When a printing plate is referred to as a printing plate, the difference between folded printing, label printing, flexible packaging, and corrugated printing must be recognized. In these printing productions above, in order to further improve the printability of inks and substrates, relatively thin printing plates are often used. In flexographic printing, the printing pressure is always higher than the kiss-print printing pressure. Therefore, the plate will inevitably occur - distortion, resulting in an increase in network points, and may lead to paste. In order to increase the screen resolution of the printing plate, reduce the dot enlargement, and increase the printing speed, the thin plate is often mounted on the elastic pad. It should be remembered that the thinner the printing plate is, the smaller the dot gain is. The softer the printing plate is, the higher the dot gain is, and the more severe the stencil is.
The higher the number of printing plate lines, the larger the dot gain. In order to obtain repeatable good printing results, some media were selected as standard media to ensure that the printability of the paper was improved.
Printing on coated paper When printing on flexible paper on coated paper, a nyloflex FHA or FARII type plate with a thickness of 1.14 mm is often used, and a sleeve with a foam coating is used, and fine mesh is also used. Roller and squeegee with ink hole. The elastic plate on the sleeve allows the actual site to undergo greater printing pressure, eliminating apertures, and on the other hand allows the halftone area to undergo less printing pressure, resulting in a clear circular dot when the ink is set in place. The amount of ink transferred by the roller can ensure that the solid part of the ink is full, as long as the FAH plate with a thickness of 1.14 mm is used (the configuration of the sleeve with foam coating, you can print solid and dot pattern. In each printing plate It is also easier to add a bar code to the field or halftone part.When printing on coated paper, the thickness of the plate is usually 1.14 mm.The hardness of FHA plate is Shore hardness (A grade, the same below) 56-58 The softer FARII plate has a hardness of 49-52 Shore A. Both of the above plates can be used to print images on coated paper.
Printing on non-coated paper without the sleeve has a surface roughness that greatly influences the printing effect. When printing on rough paper, use a 2.25 mm thick plate. The FARII254 plate is to be mounted on PE or PU double-sided elastic mounting tape. These mounting tapes are hard and soft. The harder the mounting tape, the better the printing effect. When printing on uncoated paper, harder mounting tapes are generally used. Plates with a thickness of 2.54 mm were equipped with a PU or PE mounting tape with a thickness of 0.50 mm or 0.55 mm. The plate with a thickness of 2.84 mm has a higher dot gain rate and its usage is gradually decreasing.
FAII, FARII, or FAH plates with a thickness of 1.70 mm can also be used when configuring the sleeve configuration sleeve. The configured sleeve should be a hard sleeve, and the following is a mounting tape with a thickness of 0.38 or 0.55 mm. The sleeve should be custom made according to the thickness of the mounting strip used. When printing on non-coated paper, it is better to use a softer plate material (such as nyloflex FARII or FA plate), because the soft plate material and overprinting effect are good, and the ink hiding power is strong. On small rollers, FAII plates are less rigid because they are less rigid.
Printing on corrugated board In order to significantly reduce the dot gain when printing on corrugated paper, the FAC 394 type plate was introduced with a thickness of 3.94 mm and was mounted on an elastic mat material called R/back. FAC 394 media is a kraft box printing plate. Relief relief height is generally 2-3 mm. Two different plates can be used depending on the weight of the board. The FAC 394 plate, which has a Shore hardness of 32-34, is normally used when printing on uncoated white paperboard and Kraft board B waves, eliminating the possible adverse effects due to surface roughness. However, when printing on white paperboard and kraft paperboard, Asian printers are increasingly inclined to use harder plates (such as the FAC 394S plate with a Shore hardness of 40-42). It is said that the increase in the size of this kind of plate material is small, the printing effect is clear, and it is easy to handle. To prevent crushing the corrugations, the printing pressure must be set carefully. When printed on coated and semi-coated white paperboard (E-break weight 180-220 g/m2), BASF nyloflex FAII type plates with a thickness of 2.84 mm 2.54 mm are being used more and more. . This plate has a Shore hardness of 44-46, a minimal dot gain, and a high halftone graphic print quality. A 4.05 mm thick elastomeric mat was used for plate mounting. These plates are usually mounted on a 1 mm thick tape and lined with PET to achieve the best compressible state of the plate material. Then the PET pad material is fixed on the R/bak material and then loaded on the roller. This is a form of loading that is often used in Asian printing.
Conclusion The printability of substrates is affected by many aspects of the characteristics of inks, plates, anilox rollers, printer configurations, and the substrates themselves. Only these links are just right. In order to get the best print quality. (Finish)