1. the impact of ink emulsification on printing
 
If the ink emulsification is just right, it indicates that the ink is in a relatively balanced state, creating good printing conditions for offset printing, graphic ink can realize the transfer of ink, so as to obtain the printing effect of smooth, neat, clear images, rich layers, bright colors and saturation, and ensure the accuracy of overprinting and promote the drying of printed matter. At the same time, make sure that the blank parts of the non-print area are clean and tidy. Therefore, whether the emulsion of ink can be correctly mastered and controlled is the key to ensure the balanced and stable printing quality of ink. If the ink is not properly mastered, resulting in excessive emulsification of ink, it will inevitably lead to the imbalance of ink and have a bad impact on the printing quality. In practice, if the ink is not properly mastered, it is easy to have excessive emulsification of ink, which is of great harm to the printing quality.
 
Excessive emulsification of the ink means that there are too many tiny droplets dispersed in the ink, which exceeds a certain proportion, and the nature of the ink changes immediately, such as the color becomes lighter, the color saturation decreases, the viscosity decreases, the adhesion weakens, etc., which causes the instability of the process and the quality of the print. For example: the gray balance is broken, the color is not restored, the color of the printing is gray, the level is not clear; The ink transfer deteriorates, the ink color fluctuates, and the ink color difference before and after the product is large; Easy to appear floating dirty, paste plate and other process failures, blot drying performance is greatly slowed, easy to cause the back sticky dirty, etc. Therefore, to control the printing quality, we should try to prevent the appearance of excessive emulsification of ink.
 
 
2. the cause and prevention of excessive emulsification of ink
 
The factors that cause excessive emulsification of ink are many, mainly paper, moistening liquid, ink, diluting agent and desiccant, etc. Therefore, to avoid excessive emulsification of ink should be appropriate for different influencing factors, and prevent it from happening.
 
（1）Paper factor
Because paper such as some offset paper, coated paper, whiteboard paper, the surface of the adhesive, paint or other fillers contain more or less some surface active substances, they have a certain water solubility, if combined with the paper is not strong, in the printing process by wetting the plate liquid and through the rubber sheet extrusion and stripping, These surface active substances fall off and are transferred to the ink roller and bucket through the printing plate, and are fused with the ink, so that the viscosity of the ink is greatly reduced, the water absorption is increased, the water resistance is affected, and the ink emulsification is excessive. The larger the surface moisture, the more dissolved filler, the more serious the emulsification; The paper with bad sizing, loose paper, and the more serious the powder and hair loss, the easier it is to over-emulsify.
 
 
 
Preventive measures: ① Use better quality paper to fundamentally eliminate excessive emulsification of ink caused by paper; ② Wash the rubber and printing plate frequently, and remove the dropped paper powder and paper wool in time; ③ Add a small amount of additives to the ink, and reduce the water content of the page and reduce the pressure of the water roller to reduce the paper depowder.
 
（2）Moistening fluid factor
The water film on the surface of the plate, under the extrusion of mechanical force, forms tiny droplets dispersed into the ink, causing the ink to emulsify, so the water volume of the plate liquid is too large, the plate water film is too thick, the water spread along the ink roller increases, after the roller, the ink roller extrusion, it promotes the ink emulsion acceleration and excessive emulsification. The greater the amount of water, the thicker the water film, the smaller the PH value, and the more serious the excessive emulsification.
 
Preventive measures: ①Control the water quantity of the moistening liquid, reduce the ink amount and reduce the water quantity under the condition that the printing plate is not dirty and the imprinting meets the quality requirements of level, density, color, etc.; ② Control the proportion of moistening solution, PH value should not be too small, it is best to use alcohol moistening solution as far as possible.
 
（3） Ink factor
Ink viscosity is the main factor to produce emulsification, regardless of the viscosity, can produce different degrees of emulsification. Ink viscosity is large, its molecular cohesion is large, water resistance is strong, emulsification value is small; On the contrary, if the ink viscosity is small, the fluidity is strong, the cohesion between molecules is small, and the water resistance is poor, it is easy to emulsify. Under normal circumstances, ink viscosity is inversely proportional to emulsification, and fluidity is proportional to emulsification. The different water repellent ability of the pigment itself will also cause changes in the emulsification value of the ink, for example, the water resistance of black ink and red ink is better than that of green lotus and peacock blue ink, and the emulsification value is also smaller.
 
Preventive measures: ① choose ink with good water resistance; ② For easily emulsified ink, increase the viscosity of the ink, ③ replace the new ink.
 
（4） Diluent and desiccant factors
Commonly used diluent mainly have diluent, white oil, white ink, vitamin oil, etc., which diluent is an amphoteric oxide, strong moisture absorption, emulsification value is larger, the emulsification value of white oil is also larger, easy to cause the emulsification of ink, if these diluents are added to the ink, the ink emulsification must be accelerated; Drying agents such as white dry oil, red dry oil, its emulsification value is large, adding an appropriate amount of drying agents can speed up the drying of ink, but if excessive addition, it will reduce the drying speed of ink, and will make the ink emulsification worse.
 
Preventive measures: To add diluent or desiccant according to the specific situation, can not blindly add, try to control within a certain amount, generally about 2%-3%, not more than 5%.
 
（5）Other factors
Other factors caused by excessive emulsification, such as workshop temperature, humidity, speed and water roller, ink roller pressure and other factors, will also have a certain impact on ink emulsification. For example: the higher the temperature of the workshop, the higher the surface temperature of the roller and ink roller, the thinner the ink, the greater the fluidity, the smaller the viscosity, the weaker the water resistance, if the speed is high, the interaction force is large, these factors have a strong catalytic effect on the excessive emulsification of ink, the greater the workshop temperature, the easier the ink emulsification.
 
Preventive measures: ① try to install air conditioning in the workshop, control the temperature of the workshop between 20℃-26℃, and control the humidity between 53% and 65%; ② Pay attention to adjust the pressure of the water roller and the ink roller to make it within the appropriate range to ensure the smooth water and ink delivery; ③ When idling, the water supply and ink supply should be turned off to avoid large water and ink to accelerate the emulsification of ink.
 
The factors that affect the emulsification of ink are many, and in many cases, the reasons for excessive emulsification of ink are often several factors that work together, such as: small graphic area, less ink consumption, ink contact with water for a long time is easy to emulsify, if the ink's water resistance is poor, the amount of water is too large, it is more prone to excessive emulsification of ink.
 
Therefore, for the ink emulsification problem, we should analyze and exclude one by one from many aspects, we must establish the idea of prevention, focus on prevention, in addition to the good quality of raw materials, usually also to develop good working habits, standardize process operations, such as: Do a good job of "three flat" and "three diligent" work, discover and solve problems in time, and pay attention to accumulate experience, grasp moderate ink emulsification as much as possible, control the balance of ink and wash, and print out high-quality prints with clear outlets, distinct layers and bright colors.

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