Materials and Characteristics

Coopbox has always processed polystyrene, a highly inert material that is expanded by injecting a natural gas. Expansion provides various different advantages. First, it lowers the density of the material, thereby reducing the weight of the tray and the amount of raw material required. Expansion increases the ability of the trays to withstand mechanical stress. This means improved protection against impact and allows the trays to be used for packaging processes in automatic or semiautomatic machines despite their low weight. In addition, expansion provides the trays with thermal inertia, thus improved insulation for the food product and less sensitivity to the temperature variations that are inevitable when the products are transported.

A liner or multi-layer bottom film can be applied to expanded PS (XPS) to provide the tray with an extremely high gas barrier and allow the PE-based heat-shrinkable film normally used in the sector to be welded to it.

Backed by experience with expansion technologies, Coopbox has applied the same principle to other polymers, such as PLA and PET, which comply with the increasing need for improved environmental sustainability.

PLA, a material developed during the last few years, is obtained from annually renewable sources. It is a lactic acid polymer, a natural product found in different sources such as milk and its by-products, or plant processing waste. Coopbox is able to expand this difficult material and create trays with good mechanical characteristics.

PET is a polyester widely used in the food industry. It is a high-performance polymer and is processed for the production of rigid trays in the Spanish plant. The trays possess an extremely bright finish and each individual version is designed for optimized performance while being as light as possible.

PET trays can also be welded to a liner or bottom film that provide the tray with an extremely high gas barrier and allow PE-based heat-shrinkable film to be welded to it.

The PET polymer is also expanded, using the same technology developed throughout the years for other polymers. Depending on the technology and materials used, Coopbox produces trays in expanded and crystallized PET (DOT) or trays in expanded PET. Light weight and environmental sustainability are the common features of these trays. Thanks to the expansion process to which the materials are subjected, savings in raw feedstock amount to about 30% compared to rigid PET. In addition, PET is a fully recyclable material for which the recycling circuit has been thoroughly developed since it is the same as water bottles. This means that PET trays can be disposed of along with these latter. Use of PET for food packaging purposes should also be considered in the light of the European and domestic laws, which now allow recycled materials to be used for the production of food trays.