Is the production process of BOPP thermal sensitive synthetic paper complicated?

Yes, the production process of BOPP (biaxially oriented polypropylene) thermosensitive synthetic paper is relatively complex, involving multiple steps and precise control. The following are the main process steps for producing BOPP thermal sensitive synthetic paper:

1. Raw material preparation and mixing:

Main raw materials: Polypropylene (PP) resin, especially isotactic polypropylene, is mainly used, and its content needs to reach a high standard (such as 95%~97%) to ensure the tensile strength and physical properties of the film.

Functional fillers: Add pigments, dyes, etc. as needed to give paper specific colors and functional properties.

Additives: including antioxidants, lubricants, fluorescent whitening agents, titanium dioxide, etc., to improve the processing performance of paper and the performance of the final product.

Mix these raw materials evenly in a certain proportion, and strictly control the proportion and mixing quality of the raw materials during the mixing process.

2. Plasticization and extrusion:

Send the mixed raw materials into the extruder for plasticization. The processing temperature of the extruder is generally around 250 ℃, and the specific temperature is adjusted according to the temperature resistance of the raw materials and the performance of the extruder.

During the plasticization process, the raw materials undergo high temperature and high pressure in the extruder, melting into a uniform melt.

3. Casting and cooling:

Squeeze the melted polypropylene melt through the die into thick sheets and rapidly cool them into regular thick sheets. The cooling process usually uses chilled rollers and a water tank, with a temperature controlled between 30~45 ℃.

4. Stretching treatment:

Longitudinal stretching: The casting sheet is subjected to longitudinal stretching treatment, with a stretching ratio generally between 4.5 and 5.5. During the stretching process, it is necessary to control the temperature of the preheating zone, stretching zone, and shaping zone.

Lateral stretching: The casting sheet is subjected to lateral stretching treatment, with a stretching ratio generally between 9 and 10. Horizontal stretching also requires controlling the temperature and stretching speed of the preheating zone, stretching zone, and shaping zone.

The biaxial stretching process rearranges the molecular chains of the film, forming a highly oriented structure, improving the transparency and glossiness of the film, enhancing its tensile strength, impact strength, and rigidity.

5. Surface treatment:

Perform corona treatment or other surface treatments on the stretched film as needed to improve the surface tension of the film and enhance the adhesion of the coating layer.

6. Coating treatment:

Coat the surface of the film with a thermosensitive coating, a base coating, and a protective layer. The coating process requires strict control of the composition, concentration, and coating amount of the coating liquid.

Thermal sensitive coatings are composed of water-based resins, thermosensitive agents, color developing agents, and sensitizers. By continuously optimizing the coating formula, the sensitivity, stability, and color vividness of thermal sensitive coatings can be improved.

Adopting advanced coating technologies such as wet coating, gravure coating, and reverse coating to ensure the quality and stability of the coating.

7. Rolling and slitting:

Roll the coated film into a uniform large roll. During the winding process, it is necessary to control the tension of the contact roller and pressure roller to maintain the flatness and tightness of the large film roll.

Cut the large film roll into appropriate sizes according to customer requirements. The slitting process requires strict control of slitting accuracy and edge quality.

8. Timeliness processing and quality inspection:

The sliced film is subjected to aging treatment, usually completed within 24-48 hours, to improve the physical properties and stability of the film.

Conduct quality inspection on the aged film, including appearance quality, physical properties, printing effect, etc., to ensure that the final product meets relevant standards and customer requirements.

In summary, the production process of BOPP thermal sensitive synthetic paper involves multiple fine steps and complex control processes. Each step requires strict control of process parameters and quality indicators to ensure the performance and quality of the final product.