Ultraviolet protectant stabilizer

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. 

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. ... 

Hydroxybenzophenones represent the largest and most versatile class of ulbaviolet stabilizers that are used to protect materials from the degradative effects of ulbaviolet radiation. They function by absorbing ultraviolet radiation and by quenching elecbonically excited states. 

Bifunctional spacer molecules of different sizes have been used to construct nanoparticle networks formed via self-assembly of arrays of metal colloid particles prepared via reductive stabilization [88,309,310]. A combination of physical methods such as TEM, XAS, ASAXS, metastable impact electron spectroscopy (MIES), and ultraviolet photoelectron spectroscopy (UPS) has revealed that the particles are interlinked through rigid spacer molecules with proton-active functional groups to bind at the active aluminium-carbon sites in the metal-organic protecting shells [88]. 

A review on image stability in colour photography has been published (79MI11401). Ultraviolet filters which absorb harmful radiation have been used for the protection of image dyes. These are exemplified by the benzotriazole (98) (72GEP2036719) and the pyrrolidine (99) (81BRP1592742). 

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