TEXTURED EPOXY POWDER COATING COMPOSITIONS FOR WOOD SUBSTRATES AND METHOD OF COATING WOOD THEREWITH

Thermosetting powder coating compositions adapted to form a grainy textured finish on heat sensitive substrates, especially wood products, such as particle board, conductive particle board, and medium density fiber board, without damaging the substrates comprise an epoxy resin, particularly bisphenol A type epoxy resins having low viscosities, a curing agent comprising an adduct of an imidazole or substituted imidazole and an epoxy resin, a texturing agent, a flow control agent, optional extender, and optional pigment. The thermosetting powder coatings have a cure time/temperature ranging from about 30 seconds at about 350 degree F peak substrate temperature down to about 20 minutes at about 225 degree F peak substrate temperature which provides for either a rapid cure or low bake temperature to prevent excessive heat exposure to the heat sensitive substrate, resulting in substantially no physical or chemical degradation of the heat sensitive substrate during baking. The powder coating are applied to heat sensitive substrates, especially wood products, through electrostatic spraying onto the substrate followed by heating to cure the texture finish uniformly on the surfaces and edges of the substrate. Electrostatic spraying is performed with a triboelectric or corona spray gun and heat curing is performed with a high intensity infrared oven, a convection oven, or combination. Coated heat sensitive substrates having continuous grainy textured finishes that are excellent for hiding substrate surface defects and later appearing scratches are obtained. Composiciones de revestimiento en polvo termoendurecibles para formar un acabado texturizado granuloso sobre substratos térmicamente sensibles, especialmente productos de madera, tales como tabla en partículas, tabla de partículas conductora y tabla de fibra de densidad media, sin dañar los substratos, comprenden una resina epoxi, particularmente resinas epoxi de tipo de bisfenol A, que tienen viscosidades bajas, ya sea un agente de curado catalítico que comprende un imidazol, un imidazol substituido, o aducto de un imidazol o imidazol substituido y una resina epoxi, o un agente de curado que comprende un aducto de una poliamina y una resina epoxi, o una combinacion del agente de curado catalítico y agentes de curado, un agente de texturizacion, un agente de control de flujo, extendedor opcional, y pigmento opcional. Los revestimientos en polvo termoendurecible tienen un tiempo/temperatura de curado que varía de