Home-made liquid formulations positive PS version of the common problem analysis two

Second, PS version printing quality problems

Shaiban is a "bridge" process in platemaking and printing. Its status is very important. Although the PS plate is easier to handle and the quality is better than that of the flat plate, it often causes troubles in the manufacture of the PS plate. The use of PS version is not satisfactory.

1. The image is imaginary and dirty. 1 The adhesive tape on the film is too close to the image, the image pad is imaginary, and there is dirty printing on the adhesive tape; when the imposition is made, the bases overlap, the image pad is imaginary, and sometimes there are dirty marks. Solution: Try to keep the proper distance when the tape or imposition sheet is overlapped. Adhesive smears can be removed with a dirt remover or removed with a diffuse film double exposure method. 2 Dust, sand, and other dirt are deposited on the PS plate during printing, causing the image to become dirty on the pad. Therefore, you must carefully check the layout before the printing, remove all the dust, do a good job of indoor health, the best is to print in a dust-free environment. 3 When printing, the glass is not clean. There are glue points to dirty the image pad. According to the operating process requirements, the glass must be wiped clean before printing, otherwise it is not allowed to print. 4 The performance of the vacuum pump in the printing machine is poor, and the degree of vacuum is not enough. The contact between the plate and the film is not real, resulting in blemishes. The treatment method is to overhaul the vacuum pump, and the vacuum degree must be more than 0.08 MPa. 5 The air chamber of the printing machine is not well sealed and there is a leak, which makes inhalation inaccurate. Printing plates are often sunburned due to aging of the gums and should be replaced or glued. 6 The bottom of the printing plate is uneven and the suction is not uniform. The contact between the partial film and the PS plate is not true. There are three ways to solve this problem: First, check if the bottom of the printing plate is uneven and flatten it when uneven. Second, select the porous wool pad to promote the contact between the PS plate and the film. Third, use the second suction method, that is, the first time. Suction stops releasing part of the gas, and then inhales again, which promotes close and even contact between the PS plate and the film. 7 The density of the film image is not enough. When it is printed, it is lightly penetrated, and the image is exposed, causing the image to become imaginary without ink absorption. In principle, printing cannot be done when the image density is less than the standard, and it must be re-plated. Sometimes you can try to pull the light far away, so you can reduce or avoid sun drying to a certain extent.

2. The blank part of the plate is dirty. 1 underexposure, resulting in incomplete decomposition of the sensitizer, incomplete removal of the development, causing the blank part of the dirty. If the printing plate is not printed on the machine, it can be rescued by the second development method, but this phenomenon is only applicable to underexposure situations, and severe cases cannot be saved. Determining the proper exposure time is the key to determining the quality of the printing plate. With a continuous ash grading test, the 0.45 densitizing without ink absorption will effectively solve the problem of underprinting caused by printing plates. 2 Insufficient development, non-photosensitive film removal is not clean, resulting in dirty plates. The reasons are: insufficient developer concentration; insufficient development time; low developer temperature; ideal development temperature is 22±2°C; 3 PS photosensitive layer coating is uneven, the thickness is inconsistent, the degree of decomposition of the photosensitive resin when the printing plate is different, causing the upper dirt. If the photosensitive adhesive coated with a centrifugal baking plate machine is often radiated, and the four-sided rubber is easy to be dirty, it can be rescued by local exposure or partial development. 4 Improperly used ink on the dirty, can use turpentine to wash off the ink and re-extract the ink. 5 Wipe protection glue is improper, there is a leak in the place, resulting in dirty. 6 In addition to dirty methods cause blank parts dirty. The reason is that: in addition to the amount of dirty agent; repair time is not sufficient; in addition to the dirty agent on the printing plate is not timely rinse and wipe. 7 layout is blue and green. This version can be used in addition to dirty agent to identify, can be removed in addition to dirty agent, it shows underdeveloped or underexposure; if you can not get rid of, then the PS version is not completely sealed, belonging to the quality of the PS version of the body, and The print version is irrelevant and cannot be salvaged. Contact with the manufacturer to resolve it. 8 The plate is light blue after development. This is due to the fact that the plate has been stored for a long time or the temperature at the time of applying the photo resist is too high, which causes oxidation of the aluminum oxide on the surface of the aluminum plate and the photosensitive layer. It is insoluble in the developer and does not cause dinging under normal conditions. It only appears dirty when using dirt remover. This is because the dirt remover dissolves in a bluish color, accumulates in a more color-preserving circle, and becomes dirty after drying. The solution is: wipe the lysate with a damp cloth immediately after it is dirty, and it will not be dirty.

3. Printing plate text does not absorb ink. 1 overexposure: the original density is too low, the photo transmission light when printing; exposure time is too long; PS version is not properly preserved, light leakage, storage period is too long, deterioration, bad ink absorption. 2 Over-developed; developer too concentrated, too strong alkaline; too long development time; developer temperature too high. According to the different characteristics of different manufacturers of different brands of PS version of the sensitizer, the use of appropriate formulations, matching ratio of the developer, with the test strip detection and control, is an effective way to steadily control the development of quality. 3 The protective glue becomes acid and deteriorates, which often occurs during the high-temperature rainy season. Dirty and dirty, rubber road, causing no ink.

4. The picture is too light. 1 Excessive exposure should reduce exposure time. 2 Excessive development should reduce the development time. 3Insufficient density of the original plate, transmission of light when printing, so that the network damage is reduced. 4 The press should have insufficient pressure or gaskets. Adjust the pressure or gasket properly. 5 PS version of the sand is too thick, the net damage becomes smaller and lighter.

5. The graphic is too deep. The reason why the graphic is too deep is often the opposite of the reason that the pattern is too shallow, and the solution is the opposite. 1 Underexposure, exposure time should be increased. 2 Underdeveloped, should increase the development time. 3 The original non-graphic part has a high degree of fog, and the transparency is not good, and the exposure time can be appropriately increased. 4 The pressure of the printing press or the thickness of the pad should be reduced appropriately. 5 The ink is too thin and too soft. Processing method: Update the ink.