JP5739121B2 - Lubricating base oil and lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating base oil and lubricating oil composition containing an ionic liquid.

Lubricating oils are generally composed of organic substances mainly composed of hydrocarbons, and lowering the viscosity inevitably increases the vapor pressure, increasing the evaporation loss of the lubricating oil and further increasing the risk of ignition. In particular, a lubricating oil (for example, hydraulic hydraulic oil) used in equipment that handles a high-temperature object such as a machine in a steelworks is required to have flame retardance from the viewpoint of fire prevention. In addition, in a precision motor used in recent information equipment (for example, a hard disk), lubricating oil that is difficult to evaporate and scatter is required in order to minimize the influence on peripheral precision equipment.
On the other hand, in recent years, it has been reported that an ionic liquid composed of a cation and an anion has excellent thermal stability and high ionic conductivity, and becomes a stable liquid even in air (for example, see Non-Patent Document 1). ). And various applications, such as solar cells, taking advantage of such features as the thermal stability (refractory volatility, flame retardancy), high ion density (high ion conductivity), large heat capacity, and low viscosity of such ionic liquids Application research is actively conducted as an electrolyte solution (see, for example, Patent Document 1), an extraction separation solvent, a reaction solvent, and the like.
It has also been proposed to use such an ionic liquid as a lubricating base oil (see, for example, Patent Document 2). Since ionic liquids are not linked by intermolecular attractive forces like molecular liquids but by strong ionic bonds, ionic liquids are difficult to volatilize and are flame retardant, and are resistant to heat and oxidation. It is a stable liquid. Therefore, even if it has a low viscosity, it has a low evaporation property and is also excellent in heat resistance.

Japanese Patent Laid-open No. 2003-3270 International Publication No. 2005/035702

“J. Chem. Soc., Chem. Commun.”, 1992, p. 965

  The ionic liquid is a low viscosity, low vapor pressure and excellent heat resistance as a lubricating base oil, but the ionic liquid described in the examples of Patent Document 2 is likely to corrode metals in a high temperature environment. Not enough in terms. Thus, in patent document 2, it is not clear about what kind of cation and anion is optimal as an ionic liquid used for lubricating base oil.

  Therefore, the present invention has been made in view of the above circumstances, and even if the viscosity is low, the vapor pressure is low, there is no danger of ignition, it has excellent heat resistance, it is difficult to corrode metals at high temperatures, and low temperature flow An object of the present invention is to provide a lubricating base oil having excellent properties and a lubricating oil composition using the lubricating base oil.

In order to solve the above problems, the present invention provides the following lubricating base oil and lubricating oil composition.
That is, the lubricating base oil of the present invention has the following general formula (1):
Z ⁺ A ⁻ (1)
(Z ⁺ means a cation and A ⁻ means an anion.)
A lubricating base oil containing one or more ionic liquids comprising a compound represented by the formula: wherein Z ⁺ is a cyclic quaternary ammonium ion having two different side chains, and A ⁻ is a conjugated amide ion. It is a feature.

In the lubricating base oil of the present invention, A ⁻ in the ionic liquid represented by the general formula (1) is selected from anions having a structure represented by the following general formula (2). Is necessary .

（式（２）中、ｎは１から４までの整数であり、ｍは１から４までの整数であり、それらは同一でも異なっていてもよい。）

(In Formula (2), n is an integer from 1 to 4, m is an integer from 1 to 4, and they may be the same or different.)

In the lubricating base oil of the present invention, Z ⁺ in the ionic liquid represented by the general formula (1) is selected from cations having a structure represented by the following general formula (3). Is necessary .

（式（３）中、ｎは２であり、Ｘはメチレンまたは酸素であり、Ｒ _１、Ｒ_２は、メチル基、ブチル基および２−メトキシエチル基から選ばれる基である。）

(In Formula (3), n is 2 , X is methylene or oxygen, and R ₁ and R ₂ are groups selected from a methyl group, a butyl group, and a 2-methoxyethyl group.)

In the lubricating base oil of the present invention, the molecular weight of the ionic liquid is preferably 410 or more and 570 or less.
In the lubricating base oil of the present invention, the ionic liquid preferably has a 40 ° C. kinematic viscosity of 1 mm ² / s to 100 mm ² / s.
In the lubricating base oil of the present invention, the pour point of the ionic liquid is preferably 0 ° C. or lower.

The lubricating oil composition of the present invention comprises an antioxidant, an oily agent, an extreme pressure agent, a cleaning dispersant, a viscosity index improver, a rust inhibitor, a metal deactivator, and an anti-oxidant. It is characterized by blending at least one of foaming agents.
The lubricating oil composition of the present invention is preferably used for lubricating oil-impregnated bearings, fluid bearings, vacuum equipment, and semiconductor manufacturing equipment.

  According to the present invention, a lubricating base oil having low vapor pressure, low vapor pressure, no risk of ignition, excellent heat resistance, corrosion resistance to metals at high temperatures, and excellent low-temperature fluidity. A lubricating oil composition using this lubricating base oil can be provided.

The lubricating base oil of the present invention comprises one or more ionic liquids described below.
The ionic liquid used in the present invention has the following general formula (1):
Z ⁺ A ⁻ (1)
(Z ⁺ means a cation and A ⁻ means an anion.)
It is an ionic liquid which consists of a compound represented by these.
In such an ionic liquid, in the general formula (1), Z ⁺ is a cyclic quaternary ammonium ion having two different side chains, and A ⁻ is a conjugated amide ion.

A ⁻ in the general formula (1) is preferably selected from anions having a structure represented by the following general formula (2).

In the general formula (2), n is an integer from 1 to 4, and is preferably 1 or 2 from the viewpoint of the molecular weight of the ionic liquid. M is an integer from 1 to 4, and is preferably 1 or 2 from the viewpoint of the molecular weight of the ionic liquid. m and n may be the same or different.
Examples of the anion having the structure represented by the general formula (2) include bis (trifluoromethanesulfonyl) amide, bis (pentafluoroethanesulfonyl) amide, bis (heptafluoropropanesulfonyl) amide, and bis (nonafluorobutane). Sulfonyl) amide, trifluoromethanesulfonyl (pentafluoroethanesulfonyl) amide, pentafluoroethanesulfonyl (heptafluoropropanesulfonyl) amide, heptafluoropropanesulfonyl (nonafluorobutanesulfonyl) amide, trifluoromethanesulfonyl (heptafluoropropanesulfonyl) amide, Pentafluoroethanesulfonyl (nonafluorobutanesulfonyl) amide, trifluoromethanesulfonyl (nonafluorobutanesulfonyl) a De, and the like. Among these, from the viewpoint of the molecular weight of the ionic liquid, bis (trifluoromethanesulfonyl) amide, bis (pentafluoroethanesulfonyl) amide, and trifluoromethanesulfonyl (pentafluoroethanesulfonyl) amide are preferable, and bis (trifluoromethanesulfonyl) amide is preferable. Particularly preferred.

Z ⁺ in the general formula (1) is preferably selected from cations having a structure represented by the following general formula (3).

In the general formula (3), n is 1 or 2, and X is methylene or oxygen. R ₁ and R ₂ are groups selected from an alkyl group having 1 to 12 carbon atoms which may have an ether group (ether bond), an ester group (ester bond), a nitrile group, or a silyl group. The number of carbon atoms of such an alkyl group is more preferably from 1 to 6, more preferably from 1 to 4, from the viewpoint of reducing the viscosity of the ionic liquid and improving the heat resistance (high-temperature oxidation stability). Particularly preferred.
Examples of the cation having the structure represented by the general formula (3) include 1-butyl-1-methylpyrrolidinium, 1-pentyl-1methylpyrrolidinium, 1-hexyl-1-methylpyrrolidinium, -Heptyl-1 methylpyrrolidinium, 1-octyl-1 methylpyrrolidinium, 1-nonyl-1 methylpyrrolidinium, 1-decyl-1 methylpyrrolidinium, 1-undecyl-1 methylpyrrolidinium, -Dodecyl-1 methylpyrrolidinium, 1- (2-methoxyethyl) -1-methylpyrrolidinium, 1- (2-methoxy-2-oxoethyl) -1-methylpyrrolidinium, 1-cyanomethyl-1- Methylpyrrolidinium, 1-trimethylsilylmethyl-1-methylpyrrolidinium, 1-butyl-1-methylpiperidinium, 1-pentyl-1- Methylpiperidinium, 1-hexyl-1-methylpiperidinium, 1-heptyl-1-methylpiperidinium, 1-octyl-1-methylpiperidinium, 1-nonyl-1-methylpiperidinium, 1 -Decyl-1-methylpiperidinium, 1-undecyl-1-methylpiperidinium, 1-dodecyl-1-methylpiperidinium, 1- (2-methoxyethyl) -1-methylpiperidinium, 1- (2-methoxy-2-oxoethyl) -1-methylpiperidinium, 1-cyanomethyl-1-methylpiperidinium, 1-trimethylsilylmethyl-1-methylpiperidinium, 1-butyl-1-methylmorpholinium 1-pentyl-1-methylmorpholinium, 1-hexyl-1-methylmorpholinium, 1-heptyl-1-methylmorpholinium 1-octyl-1-methylmorpholinium, 1-nonyl-1-methylmorpholinium, 1-decyl-1-methylmorpholinium, 1-undecyl-1-methylmorpholinium, 1-dodecyl- 1-methylmorpholinium, 1- (2-methoxyethyl) -1-methylmorpholinium, 1- (2-methoxy-2-oxoethyl) -1-methylmorpholinium, 1-cyanomethyl-1-methylmol Examples include folinium and 1-trimethylsilylmethyl-1-methylmorpholinium. Among these, 1-butyl-1-methylpyrrolidinium, 1-pentyl-1methylpyrrolidinium, 1-hexyl- from the viewpoint of lowering the viscosity of the ionic liquid and improving heat resistance (high-temperature oxidation stability). 1-methylpyrrolidinium, 1- (2-methoxyethyl) -1-methylpyrrolidinium, 1-butyl-1-methylpiperidinium, 1- (2-methoxyethyl) -1-methylpiperidinium, 1- (2-methoxyethyl) -1-methylmorpholinium is preferred, 1-butyl-1-methylpyrrolidinium, 1- (2-methoxyethyl) -1-methylpyrrolidinium, 1- (2- Methoxyethyl) -1-methylpiperidinium is particularly preferred.

The molecular weight of the ionic liquid is preferably 410 or more and 570 or less, more preferably 410 or more and 470 or less, and particularly preferably 420 or more and 440 or less. When the molecular weight is within the above range, the charge density and the alkyl chain of the cation are in an appropriate range, and the viscosity of the ionic liquid can be reduced and the heat resistance (high-temperature oxidation stability) can be improved.
The kinematic viscosity at 40 ° C. of ionic liquid, evaporation loss, and from the viewpoint of suppressing the power loss due to viscosity resistance is preferably not more than ^{1 mm} 2 / s or more ^{100mm 2 / s, 10mm 2 /} s or more 70 mm ² / It is more preferably s or less, particularly preferably 20 mm ² / s or more and 40 mm ² / s or less.
The pour point of the ionic liquid is preferably 0 ° C. or less, more preferably −10 ° C. or less, and particularly preferably −20 ° C. or less, from the viewpoint of suppressing an increase in viscous resistance at low temperatures. preferable.

The acid value of the ionic liquid is preferably 1 mgKOH / g or less, more preferably 0.5 mgKOH / g or less, and 0.3 mgKOH / g or less from the viewpoint of preventing corrosion of the lubricated oil material. It is particularly preferred.
The flash point of the ionic liquid is preferably 200 ° C. or higher, more preferably 250 ° C. or higher, and particularly preferably 300 ° C. or higher from the viewpoint of reducing the evaporation amount of the base oil.
The viscosity index of the ionic liquid is preferably 80 or more, more preferably 100 or more, and particularly preferably 120 or more, from the viewpoint of preventing a viscosity change with respect to temperature from becoming too large.

In the ionic liquid preferably has ion concentration measured at 20 ° C. is 1 mol / dm ³ or higher, more preferably 1.5 mol / dm ³ or higher, and particularly preferably 2 mol / dm ³ or more . Here, the ion concentration is a value calculated by [density (g / cm ³ ) / molecular weight Mw (g / mol)] × 1000 in the ionic liquid. When the ion concentration of the ionic liquid is less than 1 mol / dm ³ , the low evaporation property and heat resistance, which are the characteristics of the ionic liquid, are lowered, which is not preferable.

  The lubricating base oil of the present invention contains one or more of the ionic liquids described above, but the lubricating base oil of the present invention contains other components (for example, ethyl acetate) other than the ionic liquid. May be. However, in order to exert the effect as the lubricating base oil of the present invention, the ratio of the ionic liquid in the lubricating base oil is preferably 50% by mass or more, and more preferably 70% by mass or more. Preferably, it is still more preferably 90% by mass or more, and particularly preferably 100% by mass.

The lubricating base oil of the present invention can be used in various applications as a lubricating oil composition by blending predetermined additives. Examples of the additive include an antioxidant, an oily agent, an extreme pressure agent, a cleaning dispersant, a viscosity index improver, a rust inhibitor, a metal deactivator, and an antifoaming agent. These can be used individually by 1 type or in combination of 2 or more types. Depending on the application, a lubricant base oil may be used as it is as a lubricant without adding an additive.
As the antioxidant, amine-based antioxidants, phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants that are used in conventional hydrocarbon-based lubricating oils can be used. These antioxidants can be used singly or in combination of two or more. Examples of the amine antioxidant include monoalkyl diphenylamine compounds such as monooctyl diphenylamine and monononyl diphenylamine, 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, 4 , 4′-diheptyldiphenylamine, 4,4′-dioctyldiphenylamine, dialkyldiphenylamine compounds such as 4,4′-dinonyldiphenylamine, polyalkyl such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine Diphenylamine compounds, α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, pentylphenyl-α-na Ethylamine, hexyl phenyl -α- naphthylamine, heptylphenyl -α- naphthylamine, octylphenyl -α- naphthylamine, and naphthylamine-based compounds such as nonylphenyl -α- naphthylamine.

Examples of the phenolic antioxidant include monophenolic compounds such as 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol, 4,4 ′ Examples include diphenolic compounds such as -methylenebis (2,6-di-tert-butylphenol) and 2,2'-methylenebis (4-ethyl-6-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 Examples thereof include thioterpene compounds such as a reaction product with pinene, and dialkylthiodipropionates such as dilauryl thiodipropionate and distearyl thiodipropionate.
Examples of phosphorus antioxidants include triphenyl phosphite, diethyl [3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate, and the like.
The blending amount of these antioxidants is usually 0.01% by mass or more and 10% by mass or less, preferably 0.03% by mass or more and 5% by mass or less, based on the total amount of the lubricating oil.

  Examples of the oily agent include fatty alcohols, fatty acid compounds such as fatty acids and fatty acid metal salts, ester compounds such as polyol esters, sorbitan esters, and glycerides, and amine compounds such as aliphatic amines. The blending amount of these oil-based agents is usually 0.1% by mass or more and 30% by mass or less, and preferably 0.5% by mass or more and 10% by mass or less based on the total amount of the lubricating oil from the viewpoint of the blending effect.

Examples of the extreme pressure agent include a sulfur-based extreme pressure agent, a phosphorus-based extreme pressure agent, an extreme pressure agent containing sulfur and a metal, and an extreme pressure agent containing phosphorus and a metal. These extreme pressure agents can be used singly or in combination of two or more. Any extreme pressure agent may be used as long as it contains at least one of a sulfur atom and a phosphorus atom in the molecule and can exhibit load resistance and wear resistance. Examples of extreme pressure agents containing sulfur in the molecule include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiadiazole compounds, alkylthiocarbamoyl compounds, triazine compounds, thioterpene compounds, dialkylthiodipropionate compounds, etc. Can be mentioned.
As extreme pressure agents containing sulfur, phosphorus and metals, zinc dialkylthiocarbamate (Zn-DTC), molybdenum dialkylthiocarbamate (Mo-DTC), lead dialkylthiocarbamate, tin dialkylthiocarbamate, dialkyldithiophosphate Examples include zinc (Zn-DTP), molybdenum dialkyldithiophosphate (Mo-DTP), sodium sulfonate, calcium sulfonate, and the like. Typical examples of extreme pressure agents containing phosphorus in the molecule are phosphate esters such as tricresyl phosphate and amine salts thereof. The blending amount of these extreme pressure agents is usually 0.01% by mass or more and 30% by mass or less, more preferably 0.01% by mass or more and 10% by mass or more based on the total amount of the composition from the viewpoint of blending effect and economy. It is as follows.

Examples of the cleaning dispersant include metal sulfonate, metal salicylate, metal finate, and succinimide. The blending amount of these detergent dispersants is usually 0.1% by mass or more and 30% by mass or less, and preferably 0.5% by mass or more and 10% by mass or less based on 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 hydrogenated copolymer, etc.). The blending amount of these viscosity index improvers is usually 0.5% by mass or more and 35% by mass or less, and preferably 1% by mass or more and 15% by mass or less based on the total amount of the lubricating oil from the viewpoint of the blending effect.
Examples of the rust inhibitor include metal sulfonates, succinic acid esters, alkylamines and alkanolamines such as monoisopropanolamine. The blending amount of these rust preventives is usually 0.01% by mass or more and 10% by mass or less, and preferably 0.05% by mass or more and 5% by mass or less based on the total amount of the lubricating oil from the viewpoint of the blending effect.
Examples of the metal deactivator include benzotriazole and thiadiazole. The preferred compounding amount of these metal deactivators is usually 0.01% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 1% by mass or less, based on the total amount of the lubricating oil, from the viewpoint of the blending effect. It is.
Examples of the antifoaming agent include methyl silicone oil, fluorosilicone oil, and polyacrylate. The blending amount of these antifoaming agents is usually 0.0005% by mass or more and 0.01% by mass or less based on the total amount of the lubricating oil from the viewpoint of the blending effect.

  In the lubricating oil composition of the present invention, from the viewpoint of preventing a decrease in viscosity and corrosion, the moisture content is preferably 3000 ppm by mass or less, more preferably 500 ppm by mass or less, and particularly preferably, on the basis of the composition. It is 100 mass ppm or less.

The lubricating base oil of the present invention has very low corrosiveness to metals, and even if it has a low viscosity, its vapor pressure is low and there is no risk of ignition. The lubricating oil composition can be applied to various fields.
For example, an internal combustion engine such as an engine, a fluid coupling, an automatic transmission (AT) or a torque transmission device represented by a continuously variable transmission (CVT), a bearing (slide bearing, rolling bearing, oil impregnation or (Impregnated bearings, fluid bearings), compressors such as compressors, chains, gears, hydraulic devices, vacuum pumps, clock parts, hard disks, aerospace equipment such as aircraft and artificial satellites, sealing devices, and motor equipment. The present invention is also applicable to rolling devices such as ball screws and rolling guide surfaces, rotation transmission devices with built-in clutches, power steering devices, reciprocating compressors, and turbochargers.

The present invention further provides a metal working oil (cutting, pressing, forging, etc.), a release agent, a heat treatment agent, a heat medium, a cooling agent, a rust preventive agent, a buffering agent such as a damper, or current-carrying lubrication that requires electrical conductivity. It is also suitable as an agent.
The lubricating base oil of the present invention is also applicable as a base oil for grease. Grease thickeners include metal soaps such as lithium salts and calcium salts and non-metals. As the non-metallic thickener, for example, bentonite, silica, fluororesin powder and the like are suitable. The lubricating base oil of the present invention is also applicable as a base oil for gel substances other than grease.

Furthermore, the present invention is suitable for machine materials made of iron, copper, aluminum, zinc, and the like. In particular, stainless steel (martensitic, ferritic, austenitic) known as corrosion resistant materials, ceramic materials (silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), alumina (Al ₂ O ₃ ), aluminum nitride ( When using AlN), boron carbide (B ₄ C), titanium boride (TiB ₂ ), boron nitride (BN), titanium carbide (TiC), titanium nitride (TiN), zirconia (ZrO ₂ ), etc. It is suitable when using a material whose surface has been subjected to various coating treatments such as DLC (diamond-like carbon) treatment.

Further, the present invention is suitably used for an apparatus that performs physical vapor deposition (PVD) and an apparatus that performs chemical vapor deposition (CVD). Here, examples of the physical vapor deposition include vacuum vapor deposition, sputtering, ion plating, and ion implantation using various ion guns. Examples of vacuum deposition include electron beam deposition, ion-assisted electron beam deposition, arc deposition, and the like in addition to general resistance heating deposition. These physical vapor depositions may be used in combination. Examples of CVD include thermal CVD, plasma CVD, photo CVD, epitaxial CVD, and atomic layer CVD. These chemical vapor depositions may be used in combination, or may be used in combination with physical vapor deposition.
A physical vapor deposition apparatus and a chemical vapor deposition apparatus using the lubricating base oil (lubricating oil composition) of the present invention are suitable for manufacturing display elements, for example.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples. Various characteristics (kinematic viscosity, viscosity index, pour point, 5% mass loss temperature, friction characteristics, metal corrosivity) of the lubricating base oil and lubricating oil composition were evaluated or measured according to the following methods.
(1) Kinematic viscosity It measured based on the "petroleum product kinematic viscosity test method" prescribed | regulated to JISK2283.
(2) Viscosity index It measured based on the "petroleum product kinematic viscosity test method" prescribed | regulated to JISK2283.
(3) Pour point Measured according to the method described in JIS K2269.
(4) 5% mass reduction temperature Using a differential thermal analyzer, the temperature was increased at a rate of 10 ° C./min, and the temperature reduced by 5% from the initial mass was measured. It can be said that the higher the 5% mass loss temperature, the better the evaporation resistance and heat resistance.
(5) Friction characteristics (friction coefficient and wear width)
Using a ball-on-disk type reciprocating friction tester (Bauden-Leven type), the friction coefficient and the wear width were measured under the conditions of a load of 20 N, a temperature of 80 ° C., a sliding speed of 30 mm ² / s, and a stroke of 15 mm. The material of the ball is SUJ2, the diameter of the ball is 10 mm, and the material of the disk is SUJ2. It can be said that the smaller the friction coefficient and the wear width, the better the lubricity and wear resistance.
(6) Metal corrosivity In 8 mL of ionic liquid, iron-based (iron content is 99% by mass or more) and copper-based (copper content is 93% by mass to 98% by mass, tin content is 2% by mass to 7% by mass) Each of the other sintered bearings having a metal content of 1% by mass or less) was simultaneously immersed and allowed to stand at 140 ° C. for 240 hours, and then the appearance of the ionic liquid was observed. The bearing has an outer diameter of 12 mm and a thickness of 4 mm. And metal corrosivity was evaluated based on the criteria shown below.
○: No metal elution and no corrosion.
Δ: Slightly brown or black eluate is observed (slightly corroded).
X: There is a brownish brown or black eluate (corrosion).

[Ionic liquid]
The following ionic liquids were synthesized or prepared as follows.
(1) Ionic liquid 1: 1-butyl-1-methylpyrrolidinium bis (trifluoromethanesulfonyl) amide 1-methylpyrrolidine (50 g, 0.585 mol) and 2-propanol (70 mL) were added to a 1 L flask under a nitrogen atmosphere. added. 1-Bromobutane (96.5 g, 0.705 mol) was added dropwise thereto, and then the mixture was heated to 40 ° C. and reacted for 6 hours. After completion of the reaction, recrystallization was performed with ethyl acetate, and the crystals obtained by filtration were washed several times with ethyl acetate. Then, 1-butyl-1-methylpyrrolidinium bromide (halogen) was obtained by drying at 40 ° C. for several hours while reducing the pressure with a vacuum pump (113 g, 0.510 mol).
Next, the halogen body (113 g, 0.510 mol) and pure water (110 mL) are added to a 1 L flask, and lithium bis (trifluoromethanesulfonyl) imide (151 g, 0.525 mol) is added to pure water (150 mL). The dissolved aqueous solution was added dropwise. The reaction mixture was stirred at room temperature for about 1 hour, transferred to a 1 L separatory funnel, extracted by adding methylene chloride (230 mL), and the collected methylene chloride solution was washed several times with pure water. After washing, an aqueous layer (range from 1 mL to 2 mL) was collected and reacted with 0.5 M aqueous silver nitrate solution (1 mL) to confirm the presence or absence of precipitation (if a white precipitate was observed, bromide ions were completely removed. Repeat cleaning until it is no longer visible.) After completion of water washing, the mixture was concentrated with a rotary evaporator, a small amount of activated carbon was added, and the mixture was stirred at room temperature for 1 day. The mixture was passed through a column of neutral alumina and heated and stirred (60 ° C., 4 hours) while reducing the pressure with a vacuum pump to obtain the target compound (212 g, 0.50 mol). The chemical formula of this compound is shown below.

(2) Ionic liquid 2: 1-hexyl-1-methylpyrrolidinium bis (trifluoromethanesulfonyl) amide In the synthesis of ionic liquid 1, instead of using 1-bromobutane, 1-bromohexane (116 g, 0.705 mol) 1-hexyl-1-methylpyrrolidinium bromide (117 g, 0.468 mol) was obtained in the same manner except that was used. The target compound (202 g, 0.449 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(3) Ionic liquid 3: 1- (2-methoxyethyl) -1-methylpyrrolidinium bis (trifluoromethanesulfonyl) amide In the synthesis of ionic liquid 1, instead of using 1-bromobutane, 2-iodoethyl methyl ether 1- (2-methoxyethyl) -1-methylpyrrolidinium iodide (146 g, 0.538 mol) was obtained in the same manner except that (131 g, 0.705 mol) was used. The target compound (212 g, 0.500 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(4) Ionic liquid 4: 1-butyl-1-methylpiperidinium bis (trifluoromethanesulfonyl) amide In the synthesis of ionic liquid 1, instead of using 1-methylpyrrolidine, 1-methylpiperidine (58 g, 0.585 mol) ) To give 1-butyl-1-methylpiperidinium bromide (137 g, 0.579 mol) except that the reaction was performed at 80 ° C. The target compound (250 g, 0.573 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(5) Ionic liquid 5: 1- (2-methoxyethyl) -1-methylpiperidinium bis (trifluoromethanesulfonyl) amide In the synthesis of ionic liquid 3, instead of using 1-methylpyrrolidine, 1-methylpiperidine ( 1- (2-methoxyethyl) -1-methylpiperidinium iodide (161 g, 0.563 mol) except that the reaction was performed at 60 ° C. It was. The target compound (241 g, 0.549 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(6) Ionic liquid 6: 1- (2-methoxyethyl) -1-methylmorpholinium bis (trifluoromethanesulfonyl) amide In the synthesis of ionic liquid 3, instead of using 1-methylpiperidine, 1-methylmorpholine ( 1- (2-methoxyethyl) -1-methylmorpholinium iodide (145 g, 0.505 mol) except that the reaction was performed at 80 ° C. using 59 g, 0.585 mol). It was. The target compound (202 g, 0.460 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used in place of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(7) Ionic liquid 7: 1-butylpyridinium bis (trifluoromethanesulfonyl) amide In the synthesis of ionic liquid 1, instead of using 1-methylpyrrolidine, pyridine (46 g, 0.585 mol) was used and 2-propanol was used. 1-Butylpyridinium bromide (125 g, 0.579 mol) was obtained in the same manner except that it was changed to acetonitrile (200 mL) and reacted at 80 ° C. The target compound (234 g, 0.562 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(8) Ionic liquid 8: N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) amide This ionic liquid 8 was purchased from Kanto Chemical Co., Inc. The chemical formula of this compound is shown below.

(9) Ionic liquid 9: N, N, N-trimethyl-N-pentylammonium bis (trifluoromethanesulfonyl) amide Trimethylamine 3.2M methanol solution (183 mL, 0.585 mol), 1-iodo in a 1 L flask under nitrogen atmosphere Pentane (89 g, 0.449 mol) was added and allowed to react for several hours at room temperature. After completion of the reaction, the solvent was removed under reduced pressure, and the residue was washed several times with ethyl acetate and acetonitrile. Then, N, N, N-trimethyl-N-pentylammonium iodide was obtained by drying for several hours while reducing the pressure with a vacuum pump (89 g, 0.346 mol). The target compound (138 g, 0.336 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(10) Ionic liquid 10: Triethyl (octyl) phosphonium bis (trifluoromethanesulfonyl) amide In a 1 L flask under nitrogen atmosphere, a 20% toluene solution of triethylphosphine (346 g, 0.585 mol), 1-iodooctane (211 g, 0.878 mol) ) And reacted at 60 ° C. for several hours. After completion of the reaction, the reaction mixture was washed several times with ethyl acetate and dried at 40 ° C. for several hours while reducing the pressure with a vacuum pump to obtain triethyl (octyl) phosphonium iodide (176 g, 0.491 mol). The target compound (241 g, 0.471 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(11) Ionic liquid 11: 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) amide 1-methylimidazole (173 g, 2.100 mol), 1-chlorobutane (234 g, 2. 528 mol) was added and reacted at 90 ° C. for several hours. After completion of the reaction, recrystallization was performed with ethyl acetate and acetonitrile, and the crystals obtained by filtration were dried at 40 ° C. for several hours while reducing the pressure with a vacuum pump, whereby 1-butyl-1-methylimidazolium chloride (352 g) was obtained. 2.016 mol). The target compound (837 g, 1.996 mol) was obtained in the same manner as in the synthesis of ionic liquid 1, except that this quaternary salt was used instead of 1-butyl-1-methylpyrrolidinium bromide. The chemical formula of this compound is shown below.

(12) Ionic liquid 12: 1-butyl-1-methylpyrrolidinium trifluorotris (pentafluoroethyl) phosphate This ionic liquid 12 was purchased from Merck & Co., Inc. The chemical formula of this compound is shown below.

(13) Ionic liquid 13: 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate 1-butylpyrrolidine (34 g, 0.267 mol) and toluene (230 mL) were added to a 1 L flask under a nitrogen atmosphere. A mixed solution of methyl triflate (43 g, 0.262 mol) and toluene (100 mL) was added dropwise thereto at 0 ° C., and reacted at the same temperature for several hours. After completion of the reaction, it was washed several times with toluene and treated with activated carbon. This mixture was passed through a column of neutral alumina and heated and stirred (60 ° C., 4 hours) while reducing the pressure with a vacuum pump to obtain the desired product (68 g, 0.233 mol). The chemical formula of this compound is shown below.

[Example 1 to Example 8 and Comparative Example 1 to Comparative Example 7]
Using the above ionic liquid and the additives shown below, a lubricating base oil or lubricating oil composition was prepared according to the formulation shown in Tables 1 and 2, and the above properties (kinematic viscosity, viscosity index, pour point, 5% mass loss temperature, friction characteristics, metal corrosivity) were evaluated or measured. The results are shown in Tables 1 and 2 together with the formulation.
Extreme pressure agent: tricresyl phosphate metal deactivator: benzotriazole

  As is clear from the evaluation results shown in Tables 1 and 2, the lubricating base oils or lubricating oil compositions obtained in Examples 1 to 8 are less likely to corrode metals at high temperatures and have low temperature fluidity. It was confirmed that the heat resistance and lubricity were also good. On the other hand, when an ionic liquid that does not satisfy the condition that the cation is a cyclic quaternary ammonium ion having two different side chains and the anion is a conjugated amide ion (from Comparative Example 1 to Comparative Example 7) is used. Although excellent in heat resistance and lubricity, it was confirmed that the metal corrosion resistance at high temperature and the low temperature fluidity are not compatible, and it is not suitable as a lubricating base oil.

Claims (7)

The following general formula (1):
Z ⁺ A ⁻ (1)
(Z ⁺ means a cation and A ⁻ means an anion.)
A lubricating base oil containing one or more ionic liquids composed of a compound represented by: wherein Z ⁺ is a cyclic quaternary ammonium ion having two different side chains, A ⁻ is a conjugated amide ion,
A ⁻ in the ionic liquid represented by the general formula (1) is represented by the following general formula (2):

(In Formula (2), n is an integer from 1 to 4, m is an integer from 1 to 4, and they may be the same or different.)
Is selected from anions having a structure represented by:
Z ⁺ in the ionic liquid represented by the general formula (1) is the following general formula (3):

(In formula (3), n is 2 , X is methylene or oxygen, and R ₁ and R ₂ are groups selected from a methyl group, a butyl group, and a 2-methoxyethyl group). A lubricating base oil characterized in that it is selected from cations having the following structure: In the lubricating base oil according to claim 1,
The lubricating oil base oil, wherein the ionic liquid is any one of compounds represented by the following chemical formulas.

In the lubricating base oil according to claim 1 or 2,
A lubricating base oil having a molecular weight of 410 or more and 570 or less of the ionic liquid. In the lubricating base oil according to any one of claims 1 to 3,
A lubricating base oil, wherein the ionic liquid has a kinematic viscosity at 40 ° C. of 1 mm ² / s to 100 mm ² / s. In the lubricating base oil according to any one of claims 1 to 4,
A lubricating base oil, wherein the pour point of the ionic liquid is 0 ° C or lower.   The lubricant base oil according to any one of claims 1 to 5, added to an antioxidant, an oily agent, an extreme pressure agent, a cleaning dispersant, a viscosity index improver, a rust inhibitor, and a metal deactivator. A lubricating oil composition comprising at least one of an agent and an antifoaming agent. The lubricating oil composition according to claim 6, wherein
A lubricating oil composition used for lubricating oil-impregnated bearings, fluid bearings, vacuum equipment, and semiconductor manufacturing equipment.