The effect of photo-release of fragrances is well known. Most precursors of fragrances or the actives themselves are volatile and therefore the desired effect diminishes quickly under ambient conditions and particularily at elevated temperatures.

For example, when employed in substrates which undergo further processing at elevated tempera-tures - such as the curing process of a coating layer - many (pro)fragrances are unstable or disappear quickly.

To prolong olfactive perception, new systems have to be developed which are stable to the processing conditions and which allow a controled, slow and longlasting release of the active fragrance.

Several concepts have recently been reviewed by Hermann et al [3], for example, the controled delivery of fragrancies from polymer substrates by thermal or photochemical release and by encapsulation techniques. However, a single, unique release mechanism would be highly desirable since it would also allow the liberation of well defined scents composed of a blend of many individual components at the same rate.

Recent developments at Ciba has targeted and optimized towards pro-fragrances which can be delivered on demand by activation with appropriate UV-Vis radiation sources. Thermally stable slow release systems without impact on standard coating performance requirements such as gloss, durability, discoloration etc. are currently under development.