May. 13, 2024
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This article is about heat shrink film. For tubing, see Heat-shrink tubing
Grocery vegetables wrapped with a plastic shrink film.
Shrink wrapped ball of twine
Shrink wrap, also known as shrink film, is a material composed of polymer plastic film that shrinks tightly when heat is applied to it. The heat sources can be handheld heat guns, either electric or gas-powered, or it can stem from heat tunnels through which products pass on conveyor belts.
Polymer Components of Shrink Wrap
The most commonly utilized shrink wrap is made of polyolefin, which comes in various thicknesses, strengths, and shrink ratios. These films can be either crosslinked or non crosslinked. In addition, there are other variants like PVC, Polyethylene (PE), and Polypropylene (PP).
For specific mechanical and barrier properties required in food shrink wrapping, coextrusions and laminations are available. For example, a configuration might involve layers such as EP/EVA/copolyester/EVA/EP, where EP is ethylene-propylene and EVA is ethylene-vinyl acetate copolymer.
PVC is widely used due to its lightweight and low-cost nature. It is tough and suitable for many purposes. However, it must be utilized in well-ventilated areas to prevent the release of harmful fumes. Some disadvantages of PVC include its low shrink force and carbon deposit formation during shrinkage.
Polyolefin (POF) shrink wrap is a superior alternative, offering excellent durability and versatility. It is FDA-approved and made from fully recyclable materials, available in various gauges. POF is puncture resistant and provides a clear and glossy appearance, making it perfect for bundling irregularly shaped items.
Polyethylene (PE) is used in several flexible protective packaging forms, including LDPE (Low-Density Polyethylene), LLDPE (Linear Low-Density Polyethylene), and HDPE (High-Density Polyethylene). LDPE is recommended for shrink wrapping because of its strength and durability.
Manufacturing Process of Shrink Wrap
Shrink films can be either unidirectional or bidirectional in their shrink capabilities. The process of stretching film while it is warm orients the molecules in one or two directions. When cooled, the film can shrink back to its original dimensions upon reheating.
The two main techniques for achieving this orientation include the tenterframe process and the bubble process. Tenterframe technology is often used for heat-set products. The bubble process inflates a recooled tube into a bubble, orienting it in multiple directions simultaneously.
Shrink films today feature various multi-layer constructions that add attributes like shrink ability, sealability, clarity, toughness, and slip.
Applications and Uses of Shrink Wrap
Shrink wrap is applied using automated systems, heat guns, or heat tunnels. It can take forms such as flat roll stock, centerfolded film, or pre-formed shrink bags.
Beyond standard packaging, shrink wrap is used for various potentially unexpected operations. It’s useful for wrapping large structures after natural disasters, creating environmental containment setups, or even wrapping books and software to prevent tampering.
Vegetables like cucumbers are often individually shrink wrapped to extend shelf life. Shrink wrap is also commonly used for overwrapping packaging like cartons, beverage cans, and pallet loads, ensuring product stability and cleanliness.
Shrink bands serve as tamper-evident seals, while heavier weight shrink wraps are used in industrial settings, such as for marine wrapping, disaster relief, and containment of large equipment.
Today in Tedium: Shrink-wrap, a ubiquitous yet often overlooked plastic, is crucial for many consumer goods. Originating as a tamper-evident material, its role in retail and packaging is significant. What makes shrink-wrap unique is its ability to tightly conform to packages, ensuring they are original and unused. Unpacking this history and its many uses proves to be a fascinating story.
Today's GIF features an image of someone shrink-wrapping their sneaker, which is something sneakerheads apparently do.
The year Ralph Wiley, an employee at Dow Chemical, inadvertently discovered polyvinylidene chloride (PVDC). This discovery, leading to the creation of Saran Wrap, revolutionized food packaging. Despite its initial popularity, SC Johnson eventually reformulated it due to environmental concerns.
Recently, a Lifehacker video demonstrated a simple yet powerful shrink-wrap concept using a plastic bag and a hot knife. This technique, akin to how shrink wrap operates, shows how heat transforms plastic into tight-sealing films, making it indispensable in packaging.
Polyethylene variants in shrink-wrap, such as those used in Ziploc bags, respond similarly to heat, reaffirming the close relationship between plastic and heat.
This heating principle underpins innovations in packaging, providing secure seals for various goods. The use of shrink-wrap results from synergy among chemistry, engineering, manufacturing, and physics.
The year Raychem Corp. was founded, specializing in heat-shrink tubing for electrical wiring. This innovation, involving radiation treatment on plastic, secured changes in wiring with heat, influencing broader shrink-wrap applications.
Shrink wrapping of food items began with vacuum-sealed poultry in the 1930s. Cryovac Inc. innovated this technique, leading to its formation in 1946. The combination of heating and cooling cycles effectively preserved and packaged meats.
In the 1950s, ionizing radiation treatment of plastic changed the shrink-wrap process, making it suitable for various consumer goods. The particle accelerator technology enhanced the plastic's properties, making it malleable and more effective for packaging.
The transformative impact of these technologies extended beyond food packaging, influencing several industrial applications.
"Sous-vide is just as much about the science as it is the art."—Bruno Goussault, inventor of the sous-vide cooking technique. Initially developed in 1971, sous-vide, or "cryovacking," shares principles with shrink-wrap technology, utilizing plastic wrap and heat for food preservation.
Shrink-wrap is versatile, finding applications in:
The year Samsung announced it would reduce non-biopolymer plastics in packaging, favoring sustainable materials despite cost increases.
Title "Shrink-Wrap Authenticity: Myth or Reality?"
Shrink-wrap, while often seen as a mark of authenticity, can be easily replicated with basic tools. This brings into question its reliability for collectors seeking genuine products.
DIY videos highlight how straightforward it is to achieve professional-looking shrink-wrap results, deceiving even those well-versed in identifying genuine packaging.
The collector community, particularly with items like vinyl records, faces challenges as counterfeiters replicate rare hype stickers and create fraudulent shrink-wrapped items for higher resale value.
Shrink-wrap's perceived authenticity might be overrated, yet its role in packaging remains vital, whether protecting valuable sneakers, securing luggage, or for those captivating unboxing videos.
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