Stretch film or wrap is generally known in the industry as a material that can be used to securely wrap a collection of objects together using the stretch material's resiliency and clinginess. Stretch wrap is typically understood to be a polyethylene stretch film that is generally dispensed from a roll form for use in a variety of applications. For instance, stretch wrap is held against a collection of objects and dispensed and stretched around the collection of objects and wrapped over itself up to several times to cover and hold together the collection of objects. In the shipping industry, for example, a collection of materials may be placed on a pallet to secure such articles together during the shipping process. A collection of boxes placed on a pallet can be shipped as a single cohesive unit when bound together through wrapping with stretch wrap. Other applications of stretch wrap are known such as wrapping agricultural products or simply binding together a collection of items.
Although such usages for stretch wrap are well known and documented, the amount of stretch wrap used in any given application can be extensive. For example, for an industrial supplier that ships large numbers of pallets of materials out on a consistent basis, a large inventory of stretch wrap must be maintained to facilitate the regular shipment of such products. For example, a large amount of stretch film may be necessary to wrap a given pallet of materials. Typically, during application, a tension is applied to the stretch film as it is applied to the objects being wrapped. This tension stretches the film to facilitate a secure binding of the wrapped objects together, and this tension process also both strengthens the stretch film and allows for the use of less film. In typical approaches, the stretch creates a lengthening of the stretch wrap, but also creates significant narrowing of the stretch wrap in the direction not under tension. The narrowing causes less coverage of the object being wrapped and eliminating much of the efficiency gained in stretching the stretch wrap. One known device includes an idler roller that engages and rotates with the stretch wrap as it is pulled from its roll. The idler roller facilitates stretching of the wrap along its length due to the tension on the film. The roller also generally maintains the film's flat shape as it engages the object around which it is being wrapped. Although this stretch is advantageous, some narrowing does occur and further stretch and strength is still desirable. Another known approach is to stretch the stretch wrap with tension in the long direction while holding the sides of the stretch wrap to reduce narrowing. Such an approach is largely done through complex and expensive machinery. Another common application for stretch film is the containment and shipment of agricultural products where these products need to be ventilated to avoid spoilage or for evaporation of water. Current applications use stretch film that has holes cut into the film to allow the film to breath. This process is either done in-line during the manufacturing of the stretch film with expensive equipment or done off line as a secondary operation using expensive equipment to wind, perforate and then rewind the film. Moreover, it is common to secure the wrapped objects to the pallet through use of one or more straps. Such straps are typically metal or plastic bands that wrap over the object and through the pallet's under body. The metal or plastic band has two ends that are pulled tight and clamped together to secure the load to the pallet. Such strapping is expensive and generally not reusable. In addition, it is time consuming as the user must move the strapping over to the package, tighten the strapping with tooling and then secure the strapping together using some type of mechanical device.
The containment strength of stretch film is typically horizontal (around the load) rather than vertical (top to bottom) of the load. Often companies uses both strapping and stretch film in combination to best secure a shipment. This combination provides the maximum amount of containment force.
USPTO Backgrounds
USPTO Backgrounds