Production process of PET film

PET (polyethylene terephthalate) film is widely used in packaging, electronics, printing and construction due to its excellent mechanical properties, optical properties and chemical stability. This article will introduce the production process of PET film in detail, including raw material preparation, extrusion molding, calendering and stretching, coating and processing, as well as finished product packaging and quality inspection.

1. Raw material preparation

The main raw material of PET film is polyester resin, usually polyester chips or polyester pre-dried granules are used as raw materials. Before use, these raw materials need to be dried to remove moisture and ensure the quality of the product. The drying temperature is generally around 150-170℃, and the drying time is about 3.5-4 hours.

2. Extrusion molding

Extrusion molding is one of the key steps in the production of PET film. The dried polyester granules are added to the extruder, and after heating, melting, fusion and plasticization, the molten polyester material is extruded into a strip film. During the extrusion process, the temperature, speed, extrusion volume and stretching of the extruder need to be strictly controlled to obtain high-quality PET film.

3. Calendering and stretching

After extrusion, the PET film needs to be calendered and stretched to improve its physical and mechanical properties. During the calendering and stretching process, parameters such as operating temperature and speed need to be controlled to obtain the desired film properties. Biaxial stretching is currently the most commonly used method, which can significantly improve the tensile strength, barrier properties, optical properties, heat and cold resistance of the film.

4. Coating and processing

PET film also needs to be coated and processed during the production process. Common coating processes include silicon coating, PU coating, matte coating, etc. These coatings can give the film specific functions, such as anti-static, anti-ultraviolet, anti-fog, etc. Common processing processes include printing, laser cutting, lamination, etc., which can further enhance the application value of the film.

5. Finished product packaging and quality inspection

After the PET film is produced, it needs to be packaged and inspected. The finished product packaging is generally in the form of roll packaging or sheet packaging. The quality inspection mainly includes appearance inspection, physical property testing, chemical property testing, etc. Through strict quality inspection, it can be ensured that the quality and performance of the product meet customer requirements.

Conclusion

The production process of PET film is a complex process involving multiple links. Each link needs to be strictly controlled to ensure the quality and performance of the final product. With the continuous advancement of technology, the production process of PET film is also constantly improving. In the future, it is expected that more high-performance PET film products will be developed to meet the needs of different fields.