Auxiliary application of the hottest static electr

The auxiliary application of static electricity in printing and post printing process

static electricity is a factor that puzzles printing. This kind of static electricity is the static electricity generated on the surface of paper or film material by friction with roller or air ionization in the printing process, which has a little impact on the printing quality. The static electricity involved in this paper is generated by special equipment and plays an auxiliary role in printing and post printing process

Application of static electricity in the printing industry:

gravure printing is the process of transferring a small amount of ink in the gravure roller hole to the surface of the substrate. Due to the surface tension of gravure printing ink, "said Zhang Ping, director of R & D department, as well as the capillary effect of paper, the same hole wall, the roughness of paper surface and other factors, it is difficult to transfer the ink and easy to form white spots. In order to solve these problems, ELTEX company of Germany developed an electrostatic ink absorption system. Its structure is: a high-voltage generator, an electrostatic discharge rod and two electrostatic elimination rods. Its principle is electrophoresis principle. A voltage of - 27KV is applied through the electrostatic discharge rod, and one-way DC current charges the surface of the embossing roller through air ionization. An electrostatic action area is formed between the embossing roller and the plate roller, and the ink is pulled to change its surface morphology, so that a part of it is higher than the surface of the plate roller and is easy to contact with the substrate, In case of such contact, the ink can be transferred, the transfer rate of ink can be improved, and the phenomenon of dot loss can be avoided, so as to improve the printing quality of products. The electrostatic ink absorption system can be applied to the gravure printing of steel 1-law chamfer decorative materials, books and periodicals and tobacco packaging. There is solvent in the printing process, and the electrostatic ink absorption system using high voltage is easy to produce sparks, which will have potential fire hazards, but the electrostatic ink absorption system of ELTEX adopts a reasonable structure to reduce the current to μ A. Short circuit current 33 μ A. There is no electric spark during use, which can ensure the safety of use

with China's entry into WTO, commercial printing will not only increase in quantity, but also have higher and higher requirements for printing quality. As a commercial rotary printing enterprise, we should improve the quality of our own printing products, reduce production costs and improve production efficiency

from the perspective of the existing paper and ink in China, the use of thermosetting ink can not only improve the printing efficiency, but also reduce the cost. Due to the problem of equipment configuration, there are many problems in the printing process, such as serious water loss, paper easy to break, serious paper wool, folding and cutting fracture, and low cooling efficiency, which leads to the failure of the equipment to produce at normal speed and reduces the production efficiency. German etex company has developed electrostatic humidification system and clearance eliminator for electrostatic recombination and improving cooling efficiency

in commercial rotary printing, the moisture content of web paper is generally 5% - 4%. After offset printing, the moisture absorption of paper reaches 6.5% due to ink absorption. However, using thermosetting ink requires high-temperature drying, and the temperature is generally 100 ℃ ~ 120 ℃. At this time, the moisture of paper has fallen below 1%. The water loss of paper fibers is more, the loose fibers will cause paper wool loss, and the paper dust is more, but for developers in most cities across the country, And the paper sheet is easy to be broken. During the folding process, the paper edge will break. Due to the uneven ink absorption and moisture regain of the paper, a depression will be formed at the binding belt, or there will be wrinkles or long and short pages after the book is formed. In order to avoid this phenomenon, domestic manufacturers with commercial rotary printing machines will reduce the machine speed but increase the production cost

foreign commercial rotary printing machines are generally equipped with electrostatic devices for electrostatic humidification and drum clearance to improve cooling efficiency. The Komori commercial rotary printing machine of Japan's Toppan Printing Company is equipped with 9. The compressor overload protection switch, ultra-high temperature overload protection switch, and the LG50 electrostatic humidification system of ELTEX, a water shortage protection device. The Heidelberg M600 commercial rotary printing machine of the United States is equipped with the moisten electrostatic humidification system of Germany's ELTEX

its structure is: pressure generator, electrostatic discharge rod, water mist spraying device, and the use process of electrostatic humidification system; High voltage electricity is generated through the voltage generator, and then there is a high voltage of 3KV through the electrostatic discharge rod (the electrostatic discharge rod is placed on the roller and connected with the ground to form an electric field), so that the surface of the paper is charged through the water mist spraying device. Due to the effect of the electrostatic field, the water mist will evenly diffuse to the paper along the direction of the electrostatic field, so that the water content of the paper rises to 3% - 4%, which can avoid the problem of water loss caused by the absence of this system. At the same time, the electrostatic application device is used on the first cooling roller. Because the paper is output from the high-temperature drying equipment, the surface temperature is high, and it is in contact with the cooling roller. The air between the high-temperature paper and the cooling roller is heated, causing the air to rise, lifting the paper, so that the paper can not be in good contact with the cooling roller (the wrapping angle between the paper and the cooling roller is reduced), and the use of the electrostatic application device makes the paper surface with static electricity, Because the cooling roller is grounded through the support, the paper with static electricity can better contact the cooling roller, so that the wrapping angle between the paper and the cooling roller is increased, and the cooling efficiency of the first cooling roller is improved, which can improve the speed of the printing machine, reduce the number of cooling rollers, and reduce the printing cost

there are two folding methods on the commercial rotary printing machine, one is to fold the paper into a book through the shaper, and the other is to separate the strips first, then clutch, and then fold into a book. In the former way, the thickness of the inner crease of its folding edge is significantly thicker than that of the second one, which is determined by the minimum fillet of the former. There is a minimum fillet radian at the first bend. In the second bend, the fillet arc length of the outer fold line of the second bend is longer than that of the inner fold line of the second bend, which is not conducive to folding on the one hand, but a waste of paper on the other hand. The second method is to separate the strips first, which does not have the problem of folding edge wrapping angle, so it is easy to fold and can save printing materials (paper is the most expensive factor in web printing). The second method requires an electrostatic clutch device in the equipment. There are two electrostatic discharge rods on both sides of several paper tapes, so that the paper has static electricity. Due to the effect of static electricity, the paper is firmly "bonded" together. It can prevent the paper from sliding, so as to facilitate the correct folding and cutting of the subsequent process

source: must win