engleski

Defining the properties of fountain solution depending on type of surface active substance

The most important role of the fountain solution is to quickly cover nonprinting areas of the printing plate in a thin layer. To enable this function, in fountain solutions must be added surface active substances, which will decrease the value of surface tension of solution in which it is added. The goal of this research was to determine how the type of surface active substance changes physical and chemical properties of fountain solution in which they are added. Two types of fountain solutions were prepared for the research. Both were prepared from deionised water in which addition that give solution pH stability and defined conductivity were added. Afterwards, two types of samples were made with addition of defined surface active substance in volume fraction from 0 to 10 percent. To define physical and chemical properties of prepared fountain solutions, pH value, conductivity and surface tension were measured. Finally, to determine interaction between samples of solution and printing plate, contact angle was measured. Conventional printing plate was used in this research. Obtained results showed that both solution types have similar behaviour of the pH value and conductivity for all volume fractions of surface active substances. As expected, both surface active substances cause significant decrease of surface tension and contact angle with increase of their volume friction in a solution. According to the results, the optimal ratio between fountain solution's ingredients in printing process is proposed.

offset printing; fountain solution; surface active substance; surface tension

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