固化(化学)
咪唑
异氰酸酯
傅里叶变换红外光谱
材料科学
倍半硅氧烷
动态力学分析
聚氨酯
红外光谱学
高分子化学
化学
化学工程
复合材料
有机化学
聚合物
工程类
作者
Moonhyun Choi,Maeng Gi Kim,Kevin Injoe Jung,Tae-Hee Lee,Miran Ha,Woochan Hyung,Hyun Wook Jung,Seung Man Noh
出处
期刊:Coatings
[MDPI AG]
日期:2020-10-13
卷期号:10 (10): 974-974
被引量:15
标识
DOI:10.3390/coatings10100974
摘要
For the application of low-temperature curing on automotive clearcoats, isocyanate cross-linkers blocked with imidazole derivatives were newly synthesized. The effect of the alkyl groups in the imidazole derivatives on the deblocking behavior and curing kinetics was investigated. The free isocyanate groups exposed by the deblocking of imidazole-based blocking agents were monitored by real-time Fourier-transform infrared spectroscopy. The bond dissociation energy, activation energy of deblocking, and H–N distance were interpreted through density functional theory simulation of various imidazole-based blocked isocyanates. To evaluate their applicability to automotive clearcoats, the synthesized imidazole-based blocked isocyanates were mixed with a polyol binder containing hydroxyl groups, and the clearcoat samples were cured at relatively low curing temperatures (100, 110, and 120 °C). The real-time storage modulus was measured using a rotational rheometer to elucidate the thermal curing dynamics by the blocking agents. In addition, the surface hardness of the cured clearcoat layers, which is affected by the chemical structure of the imidazole derivatives, was evaluated by nanoindentation test. In-depth analyses of the deblocking behaviors and thermal curing properties of clearcoats using imidazole-based blocked isocyanates demonstrated that the newly developed coating system could be suitably applied for the development of low-temperature curing technology.
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