PET Processing: Molding Technologies & Applications

As a thermoplastic polyester with excellent performance, polyethylene terephthalate (PET) has unique advantages in the field of processing. Its easy processing characteristics through injection molding and extrusion molding have brought rich application possibilities to many industries. ​

Injection molding is one of the important ways to process PET. This process can accurately produce plastic products with complex shapes and fine structures. During the injection molding process, PET particles are heated to a molten state in the barrel of the injection molding machine, and then injected into the mold cavity under high pressure. After cooling and shaping, the desired shape of the product can be obtained.

For example, in the field of electronic appliances, PET can be used to make various precision electronic component shells through injection molding. These shells not only have good mechanical strength and can effectively protect the internal components, but also have excellent insulation properties, ensuring the safe operation of electronic products. Moreover, the high efficiency and high precision of injection molding make large-scale production possible, meeting the market's large demand for electronic products. ​

Extrusion molding and thermoforming: Diverse production of packaging materials ​

Extrusion molding also occupies an important position in PET processing. It is usually used to produce films and sheets. During the extrusion process, the PET raw material is heated and plasticized in the extruder, and is pushed by the screw to continuously pass through a die of a specific shape, thereby forming a film or sheet with a certain cross-sectional shape. The produced PET film has high transparency, good flexibility and excellent barrier properties, and is widely used in the packaging industry, such as food packaging, pharmaceutical packaging, etc. 

Taking food packaging as an example, PET film can effectively block oxygen, water vapor and odor, extend the shelf life of food, and its high transparency can clearly show the appearance of food and attract consumers to buy. After the subsequent thermoforming process, PET sheets can be further processed into packaging boxes, trays, etc. of various shapes, providing diversified packaging solutions for products. Thermoforming utilizes the thermoplasticity of PET sheets. After heating and softening, it can be stretched and pressed into a mold to produce packaging containers with complex shapes that fit the product. It is widely used in the packaging of cosmetics, toys and other products. ​

Blow molding: large-scale production of transparent PET bottles

Blow molding is the main process for producing transparent PET bottles. During the blow molding process, the PET preform heated to an appropriate temperature is placed in the mold, compressed air is used to expand it and fit the inner wall of the mold, and after cooling, a transparent bottle with a specific shape is obtained. The PET bottles produced by this process have extremely high transparency, can clearly show the color and state of the liquid in the bottle, and have good mechanical properties. They can withstand certain pressure and impact, and are suitable for the packaging of liquid products such as beverages and cosmetics. Since blow molding can achieve automated large-scale production, high production efficiency and relatively low cost, PET bottles are very competitive in the market. ​

Pre-processing treatment: a key step to ensure product quality ​

However, in order to obtain high-quality PET products, pre-processing treatment is crucial. It is recommended to dry the PET raw material at 120°C for 2-4 hours before processing. This is because PET has a certain degree of water absorption. If there is too much water in the raw material, the water will be vaporized at high temperature during the processing, resulting in defects such as bubbles and silver wires in the product, which seriously affects the quality and performance of the product. Through drying, the moisture in the raw materials can be effectively removed to ensure the smooth processing and the quality of the products. ​

PET plays an important role in injection molding, extrusion, blow molding and other molding processes due to its easy processing characteristics. Through reasonable pre-processing and the use of recycled materials, high-quality products that meet the needs of different industries can be produced, promoting the development of various industries and contributing to environmental protection.

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