How to improve the quality of printing plate

Shaiban is the process of transferring the original image and text to the PS plate. It connects the plate-making and printing bridges. The Environmental Festival is of paramount importance throughout print quality management. How to improve the quality of printing plates, reduce waste, and reduce costs, according to their own practice, from the following aspects to talk about experience.
First, we must have a high sense of responsibility and professionalism 1. Shaiban operators should be proficient in the performance of Shaiban, technical parameters, etc., to cherish the equipment, the need for regular maintenance of the equipment to ensure the normal operation of the Shaiban.
2. Keep the environment clean and keep the temperature and humidity in the room. Check the original carefully before printing. If you do not meet the printing requirements, analyze and deal with the specific situation to avoid unnecessary waste. The two sides of the plate of the printing machine Wipe.
3. Refer to the process sheet to check whether the original specifications and dimensions meet the job ticketing requirements; whether the mouthwash, belt mark, color mark, and station mark are complete.
Second, the quality of the original 1. First we must check the density of the original. The density of the original original site is about 3.0, and the density of dots, texts, and lines at this time meets the requirements of printing. Just perform normal exposure development. However, in actual production, it is often encountered that some of the originals have low or high density, so they must be dealt with according to different situations.
a. The lower density of the original text, in the exposure process, due to the low density, easy to make the light through the edge of the network, so that the photosensitive layer should not see the photo decomposition of the light decomposition occurs, the dot gray after development, Smaller, if it is text, the lines will become lighter. The ink is not saturated when it is on the machine, which reduces the printing resistance rate and does not achieve the desired effect. For this type of original to take less exposure, less development methods.
b. The high density graphics (blank part density is greater than 0.05), the original surface has a layer of fog, the corresponding network points, lines are not clean and there is a layer of fog, this layer of fog when the light passes Obstruction, so that the bottom of the fog edge of the network is not completely decomposed. After the development, the dots are enlarged, in particular, the enlargement rate of the dark tone portion of the image is increased, and the dark tone is graded and paste-printed during printing, which also fails to achieve the desired effect. For this original version, multiple exposures and multiple development methods are required.
2. Due to the revision of some graphics, the entire original “open skylight” part has become more difficult for the printing operation. The edge of the tape is too close to the image to make the image pad virtual, because the overlap of the film base will cause static electricity, the middle sandwich is easy to absorb some dust, and small sand particles will make the image pad virtual, and some original image parts will be folded out of the horseshoe nest and exposed. After this, the image also appears imaginary. For these phenomena, it is required that the printing operators find timely solutions.
3. Some of the original text of the book type In order to save materials, sulfuric acid paper is generally used instead of the issued film. According to the plate-making requirements, the original version is made after manual imposition. It is important to pay attention to this type of original: whether the film of the text is reversed; whether the density meets the requirements; whether the paper is curled or not.
Third, the print version of the control signal stripe print operator to work on exposure and development before each match test to determine the exposure time suitable for printing and proofing, development time, developer concentration. Method: First, ensure that the temperature of the developer and developer concentrate meet the development requirements. Then take a small PS plate and put the signal bar on it to expose the signal strip. Before the test, it is necessary to take into account the different service objects of the printing plate, and the exposure time test should also be adjusted to different degrees.
a. proofing version: the signal bar exposed by the development of four grayscale requirements sunburned half, 2% of the small outlets to the sun, 50% of the network to restore the basic accuracy, 80% of the outlets can not reduce the child% and clear edges of the outlets .
b. Printed version: After the signal bar has been exposed and developed, four levels of gray scales are required to get rid of one and a half grades, and 2% of the points on the Internet are sunburned. 50% and 80% of the communicative points are basically accurate and the edges of the nodes are also required to be clear and tidy. The main reason for the inconsistency between printing and proofing is to solve the problem of the mechanical performance of the proofer and the printing press, and to ensure that the printed matter and proofs are basically consistent in terms of tone, hue, or saturation. .
Fourth, understand the PS version of the performance indicators, the correct use of the PS version in the replacement of the new PS version or use the same manufacturer of the PS version and the batch number is different, because the photosensitive liquid ratio is not the same, the speed will be different, so exposure The time, the development time, and the developer concentration have to be changed accordingly. In the use of developer, in order to achieve the ideal development of the theater effect is best to use with the PS version of the matching developer, because the PS plate produced by different manufacturers have strong or weak anti-alkaline properties, if the alkaline weak PS plate with strong alkali The developer is developed, and no photosensitive layer of the photo-decomposed portion is severely affected, and the dots are smaller after the development and the image tone is lost. When the concentration of the developer is too large, not only the photosensitive layer is corroded, but also the oxide film of the printing plate is destroyed, so that the oleophilic performance of the printing plate is affected, and the printing durability of the PS plate is reduced. If the strong alkali-resistance PS plate is developed with a weakly alkaline developing solution, the phenomenon of incomplete development will occur. When the printing plate is dirty, the aluminum plate base will be subject to certain corrosion due to too long development time, affecting the PS plate. The effect of use.
Fifth, in addition to dirty, eraser, dry after the development of the PS version to remove dirt. Before removing dirt, the PS plate must be dried first, because most of the dirty areas are close to the image or text, and when the revised paste comes in contact with the PS plate, it is miscible with the surface of the plate and spreads to the surrounding water, which easily erodes the image. Or text, making the edges of the image blank, text lines lighter, or broken. In addition to dirty, use a brush tip to wipe a small amount of patch paste. Dirty spots need to be wiped cleanly and thoroughly removed in the shortest time, and then immediately rinse with water, to avoid the repair paste drying on the surface of the PS plate due to the long revision time. In addition, the revision time is too long to make the layout dirty. After repairing the dirt, it is necessary to timely wipe the protective layer on the PS plate. If the glue is not wiped off in time, the hydrophilic layer of the PS plate will be oxidized and the hydrophilicity will be reduced. When printing, the PS plate will be dirty. Correct squeegee method: Wipe the thin layer on the surface of the plate with a proper amount of the tarpaulin and apply evenly so that all hydrophilic layers are protected. After the squeegee is removed, the PS plate is dried and then protected.
Protection method: Each two PS plates are separated by a neutral moisture-proof paper, and the storage temperature is 25. Around C, relative humidity is about 60%.
If the quality of the printing plate is in a stable state for a long period of time, the printing staff must have the spirit of love and respect for the job, continuously accumulate experience in the work, and find a set of scientific standardized data suitable for printing and proofing, so that they can be handy when working to adapt to the current situation. This high-volume printing plate needs drying, which not only improves work efficiency but also ensures product quality.
2. Overprinting water (commonly known as water pressure). In the case that printing paper is not well controlled, in order to prevent the paper from elongating in printing, Fang Wang can be used to overprint the clean water first, so that the paper can be adapted to the printing requirements, and then the printing color can be started. This method does not solve overprinting. Have a certain role.
3. Control the printing plate surface moisture. Moisture in the printing plate. The moisture content of the printing plate is a key factor in controlling the stretching of the paper. The moisture of the plate is transmitted to the paper by a cloth, and the larger the plate surface moisture, the greater the expansion and contraction. Therefore, the smaller the control of the water content of the layout, the better, especially when printing 80 g of offset paper.
4. Pull the plate to lengthen the plate. Generally monochrome machine in the third, four-color printing process, two-color machine in the second printing process, the image of the paper has a longer stretch, resulting in overprinting is not allowed. This is because the PS plate material has good ductility and can be stretched by the plate-pulling machine so that the image on the plate plate and the image on the paper sheet can be evenly stretched to make the overprinting accurate.
At present, most domestic small and medium-sized printing and repairing companies generally do not have air-conditioning equipment. Most of the measures are to sprinkle some water around the machine to increase the air humidity. For non-network printing products that do not require high printing, the spray nozzle can be used to spray water directly on the paper edge and then printed on the machine; for the workshop with high humidity, the cut paper is best covered with a plastic cover to prevent moisture from becoming longer; If you are printing in the second printing, you can use the method of borrowing lines to compensate for the image's flexibility. In general, there are many processing methods that can solve the problem of over-printing and lead to overprinting. As long as the discussion and management of the printing process are strengthened, it can generally be solved.