When processing cartons by flexo printing, the general production speed is 300-1000 feet per minute. Although many flexo printing machineries can reach 2000 feet per minute, if you really produce at this speed, there will be many unexpected problems. Printing failure. The reason does not lie in the printing machine itself but is affected by various factors such as ink formulation and substrate surface treatment.
Ink Supply
The closed doctoring system can fully ensure that less ink surface area contacts the anilox roller. On a high-speed printing press, in order to maintain the effective ink supply of the ink system, it is necessary to have a good ink supply device. At the same time, the ink supply pump and the lateral feed position also need to be optimally adjusted.
Scraping and rub
The application of the double-edged ink system increases the friction between the doctor blade and the anilox roller. As the printing speed increases, the surface temperature of the anilox roller reaches as high as 1400 degrees Fahrenheit. Under the effect of high temperature, the ink in the cells of the anilox roller starts to dry, and when the solvent decreases instantly, the surface tension of the ink will increase, and the surface wettability of the ink will decrease. If water-based ink is used, the shape and volume of the cell will also affect the ink outflow ratio. Bordered cells such as rhomboids, hexagons, etc. Spherical cells that rely solely on surface tension dynamics can provide better ink flow.
Printing substrate
Another important issue in high-speed printing is the surface tightness of the printing substrate used. Generally, the higher the tightness, the better the ink’s hygroscopicity and fluidity, and the better the drying performance.
Ink moisture absorption
High-speed printing reduces the residence time of the ink before it reaches the drying device, so it is necessary to adjust the rheology of the ink to meet the high-speed printing conditions.
Dry
Although many drying equipments have strong drying capacity, with the increase of drying speed, it should be considered whether the residual solvent is within the requirements. In actual production, the drying temperature may be appropriately increased when necessary to match the drying speed of some inks (such as water-based inks).
Ink
The ink itself should be reprocessed to accommodate a printing speed of 1500 feet per minute. Its reprocessing includes: adding a strong mixed solvent; adjusting the pH value; or adding a more suitable surface humidity medium. The color strength of inks for high-speed printing should be appropriately increased, and thinner inks can obtain better printing effects, and the drying of printed products will also be well improved.
Foaming
Foaming is another phenomenon that often occurs in high-speed printing with water-based inks. In high-speed printing, the residual air in the ink cannot be released quickly, and as a result, micropores appear on the printed matter. In order to effectively solve this problem, a defoamer is usually added to the ink system.
