Determination of partition and diffusion coefficients of components of two rubber adhesives in different multilayer materials

Rubber adhesives both natural and synthetic are widely used in the manufacture of multilayer laminates, commonly used as food packaging. For this reason, it is very important to identify the compounds that could migrate from the laminate into the food. Twenty nine compounds were identified in two different rubber adhesives, some of them with high toxicity levels according to the theoretical model of Cramer such as benzene 4-cyanocyclohexene and benzene isothiocyanate. Partition of these compounds between the adhesive and different substrates and diffusion in both media were experimentally determined obtaining great variability of values depending on the properties of the compounds and the substrates used. Finally, only three compounds were found to migrate: benzene 4-cyanocyclohexene, butylated hydroxytoluene and 2-cyclopentyl-1.3.5-trimethylbenzene, with values of migration of 1.79, 22.9 μg/dm2 and 4.57 μg/dm2 respectively. These values were below the specific migration limits (SML) enforced by the legislation of the European Union (EU) and the values recommended by Cramer.