The development of printing technology in half a century 1.7

Development of Printing> Section 7 Development of Stencil Printing

Stencil printing, also known as filtration printing, includes stencil printing (commonly known as stencil printing), screen printing, and stencil printing. China is the first country in the world to use thin-film printing. For various reasons, stencil printing has not been developed in China. In fact, the principle of stencil printing is as simple as embossing. As long as a thin plate base is used to allow the graphic area to pass through the ink, the non-graphical blank area does not pass through the ink, and the printing plate is made. Then the printing plate is covered on the substrate, and ink is applied on the printing plate. The printing ink is transmitted through the printing plate area to the substrate.

Printing> First, copy printing

The printed version is subdivided into hand waxed paper and typed wax paper.

1. Hand-printed wax paper printing

Printed version printing is commonly known as mimeograph. Because of its convenient operation, simple equipment, and low cost of printing, it is almost universally spread to all aspects of society. The typing and writing rooms of institutions, schools, enterprises and institutions, social organizations, etc. are almost all printed and printed. There are also many types of printing services on the market. Just because of its poor printing quality, it is not a good thing, so the printing industry's competent authorities never regard it as a printing industry, but belong to the cultural service industry. But in principle, of course, it should belong to the printing category.

Although the name of the copy is called "version", it is actually just a piece of waxed paper. The wax paper is laid on a steel plate, and is inscribed or scribed on the wax paper with a steel stylus. Since the steel plate is covered with raised webs, the wax layer on the wax paper is coated by the steel nib and the steel plate mesh. Scratched to reveal the fiber pores of the wax paper itself, and the engraved wax paper was attached to the stretched frame and became a wax plate. When printing, the wax plate is placed on the substrate, and the roller is used to roll the ink on the wax plate by the ink roller. Under the pressure of the ink roller, the ink passes through the fiber pores in the graphic area of ​​the wax paper and is transmitted to the substrate. print.

This kind of printing method is simple enough that it can no longer be simple. It does not need any machine. As long as there are steel needle pens, steel plates, ink rollers, mimeographs, stencil printing inks and papers, they can be stenciled and printed. Although the printing quality is poor, the operation is simple and the cost is low, which still makes it widely popular.

2. Typing and writing wax paper printing

The handwriting of wax paper is simple, but the engraved fonts and fonts are less beautiful and the writing speed is too slow. Since the Chinese typewriter had been used, the use of typewriters to engrave wax paper has gradually replaced the manual writing of wax paper, not only the speed of typing is much faster than the speed of manual writing, and the quality of typing has also been better than the handwriting.

The principle of Chinese typewriters is basically the same as that of Western typewriters, but the structure of Chinese and Western typewriters is very different. The reason is that there are only a few dozen letters in the western alphabet, and there are thousands of Chinese characters. In order to make the structure of the Chinese typewriter as compact as possible, great care must be taken in setting the typewriter of the typewriter. According to the frequency of use of Chinese characters under normal circumstances, the Chinese characters are divided into special characters, common characters, inter-words, and spare characters, and a total of more than 2400 words are arranged in a dial according to a certain law. The typewriter's characters are made of hard metal and are called steel movable type. The tool that clamps the steel movable type is called the word hammer, and the hammer and the fuselage are placed on a smooth horizontal track, which can be easily moved back and forth and left and right so that the typing personnel can select words on the dial. The typing wax paper roll is mounted on the rubber roller of the typewriter. When typing, the typing staff selects the word on the dial and then moves the word hammer so that the selected steel movable type is facing the word hammer that captures the steel movable type. The typing staff presses the typing button, and the word hammer quickly grabs the steel movable type from the dial and hits the typing wax paper on the roller. As a result, the writing of the steel movable type was printed on the wax paper, and the wax layer was broken, exposing the pores of the typing paper fiber. After the word hammer completes the blow, it automatically sends the steel movable character back to the original dial. The typing rubber roller drives the typing wax paper to automatically step one grid to complete the typing task for one character. Repeat this process to fight waxed paper and finally complete the typing task.

3. Printing machine printing

Although hand-drawing printing is simple, the printing speed is really too slow. With a hand-printing machine, the printing speed can be greatly increased. Further installing a small motor on a hand-printing printer not only makes the operation more convenient, but also further increases the printing speed.

The screen of the printer is on the roller, and the engraved wax paper is attached to the screen roller. After fixing the position, the printer is started. The screen roller rotates the wax paper. When the input paper passes through the wax roller, the ink Passes through the wax paper to the paper, the silk net wax roller completes one printing every revolution. The domestic Great Wall brand 21 type printer can print 2400 to 3,000 sheets per hour.

Although the printed copy printing is quite popular, due to its poor printing quality, the resistance of wax paper is too low (generally 500 to 1,000 prints or so), and the capacity of the Chinese typewriter's dial is also limited, so for several decades, the printed version has been printed. Technology does not have breakthrough development. On the contrary, since the 1990s, with the advancement and improvement of computerized Chinese information processing technology, the slogan of office automation has gradually become a reality. Many offices have used computer typewriters, laser printers, and inkjet printers to replace wax paper. Printed version printing.

Printing> Second, screen printing

Screen printing plates were originally made with stencils, so they were called screen printing. Later, due to the decline of the Internet, the use of nylon nets, polyester nets, and metal nets was used, but due to the same printing principle, it was called screen printing.

Screen printing is the fastest growing and most used printing method in stencil printing. Before the 1970s, screen printing had always occupied a small share in several traditional prints, so that the printing industry saw it as special printing. However, after the 1970s, especially in the 1980s, screen printing has made rapid progress in China. Not only has the scope of application expanded step by step, but also there have been major technological improvements. The scale of screen printing has also expanded. The important feature of screen printing is that there is almost no requirement for substrates. Other than paper, other items are soft, hard, large, small, heavy, thin, flat, curved, and even cars. Body, walls, etc. can also be printed.

Due to the light pressure of screen printing, thick ink layers, bright colors, simple equipment, low investment, easy to start, it is widely used in printing and dyeing, building materials, machinery, ceramics, packaging and other industries, thus changing the people on the screen printing The traditional concept no longer regards it as special printing, but is like the plain printing, embossing, and gravure, and is one of four types of conventional printing.

1. Screen printing plate making process

The screen area of ​​the screen printing plate area is transparent, and a plate is blocked in the blank area of ​​the screen plate during the plate making process, so that ink cannot pass through. Screen printing platemaking process has the following kinds:

(1) Hand-painted version. In the fifties, photolithography technology was not very common, and in many places, screen printing was also hand-painted. Using paint shellac, alcohol, and ether to make a glue solution, cover the original with a screen plate, and use a pencil to describe the outline of the original image on a tightly-lined screen. Use a brush to dip the glue and put the non-printing space. The area of ​​the mesh is blocked and the mesh of the printed graphic area remains transparent.

Hand-drawing screen printing plates has low production efficiency and poor graphic accuracy. It is only suitable for printing thicker graphics, which, to a large extent, limits the application scope of screen printing.

(2) Photographic method. After the fifties, with the popularization of photolithography, the platemaking of screen printing has gradually adopted a photoengraving method.

The photographic process of photolithography is no different from the photographic process of plain, convex, and intaglio. It has been described in the second section of this chapter. Here mainly about the production of screen printing plate.

Direct plate method. This is a relatively popular platemaking method in screen printing. First coat the photoresist on a taut web. Before the 1980s, dichromate emulsions were used more often. Considering the environmental pollution of chromium metal, diazo sensitizers were gradually used since the 1980s. This kind of sensitized adhesive is not only non-polluting, but also has a long storage time. If it is placed in a cool place for a year, it will not affect its use. After the photosensitive film is dried, it is printed as soon as possible, and the positive film is adhered to the photosensitive surface of the screen printing plate for exposure. The blank area on the positive film forms a photosensitive curing film on the screen after being irradiated with light; the image area on the positive film blocks the light, the film on the screen is not sensitive, and after being developed with water, a transparent mesh appears. After the development is completed, immediately dry the film with a hair dryer and print it after finishing.

Indirect plate making. Different from the direct plate-making method, the indirect method of photosensitive adhesive is not coated on the screen plate, but is pre-coated on the substrate. After the photo-resist film is dried, the positive film and the photo-resist film are closely contacted for exposure. The photosensitive film was hardened with hydrogen peroxide and then developed with water. Corresponding to the blank area on the positive film, the photosensitive film is photo-cured and remains on the film base; corresponding to the image area on the positive film, the photosensitive film is not sensitive and is dissolved in the developing process. At this time, the rinsing and tightness of the screen plate is closely combined with the developed photosensitive curing film, so that the photosensitive film is transferred to the screen plate, the film base is peeled off, the screen plate is trimmed, and the screen can be printed after drying.

Direct indirect plate making method. This is a platemaking method that combines the two methods of direct and indirect methods. Firstly, apply photo-sensitive adhesive on the base of the film, attach the photo-resist film to the taut web, apply the photo-resist in the frame, bond the photo-sensitive film to the screen, and remove the film base after the film has been dried. The film is completely attached to the screen. Then the screen plate and the positive plate close-up exposure, development and drying are the same as the direct method. Comparing the three platemaking methods, the direct method is easy to operate, low in cost, and the most widely used. However, the edges of the outline of the picture are prone to jaggies and the lines are not very smooth. The indirect method has smooth outlines, high plate making cost, and low resistance to printing. It is suitable for printing with fewer prints but higher quality requirements. Direct and indirect methods are more complicated, and other properties are between the two (Figure 23-10).

(3) Other plate making methods. Since the stencil printing has almost no requirements for substrates, plastics, metals, glass, ceramics, textiles, etc. can be printed in addition to paper. Therefore, stencil printing can be selected according to the form, nature, and printing accuracy of the substrate. Platemaking method. In addition to the above net version, there is a method of engraving and electroforming.