Fifth, printing plate failure and elimination method
Due to the problems in the process of plate making, the quality of printing plates has been degraded, and some of them can be found when checking the quality of printing plates, and some can be reflected in the printing process. In general, they can be divided into dirty printing plates and poor dot reproducibility. The color of the roasting plate is abnormal and the layout is poorly inked. All these defects related to the quality of platemaking are known as plate faults.
(a), the printing plate is dirty
1. Plates are dirty due to improper printing. Improper printing may cause the plate to become dirty. Improper printing operations include the following situations: The printing plate is not clean; the original plate is dusty or scratched; the original non-graphic part has fog; the original plate has adhesive tape marks or glue material, and underexposure Wait.
The way to eliminate this kind of failure is to wipe the glass of the printing plate before the printing; clean the dust on the original plate, and repair the defects on the original plate; remove the marks and glue left on the original plate by the adhesive tape, and even return it. The unqualified original was remade. It is difficult to remove the plate due to underexposure. If the contamination is not serious, you can use the diffuser to supplement the exposure. The position of the light source should be moved during exposure. The developer concentration can also be increased and then developed. However, the more concentrated alkaline developer also dissolves the photo-degradable photosensitive layer, resulting in a decrease in the printing durability of the PS plate. If the dirt is quite serious, the above remedy does not solve the problem. The fundamental solution is to avoid underexposure when the printing plate is exposed. For this reason, every purchase of a batch of PS plates requires an exposure test to accurately find the exposure amount or exposure time, and to make the exposure as large as possible without causing a reduction in the dot area percentage.
2. Improper development caused by plate contamination. During the development process, the following causes may cause the printing plate to be dirty: the temperature of the developer is too low, the development time is too short, the proportion of each component in the developer is not appropriate, the developer becomes fatigued or even fails; during development, a poor sponge is used to wipe or the plate surface The wipe is not clean enough, the water is not rinsed thoroughly; the misalignment of the automatic developer, such as poor developer circulation, unstable temperature, etc.
For the positive PS version, the under-exposure and the plate failure caused by developer failure are the same. In order to distinguish between the two causes of the printing plate dirty, you can replace the developer after the development, the development is still not sufficient, then the cause of the printing plate is due to lack of exposure; if the normal development, it will cause the plate is dirty The cause of contamination is developer failure.
The method to eliminate this kind of failure is to check the temperature and developing time of the developer and adjust it to the standard that should be reached; adjust the developer according to the formula given by the manufacturer, and update the clear liquid in time; in the development, the layout should be fully washed with water and used. High-quality sponge thoroughly wipe the layout; overhaul automatic development machines. It is best to use a closed automatic processor with two development chambers for development. When the exposed PS plate passes through the first development chamber, the light-receiving photosensitive layer together with most of the dye is dissolved. When entering the second development chamber, only a very small amount of the photosensitive layer and the pigment dissolve, ensuring the second development. The color of the developer in the chamber is substantially constant over a long period of time, which can prolong the life of the developer and facilitate the observation of the developer.
3. In addition to dirty processing caused by the dirty plate. In addition to the dirty process, the operation is not careful, the dirt should be removed, in addition to the lack of dirty fluid, the use of liquid for a short time, the use of dirty liquid for a long time, resulting in incomplete dirty; after the use of dirty fluid On the layout, etc., it may cause the printing plate to be dirty.
The method to eliminate this kind of failure is to carefully remove the dirty operation and apply the brush to remove the dirty liquid; the dirty time should be maintained at 20 to 30 seconds; the dirty liquid should be tightly closed after use; the layout should be used after the dirty treatment. Rinse thoroughly.
4. Improper sizing caused the layout to be dirty. In Shengshang operation, a low concentration of glue is used, oxidation occurs in non-image areas, uneven, thick or streaky glue, and printing with unprocessed plates may cause printing plates. Dirty.
The method to eliminate this kind of failure is to increase the concentration of the glue solution and it should not be less than 5°Be'; the glue should be fully coated; the plate after gluing, the plate surface is completely dried and then printed on the machine.
(B), poor reproducibility of outlets
The reproducibility of the outlets is not good. The phenomenon of “virtual halo†(that is, the periphery of the outlets is not smooth, the outline is blurred and unclear), the network outlets are reduced or lost, and the outlets are expanded. The poor reproducibility of the dots may lead to a drop in the sharpness of the image, a change in the tone, and the like.
1. Vignetting occurs at outlets. The main reason for the appearance of virtual halo at the outlets is the failure of the printing machine. For example, the stencil machine is not sufficiently pumped, the degree of vacuum is low, or the glass plate and the printing plate surface cannot be closely adhered when the printing plate is installed. Since the enlarging process has a scattering effect of air on light, a dot is generated. Halo phenomenon.
The method to eliminate this kind of failure is to promptly repair the printing machine, ensure that the cosmic system is in good working condition, and the air pumping is adequate. The rubber seal of the printing plate is well-elastic and closed. When printing, verify that the printing plate is closely attached to the original plate. Immediately after, you can open the light source to expose; when you collage the original, you must repair the burr on the original side, stick the adhesive tape away from the image as far as possible, or make the entire original to ensure the original and printing plate. Fit close.
2. The network is reduced or lost. The main reasons for the reduction or loss of outlets are that the original density is too low, the original thinning is excessive, the exposure time is too long, the developer concentration, temperature is too high, and the development time is too long.
To eliminate this failure, the original plate with an image density lower than 1.5 must be re-produced; the optimal exposure time should be obtained by trial exposure and used to guide the exposure operation; and the concentration and temperature of the developer solution should be adjusted. Develop according to the standard development conditions of the specification.
3. Network expansion. The main reason for dot gain is that the developer concentration and temperature are too low, the development time is too short, and the developer ages.
The method to eliminate this kind of trouble is to adjust the concentration and temperature of the developer and develop according to the standard development conditions of the standard according to the optimum exposure time.
&n
Due to the problems in the process of plate making, the quality of printing plates has been degraded, and some of them can be found when checking the quality of printing plates, and some can be reflected in the printing process. In general, they can be divided into dirty printing plates and poor dot reproducibility. The color of the roasting plate is abnormal and the layout is poorly inked. All these defects related to the quality of platemaking are known as plate faults.
(a), the printing plate is dirty
1. Plates are dirty due to improper printing. Improper printing may cause the plate to become dirty. Improper printing operations include the following situations: The printing plate is not clean; the original plate is dusty or scratched; the original non-graphic part has fog; the original plate has adhesive tape marks or glue material, and underexposure Wait.
The way to eliminate this kind of failure is to wipe the glass of the printing plate before the printing; clean the dust on the original plate, and repair the defects on the original plate; remove the marks and glue left on the original plate by the adhesive tape, and even return it. The unqualified original was remade. It is difficult to remove the plate due to underexposure. If the contamination is not serious, you can use the diffuser to supplement the exposure. The position of the light source should be moved during exposure. The developer concentration can also be increased and then developed. However, the more concentrated alkaline developer also dissolves the photo-degradable photosensitive layer, resulting in a decrease in the printing durability of the PS plate. If the dirt is quite serious, the above remedy does not solve the problem. The fundamental solution is to avoid underexposure when the printing plate is exposed. For this reason, every purchase of a batch of PS plates requires an exposure test to accurately find the exposure amount or exposure time, and to make the exposure as large as possible without causing a reduction in the dot area percentage.
2. Improper development caused by plate contamination. During the development process, the following causes may cause the printing plate to be dirty: the temperature of the developer is too low, the development time is too short, the proportion of each component in the developer is not appropriate, the developer becomes fatigued or even fails; during development, a poor sponge is used to wipe or the plate surface The wipe is not clean enough, the water is not rinsed thoroughly; the misalignment of the automatic developer, such as poor developer circulation, unstable temperature, etc.
For the positive PS version, the under-exposure and the plate failure caused by developer failure are the same. In order to distinguish between the two causes of the printing plate dirty, you can replace the developer after the development, the development is still not sufficient, then the cause of the printing plate is due to lack of exposure; if the normal development, it will cause the plate is dirty The cause of contamination is developer failure.
The method to eliminate this kind of failure is to check the temperature and developing time of the developer and adjust it to the standard that should be reached; adjust the developer according to the formula given by the manufacturer, and update the clear liquid in time; in the development, the layout should be fully washed with water and used. High-quality sponge thoroughly wipe the layout; overhaul automatic development machines. It is best to use a closed automatic processor with two development chambers for development. When the exposed PS plate passes through the first development chamber, the light-receiving photosensitive layer together with most of the dye is dissolved. When entering the second development chamber, only a very small amount of the photosensitive layer and the pigment dissolve, ensuring the second development. The color of the developer in the chamber is substantially constant over a long period of time, which can prolong the life of the developer and facilitate the observation of the developer.
3. In addition to dirty processing caused by the dirty plate. In addition to the dirty process, the operation is not careful, the dirt should be removed, in addition to the lack of dirty fluid, the use of liquid for a short time, the use of dirty liquid for a long time, resulting in incomplete dirty; after the use of dirty fluid On the layout, etc., it may cause the printing plate to be dirty.
The method to eliminate this kind of failure is to carefully remove the dirty operation and apply the brush to remove the dirty liquid; the dirty time should be maintained at 20 to 30 seconds; the dirty liquid should be tightly closed after use; the layout should be used after the dirty treatment. Rinse thoroughly.
4. Improper sizing caused the layout to be dirty. In Shengshang operation, a low concentration of glue is used, oxidation occurs in non-image areas, uneven, thick or streaky glue, and printing with unprocessed plates may cause printing plates. Dirty.
The method to eliminate this kind of failure is to increase the concentration of the glue solution and it should not be less than 5°Be'; the glue should be fully coated; the plate after gluing, the plate surface is completely dried and then printed on the machine.
(B), poor reproducibility of outlets
The reproducibility of the outlets is not good. The phenomenon of “virtual halo†(that is, the periphery of the outlets is not smooth, the outline is blurred and unclear), the network outlets are reduced or lost, and the outlets are expanded. The poor reproducibility of the dots may lead to a drop in the sharpness of the image, a change in the tone, and the like.
1. Vignetting occurs at outlets. The main reason for the appearance of virtual halo at the outlets is the failure of the printing machine. For example, the stencil machine is not sufficiently pumped, the degree of vacuum is low, or the glass plate and the printing plate surface cannot be closely adhered when the printing plate is installed. Since the enlarging process has a scattering effect of air on light, a dot is generated. Halo phenomenon.
The method to eliminate this kind of failure is to promptly repair the printing machine, ensure that the cosmic system is in good working condition, and the air pumping is adequate. The rubber seal of the printing plate is well-elastic and closed. When printing, verify that the printing plate is closely attached to the original plate. Immediately after, you can open the light source to expose; when you collage the original, you must repair the burr on the original side, stick the adhesive tape away from the image as far as possible, or make the entire original to ensure the original and printing plate. Fit close.
2. The network is reduced or lost. The main reasons for the reduction or loss of outlets are that the original density is too low, the original thinning is excessive, the exposure time is too long, the developer concentration, temperature is too high, and the development time is too long.
To eliminate this failure, the original plate with an image density lower than 1.5 must be re-produced; the optimal exposure time should be obtained by trial exposure and used to guide the exposure operation; and the concentration and temperature of the developer solution should be adjusted. Develop according to the standard development conditions of the specification.
3. Network expansion. The main reason for dot gain is that the developer concentration and temperature are too low, the development time is too short, and the developer ages.
The method to eliminate this kind of trouble is to adjust the concentration and temperature of the developer and develop according to the standard development conditions of the standard according to the optimum exposure time.
&n
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