Heat shrink film is a commonly used material in the packaging industry, and its unique shrinkage properties make it very useful for packaging products. In this article, we will take an in-depth look at the shrinkage principles of heat shrink film to better understand its application in the packaging process.

What is heat shrink film

Hot shrink film is typically made from polyolefin materials such as polyethylene (PE) or polypropylene (PP), which possess high elasticity and flexibility. When heated, these materials shrink and tightly wrap around the surface of the packaged item.

The principle of heat shrink film

Heating process

When heat shrink film is exposed to a certain temperature, the polymer chains in it begin to relax and become active. As the temperature increases, the gaps between the molecules widen, making the film material softer and more moldable. This heating process is a prerequisite for shrinkage to occur in heat shrink film.

Shrinkage process

While heating, the surface tension of the heat shrink film increases, causing the film material to shrink towards itself. This shrinking process causes the film material to shrink in both the longitudinal and transverse directions, enabling it to tightly adhere to the surface of the packaged item, forming a secure packaging.

Scope of application

The shrinkage characteristics of heat shrink film make it suitable for packaging objects of various shapes and sizes, whether flat, round, or irregularly shaped items.

Control the degree of shrinkage

By controlling the heating temperature and time of the heat shrink film, the degree of shrinkage can be adjusted. Usually, the higher the heating temperature, the greater the shrinkage, and the longer the heating time will also increase the shrinkage. Therefore, it needs to be adjusted according to the specific packaging requirements in the actual application.

    POF Heat Shrink Film

    Key factors affecting shrinkage rate

    1. Material type: Different polymers have different shrinkage rates, e.g. PET typically shrinks 40%-70% while PVC shrinks 20%-50%.
    2. Tensile strength: Tensile strength is the ratio of the length of the material after stretching to the original length. The higher the tensile multiplier, the higher the internal stress of the material and the higher the shrinkage.
    3. Heating Temperature: The higher the heating temperature, the more energy the molecular chains receive, resulting in a higher shrinkage rate.
    4. Heating time: The longer the heating time, the more time the molecular chains have to move, resulting in a higher shrinkage rate.

    POF heat shrink film-


    By analyzing the shrinkage principle of heat shrink film, I trust you now grasp its application in the packaging industry. Its unique traits offer efficient, attractive, eco-friendly packaging solutions, making it an essential material in modern packaging.