How systems companies manage legacy chemicals in recycled content is key if they want to be able to guarantee through-life performance.
The lead stabilisers and additives may be long since gone from PVC-U extrusion but in recycled material, they’re still very much there – or at the very least could be. And that’s enough to create a significant challenge. Profile performance is dependent on the strict control of its formulation and by definition, recycled material is an unknown quantity.
If the ratios of the formulations are unknown, it can be very difficult to predict how they’re going to perform in extremes of temperature. The differentiation between metal salts or stabilisers can be significant.
The strategy adopted by the industry has for the most part to put this material into standalone second-grade products, for example reinforcements, to apply a skin of ‘virgin’ material or to foil product. The last two options, however, appear fraught with risk.
The substrate can have a significant impact on surface gloss even and consistency of finish and because it’s ‘unknown’ and variable, it can be very difficult to control.
Processing approaching 200,000 tonnes of PVC-U globally annually, equivalent to 75 per cent of the whole UK and Irish markets combined and with its worldwide customer base manufacturing more than 10million windows per year, aluplast has the scale to apply to product innovation.
Its solution to the challenge but also the opportunities delivered by the introduction of recycled PVC-U content into new generation products, is simple in concept but draws on extrusion genius to deliver it.
Available as an option on its core Ideal 70 offer but also contemporary new Ideal 4000 system, ecotech, does this by isolating recycled material only in the core web of its product where dimensional stability is not critical.
The extrusion process applied by aluplast to deliver this minor miracle in PVC-U profile manufacture, uses pre and post-extrusion product and post fabrication waste plus known source post installation pelletized, PVC-U.
Two compound screw feeds then push recycled and virgin material simultaneously through the profile dye to create the profile while maintaining a distinct separation between the two. This separates and at the same time locks recycled material away from areas of the frame visible to the end-user or which perform a structural role, which means that aluplast can guarantee surface and finish quality.
The development of ecotech has represented a significant commitment in the creation of special dyes and the increased investment in running two extruders simultaneously on a single profile. This provides a stable substrate for the millions of metres of foils the company supply each year.