â— Photopolymerization Plates Photopolymer plates are usually composed of an aluminum substrate, a photosensitive layer, and a surface layer. The photopolymerizable layer is mainly composed of a polymerizable monomer (+ oligomer), an initiator, a spectral sensitizer, and a film-forming resin. The initiator generally uses a multi-initiator system with high quantum efficiency. The function of the spectral sensitizer is to effectively extend the photosensitivity range of the initiator to the wavelength range of the laser light, which can now be extended to 488nM (sub-ion laser) and 532nM ( Frequency-doubled YAG laser). The role of the surface layer is mainly to separate the oxygen molecules in the atmosphere to prevent them from entering the photosensitive layer, so as to increase the chain growth efficiency of the photosensitive layer, thereby obtaining high sensitivity.
Due to these effective measures, the sensitivity of the photopolymerization direct plate has been greatly improved, the minimum imaging exposure has dropped to about 10μJ/CM2, second only to the silver salt type direct plate, and this plate structure Simplicity, resolution, printability, and post-processing are similar to or even better than conventional PS versions. Since most of the high-sensitivity initiator systems have an inherent photosensitivity range in the UV region, and it is also very easy to extend the photosensitivity range to the UV-LD laser's emission wavelength range, the photopolymerization direct plate will become the next generation UV direct plate material. The preferred system has a very good development prospect. With the advent of ultraviolet photosource platesetters, many companies have begun to introduce photopolymerization direct plates suitable for imaging of ultraviolet light sources based on the original visible light photopolymerization direct plate. Typical examples include MC IMaGInG's LV-1 (for UV-LD lasers), LA-5 (for AR+ lasers), LY-5 (for FD-YAG lasers), and FUJI's LP series. Photopolymer sheet (suitable for AR+ and FD-YAG lasers) and more.
â— Infrared Thermal Plates The prospects for the development of infrared thermal plates have been promising so far and are considered to be the main products of the monopoly direct plate market. For this reason, infrared laser thermal plates are the most abundant and most versatile. In general, infrared thermal plates can be roughly divided into two major types, namely thermal ablation direct plate and non-thermal ablation direct plate. Non-thermal ablation is divided into thermal cross-linking and thermal transfer. There are three types of changes caused by heat. Among the numerous thermal plates, the post-processing plates that can be printed without any chemical post-processing after laser scanning and imaging are the development direction of the thermal plates, which has attracted great attention of major companies. In this competition, Kodak-Polychrome, AGFa, Presstek, Asahi, FUJI, and TORay are still important manufacturers and suppliers of thermal direct media systems.
The representative work piece for the thermal plate without post-processing is the thermal ablation direct printing plate directly introduced by PReSSTek. The plate technology is directly imaged by HeIDeLbeRG's direct image printing machine and other manufacturers' subsequent direct image printing. Get great business success on board. Last year, ASaHI company launched a non-thermal ablative thermal phase change/affinity change direct plate without post-processing at the IGAS Expo, which aroused widespread concern in the industry. Later, at the DRUPA`2000 fair held this year, several more companies joined this group. For example, AGFa Corporation, Kodak-Polychrome Corporation, etc. have all launched prototype products or released technology. Despite the impact of UV photosensitive direct media, the development of thermal media is still very rapid, and it is still not clear who is the winner.
In thermal ablation plates, PressTek thermal ablation offset plates are worth mentioning. This plate consists of an oil-repellent silicone surface layer, a photothermal conversion layer (light-absorbing layer), a oleophilic bottom layer, and a plate base. The silicone surface layer will constitute the final non-printing surface and will be removed under the effect of heat as the vaporization of the photothermal conversion layer, so that the underlying oleophilic layer is exposed as a printing surface that accepts ink. The main function of the photothermal conversion layer is to absorb the light energy emitted by the scanning laser and effectively convert the absorbed light energy into heat energy so that the temperature of the plate surface rises to reach the vaporization temperature level. The substrate of the plate can be either a metal substrate (such as aluminum plate base) or a flexible polymer substrate (such as polyester film substrate) with a relatively wide adaptability.
This type of plate can be printed immediately after laser scanning and imaging, and is therefore particularly suitable for on-machine platemaking systems. This is why a large number of direct image printing machines are equipped with such plates. Although this plate is also a direct plate with no need for post-processing, it will generate ablation vapor and debris during the scanning and imaging process. Necessary measures shall be taken for sewage disposal, otherwise it will cause pollution to imaging optics and the environment. . In particular, waterless offset printing is not the only choice for hot ablation type direct plates. With appropriate structural changes, thermal ablation type direct plates can also be used for conventional water-based offset printing. (To be continued)
Due to these effective measures, the sensitivity of the photopolymerization direct plate has been greatly improved, the minimum imaging exposure has dropped to about 10μJ/CM2, second only to the silver salt type direct plate, and this plate structure Simplicity, resolution, printability, and post-processing are similar to or even better than conventional PS versions. Since most of the high-sensitivity initiator systems have an inherent photosensitivity range in the UV region, and it is also very easy to extend the photosensitivity range to the UV-LD laser's emission wavelength range, the photopolymerization direct plate will become the next generation UV direct plate material. The preferred system has a very good development prospect. With the advent of ultraviolet photosource platesetters, many companies have begun to introduce photopolymerization direct plates suitable for imaging of ultraviolet light sources based on the original visible light photopolymerization direct plate. Typical examples include MC IMaGInG's LV-1 (for UV-LD lasers), LA-5 (for AR+ lasers), LY-5 (for FD-YAG lasers), and FUJI's LP series. Photopolymer sheet (suitable for AR+ and FD-YAG lasers) and more.
â— Infrared Thermal Plates The prospects for the development of infrared thermal plates have been promising so far and are considered to be the main products of the monopoly direct plate market. For this reason, infrared laser thermal plates are the most abundant and most versatile. In general, infrared thermal plates can be roughly divided into two major types, namely thermal ablation direct plate and non-thermal ablation direct plate. Non-thermal ablation is divided into thermal cross-linking and thermal transfer. There are three types of changes caused by heat. Among the numerous thermal plates, the post-processing plates that can be printed without any chemical post-processing after laser scanning and imaging are the development direction of the thermal plates, which has attracted great attention of major companies. In this competition, Kodak-Polychrome, AGFa, Presstek, Asahi, FUJI, and TORay are still important manufacturers and suppliers of thermal direct media systems.
The representative work piece for the thermal plate without post-processing is the thermal ablation direct printing plate directly introduced by PReSSTek. The plate technology is directly imaged by HeIDeLbeRG's direct image printing machine and other manufacturers' subsequent direct image printing. Get great business success on board. Last year, ASaHI company launched a non-thermal ablative thermal phase change/affinity change direct plate without post-processing at the IGAS Expo, which aroused widespread concern in the industry. Later, at the DRUPA`2000 fair held this year, several more companies joined this group. For example, AGFa Corporation, Kodak-Polychrome Corporation, etc. have all launched prototype products or released technology. Despite the impact of UV photosensitive direct media, the development of thermal media is still very rapid, and it is still not clear who is the winner.
In thermal ablation plates, PressTek thermal ablation offset plates are worth mentioning. This plate consists of an oil-repellent silicone surface layer, a photothermal conversion layer (light-absorbing layer), a oleophilic bottom layer, and a plate base. The silicone surface layer will constitute the final non-printing surface and will be removed under the effect of heat as the vaporization of the photothermal conversion layer, so that the underlying oleophilic layer is exposed as a printing surface that accepts ink. The main function of the photothermal conversion layer is to absorb the light energy emitted by the scanning laser and effectively convert the absorbed light energy into heat energy so that the temperature of the plate surface rises to reach the vaporization temperature level. The substrate of the plate can be either a metal substrate (such as aluminum plate base) or a flexible polymer substrate (such as polyester film substrate) with a relatively wide adaptability.
This type of plate can be printed immediately after laser scanning and imaging, and is therefore particularly suitable for on-machine platemaking systems. This is why a large number of direct image printing machines are equipped with such plates. Although this plate is also a direct plate with no need for post-processing, it will generate ablation vapor and debris during the scanning and imaging process. Necessary measures shall be taken for sewage disposal, otherwise it will cause pollution to imaging optics and the environment. . In particular, waterless offset printing is not the only choice for hot ablation type direct plates. With appropriate structural changes, thermal ablation type direct plates can also be used for conventional water-based offset printing. (To be continued)
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