How to control the temperature in film blowing progress?  

According to the changing characteristics of the material, single screw of extruder can be divided into three segments, that is, the feeding section (solid conveying section), the melting section (compression section), and the homogenization section (metering section).

How to control the temperature in film blowing progress?  

At the end of the feeding section and the beginning of the melting section, according to the melting theory, the temperature should be viscous flow temperature. The viscosity temperature of various blowing film resin is PP: 164-175℃, PE: 105-135℃, PA: 195-210℃

Temperature requirements for feeding section: At the inlet of the feeding section, the temperature should be lower to prevent the resin viscous flow from blocking the feeding port.The temperature of the feeding port is about 120-165 degrees.The end of the feeding section is equal to the melting point or viscous flow temperature,this section can be defined as a linear temperature rise.

At the beginning of the melting section, the temperature reaches the viscosity temperature to melt, for crystalline resin, the viscosity temperature is equal to the melting point temperature,Then temperature continuous raising (approx. 150-200℃),to make the resin molecular chain in various length, different thermal activity energy of the polymer has been fused.

In the homogenization section, remelting homogenizes and quantifies the output melt at constant pressure and temperature. The temperature of this section can be kept constant or slightly higher than the temperature at the end of the melting section (2-5 ℃).

The head of extruder should be in lower temperature in order to lift film sasily and normal blowing film,and avoid broken film and film collapse phenomenon.Generally speaking, it is about 10-30℃ lower than the end of the homogenized segment. The temperature from the homogenization section to the die lip can also be regarded as the isometric temperature drop.

Tips:

1. Different kinds of resin,temperature of blowing film process is different; 

2. The same resin in different types and melting indices,temperature of blowing film process is different,if melting index is large, fluidity is good, temperature is low.
3.The same resin, blowing film in different thickness ,temperature of blowing film process is different, the film is shicker,the temperature should be higher.

4. The temperature of the die lip can also be a little lower, which is conducive to reducing viscosity and improving productivity.

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