PET one-step blow molding machine raw material characteristics

Update: 2022/10/24
Abstract:

The PET bottle blowing machine is mainly used for blowi […]

The PET bottle blowing machine is mainly used for blowing PET plastic materials. It is completed by a series of actions such as feeding, heating, conveying, stretching, and clamping. The blow molding process of the one-step PET bottle blowing machine is a two-way stretch. In this process, the PET chains are bidirectionally extended, oriented and aligned, thereby increasing the mechanical properties of the bottle wall, improving tensile, tensile, and impact strength, and having excellent air tightness. Although stretching helps to increase strength, it should not be overstretched, and the stretch-to-blow ratio should be controlled. Blowing is carried out between the glass transition temperature and the crystallization temperature, usually controlled between 90 and 120 degrees. In this range, PET exhibits a high elastic state, and it becomes a transparent bottle after being rapidly blown, cooled and shaped.

In the blow molding process, there are: stretching—one blow—second blow. The time of the three actions is very short, but they must be well coordinated, especially the first two steps determine the overall distribution of the material and the quality of the blowing. Therefore, it is necessary to adjust: stretching start timing, stretching speed, pre-blowing start and end timing, pre-blowing pressure, pre-blowing flow, etc. If possible, it is best to control the overall temperature distribution of the preform, and the internal The temperature gradient of the outer wall. In the process of rapid blow molding and cooling, induced stress occurs in the bottle wall. For inflatable beverage bottles, it can resist internal pressure and has advantages, but for PET bottle blowing machines, it is necessary to ensure that it is fully released above the glass transition temperature.

PET raw material features:
PET raw material is a milky white or light yellow, highly crystalline polymer with a smooth and shiny appearance. It has excellent physical machine performance in a wide temperature range, and the long-term use temperature can reach 120 °C. The electrical insulation is relatively good, and the motor can still work normally under high temperature and high frequency, but the corona resistance is poor, and the creep resistance, fatigue resistance, friction resistance and dimensional standardization are all good.

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