How to control the stability of plastic gravure pr

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How to control the stability of plastic gravure ink printing

in the production process, the color of the ink film mainly depends on the concentration and transfer rate of the working ink. For a specific substrate and a specific working ink, the concentration of the working ink is relatively fixed. The transfer rate of the working ink depends on its own viscosity, the number of dry revolutions is about 1400 revolutions per minute, the dryness and the condition of the printing plate hole. At the same time, it is also affected by factors such as printing speed, printing pressure, scraper pressure, scraper position, scraper angle, environmental temperature and humidity

(1) ink color

the printing ink color is mainly determined by the color of the selected ink. To solve the color difference problem of plastic gravure printing, we must first choose the ink with stable quality, no color deviation or small deviation. It is best to use the same batch of ink for a batch of printing materials, because the color of different batches of ink may also be different. If the ink color is biased, the shape difference between the clamping part at the end of the sample and the chuck is too large, it is difficult to control the consistency of the alarm of the printing ink buzzer through other methods, especially when printing. In the preparation of spot color ink, it is best to modulate enough at one time to facilitate the stability and consistency of ink color. In the printing process, the amount of ink added to the ink tray each time is less, and new ink is often added. Especially for some products with less ink, if you add too much ink at one time, the ink will oxidize and become obsolete after being exposed to the air for a long time. For example, the long-term black ink is gray, not as black as the new ink, and the long-term red ink will turn dark red, not as bright red as the new ink

(2) viscosity of ink

during the printing process, keep the viscosity of ink stable and consistent. The ideal viscosity of ink depends on the type of moving parts and printing conditions, but the color concentration of ink must be stable, because maintaining the same ink viscosity at different temperatures will cause the change of ink color concentration, thus causing the change of ink color of printed matter

(3) separation of synthetic colors

in light colors and mixtures of various colors with widely different but interrelated proportions of organic and inorganic pigments, the separation of synthetic colors is easy to occur. Especially when the ink in the ink tray is not flowing, the precipitation will promote the separation of synthetic colors, so pay attention to keep the ink circulation smooth. If possible, it is best to use the ink circulation system to ensure that the ink has good fluidity. In addition, if the mixing is not sufficient, the concentration of a certain color tends to increase with the progress of printing, so the ink should be fully stirred before formal printing

(4) printing conditions and drying conditions

printing speed and ink drying speed directly affect the ink transfer rate. Therefore, the change of printing speed and ink drying speed will inevitably cause the change of ink color. The position, angle and pressure of the scraper have a great influence on the ink color, especially the ink color of the shallow part. The ideal state is that the scraper is in the same position from beginning to end. However, due to the influence of various factors in the printing process, the position, angle and pressure of the scraper have to be adjusted. Therefore, it is necessary to understand the influence law of these changes on the color of printed matter and take corresponding measures. When the printing volume of printed matter is large, with the increase of printing volume, the degree of plate cylinder wear increases, and its printing ink color will change and tend to fade on the whole

(5) influence of post press processing

different post press processing processes (such as extrusion compounding and dry compounding) also have a certain influence on the color of printed matter. For example, the high temperature of extrusion compounding may cause changes in pigments. When heat sealing is carried out at a temperature above 200 ℃, the hue of the heated part may change. In addition, the change of post press processing substrate, such as the change of aluminum layer of aluminized film, will directly affect the overall hue

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