KR-20260064730-A - Conductive composition comprising perfluoropolyether oil and carbon nanotubes

Abstract

The present invention provides 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 5.0 nm and the content of the carbon nanotubes is 0.5 to 3.0 mass% based on the total mass of the composition.

Inventors

• 노우야마 사토시
• 이치무라 료스케

Assignees

• 교도유시 가부시끼가이샤

Dates

Publication Date

20260507

Application Date

20241009

Priority Date

20231010

Claims (4)

1. It contains perfluoropolyether oil as a base oil and carbon nanotubes as a conductive material, The diameter of the carbon nanotubes is 0.4 to 5.0 nm, and also, The content of the carbon nanotubes is 0.5 to 3.0 mass% with respect to the total mass of the composition, Conductive composition.
2. In paragraph 1, A conductive composition in which the carbon nanotubes are a single layer or two layers.
3. In paragraph 1 or 2, A conductive composition that does not contain a thickener.
4. In paragraph 1 or 2, A conductive composition further comprising a thickener.

Description

Conductive composition comprising perfluoropolyether oil and carbon nanotubes The present invention relates to a conductive composition that can be used in rolling bearings, etc. Recently, variable speed operation of rotary electric vehicles using inverter power is being implemented in fields such as automobiles, railways, and home appliances. However, electrical problems associated with inverter driving are also arising. For example, in bearings, there is damage known as electro-corrosion, which occurs when voltage is applied between the rotating shaft and the bearing, causing a discharge. In the case of bearings, electro-corrosion occurs when there is a potential difference between the inner and outer rings of the bearing, or when a common mode current flows. More specifically, it progresses into electro-corrosion due to continuous discharge in the lubricating film interposed between the spheres, which are the rolling elements of the bearing, and the raceway surface of the bearing. Patent Document 1 has the objective of providing a conductive grease that exhibits good conductivity and also has good friction characteristics, and provides a conductive grease containing perfluoropolyether oil as a base oil and 0.1 to 20 weight% of carbon nanotubes with a diameter of 40 to 200 nm as a conductive imparting material. [Fig. 1] This is a schematic diagram showing the overall structure of a carbon nanotube. Giyu The perfluoropolyether oil that can be used in the composition of the present invention is, specifically, one expressed by formulas (1) to (5), for example. Among these, one expressed by formula (1) is particularly preferred. [Painting 1] And, m and n are both numbers greater than or equal to 0. The perfluoropolyether oil of the present invention may be used alone or in a mixture of two or more types. However, it does not include base oils other than perfluoropolyether oil. It is preferable that the kinematic viscosity at 40°C (measured in accordance with JIS K2283) is approximately 4 to 2000 mm²/s. More preferably, the kinematic viscosity is 60 to 500 mm²/s. It is desirable that the kinematic viscosity of the base oil at 40°C is 4 mm²/s or higher, as this tends to suppress evaporation or oil release of the base oil under high temperatures. On the other hand, it is desirable that the kinematic viscosity at 40°C is 2000 mm²/s or lower, as this makes it easier to obtain appropriate fluidity. In addition, if a perfluoropolyether oil with a relatively high kinematic viscosity at 40°C, for example, a perfluoropolyether oil with a viscosity of 400 mm²/s or higher is used, the conductive composition of the present invention can be made into a paste form, thereby preventing liquid leakage or spillage at the application site and improving convenience of use depending on the application. As described below, a thickener and/or a solid lubricant may be added to the conductive composition of the present invention to make it into a solid to semi-solid grease form. In this case, a perfluoropolyether oil with a relatively low kinematic viscosity at 40°C, for example, a perfluoropolyether oil with a viscosity of 400 mm²/s or lower, may also be used. The content of perfluoropolyether oil in the conductive composition of the present invention is preferably 50 to 99.5 mass% based on the total mass of the composition, more preferably 60 to 99.4 mass%, and even more preferably 70 to 99.3 mass%. It is desirable for the content of the base oil to be within this range in terms of fluidity and heat resistance. Carbon Nanotubes Carbon nanotubes are tubes formed by stacking graphite-like carbon, and each layer has a closed structure at both ends, similar to fullerene. The overall structure is roughly as shown in Figure 1. The minimum diameter ("D") of carbon nanotubes reported to date is 0.4 nm (Lu-Chang Qin et al., "The smallest carbon nanotube", Nature, 408, 50 (2000)). In the present invention, carbon nanotubes with a diameter of 0.4 nm or more may be used. On the other hand, since torque increases as the content of carbon nanotubes in the composition increases, it is preferable to have a low content of carbon nanotubes in the composition. By including carbon nanotubes with a diameter of 5.0 nm or less, a sufficient discharge suppression effect can be achieved even with a small amount. The composition of the present invention preferably includes carbon nanotubes with a diameter of 0.4 to 5.0 nm, and more preferably includes carbon nanotubes with a diameter of 1.2 to 5.0 nm. Meanwhile, in carbon nanotubes with a diameter of 5.0 nm or more, since three or more layers of multilayer carbon nanotubes account for a significant proportion, making them prone to discharge, it is preferable that the conductive composition of the present invention does not include carbon nanotubes with a diameter greater than 5.0 nm. The length of the carbon nanotube is not particularly limited. For example, carbon nanotubes with a length of 5 µm or more and