Several major factors affecting the decline of plate wear resistance
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If the printing process is not standardized, it will cause insufficient printing durability of the printing plate. During the printing process, it will be affected by many factors, which will damage the printing plate and reduce its printing durability:
1. Printing pressure: Printing pressure refers to the mutual force between the embossing bodies during the printing process, which inevitably brings about compression deformation, speed difference and friction, and destroys the original structure and adsorption performance of the printing plate. The first is the roller pressure, that is, the pressure between the plate cylinder and the blanket cylinder. If the pressure is too large, the friction between the plate and the eraser will be aggravated, and the sand on the surface of the plate will gradually wear out, so that the dots of the plate portion of the plate are partially worn. Damaged, resulting in a decrease in printing durability. Again, the pressure between the ink rollers, that is, the pressure between the ink roller and the water roller, especially the pressure between the ink roller and the water roller and the printing plate, if the pressure between them and the printing plate is too large, It will increase the friction and damage the dots of the printing plate, resulting in "disappearance".
2. Dampening solution: The purpose of the dampening solution is to maintain the balance between the blank portion and the graphic portion, to protect the blank portion of the printing plate from ink encroachment and to extend it to the graphic portion. In printing, when the ink film of the printing plate is 3 pm, the water film is 1 l Am, which completely prevents the ink from expanding to the blank portion. If the amount of printing plate dampening solution is too large, the ink emulsification phenomenon is likely to occur, the density of the imprinted ink is not up to the requirement, and the degree of corrosion of the printing plate base is deepened; the printing plate "paste plate" and "stacking ink" affect the quality of the printed product.
3. The surface of the substrate is rough, powdered, and pulled, and sand is trapped in the paper. These materials increase the pressure during the printing process, accelerate the wear of the graphic portion of the printing plate, and reduce the printing durability of the printing plate.
4. Some ink pigment particles are coarser, such as gold silver powder ink and white ink. During the ink transfer process, the friction coefficient between the printing plate and the blanket is increased, and the wear of the graphic portion is accelerated to produce a "flower plate".
5. The remaining part of the printing plate maintains enough residual ink layer to prevent the graphic from directly contacting the dampening solution and protecting the graphic part of the printing plate. If the remaining ink layer in the graphic part is insufficient for a long time, the photosensitive layer is directly subjected to abrasion or acid-base erosion, which is easy to cause a "flower plate" phenomenon, which greatly reduces the printing durability of the printing plate.
6. The impact of printing machinery on the resistance to printing: some of the reasons are closely related to the improper operation of the equipment. For example, due to improper machine installation, the printing speed is too fast, the printing pressure is too large, causing the machine to vibrate, and the printing plate will wear faster when printing. The bushings at both ends of the blanket cylinder are seriously worn, causing the blanket cylinder to jump during printing, which inevitably causes the printing plate to wear and reduce its service life.
7. The blanket is used for a long time aging, the rubber becomes hard and loses elasticity, the fat-sensing ability is lowered, the ink transfer performance is poor, the ink of the printed product is light, and the printing plate wear is accelerated.