When buying stretch film/stretch wrap, you need to understand the following five performance indicators. The plastic film used for stretching must have a certain degree of self-adhesion, toughness, elongation, stress retention and required stretching range, as well as optical properties and heat sealing properties.
Stretching is the ability of a film to stretch elastically after being stretched. The increase in longitudinal stretching will eventually make the film thinner and shorten the width. Although longitudinal stretching is beneficial, excessive stretching is often undesirable. Because this will make the film thinner, easy to tear, and at the same time increase the tension applied to the package.
Toughness is a comprehensive property of film resistance to puncture and tear. The tear resistance only refers to the degree of tear resistance of the film when it is under tension and punctured. The risk value of the degree of tear resistance must be taken horizontally, that is, perpendicular to the machine operation direction, because tearing in this direction will loosen the package, and even if the longitudinal tear occurs, the package can still remain firm.
3. Stress retention
Stress retention refers to the degree to which the tension applied to the film can be maintained during the stretching and wrapping process.
4. Allowable stretching
Allowable stretch refers to the maximum stretch that can be applied to maintain various necessary characteristics in a certain application. Allowable stretching varies with different uses. The larger the allowable stretch, the smaller the amount of film used, and the lower the packaging cost.
The adhesion between the films after contact, during the stretching and wrapping process and after wrapping, can make the packaged product tighten without loosening. Self-adhesiveness is affected by many external factors.
We hope with the help with our clarification, you can have better understanding of the stretch film and have the ability for identify the best stretch film.