[Chinese Packaging Network News] In accordance with regulations, the cup mouth should not be printed within 15 mm from the cup body. The cup bottom should not be printed within 10 mm from the cup body. This is to prevent the ink from entering the mouth; it is also to prevent the ink from contaminating the inner wall of the cup when the cup is stacked. Moreover, paper cup printing requires high ink. The heat sealing properties required for continuous cup forming and the printability of the PE film surface require that ink components, residual solvent content, drying conditions and other factors must be compatible with the paper cup properties.
In general, paperboard printing uses a flexographic water-based ink. For aqueous inks, ink adhesion performance is critical. In order to avoid losses, a large number of tests are usually conducted before the official printing in order to select inks with better adhesion. In addition, paper cup prints must have good scratch resistance, gloss, semi-dullness, and matting properties. The components of the ink must comply with the Food Sanitation Law and the corresponding food packaging hygiene standards.
There is also a paper cup printing solvent. The ink solvent used should not be able to swell the PE film as much as possible, and the solvent cannot contain water in order to prevent curling of printed products. As far as possible, the ink containing a plasticized free carrier is used to prevent the ink film and the PE film from having different shrinkage rates due to temperature changes, resulting in curling of the printed product. The curled print will produce an angle after die-cutting into a fan-shaped piece, which will make it difficult to convey and make the roll forming process during cup making.