Parameter control in the most popular flexographic

2022-10-01
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Parameter control in Flexo color printing (II)

selection of printing plate and embossing roller

after the negative film is output, the printing plate should be prepared. It is particularly important to select a printing plate that matches the printing method and ink type (water-based or solvent based). It is best to use a known printing plate that has the widest range of reproduction tones, the most accurate reproduction tones, good ink transfer performance, and the smallest plate expansion. The drying of printing plates must be controlled to ensure the uniformity of printing plates. The printing plate must be washed thoroughly. It is a practical method often used to increase the post exposure based on the normal exposure to reduce the bulge depth. It can ensure that the finest highlights are decomposed, effectively maintaining the cleanness and accuracy of printing

the printing plate performance is also affected by the selected fixing materials. Choosing low-density compressible materials with sticky back will cause the increase of dots, but sometimes it will cause white dots in the field area. Therefore, it is important to choose materials with uniform performance and good printability. Accurate positioning is also important. Check whether the printing plate is defective and ensure that the rule error is within the specified tolerance

the selection of the embossing roller not only determines the printing quality, but also controls the transmission of ink. In flexographic printing, the traditional industrial standard selects the embossing roller with an engraving angle of 60 degrees and at least 4 times the number of lines. For example, if the number of lines to be added is 150 LPI, the number of units of the wrinkle roll must be at least 600 LPI. If you can achieve the desired color density, you can use a small amount of ink to achieve a high level of printing quality

segmented corrugation roller is to divide a single corrugation roller into several sections along the width. The number and volume of ink holes in each section are different. In the printing test, the segmented corrugation roller is often used to print the given test target. Observe the printing quality of each section to determine the optimal combination of ink hole number and ink hole volume. In this way, under the given conditions, the optimal configuration of the corrugation roll can be obtained, and the corrugation roll that is worn or blocked by dry ink can be avoided. Because the consequence of doing so is equivalent to the reduction of ink volume, the reduction of color density, and the color balance of printed matter cannot be achieved. We must form a good habit of regularly and carefully cleaning the wrinkle roller and checking the ink hole volume to ensure the accuracy of printing

ink

the printing ink finally determines whether the four-color printing is successful or not, and the low-end production capacity is redundant. All 2. Whether the clamping pattern is firm in the reproduction workshop, plate making and printing are done for one purpose: to control the way in which the four-color ink is transferred to the substrate. Selecting printing ink is one of the main ways to control. Two ink systems commonly used in flexographic printing are water-based ink and UV ink. These two systems have their own advantages and disadvantages, but UV ink has an absolute advantage in Flexo four-color printing

water based inks include pigments, solvents, additives, resins and water. When they are dried, the evaporation of water and solvent reduces the volume of ink by half. Although water-based inks have been successfully used in flexographic printing, the dot gain is particularly significant. The dot percentage after 2% dot printing is L296 to 20%, while with L Wu, the ink dot percentage is the lowest. 1. Under normal conditions of use, the validity period of the fatigue testing machine's indication error verification once is 1 year, which can be 5%. In addition, the change of color concentration caused by the evaporation of water in the ink tank and the use of additives to control the pH value of the ink will also lead to the change of color in the printing process

u V ink system includes pigments, additives, monomers, oligomers and photoinitiators. It has a wider support range than water-based ink, and the dot increase is smaller, especially in the bright tone area. The ink is easy to use, provides faithful point reproduction (because there is no volatile component in the ink formula), and always maintains a consistent color concentration during the printing process. Due to rapid curing, it has good stain resistance and high surface gloss. As a 100% solid ink system, UV ink printing point is solid, without using the common "halo" phenomenon in other ink systems

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