Application of the most popular flexographic print

2022-08-16
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The application of flexographic printing in newspaper printing

flexographic printing was first used in newspaper printing in the United States in the mid-1970s. In 1982, the United States launched a special flexographic press for newspapers. From then on, flexographic printing began to compete with offset printing in the field of newspaper printing. The San Francisco observer, San Francisco Chronicle, and observer all used flexographic printing and achieved good results. At present, about 30% of newspapers in the United States use flexographic printing; About 14 major newspapers in Europe use flexo printing; About 25% of Italian newspapers use flexo printing

in recent years, flexo printing has also developed rapidly in China, but on the whole, flexo printing technology in China is still in its infancy. In the total printing volume, flexographic printing only accounts for about 1.5%, and is mainly used for carton and corrugated box printing. Flexographic printing has not been applied in China's newspaper printing industry

The basic requirements of newspaper printing are: first, it should be timely and provide newspapers to the majority of readers at the fastest speed; Second, it should meet the quality requirements, with clear graphics and texts, bright colors and good visual effects; Third, we should be economical. On the premise of meeting the basic requirements, we should minimize the cost; Fourth, we should protect the environment. With the increasing requirements of the international community for environmental protection, we should meet the basic requirements of environmental protection, and we should ignore the basic conditions of newspaper printing. Next, we will make a brief analysis of offset newspapers and talk about the problems of offset newspapers

1. Adjust the structure of newspaper printing

at present, offset printing almost dominates the country in newspaper printing in China, and offset printing is used all over the world, regardless of the size and volume of printing. Europe and North America broke the single pattern of offset printing in the 1990s. We should also choose the printing method reasonably according to the specific situation. For example, the cost of offset printing for newspapers with a print volume of tens of thousands will be greatly increased. At this time, different printing methods can be selected according to different requirements

2. High paper loss rate and waste rate are the prominent problems of offset printing

in offset printing, controlling the ink water balance is an important problem, and realizing the ink water balance of offset printing requires a process. In general, it takes about minutes to adjust the machine and try printing from Startup to entering a stable working state, which will inevitably increase the paper loss rate. In the offset printing process, there are many factors that affect the ink balance, and most of these factors are changing. Even under normal printing conditions, waste products will appear due to changes in some conditions. For example, the paper loss rate of sheet fed four-color offset press is generally as high as 7%-15%, and the paper loss rate of web offset press is higher than that of sheet fed offset press. Therefore, in terms of economy, offset printing is not the best

3. Offset printing newspapers do not have much advantage in print quality

offset printing has high quality, which is based on many conditions. If the surface performance of the printing materials is required to be high, fine prints can be printed only when coated paper with high price and good quality is used for printing. Printing on paper is prone to the following problems:

(1) offset printing uses fountain solution, and the paper has strong water absorption, and the whiteness of the paper will decrease after water absorption

(2) because the paper surface is very rough, it will affect the clarity of graphics and texts

(3) in the printing process, it is easy to be affected by external factors, the stability of printing quality is poor, and it is easy to have faults such as uneven ink color and dim color

4. Offset printing newspaper is at a disadvantage in terms of environmental protection

offset rotary printing ink is a low viscosity solvent type ink. The solvent content in the ink is high. It is not added with oxidized conjunctival catalyst. It is directly absorbed by osmosis and heated and evaporated for drying. It is difficult for the print to be fully dried in a few hours. It is not only easy to get dirty during the printing process, but also when readers get the newspaper, the wet ink will stick to their hands. In addition, solvent based inks have a strong smell, which is detrimental to both operators and readers. The catalogue of technologies and products encouraged to be promoted and utilized in the building materials industry (2018 (2) 020) was issued. In addition, volatile organic solvents in inks pollute the environment. Therefore, rotary offset printing ink is a polluting ink, and its use should be gradually restricted

5. Offset printing newspaper has certain requirements for paper

offset printing newspaper has high printing speed and uses fountain solution. If the paper is too thin, it is easy to cause paper breakage. Therefore, the paper used for offset printing should not be too thin, generally not less than 52g/m2, which will also increase the printing cost

6. Offset printing has higher requirements for the operator's technical level

due to the complex structure of offset printing machine, its adjustment position is the most in all kinds of printing machines, and the control of ink balance is difficult to master, so there are higher requirements for the operator's technical level, basic knowledge and skills. According to reports, among offset printing workers, less than 1/3 are competent for the basic requirements of the collar machine, which shows that it is difficult to cultivate a relatively excellent offset printing collar machine

to sum up, in recent 10 years, China's newspaper printing has achieved offset printing, which has played a great role in the development and progress of China's newspaper industry. However, with the rapid development of printing technology, newspaper printing only adopts offset printing, which is not the best choice. Now the development trend of newspaper printing in Europe and America has proved this. In the future, China's newspaper printing should adopt flexographic printing technology on the basis of continuing to improve printing quality and reduce costs

Application of flexo printing in newspaper printing

flexo printing technology has made remarkable progress after years of development, especially in recent years, the key technology of flexo printing has made a major breakthrough, thus creating extremely favorable conditions for the application of flexo printing in newspaper printing industry. It can be considered that flexographic printing technology has been increasingly improved and has entered the stage of practical promotion in the field of newspaper printing

1. The prepress number defines the frequently used models for which the procedures are applicable: electrohydraulic servo, electromagnetic resonance, hydraulic and electric change the application of the worded workflow of the fatigue testing machine

the adoption of digital workflow is an important link to improve timeliness, reduce costs and improve quality. Its main contents and functions include open system, flexibility of making and finally modifying documents, PDF language format, electronic document exchange, trapping Large version, digital proofing and rip one-time output. Using this system can not only greatly reduce the process links and shorten the working hours, but also eliminate the influence of subjective factors of manual operation and ensure the quality of prepress processing. China's newspaper industry has a good foundation for adopting digital workflow. If we further improve and improve its standardization and standardization, we can greatly improve the technical level of China's newspaper Prepress digital workflow

2. CTP technology of flexographic printing has matured.

traditional plate making technology uses film to print, and it takes about 30 minutes to produce a set of color plates, which is not only time-consuming, but also difficult to guarantee the quality. Using CTP technology, not only greatly simplifies the plate making process, shortens the high-performance and new functional modified plastics, gradually replaces ordinary plastics and other materials, and is widely used in household appliances, office equipment, automobiles, mechanical and chemical engineering and other fields, which reduces the plate making time (the time required to produce a set of color plates is only 1/3 of the traditional plate making time), but also reduces the phenomenon of point increase, and greatly reduces the loss and merger of points in high light and dark parts, The reproduction ability of the printing plate is improved

at present, the world's famous prepress equipment and plate production companies have successively launched practical CTP products. The representative manufacturers include Agfa, Heidelberg, cliorsay angel, DuPont, Barco, Kodak Polaroid, BASF, hell, etc. the introduction of flexographic direct plate making system provides quality assurance for newspapers to adopt flexographic printing

3. Flexographic newspaper printing has advantages

compared with offset printing, using flexographic technology in newspaper printing has obvious advantages

(1) the cost of equipment is lower than that of offset press. Under the condition that the size of the substrate is the same as the printing capacity, the equipment cost of the flexographic press is about 1/3 lower than that of the offset press

(2) the printing speed is higher than that of offset press. At present, the printing speed of flexographic press can be divided into three grades: low speed (m/min), medium speed (m/min) and high speed (m/min). Because flexographic printing belongs to light pressure printing and sleeve printing plate can be used, the inertia unbalance force is very small, the paper is not easy to break, and has good running stability, so high-speed printing can be realized

(3) low gram weight paper can be used. Due to the good operation stability of the flexographic press and the absence of the influence of the fountain solution of the offset press on the paper performance, low gram weight paper (g/m2) can be used for flexographic printing. If the thick paper is changed to thin paper, the national newspaper printing paper can be saved by about 18% on average every year (based on the annual printing of 54billion pairs of folios)

(4) the paper loss rate of flexo printing is low. The adjustment and trial printing time of flexo printing is short, so the paper loss rate is low, about 2%, which is nearly 9 percentage points lower than offset printing. If the key is graphene supercapacitor and the amount of paper saved by using thin paper, only paper can save about 27% of paper every year. It is reported that due to the use of flexographic printing, the San Francisco observer has saved us $41million a year on paper alone

4. The use of ink and short ink path system provides a guarantee for the wide application of flexo printing

(1) ink. Water ink is an environmental friendly ink, which does not contain volatile organic solvents and can improve the printing environment. This is one of them. Second, the waste water after printing can be recycled after treatment, and all waste ink can also be recycled into ink for reuse. Third, ink is a fast drying ink, and there is almost no problem of rubbing when printing

(2) short ink path system. The closed roller short ink path inking system can quantitatively provide stable ink for printing plates, and the inking performance has been significantly improved. By changing the technical parameters of the roller (the number of lines and the geometric parameters of the hole), the printing product can get the required amount of ink

the use of closed reverse doctor blade system not only keeps the ink clean in the printing process, but also keeps the ink performance stable and ensures the consistency of ink color of printed products

a major breakthrough has been made in the manufacturing technology of ceramic corrugated rollers, which can process corrugated rollers with more than 1500 lines/inch, or high-speed corrugated rollers with 2000 lines/inch or even 2500 lines/inch. This not only greatly improves the service life of the corrugated roller, but also creates conditions for high-speed and high-precision flexographic printing

5. The quality of flexographic printing is good.

flexographic printing is used in newspaper printing, and the printing quality has the following characteristics:

(1) newspaper printing is mainly based on words, lines and color blocks. Flexographic printing has the advantages of embossing, clear graphics and texts, neat and bright pictures, and bright colors. In this regard, flexographic printing is better than offset printing

(2) it has good printing repeatability, which can ensure the consistency of ink color of prints

(3) the number of lines added to the printing plate can reach lines/inch. With CTP technology, its resolution can reach 1270dpi, which can meet the requirements of newspaper printing

(4) it can easily realize multi-color group printing and give full play to the advantages of spot color printing

it can be seen that the quality of flexographic printing can fully meet the requirements of newspaper printing

in short, newspaper printing has taken a gratifying step forward from the offset era and began to enter a new era of flexographic newspapers. As a large newspaper printing country, China's newspaper printing industry should also make due contributions to this. (Wu Jimei, School of printing and packaging engineering, Xi'an University of Technology)

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