Shrink wrap is a versatile packaging option that can be used for bundling, labeling, weatherproofing, tamper proofing and more. Furthermore, shrink wrap can be quite easy to use, no matter what the size of the packaging is.
What is a Shrink Wrap?
Shrink wrap or shrink film is a polymer film that shrinks when heated. Shrink wraps can be made from different types of polymers and each has its own advantages. However, when it comes to using them, the process is more or less similar. When exposed to a heat source, either by using heated air or a heat gun, the film shrinks rapidly. This happens because of the molecular structure of the film. The molecules of the film, when in the form of a roll, do not have any particular alignment.
However, when heated, the molecules quickly align themselves in a particular pattern and shrinks in size. This makes the film take up the shape of the mold of the product it is wrapping. Shrink film is useful for wrapping almost any product, either as a primary packaging or a secondary packaging. This gives a durable protective barrier. Shrink wraps are generally clear, but they can also be made opaque during manufacturing. These have printable surface.
Shrink wraps are extremely versatile. They come in multiple variants with different levels of transparency, thickness, and even shrink ratios. Different types of shrink wrap can be used with one another to get the perfect layer of protection for your product. Moreover, you can also get shrink wrap with varying sealability options, durability, memory, and temperature.
Types of Shrink Wrap
Shrink wraps mostly come in three main types. These are polyvinyl chloride, polyethylene, and polyolefin. Each of these materials provides different use cases, each having specific applications. They have a varying appearance, each provides different shelf life and come with their own distinct barrier properties. There is a breakdown of the primary variants that you get in the market.
PVC or polyvinyl chloride is one of the most common shrink film variants. It is lightweight, clear and inexpensive. However, PVC also has some issues which are why it has given way to the other two variants. Since PVC contains carbon and chloride, it releases a strong odor when heated. Therefore, it is recommended that manufacturers use it in open, well-ventilated spaces. Moreover, in some regions, the use of PVC shrink wrap is restricted. Furthermore, PVC is extremely sensitive to temperature changes and should be stored carefully. At lower temperatures, the film can become brittle while on higher temperatures, it can wrinkle easily. It also leaves carbon deposits on sealing equipment and hence, requires higher maintenance.
However, PVC is still extensively used in packaging automotive parts, packaging of CDs and DVDs and other non-edible items. In the healthcare sector, blood bags and tubings come in PVC shrink wrap.
POF or Polyolefin is a premium option. It has replaced PVC in the case of the packaging of edible products. The cross-linked POF films have high tensile strength and are quite durable. Because of the durability, large rolls with low thickness are easy to manufacture. Moreover, it also comes with great puncture resistance. POF can also be completely recycled.
In some cases, POF films require additional perforations when they are being sealed. This allows the air to escapee properly and hence creating a snug wrap. This is why you will find pre-perforated wraps in many cases.
POF shrink films is glossy and is extremely clear. Hence, it is used for books, food products, toys and other areas where appearance is extremely important.
PE or Polyethylene itself comes in three variants: HDPE or High-Density PE, LDPE or Low-Density PE and LLDPE, which stands for Linear Low-Density PE.
HDPE shrink films are useful for heavy duty bundlings, such as bundling of cereal boxes or groceries. LDPE films are suitable for heat sealing, such as for making flexible lids. LLDPE is great where there is a need for stretchable film. LLDPE does not shrink well, but the high clarity makes it perfect for applications where visibility is important.
Shrink Wrap Packaging Applications
Bundling and Shipping
Bundling is a very common application of shrink wrap and is used across various industries. Shrink wrap is often used to bundle PET bottles that are used for packaging drinking water or soft drinks. They are also used for bundling books, stationery items, electronics, groceries, farm produce and more.
Shrink film wrapping cannot be released, thereby, making it an excellent tamper-proofing and tamper evident mechanism. Often books, computer software discs, electronic products, and others come with a clear shrink wrap seal.
Product and Packaging Lamination
Shrink wrap is also used as a part of product packaging, especially in food products, such as candy. It is also used as a secondary packaging to provide additional protection from wear and tear.
Protection from Wear and Tear
Shrink wrap is often used to ship and store products. Vehicles such as boats, cars, helicopters are often wrapped using shrink wrap to protect them from storage and shipping damages.
Printed shrink wraps are used for full body labeling. Manufacturers use them for labeling bottles and jars where the label takes the shape of the container. This is extensively used in packaging of food products, beverages, and cosmetics.
Difference Between Shrink Wrap and Stretch Film
Often shrink film is confused with stretch film since both are mostly used as overwraps. The main property that separates shrink films from the rest is that it shrinks when heat is applied. Stretch film is used for bundling or grouping multiple products together on a pallet.
They are low-cost, versatile films that are used for protective packaging. Shrink wrap, on the other hand, is often a part of the primary packaging, have better aesthetics, and provides surface damage protection. Shrink wrap is used to wrap single products too. To use shrink film, a heating machine is necessary.
Advantages of Using Shrink Wrap
- Protection: Shrinkwrap offers decent surface protection at a low cost. For products with sharp edges, cross-linked films perform better. Moreover, for perishable products, shrink wraps increase their shelf life, thanks to its barrier properties.
- Improved aesthetics: Shrink wraps are often used for labeling because they can easily take the shape of the product they are wrapping. Hence, it is quite common in the beverage industry to use shrink wrap labeling.
- Sustainable: Shrink wraps made from PE and POF are recyclable. Hence, they are quickly replacing PVC wraps.
- Low cost: Shrinkwrap offers the protection and aesthetics of premium packaging options at a much lower cost. They can wrap heavy or light products, they can protect food products and increase their shelf life, and they can be used for bundling without the use of trays or other rigid packaging options.
Cost of Shrink Wrap
Shrink wrap rolls cost quite low. A six-inch-wide roll costs around ₹150. A heat gun is available in about ₹1000. This is good for home use, or for those running small businesses from home. However, the cost goes up when you are going for automatic or semi-automatic sealers. The most basic combination for slightly larger business is an impulse sealer and a heat gun. For heavier shrink films, flat wire impulse sealers are required and their cost starts from ₹2,000. Impulse sealers with cutter blades are even more expensive.
High output shrink-wrap machines or shrink wrap tunnels for factory use cost several thousand dollars. However, for larger businesses, these are just one-time investments. Since the cost of shrink wrap rolls is so low, one can balance the cost of the automated sealing machines quite easily. This makes the entire setup much cheaper than other forms of packaging.
How to Use Shrink Wraps
For small products, using shrink wraps can be quite basic. All you need is an impulse sealer and a heat gun. For occasional use, even a hair dryer and a pair of scissors will do.
First, you have to cut the film according to the size of the item you are wrapping. After completely wrapping the item, there should be enough shrink film left that can be fused together by the impulse sealer. Place the open side of the wrap in the impulse sealer and seal the shrink wrap. Sealers with cutters will automatically trim away the excess material. With the product inside the wrap, use the heat gun to shrink the film down. Use the heat gun from a distance so that the shrinking happens uniformly.
If you do not have these at your disposal, then you can simply wrap the item using the shrink film and heat it with a hairdryer. This will not create a perfect seal, but it will be close. To trim off the excess film, you can use scissors or a box cutter.
Shrink wrap is a low cost, versatile and sustainable packaging option that many businesses, small and large, have adopted. Shrink wraps can be a great option for manufacturers who are looking towards reducing the amount of plastic in packaging. They offer great barrier properties, offer decent levels of surface protection and can also be recycled.
You might also like to read about different types of packaging products available in the market.