CTP Application: Innovation and Challenge (II)

Next, we must determine the dots formed on the plate to be able to fully reflect the tone value. In practice, an effective method is to place the plate face down on a light table and observe it with a microscope.

Adjust the focal length of the microscope to the table of the light-transmissive table to ensure that the circular dots can be clearly observed. What is important here is that the outlets must be uniform and the outlets must be exactly the same. The lowest gradation value that meets the condition is the value that should be raised during image processing and during RIP.

Although accurate absolute values ​​cannot be obtained with a plate measuring instrument (eg Vipflex), it has proved to be very useful and can be used as an internal control to ensure the consistency of the plate quality. The halftone scale should be proofed to find the smallest gradation value. If possible, a ruler should be placed at the edge of the plate. Observe the condition of the step scale during the printing process. Many useful information can be obtained and the quality can be easily controlled. All results should be archived and saved.

Because the number of screens is different, the size of the network points is not the same. Therefore, the calibration of high-light area network points must be tested for various different screen lines.

To ensure the consistency of quality, it is also necessary to know this: the gradation transformation curves required for different plates are also different, and the laser's performance index has to be changed accordingly. These feature gradations should be corrected on the basis of proofs of the printing plate test, and should be carried out as far as possible under exactly the same conditions as the final printing process, that is to say, inks, printing plates, anilox rollers, etc. All should match with the printing parameter to the maximum extent.

If the laser setup and highlight correction are considered part of the plate making process, and laser and highlight test calibrations are performed on different batches of plates, and periodic inspections are performed, the laser as an output device can also be considered as An image-setter is just a matter of a higher quality than an imager.

Even if the plate cylinder does not change, deformation due to the difference in the laser cylinder should always be taken into consideration in the plate making.

Another important factor is the thickness of the plate. In the case of allowing very light and light printing pressure, the greater the thickness error of the plate, the less the plate can fully reflect the advantages of the digital platemaking process. Therefore, it is important that the plate thickness error be as small as possible. The small thickness error of the printing plate not only requires that the thickness error of the original material be small, but also that a small thickness error must be ensured during the plate making process, especially during the rinsing and drying process. If the depth of relief is too large, it may affect the stability of halftones. In the drying process, the temperature in the drying oven must be kept as constant as possible to avoid fluctuations. It is more important to ensure good air flow conditions. There should be no blind spots in the drying drawer. In addition, the drying time must be Full enough.

The new digiflex II plate from BASF Drucksysteme GmbH has a very narrow thickness tolerance range, and it can fully meet these important requirements with its associated platemaking equipment (eg Combi F1 super, Combi FIII and F1IV). In the Combi FIII washing tank, the flushing speed can reach up to 280 mm/min (ACE 114 plate material), which reduces the etching effect of the solvent on the plate material. Therefore, the “swelling” effect of the plate during the flushing process also occurs. Correspondingly reduced. The perfect combination of plate and platemaking equipment guarantees a very small thickness error range and lays the foundation for the continuous and smooth tone adjustment, even on images of 1.60 mm (63 in.) plates. Get high quality.

Table nyloflex ACE Plate Features and Benefits

Features Benefits

During the exposure process, the color will change. The image of the exposed part is obvious. Immediate exposure can identify that the exposure latitude is relatively large. The fine halftone dots have a short developing time and save time. Moreover, the “swollen/swelling” degree is small and the ink transfer performance is good. In the case of water-based inks and solvent-based inks, the ink hiding power is good, the density is uniform, and the required printing pressure is small, so the tone is smoother, the hardness is high, and the elasticity is good. A fine halftone can be obtained. image.

High wear resistance, high resistance to print force

Anti-ozone performance will not crack

Thickness error of plate becomes smaller and smaller

1, in the entire printing width, to ensure the consistency of the print

2, the required printing pressure is small

Second, the base

The higher the number of screens and the thinner the printing plate, the more important it is to use the plate correctly. When the number of screens is 60 lines/cm (150 lpi), only 1% dots can be obtained on thin plates, and the relief depth is limited to 0.7 to 0.9 mm (or 0.028 to 0.035 inches). This requires that the base must have a certain degree of flexibility, and it can produce a high degree of resiliency. If the thickness error of the printing plate is very small, even if the quality of the sleeve is poor, rough, or the thickness of the sleeve wall is greatly different, it does not matter much. Of course, it is better to use a higher quality sleeve, and it is absolutely necessary. Since the digital imaging sleeve technology is still in its early stages of development, it is recommended that in order to ensure a high level of registration accuracy, it is advisable that you check and analyze together with the sleeve manufacturer in actual production.

In addition, the small thickness error of the plate also shows the tape manufacturer, otherwise, there may be printed stripes in the area of ​​the cable.

Third, the anilox roller

Even if the above parameters are strictly observed and the edition is very serious, there is still no guarantee that excellent, high-quality printed matter can be obtained. In printing, high-line anilox rolls must be used. Otherwise, high-quality prints cannot be guaranteed. Digitally produced printing plates (54~60 lines/cm, 137~152 lpi plus screen lines) must use high-line number (60° angle engraving, ink transfer volume is very low) to transfer ink from anilox rollers. . The ratio of the number of screen lines to the number of screen printing screens should be at least 5:1. The amount of ink to be transferred (typically 2.5 to 5.0 g/m2) depends on the type of ink, the type of substrate, and the type of the enclosed squeegee system. It is recommended that Anilox manufacturer consultation.

Fourth, the conclusion

Friends who want to print using digital plates should devote more energy to platemaking and printing. High-quality, consistent prints can only be obtained with specific parameters and using appropriate plates/plates. Otherwise, full of hope may fail. CTP is a new challenge. It is necessary to understand the materials and acquire the relevant knowledge. This is the key to success.

Source: Bison