Crosslinking of acrylic latex coatings with cycloaliphatic diepoxide

Acrylic thermosetting latexes were synthesized using methyl methacrylate (M MA) and butyl acrylate (BA) with methacrylic acid (MAA) or a-hydroxyethyl m ethacrylate (HEMA). The MAA or HEMA was incorporated to provide the latexes with carboxyl or hydroxyl functionality, respectively. A cycloaliphatic di epoxide (3,4-epoxycyclohexyl methyl-3',4'-epoxycyclohexane carboxylate) was used to crosslink with hydroxyl or carboxyl functional latexes. The coatin gs were crosslinked as a function of temperature, time, and the amount of t he crosslinker. The crosslinking reactions were monitored using differentia l scanning calorimeter, IR spectroscopy, and dynamic mechanical thermal ana lysis. The coatings properties were evaluated in terms of water absorption, gel content, pencil hardness, and pull-off adhesion. The morphology of the latex coatings was studied using atomic force microscopy. The spectroscopi c and rheological data showed that the cycloaliphatic diepoxide effectively crosslinked both the hydroxyl and carboxyl functional latexes. Carboxyl la tex coatings were more reactive than hydroxyl latex coatings. The water res istance, solvent resistance, pencil hardness, and pull-off adhesion improve d with the crosslinking temperature, time, and the amount of the crosslinke r. (C) 1999 Elsevier Science Ltd. All rights reserved.