Chemistry of UV protection finishes

The requirements for a material to be effective as a UV protection finish include efficient absorption of UV radiation at 300-320 mn, quick transformation of the high UV energy into the vibration energy in the absorber molecules and then into heat energy in the surroundings without photodegradation. Further requirements are convenient application to textile fibres and lack of added colour for the neated fibre. Some typical chemical snuctures useful for UV protection are shown in Fig. 

3 and Fig. 14.4. The reversible chemical reaction, induced by UV absorption of hydroxyphenyl structures of UV absorbers, is shown in Chapter 13 (Fig. 13.6). By careful choice of substituents, molecules can be formed that have the required absorbance of UV radiation, lack of added colour and the necessary affinity to fibres and fastness. In most cases, the UV absorber is applied with the dyes during 

R2 = hydroxy, alkoxy, alkylthio, substituted alkyl, substituted phenyl, o-hydroxyphenyl 

A = direct bond or alkylene linkage M = H or alkali metal 

Comite European de Normalisation British Standards Institution 

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