Tinuvin absorber

The early recognition of the role of stable nitroxyl free radicals, e.g., 2,2,6,6-tetramethyl-4-oxopiperidine, and their hindered amine precursors, in polymer stabilization soon led to the development of the hindered amine light stabilizer (HALS) class of photoantioxidants. The first HALS, Tinuvin 770, AO-33, (commercialized in 1974) proved to offer much higher UV-stabil-ity to polymers than any conventional UV-stabilizer available at the time such as UV-absorbers, nickel compounds and benzoates. Table 3). 

LC-tandem MS was recently used for polymer/additive characterisation. In cases of soft ionisation processes (e.g. ESI, APCI, etc.), MS/MS is often necessary to confirm the ionic species. QITMS has the potential to improve the detection limits for organotin analysis compared to QMS. HPLC-UV and LC-API-MS/MS have been employed for the characterisation of the products of photodegradation of benzotriazole-based UV absorbers (Tinuvin P/328/900) under mild conditions [642]. Among the photoproducts identified... 

Even HALS compounds which absorb weakly at 337 nm can be analysed directly without matrix assistance, with the exception of the high-MW Hostavin N 30 (ca. 1500 Da), which fragments by direct laser desorption ionisation of intact molecules occurs only in the presence of a (dithranol) matrix. Direct laser desorption leads only to noncharacteristic, low-MW fragments. Hostavin N 20 leads to [M + H]+, [M + Na]+, [M + K]+ and some fragmentation peaks. MALDI-ToFMS of Tinuvin 765, which consists of a mono- and bifunctional sterically hindered amine, only shows the adduct peaks of the bifunctional amine apparently, the monofunctional amine is not ionisable. 

Figure 8. Kinetics of the photopolymerization of an epoxy diacrylate resin with and without UV absorber CO.5 % of Tinuvin 900)...

The photodegradation of synthetic polymers can be considerably reduced upon addition of ultraviolet stabilizers. The UV stabilizers (preferably derivatives of o-hydroxy-benzophenone or of 2-(2 -hydroxys -methylphenyl)benzotriazole (Tinuvin) transform the absorbed light energy into thermal energy thus preventing all sorts of photochemically initiated reactions. For review articles see the papers of Otter-stedt (.l), Heller and Blattmann ( 2, 2), Kloepffer (jl, j ), Gysling (JS) and Trozzolo (19 ) ... 

Set B Based on the results of set A discussed below, a third set. Set B, was prepared (Table IV). Cyasorb 531 (a benzophenone UV light absorber) was found to be the most effective stabilizer in Set A. It was therefore rerun at an even lower add-on in Set B, and since it was the only UV light absorber included in Set A, a second type of UV absorber, Tinuvin 327 (a benzotriazole) was included in Set B. Two new non-polymeric hindered amine light stabilizers (HALS) Tinuvin 770 and Tinuvin 765 were also evaluated in Set B with the hope that they might be more effective than the polymeric HALS (Chimassorb 944LD) included in Set A which was quite detrimental to the heat stability. Combinations of these four additives were also applied in Set B. The three new compounds evaluated have been reported to be effective light stabilizers for polyester and polyamide fibers (Capocci, G., Ciba Geigy Corporation, Ardsley, NY, personal communication, 1986). 

Light during processing, handling, and use. Typically are radical scavengers which interrupt the chain propagation steps of polymer autooxidation Absorb UV light to prevent photooxidation Tinuvin 327, 328, 384, 440, etc. (derivatives of... 

This reference documented chromatographic characteristics for many individual additives including plasticizers (phthalates, Citroflex A-4, TNPP) amides Irganox and Irgafos antioxidants UV absorbers (Tinuvin, Cyansorb) fatty acids (palmitic, stearic) Naugard XL-1 etc. 

Figure 10-18 presents the GC/MS analysis of a rubber formulation for an elastomeric insulator for devices to replace those that had been characterized after field-aging. In this example, a high quality silicone rubber was selected for inherent resistance to oxidation and UV damage, plus favorable dielectric properties. Figure 10-18 presents the GC/MS analysis of this elastomer, confirming pure silicone rubber and Tinuvin P, a UV absorbing polymer stabilizer. To reduce cost, many suppliers provide silicone rubber components that are often combined with butyl or nitrile rubber to reduce cost. 

Tinuvin [Novartis]. TM for a group of UV absorbers, substituted hydroxyphenyl benzotria-zoles, e.g., 2-(2 -hydroxy-5 -methylphe-nyl)benzotri azole. 

Effect of well-known industrial ultraviolet absorbers of Tinuvine and 2-oxy-4-methoxybenzophenone type, that were not inhibitors of radical processes, was investigated for comparison [162]. Being measured values of the rate of acetic acid accumulation were obtained with regard to corrections for shielding. 

Tinuvin . [Ciba-Geigy/Additives] Uv absorber, light stabiUzer for plastics, coatings. 

Hydroxy-3 -t-butyl-5 -methylphenyl)-5-chioro-benzotriazole. Bumetrizol Bumetrizole Bumetrlzolum 2-t-Butyl-6-(5-chloro-2H-benzotriazol-2-yl)-p-cresoi 2-(5-Chloro-2H-ben20triazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol EINECS 223-445-4 2-(2-Hydroxy-3-t-butyl-5-methyl-phenyi)-5-chloro-2H-benzotriazole 2-(2-Hydroxy-3 -t-butyl-5 -methylphenyl)-5-chloroben20-triazole Lowltit 26 Phenol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-( 1,1 -dimethylethyl)-4-methyl- Tinuvin UV Absorber-6 Uvazol 236. UV stabilizer for polyolefins, polyester resins and coatings, Used to protect polyolefins, slyrenics, acrylics, PVC, unsaturated polyesters, elastomers, PC, and PU, EniChem SpA Lowi. 

The interactions of these hindered-piperidine compounds with other conventional stabilizers has also attracted widespread interest. Allen et have clearly shown that the presence of phenolic anti-oxidants antagonize the stabilizing performance of hindered-piperidine compounds. Furthermore, their performance is drastically reduced by processing and this effect is demonstrated in Table 5 for bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (known commercially as Tinuvin 770) and a commercial phenolic anti-oxidant, Irganox 1010. With u.v. absorbers such as the 2-hydroxybenzophenones the hindered piperidines seem to... 

Compounds such as 2-(2-hydroxy-5-methylphenyl)benzotriazole 2 (tinuvin P) absorb UV light in the region of 300 - 400 nm and are used as radiation protection agents, e.g. for the prevention of sunburn, and also as photostabilizers for plastics, rubber and chemical fibres [155]. Tests have been carried out as to the suitability of polynitro-l-phenylbenzotriazoles as explosives [156]. 

A series of HALS and UV-absorbers trademarked Chimassorb and Tinuvin are available from and registered trademarks of Ciba (now BASF). 

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