K2019: SML/Kiefel explore foamed PET hot fill cups for easy recycling

K2019: SML/Kiefel explore foamed PET hot fill cups for easy recyclingg

Austrian extrusion machinery firm SML is developing foamed sheet for hot fill applications with new features in terms of heat resistance, insulation and recyclability in a joint R&D programme together with German thermoforming machinery maker Kiefel. The basis for these new products is a three-layer PET (or PP) sheet with a physically foamed central layer that can be easily recycled and also used in the airline industry.

Mono-material foamed PET or PP sheet produced from SML’s new systems have improved product features that can help to replace difficult-to-recycle hot fill applications made of expanded polystyrene (EPS). Generally, PS is permitted for food applications, but it is considered to release the chemical compound styrene into the environment.

The foamed sheet from SML’s new lines has an A/B/A structure, in which the central B layer is foamed while the two outer layers are rigid. The central layer is physically-foamed with the injection of nitrogen or simple carbon dioxide gas which is widely available. Mono-material structures facilitate recycling while the foamed layer reduces weight up to 50% compared to PET sheet with the same properties. No special additives are required to enhance the heat stability of the sheet which is thus suitable for the economic production of low-weight cups with excellent insulation properties.

K2019: SML/Kiefel explore foamed PET hot fill cups for easy recycling

In a new joint R&D project, Kiefel Technologies and SML are exploring and further developing the potentials and opportunities this type of foamed sheet is offering. Beside end products with very specific mechanical and thermal properties, the optimisation of the manufacturing processes and the research on new recycling methods are in the focus of this research programme.

SML says the first outcome is promising with cups boasting a heat resistance of up to 100°C created form standard APET. The sheet for such cups can have an overall density of about 0.65 kg/dm³, which saves material and increases the insulating properties, so that it is possible to hand-hold these cups filled with hot liquids.

Unlike PS, mono-material foamed sheet, especially from PET, is straight-forward to recycle as the relevant infrastructure already exists in many places.

Hot fill applications made of foamed PET sheet can be easily processed with other single use products from PET. This opens opportunities to branches as airline catering or system gastronomy, which still rely on disposable items.

A key element in the joint research programme of Kiefel and SML is the new demonstration and development line for thermoforming sheet in SML’s Technology Centre. With a thickness range from 200 micron to 2 mm, the line offers a maximum of flexibility for all kinds of projects related to thermoforming. Except from this research programme, it stands open to SML’s customers and partners for trials and R&D.


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