PET (polyethylene terephthalate) Blown bottles, such as bottles for daily use and bottles for beverages, have different characteristics due to different plastic properties. PET plastic particles are heated at different temperatures (less than the melting point). For example, PET particles will crystallize harder than 150 degrees, which is also the reason why PET bottles and mineral water bottles are not heat-resistant, and the farmers orchards can be heat-resistant. Due to the large changes in its characteristics, the blowing process will be very long, and the one-step method using particle-to-bottle is not easy to control (such as different particles, replacement of production bottles, etc.), and the production capacity is not too high. Therefore, PET blow molding is generally carried out after the plastic particles are injected into the preform, and then heated and then pulled to blow the bottle.
PVC film (polychlorine) is yellowish translucent and shiny. The transparency is better than that of polyethylene, polyphenylene, and polystyrene, and it is divided into soft and rigid polyvinyl chloride, and the soft product is soft and tough, and the hand feels sticky. The hardness of the hard product is higher than that of the low density polyethylene. However, below the polypropylene, whitening occurs at the inflection point. After the PVC particles are heated (below the melting point), their characteristics change little with the temperature, and its molten state is suitable for extrusion. That is, after a tumbling material comes down, it can be conveniently formed directly in the mold.
In general, these two kinds of bottles will have seams, at least the bottle mouth is, which is left when the mold is closed, and even the best mold will have a thin mold line.
1. Bottles, such as mineral water, are required to be cooled when the bottle is blown at room temperature, and the temperature is kept below 50 degrees. When the bottle is blown by hot filling, the mold needs to be heated above 130 degrees.
2. The price difference is mainly due to the difference in raw material prices. Of course, there are also some relationships with the blow molding equipment and process;
3 mold line is mainly to affect the appearance, the impact on performance should be small
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