Effect of isocyanate crosslinkers blocked with amine derivatives on rheological and crosslinking characteristics of automotive clearcoats
- Authors
- June, Young-Gun; Jung, Kevin Injoe; Lee, Tae Hee; Ha, Miran; Noh, Seung Man; Jung, Hyun Wook
- Issue Date
- 2월-2021
- Publisher
- KOREAN SOC RHEOLOGY
- Keywords
- automotive clearcoat; blocked isocyanates; urethane crosslinking; curing dynamics; surface resistance; amine-based blocking agents
- Citation
- KOREA-AUSTRALIA RHEOLOGY JOURNAL, v.33, no.1, pp.37 - 43
- Indexed
- SCIE
SCOPUS
KCI
- Journal Title
- KOREA-AUSTRALIA RHEOLOGY JOURNAL
- Volume
- 33
- Number
- 1
- Start Page
- 37
- End Page
- 43
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/49637
- DOI
- 10.1007/s13367-021-0004-2
- ISSN
- 1226-119X
- Abstract
- Isocyanate crosslinkers with blocking agents based on various amine derivatives were newly synthesized for automotive clearcoat applications. Amine-based blocking agents were prepared by varying the alkyl substituent attached on both sides of the main nitrogen atom (named DEA, DiPA, NtBEA, and NtBiA) to modify their deblocking feature in blocked isocyanates (BIs) and curing reaction under thermal curing conditions. Curing properties of clearcoats containing amine-based BIs were characterized at the normal curing temperature of 150 degrees C and were compared with those by the commercialized BI, Desmodur (R) PL350. The dissociation ability of the amine-based BIs was interpreted using the density functional theory (DFT) simulation under their optimized geometric configurations. The urethane reaction between isocyanate group in BIs and hydroxyl group in a hydroxyl-functionalized polyol binder within clearcoats was confirmed from the OH stretching absorbance data via Fourier-transform infrared (FT-IR) spectrometer. The real-time cross-linking dynamics of various clearcoats with amine-based BIs were comprehensively investigated using rotational rheometer and rigid-body pendulum tester. The surface mechanical properties of fully-cured clearcoat films were measured by nano-indentation and nano-scratch testers to address the crosslinked network formation caused by amine-based BIs. It is demonstrated that the amine-based BIs could be favorably applied to thermal curing process of clearcoats, based on their reactivity and curing performance.
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Collections - College of Engineering > Department of Chemical and Biological Engineering > 1. Journal Articles
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