Rheology and curing characteristics of dual-curable automotive clearcoats using thermal radical initiator derived from O-imino-isourea and photo-initiator

Ji Won Hwang, Kyung Nam Kim, Gil Sun Lee, Joon Hyun Nam, Seung Man Noh, Hyun Wook Jung

Research output: Contribution to journalArticle

17 Citations (Scopus)


The curing characteristics of clearcoats, including a thermal curing initiator (TRI) newly designed from O-imino-isourea and photo-initiator (PI), were investigated by means of different mono-curing and dual-curing pathways. The competitive relationship between TRI and PI on the curing pattern, reacting with acrylate double bonds in a clearcoat was elucidated by altering the UV and thermal sequence in the dual-curing process, through various experimental methods. From the rheological properties of clearcoats along the curing time, two dual-curing methods showed the different evolution of curing patterns. In the UV-thermal dual-curing case, the initial infusion of UV light promoted free radical polymerization during the subsequent thermal curing by generating considerable free radicals, and exhibiting a higher growth rate of elastic modulus during the curing in comparison with the thermal-UV dual-curing case. However, the final modulus value in the thermal-UV dual-curing case was higher due to the suppression of thermal curing by the steric hindrance in the UV-thermal dual-curing. The level of crosslinked networks in clearcoats via different curing steps can be explicitly figured out from the double bond conversion from FT-IR, curing pattern from rigid-body pendulum test, and scratch properties from nano-scratch test.

Original languageEnglish
Pages (from-to)1666-1673
Number of pages8
JournalProgress in Organic Coatings
Issue number11
Publication statusPublished - 2013 Nov 1



  • Clearcoats
  • Dual curing
  • Elastic modulus
  • Photo-initiator
  • Scratch property
  • Thermal radical initiator

ASJC Scopus subject areas

  • Organic Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry
  • Chemical Engineering(all)

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