No universal CTP

The print quality of the media, the desired level of quality, the number of plates required for each shift, and the economics of introducing CTP are the main criteria for a company seeking the most suitable CTP system. This requirement varies from company to company, so different CTP systems have their own market positioning. In other words, there is no single CTP technology that can meet all the needs of the market.

The three best-selling CTP technologies currently available today are silver halide, heat-sensitive, and photosensitive resins, which have all been proven in the market and can be supplied by different suppliers. All these technical processes are safe and reliable choices.

The best digital version uses a high-quality sanded anodized alumina substrate. This technology has been well tested by a large number of similar plate tests. For suppliers of higher quality plates, the high quality electrochemical sands and oxidation ensure that the plate is highly adaptable to the press, a stable ink balance, high quality printing results, and importantly, predictable To the press printing situation. The next consideration is the surface coating, which is why the various types of plates are present today. Many similar plates have only one simple coating. There are several layers of the digital plate. The chemicals used in these layers determine the sensitivity of the plate to the laser wavelength and the performance in different printing applications. In the 1980s, studies on high-speed plate coating began. At that time, users knew that lasers could not emit almost watts of energy, and UV lamps could. Just like today's thermal plates, lasers can be controlled in tens of watts. In addition, it is even better if a printing plate can be made with a few tens of thousands of watts of laser light. The photosensitive resin plate and the silver halide plate have several layers of coating, and even have better photosensitivity than the thermal plate, and can be exposed by a new type of violet laser. The coating of the printing plate undergoes physical and/or chemical changes during laser exposure. There is a very important critical stage when the surface of the printing plate is neither underexposed nor overexposed. For a positive digital CTP version, overexposure can cause excessive sharpening in the highlight detail, as well as for the negative digital version of the dark tone region. A long time ago, CTP suppliers hoped that in actual applications, the thermal plate should not be overexposed. Its theoretical basis is that the image can be formed on the thermal plate only when the temperature reaches the threshold, and both overexposure and underexposure are not.

Unfortunately, this is an impossible dream for the supplier - a very regrettable thing, because if all suppliers have only one technology applied to all occasions, it means that they can not be very good Use it. However, like other numbers (CTP) and similar plates, in reality, thermal exposure plates have to undergo precise exposure control in order to obtain optimal reproduction characteristics. This is why all manufacturers recommend optimized exposures with specially designed exposure wedges. Both plate and plate materials must be reliable and stable in performance.

Then, the properly exposed plate is developed. For the digital version, preheating can also be performed before development (but not always). In short, this can be seen as an image magnification stage. Preheating is used in the photopolymer plates of Fujifilm and Agfa, and is also used in some thermal plates. Preheating requires additional kilowatts of additional light and is an additional process in the process. For example, Agfa has provided hundreds of CTP systems to large newspaper companies, most of which use photosensitive resin (a few home silver halide versions). Preheating components have not caused product or system problems.

Three major CTP media technologies:

The silver halide CTP plate has a print resistance of 350,000 impressions, sometimes higher. The silver halide CTP system was once a popular choice for commercial printing and newspaper printing. Compared with the thermal printing version, the quality of the silver halide CTP system is higher. The silver halide plate has good photosensitivity to each wavelength of the light source. Silver is widely used in printing films all over the world, and laser exposure has also proved its application value is very good.

Therefore, silver halide technology is a natural choice for CTP. However, silver halide plate manufacturers do not recommend this plate for very large live job applications, nor are they recommended for UV printing.

The thermal plateau has the same high resolution as the silver halide plate. If a large amount of print is needed, the thermal plate can also be baked. It is also suitable for harsh environments such as UV printing. The general thermal plate is sensitive to infrared light of 830 nm and is exposed on an external drum type printing machine. The thermal CTP is a very good choice for many printers, and it is in good condition in the industry, but it also has applications where the application is not successful. For example, thermal CTPs strive to enter the newspaper printing industry, but in fact, a lot of Newspaper CTP is installed under visible light (or non-thermosensitive technology), and the high speed of visible CTP (usually several thousand times higher than the thermal sensitivity) means that silver halide and photosensitive resin are more Can be adapted to high speed newspaper CTP equipment. Unfortunately, this issue will often be discussed. Thermal plates and violet laser CTP devices are not compatible.

Photorespons is most commonly used in newspaper printing, but it has also been used in other commercial printing applications. It is generally believed that the resolution of the photosensitive resin plate and the thermal platen are not as high as those of the silver halide and are not suitable for high quality printing. For example, Agfa has set the maximum resolution of its N91 photosensitive resin to be 175 LPI, while the resolution of thermal and silver salt versions can reach over 200 LPI. The photosensitive resin version has been highly evaluated in a wide range due to its wide application, which may explain why it is valued in the newspaper CTP. Therefore, each CTP has its own characteristics and is suitable for certain applications. No CTP has its own characteristics and is suitable for certain applications. There is no CTP that can satisfy everyone's requirements. The demand for CTP technology in the market is diversified, and there are many today. Silver salt, photosensitive resin, and thermal plate applications are very successful.

The latest technology that can now widely disseminate the success of applications is purple laser technology. It was first exhibited at drupa 2000 and has been successful. Purple laser technology is a by-product of the DVD industry. In this industry, the lifetime of the laser is uncertain. Some people expect it to be 10 to 20 years. In this case, the violet laser diodes have a longer life than the platesetter. Taking into account the maintenance and repair of lasers, this means that the cost of violet lasers is the lowest, which undoubtedly promotes the popularity of violet laser CTPs. The low price of the diodes and the high quality of the image enable the manufacturer to provide the CTP for the double-sided or four-page printing printers. Further, high reliability means low costs and no worries. The combination of the two has attracted a lot of customers and clearly attracted the attention of suppliers. Many suppliers have already targeted the violet laser CTP system. Competition is a good thing for buyers. They see competitive prices, fast imaging and long life, which make this CTP very attractive. When using a silver salt plate, the violet laser can also provide the same quality image as the thermal sensor.

Process-free: no process CTP is replacing the current CTP? So far, no process TP has not been widely used. If no process version becomes mainstream, customers will want to see CTPs that are cheap and perform well. Unlike everyone's hope, the no-process version will not replace other CTPs, but will provide a useful supplement in performance. There are several different techniques for no process. Here we only discuss the most common ones.

The first is digital UV. The supplier has removed the dampening system of the traditional printing plate (UV exposure) and placed the development on the printing press. This has great limitations for plates that require traditional exposure, but it is possible for digital UV exposure versions. The plates are digitally imaged with UV light and then mounted on the press. The printing machine's wetting system removes the non-image areas.

The second is thermal. No heat-sensitive process technology is available and there is no need to predict whether it will happen. The advantages are also obvious, and thermal has been proven to have very good quality and performance. However, there are some areas that are less than satisfactory. Thermal imaging technology is not cheap. Today's non-process thermal imaging technology is not a general-purpose technology, it meets specific applications, but many other applications can not benefit from it, mainly because of its productivity, reliability, cost and other constraints. Remember, even if some suppliers like it, no one technology can dominate the CTP world. Each technology has its own characteristics.

The last is the inkjet CTP, which already exists and is often seen at the show. The image is sprayed directly onto the substrate or onto the carrier layer, which is later washed away. In recent years, inkjet CTP has made remarkable progress due to its advantages in quality and speed.

A large number of customer applications have promoted the development of CTP technology, many of which have already reached the photo-level output quality. It can be predicted that CTP will have greater development in the next few years.