Stretch Wrap

Stretch film, or stretch/cling film, is used to unitize goods for transportation. A thin film is stretched, either by machine or by hand, and wrapped around packages to hold the goods together. The film clings to itself and to the pallet, securing the load. In its most common form, stretch/cling film is applied to a stacked pallet using a power pre-stretch pallet wrapper in an automated operation. In this operation, the film is stretched, between 100% and 300%, by rollers turning at different speeds and is then applied to a loaded pallet that sits atop a moving turntable. Machine wrap film is typically supplied on rolls that are 20- or 30-in. (51- or 76-cm) wide. Hand wrap film is supplied on smaller rolls. Stretch/cling films may be manufactured by either a cast film or blown film process. Most stretch/cling films are layers. Most cast film lines are now being installed with five-layer capability, and blown film coextruded films are typically three layers. LLDPE is the primary component of most stretch films. For specialized applications, coextrusions containing minor PP, EVA, POP, m-LLDPE, EPE, or ULDPE layers may be employed. 

For most stretch film structures, a resin with good inherent cling is used on either one or both surface layers. A tackifier, such as poly-isobutylene, can also be added to the structure to provide the desired cling force. Stretch film is used to unitize entire or partial pallets stacked with products such as resin bags, fertilizer bags, consumer goods, and food products during distribution. Most stretch film is removed by the retailer prior to displaying the packaged items for sale. Stretch films must have the following: 

• good cling 

• stretchability 

• load retention 

• puncture resistance

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