Aminated Carbon Black for Epoxy/Paraffin PTC Ink: Achieving the Elimination of NTC and Cycle Stability

Abstract The rapid development of modern precision electronic components placed stringent demands on highly sensitive voltage overload protection and thermal management, and the positive temperature coefficient (PTC) effect observed in conductive polymer composites (CPCs) played a crucial role in this regard. However, once the polymer matrix had melted, most PTC composites exhibited a negative temperature coefficient (NTC) effect, while the excessive rigidity and brittleness of traditional ceramics limited their practical applications. This study presented a PTC ink composite material. The method involved the synergistic use of a thermosetting epoxy resin (EP) matrix and paraffin wax (PW), a material with a high expansion ratio, with γ-aminopropyltriethoxysilane (KH550)-grafted carbon black (KCB) serving as the conductive filler, printed on the film using screen printing. The results indicate that the formation of static covalent bonds and hydrogen bonds at the interface between KCB and the epoxy resin effectively eliminates the influence of NTC. This ink exhibits sensitive temperature responsiveness at 30–50 °C, extends the PTC plateau, and achieves a PTC intensity of 3. Compared with traditional heating elements, this PTC ink composite offers advantages such as rapid response, sensitivity, and the ability to meet the start-up temperature requirements of electronic devices in cold conditions, as well as temperature self-limiting properties, safety, and convenience. These epoxy-based PTC composite materials show great promise in applications such as thermal protection for electronic components and battery circuit protection.