What are the specific steps involved in the production process of BOPP thermal sensitive synthetic paper?

The production process of BOPP thermal sensitive synthetic paper mainly includes the following steps:

1、 Raw material preparation and mixing

Selection of main raw materials: Mainly use polypropylene (PP) resin, especially isotactic polypropylene, whose content needs to reach a high standard (such as 95%~97%) to ensure the tensile strength and physical properties of the film.

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

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

Mixing evenly: Mix polypropylene resin, functional fillers, and various additives in a certain proportion. The mixing process requires strict control of the proportion of raw materials and mixing quality to ensure the performance of the final product.

2、 Plasticization and extrusion

Plasticization treatment: Send the mixed raw materials into an 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.

Melt extrusion: During the plasticization process, the raw materials are melted into a uniform melt through high temperature and high pressure in the extruder.

3、 Casting and stretching

Casting: The molten polypropylene is extruded into thick sheets through a die and rapidly cooled into regular thick sheets. The cooling process usually uses chilled rollers and a water tank, with a temperature controlled between 30~45 ℃.

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 to ensure the uniformity and tensile strength of the film.

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 to achieve bi-directional stretching of the film.

4、 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.

5、 Coating

Configure coating solution: Prepare the coating solution for the bottom coat, thermosensitive coloring layer, and top coat protective layer as needed.

Coating operation: Apply thermosensitive coating, base coating, protective layer, etc. on the surface of the film. The coating process requires strict control of the composition, concentration, and coating amount of the coating liquid to ensure the performance of the final product.

6、 Roll up and slitting

Roll up: Roll up 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.

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

7、 Timeliness processing and quality inspection

Aging treatment: The cut film is subjected to aging treatment. The aging treatment is generally completed within 24-48 hours to improve the physical properties and stability of the film.

Quality inspection: Conduct quality inspection on the aged film, including appearance quality, physical properties, printing effect, and other aspects. Ensure that the final product meets relevant standards and customer requirements.

In summary, the production process of BOPP thermal sensitive synthetic paper is a complex and delicate process that requires strict control of parameters and quality in each link to ensure the performance and quality of the final product.