Renolit Ondex, a French subsidiary of the German group Renolit Worms transforms PVC by extrusion into corrugated sheets for roofs used on greenhouses and industrial premises.
PVC, and the darker colours in particular, can degrade and deform in sunny regions. It was therefore necessary to make it more resistant to heat, in order to strengthen sales activities in the south of France, Spain, Italy, Portugal, and North Africa.
Upgrading of PVC: The Luran family
The R&D department of the processor has worked closely with BASF to create a dark mixture of PVC and Luran® HH 120 to meet the market's needs for dark coloured corrugated sheets. Luran HH 120 is an AMSAN copolymer. Since January 2011 it is being sold by Styrolution, the new BASF subsidiary for styrenic polymers. The material is a modified SAN (styrene-acrylonitrile copolymer) with improved heat resistance. Its Vicat softening point is 120°C and thus distinctly higher than the Vicat temperature of PVC of approx. 75°C. Given this high Vicat value, a mixture of PVC and Luran HH 120 is more resistant to high temperatures than PVC alone. For example, a blend of 80% PVC and 20% Luran HH 120 withstands 8°C more than PVC alone.
Blending with Luran HH 120 thus makes it possible for Renolit Ondex to offer a range of dark corrugated sheets that fulfil the same requirements than the lighter coloured sheets. In order to achieve an optimum impact resistance for the mixture BASF also offers specific additives like the PVC processing aid Vinuran® which is used in many PVC blends. Next to classical granules, Luran HH 120 is now available in powder form to facilitate blending with PVC.
Another way to upgrade PVC is coextrusion with Luran® S, BASF’s ASA (acrylic ester-styrene-acrylonitrile-copolymer). Here the coextruded top layer yields not only temperature and weathering resistance but also either low or high gloss, just according to the customer’s requirements.
Under the Italian sun - and elsewhere
The Italian agricultural company Belisari Cesare in the Rome region has fitted several buildings used for storing plants and equipment with roof sheets made from such an extruded mixture by Renolit Ondex. The roof is to the customer's liking: dark, aesthetic, and it resists the Italian sunshine. Other applications for blends of PVC and Luran® HH 120 are blinds, roller shutters, pipelines, or hot water drains. Moreover, the transparent plastic which combines the advantages of classical SAN with improved temperature and weathering resistance, can be used as an alternative to PMMA in the construction of vehicles.