Paper pH refers to the acidity and alkalinity of paper. The pH value is originally an indicator of the acidity and alkalinity of the aqueous solution, and the paper is solid, so the pH value of the paper is essentially the pH value of the aqueous solution soaked in the paper.
The acidity and alkalinity of paper raw materials should be neutral, but due to the treatment of various solutions in the papermaking process, the residual ions cannot be completely neutralized, so it appears acidic or alkaline.
The pH value of paper affects the quality of printing. During the offset printing process, the pH value of the fountain solution will be affected by the pH value of the paper. During the printing process, the paper is soaked by the fountain solution, and it passes back through the blanket to the bucket to change the pH value of the fountain solution. The pH value of the fountain solution changes to emulsify the ink, which has a greater impact on the UV ink. After the ink is emulsified, ink flying and sticking are easy to occur.
When the paper is acidic, the oxidative conjunctival effect of the ink is inhibited, and the drying time of the imprint becomes longer, which seriously affects the drying of the ink.
When the paper is alkaline, the printed matter will turn yellow and become brittle in the future, which will also affect the color of the printed matter and reduce the life of the paper.
