Printing Process and Features of Packaging Aluminum Foil

The brief process flow of aluminum foil is: aluminum foil unwinding → gravure printing → drying → coating protective layer → drying → coating adhesive layer → drying → aluminum foil winding. 
During the entire production process, the surface quality of the gravure printing text pattern and the heat seal strength to be achieved by the adhesive layer, the adhesion of the protective layer and the drying temperature and the speed and tension control of the coating machine operation are the process operations. Therefore, in the "Aluminum Foil for Pharmaceutical Packaging" national standard, there are clear requirements for the surface quality of printed aluminum foil for medicinal use, and there are physical and chemical indicators for the performance of the protective layer and the adhesive layer, so as to protect the medicinal PTP aluminum foil with good barrier properties. To achieve the above-mentioned requirements in the PTP aluminum foil printing and coating production process, it is still necessary to be familiar with the applied raw material properties, and the following issues should be noted in the operation process:
1. Master the characteristics of aluminum foil and printing ink
The raw material for the production of PTP aluminum foil is industrial pure aluminum foil. The general requirement is that the thickness is 0.02mm, the tensile strength is 98kPa, the rupture strength is 90kPa, the surface is clean, smooth, no wrinkles, no indentation damage, no fluorescent material, The surface wetting tension is not less than 32. The requirement for the pinhole degree of medicinal aluminum foil is that the pinholes with a diameter of 0.1-0.3 mm are not more than 1/m2. 
2. The amount of solvent added to the ink should be appropriate
When gravure printing is used to print aluminum foil products, the ink concentration is too low, which will cause the printed text patterns to be not bright and the web patterns will be stenciled; if the ink concentration is too high, cracks will occur at the map, which will not only waste ink, but also Can easily cause the printing surface to be uneven and not beautiful. In addition, better inks should be selected based on the speed of the aluminum foil coater and the ink hole depth of the gravure roll.
3. Adhesives should meet requirements
4. Drying temperature and time should be mastered during printing and coating
Due to the different thickness of aluminum foil material, physical and mechanical properties are all different, and the thermal expansion, contraction, and elongation of the material when running in the equipment are also somewhat different, so it should not stay too long at very high temperatures, otherwise aluminum foil It is also prone to wrinkling and surface discoloration. Drying temperature is generally 170-210 °C.
5. Analysis of Printing and Coating Speed, Coating Tension, Coating Thickness and Adhesion Quality
Different kinds of aluminum foil have different requirements for the thickness of the adhesive layer. Generally, the thickness of the coating should be controlled within 3.5-7.0mm. In the printing and coating of aluminum foil, the speed, temperature, and tension of the aluminum foil are related to each other and pinned each other. The quality of the aluminum foil is directly related to the quality of printing and coating of the aluminum foil.