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In the process of packaging bag printing, the ink film color of color printing packaging bag mainly depends on the ink concentration and transfer rate. For some specific substrates or specific working inks, the concentration of working ink is relatively fixed. The transfer rate depends on the viscosity of the ink, the dryness of the working ink and the mesh condition of the layout, as well as the printing speed, position of the scraper, printing pressure, scraper pressure, scraper angle and environmental premise. What needs to be noted here is that these elements will have different effects on the high light, dark tone and intermediate tone of the printed matter when they change.
1. Temperature and humidity change
Room temperature, ink temperature such as a substantial change, the flow state will change, color will change. This is due to temperature changes affect the ink viscosity. At the same time, the image of high temperature and low humidity drying scene has a significant impact on the ink transfer rate of high gloss parts. Therefore, when printing high-end products, no matter how to control the temperature and humidity in the printing workshop. In addition, the use of ink in winter to preheat to reduce the temperature of the ink itself.
2. Separation of synthetic colors
This kind of scene is easy to happen in light color and the mixture of various colors, such as organic color and inorganic pigment. In particular, ink tray ink activity is too slow, precipitation will promote the separation of synthetic color, so we should pay attention to make ink circulation smooth. In addition, if the mixing is not sufficient, the concentration of a certain color will increase with the printing process. Therefore, mechanical or other methods such as dissolving machine should be used for sufficient mixing before formal printing.
3. The deterioration of ink results in deterioration of color
As a result of long-time printing, ink solvent composition changes, or moisture in the air mixed with the ink, resulting in ink deterioration, color deterioration.
In order to prevent the temperature drop caused by the heat of vaporization, slow drying solvent can be used. In high temperature and humidity, there may be a certain amount of moisture mixed into the ink, so in case of abnormal, new ink should be added, or all changed. The residual ink that has been used many times due to mixing a lot of dust should be filtered or abolished on schedule.
4. The working viscosity and drying speed of the ink are changed
The working viscosity of the ink can directly affect the color of the printed matter. When the viscosity is high, the color concentration is relatively high, on the contrary, the color concentration is relatively low when the viscosity is low. This kind of influence is sometimes clear and obvious, which must be paid great attention to. Due to the requirements of printing process, the working viscosity of ink should be moderate. When the working viscosity of the ink is too large, it is not conducive to the transfer of ink, easy to produce paste version scene. When the working viscosity of the ink is too small, the color of the printed matter is easy to appear electrostatic phenomenon, which is not conducive to the control of ink color.
The change of viscosity has a subtle effect on the transfer area caused by ink transfer or dot movement, especially in multicolor printing. Therefore, when the printing speed is certain, the viscosity of the ink should be kept consistent from beginning to end. It is best to use the viscosity automatic controller.
When the proportion of solvent in the ink changes, the drying speed of working ink will change, which will affect the transfer rate of ink and printing color. On some less used ink, in the ink tank after a period of time, due to the natural volatilization of solvent, not only will affect the ink viscosity, but also affect the solvent ratio and volatilization speed, so timely supplement solvent.
Dongguan Beite packaging materials Co., Ltd. is a large-scale company specializing in the production of food grade composite packaging. It is a professional manufacturer of composite packaging bags. It uses new equipment to produce packaging bags and roll films, providing comprehensive, environmental protection and safety packaging services for the market. The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries. We uphold the integrity of cooperation, good quality, good service business philosophy, won the industry's approval, products sold to all over the world; welcome friends from all walks of life to inquire, visit our factory to investigate guidance and business negotiations.