[article]
| Titre : |
An accelerated test procedure for the evaluation of acid-etch resistance of coatings |
| Type de document : |
texte imprimé |
| Auteurs : |
George D. Vaughn, Auteur ; James B. Downie, Auteur ; Patricia E. Ferrell, Auteur |
| Année de publication : |
2004 |
| Article en page(s) : |
p. 93-96 |
| Note générale : |
bibliogr. |
| Langues : |
Anglais (eng) |
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Acid etch, or environmental etch, is a defect that can occur in any exterior paint finish. However, it is a major concern for the automotive industry. The result of acid etch may appear as rings on a car's finish. These rings may seem like water spots, but in actuality, damage has been done to the finish, so washing does not remove the rings. Certain geographical areas are affected more than others - areas adjacent to heavily industrialized cities usually have high incidents of acid etch complaints.
Historically, isocyanate-crosslinked coatings outperformed melamine-crosslinked coatings for acid-etch resistance. However, melamine-crosslinked coatings are still in use because they are more cost effective and have better mar resistance.
This article details an accelerated acid-etch test. A similar test has been mentioned by Gregorovich and Hazan. They compared the acid-etch test to actual Jacksonville test date. It has been the automotive industry that has primarily studied and tried to eliminate this paint defect.
This relatively simple test yields a pair of values, the minimum spot temperature (MST) and the scaled acid value. THese values are used to rank the severity of the acid damage to a coating. The test procedure uses a BYK-Gardner gradient oven. In addition, steel panels (4"X22.5"x0.032") are required (these are the standard size panels used in the gradient oven). To make the comparison of coatings in this brief study easier, one acrylic polyol and either an isocyanate resin or a melamine resin were used as the crosslinker. |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12054 |
in PAINTINDIA > Vol. LIV, N° 8 (08/2004) . - p. 93-96
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