The three main wraps commonly used in shrink packaging for protecting and securing products for the retail and shipping environments are polyvinyl chloride (PVC), polyethylene (PE), and polyolefin (POF). Each have different capabilities and characteristics that make them suitable for specific applications.
What are the main differences between these types of shrink wrap? Which is the best choice for your packaging needs? Read on to find out!
Each of these three wraps can be co-extruded into multilayer wraps with different additives offering specific barrier properties required for shelf-life or appearance. Shrink wraps can be formed into flattened rollstock, bags, overwrap, banding and tubing, and add a form of tamper-resistant protection to packaged goods. If you aren’t sure that you are using the ideal wrap for your application, here’s a breakdown of the three:
Once the most commonly-used shrink packaging material in the world due to its light-weight and inexpensive multi-purpose capabilities, PVC Shrink wrap has since taken a backseat to PE and POF for many reasons. Most specifically due to the dangers in health during productions and incineration, and sustainability.
In its rigid form, PVC is durable and is used in many applications, including construction projects and houseware products. In terms of packaging, PVC is seen in rigid applications including blister and clamshell packaging, & flexible applications including shrink wrap, bagging. Polyvinyl chloride is a combination of three elements, carbon, hydrogen, and chlorine.
It is recommended for use in well-ventilated facilities due to the strong, harmful odors that are released when heated. Due to its chemical composition and these harmful byproducts released during its creation, and decomposition for that matter, PVC has been banned in many countries.
Polyolefin shrink is an extremely durable and versatile ‘premium’ shrink wrap. It has taken the place of PVC mentioned above in many applications, and is also an FDA-approved food-safe material. Polyolefin materials are available with different characteristics, including cross-linked wrap that provides high-tensile strength and incredible clarity for high-speed packaging applications. Cross-linked wrap also prevents buildup on sealing components of your packaging machinery
With added strength, the ability to create longer rolls of wrap with thinner gauges available that allow for less roll change-over and increased efficiency and productivity. Polyolefin shrink wrap has excellent puncture-resistance and seal-strength, allowing for irregular-shaped items to have excellent protection throughout its supply chain life-cycle. POF is available in thicknesses as low as 35-gauge (.35 mil), and is more commonly available in 45,60, 75 and 100 (1 mil) gauges.
The versatility and fairly low-cost that POF offers for multiple machines and packaging forms makes it a go-to form of protective packaging manufacturers of any size. In some instances POF will need perforations added to the wrap; tiny holes added to the wrap before application which allow air to escape during the shrinking process for a smooth package. Pre-perforated shrink wrap is available by many suppliers for this reason.
Polyethylene is a type of polyolefin, meaning it is a single monomer wrap that is formed with the addition of ethylene during polymerization. PE is used in several forms of flexible protective packaging including shrink wrap and stretch wrap, and performs very differently for each.
There are multiple forms that PE can take, but the three most common would be Low-Density Polyethylene (LDPE), Linear Low-Density Polyethylene (LLDPE), & High-Density Polyethylene (HDPE). Each of these are best used in different industrial applications, but for shrink packaging LDPE would be the most common form.
The benefits of using LDPE over the other forms of shrink film would be added strength and durability for heavier, larger items, like multipacks of beverages. These wraps are also printable and can have excellent graphics added while still maintaining the image and the strength required.
Where POF and PVC are limited in gauge thickness to usually around 100 gauge, higher gauges of PE are possible up to 1200 gauge! These thicknesses are used in Marine industrial applications, like shrink-wrapping a boat for storage. The disadvantages of PE for shrink are that it doesn’t have a high shrink rate, usually around 20%, and it has significantly lower clarity than the other wraps.
The Difference Between Shrink Wrap And Stretch Wrap
Shrink wrap and stretch wrap are often confused as they look very similar, but they perform very differently. When PE is used in a shrink wrap application, it is loosely placed over a single item or multiple items and will shrink around them when heat is applied, creating a tight, tamper-resistant seal of protection. When PE is used in stretch applications, it is formulated differently to be able to stretch around items.
The elastic-memory of the wrap, along with its ability to cling to itself, keeps a tight layer of protection around the items. Stretch wrap is generally used for palletizing, AKA unitizing, multiple items on a pallet to keep them from shifting during shipment. Stretch wrap usually stretches about 100-300% where shrink wrap will typically only stretch to around 50-75% before breakage occurs.
Posted by Thuận Minh Phát.