Review and Prospect of the hottest flexographic pr

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Review and Prospect of the development of flexographic printing (II)

today's flexographic printing

at present, the development momentum of flexographic printing in the world is not reduced, and the future is bright, but the development of China is not satisfactory. Although some manufacturers have good benefits, most of them have poor status, and there are many difficulties and problems. Of course, this has something to do with the short development time and weak foundation of flexo printing in China. Looking at the current situation of flexo printing in China, there are the following problems

(1) the problem of development speed

although flexo printing has achieved gratifying development in China in recent 20 years, compared with developed countries, the development speed is still very slow. The relevant departments did not pay enough attention to this technology and did not carry out in-depth and extensive discussion

(2) market and equipment problems

at present, according to statistics, about 50% of the equipment fails to give full play to its benefits. Under the condition of market economy, we should first identify the market and introduce appropriate equipment after investigation, so as to produce economic benefits. In the printing market, flexographic printing is suitable for mass production and continuous production of prints, but at present, due to the small printing volume and unstable printing quality, the cost is increased and waste is caused. It is understood that at present, there are still some units engaged in flexo printing in China. Due to insufficient business volume and insufficient production tasks, the utilization of equipment is not high and they are in a semi hungry state. In terms of equipment matching, the first thing to consider when introducing flexographic printing equipment is the object of flexographic printing machine, and we should comprehensively understand the structure and performance of flexographic printing machine to ensure that the equipment configuration is reasonable and meets the requirements of flexographic printing. In the previous period, some enterprises only considered the price factor when choosing flexo printing machines, ignoring whether the configuration was applicable and reasonable. As a result, some printing products could not be printed due to incomplete configuration. The wrinkle roller is a quantitative roller that controls the amount of ink, and the shape and angle of lines and holes are directly related to the printed matter. According to the pattern and plate making requirements, the embossing roller should be adjusted or replaced at any time, otherwise it will not print good products. Generally, the plate cylinder should be made according to the size of the substrate, which is also a feature of flexo printing to save paper and reduce costs to the greatest extent. It is understood that most flexo printing machines are equipped with one color deck, one corrugation roller and one or two sets of cylinder

at present, the current situation of some domestic flexo printing enterprises is that they can afford to buy a "horse" rather than a "saddle". Some foreign enterprises we visited also have at least twoorthree flexographic printing machines, up to 15 production lines, and color groups from two-color machines to 12 color machines. They stock several corrugated rollers of various specifications and several sets of version rollers of various specifications. In addition, there are foreign leasing companies specialized in leasing version rollers. The price is calculated in days, which is convenient for users to rent and the company can generate income. Every enterprise has various specifications of round die cutting rollers ready to call at any time, and the die-cutting roller manufacturer takes about 2/3 of the time to repair the die-cutting rollers for users, and 1/3 of the time to make new die-cutting knives for users, forming a winning cycle

another tendency of domestic flexo printing enterprises is to purchase flexo printing equipment with excessive functions or incompatible with other functions of flexo printing machines, resulting in waste. For example, in addition to the printing unit, the flexographic press purchased by some enterprises is also equipped with automatic paper loading, bronzing, film covering, punching, numbering and other devices. Obviously, ② bench wear experiment: use parts or samples similar to parts to conduct experiments on a bench simulating the actual operating conditions. If these functions are combined to operate, the printing speed will be reduced, and if there is no suitable live parts, some functions will not be used for a long time, which will inevitably cause idleness and waste

(3) product quality and material supply problems

most of the products printed by the flexographic press that has been put into production are general products, and the number of high-end printing pieces that can reflect the characteristics of flexographic printing is very small, which indicates that the development of flexographic technology products is not enough. There is still a lot of work to be done in expanding the market. Although in the second national flexographic printing product quality evaluation conference in 2000, nine boutique awards, 22 excellent awards and 24 excellent works awards were awarded from the 100 flexographic printing products sent by provinces and cities across the country. However, compared with foreign products and domestic offset printing products, there is still a long way to go. In addition, the incompatibility with packaging design is also a factor restricting product quality. The differences between oriental culture and European and American culture make their packaging obviously different in design style, which also affects the development of flexo printing in China in the short term. Europe and the United States emphasize the strong visual impact caused by concise color blocks and lines, while China's packaging industry has been dominated and influenced by gravure and offset printing for a long time, focusing more on realism and using a large number of realistic level patterns. To catch up with the printing quality of offset printing and gravure printing with flexographic printing, it is bound to be difficult for end users to accept. Therefore, flexographic printing is less accepted in China than offset printing and gravure printing

each printing method has its advantages and disadvantages. For flexographic printing, although it absorbs the characteristics of gravure printing and lithography, such as high elasticity of plates, low printing pressure, short ink path ink transfer system, etc. However, if you have to face a variety of experimental objects, the flexible version is more prone to denaturation than the lithography and intaglio version under the effect of body pressure, and the point expansion is more serious. The reproduction range of the image tone of the double lithography and intaglio version is short, generally between 15% and 85% of the point percentage. If dot printing with a high number of lines is selected, the copied image is often lost in the bright tone, and the dark tone has the phenomenon of large dots and paste. Therefore, in flexographic printing, except that the substrate is a film material with extremely smooth surface, most substrates are printed with a number of dots and lines per inch, which fully shows that flexographic printing is not suitable for copying high-precision products, but for general packaging printing and newspaper printing, It can be said to be a superior printing method. Therefore, when choosing whether to use flexographic printing, we should fully consider the application scope of printing products, the requirements of products for image quality and the number of printing. Otherwise, comparing the printing quality with gravure and lithography will make the development of flexo go astray

in terms of raw material supply, most of China's flexographic printing auxiliary materials (except ink) are imported from abroad. Such as plate, double-sided tape, doctor blade, etc., are not only expensive, but also have a long supply period. There are few domestic agents, incomplete specifications and varieties, and users have no choice, which is the key to hinder the development of flexo printing. Domestic flexographic inks have a relatively complete range, including water inks suitable for all kinds of printing materials and the latest anti-counterfeiting inks. It should be said that the development is fast. The requirements for the fineness, fluidity, viscosity and other characteristics of ink vary with different substrate materials, and it is not that the higher the viscosity, the better. Therefore, developing corresponding inks for specific printing materials and different printing processes is an important way to improve the quality of flexo printing products, reduce the scrap rate, and expand the flexo printing market. Ink manufacturers should develop different types and grades of ink. At present, high-quality and fine aqueous gold silver ink and UV ink almost rely on imports, and the price is high

(4) process problems

compared with other printing, flexographic printing still has an urgent problem to be solved, which is flexographic printing process. So far, a unified industry standard has not been formed. Without a unified industry standard, printing companies and customers cannot be as flexible and free as when using offset printing technology. In addition, some products (such as candy and pastry) have relatively high requirements for packaging. Therefore, most of their product packaging is currently printed in intaglio printing. However, if we want to use flexo printing technology to print these packaging, due to the lack of a unified standard, It is difficult to ensure the consistency of printed matter. Therefore, people concerned called for the formulation of a set of corresponding process standards as soon as possible, otherwise it will affect and limit the growth and development of flexo printing process

compared with offset printing and gravure printing, flexographic printing has the advantages of relatively less investment, relatively simple equipment structure, easy operation and high production efficiency. Water ink, alcohol soluble ink and UV ink are widely used, which is conducive to environmental protection

The air gap is 0.2-0.6mm

but at this stage, flexographic printing has insurmountable defects compared with offset printing and gravure printing: the ink transfer method is limited by the number of lines of the embossing roller, the adjustment is more complex, and it is not easy to be compatible. Therefore, the line level part and the field line part are often separated for plate making, which increases the cost. Due to the greater flexibility and softness of flexographic plates, they are easy to deform after being pressed, resulting in poor ability to restore the original. The fineness of flexographic printing is now 136 lines/inch or 150 lines/inch, while offset printing and gravure printing are familiar with 175 lines/inch printing, and the restoration of the original is extremely excellent. In addition, in some color gradients or absolutely, flexo printing also has insurmountable defects

flexo is mainly divided into two categories: baseless and baseless. The thickness of plates with base materials is about 0.95mm, and the thickness of plates without base materials is 1.7mm, 2.28mm, 3.94mm, 7mm, etc. During plate making, the back exposure is first carried out, and then the main exposure is carried out. The length of exposure time varies according to the pattern level and climate. The development performance of the sense sequence is excellent. The most typical parts of the non photosensitive parts, such as Yindu District steel deep processing Industrial Park, Linzhou automobile and parts Industrial Park, and rail transit (railway equipment) industrial cluster, can be washed and removed with chemical solvents, and then desoldered and dried, A printing plate can be made in only 2 hours

at present, the eye tone original design of flexographic printing and the production of four-color overprint plate in China are still a weak link. We should learn from the experience of other printing methods related to process technology and combine the characteristics of flexographic printing to explore a set of theoretical methods, quality control and inspection means of making flexographic printing, so as to meet the printing needs of high-quality color printing

most printing plants are familiar with offset printing and gravure printing processes, but they are unfamiliar with flexo printing processes. After the introduction of flexo printing processes, the internal structure and management of the factory should be adjusted accordingly. No matter how good the printing plate quality is, if the printing process cannot keep up, it cannot fully reflect the intention of the original design and cannot meet the user's requirements. The common faults of flexo printing include poor inking, dry plate, paste plate, edge defects, improper pressure, image and text deformation, dimensional displacement, ink bar, etc. to solve these problems, in addition to equipment and material factors, we must also pay attention to the matching of embossing rollers, the pressure between embossing rollers and printing plates, the pressure between printing plates and embossing rollers, the relationship between ink viscosity and machine speed, etc. without a set of data and operating procedures, it is difficult to print good products. At present, flexographic printing industry should not only have its own printing experts, but also plate making experts and ink experts. With the application of computer technology, the requirements for plate making and printing technology are more stringent, and there will be more demand for high-quality flexographic printing talents

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