The reason why the archive box is printed in pure black or magenta blue is that some of the pigments contained in the ink used in printing are very unstable under strong acid or alkali conditions. When the ink is in some acid or alkaline On paper, the color of the ink will fade after a period of time, causing the printed matter to lose its original luster and color.

In actual production, if the acidity of the printing paper is too strong, after the metallic ink is printed, the color of the pattern on the printed matter will gradually change from gold and silver to black, and the printed matter will lose its metallic luster. The paper we use is made of acid-free paper, and the PR paper is neutral paper of 7, which is non-corrosive to the ink, so that the handwriting printed on the file box will remain clear after many years.

The choice of printing paper for the archive box is acid-free paper. The specific manifestation of the corrosion of other paper printing on the archive box is: the acidity and alkalinity of the printing paper will also affect the pH value of the fountain solution. Normally, the fountain solution It is weakly acidic. When the pH value of the printing paper is too low, it will further reduce the pH value of the fountain solution, which will affect the drying speed of the printing ink, causing the printed matter to appear badly dried and dirty on the back.

At the same time, the excessive acidity of the fountain solution will inevitably speed up the corrosion rate of the printing plate, thereby reducing the printing resistance of the printing plate, and also destroy the printing plate dots and affect the reproduction of the printing quality. When the pH value of the printing paper is too high, that is, the alkalinity is too strong, during the printing process, the acid-base substances in the paper will continuously dissolve and transfer to the fountain solution, and neutralize with the weakly acid fountain solution. , So that the pH of the fountain solution changes. In addition, these alkaline substances will reduce the interfacial tension on the water-ink interface of the printing plate. Promote the emulsification of the ink, cause the non-graphic parts to be dirty, reduce the gloss of the printed product, and the more acidic the fountain solution such as the dark color of the ink, the greater the effect will be.