Announcement of the Development of High Tracking Resistance Epoxy Resin Powder Coating
Sumitomo Bakelite Co., Ltd. has developed a high tracking resistance epoxy resin powder coating with a CTI of 900V, designed for electrical insulation in high-voltage applications like EVs and renewable energy. This innovation enhances the long-term reliability and safety of high-voltage equipment by reducing the risk of short circuits due to insulation degradation.
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- 📰 Published: April 1, 2026 at 20:45
- 🔍 Collected: April 1, 2026 at 16:47
- 🤖 AI Analyzed: April 21, 2026 at 08:59 (472h 11m after Collected)
Sumitomo Bakelite Co., Ltd. (Head office: Shinagawa-ku, Tokyo; Representative Director and President: Shinichi Kajiya) has developed a powder coating for electrical insulation with high tracking resistance*1. This material boasts a Comparative Tracking Index (CTI)*2 of 900V, making it a solvent-free epoxy resin-based insulating coating suitable for insulating high-voltage conductors such as busbars.
*1 Tracking Resistance: Refers to the resistance against "tracking phenomenon," where conductive paths (tracks) are formed on the surface of an insulator due to electrical discharge, leading to short circuits (insulation breakdown) between wirings.
*2 Comparative Tracking Index (CTI): A standardized index for evaluating the tracking resistance of insulating materials. A higher CTI indicates superior tracking resistance.
**Background of Development**
In order to extend the cruising range of EVs and shorten charging times, the voltage of EV electrical systems (receiving and supplying sides) is increasingly being raised to 800V, especially in Europe and the United States. Beyond EVs, high voltage is expected to advance in mobile units such as eVTOLs*3 and electric vehicles, aiming for higher output and lighter weight. Furthermore, 1kV-class applications are expanding in industrial machinery, offshore wind power generation vessels, solar power generation-linked inverters, and large-scale storage battery systems.
As the number of high-voltage products is expected to increase, a higher level of tracking resistance than conventional materials is anticipated for conductor insulation coatings to ensure long-term reliability and safety. In response to these needs, we have developed an epoxy resin powder coating with a CTI 900V performance.
*3 eVTOL: An acronym for "Electric Vertical Take-Off and Landing," referring to aircraft that can take off and land vertically using electric power.
**Features of High Tracking Resistance Epoxy Resin Powder Coating**
Generally, liquid coatings and powder coatings are widely used to provide insulation to conductor surfaces. From the perspectives of environmental protection, shape stability, and productivity, solvent-free powder coatings are superior to liquid coatings. Additionally, among powder coatings, those based on thermoplastic resins carry a risk of insulation degradation during use because no adhesion occurs between the coated conductor and the film. In contrast, our powder coating is based on a thermosetting epoxy resin, and a reaction occurs with the conductor during the coating process, resulting in strong adhesion and improved reliability of insulation performance.
Typically, the dielectric breakdown voltage of epoxy resin powder coating films is very high, ranging from 30 to 40kV/mm, but the CTI, one of the indicators of insulation durability, is generally around 300 to 600V.
In contrast, this product conforms to the UL2597 STT test, a UL standard for tracking resistance, and our internal measurements of the CTI performance of the epoxy resin powder coating development product confirmed that it achieved CTI 900V, demonstrating its capability to meet the trend towards higher voltages (see Figure 1).
*1 Tracking Resistance: Refers to the resistance against "tracking phenomenon," where conductive paths (tracks) are formed on the surface of an insulator due to electrical discharge, leading to short circuits (insulation breakdown) between wirings.
*2 Comparative Tracking Index (CTI): A standardized index for evaluating the tracking resistance of insulating materials. A higher CTI indicates superior tracking resistance.
**Background of Development**
In order to extend the cruising range of EVs and shorten charging times, the voltage of EV electrical systems (receiving and supplying sides) is increasingly being raised to 800V, especially in Europe and the United States. Beyond EVs, high voltage is expected to advance in mobile units such as eVTOLs*3 and electric vehicles, aiming for higher output and lighter weight. Furthermore, 1kV-class applications are expanding in industrial machinery, offshore wind power generation vessels, solar power generation-linked inverters, and large-scale storage battery systems.
As the number of high-voltage products is expected to increase, a higher level of tracking resistance than conventional materials is anticipated for conductor insulation coatings to ensure long-term reliability and safety. In response to these needs, we have developed an epoxy resin powder coating with a CTI 900V performance.
*3 eVTOL: An acronym for "Electric Vertical Take-Off and Landing," referring to aircraft that can take off and land vertically using electric power.
**Features of High Tracking Resistance Epoxy Resin Powder Coating**
Generally, liquid coatings and powder coatings are widely used to provide insulation to conductor surfaces. From the perspectives of environmental protection, shape stability, and productivity, solvent-free powder coatings are superior to liquid coatings. Additionally, among powder coatings, those based on thermoplastic resins carry a risk of insulation degradation during use because no adhesion occurs between the coated conductor and the film. In contrast, our powder coating is based on a thermosetting epoxy resin, and a reaction occurs with the conductor during the coating process, resulting in strong adhesion and improved reliability of insulation performance.
Typically, the dielectric breakdown voltage of epoxy resin powder coating films is very high, ranging from 30 to 40kV/mm, but the CTI, one of the indicators of insulation durability, is generally around 300 to 600V.
In contrast, this product conforms to the UL2597 STT test, a UL standard for tracking resistance, and our internal measurements of the CTI performance of the epoxy resin powder coating development product confirmed that it achieved CTI 900V, demonstrating its capability to meet the trend towards higher voltages (see Figure 1).