CTP technology enters the era of environmental protection
At the drupa printing conference in 2008, the Austrian newspaper printing company MediaPrint Group signed 11 sets of Agfa's NJStar direct plate-making machines at one time and a multi-year plate-use contract. Perhaps this order is just an ordinary one of many large order transactions at this Drupa conference, but it is indeed of extraordinary significance for the application and development of CTP technology. This company became the first newspaper printing plant in the world to adopt a processing-free CTP system, and used a purple laser processing-free CTP system. The continuous successful application of purple lasers with environmentally friendly characteristics and heat-sensitive processing-free CTP systems is undoubtedly sending us a message: the application of CTP technology is entering the era of environmental protection.
The processing-free plate is an environmentally friendly CTP plate. Traditional CTP plates, whether they are thermal or violet laser plates, will undergo chemical development and water rinse after exposure and imaging on the plate-making machine, consuming a large amount of chemical developer and water, without processing CTP plates Eliminating or simplifying this process, there is only a very small amount of waste liquid, or no waste liquid is generated at all, and the CTP plate making process is more simplified. It can be said that the treatment-free plate material helps us achieve green production of pre-press plate making. The appearance of purple laser processing-free plate material has broken the long-standing argument that only thermal-sensitive technology can realize processing-free. Now almost all users of thermal and violet laser technology can switch their CTP production to a more environmentally-friendly CTP plate-free production, and each technology has a variety of plate materials to choose from.
In fact, since the CTP equipment, plate manufacturers have not interrupted the development and research of CTP plate materials, the same environmentally friendly processing-free plate material is also the focus of the development of various plate manufacturers. At present, there are many processing-free plates that can be seen. For ease of understanding, according to the characteristics of the plates, we can classify them as follows:
1. Completely processing-free plates
The completely processing-free plate material is the plate material that can be printed on the machine directly after imaging on the plate-making machine, and there will be no other subsequent processing on the printing machine. If a completely processing-free plate material is used, combined with an advanced waterless printing machine, no waste liquid will be generated, and true green printing can be achieved. However, the equipment and technology threshold of this printing mode is too high, and it has no reference value for the printing users of the existing equipment.
Thermal ablation and thermally induced polarity conversion are two types of technology that completely treats plates without processing. Thermal ablation technology is to ablate the surface coating of the plate material through the thermal energy effect of infrared laser, exposing the aluminum plate base, and the graphic part is retained without laser ablation, thus forming graphic and non-graphic text section. The advantage of the thermal ablation plate is that it is completely processing-free, and development is completed when the image is exposed, without subsequent development. The disadvantage is that the dust of the drug film coating is generated during the ablation of the plate material. A special dust suction device needs to be added to the plate making machine. It is not a kind of plate material for the thermal direct plate making machine currently in use. In addition, because of the high laser energy requirements, the plate-making speed will be reduced a lot.
The thermally induced polarity conversion technology uses the surface coating of the plate material to change the polarity under the action of the infrared laser thermal energy, and the hydrophilic and lipophilic properties of the surface of the heated coating layer change. Such a printing plate can be directly used without other post-processing. Print on machine. However, due to issues such as production costs and printability, this type of plate has not been commercially produced in large quantities.
Due to the technical limitations of completely processing-free plates, there is currently only a small amount of trial production, and because the sensitivity of the plates is very low, even if a high-power laser is used, the production efficiency is still low, and it can only be used for production speed in the future. Undemanding commercial printing.
2. Processing-free plates developed on the machine
The so-called on-machine development is that after the plate material is exposed and imaged on the plate-making machine, the printing plate is developed on the printing machine, and the plate material is developed by the wetting effect of the fountain solution to remove the non-graphic part of the drug film. This machine-developed plate was first developed for direct imaging (DI) printers. It was all the rage around 2000, because direct imaging printers require a laser imaging device for each color cylinder. The laser cost and Subsequent maintenance costs are very high. From the current point of view, direct printing presses have been gradually replaced by digital printing presses. There are currently some users of processing-free CTP plates developed on the machine based on the heat-sensitive type. Because of the high requirements for the energy of the purple laser, the on-machine developed plates of the purple laser are not an option for existing purple laser CTP users. It is available as a plate material, so its application and promotion will take some time.
The advantage of processing-free on-machine development of CTP plates is that no chemical development is required, and there will be no waste liquid in the prepress platemaking. The disadvantage is that the development on the printing press, the identification and proofreading of the layout content by the printing operator, and the control of the quality of the plate making cannot be accurately performed, but it is easy to produce operational errors, causing waste of time and materials; in addition, in the development process of the machine, the printing plate The non-graphic part of the drug film enters the fountain solution circulation system, which will bring hidden dangers to printing. The on-machine development plate is designed for short-run printing, so the printing durability is relatively low, generally around 50,000.
In-machine development processing-free CTP plate material is limited in newspaper printing, because the existing bending plate punching machine based on the positioning of the center of the plate cannot confirm the positioning mark on the layout, and can not accurately perform the punching processing of the bending plate. The development of the printing plate on the printing machine is easy to cause paper breakage, and the content of the layout cannot be identified and confirmed before printing, which is also an obvious shortcoming in newspaper printing.
3. Chemical-free plate
The chemical-free plate is imaged on the plate-making machine and then subjected to development processing before being printed on the machine. This process does not use chemical developing solutions. It is cleaned with clean water or developed in the process of protecting the printing plate with glue. Compared with the traditional concept CTP plate, the chemical-free processing plate saves the chemical developer, no complicated and expensive developing machine is needed, and only a simple process can get the machine-printable plate with the same performance as the traditional CTP plate . Chemical-free plates still produce waste liquid, but the amount of waste liquid generated is only 5-10% of traditional CTP plates. The printing plate obtained by the printing operator has obvious contrast, the pictures and text are clearly discernible, no difference from the traditional CTP plate, and the printing durability is also very high, generally more than 100,000 prints.
Agfa's Green Star Edition (Azura) based on hot-melt technology is a typical representative of chemical-free plate materials. The surface of the Green Star plate is composed of thermoplastic particles. During the exposure and imaging process, the thermoplastic particles are melted and bonded together with the aluminum plate base, forming a graphic part. The printing plate needs to be coated with a protective glue before the machine is put on the machine. The protective glue softens the unexposed thermoplastic particles and detaches from the surface of the plate material under the external force of the brush, so that the printing plate is completed during the gluing process Development. The glue used is non-toxic and harmless, and the dosage is extremely low. 20 liters of glue can handle 300 square meters of printing plates. At present, this type of plate has been widely used in commercial CTP, but due to the problem of exposure speed, it cannot be used in newspaper CTP.
Agfa recently launched a purple laser chemical-free plate, which is similar to the green star version in development, but it needs to be pre-heated before the protective glue is applied, which can significantly improve the plate resistance. Imprint rate. The advantage of this kind of plate material is that it has high sensitivity and high print resistance, which is very suitable for CTP output and printing in the newspaper industry.
The above various processing-free plates can provide printing users with opportunities for green plate production, but as the actual production of printing plates, the most important feature is to have excellent printing performance and strong adaptability to fountain solution , High printing durability; secondly, the quality control of the platemaking is simple, the printing operation is convenient, it is best to use the plate material that can be used, and there is no special adjustment to the platemaking machine and the printing machine; there is also the price of the plate material, The comprehensive use cost of environmental protection plates is preferably not higher than that of traditional plates. From the previous introduction, we can see that the chemical-free plate has very outstanding advantages in printing performance and operability in printing. In terms of comprehensive use cost, the three technologies are equivalent, because the cost of developing solution and developing equipment is saved, and the use cost of processing-free plates will not be higher than that of traditional plates. In countries and regions, the cost of processing plates free is lower than the cost of using traditional plates because it reduces waste liquid emissions. Actual data shows that in 2007, chemical-free plates accounted for about 80% of all market-free plates.
As early as 1992, after the United Nations Conference on Environment and Development, countries and regions around the world almost made the coordination of the relationship between environment and development and the realization of sustainable development an important agenda and strategy. In China's recent "Eleventh Five-Year Plan", the quantitative indicators of "energy saving and emission reduction" tasks and measures are more clearly specified, and its purpose is to pursue less resource consumption, lower environmental pollution, greater economic and social benefits; Production methods and civilized consumption, advocate low-input, high-output, less pollution, and recyclable production modes; and actively promote the application of resource-saving new technologies, new processes, new equipment, and new materials. In the printing industry, CTP technology itself is an environmentally friendly production mode compared to the traditional laser phototypesetting process. In the CTP production, the use of film and the processing of film are omitted, which not only saves production materials and water resources, but also greatly reduces the discharge of waste liquid. Data show that the waste liquid produced by CTP plate-making is only one third of the traditional laser phototypesetting process. Various processing-free plate materials technology minimizes the generation of pre-press platemaking waste liquid, leading printing companies to gradually enter the era of green printing.
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