In the printing process of corrugated color boxes, the impact of ink penetration on the strength of corrugated cardboard is a key concern. Ink penetration not only reduces the compressive strength of the cardboard but can also affect its overall structural stability, thus impacting the protective performance of the packaging. Therefore, this problem needs to be avoided through multifaceted process optimization during printing.
First, ink selection is crucial. Water-based inks are widely used in corrugated color box printing due to their environmental friendliness and good printability. However, water-based inks have strong penetrating power; if the formulation is inappropriate, they can easily penetrate into the corrugated cardboard fibers, leading to a decrease in strength. Therefore, fast-drying water-based inks should be selected. These inks dry quickly after printing, reducing their residence time on the cardboard surface and thus reducing the risk of penetration. Simultaneously, the ink viscosity must be strictly controlled. Too low a viscosity will result in excessive ink flow, increasing the probability of penetration; too high a viscosity may affect the printing effect. By adjusting the ink formulation, the negative impact on cardboard strength can be minimized while ensuring printing quality.
Second, controlling the printing pressure is essential to avoiding ink penetration. Corrugated cardboard is composed of a face paper, a corrugated core paper, and a liner paper. Its structural characteristics dictate that printing pressure must be moderate. Excessive pressure will not only crush the corrugated structure and reduce its compressive strength but also force ink to penetrate deeper into the cardboard, exacerbating ink penetration. Therefore, light pressure printing should be used to ensure that the ink adheres only to the surface of the cardboard and does not penetrate into the fiber layers. Flexographic printing, due to its good elasticity and light pressure, is very suitable for printing corrugated color boxes, effectively protecting the corrugated structure and reducing ink penetration.
Furthermore, matching printing speed with drying speed is also crucial to avoiding ink penetration. Printing too quickly may result in ink not being fully dried before proceeding to the next process, increasing the ink's residence time on the cardboard surface and thus increasing the risk of penetration. Therefore, the printing speed must be adjusted according to the ink's drying characteristics to ensure rapid drying and curing after printing. Simultaneously, temperature and humidity control in the printing workshop is also essential; suitable environmental conditions promote rapid ink drying and reduce the possibility of penetration.
Pre-treatment of the corrugated cardboard before printing is equally important. Rough cardboard surfaces or excessive ink absorption will exacerbate ink penetration. Therefore, this problem can be mitigated by pre-coating with a primer or selecting cardboard with moderate ink absorption. Pre-coating forms a thin film on the cardboard surface, reducing direct contact between ink and cardboard fibers, thus lowering the risk of ink penetration. Simultaneously, selecting cardboard with stable quality and uniform ink absorption provides a foundation for optimizing the printing process.
During the printing process, the selection and use of anilox rollers also require attention. The line count and cell depth of the anilox roller directly affect the ink transfer volume. If the line count of the anilox roller is too low or the cell depth is too deep, it will result in excessive ink transfer, increasing the risk of ink penetration. Therefore, a suitable anilox roller should be selected according to printing requirements to ensure a moderate ink transfer volume, meeting printing effect requirements while avoiding ink excess leading to penetration problems.
Finally, the stacking and storage methods after printing also affect ink penetration. Newly printed corrugated color boxes, with ink not yet fully dried, may be stacked immediately if undried ink adheres to the surface of other boxes, causing contamination or penetration. Therefore, after printing, boxes should be distributed and stacked and packaged only after the ink has completely dried. Meanwhile, the storage environment should be kept dry and well-ventilated to avoid high temperature and high humidity conditions that could accelerate ink penetration.
