Anti-sticking Phenomenon I: The phenomenon of anti-sticking is primarily attributed to the temperature resistance of the ink resin itself and formulation issues. It occurs when printed materials are subjected to a certain pressure, and the temperature reaches or exceeds the temperature resistance limit of the ink resin. This can also happen when printed items are stacked too high in the warehouse, leading to anti-sticking and color fading, especially during the rainy season. Flexible packaging companies should enhance ventilation during transportation and in warehouses, avoiding elevated temperatures as much as possible. Additionally, suggestions for improvement can be forwarded to ink suppliers, who can make adjustments based on the printing equipment.
Anti-sticking Phenomenon II: This occurs after the printing is wound up. When proceeding to the second stage processes, such as lamination, bag making, or slitting, instances of anti-sticking may be observed, and such cases are generally more severe. Some mild cases can be addressed by cleaning after lamination.
Causes of Anti-sticking:
Excessive tension during winding.
Incomplete drying of the ink.
Impure solvents, especially ethyl acetate, ethanol, etc.
Inappropriate solvent ratios for the printing equipment's speed and drying temperature.
Instability in temperature control or mismatched intake and exhaust air in the drying equipment.
Design of the printing plate.
Placement of the printed products after printing.
Solution:
Adjust winding tension according to different printing materials and maintain relevant data records. The optimal tension when off the machine should be moderate to the touch. Avoid using winding pressure rollers for transparent inks.
Choose inks with better drying properties and communicate with ink suppliers regarding product structure and ink requirements. If there is excess printed film, use cold air for treatment.
Regularly check solvent purity, provide specific requirements to solvent suppliers, and ensure solvent storage and extraction are done in non-humid areas.
Pay attention to the solubility and volatility of solvents, ensuring compatibility with the resin type of the ink. Viscosity of the ink and the thickness of the ink layer also impact anti-sticking.
Verify the stability of drying temperatures in printing equipment, especially ensuring that intake and exhaust air volumes match.
Design the printing plate with consideration for avoiding excessive overprinting, and control the drying properties and viscosity of metallic inks.
Avoid horizontal stacking of printed products. Opt for hanging or vertical placement.
For packaging bags that exhibit color transfer on the surface after stacking or packaging, especially with purple or a few other colors, this phenomenon is usually related to the storage environment and the properties of the ink itself. The main reason is color penetration, meaning that when ink of this color is used for printing, color transfer may occur quickly under certain conditions. In these cases, flexible packaging companies should thoroughly understand the packaging form and requirements of the product, choose suitable inks for trial production, confirm compliance with product requirements, and then proceed with mass production to effectively reduce the occurrence of quality issues such as anti-sticking and minimize losses.