Application of thin plate technology in corrugated board printing (2)

Applications of Thin-plate Technology for the Corrugated Market in the Field of Platemaking and Printing In general, thin plates with hardness between 32 and 34 Shore hardness can basically meet the requirements of corrugated board printing. This plate is designed for color halftone printing, line and field printing (suitable for various substrates). After the main exposure, there is a clear color difference between the exposed portion and the unexposed portion of the printing plate, and the contrast is relatively strong. In this way, the quality of the raised portion (text portion) on the printing plate can be easily controlled. This new type of photopolymer plate also has other advantages. For example, the printability is very good, even on very rough, uneven bags, cardboard or other substrates can get a good printing effect; Independent points print accurately, single points are not lost; small texts and UPC barcodes are very clear and accurate. The gradation reproduction range is very wide, and if the plate is made under standard conditions, the tone reproduction range can be optimized very conveniently. All in all, the exposure latitude of this new photopolymer plate is very large. From F-flute and E-flute up to N-flute and G-flute, the requirements for color, hiding power, contrast, etc. are becoming increasingly stringent. The printer began accepting and adopting thin technology. The technical differences between corrugated board printing and folding carton printing are becoming more and more blurred and less obvious. Choosing the right plate material The manufacturer has made great improvements in the performance of the plate, the dot gain rate has been reduced, the ink transfer performance has been improved, and the negative effects of the plate (wash development) have been reduced, and The contrast of halftone printing is also improved. When printing fine halftone images or lines, the consistency of the printed matter must be guaranteed. In this case, a new thin flexible plate or other thin hard standard plate is recommended. Under the effect of pressure, the plate must have high elasticity and have a strong resistance to deformation. Elastic compressible sticker material is a good choice. When a thin plate is used for printing, a large amount of printing pressure is absorbed by the foam pad, so that the printed dot is very clean and the edge contour is also very clear. This requires a correspondingly suitable pressure depending on the type of corrugated board to be printed, that is, the pressure applied between the thinner and harder plates and the softer plate is different. Based on the reduction in the diameter of the cylinder and the type of corrugated board, the best plate-pad combination was determined through testing. The plate-making time required for the thin plate material is relatively short, and the deformation amount of the film and the plate is also relatively small. The embossed depth of the thin plate must not be less than 0.039 inches, because if the depth of the relief is too small, a large printing pressure must be used. However, a large printing pressure may result in the paste of small intaglio (or negative lines). Therefore, when printing thin corrugated board, it is advisable to keep the relief height of the plate between 0.039 and 0.042 inches. In order to meet some special requirements for heavy-duty bag printing (for example, printing on film or paper), or printing on rough-surfaced substrates, another hardness between 42 and 44 Shore hardness can be used. Thicker plates may have good results. Table 1 lists some of the commonly used plates with different thickness and hardness. Practice has proved that thin plate technology is very suitable for the printing of corrugated cardboard, whether it is ordinary platemaking or digital plate making. Table 1 Application and Selection of Commonly Used Plates Thickness (inches) Hardness (Shore Hardness) Plain Plate Corrugated Cardboard 0.185~0.276 32~34 Thick Plated Corrugated Cardboard 0.155, 0.170, and 0.185 32~34 Heavy-duty bags and corrugated board 0.155, 0.185 and 0.195 42-44 thin plates are suitable for all above-mentioned products 0.112 and 0.125 38~39 Anilox roll selection The role of the anilox roll is to ink the printing plate, must choose the appropriate net The roller can not only ensure that the small dots are not lost, but also can ensure that the transfer rate of the ink from the printing plate to the substrate is relatively high, and the color intensity of the ink is also relatively high. Corresponding anilox rollers are listed below for different quality grade corrugated board printing requirements: 1. B-flute, coated paper: 356 lines/inch anilox roller, the theoretical ink transfer volume is 4.20~4.52 BCM (6.5~7.0cm3/m2), the overall printing effect of halftone, text and lines are good. 2. B-flute, non-coated paper: The amount of ink transferred is largely influenced by the thickness of the web and the liner material used with it. It is recommended to use an anilox roller of 305 threads per inch. The theoretical ink transfer amount is 5.81 to 6.13 BCM (9.0 to 9.5 cm3/m2). 3, E-flute, coated paper: For this printing material, the different types of plates, the resulting results are very different. It is mainly influenced by the type of plate material, such as the hardness of the plate, the matching of the gasket, etc. These are all very important and have a direct impact on the final result. Therefore, here we can only provide you with a rough, rough recommended value, you can use anilox roller between 356 ~ 405 lines / inch, transfer ink volume in the 3.23 ~ 4.52BCM (5.0 ~ 7.0cm3/m2 )between. In addition, the composition of the ink and its viscosity have a great influence on the ink transfer performance. When choosing a plate that is suitable for all applications, it is important to keep in mind that the various components of the system, including plates, plate materials, ink rollers, and the ink itself, are very important. If you choose the right one with the right mix, you can get high-quality, consistent prints.