,
(8) The biodegradability according to any one of (1) to (7) above, which contains 0.1 to 5.0% by mass of an extreme pressure agent and / or an antiwear agent as the component (B) and (d). Lubricating oil composition,
Is to provide.

  According to the present invention, it is excellent in biodegradability, has a high viscosity index, a low pour point, a high flash point, and has a good lubricating performance, oxidation stability, anticorrosion against nonferrous metals, and compatibility with a sealing material. A synthetic ester biodegradable lubricating oil composition can be provided.

The biodegradable lubricating oil composition of the present invention contains a synthetic ester base oil as the base oil of the component (A), (a) a phenolic antioxidant as an additive of the component (B), A composition comprising a combination of a base number calcium sulfonate and (c) a triazole compound.
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 50% 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 to 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. Condensates, 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), etc. 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. As the dehydration condensates, bimolecular or trimolecular condensates are preferable.
The production method of the hindered polyols may be a conventionally known method. The dehydration condensate of hindered polyols can be usually obtained by dehydration condensation at about 180 ° C. in the presence of a catalyst by heating the hindered polyols to a melting point or higher and dispersing them in a solvent.

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

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. Further, the content of the hindered ester in the synthetic ester base oil is 50% by mass or more, preferably 70% by mass or more, more preferably in order for the lubricating oil composition to satisfy the following predetermined properties. Is 80% by mass or more.
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. For example, when used as a working oil, It is selected in the range of about 10 to ²⁰⁰ mm ² / s, preferably 10 to 100 mm ² / s, more preferably 15 to 80 mm ² / s.
The acid value of the synthetic ester base oil is preferably 3 mgKOH / g or less, particularly preferably 1 mgKOH / g or less, from the viewpoint of suppressing corrosion of the equipment. Further, the hydroxyl value is not particularly limited, but is preferably 50 mgKOH / g or less, particularly preferably 20 mgKOH / g or less, from the viewpoint of lubricity.

  In the lubricating oil composition of the present invention, the phenolic antioxidant of the component (a) in the additive of the component (B) is not particularly limited, and is appropriately selected from conventionally known phenolic antioxidants. Can be used. Examples of this phenolic antioxidant include 4,4′-methylenebis (2,6-di-t-butylphenol); 4,4′-bis (2,6-di-t-butylphenol); '-Bis (2-methyl-6-t-butylphenol); 2,2'-methylenebis (4-ethyl-6-t-butylphenol); 2,2'-methylenebis (4-methyl-6-t-butylphenol) 4,4′-butylidenebis (3-methyl-6-tert-butylphenol); 4,4′-isopropylidenebis (2,6-di-tert-butylphenol); 2,2′-methylenebis (4-methyl-); 6-t-nonylphenol); 2,2′-isobutylene bis (4,6-dimethylphenol); 2,2′-methylenebis (4-methyl-6-cyclohexylphenol); -Di-t-butyl-4-methylphenol; 2,6-di-t-butyl-4-ethylphenol; 2,4-dimethyl-6-t-butylphenol; 2,6-di-t-amyl-p -Cresol; 2,6-di-t-butyl-4- (N, N'-dimethylaminomethylphenol); 4,4'-thiobis (2-methyl-6-t-butylphenol); 4,4'- Thiobis (3-methyl-6-tert-butylphenol); 2,2′-thiobis (4-methyl-6-tert-butylphenol); bis (3-methyl-4-hydroxy-5-tert-butylpentyl) sulfide; bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide; n-octadecyl-3- (4-hydroxy-3,5-di-t-butylphenyl) propionate; 2,2′-thio [ Ethyl - bis-3- (3,5-di -t- butyl-4-hydroxyphenyl) propionate] and the like. Among these, bisphenol-based and ester group-containing phenol-based ones are particularly preferable.

  In this invention, these phenolic antioxidants may be used individually by 1 type, and may be used in combination of 2 or more type. The above-mentioned hindered esters used in synthetic ester base oils are excellent in oxidative stability per se, but by adding a phenolic antioxidant, the lubricating oil composition is further improved in oxidative stability. In addition, thermal stability is also improved. The compounding quantity of the said phenolic antioxidant is chosen in the range of 0.1-5.0 mass% based on the composition whole quantity. When the amount of the phenolic antioxidant is within the above range, the effect of improving the oxidation stability is exhibited, and the balance between the effect and the economic efficiency is good. A preferable blending amount of the phenolic antioxidant is in the range of 0.5 to 3.0% by mass. In addition, although the improvement effect of oxidation stability can be obtained even with an amine antioxidant, a phenolic antioxidant is used in the present invention from the viewpoint of ecological effects.

In the lubricating oil composition of the present invention, the low base number calcium sulfonate of the component (b) in the additive of the component (B) is an additive used for imparting a rust-preventing effect to the lubricating oil composition, and is clean. It also has a dispersing action. This calcium sulfonate is obtained by sulfonating an alkyl aromatic compound into a calcium salt. If the base number is too high, the solubility in a synthetic ester base oil is not sufficient. Therefore, in the present invention, those having a low base number of about 0 to 100 mgKOH / g (desirably 0 to 50 mgKOH / g) are used as the total base number (TBN).
This low base number calcium sulfonate may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, the compounding quantity is chosen in the range of 0.01-2.0 mass% based on the composition whole quantity. When the amount of the low base number calcium sulfonate is in the above range, the rust prevention effect is exhibited, and the balance between the effect and the economy is good. A preferable blending amount of the low base number calcium sulfonate is in the range of 0.05 to 1.0% by mass.

In the lubricating oil composition of the present invention, the triazole-based compound of component (c) in the additive of component (B) acts as a metal deactivator and imparts anticorrosive effects to non-ferrous metals and the like to the lubricating oil composition. Used for. Examples of the triazole compound include benzotriazole and derivatives thereof. These triazole compounds may be used alone or in combination of two or more. Moreover, the compounding quantity is chosen in the range of 0.01-1.0 mass% based on the composition whole quantity. When the amount of the triazole compound is in the above range, the anticorrosive effect is exhibited and the balance between the effect and the economical efficiency is good. A preferable blending amount of the triazole compound is in the range of 0.05 to 0.5% by mass.
In the lubricating oil composition of the present invention, even the base oil alone has the same level of lubricating performance as the mineral oil-based anti-wear hydraulic fluid, but in order to further improve the lubricating performance, if necessary, An extreme pressure agent and / or an antiwear agent can be blended.
As the extreme pressure agent, a sulfur-based extreme pressure agent or a phosphorus-based extreme pressure agent can be used. Examples of the sulfur-based extreme pressure agent include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, polysulfides, sulfurized olefins, thiocarbamates, thioterpenes, and dialkylthiodipropionates. Polysulfides and sulfurized olefins are preferred.
Examples of the phosphorous extreme pressure agent include phosphoric acid esters, (mono, di, tri) thiophosphoric acid esters, acidic phosphoric acid ester amine salts, (mono, di) thiophosphoric acid ester amine salts, phosphorous acid esters, ( And mono, di, tri) thiophosphite.
On the other hand, examples of the antiwear agent include zinc dithiophosphate (ZnDTP), zinc dithiocarbamate (ZnDTC), molybdenum sulfide oxydithiophosphate (MoDTP), and molybdenum sulfide oxydithiocarbamate (MoDTC).

One of these extreme pressure agents and antiwear agents may be used alone, or two or more thereof may be used in combination. Moreover, those total compounding quantities are normally selected in the range of 0.1-5.0 mass% based on the composition whole quantity. When the amount of the extreme pressure agent and / or the antiwear agent is within the above range, the antiwear effect is improved and the balance between the effect and the economy is good. A preferable blending amount of the extreme pressure agent and / or the antiwear agent is in the range of 0.5 to 3.0% by mass.
In the lubricating oil composition, as long as the effects of the present invention are not impaired, various additives, for example, viscosity index improvers, pour point depressants, ashless dispersants, surfactants, antifoaming agents, A demulsifier etc. can be mix | blended suitably.

Next, the properties of the lubricating oil composition of the present invention will be described.
In the lubricating oil composition, the biodegradation rate is 70% or more (standard is 60% or more) in the OECD test guideline 301C method microorganism degradation test, and has excellent biodegradability. Yes. 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 130 or more, preferably 140 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 130 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 impact on ecology, has a high viscosity index, a low pour point, and a high flash point, and has good lubricating performance, oxidation stability, Excellent balance of physical properties such as anti-corrosion against non-ferrous metals and compatibility with sealing materials
The lubricating oil composition is used for driving hydraulic oil, automatic transmission, shock absorber, power steering, etc., which is a power transmission fluid used for operation of power transmission, force control, buffering, etc. in hydraulic systems such as hydraulic equipment and devices. It is suitable as a lubricating oil for automobiles used for system equipment, gears and the like, metal working oil used for metal working such as cutting, grinding and plastic working.

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 according to 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) Hydroxyl value: Measured by pyridine-acetyl chloride method according to JIS K 0070.
(E) Flash point Measured according to JIS K 2265 using a Cleveland open-type (COC) tester.
(F) Pour point Measured according to JIS K 2269.
(G) 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.

(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) Lubrication performance (I) Shell four-ball EP test (ASTM D2783)
The measurement is carried out under the conditions of a rotational speed of 1800 rpm and room temperature, the maximum non-seizure load (LNL) and the fusion load (WL) are measured, and the load wear index (LWI) is obtained therefrom. The larger this value, the better the load resistance.
(B) Shell four-ball wear test (ASTM D2783)
The test is performed under the conditions of a rotational speed of 1200 rpm, a load of 294 N, a temperature of 50 ° C., and a time of 30 minutes, and the wear scar diameter is measured.
(C) FZG scoring test In accordance with ASTM D5182-91, a test is performed under the conditions of 90 ° C., 1450 rpm, 15 minutes, A type gear, and a scoring generation load stage is obtained.
(D) Vane pump test (according to ASTM D2882)
Wear amount of vane and cam ring after operating for 250 hours under conditions of 65 ° C, 13.7 MPa, 1,200 rpm, oil amount 60 L, flow rate of about 25 L / min using a vane pump (V-104C, manufactured by Vickers) Measure.

(5) Oxidation stability (I) IOT
A cylinder of 45 mmφ × 500 mm was charged with 300 mL of oil and tested with copper and iron as a catalyst at a temperature of 130 ° C. for 48 hours, or at a temperature of 150 ° C. for 48 hours, with an air suction of 10 liters / h. The kinematic viscosity ratio at 40 ° C. of the sample before and after the test (kinematic viscosity after test / kinematic viscosity before test) is determined.
(B) High-pressure circulation test Pump model: UCHIDA-REXROTH “A2FO-10 / 61R-PPB06” manufactured by Uchida Hydraulic Co., Ltd.
Pump pressure: 35 MPa
Flow rate: 13.6 L / min
Oil temperature: 80 ° C
Air blowing rate: 1NL / h
Catalyst: Cu coil (φ1.6mm × 60m)
Time: 600h
After performing the test under the above conditions, the kinematic viscosity ratio (kinematic viscosity after test / kinematic viscosity before test) of the sample before and after the test at 40 ° C. is determined. In the test, the time is not limited, the kinematic viscosity ratio is 1.1, the acid value increase is 2.0 mgKOH / g, Millipore value (vacuum filtration with 0.8 μm membrane filter, n-hexane washing, after drying The time during which the obtained fine contaminants) is any one of 10 (mg / 100 mL) is determined and defined as the life.

(6) Corrosion protection against non-ferrous metals After performing a high-pressure circulation test for 600 hours in the same manner as in (5) above, the amounts of Cu (elution from the catalyst) and Zn (elution from the piping material) contained in the oil were determined. taking measurement.
In addition, the metal immersion test was used together as other methods. The test was performed in the following order.
(A) Charge 100 g of test oil into a 200 mL mayonnaise bottle.
(B) The test piece is polished with 240 # sandpaper, then washed with gasoline, dried and weighed.
(C) One test piece is prepared in each bottle and left in a constant temperature bath at 100 ° C. for 168 hours.
(D) Take out the test piece, wipe off the oil with a waste cloth, wash with gasoline, and measure the weight after drying.
This time, the oil used in Comparative Example 6 was subjected to the above metal immersion test using a zinc test piece (1.0 mm × 26 mm × 60 mm), and a weight loss of 0.47% was observed.

(7) Seal material compatibility In accordance with JIS K 6258, a nitrile butadiene rubber (NBR) is subjected to an immersion test at 100 ° C. for 240 hours, and polyurethane is subjected to an immersion test at 120 ° C. for 240 hours. Rate of change after test of each physical property before test [mass change rate (%), volume change rate (%), hardness change amount (no unit), tensile change rate (%), elongation change rate at break (%) ].
In addition, the criteria for evaluation in each of the properties are as follows.
◎: Very good ○: Good △: Normal ×: Bad

Examples 1-3 and Comparative Examples 1-8
(1) While preparing the lubricating oil composition of the composition shown in Table 1 and Table 1, a commercially available product was prepared. The general properties and biodegradability of these lubricating oil compositions are shown in Table 2 and Table 2.

(note)
In Table 1 and Table 1, PET means pentaerythritol, TMP means trimethylolpropane, NPG means neopentyl glycol, ZnDTP means zinc dithiophosphate, and POE means polyoxyethylene.

(2) The lubricating performance, oxidation stability, and anticorrosive properties against non-ferrous metals of each lubricating oil composition are shown in Table 3 and Table 3.

(3) Table 4 shows the results of a sealing material compatibility test on the lubricating oil composition of Example 1 and the lubricating oil compositions of Comparative Examples 1 to 4.

  As is apparent from Tables 1 to 4, the lubricating oil compositions of the present invention (Examples 1 to 3) have excellent biodegradability and a high viscosity index, low pour point, and high flash point. It has an excellent balance of physical properties such as good lubrication performance, oxidation stability, anticorrosion against ferrous and non-ferrous metals, and compatibility with sealing materials.

The biodegradable lubricating oil composition of the present invention uses a synthetic ester base oil that is excellent in biodegradability, and has excellent lubricating properties and various physical property balances. For example, hydraulic oil, for automobiles It is suitably used as a lubricating oil, metalworking oil or the like.

Claims (8)

(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 50% by weight or more of a hindered ester, (B) (a) 0.1 to 5.0% by weight of a phenolic antioxidant, and (b) a low base number calcium sulfonate. In a degradation test of a chemical substance by microorganisms according to the OECD test guideline 301C method, the biodegradation rate is 60, including 0.01 to 2.0 mass% and (c) triazole compound 0.01 to 1.0 mass% A biodegradable lubricating oil composition characterized by being at least%. The biodegradable lubricating oil composition according to claim 1, 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 biodegradable lubricating oil composition according to claim 1 or 2, having a viscosity index of 130 or more, a pour point of -40 ° C or less, and a flash point of 250 ° C or more. Aliphatic hindered polyols have 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 4, wherein the aliphatic hindered polyol is trimethylolpropane, neopentyl glycol, pentaerythritol or a dehydration condensate thereof. The biodegradable lubricating oil composition according to any one of claims 1 to 5, wherein the aliphatic monocarboxylic acid is a saturated or unsaturated monocarboxylic acid having 6 to 22 carbon atoms. The biodegradable lubricating oil composition according to any one of claims 1 to 6, wherein (B) (b) the low base number calcium sulfonate has a total base number of 0 to 100 mgKOH / g. (B) The biodegradable lubricating oil composition according to any one of claims 1 to 7, comprising 0.1 to 5.0% by mass of an extreme pressure agent and / or an antiwear agent as the component (d).