How to make the printing words more stronger and not easy to remove with the same ink ?

The surface of the laminated cardboard box is a smooth plastic film (such as BOPP/PET) with extremely low surface energy. Ordinary ink is difficult to firmly adhere to, and it is also prone to shrinkage, resulting in broken and blurry handwriting. To make the date clear and firm, the core is to "improve surface energy+match specialized ink/equipment". You can start from the following paths

Path 1: Optimize the existing ink coding (CIJ/TIJ) process

This is the lowest cost improvement method, and the key lies in ink selection and surface pretreatment.

·Replacing high adhesion specialized ink: Ordinary ink will inevitably fail on film coating. Be sure to switch to high adhesion fast drying solvent based ink or UV ink developed for low surface energy substrates. This type of ink contains special resin that can "grip" the smooth surface of the film. If the existing ink is easily peeled off during tape testing (after spraying for half an hour), it means that the ink must be replaced.

·Add corona pre-treatment: If the high adhesion ink is still not ideal (especially for stubborn film surfaces with silicone oil coatings), it is recommended to install a corona treatment device before the coding station. It can instantly increase the surface energy to above 38-45 dyn/cm, allowing ink to better wet and spread, which is a key solution to adhesion and clarity.

·Accurate tuning of printing parameters: · CIJ (continuous inkjet): It is recommended to control the printing distance within 10-12mm, not too close, to prevent the smooth surface from rebounding and causing "satellite dots" to contaminate the handwriting.

·TIJ (thermal foaming): The distance is controlled within 3-4mm, and the landing point is more precise.

·Line speed: If the edges of the handwriting are rough, reduce the production line speed appropriately to give the ink droplets more sufficient spreading and curing time.

·Reserved drying area: The coated surface does not absorb ink and dries slowly. After coding, it is necessary to reserve a non-contact drying area on the conveyor belt. The ink layer should be thoroughly dried before entering the subsequent packaging to prevent dirtying and blurring.

Path 2: Consider replacing identification technology (laser marking)

If the ink solution still cannot stably solve the problems of ink dropping and blurring, it can be considered to invest in laser equipment at once to theoretically eliminate the problem of adhesion.

·Recommendation: UV laser (cold laser): Traditional lasers (such as CO ₂) are prone to burning through or burning the film, causing the paper box to turn yellow. UV laser belongs to "cold processing" with minimal thermal impact. It can directly "cold engrave" fine and sharp dates on the surface of laminated color boxes without damaging the original printed patterns. It is permanently resistant to friction, waterproof and scratch, and cannot be removed by hand. The production date of Wang Laoji's genuine can bottom is clear and durable, using the principle of laser coding.

💎 Summary and Recommendations

It is recommended to investigate in the order of "ink change+corona discharge → parameter adjustment → final evaluation of laser". The clarity issue of laminated paper boxes can be solved by matching specialized high adhesion ink with corona treatment for over 90%. If the product is positioned as high-end and has extremely high requirements for aesthetics and permanence, ultraviolet laser will be a more permanent choice.

Are you currently using CIJ, TIJ, or other devices? If it's convenient, please let me know the specific phenomenon now (whether the handwriting is blurry and spreading, or just wiping it off), and I can help you further identify whether it's an ink problem or a parameter setting issue.