PS version: printing quality

Editor's note: In the printing industry (whether it is printing paper or printed iron), the PS plate is used as the transfer medium for lithographic offset printing. It is usually an aluminum alloy plate with a thickness of 0.15 to 0.30 mm and a layer of photosensitive liquid. The quality of the printing plate depends on the printing process of the PS plate and other influencing factors. It should be said that the printing plate quality is a prerequisite and fundamental of the quality assurance of the printing product. This article only describes and discusses some of the details that should be noted in the process of drying the PS plate.
At present, there are two types of negative and positive images in the PS version on the market, and the most commonly used is the positive PS version. The following focuses on the use of the positive version of the PS version. The positive version is a photo-decomposition type and is also a positive one. Since it is a photolytic type, what we are trying to achieve is the non-graphical part of the decomposition of visible light. It must be effectively removed, and it must not be dirty. The graphic part is not only resistant to printing, but also well reflects its high-profile part (usually we The high-profile part of the finger refers to the reproducibility of the network point should be more than 3%, even to 0.5% resolution should ensure that 10μm even to μm constantly line), and better to achieve the realistic effect of printing. The following highlights the points in the use of the PS version:
1. Exposure: The exposure of the PS plate, which is to be coated with a photosensitive layer, is placed on the workbench of the printing machine, and the film is placed. The main image and the light are exposed twice to make the pattern on the film display a basic “image” on the PS plate ( Note: It is recommended to use 1 illuminant light source with 3KW iodine lamp 2 lamp version distance 1m) for each type of PS version. It is recommended to use the iodine lamp as the best light source to achieve the best light decomposition effect of the light source on the PS plate. If the plate lamp is aged (exposure time is 20% longer than the new lamp), it is recommended to replace the lamp to improve Work efficiency and use of PS version.
2. The PS version of air guide granules technology is a more commonly used technology in the international printing equipment manufacturing industry. It can greatly increase the vacuum speed and effect of the PS version and avoid drying up. Therefore, it is recommended that manufacturers use the PS version with mature air permeable particle technology.
3, there is no formal test article, domestic, such as the Institute of simple test strips can also be used, the price is relatively cheap, general drying PS version in the normal development conditions, the gray ladder ruler should be all white and not the third level Is also the best exposure, what if these ladders are not there? First of all, according to the manufacturer's instructions for use with your own copy of the light source and lamp distance to make a judgment. For example, the PS manufacturer's recommended light source is a 3KW iodine lamp. The light is 1 meter away, your light source is 4KW, and the lamp distance is 1 meter. So the first thing you think about is shortening the exposure time. Then think about how long your lamp has been used. Is it better than when you buy? There is a possibility of aging, so that you will be more reasonable choice of exposure, and if your lamp distance has changed, then based on the theory that light energy decreases with increasing distance, you can increase or decrease the exposure time. In the second experience, a small piece of transparent tape is attached to the non-graphical blank portion of the film, and the usual empirical exposure is selected. After the exposure, the line of the edge of the tape just disappears, and the entire exposure is not completely disappeared. Normally, the edge will just disappear under normal development conditions without inking, and if the edge is obvious or not visible at all after exposure, this indicates underexposure or intensity.
4, development: development will be exposed after the PS plate flat on the developer tank, so that the developer is fully wet, about 1 minute after the removal of the wash plate placed on the wash station to wash away the coating is dissolved, thus significantly Out "image".
The vast majority of printing companies have such a situation. In the winter, there is no heating in the room and there is no air conditioning in the summer room. This type of room is similar to the outdoor temperature. The summer development temperature is sometimes as high as 30 degrees or more, and in the winter, it is even below 15 degrees. Lower, it is difficult to grasp simply by increasing or decreasing the development time and increasing or decreasing the concentration of the developer. It is very difficult for different people to master the technique inconsistently or differently. Plus some manufacturers use the developer powder without heating the water to dissolve, causing the powder to dissolve is not easy to stay on the surface of the PS plate, causing damage to the PS plate photosensitive film. In short, the development temperature of the PS plate is very critical, and is often printed by the manufacturers Ignore the problem; no way to take control of the addition and subtraction. However, it is often not enough to gradually increase the concentration of pharmacokinetics in the winter, and in the summer it is overlooked that reducing the dose of drugs is not used in accordance with the formula concentration. This has caused a lot of problems. Therefore, I suggest that air conditioners can be equipped on the basis of the manufacturer's prescribed recipes so that the ambient temperature does not deviate too much from the development temperature. General experience PS version of the development temperature at 23 ± 2 °C, then the indoor environment temperature is also best around 20-25 °C, if not this condition, it is recommended that manufacturers in the winter preparation pot hot water placed next to the developer or the developer tank, ready Add a little hot water, observe the fluctuation range of temperature, and in the summer, add some ice or gradually add cold water to observe the temperature change, so as to achieve the best development effect.
5. Development time: The development time tolerance provided by the general PS plate factory is relatively large, generally from 20 seconds to 1 minute. The problem is that the development time must be based on the understanding of the developer concentration and temperature, so that the development time is tolerant. Degrees can make up for the above two non-standard. It is well-known that the proper concentration of the developer is high and the temperature is high, the development time should be reduced. The other changes are also the same. In short. The developer concentration, temperature, and development time complement each other, and the change must be mastered by the printer. However, it must be pointed out that this mastery is passive. If you want to use the PS version correctly, it is recommended to strictly follow the temperature provided by the manufacturer. Concentration of the liquid, the time to use, and the range of change should not be too much for the best use.
6, revised version: revision is the majority of printing manufacturers, especially large-scale newspapers, books and printing companies are unwilling to accept, they a few days in a short period of time to make hundreds of printing, the task is indeed Heavy, if you re-revise, it will be even more work, but the PS version of the film for the production is a single piece, not imposition or composite imposition of the film, but now most manufacturers, especially newspapers and books and magazines imposition There are many more, this poses a problem for PS manufacturers, how to make the dried version of the edge line and a small point of drying remove, which in addition to the use of the principle of light to improve the refraction of the printing machine, PS manufacturers use multiple composite The sand layer structure and the abrasion resistance of the PS photosensitive layer have greatly improved, but the edge cannot be completely eliminated, because some of the plate printing machine has no double exposure and no light source scattering effect. What should we do? I think that in addition to the PS version of the factory to do work, in the use of the PS version, the printing plant should pay attention to the first from the purchase of the printing machine, consultation Shaiban machine is not iodine light source, there is no light scattering effect. There is no double exposure. Second, a single piece of film should be used as far as possible when making films. Third, try to scribble the edge of the piece of film with a blade as far as possible during the imposition. This will eliminate the edges better. As everyone knows that the film is almost transparent, the edges are affected by the external environment, such as hand-touching. The density has increased significantly and edges tend to form. If the edges are shaved during the imposition, the efficiency of the printing of the PS plate will be greatly improved. As a result, the difficult-to-manipulate links such as revisions in the printing plate are reduced, and the work efficiency is improved.
7, glue: Now the PS version due to the emergence of composite multi-layer sand, not glue is also very good, but the problem is that after the completion of the development of some manufacturers are not good, including indoor and outdoor and take the version of the machine, if on Good glue will make the non-graphical part of the PS plate form a protective film. The outside dust particles and dirt cannot enter into the sand. It is very easy to open the plate and protect the hydrophilic layer. The problem of non-gluing has arisen since most users do not pay attention to the middle stage after development and before the machine, and the version is randomly placed, resulting in a lot of dirt falling onto the layout or sticking to the layout due to the graphic part There is a photosensitive layer that does not adhere to dirt, and the image is not easy to absorb due to dirt. The dirt is very easy to adsorb and it is very cumbersome to clean. Affects the printing quality, so it is best to glue. And pay attention to uniform glue layer, the concentration is not too easy, a thin layer can achieve results.
8, baking version: baking version should be strictly in accordance with the recommended temperature and time operation, time is too short, the temperature is too low can not reach the baking version effect; too long, the temperature is too high will seriously affect the plate material performance, especially not only The discoloration of the layout is the basis for judging the baking version. The baking version should use high-quality baking glue. The baking temperature should be 220-240°C. The baking time is about 5-10 minutes.
9, storage and unsealing: light, heat easy to make chemical changes in the coating. The recommended storage conditions are 10-30°C and the relative humidity is not more than 60%. Kaifeng should be carried out under yellow light; it is advisable that the room should be protected from natural light, and the light sources other than the printing plate light source should be yellow light. When the plates are handled, they should be handled gently to prevent them from colliding, breaking or falling. The height of the stacking should not exceed 1.8 meters.