TY - JOUR
T1 - Crosslinking characteristics of dual-curable blocked isocyanate with thermal radical initiator for lowering curing temperature of automotive clearcoats
AU - Jung, Kevin Injoe
AU - Hong, Jun Ui
AU - Noh, Seung Man
AU - Jung, Hyun Wook
N1 - Funding Information:
This study was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Industrial Technology Innovation Program (No. 20004044 and No. 20010256 ) and the Korea Research Institute of Chemical Technology (KRICT) Research and Development (R&D, SS2141-10 ) program.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021
Y1 - 2021
N2 - A novel dual-curable blocked isocyanate crosslinker was designed for the simultaneous radical and urethane crosslinking of automotive clearcoats under low-temperature conditions. Three isocyanate groups on the three ends of the hexamethylene diisocyanate-based crosslinker were blocked using two different blocking agents: a thermal radical initiator (TRI) and dimethyl pyrazole. Clearcoats based on hydroxyl-functionalized urethane methacrylate oligomer resin and the hybrid blocked isocyanate crosslinker (BITD) were confirmed to be densely crosslinked by the simultaneous radial and urethane reactions occurring at the curing temperature of 130 °C, which temperature condition is lower than the conventional 150 °C. A comparison of the real-time curing behavior of clearcoat mixtures and the thermo-mechanical and surface hardness properties of the post-cured clearcoat films revealed that the crosslinking performance of a dual-curable BITD crosslinker was better than that of a mono-curable TRI and commercial blocked isocyanate crosslinker. This study demonstrated that through the correlation between crosslinking characteristics and coating performance, it is possible to actively implement the low-temperature curing technology of clearcoats by utilizing a dual-curable blocked isocyanate.
AB - A novel dual-curable blocked isocyanate crosslinker was designed for the simultaneous radical and urethane crosslinking of automotive clearcoats under low-temperature conditions. Three isocyanate groups on the three ends of the hexamethylene diisocyanate-based crosslinker were blocked using two different blocking agents: a thermal radical initiator (TRI) and dimethyl pyrazole. Clearcoats based on hydroxyl-functionalized urethane methacrylate oligomer resin and the hybrid blocked isocyanate crosslinker (BITD) were confirmed to be densely crosslinked by the simultaneous radial and urethane reactions occurring at the curing temperature of 130 °C, which temperature condition is lower than the conventional 150 °C. A comparison of the real-time curing behavior of clearcoat mixtures and the thermo-mechanical and surface hardness properties of the post-cured clearcoat films revealed that the crosslinking performance of a dual-curable BITD crosslinker was better than that of a mono-curable TRI and commercial blocked isocyanate crosslinker. This study demonstrated that through the correlation between crosslinking characteristics and coating performance, it is possible to actively implement the low-temperature curing technology of clearcoats by utilizing a dual-curable blocked isocyanate.
KW - Automotive clearcoat
KW - Dual-curable crosslinker
KW - Low-temperature curing
KW - Radical crosslinking
KW - Thermal radical initiator
KW - Urethane crosslinking
UR - http://www.scopus.com/inward/record.url?scp=85119287469&partnerID=8YFLogxK
U2 - 10.1016/j.porgcoat.2021.106611
DO - 10.1016/j.porgcoat.2021.106611
M3 - Article
AN - SCOPUS:85119287469
VL - 163
JO - Progress in Organic Coatings
JF - Progress in Organic Coatings
SN - 0300-9440
M1 - 106611
ER -