Photoinitiator

Photoinitiators are photoactive compounds, which on exposure to UV light and initiate radical polymerization of, for example, unsaturated acrylates.

They are components of radiation-curing lacquer and resin formulations which can be cured in a split second with irradiation by UV light. They are used for example in the diazo process, stereolithography and the multi -jet modeling. For coatings, the largest market segments are the furniture and parquet lacquer and printing inks.

Also in the LCD manufacturing photoinitiators can be used.

A frequently used in the coating industry photoinitiator is benzophenone and its derivatives.

Health hazards

2009 have discovered, for example, grain products photoinitiators for food security in dry foods several authorities. Due to the very small size of the molecules of the photoinitiator this can go on (paper, cardboard or plastic, for example ) in the food of the Printed Page of food packaging by several layers of packaging. The limits were indeed mostly below with check-ups, however, since for any type of photoinitiator A separate limit is given and no addition takes place, a significant amount of substances in the foods exist without complaint. The health effects are usually regarded as critical. Two photoinitiators, benzophenone and 4- methyl benzophenone were classified as harmful in animal studies, others not tested. These two substances can cause ulcers on the liver and kidneys. The permissible limit is 0.6 micrograms per kilogram of food. The limit was slightly exceeded in some foods tested.

Sources / literature

• R. Schwalm: UV Coatings - Basics, Recent Developments and New Applications. Elsevier 2007, ISBN 978-0-444-52979-4.
• Dieter Stoye, Günter Beuschel: Coating Resins: Chemistry and properties and applications. Hanser Verlag, 1996, ISBN 3446174753, page 93 ( limited preview on Google Book Search ).