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Sumitomo Bakelite's New High Tracking Resistance Epoxy Powder Coating

Sumitomo Bakelite Co., Ltd., based in Shinagawa, Tokyo and led by President Shinichi Kajiya, has announced the development of a high-tracking resistance epoxy powder coating specifically designed for electrical insulation applications. This innovative material meets a Comparative Tracking Index (CTI) of 900V, making it suitable for insulating coatings on conductors subjected to high voltages, such as busbars.

Understanding Tracking Resistance

Tracking resistance is a critical characteristic that defines how well an insulating material can prevent electrical discharges that form conductive pathways on its surface. This phenomenon can lead to shorts and insulation failure, which is a significant safety concern in electrical applications. The CTI is a standardized measure of an insulating material's performance, and a higher CTI indicates better tracking resistance.

Background of Development

The shift towards higher voltage systems is increasingly evident, particularly in electric vehicles (EVs), as manufacturers aim to extend driving ranges and reduce charging times. In Europe and North America, the standardization of 800V electrical systems is gaining momentum not only for EVs but also for eVTOLs (Electric Vertical Take-Off and Landing vehicles) and other high-output applications. This trend is further observed in industrial machinery, offshore wind power vessels, solar power inverters, and large-scale energy storage systems, where 1kV applications are becoming more prevalent. Given this trajectory, there is a growing demand for insulation coatings with superior tracking resistance to ensure long-term reliability and safety.

In response to these needs, Sumitomo Bakelite has developed a powder coating with a CTI of 900V, suitable for the demands of modern high-voltage applications.

Features of the New Epoxy Powder Coating

The new high tracking resistance epoxy powder coating is designed to enhance insulation on conductor surfaces, a role typically fulfilled by both liquid and powder coatings. From an environmental perspective and with regard to shape stability and productivity, solvent-free powder coatings are advantageous compared to liquid coatings. However, traditional thermoplastic coatings can present risks of decreased insulation performance due to a lack of adhesion between the coating and the conductor surface. In contrast, Sumitomo's powder coating is based on thermosetting epoxy resin, which chemically reacts during the coating process, establishing robust adhesion and enhanced insulation reliability.

While typical epoxy powder coatings exhibit dielectric breakdown voltages between 30 to 40kV/mm, the existing CTI of such coatings usually ranges around 300 to 600V. In line with this disparity, the new product complies with UL2597's Surface Tracking Test (STT) standard and has proven to achieve a CTI of 900V, confirming its capability to meet the demands of the increasing high-voltage trend.

Advantages in Development and Production

This product is designed to maintain insulation performance even under prolonged usage at 900V, significantly reducing the risk of performance degradation and allowing for a decreased creepage distance between conductors. This contributes to miniaturization and enhanced efficiency in electrical systems and components. Moreover, the capability to apply thin insulation coatings on various conductor shapes without the need for molds further enhances its applicability.

Future Plans

With the ongoing trend towards 800V systems in EVs in Europe and North America, the demand for high tracking resistance features is surging. Initially, the application of this powder coating is focused on battery busbars in EVs; however, Sumitomo Bakelite also aims to explore other sectors where high tracking resistance is crucial. The product has confirmed its CTI of 900V, and sample testing will commence shortly. Moreover, the company is dedicated to extending its product applications beyond EVs to include busbars and bus rings for drones and wind turbine motors.

For inquiries related to this product, you can contact the Materials Solution Sales Division at Sumitomo Bakelite Co., Ltd. at Tel: 03-5462-4757.