The printing ink roller mainly transfers ink on the offset press. In order to make the ink transfer evenly and meet the needs of various printing products for the amount of ink, in addition to a certain number of ink rollers, there are usually three forms of ink rollers: ink supply, For ink leveling and channeling, the ink roller must have good ink absorption and ink transfer during printing, and it must be resistant to organic solvents, gasoline, kerosene and other oils, and easy to clean. At present, nitrile rubber is generally used for the surface layer glue of the rubber roller commonly used in the offset printing machine.
Whether the daily maintenance of the ink roller is reasonable is directly related to the service life of the ink roller. Because the offset ink roller is made of rubber, it is easy to expand and deform, dry surface conjunctive or aging cracks, etc., which affects the normal transmission of ink. Therefore, it is very important to use and maintain the ink roller in daily use.
1. After work every day and after the product is printed, the rubber roller must be carefully cleaned every day to avoid the oxidation of the surface layer of the rubber roller and the ink pigment and resin to form a smooth and hard film, which is called vitrification. Offset ink transfer. Generally, cleaning is done with kerosene first, and then with gasoline. Because kerosene is not easy to evaporate, gasoline is easy to evaporate, which can make the ink roller clean and dry and protect the ink roller. Many manufacturers now use ink cleaners (car wash water) to clean the rubber roller. When cleaning, pay attention to wash the two ends of the ink roller, because the two ends of the ink roller of the offset press are easy to accumulate ink and cause dry skin. , You can't rely on the wiper to clean it completely, use clean linen to clean the place where the wiper cannot reach, and clean both ends.
2. Prevent the ink roller from being deformed by pressure. When the offset press is in normal operation, the pressure of the rubber roller is comprehensive and even, so there will be no depressions and protrusions in certain parts of the rubber roller. After the long-term shutdown of the offset printing equipment, the ink roller is pressed in a fixed position, which may cause the possibility of partial depression. Therefore, if the downtime is long or if you encounter holidays or long holidays, the best way is to remove the ink roller and place it on the ink roller shelf. Do not let the ink roller be placed on the ground or work table to prevent pressure. Deformed.
3. Prevent the sundries and ink shovel of the ink fountain from scratching and damaging the ink roller. When working, the offset press table should be kept clean and tidy. Various tools and things used in offset printing should not be placed randomly. Do not accidentally drop debris, ink shovel, coins, etc. into the running ink roller , Which will damage the ink roller. When evaluating the ink roller, adjust the pressure between the inking roller and the printing plate, the pressure between the various ink rollers and the ink roller, use a thick and thin gauge steel sheet, and try to insert the test as few times as possible to prevent scratching the ink Roll.
4. The ink roller oxidizes the conjunctiva after long time use. In the offset printing process, bright and quick-drying resin inks are commonly used. The quick-drying feature is that the ink is added with drying oil and a diffusing agent to penetrate the surface of the rubber roller for a long time, and the rough capillary pores close the surface of the ink roller to form an oxidized film, so that The decrease in fat sensitivity affects the effect of ink absorption and ink transfer. The way to eliminate this drawback is to remove the conjunctiva layer by manual or mechanical polishing, but it should be noted that the diameter of the ink roller cannot be changed too much, otherwise it will affect the ink transfer. performance.
5. The surface of the ink roller is composed of nitrile rubber. There are two forms of rubber aging: one is the light aging of the rubber, which will affect the ink roller's ink transfer performance; , Sticky, or even cracks, the printing ink roller is required to absorb and transfer ink to the maximum extent, and at the same time to absorb moisture to a minimum, but also have good oil resistance and a certain acid resistance. Due to the frequent contact with moisture, ink, Continuous contact with paper, etc., may attract the surface of the rubber ink roller to form a film state, which reduces its lipophilicity and hydrophilicity.
The aging of the ink roller is always a phenomenon. The ink roller should be stored in a place where there is no direct sunlight, dry and clean, to avoid excessive humidity or excessive heat. The ink roller should be straight on the journal end, and the surface should not be Contact with each other or with other surfaces.
6. Due to the emulsification of the ink and the reduction of the lipophilic performance of the offset ink roller of the offset press, it is often easy to deink. The hydrophilic adhesive film on the surface of the iron ink roller is relatively easy to remove. Sodium oxide 5% solution is completely removed. On the other hand, it should be noted that if the moisture particles in the emulsified ink contain an oxidant, once excessive, it will cause black copper oxide to form on the copper surface of the iron channel roller, and deinking may also occur.
7. The ink roller is deinking. Because offset printing is a unique printing method using water, there will be ink emulsification in water, and a hydrophilic base will be formed on the smooth rubber roller before the ink roller will deink. The solution is to eradicate the emulsified ink, wash the deinked roller with hydrophilic base with gasoline, clean the emulsified ink, and mix the surface of the roller with 5% sodium hydroxide aqueous solution and pumice powder to remove the hydrophilic base and let the ink The roller has oleophilic properties, but also pay attention to the proportioning method of the offset printing water bucket solution, control the PH value of the water bucket solution, use the minimum amount of water during printing without the dirty version, reduce the degree of emulsification, gum arabic, The amount of surface active substance added cannot be too much. [next]
Common faults and solutions of ink roller
1. The ink roller becomes flat
The main reasons: â‘ The ink roller is not placed properly, and it is not placed on a special rubber rack, but on the floor and work table to save; â‘¡ Long time down, holidays, after the rubber roller is stopped, the rubber roller and The rubber rollers are still in a working state, and there is pressure. In short, it is due to the deformation of the ink roller under pressure.
Solution: â‘ Place the ink roller correctly. When the ink roller is not in use, it should be erected and placed on the rubber rack; â‘¡The rubber roller under pressure can be rotated in hot water to correct the deformation and make it round; â‘¢Cannot be corrected The rubber roller is ground, and it is physically rounded.
2. Cracks on the entire surface and part of the ink roller
The main reasons: â‘ If the ink roller has a deep crack on the entire surface, it is not used in time when it is finely cracked, and it continues to be used. It is attacked by ozone heat and aging; â‘¡There are small cracks on the entire surface due to the ink roller and ink The pressure between the rollers is too high, and the ink rollers are stored for a long time under inappropriate conditions, such as long-term direct sunlight or heat aging, etc .; â‘¢ The ink rollers are locally cracked, which is due to the uneven pressure between the ink rollers and the ink rollers. Caused by uneven pressure.
Solution: â‘ For the lightly cracked ink rollers, the ink rollers should be replaced if the ink rollers have deep cracks; â‘¡Avoid photoaging and thermal aging when the offset press is directly exposed to sunlight. The gap between them reduces the pressure. When there is a small crack in the rubber roller, the surface must be ground in time; â‘¢ Make the pressure between the ink roller and the ink roller adjusted uniformly.
3. The ink roller is locally uneven
The main reasons are: â‘ The pressure between the ink roller and the ink roller is too high, and the contact surface or the rubber jacket is peeled off; â‘¡ The surface of the ink roller softens to unevenness, soaked in organic solvent or impregnated with other chemicals
Solution: â‘ Adjust the pressure between the ink rollers and replace with new rubber sleeves in time; â‘¡ Prevent the ink rollers from being soaked with banana water, benzene solvents, trichloroethylene and other organic solvents.
4. Ink roller surface hardening
The main reasons: â‘ The rubber roller is used for a long time, which is caused by long-term light, heat and chemical erosion; â‘¡ The ink roller is in contact with the ink for a long time, and it is easy to adhere to the hardening ink film.
Solution: The ink roller will grind off the hardened surface, and replace the rubber sleeve if necessary.
5. The ink roller is peeled off
The main reason: the pressure between the ink rollers is too high, and the pressure should be adjusted to an appropriate level.
6. The rubber sleeves at both ends of the ink roller peel off from the iron core
The main reason: because there is abnormal heating, find the friction heating and remove the heat.
7. The roundness becomes slightly larger
The main reason: long-term compression of the ink roller causes its deformation to appear aging or wear.
Solution: Grind it in time to make it round.
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