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Article: Effect of Melamine-Formaldehyde Structure on Cure Response of Thermoset Coatings.
- Article from:
- The Journal of Coatings Technology
- Article date:
- October 1, 1999
- Author:
CopyrightCOPYRIGHT 1999 Federation of Societies for Coatings Technology. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Shih-Bin Lee [*]
INTRODUCTION
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[([CH.sub.2][OCH.sub.3])sub.2]] or singly substituted [-N(H)([CH.sub.2][OCH.sub.3])]. 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 ...