With the increasing share of packaging film in the market, it is widely used in beverage packaging, food packaging, pharmaceutical, chemical, electronic product packaging film and other industries, which brings convenience to people’s lives. But in the market packaging film is not all high quality, so what is the judgment standard of high quality POF heat shrink film? The following is to give you an introduction.
Four aspects to identify the quality of POF heat shrink film
1.Shrinkage and shrinkage ratio
Shrinkage includes longitudinal and transverse, the test method is to measure the length of POF heat shrink film L1, then the film is immersed in glycerin at 120 ℃ for 1 ~ 2s, removed and then cooled with cold water, and then the length of L2. Ll – for the length of the film before the contraction, L2 for the length of the film after the contraction. Shrinkage film for packaging, generally requires the longitudinal and transverse direction of the shrinkage rate to be equal, about 50%; but in special circumstances there is also a unidirectional contraction, shrinkage rate of 25% to 50% or so. There are also longitudinal and transverse direction shrinkage rates that are not equal to the partial extension of the film. The ratio of the longitudinal and transverse direction shrinkage is called the shrinkage ratio.
Shrinkage tension refers to the POF heat shrinkable film shrinkage applied to the package tension. The size of the shrinkage tension generated at the shrinkage temperature is closely related to the protection of the product. Packaging of metal cans and other rigid products allows greater shrinkage tension, while some fragile or easy to fold the products shrinkage tension is too large, it will be deformed or even damaged. Therefore, the shrinkage film shrinkage tension must be selected appropriately.
POF heat shrink film is heated to a certain temperature to start shrinking, the temperature rises to a certain height to stop shrinking. The temperature within this range is called the shrinkage temperature. In terms of packaging operations, packaging in the heat shrink channel heating, film contraction to produce a predetermined tension of the temperature reached when the tension is called the contraction temperature. Shrinkage temperature and shrinkage rate has a certain relationship, a variety of different films. In shrink packaging, the lower the shrinkage temperature, the less adverse effects on the packaged product, especially fresh vegetables, fruits and textiles.
4. Heat sealing
Shrink packaging operations, before the heat shrinkage, must choose two or three-sided heat sealing, and the sealing seam is required to have a high strength. Packaging commonly used sealing methods are heat sealing method, pulse fusion sealing method, radiation sealing method, ultrasonic sealing method. Heat sealing method is an ordinary method, when sealing the flat plate (or disk) which is heated to a certain temperature is pressed on the overlapping film to seal. In order to prevent the film from heat shrinkage when sealing, it should be sealed quickly and timely cooling measures should be taken immediately after sealing.
The judgment standard of high quality POF heat shrinkable film
- Feel the identification method
Hand identification methods: POF heat shrinkable film smooth and soft to the touch is qualified, feel the stiffness of adhesion is unqualified.
- Ignition identification methods
Ignition identification methods: good quality POF heat shrink film is very easy to ignite, burning flame is obvious. Not easy to burn is unqualified products.
- Poke hole method
Poke hole method: after packaging with a finger poke a hole. If the hole poked out is only the size of a coin, then the quality of POF heat shrink film is qualified, good toughness test. If the hole poked out is long, poor toughness, can not play a protective role.
- Packaging test method
Packaging test method: the POF heat shrink film wrapped in the product, check the degree of fit; shrinkage memory function is strong, retraction tightness is good, proving that its POF shrink film quality is good.
Selection of high-quality POF heat shrink film for product packaging is crucial. This article introduces the criteria for determining the quality of POF shrink film can help you choose the most suitable POF shrink film for your product packaging needs.