How to make the ink color of a batch of printed products or batches of printing consistent in printing is a basic requirement and an important problem. For the manufacturer, the color of the packaging used in the product has become an important means and symbol for identifying the product (even the logo of the company). If the appearance of the product packaging looks different, the consumer may think that the quality of the product is unstable, and even suspect the authenticity of the product. Therefore, the well-known enterprises of these enterprises attach great importance to the color of the product packaging, and require that the ink color must be stable and consistent. How to make the ink color of a batch of printed products or batches of printing consistent in printing is a basic requirement and an important problem. For the manufacturer, the color of the packaging used in the product has become an important means and symbol for identifying the product (even the logo of the company). If the appearance of the product packaging looks different, the consumer may think that the quality of the product is unstable, and even suspect the authenticity of the product. Therefore, the well-known enterprises of these enterprises attach great importance to the color of the product packaging, and require that the ink color must be stable and consistent. The consistency of color can only be said to be relative. Strict control of the same batch of color difference is more difficult, and strict control of color difference between large batches or batches is more difficult. Plastic flexible packaging gravure printing is mostly multi-batch printing and high-volume printing, controlling color difference, is a very important issue for plastic flexible packaging printing enterprises. First, the ink Ink is one of the main factors determining the color consistency of a print. The ink itself also has the same batch color difference and chromatic aberration between different batches, which is an important indicator reflecting the quality of the ink. To solve the problem of chromatic aberration of plastic gravure, it is first necessary to select an ink with stable quality and no deviation in hue. It is best to use the same batch of ink (the best one-time modulation when preparing the spot color ink) for a batch of prints, because it is difficult to ensure that the hue is different for different batches of ink. If the ink hue deviation is too large, it is difficult to control the consistency of the printing ink by other methods, especially when printing the layered version. Second, the amount of ink added to the ink tank each time during the printing process is required to keep the new ink added frequently. Especially for a pattern with a small amount of ink, if the amount of ink applied is too much at one time, the ink will be oxidized and become old after being exposed to the air for a long time, for example, the long black ink is gray, and the new ink is not black; The long red ink will turn dark red, not as bright as new ink. In the printing process, the volatilization speed of the mixed solvent used in the ink is strictly controlled. When the volatilization speed is too fast, the transfer rate of the ink may be lowered, thereby affecting the color of the printed product. In addition, when using the two-component ink, it should be fully stirred and less matched. Otherwise it is difficult to maintain the stability of the ink viscosity, and may also cause other printing failures. Second, the scraper The contact position, angle and pressure of the scraper and the plate cylinder have a great influence on the ink color of the print, especially the light of the shallow layer, so the ideal state is that the scraper is in the same position from beginning to end. However, for various reasons, the position, angle and pressure of the blade have to be adjusted during the printing process, so we must understand the influence of the change on the color of the printed product and take corresponding measures. The contact position of the scraper with the plate cylinder determines the distance between the contact point of the knife and the plate and the imprinting point. The length of the distance should be adjusted according to the printing speed, ink viscosity, cell depth, and plate quality. In general, the longer the distance, the greater the degree of drying of the ink in the cells and the lower the transfer rate of the ink. In terms of its effect on the printing effect, it is equivalent to the partial withdrawal of the ink color. At the same time, this distance is also a test of ink adaptability. Conversely, when the distance is short, the transfer rate of the ink is relatively high, and at the same time, some fine lines on the plate are transferred to the printing material. The blade angle is the angle between the tangent of the contact point of the doctor blade and the plate cylinder and the blade. Increasing the blade angle makes it easy to scrape the ink on the plate to make the image clear, but it may also cause the ink layer to be too thin, the ink film to have poor gloss, and the like, and it is easy to damage the plate cylinder. Conversely, the blade angle is reduced, the ink layer is thickened, and the print gloss is good, but the corners of the image are easily blurred. The blade pressure also has a certain influence on the ink color. When the pressure becomes large, the ink color becomes shallow; when the pressure becomes shallow, the ink color of the printed product tends to become darker. Third, the plate cylinder The influence of the plate cylinder on the consistency of the ink color is mainly reflected in the following aspects: 1. Blocking: Blocking is caused by blockage of the cells (cured material in the ink, high-viscosity or insoluble matter of foreign matter, etc.) and causes a decrease in the transfer rate. At this time, the amount of ink transferred is reduced, thereby affecting the hue. When the blockage occurs, use a solvent or a special cleaning agent (use the general decontamination powder to easily cause other failures) to clean the plate cylinder, and take corresponding measures for the cause of the blockage to restore it to normal. There are many factors influencing the blockage. In addition to the chemical changes caused by the use of two-component inks, which cause chemical changes, the factors are insoluble. Other reasons can be summarized as drying the ink on the plate, mixing impurities, and making the plate quality low. factor. In addition, if water or other types of ink are mixed into the ink during the printing process, the fluidity of the ink will be affected, resulting in re-agglomeration of the pigment, which may also cause blockage failure. In addition, the plate cylinder should be inspected in detail before printing. If the plate cylinder adheres to oil stains, etc., a printing failure similar to the jamming is produced at the time of printing. 2, the wear of the plate cylinder When the printing quantity of the printed product is large, the printing plate cylinder is worn to a greater extent, and the printing ink color changes, and generally tends to become lighter (because the cell is shallower and the amount of ink is reduced). Therefore, after a certain number of prints, it is necessary to re-plate. Although the cylinder of the plate cylinder is lighter, although the color adjustment can be maintained through other process adjustments, the value of the re-plating plate will be lost after over-use, and only the plate is re-plated. The plate cylinder may also experience various failures and damages during use. Since there are many influencing factors in the plate making, it is almost impossible to completely repeat the original plate making process conditions during the re-plate making, so that it is difficult to obtain the same printing effect even after the same printing conditions even after the re-plate making. In order to solve this problem, if it is a large print batch and a frequently printed job, it can be considered by making two sets or even multiple sets of solutions. 3, plate design and color management The influence of the printing and finishing processes must be taken into account when designing the plate. For example, the color of some dot areas is very easy to level and level, and it should be handled well when making plates. Many plate-making companies have begun to use color management software, which has played a positive role in improving the quality of color reproduction. Fourth, printing conditions and environment In the printing process, the color of the ink film mainly depends on the concentration and transfer rate of the ink. For a specific substrate and a specific ink, the concentration of the ink is relatively fixed, and the transfer rate depends on factors such as ink viscosity, dryness, and mesh condition, as well as printing speed, printing pressure, blade pressure, and blade. The influence of factors such as position, blade angle and environmental conditions (temperature and humidity). It should be pointed out here that the degree of influence on the highlights, shadows and midtones of the printed products is different when these conditions change. 1. The viscosity and drying speed of the ink change. Changes in ink viscosity can directly affect the color of the print. When the viscosity is high, the color density is relatively high, whereas when the viscosity is low, the color density is relatively low. This effect is sometimes very obvious and must be given high priority. According to the requirements of the printing process, the viscosity of the ink should be moderate, the viscosity is too large, which is not conducive to the transfer of the ink, and the paste phenomenon is easy to occur; the viscosity is too small, the electrostatic phenomenon is easy to occur, and the control of the ink color is not favorable. The change in ink viscosity has a subtle effect on the flow area resulting from the flow of ink or the flow of dots, especially in multicolor printing. Therefore, when the printing speed is constant, the viscosity of the ink is required to be consistent from beginning to end, and it is preferable to use an automatic viscosity controller. When the ratio of the solvent in the ink changes, the drying speed of the ink changes, which in turn affects the transfer rate of the ink and the color of the print. For some inks that are used in a small amount, after being placed in the ink tank for a period of time, due to the automatic evaporation of the solvent, not only the viscosity of the ink but also the ratio of the solvent and the volatilization speed are affected, so the solvent should be replenished in time. 2. Changes in ambient temperature and humidity If the room temperature and the liquid temperature of the ink change drastically, the state of ink migration will change and the color tone will change accordingly. This is because temperature changes affect the viscosity of the ink. At the same time, the high temperature and low temperature weather will have a significant impact on the ink transfer rate of the highlights. Therefore, when printing high-end products, the temperature and humidity of the printing workshop should be controlled anyway. In addition, when using ink in winter, it is necessary to preheat it in advance to reduce the temperature change of the ink itself. 3. Separation of synthetic colors This phenomenon is apt to occur in a mixture of light colors and a mixture of colors such as organic pigments and inorganic pigments. In particular, when the ink in the ink tank does not flow, the precipitation promotes the separation of the synthetic color, so care should be taken to make the ink circulation smooth. Further, if the stirring is insufficient, the concentration of a certain color tends to increase as the printing progresses. Therefore, the ink is sufficiently stirred by a machine such as a dissolving machine or the like before the main printing. 4, the deterioration of the ink makes the color deterioration Due to long-time printing, the solvent component of the ink changes, or the moisture in the air is mixed into the ink to cause the ink to deteriorate, and the color development is deteriorated. In order to prevent a drop in ink temperature due to heat of vaporization, a slow drying solvent may be used in combination. In high temperature and high humidity weather, a certain amount of water may be mixed into the ink. When an abnormality occurs, new ink should be replenished or replaced. The used ink that has been used many times should be filtered or discarded regularly due to the incorporation of many dust. . 5, other printing conditions Printing discoloration occurs due to the coincidence of the dots and the irregular wind blowing on the layout, or the change in printing speed and drying speed. Fifth, the impact of post-press processing 1. Changes in post-press processing Different post-press processing (such as extrusion compounding and dry compounding) also has a certain influence on the hue of the printed product. At the same time, the extrusion of the composite high temperature sometimes causes a change in the pigment. Further, when heat sealing is performed at a temperature of 200 ° C or higher, the hue of the heated portion may become deep, because the heating colorant is melted, and microcrystals are formed upon cooling to cause recrystallization, and the coloring power is increased. 2. Changes in substrate after printing Changes in the substrate after printing, such as aluminum layer changes in the aluminized film, directly affect the overall hue. Of course, the color cast of the printed substrate will also have a slight effect on the overall hue. 3. Photochemical reaction When the ink coloring agent has poor light resistance and weather resistance, the color of the printed product may change due to photochemical reaction. 4, the impact of the contents of the package When the content contains volatile and migratory active substances, the color of the package print may also change due to corrosion. Therefore, choose the appropriate ink (or negotiate with the ink manufacturer) according to the end use of the package. Sixth, visual inspection and color control instrument detection The customer wants the ink of the package to be highly consistent, but the result of each person's observation of the color is not exactly the same. What customers need is convincing data, that is, quantitative data of colors. Although the naked eye is good at color, it is not good at memorizing the color (if the product is not discharged together, the naked eye cannot accurately determine the color), so the naked eye is no longer considered to be a reliable guarantee for determining the color of the ink, and the instrument shows its unique importance. From the naked eye to the densitometer, colorimeter and spectrophotometer, to the current benchtop spectrophotometer, the color measurement results are more accurate, enough to make up for the human eye fatigue effect, visual persistence, visual memory and other color observation The adverse effects. Of course, it will take time to widely use color control instruments in China. As part of the color management process, color detection is an indispensable step and the first step in color management. At the same time, since the stability of color during the operation of the printing press will be affected at any time, the measurement and monitoring of color stability using the online color control device will be an important development trend. Article source address: http:// Plush Animal ,Unicorn Soft Toy,Plush Toys,Stuffed Toy Ningbo Shinegifts Import&Export Co., Ltd. , https://www.shinegifts.com