HIGH FLEX SUPER-WEATHERING TGIC COATING
Methods and systems for coating metal substrates are provided. The methods and systems include application of TGIC-based powder coatings that demonstrate superdurability without compromising flexibility.
1 . A powder coating system for forming a flexible and superweathering coating, comprising:
at least a first powder coating composition, comprising
a polyester resin composition;
at least one pigment;
about 1 to 10 wt % of at least one impact modifier, based on the weight of the total composition;
about 1 to 12 wt % of at least one hardener, based on the weight of the total composition; and
about 1 to 10 wt % of at least one stabilizing additive, based on the weight of the total composition.
2 . The system of claim 1 , wherein the polyester resin composition is an isophthalic based polyester resin.
3 . The system of claim 1 , wherein the polyester resin composition is an isophthalic-based TGIC-reactive polyester resin.
4 . The system of claim 1 , wherein the polyester resin composition comprises up to about 40 wt % of a linear polyester resin.
5 . The system of claim 1 , wherein the linear polyester resin is acrylate-modified.
6 . The system of claim 1 , wherein the linear polyester resin is alkyd-modified.
7 . The system of claim 1 , wherein the impact modifier is a core-shell composition.
8 . The system of claim 1 , wherein the core component of the impact modifier is selected from the group consisting of polymers of butadiene, co-polymers of butadiene and sytrene, (meth)acrylic monomers, co-polymers of butadiene and (meth)acrylic monomers, copolymers of butadiene, (meth)acrylic monomers, and combinations thereof.
9 . The system of claim 1 , wherein the shell component of the impact modifier is a grafted polymethylmethacrylate (PMMA) polymer.
10 . The system of claim 1 , wherein the pigment is TiO 2 .
11 . The system of claim 1 , wherein the superweatherable coating has 20° degree gloss retention of at least about 40%.
12 . The system of claim 1 , wherein the hardener is an isocyanate hardener.
13 . The system of claim 1 , wherein the stabilizing additive is a hindered amine light stabilizer.
14 . The system of claim 1 , wherein the stabilizing additive is a UV absorber.
15 . The system of claim 1 , wherein the stabilizing additive is a combination of one or more HALS and one or more UV absorbers.
16 . The system of claim 1 , wherein the substrate is an electrocoated surface.
17 . The system of claim 1 , wherein the substrate is an unprimed surface.
18 . The system of claim 1 , wherein the substrate is a primed surface.
19 . The system of claim 1 , wherein the substrate is cold rolled steel.