22 августа, 2015 
Malyar These products have acid values in the region of 60-80mg KOH/g and can be crosslinked with either —
a) an epoxy resin catalysed with a metal soap such as zinc octoate (0.5-1.5% metal base on acrylic resin solids)
or
b) up to 20% of a hexamethoxymethyl melamine and acid catalysed with p-toluene sulphonic acid. Up to 5% addition of an epoxy resin aids substrate adhesion. This system was widely used in DWI basecoats, but today this market, in the UK, for example, has moved entirely to water based systems.
Solvent based carboxyl acrylics in Europe continue to be used as base coats in some 3 piece can applications, where they are applied at film weights of lOmg/m and cured for 10 minutes @ 190-200°C.
Flexible acrylamide based acrylic resins, crosslinked with 5-10% of an epoxy resin such as Epikote®1001 (Shell Chemicals) are used in sheet fed applications for caps, closures and other deep draw applications such as pudding basins. Acrylamide based resins have a better balance of flexibility and drawing properties combined with process resistance (retortable).
Hydroxyl functional acrylics can be crosslinked by either blocked isocyanates or aminoplasts, particularly melamines and benzoguanamines. Some acid functionality will be present to improve adhesion. Hydroxy acrylates or methacrylates can both be used and the choice may depend upon cost and Tg required. The former tend to give softer films. Stoving conditions will vary according to the crosslinking mechanism, but the commonly encountered conditions for other systems are used.
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