Four, printing plate faults and troubleshooting methods
Due to problems in the plate-making process, the quality of the printing plate is reduced. Some can be found when checking the quality of the printing plate, and some can be reflected in the printing. They can be roughly divided into dirty printing plates, poor dot reproducibility, Abnormal color of the roasted plate and poor ink on the plate, etc. All these defects related to the quality of plate-making are known as printing plate failure.
1. The printing plate is dirty
1. Dirty printing plates caused by improper printing operation. Improper printing operation may cause the printing plate to become dirty. There are several cases of improper printing operation: the printing frame is not clean; there is dust or scratches on the original version; there is fog in the non-graphic part of the original version; there are traces of adhesive tape or paste material on the original version, and insufficient exposure Wait.
The way to eliminate this kind of trouble is to wipe the glass of the printing plate clean before printing; remove the dust on the original plate, repair the damaged dots on the original plate; remove the traces and glue left by the adhesive tape on the original plate, and even return it The unqualified original version shall be re-produced. For the dirty printing plate caused by underexposure, it is difficult to remove. If the dirt is not very serious, you can use the diffuser for supplementary exposure. The position of the light source should be moved during the exposure; you can also increase the concentration of the developer and perform another development. However, the thicker alkaline developer will also dissolve the photosensitive layer that has not been decomposed by light, which will lower the PS printing durability. If the dirt is quite serious, the above remedies will not solve the problem. The fundamental solution is to avoid the disadvantage of 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 maximize the exposure amount without causing a reduction in the percentage of the dot area.
2. Dirty printing plates caused by improper development processing. During the development process, the following reasons may cause the printing plate to become 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 suitable, the developer is fatigued or even fails; use a poor quality sponge to wipe or face the plate during development The wiping is not clean enough, and the water rinse is not complete; the automatic developing machine is out of order, such as poor circulation of the developing solution, unstable temperature, etc.
For positive-type PS plates, the phenomenon of underexposure and dirty printing plates caused by developer failure is the same. In order to distinguish the two causes of printing plate contamination, the developer can be replaced after developing. If the development is still insufficient, it means that the cause of the printing plate contamination is underexposure; if the development is normal, it means that the printing plate is dirty The cause of contamination is the failure of the developer.
The way to eliminate this kind of trouble is to check the temperature and development time of the developer, and adjust to the standard that should be reached; adjust the developer according to the formula given by the manufacturer, and update the developed solution in time; the plate during the development should be fully washed with water and used Wipe the layout thoroughly with high-quality sponge; overhaul the automatic developing machine, etc. Preferably, a closed automatic developing machine having two developing chambers is used for development. When the exposed PS plate passes through the first developing chamber, most of the light-sensitive photosensitive layer and dye are dissolved. When it enters the second developing chamber, only a small amount of photosensitive layer and pigment are dissolved, which ensures the second development The color of the developer in the chamber is basically unchanged for a long period of time, which can not only extend the life of the developer, but also facilitate the observation of the developer.
3. The printing plate is dirty due to improper decontamination. In the process of decontamination, the operation is not careful, the dirt that should be removed is missed, the amount of decontamination fluid is insufficient, the use time is short, and the decontamination fluid is used for a long time, resulting in incomplete decontamination; the decontamination fluid is dried up after use On the plate, etc., it may cause the printing plate to be dirty.
The way to eliminate this kind of trouble is that the decontamination should be done carefully. Use a brush to dilute the decontamination solution to remove the decontamination; the decontamination time should be kept at 20 to 30s; the decontamination solution should be covered tightly after use; the plate should be used after decontamination Rinse thoroughly.
4. The plate surface is dirty due to improper gluing operation. In the Shangsheng operation, the use of low-concentration glue, oxidation of non-image parts, uneven application of glue, too thick or streaked, and printing with wet printing plates will cause printing plates Dirty.
The way to eliminate this kind of trouble is to increase the concentration of the glue solution, which should be no less than 5 ° Be '; apply the glue solution thoroughly; the plate after the glue is applied, and the plate surface is thoroughly dried before printing on the machine.
Second, the reproducibility of the outlets is not good
The reproducibility of the dots is not good, which is manifested in the phenomenon of "virtual halo" (that is, the periphery of the dots is not smooth and the outline is blurred and unclear), the dots are reduced or lost, and the dots are enlarged. Poor dot reproducibility may cause disadvantages such as reduced image clarity and changes in tone.
1. The halo phenomenon appeared in the outlets. The main reason for the halo phenomenon at the outlets is the malfunction of the printing machine. For example, the plate-making machine has insufficient air extraction and low vacuum, or when the plate is installed, the glass plate and the plate surface cannot be well-adhered. Due to the scattering effect of air on the light during the version increase process, dots are generated. Halo phenomenon.
The way to eliminate this kind of trouble is to maintain the plate-making machine in time to ensure that the space-time system is in good working condition, with sufficient suction, and the rubber seal of the plate-making frame has good elasticity and effective sealing; The light source can be turned on only after exposure; when tiling the original, the burrs on the edges of the original should be repaired, the adhesive tape should be attached as far as possible from the image, or the entire original should be made to ensure the original and the printing plate Close fit.
2. The outlets are reduced or lost. The main reasons for the reduction or loss of dots are that the density of the original plate is too low, the original plate is too thin, the exposure time is too long, the concentration and temperature of the developer are too high, and the development time is too long.
The method to eliminate this kind of trouble is that the original plate with image density lower than 1.5 and the original plate with excessive thinning must be re-made; the best exposure time is obtained through trial exposure and used to guide the exposure operation; adjust the concentration and temperature of the developer, Develop according to the standard development conditions.
3. Expanded outlets. The main reason for the dot expansion is that the concentration and temperature of the developer are too low, the development time is too short, and the developer is aging.
The way to eliminate this kind of trouble is to adjust the concentration and temperature of the developing solution, and develop according to the standard standard developing conditions according to the optimal exposure time.
3. Abnormal color of baking plate and poor ink on the plate
The film-forming agent of the photosensitive layer of the positive-type PS plate is m-cresol formaldehyde resin. After baking, the normal color is reddish brown. If the plate surface is tea green or dark green, it means that the baking temperature is too low or the baking time is too long. Short, you should increase the baking temperature or extend the baking time until the color of the plate reaches red brown; if the plate is dark brown, it means that the baking temperature is too high or the baking time is too long, the resin in the photosensitive layer is partially carbonized, the color The deeper, the more carbonized resin, the lower the durability of the printing plate, the baking temperature should be reduced or the baking time should be shortened; if the blank part of the plate surface after baking is light red, it is due to insufficient development of the plate The photosensitive layer can be gently wiped with pumice powder, but it can't be remedied when the area is large.
Poor inking of the plate surface is mostly caused by improper operation in the process of printing, developing, removing dirt and gluing.
Improper printing operations include: scratches, dust, foreign objects on the printing plate glass, insufficient density of the original image part, overexposure, incorrect shading operation, etc. These may cause poor ink on the plate surface. The method of elimination is: remove the dust and foreign objects on the glass of the plate, remake the original plate to increase the density of the original plate, print according to the optimal exposure time, check whether the shading paper is shading tight and improve the shading method.
Improper development and decontamination include: developing temperature is too high, developing time is too long, washing is not complete, the developer remains on the image, the decontamination solution splashes from the brush during decontamination, and the image part is touched when wiping the decontamination solution, The excessively wet decontamination solution on the plate surface spreads to the image part, and the cleaning is not thorough after the victory, etc., which may cause poor ink on the plate surface. The method of elimination is: check the temperature and development time of the developer, and adjust to meet the standard; re-develop the developer, and conduct trial development; the dirt removal operation should be careful, such as the brush is not dipped in the dirt, the layout can not be used by hand Touch, after the moisture on the plate surface is dry, remove the dirty liquid. After removing the dirt, thoroughly wash the plate surface with water.
Improper sizing includes: incorrect sizing method, uneven coating or excessive thickness, excessive drying temperature of the adhesive layer, excessive content of gum arabic (or CMC) in the glue solution, etc., which may cause the layout Bad ink. The exclusion methods are: use the correct glue application method, apply glue evenly and do not make the glue layer too thick. Dry the glue layer at an appropriate temperature to reduce the glue content in the glue and make the glue thick. The degree is kept at 5 ° Be '.
Due to problems in the plate-making process, the quality of the printing plate is reduced. Some can be found when checking the quality of the printing plate, and some can be reflected in the printing. They can be roughly divided into dirty printing plates, poor dot reproducibility, Abnormal color of the roasted plate and poor ink on the plate, etc. All these defects related to the quality of plate-making are known as printing plate failure.
1. The printing plate is dirty
1. Dirty printing plates caused by improper printing operation. Improper printing operation may cause the printing plate to become dirty. There are several cases of improper printing operation: the printing frame is not clean; there is dust or scratches on the original version; there is fog in the non-graphic part of the original version; there are traces of adhesive tape or paste material on the original version, and insufficient exposure Wait.
The way to eliminate this kind of trouble is to wipe the glass of the printing plate clean before printing; remove the dust on the original plate, repair the damaged dots on the original plate; remove the traces and glue left by the adhesive tape on the original plate, and even return it The unqualified original version shall be re-produced. For the dirty printing plate caused by underexposure, it is difficult to remove. If the dirt is not very serious, you can use the diffuser for supplementary exposure. The position of the light source should be moved during the exposure; you can also increase the concentration of the developer and perform another development. However, the thicker alkaline developer will also dissolve the photosensitive layer that has not been decomposed by light, which will lower the PS printing durability. If the dirt is quite serious, the above remedies will not solve the problem. The fundamental solution is to avoid the disadvantage of 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 maximize the exposure amount without causing a reduction in the percentage of the dot area.
2. Dirty printing plates caused by improper development processing. During the development process, the following reasons may cause the printing plate to become 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 suitable, the developer is fatigued or even fails; use a poor quality sponge to wipe or face the plate during development The wiping is not clean enough, and the water rinse is not complete; the automatic developing machine is out of order, such as poor circulation of the developing solution, unstable temperature, etc.
For positive-type PS plates, the phenomenon of underexposure and dirty printing plates caused by developer failure is the same. In order to distinguish the two causes of printing plate contamination, the developer can be replaced after developing. If the development is still insufficient, it means that the cause of the printing plate contamination is underexposure; if the development is normal, it means that the printing plate is dirty The cause of contamination is the failure of the developer.
The way to eliminate this kind of trouble is to check the temperature and development time of the developer, and adjust to the standard that should be reached; adjust the developer according to the formula given by the manufacturer, and update the developed solution in time; the plate during the development should be fully washed with water and used Wipe the layout thoroughly with high-quality sponge; overhaul the automatic developing machine, etc. Preferably, a closed automatic developing machine having two developing chambers is used for development. When the exposed PS plate passes through the first developing chamber, most of the light-sensitive photosensitive layer and dye are dissolved. When it enters the second developing chamber, only a small amount of photosensitive layer and pigment are dissolved, which ensures the second development The color of the developer in the chamber is basically unchanged for a long period of time, which can not only extend the life of the developer, but also facilitate the observation of the developer.
3. The printing plate is dirty due to improper decontamination. In the process of decontamination, the operation is not careful, the dirt that should be removed is missed, the amount of decontamination fluid is insufficient, the use time is short, and the decontamination fluid is used for a long time, resulting in incomplete decontamination; the decontamination fluid is dried up after use On the plate, etc., it may cause the printing plate to be dirty.
The way to eliminate this kind of trouble is that the decontamination should be done carefully. Use a brush to dilute the decontamination solution to remove the decontamination; the decontamination time should be kept at 20 to 30s; the decontamination solution should be covered tightly after use; the plate should be used after decontamination Rinse thoroughly.
4. The plate surface is dirty due to improper gluing operation. In the Shangsheng operation, the use of low-concentration glue, oxidation of non-image parts, uneven application of glue, too thick or streaked, and printing with wet printing plates will cause printing plates Dirty.
The way to eliminate this kind of trouble is to increase the concentration of the glue solution, which should be no less than 5 ° Be '; apply the glue solution thoroughly; the plate after the glue is applied, and the plate surface is thoroughly dried before printing on the machine.
Second, the reproducibility of the outlets is not good
The reproducibility of the dots is not good, which is manifested in the phenomenon of "virtual halo" (that is, the periphery of the dots is not smooth and the outline is blurred and unclear), the dots are reduced or lost, and the dots are enlarged. Poor dot reproducibility may cause disadvantages such as reduced image clarity and changes in tone.
1. The halo phenomenon appeared in the outlets. The main reason for the halo phenomenon at the outlets is the malfunction of the printing machine. For example, the plate-making machine has insufficient air extraction and low vacuum, or when the plate is installed, the glass plate and the plate surface cannot be well-adhered. Due to the scattering effect of air on the light during the version increase process, dots are generated. Halo phenomenon.
The way to eliminate this kind of trouble is to maintain the plate-making machine in time to ensure that the space-time system is in good working condition, with sufficient suction, and the rubber seal of the plate-making frame has good elasticity and effective sealing; The light source can be turned on only after exposure; when tiling the original, the burrs on the edges of the original should be repaired, the adhesive tape should be attached as far as possible from the image, or the entire original should be made to ensure the original and the printing plate Close fit.
2. The outlets are reduced or lost. The main reasons for the reduction or loss of dots are that the density of the original plate is too low, the original plate is too thin, the exposure time is too long, the concentration and temperature of the developer are too high, and the development time is too long.
The method to eliminate this kind of trouble is that the original plate with image density lower than 1.5 and the original plate with excessive thinning must be re-made; the best exposure time is obtained through trial exposure and used to guide the exposure operation; adjust the concentration and temperature of the developer, Develop according to the standard development conditions.
3. Expanded outlets. The main reason for the dot expansion is that the concentration and temperature of the developer are too low, the development time is too short, and the developer is aging.
The way to eliminate this kind of trouble is to adjust the concentration and temperature of the developing solution, and develop according to the standard standard developing conditions according to the optimal exposure time.
3. Abnormal color of baking plate and poor ink on the plate
The film-forming agent of the photosensitive layer of the positive-type PS plate is m-cresol formaldehyde resin. After baking, the normal color is reddish brown. If the plate surface is tea green or dark green, it means that the baking temperature is too low or the baking time is too long. Short, you should increase the baking temperature or extend the baking time until the color of the plate reaches red brown; if the plate is dark brown, it means that the baking temperature is too high or the baking time is too long, the resin in the photosensitive layer is partially carbonized, the color The deeper, the more carbonized resin, the lower the durability of the printing plate, the baking temperature should be reduced or the baking time should be shortened; if the blank part of the plate surface after baking is light red, it is due to insufficient development of the plate The photosensitive layer can be gently wiped with pumice powder, but it can't be remedied when the area is large.
Poor inking of the plate surface is mostly caused by improper operation in the process of printing, developing, removing dirt and gluing.
Improper printing operations include: scratches, dust, foreign objects on the printing plate glass, insufficient density of the original image part, overexposure, incorrect shading operation, etc. These may cause poor ink on the plate surface. The method of elimination is: remove the dust and foreign objects on the glass of the plate, remake the original plate to increase the density of the original plate, print according to the optimal exposure time, check whether the shading paper is shading tight and improve the shading method.
Improper development and decontamination include: developing temperature is too high, developing time is too long, washing is not complete, the developer remains on the image, the decontamination solution splashes from the brush during decontamination, and the image part is touched when wiping the decontamination solution, The excessively wet decontamination solution on the plate surface spreads to the image part, and the cleaning is not thorough after the victory, etc., which may cause poor ink on the plate surface. The method of elimination is: check the temperature and development time of the developer, and adjust to meet the standard; re-develop the developer, and conduct trial development; the dirt removal operation should be careful, such as the brush is not dipped in the dirt, the layout can not be used by hand Touch, after the moisture on the plate surface is dry, remove the dirty liquid. After removing the dirt, thoroughly wash the plate surface with water.
Improper sizing includes: incorrect sizing method, uneven coating or excessive thickness, excessive drying temperature of the adhesive layer, excessive content of gum arabic (or CMC) in the glue solution, etc., which may cause the layout Bad ink. The exclusion methods are: use the correct glue application method, apply glue evenly and do not make the glue layer too thick. Dry the glue layer at an appropriate temperature to reduce the glue content in the glue and make the glue thick. The degree is kept at 5 ° Be '.
Non-woven fabric, is a new generation of environmental protection materials, with water repellent, breathable, flexible, non-combustion, non-toxic and non-irritating, rich color characteristics. If the non-woven cloth is placed outside and decomposed naturally, its maximum life is only 90 days. If placed indoors, it will decompose within 5 years. When burning, it is non-toxic, odorless and free of any residual substances, so as not to pollute the environment and is suitable for washing. It has the environmental protection performance which the plastic product does not have, its by the natural degradation time is far lower than the plastic bag, therefore, USES the non-woven fabric to make the non-woven fabric bag also to be recognized as the most economical environmental protection shopping bag.
Non Woven Polypropylene Bags,Blue Non Woven Bag,Non Woven Material Backpack,A Bottom Has A Side Bags
Wenzhou Shandao Electronic Commerce Co., Ltd. , https://www.reusablebaglife.com