KR-20260064731-A - Conductive composition comprising silicone oil and carbon nanotubes
Abstract
The present invention provides a conductive composition comprising silicone 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)
- It contains silicone 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.
- In paragraph 1, A conductive composition in which the carbon nanotubes are a single layer or two layers.
- In paragraph 1 or 2, A conductive composition that does not contain a thickener.
- In paragraph 1 or 2, A conductive composition further comprising a thickener.
Description
Conductive composition comprising silicone oil and carbon nanotubes The present invention relates to a conductive composition that can be used in rolling bearings, etc. Damage caused by electricity is known in steel and steel lubricating surfaces. For example, in bearings, there is damage called electrochemical corrosion, which occurs when a voltage is applied between a rotating shaft and a bearing and causes a discharge. In the case of a bearing, electrochemical 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 electrochemical corrosion by continuously discharging in the lubricating film interposed between the sphere and the raceway surface of the bearing. Patent Document 1 has the objective of providing a conductive grease having excellent conductivity and being unlikely to experience a decrease in conductivity over time, and a driving device having a low electrical resistance value and being unlikely to become charged over a long period of time, and provides a conductive grease comprising carbon nanotubes as a conductive additive. By using this grease, the electrical resistance value of a bearing is lowered. [Fig. 1] This is a schematic diagram showing the overall structure of a carbon nanotube. Giyu The silicone oils that can be used in the composition of the present invention are, specifically, examples such as dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, and modified silicone oil. Among these, dimethyl silicone oil is particularly preferred. The silicone oil of the present invention may be used alone or in a mixture of two or more types. However, it does not contain base oils other than silicone oil. It is preferable that the kinematic viscosity at 25°C (measured in accordance with JIS K2283) is approximately 5 to 10,000 mm²/s. More preferably, the kinematic viscosity is 10 to 1,000 mm²/s. It is desirable that the kinematic viscosity of the base oil at 25°C is 5 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 25°C is 10,000 mm²/s or lower, as this makes it easier to obtain appropriate fluidity. In addition, if a silicone oil with a relatively high kinematic viscosity at 25°C, for example, 100 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 ease 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 silicone oil with a relatively low kinematic viscosity at 25°C, for example, 100 mm²/s or lower, may be used. The content of silicone 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%. If the content of the base oil is within this range, it is desirable from the perspective 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 600 µm or less can be used. As shown in FIG. 1, the diameter of the carbon nanotube refers to the short side in the plan view, and the length of the carbon nanotube refers to the long side in the plan view. The diameter and len