Heat stabilizer market ready for product changes-2

The use of the different stabilizer systems differs not only from region to region, but also from application to application.

Extruded PVC profiles are products with good physical properties that meet the most demanding economic and ecological requirements. Applications include window and door frames, shutters, cable ducting, siding, and gutters, to name a few.

In the profile sector, lead stabilizers are still widely used because of their good processability, favorable cost/performance ratio, and outstanding heat stability. However, CaZn stabilizers now possess a considerable market share in Europe since they have evolved out of expensive stabilizers based on metal soaps and polyoles to more elaborate systems comprised of effective inorganic acid scavengers and organic costabilizers.

In terms of processing properties, the tendency of CaZn stabilizers to plate-out in tools and calibration has been reduced to the same level as lead. When processed with suitable lubricant systems, CaZn-stabilized profiles compare favorably with lead-stabilized profiles in terms of processability and surface gloss.

Weathering performance is a critical issue in stabilization of building profiles. Testing indicates CaZn stabilizers achieve a better color hold than traditional lead systems. This effect is particularly relevant for dark colored profiles where additional cost savings may be realized by lower colorant requirements due to the reduced whitening pigment effect of CaZn compared to lead.

Liquid tin stabilizers used in the United States require a high dosage of titanium dioxide (TiO2) for sufficient weathering stability. Widely used solid lead stabilizers work with a much lower TiO2 level even under extreme weathering conditions.

Looking to the future, modest changes away from tin stabilizers in the United States are expected, whereas lead systems in Europe will increasingly be replaced by CaZn systems.

Analysis of stabilizers used in the pipe sector shows a similar situation. In Northern Europe, most producers switched completely to alternative stabilizers because of legislation or market pressure. In the United Kingdom, the permission to use lead in potable water pipes expired at the end of 2003. In South America, some large processors switched on a voluntary basis.

(To be continued...)