Cathodic electrodeposition of self-curable polyepoxide resins based on cardanol / Raju Pramod Kumar in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 8, N° 5 (10/2011)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 8, N° 5 (10/2011) . - p. 563-575 Titre : Cathodic electrodeposition of self-curable polyepoxide resins based on cardanol Type de document : texte imprimé Auteurs : Raju Pramod Kumar, Auteur Année de publication : 2011 Article en page(s) : p. 563-575 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cardanol Couches minces Dépôt électrolytique Epaisseur -- Mesure Epoxydes Formaldéhyde Revêtements:Peinture Index. décimale : 667.9 Revêtements et enduits Résumé : Cathodic electrodeposition (CED) behavior and film properties of coating binders as modified polyepoxide resins based on cardanol, a constituent of Cashew Nut Shell Liquid (CNSL), have been studied. These coating binders were synthesized by epoxidation of cardanol–formaldehyde novolacs (CNs) with epichlorohydrin and subsequently modified with secondary amine to make them water-thinnable by neutralization with acetic acid, and suitable for CED. Laboratory synthesized coating binders, modified, epoxidized cardanol–formaldehyde novolacs (MECNs), were cathodically electrodeposited on pretreated MS panels to investigate their electrodeposition behavior and film properties of deposited coating binders. Among the nine MECNs prepared by varying molar ratios of cardanol to formaldehyde as well as ECN to DEtOA, only seven MECNs (MECN1, MECN2, MECN3, MECN6, MECN7, MECN8, and MECN9) were water-soluble and electrodepositable, whereas MECN4 and MECN5 were not water soluble, and hence not considered for further studies. These seven MECNs were used for the study of their electrodeposition characteristics, such as electrodeposition yield (ED yield), coulombic yield (CY), dry film thickness (DFT), and properties of their deposited films. The most suitable molar ratio of ECN:DEtOA for the preparation of MECNs was found to be 1:1. The CN prepared by using cardanol and formaldehyde in the molar ratio of 1:0.7 was used for the preparation of ECN2 and MECN2 prepared from this was found to be the most suitable in terms of deposition behavior and overall film properties. The film of MECN2 electrodeposited at constant voltage (100 V) was found to be the best in terms of film properties along with corrosion resistance, as it passed 800-h exposure to salt spray atmosphere. MECN2 was optimized for its electrodeposition characteristics like ED yield as 3.62 mg/cm2, CY as 35.87 mg/C, and DFT as 25.26 μm. Through a wide cure window, the films of MECN2 were found to be self-curable at an optimum cure schedule of 160°C/30 min. The electrodeposited films of MECNs had good physical, chemical, and corrosion resistance properties, but demonstrated low resistance to xylene, in particular. The study emphasized the electrodeposition behavior and film properties of the prepared MECN resins as binders for CED coating formulations, which were self-curable without using any external crosslinker. The self-curing of the deposited films was achieved via a novel self-curing mechanism, i.e., one molecule chemistry through anionic polymerization. The prepared epoxide resins as MECNs could be cathodically electrodeposited as primer coat for the protection of metallic substrates against corrosion. Note de contenu : EXPERIMENTAL : Materials - Evaluation of film properties - General mechanisms of cathodic electrodeposition - Experimental design : cathodic electrodeposition of binders - Preparation of test panels - Preparation of electrolytic composition - Cathodic electrodeposition of coating binders derived from cardanol as MECNs. RESULTS AND DISCUSSION : Cure characteristics of deposited coating binders as MECNs - Optimization of the electrodeposition parameters - Current density - Electrodeposition yield - Coulombic yield - Dry film thickness - Kinetics of films growth during cathodic electrodeposition - Specific conductivity of the deposited films - measurement of gloss - Evaluation of film properties - Physical properties - Chemical resistance properties. DOI : 10.1007/s11998-011-9337-y En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-011-9337-y.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12232 [article]

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Synthesis and characterization of water-thinnable thermosetting acrylic resins for low-cure surface coatings / Ganesh Datt Bajpai in PAINTINDIA, Vol. LVII, N° 8 (08/2007)

[article]  inPAINTINDIA > Vol. LVII, N° 8 (08/2007) . - p. 75-82 Titre : Synthesis and characterization of water-thinnable thermosetting acrylic resins for low-cure surface coatings Type de document : texte imprimé Auteurs : Ganesh Datt Bajpai, Auteur ; Raju Pramod Kumar, Auteur Année de publication : 2007 Article en page(s) : p. 75-82 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Basses températures Caractérisation Polyacryliques Polymères -- Synthèse Réticulation (polymérisation) Revêtements:Peinture Thermodurcissables Index. décimale : 667.9 Revêtements et enduits Résumé : Among the various binders used for industrial finishes, thermosetting acrylics (TSAs) are gaining importance. There are two main reasons for this; firstly they possess inherently superior properties; such as water clear appearance, colour retention, good durability, low pigment reactivity, excellent chemical resistance and excellent flexibility. Secondly, thermosetting acrylics provide greater formulation latitude as they can be tailor made to suit specific applications. Presently, thermosetting acrylics are commonly used in the two major forms: (a) Solvent soluble thermosetting acrylics for conventional solids coatings. (b) Thermosetting acrylics for high solids coatings. . In the present work, water-thinnable acrylic resins have been developed wherein water is used in place of volatile organic solvent which is the main source of VOC emission. Water-thinnable thermosetting acrylics are getting more prominence day after day because of their eco-friendly nature, cost effectiveness and superior films performance. However, ordinary water-thinnable thermosetting acrylic resins cure at high temperature (≈120-150°C) and hence involve high energy consumption. Through this work, efforts have also been directed towards developing such water-thinnable thermosetting acrylic resins which can be cured at lower temperature to yield low-cure surface coatings. For achieving this, a series of TSA resins were prepared by reacting 2-hydroxy ethyl methacrylate (HEMA) and acrylic acid (AA) as monomers in butanol as solvent in presence of benzoyl peroxide as initiator. The prepared TSA resins were made water soluble by neutralizing with ammonia solution. The coating films-were then baked at 90°C for 30 minutes to effect film cure. Cured films were evaluated for their various optical, mechanical and chemical resistance properties to ascertain the commercial utility of low-temperature curable water-thinnable TSA resins. Note de contenu : Classification of TSA - Experimental : Materials - Synthesis - Analysis - Preparation of coating films and their curing - Results & discussion : IR-spectra - Evaluation of film properties - Mechanical properties Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11500 [article]

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