Related influencing factors of ink color of the ho

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Related influencing factors of printing ink color

release date: Source: China paper

the visual effect of printing ink color is one of the important factors to measure the quality of printing,. There are several situations in which printing coloring has a direct impact on printing ink color. Today, China paper industry takes you into packaging printing to learn more about the relevant contents

(-) influence of printing ink layer thickness and viscosity on printing ink color

appropriate printing ink layer is an important measure to ensure the quality of printing ink and prevent printing from sticking. If the ink layer is too thick, its viscosity is bound to increase, which is easy to produce paper fuzzing and affect the evenness of the ink color of the print. If the ink layer is too thin and the ink viscosity is insufficient, the ink color printed will be too light and the visual effect of the print will be poor. With the extension of the printing machine rotation time or the acceleration of the printing speed, the friction coefficient increases, and the ink temperature will gradually increase. As a result, the ink will become thinner and its viscosity will decrease accordingly. Therefore, these conditions must be taken into account when inking to ensure that a relatively balanced printing ink color can be obtained for a batch of products. However, in the actual production process, the decline of ink viscosity is inevitable. Often, the ink color of the printed products is thick at the beginning of printing, and then becomes lighter. 2. If the refrigeration compressor fails to start up and the intermittent operation takes place for a period of time, the rotation angle of the ink transfer iron roller is suddenly shut down to increase the ink supply, so as to keep the consistency of the ink color before and after. In addition, in order to prevent the ink viscosity variation from being too severe and affecting the ink color balance of the printed product, the contact between each rubber roller and the ink string iron roller shall not be too tight, and the colloid shall not be too hard, so as to minimize the friction heat and maintain the appropriate ink concentration

(II) the influence of printing pressure on the ink color of printed matter

printing pressure is one of the important conditions to realize the transfer of imprints. Because the printing plate surface is not absolutely flat, the paper surface also inevitably has subtle concave convex and uneven thickness. If the printing pressure is insufficient or uneven, the printing ink color on the plate will inevitably appear uneven. Therefore, the ideal printing process is based on the "three levels" (that is, the printing plate is relatively flat with the inking roller and the lining body to obtain good contact conditions), and the thin ink layer can obtain a more uniform ink color on the print through the effect of balanced printing pressure. If the printing pressure is insufficient or uneven, there is poor contact between the lining body and the printing plate surface. Increasing the ink delivery can meet the visual effect of the printing plate ink color, but this will not only increase the ink consumption, but also cause the printing product to be sticky and dirty, which is not desirable

(III) influence of cot quality on prints and ink color

as far as the embossing and flat printing process is concerned, whether a print can obtain an ideal ink color is closely related to the quality of cots. There are fiveorsix or even more than 10 color printing equipment equipped with three types of ink transfer rollers, ink leveling rollers and inking rollers. Among them, the ink transfer rollers and inking rollers have a greater impact on the shade of ink. The quality of COTS is mainly reflected in the elasticity, so its heat dissipation effect is limited, viscosity, center point and surface finish, and the viscosity mainly affects the ink color. In the printing process, the cots must maintain a certain viscosity to ensure that the amount of ink coated on the plate is uniform in each printing cycle. However, in the actual production process, the viscosity of the cots is not stable. First, the increase of paper dust in the ink affects the viscosity of the colloid; Secondly, the viscosifier (glycerin) on the colloidal surface is lost with the increase of temperature and the extension of service time. The viscosity on the surface of the cot is gradually reduced, and the ink absorption performance is correspondingly reduced, thus affecting the balance of the ink color of the print. Therefore, polyurethane Cots with stable quality should be used for printing plate products. If bulk products are printed, the cots shall be cleaned in time

(IV) the influence of different paper cleanliness on the ink color of printed matter

in fact, the relationship between paper and ink is complex. If only the ink color of a book is considered, it should be noted that the smoothness of the paper surface has a certain relationship with the ink color. If the pressure of each version is the same, the smoothness of the paper surface is inversely proportional to the ink consumption, and the ink absorption of smooth fans is small, on the contrary, the ink absorption is large. Therefore, if there is a difference in the smoothness of the front and back surfaces of the paper, the method of increasing the ink volume and pressure should be adopted as appropriate to make appropriate adjustments. In printing, it is customary to print the smooth surface first, and then the rough surface. When printing, increase the ink amount appropriately to achieve good printing effect. Br

(V) influence of light change on printing ink

generally, there are three light sources to identify printing ink: sunlight, fluorescent lamp and electric lamp. The light emitting conditions of these three light sources are different, and the color of the light emitted is the most important in the later service. The eyes are pure white, the fluorescent lamp is white with blue, while the electric lamp is red and slightly yellow. Although Liang Xiaoli, general manager of the fluorescent and fluorescent light source companies, said that they are somewhat similar, the differences between the two should be taken into account when identifying products with high quality. The influence of light on the identification of ink color is not only the light source, but also the intensity of light and the irradiation angle. Under the same light source, the intensity of the reflected light on the illuminated sheet is mainly determined by the distance between the sample sheet and the light source. The near is strong and the far is weak. The correct irradiation angle should be that the incident angle is equal to the reflection angle. The light irradiating on the sample inevitably has partial refraction, but it has little effect on the identification of ink color. When identifying the ink color of printed matter, whether in the daytime or at night, it should be carried out under the condition that the intensity of the light source and the irradiation angle are the same, so as to prevent color deviation or ink color variation caused by ink mixing errors

(VI) influence of incorrect overprinting on ink color

whether the overprinting of various color plates is accurate or not will have a great impact on the printing hue. Overprint accurate hue effect is also good, overprint inaccurate print hue will be biased. This is due to the position difference of overprint of various color points, which will inevitably produce visual color difference. Therefore, overprinting of the printed color products must be accurate to ensure that printing hue meets process requirements. In order to prevent inaccurate overprinting and color deviation caused by paper expansion and variation, multi-color machine should be used to complete color stacking printing at one time for point color products with high quality requirements, so as to improve overprinting quality. In addition, the paper should also be hung and dried to reduce the occurrence of sheet variation in the printing process

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