JP5748485B2 - Synthetic lubricant - Google Patents

Description

  The present invention relates to a synthetic lubricant mainly composed of an ionic liquid, and more particularly to a synthetic lubricant mainly composed of an ionic liquid that is excellent in friction adjustment performance and rust prevention performance.

  Conventionally, as a lubricating oil used for mechanical devices, power transmission devices, metalworking oils, greases, etc., base oils of the type closest to the target physical properties among base oils such as poly α olefins, diesters, polyol esters, silicones, etc. are used. A combination of these is used as necessary, and further, antioxidants, viscosity index improvers, pour point depressants, friction modifiers, extreme pressure agents, antifoaming agents, rust inhibitors In addition, a plurality of lubricant additives such as corrosion inhibitors were added and used as a lubricant suitable for the usage environment.

  In recent years, with higher performance and higher efficiency of equipment, there has been a demand for lubricants that can exhibit higher oxidation resistance, higher evaporation resistance, and stable lubrication performance over a long period of time. As a means to solve this problem, it has been reported that an ionic liquid (room temperature molten salt) composed of a combination of a specific organic cation and an inorganic anion can be used as a lubricant, and the ionic liquid has a very low vapor pressure and a wide temperature range. In addition to being excellent in stability and flame retardancy, it is known as a new material for lubricating oil because of its high viscosity index (see Non-Patent Document 1).

Regarding the lubricating oils using these ionic liquids, among the performance required for lubricating oils, the oxidation resistance, viscosity index, and pour point could be adjusted and improved by improving the molecular design of the ionic liquid itself. Regarding performances other than those described above, it was difficult to exert the performance by improving the ionic liquid itself, and therefore it was considered to use various existing additives.
However, many of these existing additives do not dissolve in ionic liquids, and there are currently no lubricating oil additives that can actually be used in synthetic lubricants based on ionic liquids. This has been an obstacle to the practical use of ionic liquid as a lubricating oil.

R.A.Reich et al., Journal of the Society of Tribologists and Lubrication Engineers, July 2003, p.16-21

  Therefore, in the present invention, under such a background, it is possible to impart friction adjustment performance and rust prevention performance, which are indispensable for the practical use of synthetic lubricants composed of ionic liquids. Synthesizing by adding a lubricating oil additive that dissolves or disperses even when added and does not impair the performance as a base oil of a ionic liquid, especially a fluorinated ionic liquid that has low viscosity and is useful for lubricant applications The purpose is to provide a lubricant.

However, as a result of intensive research in view of such circumstances, the present inventors have found that an imidazolium phosphate ester salt as an additive is added to a synthetic lubricant mainly composed of a fluorinated ionic liquid whose cation portion is an imidazolium cation. By compounding, it discovered that the synthetic lubricant which was excellent in friction adjustment performance and rust prevention performance was obtained, and came to complete this invention.

That is, the gist of the present invention is a synthetic lubricant mainly composed of a fluorine atom-containing ionic liquid (A) whose cation portion is an imidazolium cation, and contains an imidazolium phosphate ester salt (B). It relates to a characteristic synthetic lubricant.

According to the present invention, by adding an imidazolium phosphate ester salt to an ionic liquid lubricant containing a fluorine atom-containing ionic liquid whose cation portion is an imidazolium cation as a main component, low volatility, wide temperature stability, While maintaining the characteristics of the fluorine atom-containing ionic liquid such as a high viscosity index, the friction coefficient, the wear amount of the material in contact with the lubricant, and the rusting of the material can be reduced.
Although the mechanism of the development of such effects has not been fully elucidated, imidazolium phosphate ester salts have a higher affinity with the metal surface compared to the main component fluorine atom-containing ionic liquid. It is presumed that the friction characteristics are improved efficiently by being able to be stably adsorbed (stayed) on the friction surface.
Further, since the addition amount of the imidazolium phosphate ester salt is small and effective, it has little influence on the physical properties of the main component ionic liquid.

The present invention is described in detail below.
The synthetic lubricant of the present invention comprises a fluorine atom-containing ionic liquid (A) whose cation portion is an imidazolium cation (hereinafter sometimes abbreviated as “ionic liquid (A)”) as a main component, and further imidazolium phosphorus. The acid ester salt (B) is contained.
In addition, the ionic liquid in this invention shows the ionic substance which is in a molten state at normal temperature (25 degreeC), and consists of a cation part and an anion part.

  The ionic liquid (A) contains a fluorine atom, but it is sufficient that the fluorine atom is contained in at least one of the cation part or the anion part, and it is particularly preferred that it is contained only in the anion part.

As the cation part of the ionic liquid (A) , an imidazolium cation is used, which is preferable in that it has a low melting point and easily becomes liquid.

  Although it does not specifically limit as said imidazolium cation, For example, what has the structure of following General formula (3) can be mention | raise | lifted.

Wherein R1 to R5 are each independently a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, an alkenyl group, an alkynyl group, an alkoxyl group, an acyl group, an amide group, a cyano group. , A nitro group, an amino group, and an alkyl group, an alkenyl group, an alkynyl group, an alkoxyl group, and an acyl group may contain a heteroatom selected from N, S, and O. (It may contain a heavy bond or a triple bond.)

  When the substituents R1 to R5 are an alkyl group, an alkenyl group, an alkynyl group, an alkoxyl group, or an acyl group, the number of carbon atoms is preferably 1 to 16, more preferably 1 to 12, and more preferably 1 to 6. More preferably it is. These substituents may be either a straight chain or a branched structure, but if the number of carbons is too large, there is a tendency for the viscosity to increase because of the intermolecular interaction of the side chain.

  The alkyl group, alkenyl group, alkynyl group, alkoxyl group and acyl group may contain a heteroatom selected from N, S and O, and the number of heteroatoms contained is not particularly limited. . Further, it may contain a conjugated or independent double bond or triple bond, and the number of these unsaturated bonds is not particularly limited.

  Specific examples of such an alkyl group include, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secondary butyl group, a tertiary butyl group, a pentyl group, and a hexyl group. , Cyclopropyl group, cyclopentyl group, cyclohexyl group and the like. Examples of the alkenyl group include vinyl group, allyl group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, and 2-hexenyl group. Furthermore, examples of the alkynyl group include ethynyl group, 1-propynyl group, 2-propynyl group and the like, and examples of the alkoxyl group include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, t- Examples of the acyl group such as butoxy group include acetyl group, propionyl group, butyryl group, and benzoyl group. Examples of amino group include N, N-dimethylamino group and N, N-diethylamino group. It is done. In view of industrial utility, an alkoxyl group, an acyl group, an amide group, a cyano group, a nitro group, an amino group, and the like are preferable from the viewpoint that they can be easily degraded by an enzyme and biodegradability can be improved.

  Specific examples of the imidazolium cation represented by the above formula (3) include 1,3-dimethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-methyl-3-propylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-methyl-3-pentylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-methyl-3- Octylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-ethyl-3-propylimidazolium cation, 1-butyl-3-ethylimidazolium cation, etc. Dialkylimidazolium cation; 3- Til-1,2-dimethyl-imidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1,2-dimethyl-3-hexylimidazolium cation 1,3-dimethyl-3-octylimidazolium cation, 1-ethyl-3,4-dimethylimidazolium cation, 1-isopropyl-2,3-dimethylimidazolium cation and the like trialkylimidazolium cations Can do.

  Among these imidazolium cations, 1,3-disubstituted imidazolium cations and 1,2,3-trisubstituted imidazolium cations are preferably used from the viewpoint of easy synthesis, and in particular, 1,3-disubstituted imidazolium cations. A lithium cation is preferably used. The substituents in these derivatives may be the same or different and may have multiple bonds or branches.

  The substituent is the same as the substituent in the general formula (3), and is appropriately selected from these.

Regarding the anion part of the ionic liquid (A), for example, Cl ⁻ , Br ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) n ⁻ , (CN) ₂ N ⁻ , SCN ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF _{3 SO 2) (CF 3 CO)} N - it is possible to use an anion commonly used in ionic liquids and the like.
Among these, anions having a halogen atom are preferable, and fluorine-containing anions are particularly preferable. In particular, the generated ionic liquid has low solubility in water and is suitable for the purpose of use as a lubricant. It is preferable to use a fluorine-containing imide anion represented by the formula (1).

[Chemical 2]
(C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (1)
(Where n is an integer from 0 to 15)

  Regarding the fluorine-containing imide anion represented by the general formula (1), the melting point and viscosity of the ionic liquid to be generated vary depending on the number of carbons n in the general formula (1). It is necessary to select a hydrocarbon group having a long chain length. For the purpose of developing a lubricant in a low temperature region, it is preferable to use a hydrocarbon group having a small value of n. Specifically, it is preferable to use a bis (fluorosulfonyl) imide anion or a bis (trifluoromethanesulfonyl) imide anion. As said n, it is 0-15 normally, Preferably it is 0-8, Most preferably, it is 0-4.

  The method for producing the ionic liquid (A) is not particularly limited, and a known method such as an anion exchange method or an acid ester method can be applied. For example, it can be obtained by an anion exchange reaction using a halogenated salt of an organic cation to be used and an alkali metal salt of a perfluoroalkylsulfonate anion. The halogen of the halogenated salt includes chlorine or bromine. Examples of the alkali metal of the alkali metal salt include sodium and potassium.

  The imidazolium phosphate ester salt (B) (excluding (A)) in the present invention may be a salt composed of an imidazolium cation and a phosphate ester anion, and when used as a lubricant, Affinity with the surface is increased, and it becomes possible to stably adsorb (stay) on the friction surface of the metal surface. It is preferable that it does not contain.

  As said imidazolium cation, what has the structure of following General formula (4) can be mention | raise | lifted, for example.

Wherein R1 to R5 are each independently a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, an alkenyl group, an alkynyl group, an alkoxyl group, an acyl group, an amide group, a cyano group. , A nitro group, an amino group, and an alkyl group, an alkenyl group, an alkynyl group, an alkoxyl group, and an acyl group may contain a heteroatom selected from N, S, and O. (It may contain a heavy bond or a triple bond.)

  When the substituents R1 to R5 are an alkyl group, an alkenyl group, an alkynyl group, an alkoxyl group, or an acyl group, the number of carbon atoms is preferably 1 to 16, more preferably 1 to 12, and more preferably 1 to 6. More preferably it is. These substituents may be either a straight chain or a branched structure, but if the number of carbons is too large, there is a tendency for the viscosity to increase because of the intermolecular interaction of the side chain.

  The alkyl group, alkenyl group, alkynyl group, alkoxyl group and acyl group may contain a heteroatom selected from N, S and O, and the number of heteroatoms contained is not particularly limited. . Further, it may contain a conjugated or independent double bond or triple bond, and the number of these unsaturated bonds is not particularly limited.

  Specific examples of such an alkyl group include, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secondary butyl group, a tertiary butyl group, a pentyl group, and a hexyl group. , Cyclopropyl group, cyclopentyl group, cyclohexyl group and the like. Examples of the alkenyl group include vinyl group, allyl group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, and 2-hexenyl group. Furthermore, examples of the alkynyl group include ethynyl group, 1-propynyl group, 2-propynyl group and the like, and examples of the alkoxyl group include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, t- Examples of the acyl group such as butoxy group include acetyl group, propionyl group, butyryl group, and benzoyl group. Examples of amino group include N, N-dimethylamino group and N, N-diethylamino group. It is done. In view of industrial utility, an alkoxyl group, an acyl group, an amide group, a cyano group, a nitro group, an amino group, and the like are preferable from the viewpoint that they can be easily degraded by an enzyme and biodegradability can be improved.

  Specific examples of the imidazolium cation represented by the above formula (4) include 1,3-dimethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-methyl-3-propylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-methyl-3-pentylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-methyl-3- Octylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-hexadecyl-3-methylimidazolium cation, 1-ethyl-3-propylimidazolium cation, 1 -Butyl-3-ethylimidazolium Dialkylimidazolium cations such as cations; 3-ethyl-1,2-dimethyl-imidazolium cations, 1,2-dimethyl-3-propylimidazolium cations, 1-butyl-2,3-dimethylimidazolium cations, 1, 2-dimethyl-3-hexylimidazolium cation, 1,2-dimethyl-3-octylimidazolium cation, 1-ethyl-3,4-dimethylimidazolium cation, 1-isopropyl-2,3-dimethylimidazolium cation, etc. And trialkylimidazolium cations.

  Among these imidazolium cations, 1,3-disubstituted imidazolium cations and 1,2,3-trisubstituted imidazolium cations are preferably used from the viewpoint of easy synthesis, and in particular, 1,3-disubstituted imidazolium cations. A lithium cation is preferably used. The substituents in these derivatives may be the same or different and may have multiple bonds or branches.

  The phosphate ester anion may be either a phosphate ester anion having a monoester structure or a phosphate ester anion having a diester structure. For ease of synthesis, the phosphate ester anion has a diester structure. Preferably there is.

  As the phosphate ester anion having such a diester structure, those represented by the following general formula (5) are preferable.

(In the formula, R 1 and R 2 are each independently an alkyl group having 1 to 8 carbon atoms.)

  Carbon number of the alkyl group of R1 and R2 is usually 1 to 8, preferably 1 to 4. R1 and R2 may be the same or different, but are preferably the same because they are easily synthesized.

  Examples of the phosphate ester anion represented by the general formula (5) include dimethyl phosphate anion, diethyl phosphate anion, dipropyl phosphate anion, dibutyl phosphate anion, dipentyl phosphate anion, dihexyl phosphate anion, diheptyl phosphate anion, dioctyl phosphate. Examples of the anion include dimethyl phosphate anion, diethyl phosphate anion, dipropyl phosphate anion, and dibutyl phosphate anion.

  As the imidazolium phosphate ester salt (B) in the present invention, a compound represented by the following general formula (2) has a low melting point and is easily compatible with a fluorine atom-containing ionic liquid as a main component. This is preferable.

(In the formula, R 1 and R 2 are each independently an alkyl group having 1 to 16 carbon atoms, and R 3 is an alkyl group having 1 to 8 carbon atoms.)

Specific examples of the compound (B) represented by the following general formula (2) include 1,3-dimethylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium dimethyl phosphate, and 1-methyl-3-propylimidazole. Lithium dimethyl phosphate, 1-butyl-3-methylimidazolium dimethyl phosphate, 1-methyl-3-pentylimidazolium dimethyl phosphate, 1-hexyl-3-methylimidazolium dimethyl phosphate, 1-heptyl-3-methylimidazolium dimethyl Phosphate, 1-methyl-3-octylimidazolium dimethyl phosphate,
1-methyl-3-nonylimidazolium dimethyl phosphate, 1-decyl-3-methylimidazolium dimethyl phosphate, 1-methyl-3-undecylimidazolium dimethyl phosphate, 1-dodecyl-3-methylimidazolium dimethyl phosphate, 1 Hexadecyl-3-methylimidazolium dimethyl phosphate, 1,3-diethylimidazolium dimethyl phosphate, 1-ethyl-3-propylimidazolium dimethyl phosphate, 1-butyl-3-ethylimidazolium dimethyl phosphate, 1-ethyl-3 -Pentylimidazolium dimethyl phosphate, 1-ethyl-3-hexylimidazolium dimethyl phosphate, 1-ethyl-3-heptylimidazolium dimethyl phosphate, 1-ethyl-3 Octylimidazolium dimethyl phosphate, 1-ethyl-3-nonylimidazolium dimethyl phosphate, 1-decyl-3-ethylimidazolium dimethyl phosphate, 1-ethyl-3-undecylimidazolium dimethyl phosphate, 1-dodecyl-3-ethyl Dimethyl phosphate anionic salts such as imidazolium dimethyl phosphate, 1-ethyl-3-hexadecylimidazolium dimethyl phosphate, 1-butyl-3-dodecylimidazolium dimethyl phosphate, 1-butyl-3-hexadecylimidazolium dimethyl phosphate, 1,3-dimethylimidazolium diethylphosphate, 1-ethyl-3-methylimidazolium diethylphosphate, 1-methyl-3-propylimidazolium diethylphosphate 1-butyl-3-methylimidazolium diethyl phosphate, 1-methyl-3-pentylimidazolium diethyl phosphate, 1-hexyl-3-methylimidazolium diethyl phosphate, 1-heptyl-3-methylimidazolium diethyl phosphate, 1-methyl-3-octylimidazolium diethyl phosphate, 1-methyl-3-nonylimidazolium diethyl phosphate, 1-decyl-3-methylimidazolium diethyl phosphate,
1-methyl-3-undecylimidazolium diethyl phosphate, 1-dodecyl-3-methylimidazolium diethyl phosphate, 1-hexadecyl-3-methylimidazolium diethyl phosphate, 1,3-diethylimidazolium diethyl phosphate, 1-ethyl -3-propylimidazolium diethyl phosphate, 1-butyl-3-ethylimidazolium diethyl phosphate, 1-ethyl-3-pentylimidazolium diethyl phosphate, 1-ethyl-3-hexylimidazolium diethyl phosphate, 1-ethyl-3 -Heptylimidazolium diethylphosphate, 1-ethyl-3-octylimidazolium diethylphosphate, 1-ethyl-3-nonylimidazolium diethylphosphate, 1-decyl- -Ethyl imidazolium diethyl phosphate, 1-ethyl-3-undecylimidazolium diethyl phosphate, 1-dodecyl-3-ethyl imidazolium diethyl phosphate, 1-ethyl-3-hexadecylimidazolium diethyl phosphate, 1-butyl-3 -Dodecylimidazolium diethyl phosphate, diethyl phosphate anion salt such as 1-butyl-3-hexadecylimidazolium diethyl phosphate, 1,3-dimethylimidazolium dipropyl phosphate, 1-ethyl-3-methylimidazolium dipropyl phosphate 1-methyl-3-propylimidazolium dipropyl phosphate, 1-butyl-3-methylimidazolium dipropyl phosphate, 1-methyl-3-pentylimidazolium Propyl phosphate, 1-hexyl-3-methylimidazolium dipropyl phosphate, 1-heptyl-3-methylimidazolium dipropyl phosphate, 1-methyl-3-octylimidazolium dipropyl phosphate, 1-methyl-3-nonylimidazo 1-decyl-3-methylimidazolium dipropyl phosphate, 1-methyl-3-undecylimidazolium dipropyl phosphate, 1-dodecyl-3-methylimidazolium dipropyl phosphate, 1-hexadecyl-3 -Methylimidazolium dipropyl phosphate, 1,3-diethylimidazolium dipropyl phosphate, 1-ethyl-3-propylimidazolium dipropyl phosphate, 1-butyl-3-ethylimidazole 1-ethyl-3-pentylimidazolium dipropyl phosphate, 1-ethyl-3-hexylimidazolium dipropyl phosphate, 1-ethyl-3-heptylimidazolium dipropyl phosphate, 1-ethyl-3- Octylimidazolium dipropyl phosphate, 1-ethyl-3-nonylimidazolium dipropyl phosphate, 1-decyl-3-ethylimidazolium dipropyl phosphate,
1-ethyl-3-undecylimidazolium dipropyl phosphate, 1-dodecyl-3-ethylimidazolium dipropyl phosphate, 1-ethyl-3-hexadecylimidazolium dipropyl phosphate, 1-butyl-3-dodecylimidazolium Dipropyl phosphate anion salts such as dipropyl phosphate, 1-butyl-3-hexadecylimidazolium dipropyl phosphate, 1,3-dimethylimidazolium dibutyl phosphate, 1-ethyl-3-methylimidazolium dibutyl phosphate, 1- Methyl-3-propylimidazolium dibutyl phosphate, 1-butyl-3-methylimidazolium dibutyl phosphate, 1-methyl-3-pentylimidazolium dibutyl phosphate, 1-hexyl-3-methyl Louis imidazolium dibutyl phosphate, 1-heptyl-3-methylimidazolium dibutyl phosphate, 1-methyl-3-octylimidazolium dibutyl phosphate, 1-methyl-3-nonylimidazolium dibutyl phosphate, 1-decyl-3-methylimidazole 1-methyl-3-undecylimidazolium dibutyl phosphate, 1-dodecyl-3-methylimidazolium dibutyl phosphate, 1-hexadecyl-3-methylimidazolium dibutyl phosphate, 1,3-diethylimidazolium dibutyl phosphate 1-ethyl-3-propylimidazolium dibutyl phosphate, 1-butyl-3-ethylimidazolium dibutyl phosphate, 1-ethyl-3-pentylimidazole Mudibutyl phosphate, 1-ethyl-3-hexylimidazolium dibutyl phosphate, 1-ethyl-3-heptylimidazolium dibutyl phosphate, 1-ethyl-3-octylimidazolium dibutyl phosphate, 1-ethyl-3-nonylimidazolium dibutyl Phosphate, 1-decyl-3-ethylimidazolium dibutyl phosphate, 1-ethyl-3-undecylimidazolium dibutyl phosphate, 1-dodecyl-3-ethylimidazolium dibutyl phosphate, 1-ethyl-3-hexadecylimidazolium dibutyl Dibutyl phosphate anionic salts such as phosphate, 1-butyl-3-dodecylimidazolium dibutyl phosphate, 1-butyl-3-hexadecylimidazolium dibutyl phosphate, etc. Among these, those containing a dipropyl phosphate anion salt and a dibutyl phosphate anion salt are preferable because they are excellent in both compatibility with an ionic liquid and lubrication characteristics.

  As a compounding quantity of imidazolium phosphate ester salt (B), it is preferable that it is the range of 0.001-5 weight part with respect to 100 weight part of ionic liquid (A), for example, Most preferably, it is 0.01. ˜2 parts by weight, particularly preferably 0.05 to 1 part by weight. When the compounding amount of the compound (B) is too small, the function as a lubricating oil additive tends not to be sufficiently exhibited, and when it is too large, there is a tendency that it is not uniformly dispersed or dissolved in the lubricant.

  In the present invention, the synthetic lubricant which “contains mainly” an ionic liquid usually indicates a synthetic lubricant containing 50% by weight or more of the ionic liquid.

The synthetic lubricant of the present invention can be obtained, for example, by a method in which an ionic liquid (A) and an imidazolium phosphate ester salt (B) are appropriately blended and heated and stirred as necessary.
The obtained ionic liquid composition may be in a solution state in which the imidazolium phosphate ester salt (B) is dissolved in the ionic liquid (A), or the imidazolium phosphate ester salt (B ) May be dispersed.

  In addition, the synthetic lubricant of the present invention contains various additives such as conventionally known lubricating base oils, extreme pressure agents, and oily agents, as necessary, to the extent that the effects of the present invention are not hindered. Also good.

  The synthetic lubricant composed of the ionic liquid (A) and the imidazolium phosphate ester salt (B) thus obtained varies depending on the conditions of use of the lubricant, but preferably satisfies the following lubricating performance.

  For the purpose of using a low-viscosity lubricant, the viscosity of the synthetic lubricant at 25 ° C. is usually preferably 30 mPa · s or less, more preferably 20 mPa · s or less. If the viscosity is too high, energy loss tends to occur due to the viscosity of the lubricant itself. Further, the lower limit of the viscosity is usually 2 mPa · s, and if it is less than the lower limit, the viscosity tends to be scattered due to low viscosity.

The viscosity index of the synthetic lubricant is preferably 180 or more, more preferably 200 or more, and particularly preferably 220 or more. Here, the viscosity index is an index representing the relationship between temperature and viscosity, and the calculation method of the viscosity index is Japan Industrial Standard (JIS) K2283 (kinematic viscosity test method for crude oil and petroleum products and petroleum product viscosity index calculation method). ).
In addition, the higher the viscosity index, the smaller the change in viscosity due to temperature, which means that it is excellent as a lubricant.

  The lubricant may be used in cases where the absolute viscosity is important depending on the application, or in which other physical properties such as a contact angle with a metal are more important than the absolute viscosity. In this case, the organic cation is selected from imidazolium cation, pyridinium cation, quaternary ammonium cation and quaternary phosphonium cation according to the required physical properties, and further, if necessary, the physical properties are adjusted by changing the substituent. Also in this case, the viscosity index is a physical property regarded as important. When the viscosity index is less than the lower limit, the rate of change in viscosity with temperature tends to be too high.

  The synthetic lubricant of the present invention has excellent viscosity characteristics of an ionic liquid, and has various physical properties such as non-volatility and thermal stability, as well as lubricity and rust prevention that could not be obtained alone. It can be widely used as a mechanical device for automobiles, electrical products, etc., a power transmission device, a lubricant for precision machinery, metalworking oil, and a lubricant under special circumstances.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “parts” and “%” mean weight basis unless otherwise specified.

[Production Example of Fluorine Atom-Containing Ionic Liquid (A)]

<Production Example 1> Synthesis of 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide (A-1) In a flask equipped with a reflux tube, 6.28 g (76.5 mmol) of 1-methylimidazole was added, Ethyl bromide 33.01 g (302.9 mmol) and acetonitrile 8.20 g were added and reacted at 40 ° C. for 8 hours to give 13.41 g (70.2 mmol, yield 91) of 1-ethyl-3-methylimidazolium bromide. 8%). Reaction of 11.04 g (57.8 mmol) of the obtained 1-ethyl-3-methylimidazolium bromide and 13.29 g (60.6 mmol) of the potassium salt of bis (fluorosulfonyl) imide in 20 g of water at 50 ° C. for 4 hours. Then, 50 ml of methylene chloride is added and the methylene chloride layer is separated. The methylene chloride layer was washed with water and then dried under reduced pressure to obtain 15.85 g (54.4 mmol, yield 94.2%) of 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide.

<Production Example 2> Synthesis of 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (A-2) 1-ethyl-3-methylimidazolium bromide obtained by the same method as Production Example 1 11 0.04 g (60.6 mmol) and potassium salt of bis (trifluoromethanesulfonyl) imide anion 20.33 g (63.66 mmol) were reacted in 20 g of water-methylene chloride at 40 ° C. for 4 hours, and then the aqueous layer was separated. After separating with a liquid funnel, washed with water and dried under reduced pressure to obtain 22.53 g (57.6 mmol, yield 95%) of 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide.

<Production Example 3> Synthesis of 1-methyl-3-octylimidazolium bis (trifluoromethanesulfonyl) imide (A-3) 1-ethyl-3-methylimidazolium bromide of Production Example 2 was converted to 1-methyl-3-octyl. The target 1-methyl-3-octylimidazolium bis (trifluoromethanesulfonyl) imide was synthesized in the same manner as in Production Example 2, except that the amount was changed to 16.7 g of imidazolium bromide (yield). 91%).

[Production Example of Imidazolium Phosphate Salt (B)]
The following imidazolium phosphate ester salt (B) was synthesized according to WO 2008-114584 and Feul vol 87 79-84 page 2008.

<Production Example 4> Synthesis of 1-ethyl-3-methylimidazolium dimethyl phosphate (B-1) 17.5 g of trimethyl phosphoric acid is added to 10.0 g of 1-ethylimidazole and heated at 80 ° C for 72 hours. After heating, cool to room temperature and wash 5 times with 50 ml of toluene. The lower layer 1-ethyl-3-methylimidazolium dimethyl phosphate was dried at 60 ° C. under vacuum to obtain 24.4 g of the desired product.

<Production Example 5> Synthesis of 1-dodecyl-3-methylimidazolium dimethyl phosphate (B-2) 10.0 g of 1-ethylimidazole of Production Example 4 was changed to 10.0 g of 1-dodecylimidazole, and trimethyl phosphate 17. The same operation was carried out except that 5 g was changed to 7.1 g to obtain 15.4 g of the desired product.

<Production Example 6> Synthesis of 1-hexadecyl-3-methylimidazolium dimethyl phosphate (B-3) 10.0 g of 1-ethylimidazole in Production Example 4 was changed to 10.0 g of 1-hexadecylimidazole, and trimethyl phosphate 17 The same operation was carried out except that 0.5 g was changed to 5.7 g, and 13.2 g of the target product was obtained.

<Production Example 7> Synthesis of 1-ethyl-3-methylimidazolium diethyl phosphate (B-4) 10.0 g of 1-ethylimidazole of Production Example 4 was changed to 10.0 g of 1-methylimidazole, and trimethyl phosphate 17. The same operation was carried out except that 5 g was changed to 26.7 g of triethyl phosphoric acid to obtain 33.1 g of the desired product.

<Production Example 8> Synthesis of 1-ethyl-3-dodecylimidazolium diethyl phosphate (B-5) 10.0 g of 1-ethylimidazole of Production Example 4 was changed to 10.0 g of 1-dodecylimidazole, and trimethyl phosphate 17. The same operation was carried out except that 5 g was changed to 9.3 g of triethyl phosphoric acid and 50 ml of toluene was changed to 15 ml of dibutyl ether to obtain 7.2 g of the desired product.

<Production Example 9> Synthesis of 1-butyl-3-ethylimidazolium dibutyl phosphate (B-6) 33.3 g of tributyl phosphoric acid is added to 10.0 g of 1-ethylimidazole and heated at 120 ° C for 120 hours. After heating, cool to room temperature and wash 6 times with 50 ml of hexane. The lower layer 1-butyl-3-ethylimidazolium dibutyl phosphate was dried at 60 ° C. under vacuum to obtain 25.0 g of the desired product.

<Production Example 10> Synthesis of 1-butyl-3-dodecylimidazolium dibutyl phosphate (B-7) 10.0 g of 1-ethylimidazole in Production Example 9 was changed to 10.0 g of 1-dodecylimidazole, and tributyl phosphate was changed to 13 The same operation was carried out except that the amount was changed to 0.5 g, to obtain 6.5 g of the desired product.

<Production Example 11> Synthesis of 1-butyl-3-hexadecylimidazolium dibutyl phosphate (B-8) 1-ethylimidazole in Production Example 9 was changed from 10.0 g to 10.0 g of 1-hexadecylimidazole, and tributyl phosphate The same operation was carried out except that 10.9 g was changed to 8.7 g of the desired product.

<Production Example 12> Synthesis of 1- (O, O, dimethylphosphoryl) -3-n-octylimidazolium hexafluorophosphate
To 1 mol of 1-octylimidazole, 3 mol of phosphoric acid chloride dimethyl ester was added, 100 ml of methylene chloride was added, stirred for several days under reflux, concentrated methylene chloride, washed with a solvent, dried and 1- ( O, O, dimethylphosphoryl) -3-n-octylimidazolium chloride was obtained. 1 mol of 1- (O, O, dimethylphosphoryl) -3-n-octylimidazolium chloride obtained is charged with 1 mol of KPF6 and 300 ml of water, stirred at room temperature for 5 hours, and after separation, the lower layer is dried. 1- (O, O, dimethylphosphoryl) -3-n-octylimidazolium hexafluorophosphate was obtained quantitatively.

<Examples 1-5>
To 100 parts by weight of the ionic liquid (A-1) obtained in Production Example 1, 0.5 part by weight of imidazolium phosphate ester salt (B-1, 4-7) is added and heated to 40 ° C. sufficiently. The synthetic lubricants of Examples 1 to 5 were obtained by mixing and stirring.

<Comparative Example 1>
In the ionic liquids (A-1) of Examples 1 to 5, a synthetic lubricant was obtained in the same manner except that the imidazolium phosphate ester salt (B) was not used.

<Example 6>
To 100 parts by weight of the ionic liquid (A-2) obtained in Production Example 2, 0.5 part by weight of imidazolium phosphate ester salt (B-5) is added, heated to 40 ° C., and sufficiently mixed and stirred. Thus, the synthetic lubricant of Example 6 was obtained.

<Comparative Example 2>
A synthetic lubricant was obtained in the same manner except that the imidazolium phosphate ester salt (B) was not used in the ionic liquid (A-2) of Example 6.

<Examples 7 to 13>
To 100 parts by weight of the ionic liquid (A-3) obtained in Production Example 3, 0.5 part by weight of imidazolium phosphate ester salt (B-2 to 8) is added and heated to 40 ° C. and mixed thoroughly. By stirring, the synthetic lubricants of Examples 7 to 13 were obtained.

<Comparative Example 3>
Synthetic lubricants were obtained in the same manner as in Examples 7 to 13 except that the imidazolium phosphate ester salt (B) was not used in the ionic liquids (A-3).

<Comparative Example 4>
To 100 parts by weight of the ionic liquid (A-1) obtained in Production Example 1, 1- (O, O, dimethylphosphoryl) -3-n-octylimidazolium hexafluorophosphate (hereinafter referred to as [PO (OMe)). ₂ OcIm] PF ₆ ) was added, and the mixture was heated to 40 ° C. and sufficiently mixed and stirred to obtain a synthetic lubricant of Comparative Example 4 .

  The resulting synthetic lubricant was subjected to the following lubrication performance evaluation and rust prevention performance evaluation. The results are shown in [Table 1].

● Lubrication performance evaluation <Friction coefficient>
A friction coefficient under the following conditions was measured using a lubricating oil friction tester (manufactured by Kyoshin Co., Ltd., “KT-1203”). In addition, the value of the friction coefficient was shown by the average value except the value of the measurement initial stage (0-30 seconds) among all the coefficient data obtained during the measurement time on the following conditions.
[Measurement condition]
Experimental materials: 3/16 inch SUJ-2 steel ball, SCM435 bearing steel plate (φ25 mm × 5 mm, HRC> 40, Rz≈0.8
(Μm))
Load load: 0.1kgf
Friction speed: 5mm / sec
Reciprocating stroke: 5mm,
Data recording interval: 4 sec
Measurement temperature: Examples 1 to 5, Comparative Example 1; Room temperature to 150 ° C. (stepwise temperature increase)
: Examples 6 to 13 , Comparative Examples 2 to 4 ; Room temperature to 200 ° C (stepwise temperature increase)
Measurement time: 20 minutes <wear volume>
It calculated | required by the following formula from the wear scar diameter (minor axis: a, major axis: b) of SUJ-2 steel ball after completion | finish of the said friction test.
Wear volume = πa ³ b / 32D (D: diameter of steel ball) (unit: μm ³ )
[Criteria]
◎ ··· 4,000μm less than ³ ○ ··· 4,000μm ³ or more 10,000μm less than ³ △ ··· 10,000μm ³ or more ~20,000μm ³ less than × ··· 20,000μm ³ or more

● Rust prevention performance evaluation The presence or absence of rust on the wear marks generated on the test steel sheet after completion of the friction test was determined.
[Criteria]
○ ・ ・ ・ Rust is not observed even if the wear trace on the test steel sheet is enlarged. △ ・ ・ ・ Rust is observed if the wear trace on the test steel sheet is enlarged. × ・ ・ ・Rust is recognized in

From the results shown in Table 1, the synthetic lubricant obtained by adding the imidazolium phosphate ester salt to the ionic liquids of the examples has higher friction performance and rust prevention than the synthetic lubricant obtained by adding no imidazolium phosphate ester salt of the comparative example. It turns out that it is excellent in both performance.
This indicates that the imidazolium phosphate ester salt of the present invention is a useful compound as a friction modifier and a rust preventive for a synthetic lubricant mainly composed of an ionic liquid.

  The lubricant composition of the present invention has an essential lubricating performance enhanced by an additive when the composition utilizing the characteristics of an ionic liquid as a base oil of the lubricating oil is put into practical use. It is useful as a mechanical device such as a power transmission device, a precision machine, and a lubricant in a special environment.

Claims (6)

A synthetic lubricant comprising, as a main component , a fluorine atom-containing ionic liquid (A) whose cation portion is an imidazolium cation, and comprising an imidazolium phosphate ester salt (B). The anion moiety of the fluorine-containing ionic liquid (A) is, synthetic lubricants according to claim 1 Symbol mounting, characterized in that a fluorine-containing imide anion represented by the following general formula (1).
[Chemical 1]
(C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (1)
(Where n is an integer from 0 to 15) The synthetic lubricant according to claim 1 or 2 , wherein the anion portion of the fluorine atom-containing ionic liquid (A) is bis (fluorosulfonyl) imide or bis (trifluoromethanesulfonyl) imide. The synthetic lubricant according to any one of claims 1 to 3 , wherein the imidazolium cation of the imidazolium phosphate ester salt (B) is a 1,3-disubstituted imidazolium cation. The synthetic lubricant according to any one of claims 1 to 4 , wherein the phosphate anion of the imidazolium phosphate ester salt (B) is a phosphate anion having a diester structure. The synthetic lubricant according to any one of claims 1 to 5, wherein the imidazolium phosphate ester salt (B) is a compound represented by the following general formula (2).
(In the formula, R 1 and R 2 are each independently an alkyl group having 1 to 16 carbon atoms, and R 3 is an alkyl group having 1 to 8 carbon atoms.)