Compounding Creativity with Technology
Color trends have varied over the years, but white seems to never go out of style. Whether its shades of white, or finishes, white railing, fence and windows remain the predominant color for these outdoor applications.
As end customers have spent more for these products as of late, they are asking more of their performance in terms of consistency of overall appearance (shade and gloss), inherent physical properties such as scratch or abrasion, or long-term resistance to color change and fading. With performance expectations rising, it becomes that much more critical to have a high-performing white compound that delivers and, to that end, new enhanced grades of PVC have done just that for capstocking building products.
Available in a range of finishes, from matte to high gloss, the customer can select the desired finish for the application, all while knowing the performance exceeds that of conventional white PVC compounds. Depending on the application, like railing, post sleeves or spindles, non-chalking grades are available. Chalking grades for windows and fence applications are suggested for added UV protection (the surface of the part will exhibit a “chalk” like effect for added protection against UV rays.) Teknor Apex capstock materials show significant improvements to reduce yellowing by as much as 1-2 units compared to conventional grades (tested via accelerated weathering.)
We rigorously test new capstock grades – in four geographic locations (FL, AZ and OH in addition to Xenon, QUV and environmental chamber testing. On top of outdoor and accelerated weathering, we perform a battery of physical property tests, including tensile and flexural strength and modulus, impact strength, scratch and abrasion resistance. This testing is performed to help our customers make informed decisions regarding expected long-term performance and to help alleviate the burden of some of their own internal testing.
Figure 1 below compares the shift in color or Delta E (DE) over two years when exposed to a Florida environment. The higher the DE value, the greater the shift in overall color. An initial shift of colorto the blue side is not uncommon, but ultimately returns back towards the control or slightly yellow. This would explain why the curves have an initial upward trend, and then shift downward. In each case, the enhanced formulation results in a lower color shift (DE) as compared to the conventional white capstock.
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