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Effect of malamine-formaldehyde structure on cure response of thermoset coatings / Loren W. Hill in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 897 (10/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 897 (10/1999) . - p. 127-133 Titre : Effect of malamine-formaldehyde structure on cure response of thermoset coatings Type de document : texte imprimé Auteurs : Loren W. Hill, Auteur ; Shih-Bin Lee, Auteur Année de publication : 1999 Article en page(s) : p. 127-133 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Matériau  revêtement'  Peinture  Thermodurcissable  Réticulant  'Mélamine  résine'  Ethérification  Durcissement  Polyol  'Acrylique  dérivé  polymère'  'Ester  'Propriété  mécanique'  Feuil  'Etude  expérimentale' Index. décimale : 667.9 Revêtements et enduits Résumé : Reactivity of etherified melamine-formaldehyde (MF) resins with polyol binders depends on the pattern of substitution on off-ring nitrogen atoms. These sites can be doubly substituted [-N(CH2OCH3)2] or singly substituted [-N(H)(CH2OCH3)]. The (N-H) portion of singly substituted sites is referred to as an imino group. The main finding of this work is that acid catalyzed cure response is improved greatly when the imino content is reduced to very low levels. The effect of degree of substitution on MF basicity and the site of protonation, ring, or side chain are key elements in the explanation of this cure response behavior. Properties were determined for films cured for 30 min at various temperatures with constant catalyst level and type (0.5 phr paratoluenesulfonic acid). Resins of varying imino content were used. With the MF resin of lowest imino content, extensive cure of acrylic and polyester polyols was observed at cure temperatures as low as 180°F (82°C). Paint tests of hardness and solvent resistance were useful for determining cure response. Dynamic mechanical analysis (DMA) on free films also indicated cure response differences. Storage modulus values from DMA were used to calculate crosslink densities of the thermoset films. Note de contenu : - EXPERIMENTAL : Materials - Film preparation and cure - Test methods - RESULTS : Paint test results-acrylic films - Paint test results-polyester films - DMA results-acrylic films - DMA results-polyester films - DISCUSSION : Basicity and ring protonation - Co-condensation and self-condensation - Cure response with weak catalyst or no catalyst Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17944 [article]

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Crosslinking of epoxy-modified phenol novolac (EPN) powder coatings : particle size and adhesion / B. D. Pennington in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 897 (10/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 897 (10/1999) . - p. 135-142 Titre : Crosslinking of epoxy-modified phenol novolac (EPN) powder coatings : particle size and adhesion Type de document : texte imprimé Auteurs : B. D. Pennington, Auteur ; J. C. Grunlan, Auteur ; M. W. Urban, Auteur Année de publication : 1999 Article en page(s) : p. 135-142 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : These studies were undertaken to examine how particle size of epoxy phenol novolac (EPN) powder coatings may affect adhesion to metal substrates. Particle sizes of 21 and 83 ?m diameter were utilized. DSC analysis shows that the activation energies of crosslinking for the 21 ?m particle size is 41 kJ/mol and 58 kJ/mol for 83 ?m particle size which is attributed to the effect of particle size, and time-temperature-particle size (TTPS) parameters are used to describe powder-liquid-solid film transformation process. Although, the TTSP term represents a combination of intrinsic and extrinsic properties. We believe that this is the TTPS term that adequately describes the processes in which, in order for crosslinking reactions to occur, particles must initiate the flow. Quantitative attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopic analysis was used to follow crosslinking processes by monitoring the decrease of oxirane concentration, and showed that for thermal cure at 185°C for 20 min, the oxirane concentration decreases at a similar rate for 21 ?m and 83 ?m particle sizes. The results of pull-off adhesion measurements from an Al substrate show that when the 21 ?m particle size is crosslinked for 10 min at 110, 140, and 170°C, adhesion is consistently higher than for the same coating system at 83 ?m particle size. This difference is attributed to the finite time required for powder particles to reach a proper melt viscosity, followed by reactions of functional groups leading to crosslinking. Extended cure times to 120 min for the 83 ?m particle resulted in adhesion similar to the 21 ?m particle size. Note de contenu : - Sample preparation - DSC measurements - Spectroscopic measurements - Adhesion measurements Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17945 [article]

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Effects of additives on the performance of two-component waterborne polyurethane coatings / Sharon Xudong Feng in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 897 (10/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 897 (10/1999) . - p. 143-149 Titre : Effects of additives on the performance of two-component waterborne polyurethane coatings Type de document : texte imprimé Auteurs : Sharon Xudong Feng, Auteur ; Phil Lunney, Auteur ; Rebecca Wargo, Auteur Année de publication : 1999 Article en page(s) : p. 143-149 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Matériau  revêtement'  'Peinture  eau'  deux  constituants'  Polyuréthane  Adjuvant  'Relation  composition  propriété'  'Propriété  rhéologique'  Viscosité  mécanique'  optique'  Feuil  Dureté  Brillant  chimique'  'Résistance  'Etude  expérimentale' Index. décimale : 667.9 Revêtements et enduits Résumé : The effects of various additives and solvents on a coating's performance in a two-component waterborne polyurethane coating system are studied using a statistical experimental design method. Using a blocked arrangement of fractional factorial design matrices, six different independent variables, including the use of different additives, catalysts, as well as solvents at different levels, were examined for their effects on various coating performance parameters, such as gloss, hardness, viscosity, and chemical resistance. Statistical analysis revealed several significant effects of these additives on the coating performances. Most importantly, several two-factor interactions between additives were also found to significantly influence the performance properties of the coating. These interactions could be very difficult to detect using traditional one-at-a-time experimental approaches. The information obtained from this study could be used for designing coating systems with superior performance properties. Note de contenu : - EXPERIMENTAL : Materials - Formulation and application - Evaluation - RESULTS AND DISCUSSION : Continuous response - Categorical response - Coorelation between the continuous and categorical parameters - Correlation between earlier hardness and chemical resistance to coffee, acetone, and ethanol Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17946 [article]

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