Current situation and development of the hottest g

2022-08-09
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The current situation and development of gravure printing technology

first, the technical advantages of gravure printing. It has always been high-speed, wide width, low consumption and less downtime, which can obtain the best effect on various substrates. 1. High speed: at present, the maximum speed of web gravure printing machine can reach 55000 rpm, and the paper tape speed is about 15 m/s. 2. Width: the maximum web width of rotary gravure printing machine is: Publishing and printing 106 inches, building materials printing 150 inches, packaging printing 40 ~ 60 inches 3 High profile and short time: the adjustment time from the completion of the previous batch of work to the printing of new live parts is about 30 minutes. 4. Wide range of substrates: gravure printing adopts liquid volatile color ink and a short ink transfer system, so the ink dries quickly, which is suitable for the printing of non absorbent substrates. 5. High quality: gravure products are of good quality and can truly reflect the effect of the original. The layers are rich and clear, the ink layer is thick, the color saturation is high, and the ink color is bright and bright. The high quality of gravure printing is determined by its characteristics. Unlike letterpress and lithography, which rely on different levels of ink area, gravure printing adopts a hole structure, that is, it depends on different ink volume to achieve level expression. The hole structure of gravure printing is divided into three categories: equal size and different depth; Different sizes and equal depths; The size and depth are different. Because gravure printing adopts a hole inking structure, the ink layer of gravure printing products is thick, which can reach 12 μ M, and the thickness of the lithographic ink layer is about 3 μ M, the embossing ink layer is about 6 μ M or so. Gravure printing can achieve the perfect coverage that can be achieved by offset printing and second full page printing by selecting the appropriate line width and corrosion depth. 2、 Application status of gravure printing. At present, the total proportion of gravure printing in developed countries is about 1/5. Traditional gravure printing is considered to be suitable for printing magazines and commodity packaging products with a circulation of millions. 80% of the color printing of magazines with large circulation in Europe and America is done by gravure printing, and gravure printing is used for more than 30 magazines with the largest circulation in the United States; Gravure printing is also used for stamps and independent inserts of newspapers and periodicals. From the field of packaging and printing, gravure printing is mainly used in soft and hard packaging printing. At present, 70% of soft packaging in the world adopts gravure printing. In domestic cigarette packaging, the hard box packaging is mainly gravure printing. Gravure printing has not formed standard production in China for a long time, and simple products occupy the main position. Since the reform and opening up, China has actively developed the packaging industry, which has promoted the continuous development of China's packaging industry. The majority of printing manufacturers have realized that in order to survive and develop in the tide of market economic competition, they must make production standardized and high-grade, and updating equipment is the main wish of the majority of manufacturers. In the past decade, China has introduced a large number of multicolor advanced gravure printing machines and electronic engraving plate making equipment from abroad. Dozens of gravure packaging production lines are mainly used in plastic film and cigarette box packaging, which has fundamentally changed China's traditional gravure technology and has formed 2 gravure standard production. The output value of gravure printing accounts for about 10% of the total output value of printing in China. However, we should also be aware that gravure printing technology and equipment in China are still in the process of transformation from low-level and low-grade to high-level and high-grade. 1. Give full play to the traffic of imported equipment. Taking a comprehensive view of the gravure printing production lines introduced across the country for the purpose of printing cigarette boxes, due to the limited market business, most of the machines failed to give full play to their traffic, some of them started and stopped, and only a few of them worked normally, causing a great waste of the limited funds of the state. 2. The process of equipment localization should be accelerated. Due to the high price of imported gravure printing equipment, most manufacturers are unable to follow suit. How to improve the level of gravure printing technology and equipment in China as soon as possible has become the biggest issue facing the development of gravure printing in China. 3. The layout and type selection shall be reasonable. 3、 The development trend of gravure printing. Gravure printing is suitable for long-term products due to its large investment and high plate making cost; Gravure ink is toxic, so its development is limited. If the above shortcomings can be solved, gravure printing may also have a certain development. The current development of gravure printing technology, especially gravure printing. I particularly like the development of the face printing technology of the elderly, which will greatly shorten the preparation time of gravure printing, so as to improve the competitiveness of gravure printing in the short version and medium version markets. The development of gravure can be summarized into the following aspects: 1 Automatic gravure cylinder electroplating processing automatic electroplating line, the development trend is from full immersion to semi immersion, there is no sealing problem; The increase of copper content in electrolyte is monitored and controlled by the full-automatic control and measuring device of sulfuric acid content. The latest improvement in gravure drum processing is that people realize that the ideal printing surface needs grinding with grindstones, so on the drum processing equipment, the equipment has 2 ~ 4 grindstones that are automatically replaced. The minimum grinding amount is 0.5 ~ 0.6 μ m。 2. The rapid implementation of the film free engraving process (1) the new film free engraving process. The traditional gravure etching plate making process is now only used for packaging gravure printing and decorative gravure printing, which has no chance with pictorial gravure printing. Compared with traditional etching process, electronic engraving process is more reliable, repeatable and free of environmental pollution. In film engraving gravure printing, the process flow is: electric recording engraving manuscript → film → gravure cylinder. This process has two disadvantages. One is that there is an inevitable bottle strength link in the electric recording process - Manual patching, which restricts the production action of high quality and high efficiency. Manual assembly and cowperware have complicated processes, poor registration accuracy and large waste of materials. Due to the vibration during the experiment, it is easy to loose. Due to manual operation, the quality and production cycle are affected. Second, the output mode of Electrical Division is to record the color separation film. The film needs to be developed, which is affected by factors such as film quality, concentration of developer solution, temperature and processing time, resulting in many intermediate errors. It is imperative to adopt a new process of film free electrical carving. There is no film engraving system, and the process flow is as follows: electric division scanning graphic engraving manuscript - → color image file - → whole page graphic file - → gravure cylinder. Compared with the traditional process, the color separation sheet output by the electric division machine is omitted, and the world configuration of the scanning data of the electric engraving machine and the interface data of the electric engraving machine is omitted, which ensures the correct reproduction of the level, tone and color of the engraved image item by item. (2) Developing towards electron beam engraving, Haier company of Germany is an enterprise that studies electron beam engraving technology in the world. It launched this technology in 1976. It is to put the engraved drum into the vacuum chamber, cover the vacuum cover, and the vacuum pump discharges all the air in the chamber. When the drum reaches the working speed, the electron beam gun scans the surface of the drum through the optical control device according to the stored digital graphic information, so that the copper plated surface melts and evaporates at a high speed, resulting in a gravure cavity between spherical and cylindrical with different diameters and depths, which is easy to receive ink. (3) The laser engraving intaglio process first completely corrodes the intaglio cylinder, making its surface form a traditional inking hole (about 50 deep μ m) At the same time, the angle of acupoints and overprint marks are determined. Then, the epoxy resin with specific formula is coated on the surface of gravure cylinder by electrostatic spraying process, and the resin is cured by heat treatment, and the surface is smoothed by grinding. During engraving, the drum rotates at the speed of 1000 rpm, and a high-power carbon dioxide laser beam is used to scan the drum surface horizontally at the speed of 70mm/min to vaporize the epoxy resin on the image and text surface, and adjust the focusing degree of the laser beam to make the inking hole reach the required depth and size. After many times of scanning, the inking holes are smooth and clear, forming intaglio holes. 3. The photopolymer thin drum gravure is based on 0.3mm thick steel sheet, the thickness of photosensitive adhesive layer is 0.2mm, and the thickness of the whole gravure is 0.5mm. The weight is the same as that of offset plate. The plate making method is the same as that of ordinary resin plate, which can be exposed by platform type exposure machine or roller type exposure machine. First, pre expose to increase the surface strength and control the eye depth, and then print with the added positive image film. According to the type of printing plate, the plate washing solution can be ethanol based solution or water with a certain pH value, and finally dry it. The time to make a plate is about 30min. Stop steps of gravure photopolymer plate: ① install a clamping plate at both ends of the photopolymer plate with a hydraulic or pneumatic device and fix it in the corresponding groove of the drum body. ② Use a spray gun to inject paste ultraviolet curing bonding material into the gap, and scrape it flat with an arc scraper. ③ Shine ultraviolet light on the top of the roller joint to cure the bonding material. ④ Use the hair cutting device (temporarily installed at the original ink tank position) to remove the excess adhesive on the surface of the drum. Finally, remove the cutting device and install the ink tank. The whole process of loading the plate takes about 30 minutes. The printing plate cost is about three times that of the same full size offset plate, the printing speed can reach 10000 prints/hour, and the printing plate can be printed 50000 times continuously. 4. Realize fast proofing by counting with graphic database. Graphic database directly controls gravure cylinder plate making, which is naturally inseparable from digital rapid proofing coordinated with official printing with graphic database. The principles adopted by the digital rapid proofing system are different, for example: ① the inkjet printing principle system launched by stok color proofing company can be connected with various electronic plate making systems and electronic extensions, which is suitable for various standard data formats, and can use 30 ~ 250g/㎡ ordinary paper for proofing in the sun. The maximum proofing size is 460 × 635mm。 ② DuPont's latest "4cast" digital proofing system uses the principle of thermal sublimation. ③ 3M matchprint digital rapid proofing system, the latest product of 3M company, can produce two A2 high-resolution and color samples on any carrier material in 16 minutes. 5. The development of gravure printing machine is towards multi-purpose, multi-color, high-speed, automation, linkage and environmental protection. ① Multi purpose: with the development of science and technology, the printing range of gravure printing machine will be larger and larger, and it should be suitable for printing materials with a variety of materials and widths. ② Multicolor: as consumers have higher and higher requirements for the quality of printed matter, models with more than 8 colors will become common models. ③ High speed: most gravure printing machines are equipped with a transportation system, which can prepare for the next moving part outside the machine, so as to shorten the time of version change and adjustment. The development trend is that mechanical adjustment is gradually reduced. Increase effective working hours. In order to improve the replacement speed of the doctor blade, a novel pneumatic fixture device is used instead of the screw connection. ④ Automation: a. the fully automatic replacement system of the printing drum generally adopts the double-layer guide rail roller car for direct transportation, or the sedan chair crane parallel to the printing unit for transportation. b. Web gravure paper tends to adopt fully automatic paper roll conveying system, which includes the supply of paper roll and the removal of roll core. c. The use of automatic registration control and automatic tension control is to print a record mark on the determined position of the dynamic analysis print that undertakes to strengthen the notification of high-risk products and high-risk markets, detect the position of the mark by optical method, calculate the error, and start the compensation roller for correction. The paper roll brake automatically controls the tension state. After comparing the preset tension value, the variable momentum is calculated and fed back to the brake for control. d. The color measurement technology of spectrum is adopted to carry out closed-loop monitoring and automatic adjustment of printing quality. ⑤ Linkage: gravure joint production line enables printing and bronzing, polishing, die cutting, slitting, combined one-time molding processing, etc. Wide web gravure printing machines tend to use double width folding machines or two back-to-back or side-by-side single folding machines. A single folding machine can no longer be equipped with a gravure press with a width of more than 2.45m. The new web gravure printing machine tends to adopt the upper structure of alum triangle, which has great influence on folding products

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