Summary of temperature setting requirements for each stage of film blowing machine operation

Release time：

2019-04-16

Summary of temperature setting requirements for each stage of film blowing machine operation

Temperature control is a very important index during the operation of film blowing machine. This paper summarizes the temperature requirements of different stages of film blowing for reference.

According to the melt theory of plastic, the extruder screw of blown film is divided into three sections: feeding section, melting section and homogenizing section. At the end of the feeding section, at the beginning of the melting section, according to the melting theory, its temperature should be viscous flow temperature. The viscous flow temperature of various film blowing resins is PP: 164-175℃, PE: 105-135℃, PA: 195-210℃.

Feeding section temperature requirements
At the inlet of the feeding section, it is hoped that the temperature should be low to prevent the resin viscous flow from blocking the feed port. In addition, the resin in the feeding section is continuously compressed, and the air should be discharged from the feeding port upside down. According to the different structure of the equipment, the feeding port is not electrically heated, but the heat transfer through the barrel, the temperature of the feeding port is about 50-90 degrees. In this way, the feeding section temperature is determined. The inlet is 50-90 degrees, the end is equal to the melting point or viscous flow temperature, and the temperature isometric linear heating can be defined on this section.

Melting section temperature requirements
At the beginning of the melting stage, the temperature reaches the viscocurrent temperature to melt. For crystallizing resins, the viscocurrent temperature is equal to the melting point temperature. Then continuously compress and increase the melt layer, the temperature needs to be constantly increased, in order to make the resin molecular chain length is different, different thermal energy of polymer melt, so that after the establishment of the temperature at the end of the melt section, can be determined to be in the other parts of the section is linear heating.

Temperature requirements for homogenization section
In the homogenization section, mainly remelting homogenization and quantitative constant pressure constant temperature output melt, the temperature of this section can be kept constant, or the temperature at the end of the melt section can be slightly increased (about 2-5 degrees).

For blowing film, the temperature of the head section is required to be lower, but it can not be lower than the viscous flow temperature, which is easy to lift film and normal blowing film. The melt should have a certain viscosity when it comes out of the mold, so as not to break the film and collapse the film. In general, it is about 10-30 degrees lower than the end of the homogenization section, and the temperature from the homogenization section to the touch mouth can also be regarded as an isometric temperature drop.

Key points of extrusion temperature control
1, different kinds of resin, blowing film process temperature is different.
2, the same kind of resin, the model and melting index are different, the process temperature of blowing film is different, the index is large, the fluidity is good, the temperature is low.
3, the same kind of resin, blowing film of different thickness film, the process temperature is different, processing thick film, the process temperature can be higher.
4. The temperature of the touch mouth can also be a little higher, which is conducive to reducing viscosity and improving productivity.

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How to operate the film blower correctly? Details of operation precautions

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How to operate the film blower correctly? Details of operation precautions