Plastic is currently the main medium for packaging because it is lightweight and affordable. Previously, PVC was the go-to material of choice but that is no longer the case today.
Advancements in science and awareness towards socio-environmental health led to the creation of polyolefin shrink film. Now POF is the most popular shrink wrapping plastic used across a vast range of industries. Why? The reasons are many.
What is POF shrink film?
It is a type of translucent film or polymer plastic sheet that has become the preferred choice for packaging both edible and non-edible goods in the manufacturing sector.
The name “shrink film” was created because plastic shrinks tightly over whatever it is covering when heat is applied to it. Thus, “shrink wrapping” using shrink film.
POF shrink film is made from POF which stands for polyolefin. In the past, PVC (Polyvinyl Chloride) film was widely used for shrink wrapping but it is slowly being replaced by POF shrink film.
What is POF?Polyolefin is actually a group of hydrocarbons, i.e. compounds containing hydrogen [H] and carbon [C] atoms. It is often derived from natural gas or from low-molecular-weight constituents of petroleum.
As a thermoplastic, the polyolefin is popular because it is extremely easy to mould, to shape and can be reshaped over and over again simply by repeating the heating, moulding and cooling process. POF also has several other good qualities which makes it safer than PVC.
There are two main types of POF – polyethylene and polypropylene. These are further subdivided into several grades for different applications.
What is POF shrink film used for?Polyolefin shrink film is used for almost every kind of application. Essentially, it is used to protect and package a single product, or to bundle multiple products together.
It is particularly favoured for packaging less rigid items such as foodstuff, stationery, cards and electronic items, just to name a few.
Qualities of POF shrink filmThe following are the extensive qualities that make POF shrink film a popular packaging material worldwide:
Anti-fog
Durable
Versatile
Seal-strength
Fairly low-cost
Tear-resistance
Low shrink force
Puncture-resistance
Wide range of gauges
Excellent tensile-strength
Can be pre-perforated –
no air pockets
Can be made from 100% recyclable material
Clarity and glossiness – makes for excellent shelf appearance
Stable – not as affected by temperature changes compared with PVC
FDA-approved food-safe material – suitable for the Food & Beverage industry
Ability to shrink quickly and completely – shrinks when heated resulting in a finished good as soon as it comes out of the shrink tunnel)
Polyolefin is also available with different characteristics, including cross-linked wrap which provides high-tensile strength and incredible clarity for high-speed packaging applications, as well as prevents buildup on sealing components of your packaging machinery.
As POF shrink film easily bends to low temperatures, it does not deform, bend or collapse thin, flimsy or delicate products. This quality also provides excellent protection for irregular-shaped items.
Common terms related to shrink wrapping
Gauge – a measurement used to describe film thickness
Shrink force – (shrink energy) the amount of force that the shrink film will exert on your product
Tear resistance – the ability of a film to resist tear with forced exertion on the film
Shrink tunnel – equipment that uses a chamber to produce heat with a continuous conveyor running through the chamber
Centerfold shrink film – film that has been folded in half lengthways to make wrapping easier and quicker
Crow’s feet – wrinkles diverging out from a finished package’s corners
Dog ears – triangular projections of unshrunk film at the corners of complete packages (common in packages wrapped with PVC shrink wrap)
Impulse sealer – a sealer using a heating element that is pulsed with voltage during the sealing process to mend polymer materials together
L-Bar sealer – a sealer where the sealing surface is in the shape of a backward “L”
Lap seal – making a seal using two layers of shrink film lapped over each other
Machine direction – the direction the film is manufactured and moves through the sealing equipment
Memory – the ability of a shrink film to maintain characteristics after sealing
Optics – the visual properties of a shrink or stretch film
Thickness conversion chart
POF is available in various thicknesses, from as low as 35-gauge (0.35 mil) up to 100 (1 mil) gauge. Sometimes, the term “micron” or “mil” is used instead to indicate thickness. Here is a thickness conversion chart for easier reference.
1 Gauge = One-hundredth of a Mil
100 Gauge = One Mil Thickness
1 Gauge = 0.254 Microns
100 Gauge = 25.4 Microns
1 Mil = one-thousandth of an Inch
1 Mil = 25.4 Microns
Industries that use shrink wrapFood: It is one of the largest industries that commonly use shrink wrap. Wrapping in shrink film helps to remove oxygen contact from the food and can reduce waste.
Printing & Paper Products: Many companies in this industry use shrink wrap to protect their products and goods as well as to detect and deter tampering.
Pharmaceuticals: Shrink wrap is used to help seal caps and detect tampering.
Hardware & Housewares: Shrink wrap is commonly used to deter and detect tampering as well as bundle multiple products together.
Electronics: The electronics industry commonly uses shrink tubing and shrink wrap.
Miscellaneous: There are a variety of other industries and uses for shrink wrap. The marine industry, for example, commonly uses shrink wrap to winterize boats and protect them from environmental elements.
Games & Sporting Goods: Manufacturers, resellers, wholesalers, and retailers use shrink wrap for wrapping a variety of goods and products. PVC shrink wrap is frequently used for these items.
Differences between “shrink wrap” and “stretch wrap” Shrink Wrap Stretch Wrap DefinitionTo wrap an object with shrink film
To wrap an object with stretch film
UsageTo create a seal that envelopes an entire object to protect it, especially from tampering
To hold large items together, prevent them from shifting during shipment
ItemSingle or multiple
Boxes or cartons
StretchabilityShrink film can stretch 50 to 75%
Stretch film can stretch 100 to 300%
ApplicationShrink film is placed loosely around an item and heat is applied on it to make the film shrink around the item
Stretch film is wound a few times around the items
StickinessShrink film cannot cling to itself
Stretch film has the ability to cling to itself
Differences between PVC and POF
To the non-discerning, a PVC shrink film and POF shrink film may be the same. However, there are vast differences which have made POF the favoured material over PVC.
PVC stands for Polyvinyl Chloride. PVC shrink film was most commonly used until several years ago when it got replaced by polyolefin (POF) shrink wrap. There are a few reasons for this.
1. Common drawbacks of PVC Shrink Wrap – sealing strength, storage issuesThe plasticizer in PVC Shrink becomes brittle in cold conditions and wrinkles under hot conditions, thus compromising the strength of the seal and the plastic.
Polyolefin shrink wrap also does not have any plasticizers, so the temperature is not an issue. Polyolefin can be stored in a wide range of temperatures and does not harden or soften in different environments like PVC shrink film.
2. Harmful sealing by-productsPVC shrink wrap also releases small quantities of hydrogen chloride into the air and carbon deposits onto the sealer. Proper ventilation is required when sealing PVC shrink wrap.
Polyolefin shrink film produces fewer odors when sealed because its material does not have any chlorine. Therefore, the film does not produce HydroChloric gas as a by-product.
3. Health and safety concernsWhen PVC is heated, it releases HydroChloric gas. For this reason, PVC poses a danger to the health of factory workers during production and the public during incineration or decomposition.
Many countries have banned the use of PVC. Brands that hold high regard for corporate and social responsibility have also banned PVC in their product packaging. This is an important consideration for brands. Some stores have limited products that use PVC packaging, such as Walmart.
4. Maintenance costPVC leaves carbon deposits on the sealer. This causes regular maintenance in order for the sealer to operate consistently.
Recommendations for POF shrink wrap usageTools and machinery for POF shrink wrapping
Typical tools are heat guns, L-Bar sealers, I-Bar Sealers and shrink tunnels. When using shrink wrap, a heating instrument will be needed to shrink the film. Certain machinery may be required depending on the desired application.
Can a hairdryer replace a shrink wrap heat gun?
No, a heat gun is recommended for a professional look.
Does a shrink wrap machine cut and seal the shrink wrap at the same time?
Yes, most of them do. Once sealed and cut, the scraps can be peeled away, and heat can be applied to the shrink wrap. The heat will reduce the size of the shrink wrap film and help to conform it to the product.
What gauge of shrink wrap do I need?
It depends on the weight of the product. The heavier the product, the bigger the gauge.
How much shrink film is needed?
Measuring for shrink film is relatively simple, but is determined by the type of shrink product you intend on using. See below for measurement formulas for every kind of film. Remember, if the exact size needed is not available, go to the next size up. All of our shrink film has a shrink rate of at least 30%.
There is a wide variety of POF shrink film in the market. Each brand or type has a different shrink rate. The size of film needed for sealing a product depends on the shrink rate of the film, but there are a few formulas for measuring in general.
Centerfold Shrink Film Measurement FormulaWidth + Depth x 2 x 1.1÷2 = Centerfold Film Width Needed
Shrink Bag Measurement FormulaFor bag width: Width + Depth x 2 x 1.1÷2 = Centerfold Film Width Needed
For bag length: Width + (Depth +2 inches) x 2 x 1.1÷2 = Centerfold Film Width Needed
Shrink Tubing Measurement FormulaFor squared objects: Width + Depth x 2 x 1.1÷2 = Centerfold Film Width Needed
(but most people use tubing for cylindrical purposes)
For circular objects: Circumference x 2 x 1.1÷2 = Tubing Width Needed
ConclusionWhen deciding on the best type of shrink wrap for your product, the cost is definitely a huge factor. Nonetheless, the cost of POF shrink wrap has become very competitive due to increased production to fulfill a worldwide demand.
The long list of positive qualities of polyolefin shrink wrap and its safety factor also explains why it is the best choice for food, beverage and consumer product packaging.
Cost of the HSA and environmental factors in the production process and POF becomes a better option than POV at any time.
Local and global consumers are also increasingly aware of the environmental and health impacts of their buying activities. This has forced big brands to be cautious of packaging material for their products. If POV shrink wrap is safe for wrapping edible items, it is safe for non-edible items and the environment.
Sources:
WILEY-VCH. Polyolefin Reaction Engineering. First Edition. Joa˜o B. P. Soares and Timothy F. L. McKenna. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2012 by Wiley-VCH Verlag GmbH & Co. KGaA (Print) Available on: https://application.wiley-vch.de/books/sample/3527317104_c01.pdf [Accessed on 25 June 2020]
Encyclopaedia Britannica. Polyolefin. (Online) Available at: https://www.britannica.com/science/polyolefin [Accessed on 25 June 2020]
US Packaging & Wrapping LLC. Shrink Film 101. (Online) Available at: (https://uspackagingandwrapping.com/shrink-film-101.html) [Accessed on 25 June 2020]
US Packaging & Wrapping LLC. 5 January 2017. Sustainable Packaging: The Walmart Sustainability Playbook. (Online) Available at: https://www.industrialpackaging.com/blog/walmart-sustainability-playbook [Accessed on 25 June 2020]
United States Plastic Corp. What is the difference between a stretch wrap and shrink wrap? (Online) Available at: https://www.usplastic.com/knowledgebase/article.aspx?contentkey=957 [Accessed on 25 June 2020]