Metal Packaging: Analysis of PS Plate Printing Problems

Metal Packaging: Analysis of PS Plate Printing Problems

Metal Packaging

Problems when printing plates are stored

1. The tape is too close to the image on the film, and the image pad is imaginary, and there is dirty tape.

When the puzzle is overlaid, the image overlays the image pad, and there are also dirty marks. Solution: Try to make the tape or patch base to maintain the proper distance, to avoid false. The dirt on the tape can be removed with a dirt remover or removed with a double exposure of a scattering film.

2. Dust, sand and other dirt on the PS plate cause the image to be dirty on the pad. Therefore, must carefully check the layout before the print, remove all the dust, do a good job of indoor health, the best is to print in a dust-free environment.

3. The glass is unclean during printing, and 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 of the plate-making machine is poor, the vacuum degree is insufficient, and the contact between the plate and the film is not true, resulting in stenosis. The treatment method is to overhaul the vacuum pump, and the vacuum degree should be kept at 0.08Mpa.

5. The air chamber of the printing machine is not well sealed and there is a leak, which makes the air intake inaccurate. Printing plates are often sunburned due to aging of the gums and should be replaced or glued.

6. The bottom of the printing machine is uneven, the suction is not uniform, and the partial film is in poor contact with the PS plate.

There are three ways to solve this problem. One is to check whether the bottom of the drying rack is uneven and to be flattened when uneven. The other is to select a porous wool liner to promote contact between the PS plate and the film. Third, the second suction method is used, ie, the first suction The gas stops releasing part of the gas and then inhales again, which can promote even and close contact between the PS plate and the film.

The film image is not dense enough to protect the image, and the image is exposed when it is printed. 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.

Blank part of printing plate

1. Underexposure results in incomplete decomposition of the sensitizer, incomplete development, and dirt on the blank part of the plate. If the printing plate is not printed on the machine, it can be rescued by the second development method, but this rescue is only applicable to the case of slight exposure, and severe cases cannot be saved. Determine the appropriate exposure time is the key to determine the quality of the printing plate, you can use continuous ash scale test, when the 0.45 density does not absorb ink, you can effectively solve the problem of under-exposed plate caused by dirty.

2. Underdeveloped, non-image sensitive film is not clean, resulting in dirt on the plate. its

Reasons: (1) Insufficient developer concentration; (2) Insufficient development time; (3) Low developer temperature, ideal developer temperature at 22±2°C.

3. The photosensitive layer of the PS plate is not evenly coated, and the thickness is not uniform. The degree of decomposition of the photosensitive resin is different when the plate is printed, causing scumming. If the photosensitive adhesive coated by the centrifugal baking machine is often radiated, the four sides are easy to get dirty. This situation can be rescued by local exposure or partial development.

4. Pick up ink improperly dirty, you can use turpentine oil to wash off the ink, re-ink.

5. Improper protection of glue, there is a leak in the place, resulting in dirty.

6. In addition to dirty method caused by the blank part of the dirty, the reasons are: (1) in addition to the amount of dirty agent; (2) insufficient time to repair dirty; (3) in addition to dirty agent on the printing plate is not timely rinse rub net.

7. The layout is blue and green. This version can be used to identify the dirty agent, can be removed when the dirt removal agent, it shows underdevelopment or underexposure; if you can not afford to remove, then the PS version is not completely sealed, belonging to the PS version of the body quality problems, and the sun The version is irrelevant and cannot be saved. Contact with the manufacturer for resolution.

8. The plate is light blue after development. This is due to the long storage time or coating sensitivity

When the temperature of the glue is too high, the aluminum oxide on the surface of the aluminum plate is oxidized with 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 darker circles, and becomes dirty after drying. The solution is to wash the lysate with a damp cloth immediately after it is dirty.

Plate printing does not absorb ink

1. Overexposure: (1) The original density is too low, and the graphic is transparent when printing; (2) The exposure time is too long; (3) The PS plate is stored improperly, leaks light, the storage period is too long, deterioration, bad ink absorption.

2. Over development: (1) developer is too concentrated, alkali is too strong; (2) development time is too long; (3) developer temperature is too high. According to the different characteristics of different manufacturers of different grades of the PS version of the sensitizer, the use of the appropriate formulation, matching ratio of the developer, test and control with the test strip, is an effective way to steadily control the development quality.

3. The protective glue will remain unchanged and not deteriorated. This is often the case in the summer months of high-temperature plum rain, where the glue is uneven and the road appears, causing no ink absorption.

Too light

1. Excessive exposure should reduce the exposure time;

2. Excessive development should reduce the development time;

3. The original density is insufficient, and the light is transmitted during the printing, so that the outlets are exposed to small changes; the pressure of the printing machine is insufficient or there are few gaskets, and the pressure or the gasket should be properly adjusted.

4. The PS grain is too coarse, and the mesh is damaged and becomes lighter.

Picture is too deep

The reason why the graphic is too deep is often the opposite of why the graphic is too light. The solution is the opposite.

1. Underexposure, exposure time should be increased;

2. Underdeveloped, should enhance the development;

3. The original non-graphic part has a high degree of fog, the transparency is not good, and the exposure time can be appropriately increased;

4. The pressure of the printing machine is large or the thickness of the pad is thick, and the pressure or pad should be properly reduced;

5. The ink is too thin and too soft. Processing method: Update the ink.