The fountain solution containing isopropyl alcohol (IPA) is widely used in printing plants,titanium Dioxide. This fountain wave liquid can easily control the ink balance and ensure the printing quality. This fountain solution usually contains 10% to 15% isopropyl alcohol, 80% water, and 5% other additives,pvc resin. After adding isopropyl alcohol to the fountain solution, there are the following advantages:
1. It can effectively reduce the wheat flour tension of fountain solution. When the IPA content is 10% to 15%, the surface tension of the dampening solution can reach an ideal level of about 40 xlo-3N/m. The smaller the surface tension of the fountain solution is, the more favorable the water is to quickly form a water film on the non-graphical part of the PS plate to reduce water consumption. Figure 1 is added in the fountain solution! After IPA or ethanol, the static surface tension of the solution varies with alcohol concentration. Among them, Series 1 is the static surface tension curve with the change of IPA, Series 2 is the static surface tension with ethanol concentration curve. Therefore, ifPA's ability to reduce the static surface tension is stronger than that of ethanol, ie, at the same alcohol concentration, the static surface tension of the IPA fountain solution is smaller than that of dihexanol. Therefore, the amount of IPA added to the fountain solution may be less than the amount of diol (usually 12% - 20% of ethanol).
2. IPA volatilizes quickly at room temperature and leaves no residue. The rapid volatilization can take away heat, which is conducive to the reduction of the surface temperature of the printing plate and the stability of the ink temperature on the printing plate, so as to maintain the stability of the ink rheological properties.
3. Adding IPA to the fountain solution increases the viscosity of the fountain solution (see Figure 2). The increased viscosity of the fountain solution can make the water film transfer more efficient and the ink balance is easier to grasp. However, yes. At present, in Western developed countries, the amount of alcohol in the fountain solution is greatly reduced. This is considered from the perspective of the law and the user: First of all, it violates the requirements of the VoC law on the emission of organic substances, and the VoC law is extremely strong for the printing industry. Targeted. Second, IPA is a flammable substance. Its flash point is only 11.7 °C, which is usually lower than room temperature. Its storage and use are very strictly limited. The vapor concentration of IPA is usually high and harmful to the health of workers. Because IPA is in the fountain solution. Evaporation continuously requires constant replenishment in the enamel liquid. The actual consumption of IPA is much higher than the expected consumption, and therefore, it is not economical from a financial point of view.
Based on the above reasons. Diethylene glycol solution was used as a substitute in the past. However, it failed due to problems with its use safety. Newer chemicals are now commonly used instead of alcohol. However, it is very difficult for substitutes to have I! The advantages of PA. The first is that IPA evaporation speed is fast. The effect of lowering the plate temperature due to evaporation is difficult to achieve with other chemicals. The rheological properties of the ink are very sensitive to temperature. Therefore, it is not feasible to add alcohol without alcohol in the liquor. Unless the ink formulation is improved.
At present, the surface tension is reduced by adding a non-ionic surfactant in some fountain solution. However, the molecular weights of currently used surficial molecules (usually more than several hundred) are far greater than the molecular weight of IPA (60). Compared with IPA, they cannot move rapidly in solution (in aqueous solution, from aqueous solution). Internal movement to the surface of the aqueous solution takes about 1 second.) Therefore, in the static surface tension measurement, that is, the equilibrium surface tension, it can significantly reduce the surface tension (down to about 40 xlo-3N/m). However, in the measurement of the dynamic surface tension, the surfactant molecules can hardly reduce the surface tension because the surfactant molecules do not adsorb onto the surface of the solution. Even in the measurement of dynamic surface tension, IPA can significantly reduce the surface tension. Measuring the dynamic surface tension of the fountain solution reflects the real process in the case of high-speed printing presses. Therefore, a lot of work needs to be done to find substitutes for IPA.
Beijing Institute of Printing Zhou Zhen Zhao Yinshu
