The temperature of the small film blower determines the quality of the product. How to control the temperature of the small film blower reasonably, follow the small braid to see.
According to the melting theory of plastics, the extruder screw of small film blower is divided into three sections: feeding section, melting section and homogenizing section. According to the melting theory, the temperature at the end of the feeding section should be the viscous flow temperature at the beginning of the melting section. The viscous flow temperatures of various blowing resins are PP:164-175 degrees Celsius, PE:105-135 degrees Celsius and PA:195-210 degrees Celsius respectively.
At the feeding section entrance, the temperature is expected to be lower to prevent the resin viscous flow from blocking the feeding port. In addition, the resin in the feeding section is constantly compressed and the air is discharged from the feeding port upside down. According to the different structure of the equipment, although the feeding port does not carry out electric heating, but through the barrel heat transfer, feeding port temperature is about 50-90 degrees. In this way, the temperature of the charging section is fixed. The entrance is 50-90 degrees, the end is equal to the melting point or viscous flow temperature, in this section can be set as temperature equivalence linear heating. At the beginning of the melting stage, the temperature reaches the viscous flow temperature before melting. For crystalline resin, the viscous flow temperature is equal to the melting point temperature. And then continuously compress and increase the melting layer, the temperature needs to be constantly improved, in order to make the resin chain length varies, different thermal energy of the polymer melts successively, so to the end of the melting section of the temperature established, can be defined as the other parts of the section is linear heating. In the homogenization section, the main melt is remelting homogenization and quantitative constant pressure constant temperature output, which can maintain a constant temperature, or the end of the melting section temperature slightly increased (about 2-5 degrees).
For blown film, the temperature through the touch section is lower, but it can not be lower than the viscous flow temperature, easy to lift film and normal blown film. When the melt comes out of the die, it must have a certain viscosity, not break the film, collapse film and so on. Generally speaking, it is about 10-30 degrees lower than the end of the homogenizing section, and the temperature from the homogenizing section to the mouth can also be regarded as an isothermal drop.
If you control the temperature of each section of the film blowing machine, the probability of making a good film has reached 17%, so temperature control is very important, I hope you can master these things.
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