Migration of monomers from liquid crystalline poly(p-hydroxybenzoic acid-co-2-hydroxy-6-naphthoic acid)

Liquid-crystalline co-polyesters (e.g. a random copolyester based on p-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA) known as Vectra A950) offer good barrier properties, but for food-contact use require overall and specific migration testing. For Vectra A950 films, the highest overall migration level obtained was 2.3 mg kg−1 in olive oil (10 days at 40°C) well below the EC limit of 60 mg kg−1. The highest specific migration for p-hydroxybenzoic acid was 15.2 µg dm−2 in olive oil (2h at 175°C). For 2-hydroxy-6-naphthoic acid, the highest value obtained was 4.3 µg dm−2 in 10% ethanol (4h at 100°C), although it was not on the EC positive and cannot yet be used for food-contact materials. At conditions considered as severe, the estimated daily intake for p-hydroxybenzoic acid was calculated as 11.9 µg/person day−1 and for 2-hydroxy-6-naphthoic acid it was 5.3 µg/person day−1. The results exceed the threshold of regulation of 1.5 µg/person day−1.