A novel isocyanate blocked with an amine derivative blocking agent (2-(tert-butylamino) ethyl methacrylate, TBEMA) was designed as a thermal crosslinker for an eco-friendly automotive clearcoat system. New dual-curable blocked isocyanate (BITBEMA) was effectively deblocked at curing temperatures of 120 and 130 °C, which are lower than the conventional curing temperature of 150 °C. The deblocking features of BITBEMA were verified through experimental measurements and density functional theory simulations. The amine-based blocking agent with the methacrylate functionality directly participated in free radical polymerization with C[dbnd]C double bonds in the main resin (hydroxyl functionalized urethane methacrylate oligomer) during thermal curing, leading to enhanced crosslinking networks as well as reduced emissions of volatile organic compounds. The real-time crosslinking behaviors and mechanical properties of the clearcoat with BITBEMA were compared to those of clearcoats with mono-curable amine-based blocked isocyanate and a commercial crosslinker, confirming the excellent crosslinking characteristics of the dual-curable isocyanate crosslinker.
Bibliographical noteFunding Information:
This research was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Industrial Technology Innovation Program (grant numbers 20017536 and 20010256) and the Korea Research Institute of Chemical Technology (KRICT) Research and Development (R&D, SS2241-10) program.
© 2022 Elsevier B.V.
- Amine-based blocked isocyanate
- Eco-friendly clearcoat
- Methacrylate functionalization
- Thermal crosslinking
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Surfaces and Interfaces