Stretch wrap, also known as stretch film or pallet wrap is a highly stretchable plastic film which is wrapped around items via hand or machine application methods. The "elastic recovery" also known as the "memory effect" of the stretch film keeps the items tightly bound. The most common usage of pallet wrap is to palletize loose units of goods for more efficient transport and storage.
There are two main methods of production for stretch film. The older, "Blown" method and the newer "Cast" method. From a manufacturing perspective:
Blown pallet wrap: Raw materials are extruded and blown out. The film is then cooled via air during a lengthy cooling process. Due to the slow cooling process, crystals form in the film which causes a "hazy" appearance in the resulting stretch wrap. In order to acquire "cling" properties, an additive is fed into the resin. This additive renders the end product unsuitable for recycling facilities. The "cling additive" is also responsible for the loud "tearing" noise that occurs when the stretch film is unwound during use.
Cast pallet wrap: The film is passed over chill cooling rollers - a much faster cooling process. The rapid cooling process allows for a greater productive output per hour and a high clarity film which infrared scanners can read barcodes through. Cast pallet wrap has inherent cling properties due to the cooling process. This allows the end product to be recyclable, and for the unwinding of the stretch film to be comparatively silent.
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