Assessment of migration potential of photoinitiators from ultraviolet (UV) curable printing inks

Abstract

Food safety is a subject of great importance and demands for safer products are constantly increasing. Within this context, packaging has a key role in the food and beverage chain. Besides the protection/preservation functions that the packaging system must provide, it should be specified to prevent the transfer of substances from this system to food products. Packaging is a complex system which often consists of several components, among them, printing inks. Generally, inks are mixtures of dyes or pigments, polymers, plasticizers, solvents and other additives. They could be water or solvent-based, oleo-resinous or energy-curing (ultraviolet (UV) or electron beam (EB)) systems. The main legislations for food contact materials do not have regulations for printing inks and it is essential to create scientific knowlegde in this area. Thus, this project was elaborated to study UV curable inks used in food packaging in terms of food safety. UV curable inks are reactive liquid systems constituted by oligomers, reactive solvents, additives, dyes or pigments and photoinitiators, which are capable of producing thermosetting polymers by polymerization and radiation-induced crosslinking reactions. The photoinitiator is responsible for the absorption of UV radiation and it is capable of initiating the polymerization reaction using specific reaction mechanisms. Several photoinitiators are commercially available and benzophenone (BP) is one of the most employed. However, BP can migrate to foods and/or simulants as stated in several published papers. Based on this scenario, there has been a demand for UV curable inks with low migration potential and for this reason polymeric photoinitiators have been the subject of several studies. Most of them are benzophenone-based polymerics, which are already produced industrially for use in food packaging inks. Therefore, the aims of this project are to develop and validate methods for determining the migration of BP and benzophenone-based polymerics to food simulants, study the relationship of some parameters inherent to the printing system such as "photoinitiator concentration in the formulation" and "UV dose" versus migration of BP to food simulants. A comparative study of the migration potential of BP and benzophenone-based polymerics will also be carried out. (AU)