Detailed explanation of the printing process of th

2022-08-14
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Detailed explanation of the printing process of books and periodicals (middle)

Chapter 2 flat offset printing

brief introduction to the history of printing:

letterpress printing through breast feeding is the earliest printing technology invented by our ancestors, which has been more than 1300 years. Relief printing evolved from stamping seals and stone carving, and the earliest writing stones and seals existed before the Shang Dynasty. The real symbol of relief printing is block printing, which originated in the Tang Dynasty. Reverse words and simple graphics were manually carved on the wood block. At that time, the book was still in the shape of a scroll. In the Song Dynasty, there was a wax printing method, that is, painting wax on the wood, and then carving. The efficiency of carving wax is much higher than carving wood, and the binding of books has also changed into butterfly binding in the form of pages. Whether carving wood or wax, if you want to print the refreshed content, you must repeat the whole page. Any same words and graphics must be re carved, which is very troublesome. In the Qing Dynasty of Song Dynasty, Bi Yi invented movable type printing, which is a leap forward in Chinese printing. In the Yuan Dynasty, Wang Zhen improved Biyi's technology and spread this advanced technology to the world. In 1440 and 1448, the German Gudengbao improved the wooden movable type into the type, and made the type by casting. In 1798, Austrian composer serdeli invented lithography with Bavarian limestone. In 1905, lubel invented indirect lithography, which is now widely used, based on the principle of mutual exclusion between ink and water of SEI's lithography

classification of modern printing:

letterpress printing: letterpress printing has the longest history and is the most popular. The protruding part of the page image and text accepts ink, and the concave part does not accept ink. When the plate is pressed tightly with the paper, the ink will be printed on the paper. Printing plates are mainly in movable type plate, lead plate, zinc plate, copper plate, photosensitive resin plate, etc. Some books and periodicals, bills, envelopes, business cards, etc. are still using letterpress printing: those requiring special processing, such as bronzing, silver, embossing, etc., generally also use letterpress printing

lithography: offset printing is the most common and widely used printing method at present. The image and non image are on the same plane, using the principle that water and ink are mutually exclusive, the graphic part accepts ink and does not accept water, and the non graphic part is opposite. The printing process adopts the indirect method. First, the image is printed on the rubber drum, and the image and text change from positive to negative, and then the image and text on the rubber drum are transferred to the paper. Picture books, periodicals, brochures, books, samples, calendars, etc. can be printed in this way

concave printing: the principle of concave printing is opposite to that of relief printing. The text and image are concave and below the layout, and the concave part carries ink. The thickness of printing is related to the depth of the recess, which is deep and light. Due to the different inks printed on the four plates, the printed lines have a bulge. Coins, stamps, securities, etc. are printed with concave plates. Concave printing is also suitable for the printing of plastic film and silk. Due to the long plate making time and complex process of concave printing, the cost is very high

hole printing: also known as silk printing. If you have seen a teacher engrave wax printing papers in primary school, you will better understand this kind of printing method. The silk, wax paper, etc. of silk cloth, metal and synthetic materials are used as printing plates, and the graphic parts are hollowed into fine holes. The non graphic parts are protected by printing materials. The printing plate is close to the substrate, and the ink is infiltrated onto the substrate with a scraper or an ink roller. Silk printing can be printed not only on flat substrates but also on curved substrates, with bright colors and durability. It is suitable for printing labels, bags, T-Shirts, plastic products, glass, Metalware m and other objects

the above is a brief introduction to the types of printing, and modern books, periodicals and newspapers basically use offset printing, so professional book and periodical printing plants are equipped with offset printing machines

according to the number of colors printed, the flat sheet printing machine can be divided into monochrome machine, two-color machine, four-color machine, five color machine, etc; According to the printing method, it can be divided into single-sided printing machine and double-sided printing machine; According to the form of printing paper, it can be divided into flat sheet printing machine and rotary printing machine

schematic diagram of flat sheet offset printing

the advantages and disadvantages of a book after printing are related to the following factors: the first is the printing machine. It is easy to understand that if you want to do a good job, you must first use its tools. If a printing machine has low accuracy and poor stability, it is difficult to expect it to print high-quality books and periodicals

next is ink. High quality ink will make graphics and texts bright, bright and accurate, giving people visual enjoyment. Of course, this is not obvious for black-and-white books

there is also paper. The smoothness of the paper surface and the uniformity of the coating layer will directly affect the effect of graphics and text. Of course, different types of paper should be selected for printing of different properties, which will be introduced below

in addition to the hardware conditions of machine, ink and paper, there are also factors such as printing accessories, which will not be listed here. It is worth noting that in addition to hardware, there is also the influence of software, which is very important. For example, people drive the printing press, adjust the ink, and catch up with the color. Therefore, the technology, operation specifications, and heart of the operating workers are very important, which directly depends on management

printing knowledge

* advantages of CTP:

ctp technology refers to the technology that the digital information of graphics and text is no longer output to the film but directly output to the printing plate. It not only eliminates the traditional process of film imaging, plate making, drying, and the interval between the two chucks. When the plate and PS plate are changed, it also replaces the traditional analog technology or analog digital hybrid technology with digital technology, Therefore, CTP technology is known as a technological revolution in the printing field

Compared with the traditional PS version, the technical advantages of CTP plate material lie in:

1. It improves the plate making speed, and the plate making time is shortened from the traditional 50 minutes to only a few minutes, thus shortening the production cycle of books; 2. Set the number of experiments to stop automatically

2, improve the printing quality, and reproduce 1% - 99% of the points; The traditional PS version is at most 5% - 95%

3, the plate has high resolution (more than 175 lines/inch), which can meet the requirements of high-quality color printing

* printing plate and printing plate:

transfer the image and text points on the original plate of the color separation and plate making picture to the printing plate in a photosensitive way. For lithography, it is also necessary to make the image and text points of the printing plate have ink friendly performance, and the preheating temperature of the blank part is restricted by the setting out speed, and the position has ink friendly and repelling performance. This image transfer procedure is lithography printing plate. Only by drying the original picture into a printing board, forming an inked picture and text, and then transferring it to the paper through printing, can the reproduction of the picture and text be completed

plate printing is a bridge process between plate making and printing. For color separation and plate making, it is required to transfer the graphics and text of the original image without deformation. For next printing, it is required that the ink affinity of the graphic part and the hydrophilicity of the blank part should be clear, and at the same time, it should be able to withstand tens of thousands of times of imprinting friction without changing its ink hydrophilicity

however, since it is an intermediate transfer process, changes are bound to occur. In order to ensure its stability and less changes, it is necessary to control the photosensitivity of the plate, the printing operation process, the image transfer data and the adaptability to printing in the overall standard data of the plate making and printing process, so as to ensure a smooth and good complete reproduction

printing needs to be done twice in the whole replication process, one for proofing and one for printing. Therefore, plate printing is very important in the whole reproduction process. Its quality directly affects the print quality and printing efficiency

when printing color books (such as color book covers, pictorials, and color magazines), we only need four basic colors. C, m, y, and K are the four primary colors commonly used in printing. When printing primary colors, these four colors have their own color plates, and the points of this color are recorded on the color plate. These points are generated by the halftone screen. Merging the four color plates together is like a defined color. In fact, the four printing colors on the paper are separated, but the distance is very close. Due to the limited ability of human eyes to distinguish them, they cannot be distinguished. The visual impression obtained is the mixing effect of various colors, so various colors grow

Chapter III rotary printing

the printing principle of rotary offset press is basically the same as that of flat offset press. However, because the printing speed of the rotary machine is very high, the front and back are printed at the same time, and it is equipped with an automatic folding device, an eight color commercial rotary machine is very bulky. Of course, its printing efficiency is also very high. According to rough statistics, the output of one rotary press is equivalent to seven or eight flat four-color offset presses

the following are the characteristics of the rotary press:

l. The commercial rotary press uses web paper, which is suitable for thin paper with a paper thickness of less than 1059

2. The printing speed of the rotary press is very high, with an average speed of 50000 sheets per hour, while the printing speed of the general flat offset press is less than 10000. Moreover, the rotary machine prints both front and back sides at the same time, while the flat sheet machine turns over the printing after printing one side and the ink is basically dry

3. The wonder of the rotary machine is that the printed sheet is quickly dried and disconnected after printing, and it cannot be directly connected

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