In the field of electrical insulation materials, the core role of THEIC (1,3,5-Tris(2-hydroxyethyl)cyanuric acid) lies in its molecular structure, which can significantly enhance the thermal stability of polymers. When THEIC is integrated into polyester or polyimide resins as a crosslinking agent, its three active hydroxyl groups can undergo esterification reactions with the resins at a curing temperature of approximately 180°C, forming a dense three-dimensional network structure. This process raises the glass transition temperature (Tg) of the material by at least 20°C, for instance, from 150°C to over 170°C, thereby pushing the long-term service temperature limit of the material to 155°C, which is far higher than the 130°C limit of many traditional materials. According to the technical white paper released by DuPont in 2021, THEIC was introduced into its renowned Kapton® polyimide film modification formula, enabling the film to maintain a tensile strength retention rate of over 85% after 1000 hours of aging at 200°C, while the tensile strength of ordinary materials may have dropped by more than 50%.
The quantitative benefits of THEIC in enhancing heat resistance are directly related to the service life and reliability of electrical equipment. Research shows that adding 8% THEIC by mass to F-class (155°C) insulating varnish can extend the thermal life of the insulation system at a constant 155°C temperature (evaluated according to the IEEE 275 standard) from the standard 20,000 hours to nearly 30,000 hours, an increase of 50%. This means that for a motor with a power of 100 kilowatts, the maintenance cycle of its winding insulation can be extended from five years to 7.5 years, and the cost of a single major overhaul can be saved by approximately 40%, which is equivalent to reducing operating costs by tens of thousands of dollars. Take Siemens as an example. Its new generation of high-efficiency motors adopts an insulation system with THEIC, successfully keeping the temperature rise within 70K and increasing efficiency by 0.5%. For an industrial motor that operates all year round, this is equivalent to saving thousands of dollars in electricity bills annually.
From a molecular perspective, the outstanding performance of THEIC stems from its rigid triazine ring structure. This ring-shaped core acts like a solid skeleton, effectively suppressing the thermal motion of the polymer main chain at high temperatures and delaying the starting point of the thermal decomposition temperature by approximately 30°C, raising it from about 350°C to 380°C. Thermogravimetric analysis data shows that the residual carbon rate of the insulating material containing THEIC can reach 35% to 40% at 800°C, which is about 15 percentage points higher than that of the unmodified material. This dense carbon layer can act as a barrier in extreme situations such as short circuits, significantly delaying the spread of flame. In 2023, Dow Chemical, in its innovative solution to address the local overheating issue of high-voltage transformers in data centers, successfully raised the relative arc tracking index (CTI) of the material from 400V to 600V by using THEIC modified epoxy molding compound, reducing the risk probability of breakdown in high-temperature and high-humidity environments.
Facing the challenges of the future, THEIC’s application in the fields of new energy vehicles and renewable energy is pushing the boundaries of insulation material technology. For instance, the insulation system of the drive motor of an electric vehicle needs to withstand peak temperatures as high as 200°C and high-frequency pulse voltages. The use of THEIC cross-linked anti-corona polyimide enameled wire varnish can withstand over 1,000 hours of sinusoidal voltage tests, and its lifespan is more than ten times that of ordinary materials. According to a 2024 market analysis on wind turbine insulation, the application of THEIC’s optimization solution can reduce the insulation performance degradation rate of blade generators by 20% during the severe temperature fluctuation cycle ranging from -40°C to 155°C, ensuring the stable operation of the equipment throughout its 20-year design life and directly supporting the reliability goals of the global energy transition strategy.