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Stretch wrap or stretch film is a highly stretchable plastic film that is wrapped around items. The elastic recovery keeps the items tightly bound. In contrast, shrink wrap is applied loosely around an item and shrinks tightly with heat. It is frequently used to unitize pallet loads but also may be used for bundling smaller items. Types of stretch film include bundling stretch film, hand stretch film, extended core stretch film, machine stretch film and static dissipative film. ==Materials== The most common stretch wrap material linear low-density polyethylene or LLDPE, which is produced by copolymerization of ethylene with alpha-olefin There are two methods of producing stretch wrap. 1) Blown: the resin is melted and extruded through an annular die, it is air-cooled. This is a slower process but provides for higher quality in all the areas listed below. The cost of production is also higher due to the quantity that can be produced per hour. 2) Cast: the film is extruded through a slot die, then passed over cooling rollers. This makes the cooling process quick. The quality is not as good as blown but more can be produced in an hour with lower costs. Other properties such as break strength, cling, clarity, tear resistance, static discharge, etc. are also important. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stretch wrap」の詳細全文を読む スポンサード リンク
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