Enhanced weatherability of exterior PVC building products

Poly(Vinyl) Chloride (WC) is used extensively as a material for the growing building-products market. The color preferences of consumers for markets such as vinyl siding have forced the industry to seriously reconsider the use of WC especially for the medium-to-dark color palettes, where the performance is critical. Organotin mercaptides have always been the stabilizers of choice :in the U.S. market because of their inherent outstanding heat-stabilization properties. On the other hand, this technology is also known to be a compromise between processability and weathering characteristics. In a market that drives for excellence, all additives must be optimized to meet the final performance requirement. Organotin carboxylates and specifically maleates have long been known for excellent weathering but have not been used extensively in the industry owing to less-than-optimum intrinsic heat stabilization efficiency, and in some cases, troublesome lachrymatory properties. A new generation of organotin maleates has been successfully developed to address both issues. This paper describes the improved lachrymatory behavior of the new technology compared to standard organotin maleates and also shows its outstanding weathering performance in PVC capstock compared with conventional organotin mercaptide during natural aging.