Clean - the key to success. Cleaning Systems wetting offset printing machines

I. Solovyov

In process of offset printing fountain solution with the passage of time is polluted ink, paper dust, Spray powder flush substances. In addition, under adverse conditions (eg, insufficient cooling, moistening without alcohol, contaminated tap water) in the system can appear microorganisms, making the walls of the tank humidity covered mucus or green. These deposits form bacteria, fungi and algae, which adversely affect the print quality and condition of the machine. Are possible other impurities in the moisture (Table 1).

If timely manner to clean the system, any problems in the printing process. There is a change in pH of fountain solution, increasing its electrical conductivity, foaming occurs, the solution becomes brown or black color. Violated balance paint / water: there is delay in raster points, Tenen, otmaryvanie impressions in his foot, etc. Replacement of fountain solution helps long. This is to stop the equipment during printing the circulation, when try to change the parameters of the printing process and the properties of paint and positive result is not always possible to achieve.

Table. 1. Effect of impurities on the water quality

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Impurities in the water

Availability impurities and therefore the quality of water used printers, depends on various factors (type of soil in this region, climatic conditions area). The exact content of salts in the water (its hardness) is determined using special test titration. The value of total hardness (dH) shows the amount of salts of alkali-earth metals (primarily calcium and magnesium) contained in the water. This parameter is specified in German degrees of rigidity (in - in meq / l, 1 mg-eq / l = 2,8 ? dH). Carbonate stiffness (cH) shows the content of calcium bicarbonate in water. When

use tap water for the fountain solution, one should consider following factors: hardness, hydrocarbon salts conductivity, pH. All of them are closely linked (Table 2).

Rigid water causes the formation of salt deposits on the paint roller, rubberized canvas, printed form, and on the dampening rollers and fountain solution circulation system.

Table. 2. Physico-chemical properties of water

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forms part of the rigidity of calcium bicarbonate. This substance may be different way adversely affect the printing process. It is easily transformed into insoluble lime. Because the process of offset printing of the fountain solution to the printing plate comes in a colorful part of the apparatus and there evaporates, lime can be deposited in the small pores of rubber rollers inking unit. When alcohol dampening system evaporation occurs intense, and this process proceeds more rapidly. Given that calcium carbonate (lime) hydrophilic, surface rollers loses its oil receptivity properties. Water is retained on the shaft and prevents the roller could transmit sufficient quantity of paint. Splitting of paint (adhesion) is interrupted, it behind rollers: are their "uncovering." Calcium reacts with fatty acids paint. This lime soap is formed (minerals with very sharp edges), and simultaneously a mechanical abrasion of the surface rollers, which leads to deterioration of color reproduction and premature wear rollers. When

increased content of hydrogen carbonate in water increases the pH. To maintain pH in the ideal technology for the printing range (from 4,8 to 5,5) used buffer additives for fountain solution. For different levels hardness of tap water are offered special additives to solutions with varying buffer capacity and pH values obtained.

Note that hardness is not reduced additives: they just eliminate the negative effects of hard water on the printing process. In such concentrates contain special components - complexing agents, which, converting salt calcium in the well-soluble compounds, compensate for the high hardness and not give calcium salts crystallize. In the composition of the concentrates for moistening also include corrosion inhibitors - substances that protect the metal parts printing machine from razruschayuschego effects of water.

In During the year the composition of water varies. Especially in spring and autumn, when the melt-water and Showers are in the plumbing system a lot of impurities. Very much melt-water softer artesian. Water hardness, depending on time of year can be different. It is necessary to track these changes, and, if necessary, be kept in reserve concentrates dampening water of different hardness. When

use of very hard water is recommended to carry out preventive clean colorful and moisturizers (especially sliding) rollers, offset rezinotkanevogo cloth means to remove the glaze. More about them will discussed below.

In Some printing problem solve by installing filters for cleaning and decrease the hardness of tap water and additional filters in the system Dampening solution coming from the bathroom moisture in the tank. Or use special methods of preparation of water for fountain solution (see auth. certificate).

Microorganisms in the fountain solution

Next Group clogged dampening system - micro-organisms, which fall into car from water, air, paper, dust. These are: algae, fungi (yeast, mold, etc.) and bacteria. Hydrating solution - suitable for them among habitat. Finding it food, microorganisms alter the pH of moistening and violate printing process. Particularly rapid is the growth of microorganisms, if the system moisture is not cleared and the walls of the tank and the periphery of the moisture accumulated deposits of paper fibers, paints, gummiruyuschih funds, etc. The presence of Microorganisms in water can be measured with special tests.

Bacteria and algae cause corrosion of metal. They consume and decompose acid, and pH increases. The growth of microorganisms violates the circulation of moisture in the system, reduced productivity and print quality, there is an unpleasant smell the risk of disease.

Author Help

Preparation of water for fountain solution There

several ways to prepare water for the printing process: softening, complete desalination (desalting), reverse osmosis.

Devices water softeners operate on the basis of cation, which is regenerated from using salt. Calcium and magnesium ions are replaced by sodium ions. But anions (eg, hydrocarbons) no. Thus, the total salt content is not decreases. Water softening only prevents the deposition of lime, as hydrogen carbonate (sodium bicarbonate) is easily soluble. Since

bicarbonate content is saved, there is nothing to prevent the influence of value of pH (increases the pH value) and the buffer capacity fountain solution (it decreases).

Conduct alone water softening inappropriate. Neutral water softening conducted as a preliminary step in the reverse osmosis. When

full desalination one after the other includes two exchanger: cation, which replaces all cations (eg calcium, magnesium and sodium) hydrogen ions, and anion exchanger that replaces hydroxyl ions all anions, such as bicarbonate, sulfate, chloride (chlorides and sulfates accelerate corrosion). Jonah hydrogen and hydroxyl give us clean water, so that the sum of all soluble replaced with salt water. Cation exchanger is regenerated with hydrochloric acid, anion exchanger - sodium hydroxide. When

reverse osmosis desalination is complete. Water after it passes through 1-2 activated carbon filter for removing chlorine, is injected under certain pressure through the membrane, which allows only water, but not salt. The treated water has very low residual salt content, simultaneously eliminated bacteria and fungi. To avoid lime deposits in the membrane, water must be skipped at first through the neutral softening. When

general water desalination and distillation, almost all the mineral salts removed. Fully demineralized and distilled water also adversely affect the process of printing. Practice shows that the total desalination of water and decrease stiffness to a0 dH increases emulsification paint Dot gain a strong distortion of halftone dots and gradation. It should be noted that distilled water has a pH = 5, and at the double distillation of pH = 4.

Optimal printing results achieved with the total water hardness 7-10 ? dH, carbonate 3-4 ? dH. Therefore, in demineralized water, introduction of special additives (eg, Hydroplus 10 from BASF or Aqua Conditioner from Varn), to establish the rigidity demineralized water at 7-10 ? dH. This can be done using a special dosing (eg, Doser from Varn). Thus, we get the water, fully suitable for the printing process. It introduces a concentrated additive for average water hardness. At very high rigidity (maintenance hydrocarbon salts above 400 mg / l) is sometimes mixed with tap water distilled. Necessary in this case to determine the correct ratio, obtained by measuring the hardness of water. Stiffness was determined by titration. Recall that the composition of water varies throughout the year, and need to track these changes.

Methods preparation of water

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K Unfortunately, sometimes it is necessary to observe a complete disregard for this issue. Thus, in one of the printing presses to never something that has not been cleaned humidification system, but did not change the fountain solution, do not wash blankets dampening rollers. At the same time during the printing process is constantly going otmaryvanie. When decided to do an analysis of fountain solution and poured it into bottle, the next day on her neck formed plug of microorganisms and the liquid is not overflowed. Had several times to clean the system of humidification special means and to introduce biocides (preservatives), killing microorganisms.

Special antiseptic components - biocides (see bus. certificate) are part of the additives in hydration. They prevent the formation of slime and the growth of bacteria and algae in the dampening system and the piping humidifying system, providing significant increase in the interval between the slops humidifying system and change water.

Corrosion caused by microorganisms

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K biocide meet the following requirements. They should:

influence all kinds of microorganisms,

remain stable in solution over a wide range of temperatures,

well mixed with water,

not affect the existing fountain solution of surface-active substances (SAS) and paints,

not be toxic to the environment.

To avoid problems, it is necessary to change the fountain solution and to preventive cleaning at least once in 2 weeks and to thorough cleaning of the dampening system with special means at least two once a year, while bad water more often.

Author Help

Materials required for dampening solution

In Help gathered information on various materials intended for use with humidification modern offset presses. These tools solve several tasks: regulate water hardness and stabilize the pH, reduce the volume use isopropyl alcohol (IPA), prevent the growth of microorganisms and etc.

Buffer additives in the wetting Such

additives for hard water are available, for example, in the range of companies BASF (for sheet-fed offset machine) and Varn (for sheet and web offset machines). Eat the market and other concentrates moisture, each manufacturer of a rather lot.

Flavor funds must be in accordance with the tasks that need to be solved, and better consult a specialist.

Buffer additives in the moistening for hard water company BASF (for sheet-fed offset machine)

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Biocides

Safety biocides introduced into the supplements tested on more than 500 tests on harmful. Special biologically sterilizing solution - Sterilising solution (Varn) -- protects against microorganisms, is fast acting and is suitable for all systems moisture. It is used in the amount of 0,5% of the volume of water can be mixed and with the addition of moisture in the amount of 1-2%. If there is a system of water preparation solution can be filed with the dispenser to prevent contamination moisture.

K Unfortunately, buying equipment for offset printing, often do not consider necessary to establish a system of preparation of water for fountain solution. A because it would solve the problem of its purification from impurities and microorganisms. Only, when in the process of printing problems, begin to look for ways to clean water. In , such systems offer many domestic manufacturers.

Buffer additives in the moistening for hard water company Varn (for sheet and roll offset printing machines)

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Support clean fountain solution also helps special adsorbent pads Super solvent soakers (Varn). They absorb 20 times its own weight, is there a reverse pollution solution.

In alcohol moistened isopropyl alcohol is an antiseptic, but if not care for humidification, no alcohol, no preservatives contained in supplements do not have the desired effect. Humidifying system requires Preventive cleaning.

washes paint rollers and blankets

Automatic remover inking unit is recommended to use special funds that do not contain aromatic hydrocarbons. For example, Bottcherin 60 (Bottcher), Washmittel 60 (Varn).

hand washing paint rollers hold special emulsion (Bottcherin Blue (Bott-cher), Washmittel 111 (W-111 Varn).

Withdrawal glazes. There are special tools. For example, Feboclean EK (Bottcher), which can be used for the prevention of not less than 1 time per week. Medium-jelly applied to the rollers for 5-10 minutes, until a reaction occurs, and washed water. Feboclean EK sparing contains organic acids and does not provide adverse effects on the rubber coating paint rollers.

Withdrawal raids calcium salts. Calcium Deglazer (Varn) used in the formation of cylinders flying white crystals of calcium carbonate that breaks the surface roller in the printing process. This highly concentrated agent is applied, when not helping funds from the glaze. Be grown with water 1:5.

Cleaning then rubber rollers of colorful sediments hold a special compound For example, Feboclean RE 2 (Bottcher). This tool is also used quick change colors, especially dark on light.

Universal cleaners. May be cleaned and dried on the paint, and the glaze, and both ridges and blankets. For example, Walzenreiniger 6001 (BASF) or Revitol (Varn). Revitol tool can be used for cleaning offset rubber canvases.

Deep clean blankets. S.R.R. (Super Rubber Rejuvenator (Varn) or Bottcherin EG-20 - a very effective means. First clean cloth conventional flush tool, then applied SRR (or Bottcherin EG-20) for 15-20 min. (for this time regeniriruyuschee means completely evaporated). If necessary operation can be repeated. At the end have to wipe the offset rubber dry cloth. After use this tool surface again becomes a rubber mat. Shoe

dampening system

Preventive cleaning. For this ideal tool Fount Cleaner (Varn), which destroys microbes, removes sediment and water-soluble paint residues in circulatory system. Value concentration and water in the solution - 1:20.

Cleaning rollers. Moisturizers rollers carefully wiped 20% solution of isopropanol. Luchshe use a special remover, volatile and does not contain aromatic hydrocarbons. For example, Bottcherin FR 1000. This tool also well suited to direct film of moisture and is recommended for daily prophylactic treatment dampening rollers apparatuses cars GTO. Rollers can be cleaned with zazhirivanii also means True Blue (Varn).

Deep purification. If the system is heavily contaminated with moisture or not cleaned for a long time, suitable means Fount Clean (Varn). At one part of concentrate add 4 parts water in the tank dampening the printing press. There is a special set of tools from BASF for thorough cleaning of the dampening system, in particular Hydroclean-Reiniger. Its membership includes cleaner, and converter, and biocide.

Fabric blankets dampening system. If your machine is installed with the moisture fabric covers, they should be cleaned ad biologically decomposable washing Eco-Wash (Varn) manually.

Shoe humidification systems When

Integrated cleaning system recommended moisture to conduct such operations:

Cleaning inking unit. At the beginning of colorful rubber rollers accumulate tiny paint particles, which hardens, Spray powder, particles coated sheet of paper. All this complicates the process of transferring ink. Rollers inking unit, first clean the usual flush means. Then special means (see the bus. help) produce a deep cleaning. Eat means for cleaning paint deposits from the glaze, universal. First cleanse the pores of the paint, then from the glaze: Apply cleaner to several minutes until the reaction occurs, and then wash it. When use the money for deep cleaning is necessary to strictly comply recommendations of the manufacturer. The so-called funds from the glaze first, as Generally, wash water, and then flush the usual way, otherwise the glaze again tread on the shaft and does not fully wash off.

Cleaning alcohol dampening system: fountain solution is recommended to change at least once every 2 weeks, cleansing and moisturizing bath tank, as well as banishing water through the hoses. For prevention and good use of special tools. The procedure is as follows: drained fountain solution, wash moisturizing rollers special means, to conduct thorough cleaning and remove glaze from rollers special tool. Then fill the tank of water and moisture is introduced concentrate for cleaning, then include the circulation of the fountain solution, and filing of isopropanol and additives disconnected. Circulation conducted during 20-40 min, then the solution is discharged from the system. Several times the dampening system washed with tap water until the pH will not be the same as in water, coming into the system moisture. To neutralize possible to introduce about 2% additives in the second clean water for washing. Such a thorough cleaning is recommended 1-2 times per year. If the system was infected, for prevent the growth of microorganisms after cleaning humidifying system recommended to add water biocides. Cleaning

traditional dampening system

Moisturizers rollers traditional dampening system with fabric cover recommended to clean the extent of pollution, as well as after using metallic inks, as after they are covering a very clean difficult. Rollers hardens, and reduces the transfer of dampening solution in their individual parts or the whole length, which causes uneven distribution of supply of fountain solution, or a general decrease in feed moisture. As a result, the balance is disturbed and there is delay in raster point, Tenen, otmaryvanie paint. Print metallized inks recommended to use separate blankets in moisture and to clean covers -- special funds, made on the basis of natural natural components do not contain galogenozameschennyh hydrocarbons and organic decomposable.

Cleaning beads coated textile cases, manually using hair brushes, or specially designed for the automatic devices. After processing flush tool spindle must be washed plenty of water.

Use soap and washing powder increases alkalinity moisturizer solution. There may be violations: fatty oils ink decomposed alkalis on the components, resulting in the formation of soap (salts of fatty acids). Since the molecules of fatty acids are hydrophilic and oil receptivity group, they act as wetting agents and reduce border tensions between paint and water, which are partially blended. There emulsification, raster tone becomes denser, the non-tenyat begins otmaryvanie.

not encouraged to use aggressive and do not mix with water resources in shrink cylinders: they lose their properties to push the paint. Not use flush substances intended for paint rollers, as they are badly washed with water and break down the paint.

After cleaning rollers should be overcome and put to dry on special stands. Before installing the car wet.

Table. 3. Microorganisms

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Conclusion

If systematically carry out preventive and comprehensive treatment moisturizing system and the inking unit, significantly reduce the technological downtime presses. Parameters fountain solution should be checked daily with using devices.

Cleaning humidification systems must be part of the production process, included in the schedule of maintenance of equipment, to require compliance. For Printers-write detailed instructions that all funds used correctly.

hope information proposed in this article will help you understand the tools purification. In any case, always ask for instructions from the suppliers.

References

For preparation of this work were used materials from the site publishprint/


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