Polyester resin (PET), appearance: transparent. Flammability: flammable, keep burning away from the flame. The near flame shrinks and burns, and it can continue to burn away from the flame. A few have smoke, with a small sweet taste, and the ashes are hard and round, black or light brown.
The difference between PET and PVC can be seen by the melting point. The melting point of PET is about 265~280℃, and that of PVC is 185~205℃.
The natural color of PVC film (polychloride) is yellowish translucent and shiny. Transparency is better than polyethylene and polystyrene, but worse than polystyrene. Depending on the amount of additives, it can be divided into soft and hard polyvinyl chloride. The soft products are flexible and tough, and the hand feels sticky. The hardness of hard products is higher than that of low-density polyethylene. , And lower than polypropylene, whitening will occur at the inflection. After the PVC particles are heated (below the melting point), their characteristics change little with temperature, and its molten state is suitable for extrusion, that is, it can be easily formed directly in the mold after the material is down.
Generally speaking, these two kinds of bottles will have seams, at least there is a mouth, which is left when the mold is closed, and the best mold will have a thin parting line.
1. When blowing mineral water and other normal temperature filling bottles, the mold needs to be cooled and the temperature is kept below 50 degrees, while for hot-filling bottles, the mold needs to be heated above 130 degrees;
2. The price difference is mainly due to the price difference of raw materials, which of course also has some relationship with the blow molding equipment and technology;
3. The mold-clamping line mainly affects the appearance, and should have little effect on performance
PET commonly used plastic blister material, soft, strong toughness, good plasticity, can be made into transparent and various colors, commonly used transparent PET packaging electronics, cosmetics, toys, gifts and other products. PET is hard, good toughness, high strength, bright surface, environmental protection, transparent and multi-color sheets. The disadvantage is that it is difficult to heat PET with high frequency, and this material is often replaced by PVC by users who require products and environmental protection. PS has low density (light weight), environmental protection, very good plasticity, poor toughness and brittleness, and cannot be made into transparent materials. Therefore, it can only be made into bottom bracket type blister. Because it is easy to crack, this type of blister is not suitable for recycling. PP material is very soft, good toughness, environmental protection, and high temperature resistance. It is often used as packaging for dining utensils or other high temperature resistant products; but its plasticity is poor, processing is difficult, surface gloss is poor, and the color becomes lighter during processing.
