EP4621033A1

EP4621033A1 - Anti-wear agent

Info

Publication number: EP4621033A1
Application number: EP23891540.9A
Authority: EP
Inventors: Yusuke Nakanishi; Yukio Yoshida; Shizuka Agano
Original assignee: Idemitsu Kosan Co Ltd
Current assignee: Idemitsu Kosan Co Ltd
Priority date: 2022-11-16
Filing date: 2023-11-13
Publication date: 2025-09-24
Also published as: JP2024072503A; CN120112619A; WO2024106393A1

Abstract

Provided is an anti-wear agent, which includes one or more kinds selected from compounds each represented by the following general formula (B1), and is excellent in wear resistance and maintenance of its anti-rust property. In the general formula (B1), respective symbols represent the following: R^B1 represents an alkyl group having 1 to 9 carbon atoms; R^B2 represents an alkyl group having 1 to 9 carbon atoms; R^B3 represents an alkyl group having 1 to 9 carbon atoms; R^B4 represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms; R represents an alkyl group having 1 to 3 carbon atoms; Y represents a methylene group or an oxygen atom; n1 represents 1 or 2; and when n1 represents 1, "m" represents an integer of from 0 to 8, and when n1 represents 2, "m" represents an integer of from 0 to 10.

Description

Technical Field

The present invention relates to an anti-wear agent.

Background Art

An ionic liquid such as a pyrrolidinium-type ionic liquid has been known as the following base material: while the base material has a viscosity lower than that of a MAC oil (cyclopentane oil such as tris(2-octyldodecyl)cyclopentane) generally used as a base material for a space lubricant, the base material has both of excellent low volatility and excellent thermal stability. In view of the foregoing, it has been particularly desired that the ionic liquid be used as a base material for a long-life lubricant by exploiting its features, that is, the low volatility and the thermal stability. In addition, in order that the liquid may be used in a lubricant for a long time period, the liquid needs to be excellent in wear resistance and anti-rust property.
However, the kinds of additives that may be used in the ionic liquid are limited because the properties of the liquid largely differ from those of, for example, a mineral oil or a synthetic oil generally used as a base material for a lubricant. Accordingly, an additive to be blended into a lubricant composition using the ionic liquid as a base material desirably has a plurality of characteristics.
In this connection, an imidazolium-type phosphate compound whose cation has an imidazolium structure has been known as an additive to be blended into the ionic liquid (see, for example, PTL 1 and PTL 2).

Citation List

Patent Literature

PTL 1: JP 2011-174050 A
PTL 2: JP 2014-98053 A

Summary of Invention

Technical Problem

However, the inventors of the present invention have made an investigation, and as a result, have found that the imidazolium-type phosphate compound has a problem in that the compound has high metal corrosiveness, and is hence remarkably poor in anti-rust property, though the compound is excellent in wear resistance.
In addition, in each of PTL 1 and PTL 2, a lubricant composition containing the imidazolium-type phosphate compound has been evaluated for its wear resistance and anti-rust property. However, only the presence or absence of the occurrence of rust immediately after a test has been evaluated, and no reference has been made to an anti-rust property after the compound has been left for a long time period.
It is important that the effect of an anti-rust property be maintained for a long time period because rust generally occurs on the surface of a metal after the metal has been left for a long time period. Accordingly, an anti-rust property evaluation performed only immediately after a test is insufficient.
The present invention has been made in view of the problems, and an object of the present invention is to provide an anti-wear agent excellent in wear resistance and maintenance of its anti-rust property.

Solution to Problem

The inventors of the present invention have made extensive investigations, and as a result, have found that a specific anti-wear agent can solve the problems. Thus, the inventors have completed the present invention.
That is, the present invention provides the following item [1].

[1] An anti-wear agent, including one or more kinds selected from compounds each represented by the following general formula (B1): wherein
in the general formula (B1), respective symbols represent the following:
- R^B1 represents an alkyl group having 1 to 9 carbon atoms;
- R^B2 represents an alkyl group having 1 to 9 carbon atoms;
- R^B3 represents an alkyl group having 1 to 9 carbon atoms;
- R^B4 represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms;
- R represents an alkyl group having 1 to 3 carbon atoms;
- Y represents a methylene group or an oxygen atom;
- n1 represents 1 or 2; and
- when n1 represents 1, "m" represents an integer of from 0 to 8, and when n1 represents 2, "m" represents an integer of from 0 to 10.

Advantageous Effects of Invention

According to the present invention, the anti-wear agent excellent in wear resistance and maintenance of its anti-rust property can be provided.

Description of Embodiments

The upper limit values and lower limit values of numerical ranges described herein may be arbitrarily combined. For example, when the range of "from A to B" and the range of "from C to D" are described as numerical ranges, the numerical range of "from A to D" and the numerical range of "from C to B" are also included in the scope of the present invention.
In addition, the numerical range of "from a lower limit value to an upper limit value" described herein means that a physical property value is "the lower limit value or more and the upper limit value or less" unless otherwise stated.
In addition, in this description, the numerical values of Examples are numerical values that may each be used as an upper limit value or a lower limit value.

[Anti-wear Agent]

An anti-wear agent according to an embodiment of the present invention is an anti-wear agent including one or more kinds selected from compounds each represented by the following general formula (B1): wherein
in the general formula (B1), respective symbols represent the following:

R^B1 represents an alkyl group having 1 to 9 carbon atoms;
R^B2 represents an alkyl group having 1 to 9 carbon atoms;
R^B3 represents an alkyl group having 1 to 9 carbon atoms;
R^B4 represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms;
R represents an alkyl group having 1 to 3 carbon atoms;
Y represents a methylene group or an oxygen atom;
n1 represents 1 or 2; and
when n1 represents 1, "m" represents an integer of from 0 to 8, and when n1 represents 2, "m" represents an integer of from 0 to 10.

The inventors of the present invention have made extensive investigations with a view to solving the problems.
As a result, the inventors have found that when a pyrrolidinium-type ionic liquid is used, the preparation of an anti-wear agent including a pyrrolidinium-type phosphate compound whose cation moiety has a structure similar to that of the ionic liquid can suppress a reduction in anti-rust property after the lapse of a long time period. In addition, the inventors have found that the optimization of the carbon chain length of an alkyl group of a phosphate serving as the anion moiety of the compound provides excellent wear resistance.
The inventors have completed the present invention on the basis of those findings.
R^B1 in the general formula (B1) represents an alkyl group having 1 to 9 carbon atoms, and the group has preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms. In addition, the alkyl group may be linear or branched.
When R^B1 represents an alkyl group having 1 to 9 carbon atoms, the wear resistance, anti-rust property, and thermal stability of the anti-wear agent become satisfactory.
R^B2 in the general formula (B1) represents an alkyl group having 1 to 9 carbon atoms, and the group has preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms. In addition, the alkyl group may be linear or branched.
When R^B2 represents an alkyl group having 1 to 9 carbon atoms, the anti-rust property and thermal stability of the anti-wear agent, and the solubility thereof in an ionic liquid become satisfactory. In addition, R^B2 may represent the same alkyl group as that represented by R^B1.
R^B3 in the general formula (B1) represents an alkyl group having 1 to 9 carbon atoms, and the group has preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms. In addition, the alkyl group may be linear or branched.
When R^B3 represents an alkyl group having 1 to 9 carbon atoms, the anti-rust property, thermal stability, and wear resistance of the anti-wear agent, and the solubility thereof in an ionic liquid become satisfactory.
When the number of the carbon atoms of the alkyl group represented by R^B3 is 10 or more, the wear resistance of the anti-wear agent and the solubility thereof in an ionic liquid become insufficient.
R^B4 in the general formula (B1) represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms. When R^B4 represents an alkyl group, the group has preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms. When R^B4 represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms, the wear resistance and thermal stability of the anti-wear agent become satisfactory. In addition, the alkyl group may be linear or branched.
When the number of the carbon atoms of the alkyl group represented by R^B4 is 10 or more, the wear resistance and the thermal stability become insufficient.
Although R^B2, R^B3, and R^B4 in the general formula (B1) may represent the same alkyl group or different alkyl groups, the symbols preferably represent the same alkyl group from the viewpoint of synthesis.
The groups represented by R^B1, R^B2, R^B3, and R^B4 in the general formula (B1) each have preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms.
R in the general formula (B1) represents an alkyl group having 1 to 3 carbon atoms, and the number of its carbon atoms is preferably 1. In addition, the alkyl group may be linear or branched.
Y in the general formula (B1) represents a methylene group or an oxygen atom, preferably a methylene group.
n1 in the general formula (B1) represents 1 or 2, preferably 1.
When n1 in the general formula (B1) represents 1, "m" represents an integer of from 0 to 8, preferably 0. When n1 represents 2, "m" represents an integer of from 0 to 10, preferably 0.
In the general formula (B1), the total of the number of the carbon atoms of the alkyl group represented by R^B1 and the number of the carbon atoms of the alkyl group represented by R^B2 is not particularly limited. However, the total is preferably 6 or less.
When the total of the number of the carbon atoms of the alkyl group represented by R^B1 and the number of the carbon atoms of the alkyl group represented by R^B2 is 6 or less, the anti-wear agent is easily improved in wear resistance, and is excellent in thermal stability.
The compound represented by the general formula (B1) is a salt structure containing a cation and an anion. The foregoing shows that the compound is excellent in solubility in an ionic liquid and low volatility.
The anti-wear agent of this embodiment is excellent not only in wear resistance but also in maintenance of its anti-rust property.
In the anti-wear agent of this embodiment, rust means a "product produced as a result of the advance of a corrosion phenomenon in a metal brought into contact with an ionic liquid."
The inventors of the present invention have made investigations, and as a result, have found that the rust tends to occur in a portion brought into contact with the ionic liquid on the surface of the metal (boundary surface between the ionic liquid and the metal).
This is probably because the ionic liquid contains a cation and an anion, and hence the occurrence of the rust is accelerated by the ionic conductivity of the ionic liquid.
In view of the foregoing, the inventors of the present invention have assumed that the preparation of an anti-wear agent including a pyrrolidinium-type phosphate compound whose cation moiety has a structure similar to that of the ionic liquid suppresses a reduction in anti-rust property after the lapse of a long time period.
The anti-wear agent of this embodiment can maintain its anti-rust property, by which the occurrence of rust is suppressed, for a long time period.
With regard to the anti-rust property in the anti-wear agent of this embodiment, a state in which "no rust occurs" is evaluated as a desirable state.
The compound represented by the general formula (B1) may be obtained by, for example, ionizing an alkyl pyrrolidine and a trialkyl phosphate to synthesize the compound represented by the general formula (B 1).
When R^B2, R^B3, and R^B4 in the general formula (B1) represent the same alkyl group, the compound is easy to synthesize because the alkyl group can undergo rearrangement from a triester in the phosphate serving as an anion to produce an alkyl group of pyrrolidinium serving as a cation.
Although the anti-wear agent of this embodiment may be formed only of the one or more kinds selected from the compounds each represented by the general formula (B1), the agent may include any other component except the compound, or may be free of the component.
The content of the one or more kinds selected from the compounds each represented by the general formula (B 1) in the anti-wear agent of this embodiment is preferably from 50 mass% to 100 mass%, more preferably from 60 mass% to 100 mass%, still more preferably from 70 mass% to 100 mass%, still further more preferably from 80 mass% to 100 mass%, yet still further more preferably from 90 mass% to 100 mass%, even more preferably from 95 mass% to 100 mass%, still even more preferably from 98 mass% to 100 mass% with respect to the total amount of the anti-wear agent.

(Ionic Liquid)

The anti-wear agent of this embodiment is preferably used together with an ionic liquid.
When the anti-wear agent is used together with the ionic liquid, the agent may be used in, for example, a lubricant composition using the ionic liquid as a base material.
The ionic liquid is a liquid compound including a cation and an anion, and various compounds that are free of metal contents may each be adopted.
The compound represented by the general formula (B1) is not included in the ionic liquid.
The ionic liquid preferably contains, as its anion, bis(trifluoromethanesulfonyl)imide.
The ionic liquid preferably contains, as its cation, a cation represented by the following general formula (A1): wherein
in the general formula (A1), respective symbols represent the following:

n2 represents 1 or 2;
X represents a methylene group or an oxygen atom; and
R^A11 and R^A12 each independently represent an alkyl group having 1 to 12 carbon atoms that may have one or more kinds of groups selected from an ether group, an ester group, a nitrile group, and a silyl group.

From the viewpoints of reducing the viscosity of the ionic liquid and improving the thermal stability thereof, the number of the carbon atoms of the alkyl group represented by each of R^A11 and R^A12 in the general formula (A1) is preferably from 1 to 6, more preferably from 1 to 4.
R^A11 preferably represents a methyl group. In addition, R^A12 preferably represents a n-butyl group or a methoxyethyl group.
Examples of the cation represented by the general formula (A1) include 1-butyl-1-methylpyrrolidinium, 1-pentyl-1-methylpyrrolidinium, 1-hexyl-1-methylpyrrolidinium, 1-heptyl-1methylpyrrolidinium, 1-octyl-1-methylpyrrolidinium, 1-nonyl-1-methylpyrrolidinium, 1-decyl-1-methylpyrrolidinium, 1-undecyl-1-methylpyrrolidinium, 1-dodecyl-1-methylpyrrolidinium, 1-methoxymethyl-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-methoxymethyl-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-methoxymethyl-1-methylmorpholinium, 1-(2-methoxy-2-oxoethyl)-1-methylmorpholinium, 1-cyanomethyl-1-methylmorpholinium, and 1-trimethylsilylmethyl-1-methylmorpholinium.
Among them, 1-butyl-1-methylpyrrolidinium, 1-pentyl-1-methylpyrrolidinium, 1-hexyl-1-methylpyrrolidinium, 1-(2-methoxyethyl)-1-methylpyrrolidinium, 1-butyl-1-methylpiperidinium, 1-(2-methoxyethyl)-1-methylpiperidinium, and 1-(2-methoxyethyl)-1-methylmorpholinium are preferred, 1-butyl-1-methylpyrrolidinium, 1-(2-methoxyethyl)-1-methylpyrrolidinium, and 1-(2-methoxyethyl)-1-methylpiperidinium are more preferred, and 1-butyl-1-methylpyrrolidinium and 1-(2-methoxyethyl)-1-methylpyrrolidinium are still more preferred from the viewpoints of reducing the viscosity of the ionic liquid and improving the thermal stability thereof.
The ionic liquid preferably contains at least one kind selected from a compound represented by the following general formula (A2) and a compound represented by the following general formula (A3): wherein
in the general formula (A2), respective symbols represent the following:

n3 represents 1 or 2;
X represents a methylene group or an oxygen atom; and
R^A21 represents an alkyl group having 2 to 12 carbon atoms;

n4 represents 1 or 2;
X represents a methylene group or an oxygen atom;
R^A31 represents an alkylene group having 1 to 5 carbon atoms; and
R^A32 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

In the general formula (A2), the number of the carbon atoms of R^A21 is preferably from 2 to 8, more preferably from 3 to 6. When the number of the carbon atoms of R^A21 is 2 or more, a side chain of the compound can freely move, and the symmetry thereof reduces. Accordingly, the crystallization thereof is suppressed, and hence the function thereof as an ionic liquid can be improved. When the number of the carbon atoms of R^A21 is 12 or less, the side chain does not become excessively large, and hence the ionicity of the entirety of the compound is high. Accordingly, the oxidative degradation thereof is easily suppressed.
In the general formula (A3), the number of the carbon atoms of R^A31 is preferably from 1 to 3, more preferably 1 or 2. In addition, the number of the carbon atoms of R^A32 is preferably 1 or 2. When the number of the carbon atoms of R^A31 is 1 or more, a side chain of the compound can freely move, and the symmetry thereof reduces. Accordingly, the crystallization thereof is suppressed, and hence the function thereof as an ionic liquid can be improved. When the number of the carbon atoms of R^A31 is 5 or less, or the number of the carbon atoms of R^A32 is 3 or less, the side chain does not become excessively large, and hence the ionicity of the entirety of the compound is high. Accordingly, the oxidative degradation thereof is easily suppressed.
The content of the compound represented by the general formula (A2) in the ionic liquid is preferably from 60 mass% to 100 mass%, more preferably from 70 mass% to 100 mass%, still more preferably from 80 mass% to 100 mass% with respect to the total amount of the ionic liquid.
In addition, the content of the compound represented by the general formula (A3) in the ionic liquid is preferably from 60 mass% to 100 mass%, more preferably from 70 mass% to 100 mass%, still more preferably from 80 mass% to 100 mass% with respect to the total amount of the ionic liquid.
One or more kinds selected from the compounds each represented by the general formula (A2) may be used as the ionic liquid, or one or more kinds selected from the compounds each represented by the general formula (A3) may be used. One or more kinds selected from the compounds each represented by the general formula (A2), and one or more kinds selected from the compounds each represented by the general formula (A3) may be used in combination.
In the lubricant composition, the content of the ionic liquid is not particularly limited. However, from, for example, the viewpoint of improving the effect of the present invention, the content is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, still further more preferably 80 mass% or more, yet still further more preferably 85 mass% or more with respect to the total amount (100 mass%) of the lubricant composition.
The upper limit value of the content of the ionic liquid is appropriately set in accordance with the addition amount of a component except the ionic liquid, and is preferably 99.8 mass% or less, more preferably 99.7 mass% or less, still more preferably 99.5 mass% or less, still further more preferably 99.0 mass% or less, yet still further more preferably 98.5 mass% or less.
The upper limit values and lower limit values of those numerical ranges may be arbitrarily combined. Specifically, the content is preferably from 50 mass% to 100 mass%, more preferably from 60 mass% to 100 mass%, still more preferably from 70 mass% to 100 mass%, still further more preferably from 90 mass% to 100 mass%, yet still further more preferably from 95 mass% to 100 mass%.
A base material component except the above-mentioned ionic liquid (e.g., a base material component that does not correspond to the ionic liquid such as ethyl acetate) may be incorporated as a base material into the lubricant composition. From, for example, the viewpoint of improving the effect of the present invention, the content of the above-mentioned ionic liquid is preferably 50 mass% or more, more preferably 70 mass% or more, still more preferably 90 mass% or more, still further more preferably 100 mass% with respect to the total amount of the base material.
The ratio (B/A) of the content B of the compound represented by the general formula (B1) to the content A of the ionic liquid is preferably 0.0005 or more and 0.15 or less, more preferably 0.001 or more and 0.111 or less, still more preferably 0.003 or more and 0.08 or less in terms of mass ratio. When the ratio (B/A) is 0.0005 or more, the anti-rust property of the composition is easily made sufficient. When the ratio (B/A) is 0.15 or less, the solubility of the compound represented by the general formula (B1) in the ionic liquid is easily made sufficient.
The lubricant composition may contain any other component except the anti-wear agent of this embodiment as required to the extent that the effect of the present invention is not impaired.
Examples of the other component include: a by-product produced in a synthesis process for the compound represented by the general formula (B1); and an unreacted raw material and a diluent remaining in the synthesis process for the compound represented by the general formula (B1). In addition, the examples of the other component except the anti-wear agent of this embodiment include: an additive such as a viscosity index improver; and a thickener.
Those components may be used alone or in combination thereof.

When the wear resistance of the compound represented by the general formula (B1) is evaluated by a method described in Examples, the wear width thereof is preferably 250 µm or less, more preferably 230 µm or less, still more preferably 200 µm or less.

When the anti-rust property of the compound represented by the general formula (B 1) is evaluated by a method described in Examples to be described later, it is preferred that no reddish brown or black color change (rust) be observed on a surface.

[Applications of Anti-wear Agent]

The anti-wear agent of this embodiment is excellent not only in wear resistance but also in maintenance of its anti-rust property. Accordingly, the agent may be blended into a lubricant composition that is required to have a high anti-rust property.
The lubricant composition is, for example, a lubricant composition that lubricates, for example, a production apparatus for an instrument to be mounted on an apparatus to be used in an outer space, a semiconductor, a liquid crystal or organic EL flat panel display, a solar panel, or the like. However, the composition is applicable to other applications.
Accordingly, the anti-wear agent according to this embodiment provides the following (1) and (2):

(1) a method of suppressing wear with the anti-wear agent according to this embodiment; and
(2) the use of the anti-wear agent according to this embodiment for the lubrication of at least one of: an instrument to be mounted on an apparatus to be used in an outer space; a semiconductor; a liquid crystal or organic EL flat panel display; and a solar panel.

[One Aspect of the Present Invention to be provided]

In one aspect of the present invention, there are provided the following items [1] to [5].

[1] An anti-wear agent, including one or more kinds selected from compounds each represented by the following general formula (B1): wherein
in the general formula (B1), respective symbols represent the following:
- R^B1 represents an alkyl group having 1 to 9 carbon atoms;
- R^B2 represents an alkyl group having 1 to 9 carbon atoms;
- R^B3 represents an alkyl group having 1 to 9 carbon atoms;
- R^B4 represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms;
- R represents an alkyl group having 1 to 3 carbon atoms;
- Y represents a methylene group or an oxygen atom;
- n1 represents 1 or 2; and
- when n1 represents 1, "m" represents an integer of from 0 to 8, and when n1 represents 2, "m" represents an integer of from 0 to 10.
[2] The anti-wear agent according to the above-mentioned item [1], wherein a total of the number of carbon atoms of the alkyl group represented by R^B1 and the number of carbon atoms of the alkyl group represented by R^B2 is 6 or less.
[3] The anti-wear agent according to the above-mentioned item [1] or [2], wherein the anti-wear agent is used together with an ionic liquid.
[4] The anti-wear agent according to the above-mentioned item [3], wherein the ionic liquid contains a cation represented by the following general formula (A1): wherein
in the general formula (A1), respective symbols represent the following:
- n2 represents 1 or 2;
- X represents a methylene group or an oxygen atom; and
- R^A11 and R^A12 each independently represent an alkyl group having 1 to 12 carbon atoms that may have one or more kinds of groups selected from an ether group, an ester group, a nitrile group, and a silyl group.
[5] The anti-wear agent according to the above-mentioned item [3] or [4], wherein the ionic liquid contains at least one kind selected from a compound represented by the following general formula (A2) and a compound represented by the following general formula (A3): wherein
in the general formula (A2), respective symbols represent the following:
- n3 represents 1 or 2;
- X represents a methylene group or an oxygen atom; and
- R^A21 represents an alkyl group having 2 to 12 carbon atoms;
wherein
in the general formula (A3), respective symbols represent the following:
- n4 represents 1 or 2;
- X represents a methylene group or an oxygen atom;
- R^A31 represents an alkylene group having 1 to 5 carbon atoms; and
- R^A32 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

Examples

The present invention is specifically described by way of Examples below. However, the present invention is not limited to Examples below.

[Production Examples 1 to 4, Comparative Production Examples 1 and 2, and Comparative Compounds 1, 2, and 5]

Compounds 1 to 4, and Comparative Compounds 3 and 4 were synthesized by methods described in Production Examples 1 to 4, and Comparative Production Examples 1 and 2. In addition, Comparative Compounds 1, 2, and 5 were prepared.

First, 10 g (117 mmol) of N-methylpyrrolidine and 13 g (71 mmol) of triethyl phosphate were loaded into a Schlenk tube under a nitrogen atmosphere, and were heated at 80°C for 40 hours. Next, the resultant product was washed with 20 mL of ethyl acetate four times. Ethyl acetate in the resultant ionic liquid layer was removed from the layer by drying under reduced pressure. Thus, 3.7 g (14 mmol) of Compound 1 was obtained. The product was identified by ¹H-NMR (DMSO solvent).
The structural formula of Compound 1 is shown below.
Compound 1 is such a compound that the respective symbols in the general formula (B1) represent the following:

R^B1 represents a methyl group having 1 carbon atom;
R^B2, R^B3, and R^B4 each represent an ethyl group having 2 carbon atoms;
Y represents a methylene group;
"n" represents 1; and
"m" represents 0.

First, 10 g (117 mmol) of N-methylpyrrolidine and 5 g (36 mmol) of trimethyl phosphate were loaded into a Schlenk tube under a nitrogen atmosphere, and were heated at 80°C for 4 hours. Next, the resultant product was washed with 20 mL of ethyl acetate four times. Ethyl acetate in the resultant ionic liquid layer was removed from the layer by drying under reduced pressure. Thus, 6.1 g (27 mmol) of Compound 2 was obtained. The product was identified by ¹H-NMR (DMSO solvent).
The structural formula of Compound 2 is shown below.
Compound 2 is such a compound that the respective symbols in the general formula (B1) represent the following:

R^B1, R^B2, R^B3, and R^B4 each represent a methyl group having 1 carbon atom;
Y represents a methylene group;
"n" represents 1; and
"m" represents 0.

First, 11 g (86 mmol) of N-butylpyrrolidine and 10 g (55 mmol) of triethyl phosphate were loaded into a Schlenk tube under a nitrogen atmosphere, and were heated at 150°C for 20 hours. Next, the resultant product was washed with 20 mL of diethyl ether four times. Diethyl ether in the resultant ionic liquid layer was removed from the layer by drying under reduced pressure. Thus, 14 g (47 mmol) of Compound 3 was obtained. The product was identified by ¹H-NMR (DMSO solvent).
The structural formula of Compound 3 is shown below.
Compound 3 is such a compound that the respective symbols in the general formula (B1) represent the following:

R^B1 represents a n-butyl group having 4 carbon atoms;
R^B2, R^B3, and R^B4 each represent an ethyl group having 2 carbon atoms;
Y represents a methylene group;
"n" represents 1; and
"m" represents 0.

First, 11 g (86 mmol) of N-butylpyrrolidine and 7.7 g (55 mmol) of trimethyl phosphate were loaded into a Schlenk tube under a nitrogen atmosphere, and were heated at 120°C for 4 hours. Next, the resultant product was washed with 20 mL of diethyl ether four times. Diethyl ether in the resultant ionic liquid layer was removed from the layer by drying under reduced pressure. Thus, 11 g (42 mmol) of Compound 4 was obtained. The product was identified by ¹H-NMR (DMSO solvent).
The structural formula of Compound 4 is shown below.
Compound 4 is such a compound that the respective symbols in the general formula (B1) represent the following:

R^B1 represents a n-butyl group having 4 carbon atoms;
R^B2, R^B3, and R^B4 each represent a methyl group having 1 carbon atom;
Y represents a methylene group;
"n" represents 1; and
"m" represents 0.

1-Butyl-3-methylimidazolium dibutyl phosphate (manufactured by Tokyo Chemical Industry Co., Ltd.) was prepared as Comparative Compound 1.
The structural formula of Comparative Compound 1 is shown below.

1,3-Dimethylimidazolium dimethyl phosphate (manufactured by FUJIFILM Wako Pure Chemical Corporation) was prepared as Comparative Compound 2.
The structural formula of Comparative Compound 2 is shown below.

First, 2.0 g (5.0 mmol) of sodium didecyl phosphate, 1.1 g (5.0 mmol) of N,N-butylmethylpyrrolidinium bromide, 10 mL of ion-exchanged water, and 10 mL of methanol were loaded into a recovery flask, and were stirred at room temperature for 1 hour. 20 Milliliters of dichloromethane was added to the mixture, and then the whole was washed with 10 mL of ion-exchanged water three times. Thus, 0.21 g (0.4 mmol) of Comparative Compound 3 was obtained.
The structural formula of Comparative Compound 3 is shown below.

First, 5.0 g (7.2 mmol) of a 40% aqueous solution of tetrabutylphosphonium hydroxide and 1.5 g (7.2 mmol) of dibutyl phosphate were loaded into a recovery flask, and were stirred at room temperature for 1 hour. Next, moisture was removed with an evaporator. Thus, 3.2 g (6.8 mmol) of Comparative Compound 4 was obtained.
The structural formula of Comparative Compound 4 is shown below.

Potassium di-tert-butyl phosphate (manufactured by Tokyo Chemical Industry Co., Ltd.) was prepared as Comparative Compound 5.
The structural formula of Comparative Compound 5 is shown below.

[Examples 1 to 5 and Comparative Examples 1 to 6]

N-(2-Methoxyethyl)-N-methylpyrrolidinium-bis(trifluoromethanesulfonyl)imide was used as an ionic liquid.
Then, as shown in Table 1, lubricant compositions were prepared by blending Compounds 1 to 4 serving as anti-wear agents in Examples 1 to 5, and blending Comparative Compounds 1 to 5 serving as anti-wear agents in Comparative Examples 1 to 6, followed by the following evaluations.
The results are shown in Table 1.

The wear width of an upper ball at the time of the use of each of the prepared lubricant compositions was measured with a Bowden-type reciprocating friction tester (manufactured by Orientec Corporation) under the following conditions. When the wear width was 250 µm or less, it was judged that the wear resistance of the composition was satisfactory.

·Test piece: upper ball (SUJ2), lower disc (SUJ2)
·Speed: 15 mm/sec
·Sliding width: 15 mm
·Load: 20 N
·Temperature: 100°C
·Number of times of sliding: 3,000 times

5 Grams of distilled water and 5 g of each of the lubricant compositions were loaded into a sample bottle having a volume of 10 mL. Then, a SUS440C plate cut into a strip shape (measuring 51 mm long by 13 mm wide by 3.0 mm thick) was loaded into the bottle, and was left at rest at room temperature for 14 days. After that, the appearance of the SUS440C plate was observed, and the anti-rust property of the composition was judged as described below.

A: No reddish brown or black color change (rust) was observed on the surface of the plate.
B: A reddish brown or black color change (rust) was observed on the surface.

[Table 1]

Table 1

			Example					Comparative Example
			1	2	3	4	5	1	2	3	4	5	6
Ionic liquid		mass%	99.7	99.5	99.7	99.7	99.7	99.7	99.5	99.7	99.5	99.7	99.7
	Compound 1	mass%	0.3	0.5	-	-	-	-	-	-	-	-	-
	Compound 2	mass%	-	-	0.3	-	-	-	-	-	-	-	-
	Compound 3	mass%	-	-	-	0.3	-	-	-	-	-	-	-
	Compound 4	mass%	-	-	-	-	0.3	-	-	-	-	-	-
Anti-wear agent	Comparative Compound 1	mass%	-	-	-	-	-	0.3	0.5	-	-	-	-
	Comparative Compound 2	mass%	-	-	-	-	-	-	-	0.3	-	-	-
	Comparative Compound 3	mass%	-	-	-	-	-	-	-	-	0.5	-	-
	Comparative Compound 4	mass%	-	-	-	-	-	-	-	-	-	0.3	-
	Comparative Compound 5	mass%	-	-	-	-	-	-	-	-	-	-	0.3
Total		mass%	100	100	100	100	100	100	100	100	100	100	100
Evaluation Result	Wear resistance	µm	178	179	178	177	180	176	177	178	541	211	Insoluble
Evaluation Result	Maintenance of anti-rust property	-	A	A	A	A	A	B	B	B	A	B	Insoluble

The following is found from Table 1.
It is found that Examples 1 to 5 containing Compounds 1 to 4 serving as anti-wear agents are each excellent in wear resistance because the wear widths are 250 µm or less. In addition, the following results were obtained: Examples 1 to 5 were each also excellent in maintenance of its anti-rust property.
Meanwhile, the following results were obtained: Comparative Examples 1 to 5 containing Comparative Compounds 1 to 4 serving as anti-wear agents were each poor in at least one of wear resistance or maintenance of its anti-rust property. Specifically, in Comparative Example 4, the wear width was much more than 250 µm, and hence the wear resistance was extremely insufficient. In addition, the following results were obtained: Comparative Examples 1 to 3 and Comparative Example 5 were each poor in maintenance of the anti-rust property. In addition, in Comparative Example 6, the wear resistance and the maintenance of the anti-rust property were not able to be evaluated because Comparative Compound 5 was not dissolved in the ionic liquid.

Claims

An anti-wear agent, comprising one or more kinds selected from compounds each represented by the following general formula (B1): wherein
in the general formula (B1), respective symbols represent the following:
R^B1 represents an alkyl group having 1 to 9 carbon atoms;

R^B2 represents an alkyl group having 1 to 9 carbon atoms;

R^B3 represents an alkyl group having 1 to 9 carbon atoms;

R^B4 represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms;

R represents an alkyl group having 1 to 3 carbon atoms;

Y represents a methylene group or an oxygen atom;

n1 represents 1 or 2; and

when n1 represents 1, "m" represents an integer of from 0 to 8, and when n1 represents 2, "m" represents an integer of from 0 to 10.
The anti-wear agent according to claim 1, wherein a total of the number of carbon atoms of the alkyl group represented by R^B1 and the number of carbon atoms of the alkyl group represented by R^B2 is 6 or less.
The anti-wear agent according to claim 1 or 2, wherein the anti-wear agent is used together with an ionic liquid.
The anti-wear agent according to claim 3, wherein the ionic liquid comprises a cation represented by the following general formula (A1): wherein
in the general formula (A1), respective symbols represent the following:
n2 represents 1 or 2;

X represents a methylene group or an oxygen atom; and

R^A11 and R^A12 each independently represent an alkyl group having 1 to 12 carbon atoms that may have one or more kinds of groups selected from an ether group, an ester group, a nitrile group, and a silyl group.
The anti-wear agent according to claim 3 or 4, wherein the ionic liquid comprises at least one kind selected from a compound represented by the following general formula (A2) and a compound represented by the following general formula (A3): wherein in the general formula (A2), respective symbols represent the following:
n3 represents 1 or 2;

X represents a methylene group or an oxygen atom; and

R^A21 represents an alkyl group having 2 to 12 carbon atoms;
wherein
in the general formula (A3), respective symbols represent the following:
n4 represents 1 or 2;

X represents a methylene group or an oxygen atom;

R^A31 represents an alkylene group having 1 to 5 carbon atoms; and

R^A32 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.