Talking about the concept of ink and water balance in lithographic printing

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1. Introduction

The lithographic Litho Graph (Offset) printing originated from the lithographic ink-repellent printing method invented by A. Senefelder in 1797. The lithographic printing and other relief, gravure and screen printing are used to produce different printing patterns. Other printing methods use only one type of flow ink to create the print and transfer it to the print. The lithographic plate must use two fluids to produce the print. Only the print (oil) ink can not distinguish the print on the plate (except for the horizontal plate), but the plate must be coated with water to make the print. The part of the pattern is covered with a layer of water, and the printed part is water-soluble to remove water. When the ink is applied, the printed part is oily and has no water, so it is easy to make the ink flow on the printed grease. On the contrary, in the non-printed part, because the water is pre-coated, the ink layer cannot be adhered, and only the printed portion with grease is left. In printing, the printing ink is removed by the blanket, but some of the non-printed part of the water is also removed by the blanket, but most printers only pay attention to the printing ink during production. Transfer, rarely notice the fact that the non-printed part of the water is transferred, and even do not notice the effect of the non-printed part of the moisture remaining on the surface of the printed medium, which will result in the post-printing ink. Difficulties in transfer. If the lithographic water is carefully analyzed, the effect is to reject the transfer of the ink, and the water film layer which is transferred from the non-printed portion of the printed medium to the surface of the printed medium on the printed medium also causes the printing ink to be printed. When attached, some parts will be rejected. Unless there is a well-absorbed paper medium, it will have a more dry "dry" printing surface for absorption of the next color ink. Therefore, there is a design of the modern lithographic printing machine from one unit two-color system to one unit per color, and there is no longer a design of two-color one unit.

In theory, everyone said that lithography uses the principle that oil and water are not mixed to achieve the effect of distinguishing between print and non-printing. In fact, this argument has its basis, but not both are 100% unmixed. Often the ink is also transferred to the water supply system, but the ink layer on the printing ink supply system is transferred to the printing plate, blanket and paper-printed ink, which contains more or less water unless there is no horizontal printing. It is possible that only 100% of the ink does not contain water. The reason is that the ink must have a certain percentage of compatibility with water content to make compromises. The situation is as long as there are female estrogens in men. If there are too many estrogens, men have obvious feminine characteristics. Women also have male hormones, but not too much, otherwise girls will have long beards. In the lithographic ink, it must contain about 5~28% emulsified water. This is a normal phenomenon and a necessary safety zone for buffering. Just like the 38° degree line between North and South Korea along the north latitude, there is an isolation on both sides. Like a non-military buffer. In the police, it is often not enough to arrest the prisoners. The police force is not enough. There must be a "netizen" in the eyes of the police. It is easier to control. From the possible inside, it is necessary to find clues to solve the case. Otherwise, it is difficult to maintain the ecological balance of the public security. . In case the lithographic ink is 100% water repellent, the lithographic ink balance is as easy as balancing on the steel cable. As long as the water is a little bit more ink, the print portion is completely removed. A little less non-printed part of the water becomes full version. For lithographic printing, there is easier ink balance control. Usually, lithographic inks must have a water tolerance of up to 18~35%. This is not recommended for printing. In operation, the maximum upper limit is used, because as long as the upper limit of moisture tolerance is passed, not only a lot of emulsified white spots on the printing mark are generated when printing, but even the ink will disintegrate until it has no viscous ability to lose its transfer, and the next is not On the layout ink roller and the printing plate, the complete collapse state of the printing ink transfer function is completely lost. The ink supply system must be washed back to print.

In some printing press manufacturers, in order to make the lithographic printing operation easier, printing in small-scale and small-size printing such as printing plastic cards is carried out using the horizontalless Waterless Offset method, which is a printing plate with all horizontal printing inks. The repelled silicone rubber layer is used as a non-printed surface, so the ink does not adhere to the surface of the low-caliber material of the silicone layer when ink is applied, and the ink is produced only in the printed portion without the silicone. The attached print is transferred to a single-fluid printing method. It is only necessary to control the temperature of the printing plate and the ink supply system very accurately, in order to avoid the poor transfer of the printing ink due to the temperature being too low, or the malfunction of the non-printing ink staining due to the temperature being too high. Also, because no horizontal printing is a single-fluid printing method, there is no trouble with ink-liquid two-fluid printing. In the 1980s, there are still many advocates. KBA has designed a large Cortina-free watermark. The machine has the advantages of quality, operability and quick printing start, and less waste, and there is a new development trend.

2. the uniformity of ink supply and water supply system

If you want to make the lithographic machine ink-balanced, from the ink supply system, the water supply system, from the ink tank roller, the sink roller, to the plate-facing (touch) ink roller closest to the plate, you must have a very flat diameter and roller. The roundness of the cylinder surface, otherwise the diameter of these rollers is inconsistent, and there are concave defects on the surface of the roller. Even if the best technician wants to adjust the two systems, it is impossible. As long as the diameter is inconsistent, the surface is concave, and the surface is uneven, the water will be uneven, the water will be uneven, and the water will be uneven. It must be the most dry place, and it will not be dirty due to insufficient water. The wettest place must be It is a problem that the water supply is too much, and it is easy to cause emulsification. If there is less water, it will cause dirty spots due to insufficient water. The unevenness of the water roller is not only a mechanical size, but the water roller can also be partially water-free or water-receiving if it is adhered to the ink or ink mordant (Fan Lishui). Lowering, the situation is as good as the broken surface of the water roller. The same is true for the ink roller. The diameter is out of shape, the roundness is not good, the surface is broken, and the surface of the ink roller is stained with a hydrophilic colloid. When it is wet, it will be deinked. It is the same as the water supply, but the effect is reversed. I can't get dirty, but the ink color fades, and even the entire ink supply area has no big problem with ink. Uniformity, no defects on the surface, no adhesion to water or ink transfer deposits, etc., are important conditions in the balance of ink and water, so that smooth printing can be achieved.

The appropriate hardness of the water roller and the ink roller and the adjustment of the appropriate roller pressure are also important factors for the transfer of the water ink, because many people use the ink roller, the water roller, and even the printing tube to fully print the ink and see it. The width and width of the contact are used to determine the reference of the press to adjust the pressure of the roller. This has only relative accuracy, but no absolute accuracy. As for what is relative accuracy? For example, the touch width of 5mm is too heavy! It should be light if it is adjusted to 4mm or 3mm, and the 6mm is the increased contact. However, the diameter of the roller or the printing tube is different. When the contact amplitude is the same, it does not mean that the pressure is the same. If the diameter is doubled, the contact pressure should be doubled to be the same. As for the small diameter, the same is also required. It is appropriate to reduce the size of the tentacles to calculate, the pressure can be produced properly and not too heavy. In addition, all the rubber ink rollers and printing rollers of the lithographic printing machine are arranged in a hard and soft manner, and the soft rubber roller or the rubber rubber tube with the blanket is used as the retracting elastic body when being pressed. Therefore, these rubber elastic, Shore Hardness values also affect the pressure, the same large contact depth or contact amplitude, the hard rubber ★ cylinder will produce greater pressure, softer rubber roller or rubber Cloth and padding produce a small pressure response, so the hard padding intrusion pressure can only have a pressure of 0.05~0.07mm, the medium hard type can have a pressure of 0.12~0.15mm, and the soft pad can reach 0.2~0.3mm invasion. Pressure, otherwise the full-size ink transferability will be worse. As for the lack of pressure, due to poor water transfer and poor ink transfer, it is necessary to have a very thick layer of water and ink to transfer between abnormal gaps. Naturally, there is no real need for ink supply and water supply. Water supply or ink supply. If the abnormal production is performed under the emulsification of a large amount of thick film ink, not only the ink transfer property is poor, but also the printing on the printed matter is swollen, the drying is delayed, the back printing occurs, and the ink color is dark and the dot is enlarged. It is common for many ink rollers and water rollers to be used for a long time. The roller rubber is slimmed due to the release of the material, resulting in insufficient pressure of the ink roller and the water roller, and it is necessary to perform a shutdown inspection. After printing the waste plate that is no longer saved, put down four touch-plate ink rollers or one water roller to lean against the plate. At least check the pressure of the last pass to the layout. Can it be saved normally? After the machine is stopped, press the inching forward or reverse again to see the horizontal contact residue on the surface of the roller. Is it consistent and the touch is moderate? But the inside of the roller touch this way does not work. Therefore, the contact pressure method to see the pressure of the printing press has its convenience and reference, but the diameter and hardness of the object to be inspected are another reference index. If the pressure of the ink roller is too large, the contact width is too wide, not only the ink transfer amount is changed, but also the ink is softened and softened, and the ink is easily emulsified and the ink supply amount is lowered. Therefore, the printing plate is easily damaged, and the rubber heat-expanding skin is generated. Injury.

The ink roller must have a lipophilic rubber to ensure that the printing ink adheres and is not easily deinked by the colloid of the wet water. On the other hand, the water roller needs a softer hydrophilic rubber. If the ink roller is used as a lipophilic rubber, the water supply amount will be greatly reduced, and it is easy to cause the ink to affect the water supply amount. More importantly, the water roller does not. Under even ink, it is necessary to increase the amount of water so that the lowest water supply block has enough water, so the area without water will be too much water supply! Severe emulsification of the generated area, the unevenness of the water supply, the degree of unsmoothness is not less than the diameter deformation of the water roller.

The ink roller is generally divided into two or three different rubber hardness grades. The rubber near the ink groove roller portion and the riding roller is relatively hard, about 35° Shore, and the ink roller of the layout is softer to reduce the impact streak. And the head is smooth with 28~30°Shore, others are between 30~35°Shore. The water roller is made of a soft hydrophilic rubber with a Shore hardness of about 18 to 22°. The water supply is too hard and the water supply is reduced due to the pressure. At present, many manufacturers change the sink roller from chrome to ceramic surface. On the one hand, it can avoid the formation of chrome oxide and hinder the hydrophilicity of the chrome roller. On the other hand, the ceramic water roller retains good and long-lasting hydrophilicity. According to this, it is possible to reduce or even use IPA isopropyl alcohol to achieve a more environmentally friendly purpose.

3. the temperature control and additives of the water supply system

Water is a liquid state. After it absorbs heat and reaches the critical point of molecular perturbation, it quickly escapes into the air when the vapor pressure in the air is small. On the contrary, when the water absorbs the same heat but the vapor in the air reaches 100% saturation. Water is difficult to convert into steam and escape into the air. It takes more heat to evaporate. From this example, we can understand that in the ink-and-water balance, if the water supply is the same, the humidity in the air is closer to saturation at low temperatures, and the evaporation of water is less, and the layout retains more water. On the contrary, high temperature, low humidity in the air, low vapor pressure, and faster evaporation of water, will result in insufficient water, which will cause a lot of water and water balance in the operation of the lithographic printing machine, so that the water on the plate A large amount of evaporation is insufficient, resulting in dry spots on the non-printed portion of the ink. In addition, due to the low temperature and high humidity, the water supply is excessively emulsified. If it is printed on a white paper, it will be a large amount of paper. It will also increase the consumption of wet water; printing coated paper with less water absorption, even plastics, synthetic paper, and metal foil that do not absorb water, then the absorption of water in the absorption is equal to zero, so that the water becomes too much, so Water consumption is divided into three aspects. One is the size of the layout, the temperature and humidity, the printing speed, the size of the layout is large, the printing speed is fast, and the water consumption is proportional to the increase, while the rotation speed is fast, the temperature may rise to increase the evaporation of the thermal disturbance, and the other one. The reason is that the amount of water taken away by the paper and the amount of water taken away by the emulsified ink are increased when the printing speed is increased, (the ratio of the two is consumed, and the emulsified water is used because there are many printing lines) Increase, increase water consumption due to increased water absorption of non-printed white paper). The temperature of these ink rollers rises due to the viscous drawing of the ink, or the heat is generated by the ink roller oscillating the rubber roller, so that the temperature is rapidly increased and the ink balance is adjusted. Generally, lithographic printing absorbs a large part of heat because of a large amount of water evaporation, but generally it is suitable for 25 ° C. Therefore, all the printing machines currently use a humid water cooling system to reduce water evaporation and keep the ink supply system ink. The layer reduces emulsification due to good astringency. However, as the speed of the printing press becomes faster and faster, from six or seven thousand sheets per hour to 15,000, 16,000, and 18,000 sheets per hour, it is impossible to maintain the temperature stability of the ink supply system by simply relying on the low temperature of the moist water. Today, most Zhangye printing presses use hollow steel ink rollers to hollow out the cooling water to reduce the temperature of the ink supply system. As long as the temperature rises above 150 °C, the hardness of the ink will be softened, and the resistance to splitting will be reduced. Reducing the amount of transferred ink is less, and it is easy to emulsify. This is the main reason why the printing ink color is light and light under the high speed and long rotation. Due to the softening of the ink, the mid-tone dot rises and the control cannot be controlled. Unlike the normal performance of the first-print cold machine, the mid-tone is not increased due to the increase of the dot point, and the ink density of the full and dark parts is reduced. The lightening quality is declining. Therefore, not only the horizontal printing machine, but also the horizontal printing machine, in addition to the water roller system, has a water temperature control in the water tank, and the ink roller system is also equipped with a cooling water cooling system through the ink roller or the ink fountain roller. The center absorbs heat to keep the temperature of the ink roller from rising.

Some acid and colloids must be added to the bath. Previously, ammonium nitrate, ammonium phosphate or ammonium dichromate was used. Among them, ammonium dichromate can keep the water acidity, avoiding the ink being turned into alkaline after the ink is turned to alkaline. The oil is "saponified", which causes the ink to decompose and dissolve into the water, causing fat and pigment contamination. The surface adsorbs the dichromate, forming a surface that is not easily oxidized and soiled. Before the PS version is raised, it is a very A useful anti-oxidation, anti-paper powder rubbing surface that is extremely effective in keeping non-printing clean. At the beginning of the PS version, the surface of the aluminum plate was not anodized. After thousands of revolutions in printing textbooks, the aluminum would absorb too much alkaline chemicals on the paper surface, causing corrosion to cause the print to fall off. Later, after the anodizing treatment, not only the plate surface was raised to 9 degrees high hardness wear resistance, but also the ability to resist alkaline chemical corrosion was much enhanced. Therefore, most of the water tank liquids are mainly maintained in an acidic environment of 4.5 to 5.5 PH, but the printing rotary machine is not saponified because of the ink, so it is produced in a weak alkali environment of pH 7 or higher. In order to counter the contamination of alkaline substances dissolved from the paper surface, and the acidity of the layout can maintain the ink convergence, the printing will not increase, and the addition of acidic substances is an important component of the current hydrophilic liquid, so that the pH value changes little, many The pH buffer is added to the bath to maintain a normal pH of 4.5 to 5.5. Therefore, the true PH data is not measured, but only a certain degree of action is maintained. Therefore, the conductivity is detected by the resistivity. To find out the true acid content of the wet water, it is no longer affected by the buffer. In the past, when the quality of printed paper was poor, there was a thin layer of gum arabic on the printing plate to improve the layout and better hydrophilicity. However, when the paper and paper powder were too much, the layout would be smoothed and lost. Hydrophilic and hydrated, so it is necessary to rely on the colloid contained in the sink liquid to supplement the consumption of the gum arabic layer. Now almost no glue is added, because the PS plate and the CTP plate are all treated with hardened oxygen to form alumina hard. The film is very abrasion resistant, so the modern tank liquid is composed of hydrophilic treatment liquid, interface active agent, pH control and buffer, plus IPA isopropanol.

Today, there is a rise of IPA-free alcohol-free wet water system to avoid evaporation of VOCs and affect the environment, but how to deal with it without IPA? First of all, it is necessary to filter and remove minerals such as calcium, magnesium, iron and manganese in the water, so that the water is softened, and the water is more humid, and the oil and pollutants in the water are also removed, and the good moisturizing power close to "pure water" is maintained at all times. Some use UV light to do photocatalyst sterilization, reduce the occurrence of floating matter and mold in water, and affect and block the fluency of water pipes. Now the alcohol-free wet water system is also in the epidemic, which is the development direction under the environmental protection demand.

4. the printing ink supply layer is the fixed drum of the ink balance

Ink and water balance is the interaction between the water layer and the ink layer, so that the minimum color of the ink layer can be printed to print the appropriate color, and the printing plate is kept clean with the thinnest water film and a little safety factor, which is the best ink balance. in principle. However, the seemingly easy operating conditions, in the actual operation, the new printing machine is generally easier to achieve ink and water balance, the main reason is that the ink roller, water roller, each of the flat and roundness is very good, and the rubber elasticity is good. Claim. Therefore, the thickness of the ink layer on the left and right sides is easy to be uniform and the ink and water layers are accurately transferred, and the ability to react ink refilling and water addition and water reduction is as fast and accurate as expected. An old printing machine, first of all, the rubber hardens, bulges, shrinks, and the pressure changes unevenly. Even the four printing rollers have only two inks on the printing plate, and the left and right pressures are not uniform, resulting in ghosts, Streaks, the ink layer is also rough because it is not well-distributed, it is easy to back print dirty, the color is not enough to add a thick ink layer to be enough ink, and at the same time make the ink out of balance. The same thing happens when the water supply system with only one plate water roller is more serious, so today many large printing machine manufacturers return to the previous emulsified ink configuration. The first ink roller is a way of mixing water and ink. Produces greater tolerance and flexibility in ink balance. Therefore, every three or four months (now the rubber is more stable than before), the water roller and the ink roller pressure check should be adjusted. The smooth surface of the water roller should be removed with an alkaline detergent. Similarly, the surface of the ink roller is often cured by the mordant in the ink, and the pores are smooth and smooth, and the traction force of the surface rubber suede and the ink-pulling ability of the ink for drawing ink are lost, and the ink-distributing and ink-receiving ability are lowered. More advanced, close to the water roller's first and second layout ink rollers, and the upper drive hard swing roller, if the surface is attached with colloid, it is easy to produce segmental hydrophilic deinking when there is too much water. , making the ink supply extremely uneven. This kind of situation often occurs in the water roller. If the ink layer is attached to the segment, the total water supply must be increased to obtain the amount of water in the ink-blocking section, that is, the water in the minimum and minimum water supply sections is still not available. Insufficient, it will be free from the occurrence of ink spots on the layout, but when there is too much water, some will exceed 50% and 100%. The ink tank roller has an ink button to control the amount of ink in the section. On the contrary, the water roller does not currently have a section control button, and only the ink roller section is blown to evaporate the emulsified water of the section of the ink roller as an excess of water. The balance of the role. Therefore, the pressure of the ink roller and the water roller and the rubber surface retain their respective oleophilic, hydrophilic, and elastic, roundness, which will affect the segment and even the overall ink balance. Some printing machines, especially above the platen ink roller, have gear-driven oscillating ink rollers themselves, but because the cleaning ink roller ink squeegee pressurizes the ink on the surface, after a long time, the diameter of the oscillating ink roller becomes smaller due to wear, so that the ink roller The surface speed is slow, does not meet the normal speed of the surface of the plate cylinder, causing the "brake" phenomenon during operation, which also causes dirty streaks of ink, which must be opened to reduce its slow sliding. Stain, therefore also affects the basic ink-and-wash balance, it is necessary to clean the hard ink roller.

Under the normal conditions of the water roller and ink roller of the printing machine, it is easy to talk about the ink balance. Otherwise, in the abnormal situation, the ink balance is in the "unbalanced balance". The operator should always pay attention to the water, but not too much. Insufficient dry spots on the water section cannot occur. Today's modern CIP 3 / CIP 4, the pre-press version of the printed ink mark section of the information, the original juice, the original taste to the printing machine, must have a set of different ink properties, printing room temperature and humidity, paper, printing pressure And the customer demand conditions, converted into the color of each color, each ink key area, this conversion curve changes every printing company, each different printing machine, and even each printing machine, has its experience The value conversion curve is placed on the computer software plug-in of the printing machine ink control system to make the most suitable conversion. After the printing, the ink supply of each ink key area should have a consistent and stable continuous ink supply, and will not be excessive. Insufficient, than the previous master used to visually measure the cumulative percentage of the print on the plate to adjust the ink key, has its absolute advantages and benefits. However, the premise is that the zero return and leveling of the ink slot key must be done very well. Otherwise, Gaoming Technology is built on the inconsistent starting point, and it is easy to change in a small amount of ink supply area, especially 5~10% of the ink key. Errors can cause many data to be garbled. Originally, the opening degree of the ink fountain key is inversely proportional to the rotation angle of the ink groove roller, so the average opening degree of the ink key is large, and the amount of ink groove roller rotation is relatively small; on the contrary, the average opening degree of the ink key is small; the ink roller The transfer of ink is relatively large, so the zero-inaccurate printing machine has a larger average opening of the ink key to reduce the interference of the error value. In the previous version, the ink mark is distributed according to the print pattern, so that the ink layers in the upper sections of the ink supply system are different in thickness of the ink layer. It is also necessary to adjust the color before the next section of printing, otherwise it will affect the color change during the calibration. Therefore, some printing machines have intelligent leveling function. When this version is printed with 10~20 mantissas left, the ink tank key will be averaged, such as 10%, 15% of the average ink supply, so that the lower The ink-intensive area with large ink consumption takes away more ink layers, leaving a relatively evenly-balanced ink layer to be used for the next print. If the amount of ink is evenly printed, the ink consumption is less than 15%. It is not necessary to do so to flatten the unevenness of the ink supply layer above.

Different from the gravure printing machine, there is a very fixed printing machine that can not change the ink thickness and flexo printing machine and the Anilox Roller micro-cavity roller. The distribution and depth of the ink of the Anilox Roller determine the thickness of the ink supply layer of the layout. In addition, letterpress printing and lithographic printing, from the gap between the ink tank and the ink tank key, the ink layer discharged from the ink layer is transferred five to seven times to produce ink on the surface of the printing plate, so the ink layer is inked. The flow of the ink formed by the key gap to the layout and the thickness of the ink layer on the printing plate itself, in addition to the printing density, also form a water supply. Whether it is a key factor in the balance of printing ink and wash with clean and appropriate color, and the proportional relationship between the ink layer and the water supply layer cannot be operated constantly, but also depends on the thickness change and temperature change of the ink supply system, and even It is improved in the case where the ink crust is dry, mixed with paper powder, and paper hair. On the other hand, in the case of water supply, there are changes in the temperature of the evaporation water, the degree of contamination of the water roller, the pH value, and the water absorption of the printing paper, the humidity in the air, and how much the water vaporizes. Therefore, mainly because of the amount of ink supply, there are still many different factors that affect the change of ink and water balance.

5. The wet water runs there in the printing.

Most printers and printing company managers, although they are very careful in managing the inks bought by a large amount of banknotes, where they go, whether there is good color reproduction and printability, but they rarely pay attention to them. Use tap water to flow in tons of wet water and where to go. Water removal: (1) Paper absorption, which is different due to different materials. Smooth coated paper absorbs less water, snow paper is second, light coated paper is more, non-coated paper is quite large, and porous There is no glue on the tissue paper, news paper absorbs more, on the contrary synthetic paper, plastic, coated paper, foil almost does not absorb water. The same type of paper, the high humidity itself absorbs relatively little water, the low moisture absorbs more water, and the total amount of water absorbed by the paper increases in proportion to the printing speed (printing). (2) Evaporation is a very important part of water consumption. The evaporation of the printing plate is closed due to the flatness of the lithographic printing machine, which makes the proportion decrease a lot. Instead, it is the blanket and the pressure. The cylinder surface has a non-printing part with water. The part is the larger part of the evaporation of water, especially the double diameter and triple diameter pressure. When there is no paper size, it will cause a larger percentage of water evaporation. (3) Evaporation of emulsified water in the ink layer of the ink roller is also indirect water evaporation. In addition to the evaporation of the printing area, the evaporation of the printing area will not increase due to the faster printing speed. The evaporation itself is closely related to the air pressure, wind disturbance, temperature and humidity of the printing machine room, which also causes the major factors of the balance of ink and water. Usually, the temperature is high, and the moisture of the natural moist water in the water roller, the emulsified water of the ink roller, the layout and other parts that are not printed to the surface of the tube will increase evaporation. High humidity will reduce the amount of water evaporation in all parts of the whole. Today, due to the cooling of the ink roller, the freezing and temperature control mode of the water supply system, and the temperature control of the printing machine room, the temperature changes little throughout the year. On the other hand, the humidity factor is often the cause of the printing machine room that is not easy to detect and less noticeable, but it often affects the water balance of the printing press. Many people mistakenly think that the air-conditioner installed with cooling is air-conditioning. A single tool that reduces the temperature of the printing room, sometimes removing excess water from the air. Real air conditioners should have four functions of cooling, warming in winter, dehumidification and humidification. Therefore, the functions of dehumidifiers and humidifiers are very important in air conditioning. It is not only necessary to cool down the air, but also hopes that the air conditioner will be under the action. In order to remove excess water, the room temperature is only 13 ° C in winter and the relative humidity is 90%. This is also a difficult printing condition, and the paper will be stretched and deformed. Therefore, it is not advisable to use the air-conditioner to dehumidify. It should be combined with a cold-discharge dehumidifier. It is not only dehumidification but also the function of improving room temperature. It is a good method. In summer, the air-cooling function has the function of cooling and dehumidifying one stone and two birds, keeping the humidity of the printing machine room stable, increasing the balance of printing ink and ink and the stability of printing quality. If the printing room is in the summer thunderstorm or rainy season, use a five or sixty-ton air conditioner to cool down, you can see that the water in the air is like a third of the water in the tap, because the water in the outside atmosphere, and two or three The four-color printing machine, the evaporation of water is in the spectrum of five or six hundred liters per day, so one day air-conditioner, removing 800~1,000 liters of water is nothing special. It can be seen that the humidity of the printing room is 50~60. % is more suitable in Taiwan, but in winter it is more suitable for 45~55%. Too much water consumption for printing presses will increase a lot.

Some people think that the faster the printing press, the more the water supply will increase, and some people think that the scale of the water supply on the printing press should be reduced. It sounds very contradictory, but each has its own statement and basis, and there is no conflict. Basically, the faster the printing machine speed, the more the printing quantity, regardless of the emulsification of the ink, the absorption of the paper, the increase of the temperature of the printing machine, the increase of the heat disturbance, and the increase of the amount of water used for evaporation is a fact. On the other hand, the water on the surface of the printing plate and the printing paper does not increase, so the speed is increased and the water demand is increased, but there is no proportional increase. If the water roller takes one water per print, Or take two waters, then the faster the printing speed, the more water will be taken, the equivalent consumption is OK, but in the evaporation of the consumption, the excess water will be redundant. On the other hand, if continuous water supply is used, the water is always sent to the humid system. If the ink emulsified water, paper absorption water and heat disturbance increase more water, it is necessary to use the speed of the fast water tank to increase some water supply, otherwise the water supply There will be insufficient, and how this program is written has different opinions.

6. lithographic plates, some causes

Ink and wet water are the main characters in lithography, and they play a dynamic blending role and role. But let us not forget that the more important thing is the "print plate". This piece can distribute and absorb water, and at the same time, it can absorb ink in the "printing part" where it is to be printed. This is a very important platform for water and ink to balance performance. .

More than two hundred years ago, this platform was built on limestone in the Austrian Alps and the southern Alps of Germany. This milky white porous limestone plate has good water absorption. After accidentally dropping the candle, using a cloth with grease and water, when wiping, it was found that not only the wax was not wiped off, but the water and oil were separated from each other by the water and oil. It also promotes the principle of semi-physical and semi-chemical printing of non-printed and printed parts by lithographic printing in a single plane. Although there is a long time, there is also a very brilliant era of hand-painted color printing, hand-printed color lithography in Japan, Shanghai lithograph posters, and European and American lithograph posters, lithograph prints are still popular, but heavy stone plates can only be handmade and mechanical. Platform printing, can not enter the high-speed printing. In 1903, Mr. Z.W. Rubel of the United States invented the Zhangye lithography press, which is now indirect printing Offset, using a zinc metal lithography. The zinc lithographic material, its hydrophilicity and lipophilicity is almost in the middle, so the non-printed part of the printing plate is not very easy to get dirty, and the lipophilicity of the printed part is moderate, compared with copper. A lot worse. In addition, the zinc plate material is easily oxidized, and once it is oxidized, it becomes a non-hydrophilic and non-inking zinc oxide. This wall material, which is incompatible with printing, is placed on the non-printed portion to become a gray spot. In the printed part, the white spot on the imprinted part is full. Therefore, it is necessary to use more water to keep the non-printed part of the printing plate clean on the zinc plate. On the other hand, it is necessary to prevent the plate from being printed before the plate making. The zinc on the printing surface after plate making, printing, and preservation is oxidized. Zinc plate grain is thicker than aluminum and easy to wear, and it is also unfavorable for long-length printing. Now using aluminum plates, it has excellent effects in terms of hydrophilicity. In addition, although the grain grain (sand) is very fine, it is deep, and the water content is large, and the oxidation is formed under anodizing. Aluminum hardness is up to 9 degrees, higher than most gemstones, second only to diamonds, and the oxygen-polarized aluminum oxide layer has strong abrasion resistance, and more porous micro-structures, forming triple-type water-containing non-printing The pattern part, with less moist water, can make reasonable ink-and-wash balance printing, changing from zinc material to aluminum material as printing plate material, which is very helpful for lithography, easier to operate, not easy to get dirty, and aluminum is lighter than zinc. a lot of.

In the early days of the PS version in the 1970s, 3M Company also introduced un-ground aluminum plates, which were difficult to control the plate moisture, so it was not successful. Another multi-layer version for lithography is also a highly successful plate that can withstand millions of sheets for packaging and metal printing. The outermost layer of the multi-layer version is a highly hydrophilic chrome metal, which is used as a non-printed part, and the bottom is copper (red copper) which has very good lipophilicity. There are three layers in the production, some are made of steel as the base, the surface is first plated with copper, then chrome plated, the plate is printed with a flat plate in the form of a flat plate, and then the chrome layer is etched in the unexposed part until the lipophilic The copper layer is barely exposed. In the future printing, the chrome layer can absorb moisture, and the printed copper layer can absorb oil, forming a full-metal stable and high-efficiency printing plate, and the abrasion resistance is three or fifty times that of the general drying plate. Materials such as zinc and aluminum. The full version of the double-layer version is made of chrome-plated copper, but the plate is not resistant to mechanical impact. Therefore, the steel is a practical three-layer version, but it has never been introduced in Taiwan. Because the plate cost is high, the printing volume is not big enough. Enough to use such plates.

Nowadays, the PS plate and CTP plate are the mainstream plates produced by lithography. In the early PS plate, there are many difficulties. For example, the acid and alkali values of the printing paper are not resistant to paper, too acid and too alkali will fall off, so the moist water should be done. The change is due to the fact that the paper coating layer and the pulp filler chemical dissolved from the printing paper surface will be traced from the moisture of the rubber blanket surface to the printing plate, the water roller and the water supply tank to form a chemical accumulation. The printing pattern is corroded and not durable, so thousands of sheets can not be used. Therefore, it is effective to make the printing glaze, or to replace the sink liquid, clean the wet system, and replace the printing paper. I remember that when I printed the classmates in the factory, I printed three or four sets (manually loaded) every hour, and printed three or five hundred sheets each time. I used the water roller to wet and dissolve the glue on the plate for half a day. The printing pattern is not inked, mainly because the wet water glue is too much and the acid is too strong, so that the ink of the ink supply system loses a lot of oiliness due to too much glue mixed, so the manual washing is used to remove the glue, and the ink roller is cleaned. Water roller, re-printing to work smoothly. If the tank liquid tank has not been used for a long time, it will often ferment and grow mold, which is not conducive to the role of moist water.

In the non-printed part of the plate, it is necessary to apply glue before printing, so that a thin layer of arabic acid glue is attached to it, and the long-term water absorption of the colloidal molecules is exerted. Therefore, it is called lithography that is not only incompatible with ink. In addition to the principle, there are also many principles of meta-chemical action.

7. Conclusion

An excellent lithographic press operator, today's technologically advanced era, although with many advanced precision machinery, motor to electronic equipment, under the control of many hardware and software, even the very difficult ink roller swing amplitude, pendulum phase, You can make fine-tuning change control on the console. Others such as the turning mechanism, the front and rear printing presses, the phase change of the cylinder and the jaws are opened and closed by the normal paper, and the twisting and turning back to the tail of the paper is extremely accurate. The complicated control work can be done by modern printing presses, not to mention the size of CIP 3 /CIP 4, ink key information reception and pre-adjustment. Therefore, Manroland changed the pad printing machine to press only one Start button, and all the projects were executed under the programmed system. But the advantage of our lithographic printing press, the use of thin low-cost aluminum, and high-precision 2400dpi, 3000dpi high-precision CTP platesetter, can make a plate from 500mm to 2860mm, both have good overprint precision, the plate from Enter to install fully automated.

The printing machine works for four or fifty years, and I want to find ways to develop the water film thickness of the wet water on the printing plate. According to the visual observation of the previous teacher, it is estimated that the amount of moisture on the non-printed surface of the printing plate is determined by the gloss of the side of the printing plate at an angle of about 10°, and it is easier to match the printed surface of the printed plate. Lose water in the block, do monitoring and add water. In this area, the prints are kept clean, and the total water supply is reduced. If the water is tested, the dry spots will appear immediately, indicating that the water supply has reached the critical point of the lower limit of the danger zone. It is not easy to raise the water supply higher. Produce defective products. The masters often have to change depending on the weather. At noon and afternoon, the temperature is high and the water is raining. When the wind blows over the window, the printing plate will dry up near the window, and quickly sprinkle water to make up the water, so these people’s experience, Observing, in conjunction with the slower and slower production rhythm at the time, it is feasible to control the monochrome machine and the two-color machine, because these have a deep understanding of the ink and water balance characteristics of each environment and various blocks of the machine and the countermeasures are formed. A "work" that can be produced. Today, Zhang Yeping Printing Machine is not only four colors, six colors, even eight colors and ten colors. It is not only impossible to use manual inspection to visually check the water film of each printing plate on the tube, and the printing machine is now entering. In a small number of diverse production environments, it is not allowed to use manual observation of the water supply of various color plates. Instead, it is based on the speculation of workers, which is a large cover for high-priced, high-productivity flat printing machines worth tens of millions and hundreds of millions. The door is also a very ironic thing. The normal printed sheet was printed in the last minute. After 250 or 550 sheets in the next minute, it was a pile of waste prints that were too dry and too wet! This very drastic change does not exist in high-speed gravure and flexo press production. Therefore, using optical technology, infrared measuring instruments, microwave reflection and other technologies, I want to measure the research and development technology of the water film thickness of each block on the lithographic printing plate. Although there are so many high-tech measurement procedures, there is still no one today. , the work into practical control. Even with the Anilox Roller micro-acupressure ink supply roller, there is a more uniform ink supply layer printing method, but there is no successful control of the ink balance, but special ink must be used for normal printing. It can be seen that this difficult picture of ink and water balance is still based on the experience of high-tech lithographic printing presses. This is the operation of hundreds of thousands of printing presses. Every day, it is enough to do enough to operate the production. High-quality products, high-yield prints, this is a fact and a very helpless thing. Therefore, we should adjust the water supply, ink supply and roller elasticity, precision, pressure and surface condition of the printing machine, and then improve the ink and water conditions of the printing plate, and control the temperature and humidity of the printing machine room, ink and consumables. The quality management, coupled with the CIP 4 data, believes that under the helpless conditions, perhaps we still have to use lithography to continue printing for another 50 years, a hundred years is not necessarily, this ink and wash balance struggle history will continue to write Go on.