Infra-Red Absorbers
Special additives such as kaolin absorb infra-red
radiation and are used as infra-red barriers in agricultural and horticultural
applications. We test the effectiveness of active agents in our infra-red
absorber masterbatches in our laboratories and in outdoor weathering.
UV-Absorbers
These substances are to protect plastics against
the damaging influence of light and to prevent consequential damage by the
influence of light (ageing) respectively. The consequential damages are
yellowing, embrittlement a.s.o. Polymers are protected against the light
damages as follows:
- Special energy transfering substances ( such as nickel-derivates)
also called quencher, deactivate excited state.
- Metal complexes of sulphur-containing compounds decompose formed
hydrogen peroxide connections.
- Monomeric and polymerc HALS (hindered amine light stabilizers)
intercept radicals.
- UV-Absorber with a high absorption capacity for ultraviolet
radiation (such as substituted O-Hydroxybenzophenones, salicylic acid
ester or hydroxyphenylene benztriazole etc.) prevent the light absorption
of plastics at wavelengths < 420 nm, which correspond to the absorption
maxima of the most polymers. The radiated energy is absorbed by the
absorbers and converted into infra-red radiation (harmless heat).
Apart from their effectiveness
light stabilizers have to be lightfast, must have a low inherent color, no
tendency to discolor and a low volatility. The composition of our UV
Masterbatches depends on the compatibility with the kind of plastic material
which has to be protected, the spectral range and the intensity of the acting
radiation, the heat stabilizers for the extrusion process and eventually the
non-toxicity etc.