Application of polycarbonate diol containing hindered urea to polyurethane-based clearcoats for tuning of scratch-healing properties / Dong Geun Lee in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 17, N° 4 (07/2020)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 17, N° 4 (07/2020) . - p. 963-976 Titre : Application of polycarbonate diol containing hindered urea to polyurethane-based clearcoats for tuning of scratch-healing properties Type de document : texte imprimé Auteurs : Dong Geun Lee, Auteur ; Sujin Sung, Auteur ; Dae Geun Oh, Auteur ; Young Il Park, Auteur ; Sang-Ho Lee, Auteur ; Jin Chul Kim, Auteur ; Seung Man Noh, Auteur ; Hyun Wook Jung, Auteur Année de publication : 2020 Article en page(s) : p. 963-976 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse mécanique dynamique Nanotechnologie Polycarbonates Polymères autoréparants Polyuréthanes Rayures Revêtement autoréparant:Peinture autoréparante Rhéologie Vernis Index. décimale : 667.9 Revêtements et enduits Résumé : Newly synthesized polycarbonate diols containing hindered urea (PCD-HUs) were employed to modify the scratch-healing properties of conventional two-component clearcoats. To elucidate their contributions to the crosslinking properties of the coatings under conventional thermal curing (150°C), the real-time rheological properties of the clearcoat mixtures were measured using a rotational rheometer in the small-amplitude oscillatory shear mode. A dynamic mechanical analysis was carried out to compare the thermomechanical properties of the cured clearcoat free films. PCD-HU, a key component for the tuning of the scratch-healing, was further identified by analyzing the clearcoat layer cured over a phosphated metal substrate with undercoats such as primer and basecoat as a precoated metal (PCM) sheet. Elastic recovery and scratch profiles of the outermost clearcoat layer in the PCM sheet were acquired through nano-indentation and nano-scratch tests by gradually increasing the quantitative normal force. Finally, the healing patterns of the scratches on various clearcoat layers at a certain normal force were visualized by three-dimensional and one-dimensional cross-cut images using atomic force microscopy under specified temperature and healing time conditions. The surface durability provided by the PCD-HU in the clearcoat layer was confirmed by repeated scratching and healing tests on the same surface positions. Therefore, the coating layer containing HU, which possessed similar surface mechanical properties to those of conventional references, exhibited better scratch-healing performance. Note de contenu : - EXPERIMENTAL METHODS : Preparation of PCD-HUs - Preparation of clearcoat coatings and their property measurements - Elastic recovery and scratch-healing properties of the clearcoat layers - RESULTS AND DISCUSSION : Real-time rheological properties of the clearcoats during the thermal curing - Thermomechanical properties of the clearcoat free films - Indentation and related elastic recovery properties of the cured clearcoat layers in the PCMs - Scratch properties of the cured clearcoat layers in the PCMs - Scratch-healing pattern analysis by AFM - Durability features through repeated scratching and healing procedures DOI : https://doi.org/10.1007/s11998-019-00316-0 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-019-00316-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34384 [article]

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Influence of functional group content in hydroxyl-functionalized urethane methacrylate oligomers on the crosslinking features of clearcoats / Young-Gun June in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 1 (01/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 1 (01/2021) . - p. 229-237 Titre : Influence of functional group content in hydroxyl-functionalized urethane methacrylate oligomers on the crosslinking features of clearcoats Type de document : texte imprimé Auteurs : Young-Gun June, Auteur ; Kevin Injoe Jung, Auteur ; Dong Geun Lee, Auteur ; Subin Jeong, Auteur ; Tae-Hee Lee, Auteur ; Young Il Park, Auteur ; Seung Man Noh, Auteur ; Hyun Wook Jung, Auteur Année de publication : 2021 Article en page(s) : p. 229-237 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Basses températures Liants Méthacrylate d'uréthane Oligomères Réticulants Réticulation (polymérisation) Revêtements organiques Vernis Index. décimale : 667.9 Revêtements et enduits Résumé : Crosslinking characteristics and surface mechanical properties of radical and urethane dual-curable clearcoats were investigated by changing quantities of C=C bonds and OH groups in hydroxyl-functionalized urethane methacrylate oligomer (HFUMO) resins. The isocyanate blocked with a thermal radical initiator (BL-Tri-cHD) was utilized as a hybrid dual-curable thermal crosslinker to expedite the crosslinking of the main resin. The dual reactions between various HFUMO resins and BL-Tri-cHD were efficiently monitored via Fourier transform infrared spectroscopy to measure the peaks before and after curing. The influence of each functional group (C=C bond or OH group) in HFUMO on the initiation and development of crosslinking in dual-curable clearcoats was investigated by real-time measurements using rotational rheometer and rigid body pendulum tester. Temperature-dependent mechanical properties of cured films were confirmed through dynamic mechanical analysis. The surface mechanical properties of cured clearcoat films were also evaluated via the nanoindentation and nanoscratch tests, demonstrating the variation in surface resistance with respect to the C=C bond content and the OH value. Thus, the low-temperature curing and desired mechanical properties of clearcoats can be optimized by adjusting the content of the functional groups in a HFUMO and using a dual-curable crosslinker to simultaneously generate both radical and urethane crosslinking reactions. Note de contenu : - EXPERIMENTAL METHOS : Synthesis of HFUMOs and blocked isocyanate using a TRI (BL-Tri-cHD) - Formulation of clearcoats with various HFUMO resins - Variations in functional groups by FTIR analysis - Real-time crosslinking behaviors of HFUMO-based clearcoats - Dynamic mechanical analysis of cured films - Surface mechanical properties of cured films - RESULTS AND DISCUSSION : FTIR analysis of clearcoats with varying quantities of functional groups in HFUMOs - Rheological analysis of crosslinking behavior - Analysis of curing behaviors using RPT - Dynamic mechanical analysis - Indentation depth profiles - Scratch depth profiles - Table 1 : Formulation of clearcoat mixtures with various HFUMOs with different contents of C=C bond and OH group DOI : https://doi.org/10.1007/s11998-020-00398-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-020-00398-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35365 [article]

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