Analysis of Influencing Factors of Printing Color Difference (Part 2)

Fourth, poor ink supply device caused by the color difference

When the center of the iron roller is poor or there is wear and deformation, the ink fountain plate also appears wear and deformation, and there is a defect in the mechanism for controlling the rotation of the ink fountain roller, which causes the ink flow in the printing process to be unstable, and can also cause the printing color difference to occur. Should take appropriate measures to deal with, in order to prevent the production of color. In addition, we should pay attention to reasonable adjustment to the ink supply device, the ink in the ink fountain to increase or reduce the total amount of delivery, there are two ways to adjust, the first is to adjust the gap between the ink fountain and the transfer of ink (to ink) to achieve the gap; The second is by adjusting the size of the rotating arc of the transfer roller. In the case of thinner inks, it is not advisable to adjust the gap between the steel sheet and the iron roll so as to prevent ink leakage due to ink leakage. When adjusting the ink volume, the rotation arc of the transfer roller should be controlled between 1/2 of the adjustment range. This will allow the ink volume to be flexibly adjusted when the ink density changes during printing. The uniform color of the product prevents the problem of printing color.

V. Printing color difference caused by poor dampening factors

Lithographic printing process if the dampening discomfort, but also prone to color printing phenomenon. For example, when there is an eccentricity in the water roller, since the contact with the plate is inconsistent, it is easy to make a difference in the amount of water supply on the plate. In addition, if the water roller sleeves use aging or adsorption ink, impurities, it will affect the water roller's water absorption and even transfer of the fountain solution. In addition, if water leakage occurs in the water bucket device, it will also affect the uniform transport of moisture on the printing plate surface. If these unfavorable conditions exist, the even and stable transmission of the layout ink will be damaged, and the ink color of the printed product will be different. Therefore, the dampening system must maintain a good state, should wash the ink roller frequently, the use of aging water roller cashmere cover should be replaced in order to better prevent the production of color.

Sixth, poor printing materials caused by poor color printing

In the daily printing: In the art, we can find that the difference in the material quality of the substrate is one of the reasons for the color difference in the printing. For example, the difference in the glossiness and the hue of the substrate will cause the problem of color printing. Taking embossed aluminized paper as an example, the embossing depth of the aluminized paper surface is inconsistent, and the difference in the hue of the aluminum spray layer can cause inconsistency in the print color effect. Therefore, printing color products should try to use gloss and hue - consistent substrates. If objective factors exist, the same batch of products use two materials with different shades and gloss, and separate printing should be paid attention to, and the printing ink color of the two materials should be basically prevented by adjusting the ink hue and printing pressure in the process. Print color production

Seventh, poor color printing caused by the machine

If a worker wants to do good, he must first sharpen his tools. The good performance of the picking machine is a reliable guarantee for improving the quality of printing ink. However, if the machine has a bad condition, such as imprinting system work is not stable, so that the pressure of each sheet is inconsistent, and the paper feeding system is not normal, frequent occurrence of empty, multiple sheets and other failures in the printing, it is most likely to cause printing The appearance of color aberration problems.

Therefore, we should always pay attention to equipment maintenance and maintenance, we should pay attention to the lubrication of the machine key parts, such as roller shaft and other parts to prevent wear, so that the imprinting mechanism to maintain a better working condition, so that the printing pressure remains constant. It is necessary to adjust the feeder and air pump device so that the air path is unimpeded and the sheet is normally sucked to ensure that the paper is fed smoothly and no vacancy occurs. This can better prevent the occurrence of printing chromatic aberration.

Eight, poor printing caused by printing color

Printing plate is one of the basic elements of the quality of graphic reproduction. In the printing process, the printing plate can only maintain the stability of the ink transferred on the plate. During the printing process, if the layout of the screens is distorted or worn and deformed, the lines appear to wear out and expand. In this way, due to the change in the amount of ink sucked on the layout, the ink color of the prints will inevitably be deviated. So, color printing products should pay attention to control moderate printing pressure, and adjust the rubber roller, water roller contact pressure plate, the pressure is too great to prevent increased wear of the printed page, before and after the printing ink product deviation. On the other hand, it should be possible to adopt printing materials with good smoothness, which are not easy to lose powder and lose hair. This is also one of the technical measures for effectively avoiding the wear and deformation of the printing plate in printing, which is favorable for preventing the production of printing color aberrations.

Nine, poor lining caused by printing color

Lining is the medium for blotting and has a great influence on the printing ink color. If the lining elasticity is too bad, it will be difficult to be reset after the sinking deformation occurs with the increase in the number of printing times; therefore, the printing ink before and after the printing will be inconsistent. On the other hand, if the printing surface is covered with a layer of ink and paper impurities, the ink color of the ink will be deviated. Therefore, printed color products should be selected with a certain elastic lining, and timely cleaning of the blanket surface blots or paper scraps, in order to prevent poor lining caused by printing color.

Ten, light source characteristics and different viewing angles to identify differences in print color

Usually identify the light source of printed ink, mainly sunlight (natural light), fluorescent lamps and incandescent lamps and other light sources. They emit different light source characteristics, and the emitted light color is also different. For example, sunlight is pure white, and the observation of the color is relatively accurate. The light of the fluorescent lamp is white and blue, similar to sunlight. The incandescent light has a yellowish color in red, so it is difficult to accurately identify the color. Although sunlight and fluorescent lamps are somewhat similar, the difference between the two should also be considered when identifying high-quality color products. The effect of light on the identification of ink is not only the characteristics of the light source, but also has a lot to do with the light intensity and the angle of illumination. Under the same light source, the strength of the reflected light on the illuminated sample sheet is mainly determined by the distance between the proof and the light source, while the strong and distant ones are weak. The correct irradiation angle should be that the angle of incidence is equal to the angle of reflection. Irradiation on the sample sheet will inevitably result in partial refraction, but it does not have much influence on the ink color. When identifying the ink color of the printed product, whether it is day or night, the intensity of the light source should be strong or weak. The situation is the same as the irradiation angle. In addition, in identifying the ink of printed products, especially the printed paper of aluminized paper, the color of the control sample in the middle of the printing, the difference between the color of the identified sample and the color of the identified sample should be correctly distinguished. For example, the printing sample should be placed on the standard sample. Next to the color comparison, because the difference in the viewing angle is large, it will produce a certain visual error, easily inaccurate identification of ink. The printing ink samples are superimposed on the standard sample for comparison. Since the observation angle difference is small, the color identification is relatively accurate. This point the author has profound experience, such as the author sent a trademark sample (the same as the background of the main label and the back of the standard) to the customer to confirm, the customer after seeing the standard sample placed side by side, that the main label and the back of the background is obvious The color difference raised an objection. After the author superimposed the back label on top of the main label, he felt that the color was closer than the color, so the customer finally signed and confirmed it. The process practice shows that the differences in light source characteristics and observation angles will directly affect the accurate identification of colors. Therefore, products with higher requirements for printing color quality should be best arranged during the day, and should be used when comparing colors. The angles are repeatedly observed and compared to prevent improper ink control during the printing process, resulting in inconsistent ink color of the products printed before and after.

In summary, a correct understanding of the factors that produce chromatic aberration in printing, and through the combination of good printing process technology and operating technology, can not only effectively avoid the occurrence of such or such printing defects, but also can better ensure the quality of the ink of color prints. .

(Kang Qilai)

China Packaging News

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