Since GMA acrylic
powder resins are epoxy functional, any curing mechanism for epoxy
resins will also function with GMA resins. At this time the preferred
curative for GMA acrylic powder resins is dodecanedioic acid (DDDA) due
to its combination of favorable melting point, cure rate &
viscosity reduction. DDDA also provides cured coatings with excellent
clarity, chemical resistance and weatherability. Other polycarboxylic
acids or anhydrides may be used as curatives or additives to modify
cure rate or coating properties.
Many additives used in the powder coating
industry may also be used in GMA acrylic powder formulations. These
additives include: flow control agents (FCA), de-gassing agents, UVAs,
and HALS. For clearcoat applications, non-silica dispersed FCA's or
special solid FCA's are preferred. The selection of UVA/HALS can also
effect the yellowing and degree of outdoor durability.
Apart from their positive qualities GMA
powder coatings are known for a tendency to give brittlle coatings, to
cause craters in other powder chemistries, to have limited
pigmentability and to be difficult to matt. All of these issues can be
addressed with special resins or through formulation means.
Anderson Development Company and its parent
company Mitsui Chemicals Inc. have over 30 years experience with GMA
powder coatings for various applications, and would be glad to design
special resins or assist in formulating for specific coating
applications.
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