Characteristics of dual-curable blocked isocyanate with thermal radical initiator for low-temperature curing of automotive coatings

Jung, Kevin Injoe; Kim, Beomjin; Lee, Dong Geun; Lee, Tae Hee; Choi, Seo Yeon; Kim, Jin Chul; Noh, Seung Man; Jung, Hyun Wook

doi:10.1016/j.porgcoat.2018.09.009

Cited by 20 publications

(10 citation statements)

References 33 publications

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“…50 BDTDHP and BDTHTP are two components of a commercial UV filter mixture called Tinuvin 400, which is widely used in various coatings, such as architectural coatings and automotive coatings. 51,52 This is the first identification of multiple triazine UV filters in typical indoor dust. Our findings clearly uncover the broad occurrences and prevalence of another emerging class of UV filters in general dwelling environments, likely due to their wide applications in personal care and polymeric products.…”

Section: ■ Results and Discussionmentioning

confidence: 90%

Identification of Triazine UV Filters as an Emerging Class of Abundant, Ubiquitous Pollutants in Indoor Dust and Air from South China: Call for More Concerns on Their Occurrence and Human Exposure

Liang

et al. 2022

Environ. Sci. Technol.

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Triazine UV filters are an important class of UV filters, but knowledge on their environmental occurrence and human exposure remains largely unknown. In this study, we performed a targeted analysis of 17 emerging triazine UV filters in indoor dust and indoor air from South China based on a newly developed LC–MS/MS method. A total of 12 of the 17 emerging triazine UV filters were first positively detected in the dust and air samples. Ethylhexyl triazone (EHT) and bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT) were identified as the most abundant compounds. The median total concentrations of triazine UV filters reached 3860 ng/g in indoor dust and 1590 pg/m3 in indoor air. Gas-particle partitioning analysis showed that triazine UV filters were predominant in the particle phase in ambient air. Significant concentration correlations were observed among most triazine UV filters. The estimated daily intake of triazine UV filters through dust ingestion and air inhalation for toddlers under high-end exposure scenarios was up to 839 ng/kg bw/day, but a lack of toxic thresholds hampers accurate risk assessment. Our work highlights another emerging class of UV filters that significantly contribute to indoor chemical mixtures and expresses concerns over their occurrence and human exposure.

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Section: ■ Results and Discussionmentioning

confidence: 90%

Identification of Triazine UV Filters as an Emerging Class of Abundant, Ubiquitous Pollutants in Indoor Dust and Air from South China: Call for More Concerns on Their Occurrence and Human Exposure

Liang

et al. 2022

Environ. Sci. Technol.

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“…The prepared pyrazole-based BIs (denoted as BI-DBP, BI-DMP, and BI-PYR) and BI-PL350 were individually mixed with the main HFUMO binder having an OH value of 125 mg KOH/g [16,17,38] (Table 1). They were mixed based on a molar ratio of 1.1:1 between the NCO group of each BI and OH group in the HFUMO.…”

Section: Formulation Of Clearcoats Containing Pyrazole-based Bismentioning

confidence: 99%

“…The macroscopic crosslinking evolution of clearcoat samples containing various pyrazole-based BIs was investigated in real time using a rotational rheometer (MCR-301, Anton Paar, Graz, Austria) [16,17]. Under the small-amplitude oscillatory shear mode with an angular frequency of 5 Hz and strain of 2% based on the measurement gap, the real-time storage modulus (G') was measured to clearly substantiate the growth of a crosslinked network.…”

Section: Real-time Measurement Of Crosslinking Behaviors Of Clearcoatsmentioning

confidence: 99%

“…In automotive original equipment manufacturer (OEM) coating processes, typical thermal curing conditions for clearcoats include curing at 150 • C for 30 min to induce the formation of a highly crosslinked coating layer [15][16][17]. Such curing conditions are most suitable for initiating and propagating urethane polymerization between a polyol binder and a thermal crosslinker.…”

Section: Introductionmentioning

confidence: 99%

“…The chemical structure of the substituent in the pyrazole-based blocking agents was varied to tune the deblocking behavior, which depends on the steric configuration effect of the blocking agents. The prepared thermal crosslinkers, pyrazole-based BIs, were mixed with a main binder-hydroxyl-functionalized urethane methacrylate oligomer (HFUMO) [15,16], which has hydroxyl groups on the chain. The thermally induced urethane reaction of clearcoat mixtures containing different pyrazole-based BIs was examined from changes in the OH stretching frequency in the Fourier transform infrared (FT-IR) spectral data before and after thermal curing.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Urethane Crosslinking by Blocked Isocyanates with Pyrazole-Based Blocking Agents on Rheological and Mechanical Performance of Clearcoats

et al. 2020

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A novel blocked isocyanate crosslinker was synthesized, and its applicability was investigated for the low-temperature curing of automotive clearcoats. Various pyrazole derivatives were prepared as blocking agents in isocyanate crosslinkers, which strongly affect the deblocking and curing properties of the urethane-bonded coating systems. The thermal curing properties of clearcoat samples containing a pyrazole-based blocked isocyanate crosslinker and polyol resin were characterized under two different temperature conditions (120 and 150 °C). The decrease in the amount of hydroxyl groups in the polyol before and after curing was expressed by the change in OH stretching frequency in the Fourier transform infrared (FT-IR) spectra. The real-time rheological storage moduli of the bulk clearcoat mixtures were measured via a rotational rheometer to determine the effect of pyrazole-based blocking agents on the curing dynamics. In addition, a rigid-body pendulum tester (RPT) was employed to investigate the curing behavior in the thin film form. The nano-indentation and the nano-scratch tests were conducted to examine the surface hardness and scratch resistance characteristics of the cured clearcoat films. The results show that a low-temperature curing system of clearcoats can be realized by tuning the curing temperature and reactivity of isocyanate crosslinkers blocked with pyrazole-based substituents.

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Synthesis and characterization of polyurethanes using 4-bromo-1H-pyrazole as a blocking agent

et al. 2023

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Characteristics of dual-curable blocked isocyanate with thermal radical initiator for low-temperature curing of automotive coatings

Cited by 20 publications

References 33 publications

Identification of Triazine UV Filters as an Emerging Class of Abundant, Ubiquitous Pollutants in Indoor Dust and Air from South China: Call for More Concerns on Their Occurrence and Human Exposure

Identification of Triazine UV Filters as an Emerging Class of Abundant, Ubiquitous Pollutants in Indoor Dust and Air from South China: Call for More Concerns on Their Occurrence and Human Exposure

Effect of Urethane Crosslinking by Blocked Isocyanates with Pyrazole-Based Blocking Agents on Rheological and Mechanical Performance of Clearcoats

Synthesis and characterization of polyurethanes using 4-bromo-1H-pyrazole as a blocking agent

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