Is Spectar appropriate for applications with prolonged outdoor exposure?
There are two things to consider when contemplating the use of any plastic in an outdoor environment— the material’s ability to withstand UV radiation and the temperature it will be exposed to on a regular basis. Additional details follow to help you determine whether Eastman Spectar™ copolyester is appropriate for your outdoor application. If an outdoor application requires color, Eastman Tritan™ copolyester may be the best choice.
Prolonged exposure to the sun and weather can be harmful in many aspects. Unprotected copolyesters are not immune to the effects of damaging UV rays. Like polycarbonate and other competitive sheet products, you need to give special consideration to how much exposure your application will have to harsh weather environments.
UV rays in sunlight can adversely affect a copolyester’s appearance and performance by causing a color shift to yellow, decreasing impact resistance and increasing haze.
There is something, however, that you can do to prevent these undesirable issues.
If you have an application that is going to be exposed to sunlight, Eastman has various UV absorbers that can help stabilize Spectar and Tritan in certain conditions. You may request UV-protected Spectar and Tritan sheet from your supplier. As you can see in the following charts, Eastman Spectar UV™ copolyester exhibits low color shift and retains its impact resistance—even when exposed to the sun in Florida for five years. Tritan with a UV cap layer also withstands the rigors of extreme exposure. For those who are unfamiliar with xenon arc accelerated artificial weathering, the general rule of thumb is that 1500 kJ of exposure is usually equated to about one year of real-time weathering in exterior environments.
You should also give some thought to a material’s heat distortion temperature for exterior applications. If your specific outdoor application requires a color, then sheets of Tritan should be used instead of Spectar to avoid heat-induced warping.
For do-it-yourselfers and smaller applications that may not require a large order of Spectar UV material, clear-coat spray paint options and weatherable laminated films are available that can help add UV protection. Contact your Eastman representative for more information.
For more information on signs and Tritan,
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