| 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 |
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https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17944 |
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 897 (10/1999) . - p. 127-133
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Effect of malamine-formaldehyde structure on cure response of thermoset coatings in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 897 (10/1999)
