Safety, health and environmental issues continue to drive the trend toward lower VOC coatings.
An important feature of this crosslinking monomer compared to epoxy, aziridine or isocyanate curing systems is its relatively low toxicity, which makes it especially attractive for high-performance, environmentally friendly, nonhazardous coatings. It is for these reasons that AAEM-containing waterborne coatings have gained such high interest as evidenced by recent patents2-5 and literature reports.6,7
Polymers containing acetoacetoxy (AcAc) and other functionalities containing active hydrogen atoms, such as diketo and acetoacetamide, crosslink rapidly at room temperature in the presence of diamines. An alkali-soluble polymer with AcAc functionality dissolved in water at high pH might therefore be expected to gel upon the addition of a soluble primary diamine. The coatings described herein are based on the discovery that certain alkali-soluble acrylic polymers with high levels of AcAc functionality will not gel upon the addition of diamine but rather will form stable, translucent colloidal dispersions. Such polymers are useful in their own right and can further serve as crosslinkable support resins for emulsion polymerization.8