PET is an acronym for Polyethylene terephthalate, a
plastic material which is part of the polyester family and can be used for food
contact applications. PET is perfectly transparent, light, shock-resistant and
can be produced in different colours. The production of bioriented bottles in
PET occurs in two phases:
- The first phase consists in creating a preform by
injection mold of melted PET at 350°C in appropriate moulds with particular
characteristics in terms of shape and thickness depending on the type of final
bottle.
- The second phase entails blowing of the preform, at a
temperature of 120°C, with a simultaneous axial and radial stretch.
The stretching confers to the bottle a bioriented structure, improving its
mechanical resistance and gas barrier properties.
The use of PET bottles started to become widespread within the beverage
industry in the late 70’s. PET use started in the mineral water sector and the
CSD and then expanded in the juices, fresh milk, wine and liqueurs market. PET
has recently entered in the beer sector, thanks to new systems for coating of
the bottles to increase barrier properties against oxygen and carbon
dioxide.
Additionally, there is a current study in process concerning additives
which, if added to liquid PET prior to injection in the preform moulds, confer
improved UV or oxygen barrier properties to the material.
PET containers have many advantages, such as a high shock-resistance, great
transparency, lightness, the possibility of producing tailor-made bottles with
original shapes and a good barrier against carbon dioxide.
Today PET can be easily recycled, with systems now able to recycle the
product to produce new bottles using 100% of material coming from old bottles.
The compatibility of PET for food contact is sanctioned by norms 2002/72/CE of
the European commission and subsequent modifications (2004/19/CE).