The Influence of Production Factors on the Printing Ink of Carton Paste

The uniform ink color, color, and color consistency of preprinted carton face paper are the basic requirements for the quality of carton products. Throughout the carton printing process, the following conditions are closely related to the quality of the printing ink on the paper. Therefore, a correct understanding and understanding of these factors and the relationship between the quality of white paper printing ink, for accurate control of the paper printing ink color, improve the printing quality of the carton products, is of great significance.

The effect of white paper on the color of paper

Whiteboard paper is the main printing material for preprinted cartoned paper, and its surface color looks white. However, a closer look usually has a certain color cast in the white, such as white in the blue phase, reddish phase, yellowish or greenish phase and so on. In particular, different batches, different varieties, different manufacturers, and even whiteboard papers of the same grade and the same type produced by the same manufacturer may all have more or less inconsistencies in the hue and adversely affect the stability of the quality of the paper printing ink. . When we reprint printing preprinted cardboard paper or other paper container packaging products, due to the deviation of the color of the white paper, the printing ink color appears the corresponding error phenomenon. For this unavoidable problem, it is often necessary to compensate and overcome through the control of ink volume and pressure or adjusting ink color equal methods. However, the control of ink volume and pressure can only be trace, limited, and passive, and it is easy to produce other printing defects. Relatively speaking, adjusting ink hue is a relatively good way to solve the effect of the difference in white paper's hue on the printing ink color of paper. However, the correct adjustment of the hue of the ink requires the operator to have a good technical quality and a solid, rich production experience in order to be able to better deal with the effect of white paper color on the printing ink. According to the author's experience in production and quality management, before the printing, the color of the white paper to be printed should be compared with the original (the color of the white paper). Observe the deviation phenomenon of the paper color and see what the paper color is. And the degree of color cast in order to take appropriate technological measures to adjust. For products that print spot colors, when the paper color appears reddish, it may be appropriate to consider reducing the amount of red ink when transferring ink.

Effect of Difference of Paper Gloss on Printing Paper Ink

The printing process shows that the gloss of the face paper has a great relationship with the quality of the printing ink. In the printing process, when there is a difference in the glossiness of the surface paper, such as a rough surface of the paper surface, the printing ink color appears shallow phenomenon, especially when the quality of the printing paper surface is poor and the paper dust surface is large and the color is not pure. It is more likely to produce chromatic aberration. This is because, under the same printing pressure conditions, the glossiness of the face paper is inversely proportional to the ink absorption amount of the printing plate surface, and the ink amount of the glossy face paper is small, and vice versa, the ink absorption amount is large. Therefore, if there is a large difference in the gloss of the paper surface, appropriate methods should be taken to increase the amount and pressure of the printing ink, and appropriate compensation and adjustments should be made.

The Effect of Paper Powder and Lint on White Paper Printing Ink

If the surface strength of the white paper is poor, it is easy to cause powder dropping and hair loss. In the printing process, the phenomenon of stacking and stacking of rubber is likely to occur, which will inevitably affect the normal transmission of ink. The rubber roller and the water roller are also easy to absorb paper. Hair and paper scraps cause uneven ink and water. The occurrence of these undesirable phenomena directly affects the evenness and stability of the printing ink. Therefore, when printing large-area color products, high-quality whiteboard paper with high quality must be used for printing. If customers require the use of low-quality whiteboard paper for printing, the speed and ink viscosity of the printing press can be appropriately reduced, and the excess color group of the multicolor printing machine before the color group can be used to perform water and air imprinting on the whiteboard paper. The processing of the process to achieve the reduction of powder off, hair loss on the negative impact of paper printing ink quality.

Effect of Layout Overprint Accuracy on Printing Paper Ink

The practice of the process shows that the registration conditions of the screen print layout will have a certain influence on the quality of the printing ink of the paper. Because the dot area and the screen angle of the anilox layout are different, if there is a difference in the position of the overprint, the result of the overprint of the layout is not the same, and the color rendering effect of the printing surface must also be different. Therefore, the overprinting of web products requires the product's overprinting to achieve accurate and consistent results. Therefore, it is necessary to adopt necessary process control measures during production to effectively prevent the change of the expansion and contraction of printed sheets; at the same time, it is necessary to properly use and maintain the machines. To ensure the stability of the machine's paper feeding mechanism, pull gauges (side gauges), pre-registration positions, delivery teeth and drum clenching work, to prevent the stability of the quality of surface printing inks due to inaccurate product overprinting.

Effect of Printing Pressure on Printing Paper Ink

Printing pressure is one of the important conditions for achieving ideal imprint transfer. Since the surface of the printing plate cannot be absolutely flat, the surface of the whiteboard paper is inevitably subject to fine irregularities and uneven thicknesses. If the printing pressure is insufficient or uneven, The ink layer on the layout is difficult to transfer completely and evenly to the surface paper, which will cause the print layout to appear uneven. Therefore, the ideal printing process is based on the "three levels", that is, the surface of the plate, the ink roller and the surface paper (including the liner) are required to be relatively flat, so that a thinner ink layer can achieve the effect of equalizing the printing pressure. Get a more uniform ink on the print. When the printing pressure is insufficient or non-uniform, when the contact between the lining and the plate surface is poor, the quality of the printing ink satisfying the visual effect can be obtained only by increasing the amount of ink transferred to the printing plate, but this will not only increase the ink. The amount of consumption, it is easy to make the printed product appear sticky ills, it is not desirable. Therefore, the use of moderate and uniform printing pressure is the basic condition for improving the quality of printing ink in cartons.

Effect of Printing Ink Layer Thickness and Viscosity on Quality of Paste Printing Printing Inks

In general, a moderate and uniform printing ink layer is an important measure to ensure the quality of the printed ink and prevent the printing from being dirty. The daily printing process shows that when the ink layer is thicker, its viscosity increases accordingly. This can easily cause the paper surface to fall out of powder and pull the hair, which in turn affects the evenness of the ink. However, if the printing ink layer is thin and the ink viscosity is too small, the ink color of the printing product becomes lighter, and the visual effect of the printing product is also poor. On the other hand, with the increase in the rotation time of the printing press, and the increase in the printing speed, the increase in the coefficient of friction of the machine, the ink temperature will gradually increase, so that the viscosity of the ink will decrease accordingly. Therefore, the ink must be taken into account when adjusting the ink. These factors to ensure a balanced print ink. However, in the actual printing process, the phenomenon of ink viscosity decrease is unavoidable, and the ink of the printing product is often rich at the beginning of printing, and then gradually fades. In this case, a more balanced and stable printing ink color can be obtained by appropriately adjusting the rotation angle of the ink transfer roller.

The effect of the quality of the rubber roller on the printing ink of the paper

In the traditional printing process, whether the ink can obtain the ideal ink color, the quality of the rubber roller has a crucial connection. The machines for printing color products are generally equipped with three components: an ink transfer roller, an ink distribution roller, and an ink roller. The ink printing roller and the ink roller are the major factors that have a significant influence on the quality of printing ink. The quality of the rubber roller is mainly reflected in the elasticity, stickiness, the center of the circle and the surface finish, among which the main effect of the ink shade is stickiness. During the printing process, the glue roller should maintain a certain viscosity in order to ensure that the ink applied to the printing surface is the same during each printing cycle. However, in the actual production process, the cohesiveness of the rubber roller is not stable. The reason is as follows: First, due to the increase of paper dust in the ink; Second, the tackifier (ie, glycerin) on the surface of the rubber roller will increase with temperature and use. When the time is extended and lost, the viscous surface of the rubber roller will gradually decrease, and the ink absorption performance will also decline accordingly, thus affecting the balance of the ink color of the printed product. Therefore, printed color products should use a more stable quality polyurethane roller. If printing large quantities of products, the rubber rollers should be cleaned at a proper time to remove the impurities on the rollers to ensure the printing quality of the products.

Effect of Light Source Difference on Printing Paper Ink Color

Usually identify the surface of the light ink printing paper, mainly daylight (natural light), fluorescent and incandescent lamps. Because of their different light source characteristics, the color of the emitted light is also different. For example, the sunlight is pure white, and the observed color is relatively accurate. The white light of the fluorescent lamp is greenish and close to daylight. The accuracy of observation of color is second only to natural light. The incandescent light has a yellowish color in the 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. In addition, the effect of light on the identification of ink is not only the characteristics of the light source, but also has a great relationship with the light intensity and the angle of illumination. Under the same light source, the intensity of the reflected light on the illuminated sample sheet is mainly determined by the distance between the proof and the light source, and 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. Perform with the same irradiation angle to prevent ink misregistration from causing color shift or ink inconsistency. Since there are certain differences between the electric light source and the natural light source, the color observed under the natural light source conditions is relatively accurate. Therefore, the carton products with high requirements for the printing ink color should preferably be arranged for production during the day so that the control of the printing ink color can be more accurate. .

Effect of Printing Temperature on Printing Paper Ink

Under the condition of high printing temperature, the printed ink tends to appear lighter. This is because the ink has thixotropy characteristics, when the printing temperature is high, the ink appears thinning phenomenon, making the printing ink fade. Conversely, when the printing temperature drops, the ink will thicken, and the facial printing ink color will also darken. During the process, we found that in the printing process, especially when the temperature is low and the speed of the machine is slow, the ink in the ink fountain is often not smoothly conveyed, and the ink supply is not normal, resulting in the ink of the printing product becoming more and more. The lightness has affected the stability of the quality of printing ink. This is the main performance of the thixotropy of ink. In this regard, it should be noted that the ink in the ink fountain is frequently agitated to maintain a continuous and uniform fluidity, ensuring that the ink quality of the product is stable. Some inks in the transfer coating process, due to thixotropy is too large, in the printing process in the condition of increasing temperature, the ink on the machine is more and more dilute, the Indian ink printing more and more light, almost impossible to adjust, this The inks are not suitable for printing full-size and large-area color prints in the field. Therefore, printing colored carton products should pay attention to choose high-grade ink, because its thixotropy is relatively stable, help to improve the quality of printed ink. In addition, controlling the printing temperature is an important part of reducing the thixotropy of ink and ensuring the ink color of the printing product is stable. In order to prevent the ink viscosity variation from being too severe and affect the balance of the ink color of the printed product, the production workshop of the printed color product should use the constant temperature and humidity conditions as much as possible; the speed of the printing machine should not be adjusted too high, and the printing should be performed at a constant speed; Do not use as much as possible to remove the unused roller; the contact pressure between the rubber roller and the iron roller is not adjustable too tight; do not use the hard rubber roller; the contact between the roller, the roller and the printing plate should be appropriate In order to minimize the friction coefficient during the printing process, to minimize the effect of frictional heat on the ink characteristics, to reduce the thixotropy of the ink on the paper printing ink.

In summary, the factors influencing the quality of the paper printing ink are various, and the presence of any kind of undesirable factors can easily change the ink color of the carton product. Therefore, the correct understanding of the factors that affect the inking paper printing ink and the implementation and control of the production process technology and operating technology measures can not only effectively reduce the chance of changes in the printing ink color during the production process, but also can better prevent A variety of print quality defects have arisen to increase the efficiency of production of face paper printing.

Kang Qilai Global Corrugated Industry - Issue 10, 2006