JP2017197716A - Conductive lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive lubricant composition excellent in temporal stability of conductivity.SOLUTION: A conductive lubricant composition contains at least one lubricant base oil selected from the group consisting of fatty acid monoester base oil and ether ester base oil, and 0.01-1 mass% of at least one conductivity imparting agent selected from the group consisting of potassium trifluoromethane sulfonate, lithium trifluoromethane sulfonate, lithium nonafluorobutane sulfonate, bis(trifluoromethanesulfonyl)imide lithium, bis(trifluoromethanesulfonyl)imide potassium, and tris(trifluoromethanesulfonyl)methide lithium, where a change ratio of conductivity after the conductive lubricant composition has been stored at 120°C for 200 hours is 10% or less.SELECTED DRAWING: None

Description

  The present invention relates to a conductive lubricating oil composition.

  In recent years, precision devices such as personal computers and other peripheral devices have been advanced and miniaturized. The lubricating oil composition used for such a high-speed rotating part of a precision instrument may be required to have conductivity in order to suppress static charge generated by friction of the high-speed rotating part. Examples of the lubricating oil composition imparted with conductivity include conductive lubricants for hydrodynamic bearings including ester base oils and anionic, cationic, amphoteric or nonionic antistatic agents. It has been proposed (see, for example, Patent Document 1).

JP 2001-115180 A

  However, when nonionic (nonionic) and ionic (anionic, cationic, amphoteric) antistatic agents are used, the conductivity of the lubricating oil composition depends on the amount of water contained in the lubricating oil composition. There are problems such as fluctuating sex. Furthermore, depending on the type of antistatic agent, the stability at high temperature is insufficient, and there is a problem that the conductivity varies greatly when the lubricating oil composition is used for a long period of time.

  This invention is made | formed in view of the above situations, and makes it a subject to provide the electroconductive lubricating oil composition excellent in electroaging stability.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors combined a specific base oil and a specific conductivity-imparting agent to suppress a change in conductivity, and were stable for a long time. The present inventors have found that a conductive lubricating oil composition can be obtained and completed the present invention. That is, the present invention is as follows.

<1> At least one lubricating base oil selected from the group consisting of fatty acid monoester base oils and ether ester base oils, potassium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, bis ( At least one conductivity-imparting agent selected from the group consisting of trifluoromethanesulfonyl) imide lithium, bis (trifluoromethanesulfonyl) imide potassium, and tris (trifluoromethanesulfonyl) methide lithium is 0.01 to 1% by mass, and a conductive lubricating oil composition having a change rate of conductivity of 10% or less after storage at 120 ° C. for 200 hours.

<2> Further, at least one antioxidant selected from the group consisting of a diphenylamine compound, an alkylated phenyl-α-naphthylamine, a hindered phenol compound, and a phosphite is 0.05 to 2 with respect to the total mass of the composition. The conductive lubricating oil composition according to <1>, which is contained by mass%.

<3> The lubricating base oil according to <1> or <2>, wherein the lubricating base oil is a compound represented by any one of the following general formula (1), general formula (2), or general formula (3). A conductive lubricating oil composition.

[In General Formula (1), R ¹ represents a linear or branched alkyl group having 8 to 16 carbon atoms or a heteroalkyl group containing an oxygen atom, and n represents an integer of 5 to 11. ]

[In General Formula (2), R ² represents a linear or branched alkyl group having 8 to 16 carbon atoms or a heteroalkyl group containing an oxygen atom, and n represents an integer of 5 to 11. ]

[In General Formula (3), A ¹ represents a linear or branched alkylene group or heteroalkylene group having 8 to 15 carbon atoms, and R ³ and R ⁴ each independently represent 6 to 6 carbon atoms. 10 linear or branched alkyl groups are represented. ]

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive lubricating oil composition excellent in electroaging stability is provided.

  By using such a conductive lubricating oil composition for the sliding part and the rotating part of precision equipment, excellent lubricity can be achieved while ensuring the conductivity stably.

  Hereinafter, the conductive lubricating oil composition of the present invention will be described in detail. In addition, in this specification, "-" showing a numerical range represents the range containing the numerical value each described as the upper limit and the minimum. In addition, when only the upper limit value is described in the numerical range represented by “to”, it means that the lower limit value is also the same unit.

The conductive lubricating oil composition of the present invention comprises at least one lubricating base oil selected from the group consisting of fatty acid monoester base oils and ether ester base oils, potassium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, nona At least one conductivity-imparting agent selected from the group consisting of lithium fluorobutanesulfonate, bis (trifluoromethanesulfonyl) imide lithium, potassium bis (trifluoromethanesulfonyl) imide, and tris (trifluoromethanesulfonyl) methide lithium is 0.01 The rate of change in conductivity after storage at 120 ° C. for 200 hours is 10% or less.
The conductive lubricating oil composition of the present invention may contain components other than those described above as necessary.

  As a result of intensive studies to solve the above problems, the present inventors have found that at least one lubricating base oil selected from the group consisting of fatty acid monoester base oils and ether ester base oils, and potassium trifluoromethanesulfonate At least one selected from the group consisting of lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, lithium bis (trifluoromethanesulfonyl) imide, potassium bis (trifluoromethanesulfonyl) imide, lithium tris (trifluoromethanesulfonyl) methide In combination with the property-imparting agent, the present inventors have found that a conductive lubricating oil composition having excellent stability over time of conductivity is obtained, and the present invention has been completed. Hereinafter, the conductive lubricating oil composition of the present invention will be specifically described.

<Conductivity imparting agent>
The conductive lubricating oil composition of the present invention comprises potassium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, lithium bis (trifluoromethanesulfonyl) imide, potassium bis (trifluoromethanesulfonyl) imide, and tris. It contains 0.01 to 1% by mass of at least one conductivity imparting agent selected from the group consisting of (trifluoromethanesulfonyl) methide lithium.

  Among the conductivity imparting agents, lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, lithium bis (trifluoromethanesulfonyl) imide, or potassium bis (trifluoromethanesulfonyl) imide is preferable, lithium nonafluorobutanesulfonate, Bis (trifluoromethanesulfonyl) imide lithium or bis (trifluoromethanesulfonyl) imide potassium is more preferable, bis (trifluoromethanesulfonyl) imide lithium or bis (trifluoromethanesulfonyl) imide potassium is more preferable, and bis (trifluoromethanesulfonyl) imide lithium Is particularly preferred.

Content of an electroconductivity imparting agent is 0.01-1 mass% with respect to the composition total mass, and it is preferable to set it as 0.01-0.5 mass%, 0.01-0.1 mass% More preferably.
When the content of the conductivity imparting agent is 0.01% by mass or more, the conductivity of the lubricating oil composition is improved, and when it is 1% by mass or less, conductivity corresponding to the content can be imparted.
The conductivity imparting agent may be contained alone or in combination of two or more. As for the content when two or more kinds are contained in combination, the total amount is preferably within the above range.

<Lubricant base oil>
The conductive lubricating oil composition of the present invention contains at least one lubricating base oil selected from the group consisting of fatty acid monoester base oils and ether ester base oils.
In this specification, a fatty acid monoester base oil is a reaction product obtained by an esterification reaction of a monovalent alcohol and a monovalent carboxylic acid, and means an ester oil having 21 to 41 carbon atoms.
In the present specification, the ether ester base oil is a reaction product obtained by an esterification reaction of a monovalent or divalent alcohol and a monovalent carboxylic acid, and has 20 to 20 carbon atoms having at least one ether bond. Means 35 ester oils. The ether bond of the ester oil is introduced when at least one of a monovalent or divalent alcohol and a monovalent carboxylic acid is a compound having an ether bond.

  Examples of the lubricating base oil include compounds represented by the following general formula (1), general formula (2), or general formula (3).

In the general formula (1), R ¹ represents a linear or branched alkyl group having 8 to 16 carbon atoms or a heteroalkyl group containing an oxygen atom. The heteroalkyl group containing an oxygen atom represented by R ¹ may contain one oxygen atom or a plurality of oxygen atoms.
In general formula (1), n represents the integer of 5-11.

In the general formula (2), R ² represents a heteroalkyl group containing a linear or branched alkyl group or an oxygen atom of 8-16 carbon atoms. The heteroalkyl group containing an oxygen atom represented by R ² may contain one oxygen atom or a plurality of oxygen atoms.
In general formula (2), n represents the integer of 5-11.

In General Formula (3), A ¹ represents a linear or branched alkylene group or heteroalkylene group having 8 to 15 carbon atoms. The heteroalkylene group represented by A ¹ may contain one hetero atom or a plurality of hetero atoms. Examples of the hetero atom include an oxygen atom and a nitrogen atom.
In General Formula (3), R ³ and R ⁴ each independently represents a linear or branched alkyl group having 6 to 10 carbon atoms.

<Antioxidant>
The conductive lubricating oil composition of the present invention preferably contains at least one antioxidant.
Examples of the antioxidant include antioxidants such as diphenylamine compounds, alkylated phenyl-α-naphthylamines, hindered phenol compounds, and phosphites. From the viewpoint of maintaining a low rate of change in conductivity at a high temperature of the conductive lubricating oil composition, the above antioxidant is preferably used.

  As a diphenylamine compound, the compound represented by following General formula (4) is mentioned, for example.

In General Formula (4), R ⁵ and R ⁶ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 16 carbon atoms.
R ⁵ and R ⁶ may be the same or different.

Specific examples of the linear or branched alkyl group represented by R ⁵ and R ⁶ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-methylbutyl group, n-hexyl group, isohexyl group, 3-methylpentyl group, ethylbutyl group, n-heptyl group, 2-methylhexyl group, n -Octyl group, 2-ethylhexyl group, 3-methylheptyl group, n-nonyl group, methyloctyl group, ethylheptyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tetradecyl group, etc. It is done.

R ⁵ and R ⁶ are preferably a hydrogen atom or a linear or branched alkyl group having 3 to 9 carbon atoms, more preferably a hydrogen atom or a linear or branched alkyl group having 4 to 8 carbon atoms. is there.

  Said diphenylamine compound may be contained individually by 1 type, and 2 or more types may be combined and contained.

  Examples of the alkylated phenyl-α-naphthylamine include compounds represented by the following general formula (5).

In the general formula (5), R ⁷ represents a linear or branched alkyl group having 1 to 16 carbon atoms.

Specific examples of the linear or branched alkyl group represented by R ⁷ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, and an n-pentyl group. Group, isopentyl group, neopentyl group, tert-pentyl group, 2-methylbutyl group, n-hexyl group, isohexyl group, 3-methylpentyl group, ethylbutyl group, n-heptyl group, 2-methylhexyl group, n-octyl group 2-ethylhexyl group, 3-methylheptyl group, n-nonyl group, methyloctyl group, ethylheptyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tetradecyl group and the like.

R ⁷ is preferably a linear or branched alkyl group having 4 to 8 carbon atoms.

  The alkylated phenyl-α-naphthylamine may be contained singly or in combination of two or more.

  Examples of the hindered phenol compound include compounds represented by the following general formula (6), general formula (7), or general formula (8).

In General Formula (6), R ⁸ , R ⁹ , R ¹¹ , and R ¹² each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms.
R ⁸ , R ⁹ , R ¹¹ , and R ¹² may be the same or different.

Specific examples of the linear or branched alkyl group represented by R ⁸ , R ⁹ , R ¹¹ , and R ¹² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and isobutyl. Group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-methylbutyl group, n-hexyl group, isohexyl group, 3-methylpentyl group, ethylbutyl group, n-heptyl group, 2-methylhexyl group, n-octyl group, 2-ethylhexyl group, 3-methylheptyl group, n-nonyl group, methyloctyl group, ethylheptyl group, n-decyl group, n-undecyl group, n-dodecyl group, etc. Is mentioned.

R ⁸ , R ⁹ , R ¹¹ , and R ¹² are preferably a hydrogen atom or a linear or branched alkyl group having 4 to 8 carbon atoms.

In General Formula (6), R ¹⁰ represents an alkylene group having 1 to 5 carbon atoms.

Specific examples of the alkylene group represented by R ¹⁰ include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group.

R ¹⁰ is preferably an alkylene group having 1 to 4 carbon atoms.

In General Formula (7), R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms.
R ¹³ and R ¹⁴ may be the same or different.

Specific examples of the linear or branched alkyl group represented by R ¹³ and R ¹⁴ include the same as R ⁸ , R ⁹ , R ¹¹ , and R ^{12 in} the general formula (6).

R ¹³ and R ¹⁴ are preferably a hydrogen atom or a linear or branched alkyl group having 4 to 8 carbon atoms.

  In general formula (7), n represents the integer of 1-4, Preferably it is an integer of 1-3.

In the general formula (8), R ¹⁵ , R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms.
R ¹⁵ , R ¹⁶ and R ¹⁷ may be the same or different.

Specific examples of the linear or branched alkyl group represented by R ¹⁵ , R ¹⁶ and R ¹⁷ are the same as R ⁸ , R ⁹ , R ¹¹ and R ^{12 in} the general formula (6). Can be mentioned.

R ¹⁵ and R ¹⁶ are preferably a hydrogen atom or a linear or branched alkyl group having 4 to 8 carbon atoms, and R ¹⁷ is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. It is a group.

  The hindered phenol compound may be included singly or in combination of two or more.

  Examples of the phosphite include a compound represented by the following general formula (9).

In General Formula (9), R ¹⁸ and R ¹⁹ each independently represent a linear or branched alkyl group having 1 to 20 carbon atoms.
R ¹⁸ and R ¹⁹ may be the same or different.

Specific examples of the linear or branched alkyl group represented by R ¹⁸ and R ¹⁹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-methylbutyl group, n-hexyl group, isohexyl group, 3-methylpentyl group, ethylbutyl group, n-heptyl group, 2-methylhexyl group, n -Octyl group, 2-ethylhexyl group, 3-methylheptyl group, n-nonyl group, methyloctyl group, ethylheptyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tetradecyl group, etc. Can be mentioned.

R ¹⁸ R ¹⁹ is preferably a linear or branched alkyl group having 2 to 6 carbon atoms.

  The phosphite may be contained singly or in combination of two or more.

The content of the antioxidant is preferably 0.05 to 2.0% by mass relative to the total mass of the composition, more preferably 0.25 to 1.5% by mass, and 0.5 to More preferably, the content is 1.0% by mass.
When the content of the antioxidant is 0.05% by mass or more, variation in conductivity at a high temperature of the conductive lubricating oil composition is further suppressed.
One type of antioxidant may be included alone, or two or more types of antioxidants may be combined and included. As for the content when two or more kinds are contained in combination, the total amount is preferably within the above range.

In the conductive lubricating oil composition, the ratio of the antioxidant to the aforementioned conductivity-imparting agent (antioxidant / conductivity-imparting agent) is preferably 0.05 to 200, and preferably 0.5 to 150 on a mass basis. More preferred.
When the above ratio is 0.05 or more, the change in conductivity with time is suppressed, and when it is 200 or less, an effect commensurate with the amount added can be obtained.

<Other additives>
The conductive lubricating oil composition of the present invention further includes general lubricating oil additives such as metal deactivators, rust inhibitors, antiwear agents, pour point depressants, viscosity index improvers, and hydrolysis inhibitors. It may contain.

<Conductivity of composition>
The conductive lubricating oil composition of the present invention has a conductivity at 80 ° C. of preferably 10,000 pS / m or more, more preferably 10,000 pS / m to 100,000 pS / m. When the electrical conductivity is 10,000 pS / m or more, charging of generated static electricity can be suppressed.
The conductivity is measured by using a conductivity meter (for example, a handy conductivity meter 1152 manufactured by Emcee Electronics), heating the temperature of the conductive lubricating oil composition to 80 ° C., and stirring the probe of the conductivity meter. Can be done by plugging in.

The conductive lubricating oil composition of the present invention has a change rate of conductivity of 10% or less after storage at 120 ° C. for 200 hours.
The change rate of the conductivity is more preferably 5% or less, further preferably 2.5% or less, further preferably 2% or less, further preferably 1.5%, and particularly preferably 1% or less.
The lower the change rate of the conductivity, the more stable the conductivity can be maintained for a long time.
The rate of change in conductivity can be determined by measuring the conductivity of the conductive lubricating oil composition before and after storage for 200 hours at 120 ° C.

<Kinematic viscosity and viscosity index of composition>
The electroconductive lubricating oil composition of the present invention preferably has a kinematic viscosity at 40 ° C. of 6 to 15 mm ² / s, more preferably 7.5 to 13 mm ² / s. When the 40 ° C. kinematic viscosity is 6 mm ² / s or more, evaporation loss is suppressed and sufficient lubrication performance can be maintained. Moreover, when it is 15 mm < ² > / s or less, it is suppressed that the viscous torque at the time of using for a precision instrument etc. becomes large, and low temperature fluidity falls. Therefore, it is considered that the kinematic viscosity is in the range of 6 to 15 mm ² / s from the viewpoint of low power consumption, evaporation loss, and lubrication performance.
Further, the conductive lubricating oil composition of the present invention preferably has a viscosity index of 110 or more, more preferably 120 or more. When the viscosity index is 110 or more, a change in viscosity with respect to a change in temperature is suppressed, and an increase in viscosity torque at a low temperature is suppressed.
In addition, 40 degreeC kinematic viscosity of a composition is a value measured by the method prescribed | regulated to JIS-K-2283: 2000 (ASTM D445). Moreover, the viscosity index of a composition is a value measured by the method prescribed | regulated to JISK2283: 2000 (ASTM D2270).

<Use of composition>
The conductive lubricating oil composition of the present invention can be used as lubricating oil for motors and bearings of various precision devices such as CD-R, DVD-R, HDD, and watches.
In particular, excellent lubrication performance is exhibited while stably securing conductivity by using the sliding part and the rotating part of the precision instrument.

  Hereinafter, the contents of the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

In the examples and comparative examples, the conductivity was measured using a “Handy Conductometer 1152 manufactured by Emcee Electronics”. The sample placed in the light-shielding bottle was heated to 80 ° C. with a hot stirrer, and a probe of a conductivity meter was inserted while stirring and measurement was performed.
Further, the change in conductivity was evaluated at 80 ° C. for the conductive lubricating oil composition after being stored at 120 ° C., which is severer than normal use conditions.

(Examples 1-4)
Each component was mix | blended in the ratio (mass%) shown in following Table 1, and the electrically conductive lubricating oil composition of each Example was prepared.
Each of the prepared compositions was stored in a constant temperature bath at 120 ° C. for 200 hours, the conductivity before and after storage was measured, and the rate of change was calculated. Each composition was stored in a thermostat (DRN420DB manufactured by Advantech Co., Ltd.) and kept at a temperature of 120 ° C. without adding pressure and humidity. The results are shown in Table 1 below.

Details of each component in Table 1 are as follows.
(Base oil A) Decanoic acid 2-hexyldecyl ester: a compound in which R ¹ is a linear alkyl group having 10 carbon atoms and n = 7 in the general formula (1) (antioxidant A) alkylated phenyl-α- Naphthylamine: Compound (antioxidant B) in which R ⁷ is a branched alkyl group having 7 carbon atoms in general formula (5) Phosphite: In general formula (9), R ¹⁸ and R ¹⁹ are branched chains having 4 carbon atoms. Compound which is alkyl (antioxidant C) alkylated diphenylamine: Compound (conductivity-imparting agent A) bis (trifluoromethanesulfonyl) in which R ⁵ and R ⁶ are branched alkyl groups having 7 carbon atoms in general formula (4) Imido lithium (conductivity imparting agent B) lithium trifluoromethane sulfonate (conductivity imparting agent C) lithium nonafluorobutane sulfonate (conductivity imparting agent D) bis (t Trifluoromethanesulfonyl) imidopotassium (other lubricant additives) metal deactivators, rust inhibitors, antiwear agents, hydrolysis inhibitors

(Comparative Examples 1-3)
Each component was mix | blended in the ratio (mass%) shown in following Table 2, and the electroconductive lubricating oil composition of each comparative example was prepared.
Each of the prepared compositions was stored in a constant temperature bath at 120 ° C. for 200 hours, and the conductivity before and after storage was measured in the same manner as in Examples 1 to 4, and the rate of change was calculated. The results are shown in Table 2 below.

Details of each component in Table 2 are as follows. The same base oil A, antioxidant A, antioxidant B, antioxidant C, conductivity-imparting agent A, and other lubricating oil additives as in Table 1 were used.
(Conductivity imparting agent E) Alkyl naphthalene sulfonate (Conductivity imparting agent F) Phosphate ester type anionic surfactant

  From Table 1 and Table 2, it can be seen that the conductive lubricating oil compositions of the examples have a low rate of change in electrical conductivity and are excellent in electrical stability over time.

  The conductive lubricating oil composition of the present invention can be used as lubricating oil for motors and bearings of various precision devices such as CD-R, DVD-R, HDD, and watches.

Claims (3)

At least one lubricating base oil selected from the group consisting of fatty acid monoester base oils and ether ester base oils;
Selected from the group consisting of potassium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, lithium bis (trifluoromethanesulfonyl) imide, potassium bis (trifluoromethanesulfonyl) imide, and lithium tris (trifluoromethanesulfonyl) methide Containing at least one conductivity-imparting agent in an amount of 0.01 to 1% by mass relative to the total mass of the composition,
A conductive lubricating oil composition having a conductivity change rate of 10% or less after storage at 120 ° C. for 200 hours.   Further, 0.05 to 2% by mass of at least one antioxidant selected from the group consisting of diphenylamine compounds, alkylated phenyl-α-naphthylamines, hindered phenol compounds, and phosphites is contained with respect to the total mass of the composition. The conductive lubricating oil composition according to claim 1. The electroconductive lubrication of Claim 1 or Claim 2 whose said lubricating base oil is a compound represented by either the following general formula (1), general formula (2), or general formula (3). Oil composition.

[In General Formula (1), R ¹ represents a linear or branched alkyl group having 8 to 16 carbon atoms or a heteroalkyl group containing an oxygen atom, and n represents an integer of 5 to 11. ]

[In General Formula (2), R ² represents a linear or branched alkyl group having 8 to 16 carbon atoms or a heteroalkyl group containing an oxygen atom, and n represents an integer of 5 to 11. ]

[In General Formula (3), A ¹ represents a linear or branched alkylene group or heteroalkylene group having 8 to 15 carbon atoms, and R ³ and R ⁴ each independently represent 6 to 10 carbon atoms. Represents a linear or branched alkyl group. ]