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BOPET (biaxially stretched polyester film) is a chemical raw material widely used in packaging, electronics, electrical, medical and other fields. The manufacturing method mainly involves the preparation of polyester resin, extrusion of thin films, biaxial stretching and other processes. This article will provide a detailed introduction to the manufacturing method of BOPET

1、 Preparation of polyester resin 

1 Ingredients: Add purified terephthalic acid (PTA) and ethylene glycol (EG) in a certain molar ratio to the ingredient tank, and add an appropriate amount of catalyst, stabilizer, and other additives

2. Esterification reaction: Under high temperature and pressure conditions, PTA and EG undergo esterification reaction to produce oligomers

3. Condensation reaction: Oligomers undergo condensation reaction under vacuum conditions to produce high molecular weight polyester resin

2、 Extrusion of thin film 

1 Melt extrusion: Polyester resin is added to the extruder, heated and melted, and then extruded into flakes through the die head

2. Cooling and shaping: The extruded sheet-like resin is rapidly cooled through a cooling device to form a preliminary thin film

3、 Biaxial stretching 

1 Longitudinal stretching: The initially cooled film is stretched longitudinally through a set of rollers to increase its length

2. Horizontal stretching: The film that has been longitudinally stretched is fed into a horizontal stretching machine and stretched horizontally through pneumatic or mechanical means to increase its width

4、 Heat setting and winding 

1 Heat setting: The biaxially stretched film enters the heat setting zone and is heated at high temperature to rearrange the molecular chains, improving the thermal stability and mechanical properties of the film

2. Roll up: The heat formed film is rolled up into a roll by the roll up device, completing the manufacturing process of BOPET film

The above is the basic manufacturing method of BOPET film, and the specific production process also needs to adjust the process parameters according to product requirements to ensure product quality. Meanwhile, the waste and exhaust gases generated during the production process also need to be treated to ensure environmental protection requirements

In summary, the manufacturing method of BOPET film involves multiple process steps, and it is necessary to strictly control the process parameters of each step to ensure product quality and production efficiency. With the continuous progress of technology, the manufacturing technology of BOPET films is also constantly improving, providing more possibilities for applications in various fields.