Resistance Of Organic Pigments in Inks - Solvent Resistance

According to the definition of organic pigments, organic pigments should not dissolve in all their connecting materials, which usually contain organic solvents. If the pigment has a high solubility in the connecting material, it will experience problems such as crystallization, flocculation, and foaming in the ink film, which will affect the performance of the entire ink film. Especially when organic pigments have a high solubility in the connecting material system they are used in, there will be precipitation of organic pigment particles during use, which will have a negative impact on the quality of the ink.

The factors that have a significant impact on the solubility of pigments include not only the chemical structure of organic pigments themselves, but also the solubility properties, particle size, and temperature of organic pigments. The stronger the polarity of a solvent, the stronger its ability to dissolve organic pigments, and vice versa. The most commonly used method for determining the solvent resistance of organic pigments is to put a certain amount of organic pigments into a long strip of filter paper bag, then completely immerse in a certain amount of organic solvent, soak at room temperature for 24 hours, take out the filter bag, observe the color change of the organic solvent, and use the intensity of the color change in this solution as an indicator of the fastness of organic pigments to this organic solvent.