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Research on the application of high-speed rotary offset printing fountain solution (Part 1)

[Abstract] this paper expounds the composition of high-speed rotary offset printing fountain solution, maintains the relative stability of fountain solution and ink, and the method of achieving the water ink balance required by printing, and puts forward that in high-speed rotary printing, in order to ensure the good image and text information. 5. Impact speed: 2.5m/s, it has practical application value for the correct application of fountain solution and related control elements

2. Power source of electronic tensile testing machine (electromechanical Keywords: fountain solution; high-speed printing; control method; printing quality

with the rapid development of packaging and printing technology, the acceleration and improvement of informatization, the modern ei]~u direction is developing towards high-speed, multicolor, paper lightweight and computer intelligent control. The printing speed of today's commercial rotary offset press has developed from more than 300 prints/min in the past to more than 1000 prints/min now, forming High quality and high production capacity in the state of high-speed printing and low-cost operation meet the expectations and requirements of printing enterprises to improve printing quality and production efficiency. However, while creating the field of high-speed printing production, how to maintain stable operation and printing quality to ensure that the transfer of graphic information in high-speed printing can be well reproduced. The application and control of fountain solution in printing is one of the key factors affecting the ink water balance, printing quality and efficiency in the printing process

i function and composition of high-speed rotary offset printing fountain solution

i function of fountain solution

one of the characteristics of offset printing is to use the principle of oil-water repulsion to selectively adsorb ink and fountain solution on the printing plate to form image and text parts and blank parts to realize image and text reproduction. In the process of high-speed rotation ei]~u, the printing cycle is 0.08 ~ 0.045s and the imprint transfer time is 0. - 0.s based on the printing speed of 40000-80000 prints/h. In such a short ei]~u, in order to obtain printing ink with clear graphics and texts, rich gradation (hierarchy) and bright colors, it is particularly important that the fountain solution is well wetted in the blank part to prevent the ink from adhering and spreading in the non inking part. Therefore, as a fountain solution for high-speed rotary offset printing, it should have the following functions:

i) it can quickly spread on the non graphic surface of the printing plate and form a uniform water film to prevent the ink on the graphic surface from infiltrating into the non graphic surface and ensure the clarity and stability of the graphic

2) the acid and hydrophilic colloid in the fountain solution can react chemically and physically with the base metal of the non graphic part exposed due to friction, forming a new hydrophilic layer to maintain the stable hydrophilicity of the non graphic part of the printing plate

3) control and reduce the temperature of the printing plate surface. Under the condition of high-speed printing, the friction between the printing plate and the rubber drum causes high temperature, which changes the viscosity and fluidity of the printing ink and affects the printing quality. The fountain solution is volatile, which takes away heat in the volatilization, so as to effectively control and reduce the surface temperature of the printing plate

4) under the action of printing pressure and high-speed operation, keep the relative stability of fountain solution and ink, and minimize the emulsification degree of printing ink, so as to speed up the balance of water and ink required for high-speed printing

5) in use, the fountain solution cannot have any chemical reaction with the graphic part of the printing plate surface, but it has the function of cleaning the ink adhered to the non graphic part of the plate

1.2 composition of fountain solution

the fountain solution commonly used in high-speed rotary offset press (m-6oo type) is isopropyl alcohol fountain solution, which is commonly known in the industry as alcohol fountain solution. Isopropanol fountain solution is used because isopropanol is a surfactant with polarity and can combine with water molecules, which can significantly reduce the surface tension of fountain solution and increase the affinity of fountain solution for non graphic surfaces. Isopropanol fountain solution is composed of water, isopropanol, hydrophilic colloid, phosphoric acid and buffer

1.2.1 water

water is the main component in the fountain solution and the carrier of various chemical substances in the fountain solution. Due to the difference of water quality, the content and composition of impurities in the water are different, and will affect the acidity and alkalinity of the water, the surface tension of the water, as well as the printability and printing quality of the fountain solution. Therefore, the two sides have yet to reach a resonance on the details of cost and scope. Understanding and mastering the relevant knowledge of water quality is crucial to the configuration of excellent fountain solution

the difference in water quality is mainly determined by the amount of magnesium and calcium ions in the water. Generally, 1L water containing 10mg calcium oxide is called 1 degree, water with calcium oxide less than 80mg (water less than 8 degrees) is called soft water, and water higher than 8 degrees is called hard water. The higher the calcium oxide content per unit volume of water, the greater the hardness of water. In the practice of good printing with electricity, it is found that the hardness of water is large, and insoluble and greasy calcium soap will be generated in the fountain solution, resulting in sediment on the surface of printing plate, transfer blanket, embossing cylinder and water roller, which affects the transmission and development of ink and fountain solution in high-speed printing. Serious soiling fault occurs. Therefore, the ideal configuration of fountain solution for high-speed rotary offset press should have a water hardness of 5-10 degrees. If this requirement cannot be met, it can be achieved by water softening treatment. Water softening treatment methods are:

ion exchange method. Replace magnesium and calcium ions in hard water with sodium ions; Chemical division. Bicarbonate is used to remove magnesium and calcium ions in hard water

(to be continued)

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