Ultraviolet Light Protection and Stabilization

Ultraviolet Light Stabilizers. Both titanium dioxide and carbon black are strong ultraviolet light absorbers and effective in protecting the PVC. For ultraviolet light absorption in transparent PVC oi foi impiovement of pigmented systems, various derivatives of benzotnazole are used. 

USE An ultraviolet light absorber for stabilizing plastics and other organic materials against discoloration and deterioration. Effective in protecting polyesters, chlorinated polyesters, polystyrene, polyvinyls, polypropylene, alkyds, cellulose acetate, ethyl cellulose, acrylates, dyes, synthetic and natural fibers, waxes, detergent solns. cosmetic formulations. Ref Dunn, Fogg, J. Appl. Polymer Sci 2, 367 (1959). 

The solvent-borne clearcoat is spray-applied over the basecoat at a dry film thickness of 1.8 to 2.0 mils. The clearcoat, responsible for UV protection, chemical resistance, chip resistance, and so on, is most often composed of a hydroxy functional acrylic binder together with a melamine or an isocyanate cross-linker. Ultraviolet light absorbers and hindered amine light stabilizers also are added to achieve better free-radical oxidative degrada-... 

Ultraviolet-light stabilizers are of two types those that preferentially absorb UV, thus shielding the polymer structure from UV light and those that protect by quickly scavenging the free radicals as they form. The latter belong to a group of compounds known as hindered amine light stabilizers (HALS). 

Triazoles, such as phenylbenzotriazole, naphthylbenzotriazole, and related compounds, such as benzophenone are UV absorbers. A particularly well-known group of ultraviolet stabilizers are hydroxyphenylbenzo-triazole-based compounds. However, UV light stabilizers of this type are often lost from the product into which they are incorporated by leaching or hy evaporation. To overcome these difficulties, efforts have been directed towards chemically incorporating the ultraviolet light stabilizer into the polymeric backbone of the material to be protected. ... 

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