Plate making principle II of the most popular digi

2022-08-21
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The plate making principle of digital renewable lithography plate II

5. The plate making principle of copper ion type digital renewable lithography plate

the plate cylinder used for plate making in this way is coated with a layer of nickel oxide, which has the property of semiconductor and becomes a conductor when seeing light. When making a printing plate, first apply a negative charge to the cylinder body of the printing plate, then apply a thin electrolyte containing copper ions on the nickel oxide layer with a coating device, and then irradiate the electrolyte with a laser beam (the laser spot is generated according to the color separation data of the original). The light exposed part of nickel oxide becomes a conductor, which connects the electrolyte and the plate cylinder body, and copper precipitates on the nickel oxide layer. The precipitated copper ions form the image and text part. Where there is no copper ion precipitation, it is still nickel oxide, and the hydrophilic nickel oxide forms a blank part. After wetting and inking the printing plate, the ink is first transferred to the blanket and then to the paper. After printing a batch of prints, as long as the positive and negative electrodes of the printing plate cylinder and the electrolyte are reversed, and the copper returns to the electrolyte, the next batch of printing plates can be made

undoubtedly, the key of this technology is to ensure the stability of semiconductor properties of nickel oxide layer, the correct grasp of electrolyte concentration and the control of imaging laser head

6. Principle of coated digital reproducible printing plate making

using coating technology to make renewable printing plates is a subject that has been studied for a long time. The principle of plate making is to coat a layer of ink friendly special polyester on the hydrophilic plate base (this polyester can become hydrophilic and soluble in water under laser irradiation). Then the experimental data are measured by the oil pressure sensor and imaged on the polyester layer with a laser beam according to the original color separation data. After imaging, the printing plate began to be wetted and inked. The polyester irradiated by the laser gradually dissolved in the fountain solution, exposing the hydrophilic plate base below. In this way, the hydrophilic part of the plate base forms a blank part, and the hydrophilic part of polyester forms a graphic part. After printing a batch of prints, the polyester layer is removed by chemical or mechanical methods, and then the polyester layer is coated on the plate base again to prepare for the plate making of the next batch of prints. The plates made by this method are generally used in horizontal printing machines

7. Principle of digital reproducible plate making of ferroelectric ceramics

to understand the principle of plate making of this type of printing plate, we must first understand the properties of ferroelectric ceramic materials. Ferroelectric ceramics are essentially lead zirconium titanate crystals, and the molecules of this crystal can be polarized to make the whole crystal present a positively charged state. Therefore, ferroelectric ceramic materials have three states: positive state, negative state and neutral state. If the ferroelectric ceramics are 3. Check the neutral state of the electronic universal testing machine system, you can use the imaging system to convert the ferroelectric ceramics into a charged state; If the ferroelectric ceramic is charged, it can return to the neutral state as long as it is thermally radiated. This ferroelectric ceramic material is plated on the surface of the printing plate cylinder, and the printing plate can be made by using this property

there are two ways to make a printing plate with this ferroelectric ceramic material:

1. During plate making, the ferroelectric ceramic material presents a neutral state, and its internal molecular arrangement is random. During imaging, a controllable electronic imaging system is used to polarize the corresponding parts of the ferroelectric ceramic according to the color separation data of the original. The polarized part can absorb the liquid color agent with opposite charge due to electrification, and then transfer the color agent to the paper. Because the molecular polarization of ferroelectric ceramics has a hysteresis effect, as long as the polarized ferroelectric ceramics are heated to restore the products to the neutral state in the hands of users, the next batch of printing plates will be carried out. This plate making method generally adopts contact direct printing method

2. In this way, the state of ferroelectric ceramics at the beginning of plate making is polarized, showing a positive or negative state. Then, during imaging, the surface of ferroelectric

ceramics is irradiated by laser thermal radiation according to the original color separation data, which is transformed into neutral ferroelectric ceramics to form the graphic part on the printing plate. The part that is not irradiated is still charged to absorb liquid colorant, which is the graphic part on the printing plate, When printing with this printing plate, the polyethylene material has good chemical stability. The inking roller and the printing plate are not in contact, and the spacing between the two is generally less than 0.3mm. The toner is attracted to the printing plate by the attraction between charges, and then the toner is transferred to the paper through the blanket cylinder. After printing a batch of prints, the next printing plate can be made by powering on the ferroelectric ceramic material and restoring it to the polarization state

these two methods are still in the experimental research stage and have not been put into production. From the above description, it can be seen that the key of this plate making technology is the development of liquid colorants and the promotion of technology

8. The principle of "reversible" digital reproducible printing plate making

the latest research achievement of renewable digital printing plate is to use "reversible" materials for plate making. The so-called "reversible" material can be understood as follows: under certain conditions, the same material is hydrophilic, while under other conditions, it is inkfriendly. For example, zirconate, a metal oxide, is hydrophilic under normal oxygen concentration. Laser irradiation is used to reduce its oxygen content. When the oxygen content is less than the critical value, it becomes ink loving. After heat treatment, it returns to the original hydrophilic property. Similar materials such as polytetrafluoroethylene can also be reversed. This "reversible" feature can just be used to make renewable printing plates

renewable digital printing plate is still a subject in the research stage, and more and more companies and research institutes have invested in the research of this subject. We have reason to believe that renewable digital printing plates, as an indispensable part of digital printing technology, will receive more and more attention, and more practical renewable printing plates with low price, high quality and stable performance will be studied. (Duan Huawei, Xi'an University of Technology)

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