Use and storage of blankets and rubber rollers

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.
one. Problems with 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 some blankets are 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 the printing. It has to be "saving" and causes serious waste.
3. In the past 10 years, the number of offset presses in China has increased. Many individual printers have also purchased offset presses. However, some individuals lack common knowledge about the use of blankets and rubber rollers and neglect their important role in printing presses. The blankets on the aircraft have not been replaced when they have been aged (loss of suitability).
4. There are shortages of liquidity in some small offset printing factories, 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.
two. How to change the bad conditions in the use and storage of blankets and rubber rollers 1. The manufacture and processing of blankets and rollers is a special industry. It serves both the printing industry and the printing industry. 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 blankets 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 should 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 for ensuring the quality of offset printing and for promoting the pass rate of rubber blankets.
three. Finished appearance quality standard of blanket rubber roller 1. Appearance quality standard of blanket finished product 1. Impurities with diameter greater than 0.5mm are not allowed in the effective use area, and small pits, small bubbles and so on are not allowed.
2 The surface of the product must not be dirty, oil, rust, etc.
3 The surface of the product is not allowed to have mechanical operation and grinding track marks. 4 The bottom cloth should not have knuckles and rovings.
2. Appearance quality requirements of the rubber roll 1 The surface of the rubber roll is smooth and uniform in color.
2 The surface of the rubber roller is free from oblique bars, bubbles, sand holes, pits, pinholes, dark bubbles, peeling, and lack of glue.
3 The effective printing range of the rubber roller should be free of impurities and miscellaneous glue.
4 The rubber layer of the rubber roller has good adhesion with the iron core without delamination.
5 Roller hardness (Shore) error ±3.
6 Roller diameter and shape error should be controlled within the required range.
four. The use and storage of rubber blankets and rubber rollers 1. Use and storage of blankets (1) Reasonably use rubber blankets according to model and printing requirements. For example, rubber blankets with poor elasticity are not suitable for high-speed printing machines and large-area dot-text printing. Otherwise, printing quality and printing plate resistance will be severely reduced. Without a good blanket, even if the drum path is adjusted correctly, it is impossible to achieve "ideal pressure."
(2) The surface of the new blanket has a smooth anti-oxidation film, which must be pumice powder in use.
(3) When installing a new blanket, the longitudinal (or marking line) is perpendicular to the axis of the drum. 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 roll, and the underlying liner (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 on the surface of the blanket pores, otherwise, the oxidized conjunctiva, dry, make the surface smooth, reduce the ability to absorb ink, directly affect the quality of the product improve.
(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 blankets, the new blankets should be tightened several times to tighten the towels on the surface of the rollers 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 not 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 saving the blanket removed from the machine, the above ink and oil must be washed with detergent or gasoline first, then washed with 5% alkali solution to saponify the oil that penetrates the surface of the rubber, and then use clean water. Wash the saponified product and dry it. 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, oil black emulsification occurs due to "great ink and large ink", and a hydrophilic base is formed on the smooth rubber roller to deink it. The solution is to scrape off the emulsion ink, wash the black roller with gasoline, mix it with 5% sodium hydroxide solution and pumice powder, and also perform the 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 too long aging, coupled with the erosion of chemicals, resulting in rotten rubber off the "residue", such a rubber roller is best not to use, or seriously affect the quality of printed products.
(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 rollers should be flat on the outside of the journal, and the surfaces should not be in contact with each other or with other objects.
(5) Cots should not be stored near large motors and generators. Because the large amount of ozone generated by these devices will cause the surface of the roller to crack and crack.