Analysis of Non-printing Digital Printing

With the increase in the amount of information, the rapid growth of digitalization and computer networks has brought great changes to the printing industry. The diversification of personal lifestyles and the desire to express personality have changed the nature of the media and the flow of information, and it has begun to show signs of turning from one direction to the other. In the printing business, using the Internet, on-demand printing, in which the compiled data is printed in the required quantity, has started.

As a huge equipment industry, the printing industry has come to the goal of improving productivity. In recent years, due to the digitization of information processing technology and the rapid development of hard copy technology, especially based on the technology that is fostered by family needs and business needs, inkjet and electrophotographic methods have promoted high resolution and high speed, and have sought to expand. Print on demand. In the printing market, we also advocating short lead times and small batches, the possibility of printing with variable printing, the digitization of printing devices and the reorganization of high-speed data communication networks, which have led to the development of on-demand printing environments. . As an on-demand printer, various methods such as an ink jet method and an electrophotographic method have been developed. Prototype development is still underway. Next, based on the electrocoagulation method, a technique relating to an unelastic digital printer "Elcography" will be introduced.

In order to improve the printing speed and improve the printing effect, at the NEXPO exhibition in June 1996, Elcorsy and the Toyo Ink Company of Japan published Elcography. After that, at the IPEX exhibition in 1998, the Model 200 Elcography press was exhibited. The variable data was printed at 200 dpi printing speed, 200 feet per minute. At the DRUPA 2000 exhibition, the Elco 400 Digital press with a resolution of 400 dpi was displayed at 400 feet per minute. Currently, the two companies are developing new models that have improved the key parts of the press based on the Elco 400.

The main features of Elcography:

1) Use water-based ink, corresponding to VOC printing;

2) High-speed printing at 400 feet per minute (120 meters per minute);

3) There is 400dpi resolution;

4) Reproducible 256 price adjustment.

Elcography image formation principle: Elcography ink is the use of electrochemical resin solidification principle, according to the data signal, to adapt to the flow of current between the yin and yang electrodes, generate the corresponding size of the network, the formation of images, the principle of electrocoagulation is derived from the metal anode Chemical reaction between the functional groups of the water-soluble resin (polypropylene amides) and trivalent iron ions. The resin contains a carboxyl group and a hydroxyl group, and when it is rendered water-soluble, it is accompanied by reactivity with iron ions.

In addition to resins, Elco inks include pigments for coloration, dispersants for dispersing pigments, and chloride salts for conductivity.

Anode passivation layer

The electrodes that form the key to the image are composed of a metal anode covered with a passivation layer and a tip cathode arranged perpendicular to the anode, and Elco ink is filled between them.

The non-Kinxiu steel used on the anode of Elcography has the property of forming a so-called self-passivation state, is easily oxidized, and forms a thin passivation layer of several angstroms (A) which is chemically or electronically inert on its surface. When this layer is subjected to compulsive damage, in the presence of oxygen, a new passivation layer can be easily regenerated.

The anode of Elcography is in the shape of a roller, with a gap of about 50 μm, and the cathode is arranged opposite to the roller. As the anode roller rotates, the ink is injected into the gap between the electrodes.

2. Cathode activation and destruction of passivation layer

When the current does not flow through the electrodes, it is inert and does not cause any change. Once the cathode is given a direct current pulse corresponding to the image data, the charge initiates the electrolysis of the chlorine aqueous solution, and the chlorine contained in the ink locally destroys the blunt surface of the anode opposite the cathode. The layers activate the surface of the anode. On the surface of the activated stainless steel roller, the amount of ferric ions that should be pulsed is eluted into the ink.

3. Cohesion of resin

The eluted iron ion reacts with the carboxyl phase of the water-soluble resin dissolved in the ink, and the pigment particles dispersed in the ink are attracted to form a solidified body, and eventually a colored dot is formed. The amount of solidified resin is proportional to the amount of iron ions that elute, and the length of the current pulse can be adjusted according to the image data, so that the amount of solidified resin can be controlled.