Diamine-modified bismaleimide for toughening of UV-cured epoxy acrylate coating

With the rapid development of the electronics industry, higher requirements are being placed on the quality and reliability of flexible copper clad laminate (FCCL). To protect FCCL, there have been studies on using UV curable coatings for surface protection. However, traditional UV curable coatings based on epoxy acrylate (EA) resins tend to be rigid, and although methods for toughening them exist, they often compromise their heat resistance. Therefore, there is ongoing research on how to improve the toughness of UV-curable coatings while maintaining the heat resistance of the EA resin. In this study, a high-heat-resistant bismaleimide (BMI) with excellent properties was used as a toughener by modifying it with 4,4′-Oxydianiline (ODA) and polyetheramine (PEA). The modified BMI was then introduced into the EA resin to prepare a UV-curable protective coating with high heat resistance, toughness, and good insulation and dielectric properties. The research results showed that after the addition of modified BMI, the heat stability was not reduced and even showed improvement, and under conditions of nearly unchanged hardness, the best adhesion was rated as 5B, with a minimum bending radius of 1 mm. At an ODA:PEA ratio of 3:7, the coating attains a maximum tensile strength of 36.84 MPa, showcasing a notable 76.65 % enhancement in elongation at break when contrasted with coatings composed solely of pure EA. When the ratio of ODA to PEA was 4:6, the coating exhibited a minimum dielectric constant of 3.05, a breakdown field strength of up to 77.37 kV/mm, and a volume resistivity of 3.52 × 1014 Ω m, indicating excellent dielectric and insulation performance. This study provides a novel method for the preparation of UV curable coatings with outstanding performance, offering new insights and directions for future research on UV curable coatings for FCCL. Moreover, the research results have important implications for industrial applications.