<p>
In addition to be used in household cooking, the industrial
aluminium foil is more frequently used in food packaging, the first stage of which involves printing. Then how to print it? And what are things worth attention?</p>
<p>
Surface Cleaning</p>
<p>
While being placed in the air, the <strong>industrial
aluminium foil </strong>would immediately reacts to the oxygen and a very thin layer of dense oxide would be formed on the surface in no time. If the oxide layer is not dirty, the ink has good adhesion. However, in actual production, the
aluminum foil paper is contaminated by lubricants and environmental dust, and a very thin film layer is formed to affect the adhesion properties of the ink. Therefore, a surface cleaning process is inevitable before printing
aluminum foil. This is known as a pre-press etching coating treatment, aimed to eliminate the dirt of the lubricant and enhance the adhesion between the ink and the foil surface. Also known as the bottom surface treatment, this is is to coat the surface of the
aluminum foil paper with a shellac coating or a nitrocellulose coating. After coating, the printing surface is no longer an
aluminium foil but a coating material. These coating materials have good affinity with the ink, thereby improving the adhesion of the ink to the foil surface.<br></p>
<p>
Pretreatment before printing</p>
<p>
Based on the information above, we can see that
aluminum foil for packaging is actually a composite material of aluminum and paint coating. In case of dramatic changes of the temperature and humidity of the further processing environment, it's difficult for the inner environment gets balanced with the outer environment, the double-layer structure connected by the inner coating or the adhesive will generate internal stress, which will not only cause shape changes but also form curls, wrinkles and waves because of the change of water content, which seriously affects the quality of printing and post-processing. Therefore, in order to ensure the normal printing of <strong>
aluminium foil</strong> for packaging, it is necessary to control the temperature and humidity of the printing workshop, so that the temperature of the workshop is maintained at (25 + 2) ° C, and the relative humidity is maintained at 50% to 60%.</p>
<p>
The temperature and humidity balance before printing processing is important. Otherwise static electricity will be generated, which will make foil feeding difficult. In actual production, the original packaging of <strong>industrial
aluminum foil </strong>should be placed in the workshop for at least 16 hours before being opened for cutting, and another 8-12 hours before printing. In addition, the printed product should be covered with a plastic film to prevent moisture and reduce deformation during processing.</p>