Newspaper web printing machine drying technology authoritative analysis report

PrintCity is a strategic alliance that brings together independent companies in the global printing industry. PrintCity's partners work together to find practical solutions to optimize production and workflow by sharing each other's technology and experience.

Recently, a research report on the printing of newspapers issued by PrintCity has aroused widespread concern among people in the global industry. This study systematically evaluates the unique economical and technical characteristics of newspaper web presses in order to improve products. Printing quality. In fact, the quality of printing depends on the paper, ink and curing system. The interaction among these three elements ultimately affects the capital investment, operating costs, maximum production speed, print quality and range of printing materials.

For multi-functional web presses in high-speed operation, the thermosetting device is the standard for mature processes, in addition to the common UV type, inert UV type, electron beam (EB ) type, they are also widely used in printing, packaging, and related technology has been very mature.

In the study, PrintCity specifically compared the UV and EB curing technologies together with other devices that play an important role in the production process to analyze and configure different newspaper web presses.

Oil-based offset cold-setting and thermosetting ink drying devices can well meet the requirements of high-speed production. Mineral oil-based inks and vegetable oil-based inks have a long molecular chain and are not prone to ink-flooding, and can be produced at speeds of up to 3,500 feet per minute. In the case of thermosetting devices, it is also possible to perform unrestrained drying on rolls of different qualities.

UV ink and EB ink

With UV light and EB energy, the UV/EB radiation curable ink cures by chemical bonding. The difference is that UV inks require photoinitiators to speed up the cure time; while EB inks require an inert gas to maintain a specific curing environment. UV/EB inks have the advantage of being able to print on any substrate, with little heat transfer to the paper. Frankly speaking, UV/EB inks are all strong in lithography. However, many problems that exist today are inseparable from their own characteristics. For example, if the molecular weight is low, the continuous printing speed can only be 1000 to 1400 feet/minute. Moreover, UV/EB inks require higher adhesion than conventional inks. Black ink curing is affected by the degree of UV light absorption. UV inks require photoinitiators and need to increase the lamp energy. Therefore, the above problems are solved in the short term. The speed is very difficult. In addition, acrylate is a very expensive ingredient that is a limited supply, resulting in UV/EB inks that are 300% to 500% more expensive than oil-based inks, and there is no potential for cost reduction.

Currently, EB systems are mostly used in web printing machines, as well as gravure printing machines that use aqueous ink to print cartons and plastics. Theoretically speaking, EB curing is completely a kind of cold processing technology, there is no problem of reduction of curing strength, not affected by ink color, and EB curing requires less energy and does not require frequent maintenance.

Inert UV is a brand-new technology that utilizes inert gas and ion generators to reduce the oxygen separation layer on the adjacent paper to prevent the curing from being hindered and improve the production efficiency of newspapers. By reducing the number of lamps or increasing the curing speed, the system can save lamp energy up to 35%, and can greatly reduce heat transfer and improve ink luster.

Technical assessment

1. Printing quality

The application of UV/EB curing devices has greatly improved the printing quality. However, UV/EB inks generally have the problem of increased printing dots. For printers who still wish to use cold-curing devices, high-value-added coated paper is a solution. The first choice for this problem.

2. Technical limitations

Although the use of UV/EB systems has significantly reduced various restrictions, it still exists. First of all, the most common printing problem at present is the ink sloshing and splashing, which limits the printing speed. Secondly, when using different types of inks alternately, the ink supply system must be thoroughly cleaned. Even a tiny residue can contaminate the radiation ink. Thirdly, UV ink itself has higher viscosity and lower fluidity, which brings a lot of inconvenience to the solution and cleaning of most ink sticks. Finally, the rubber roller and the blanket must meet the requirements of UV ink, otherwise it will lead to quality. The rapid decline.
If you set up a special printing unit to produce 100% of UV products, then all aspects of the restrictions will be greatly reduced.

3. Printing speed

Conventional thermosets can be produced at a speed of 3,600 feet per minute, but the nature of UV/EB inks has limited this speed. At present, narrow commercial web presses can print at speeds of up to 1,500 feet per minute. Sheet-fed presses and newspaper presses can print at speeds of up to 1,000 feet per minute. The upper printing speed can be increased to 1500 ft/min, but it is very difficult to achieve for newspaper presses, because the ink viscosity is a big problem, the ink flying problem on the UV ink roller is very high under high temperature conditions. frequently.

To date, inert UV systems have been able to produce up to 2,000 ft/min under test conditions, and the actual production speed maintained at around 1600 ft/min is likely to increase further.

As for EB ink, theoretically speaking, it has greater potential in printing speed, because of its high energy, no photoinitiator, and better curing efficiency than UV ink, so it has more to solve the problem of ink sling and splash. High flexibility.

4. Operating costs

Operating costs are mainly reflected in two aspects: the cost of ink and the cost of the curing device.

Affected by scarce materials and refining technology, the cost of UV/EB inks remains high, surpassing oil-based inks by 300% to 500%. In addition, the cost of converting a chiller to a UV system is also considerable.

In addition, the unit cost analysis of gas and energy in this report also shows that the energy cost of the thermosetting device equipped with oxidants is the lowest, which is almost the same as that of the EB system, but the conventional UV system is 50% more expensive, and Under normal circumstances, the UV lamp needs to be replaced every 1000 to 1500 hours.

5. Installation issues

The compact UV/EB system has a prominent advantage. Even if the existing cold-setting printer has limited space, it can also be refurbished curing device.

Economic evaluation

When updating technology, one of the major issues that people generally have to consider is the economics of the process. Usually, we can only get some information, and this part of information is incomparable. In view of this, PrintCity entrusted this research to experienced professional companies and made comprehensive and systematic data analysis through scientific modeling. Figure 1 shows the performance of a thermoset system, a general UV system, an inert UV system, and an EB system.

Chart 1

Taking a newspaper web press as an example, its width is 47.7 inches, the cutting size is 18.5 inches, and the printing speed is 2400 feet per minute. As its additional printing unit, all installation contents include printing tower and coating. The device, the automatic paper splicing device and the auxiliary drying unit, in which the input of the drying device is embodied in the installation and various types of devices necessary for the ink drying process, such as cooling rollers, paper guide rollers, inert gas, and the like.
Relatively speaking, due to the necessary oxidant, the investment cost of the thermosetting device is the highest; while the investment cost of the inert UV system is less than that of the ordinary UV system, it requires fewer lamps under the premise of obtaining the same speed; the EB system is in Between the two, but with the UV system compared to its curing speed is almost no constraint, as shown in Figure 2.

Chart 2

As shown in Fig. 2, in the operating state, the required cost per hour for the thermosetting device and the EB system is similar, while the cost per hour required for the conventional UV system and the inert UV system is about 8% higher than that. At the same time, there is a big difference in the hourly production output. Compared with the thermosetting and chilling devices, the general UV system and the inert UV system are lower, but this gap is not obvious in slow single-frame printing equipment. .

Calculated in three shifts, there are 5,307 hours of working time for printing operators in a year. The hourly rate includes the cost of labor (a printing operator and an assistant), plus indirect costs such as blankets, rollers, water, electricity, service, maintenance, and necessary management and marketing. The cost of capital involves currency devaluation and Interest, and other space costs are not counted because they are generally more diverse and have no impact on production. For each of the two different operating states of the drying device “on” and “off,” the relevant costs are calculated separately. Investing in a drying device for a cold-solid product means that an hourly fee will be incurred. Because of the need for energy and consumption, the operating costs are higher. However, once the drying device is applied, it means that the cost will increase.

Under the premise of processing the same representative printed matter, the overall cost reflects the difference in preparation time, production speed, and ink and paper replacement time. This is a major calculation method for comparing all cost factors. The sample is a signature book with a page size of 9.25 x 12.4 inches and a total of 16 pages. During the test, printing machines with different drying systems are required to print 100,000 copies on 6 types of paper.

Figure 2 shows a concrete comparison of the overall production cost of this job, assuming that the press has 50% of the time for printing, the remaining 50% of the time for drying, and the production cost of the chilled device is at 100% of the baseline price. It can be seen that the production cost of the thermosetting device still needs 14%, and the UV/EB system is 60% higher. To analyze, there are three factors that lead to an increase in the cost of radiation curing: first, the cost of ink is higher; second, the speed of production is limited (this factor is not obvious on slow single-web printing equipment); and finally, ink replacement Need to clean the printing press.

After the order

The method of improving newspaper printing quality is not unique. The technology of the current thermosetting and chilling equipment is very mature, and the market is recognized for its speed, quality and overall production cost. In contrast, ordinary UV systems are very successful in low-speed newspaper presses, while inert UV systems can accommodate higher speed newspaper web presses. It is worth mentioning that the EB system It is the most promising. The printing process of newspapers is different from commercial printing and cannot be determined by simple minimum overall operating costs. It also involves the frequent use of drying devices, the amount of funds that can be invested, and the installation space of existing printing presses. However, after all, we should analyze specific issues and make a comprehensive and systematic analysis before making investment decisions. The UV/EB system is not suitable for commercial web presses because of its high production costs, slow printing speed, and restricted operation compared to thermosets.