Since Drupa 95, CTP technology has rapidly developed in the world, and the corresponding CTP plates are also rapidly developing. Data show that in 2003, CTP plates accounted for about 30% of the total plate material in the world, and it is estimated that by 2007 it will reach more than 60%. Among them, the thermal CTP technology is currently the fastest growing. The global thermal CTP installed capacity accounts for about 60% of the total, and it also accounts for more than 55% in China. The reason why the thermal technology develops so rapidly is because it has the advantages of high printing rate, high resolution and bright room operation, and is recognized as the development direction of future CTP technology.
Many world-famous suppliers of plate materials, such as Agfa, KPG, and Fuji, have developed various types of thermal CTP plates. The thermal CTP plate is divided into two types of negative and positive patterns. The CTP version of the negative pattern is partially exposed during infrared scanning and the positive pattern is partially exposed. In addition, the CTP plate that does not require development after exposure is referred to as an exempt plate. It is currently a hot topic for various plates suppliers. The imaging mechanism of the thermal CTP plate is various, and the CTP plate can be classified according to its different. The following describes the imaging mechanism and application of various thermal CTP plates.
1, negative heat-sensitive CTP plate
1.1 Pre-heating thermal cross-linked negative chart CTP plate
This is the earliest product that has been developed. The technology is very mature. It has a high degree of commercialization and practicality and is widely used. At present, all plate suppliers have production.
This type of plate is usually made by uniformly coating a heat sensitive layer on a pelletized and anodized or coated polyester base plate. The thermosensitive layer generally includes a film-forming resin, a cross-linking agent, an infrared absorbing dye, and a photothermal acid generator. The imaging mechanism is: when infrared light illuminates the plate, the infrared dye absorbs light energy and converts it into heat energy, and the acid generator generates acid. Under the catalysis of acid, the resin in the exposed area produces a certain degree of cross-linking, forming a latent image. After preheating, the resin in the exposed area undergoes a sufficient crosslinking reaction, while the non-exposed area does not react. The non-exposed areas were removed by developing with alkaline solution. The imaging process is shown in Figure 1.