Offset and flexo printing in the hottest corrugate

2022-08-26
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Offset printing and flexo printing in the corrugated paper printing market more than 10 years ago, flexo printing had not yet entered the field of color corrugated box production. At that time, there were no more than two ways of color printing: one was fine color cartons, which were printed on a single sheet of paper with offset printing and then pasted on the corrugated board; The second is bold text and color, and the following specifications can also be customized: M6, M8, M10; The corrugated boxes of block type are carved into relief plates with rubber plates, which are transferred to the cardboard surface after being inked, or painted on the carton board with a brush stained with ink by means of extension brush. Due to the complex production process, long production cycle and high labor intensity, the general corrugated boxes for outer packaging and transportation have few requirements for printing, as long as they can achieve centralized packaging and understand the packaging content

with the improvement of people's living standards when it requires the selection of synthetic raw materials for additives, corrugated boxes should not only complete the task of centralized packaging, but also clearly indicate the quality, specification, quantity, storage requirements and effective date of packaging products that prohibit the production, sale and use of plastic shopping bags with a thickness of less than 0.025 mm (hereinafter referred to as ultra-thin plastic shopping bags) nationwide. When these corrugated boxes are stacked on supermarkets, hypermarkets and various container racks, the patterns on the boxes can also promote the products and help attract customers. Therefore, over the years, color corrugated boxes have been used more and more widely in commodity packaging and circulation. With the change of living environment, people require that the packing box not only has a beautiful appearance, but also is attractive. In addition, during the contact process of using the packing box, it should not harm the human body and has the function of environmental protection. Upgrade the original transportation packaging of color corrugated boxes to sales packaging and product packaging. Flexographic printing color corrugated boxes are fortunately promoted in such an environment. After nearly 10 years of efforts, it has achieved vigorous development. The reasons are as follows:

flexo printing produces cartons, and the efficiency of cartons is higher

compared with the above three methods The fastest pre printing speed, the best printing quality and the highest efficiency is one of the more common methods used in developed countries

when printing color corrugated boxes by offset printing There needs to be a pasting process of slurry brushing, pasting and drying in the middle, which is the bottleneck in the production process and has low production efficiency. Secondly, most corrugated box manufacturers do not have offset printing equipment and need to be outsourced for processing. It takes time for printed matter to enter and leave, which will affect the production cycle of cartons

one is that 80% - 90% of the color corrugated boxes are now printed on a single corrugated board that has been cut into the size of one (or more) carton and directly printed by a flexographic printing machine. After the corrugated board has been formed Then print on its surface. This method is called "post printing" or "direct printing" in the industry. Because flexo is soft and light pressure printing, corrugation has little impact on printing pressure. Sometimes, although there are slight streaks, it can meet the requirements of the product. Moreover, after printing, slotting, indentation and printing machine online processing have been completed when the product is out of the machine It can be packed into boxes

the other is to use a wide flexographic press First print the roll of corrugated paper, and then put the printed roll into the face paper basin of the corrugated paper making machine It is compounded with the middle layer paper roll and the bottom layer paper roll to form corrugated board. After slitting, as long as the notch indentation can become a product. This way of printing before making corrugated board process is called "pre printing" in the industry

flexographic printing can print large format multicolor prints

it is well known At present, the most common specification size of offset printing machine is 1020mm x 720mm. This specification and below account for about 80% of the existing equipment -- 851/q 1270mm x 920mm full sheet machines account for about 10% of the existing equipment - 150/q offset printing machines larger than the full sheet are few in the country. It is understood that At present, there are no more than 10 offset presses with a width of 1.4-1.8m across the country, and there are almost no offset presses with a width of more than 1.8m. But the specification of corrugated box depends on the size of the product Many household appliances, such as refrigerators and large screen televisions, have a carton area of more than 2M2 Some even exceed 3m= or more. Therefore, offset press is difficult to meet these specifications. And the larger the offset press, the more expensive it is. It is reported that a four-color offset press with a width of 1.4m! There is no such product in China) the import price is about 10000 US dollars Even with this machine, it may not meet all the specifications. On the contrary, whether there are so many jobs suitable for printing machines in the local area is also a problem. So there are still some risks.

and the width of the multi-color corrugated printing slotting machine for flexographic printing is generally more than 2m, the price is about 10000 yuan, and the size and specification adjustment is flexible and easy to operate. There are thousands of machines distributed all over the country Across the country, many corrugated paper manufacturers buy dish flexo machines It can print by itself and send products directly to end users It is more convenient and has a short production cycle, which is very popular with users. Figure 1 shows the corrugated box products printed by flexo printing

flexographic printing can adopt high-quality ink printing

in the packaging and printing of food and drugs, the traditional method is to use offset printing and gravure printing technology. The ink used in offset printing contains heavy metal elements, and the ink used in gravure printing contains benzene and toluene organic solvents. These toxic substances have been excluded by the increasing environmental requirements of society. In late July 2005, Shanghai TV reported that the Shanghai food and drug quality supervision and administration had tested the packaging bags of two food processing plants and announced that the content of F in toluene per square meter should not exceed 3mg. The use of over standard packaging bags is prohibited, and the printing plant that exceeds the standard shall stop production. At the same time, I heard many export commodities In Europe and the United States, the packaging is not environmentally friendly and is refused entry from time to time

the water-based ink used in flexographic printing is a non-toxic printing ink There is only a small amount of alcohol solvent in the composition of water-based ink It is the only non-toxic printing ink approved by the U.S. Food and drug administration, so it is widely used in the packaging and printing of food and drugs. thus. Flexographic printing is called green printing. Since 2005, McDonald's, KFC and other fast-food restaurants in China have (2) low investment intensity. In order to meet environmental protection standards, paper containers such as dinner paper and packaging boxes have all been changed from offset printing to flexographic ink printing. Some factories that used to use offset printing had to be specially equipped with flexo printing machines An environmental protection printing workshop has been established. This not only ensures the environmental quality of printed matter, but also ensures that the printing business is not lost. The social and economic benefits are self-evident

China's flexographic ink is also developing rapidly. Today's products have excellent quality, stable performance, strong coloring power and bright colors. They can be printed on the surface of paper, plastic film, composite gold and silver foil, self-adhesive and other substrates It is a major advantage of flexo printing at present. The beer boxes in figure I and Figure 2 are printed with ink

the printing quality of flexographic printing has made great progress

offset printing is recognized for its excellent printing quality It has the characteristics of fine, small deformation, bright colors, rich layers, strong three-dimensional sense and so on. It is especially suitable for paper printing for people to read works in close range. This is the advantage of offset printing in quality. Using these mature technologies and conditions to provide supporting services for color corrugated boxes is easy from the perspective of printing quality. However, there are still many deficiencies in terms of substrate adaptation and auxiliary technology Affect production efficiency. Especially in the past 10 years, with the improvement of the accuracy of flexographic printing machine and the development of varieties, the wide corrugated board flexographic printing machine has been successfully developed (as shown in Figure 3). And the rapid progress of flexographic printing plate making technology, especially after the introduction of electronic color separation digital plate making technology, the printing plate quality has been greatly improved. Coupled with the improvement of the accuracy of machinery, the stable supply of supporting equipment and the in place service have guaranteed flexographic printing, and the printing quality has been comprehensively improved. The dot accuracy of large format color corrugated boxes has changed from 48 to 60 lines/inch Increase to 80-120 lines/inch Pre printing has adopted 150 lines/inch. So that the level of prints, three-dimensional sense and brightness Have been very close to offset printing. This has been accepted by end users. Therefore, in the expanding market of color corrugated boxes, flexo printing has achieved a competitive advantage in the market with its rising share much faster than offset printing as the cost is reduced and the cycle is shortened

according to the information, the United States uses the pre printing and post printing methods of flexographic printing, and the printed color corrugated boxes account for more than 90% of the national total; European countries are also more than 80%, so this technology has been recognized as one of the most mature solutions

offset and flexo printing process performance and cost comparison

see Table 1 Through comparison, the advantages and disadvantages of offset printing and flexo printing can be comprehensively studied and analyzed. Because the two methods involve a wide range of contents, it is difficult to list specific figures. If there is existing data in the enterprise, you can fill it in, and you can draw a conclusion that the benefit of which method is more ideal through comparative analysis

conclusion

from the point of view discussed above, flexographic direct printing corrugated paper can meet the requirements due to less process flow, simple operation and quality It can also be produced online In a more favorable position. However, this does not belittle the role of offset printing. The advantage and specialty of offset printing is to print more sophisticated products, such as exquisite picture albums, wall calendars, wall charts, books, samples, publications, tickets and other paper products. This is not comparable to any printing method at present It is the "leader" in the printing industry. However, in packaging and printing, which includes paper, plastic film, composite materials and other substrates, the printing conditions are quite different, for example, the surface of plastic film is smoother than that of paper The surface of corrugated board is rough And the adsorption ability of gold and silver aluminum foil to ink is different. For example, auxiliary processing, bronzing, indentation, die cutting, and pasting all need on-line production, so flexible relief printing with simple machine structure is used (even on multi-color flexo printing machines, silk screen printing, gravure printing, or offset printing with 1-2 color groups can also be mixed) It can also ensure the quality of prints Remove the complexity of printing Shorten the production cycle and reduce the production cost. The product has environmental protection performance It also has the anti-counterfeiting function and gets the effect of killing several birds with one stone. Why not do it

may these two printing methods be used in different fields Give full play to their respective strengths and advantages, and make due contributions to China's printing industry

reprinted from: Printed today

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