BOPP film (biaxially oriented polypropylene) is a plastic film widely used in the packaging, labeling and laminating industries. It has excellent properties such as transparency, smoothness, wear resistance, heat resistance and chemical corrosion resistance, so it is widely used in food packaging, pharmaceutical packaging, daily necessities packaging, printed labels, laminated materials and other fields.
8 key steps in the BOPP film production process
1.Raw material preparation
The raw material of BOPP film is polypropylene resin. Polypropylene resin is a thermoplastic with good melt flow and film-forming properties. The production of BOPP film requires the use of high-quality polypropylene resin to ensure the performance of the film.
2.Extrusion
Polypropylene resin has good fluidity in the molten state and can be extruded into a melt through an extruder. After the melt flows out through the die, it is cooled and solidified into flakes on the cooling roller.
3.Casting
After the sheet flows off the cooling roller, it is cast through a casting machine. Casting refers to stretching the sheet on a heated casting roller to make the thickness of the sheet uniform.
4.Bidirectional stretching
The cast sheets are biaxially stretched through a stretching machine. Biaxial stretching refers to stretching the sheet in two perpendicular directions to improve the strength, toughness and transparency of the sheet.
5.Surface treatment
Depending on the desired properties, the film may be treated with corona discharge or other methods to improve ink adhesion and printability.
This treatment modifies the surface energy of the film, making it more receptive to inks and coatings.
6.Coating
In some cases, the film may be coated with additional layers to enhance its functionality.
Common coatings include:
Primer: Improves adhesion of subsequent layers.
Anti-fog coating: Prevents condensation from forming on the film.
Barrier coatings: Enhance resistance to moisture, chemicals, and gases.
Heat-resistant coatings: Allow the film to withstand higher temperatures.
7.Slitting and rewinding
The film is slit into desired widths and rewound onto rolls for further processing.
This step prepares the film for various applications, such as packaging, printing, and laminating.
8.Quality control
The film is inspected for any defects, such as uneven thickness, tears, or surface imperfections.
Only films that meet the required quality standards are released for sale and distribution.
Additional factors influencing BOPP film production
Type of polypropylene: Different grades of polypropylene can be used to create BOPP film with varying properties.
Additives: Specific additives are added to the polypropylene to enhance the film’s performance and functionality.
Process parameters: Precise control of temperature, pressure, and other process parameters is crucial for achieving the desired film properties.
Environmental considerations: BOPP film production can be energy-intensive. However, manufacturers are increasingly adopting sustainable practices to minimize their environmental impact, such as using recycled materials and improving energy efficiency.
Overall, BOPP film production is a complex but efficient process that requires sophisticated equipment and technological expertise. The careful control of each step ensures that the final BOPP film meets the desired properties for various applications.