JP3306199B2 - Lubricating oil composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition having excellent heat resistance and extreme pressure properties, and more particularly to a lubricating oil composition useful as an engine oil used at high temperatures and a lubricating oil for bearings.

[0002]

2. Description of the Related Art In recent years, lubricating oils used in turbocharged engines, ceramics engines, heat-insulated engines, etc., have recently been required to be lubricating oils capable of withstanding high temperatures exceeding 300 ° C. In particular, (1) heat resistance (2) It is required to have excellent properties such as excellent oxidation stability and the like, (2) excellent wear resistance (extreme pressure property and the like), low generation of deposits at high temperatures, and excellent cleanliness. .

In order to satisfy this requirement, sulfur-based extreme pressure agents such as disulfides and the like, phosphorus-based extreme pressure agents such as acid phosphates and alkylamine salts of acid phosphates have been known. There is a problem in oxidation stability at high temperatures.

Further, addition of an aromatic amine salt of an acidic alkyl phosphate ester, which is a kind of phosphorus-based extreme pressure agent, as an extreme pressure agent is disclosed in JP-A-56-141397, US Pat. No. 4,514,312. In the specification. The former relates to a lubricating oil composition based on mineral oil,
The latter is added to grease, and its operating temperature is at most 150 ° C. or less.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition which is excellent in oxidative stability and extreme pressure properties (load-bearing performance), and which can be used particularly at high temperatures.

[0006]

The lubricating oil composition of the present invention is characterized in that a phosphoric monoester and / or an amine salt of a phosphoric monoester and a phosphoric triester are added to a synthetic lubricating base oil. I do.

The phosphoric acid monoester of the present invention has the general formula

[0008]

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Wherein R ₁ is a C ₁ -C ₂₀ alkyl group;
Represents an aryl group, an aralkyl group, or an araryl group. )
And examples thereof include monomethyl phosphate, monobutyl phosphate, mono-2-ethylhexyl phosphate, monophenyl phosphate, and monocresyl phosphate.

The amine salts of phosphoric acid monoesters include octylamine, stearylamine, oleylamine, diisopropylamine, dioctylamine, triethylamine, trioctylamine, diphenylamine, and the like.
Such as phenyl-α-naphthylamine, di (alkylphenyl) amine (the alkyl group has 4 to 20 carbon atoms), p-methylaniline, p-nonylaniline, p-dodecylaniline, p-phenylaniline, and N-ethylaniline. An amine salt may be mentioned, and it is preferable that all or a part of the phosphoric acid monoester is aminated. Further, as the phosphoric acid triester, a general formula

[0011]

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Wherein R ₂ , R ₃ and R ₄ represent a C ₁ -C ₂₀ alkyl group, aryl group, aralkyl group or araryl group, for example, tributyl phosphate, phosphoric acid Examples include triphenyl ester and tricresyl phosphate.

In the present invention, the phosphoric acid monoester and / or its amine salt and the phosphoric acid triester are combined in a total amount of 0.01 to 5.0% by weight, preferably 0.01 to 5.0% by weight, based on the base oil. It is preferable to add 0.1% by weight to 2.0% by weight, and if 5.0% by weight or more is contained, it lacks oxidative stability at a high temperature of 200 ° C. or more, corrodes metals and increases viscosity,
Problems such as sludge formation occur. The use of an amine salt of a phosphoric acid monoester is particularly preferable because it has excellent oxidation stability and does not cause problems such as corrosion of metal, increase in viscosity, and generation of sludge as compared with a phosphoric acid monoester.

The ratio of the monoester of phosphoric acid to the triester of phosphoric acid is from 10/90 to 90/10 (molar ratio),
The mixing ratio is preferably 30/70 to 70/30 (molar ratio). If the mixing ratio is outside this range, it is not possible to achieve both oxidation stability and load-bearing performance.

Next, the base oil in the present invention is a synthetic lubricating oil having heat resistance, and examples thereof include polyol esters, diesters, polyphenyl ethers, and organopolysiloxanes. These base oils may be used alone or in combination. Preferably, polyol esters are used. The viscosity range of the base oil at 40 ° C. is 10 to 500 mm ² / s, preferably 20 to 480 mm ² / s.

First, examples of esters such as polyol esters and diesters include the following types of organic carboxylic esters. Since the following polyol ester oil particularly generates water in its production process, the base oil in the present invention is preferably sufficiently purified to reduce the water content.

(1) First, there are polyol esters of an aliphatic polyhydric alcohol and a linear or branched fatty acid. Examples of the aliphatic polyhydric alcohols forming the polyol esters include trimethylolpropane, ditrimethylolpropane, trimethylolethane, ditrimethylolethane, pentaerythritol, dipentaerythritol, and tripentaerythritol. Those having a number of 3 to 20 can be used, and preferred fatty acids are propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, isovaleric acid, neopentanoic acid, and 2-methylbutyric acid. , 2
-Ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2'-dimethyloctanoic acid, 2-butyloctanoic acid and the like.

Further, partial esters of an aliphatic polyhydric alcohol and a linear or branched fatty acid can also be used. As this aliphatic polyhydric alcohol, trimethylolpropane,
Ditrimethylolpropane, trimethylolethane, ditrimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol and the like can be used. Fatty acids having 3 to 20 carbon atoms include propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, Isodecanoic acid, 2,2′-dimethyloctanoic acid,
2-butyloctanoic acid and the like.

Esters of these aliphatic polyhydric alcohols with linear or branched fatty acids are particularly preferably pentaerythritol, dipentaerythritol, and tripentaerythritol having 5 to 12 carbon atoms, more preferably carbon atoms. Fatty acids of several 5 to 9, for example, valeric acid, hexanoic acid, heptanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2′-dimethyloctanoic acid, 2-butyl Esters composed of octanoic acid or a mixture thereof are mentioned.
These esters can be obtained by appropriately adjusting the number of moles of the reaction between the aliphatic polyhydric alcohol and the fatty acid to cause the reaction.

(2) Neopentyl glycol as an aliphatic polyhydric alcohol and a linear or branched fatty acid having 3 to 20 carbon atoms, for example, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid And diesters of nonanoic acid, 2-ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid and the like can also be used.

(3) Aliphatic polyhydric alcohol and C3-C3
Complex esters of 20 partial esters with linear or branched fatty acids and linear or branched aliphatic or aromatic dibasic acids can also be used. As the aliphatic polyhydric alcohol, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythitol and the like can be used. As fatty acids having 3 to 20 carbon atoms, propionic acid,
Butyric acid, isobutyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2 '-Dimethyloctanoic acid, 2-butyloctanoic acid and the like can be used.

Complex esters are preferably those having 5 to 7 carbon atoms, more preferably 5 carbon atoms.
It is preferred to use up to 6 fatty acids. As the fatty acid, valeric acid, hexanoic acid, isovaleric acid, 2-methylbutyric acid, 2-ethylbutyric acid or a mixture thereof is used, and those having 5 and 6 carbon atoms in a weight ratio of 10: 90- Fatty acids mixed in a ratio of 90:10 can be suitably used.

The aliphatic dibasic acids used for esterification with polyhydric alcohols together with this fatty acid include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid and dodecane acid. Diacid,
It is preferable to use tridecandioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid, docosanedioic acid, etc. Also, as the aromatic dibasic acid, phthalic acid, isophthalic acid, and as the aromatic tribasic acid, trimellitic acid, aromatic Examples of the tetrabasic acid include pyromellitic acid.

The ratio of the fatty acid to the aliphatic dibasic acid or aromatic dibasic acid, aromatic tribasic acid or aromatic tetrabasic acid is preferably 6: 1 (molar ratio). In this case, the ratio of the total amount of the fatty acid and the aliphatic dibasic acid or the aromatic dibasic acid to the amount of the aliphatic polyhydric alcohol to be used is preferably 7: 1 (molar ratio).

In the esterification reaction, first, a polyhydric alcohol and an aliphatic dibasic acid or an aromatic dibasic acid are reacted at a predetermined ratio to partially esterify, and then the partially esterified product is reacted with a fatty acid. Alternatively, the reaction order of the acids may be reversed, or the acids may be mixed and subjected to esterification.

(4) A linear or branched dialkyl ester of an aliphatic dibasic acid (having 16 to 22 carbon atoms) may be used.

The aliphatic dibasic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, tridecandioic acid, carboxyoctadecanoic acid and carboxymethyloctadecane. Acids, docosandioic acids and those having properties equivalent to these are exemplified. Preferred aliphatic dibasic acids are succinic acid, adipic acid, sebacic acid, undecandioic acid, dodecandioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid and the like.

The alcohol component is an alcohol having 5 to 8 carbon atoms, specifically, amyl alcohol, hexyl alcohol, heptyl alcohol and octyl alcohol, and isomers thereof, preferably isoamyl alcohol, isohexyl alcohol. And octyl alcohol.

Specifically, dioctyl adipate, di-
Isoheptyl adipate, dihexyl sebacate, diheptyl succinate and the like.

(5) Dialkyl esters of aromatic dibasic acids (having 18 to 26 carbon atoms) can also be used.

Examples of the aromatic dibasic acid include phthalic acid, isophthalic acid and the like, and the alcohol component in the dialkyl ester has 5 carbon atoms.
-8 alcohols, such as amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, and isomers thereof. Preferred alcohols include isoamyl alcohol, isoheptyl alcohol, and octyl alcohol. Aromatic diesters include dioctyl phthalate, diisoheptyl phthalate, diisoamino phthalate and the like.

(6) As alcohol components, trihydric alcohols such as monohydric alcohols selected from methanol, ethanol, propanol, butanol and the isomers thereof, glycerin and trimethylolpropane, and ethylene oxide, propylene oxide, 1 mol to 1 mol of alkylene oxide selected from butylene oxide, amylene oxide and the like, and isomers thereof
0 mol, preferably 1 to 6 mol of adduct is used.

As the organic carboxylic acid ester, an alkylene oxide adduct of a monohydric alcohol is prepared by adding adipic acid,
Pimelic acid, suberic acid, azelaic acid, sebacic acid,
There are diesters obtained by esterification with an aliphatic dibasic acid such as undecandioic acid, dodecandioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid, docosantioic acid, or an aromatic dibasic acid such as phthalic acid.

Further, alkylene oxides of polyhydric alcohols such as glycerin and trimethylolpropane are 1 to 10
The molar adduct is converted to a linear or branched fatty acid having 3 to 20 carbon atoms, such as propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, 2-decanoic acid, Methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid,
Esters obtained by esterification with 2,2'-dimethyloctanoic acid, 2-butyloctanoic acid or the like can be used.

As the fatty acid constituting the organic carboxylic acid ester, a linear or branched fatty acid can be used. However, when a branched fatty acid is used, the hydrolysis stability is more excellent. is there.

The above-mentioned organic carboxylic acid esters may be used alone, but in order to adjust the viscosity range according to the above-mentioned various uses, the above-mentioned organic carboxylic acid esters may be appropriately used in combination.

For example, when the complex type organic carboxylic acid ester of the above (3) is high in viscosity, it is an ester oil of an aliphatic polyhydric alcohol and a fatty acid having 3 to 9 carbon atoms at 100 ° C. A viscosity range of 6 mm ² / s or less can be added to adjust the viscosity range according to the application. When the viscosity is low, the viscosity may be adjusted by adding polymers to the organic carboxylic acid ester oil. The polymer preferably has a viscosity at 100 ° C. of 10 mm ² / s or more.

Examples of such polymers include polyalkyl methacrylates (for example, when the alkyl group has 4 to 8 carbon atoms).
), Polyalkylene glycol (for example, polypropylene glycol, or a copolymer composed of a polyethylene glycol component and a polypropylene glycol component, a copolymer composed of a polypropylene glycol component and a polytetramethylene glycol component), neopentyl glycol and a fat Polyesters with group dibasic acids can be mentioned. The amount of the polymer to be added is not particularly limited as long as an ester oil having a desired viscosity can be obtained, but can be usually in a range of 1% by weight to 99% by weight.

Next, examples of the alkyl diphenyl ether include monoalkyl diphenyl ether, dialkyl diphenyl ether, and trialkyl diphenyl ether synthesized by alkylating diphenyl ether using a Friedel-Crafts reaction and the like. Alternatively, it may be branched.

Examples of the polyphenyl ether include bis (m-phenoxyphenyl) ether, C-ethers and the like.

Next, as the organopolysiloxane,
Average unit formula

[0042]

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Wherein R represents the same or different, optionally halogenated hydrocarbon group having 1 to 18 carbon atoms, and a is a number from 1.9 to 2.1. are those, viscosity of 30 mm ² / s to 50 ten thousand ^{mm 2 / s (25 ℃)} , and preferably from 50 mm ² / s to 10 ten thousand mm ² / s.

In the formula, R represents a methyl group, an ethyl group, n
-Propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, decyl group,
And alkyl groups such as octadecyl group, phenyl group,
Aryl groups such as naphthyl groups, benzyl groups, aralkyl groups such as 1-phenylethyl group and 2-phenylethyl groups, araryl groups such as o-, m- and p-diphenyl groups, o- , M-, p-chlorophenyl group, o-, m
-, P-bromophenyl group, 3,3,3-trifluoropropyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group, heptafluoroisopropyl group and heptafluoro-n-propyl A halogenated hydrocarbon group such as In particular, R is preferably a fluorinated hydrocarbon group having 1 to 8 carbon atoms excluding an aliphatic unsaturated group, and is more preferably a methyl group or a phenyl group. Also,
A mixture of methylpolysiloxane and phenylpolysiloxane may be used.

The lubricating oil composition of the present invention may further contain an antioxidant, a corrosion inhibitor, a metal deactivator, a defoamer, a detergent / dispersant, an antiwear agent, a viscosity index improver, and the like. Good.
Examples of the antioxidant include di (alkylphenyl) amine (the alkyl group has 4 to 20 carbon atoms), phenyl-α-
Naphthylamine, alkyldiphenylamine (alkyl group having 4 to 20 carbon atoms), N-nitrosodiphenylamine, phenothiazine, N, N'-dinaphthyl-p-phenylenediamine, acridine, N-methylphenothiazine, N-ethylphenothiazine, dipyridylamine, diphenylamine , Phenolamine, 2,6-di-t-
Amine-based antioxidants such as butyl-α-dimethylaminoparacresol; 2.6-di-t-butylparacresol-
4.4'-methylenebis (2.6-di-t-butylphenol), 2.6-di-t-butyl-4-N, N-
Phenol antioxidants such as dimethylaminomethylphenol and 2.6-di-tert-butylphenol; organic iron salts such as iron octoate, ferrocene and iron naphthoate; cerium naphthoate and cerium toluate It is preferable to use an organometallic compound-based antioxidant such as an organic cerium salt such as silicate and an organic zirconium salt such as zirconium octoate. The above antioxidants may be used alone, but may be used in such a manner that a synergistic effect is exhibited by using two or more kinds in combination. The antioxidant may be used in an amount of 0.001 to 5% by weight, preferably 0.01 to 2% by weight, based on the base oil.

Isostearate, n
-Octadecyl ammonium stearate, duomin T-diolate, lead naphthenate, sorbitan oleate,
Pentaerythritol oleate, oleyl sarcosine,
Alkyl succinic acid, alkenyl succinic acid, and derivatives thereof, and the like are used in an amount of 0.000 to base oil.
1 to 1.0% by weight, preferably 0.01 to 0.5% by weight
Good to use.

As the metal deactivator, for example, benzotriazole, benzotriazole derivative, thiadiazole, thiadiazole derivative, triazole, triazole derivative, dithiocarbamate, etc. may be used. % By weight, preferably from 0.01% by weight to 1.0% by weight.

As an antifoaming agent, silicone is preferably used, and its use ratio is from 0.0001 to 0.1 with respect to the base oil.
003% by weight, preferably 0.0001 to 0.001% by weight.

As the ashless detergent / dispersant, for example, succinimides, amines, nonionic dispersants and the like are used.
Specific examples include polybutenylsuccinimide, sorbitan monooleate, sorbitan sesquiolate, and benzylamine. These are usually 0.5 to base oil.
It is used in a proportion of 15% by weight to 15% by weight.

The metal detergent generally includes phenates and / or sulfonates. The phenates are alkaline earth metal salts of sulfides of alkylphenols having an alkyl group having 8 to 30 carbon atoms, and are preferably calcium, magnesium or barium salts. Sulfonates with a molecular weight of 400 to 600
Or a metal salt of an alkyl-substituted aromatic compound sulfonate, preferably a calcium, magnesium or barium salt. Salicylates, phosphonates, naphthenates and the like as alkali metal earth salts can also be used. These metal-based detergents may be neutral type or overbased type having a base number of 300 or more.
Used in percentages by weight.

The antiwear agent is represented by the general formula (RO) ₃ P
= S (wherein R is an alkyl group, an aryl group, or a phenyl group and may be the same or different), and specifically, trialkylphosphorothionate, triphenylphospho Forothionate, sulfur-based antiwear agents such as alkyl diallyl phosphorothionate, diphenyl sulfide, diphenyl disulfide,
Di-n-butyl sulfide, di-n-butyl disulfide, di-tert-dodecyl disulfide, sulfides such as di-tert-dodecyl trisulfide, sulfurized palm oil, sulfurized oils such as sulfurized dipentene, Thiocarbonates such as xanthic disulfide, zinc thiophosphate-based wear inhibitors such as primary alkyl zinc thiophosphate, zinc secondary alkyl thiophosphate, zinc alkyl-allyl thiophosphate and zinc allyl thiophosphate can be used.

Other phosphorus-based wear inhibitors include phosphites such as triisopropyl phosphite and diisopropyl phosphite, hexamethylphosphoric triamide, and n-butyl-n-dioctyl phosphite. Carbonate, di-n-butylhexyl phosphonate,
Amine dibutyl phosphonate, dibutyl phosphoramidate can be used.

The use ratio of the antiwear agent is from 0.01% by weight to 5% by weight, preferably from 0.1% by weight to 5% by weight based on the base oil.
It is preferable to use 3% by weight, and it may be used alone or in combination of two or more.

Further, a viscosity index improver such as polyalkyl methacrylate, ethylene-propylene copolymer, styrene-butadiene copolymer and the like may be added to the lubricating oil composition of the present invention, if necessary. Further, a so-called dispersion type viscosity index improver having a dispersing property may be used.

Further, a viscosity index improver such as polyalkyl methacrylate, ethylene-propylene copolymer and styrene-butadiene copolymer may be added to the lubricating oil composition of the present invention, if necessary. Further, a so-called dispersion type viscosity index improver having a dispersing property may be used. In addition to these additives, general extreme pressure agents, rust inhibitors, and friction modifiers may be further added to the lubricating oil composition for high temperatures of the present invention.

[0056]

The lubricating oil composition of the present invention can provide a lubricating oil composition excellent in extreme pressure properties such as oxidative stability and load-bearing performance, and can be used at various high temperatures. Lubricating oil compositions such as engine oils and bearing lubricating oils. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

[0057]

EXAMPLES 1 mole of pentaerythritol and C ₅ -C ₉ acid (iso-C ₅ acid 15 wt%, n-C ₅ acid 28 wt%, n-C ₇
A polyol ester obtained by subjecting 4 mol of a mixed acid of 30% by weight of an acid and 27% by weight of an nC ₉ acid) to an esterification reaction was used as a base oil.

The following additives were added to the base oil at the following ratios to the base oil to prepare sample oils and comparative oils.

(Sample oil 1)-Monobutyl phosphate ... 0.5% by weight-Tributyl phosphate ... 0.5% by weight-Antioxidant (diphenylamine) ... 2.0% by weight (Sample Oil 2)-Monobutyl phosphate ... 0.3% by weight-Tributyl phosphate ... 0.7% by weight-Antioxidant (diphenylamine) ... 2.0% by weight (sample oil 3)-Phosphoric acid Dodecyl aniline salt of monobutyl ester: 0.5% by weight Tributyl phosphate: 0.5% by weight Antioxidant (diphenylamine): 2.0% by weight (comparative oil 1) Monophosphate Butyl ester ... 1.0% by weight-Antioxidant (diphenylamine) ... 2.0% by weight (comparative oil 2)-Tributyl phosphate ... 1.0% by weight-Antioxidant (Diphenylamine) ... 2.0% by weight (Comparative oil 3)-Dodecylaniline salt of monobutyl phosphate ... 1.0% by weight-Antioxidant (diphenylamine) ... 2.0% by weight The test method of load resistance and oxidation stability of each lubricating oil composition is shown. (1) Load resistance test ASTM D2596-
(2) Corrosion and oxidation stability test (Corrosion & Oxidation S)
tability Test) Federal Test Method STD 7
Al, A according to 91-5308 at 218 ° C. for 72 hours
The evaluation was performed using four types of metal catalysts, g, Fe, and Ti. The viscosity change rate is the viscosity change rate (%) of the lubricating oil composition before and after the test, and the total acid value change is the difference (mg KOH / g) between the total acid value of the lubricating oil composition before and after the test. .

The test results are shown in Table 1 below.

[0061]

[Table 1]

As can be seen from the table, it can be seen that the lubricating oil composition of the present invention has excellent oxidation stability and load resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C10N 30:08 C10N 30:08 40:02 40:02 40:25 40:25 (58) Field surveyed (Int.Cl. ⁷ , DB name) C10M 137/04-137/08 C10N 30:04-30:08 C10N 40:02 C10N 40:25-40:28

Claims (1)

(57) [Claims] 1. A lubricating oil composition comprising a synthetic lubricating base oil and a phosphoric acid monoester and / or an amine salt of the phosphoric acid monoester and a phosphoric acid triester.