Since Drupa 2000 Agfa launched the chemical-free processing version of the Azura Green Star version, the free handling of the plate has caused great interest among the printing plate manufacturers and printing manufacturers. Compared to the traditional CTP plates, the plates are free of processing. Cost, environmental protection and other aspects have obvious advantages. Currently, the Green Star version has more than 1,000 users in the world, and the more it is in areas where strict environmental protection policies are required, the more attractive it is to deal with plates. At present, there are more and more plate materials processed on the market, and how to deal with the printing plates without treatment? What "processing" is dispensed with? What kind of user is suitable for using the free-handling plate? This article will address these concerns.

First, "free processing", what is removed?

When it comes to free processing of plates, everyone first thinks that after the plates are exposed in the platesetter, they should be directly printed on the machine without any processing. However, some plates require an independent cleaning unit to clean the plates before they are on the machine. Edition before you can get on board. Can this type of plate be called "free handling"? Before answering this question, let's take a look at what kind of processes are hidden before different types of process-free plates are printed on the machine.

Process-free plates have evolved to today and have gone through several different technologies. There are thermal ablation technology, polarity conversion technology, hot melt technology and so on. The representative product of thermal ablation technology is Agfa's Mistral Thermal Plate, which uses hot melt technology such as Thermoflex's Thermoplate and Azura Green Star.

The principle of the thermal ablation printing plate is to ablate the film layer of the non-graphic part through laser to expose the aluminum plate base. There is no change in the graphic part. After exposure can be printed directly. Its imaging and printing process is shown in the figure below.

This type of printing plate is a true process-free plate in our concept and can be printed directly without any processing steps. However, such printing plates are not currently commercially available on a large scale, and the dust generated during the imaging process has a certain influence on the environment.

Agfa's Thermolite printing plate adopts hot-melt technology and can be directly printed on the machine after exposure. Kodak's Thermal Direct Plates also do not require a separate cleaning unit after imaging in the platesetter and can be directly on the machine. These kinds of plates are in line with our concept of "handle-free", and they will be directly on the machine without additional processing after imaging. However, the process of cleaning is hidden, and the printing plate can be truly printed after the printer is cleaned. Its imaging and printing process is shown in the figure below.

After the exposure of the printing plate, the physical attributes of the graphic and non-graphical texts are different, but the colors are almost indistinguishable. The printing plate can hardly recognize the content of the pages before it is turned on. After the plate is placed on the machine, it is first wetted by the printer's water roller to dissolve the non-graphic portion and then inked. A portion of the dissolved non-graphic portion is carried away by the offset paper, and the other portion is dissolved in the fountain solution. After the printer cleans the plate, printing can really start.

Agfa's Azura Green Star version uses an independent cleaning unit. After the plates are imaged, they are cleaned by the cleaning unit before they are put on the machine. The imaging and printing processes are shown in the figure below.

The role of the cleaning unit is to clean the non-graphical part of the printing plate and expose the aluminum plate base. The second is to protect the printing plate on the one hand to protect the plate surface and extend the printing plate preservation time after exposure; on the other hand, it can make the plate surface. It has better hydrophilicity and ink affinity, quickly realizes ink-water balance during printing, and reduces over-printing paper.

From the above analysis, it can be seen that the current process-free printing plate obviates the need for the development process of the developer using a common CTP plate. However, there is a need for a plate cleaning process. The difference is that the plate cleaning is performed at different points. Returning to the question we mentioned at the beginning, before printing on the machine, can the plate of an independent cleaning unit be called “free handling”? I believe we already have the answer. The free-handling plate represented by Azura Greenstar Edition is the real “free handling”.

Kodak's Thermal Direct Plate uses press cleaning, and Agfa's early process-free plates also use press cleaning. However, the latest Azura Green Star version uses a separate cleaning unit. This change was made after fully comparing the advantages and disadvantages of the two different technologies. The only benefit of printing press cleaning is that it is more in line with the concept of “handle-free” in everyone's minds, but the use of an independent cleaning unit has a clear advantage for actual production.

1. The graphic part of the printing plate before the machine is clearly visible.
After the Azura Green Star version was cleaned up, the graphic part was the film layer, and the non-graphic part was the aluminum plate base. The contrast was obvious. Printers can easily identify and ensure the correct version. The printing plate clean printing plate, before the machine graphics and non-graphic parts are the same color film, can hardly identify, need to have strict production management methods to ensure that will not be wrong version.

The version of the room can check the quality of the plate before sending the Green Star version to the printing garage to prevent the layout from being flawed. In addition, the plate can be measured using a plate measuring instrument and a reflection densitometer to ensure that the percentage of dots in the plate image meets the requirements. The printing plate clean version of the printing plate, only after checking the printed matter can find the printing plate defects, reduce the effective boot time of the printing press, greatly increased production costs.

2. Faster ink-and-wash balance The Green Star version uses an independent cleaning unit that eliminates the need for a printer water roller and ink roller to clean the plate. When cleaning, the protective layer is coated on the plate surface and the water/ink balance can be quickly achieved during printing. . With the CIP3 ink distribution system, the first print product can be finished, reducing waste.

Printing plate cleaning plates need to take a non-graphical portion of the plate paper, and there is no plate protection glue, reducing the water / ink balance. Even if you have a CIP3 system, you cannot reduce overprinting and start up time.

3, after the image of the printing plate to save a longer time Green Star version in the imaging clean version can be stored for a long time, no difference with the ordinary printing plate, easy to print production scheduling arrangements. The press-free cleaning plate can only be kept for several hours after imaging, which is not conducive to printing production arrangements. At present, there are more and more publications in different places. The Green Star version has more advantages.

After the Green Star version is printed, it can be cleaned in the same way as a normal plate, and it can be stored for a long period of time after being protected by a protective tape for easy reprinting.

4, lower cost Compared to press cleaning, green star version has more independent cleaning unit, but the overall cost is lower. The Green Star version of the cleaning unit is simple in structure and does not require control of speed, temperature, refill volume and other factors. In terms of printing, it is possible to increase the effective start-up time of the printing press, shorten the preparation time for printing, and reduce the risk of errors. In a comprehensive comparison, the cost of independent cleaning is even lower.

Second, free processing plate for which customers?

At present, the price of processing-free printing plates is higher than that of ordinary CTP plates. It may be considered that only in the short-run printing market, which is not sensitive to costs and small-volume printing, the printing quality requirements are not suitable for use in the free-handling version. material. So what is the actual situation? We use Agfa's Azura Greenstar Edition as an example for analysis.

Using Agfa's Sublima, the Green Star version can reproduce 1-99% of the dots under 240 lpi screens. Using ordinary ink, you can achieve 100,000 prints. With the use of UV inks, up to 25,000 prints can be made (no baking version required). At present, domestic printing garages generally use high-alcohol content fountain solutions and strong chemical car wash water. The resistance of ordinary CTP plates to printing forces is greatly reduced in this printing environment. The green star version of the hot melt plastic ink layer is very strong chemical resistance, the same printing environment, can still achieve the ordinary ink of 100,000 India's resistance to India.

At present, the majority of commercial printers account for the largest percentage of the business under 50,000 impressions, and orders for more than 100,000 impressions are rare. Most printing uses 175 lpi screens. It can be seen that, considering the factors of quality, durability, printing environment and other factors, the Green Star version fully meets the requirements of commercial printing factories.

From the perspective of cost, the cost to be considered from the imaging to the upper printing of a printing plate includes the cost of the plate, the depreciation and maintenance costs of the platesetter, the depreciation and maintenance costs of the developing machine, the cost of the developing potion, the disposal cost of the waste liquid, and the labor cost There are many factors such as the cost of energy consumed, the cost of machine land, and so on.

According to actual calculations, if a printing factory uses 3,000 sheets of 1030800mm-sized printing plates per month as an example and uses ordinary thermal CTP plates, the plate price is RMB 62/sheet, and then one plate will be imaged and delivered. The total cost before printing presses was 81.2 yuan/card.

If Azura Green Star is used, 3,000 pieces of 1030800mm half-size plates will be exported per month. The plate price will be RMB 74 per piece. One plate will be imaged and the total cost before delivery to the printing press will be 80.73 yuan per piece. .

From the above analysis, it can be seen that the use of plate-free processing, although the cost of the sheet-printing plate is more expensive than the ordinary thermal CTP plate, but the comprehensive cost of the free-handling plate is lower than the ordinary thermal plate.

For most commercial printing manufacturers, free-handling plates can be used. If it is a packaging and printing company, printing a long-lived job that is higher than 100,000 impressions, or using a lot of UV inks and metallic inks, the ordinary thermal-sensitive media is more appropriate.
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Reprinted from: Printing Information