Why is water-based ink inseparable from solvents?
author: Uvink
2023-03-23
A solvent is a liquid that can dissolve other substances. In printing inks, solvents are used to
dissolve resins and greases, etc. The molecular structure of solvents is much simpler than that
of resins, and they are generally organic compounds with much smaller molecular weights.
The ability of the solvent to dissolve the selected resin and oil, and the ability of the solvent to
release the resin. The solubility of the solvent is related to the polarity of the solvent and the solute.
According to the "similar miscibility principle", that is, both the solvent and the solute are polar
substances, and the dissolution effect is often better; on the contrary, if the solvent and the solute
are non-polar substances, the dissolution The effect is also better. So knowing whether the solute
is polar or non-polar helps a lot in choosing the right solvent.
Solvents, such as surfactants, preservatives, and defoamers, are still inseparable from ink
formulations. The resin amination process requires the addition of organic amines, which are also
solvents. At present, when the domestic printing industry uses paper gravure ink, because the ink
dries too slowly, a large amount of alcohol is added to the ink. It is hoped that with the volatilization
of the alcohol, the water can be taken away, and the solvent volatilization can be used to help dry.
It seems that it is even more inseparable. open solvent.
Solvents in inks can be divided into main solvents, auxiliary solvents, diluents, and active solvents.
From the perspective of the solubility of solvents on resins, solvents can be divided into three types:
active solvents, inert solvents, and thinners. The active solvent has the strongest dissolving power.
The inert solvent has the strongest dissolving power. The diluent has no dissolving power to the resin,
but it can be mixed with the other two solvents to play a dilution role. The volatilization speed of
the solvent in the ink not only determines the drying speed of the ink, but also directly affect the
printability. Therefore, it is very important to use a solvent with a suitable volatilization
rate to adjust the ink.
The solvent content of ink does not exceed 5%, which is the bottom line of whether ink can truly
meet environmental protection requirements. The role of co-solvent is only to help the film-forming
resin to form a film and help improve the quality of the water-based ink film. If it is used without restriction,
the design strength of the water-based ink film will be destroyed, and the ink will change from an
environmentally friendly product to a problematic product that also needs to increase the atmospheric
sewage treatment device, which is not worth the candle. There is nothing wrong with adding a solvent to
ink, because the ink under the current conditions is an ink that is formed by a water-based emulsion
resin, and it is indeed inseparable from a solvent.
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