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

Liquid-crystalline co-polyesters (e.g. a random co-polyester 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 40degrees C) well below the EC limit of 60 mg kg(-1). The highest specific migration for p-hydroxybenzoic acid was 15.2 mug dm(-2) in olive oil (2 h at 175degreesC). For 2-hydroxy-6-naphthoic acid, the highest value obtained was 4.3 mug dm(-2) in 10% ethanol (4 h at 100degrees 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 mug/person day(-1) and for 2-hydroxy-6-naphthoic acid it was 5.3 mug/person day(-1). The results exceed the threshold of regulation of 1.5 mug/person day(-1).