Rheology and curing characteristics of dual-curable automotive clearcoats using thermal radical initiator derived from O-imino-isourea and photo-initiator
- Authors
- Hwang, Ji Won; Kim, Kyung Nam; Lee, Gil Sun; Nam, Joon Hyun; Noh, Seung Man; Jung, Hyun Wook
- Issue Date
- 11월-2013
- Publisher
- ELSEVIER SCIENCE SA
- Keywords
- Dual curing; Clearcoats; Thermal radical initiator; Photo-initiator; Elastic modulus; Scratch property
- Citation
- PROGRESS IN ORGANIC COATINGS, v.76, no.11, pp.1666 - 1673
- Indexed
- SCIE
SCOPUS
- Journal Title
- PROGRESS IN ORGANIC COATINGS
- Volume
- 76
- Number
- 11
- Start Page
- 1666
- End Page
- 1673
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/101819
- DOI
- 10.1016/j.porgcoat.2013.07.019
- ISSN
- 0300-9440
- Abstract
- 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. (C) 2013 Elsevier B.V. All rights reserved.
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