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Why Stretch Film Should Be Stretching Before Use?

In our life, we often see the packaging effect of stretching film. The packaging of stretch film is very tight and strict, which is enough to show the good quality of the product. So do you know why stretch film is so effective in packaging? In fact, before we use stretch film for packaging, we must go through a stretching operation. Many users do not understand why this is necessary, they think stretch film itself is very good stretching performance, do not need to do anything more, it is a stretch. This thinking is wrong.

Let'S Come Together To Give You A Correction, The Specifics of Stretching Film are As Follows.

1、Stretch film packaging must be stretching.

  1. When using mechanical equipment to package stretching is divided into direct stretch and pre-stretch. Pre-stretching is divided into roll stretching and electric stretch. The best stretch in the original length of 60% or less, its stretching ability is still very strong on the contrary, if more than half of the width of the stretch film decreases, this time the stretch film is very easy to break the phenomenon.
  2. Pallet mechanical packaging stretched forms include direct stretched and pre-stretched. There are two types of pre-stretched, one is roll pre-stretched and the other is electric stretched. Direct drawing is done between the pallet and the drawing film. This method has a low draw ratio (about 15% to 20%). If the stretch ratio exceeds 55% to 60%, which exceeds the original yield point of the stretch film, the width of the stretch film decreases, the perforation properties are lost, and the stretch film is prone to breakage. And at 60% stretching ratio, the stretch force is still very large, and for light goods, it is likely to make the goods deformed.

2、It is pre-stretched by two rollers

  1. Two rolls pre-stretch rolls are connected by gear mechanism. The drawing ratio can be different according to the gear ratio. The tensile force is generated by the turntable. Since the stretch is generated in a short distance and the friction between the rolls and the stretched film is large, the width of the stretched film does not shrink and the original puncture performance of the stretched film is maintained. In the actual winding, there is no stretch, which reduces the breakage caused by sharp edges. This pre-stretch can increase the stretch ratio to 110%.
  2. Two-roller stretch is driven by gears, and the stretch ratio is changed by the change of gear ratio. The reason why the width of the stretched film does not change after stretching is that the length of the stretch is produced in a short distance and the friction between the rolls and the gears does not change its width, so that the stretch is consistent with the indicators given before the stretch.

3、Stretch film is self-adhesive film

  1. Stretch film is a double-sided film containing self-adhesive properties, and such adhesion exists only between the film and the film, with high tensile strength, better self-adhesive properties and high transparency. 
  2. It is a single-sided or double-sided adhesive plastic film, which can stretch and wrap the packaged material very tightly, and the self-adhesive adhesive does not adhere to the surface of the packaged material, but only exists on the surface of the film and the film. It has high tensile strength, high elongation, good self-adhesiveness and high transparency. It is widely used in export, bottle making, paper making, hardware and electrical appliances, plastic, chemical, building materials, agricultural products, food and other industries.

To sum up, stretching the stretch film before the wrapper can not only improve the tensile properties, but also change its puncture resistance and viscosity.

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