Study of hotmelt adhesives used in food packaging multilayer laminates. Evaluation of the main factors affecting migration to food

Hotmelt adhesives are widely used in the manufacture of multilayer laminates, commonly used as food packaging materials. For this reason, it is very important to determine the composition of the adhesives and to identify which compounds could migrate from the laminate to the food. Twenty four compounds were identified in 2 different hotmelt adhesives, some of them with high toxicity levels according to theoretical model of Cramer, such as 9,10-dihydroanthracene and retene. Some physicochemical properties of these compounds, such as their partition and diffusion coefficients in the different materials used in the laminates, provide useful information for evaluating their potential migration to the food. The determination of the partition and diffusion coefficients was performed with two different laminates made of cardboard or polypropylene cardboard substrates and the adhesive. Partition and diffusion coefficients of the migrants in the adhesives and substrates were calculated from the experimental results. It was found that diffusion was always lower in the adhesive than in the cardboard. All diffusion coefficients determined increased with temperature while the partition coefficients showed the opposite effect. Migration results confirmed that the migration value of a compound was closely related to the calculated partition and diffusion coefficients. None of the migrants exceeded the recommended Cramer exposure values.