Ultra-violet cure coating

摘要

Several low observable aqueously dispersed polymeric materials with dual cure properties utilizing both ambient and UV curing modalities are provided. Compositions are suitable for coating a substrate such as those used in military, hunting, or other applications for which low visibility is desired. A water dispersible low observable curable composition includes an aqueously dispersed hydroxyl functional polyurethane resin, an aqueously dispersed urethane acrylate resin; and one or more low solar absorbing pigments. In some embodiments, the acrylate resin present at less than 50% total resin weight. Preferred pigments include those that are cobalt free, do not absorb significant UV radiation during cure, and provide reduced surface temperature resulting in low IR signature. Illustrative pigments include chromium oxide green, magnesium ferrite, red iron oxide (Fe2O3), black iron oxide (Fe3O4), zinc ferrite (ZnFe2O4), or combinations thereof.

主权项

1. A water-dispersible, low observable curable composition comprising:
from about 10 to about 50 weight percent of an aqueously dispersed hydroxyl functional polyurethane resin wherein said aqueously-dispersed hydroxyl functional polyurethane resin has a molecular weight of from about 400 Daltons to about 6,000 Daltons; from about 10 to about 50 weight percent of an aqueously dispersed urethane acrylate resin wherein said aqueously-dispersed, urethane acrylate resin is formed from (A) one or more compounds of monohydroxy-functional alcohols containing (meth)acrylate groups, (B) polyester polyols obtainable from aliphatic diols having 2 to 4 carbon atoms between the two OH functions and/or aliphatic triols or aromatic di- and/or tricarboxylic acids, and (C) one or more compounds having at least one group which is reactive towards isocyanate; and from about 0.5 to about 2 weight percent of an ultraviolet photoinitiator; a low solar absorbing pigment that has low UV absorbance and that does not interfere with activation of the ultraviolet photoinitiator, said low solar absorbing pigment selected from the group consisting of chrome oxide, cobalt spinel, magnesium ferrite, red iron oxide (Fe2O3), black iron oxide (Fe3O4), zinc ferrite (ZnFe2O4), and combinations thereof; and from about 5 to about 50 weight percent of water wherein composition is at least “set to touch” according to ASTM standard 5895-03 following 10 minutes of flash off in spray both after 10 minutes of UVA exposure at a 14 inch lamp stand-off distance and further wherein said composition meets or exceeds MIL-DTL-64159 specification requirements.