Isocryl EP-550G is the ground version of Isocryl EP-550 resin
flakes. This GMA acrylic resin is the original matting hardener of
the Isocryl line that now includes EP-550/550G, EP-560 and EP-570.
Isocryl EP-550G can be formulated with low viscosity, linear,
carboxyl-functional polyesters having acid values 30-35 to generate
low-gloss, weatherable, TGIC-free powder coating systems. A typical
binder consists of 75 parts polyester and 25 parts Isocryl EP-550G.
Mechanical properties and chemical resistance are enhanced with the
use of Estron’s specialty additive ESCAT 22 in the formulation,
which is generally used at one-tenth the amount of the Isocryl
EP-550G. TGIC is not to be formulated with Isocryl EP-550G.
As with any raw material, laboratory evaluation is required for
each formulation to determine the best processing method and the
optimum concentration of the binder components. In addition to
matte finishes with Isocryl EP-550G, mid-gloss powder coatings are
possible with some formulation adjustments such as using two
polyesters of differing viscosities, or by addition of a
co-reactant such as Estron’s GMA-300.
The ability to adjust the 60° gloss from 5 to 50% is a key
attribute of Isocryl EP-550G. Additional formulating tips and
application data for Isocryl EP-550 (or EP-550G) are provided in
the Technical Briefs #1, #2, and #3.