1. Identification of equipment
Tensile testing machines and puncture testing machines can be used to test the quality of stretched films. However, these methods are for systematic inspection, and most people do not have such inspection standards. So in general, the following methods can be used,
2. Look at the appearance to distinguish
The appearance of the stretched film is mild in color, of course, with good clarity. Place a newspaper and periodicals just under 20 cm of the stretched film, and you will not be hindered to read the article if you can see the words. Shows that there is a high-quality stretch film. On the contrary, it is a shoddy stretch film. Generally, ordinary stretched films are relatively dark, and good stretched films are relatively transparent.
3. Smell the smell of stretch film
The quality can be identified by asking the smell of the stretch film product. If it smells, there is no pungent smell, but there is only a slight plastic smell, indicating that the quality is acceptable. On the contrary, the quality is not good, it smells quite pungent, there is a smell of plastic mixed with recycled materials.
4. Judge according to the stretch ratio
We can stretch the film from the length of the stretched film outward, and then stretch it from the transverse direction, which can also be a good judgment of the quality; if it is too thin a stretched film, the toughness can be seen without testing. Extensibility is not good. The high-quality stretch film can stretch very long, within the range of 300%-700%, and is not easy to be broken. The inferior stretch film becomes soft when it is stretched, and it will break when pulled.
5. Identify by stickiness
The adhesion of the stretched film after contact between the films can make the packaged product tighten without loosening during the stretch winding process and after the wrapping. For example, encapsulating a raw egg and developing a pressing posture can lift the raw egg, while the fake stretch film does not have this effect.
6. Toughness of stretch film
Toughness is a comprehensive property of film resistance to puncture and tear. When the stretch film is torn, but the packaging can maintain a firm condition, it shows that the quality of the stretch film is high quality, on the contrary it is fake and inferior. You can also encapsulate the stretched film with water. After a puncture, it is generally not easy to see water at a depth of 5 cm, indicating that it is of high quality. On the contrary, the quality is not good.