As we all know, in the offset printing process, the ink emulsification phenomenon is inevitably present. The so-called emulsification is a phenomenon in which a liquid is dispersed into another liquid that is not in phase with it. A completely non-emulsified ink is used, but absolutely no emulsification is also not feasible. Without a proper emulsification, a good offset printing cannot be achieved. Ink transfer process. The danger of over-emulsification of ink to printing is very great. When the press is stopped, we can see a thick layer of ink on the surface of the roller that resembles a network of uneven ink with burrs. This is a very obvious ink we can directly observe with the naked eye. Degree of emulsification. So what kind of harm does printing bring?
The first is that the print product has a dark color scheme, the colors are not bright, the prints are dull, the dots are badly deformed, the dots are hairy, the surroundings are not clean, the prints should be dry, the drying speed is slow, and the back of the prints is dirty and the prints are serious. Caused a large number of printing ink shades, shades of inconsistency, with victory, flower version, stencil, text is unclear, poor printing ink, resulting in printing ink ink imbalance. There are many factors that cause ink emulsification to be excessive, such as the emulsifier that often appears, the solid powder of the active material on the paper surface, the acidity and alkalinity of a filler, electrolyte, and paper. In order to reduce the occurrence of over-emulsification of ink, it is necessary to fully understand what substances are known to cause excessive emulsification of the ink.
The factors that cause over-emulsification of the ink are as follows:
1. Paper. Most of the offset paper coated paper used in our production process will have a certain amount of surface active materials and fillers. In the printing process, the dampening of the dampening solution is followed by stripping of the blanket and numerous times of rolling. As a result, those surface active substances are transferred to the ink roller by the Printing Plate, and the water fineness accelerates the emulsification speed of the ink. Offset paper has a relatively large impact, especially those with poor sizing, poor paper sealing, loose paper, and lint-free quality paper. During the printing process, the loose paper powder is peeled off by a rubber roller and transferred to the ink roller through the printing plate and mixed with the ink in the ink fountain to reduce the viscosity of the ink, destroy the water resistance of the ink, and increase the water absorption of the ink. Sexuality leads to increased emulsification of the ink.
2. Ink. The ink has high viscosity, strong water resistance, and low emulsification value. If the ink has small viscosity and strong fluidity, the inter-molecular cohesive force is reduced, and it is easy to emulsify. Like the pigment in the ink, there is residual water, and there is water resistance. The water-based emulsion is easy to emulsify, while the water-resistant is not easy to emulsify.
3. Fountain solution. There are ordinary fountain solution, non-ionic surfactant fountain solution, alcohol fountain solution, etc., alcohol fountain solution is a solution without electrolyte, alcohol due to volatilization, thereby greatly reducing the ink's emulsification value. The ordinary fountain solution in the process of use must be used to test the pH of the fountain solution to control the pH of 3 to 4.5, maintaining weak acidity. Maintain proper emulsification of the ink, but no matter what kind of fountain solution is used, the dosage should be controlled. The larger the amount, the easier it is to emulsify the ink.
4. Auxiliary materials for ink transfer, plus 6# varnish or sticking can reduce the viscosity of the ink. Increase the fluidity of ink, but also reduce the ink's water resistance, it is easy to cause the emulsification of the ink. So be sure to control the amount of printing. Try to control about 2% to 3%, and never blindly add. In addition, there are auxiliary materials such as dilute agent, white oil, maintenance oil, diluting agent, and white ink, which are all very likely to cause the emulsification of the ink. In particular, white oil and dimensional oil are most likely to cause emulsification of the ink.
5. other factors. Shop temperature, humidity, and the machine's operating speed and other factors, all have a considerable effect on the ink emulsification, such as the higher the shop temperature, the ink is more dilute, and the greater the flow, the viscosity becomes smaller, the water resistance is reduced, plus The speed of the machine, the greater the interaction force, the higher the surface temperature of the roller, the above factors can easily cause excessive emulsification of the ink, so the workshop must control the equilibrium temperature of 20 °C, the humidity is generally controlled at 55% ~ 65% Between the higher the temperature of the shop, the more easily the ink is emulsified.
In summary, we fully understand the factors that cause the ink to easily emulsify, as long as we can properly grasp the proper degree of ink emulsification, we can print clear, neatly printed, brightly colored prints.
The first is that the print product has a dark color scheme, the colors are not bright, the prints are dull, the dots are badly deformed, the dots are hairy, the surroundings are not clean, the prints should be dry, the drying speed is slow, and the back of the prints is dirty and the prints are serious. Caused a large number of printing ink shades, shades of inconsistency, with victory, flower version, stencil, text is unclear, poor printing ink, resulting in printing ink ink imbalance. There are many factors that cause ink emulsification to be excessive, such as the emulsifier that often appears, the solid powder of the active material on the paper surface, the acidity and alkalinity of a filler, electrolyte, and paper. In order to reduce the occurrence of over-emulsification of ink, it is necessary to fully understand what substances are known to cause excessive emulsification of the ink.
The factors that cause over-emulsification of the ink are as follows:
1. Paper. Most of the offset paper coated paper used in our production process will have a certain amount of surface active materials and fillers. In the printing process, the dampening of the dampening solution is followed by stripping of the blanket and numerous times of rolling. As a result, those surface active substances are transferred to the ink roller by the Printing Plate, and the water fineness accelerates the emulsification speed of the ink. Offset paper has a relatively large impact, especially those with poor sizing, poor paper sealing, loose paper, and lint-free quality paper. During the printing process, the loose paper powder is peeled off by a rubber roller and transferred to the ink roller through the printing plate and mixed with the ink in the ink fountain to reduce the viscosity of the ink, destroy the water resistance of the ink, and increase the water absorption of the ink. Sexuality leads to increased emulsification of the ink.
2. Ink. The ink has high viscosity, strong water resistance, and low emulsification value. If the ink has small viscosity and strong fluidity, the inter-molecular cohesive force is reduced, and it is easy to emulsify. Like the pigment in the ink, there is residual water, and there is water resistance. The water-based emulsion is easy to emulsify, while the water-resistant is not easy to emulsify.
3. Fountain solution. There are ordinary fountain solution, non-ionic surfactant fountain solution, alcohol fountain solution, etc., alcohol fountain solution is a solution without electrolyte, alcohol due to volatilization, thereby greatly reducing the ink's emulsification value. The ordinary fountain solution in the process of use must be used to test the pH of the fountain solution to control the pH of 3 to 4.5, maintaining weak acidity. Maintain proper emulsification of the ink, but no matter what kind of fountain solution is used, the dosage should be controlled. The larger the amount, the easier it is to emulsify the ink.
4. Auxiliary materials for ink transfer, plus 6# varnish or sticking can reduce the viscosity of the ink. Increase the fluidity of ink, but also reduce the ink's water resistance, it is easy to cause the emulsification of the ink. So be sure to control the amount of printing. Try to control about 2% to 3%, and never blindly add. In addition, there are auxiliary materials such as dilute agent, white oil, maintenance oil, diluting agent, and white ink, which are all very likely to cause the emulsification of the ink. In particular, white oil and dimensional oil are most likely to cause emulsification of the ink.
5. other factors. Shop temperature, humidity, and the machine's operating speed and other factors, all have a considerable effect on the ink emulsification, such as the higher the shop temperature, the ink is more dilute, and the greater the flow, the viscosity becomes smaller, the water resistance is reduced, plus The speed of the machine, the greater the interaction force, the higher the surface temperature of the roller, the above factors can easily cause excessive emulsification of the ink, so the workshop must control the equilibrium temperature of 20 °C, the humidity is generally controlled at 55% ~ 65% Between the higher the temperature of the shop, the more easily the ink is emulsified.
In summary, we fully understand the factors that cause the ink to easily emulsify, as long as we can properly grasp the proper degree of ink emulsification, we can print clear, neatly printed, brightly colored prints.
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