CN-121986153-A - Conductive composition comprising perfluoropolyether oil and carbon nanotubes

Abstract

According to the present invention, there is provided a conductive composition comprising a perfluoropolyether oil as a base oil and carbon nanotubes as a conductive substance, wherein the diameter of the carbon nanotubes is 0.4 to 5.0nm, and the content of the carbon nanotubes is 0.5 to 3.0 mass% relative to the total mass of the composition.

Inventors

• Accept the wisdom of mountains
• ICHIMURA RYOSUKE

Assignees

• 协同油脂株式会社

Dates

Publication Date

20260505

Application Date

20241009

Priority Date

20231010

Claims (4)

1. 1. A conductive composition comprising a perfluoropolyether oil as a base oil and carbon nanotubes as a conductive material, The diameter of the carbon nano tube is 0.4-5.0 nm, and The content of the carbon nanotubes is 0.5-3.0 mass% relative to the total mass of the composition.
2. 2. The conductive composition of claim 1, wherein the carbon nanotubes are a single layer or two layers.
3. 3. The conductive composition according to claim 1 or 2, wherein a thickener is not contained.
4. 4. The conductive composition of claim 1 or 2, further comprising a thickener.

Description

Conductive composition comprising perfluoropolyether oil and carbon nanotubes Technical Field The present invention relates to a conductive composition useful for rolling bearings and the like. Background In recent years, variable speed operation of a rotating electrical machine using an inverter power source has been performed in the fields of automobiles, railways, home appliances, and the like. However, electrical problems associated with inverter driving also occur. For example, in the bearing, there is a damage called electrolytic corrosion, which is caused by applying a voltage between the rotating shaft and the bearing to cause discharge. In the case of a bearing, electrolytic corrosion occurs due to a potential difference or a common mode current flowing between an inner ring and an outer ring of the bearing. Specifically, the electrolytic corrosion progresses due to continuous discharge in a lubricating film interposed between balls, which are rolling elements of the bearing, and raceway surfaces of the bearing. Patent document 1 has an object of providing a conductive grease exhibiting good conductivity and good friction characteristics, and provides a conductive grease containing a perfluoropolyether oil as a base oil and 0.1 to 20 wt% of carbon nanotubes having a diameter of 40 to 200nm as a conductivity-imparting substance. Prior art literature Patent literature Patent document 1 Japanese patent application 5747230 Disclosure of Invention Problems to be solved by the invention Patent document 1 evaluates the quality of conductivity by the value of volume resistivity. The volume resistivity is a value calculated based on measurement by a dc circuit, but it is more appropriate to evaluate the difficulty of current flow in an inverter circuit converting dc into ac, that is, an index corresponding to resistance, by using impedance indicating the difficulty of current flow in an ac circuit. The invention aims to provide a conductive composition with low impedance. Means for solving the problems According to the present invention, the following conductive composition is provided. 1. A conductive composition comprising a perfluoropolyether oil as a base oil and carbon nanotubes as a conductive material, wherein the diameter of the carbon nanotubes is 0.4 to 5.0nm, and the content of the carbon nanotubes is 0.5 to 3.0 mass% relative to the total mass of the composition. 2. The conductive composition according to 1, wherein the carbon nanotube is a single layer or two layers. 3. The conductive composition according to 1 or 2, wherein a thickener is not contained. 4. The conductive composition according to 1 or 2, further comprising a thickener. Effects of the invention According to the present invention, by combining the perfluoropolyether oil with a specific amount of carbon nanotubes of a specific size, the value of impedance indicating difficulty in flowing current in an ac circuit can be reduced. Thus, the conductive composition of the present invention can suppress the occurrence of electrolytic corrosion because the conductive composition maintains a good conductive state and charges are less likely to accumulate, thereby suppressing discharge. The composition of the present invention also reduces the dielectric breakdown voltage. Drawings Fig. 1 is a schematic view showing the overall structure of a carbon nanotube. Detailed Description < Base oil > The perfluoropolyether oils usable in the composition of the present invention are specifically those represented by the formulae (1) to (5). Among them, the compound represented by the formula (1) is particularly preferable. [ Chemical 1] Wherein m and n are each a number of 0 or more. The perfluoropolyether oil of the present invention can be used alone or in combination of 2 or more. But does not include base oils other than perfluoropolyether oils. The kinematic viscosity at 40℃is preferably about 4 to 2000mm 2/s as measured in accordance with JIS K2283. Further preferably, the kinematic viscosity is 60 to 500mm 2/s. When the kinematic viscosity of the base oil at 40℃is 4mm 2/s or more, evaporation of the base oil at high temperature, oil separation and the like tend to be suppressed, and thus it is preferable. On the other hand, a kinematic viscosity at 40℃of 2000mm 2/s or less is preferred because appropriate fluidity can be easily obtained. In addition, if a perfluoropolyether oil having a relatively high kinematic viscosity at 40 ℃ is used, for example, a perfluoropolyether oil having a kinematic viscosity of 400mm 2/s or more, the conductive composition of the present invention can be made into a paste, and thus leakage or dripping at the application site can be prevented, and the convenience of use can be improved depending on the application. As described later, a thickener and/or a solid lubricant may be added to the conductive composition of the present invention to form a solid or semisolid grease. In this case, the perfluoropolyether oi