Shrink film, a kind of packaging material, is reaching the height of its popularity because of its versatility and cost-effectiveness. Various applications involved are cosmetics, food packaging, electronics, and pharmaceuticals.

Shrink Film Defined

Shrink film is a plastic sheet composed of polyvinyl chloride (PVC) materials. The extrusion process produces shrink films. Extrusion involves melting the plastic and pushing it through a die to make a thin sheet. It is then cooled and rolled for distribution.

Two Kinds of Shrink Films

Among the different kinds of shrink films, polyvinyl chloride and polyolefin shrink films are the most popular ones. Many choose PVC because of its various advantages. These include being less costly, easier to handle, and having high clarity. The food and beverage industry opts for PVC because it is of food-grade quality. However, there are issues with PVC such as the emission of harmful fumes during heating.

Polyolefin shrink film is the more recent and more eco-friendly choice compared to PVC. It provides flexibility, strength, and high clarity. Polyolefin is safer compared to PVCs as it does not emit harmful fumes when heating.

How Shrink Films Work

There is truly Science that works behind shrink films. Shrink films stretch in a biaxial orientation which is stretching in both vertical and horizontal directions. This process aligns the polymer chains so they can return to their original state. The film starts to shrink when heat is applied releasing the tension.

There are lot of information that one can know about shrink film. The following are seven characteristics that one has to know when considering the shrink film, one needs for packaging.

1. Shrink Force (Shrink Energy)

Shrink force, which is also known as shrink energy, is measured is PSI. This provides information on the amount of force that the shrink film will exert on a product. If the product is a multi-pack package that requires to be tightly contained without being damaged, one’s knowledge of the shrink force is highly required to adjust the shrink machinery properly. If the PSI of the shrink force is high and wood is the material to be packaged, this will not matter.

On the other hand, if one is to package lightweight chipboard boxes or a small stack of paper, a high PSI will matter. It is a fact that polyolefin films are high-valued shrink-force films. Polyvinyl chloride (PVC) films are low-valued shrink-force films. There is new technology regarding formulations on polyolefin that decrease amounts of shrink force.

2. Shrink Orientation

Shrink films could either be preferentially oriented or bi-axially oriented. Preferentially oriented film shrinks differently in either direction. The advantage of using a preferentially oriented film involves the use of less film which prevents product distortion. On the other hand, a bi-axially oriented film shrinks equally in both directions, whether it is in a cross direction or a machine direction.

3. Shrink Percentages

The shrink percentage is the amount the film experiences in terms of size reduction. Various kinds of shrink films have varying shrink percentages that range from 20% to 40%. This can also be decreased through the use of a bi-axially oriented film or a preferentially oriented film.

The free shrink is a closely related characteristic. Free shrink is the value of shrinkability a film makes before making contact with the product. High values of free shrink allow one to obtain a better-looking package on difficult shapes and sizes.

4. MVTR (Moisture Vapor Transmission Rate)

The MVTR measures the amount of moisture that will or will not travel through the film. This characteristic is significant especially if there must be a low moisture transmission into or out of the package as this affects the shelf life of the product.

5. Resistance to Puncture/Tear

This is the measure of the ability to break the film or the capacity to tear the film once it has been punctured.

High-resistant films have lower resistance to tear while low-resistant films have greater resistance to tear. This characteristic is significant to consider especially when puncture resistance is very important. There must be a balance between ease of access to the actual product and with security of the product. Shrink wraps must be kept cooled in a storage area to prevent the weakening of the film before it is used.

6. Odor Barrier

Shrink films are used as barrier films to prevent unwanted odors from travelling into or out of the package. It is never a good practice that customers will purchase a product with a bad smell.

7. Antifog

Antifog films are utilized on fresh and frozen food to prevent moisture build-up on the film. Moisture can result in a fog that influences the view of the product through the film. Buyers often do not buy a package that is fogged up.

It is important to be familiar with these seven characteristics of a shrink film. These should be put in mind in choosing a packaging for the products. It is a must that all of these should be covered by the supplier who supplies the products.

Beginning to understand the characteristics of these shrink films can affect the management of a business. Understanding shrink films can shrink costs. It is thus important that buyers should discuss this with their suppliers.

If you need a trusted supplier for a shrink film, you can get in touch with us in Zhongcheng. We ensure that it is a name that you can trust.