Patent ID: 7097789

Claim:
A high clarity, substantially colorless thermoplastic polyester article having a relatively high light transmission in the visible light range of 450 nm, and a relatively low light transmission in the Ultraviolet (UV) light range of 390 nm, said thermoplastic article comprising: (a) at least one ultraviolet absorber compound, said ultraviolet absorber compound being dispersed in said polyester article in a concentration loading level, said ultraviolet absorber compound exhibiting ultraviolet absorption characteristics over the range of wavelengths from 300 to 400 nm; (b) said thermoplastic article exhibiting an extraction level for said ultraviolet absorber compound of at most 0.1 absorbance units from said thermoplastic article, said extraction level being measured as the level of absorbance exhibited by a heated alcohol extract solution after 2 hours exposure, said absorbance being measured within a cell of ten (10) cm in optical length; (c) wherein said high clarity thermoplastic polyester article exhibits at least 20–86 % T visible light transmission value at 450 nm for an article having a thickness of 17 mils, said article exhibiting a UV light transmission when exposed to UV radiation of at most 10% T at the 390 nm wavelength for a loading level of 2000 ppm or less for an article of a thickness of 17 mils, said thermoplastic article being substantially colorless; and (d) wherein said article provides protection from ultraviolet exposure whereby upon introduction of a 50 mg/L aqueous solution of Vitamin B 2 exhibiting an initial UV-Vis absorbance at a wavelength of 444 nm, further wherein said aqueous solution of Vitamin B 2 exhibits 48–62% retention of said initial UV-vis absorbance at 444 nm wavelength after about 9 hours of sealed exposure under the UV Weathering Test.