Printing ink effect

The effect on the ink color of printed products

Plate printing is a widely used production process. How to improve the quality and production efficiency of color prints is worthy of analysis and discussion.

The visual effect of printed ink is one of the important factors to measure the quality of printed matter. The following are the conditions that directly affect the ink color of printed products.

(-) Effects of Printing Ink Layer Thickness and Viscosity on Printing Ink Color

The moderate printing ink layer is an important measure to ensure the quality of the printed ink and to prevent the print from sticking. If the ink layer is thicker, its viscosity will inevitably increase, and it will easily lead to paper pull, which will affect the evenness of the printed ink. If the printing ink layer is thin and the ink viscosity is insufficient, the printed ink will be too light, and the visual effect of the printed product is also Just bad. As the printer's rotation time increases or the printing speed increases, the friction coefficient increases, and the ink temperature also gradually increases. Therefore, the ink becomes thin and its viscosity decreases accordingly. Therefore, these conditions must be taken into consideration when transferring ink to ensure that a batch of products can obtain a relatively balanced printing ink color. However, in the actual production process, the decrease of the ink viscosity is unavoidable, and the ink is often dark at the beginning of the printing process and fades afterwards. This can be achieved by appropriately adjusting the rotation angle of the ink transfer roller. The amount of ink keeps the shades of ink before and after. In addition, in order to prevent the ink viscosity variation from being too severe and affect the balance of ink color, the contact between each roller and the iron roller should not be too tight, and the glue should not be too hard to minimize frictional heat and keep the ink properly. concentration.

(b) The effect of printing pressure on ink color of printed products

Printing pressure is one of the important conditions for imprint transfer. Since the surface of the printing plate is not absolutely flat, the surface of the paper will inevitably contain slight irregularities and uneven thickness. If the printing pressure is insufficient or uneven, the printing on the plate will be printed. Ink will inevitably appear uneven. Therefore, the ideal printing process is based on the "three levels" (ie, the plate surface and the ink roller and the lining body are relatively flat to obtain good contact conditions), and the thinner ink layer is used to achieve a balanced printing pressure. , to get a more uniform ink on the print. If the printing pressure is insufficient or uneven, there is a poor contact between the lining body and the printing plate surface. By increasing the amount of ink to be fed, the visual effect of the ink on the printing surface can be satisfied, but this not only increases the consumption of ink, but also occurs easily. Dirty printed products are undesirable.

(3) The effect of the quality of the rubber roller on the print and ink

As far as the embossing and peaceful printing process is concerned, whether the printed product can obtain the ideal ink color has a close relationship with the quality of the rubber roller. The equipment for printing color prints is equipped with an ink transfer roller, an ink roller and an ink roller. There are five or six or even more than ten ink meter rollers, of which the ink roller and the ink roller are the most influential factors in the ink shade. The quality of the rubber roller is mainly manifested in the aspects of elasticity, stickiness, roundness, and surface finish, while the main influence on ink density is stickiness. In the printing process, only a certain degree of stickiness of the rubber roller is ensured, so as to ensure that the amount of ink applied to the plate surface is uniform during each printing cycle. However, in the actual production process, the cohesiveness of the rubber roller is not stable. First, due to the increase of paper dust in the ink, the viscosity of the colloid is affected; secondly, the viscosity agent (ie, glycerin) on the surface of the colloid increases with the temperature and the use time. Prolonged and lost, the adhesive surface of the roller gradually reduces the viscosity, the corresponding decline in the ink absorption performance, thus affecting the balance of ink ink. Therefore, the printing plate product should use a more stable quality polyurethane roller. If printing bulk products, clean the rollers at a proper time.

(4) The influence of the difference in paper quality on the ink color of printed products

In fact, the relationship between paper and ink is complicated. If only considering the shade of ink in a book, it should be noted that the smoothness of the paper surface has a certain relationship with ink. If the pressure of each plate is the same, the smoothness of the surface of the paper is inversely proportional to the consumption of ink, and the amount of ink sucked by the sleek lover is small, and vice versa. Therefore, if there is a difference in the smoothness of the positive and negative sides of the paper, the method of increasing the amount of ink and the pressure should be taken as appropriate and appropriate adjustments can be made. The printing is used to print glossy first, and when the rough surface is printed later, the pressure and the ink supply are appropriately increased, so that both the positive and negative ink colors have an ideal visual effect. Practice has shown that the effect of the above method is much better than simply increasing the amount of ink delivered, and the printing quality is better.

(5) Effect of light changes on the ink color of printed products

The light source that normally identifies printed ink is three types of sunlight, fluorescent light and electric light. The light emission of these three light sources is different, and the color of the emitted light is different. The eyes are pure white light, the fluorescent light is white with green, and the electric light is reddish and slightly yellowish. Although sunlight and fluorescent light sources are somewhat similar, the differences between the two should be taken into account when identifying higher quality products. The effect of light on the identification of ink is not only the light source, but also the light intensity and the irradiation angle. Under the same light source, the intensity of the reflected light on the sample sheet is mainly determined by the distance between the proof sheet and the light source, and the strong and weak ones are weak. The correct angle of illumination should be the angle of incidence equal to the angle of reflection. Irradiation on the proofs will inevitably result in partial refraction, but it does not have much influence on the identification of ink. In the identification of ink color, whether it is day or night should be carried out in the same light intensity and irradiation angle, in order to prevent ink mis-correction caused by color cast or before and after the ink variation.

(6) The impact of overprinting on ink color is not allowed

The fineness of products produced by the outlets, and whether the overprint of various printing plates are accurate, will have a great influence on the printing hue. The accurate hue effect of the overprinting is also good, and the overprint of the overprinted print will be deviated. This is due to the difference in the position of overprinting of each color dot, which inevitably produces a visual color difference. Therefore, for printing textured color products, overprinting must be precise to ensure that the printing hue meets the process requirements. In order to prevent the misalignment and variation of the paper, the misalignment and color misalignment caused by the paper cannot be ensured. For the dot quality products with high quality requirements, a multi-color machine should be used to complete the overlap color printing at a time to improve the overprint quality. In addition, it is also necessary to carry out hanging and drying treatment of the paper in order to reduce the occurrence of variation of printed sheets in the printing process.