Interaction of a Vinylic Organosol Used as Can Coating with Solvents and Food Simulants

Abstract

Metal cans are often protected from corrosion by vinylic organosol coatings, made from PVC and epoxyphenolic (EP) resins. Using electron spin resonance, BADGE, a monomer of EP, was shown to plasticize PVC. Optimization of extraction allowed extraction of 4 mg of BADGE/dm2, so vinylic organosols appear to be worst-case coatings. Comparison of behavior between BADGE and a paramagnetic probe revealed that these compounds were trapped to a large extent in the cross-linked EP network and could not migrate at 40 °C. Contact with triglycerides, which plasticize the coating, induced high migration of BADGE. Neither isooctane nor ethanol could mimic fats, in contrast to isooctane/tert-butyl acetate mixtures. In aqueous foodstuffs, BADGE hydrolyzed into a monoepoxide and then into a bisdiol. The total amount of toxicologically relevant epoxides over shelf life was shown to reach a maximum value within 3 weeks at 40 °C, at very low levels, whatever the aqueous food simulant. After sterilization at 120 °C (20 min), the level of BADGE in the migrate is very low, whereas up to 2 mg of hydrolysis products is found in the liquid/dm2. During further storage at 40 °C, the amount of epoxides rapidly decreases.