Blankenhain/Thuringia – Life without plastics – unthinkable. Yet every product must be treated individually. This is what drives research and development staff at the GRAFE Group to continually search for new and innovative products for the market. „Either we can find the way – or we create our own way”, is how Petra Henkel of the Additive Business Division in the GRAFE Group puts it. At the FAKUMA, GRAFE is presenting a new development – a UV Masterbatch for PC twin-wall sheets.
Ultraviolet light is a relatively high-energy radiation which is very important for many chemical and technical processes. Ultraviolet light as a component of sun light is essential for maintaining nature and the existing biological equilibrium, as well as reducing air pollutants caused by civilization. Ultraviolet radiation is part of sunlight, but can also be generated by artificial sources of radiation. The sun’s radiation presents a great challenge for the producers of masterbatches, since UV radiation can age plastics and colors. The life cycle of plastic components is shortened in outdoor applications but also by exposure to artificial light. UV absorbers are important as a means of protecting plastics.
UV absorbers used in twin-wall sheets are primarily Polycarbonate based. Unlike PMMA or polyolefine,
polycarbonate does not stand up well against low-wave (high energy) radiation. The main effects of such radiation are a loss of mechanical strength and yellowing. The use of PC compounds with approx. 5 to 6
% UV absorbers, normally benzotriazole or cyanacrylates derivates, is now state of the art practice. These compounds are used primarily in coextrusion processes. The thickness of the layer, and therefore the concentration of the UV absorbers, determine the guarantee and durability of the twin-wall sheets in outdoor applications. The co-extruded layer is 30 and 50 μm, which explains the high concentration of additives.
These types of compounds are included in the standard range of many well-known
manufacturers of polycarbonates worldwide. Optical brighteners and blue/ violet colorants are used in
addition to UV absorbers to counteract the natural yellowing of the polymers during the processing between 250 and 280 °C.
GRAFE’s newly developed UV masterbatches for polycarbonate twin-wall sheets offer the advantage of
highly concentrated additive masterbatches and contain 50% of the active ingredient in addition to optical brighteners and a color improver. The masterbatch is dosed at 10 to 12 % with pure PC and
coextruded on to the twin-wall sheets. The issue of dispersibility under industrial conditions has been successfully resolved. GRAFE’s flexible production technology allows the use of any type of UV absorber to meet its customers’ demands in terms of both technology and price. It allows savings of up to 30 % in comparison with traditional products. In addition it saves up to one tenth of the normally required quantity due to quick transportation and simple storage requirements.