Benzotriazoles UV absorbers

Transparent PVC plates were coated with a 70 pm thick film of an epoxy-acrylate resin containing 0.5 % of a benzotriazole UV absorber. They were first UV cured for one second and then exposed at 40°C to the low intensity radiations of a QUV accelerated weathering tester. The extent of the degradation was followed by Invisible spectroscopy, a very sensitive method that permits detec-... 

Figure 3. SEM micrograph at 600x (left) and IR spectra (right) of impact polystyrene with 0.5% LSI (HA LS) and 0.5% LS II (benzotriazole UV absorber). The samples were exposed in Florida at a 45° anglefacing south. The 6-month SEM shows the presence...

Figure 6. SEM photomicrographs of impact polystyrene exposed in Florida at a 45° angle facing south for 12 months. The photos of the non-light-stabilized samples show the presence of mildew. The light-stabilized samples contained 0.5% LS / (HA LS) and 0.5% LS I (benzotriazole UV absorber).

Hydroxy-3,5-di-(1,1-dimethyl benzyl) phenyll-2H-benzotriazole UV absorber, acrylates 2-Ethyl, 2 -ethoxy-oxalanilide UV absorber, acrylic 2-(3, 5 -Di-t-butyl-2 -hydroxyphenyl)-5-chiorobenzotriazole Drometrizoie 2-(2 -Hydroxy-3,5 -di-t-amylphenyl) benzotriazoie 2-[2-Hydroxy-3,5-di-(1,1-dimethylbenzyl) phenyn-2H-benzotri azole Octrizole... 

For UV management, proper understanding for UV absorbers is necessary. Most UV absorbers, independent on the type of chromophor, absorb the damaging light and emit non destructive heat. This is the examples of benzotriazole type of UV absorbers (Figure 6.5). In the market, different kinds of substitution of benzotriazole UV absorbers are... 

Figure 6.5 Side chain effect on benzotriazole UV absorbers...

Benzotriazole. Benzotriazole UV absorbers are highly effective in high-temperature resins such as acrylics and polycarbonate. They also find extensive use in areas outside plastics such as coatings. 

A practical route to reduce the effects of photo-degradation in PUs (as in the case of other polymers) is the addition of suitable light stabilizers by different ways. The most used procedure is the additive stabilization method. A more effective method to increase the maintenance of the stabilizer in the polymer is the chemical bonding of these compounds to the macromolecular chain even in the course of polyurethane synthesis. Some attempts to introduce in such way the stabilizers in polymers are known. Thus, a benzotriazole UV absorber was mixed with a prepolymer containing isocyanate groups and the chain extender directly into moulding machine (cone. 0.5%) [64, 323]. The stabilizer can be also mixed into polyol component before its reaction with the isocyanate component. The stabilizer that usually contains OH groups could form chemical bonds with the macromolecular chain in some extent [324]. 

Benzophenone UV absorbers have been used for many years in polyolefins, PVC, and other resins. Benzotriazole UV absorbers are highly effective in high-temperature resins such as acrylics and polycarbonates. They also find extensive use in the coatings industry. Benzoates and salicylates, such as 3,5-di-f-butyl-4-hydroxybenzoic acid n-hexadecyl ester, function by rearranging in 2-hydroxyben-zophenone analogs when exposed to UV light to perform as UV absorbers. 

Key A, benzophcnone UV absorbers B. benzotriazole UV absorbers C. HAl,Ss I). special stabilizer blends. 

Of the various chemical classes of UV stabilizers that have been developed, the benzophenone and benzotriazole UV absorbers, the hindered amine light stabilizers (HALS), and their combinations continue to satisfy the UV stabilization requirements of most of the large-volume outdoor polymer applications. In addition, many new stabilizer chemistries, such as UV absorbers based on hydrox-yphenyl triazines, have been developed for more demanding applications or to satisfy specific market needs. Light stabilizers together with other additives (qv), such as antioxidants (qv), impact modifiers, colorants (qv), fillers, heat stabilizers (qv) and plasticizers (qv), have enhanced the properties and extended the service life of polymeric materials, resulting in the replacement of traditional materials in a multitude of outdoor weatherable applications. 

Broad-band benzotriazole UV absorber recommended for polyolefin applications. 

Broad-band benzotriazole UV absorber recommended for acrylic, unsaturated polyester, polycarbonate, styrenes, and vinyls. 

Benzotriazole UV absorber recommended for unsaturated polyester and PVC applications. 

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