Thermoset coatings amine-cured systems

A wide variety of other specialty monomers are also used to provide specialized performance properties for coating applications. For example, amine functional monomers can be used to improve adhesion to aged alkyd substrates. Specialized monomers can also be used to improve exterior durability, for example VEOVA (vinyl ester of vesatic acid) monomers can improve the hydrolysis resistance of vinyl acetate polymers, and n-butyl methacrylate can be used to enhance the durabiHty of BA-MMA acrylics. Polymer hydrophobicity can be fine tuned by varying the levels of hydrophobic and hydrophilic monomers in the composition and styrene or ethyl hexyl acrylate are used to increase film hydrophobicity and reduce water permeability in BA-MMA systems. Specialty monomers are also used to provide specific chemical functionality to polymer compositions. For example, hydroxyethyl methacrylate can be used to provide hydroxyl functionality to acrylic resins, allowing these polymers to be used in cross-linkable thermoset coatings which cure via melamine chemistry. While specialty monomers are used at relatively low levels in polymer compositions, they frequently provide the performance features needed for the successful application of emulsion polymers in many coating areas. 

Water reducible acrylic resins are available to the coatings formulator as both thermoplastic, and thermosetting types. The thermoplastic acrylics film form by simple solvent evaporation and, therefore, cosolvent and amine selection are important. One of the cosolvents used must be a true solvent for the system and be less volatile. It must evaporate more slowly than water. This is to minimise the potential for blushing or flocculation that could be caused by having water as the last solvent to leave the film. The amine should also be volatile at ambient temperatures to minimise the retained water solubility, or sensitivity of the film after drying. This is particularly important since there is no curing reaction with thermoplastics. 

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