The Main Reasons For Deformation, Winding Slippage And Broken Film Rupture Of Plastic Film Products

In recent years, with the improvement of quality of life, more and more consumers have begun to pay attention to the safety and quality of food packaging. Therefore, in the packaging industry, the process of plastic film products is becoming more and more important. In addition to improper heating temperature, poor tension control and other reasons, there is also the quality of raw materials, in which the friction properties of raw materials can be characterized by their dynamic and static friction coefficients.

Friction and coefficient of friction：
When there is relative motion or relative motion tendency between two objects in contact with each other, the mechanical force generated on the contact surface that hinders the relative movement is friction. Static friction is the maximum resistance of the two contact surfaces at the beginning of relative movement, and the ratio of it to the normal force is the static friction coefficient; Dynamic friction is the resistance of two contact surfaces when a certain speed is moving relative to each other, and the ratio of it to the normal force is the dynamic friction coefficient.

The impact it has：
1. Influence on bag making: The friction coefficient has an important impact on the opening of the packaging bag, the adaptability of the roll film to automatic packaging, and the operability of the bag making process of the packaging factory.
The friction force in the packaging process is often both drag force and resistance, so its size should be controlled within the appropriate range. The same bag making machine produces back seal bags, the material is OPP18//PE25, when the dynamic friction coefficient of the hot cover is 0.34, the resistance of bag making is too large, and the phenomenon of different bag lengths occurs. The material is OPA15//1C7A20//milky white PE65, and when the dynamic friction coefficient of the hot cover is 0.18, the resistance of bag making is too small, and the phenomenon of different bag lengths also occurs.

2. Impact on automatic packaging
Rolls for automatic packaging generally require a small coefficient of friction of the inner layer and a suitable coefficient of friction of the outer layer. If the friction coefficient of the outer layer is too large, it will cause excessive resistance during the packaging process and cause tensile deformation of the material; If it is too small, it may cause the drag mechanism to slip, resulting in inaccurate eye tracking and cut-off positioning. However, the friction coefficient of the inner layer is sometimes not too small, and some packaging machines have too little friction coefficient in the inner layer, which will cause the material to be unstable and misaligned when forming the bag.

3. The effect on the production of composite film
For composite films for strip packaging, the friction coefficient of the inner layer is too small, which may also cause the unloaded tablet or capsule to slip, resulting in inaccurate positioning of the blank. The friction coefficient of the inner layer of the composite film mainly depends on the content of the opening agent and slippery agent of the inner layer material and the thickness and stiffness of the film. Corona treatment, curing temperature and time during the production process also affect the coefficient of friction of the product.

4. Impact on the production of stretch film
In the production process of BOPA film and plastic packaging bags, the friction coefficient of plastic film is an important technical index. On the one hand, it has become a quantitative evaluation index of plastic film openness together with the anti-blocking performance of the film, and on the other hand, it can be used as one of the reference data for the running speed, tension adjustment and wear of the film during the operation of the automatic packaging machine.

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