CTP screen printing principle and the requirements of the ink

CTP screen printing has the following features:

(1) Reduce the plate making process and achieve the goal of rapid plate making.

(2) Save film, because no film is needed, so as to prevent the quality problems caused by film wear and network level loss.

(3) Screen positioning can be performed automatically for multicolor screen printing.

(4) The inkjet coating does not require a special photosensitive adhesive, and the commonly used photosensitive adhesive is suitable.

(5) The screen version of various meshes can be done.

(6) All kinds of frame, aluminum alloy frame and wooden frame can be used.

(7) Plate making up to 66x96.5 cm.

Screen printing CTP direct plate making principle is the use of computer digital processing technology to design the required screen printing image, after modification, finalized and stored in the computer. At the time of plate making, a laser ink jet printer was used to print the image on a screen previously coated with a photosensitive resin. This screen is called a pre-printed version (screen printing PS version). The ink-receiving image on the screen acts as a film or a cover film, and then the entire screen is exposed with ultraviolet light (stencil printing). The ink is partially exposed to ultraviolet light, and no chemical reaction occurs, resulting in a difference in solubility. After the same as the traditional photoengraving principle, exposure, development and imaging imaging plate. Please refer to screen printing CTP plate making process diagram.

Screen printing CTP plate, screen printing presensitized photosensitive emulsion used in the photosensitive layer, the general traditional all kinds of screen printing with photosensitive adhesive can be used. The requirements for laser ink jet ink are many, but the main two points are:

(1) The ink density and ink ejection amount are based on the final image optical density of 3.0 or more.

(2) The connecting resin for ink is preferably water-soluble so that water can be removed during development. However, if the photoresist is positive, the ink-based resin should be oil-soluble. Now Polaroid and Gerber Technologies of the United States have all developed such CTP platesetters.

The United States Gerber technology company developed the computer digital without film CTP platemaking machine. The plate-making machine can be connected with a personal computer. The necessary plate-making graphics and characters are input to the disk, and the disk is placed on the plate-making machine. After the plate-making machine is started, the computer-controlled ink-jet device mounted on the machine will follow the input. The image text is automatically sprayed on the screen that has been coated with photoresist. Injected by the ink jet device, of course, is not ink, but a special coating material, which can play exactly the same role as the traditional film printing.

In addition to the Gerber company in the United States, Denmark has also successfully developed a digital computer-less film CTP platemaking machine, the development of the machine is the Danish Mografa (MOGRAFA) company. It is different from the United States Gerber plate making machine in that the output graphic uses a laser-generated spot-exposure method, and the computer-generated graphic message is directly hit on a screen plate that has been coated with a good photoresist for exposure printing, and then rinsed. Developed screen printing plate. This kind of direct plate making method can also save the costs of film, medicine, and amplification, and avoid the undesirable phenomena such as dust pollution and blowholes generated in the conventional plate making process.





Source: Dalian Printing and Packaging Information Network