Stretch film has the advantages of toughness, impact resistance, transparency and self-adhesiveness. Whether it is used for collective product packaging or cargo pallets, it can effectively prevent moisture, dust and reduce labor costs, improve work efficiency, and protect products. And the purpose of reducing costs.

 

Many users think that the adaptation of PE stretch film is very simple, but it is not. Its use process, links, steps, precautions, etc. are more complicated. So what is the effect of tension on the stretch film? The following will be introduced by the Zhiteng stretch film manufacturer.

 

The surface tension of the stretched film depends on the free energy of the surface of the plastic film. Therefore, its surface tension has many influence factors. Stretch film tension is the resistance of the substrate to the tensile force per unit area of ​​its cross-section, in kg/m² or M/m². The tension displayed on the device is the tensile force of the stretched film in kg. The meaning of the stretched film tension and the displayed tension of the device are different. Therefore, different types and thicknesses of stretched films should be set differently. The device displays tension.

 

The principle of tension setting:

 

The hand feel can clearly feel the difference in tension. Under the premise that the substrate runs smoothly, the smaller the tension, the better, with a slight relaxation, and it is better to stretch the film without curling.

 

The tension has a great influence on the stretched film, especially the oven tension is very sensitive. Excessive oven tension can easily lead to tunnels and transfer of aluminum coating. The tension of the mask and base film should match, and the linear expansion coefficient of the stretched film should be as close as possible, otherwise the stretched film will be easily curled.

 

Use a blade to draw a cross on the stretched film. It is better to make the four divided film angles flat or slightly curved. The stretched film will roll to the layer with excessive tension, and the tension of the corresponding substrate can be adjusted accordingly.

 

Tension and substrate linear expansion coefficient：

 

The dimensional change rate of the base material per unit length under the action of external force is called the coefficient of linear expansion, that is, the shrinkage rate. For elastic materials, such as plastic film, the size will increase when the external force is stretched. When the external force is released, the size will increase. It will retract, and if there is a temperature effect at the same time, the degree of retraction will increase.

 

In the elastic range, the degree of stretching or retraction is proportional to the stretching force. When the yield strength range is exceeded, the size of the substrate no longer rebounds. At this time, it is really stretched. Different materials have different linear expansion coefficients. .

 

The principle of matching tension is to control the amount of stretching of the substrate to be small, and to make the size of the face mask and the bottom film consistent after shrinking.

 

Stretching and shrinking of double-layer film:

 

The two-layer substrates are each stretched to a certain degree under tension and temperature conditions and then compounded together. After compounding, they tend to return to the original size state. The stretched film per unit length, the original size of the two layers of the material They are not necessarily the same, so the composite or the beams are not necessarily the same, and the initial bond strength of the adhesive also affects their respective shrinking capabilities, which results in different appearances.

Therefore, the key to tension matching is to make the original size of the stretched film consistent before stretching and a small amount of stretch.