JP2008291231A - Ionic liquid composition and synthetic lubricant comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ionic liquid composition whose viscosity is so low as to sufficiently function as a lubricant and which is excellent in thermal stability without causing coloring degradation even at a high temperature. <P>SOLUTION: The ionic liquid composition comprises an ionic liquid consisting of a cationic part and an anionic part. The ionic liquid is an ionic liquid (A) having a halogen atom in the anionic part. The ionic liquid composition contains the ionic liquid (A) and at least one compound (B) selected from the group consisting of neutral salts and basic compounds. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ionic liquid composition containing an ionic liquid and at least one compound selected from the group consisting of a neutral salt and a basic compound, and particularly relates to an ionic liquid composition having lubricating oil performance. Is.

  Conventionally, as a lubricating oil used for mechanical devices, power transmission devices, metalworking oils, greases, etc., base oils of the types closest to the target physical properties among base oils such as poly α-olefins, diesters, polyol esters, silicones, etc. Have been selected, combined as necessary, and further added with appropriate additives. However, these lubricating oils have a risk of ignition or evaporation under special circumstances such as high temperature and high vacuum, and more suitable lubricating oils are desired. In addition, with higher performance and higher efficiency of the apparatus, there is a demand for a lubricating oil having better oxidation resistance and evaporation resistance and excellent lubricating performance over a long period of time.

As means for solving these problems, for example, Non-Patent Document 1 reports that a compound composed of a combination of an organic cation and an inorganic anion, a so-called ionic liquid (room temperature molten salt) can be applied as a lubricating oil, At present, the ionic liquid is not only non-volatile, excellent in stability over a wide temperature range and flame retardancy, but also has some physical properties that satisfy the friction coefficient required for the lubricant and the friction scar diameter. It is known as a material for lubricating oil.
R. A. Reich et al. , Journal of the Society of Tribologists and Lubrication Engineers, July 2003, p. 16-21

  However, in general, many ionic liquids have high viscosity and high specific gravity, and in order to put them into practical use as lubricating oil, etc., it is necessary to find ionic liquids with low viscosity. It is hoped that. Accordingly, the present inventors proceeded with research and development for the purpose of obtaining a low-viscosity ionic liquid, and halogen atoms (particularly fluorine atoms) such as bis (trifluoromethanesulfonyl) imide anion and bis (fluorosulfonyl) imide anion. ) Having an anionic moiety having a low viscosity), a low viscosity ionic liquid was obtained.

  However, the ionic liquid containing an anion moiety having this halogen atom (especially fluorine atom) is slightly lower in heat resistance than expected, and causes problems such as color deterioration at high temperatures. The reality is that no solution is available.

  The present invention has been made in view of such circumstances, an ionic liquid composition having a low viscosity to such an extent that it sufficiently functions as a lubricating oil and the like and excellent in thermal stability that does not cause coloring deterioration even at high temperatures. The purpose is to provide

  In order to achieve the above object, the present invention is an ionic liquid composition comprising an ionic liquid composed of a cation part and an anion part, the ionic liquid being an ionic liquid (A) having a halogen atom in the anion part, An ionic liquid composition containing the ionic liquid (A) and at least one compound (B) selected from the group consisting of a neutral salt and a basic compound is a first gist, and the ionic liquid composition Synthetic lubricating oil using the product is a second gist.

That is, the present inventors made extensive studies in view of the above circumstances. In the process, when the ionic liquid (A) having a halogen atom in the anion portion is heated, for example, when the halogen atom is a fluorine atom, fluoride ions (F ⁻ ) released from the anion portion of the ionic liquid are It reacts with water [hydrogen ion (H ⁺ )] in the air to form HF (acid), and depending on the type of anion moiety, sulfuric acid (H ₂ SO ₄ ), sulfamic acid (NH ₂ SO ₃ H), etc. It was found that the generation of these acidic substances promotes further decomposition and decreases the heat resistance of the ionic liquid. As a result of further research based on this knowledge, the present inventors have found that at least one compound (B) selected from the group consisting of a neutral salt and a basic compound is an acid produced from the ionic liquid (A). Since the substance is trapped, it has been found that this improves the thermal stability of the ionic liquid (A) at a high temperature, and the present invention has been reached. That is, in the ionic liquid (A) having a halogen atom in the anion part, by blending at least one compound (B) selected from the group consisting of a neutral salt and a basic compound as a compounding agent, In addition, an ionic liquid composition having excellent thermal stability can be obtained. In particular, the ionic liquid composition is suitably used for a lubricating oil.

  The present invention is an ionic liquid composition comprising an ionic liquid comprising a cation part and an anion part, wherein the ionic liquid is an ionic liquid (A) having a halogen atom in the anion part, and the ionic liquid (A), An ionic liquid composition comprising at least one compound (B) selected from the group consisting of a neutral salt and a basic compound. Thus, when at least one compound selected from the group consisting of a neutral salt and a basic compound is blended with an ionic liquid having a halogen-containing anion moiety, it has low viscosity and excellent thermal stability.

  Next, embodiments of the present invention will be described in detail.

  The ionic liquid composition of the present invention is an ionic liquid composition containing an ionic liquid, and has an ionic liquid (A) having a halogen atom in the anion portion (hereinafter sometimes abbreviated as “ionic liquid (A)”). And at least one compound (B) selected from the group consisting of neutral salts and basic compounds (hereinafter sometimes abbreviated as “compound (B)”). Here, the ionic liquid in the present invention represents an ionic substance composed of a cation portion and an anion portion that holds the liquid at a constant temperature in the range of 0 to 150 ° C.

  The anion portion of the ionic liquid (A) used in the present invention is not particularly limited as long as it is an anion having a halogen atom as described above, and an anion used in a general ionic liquid is used. Is possible. Further, the type of halogen atom contained in the anion is not particularly limited, but in particular, a fluorine atom is preferably used.

  Examples of such an anion having a fluorine atom include bis (fluorosulfonyl) imide anion, bis (trifluoromethanesulfonyl) imide anion, (fluorosulfonyl) (trifluoromethanesulfonyl) imide anion, and (trifluoroacetyl) (trifluoromethane). Examples include imide anions such as (sulfonyl) imide anion, phosphate anions such as hexafluorophosphate anion, and borate anions such as tetrafluoroborate anion. Among them, it is preferable to use imide anions. In particular, bis (fluorosulfonyl) imide anion and bis (trifluoromethanesulfonyl) imide anion have low solubility in water, that is, hygroscopicity of water in the open atmosphere. Is preferable in that there is almost no.

  The anion part having the halogen atom may be the same type or different from each other, but when the anion part is the same, compared with the case of having multiple types of anion parts, In particular, the anion moieties of the same type are preferable.

  The cation portion of the ionic liquid (A) used in the present invention is not particularly limited, and a cation used in a general ionic liquid is used. Examples of such cations include, for example, cations of heterocyclic compounds, particularly cations of 1 to 5 membered heterocyclic compounds containing 1 to 5 heteroatoms, particularly nitrogen atoms as heteroatoms. Examples thereof include cations of 1 to 5 membered heterocyclic compounds containing 1 to 5 heteroatoms, including imidazolium cation, pyrrolidinium cation, piperidinium cation, and pyridinium cation. It is also preferable to use a chain-like quaternary ammonium cation or quaternary phosphonium cation. Among these, imidazolium cation, pyridinium cation, quaternary ammonium cation, and quaternary phosphonium cation are preferable, and imidazolium cation is particularly preferable in terms of low viscosity.

  Examples of the imidazolium cation include 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, 1-methyl-3-propylimidazolium ion, and 1-butyl-3-methylimidazolium ion. 1-methyl-3-pentylimidazolium ion, 1-hexyl-3-methylimidazolium ion, 1-heptyl-3-methylimidazolium ion, 1-methyl-3-octylimidazolium ion, 1-decyl-3 Dialkyl imidazolium ions such as methyl imidazolium ion, 1-dodecyl-3-methyl imidazolium ion, 1-ethyl-3-propyl imidazolium ion, 1-butyl-3-ethyl imidazolium ion, 3-ethyl-1 , 2-dimethyl-imidazolium ion, , 2-dimethyl-3-propylimidazolium ion, 1-butyl-2,3-dimethylimidazolium ion, 1,2-dimethyl-3-hexylimidazolium ion, 1,2-dimethyl-3-octylimidazolium ion 1-ethyl-3,4-dimethylimidazolium ion, trialkylimidazolium ion such as 1-isopropyl-2,3-dimethylimidazolium ion, and the like.

  Examples of the pyrrolidinium cation include N, N-dimethylpyrrolidinium ion, N-ethyl-N-methylpyrrolidinium ion, N-methyl-N-propylpyrrolidinium ion, and N-butyl-N-methylpyrrolidinium. Ion, N-methyl-N-pentylpyrrolidinium ion, N-hexyl-N-methylpyrrolidinium ion, N-methyl-N-octylpyrrolidinium ion, N-decyl-N-methylpyrrolidinium ion, N-dodecyl- N-methylpyrrolidinium ion, N- (2-methoxyethyl) -N-methylpyrrolidinium ion, N- (2-ethoxyethyl) -N-methylpyrrolidinium ion, N- (2-propoxyethyl) -N- Methylpyrrolidinium ion, N- (2-isopropoxyethyl) -N-me Le pyrrolidinium ions and the like.

  Examples of the piperidinium cation include N, N-dimethylpiperidinium ion, N-ethyl-N-methylpiperidinium ion, N-methyl-N-propylpiperidinium ion, and N-butyl-N-methylpiperidinium. , N-methyl-N-pentylpiperidinium ion, N-hexyl-N-methylpiperidinium ion, N-methyl-N-octylpiperidinium ion, N-decyl-N-methylpiperidinium ion, N-dodecyl- N-methylpiperidinium ion, N- (2-methoxyethyl) -N-methylpiperidinium ion, N- (2-methoxyethyl) -N-ethylpiperidinium ion, N- (2-ethoxyethyl) -N- Methylpiperidinium ion, N-methyl-N- (2-methoxyphenyl) pi Lidinium ion, N-methyl-N- (4-methoxyphenyl) piperidinium ion, N-ethyl-N- (2-methoxyphenyl) piperidinium ion, N-ethyl-N- (4-methoxyphenyl) piperidinium ion Etc.

  Examples of the pyridinium cation include a pyridinium cation substituted with an alkyl group having 1 to 16 carbon atoms such as N-methylpyridinium, N-ethylpyridinium, N-butylpyridinium, and N-propylpyridinium.

  Examples of the quaternary ammonium cation include N, N, N, N-tetramethylammonium ion, N, N, N-trimethylethylammonium ion, N, N, N-trimethylpropylammonium ion, N, N, N-trimethylbutylammonium ion, N, N, N-trimethylpentylammonium ion, N, N, N-trimethylhexylammonium ion, N, N, N-trimethylheptylammonium ion, N, N, N-trimethyloctylammonium ion N, N, N-trimethyldecylammonium ion, N, N, N-trimethyldodecylammonium ion, N-ethyl-N, N-dimethylpropylammonium ion, N-ethyl-N, N-dimethylbutylammonium ion, N -Ethyl-N, -Dimethylhexylammonium ion, 2-methoxy-N, N, N-trimethylethylammonium ion, 2-ethoxy-N, N, N-trimethylethylammonium ion, 2-propoxy-N, N, N-trimethylethylammonium ion N- (2-methoxyethyl) -N, N-dimethylpropylammonium ion, N- (2-methoxyethyl) -N, N-dimethylbutylammonium ion, and the like.

  Examples of the quaternary phosphonium cation include a quaternary phosphonium cation substituted with an alkyl group having 1 to 16 carbon atoms such as tetramethylphosphonium, tetraethylphosphonium, and tetrabutylphosphonium.

  The cation parts may be of the same type or different from each other, but when the cation parts are the same, it is advantageous in production as compared with the case of having many kinds of cation parts. Therefore, it is particularly preferable that they are the same type of cation moiety.

  By using these cations together with the anion having the halogen atom, the viscosity of the ionic liquid can be greatly reduced, which is suitable as a synthetic lubricating oil.

  Although it does not specifically limit as a manufacturing method of the ionic liquid (A) used by this invention, Well-known methods, such as an ion exchange method or a metathesis reaction, are applicable. For example, it can be obtained by an anion exchange reaction using the halide salt of the cation moiety and the alkali metal salt of the anion moiety. Examples of the halogen of the halogenated salt include chlorine and bromine. Examples of the alkali metal of the alkali metal salt include sodium, potassium, lithium and the like.

  The at least one compound (B) selected from the group consisting of a neutral salt and a basic compound used in the present invention is not particularly limited, and examples thereof include a neutral salt, a basic inorganic salt, and a base. Organic materials and the like. These compounds may be either liquid or solid, and may be used alone or in combination of two or more.

  Examples of the neutral salt include potassium fluoride, potassium chloride, potassium sulfate and the like.

  Examples of the basic inorganic salt include basic phosphates such as dipotassium hydrogen phosphate, trisodium phosphate and ammonium dihydrogen phosphate, and basic carbonates such as sodium carbonate, ammonium carbonate, lithium carbonate and potassium carbonate. Examples thereof include basic hydrogen carbonates such as salts, lithium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. Among these, basic phosphates such as dipotassium hydrogen phosphate, trisodium phosphate, and ammonium dihydrogen phosphate are preferably used.

  As the basic organic substance, a compound having 1 to 30 carbon atoms, preferably 1 to 25 carbon atoms, particularly 1 to 20 carbon atoms is generally used. For example, aliphatic primary amine compounds such as methylamine, ethylamine, propylamine and the like. Aromatic primary amine compounds such as benzylamine, aliphatic secondary amine compounds such as dimethylamine and ethylmethylamine, aromatic secondary amine compounds such as benzylmethylamine, triethylamine, ethyldiisopropylamine, N- Aliphatic tertiary amine compounds such as methylmorpholine, 1,8-diazabicyclo [5.4.0] -7-undecene (DBU), pyridine, 2,4,6-trimethylpyridine, 2,6-di (t -Butyl) pyridine compounds such as pyridine, 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole , 1-octyl imidazole, aromatic tertiary amine compounds of imidazole compounds such as 1-dodecyl imidazole. Among these, aliphatic and aromatic tertiary amine compounds are preferably used, and aromatic tertiary amine compounds are particularly preferably imidazole compounds because they have a high boiling point and are difficult to volatilize.

  Moreover, as said compound (B), when it becomes a saturated aqueous solution at the density | concentration of 0.01M aqueous solution or less than it, it is preferable that the pH in 20 degreeC of a saturated aqueous solution is especially 6-13, Furthermore, it is preferable that it is 7-12. When a compound outside the pH range is blended in place of the compound (B), a tendency to be inferior in thermal stability is observed.

  The blending amount of at least one compound (B) selected from the group consisting of a neutral salt and a basic compound is, for example, 0 with respect to 100 parts by weight (hereinafter abbreviated as “part”) of the ionic liquid (A). The range is preferably 0.001 to 10 parts, particularly preferably 0.01 to 1 part. When the compounding amount of the compound (B) is too small, the heat resistance tends to be inferior. Conversely, when the compounding amount is too large, the compound (B) which does not dissolve tends to inhibit the lubricating performance.

  The ionic liquid composition in the present invention may contain additives such as an antiwear agent, a rust inhibitor, and a corrosion inhibitor, as necessary. These may be used alone or in combination of two or more.

  The ionic liquid composition of the present invention is produced, for example, as follows. For example, by appropriately mixing and stirring the ionic liquid (A), at least one compound (B) selected from the group consisting of a neutral salt and a basic compound, and other additives as necessary can get. The obtained ionic liquid composition may be in a solution state in which the compound (B) is dissolved in the ionic liquid (A), or in a state in which the compound (B) is dispersed in the ionic liquid (A). Good.

  The ionic liquid composition of the present invention obtained as described above is hydrophobic, has a low viscosity, maintains a molten state even at low temperatures, and is excellent in various physical properties such as non-volatility, nonflammability, and thermal stability. It can be widely used as an electrolyte / electrolyte material for machinery equipment such as automobiles and electric products, power transmission equipment, lubricating oil for precision machinery, metalworking oil, batteries, capacitors, capacitors and the like. Especially, it is very useful especially for synthetic lubricating oil and electrolyte solution use, especially synthetic lubricating oil use.

  When the ionic liquid composition of the present invention is used for a synthetic lubricating oil, the ionic liquid composition of the present invention may be used as a lubricating oil as it is, but if necessary, a lubricating base oil that is usually used may be included. In addition, additives such as a rust inhibitor and a pour point depressant may be used as necessary.

  As described above, “using” an ionic liquid composition in the synthetic lubricating oil of the present invention means using the ionic liquid composition in combination with other materials, in addition to using only the ionic liquid composition. The amount of other materials used is not particularly limited as long as the effect of the present invention is not hindered, but is usually set to less than 50% by weight of the ionic liquid composition. The

  The viscosity of the synthetic lubricating oil of the present invention at 25 ° C. is preferably 2 to 30 mPa · s, more preferably 2 to 20 mPa · s. If this viscosity is too low, it tends to be scattered due to low viscosity, and conversely, if it is too high, energy loss due to the viscosity of the lubricating oil itself tends to occur.

The kinematic viscosity of the synthetic lubricating oil of the present invention is preferably ² to 20 mm ² / sec at 40 ° C., more preferably 5 to 13 mm ² / sec. Further, the kinematic viscosity of the synthetic lubricating oil of the present invention is preferably 1 to 10 mm ² / sec, more preferably ² to 5.5 mm ² / sec at 100 ° C. If the kinematic viscosity is too low at each temperature, the viscosity tends to be scattered due to the low viscosity. Conversely, if the kinematic viscosity is too high, energy loss due to the viscosity of the lubricating oil itself tends to occur.

  The viscosity index of the synthetic lubricating oil is preferably 400 or more, more preferably 430 or more, and particularly preferably 460 or more. The upper limit of the viscosity index is usually 700. Here, the viscosity index is an index representing the relationship between temperature and viscosity, and the calculation method of the viscosity index is defined in JIS K 2283 (dynamic viscosity test method for crude oil and petroleum products and petroleum product viscosity index calculation method). Say how. In addition, the higher the viscosity index, the smaller the change in viscosity due to temperature, which means that it is excellent as a lubricating oil.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to a following example, unless the summary is exceeded.

[Example 1]
0.5 g of ionic liquid [cation part: 1-ethyl-3-methylimidazolium ion (EMI ⁺ ), anion part: bis (fluorosulfonyl) imide (FSI ⁻ )] was taken in a test tube, and dipotassium hydrogen phosphate (K ₂ HPO ₄ ) [manufactured by Kishida Chemical Co., Ltd .: special grade] 0.5 mg was added and stirred to obtain an ionic liquid composition. The pH at 20 ° C. when the used K ₂ HPO ₄ was changed to a 0.01 M aqueous solution was 9.7.

[Example 2]
The same procedure as in Example 1 was performed except that dipotassium hydrogen phosphate of Example 1 was replaced with trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O) [Wako Pure Chemical Industries, Ltd .: Special Grade]. An ionic liquid composition was obtained. Incidentally, pH at 20 ° C. at the time of the _Na 3 _PO 4 · 12H ₂ O was used in 0.01M aqueous solution was 13.4.

Example 3
Except that dipotassium hydrogen phosphate of Example 1 was replaced with diammonium hydrogen phosphate [(NH ₄ ) 2 HPO ₄ ] [manufactured by Kishida Chemical Co., Ltd .: special grade] A liquid composition was obtained. The pH at 20 ° C. when the used (NH ₄ ) 2 HPO ₄ was changed to a 0.01 M aqueous solution was 8.3.

Example 4
An ionic liquid composition was obtained in the same manner as in Example 1 except that dipotassium hydrogen phosphate of Example 1 was replaced with potassium fluoride (KF) [manufactured by Kishida Chemical Co., Ltd .: Special Grade]. The pH at 20 ° C. when the used KF was changed to a 0.01M aqueous solution was 7.6.

Example 5
An ionic liquid composition was obtained in the same manner as in Example 1 except that dipotassium hydrogen phosphate of Example 1 was replaced with potassium chloride (KCl) [manufactured by Kishida Chemical Co., Ltd .: Grade 1]. The pH at 20 ° C. when the used KCl was changed to a 0.01 M aqueous solution was 6.3.

Example 6
An ionic liquid composition was obtained in the same manner as in Example 1 except that dipotassium hydrogen phosphate of Example 1 was replaced with potassium sulfate (K ₂ SO ₄ ) [manufactured by Kishida Chemical Co., Ltd .: Special Grade]. It was. The pH at 20 ° C. when the used K ₂ SO ₄ was a 0.01 M aqueous solution was 6.9.

Example 7
An ionic liquid composition was obtained in the same manner as in Example 1 except that 1-methylimidazole was used instead of dipotassium hydrogen phosphate in Example 1. The added 1-methylimidazole was completely dissolved. The pH at 20 ° C. when the used 1-methylimidazole was changed to a 0.01M aqueous solution was 10.4.

Example 8
An ionic liquid composition was obtained in the same manner as in Example 1 except that 1-octylimidazole was used instead of dipotassium hydrogen phosphate in Example 1. The added 1-octylimidazole was completely dissolved. In addition, although it was going to prepare 0.01M aqueous solution using the used 1-octyl imidazole, it became saturated aqueous solution with the compounding quantity of less than 0.01M. The pH of this saturated aqueous solution at 20 ° C. was 8.8.

Example 9
An ionic liquid composition was obtained in the same manner as in Example 1 except that 1-dodecylimidazole was used instead of dipotassium hydrogen phosphate in Example 1. The added 1-dodecylimidazole was completely dissolved. In addition, although it was going to prepare 0.01M aqueous solution using the used 1-dodecyl imidazole, it became saturated aqueous solution with the compounding quantity of less than 0.01M. The pH of this saturated aqueous solution at 20 ° C. was 7.5.

Example 10
The same procedure as in Example 1 was conducted except that dipotassium hydrogen phosphate of Example 1 was replaced with sodium carbonate (Na ₂ CO ₃ ) [manufactured by Kishida Chemical Co., Ltd .: Special Grade]. Incidentally, pH at 20 ° C. at the time of the _Na 2 CO ₃ was used in 0.01M aqueous solution was 12.4.

Example 11
The same procedure as in Example 1 was performed except that dipotassium hydrogen phosphate in Example 1 was replaced with ammonium carbonate [(NH ₄ ) 2 CO ₃ ] [manufactured by Kishida Chemical Co., Ltd .: Special Grade]. The pH at 20 ° C. when the used (NH ₄ ) 2 CO ₃ was changed to a 0.01 M aqueous solution was 9.6.

[Comparative Example 1]
0.5 g of ionic liquid [cation part: 1-ethyl-3-methylimidazolium ion (EMI ⁺ ), anion part: bis (fluorosulfonyl) imide (FSI ⁻ )] was taken in a test tube, and compound (B) was Not blended.

  Using the ionic liquid compositions (or ionic liquids) of Examples and Comparative Examples obtained as described above, the viscosity, kinematic viscosity and viscosity index were measured and evaluated according to the following methods.

<viscosity>
Equipment used: AR-1000 type rotational rheometer (TA Instruments)
Measurement method: The apparatus was set at 25 ° C., 0.6 ml of sample was placed on the sample stage, a cone was placed, and the viscosity value when this cone was rotated with a constant force (20 Pa) was read.

<Kinematic viscosity at 40 ° C. and 100 ° C.>
The kinematic viscosities at 40 ° C. and 100 ° C. were obtained by measuring the viscosity values at each temperature using the above-described apparatus and measurement method, and calculating from the values. Moreover, the viscosity index was calculated | required by calculation using the value of these kinematic viscosity.

  As a result, each of Examples 1 to 11 and Comparative Example 1 has a viscosity of 19 mPa · s, a kinematic viscosity at 40 ° C. of 9.4 mPa · s, and a kinematic viscosity at 100 ° C. of 4.9 mPa · s. And the viscosity index was 623. These show a low viscosity and a high viscosity index, and in this respect, it can be seen that they are excellent in properties as a synthetic lubricating oil. In addition, these Examples 1-11 and Comparative Example 1 all show the same value because the viscosity etc. of an ionic liquid composition depend on the kind of ionic liquid (A).

  In addition, using the obtained ionic liquid compositions (or ionic liquids) of Examples and Comparative Examples, the colorability after heating was measured and evaluated according to the following method, and the results are shown in Table 1 below. .

<Colorability after heat treatment>
Each ionic liquid composition (or ionic liquid) was taken into a test tube, placed in a thermostat previously heated to 170 ° C., and the presence or absence of coloring was confirmed visually every 30 minutes. Further, the heat resistance (colorability) of the lubricating oil was evaluated according to JIS K 2540. That is, in heating at 170 ° C., “◯” indicates that no coloring occurs after 12 hours, and “Δ” indicates that coloring is confirmed after 4 hours to 11.5 hours, and 0.5 to 3 ... After 5 hours, coloring was confirmed and evaluated as “x”.

  As can be seen from the results in Table 1, all of Examples 1 to 11 are not colored in heating for 8 hours, and in particular, in Examples 1 to 5 and Examples 7 to 9, even after 12 hours have elapsed. There was no coloring and it remained colorless and transparent. On the other hand, Comparative Example 1 turns yellow in a short time of 1 hour and turns brown after 1.5 hours, indicating that the thermal stability at high temperature is poor.

  Moreover, the thermogravimetric analysis measurement was performed about the ionic liquid composition (or ionic liquid) of Example 1 and Comparative Example 1 according to the following method. The measurement result of Comparative Example 1 is shown in FIG. 1, and the measurement result of Example 1 is shown in FIG.

<Thermal decomposition>
Equipment used: Thermogravimetric Analyzer (TGA-7) (Perkin Elmer)
Measurement conditions: Weight change (thermal decomposability) from 30 to 550 ° C. was measured using the thermogravimetric analyzer. The initial weight of the sample was about 12 mg, and the measurement was performed in air using an aluminum pan at a heating rate of 10 ° C./min.

  In Comparative Example 1 containing no compound (B), as shown in FIG. 1, weight loss was caused by thermal decomposition from around 190 ° C., whereas ionic liquid (A), compound (B) and As shown in FIG. 2, in Example 1 containing N, weight loss is caused by thermal decomposition from around 245 ° C. Thus, in Example 1, it can be seen that the thermal decomposition start temperature is shifted to a high temperature side by about 50 ° C. compared with Comparative Example 1, and the thermal stability is greatly improved.

  As is clear from the above results, the ionic liquid composition of the present invention containing the ionic liquid (A) and at least one compound (B) selected from the group consisting of a neutral salt and a basic compound is high. It has thermal stability. Thereby, the ionic liquid composition of this invention comes to be used suitably for lubricating oil.

It is a result of the thermogravimetric analysis measurement of the ionic liquid of the comparative example 1. It is a result of the thermogravimetric analysis measurement of the ionic liquid composition of Example 1.

Claims (8)

  An ionic liquid composition comprising an ionic liquid comprising a cation part and an anion part, wherein the ionic liquid is an ionic liquid (A) having a halogen atom in the anion part, the ionic liquid (A), a neutral salt and An ionic liquid composition comprising at least one compound (B) selected from the group consisting of basic compounds.   The anion part having a halogen atom of the ionic liquid (A) is at least one selected from the group consisting of bis (fluorosulfonyl) imide, bis (trifluoromethanesulfonyl) imide, hexafluorophosphate and tetrafluoroborate. Item 5. An ionic liquid composition according to Item 1.   The cation part of the ionic liquid (A) is at least one selected from the group consisting of imidazolium cation, pyridinium cation, quaternary ammonium cation, quaternary phosphonium cation, pyrrolidinium cation and piperidinium cation. The ionic liquid composition according to claim 1 or 2.   The ionic liquid composition according to any one of claims 1 to 3, wherein the basic compound selected from the compound (B) is a basic phosphate.   The ionic liquid composition according to any one of claims 1 to 3, wherein the basic compound selected from the compound (B) is a tertiary amine compound.   The ionic liquid composition according to any one of claims 1 to 3, wherein the neutral salt selected from the compound (B) is at least one selected from the group consisting of potassium fluoride and potassium chloride.   The compounding quantity of the said compound (B) is the range of 0.001-10 weight part with respect to 100 weight part of ionic liquid (A), The ionic liquid composition as described in any one of Claims 1-6. .   A synthetic lubricating oil comprising the ionic liquid composition according to any one of claims 1 to 7.

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