In the event of a print quality problem or when the printing standard cannot be met, ink is the scapegoat for the scapegoat. In order to obtain a good print quality, you need to understand the characteristics and application skills of the ink itself:
※ Viscosity: Before a few days before planning to start a printing task (especially before major and complex printing tasks are performed), the ink brewing staff needs to bear the printing tasks to be undertaken (printing process, full-filled color blocks, overprint combination, etc.) And the structure of the anilox roller and the printing speed to be set are fully understood. Only in this way can the ink viscosity be adjusted according to the printing needs.
※ PH value: In addition to focusing on ink viscosity and related information above, ink brewing personnel also need to determine the correct ink PH value to obtain the best printing effect. It is worth noting that the pH of water-based inks will gradually decrease, especially during printing or long-term exposure to the air (without capping the ink cartridge). Therefore, when the ink is not used, close the lid of the ink cartridge. Once the pH is lowered, the ink viscosity increases. Only when the pH value is adjusted back to the standard state (8.2 ~ 9.0), the viscosity of the ink can be restored to the normal state. Changes in viscosity during the printing process can not only lead to changes in printing color, but also can lead to other problems, such as dirty printing, outer edge phenomenon, reduced color wear resistance, and so on. Therefore, it is very useful to install the printing linkage unit for automatic ink viscosity or pH adjustment device designed for high-end users.
※ Color: Everyone hopes that the color of printed products will meet the regulations. In addition, there are some notes:
â– The same quality of printing material/paper must be used for actual printing and proof printing
â– The same printing equipment must be used for actual printing and proof printing with the same printing speed, parameter settings, printing plates, anilox rolls and other parts.
â– Printed colors and standard printing colors must be compared under the same lighting conditions.
According to the report of the International Laboratory and Quality Control (QC) report, the color assessment also includes the comparison of the color viscosities of the two printing results. That is, if the viscosity of the two printing results is different, even if it falls within the allowable error range of the colorimeter, It is not possible to obtain the "QC PASSED" label.
In order to keep the ink in good condition after use, in order to ensure that the ink is still stable after a few days of use, there are some minor details to be aware of:
※ Never add water to the ink to dilute the color density of the ink, especially when working under high-temperature long orders. Please use the designated diluent recommended by the ink supplier.
※ Advise the operator not to bring too much moisture (including water from the cleaning drum) into the ink cartridge each time the printing is completed.
※ Before reloading the ink into the ink cylinder, it is necessary to go through the international quality control (QC) and quality assurance (QA) system to re-determine and adjust the ink index. This includes re-adjusting the ink viscosity, pH and color back to the original standard.
print
Before using printing, there are several parameters that require special attention:
※ Hardness: It is necessary to carefully select the appropriate printing plate for different printing job requirements. Fine print designs include dots, small letters, bar code printing, and require higher hardness plates, such as 550 shore A; cardboard printing requires slightly lower hardness of the plates, which is approximately between 360 and 38 0 shore A.
※ Adhesiveness: Printing plates with too high adhesiveness are likely to be stained with “dirty stains†because the dust or other dirt on the printed material is likely to adhere to the plate, and in the long run it will lead to printing. The ink capacity is reduced, and the printing color density is reduced.
※ Surface Tension: Checking the surface tension is particularly important for photosensitive resin plates because some operations during the production of such plates, such as cleaning and disassembly, may cause changes in the surface tension on the plate product.
※ Cleaning: Whether it is a rubber plate or a photosensitive resin plate, it needs to be thoroughly cleaned. Dry ink agglomerates and paper dust adhered to the plate should be removed after each use. If it is not cleaned, the printing quality will be reduced, the ink transfer ability will be weakened, and the service life of the printing equipment will be shortened.
Finally, the plates should be subjected to regular hardness tests, especially after printing 200,000 sheets. Once the hardness of the plate has been significantly increased or decreased, a new plate needs to be replaced.
Mesh roller
The requirements for the roll include
※ Usually the anilox roller is mounted on a single printing unit. And usually anilox rollers with many cells (>400) can be used for fine printing (small characters); single printing units with anilox rollers with fewer number of cells (>400) are suitable for printing cardboard; The printing unit <4-color printing machine> is used for ordinary printing <number of cells: 200 ~ 300>.
※ If the printing company has the latest generation of press equipment that can be quickly and more aniloxed, it is possible to print both long and short orders. Therefore, an anilox roller with 160 to 550 cells is sufficient to meet the printing requirements for corrugated board production. The anilox roller with 440 ~ 1260 cells is suitable for narrow film printing.
Of course, in order to obtain good print quality, it is not enough to rely on the correct and effective use of the above three elements. The factors that affect print quality also include the characteristics of printed materials and the use of other equipment.
In the event of poor quality prints or products that do not meet the printing standards, the printed material (paper, film, or foil) is usually better than ink, because most people blame the ink. Why does ink always act as a scapegoat? The main reason is that the characteristics of the printed material are not easily observed by the naked eye, and are not as obvious as the ink (such as the amount of blisters, the concentration of the ink, or whether or not the ink is fluent, etc.). When observing the printed material, only one point is easily observed, namely the color and gloss of the paper. However, in fact, many cardboard properties can be detected by the quality control system (QC) before the board is used for printing. Some of the special points to note include:
※ Cardboard Material Composition (Cardboard Fiber Distribution Characteristics / Cardboard Smoothness)
※ Air permeability (absorbent, usually measured by COBB SIZE / FELT)
※ Color and gloss ※ Thickness ※ Surface tension <The surface tension of the paperboard is too low to cause the water-based ink to be hard to color>
※ Cardboard cleanliness (the presence of dust on the cardboard surface will seriously affect the printing process)
In addition, porous prints may cause the ink to dry too quickly and easily clog the plate or anilox roll, even causing serious wear; printing on a too rough paper surface cannot achieve good print quality because the operator Obtaining normal printing results often requires greater pressure on the printed material; better printing effects can be obtained by printing on thicker objects (especially during color overprinting); dark paper is not easy To obtain a bright printing effect, in order to ensure the color overprint effect, it is best to use a good quality, thick, smooth white cardboard or ivory cardboard.
Other factors that affect print quality include:
※ The accuracy of print registration must be very accurate
※ A good printing device should be equipped with a duster before the first printing unit, because if there is dust on the cardboard, it will have a great impact on the printing process.
※ The cleaning of the printing equipment includes the cleaning of each part of the anilox roller, the printing roller, the correction roller and the printed material. This is a prerequisite for better printing quality.
In short, in addition to mastering the characteristics of inks, plates, and anilox rolls, and using techniques, it is also necessary to combine the performance and application skills of other printing equipment and raw materials to ensure good print quality.
Ink