Ink itself is not light-resistant, but faded ink will fade after illumination, and discoloration is inevitable. All inks will fade and change color in different degrees after illumination. Light-colored ink will fade after long-term exposure, and the discoloration is very serious. Yellow, magenta and green fade faster, while cyan, blue and black fade slower.
Principle of photosensitive seal
Photosensitive technology refers to the method of making seals by using the photosensitive characteristics of photosensitive materials. Special photosensitive material is a kind of ultrafine bubble material, and its surface pore size is very small, with an average pore size of less than 30 microns. It has the characteristics of oil storage, oil seepage and light flash melting. Photosensitive materials can absorb light energy and convert it into heat energy under strong light irradiation. The darker the color, the more energy they absorb.
During exposure, the surface of the photosensitive material instantly absorbs a large amount of light energy, and then the temperature rises rapidly to reach the melting point. After flashing, the surface melt temperature drops rapidly, forming a film with a certain thickness and strength, which plays the role of sealing the hole and closing the hole, and isolating the penetration of ink. This is the principle of photosensitive seal imaging.
Using this characteristic of photosensitive material, the seal is printed on sulfuric acid paper or laser film with light transmission characteristics by laser printer, and then covered with photosensitive material and exposed in an exposure machine. Because the seal itself is black and cannot transmit light, the photosensitive material covered on the seal can still store oil and leak oil without being illuminated, while other parts cannot leak oil because of being solidified by illumination, thus realizing the manufacture of the seal.