JP2000336384A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricating oil composition capable of reducing the friction coefficient at an oil-impregnated bearing and improving abrasion resistance when the composition is used as the impregnation bearing oil. SOLUTION: This lubricating oil composition is obtained by compounding the base oil of a lubricating oil with (a) a phosphoric acid ester, (b) a fatty acid polyhydroxy alcohol ester, (c) triphenyl phosphorothionate and (d) an N- acyl-N-hydrocarbonoxyalkyl aspartic acid ester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition. More specifically, it relates to a lubricating oil composition suitably used for impregnated bearings and the like.

[0002]

2. Description of the Related Art Generally, the friction coefficient of a base oil is reduced by adding an extreme pressure agent or an oil agent to the base oil. As extreme pressure agents, phosphorus compounds, sulfur compounds, chlorine compounds, metal organic compounds, etc., and as oil agents, fatty acids, higher alcohols, polyhydric alcohol esters, fatty acid esters, aliphatic amines, aliphatic monoglycerides Are used in various combinations as necessary.

However, when selecting a combination of extreme pressure agents, corrosion and wear of the friction surface may occur depending on the load area, as in the case of using the extreme pressure agent alone. In addition, when selecting an oily agent, since all of the oily agents have a polar group in the molecular structure, they have the property of coordinating or adsorbing strongly to the metal, and have a strong bonding force between them. Therefore, it is necessary to pay attention to the solubility in the base oil. This causes turbidity in appearance of the lubricating oil composition, and even when dissolved under room temperature conditions, causes turbidity and reduced fluidity at low temperatures.

JP-A-6-200268 discloses N-acyl-N-
A description is given of a lubricating oil composition containing a hydrocarbonoxyalkyl aspartate and an antiwear agent. Although this lubricating oil composition achieves good wear resistance, it is not sufficient for reducing the coefficient of friction.

[0005] In particular, when the lubricating oil composition is applied to an impregnated bearing represented by a sintered oil-impregnated bearing, it has good compatibility with the bearing material, does not generate corrosion or sludge, and is used in a wide temperature range. It can be used, more specifically, it can be used in a temperature range of about -40 to + 150 ° C., particularly in automobiles, has a small evaporation loss at high temperatures, has good oxidation stability, and can be used at low temperatures. It is required that the fluidity is not impaired, and in order to cope with recent miniaturization, low current, and long life, good resin resistance, low friction coefficient, good wear resistance, etc. Are also required.

[0006] A sintered oil-impregnated bearing is a kind of slide bearing which is used in a self-lubricated state by impregnating a lubricating oil, and is a self-lubricating system which is relatively inexpensive, has relatively low friction, and has high precision. It is widely used as a motor bearing and the like in various parts ranging from electronic parts for automobiles, audiovisual equipment, office equipment, electronic equipment for home appliances, and a drive unit for computer auxiliary storage device.

In recent years, as the performance of these various devices has been improved, the performance required for sintered oil-impregnated bearings has also been reduced in size and speed.
It is becoming very severe, such as low current and low power consumption. To meet these demands, the bearing manufacturer must consider bearing materials and other factors, but the performance of several milligrams of lubricating oil impregnated in the bearings will greatly affect the characteristics and life of the motor. Is coming.

[0008] In order to solve such demands, zinc dialkyldithiophosphate, Mo-
Dialkyldithiocarbamate, Mo-dialkyldithiophosphate or those containing sulfur-phosphorus extreme pressure additives (Japanese Patent Application Laid-Open No. 7-53984) and those containing dihydrocarbyl hydrogendiene phosphite or trihydrocarbyl phosphate containing a hydrocarbyl group ( Id 9-489
No. 89) has been proposed, but even these lubricating oil compositions cannot actually satisfy all of the above-mentioned various requirements.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition which, when used as an impregnated bearing oil, can reduce the coefficient of friction at the oil-impregnated bearing portion and improve the wear resistance. It is in.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
(A) phosphoric acid ester, (b) polyhydric alcohol fatty acid ester, (c) triphenyl phosphorothionate and (d) N-acyl-N-hydrocarbonoxyalkyl aspartate to lubricating base oil Achieved by the added lubricating oil composition.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a lubricating base oil, for example,
-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, polyalkylene glycol, polyphenylether, alkyl-substituted diphenylether, polyol ester, dibasic acid ester, phosphate ester, phosphite ester,
Synthetic oils such as carbonate esters, silicone oils, and fluorinated oils,
At least one kind of mineral oil such as paraffinic mineral oil, naphthenic mineral oil or mineral oil refined by appropriately combining solvent refining, hydrorefining and the like is used.

Further, depending on the application, a resin material or a rubber material is rarely used at or around a use site, and in that case, a lubricating base oil having little influence on these materials, generally Is poly-α-olefin,
It is preferable to use ethylene-α-olefin copolymers or those mainly composed of these.

The type and properties of these various lubricating base oils are not particularly limited and may be appropriately selected depending on the conditions of use. Generally, the kinematic viscosity (40 ° C.) is about 2 to 1000 cSt, preferably about 5 to 1000 cSt. ~ 500 cSt is used. If a kinematic viscosity of less than this is used, it may cause a decrease in life, wear, or seizure such as an increase in evaporation loss and a decrease in oil film strength. In
There is a possibility that power consumption and torque increase such as an increase in viscous resistance may occur.

In the lubricating base oil, a lubricating base oil to which a viscosity index improver is added may be used. As the viscosity index improver, for example, ethylene-propylene copolymer, styrene-isobutylene copolymer, polystyrene, polyisobutylene, polyacrylate, polymethacrylate and the like are used. The molecular weight of these polymers is not particularly limited, but in order to sufficiently improve the viscosity index, the number average molecular weight Mn is about 3000 to 10
It is desirably in the range of 00000, preferably about 3000-300000.

As the phosphoric acid ester of the component (a) added to the lubricating base oil, those conventionally used as extreme pressure agents or antiwear agents can be used as they are. As the phosphate ester, an alkyl phosphate ester, an aromatic phosphate ester, a halogen-containing phosphate ester, an acidic phosphate ester, or the like is used.

More specifically, alkyl phosphates include tributyl phosphate, tri (2-ethylhexyl) phosphate, tri (butoxyethyl) phosphate, and trioleyl phosphate, and aromatic phosphates include triphenyl phosphate. Phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, and the like, as halogen-containing phosphates, tris (chloroethyl) phosphate, tris (dichloropropyl) Phosphate, tris (tribromophenyl) phosphate, tris (dibromophenyl) phosphate, tris (tribromoneopentyl) phosphate, etc., as acidic phosphates, Chill acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl acid phosphate, monobutyl acid phosphate, 2-ethylhexyl acid phosphate, di (2-ethylhexyl) acid phosphate, isodecyl acid phosphate, monoisodecyl acid phosphate, etc. are used, respectively. Can be Among these various phosphates, aromatic phosphates are preferably used from the viewpoint of thermal stability and abrasion prevention effect, and corrosion of the friction surface and generation of sludge can be reduced. Further, these phosphate esters include di (n-butyl) phosphate dodecylamine, di (n-butyl) phosphateoctylamine, di (n-butyl) phosphatecyclohexylamine, di (2-ethylhexyl) phosphateoctylamine, It is also used as an amine salt such as (2-ethylhexyl) phosphate butylamine and di (2-ethylhexyl) phosphate ethylamine.

At least one of these phosphate esters is used in an amount of about 0.01 to 5%, preferably about 0.
It is used at a rate that accounts for 05-2%. If the addition ratio is lower than this, the contribution to the friction and wear characteristics becomes insufficient, while if added at a higher ratio, not only does the effect not increase for the addition ratio, but also metal corrosion and sludge generation. Will have a negative effect on the point.

As the polyhydric alcohol fatty acid ester of the component (b), those which are conventionally used as oil agents, that is, polyhydric alcohols such as glycerin, sorbitan, alkylene glycol, neopentyl glycol, trimethylolpropane and pentaerythritol can be used. Full or partial esters of saturated or unsaturated fatty acids having 1 to 24 carbon atoms are used.

More specifically, glycerin esters include glycerin monolaurate, glycerin monostearate, glycerin monopalmitate, glycerin monooleate, glycerin dilaurate, glycerin distearate, glycerin dipalmitate, glycerin Dioleate, etc., as sorbitan esters,
Sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan dilaurylate, sorbitan dipalmitate, sorbitan distearate, sorbitan dioleate, sorbitan tristearate, sorbitan trilaurate, Sorbitan trioleate, sorbitan tetraoleate and the like, alkylene glycol esters include ethylene glycol monolaurate, ethylene glycol monostearate, ethylene glycol monooleate, ethylene glycol dilaurate, ethylene glycol distearate, ethylene glycol dioleate. Eate, propylene glycol monolaurate, propylene glycol monostearate, propylene glycol Oleate, propylene glycol dilaurate, propylene glycol distearate, propylene glycol dioleate, and examples of the neopentyl glycol ester, neopentyl glycol monolaurate, neopentyl glycol monostearate, neopentyl glycol monooleate,
Neopentyl glycol dilaurate, neopentyl glycol distearate, neopentyl glycol dioleate, and the like, as trimethylolpropane esters, trimethylolpropane monolaurate, trimethylolpropane monostearate, trimethylolpropane monooleate , Trimethylolpropane dislaurate, trimethylolpropane distearate,
Trimethylolpropanediolate, pentaerythritol monolaurate and the like, and pentaerythritol esters as pentaerythritol monostearate, pentaerythritol monooleate, pentaerythritol dilaurate, pentaerythritol distearate, pentaerythritol dioleate And dipentaerythritol monooleate are preferably used, and a partial ester of a polyhydric alcohol with an unsaturated fatty acid is preferably used.

These polyhydric alcohol fatty acid esters are used in an amount of about 0.01 to 5%, preferably about 0.01 to 5% by weight of each essential component composition.
Used at a rate of 0.05-2%. The component (b) contributes to the reduction of the friction coefficient, but if the addition ratio is out of this range, the reduction of the friction coefficient cannot be expected.

The triphenylphosphorothionate of the component (c) is represented by the formula (C ₆ H ₅ O) ₃ P = S, wherein the phenyl group is an alkyl group, preferably an alkyl group having 3 to 18 carbon atoms. It may be mono- or poly-substituted. Triphenylphosphorothionate is used in an amount of about 0.01 to 5%, preferably about 0.05 to 2% by weight based on the weight of each essential component composition, and contributes to improvement of abrasion resistance. Therefore, if the additive ratio is less than this, the improvement of the abrasion resistance becomes insufficient. On the other hand, even if it is added at a higher ratio, the performance is not improved for the added amount, which is economically disadvantageous. Become.

The component (d), N-acyl-N-hydrocarbonoxyalkyl aspartate, is represented by the general formula R ^{1 is} a carboxyl group-substituted alkoxyl group having 2 to 30 carbon atoms, and the carboxyl group may be an alkali metal salt, an alkaline earth metal salt or an amine salt (Example) 3-carboxy-1-oxo-propyl Group R ² : alkoxyalkyl group having 6 to 30 carbon atoms (Example) 3-cyclohexyloxypropyl group 3-octyloxypropyl group 3-isooctyloxypropyl group 3-decyloxypropyl group 3-isodecyloxypropyl group 3- (C ₁₂ -C ₁₆ ) alkoxypropyl group R ³ -R ⁷ : A compound represented by a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, which is represented by about 0.01 to
It is used in an amount of 5% by weight, preferably about 0.05 to 2%, and contributes to improvement of abrasion resistance. Therefore, if the addition ratio is less than this, the improvement of the abrasion resistance becomes insufficient.On the other hand, if the addition ratio is higher than this, the performance is not improved for the added amount, and it is not only economically disadvantageous. In addition, the friction coefficient is adversely affected.

In addition to the above essential components, conventional pour point depressants, ashless dispersants, metal detergents, antioxidants, rust inhibitors, corrosion inhibitors, defoamers, friction modifiers, etc. Known additives used in lubricating oils can be added and used depending on the application.

Examples of the pour point depressant include polymethacrylate, polyacrylate, di (tetraparaffinphenol) phthalate, condensation products of tetraparaffinphenol, condensation products of alkylnaphthalene, chlorinated paraffin-naphthalene condensates, and alkylation products. Polystyrene and the like, as ashless dispersants, for example, succinimide type, succinamide type, benzylamine type, ester type and the like, and as the metal type detergent, for example, dinonyl naphthalene sulfonic acid is represented. Metal salts such as sulfonic acid, alkylphenol and salicylic acid are used.

Examples of the antioxidant include 2,6-di-tert-butyl-4-methylphenol and 4,4'-methylenebis
Phenolics such as (2,6-ditert-butylphenol), alkyl (4 to 20 carbon atoms) diphenylamine, triphenylamine, phenyl-α-naphthylamine, phenothiazine, alkylated phenyl-α-naphthylamine, phenithiazine, alkyl At least one of amine-based compounds such as phenothiazine hydride is used. As the rust inhibitor, for example, fatty acid, fatty acid soap, alkyl sulfonate, fatty acid amine, oxidized paraffin, alkyl polyoxyethylene ether and the like are used. As corrosion inhibitors, for example, benzotriazole, benzimidazole,
Thiadiazole and the like are used. As the defoaming agent, for example, dimethylpolysiloxane, polyacrylic acid, metal soap, fatty acid ester, phosphate ester and the like are used.

[0026]

According to the lubricating oil composition of the present invention, the reduction of the coefficient of friction leads to the reduction of the torque and the current value. Improvement also promotes longer life. Further, since turbidity at a low temperature and corrosion and sludge formation of a metal at a high temperature are small, it can be used in a wide temperature range.

The lubricating oil composition of the present invention exhibiting such improved properties is suitably used for impregnated bearings, especially sintered oil-impregnated bearings, and reduces the coefficient of friction at the site where various parts or equipment are used. And it greatly contributes to improvement of wear resistance.

[0028]

Next, the present invention will be described with reference to examples.

Examples 1 to 6 Base oil A [Poly-α-olefin manufactured by Mobile Chemical Co., Ltd.
Kinematic viscosity (40 ° C; same hereafter) 30 cSt] 100 parts (weight, same below)
Was added to each of the following additives to prepare a composition. Example (Part) Additive 1 2 3 4 5 6 [Component (a)] Tricresyl phosphate 1.0 2.0 1.0 1.0 1.0 Triphenyl phosphate 1.0 [Component (b)] Pentaerythritol monooleate 0.5 1.0 0.5 Glycerin monooleate 0.5 0.5 Sorbitan monooleate 0.5 [Component (c)] Triphenyl phosphorothionate 1.0 1.0 1.0 1.0 1.0 Alkyl triphenyl phosphorothionate 0.2 1.0 [Component (d)] N-acyl-N-hydrocarbonoxy 0.5 0.2 0.3 0.5 0.5 0.5 Alkyl aspartate (K-CORR 100A2, King product)

The obtained composition was subjected to measurement tests for the following items. (Shell abrasion test) Using a shell four-ball tester, measure the wear scar diameter (unit: mm) after testing under the following conditions Test piece: SUJ2 (1/2 inch), class 20 Revolution: 1200 rpm Load: 40 kgf Temperature: Room temperature Test time: 60 minutes (Pendular test) Using a Soda-type pendulum type friction tester, measure the friction coefficient under the following conditions Ball: SUJ2 (3/16 inch) Roller pin: SUJ2 Temperature: Room temperature Load: Left and right- 80g, center -40g

Examples 7 to 11 Base oils: Base oil B (Example 7): poly-α-olefin manufactured by Mobil Chemical Co., Ltd., kinematic viscosity: 411 cSt Base oil C (Example 8): Kao product pentaerythritol ester (Kaoloop) 268), kinematic viscosity 33 cSt Base oil D (Example 9): di (2-ethylhexyl) sebacate,
Kinematic viscosity 12 cSt base oil E (Example 10): Asahi Denki Co., Ltd. glycol oil (ADEKA CARPOL M-60), kinematic viscosity 60 cSt base oil F (Example 11): Matsumura Sekiyu product alkyl-substituted diphenyl ether (Moresco Hylube LB100) ) And a kinematic viscosity of 104 cSt (100 parts) were used, and the following additives were added thereto to prepare a composition. Example (Part) Additive 7 8 9 10 11 [Component (a)] Tricresyl phosphate 1.0 1.0 Triphenyl phosphate 0.9 1.0 Phosphate amine salt 0.1 1.0 [Component (b)] Pentaerythritol monooleate 1.0 Glycerin mono Oleate 0.5 0.5 0.5 Sorbitan monooleate 0.5 [Component (c)] Triphenylphosphorothionate 1.0 0.5 1.0 1.0 Alkyltriphenylphosphorothionate 0.5 1.0 [Component (d)] N-acyl-N-hydrocarbonoxy 0.5 0.5 0.3 0.5 0.1 Alkyl aspartate (K-CORR 182CA, King product)

Examples 12-16 Compositions were prepared by adding the following additives to 100 parts of two types of base oil mixtures. Base oil G: Japan Petrochemical Alkylbenzene (Alkene 5
6N), kinematic viscosity 6 cSt Example (part) Composition component 12 13 14 15 16 [Base oil] Base oil A 50 80 80 80 80 Base oil B 50 Base oil C 20 Base oil D 20 Base oil F 20 Base oil G 20 [(a) component] tricresyl phosphate 1.0 0.9 1.0 1.0 0.5 triphenyl phosphate 0.1 0.5 [(b) component] pentaerythritol monooleate 1.0 0.4 glycerin monooleate 0.5 sorbitan monooleate 0.1 1.0 0.5 0.5 [(c Component) Triphenyl phosphorothioate 1.0 0.5 1.0 1.0 0.5 Alkyl triphenyl phosphorothioate 0.5 0.5 [Component (d)] N-acyl-N-hydrocarbonoxy 0.5 0.5 0.2 0.5 0.5 Alkyl aspartate (King Co., Ltd.) Product K-CORR 181CA)

Comparative Examples 1 to 7 Compositions were prepared by adding the following additives to 100 parts of base oil A, base oil C, base oil F or a mixture. Comparative Example Composition Component 1 2 3 4 5 6 7 [Base oil] Base oil A 100 100 100 100 80 Base oil C 20 100 Base oil F 100 [Component (a)] Tricresyl phosphate 1.0 1.0 1.0 1.0 [(b Component) Glycerin monooleate 0.5 1.0 1.0 [Component (c)] Triphenyl phosphorothionate 1.0 0.5 1.0 [Component (d)] N-acyl-N-hydrocarbonoxy 0.2 0.5 Alkyl aspartate (King's product) K-CORR 100A2)

The measurement results in the above Examples and Comparative Examples are shown in the following table. Table example Shell wear scar diameter (mm) Pendulum type friction coefficient Example 1 0.35 0.104 〃 2 0.33 0.107 ３ 3 0.37 0.110 ４ 4 0.33 0.108 ５ 5 0.38 0.106 ６ 6 0.35 0.108 ７ 7 0.35 0.110 ８ 8 0.39 0.112 ９ 9 0.39 0.112 〃 10 0.41 0.110 〃 11 0.40 0.111 〃 12 0.33 0.105 〃 13 0.36 0.107 〃 14 0.35 0.104 〃 15 0.37 0.106 〃 16 0.38 0.108 Comparative Example 1 0.52 0.135 〃 2 0.58 0.152 ３ 3 0.49 0.129 〃 4 0.55 0.140 〃 5 0.52 0.132 6 0.68 0.145 ７ 7 0.49 0.152

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 4, 1999 (1999.6.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

The component (c) triphenylphosphorothionate is represented by the formula (RC ₆ H ₄ O) ₃ P = S , wherein R is water
A hydrogen atom or an alkyl group, preferably an alkyl group having 3 to 18 carbon atoms.
Is a alkyl group . Triphenylphosphorothionate is present in an amount of about 0.01-5%, preferably about 0.01%, by weight of each essential component composition.
It is used at a ratio of 0.05 to 2% by weight and contributes to improvement of wear resistance. Therefore, if the additive ratio is less than this, the improvement of the abrasion resistance becomes insufficient. On the other hand, even if it is added at a higher ratio, the performance is not improved for the added amount, which is economically disadvantageous. Become. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 21, 2000 (2007.2)
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

More specifically, glycerin esters include glycerin monolaurate, glycerin monostearate, glycerin monopalmitate, glycerin monooleate, glycerin dilaurate, glycerin distearate, glycerin dipalmitate, glycerin Dioleate, etc., as sorbitan esters, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan dilaurate, sorbitan dipalmitate, sorbitan distearate, sorbitan dioleate , sorbitan tristearate, sorbitan Tanto lira selling rate, sorbitan trioleate, Seo
Rubitan tetraoleate and the like, as alkylene glycol esters, ethylene glycol monolaurate, ethylene glycol monostearate, ethylene glycol monooleate, ethylene glycol dilaurate, ethylene glycol distearate, ethylene glycol dioleate, propylene Glycol monolaurate, propylene glycol monostearate,
Propylene glycol monooleate, propylene glycol dilaurate, propylene glycol distearate, propylene glycol dioleate and the like, and neopentyl glycol esters as neopentyl glycol monolaurate, neopentyl glycol monostearate, neopentyl glycol Monooleate, neopentyl glycol dilaurate, neopentyl glycol distearate, neopentyl glycol dioleate, etc., as trimethylolpropane esters, trimethylolpropane monolaurate,
Trimethylolpropane monostearate, trimethylolpropane monooleate, trimethylolpropane dilaurate, trimethylolpropane distearate, trimethylolpropanediolate, pentaerythritol monolaurate, and the like. Erythritol monostearate, pentaerythritol monooleate, pentaerythritol dilaurate, pentaerythritol distearate, pentaerythritol dioleate,
Dipentaerythritol monooleate or the like is used, and a partial ester of a polyhydric alcohol with an unsaturated fatty acid is preferably used.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C10N 40:02 F term (reference) 4H104 BB34C BE11C BH03C BH06C DA02A EB02 LA03 LA04 PA01 RA03

Claims (3)

[Claims] 1. A lubricating base oil comprising: (a) a phosphate ester, (b) a polyhydric alcohol fatty acid ester, (c) triphenyl phosphorothionate and (d) N-acyl-N-hydrocarbon A lubricating oil composition comprising an oxyalkyl aspartate ester. 2. The lubricating oil composition according to claim 1, which is used for an impregnated bearing. 3. The impregnated bearing is a sintered oil-impregnated bearing.
The lubricating oil composition according to the above.