For polymer materials – in terms of outdoor ageing – sunlight is the energetically most rich component of weather effects. Photochemical degradation causes a deterioration in mechanical characteristics. It induces cracking and eventually complete disintegration of the material. Polyolefins are more sensitive to irradiation than methods reflecting chemical changes . Deterioration of mechanical properties is a final consequence of the series of processes involved in photochemical degradation. For polyolefins, hindered amine-based on 2,2,6,6-tetramethylpiperidine derivatives are gaining importance as light stabilisers . They are effective as antioxidants at low and moderate temperatures . Hindered amine light stabilisers have a synergistic effect in combination with aliphatic phosphites under photo-oxidative conditions.