The development of printing technology in half a century 1.3

Development of Platemaking Technology> Section III Development of Platemaking Technology

As the name suggests, plate making is used for making printing plates for the printing process. Since printing is traditionally divided into offset printing, letterpress printing, gravure printing, and stencil printing, platemaking is naturally divided into lithographic platemaking, letterpress platemaking, gravure platemaking, and stencil printing. The process technology of these four plate making processes, color separation, and netting (excluding gravure) is very similar, however, due to the different structure of the printing machine, the printing plates have different types of plates, and the plates are different, so that the plates are made on the plate. The four processes are quite different.

Changes in platemaking technology> First, changes in platemaking technology

The oldest in relief printing is Chinese engraving woodblock printing. This is described in the previous section. This section of the letterpress plate mainly refers to the modern printing since the letterpress, photo-production of copper zinc and photosensitive resin letterpress.

1. Bulletin board

In the initial letterpress printing, the printing plate was composed of lead type, lead blank, lead strips, etc. It was placed on the printing plate platform and fastened and printed. This is movable type printing. This kind of printing plate has only one or two thousand and ten thousand Indian prints, and it is necessary to retype after reprinting.

If the print volume is large, or if it is reprinted many times later, repeated typesetting is uneconomical. Especially for letterpress rotary presses, the plate cylinder is round and the movable type cannot be installed at all. For these reasons, people have found a letterpress method for making paper type from movable type, and then copying plate with lead type on paper type.

First, use thin paper-type paper to spread one by one on the movable type plate, and then beat it with a brush to make the paper surface fill the low-lying surface of the movable type and thus reproduce the typeface of the movable type. Casting lead on such a paper pattern results in a lead-cast version that is exactly the same as that of the movable type.

The height of the movable characters is 23.44 mm. One offset platform press is full of movable type. Its weight is more than 100 kilograms. The weight of the platform is so heavy that the plane is reciprocated. The huge inertia of motion makes it difficult to increase the printing speed. The use of pouring type, first of all can greatly reduce the weight of the plate, which is conducive to the safe and rapid operation of the machine; followed by the lead plate is a whole, when printing no longer have the word, scattered version of the defect; the third is the lead version can be bent into The arc is printed on a rotary press.

At the beginning of the fifties, it was manual paper-making. Not only did it have a high labor intensity, but also the quality of the paper type was not very good. In 1956, Shanghai Xinhua Printing Co., Ltd. successfully developed the automatic paper-making machine. In the future, many book and book printing companies improved the paper-making machine gradually. The use of machines to make paper patterns has reduced the labor intensity of personnel.

The further increase in printing speed requires the printing plate to be thinner and lighter. In the early 1980s, it was the printing factory in Beijing that brought back a version of the thin lead version from Japan. In 1981, the Beijing Municipal Publishing Administration Bureau held an on-site meeting at the Printing Factory in Beijing to introduce the techniques for making and using thin lead plates. After this on-site meeting, the thin-plate printing process was quickly promoted in printing and printing facilities around the country. Thin lead plate is not only lighter, but also easier and faster to install, and improve the printing quality and production efficiency.

2. The rise and fall of the photosensitive resin plate

The photosensitive resin version appeared in the sixties abroad. The new plate is a photochemical method that uses artificially synthesized high-molecular polymers with sensitization to make relief printing, and cooperates with phototypesetting to replace lead type and copper-zinc plates. This is a new letterpress platemaking process.

In view of the implementation of phototypesetting in the 1970s, books and periodicals printing presses were all using letterpress printers. They wanted to use advanced phototypesetting and make full use of the existing letterpress printing machines, so people generally viewed the photosensitive resin printing plate. The relief printing plate made of this material can not only save a large amount of nonferrous metals such as lead, zinc, and copper, but also be lighter and thinner than the metal plate.

Since the 1970s, some printing companies in Beijing and Guangdong have taken the lead in starting trial production of photosensitive resin plates (including nylon plates). The use of results proves that, regardless of the plate making process or the performance, the photosensitive resin plate is better than the movable type, cast type and copper zinc plate.

In September 1974, the State Publishing Bureau held a conference in Beijing for the exhibition of innovative technologies for the innovation of new plates. Representatives from 14 provinces, municipalities, and autonomous regions attended the meeting. The meeting affirmed the direction of replacing the lead plate with a photosensitive resin plate. After this meeting, the development of the photosensitive resin was listed as a research project in many print shops in the north and south of the Great Wall, inside and outside the Great Wall. So after the mid-1970s, there was a "photoresin heat" in the printing industry. By the early 1980s, the "heat" of this research activity had declined, and the printing of book printing still did not get rid of "lead and fire" technology.

What was the enlightenment of the rise and fall of photosensitive resin plate technology? In November 1978, the State Publishing Bureau entrusted the China Printing Materials Corporation and the China Institute of Printing Science and Technology to hold a press conference on letterpress printing in Wuxi, Jiangsu. The meeting held that the development of photosensitive resin plates all over the country has been in a spontaneous and decentralized state. There is no division of labor and there is no unified planning. Everyone is doing repeated tests at a low level, causing human, material and financial waste.

The plate of industrial polymer compounds like photosensitive resin plates is a high-tech product, and it is not enough to rely on printing companies to engage in technological innovation. Only by strengthening planning, investing in a certain level of scientific research, setting up a factory that specializes in the production of plates, and organizing industrial production, can we replace the “lead and fire” backward technology with its low cost and high quality.

After this, the photosensitive resin plate was still used in newspaper printing. Until 1993, after the printing of the newspaper was completely imprinted, the photosensitive resin plate gradually decreased as the letterpress printing disappeared.

The development of things is often "both reasonable" but sometimes "unexpected." Originally, the development of the photosensitive resin was originally intended to solve the problem of replacing the lead plate with a new plate. However, the final letterpress printing was replaced by plain printing. However, since the 1990s, with the rise of flexo printing, photosensitive resins have found their place on flexographic printing presses.

3. Copper-zinc plate free powder etching plate making method

The traditional letterpress typesetting and image-making copper-zinc printing plate (copper plate suitable for continuous adjustment of the original manuscript; zinc plate is the general line manuscript) two process routes. In the 1950s, the copper and zinc plates were made, and the negative film was made first. The negative film was exposed on the copper or zinc plate coated with gelatin ammonium dichromate sensitized adhesive (commonly known as printing) and then corroded. deal with. The copper plate was corroded with a ferric chloride solution; the zinc plate was etched with a solution of nitric acid and hydrochloric acid. In order to protect the convex image side from being corroded, the ink is rolled, red powdered, baked and etched during the etching process. This operation is repeated three to four times to achieve the necessary depth of corrosion. This is a backward manual process of plate making, and the quality of the plates is not high.

In the early 1960s, the Beijing Institute of Printing Technology introduced a primary corrosion method that does not use red powder, also known as powder-free etching. The institute also developed powder-free corrosion additives. In order to promote this new process technology, China Printing Materials Co., Ltd. organized the Guangzhou Zinc Sheet Plant and the Shanghai Nonferrous Alloy Factory to produce microcrystalline zinc plate materials, and the Yingkou Machinery Plant produced powder-free corrosion machines. In the 1970s, the powder-free corrosive copper-zinc plate method was widely popularized in printing plants and completely replaced the backward corroded red powder corrosion method.

The development of plate making technology> Second, the development of flat plate making technology

For more than 40 years, with the development and popularization of lithographic printing technology, lithographic plate making technology has made great progress. It has undergone fifties lithographs, protein plates, flat intaglio plates from the sixties to the seventies, multi-layered metal plates. Pre-coated version (PS version) since the 1980s.

Lithographic plate

Plain printing was developed from lithographs. The lithographic plate was originally called "painted stone." It was the plate-making staff who used the fatty substances to directly depict the graphic on the stone plate surface. Later, with the progress of the transfer method, the plate-making staff first attached the graphic containing the fat-transfer ink to the pasted paper, and then transferred the transferred ink on the pasted paper onto the stencil under the pressure. Lithographic version. Stones are heavy and neither easy to use nor easy to use. Second, this type of lithographic material is a natural marble that has been milled and has a limited source.

Due to these shortcomings of the lithographs, many printing factories in the 1950s gradually switched to the lithographed version of the zinc-coated leather plate. The printed version is lighter, but the principle of plate making is the same as that of the stone making version, and there is also a saying that this type of printing plate is a paste version. Slurry transfer ink transfer under the pressure effect, to expand outwards, so that the graphic thicker, so this version can only be applied to some thick lines, text printing.

2. Minami plate making process

In the lithographic plate family, there is also a version that is very old and has a small amount of usage, but is quite distinctive. It is said that it is a long-lived person who has been in Europe since the 1850s. In 1907, the Commercial Press formally established the Feiluo workshop. It is said that its small amount is due to the fact that the output of the Minami version print is minimal in the entire print product. But it is quite distinctive. It can copy continuous originals without going through the net.

The Feiluo version also belongs to photolithography. The process is as follows: 10 mm thick glass plate is used as a base plate, and a photosensitive solution of ammonium dichromate gelatin is coated on the plate, and after drying, the negative film is successively adjusted to the negative film for close exposure. Develop with water. Since the tone on the negative film is continuously changed, the exposure amount of the photosensitive film is also continuously changed, and the degree of hardening of the photosensitive film after exposure is changed accordingly. When the amount of light on the cloudy film passes through many places, the film hardens the wrinkles and absorbs ink, and its water repellent ability is weak. The printing ink layer is thick and has a dark hue; the light quantity passes through a small area, the film hardens the wrinkles, and the ink absorbing ability is weak, and the water absorption ability is strong. The printing ink is thin and light in color. Where no light is received, no hardened wrinkles are generated, completely hydrophilic, and no ink is absorbed. The Jurassic version does not require screening, and it can still print continuous-tone images with bright and dark effects at the light and dark levels. This is where the Jurassic printing is uniquely attractive. This is also not possible with other printing methods.

The graphic version of the Milo Edition is based on a film of different degree of hardening. Under the constant infiltration of water during the printing process, the wrinkles in the graphic area gradually lose their ability to attract ink or fall off. Therefore, the number of imprints of the Milo version is very low, generally around 500 impressions. Although the images are printed beautifully, the print resistance is too low, and the consistency of printed products is poor, which greatly limits its application.

After the public-private partnership in the Shanghai printing industry in the 1950s, part of the Jurassic printing factory was relocated to Beijing, and Shanghai retained part of it as a laboratory for Shanghai printing companies. I moved this part of Beijing to the Printing House of the Palace Museum and later changed its name to the printing house of the Cultural Relics Publishing House. For decades, the basic version of the Milon Edition technology