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In the printing process of the packaging bag, the color of the ink film of the color printing package mainly depends on the concentration and transfer rate of the ink in the printing work. For some specific substrates or specific working inks, the working ink concentration is relatively fixed, and the transfer rate depends on factors such as the viscosity of the ink, the dryness of the working ink, and the condition of the mesh of the plate. It is affected by factors such as printing speed, blade position, printing pressure, blade pressure, blade angle and environmental premise. It should be noted here that these elements will have different effects on the highlights, shadows and midtones of the printed matter when they change.
1, temperature and humidity changes
When the liquid temperature of the ink is changed at room temperature, the flow state changes and the color tone changes. This is due to temperature changes affecting the viscosity of the ink. At the same time, the high-temperature and low-humidity dry scene image will have a significant impact on the ink transfer rate of the highlight portion. Therefore, no matter how to control the temperature and humidity of the printing workshop when printing high-grade products. In addition, when using ink in winter, it is necessary to preheat in advance to reduce the temperature change of the ink itself.
2. Separation of synthetic colors
This kind of scene is prone to occur in various colors and mixed colors such as light colors and organic colors and inorganic pigments. Especially when the ink in the ink tray is too slow, the precipitation will promote the separation of the synthetic color, so it is necessary to pay attention to make the ink wheel flow smoothly. In addition, if the stirring is insufficient, the concentration of a certain color is increased with the progress of printing, so that sufficient stirring should be carried out by using a mechanical means such as a dissolving machine or other methods before the printing.
3, the ink deteriorates and the color becomes worse
Due to long-time printing, the ink solvent composition is changed, or the moisture in the air is mixed into the ink to cause deterioration of the ink, which deteriorates the color.
In order to prevent a temperature drop due to heat of vaporization, a slow-drying solvent can be used in combination. When the temperature is high and humid, there may be a certain amount of water mixed into the ink. Therefore, new ink should be added when the sample is abnormal, or all of the ink should be changed. The used ink used for many times should be filtered or abolished on schedule due to the mixing of a lot of dust. .
4. The working viscosity and drying speed of the ink change.
The change in the working viscosity of the ink 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 clear and must be highly valued. Due to the requirements of the printing process, the working viscosity of the ink should be moderate. When the working viscosity of the ink is too large, it is not conducive to the transfer of the ink, and the paste image is easily generated. When the working viscosity of the ink is too small, the color of the printed product is easy to cause static electricity, which is not conducive to the control of the ink color.
The change in viscosity has a subtle effect on the flow area resulting from the migration of the ink or the moving method of the dots, especially in multi-color printing. Therefore, when the printing speed is affirmative, 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 is changed, the drying speed of the working ink is changed, which in turn affects the ink transfer rate and the printing color. For some inks with a small amount of use, after using for a period of time in the ink tank, due to the natural volatilization of the solvent, not only will the viscosity of the ink be affected, but also the ratio of the solvent and the volatilization speed, so the solvent should be added in time.
Dongguan Bite Packaging Materials Co., Ltd. is a large-scale company specializing in the production of food-grade composite packaging. It is a professional composite packaging bag manufacturer that uses new equipment to produce packaging bags and film rolls to provide comprehensive, environmentally friendly and safe packaging services for the market. The company produces composite bags, film, fruit bags, aluminum foil bags, nozzle bags, stand-up bags, zipper bags, anti-static bags, shaped bags, etc., suitable for food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products, etc. Internal and external packaging for various industries. We adhere to the business philosophy of good faith cooperation, high quality and considerate service, and have been recognized by the industry. Our products are sold all over the world. Welcome friends from all walks of life to inquire, visit our factory for inspection and business negotiation.