Offset rubber and rubber roller use and storage

If the offset press does not have excellent blankets and rubber rollers to match it, it cannot print high quality prints. Due to the need for work, the author visited some printing factories and found that the use and storage conditions of a considerable number of printing blankets and rubber rollers were very poor. It has come to our attention.
First, problems in the use and storage of rubber blankets and rubber rollers 1. At present, there are few systematic data on the mechanical properties and properties of rubber blankets and rubber rollers. This is incompatible with today's rapidly evolving printing situation.
2. Due to market competition, some blanket manufacturers have taken unfair measures to reduce costs and even sold unqualified blankets to users at low prices. The flatness and elasticity of these blankets are very poor, and other performance indicators do not meet the standards. There are more rubber roller production factories than rubber blanket production plants, and the production scale and technical strength of each manufacturer are quite different. The pass rate of the rubber rollers processed by some small factories is very low. The use of such blankets and rubber rollers not only shortens the period of use, but also reduces the quality of printing. This not only does not save money, but also causes serious waste.
3. In the past 10 years, the number of offset presses in China has increased, and many individual printers have also purchased offset presses. However, individual personnel lack common sense about the use of blankets and rubber rollers, ignoring its important role in printing presses. The blanket is not replaced when it has aged (loss of printability). Some offset press rollers do not change for several years in continuous use.
4. Some small offset printing plants are in short supply of liquidity, and the purchase price is low-quality paper. These papers have many sands and many paper powders, which not only affect the printing quality but also wear the blanket. Some plants have excessively controlled the use of gasoline and cotton yarn. Operators have to reduce the number of washing blankets. Some printing houses that only print monochromatic texts for a long time do not generally change their colors, so they rarely wash their ink rollers. In doing so, even a new rubber roller that has just been used, it is easy to lose the ink-receptive performance. These above-mentioned practices not only fail to save, but also cause greater waste.
Second, how to change the use of blankets and rubber rollers and the use of storage in the bad situation 1, rubber blanket and roller manufacturing, processing is a relatively special industry, both for the printing industry services, but also not the printing industry management. Therefore, the lack of industry standardization management and supervision. It is recommended that the state coordinate the printing industry, the rubber processing industry, and other relevant departments to strengthen standardization management of rubber blankets and rubber roll processing industries, and regularly organize product quality evaluation activities in the same industry. This will have the effect of mutual communication and promotion.
2. At present, the important reason for the poor use and storage of rubber cloth and rubber rollers is that some printing house cadres and workers know too little about common sense in this area. Although books and magazines related to printing technology have been published in recent years, technical books on blankets and rollers have rarely been published. It is suggested that more books in this area be used in the future to adapt to the current rapid development of the printing situation.
3. The management and technical personnel of each printing manufacturer shall briefly understand the manufacturing process flow and appearance quality standards of blankets and rubber rollers. In this way, the pros and cons can be judged at the time of purchase or acceptance, and unqualified products should not be purchased. This is also of great benefit in terms of ensuring the quality of offset printing products and promoting the improvement of the yield of rubber blankets and rubber rollers.
Third, the appearance of rubber blankets and rubber roller appearance quality standards 1, blankets finished product appearance quality standards (1) in the effective use of the area does not allow a diameter greater than 0.5mm impurities, not allowed to have small pits, small bubbles and so on.
(2) The surface of the product must not have any dirt, oil, rust, etc.
(3) The surface of the product is not allowed to have mechanical damage and grinding marks.
(4) The bottom cloth should not have knuckles or rovings.
2. Appearance quality requirements of the rubber roller (1) The roller surface is smooth and uniform in color and color.
(2) The surface of the rubber roller is free of oblique strips, bubbles, trachoma, pits, pinholes, dark bubbles, peeling, and lack of glue.
(3) There should be no impurities or miscellaneous glue within the effective printing range of the rubber roller.
(4) The rubber layer of the rubber roller adheres well to the iron core without delamination.
(5) The roller hardness (Shore's) error is plus or minus 3.
(6) The roller diameter and shape error should be controlled within the required range.
Fourth, the use of blankets and rubber rollers and storage 1, the use and storage of blankets (1) according to the type of aircraft, printing requirements reasonable selection of blankets are not suitable for high-speed machines and large-area network printing, otherwise it will seriously reduce Print quality and plate resistance. Without a good blanket, even if the roller section is adjusted correctly, it is impossible to achieve "ideal pressure."
(2) There is a smooth anti-oxidation film on the surface of the new blanket. This film must be scrubbed with pumice powder, gasoline or kerosene (or mixture) in order to ensure that the surface of the blanket has good ink absorption performance.
(3) When installing a new blanket, the longitudinal (or marking line) must be perpendicular to the axis of the roller. Do a good job of cutting work, and the shear lines of the tip and mouth must be parallel.
(4) The length of the blanket should be less than the size of the pillow. The underlying underlay (such as felt, hard paper, etc.) must be narrower than the blanket. In this way, when the blanket is tight, the left and right sides of the blanket are tightly tightened on the roller surface of the machine, which can prevent impurities such as impurities, oil detergent, and water in the printing process from entering the inside and causing blanket delamination. Foaming and so on.
(5) In the daily production, cleaning the blanket must be serious, do not allow the ink to remain in the pores of the surface of the blanket, otherwise, the oxidized conjunctiva will become dry and the surface will become smooth, which will reduce the ink-absorbing ability and directly affect the product. Quality improvement.
(6) The "ideal pressure" advocated by the offset printing process not only guarantees the quality of the product, but also has an important significance for extending the service life of the blanket and reducing the creep. Therefore, we must do our best.
(7) In order to reduce the obvious appearance of the stress relaxation phenomenon of the blanket, the new blanket should be exchanged and tightened in stages to make it tightly adhere to the surface of the cylinder to prevent double imprinting and deformation.
(8) Removing the tension when the blanket is disabled is an effective way to prolong the high elasticity. Therefore, it is recommended to use two blanket replacement methods.
(9) During the storage of the blanket, avoid contact with oil, acid, alkali, salt, etc.; do not subject it to squeezing so as not to break the blanket and destroy its elasticity. The blanket is also afraid of light and hot and humid air, these media will make the surface of the blanket sticky, crusted, cracked, hardened and make the cloth mildew.
(10) When the blanket removed from the machine is stored, the above ink and oil must be washed with detergent or gasoline first, and then washed with 5% alkali solution to saponify the oil that has penetrated into the surface of the blanket. Wash the saponified body with water and wipe it dry. Finally pour talcum powder.
2. Use and storage of the rubber roller (1) The printing roller mainly transmits ink on the offset printing machine. Therefore, the daily cleaning of the rubber roller must be carefully cleaned, otherwise it will cause the surface layer of rubber roller and the pigment and resin to oxidize to form a smooth and hard film, which will cause the surface vitrification and affect the transmission of ink. If the cleaning is not always clean, the surface of the rubber roller will not be easy to use. Therefore, the roller should be cleaned and put back for use when shutting down.
(2) In the offset printing operation, ink is emulsified due to the “great ink and large ink”, and a hydrophilic base is formed on the smooth rubber roller to deink it. The solution is to remove the emulsified ink, wash the deinking roller with gasoline, mix it with 5% aqueous sodium hydroxide solution and pumice powder, and perform corresponding treatment on the metal roller. The fundamental solution is to control the pH of the fountain solution and do a good job of ink and water balance.
(3) The rubber roller is used for a long time aging, together with the invading turbidity of the chemical, causing the rotten rubber to lose the “residue”. Such a rubber roller is best not to be used again, otherwise it will seriously affect the quality of the printed product.
(4) In order to ensure that it does not affect the quality of production and printing, there must be a backup ink roller, but do not store too much to avoid aging. The storage environment of the rubber roller is the same as the blanket. In addition, the rubber roller should be straightened at the journal, and the surfaces should not touch each other or other objects.