What is the acid, alkali, water and solvent resistance of ink? How to measure?

The acid, alkali (including detergent), water, and solvent (mainly ethanol) properties of the ink are discussed together because their measurement methods are basically the same.

In a certain sense, the determination of the acid and alkali resistance of the ink is to determine the resistance of the pigments used in the ink to these chemicals. Of course, since the measurement is to scrape the sample (or print) with ink on the paper and measure it after drying, it is actually mainly to measure the resistance of the film formed after the pigmentation of the linking material to these chemicals. .

These items for measuring ink are basically based on the purpose of application. For example, the determination of acid resistance of lithographic ink is because the ink has to pass the test of acidic offset printing solution in the process of lithographic printing. The reason for determining the alkali resistance (including detergent) of the ink is that many printed matters are exposed to alkali. For example, some pastes are alkaline and not alkali-resistant. When pasting with this paste, it may cause discoloration. Banknotes or postage stamps are often forgotten in the pockets of clothes and soaked in alkaline solutions, washed, etc. Some printed materials need to pack soap, soda and other alkaline substances. The determination of water resistance is due to two reasons. One is that the lithographic ink has passed the test of water (not referring to the emulsification of the ink when it meets water), and the other is whether the printed matter of the ink will bleed when it meets water. The determination of solvent resistance is mainly to measure the resistance to ethanol for lithographic inks and letterpress inks. Substances), if the dried ink film is not resistant to ethanol, it will damage the printed matter during glazing. In recent years, due to the emergence of plastic-coating and plastic-sticking technology for printed dramas, the requirements for ink resistance to other solvents have also been put forward. Of course, what solvent to use depends on the needs.