Failure Analysis of PS Plates in Printing Production
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First, the printing plate is imaginary
In the actual printing, the problem of the printing and printing of the printing plate is mainly caused by the plate-making operation, and there are many reasons. According to the reasons, it is divided into the following categories:
1. A virtual version caused by dirt
Reasons: 1 The printing machine glass, the printing plate film, the imprinting film base, the printing plate surface is attached with foreign matter or dirt; 2 between the printing film and the imprinting substrate, the printing plate and the film are mixed with foreign matter (such as hair silk) Etc.); 3 printing time is too long, the printing plate, the printing film produces static electricity, adsorption of dust during the printing process; 4PS plate surface has medicine, white spots and so on.
2, the virtual version caused by the film
Reason: 1 The density of the film is not enough (should be above 3.5); 2 The fog of the imprinted film is too high; 3 The film is not properly tiled, the outer edge of the film is too narrow (should be more than 3cm), and the imposition is too crowded ( 0.5-1mm), causing arching, etc.; 4 scotch tape of the imposition film is away from the image titanium (should be more than 7mm away) or pasted too thick; 5 film is reversed when printing.
3, the virtual version caused by insufficient vacuum pumping
Reasons: 1 poor performance of vacuum pump; 2 sealing ring of the printing machine, air pipe leakage; 3 sealing rubber ring aging deformation; 4 printing machine rubber air cushion is not flat or aging; 5 vacuum pumping indicator has problems, pointer to the end Actually, it is not pumped; 6 film or PS plate has creases, etc.; 7 When Newton's ring, large air retention zone, and dust and debris are found, it is necessary to perform secondary pumping in time.
4. The virtual version caused by exposure and over development
Reason: 1 exposure time is too long; 2 before exposure (during punching) or after exposure to develop light before development; 3 developer temperature is too high, the concentration is too large; 4 development time is too long; 5 developer replenishment is too much.
Second, the layout is dirty
1, the upper body caused by the plate material
The 1ps version of the base sand is too shallow, and the non-image part caused by the small amount of water storage is dirty. Solution: When printing with such plates, the moisture of the plate should be increased or an appropriate amount of surfactant should be added to the dampening solution to enhance the hydrophilicity of the non-image parts of the plate.
The 2ps version of the base oxide film is thin and brittle, can not withstand the friction in printing and is worn away, the sand is bare and smoothed, and the new water performance is reduced. Solution: Re-replace the plate.
3ps version sealing hole is not sufficient, the plate remains unsealed micropores, the plate has large adsorption capacity, easy to adsorb dust and other impurities; or the sealing liquid contains calcium particles or other impurity ions, which produces calcium silicate and other incompatible salts, polluting the layout. Solution: Develop with developer solution of calcium silicate as the main agent, and seal the plate twice during development.
The 4ps version of the photosensitive layer is too thick, the normal exposure time can not be completely decomposed, and the photosensitive glue remains on the inner wall of the sand, which makes the non-image part lipophilic enhanced. Solution: Extend the exposure time to completely decompose the adhesive layer.
2, the PS version of the fog caused by the dirty
Due to improper storage of the ps version or improper illumination of the interior of the printing plate, the ps version is fogged, resulting in the non-image portion of the printing plate being hydrophilic and dirty.
Handling: Protect the ps version from the light, and work under the safety light when printing.
3, the print on the dirty
1 The upper part caused by improper exposure operation. It is mainly caused by the adhesion of dirt on the large glass or film, which hinders the transmission of light, or the film formed by the tape and the border on the original film. Solution: Before the operation of the former, the part should be inspected in detail, trimmed or cleaned with a cleaning agent; the latter can be removed by removing the dirt when the area is small, and the double exposure method can be used for the double exposure method when the area is large.
2 the upper organs caused by insufficient exposure. Different performance ps version of the photographic performance is not the same, so the exposure time is different. The exposure efficiency of the photosensitive layer is gradually decreasing as the photochemical reaction of the light is irradiated. When the power of the light source is insufficient, the inner part of the photosensitive layer is not completely decomposed, and it will be dirty. Therefore, each batch of ps version should measure the exposure, adjust the exposure time in time, and regularly check the effective power and voltage stability of the light source.
3 development is not transparent caused by the upper organs. Mainly due to fatigue failure of the developer, insufficient concentration, too low developer temperature or insufficient development time.
4 When the developer is prepared, the amount of strong alkali such as sodium hydroxide is too large, the developer is too alkaline, the oxide film is etched, the substrate is bare, and the hydrophilic property of the non-image portion of the printing plate is lowered and dirty. Solution: Add an appropriate amount of inhibitors such as potassium chloride or sodium phosphate to the developer.
4, altered on dirty
1 altered parts on the dirty
Cause: The correction fluid has deteriorated; the moisture of the layout has not been dried during the modification; the alteration is not sufficient; the modification time is too long.
Solution: It is forbidden to change the printing plate with the altered coating fluid. The correction fluid should be properly stored when not in use.
2 stained around the affected area
Cause: insufficient exposure or insufficient development, residual photoresist layer; residual around the altered part, adhere to the photosensitive layer dissolved by the correction solution; before the soil modification of the layout, remove the dirt, to dry the layout, the correction solution Invaded around the corrections department.
Third, poor ink
1. Wipe the protective glue improperly
1 Ink problem at the beginning of printing
The specified protective glue is not used; the protective glue is too thick; the glue is uneven; the plate touches the strong light after the board is wiped, the plate runs, the lipophilicity of the graphic part is lowered; the protective glue is too thick and too much.
2 Ink problems in the middle of printing
Cause: There is too much glue in the dampening solution.
Solution: After using the PS version of the cleaning agent, it must be rinsed with water.
2, improper alteration operation
Reason: Before the printing plate is changed, the plate water is wiped dry, and the correction fluid invades the surrounding printing plate, so that the image of the part is corroded and lost.
Solution: The water in the layout should be thoroughly wiped before the alteration; the coating protection is carried out later.
3, PS version of the photosensitive adhesive layer peeled off
Reason: The main voice board is protected and stored poorly. In addition, if the developer concentration is too high, a small portion of the plate image may be revealed, resulting in high peeling and peeling of the photosensitive layer.
Solution: Do not rub the PS layout when transporting the media; the developer concentration should be moderate.
Fourth, the printing plate is resistant to printing (disappearance)
The location of the PS version of the printing force depends not only on the plate itself, but also on every aspect of the printing and printing process. There are many factors that affect the printing durability of printing plates in actual printing.
1, the plate
The sand is shallow; the oxide layer is thin and uneven.
2, plate making
Run before exposure or development; overexposure; overexposure; deterioration of the baking paste, too high temperature of the baking plate, too long.
3, printing
A strong plate cleaning agent or roller cleaning agent is used; the printing pressure is too large; the plate is not flat with the blanket; the plate roller is tight and not tight; the plate rubber roller and the blanket are aged.
4, dampening solution
The concentration of the fountain solution is too large to erode the plate.
5, printing paper
The printed paper is rough, powdery, and lint.
6, ink
The ink layer is too thick; the ink particles are coarse.