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Cross‐linked coatings by co‐reaction of isocyanate–methoxymethyl melamine systems
Author(s) -
Ntsihlele E. S.,
Pizzi A.
Publication year - 1995
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1995.070550117
Subject(s) - isocyanate , melamine , polyol , polymer chemistry , chemistry , methanol , organic chemistry , polyurethane
Abstract Two‐components methoxymethyl melamine/isocyanate and three‐components methoxymethyl melamine/isocyanate/polyol coating systems were studied. Methoxymethyl melamine was shown to react with isocyanate groups through the carbocation formed by splitting within the methoxymethyl group. In three‐components systems, methoxymethyl melamine/polyol and methoxymethyl melamine/isocyanate rections appear to occur, but not isocyanate/polyol reactions. This was ascribed to the release from the methoxymethyl melamine/polyol reaction of methanol which reacts more rapidly than the polyol with the isocyanate group. A blocked isocyanate was then used whereby the methoxymethyl melamine reacts at an earlier stage and urethane formation is delayed. Introducing the blocked isocyanate, however, required significant increase in cure temperature for the isocyanate/polyol reaction, narrowing the cure temperature window of the system. © 1995 John Wiley & Sons, Inc.