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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Characterization of clearcoats containing phosphoric acid-functionalized acrylic polyols for automotive precoated metal sheet coatings / Jae Young Lee in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 11, N° 5 (09/2014)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 11, N° 5 (09/2014) . - p. 697-710 Titre : Characterization of clearcoats containing phosphoric acid-functionalized acrylic polyols for automotive precoated metal sheet coatings Type de document : texte imprimé Auteurs : Jae Young Lee, Auteur ; Myung Seon Yi, Auteur ; Ho Cheol Jeong, Auteur ; Jung Teag Kim, Auteur ; Joon Hyun Nam, Auteur ; Seung Man Noh, Auteur ; Hyun Wook Jung, Auteur Année de publication : 2014 Article en page(s) : p. 697-710 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Automobiles -- Vernis Tags : 'Automotive  clearcoat'  'Precoated  metal  sheet'  'Phosphoric  acid-functionalized  acrylic  polyols'  'Glycidyl  methacrylate'  acid-GMA  modified  'Deep-draw  formability'  'Crosslinking  networks' Index. décimale : 667.9 Revêtements et enduits Résumé : In this study, the various physical and mechanical properties of clearcoats prepared through a new crosslinking method were investigated. The method was aimed at developing clearcoat systems to improve the deep-draw processing and formability performance in precoated metal (PCM) sheets for automotive applications. From phosphoric acid-functionalized acrylic polyols (PAFAPs) first synthesized in this study and glycidyl methacrylate-modified acrylic copolymer (GMAMAC), phosphoric acid-GMA modified acrylic polyols (PAGMAPs) were newly prepared as new binders in automotive clearcoats. Several clearcoats were formulated with different molecular weights and hydroxyl contents from PAFAPs and GMAMAC. Using clearcoats themselves, the crosslinking reactions for these clearcoats were compared by evaluating the curing behaviors with a rigid-body pendulum test (RPT) and the changes of chemical structures via attenuated total reflectance FTIR spectroscopy. The mechanical properties of the clearcoats were systematically characterized, using dynamic mechanical analysis (DMA) and universal testing machine analysis (UTM). Also, various tests were carried out using PCM sheets by depositing clearcoats above the same PCM-based primers and basecoat layers on galvanized steel. The fracture and deformation patterns related to surface damages on the clearcoat surface were visualized using a nano-scratch test, in association with atomic force microscopy. In particular, deep-draw processing tests, based on forming process simulations, were employed to scrutinize the effect of clearcoats developed in this study on the forming feature in PCM sheets. From the results of RPT, DMA, and UTM tests, the primary crosslinking networks of PAGMAPs from the synthesized PAFAPs and GMAMAC, and also succeeding secondary crosslinking networks between PAGMAPs and blocked isocyanates, were closely correlated with the degree of crosslinking (X c), in accordance with the molecular weight between crosslinks (M c), and glass transition temperature (T g). As a result, the presented clearcoats with a long pendulum period, a low rubbery modulus, and a large tensile strain value, which are the significant factors for developing automotive PCM sheet technology, have truly demonstrated more superior formability during the deep-draw process. It is confirmed that properties of clearcoats with toughness and flexibility could be optimally controlled by PAGMAPs for automotive coatings. Note de contenu : - EXPERIMENTAL : - Materials - Characterization methods - RESULTS AND DISCUSSION : -Reactivity analysis by FTIR spectroscopy - Curing behavior by RPT - Viscoelastic and mechanical properties - Water-swelling and gel-fraction properties - Tensile properties - Deformations of clearcoat surfaces - Deep-draw processing formability DOI : 10.1007/s11998-014-9589-4 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-014-9589-4.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=22052 [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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Scratch and recovery characteristics of automotive clearcoats containing blocked polyisocyanate crosslinkers / Seung Man Noh in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 12, N° 1 (01/2015)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 12, N° 1 (01/2015) . - p. 85-95 Titre : Scratch and recovery characteristics of automotive clearcoats containing blocked polyisocyanate crosslinkers Type de document : texte imprimé Auteurs : Seung Man Noh, Auteur ; Joon Hyun Nam, Auteur ; Jung Kwon Oh, Auteur ; Hyun Wook Jung, Auteur Année de publication : 2015 Article en page(s) : p. 85-95 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Automobiles -- Vernis Caractérisation Echantillonnage Polyisocyanates Polymères à silane modifié Résistance à l'abrasion Réticulation (polymérisation) Index. décimale : 667.9 Revêtements et enduits Résumé : Scratch characteristics and self-recovery behaviors of automotive clearcoats including newly designed silane-modified blocked polyisocyanate (SMBI)1 as an organic–inorganic hybrid crosslinker were compared with those with the commercially well-known crosslinkers such as blocked HDI-based and blocked IPDI-based polyisocyanates. To extensively scrutinize the effects of various crosslinkers with different chemical structures on the chemical and mechanical properties of clearcoats themselves, rigid-body pendulum tester analysis, creep-recovery analysis, and FTIR analysis were performed, resulting in a noticeable variation in curing features and crosslinking networks. Employing the overall coating systems by depositing clearcoats with different crosslinkers above the same undercoats on galvanized steel, the scratch behaviors on the surface of the outermost clearcoat layer were examined via the nano-scratch tester for scratch depth profiles and atomic force microscopy for three-dimensional scratch images, under various self-reflow temperatures and duration time periods. The results demonstrated that the SMBI crosslinker induced a considerably higher degree of crosslinked networks, through the reaction of urethane bonds and silanol bonds in clearcoats, in comparison with the blocked HDI and IPDI polyisocyanates. Also, the recoverable behaviors of scratched clearcoats containing different blocked polyisocyanates were affected by the intrinsic chemical structures of crosslinkers, as well as scratch-recovery conditions such as external temperatures and duration times. Note de contenu : - EXPERIMENTAL : Preparation of clearcoat samples - Characterization methods - RESULTS AND DISCUSSION : Curing analysis by RPT - FTIR analysis - Creep-recovery properties - Scratch resistance and recovery characteristics DOI : 10.1007/s11998-014-9617-4 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-014-9617-4.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23209 [article]

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The effect of thermal radical initiator derived from O-imino-isourea on thermal curing characteristics and properties of automotive clearcoats / Ji Won Hwang in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 12, N° 1 (01/2015)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 12, N° 1 (01/2015) . - p. 177-186 Titre : The effect of thermal radical initiator derived from O-imino-isourea on thermal curing characteristics and properties of automotive clearcoats Type de document : texte imprimé Auteurs : Ji Won Hwang, Auteur ; Kyung Nam Kim, Auteur ; Seung Man Noh, Auteur ; Hyun Wook Jung, Auteur Année de publication : 2015 Article en page(s) : p. 177-186 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Amorceurs (chimie) Automobiles -- Vernis Hydroxyle En chimie organique, un hydroxyle (ou oxhydryle) peut désigner deux entités. Un groupement -OH, appelé aussi hydroxy, qui se rencontre en particulier dans les alcools et les phénols. Un radical : HO^{\bullet}. Il est produit par exemple lors de réactions de dissociation de peroxydes, en présence d'ions de métaux de transition (Fe(II), Cu(I), réaction de Fenton), de chauffage ou de rayonnement. Mélamine La mélamine, de nom chimique 1,3,5-triazine-2,4,6-triamine, est parfois dénommée cyanuramide ou cyanurotriamine. Sa formule brute est C3H6N6. Les "résines mélamine-formaldéhyde" ou "mélamine-formol" (sigle MF) sont appelées "mélamine" dans le langage courant. Elles font partie de la famille des aminoplastes qui regroupe des résines thermodurcissables aminées, issues d'un comonomère tel l'urée ou la mélamine, parfois le thiocarbamide, le cyanamide hydrogène ou le dicyandiamide ; le second comonomère étant le formaldéhyde. Méthacrylate d'uréthane Oligomères Polyaddition Résistance à l'abrasion Réticulation (polymérisation) Rhéologie Vernis -- Propriétés mécaniques Index. décimale : 667.9 Revêtements et enduits Résumé : Curing characteristics of melamine-based automotive clearcoats with or without thermal radical initiator (TRI) derived from an O-imino-isourea have been examined by means of their real-time rheological properties during a thermal curing process. By changing functionalities of reactive sites at hydroxyl groups and unsaturated double bonds in hydroxyl-functionalized urethane methacrylate oligomer as a main binder, the effect of TRI on various properties of thermally cured clearcoats has been compared by means of rheological, rigid-body pendulum, ultra nano-indentation, and nano-scratch tests. It was found that a small portion of TRI significantly enhanced the final elastic modulus of clearcoats with the lower content of hydroxyl groups and considerably shortened curing time, implying the formation of denser crosslinked networks inside clearcoats by the free-radical polymerization at relatively lower curing temperature. These results were directly linked with the improvement of their mechanical properties such as indentation hardness and scratch resistance. TRI plays a key role in desirably controlling the rheological and mechanical properties of clearcoats under insufficient thermal curing conditions. Note de contenu : - EXPERIMENTAL : Preparation of clearcoat samples - Characterization methods - RESULTS AND DISCUSSION : Thermal characteristics of clearcoats - Comparison of elastic rheological data for clearcoats with or without TRI - Curing characteristics by RPT tests - Mechanical properties of cured clearcoats DOI : 10.1007/s11998-014-9619-2 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-014-9619-2.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23216 [article]

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