Ultraviolet light absorbing coating

This product is an ultraviolet light absorber for use in polystyrene, unsaturated polyesters, coatings, varnishes, lacquers, and coatings based on epoxy or phenolic alkyds. It is also used in pressure sensitive adhesives, polymethylacrylate (fdm or sheeting), thermoplastic rubbers, polyisoprene latex and alcohol based cosmetics. 

Coatings exposed to sunlight for extended periods are also subjected to degradation. Combinations of HALS and ultraviolet light absorbers (UVAs) are used to obtain a synergistic effect. A 1 1 combination of a UVA of the benzotriazole class with HALS has been used [13], Figures 4.7 and 4.8 show the benzotriazole and HALS combination. 

Two different types of photostabilizers are typically added to antomotive clearcoats, ultraviolet light absorbers (UVA) and HALS. Clearcoat UVA acts to reduce the intensity of light inside the paint system. That is, it reduces clearcoat PIR and screens light sensitive coating layers underlying the clearcoat (e.g., basecoat) from UV light. As a result, clearcoat UVA also acts to extend HALS longevity. Clearcoat UVA performance is not discussed further in this chapter. Typical HALS types that are used in clearcoats are shown below. " ... 

RD Tokash. Ultraviolet light absorbers A study of migration susceptibhity from flexible topcoats into TPO substrates. Conference Proceedings of Advanced Coatings Technology, Detroit, MI, 1993, pp 173-183. 

Detection and Identification Detection and identification of solute bands is done by methods essentially the same as those described in Column Chromatography. However, in TLC an additional method cal led fluorescence quenching is also used. In this procedure, an inorganic phosphor is mixed with the adsorbent before it is coated on the plate. When the developed chromatogram is irradiated with ultraviolet light, the surface of the plate fluoresces with a characteristic color, except in those places where ultraviolet-absorbing solutes are situated. These quench the fluorescence and are detectable as dark spots. 

HALS 2 and the benzotriazole ultraviolet (UV) light absorber CGL-900 were obtained from the Ciba-Geigy Corporation and recrystallized before use. The synthesis of nitroxide 2 has been described (44). Nonpigmented coatings were cast on quartz slides (for the ESR studies) or on KRS-5 salt plates (for the IR studies) and cured at 130 C for 30 minutes. The coatings were then exposed in a modified Atlas UV-2 UV weathering chamber. The chamber was modified to allow air temperature and dew point to be controlled simultaneously. 

Optical bri teners These compounds are used to make white clothes appecu extra clean and bright. These very complex organic compounds deposit themselves as a thin coating on the clothes. They absorb ultraviolet light and re-emit it as a blue light in the visible part of the spectrum. This process is shown in Figure 17-3. 

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