Since the 1990’s most strap is produced using PP or PET. Plastic strap became available from the 1960’s, before this Woven Strap or Steel strap were the main materials used to strap.
Woven Strap is generally made from polyester or rayon yarns woven together and bonded in a hot melt process, it is sometimes referred to as corded strapping. Gordian is one of the few companies still manufacturing this strap in the UK, under the brand names Balestrap, Pakord and Tytape. Usually applied by hand and using buckles to tension it, this strap is mainly used for a lighter tension.
Steel strap was used for high tension applications. However since the 1990’s steel has been largely superseded by PET. The advantages of PET compared to steel are as follows:
Generally made from virgin polymer PP strap is available in a variety of colours. Commonly available widths are 5mm, 6.5mm, 9mm, 12mm and the strap is usually embossed. High elongation PP (typically 25-35%), which renders the strap less stiff, is useful for smaller packs especially with sharp corners.
PET used to be made from virgin polymer, but over the last 10 years more companies are using recycled PET bottles to make PET strap. Commonly available widths are 9mm, 12mm, 15.5mm, 16mm and the strap is available either in smooth or embossed variants and is generally green.
Plastic strap is available with different breaking strengths according to whether a lighter or heavier tension is required. When selecting the right strap, it is important to know the dimension and weight of the pack and how it will be stored and transported.
Some companies purchase pre-printed strap either to enhance company branding or to comply with traceability regulations. Alternatively it is possible to print in-line directly onto the strap meaning that dates and batch codes can easily and quickly be entered into the printer.